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£EPA

EPA/600/R-10/038A
www.epa.gov/iris

EPA's Reanalysis of Key Issues Related to
Dioxin Toxicity and Response to
NAS Comments

NOTICE

THIS DOCUMENT IS AN EXTERNAL REVIEW DRAFT. It has not been formally released
by the U.S. Environmental Protection Agency and should not at this stage be construed to
represent Agency policy. It is being circulated for comment on its technical accuracy and policy
implications.

National Center for Environmental Assessment
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, OH


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DISCLAIMER

This document is distributed solely for the purpose of pre-dissemination peer review
under applicable information quality guidelines. It has not been formally disseminated by EPA.
It does not represent and should not be construed to represent Agency determination or policy.
Mention of trade names or commercial products does not constitute endorsement or
recommendation for use.

ABSTRACT

This draft report details EPA's technical response to the key comments and recommendations
included in the 2006 NAS report, "Health Risks from Dioxin and Related Compounds:
Evaluation of the EPA Reassessment," focusing on the NAS comments regarding TCDD dose-
response assessment. After systematically evaluating the epidemiologic studies and rodent
bioassays on TCDD, this draft report utilized a TCDD physiologically-based pharmacokinetic
model to simulate TCDD blood concentrations, the dose metric used in the dose-response
analyses. The draft report develops an oral reference dose (RfD) of 7 x 10 10 mg/kg-day based
on two epidemiologic studies that associated TCDD exposures with decreased sperm
concentration and sperm motility in men who were exposed during childhood (Mocarelli et al.,
2008, 199595) and increased thyroid-stimulating hormone levels in newborn infants (Baccarelli
et al., 2008, 197059). EPA also classifies TCDD as carcinogenic to humans, based on numerous
lines of evidence, including primarily: multiple occupationally- and accidentally-exposed
epidemiologic cohorts showing an association between TCDD exposure and certain cancers or
increased mortality from all cancers and extensive evidence of carcinogenicity at multiple tumor
sites in both sexes of multiple species of experimental animals. Based on a cancer mortality
analysis of an occupational cohort (Cheng et al., 2006, 523122). EPA also develops an oral
cancer slope factor of 1 x 106 per (mg/kg-day) when the target risk range is 10 5 to 10 1. While
this draft report provides limited sensitivity analyses of several steps in the cancer and noncancer
dose-response assessment, it concludes that a comprehensive uncertainty analysis is infeasible at
this time.

Preferred Citation:

U.S. Environmental Protection Agency (U.S. EPA). (2010) EPA's Reanalysis of Key Issues Related to Dioxin
Toxicity and Response to NAS Comments. EPA/600/R-10/038A. NAS comments are published by the National
Research Council of the National Academies and available from the National Technical Information Service,
Springfield, VA, and online at http://www.epa.gov/ncea.

This document is a draft for review purposes only and does not constitute Agency policy.

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CONTENTS

LIST OF TABLES	ix

LIST OF FIGURES	xiii

LIST OF ABBREVIATIONS AND ACRONYMS	xvii

PREFACE	xxi

AUTHORS, CONTRIBUTORS, AND REVIEWERS	xxii

EXECUTIVE SUMMARY	xxvi

1.	INTRODUCTION	1-1

1.1.	SUMMARY OF KEY NAS (2006, 198441) COMMENTS ON DOSE-
RESPONSE MODELING IN THE 2003 REASSESSMENT	1-2

1.2.	EPA'S SCIENCE PLAN	1-4

1.3.	OVERVIEW OF EPA'S RESPONSE TO NAS (2006, 198441) "HEALTH
RISKS FROM DIOXIN AND RELATED COMPOUNDS: EVALUATION OF
EPA's 2003 REASSESSMENT"	1-5

1.3.1.	TCDD Literature Update	1-6

1.3.2.	EPA's 2009 Workshop on TCDD Dose Response	1-7

1.3.3.	Overall Organization of EPA's Response to NAS Recommendations	1-9

2.	TRANSPARENCY AND CLARITY IN THE SELECTION OF KEY DATA SETS

I OR DOSE-RESPONSE ANALYSIS	2-1

2.1.	SUMMARY OF NAS COMMENTS ON TRANSPARENCY AND CLARITY
IN THE SELECTION OF KEY DATA SETS FOR DOSE-RESPONSE
ANALYSIS	2-1

2.2.	EPA's RESPONSE TO NAS COMMENTS ON TRANSPARENCY AND
CLARITY IN THE SELECTION OF KEY DATA SETS FOR DOSE-
REsPONSE ANALYSIS	2-2

2.3.	STUDY INCLUSION CRITERIA FOR TCDD DOSE-RESPONSE

ANALYSIS	2-4

2.3.1.	Study Inclusion Criteria for TCDD Epidemiologic Studies	2-6

2.3.2.	Study Inclusion Criteria for TCDD In Vivo Mammalian Bioassays	2-8

2.4.	EVALUATION OF KEY STUDIES FOR TCDD DOSE RESPONSE	2-10

2.4.1.	Evaluation of Epidemiological Cohorts for Dose-Response Assessment	2-10

2.4.1.1.	Cancer	2-11

2.4.1.2.	Noncancer	2-87

2.4.2.	Summary of Animal Bioassay Studies Included for TCDD Dose-

Response Modeling	2-134

2.4.2.1.	Reproductive Studies	2-135

2.4.2.2.	Developmental Studies	2-149

2.4.2.3.	Acute Studies	2-168

2.4.2.4.	Subchronic Studies	2-176

2.4.2.5.	Chronic Studies (Noncancer Endpoints)	2-191

2.4.2.6.	Chronic Studies (Cancer Endpoints)	2-204

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CONTENTS (continued)

2.4.3. Summary of Key Data Set Selection for TCDD Dose-Response

Modeling	2-211

3.	THE USE OF TOXICOKINETICS IN THE DOSE-RESPONSE MODELING FOR
CANCER AND NONCANCER ENDPOINTS	3-1

3.1.	SUMMARY OF NAS COMMENTS ON THE USE OF TOXICOKINETICS

IN DOSE-RESPONSE MODELING APPROACHES FOR TCDD	3-1

3.2.	OVERVIEW OF EPA'S RESPONSE TO THE NAS COMMENTS ON THE
USE OF TOXICOKINETICS IN DOSE-RESPONSE MODELING
APPROACHES I OR TCDD	3-3

3.3.	PHARMACOKINETICS (PK) AND PK MODELING	3-4

3.3.1.	PK Data and Models in TCDD Dose-Response Modeling: Overview and
Scope	3-4

3.3.2.	PK of TCDD in Animals and Humans	3-6

3.3.2.1.	Absorption and Bioavailability	3-6

3.3.2.2.	Distribution	3-6

3.3.2.3.	Metabolism and Protein Binding	3-9

3.3.2.4.	Elimination	3-11

3.3.2.5.	Interspecies Differences and Similarities	3-11

3.3.3.	PK of TCDD in Humans: Interindividual Variability	3-12

3.3.3.1.	Life Stage and Gender	3-13

3.3.3.2.	Physiological States: Pregnancy and Lactation	3-16

3.3.3.3.	Lifestyle and Habits	3-17

3.3.3.4.	Genetic Traits and Polymorphism	3-18

3.3.4.	Dose Metrics and Pharmacokinetic Models for TCDD	3-18

3.3.4.1.	Dose Metrics for Dose-Response Modeling	3-18

3.3.4.2.	First-Order Kinetic Modeling	3-22

3.3.4.3.	Biologically-Based Kinetic Models	3-26

3.3.4.4.	Applicability of PK Models to Derive Dose Metrics for Dose-
Response Modeling of TCDD: Confidence and Limitations	3-42

3.3.4.5.	Recommended Dose Metrics for Key Studies	3-45

3.3.5.	Uncertainty in Dose Estimates	3-47

3.3.5.1.	Sources of Uncertainty in Dose Metric Predictions	3-47

3.3.5.2.	Qualitative Discussion of Uncertainty in Dose Metrics	3-49

3.3.6.	Use of the Emond PBPK Models for Dose Extrapolation from Rodents

to Humans	3-51

4.	CHRONIC ORAL REFERENCE DOSE	4-1

4.1.	NAS COMMENTS AND EPA'S RESPONSE ON IDENTIFYING
NONCANCER EFFECTS OBSERVED AT LOWEST DOSES	4-1

4.2.	NONCANCER DOSE-RESPONSE ASSESSMENT OF TCDD	4-6

4.2.1.	Determination of Toxicologically Relevant Endpoints	4-6

4.2.2.	Use of Toxicokinetic Modeling for TCDD Dose-Response Assessment	4-7

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CONTENTS (continued)

4.2.3.	Noncancer Dose-Response Assessment of Epidemiological Data	4-9

4.2.3.1.	Baccarelli et al. (2008, 197059)	4-9

4.2.3.2.	Mocarelli etal. (2008, 199595)	4-10

4.2.3.3.	Alaluusua et al. (2004, 197142)	4-11

4.2.3.4.	Eskenazi et al. (2002, 197168)	4-12

4.2.4.	Noncancer Dose-Response Assessment of Animal Bioassay Data	4-13

4.2.4.1.	Use of Kinetic Modeling for Animal Bioassay Data	4-13

4.2.4.2.	Benchmark Dose Modeling of the Animal Bioassay Data	4-14

4.2.4.3.	POD Candidates from Animal Bioassays Based on HED and

BMD Modeling Results	4-16

4.3.	RfD DERIVATION	4-18

4.3.1.	Toxicological Endpoints	4-19

4.3.2.	Exposure Protocols of Candidate PODs	4-20

4.3.3.	Uncertainty Factors (UFs)	4-21

4.3.4.	Choice of Human Studies for RfD Derivation	4-22

4.3.4.1.	Identification of POD from Baccarelli et al. (2008, 197059)	4-24

4.3.4.2.	Identification of POD from Mocarelli et al. (2008, 199595)	4-25

4.3.4.3.	Identification of POD from Alaluusua et al. (2004, 197142)	4-27

4.3.5.	Derivation of the RfD	4-27

4.4.	UNCERTAINTY IN THE RfD	4-28

5. CANCER ASSESSMENT	5-1

5.1.	QUALITATIVE WEIGHT-OF-EVIDENCE CARCINOGEN
CLASSIFICATION FOR 2,3,7,8-TETRACHLORODIBENZO-p-DIOXIN

(TCDD)	5-1

5.1.1.	Summary of National Academy of Sciences (NAS) Comments on the
Qualitative Weight-of-Evidence Carcinogen Classification for
2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD)	5-1

5.1.2.	EPA's Response to the NAS Comments on the Qualitative Weight-of-
Evidence Carcinogen Classification for TCDD	5-2

5.1.2.1.	Summary Evaluati on of Epi demi ol ogi c Evi dence of TCDD

and Cancer	5-3

5.1.2.2.	Summary of Evidence for TCDD Carcinogenicity in
Experimental Animals	5-10

5.1.2.3.	TCDD Mode of Action	5-10

5.1.3.	Summary of the Qualitative Weight of Evidence Classification for

TCDD	5-20

5.2.	QUANTITATIVE CANCER ASSESSMENT	5-21

5.2.1. Summary of NAS Comments on Cancer Dose-Response Modeling	5-21

5.2.1.1.	Choice of Response Level and Characterization of the

Statistical Confidence Around Low Dose Model Predictions	5-21

5.2.1.2.	Model Forms for Predicting Cancer Risks Below the Point of
Departure (POD)	5-22

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CONTENTS (continued)

5.2.2.	Overview of EPA Response to NAS Comments on Cancer Dose-

Response Modeling	5-23

5.2.3.	Updated Cancer Dose-Response Modeling for Derivation of Oral Slope
Factor	5-24

5.2.3.1.	Dose-Response Modeling Based on Epidemiologic Cohort

Data	5-24

5.2.3.2.	Dose-Response Modeling Based on Animal Bioassay Data	5-35

5.2.3.3.	EPA's Response to the NAS Comments on Choice of
Response Level and Characterization of the Statistical
Confidence Around Low Dose Model Predictions	5-50

5.2.3.4.	EPA's Response to the NAS Comments on Model Forms for
Predicting Cancer Risks Below the POD	5-51

5.3. DERIVATION OF THE TCDD ORAL SLOPE FACTOR AND CANCER

RISK ESTIMATES	5-75

5.3.1.	Uncertainty in Estimation of Oral Slope Factors from Human Studies	5-77

5.3.1.1.	Uncertainty in Exposure Estimation	5-78

5.3.1.2.	Uncertainty in Shape of the Dose-Response Curve	5-82

5.3.1.3.	Uncertainty in Extrapolating Risks below Reference

Population Exposure Levels	5-83

5.3.1.4.	Uncertainty in Cancer Risk Estimates Arising from

Background DLC Exposure	5-84

5.3.1.5.	Uncertainty in Cancer Risk Estimates Arising from
Occupational DLC Coexposures	5-85

5.3.2.	Other Sources of Uncertainty in Risk Estimates from the

Epidemiological Studies	5-86

5.3.2.1. Effect of Added Background TEQ on TCDD Dose-Response	5-88

5.3.3.	Approaches to Combining Estimates from Different Epidemiologic

Studies	5-90

5.3.3.1.	The Crump et al. (2003, 197384) Meta-analysis	5-90

5.3.3.2.	EPA's Decision Not to Conduct a Meta-analysis	5-92

6. FEASIBILITY OF QUANTITATIVE UNCERTAINTY ANALYSIS FROM NAS

EVALUATION OF THE 2003 REASSESSMENT	6-1

6.1. INTRODUCTION	6-1

6.1.1.	Historical Context for Quantitative Uncertainty Analysis	6-1

6.1.2.	Definition of Terms	6-3

6.1.3.	Key Elements of a Quantitative Uncertainty Analysis	6-6

6.1.3.1.	Quantitative Model	6-6

6.1.3.2.	Marginal Distributions over Model Parameter	6-6

6.1.3.3.	Dependence between Parameter Uncertainties: Aleatoric and
Epistemic (Uncertainty and Variability)	6-7

6.1.3.4.	Model Uncertainty	6-8

6.1.3.5.	Sampling Method	6-9

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CONTENTS (continued)

6.1.3.6. Method for Extracting and Communicating Results	6-9

6.2.	EPA APPROACHES FOR ORAL CANCER AND NONCANCER
ASSESSMENT	6-10

6.3.	HIGHLIGHTS OF NAS REVIEW COMMENTS ON UNCERTAINTY
QUANTIFICATION FOR THE 2003 REASSESSMENT	6-12

6.4.	FEASIBILITY OF CONDUCTING A QUANTITATIVE UNCERTAINTY
ANALYSIS FOR TCDD	6-15

6.4.1.	Feasibility of Conducting a Quantitative Uncertainty Analysis under the

RfD Methodology	6-15

6.4.1.1.	Feasibility of Conducting a Quantitative Uncertainty Analysis

for the Point of Departure	6-16

6.4.1.2.	Feasibility of Conducting a Quantitative Uncertainty Analysis

with Uncertainty Factors	6-19

6.4.1.3.	Uncertainty Reduction Using Quantitative Data for Species
Extrapolation	6-21

6.4.1.4.	Conclusion on Feasibility of Quantitative Uncertainty

Analysis with the RfD Approach	6-22

6.4.2.	Feasibility of Conducting a Quantitative Uncertainty Analysis for TCDD
under the Dose-Response Methodology	6-23

6.4.2.1.	Feasibility of Quantitatively Characterizing the Uncertainties
Encountered when Determining Appropriate Types of Studies
(Epidemiological, Animal, Both, and Other)	6-24

6.4.2.2.	Uncertainty in TCDD Exposure/Dose in Epidemiological

Studies	6-25

6.4.2.3.	Uncertainty in Toxicity Equivalence (TEQ) Exposures in
Epidemiological Studies	6-28

6.4.2.4.	Uncertainty in Background Feed Exposures in Bioassays	6-29

6.4.2.5.	Feasibility of Quantifying the Uncertainties Encountered
When Choosing Specific Studies and Subsets of Data (e.g.,

Species and Gender)	6-31

6.4.2.6.	Feasibility of Quantifying the Uncertainties Encountered
when Choosing Specific Endpoints for Dose-Response

Modeling	6-31

6.4.2.7.	Feasibility of Quantifying the Uncertainties Encountered
when Choosing a Specific Dose Metric (Trade-Off between
Confidence in Estimated Dose and Relevance of MO A)	6-32

6.4.2.8.	Feasibility of Quantifying the Uncertainties Encountered

When Choosing Model Type and Form	6-34

6.4.2.9.	Threshold MOA for Cancer	6-36

6.4.2.10.	Feasibility of Quantifying the Uncertainties Encountered

when Selecting the BMR	6-37

6.5.	CONCLUSIONS REGARDING THE FEASIBILITY OF QUANTITATIVE
UNCERTAINTY ANALYSIS	6-38

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CONTENTS (continued)

6.5.1.	Summary of NAS Suggestions and Responses	6-38

6.5.2.	How Forward? Beyond RfDs and Cancer Slope Factors to Development

of Predictive Human Dose-Response Functions	6-41

REFERENCES	R-l

APPENDIX A: DIOXIN WORKSHOP	A-l

APPENDIX B: EVALUATION OF CANCER AND NONCANCER

EPIDEMIOLOGICAL STUDIES FOR INCLUSION IN

TCDD DOSE-RESPONSE ASSESSMENT	B-l

APPENDIX C: KINETIC MODELING	C-l

APPENDIX D: EPIDEMIOLOGICAL KINETIC MODELING	D-l

APPENDIX E: NONCANCER BENCHMARK DOSE MODELING	E-l

APPENDIX F: CANCER BENCHMARK DOSE MODELING	F-l

APPENDIX G: ENDPOINTS EXCLUDED FROM REFERENCE DOSE

DERIVATION BASED ON TOXICOLOGICAL RELEVANCE	G-l

APPENDIX H: CANCER PRECURSOR BENCHMARK DOSE MODELING	H-l

APPENDIX I: EFFECT OF BACKGROUND EXPOSURE ON BENCHMARK-DOSE

MODELING	1-1

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LIST OF TABLES

2-1. Summary of epidemiological cancer studies (key characteristics)	2-212

2-2. Epidemiological cancer study selection considerations and criteria	2-215

2-3. Epidemiological noncancer study selection considerations and criteria	2-219

2-4. Epidemiological studies selected for TCDD cancer dose-response modeling	2-223

2-5. Epidemiological studies selected for TCDD noncancer dose-response modeling	2-228

2-6. Animal bioassays selected for cancer dose-response modeling	2-232

2-7.	Animal bioassay studies selected for noncancer dose-response modeling	2-234

3-1.	Partition coefficients, tissue volumes, and volume of distribution for TCDD in

humans	3-56

3-2. Blood flows, permeability factors and resulting half lives (VA) for perfusion losses
for humans as represented by the TCDD PBPK model of Emond et al. (2005,

197317; 2006, 197316)	3-56

3-3. Toxicokinetic conversion factors for calculating human equivalent doses from

rodent bioassays	3-57

3-4. Equations used in the concentration and age-dependent model (CADM; Aylward

et al., 2005, 197014)	3-58

3-5. Parameters of the Concentration and age-dependent model (CADM; Aylward et

al., 2005, 197014)	3-59

3-6. Confidence in the CADM model simulations of TCDD dose metrics	3-60

3-7. Equations used in the TCDD PBPK model of Emond et al. (2006, 197316)	3-61

3-8. Parameters of the PBPK model for TCDD	3-63

3-9. Regression analysis results for the relationship between logio serum TCDD at the
midpoint of observations and the logio of the rate constant for decline of TCDD
levels using Ranch Hand data	3-66

3-10. Confidence in the PBPK model simulations of TCDD dose metrics	3-66

3-11. Overall confidence associated with alternative dose metrics for cancer and

noncancer dose-response modeling for TCDD using rat PBPK model	3-67

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LIST OF TABLES (continued)

3-12. Overall confidence associated with alternative dose metrics for cancer and

noncancer dose-response modeling for TCDD using mouse PBPK model	3-67

3-13. Contributors to the overall confidence in the selection and use of dose metrics in

the dose-response modeling of TCDD based on rat and human PBPK models	3-67

3-14. Contributors to the overall uncertainty in the selection and use of dose metrics in

the dose-response modeling of TCDD based on mouse and human PBPK models	3-68

3-15. Comparison of human equivalent doses from the Emond human PBPK model for

the 45-year-old and 25-year-old gestational exposure scenarios	3-68

3-16.	Impact of toxicokinetic modeling on the extrapolation of administered dose to

HED, comparing the Emond PBPK and first-order body burden models	3-69

4-1.	POD candidates for epidemiologic studies of TCDD	4-33

4-2. Models run for each study/endpoint combination in the animal bioassay

benchmark dose modeling	4-33

4-3. Summary of key animal study PODs (ng/kg-day) based on three different dose
metrics: administered dose, first-order body burden HED, and blood
concentration	4-34

4-4. TCDD BMDL analysis (NOAEL, LOAEL, BMD, and BMDL values given as

animal whole blood concentrations in ng/kg)	4-38

4-5. Candidate points of departure for the TCDD RfD using blood-concentration-

based human equivalent doses	4-49

4-6. Qualitative analysis of the strengths and limitations/uncertainties associated with

animal bioassays possessing candidate points-of-departure for the TCDD RfD	4-53

4-7.	Basis and derivation of the TCDD reference dose	4-57

5-1.	Cancer slope factors calculated from Becher et al. (1998, 197173), Steenland et al.
(2001, 197433) and Ott and Zober (1996, 198408) from 2003 Reassessment Table

5-4	5-94

5-2. Cox regression coefficients and incremental cancer-mortality risk for NIOSH

cohort data	5-95

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LIST OF TABLES (continued)

5-3. Comparison of fat concentrations, risk specific dose estimates and associated oral
slope factors based on upper 95th percentile estimate of regression coefficient of
all fatal cancers reported by Cheng et al. (2006, 523122) for selected risk levels	5-96

5-4. Comparison of fat concentrations, risk specific dose estimates and associated

central tendency slope estimates based on best estimate of regression coefficient

of all fatal cancers reported by Cheng et al. (2006, 523122) for selected risk levels.... 5-97

5-5. Kociba et al. (1978, 001818) male rat tumor incidence data and blood

concentrations for dose-response modeling	5-97

5-6. Kociba et al. (1978, 001818) female rat tumor incidence data and blood

concentrations for dose-response modeling	5-98

5-7. NTP (1982, 594255) female rat tumor incidence data and blood concentrations

for dose-response modeling	5-98

5-8. NTP (1982, 594255) male rat tumor incidence data and blood concentrations for

dose-response modeling	5-99

5-9. NTP (1982, 594255) female mouse tumor incidence data and blood

concentrations for dose-response modeling	5-99

5-10. NTP (1982, 594255) male mouse tumor incidence data and blood concentrations

for dose-response modeling	5-100

5-11. NTP (2006, 197605) female rat tumor incidence data and blood concentrations

for dose-response modeling	5-100

5-12. Toth et al. (1979, 197109) male mouse tumor incidence data and blood

concentrations for dose-response modeling	5-101

5-13. Delia Porta et al. (1987, 197405) male mouse tumor incidence data and blood

concentrations for dose-response modeling	5-101

5-14. Delia Porta et al. (1987, 197405) female mouse tumor incidence data and blood

concentrations for dose-response modeling	5-101

5-15. Comparison of multi-stage modeling results across cancer bioassays using blood

concentrations	5-102

5-16. Individual tumor points of departure and slope factors using blood concentrations... 5-104

5-17. Multiple tumor points of departure and slope factors using blood concentrations	5-105

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LIST OF TABLES (continued)

5-18. Comparison of cancer BMDs, BMDLs, and slope factors for combined or selected

individual tumors for 1, 5, and 10% extra risk	5-106

5-19. TCDD human-equivalent dose (HED) BMDs, BMDLs, and oral slope factors

(OSF) for 1, 5, and 10% extra risk	5-107

5-20. Illustrative RfDs based on tumorigenesis in experimental animals	5-108

5-21. Illustrative RfDs based on hypothesized key events in TCDD's MOAs for liver

and lung tumors	5-109

5-22. Comparison of prinicipal epidemiological studies	5-110

5-23. Added background TEQ exposures to blood TCDD/TEQ concentrations in rats	5-112

5-24. Effect of added background TEQ exposure on BMDLoi for cholangiocarcinomas

in rats	5-113

5-25.	NIOSH cohort septile data with added TEQ background	5-113

6-1.	Key sources of uncertainty	6-44

6-2. PODs and amenability for uncertainty quantification	6-45

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LIST OF FIGURES

2-1. EPA's process to select and identify in vivo mammalian and epidemiologic

studies for use in the dose-response analysis of TCDD	2-248

2-2. EPA's process to evaluate available epidemiologic studies using study inclusion

criteria for use in the dose-response analysis of TCDD	2-249

2-3.	EPA's process to evaluate available animal bioassay studies using study inclusion
criteria for use in the dose-response analysis of TCDD	2-250

3-1.	Liver/fat concentration ratios in relation to TCDD dose at various times after oral
administration of TCDD to mice	3-70

3-2. First-order elimination rate fits to 36 sets of serial TCDD sampling data from

Seveso patients as function of initial serum lipid TCDD	3-71

3-3. Observed relationship of fecal 2,3,7,8-TCDD clearance and estimated percent

body fat	3-72

3-4. Unweighted empirical relationship between percent body fat estimated from body
mass index and TCDD elimination half-life—combined Ranch Hand and Seveso
observation	3-73

3-5. Relevance of candidate dose metrics for dose-response modeling, based on mode

of action and target organ toxicity of TCDD	3-74

3-6. Process of estimating a human-equivalent TCDD lifetime average daily oral

exposure (dH) from an experimental animal average daily oral exposure (d\) based
on the body-burden dose metric	3-75

3-7. Human body burden time profiles for achieving a target body burden for different

exposure duration scenarios	3-76

3-8. Schematic of the CADM structure	3-77

3-9. Comparison of observed and simulated fractions of the body burden contained in

the liver and adipose tissues in rats	3-78

3-10. Conceptual representation of PBPK model for rat exposed to TCDD	3-79

3-11. Conceptual representation of PBPK model for rat developmental exposure to

TCDD	3-80

3-12. TCDD distribution in the liver tissue	3-81

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LIST OF FIGURES (continued)

3-13. Growth rates for physiological changes occurring during gestation	3-82

3-14. Comparisons of model predictions to experimental data using a fixed elimination
rate model with hepatic sequestration (A) and an inducible elimination rate model
with (B) and without (C) hepatic sequestration	3-83

3-15. PBPK model simulation of hepatic TCDD concentration (ppb) during chronic
exposure to TCDD at 50, 150, 500, 1,750 ng TCDD/BW using the inducible
elimination rate model compared with the experimental data measured at the end
of exposure	3-84

3-16. Model predictions of TCDD blood concentration in 10 veterans (A-J) from Ranch

Hand Cohort	3-85

3-17. Time course of TCDD in blood (pg/g lipid adjusted) for two highly exposed

Austrian women (patients 1 and 2)	3-86

3-18. Observed vs. Emond et al. (2005, 197317) model simulated serum TCDD

concentrations (pg/g lipid) over time (In = natural log) in two Austrian women	3-87

3-19. Comparison of the dose dependency of TCDD elimination in the Emond model
vs. observations of nine Ranch Hand veterans and two highly exposed Austrian
patients	3-88

3-20. Sensitivity analysis was performed on the inducible elimination rate	3-89

3-21. Experimental data (symbols) and model simulations (solid lines) of (A) blood, (B)
liver and (C) adipose tissue concentrations of TCDD after oral exposure to 150
ng/kg-day, 5 days/week for 17 weeks in mice	3-90

3-22 Comparison of PBPK model simulations with experimental data on liver

concentrations in mice administered a single oral dose of 0.001-300 jag TCDD/kg.... 3-91

3-23. Comparison of model simulations (solid lines) with experimental data (symbols)
on the effect of dose on blood (cb), liver (cli) and fat (cf) concentrations following
repetitive exposure to 0.1-450 ng TCDD/kg, 5 days/week for 13 weeks in mice	3-92

3-24. Comparison of experimental data (symbols) and model predictions (solid lines) of
(A) blood, (B) liver and (C) adipose tissue concentrations of TCDD after oral
exposure to 1.5 ng/kg-day, 5 days/week for 17 weeks in mice	3-93

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LIST OF FIGURES (continued)

3-25. Comparison of experimental data (symbols) and model predictions (solid lines) of
(A) blood concentration, (B) liver concentration, (C) adipose tissue concentration
(D) feces excretion (% dose) and (E) urinary elimination (% dose) of TCDD after
oral exposure to 1.5 ng/kg-day, 5 days/week for 13 weeks in mice	3-94

3-26. Comparison of experimental data (symbols) and model predictions (solid lines) of
(A) blood concentration, (B) liver concentration, (C) adipose tissue concentration
(D) feces excretion (% dose) and (E) urinary elimination (% dose) of TCDD after
oral exposure to 150 ng/kg-day, 5 days/week for 13 weeks in mice	3-95

3-27. PBPK model simulations (solid lines) vs. experimental data (symbols) on the
distribution of TCDD after a single acute oral exposure to A-B) 0.1, C-D) 1.0
and E-F) 10 jag of TCDD/kg of body weight in mice	3-96

3-28. PBPK model simulation (solid lines) vs. experimental data (symbols) on the

distribution of TCDD after a single dose of 24 [j,g/kgBW on GD 12 in mice	3-97

3-29. Comparison of the near-steady-state body burden simulated with CADM and
Emond models for a daily dose ranging from 1 to 10,000 ng/kg-day in rats and
humans	3-98

3-30. TCDD serum concentration-time profile for lifetime, less-than-lifetime and

gestational exposure scenarios, with target concentrations shown for each; profiles
generated with Emond human PBPK model	3-99

3-31.	TCDD serum concentration-time profile for lifetime, less-than-lifetime and
gestational exposure scenarios, showing continuous intake levels to fixed target
concentration; profiles generated with Emond human PBPK model	3-100

4-1.	EPA's process to select and identify candidate PODs from key epidemiologic

studies for use in the noncancer risk assessment of TCDD	4-58

4-2. EPA's process to select and identify candidate PODs from key animal bioassays

for use in noncancer dose-response analysis of TCDD	4-59

4-3.	Exposure-response array for ingestion exposures to TCDD	4-60

4-4.	Candidate RfD array	4-61

5-1.	Mechanism of altered gene expression by AhR	5-114

5-2.	TCDD's hypothesized modes of action in site-specific carcinogenesis	5-115

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LIST OF FIGURES (continued)

5-3. EPA's process to select and identify candidate OSFs from key animal bioassays

for use in the cancer risk assessment of TCDD	5-116

5-4. Dose-response model shape	5-117

5-5. Comparison of individual and population dose-response curves; a simple

illustration	5-118

5-6. Multistage benchmark dose modeling of NTP (2006, 197605) cholangiosarcoma

data	5-119

5-7. Multistage benchmark dose modeling of NTP (2006, 197605) combined tumor

data	5-120

5-8. Estrogen receptor-mediated response-modeling plot from Kohn and Melnick

(2002, 199104): low-dose region shown	5-121

5-9. Representative endpoints for each of the hypothesized key events following AhR

activation for TCDD-induced liver tumors	5-122

5-10. Representative endpoints for two hypothesized key events following AhR

activation for TCDD-induced lung tumors	5-123

5-11.	Candidate oral slope factor array	5-124

6-1.	Back-casted vs. predicted TCDD serum levels for a worker subset	6-46

6-2. Distribution of in vivo unweighted REP values in the 2004 database	6-47

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LIST OF ABBREVIATIONS AND ACRONYMS

2,4,5-T

2,4,5-trichlorophenoxyacetic acid

2,4-D

2,4-dichlorophenoxyacetic acid

AA

ascorbic acid

ACOH

acetanilide-4-hydroxylase

AHH

aryl hydrocarbon hydroxylase

AhR

aryl hydrocarbon receptor

AhR-/-

AhR-deficient

AIC

Akaike Information Criterion

ANL

Argonne National Laboratory

ANOVA

analysis of variance

APE

airborne particulate extract

ASAT

aspartate aminotransferase

AUC

area under the curve

bHLH-PAS

basic helix-loop-helix, Per-Arnt-Sim

Bmax

equilibrium maximum binding capacity

BMD

benchmark dose

BMDL

benchmark dose lower confidence bound

BMDS

Benchmark dose software

BMI

body mass index

BMR

benchmark response

BPS

balanopreputial separation

BROD

benzyloxy resoufin-O-deethylase

b-TSH

blood thyroid-stimulating hormone

BW

body weight

C

cerebellum

CADM

concentration- and age-dependent elimination model

Cc

cerebral cortex

CI

confidence interval

CSAF

chemical-specific adjustment factor

CSLC

cumulative serum lipid concentration

Cx

connexin

CYP

cytochrome P450

Da:HED

ratio of administered dose to HED

DEN

diethylnitrosamine

df

degrees of freedom

DLC

dioxin-like compound

DRE/XRE

dioxin/xenobiotic response elements

DRL

differential reinforcement of low rate

DSA

delayed spatial alteration

e2

17P-estradiol

EDX

effective dose eliciting x percent response

EGFR

epidermal growth factor receptor

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LIST OF ABBREVIATIONS AND ACRONYMS (continued)

EPA

Environmental Protection Agency

ER

estrogen receptor

EROD

7-ethoxyresorufin-O-deethylase

ERa

estrogen receptor alpha

EU

European Union

FFA

free fatty acid

FR

fixed-ratio

FSH

follicle stimulating hormone

FT4

free thyroxine

GD

gestation day

GSH

glutathione stimulating hormone

GSH-Px

glutathione stimulating hormone peroxidase

GST

glutathione-»Y-transferase

H

hippocampus

HCH

hexachl orocy cl ohexane

HED

human equivalent dose

HQ

hazard quotient

HR

hazard ratio

Hsp90

heat shock protein 90

IARC

International Agency for Research on Cancer

IGF

insulin-like growth factor

IL

interleukin

ILSI

International Life Sciences Institute

i.p.

intraperitoneal

IRIS

Integrated Risk Information System

KABS

oral absorption parameters

LASC

lipid-adjusted serum concentration

LD50

lethal dose eliciting x percent response

LED

lower confidence effective dose

LEDX

lower bound of the 95% confidence interval on the dose that yields an x% effect

LH

luteinizing hormone

LOAEL

lowest-observed-adverse-effect level

LOAELhed

HED estimate based on LOAELs

LOEL

lowest-observed-adverse level

MCH

mean corpuscular hemoglobin

MCMC

Markov Chain Monte Carlo

MCV

mean corpuscular volume

MOA

mode of action

MOE

margin of exposure

MROD

7-methoxyresorufin-O-deethylase

MTD

maximum tolerated dose

NAS

National Academy of Sciences

NIOSH

National Institute for Occupational Safety and Health

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LIST OF ABBREVIATIONS AND ACRONYMS (continued)

NOAEL

no-observed-adverse-effect level

NOEL

no-ob served-effect level

NRC

National Research Council

NTP

National Toxicology Program

OR

odds ratio

OSF

oral slope factor

PA

permeability x area

PAI2

plasminogen activator inhibitor 2

PBMC

peripheral blood mononuclear cells

PBPK

physiologically based pharmacokinetic

PCB

polychlorinated biphenyl

PCDD

polychlorinated dibenzo-/>dioxin

PCDF

polychlorinated dibenzofuran

PEPCK

phosphoenolpyruvate carboxykinase

PF

adipose tissue:blood partition coefficient

PHAH

polyhalogenated aromatic hydrocarbons

PK

pharmacokinetic

PND

postnatal day

POD

point of departure

PP

phosphotyrosyl protein

PRA

probabilistic risk assessment

PRE

body:blood partition coefficient

PROD

7-pentoxyresorufin-O-deethylase

RAR

retinoic acid receptor

REP

relative potency

RfC

reference concentration

RfD

reference dose

RL

reversal learning

RL

risk level

RR

rate ratios

RR

relative risk

RT-PCR

reverse transcription polymerase chain reaction

RXR

retinoid X receptor

S

saline

SA

superoxide anion

SAhRM

SRM for AhRs

S-D

Sprague-Dawley

SD

standard deviation

SIR

standardized incidence ratio

SMR

standardized mortality ratio

SOD

superoxide dismutase

SRBC

sheep red blood cell

SSB

single-strand break

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LIST OF ABBREVIATIONS AND ACRONYMS (continued)

SWHS

Seveso Women's Health Study

T4

thyroxine

TBARS

thiobarbituric acid-reactive substances

TCB

3,3',4,4'-tetrachlorobiphenyl

TCDD

2,3,7,8 -T etrachl orodib enzo-p-di oxin

TCP

2,4,5-trichlorophenol

TEF

toxicity equivalence factor

TEQ

toxicity equivalence

TGFa

transforming growth factor a

TK

toxicokinetic

TNF-a

tumor necrosis factor alpha

TOTTEQ

total toxicity equivalence

TSH

thyroid stimulating hormone

TT4

total thyroxine

TWA

time-weighted average

U.S. NRC

U.S. Nuclear Regulatory Commission

UDP

uridine diphosphate

UDPGT

UDP-glucoronosyl transferase

LIED

upper confidence bound for the effective dose

UF

uncertainty factor

UFa

interspecies extrapolation factor

UFd

database factor

UFh

human interindividual variability

UFl

LOAEL-to-NOAEL UF

UFS

subchronic-to-chronic UF

UGT

UDP-glucuronosyltransferase

UGT1

uridine diphosphate glucuronosyltransferase I

Vd

volume of distribution

WHO

World Health Organization

ZS@Z

zero slope at zero dose

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PREFACE

This report was developed by the U.S. Environmental Protection Agency's (EPA) Office
of Research and Development (ORD), National Center for Environmental Assessment (NCEA).
Sections of the report, including Section 6 and the updated literature search, were developed
through a collaborative effort between NCEA and the Department of Energy's Argonne National
Laboratory (ANL).

In 2003, EPA, along with other federal agencies, asked the National Academy of
Sciences (NAS) to review aspects of the science in EPA's draft dioxin reassessment entitled,
"Exposure and Human Health Reassessment of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD)
and Related Compounds," and, in 2004, EPA sent the 2003 draft dioxin reassessment to the NAS
for their review. In 2006, the NAS released the report of their review entitled, "Health Risks
from Dioxin and Related Compounds: Evaluation of the EPA Reassessment." The NAS
identified three areas in EPA's 2003 draft reassessment that required substantial improvement to
support a more scientifically robust risk characterization. These three areas were:

(1)	justification of approaches to dose-response modeling for cancer and noncancer endpoints;

(2)	transparency and clarity in selection of key data sets for analysis; and (3) transparency,
thoroughness, and clarity in quantitative uncertainty analysis. The NAS provided EPA with
recommendations to address their key concerns. This draft report details EPA's response to the
key comments and recommendations included in the 2006 NAS report.

In 2008, prior to developing this draft report, EPA, in collaboration with ANL, developed
and published a literature database of peer-reviewed studies on TCDD toxicity, including in vivo
mammalian dose-response studies and epidemiologic studies. EPA subsequently requested
public comment on this database. EPA and ANL then convened a scientific workshop in 2009.
The Workshop goals were to identify and address issues related to the dose-response assessment
of TCDD and to ensure that EPA's response to the NAS focused on the key issues and reflected
the most meaningful science.

This draft report provides a technical response to the 2006 NAS report. It utilizes a
TCDD physiologically-based pharmacokinetic model in its development of dose-response
analyses of TCDD toxicological and epidemiological literature. This draft report presents new
analyses of both the potential cancer and noncancer human health effects that may result from
exposures to TCDD. The draft report develops an oral reference dose (RfD) for TCDD. It also
presents a new cancer oral slope factor. Federal agencies and White House offices have been
provided an opportunity for review and comment on this draft report prior to its public release.

This draft dioxin report is being released for public comment and will also be provided to
EPA's Science Advisory Board (SAB) for independent external peer review. The SAB will
convene an expert panel composed of scientists knowledgeable about technical issues related to
dioxins and risk assessment. The SAB is expected to hold their first public meeting on
July 13-15, 2010.

This document is a draft for review purposes only and does not constitute Agency policy.

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AUTHORS, CONTRIBUTORS, AND REVIEWERS

PRIMARY AUTHORS

National Center for Environmental Assessment, U.S. Environmental Protection Agency,
Cincinnati, OH

Belinda Hawkins
Janet Hess-Wilson
Glenn Rice (Project Co-Lead)

Jeff Swartout (Project Co-Lead)

Linda K. Teuschler

CONTRIBUTING AUTHORS

National Center for Environmental Assessment, U.S. Environmental Protection Agency,
Cincinnati, OH

Scott Wesselkamper
Michael Wright
Bette Zwayer

National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection
Agency, Research Triangle Park, NC
Hi sham El-Masri

Argonne National Laboratory, Argonne, IL
Margaret MacDonell

Emory University, Atlanta, GA
Kyle Steenland

Resources for the Future, Washington, DC
Roger M. Cooke

University of Montreal; BioSimulation Consulting, Newark, DE
Claude Emond

University of Montreal, Montreal, Canada
Kannan Krishnan

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AUTHORS, CONTRIBUTORS, AND REVIEWERS (continued)

CONTRIBUTORS

National Center for Environmental Assessment, U.S. Environmental Protection Agency,
Washington, DC

Karen Hogan
Leonid Kopylev

Argonne National Laboratory, Argonne, IL
Maryka H. Bhattacharyya
Andrew Davidson

Ravi Subramaniam
Paul White

Mary E. Finster
David P. Peterson

Clark University, Worcester, MA
Dale Hattis

Colorado State University, Fort Collins, CO
Raymond Yang

Bruce Allen Consulting, Chapel Hill, NC
Bruce C. Allen

ICF International, Durham, NC
Robyn Blain
Rebecca Boyles
Patty Chuang
Cara Henning
Baxter Jones
Penelope Kellar
Mark Lee

Nikki Maples-Reynolds

Amalia Marenberg
Garrett Martin
Margaret McVey
Chandrika Moudgal
Bill Mendez
Ami Parekh
Andrew Shapiro
Audrey Turley

National Toxicology Program, Research Triangle Park, NC
Michael Devito

Penn State University, University Park, PA
Jack P. Vanden Heuvel

Risk Sciences International, Ottawa, Ontario
Jessica Dennis
Dan Krewski
Greg Paoli

University of California-Berkeley, Berkeley, CA
Brenda Eskenazi

Salomon Sand
Natalia Shilnikova
Paul Villenueve

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AUTHORS, CONTRIBUTORS, AND REVIEWERS (continued)

CONTRIBUTORS (continued)

University of California-Irvine, Irvine, CA
Scott Bartell

REVIEWERS

This document has been provided for review to EPA scientists and interagency reviewers
from other federal agencies and White House offices.

INTERNAL REVIEWERS

National Center for Environmental Assessment, U
Glinda Cooper, Washington, DC
Ila Cote, Research Triangle Park, NC
Lynn Flowers, Washington, DC
Martin Gehlhaus, Washington, DC
Kate Guyton, Washington, DC
Samantha Jones, Washington, DC
Matthew Lorber, Washington, DC

ACKNOWLEDGMENTS

National Center for Environmental Assessment, U
Jeff Frithsen, Washington, DC
Annette Gatchett, Cincinnati, OH
Andrew Gillespie, Cincinnati, OH
Marie Nichols-Johnson, Cincinnati, OH

Colorado State University, Fort Collins, CO
William H. Farland

ECFlex, Inc., Fairborn, OH
Dan Heing
Heidi Glick
Amy Prues
Lana Wood

This document is a draft for review purposes only and does not constitute Agency policy.

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S. Environmental Protection Agency
Eva McLanahan, Research Triangle Park, NC
Susan Rieth, Washington, DC
Reeder Sams, Research Triangle Park, NC
Paul Schlosser, Research Triangle Park, NC
Jamie Strong, Washington, DC
John Vandenberg, Research Triangle Park, NC

.S. Environmental Protection Agency
Maureen Johnson, Washington, DC
Peter Preuss, Washington, DC
Linda Tuxen, Washington, DC


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AUTHORS, CONTRIBUTORS, AND REVIEWERS (continued)

ACKNOWLEDGMENTS (continued)

IntelliTech Systems, Inc., Fairborn, OH
Cris Broyles
Luella Kessler
Debbie Kleiser
Stacey Lewis
Linda Tackett

National Institute of Environmental Health Sciences, Research Triangle Park, NC
Linda S. Birnbaum
Christopher J. Portier

National Toxicology Program, Research Triangle Park, NC
Nigel Walker

2009 Dioxin Workshop Participants

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EXECUTIVE SUMMARY

OVERVIEW

The U.S. Environmental Protection Agency (EPA) is committed to the development of
risk assessment information of the highest scientific integrity for use in protecting human health
and the environment. Scientific peer review is an integral component of the process EPA uses to
generate high quality toxicity and exposure assessments of environmental contaminants. To this
end, EPA asked the National Academy of Sciences (NAS) to review its comprehensive human
health risk assessment external review draft entitled, Exposure and Human Health Reassessment
of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) andRelatedCompounds (U.S. EPA, 2003,
537122; "2003 Reassessment"). This current document, EPA's Reanalysis of Key Issues Related
to Dioxin Toxicity and Response to NAS Comments, directly and technically responds to key
comments and recommendations pertaining to TCDD dose-response assessment published by the
NAS in their review (NAS, 2006, 198441). This document only addresses issues pertaining to
TCDD dose-response assessment.

In May 2009, EPA Administrator Lisa P. Jackson announced the "Science Plan for
Activities Related to Dioxins in the Environment' ("Science Plan") that addressed the need to
finish EPA's dioxin reassessment and provide a completed health assessment on this high profile
chemical to the American public as quickly as possible.1 The Science Plan states that EPA will
release a draft report that responds to the recommendations and comments included in the NAS
review of EPA's 2003 Reassessment, and that, in this draft report, EPA's National Center for
Environmental Assessment, Office of Research and Development, will provide a limited
response to key comments and recommendations in the NAS report (draft response). This draft
response is to focus on dose-response issues raised by the NAS and include analyses of relevant
new key studies. The draft response is to be provided for public review and comment and for
independent external peer review by EPA's Science Advisory Board. Following completion of
this report, EPA is to review the impacts of the response to comments report on its 2003
Reassessment.

Available at http://www.epa.gov/dioxin/scienceplan.

This document is a draft for review purposes only and does not constitute Agency policy.

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This draft document comprises EPA's report that responds both directly and technically
to the recommendations and comments on TCDD dose-response assessment included in the NAS
review of EPA's 2003 Reassessment. Because new data are analyzed in this report and toxicity
values are derived, this document will follow the IRIS process for review, clearance and
completion; however, it is not a traditional IRIS document. Information developed in this
document is intended to not only respond to the NAS review, but also to expand EPA's
knowledge of TCDD cancer and noncancer dose-response based on the most current literature,
existing methods, and adherence to EPA risk assessment guidance documents.

In addition to this document, three separate EPA activities address additional NAS
comments pertaining to toxicity equivalence factors (TEFs) and background exposure levels.
Information on the application of the dioxin TEFs is published elsewhere by EPA for both
ecological (U.S. EPA, 2008, 543774) and human health (U.S. EPA, 2009, 192196^) risk
assessment. EPA does not directly address TEFs herein, but makes use of the concept of toxicity
equivalence (TEQ)2 as applicable to the analysis of exposure dose in epidemiologic studies and
to discussions on the effect of background TEQ on TCDD dose response. Furthermore,
information on updated background levels of dioxin in the U.S. population has been recently
reported by EPA (Lorber et al., 2009, 543766). addressing the NAS recommendations pertaining
to the assessment of human exposures to TCDD and other dioxins.

The NAS identified three key recommendations requiring substantial improvement to
support a scientifically robust characterization of human responses to exposures to TCDD.

These three key areas are (1) improved transparency and clarity in the selection of key data sets
for dose-response analysis, (2) further justification of approaches to dose-response modeling for
cancer and noncancer endpoints, and (3) improved transparency, thoroughness, and clarity in
quantitative uncertainty analysis. The NAS also encouraged EPA to calculate a Reference Dose
(RfD), and provided numerous specific comments on various aspects of EPA's 2003
Reassessment. The three key recommendations specifically pertain to dose-response assessment
and uncertainty analysis. Therefore, EPA's response to the NAS in this document is focused on

2Toxicity equivalence (TEQ) is the product of the concentration of an individual dioxin like compound in an
environmental mixture and the corresponding TCDD TEF for that compound. These products are summed to yield
the TEQ of the mixture.

This document is a draft for review purposes only and does not constitute Agency policy.

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these issues. EPA thoroughly considered the recommendations of the NAS and responds with
scientific and technical evaluation of TCDD dose-response data via:

•	an updated literature search that identified new TCDD dose-response studies (see
Section 2);

•	a kickoff workshop that included the participation of external experts in TCDD health
effects, toxicokinetics, dose-response assessment and quantitative uncertainty analysis;
these experts discussed potential approaches to TCDD dose-response assessment and
considerations for EPA's response to NAS; a Workshop Report was developed

(U.S. EPA, 2009, 543757. see Appendix A);

•	detailed TCDD-specific study inclusion criteria and processes for the selection of key
studies (see Section 2.3) and epidemiologic and animal bioassay data for TCDD
dose-response assessment (see Section 2.4.1, Appendix B, and Section 2.4.2,
respectively);

•	kinetic modeling to quantify appropriate dose metrics for use in TCDD dose-response
assessment (see Section 3 and Appendices C and D);

•	dose-response modeling for all appropriate noncancer and cancer data sets (see
Section 4.2/Appendix E and Section 5.2.3/Appendix F, respectively);

•	thorough and transparent evaluation of the selected TCDD data for use in the derivation
of an RfD and an oral slope factor (OSF) (see Sections 4.2 and 5.2.3, respectively);

•	the development of an RfD (see Section 4.3);

•	the development of a revised OSF (see Section 5.3) with an updated cancer weight of
evidence determination for TCDD based on EPA's 2005 Cancer Guidelines (U.S. EPA,
2005, 086237") (see Section 5.1.2);

•	consideration of nonlinear dose-response approaches for cancer, including illustrative
RfDs for cancer precursor events and tumors (see Section 5.2.3.4) ; and

•	discussion of the feasibility and utility of quantitative uncertainty analysis for TCDD
dose-response assessment (see Section 6).

Each of the activities listed above is briefly described in this Executive Summary, and is
described in detail in the related sections of this document.

PRELIMINARY ACTIVITIES UNDERTAKEN BY EPA TO ENSURE THAT THIS
TECHNICAL RESPONSE REFLECTS THE CURRENT STATE-OF-THE-SCIENCE

As part of the development of this document, EPA undertook two activities that included

public involvement: an updated literature search and a scientific expert workshop. The adverse

This document is a draft for review purposes only and does not constitute Agency policy.

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health effects associated with TCDD exposures are documented extensively in epidemiologic
and toxicologic studies. As such, the database of relevant information pertaining to the
dose-response assessment of TCDD is vast and constantly expanding. Responding directly to the
NAS recommendation to use the most current and up-to-date scientific information related to
TCDD, EPA, in collaboration with Argonne National Laboratory (ANL), developed an updated
literature database of peer-reviewed studies on TCDD toxicity, including in vivo mammalian
dose-response studies and epidemiologic studies. An initial literature search for studies
published since the 2003 Reassessment was conducted to identify studies published between the
year 2000 and October 31, 2008. EPA published the initial literature search results in the Federal
Register in November 2008 and invited the public to review the list and submit additional
peer-reviewed relevant studies. Additional studies identified by the public and through
continued work on this response have been incorporated into the final set of studies for TCDD
dose-response assessment (updated through October 2009). EPA believes that the
implementation of this rigorous search strategy ensures that the most current and relevant studies
were considered for the technical response to NAS and TCDD dose-response assessment
included herein.

To assist in responding to the NAS, EPA, in collaboration with ANL, convened a
scientific expert workshop ("Dioxin Workshop") in February 2009 that was open to the public.
The primary goals of the Dioxin Workshop were to identify and address issues related to the
dose-response assessment of TCDD and to ensure that EPA's response to the NAS focused on
the key issues, while reflecting the most meaningful science. EPA and ANL assembled expert
scientists and asked them to identify and discuss the technical challenges involved in addressing
the NAS comments, discuss approaches for addressing these key recommendations, and to assist
in the identification of important published and peer-reviewed literature on TCDD. The
workshop was structured into seven scientific topic sessions as follows: (1) quantitative
dose-response modeling issues, (2) immunotoxicity, (3) neurotoxicity and nonreproductive
endocrine effects, (4) cardiovascular toxicity and hepatotoxicity, (5) cancer, (6) reproductive and
developmental toxicity, and (7) quantitative uncertainty analysis of dose-response. External
co-chairs (i.e., scientists who were not members of EPA or ANL) were asked to facilitate the
sessions and then prepare summaries of discussions occurring in each session. The session
summaries formed the basis of a final workshop report (U.S. EPA, 2009, 543757. Appendix A of

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this document). Some of the key outcomes from the workshop include the following
recommendations:

•	to further develop study selection criteria for evaluating the suitability of developing
dose-response models based on animal bioassays and human epidemiologic studies;

•	to use kinetic modeling to identify relevant dose metrics and dose conversions between
test animal species and humans, and between human internal dose measures and human
intakes;

•	to consider newer human or animal (e.g., NTP, 2006, 197605) publications when
evaluating quantitative dose-response models for cancer;

•	to consider both linear and nonlinear modeling in the cancer dose-response analysis.

The discussions held during the Dioxin Workshop helped inform, guide, and focus EPA's
response to NAS.

EPA'S APPROACH TO CONSIDERING TRANSPARENCY AND CLARITY IN THE
SELECTION OF KEY STUDIES AND DATA SETS FOR DOSE-RESPONSE
MODELING

One of the key NAS recommendations to EPA was to utilize a clear and transparent
process for the selection of key studies and data sets for dose-response assessment. EPA agrees
with the NAS and believes that clear delineation of the study selection process and decisions
regarding key studies and data sets will facilitate communication of critical decisions made in the
TCDD dose-response assessment. EPA developed detailed processes and TCDD-specific
criteria for the selection of key dose-response studies. These criteria are based on common
practices and current guidance for point of departure (POD) identification and RfD and OSF
derivation and also consider issues specifically related to TCDD. Following the selection of key
studies, EPA employed additional processes to further select and identify cancer and noncancer
datasets from these key studies for use in dose-response analysis of TCDD.

For the study evaluation and key data set selection, EPA has undertaken different
approaches for the epidemiologic and in vivo animal bioassay studies. The significant
differences between animal and human health effects data and their use in EPA risk assessment
support development of separate criteria for study inclusion and different approaches to study
evaluation. For the vast majority of compounds on EPA's Integrated Risk Information System

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(IRIS, U.S. EPA, 2009, 192196), cancer and n on cancer toxicity values have been derived using
animal bioassay data; thus, some of the TCDD-specific study inclusion criteria for animal
bioassay data are based on EPA's common practices and guidance for POD selection and RfD
and OSF derivation. Far fewer IRIS toxicity values have been derived from human data,
although some examples do exist.3 The modeling and interpretation of such human data have
been conducted on a case-by-case basis because each cohort is uniquely defined and has its own
set of exposure conditions, significant confounders, and biases that may need to be considered in
dose-response modeling.

Figure ES-1 presents EPA's study evaluation process for the epidemiologic studies
considered for this TCDD dose-response assessment, including specific study inclusion criteria
(see Section 2.3.1). EPA applied TCDD-specific epidemiologic study inclusion criteria to all
epidemiologic studies published on TCDD and dioxin-like compounds (DLCs) that had been
identified in the TCDD literature database (see Section 2.4.1, Appendix B). The studies were
initially evaluated using five considerations (see Figure ES-1) that provide the most relevant
kinds of information needed to consider the feasibility of quantitative human health risk
analyses. Then EPA required that the studies meet three study inclusion criteria: 1) the study is
published in the peer-reviewed scientific literature and includes an appropriate discussion of
strengths and limitations; 2) the exposure is primarily to TCDD, rather than dioxin-like
compounds (DLCs), and is properly quantified so that dose-response relationships can be
assessed; and 3) the effective dose and oral exposure must be reasonably estimable. To meet the
third criterion, information is required on long-term exposures for cancer, and, for noncancer,
information is required regarding the appropriate time window of exposure that is relevant for a
specific, nonfatal health endpoint. Therefore, the study should include an appropriate latency
period between TCDD exposure and the onset of the effect. Only studies meeting these
three criteria were included in EPA's TCDD dose-response analyses (see Section 2.4.3).

Figure ES-2 presents EPA's study evaluation process for mammalian bioassays
considered for TCDD dose-response assessment, including the specific study inclusion criteria
(see Section 2.3.2). EPA applied TCDD-specific in vivo mammalian bioassay study inclusion

3 Examples of toxicity values on IRIS from human data include benzene, beryllium and compounds, chromium IV,
and 1,3-butadiene that have RfDs, Reference Concentrations, Inhalation Unit Risks and/or OSFs all based on
occupational cohort data and the methyl mercury RfD that is based on high fish consuming cohorts (U.S. EPA,
2009, 1921961.

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criteria to all of the bioassay studies of TCDD that had been identified in the TCDD literature
database (see Section 2.4.2). After ascertaining that a study had been published in the
peer-reviewed literature, EPA applied dose requirements to the lowest tested average daily doses
in each study, with specific requirements for cancer (<1 (j,g/kg-day) and noncancer
(<30 ng/kg-day) studies to ensure that only low-dose TCDD bioassays would be considered for
quantitative assessment. These dose requirements were used to eliminate those studies that
would not be selected for development of an RfD or an OSF because the lowest doses tested
were too high relative to other TCDD bioassays. EPA also required that the bioassays exposed
animals via the oral route to TCDD only and that the purity of TCDD was specified. Finally, the
studies were evaluated using four considerations (see Figure ES-2) regarded as providing the
most relevant information for development of quantitative human health risk analyses from
animal bioassay data. Only the bioassay studies meeting these criteria and considerations were
included in EPA's TCDD dose-response analyses (see Section 2.4.3).

Applying the study inclusion criteria for both epidemiologic and mammalian bioassay
datasets resulted in a list of key noncancer and cancer studies that were considered for
quantitative dose-response analyses of TCDD. Endpoints from these studies that were not
considered to be toxicologically relevant were eliminated from consideration (see Section 4.2.1,
Appendix G). The study/endpoint dataset combinations from the remaining studies were then
subjected to dose-response assessment, and PODs for use in developing RfDs or OSFs were
identified. PODs included no-observed-adverse-effect levels (NOAELs), lowest-observed-
adverse-effect levels (LOAELs) or lower bound benchmark dose levels (BMDLs). The most
sensitive PODs were selected as candidates for derivation of the RfD and OSF.

USE OF KINETIC MODELING TO ESTIMATE TCDD DOSES

NAS recommended that EPA utilize state-of-the-science approaches to finalize the
2003 Reassessment. Although NAS concurred with EPA's use of first-order body burden
models in the 2003 Reassessment, analyses of recent TCDD literature and comments by experts
at the Dioxin Workshop suggested that the understanding of TCDD kinetics had increased
significantly since the release of EPA's 2003 Reassessment. These advances led to the
development of several pharmacokinetic models for TCDD (Ay 1 ward et al., 2005, 197114; e.g..

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Emond et al., 2004, 197315; Emond et al., 2005, 197317; Emond et al., 2006, 197316) and
resulted in EPA's incorporation of TCDD kinetics in the dose-response assessment of TCDD.

The evaluation of internal dose in exposed humans and other species is facilitated by an
understanding of pharmacokinetics (i.e., absorption, distribution, metabolism, and excretion).
TCDD pharmacokinetics are influenced by three distinctive features: (1) TCDD is highly
lipophilic, (2) TCDD is slowly metabolized, and (3) TCDD induces binding proteins in the liver.
The overall impact of these factors results in preferential storage of TCDD in adipose tissue, a
long half-life of TCDD in blood due to slow metabolism, and sequestration in liver tissue when
binding induction becomes significant. As these kinetic features control target tissue levels of
dioxin, they become important in relating toxicity in animals to possible effects in humans.

Consideration of pharmacokinetic mechanisms is critical to the selection of the dose
metrics of relevance to dose-response modeling of TCDD. Earlier assessments for TCDD,
including the 2003 Reassessment, used estimates of body burden as the dose metric for
extrapolation between animals and humans. These body burden calculations used a simple
one-compartment kinetic model based on the assumption of a first-order decrease in the levels of
administered dose as a function of time. However, the assumption of a constant half-life value
for the clearance of TCDD from long-term or chronic exposure is not well-supported
biologically given the dose-dependant elimination observed in rodents and humans. The
dynamic disposition and redistribution of TCDD between blood, fat, and liver as a function of
time and dose is better described using biologically-based models. Additionally, these models
provide estimates for other dose metrics (e.g., serum, whole blood, or tissue levels) that are more
biologically relevant to response than body burden estimated based on an assumption of
first-order elimination over time.

EPA considered the following possible dose metrics for TCDD: administered dose,
first-order body burden, lipid-adjusted serum concentration (LASC), whole blood concentration,
tissue concentration, and functional-related metrics of relevance to the mode of action (MO A)
(e.g., receptor occupancy) (see Section 3.3.4.1). After careful evaluation of these dose metrics,
EPA chose to use TCDD concentration in whole blood as the dose metric for assessing TCDD
dose response in this document. Although LASC is generally considered to be the most relevant
metric, whole blood concentration was chosen because of the structure of the PBPK models, in
which the target tissue compartments are connected to the whole blood compartment rather than

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to the serum compartment; LASC is related to whole blood by a scalar, so use of either is
equivalent in the model. Whole blood concentrations also reflect TCDD dose to target tissues
and, are biologically-relevant measures of internal dose. EPA used the time-weighted average
whole-blood concentration over the relevant exposure periods for all continuous dosing
protocols, dividing the area under the time-course concentration curve (AUC) by the exposure
duration.4

Several biologically-based kinetic models for TCDD exist in the literature. The more
recent pharmacokinetic models explicitly characterize the concentration-dependent elimination
of TCDD (Carrier et al., 1995, 197618; Carrier et al., 1995, 543780; Emond et al., 2004, 197315;
Emond et al., 2005, 197317; Emond et al., 2006, 197316; Aylward et al., 2005, 1971141 The
biologically-based pharmacokinetic models describing the concentration-dependent elimination
(i.e., the pharmacokinetic models of Aylward et al. (2005, 197114) and Emond et al. (2005,
197317; 2006, 197316) are relevant for application to simulate the TCDD dose metrics in
humans and animals exposed via the oral route. The rationale for considering the application of
the Aylward et al. (2005, 197114) and Emond et al. (2004, 197315; 2005, 197317; 2006,

197316) models was largely based on the fact that both models reflect research results from
recent peer-reviewed publications, and both models are formulated with dose-dependent hepatic
elimination consistent with the physiological understanding of TCDD kinetics. Dose-response
modeling based on body burden of TCDD in adult animals and humans can be conducted with
either of the models, provided the duration of the experiment is at least one month, due to
limitations in the Aylward et al. (2005, 197114) model. The predicted slope and body burden
over a large dose range are quite comparable between the two models (generally within a factor
of two).

Results of simulations of serum lipid concentrations or liver concentrations vary for the
two models to a larger extent (up to a factor of 7), particularly for simulations of short duration.
These differences reflect two characteristics of the Emond et al. (2006, 197316) model: first,
quasi-steady-state is not assumed in the Emond et al. (2006, 197316) model; second, the serum
lipid composition used in the model is not the same as the adipose tissue lipids. The Aylward

4For the Seveso cohort, which had a high single exposure followed by low-level background exposures leading to a
gradual decline in the internal TCDD concentrations, EPA estimated dose as the mean of the peak exposure and the
average exposure over a defined critical exposure window (see Section 4.2.2).

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et al. (2005, 197114) model does not account for differential solubility of TCDD in serum lipids
and adipose tissue lipids, nor does it account for the diffusion-limited uptake by adipose tissue.
Based on this evaluation, EPA determined that the Emond et al. (2006, 197316) model
performed better than the Ay 1 ward et al. (2005, 197114) model with respect to the ability to
simulate serum lipid and tissue concentrations during exposures that do not lead to the onset of
steady-state condition in the exposed organism. Additionally, of the two selected models, the
pharmacokinetic model developed by Emond et al. (2006, 197316) is more
physiologically-based, as compared to the Ay 1 ward et al. (2005, 197114) model, and models the
blood compartment directly in the rat, mouse, and human; there are also gestational and life-time
nongestational forms of the Emond et al. (2006, 197316) model. In this document, EPA chose
the Emond rodent physiologically-based pharmacokinetic (PBPK) model to estimate blood
TCDD concentrations based on administered doses (see Section 3.3.4, Appendix C).

To enhance the biological basis of the PBPK model of Emond et al. (2006, 197316),
three minor modifications,were made before its use in the computation of dose metrics for
TCDD: 1) recalculation of the volume of the "rest of the body compartment" after accounting for
volume of the liver and fat compartments; 2) calculation of the rate of TCDD excreted via urine
by multiplying the urinary clearance parameter by blood concentration in the equation instead of
by the concentration in the rest of the body compartment; and 3) recalibration for the human
gastric nonabsorption constant to yield observed oral bioavailability of TCDD (Poiger and
Schlatter, 1986) (see Section 3.3.4.4 for details). The modified PBPK model was evaluated
against all published data used in the original model. EPA assumed that the same blood TCDD
levels that led to effects in animals would also lead to effects in humans; therefore, the Emond
human PBPK model was used to estimate the lifetime average daily oral doses (consistent with
the chronic RfD and OSF) that would correspond to the blood TCDD concentrations estimated to
have occurred during the animal bioassays. EPA used the same Emond human PBPK model to
estimate the lifetime average daily doses that would correspond to the TCDD blood or tissue
concentrations reported in the epidemiological studies (Appendix D). These estimates are the
Human Equivalent Doses (HEDs) that are used to develop candidate RfDs and OSFs for TCDD.

Because TCDD elimination is inducible in the Emond model, ratios of daily averaged
intake to long-term blood concentrations are not linear. Because of the nonlinearity of blood
concentration and ingested dose in the Emond Human PBPK model, the cancer risk is only

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approximately linear with the TCDD blood concentration and low TCDD oral ingestion doses,
but is not linear with ingested TCDD at higher doses. Thus, to use these estimates in human
health risk assessment, risk-specific TCDD oral intake levels corresponding to the target risk
levels should be calculated (see Section 5.2.3.1.2.1).

DERIVATION OF AN RfD FOR TCDD

The NAS specifically recommended that EPA derive an RfD for TCDD. Through a
transparent study selection process, EPA identified key studies from both human epidemiologic
studies and animal bioassays. To select candidate PODs for its RfD methodology, EPA applied
additional processes to the key human epidemiologic studies and animal bioassays. Figure ES-3
(exposure-response array) shows the entire candidate PODs graphically in terms of
human-equivalent intake (ng/kg-day). The human study endpoints are shown at the far left of the
figure and, to the right, the rodent endpoints are arranged by the following study categories: less
than 1 year, greater than 1 year, reproductive, and developmental.

For each noncancer epidemiologic study that EPA selected as key, EPA evaluated the
dose-response information developed by the study authors to determine whether the study
provided noncancer effects and TCDD-relevant exposure data for a toxicologically-relevant
endpoint. If such data were available, EPA identified a NOAEL or LOAEL as a candidate POD.
Then, EPA used the Emond human PBPK model to estimate the continuous oral daily intake
(ng/kg-day) that would lead to the relevant blood TCDD concentrations associated with the
candidate POD. If all of this information was available, then the result was included as a
candidate POD.

Through this process, EPA identified health effects from the following
four epidemiologic studies to be considered as the basis for the RfD: Eskenazi et al. (2002,
197168)( reproducti ve—increased length of menstrual cycle), Alaluusua et al. (2004, 197142)
(developmental—tooth development), Mocarelli et al. (2008, 199595s) (reproductive—decreased
sperm concentrations and motility), and Baccarelli et al. (2008, 197059)

(developmental—increased thyroid-stimulating hormone levels in neonates). All four studies are
from the Seveso cohort, whose members were exposed environmentally to high peak
concentrations of TCDD as a consequence of an industrial accident. This complicated the
estimation of average daily doses associated with these specific endpoints, however EPA was

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able to calculate candidate PODs for derivation of an RfD from each of these human studies (see
Section 4.2.3). The Alaluusua et al. (2004, 197142) and Eskenazi et al. (2002, 197168) studies
had PODs well above the Mocarelli et al. (2008, 199595) and Baccarelli et al. (2008, 197059);
because the LOAEL in Eskenazi et al. (2002, 197168) is almost 2 orders of magnitude higher
than the LOAELs for Baccarelli et al. (2008, 197059) and Mocarelli et al. (2008, 199595), it was
not considered further as a candidate POD for derivation of the RfD.

Figure ES-4 summarizes the strategy employed for identifying and selecting candidate
PODs from the key animal bioassays EPA identified for use in noncancer dose-response analysis
of TCDD (see Section 4.2.4). For each noncancer endpoint, EPA first evaluated the
toxicological relevance of each endpoint, rejecting those judged not to be relevant for RfD
derivation (Section 4.2.1, Appendix G). Next, initial PODs (NOAELs, LOAELs, and BMDLs)
based on the first-order body burden metric, and expressed as continuous human-equivalent oral
daily doses (HEDs), were determined for all relevant endpoints.

Because there were very few NOAELs, and BMDL modeling was largely unsuccessful
due to data limitations, the next stage of evaluation was carried out using LOAELs only.
Endpoints not observed at the LOAEL (i.e., reported at higher doses) with BMDLs greater than
the LOAEL were eliminated from further analysis, as they would not be considered as candidates
for the final POD on either a BMDL or NOAEL/LOAEL basis (i.e. the POD would be higher
than the PODs of other relevant endpoints). In addition, all endpoints with HEDs for LOAELs
(LOAELheds) beyond a 100-fold range of the lowest identified LOAELHed were eliminated
from further consideration, as they would not be potential POD candidates either (i.e. the POD
would be higher than the PODs of other relevant endpoints). For the remaining endpoints, EPA
then determined final potential PODs (NOAELs, LOAELs, and BMDLs) based on TCDD blood
concentrations obtained from the Emond rodent PBPK models. HEDs were then estimated for
each of these PODs using the Emond human PBPK model. From these HEDs, a PODred was
selected for each study as the basis for the candidate RfD, to which appropriate uncertainty
factors were applied following EPA guidelines. The resulting candidate RfDs were then
considered in the final selection process for the RfD. Other endpoints occurring at slightly
higher doses representing additional effects associated with TCDD exposure (beyond the
100-fold LOAEL range) were evaluated, modeled, and included in the final candidate RfD array

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to examine endpoints not evaluated by studies with lower PODs. In addition, BMD modeling
based on administered dose was performed on all endpoints for comparison purposes.

For BMD modeling, EPA has used a 10% BMR for dichotomous data for all endpoints;
no developmental studies were identified with designs that incorporate litter effects, for which a
5% BMR would be used (U.S. EPA, 2000, 052150). For continuous endpoints in this document,
EPA has used a BMR of 1 standard deviation from the control mean whenever a specific
toxicologically-relevant BMR could not be defined. Importantly, the 2003 Reassessment defined
the EDoi as 1% of the maximal response for a given endpoint, not as a 1% change from control.
Because RfD derivation is one goal of this document, the noncancer modeling effort undertaken
here differs substantially from the modeling in the 2003 Reassessment. Evaluation of BMD
modeling performance, goodness-of-fit, dose-response data, and resulting BMD and BMDL
estimates included statistical criteria as well as expert judgment of their statistical and
toxicological properties. EPA has reported and evaluated the BMD results using the standard
suite of goodness-of-fit measures from the benchmark dose modeling software (BMDS 2.1).
These include chi-square^-values, Akaike's Information Criterion (AIC), scaled residuals at
each dose level and plots of the fitted models. In some cases, when restricted parameters hit a
bound, EPA used likelihood ratio tests to evaluate whether the improvement in fit afforded by
estimating additional parameters could be justified. Goodness-of-fit measures are reported for
all key data sets in Appendix E. (See Section 4.2.4.2 for a more complete description of the
benchmark dose modeling criteria for model evaluation.)

For selection of the POD to serve as the basis of the RfD, EPA gave the epidemiologic
studies the highest consideration because human data are preferred in the derivation of an RfD,
given that the underlying epidemiologic and animal bioassay data are of comparable quality.

This preference for epidemiologic study data also is consistent with reccomendations of panelists
at the Dioxin Workshop (see U.S. EPA, 2009, 543757. Appendix A). Figure ES-5 arrays the
candidate RfDs from both the human and animal bioassays. The human studies included in
Figure ES-5 (Alaluusua et al., 2004, 197142; Baccarelli et al., 2008, 197059; Mocarelli et al.,
2008, 199595) each evaluate a segment of the Seveso civilian population (i.e., not an
occupational cohort) exposed directly to TCDD released from an industrial accident. In this
document, EPA uses the Baccarelli et al. (2008, 197059) and Mocarelli et al. (2008, 199595)

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studies as co-critical studies in deriving the RfD (Section 4.3).5 In the Seveso cohort exposures
were primarily to TCDD, the chemical of concern, with apparently minimal DLC exposures
beyond those associated with background intake,6 making these studies highly appropriate for
use in RfD derivation for TCDD. In addition, health effects associated with TCDD exposures
were observed in humans, the species of concern whose health protection is represented by the
RfD, eliminating the uncertainty associated with interspecies extrapolation. The cohort members
who were evaluated included infants (exposed in utero) and adults who were exposed when they
were less than 10 years of age. The inclusion of these studies among the RfDs derived also may
characterize noncancer health effects associated with TCDD exposures in potentially vulnerable
populations, thus accounting for some part of the intraspecies uncertainty in the RfD. Finally,
the two virtually identical RfDs from different endpoints in the Baccarelli et al. (2008, 197059)
and Mocarelli et al. (2008, 199595) studies provide an additional level of confidence in the use
of these data for derivation of the RfD for TCDD.

Although the human data are preferred, Figure ES-5 presents a number of animal studies
with RfDs that are lower than the human RfDs. To a large extent, this is expected because a
10-fold interspecies uncertainty factor is generally used to extrapolate from test-animal species to
humans, intended to provide a conservative estimate of an RfD that would be derived directly
from human data. Two of the rat bioassays among this group of studies—Bell et al. (2007,
197041) and NTP (2006, 197605)—are of particular note. Both studies were recently conducted
and very well designed and conducted, using 30 or more animals per dose group; both also are
consistent with and, in part, have helped to define the current state of practice in the field.

Bell et al. (2007, 197041) evaluated several reproductive and developmental endpoints, initiating
TCDD exposures well before mating and continuing through gestation. NTP (2006, 197605) is
the most comprehensive evaluation of TCDD chronic toxicity in rodents to date, evaluating
dozens of endpoints at several time points in all major tissues. Thus, proximity of the RfDs
derived from these two high quality, recent studies, provide additional support for the use of the
human data for RfD derivation.

5 The candidate RfD for Alaluusua et al. (2004, 1971421 was approximately 2 orders of magnitude higher than the
RfDs for Mocarelli et al. (2008, 1995951 and Baccarelli et al. (2008, 1970591. thus, it was not included as a
co-critical study for the RfD.

6As an example, note the lack of statistically significant effects reported by Baccarelli et al. (2008, 197059: Figure 2
C and D) in regression models based on either maternal plasma levels of non-coplaner PCBs or total TEQ on
neonatal TSH levels.

This document is a draft for review purposes only and does not constitute Agency policy.

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There are several animal bioassay candidate RfDs at the lower end of the RfD range in
Figure ES-5 that are more than 10-fold below the human-based RfDs. Two of these studies
report effects that are analogous to the endpoints reported in the three human studies and support
the RfDs based on human data. Specifically, decreased sperm production in Latchoumydandane
and Mathur (2002, 197498) is consistent with the decreased sperm counts and other sperm
effects in Baccarelli et al. (2008, 197059). and missing molars in Keller et al. (2007, 198526;
2008, 198531; 2008, 198033) are similar to the dental defects seen in Alaluusua et al. (2004,
197142). Thus, because these endpoints have been associated with TCDD exposures in humans,
these animal studies would not be selected for RfD derivation in preference to human data
showing similar effects.

Another characteristic of the remaining studies in the lower end of the candidate RfD
distribution is that they are dominated by mouse studies (comprising 6 of the 8 lowest
rodent-based RfDs). EPA considers the candidate RfD estimates based on mouse data to be
much more uncertain than either the rat or human candidate RfD estimates. The EPA considers
the Emond mouse PBPK model to be the most uncertain of toxicokinetic models used to estimate
the PODs because of the lack of key mouse-specific data, particularly for the gestational
component (see Section 3.3.4.3.2.5). The LOAELreds identified in mouse bioassays are low
primarily because of the large toxicokinetic interspecies extrapolation factors used for mice, for
which there is more potential for error. The ratio of administered dose to HED (Da:HED) ranges
from 65 to 1,227 depending on the duration of exposure. The Da:HED for mice is, on average,
about four times larger than that used for rats. In addition, each one of the mouse studies has
other qualitative limitations and uncertainties that make them less desirable candidates as the
basis for the RfD than the human studies.

The most relevant human PODs are based on the Baccarelli et al. (2008, 197059) and
Mocarelli et al. (2008, 199595) studies, which exhibited similar LOAELs of 0.024 and
0.020 ng/kg-day, respectively. For Baccarelli et al. (2008, 197059). EPA defined a LOAEL as
the group mean of 39 ppt TCDD in neonatal plasma which corresponds to thyroid-stimulating
hormone (TSH) values above 5 |iU/mL. The World Health Organization (WHO, 1994)
established the 5 |iU/mL standard as an indicator of potential iodine deficiency and potential
thyroid problems in neonates. Increased TSH levels are indicative of decreased thyroid hormone
(T4 and/or T3) levels. For TCDD, the toxicological concern is not likely to be iodine uptake

This document is a draft for review purposes only and does not constitute Agency policy.

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inhibition, but rather increased metabolism and clearance of T4, as evidenced in a number of
animal studies (e.g., Seo et al., 1995, 197869). Clinically, a TSH level of >4 |iU/mL in a
pregnant woman is followed up by an assessment of free T4, and treatment with L-thyroxine is
prescribed if T4 levels are low (Glinoer and Delange, 2000). This is to ensure a sufficient supply
of T4 for the fetus, which relies on maternal T4 exclusively during the 1st half of pregnancy
(Chan et al., 2005; Morreale de Escobar et al., 2000; Calvo et al., 2002). Adequate levels of
thyroid hormone also are essential in the newborn and young infant as this is a period of active
brain development (Glinoer and Delange, 2000; Zoeller and Rovet, 2004). Thyroid hormone
disruption during pregnancy and in the neonatal period can lead to neurological deficiencies.

Baccarelli et al. (2008, 197059) showed, in graphical form, how the TSH distribution in
each of three categorical exposure groups (reference, zone A, and zone B—representing
increasing TCDD exposure) shifted to higher TSH values with increasing exposure. The
individuals comprising the above 5 |iU/mL group were from all three categorical exposure
groups, not just from the highest exposure group. Therefore, EPA was able to designate a
LOAEL independently of the nominal categorical exposure groups for TSH values above
5 |iU/mL. Baccarelli et al. (2008, 197059) did not estimate the equivalent oral intake associated
with TCDD serum concentrations, rather they provided neonatal serum TCDD concentrations for
the groups above and below 5 |iU/mL. EPA estimated the maternal intake at the LOAEL from a
maternal serum-TCDD/TSH regression model presented in Baccarelli et al. (2008, 197059) by
estimating the maternal TCDD lipid adjusted serum concentration (LASC) at which neonatal
TSH exceeded 5 |iU/mL. EPA then used the Emond PBPK model to estimate the continuous
daily TCDD intake that would result in this TCDD LASC. The resulting predicted maternal
daily intake rate established the LOAEL (0.024 ng/kg-day). EPA did not defined a NOAEL
because it is not clear what maternal intake should be assigned to the group below 5 |iU/mL.

For Mocarelli et al. (2008, 199595). EPA defined a LOAEL as the lowest exposed group
mean of 68 ppt (lst-quartile) corresponding to decreased sperm concentrations (20%) and
decreased motile sperm counts (11%) in men who were 1-9 years old at the time of the Seveso
accident (initial TCDD exposure event). Although a decrease in sperm concentration of
20% likely would not have clinical significance for an individual, EPA's concern is that such
decreases associated with TCDD exposures could lead to shifts in the distributions of these
measures in the general population. Such shifts could result in decreased fertility in men at the

This document is a draft for review purposes only and does not constitute Agency policy.

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low end of these population distributions. In the group exposed due to the Seveso accident,
individuals one standard deviation below the mean are just above the cut-off used by clinicians
(20 million/ml) to indicate follow-up for potential reproductive impact in affected individuals,
indicating that a number of individuals in the exposed group likely had sperm concentrations less
than 20 million/ml; EPA could not obtain the individual data to determine the exact number of
men in this category. EPA judged that the impact on sperm concentration and quality reported
by Mocarelli et al. (2008, 199595) is biologically significant given the potential for functional
impairment as a consequence of potential shifts in the distribution of these male fertility
measures in an exposed population.

For Mocarelli et al. (2008, 199595). TCDD LASC- levels were measured within
approximately one year of the initial exposure event. Because effects were only observed in men
who were under 10 years of age at the time of exposure, EPA assumed a maximum 10-year
critical exposure window for elicitation of these effects. EPA has estimated a continuous daily
oral intake of 0.020 ng/kg-day associated with the designated LOAEL from the lowest exposure
group (68 ppt), (see Section 4.2.3.2). The reference group is not designated as aNOAEL
because there is no clear zero-exposure measurement for any of these endpoints, particularly
considering the contribution of background exposure to DLCs, which futher complicates the
interpretation of the reference group response as a true "control" response (see discussion in
Section 4.4). However, males less than 10 years old can be designated as a sensitive population
by comparison to older males who were not affected.

The two human studies, Baccarelli et al. (2008, 197059) and Mocarelli et al. (2008,
199595). have similar LOAELs of 0.024 and 0.020 ng/kg-day, respectively. Together, these
two studies constitute the best foundation for establishing a POD for the RfD, and are designated
as co-principal studies. Therefore, increased TSH in neonates (Baccarelli et al., 2008, 197059)
and male reproductive effects (decreased sperm count and motility) are designated as cocritical
effects. Although the exposure estimate used in determination of the LOAEL for Mocarelli et al.
(2008, 199595) is more uncertain than the Baccarelli et al. (2008, 197059) exposure estimate, the
slightly lower LOAEL of 0.020 ng/kg-day from Mocarelli et al. (2008, 199595) is designated as
the POD.

EPA used a composite UF of 30 for both studies. EPA applied a factor of 10 for UFL to
account for lack of a NOAEL. EPA also applied a factor of 3 (10°5) for UFH to account for

This document is a draft for review purposes only and does not constitute Agency policy.

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human interindividual variability because the effects were elicited in sensitive populations. A
further reduction to 1 was not made because the sample sizes in these two epidemiologic studies
were relatively small, which, combined with uncertainty in exposure estimation, may not fully
capture the range of interindividual variability. The resulting RfD for TCDD in standard units is
7 x 10~10 mg/kg-day.

WEIGHT-OF-EVIDENCE STATEMENT FOR CARCINOGENICITY

The NAS recommended that EPA update its cancer classification for TCDD and the
weight-of-evidence (WOE) statement to reflect the current state of the science and incorporate
the latest EPA Cancer Guidelines (U.S. EPA, 2005, 086237). Several notable new studies
addressing TCDD's carcinogenic potential have been published since the release of EPA's
2003 Reassessment, including several new studies of the Seveso epidemiologic cohort and an
NTP 2-year cancer bioassay in female rats (NTP, 2006, 197605).

Under the 2005 Guidelines for Carcinogen Risk Assessment (U.S. EPA, 2005, 086237)
TCDD is characterized as carcinogenic to humans, based on the available data as of 2009 (see
Section 5.1.2). When evaluating the carcinogenic potential of a compound, EPA employs a
WOE approach in which all available information is evaluated and considered. In the case of
TCDD, EPA based the classification on numerous lines of evidence, including: multiple
occupationally- and accidentally-exposed epidemiologic cohorts showing an association between
TCDD exposure and certain cancers or increased mortality from all cancers; extensive evidence
of carcinogenicity at multiple tumor sites in both sexes of multiple species of experimental
animals; consensus that the mode of TCDD's carcinogenic action in animals involves aryl
hydrocarbon receptor (AhR)-dependent key precursor events and proceeds through modification
of one or more of a number of cellular processes; the human AhR and rodent AhR are similar in
structure and function, and human and rodent tissue and organ cultures respond to TCDD in a
similar manner and at similar concentrations; and general scientific consensus that AhR
activation is anticipated to occur in humans and may progress to tumors.

Most evidence suggests that the majority of toxic effects of TCDD are mediated by
interaction with the AhR. EPA considers interaction with the AhR to be a necessary, but not
sufficient, event in TCDD carcinogenesis. Although AhR binding and activation by TCDD is
considered to be a key event in TCDD carcinogenesis, the sequence of key events following AhR

This document is a draft for review purposes only and does not constitute Agency policy.

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activation that ultimately leads to the development of cancer is unknown (See Section 5.1.2.3).
Therefore, EPA has determined that TCDD's mode of action, as defined by the 2005 Cancer
Guidelines, is unknown. Since the mode of action for TCDD carcinogenesis is not known, EPA
has used a low dose linear extrapolation approach in the development of a cancer oral slope
factor.

DERIVATION OF CANDIDATE OSFs FROM EPIDEMIOLOGIC STUDIES AND
ANIMAL BIOASSAYS

In response to the NAS concerns that EPA evaluate data published since the
2003 Reassessment and better justify its approach to cancer dose-response modeling, EPA has
developed candidate OSFs using epidemiologic studies and animal bioassays for TCDD,
including both new evaluations of data from the 2003 Reassessment and also the assessment of
new studies. The BMR level that has been used for the POD in deriving the cancer OSF is
one percent extra risk, which is close to the observable response data for most data sets and,
therefore, best represents low dose cancer risks (see Section 5.2.3.2.6.11). EPA has chosen a
single BMR for consistency across studies.

There are several well-studied occupationally-exposed epidemiologic cohorts showing an
association between TCDD and increased all-cancer mortality, and several epidemiologic
cohorts exposed to TCDD as a consequence of industrial accidents showing an association
between TCDD and cancer or cancer mortality (see Section 5.2.3.1). The 2003 Reassessment
included cancer dose-response analyses based on the following three occupational cohorts: the
NIOSH cohort, an occupational cohort subject to chronic TCDD exposures (Steenland et al.,
2001, 197433); the Hamburg cohort, an occupational cohort also subject to chronic TCDD
exposures (Becher et al., 1998, 197173); and the BASF cohort, an occupational cohort subject to
peak TCDD exposures through clean-up following an industrial accident (Ott and Zober, 1996,
198101). In this document, EPA determined that each of these studies met the epidemiologic
study inclusion criteria. Thus, after further evaluating the OSFs presented in the 2003
Reassessment for these three studies, EPA accepted those OSF estimates and retained them as
candidate OSFs in this document. These OSF estimates are arrayed in Figure ES-6, along with
the other OSFs calculated by EPA in this document. EPA also determined that three additional
studies met the epidemiologic study inclusion criteria: Cheng et al. (2006, 523122) and Collins

This document is a draft for review purposes only and does not constitute Agency policy.

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et al. (2009, 197627) (NIOSH cohort) and Warner et al. (2002, 197489) (Seveso cohort). EPA
determined that the data presented in Collins et al. (2009, 197627) were not sufficient to derive
an OSF, and EPA was unable to derive a credible OSF from the data presented by Warner et al.
(2002, 197489) (see discussions in Section 5.2.3.1).

EPA did derive an OSF from Cheng et al. (2006, 523122). as detailed in Text Box ES-1.
In Table ES-1, EPA presents estimates of OSFs for specific TCDD intake rates based on target
risk levels of 1 10 2, through 1 x icr7 based on Cheng et al. (2006, 523122). Note that there
are two nonlinear steps in the estimation of risk-specific doses from the Cheng et al. model.

First, fat-AUC (AUCrl) and the incremental cancer mortality risk (RD) do not have a linear
relationship (Equation 5-4); however, the relationship becomes virtually linear below an
incremental risk of 10 3 (see Table ES-1). Second, TCDD fat concentration is not linear with
oral intake in the Emond human PBPK model (see Section 3); this relationship also is close to
linear below the 10 5 risk level. The resulting predicted cancer-mortality risk is approximately
linear with daily oral intake at low doses.

EPA also identified candidate OSFs for TCDD from key animal bioassays (see
Section 5.2.3.2). Based on the inclusion criteria, EPA selected five key rodent cancer bioassays
suitable for quantitative dose-response assessment. These included Delia Porta et al. (1987,
197405). Kociba et al. (1978, 001818). NTP (1982, 54J /o4). and Toth et al. (1979, 197109) that
were evaluated in the 2003 Reassessment, and the new NTP (2006, 197605) rat chronic bioassay.
EPA conducted dose-response modeling for each tumor type separately (individual tumor
models) as well as for composite tumor incidence (multiple tumor models). The tumor types that
EPA analyzed are shown in Table ES-2.

For each in vivo animal cancer study that qualified for TCDD dose-response assessment,
EPA selected the species/sex/tumor dataset combinations characterized as having statistically
significant increases in tumor incidences, then used the Emond rodent PBPK model to estimate
blood concentrations corresponding to each study's average daily administered dose for use in
dose-response modeling. BMDLois were then estimated for the blood concentration by
two different methodologies: (1) using the multistage cancer model for each species/sex/tumor
combination within each study, and (2) using a Bayesian Markov Chain Monte Carlo framework
that assumes independence of tumors, modeling all tumors together for each species/sex

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Text Box ES-1. OSF Calculations Using Cheng et al. (2006,523122) Information.

To develop cancer risks for TCDD, EPA used the modeling results of the Cheng analysis, with conversion to
oral intake using the Emond human PBPK model as follows. The slope (/;) from the Cheng analysis is the slope of
the linear relationship between the natural logarithm of the rate ratio (RR) and the cumulative fat TCDD
concentration (fat-AUC). Conceptually, the slope ((3) is similar to an OSF, except that it is expressed in terms of
fat-AUC rather than intake. Also, the slope represents the incremental increase in cancer mortality (expressed as an
RR) above the background TCDD exposure experienced by the NIOSH cohort rather than above zero. Using the
upper 95% bound on /; and assuming that the slope is the same below the NIOSH cohort background exposure level
(approximately 5 ppt/yr TCDD fat concentration), EPA calculated risk-specific doses (as daily oral intakes) for
TCDD for risk levels of concern to EPA. The risk-specific doses were estimated from the Emond human PBPK
model for the lifetime-average TCDD fat concentrations corresponding to the fat-AUC predicted by the Cheng et al.
model for each of the risk levels of concern. The steps in this computation are as follows:

•	Background cancer mortality risk estimate (Rn). EPA used an Ru of 0.112 as reported by Cheng et al. (2006,

523122)

•	Total cancer mortality risk in the exposed group associated with a specified (extra) risk level (RL) of fatal
cancer (TRm). A TRm_ associated with any given extra risk level (e.g., 0.01, 1 x 10"6) can be calculated using
the following relationship for extra risk:

ER = ——	(Eq. ES-1)

1 -R,

•	Incremental cancer mortality risk in the exposed population based on a given extra risk (Rn). RD, is
calculated as the difference between the total risk and background risk and expressed in terms of RL and R0
by combining Equations ES-2 and ES-1.

Rd = TRrl — R0	(Eq. ES -2)

Rd = RL*(1-R0)	(Eq. ES-3)

•	Cumulative TCDD concentration in the fat compartment for a given extra risk (AUCpi_). AUCrl is then
calculated by taking the natural logarithm of Equation 3 from Cheng et al. (2006, 523122). rearranging and
substituting for RR1 (RR = |/<7, + R„\/Ru)'.

A UCk, = In((Rd + Rq)/R0)/P*	(Eq. ES -4)

where /;* is the central-tendency regression slope or the 95% upper bound (fios) determined by summing the
regression coefficient ((3) and the product of 1.96 and the standard error of the regression coefficient,
yielding an estimate of 6.0 x 10 6 per ppt-year lipid adjusted serum TCDD, as follows:

P95 = P + \.96* SE	(Eq. ES -5)

•	Continuous daily TCDD intake associated with a given extra risk I Dm 1. Because the fat concentrations
generated by CADM are not linear with oral exposure at higher doses, a single oral slope factor to be used
for all risk levels cannot be obtained; the response is approximately linear with fat concentrations and oral
intake at lower doses. Instead, a risk-specific Drl must be estimated by converting the respective AUCrl to
the corresponding lifetime daily intake, using an appropriate human toxicokinetic model. EPA has chosen to
use the Emond human PBPK model for this purpose because the CADM configuration does not facilitate this
process and so that the dose conversions are consistent with those used in the derivation of the RfD. A Drl
is obtained from the Emond model by finding the average lifetime daily intake corresponding to the AUCrl
in the fat compartment.

This document is a draft for review purposes only and does not constitute Agency policy.

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combination within each study. The final selected models were subjected to goodness-of-fit tests
and visual inspection of fit to the raw data. Thus, for each sex/species combination within each
study, EPA generated a BMDLoi for each single tumor type and another BMDL0i for the
combined tumors. Using the Emond human PBPK model, BMDLredS were then calculated for
each of the BMDLois, and using a linear extrapolation, OSFs were calculated by
OSF = 0.01/BMDLred The highest OSF for a species/sex combination for either a single tumor
type or all combined tumors was selected as a candidate OSF. The OSF candidates from the key
animal bioassays are shown in Table ES-2.

DERIVATION OF TCDD ORAL SLOPE FACTOR AND RISK ESTIMATES

EPA was able to derive OSFs for tumor incidence data from five animal cancer
bioassays, as well as for cancer mortality data from four epidemiological cohort studies that were
selected for TCDD dose-response modeling using the study inclusion criteria (see Section 5.3).
These OSFs are arrayed in Figure ES-6. For the animal data, OSFs based on individual tumors
were developed for 28 study/sex/endpoint combinations, and the results ranged from 1.8 x io4 to
5.8 x 106 (per mg/kg-day). The OSFs based on combined tumors were developed for
seven study/sex combinations, and the results ranged from 3.2 x 105 to 9.4 x 106 (per
mg/kg-day). EPA also developed OSFs based on four epidemiologic studies from three cohorts,
ranging from 3.75 x 105 to 2.5 x 106 (per mg/kg-day).

EPA has chosen to use the human data over the animal data as recommended by expert
panelists at EPA's 2009 Dioxin Workshop (U.S. EPA, 2009, 522927) and in the 2005 Cancer
Guidelines (U.S. EPA, 2005, 086237). OSFs derived from the human data are consistent with
the animal bioassay results; human OSFs fall within the same range as the animal bioassay
OSFs.

Among the human studies, the occupational TCDD exposures in the NIOSH and
Hamburg cohorts are assumed to be reasonably constant over the duration of occupational
exposure. In contrast, the TCDD exposure pattern for the Seveso and BASF accidents is acute,
high dose, followed by low-level background exposure. Such exposure patterns similar to those
experienced by the BASF and Seveso cohorts have been shown to yield higher estimates of risk
when compared to constant exposure scenarios with similar total exposure magnitudes (Kim
et al„ 2003, 199146: Murdoch and Krewski, 1988, 548718: Murdoch et al„ 1992, 548719).

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Thus, EPA has judged that the NIOSH and Hamburg cohort response data are more relevant than
the BASF and Seveso data for assessing cancer risks from continuous ambient TCDD exposure
in the general population.

The NIOSH (Steenland et al., 2001, 197433; Cheng et al., 2006, 523122) and Hamburg
(Becher et al., 1998, 197173) cohort studies report cumulative TCDD levels in the serum for
cohort members. The most significant difference among the Cheng et al. (2006, 523122)
analysis and those of Steenland et al. (2001, 197433) and Becher et al. (1998, 197173) is the
method used to back-extrapolate exposure concentrations based on serum TCDD measurements.
Steenland et al. (2001, 197433) and Becher et al. (1998, 197173) back-extrapolated exposures
and body burdens using a first-order model with a constant half-life. In contrast, Cheng et al.
(2006, 523122) back-extrapolated body burdens using a kinetic modeling approach that
incorporated concentration- and age-dependent elimination kinetics.

Although all three of these are high-quality studies, the kinetic modeling used by Cheng
et al. (2006, 523122) is judged to better reflect TCDD pharmacokinetics, as currently
understood, than the first-order models used by Steenland et al. (2001, 197433) and Becher et al.
(1998, 197173). EPA believes that the representation of physiological processes provided by
Cheng et al (2006, 523122) is more realistic than the assumption of simple first-order kinetics
and this outweighs the attendant modeling uncertainties. Furthermore, the use of kinetic
modeling is consistent with recommendations both by the NAS and the Dioxin Workshop panel.

EPA, therefore, has decided to use the results of the Cheng et al. (2006, 523122) study for
derivation of the TCDD OSF based on total cancer mortality as calculated by EPA using data
and models from the Cheng et al. (2006, 523122) study, as described in Section 5.2.3.1.2.
Although the OSF is only strictly defined for exposures above the background exposure
experienced by the NIOSH cohort, which was assumed to be 0.5 pg/kg-day TCDD, or
5 pg/kg-day total TEQ, EPA assumes that the slope (risk vs. blood concentration) is the same
below those background exposure levels as it is above. Table ES-1 shows the oral slope factors
at specific target risk levels (OSFRLs) which range from 1.1 x 105 to 1.3 x 106 per (mg/kg-day).
EPA recommends the use of an OSF of 1 x 106 per (mg/kg-day) when the target risk range is 10 5
to 10 7.

This document is a draft for review purposes only and does not constitute Agency policy.

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CONSIDERATION OF NONLINEAR DOSE-RESPONSE APPROACHES FOR
CANCER

The NAS focused much of its review on EPA's derivation of a cancer slope factor,
commenting extensively on the extrapolation of dose-response modeling below the POD. The
NAS questioned EPA's choice of a linear, nonthreshold model for extrapolating risk associated
with exposure levels below the POD, concluding that the current scientific evidence was
sufficient to justify the use of nonlinear methods when extrapolating below the POD for dioxin
carcinogenicity.

While, based on the 2005 Cancer Guidelines, EPA deemed linear extrapolation to be
most appropriate for TCDD, EPA carefully considered the NAS recommendation to provide risk
estimates using both linear and nonlinear methods. In this document, EPA has evaluated the
information available for identifying a threshold and for estimating the shape of the
dose-response curve below the POD (see Section 5.2.3.4). EPA presents a hypothetical sublinear
dose-response modeling example of rodent carcinogenicity. EPA also presents two illustrative
examples of RfD development (i.e., nonlinear method) for carcinogenic effects of TCDD, using
data derived from animal bioassays. EPA derives illustrative RfDs for cancer based on
combined tumor response and also on hypothesized key events in TCDD's MOA for female rat
liver and lung tumors. EPA identifies a number of limitations that prevent making strong
conclusions based on the nonlinear dose-response modeling exercises.

FEASIBILITY OF QUANTITATIVE UNCERTAINTY ANALYSIS

EPA also addresses the third key recommendation of the NAS, specifically, improving
transparency, thoroughness, and clarity in quantitative uncertainty analysis (see Section 6). In
summary, NAS suggested that EPA should

•	describe and define (quantitatively to the extent possible) the variability and
uncertainty for key assumptions used for each key endpoint-specific risk
assessment (choices of data set, POD, model, and dose metric),

•	incorporate probabilistic models to the extent possible to represent the range of
plausible values,

•	clearly state it when quantitation is not possible and explain what would be
required to achieve quantitation (NAS, 2006, 198441. p. 9).

This document is a draft for review purposes only and does not constitute Agency policy.

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1	Although the NAS summarized the shortfalls in the 2003 Reassessment categorically, the

2	elaborations within their report often contain the qualification "if possible" and do not take a

3	position with regard to the feasibility of many suggestions. With appreciation for the extent of

4	information available for dioxin, EPA's goal herein was to examine the feasibility of a

5	data-driven quantitative uncertainty analysis for TCDD dose-response assessment.

6	In examining feasibility of quantitative uncertainty analysis, EPA recognized that

7	different kinds of uncertainty require different statistical treatment. Cognitive uncertainty

8	concerns uncertainty that can be expressed as probabilities and may be operationalized using

9	either frequentist or Bayesian approaches. For example, classical statistical methods yield

10	distributions on model parameters which reflect sample fluctuations, assuming that the model is

11	true. This type of uncertainty can be taken into account in the BMDL estimation. Also, for

12	TCDD epidemiologic data, the dose reconstruction often involves assumptions that may be

13	amenable to data-driven uncertainty analysis if sufficient data can be retrieved; back-

14	extrapolated TCDD levels, biological half-life, body fat, and background levels are example

15	variables that could be included in such an analysis. In addition, a Monte Carlo analysis has

16	been examined to develop quantitative uncertainty distributions for the RfD (e.g., Swartout et al.,

17	1998, 093460). Given a set of animal bioassay data, quantifying dose-response uncertainty may

18	be approached in different ways. The differences reflect different types of uncertainty that are

19	captured. A recent evaluation enumerates the following possible methodologies (Bussard et al.,

20	2009, 543770V

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Benchmark Dose Modeling (BMD): Choose the 'best' model, and
assess uncertainty assuming this model is true. Supplemental results can compare
estimates obtained with different models, and sensitivity analyses can investigate
other modeling issues.

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Probabilistic Inversion with Isotonic Regression (PI-IR): Define
model-independent 'observational' uncertainty, and look for a model that captures
this uncertainty by assuming the selected model is true and providing for a
distribution over its parameters.

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31

32

33

Non-Parametric Bayes (NPB): Choose a prior mean response (potency)
curve (potentially a "non-informative prior") and a precision parameter to express
prior uncertainty over all increasing dose-response relations, and update this prior
distribution with the bioassay data.

This document is a draft for review purposes only and does not constitute Agency policy.

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Bayesian Model Averaging (BMA) (as considered here): Choose an
initial set of models, and then estimate the parameters of each model with
maximum likelihood. Use classical methods to estimate parameter uncertainty,
given the truth of the model. Determine a probability weight for each model
using the Bayes Information Criterion (BIC), and use these weights to average the
model results.

The first of the above methods involves standard classical statistical methods and captures
sampling uncertainty conditional on the truth of the model used. The other methods are "exotic"
in the sense that they attempt to capture uncertainty that is not conditional on the truth of a given
model. In this response document, EPA has not applied such methods, but recognizes that
quantitative uncertainty analysis is possible in these cases.

In contrast to cognitive uncertainty, Volitional uncertainty concerns uncertainty regarding
choices on the best course of action to take; volitional uncertainty cannot be analyzed by
sampling from a probability distribution and, thus, is not amenable to a complete quantitative
uncertainty analysis. Some of the choices made in TCDD dose-response assessment that are
volitional include: choice of occupational cohort data set or bioassay data set; choice of PODs
(e.g., EDoi, EDos, and EDio); choice of species, strain, or sex within an animal bioassay; and
choice of dose metric (e.g., administered doses, blood concentrations, lipid-adjusted serum
concentrations). These volitional uncertainties cannot be quantified by sampling an input
distribution.

Although EPA has determined that a comprehensive quantitative uncertainty analysis is
not feasible because of the limitations discussed above, EPA believes the NAS was requesting
that dose-response modeling results be shown for specific choices of interest to TCDD
assessment. In response to the NAS concerns, this document provides some limited quantitative
comparisons. BMDs, BMDLs, and OSFs from the animal cancer bioassay benchmark dose
modeling assuming 1, 5, and 10% extra risk are compared in units of blood concentrations and
human equivalent doses (see Tables 5-18 and 5-19, respectively). In addition, central tendency
slope estimates and upper bound slope factor estimates based on Cheng et al. (2006, 523122) are
presented (see Tables 5-3 and 5-4). For the noncancer effects, key animal study PODs
(ng/kg-day) are shown based on different dose metrics: administered dose, first-order body
burden HED, and blood concentration (Tables 4-3 and 4-4). EPA has undertaken some limited
quantitative uncertainty analyses for the kinetic modeling, presenting a sensitivity analysis and

This document is a draft for review purposes only and does not constitute Agency policy.

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uncertainty analysis in dose metrics derived for the risk assessment of TCDD and a detailed
discussion on the uncertainty in choice of PBPK model-driven dose metrics, (see Sections 3.3.3
and 3.3.5). TCDD kinetic doses from the Emond et al. (2005, 197317: 2006, 1973161 PBPK
model that is primarily used in the technical analysis in this document are compared with those
predicted by the Ay 1 ward et al. (2005, 197114) model.

Uncertainty quantification is an emerging area in science. There are many examples of
highly vetted and peer-reviewed uncertainty analyses based on structured expert judgment.

Under this process, experts in effect synthesize a wide diversity of information in generating
their subjective probability distributions. Where considerable data exist for an environmental
pollutant, such as for the well-studied TCDD, it is natural to ask whether these extensive data can
be leveraged more directly in uncertainty quantification. This is an area where research could be
focused. Additional research topics relevant to dioxin that could further inform health
assessments include population variability of biokinetic constants and threshold mechanisms for
the mass action model. Further data and improved methodologies in these areas, combined with
developments illustrated elsewhere in this report, will help reduce or better quantify uncertainties
and strengthen EPA's understanding of potential health implications of environmental TCDD
exposures.

This document is a draft for review purposes only and does not constitute Agency policy.

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Table ES-1. Comparison of fat concentrations, risk specific dose estimates
and equivalent oral slope factors based on upper 95th percentile estimate of
regression coefficient3 of all fatal cancers reported by Cheng et al. (2006,
523122) for selected risk levels

Risk level
(RL)

AUCrl
(ppt-yr)

FATrL
(ng/kg)

Risk specific doseb
(Drl) (ng/kg-day)

Equivalent oral slope
factors (OSFrl) per
(mg/kg-day)

1 x 1(T2

1.262 x 104

1.803 x 102

8.79 x 10~2

1.1 x 105

5 x l(T3

6.432 x 103

9.189 x 101

3.14 x 10~2

1.6 x 105

1 x l(T3

1.307 x 103

1.867 x 101

2.88 x 10~3

3.5 x 105

5 x l(T4

6.546 x 102

9.352 x 10°

9.56 x 10~4

5.2 x 105

1 x l(T4

1.311 x io2

1.873 x 10°

1.29 x 10~4

7.8 x 105

5 x l(T5

6.558 x 101

9.368 x 10"1

5.52 x 10~5

9.1 x 105

1 x l(T5

1.312 x 101

1.874 x 10_1

8.94 x 10~6

1.1 x 106

5 x l(T6

6.559 x 10°

9.370 x 10"2

4.25 x 10~6

1.2 x 106

1 x 10~6

1.312 x 10°

1.874 x 10~2

8.08 x 10~7

1.2 x 106

5 x l(T7

6.559 x 10"1

9.370 x 10"3

4.00 x 10~7

1.3 x 106

1 x l(T7

1.312 x KT1

1.874 x 10~3

7.92 x 10~8

1.3 x 106

'Based on regression coefficient of Cheng et al. (2006, 523122. Table III), excluding observations in the upper 5%
range of the exposures; where reported (3 = 3.3 x 10 6 ppt-years and standard error = 1.4 x 10 6. Upper 95th
percentile estimate of regression coefficient (p95) calculated to be 6.04 x 10 6 = (3.3 x 10 6) + 1.96 x (1.4 x 10 6);
background cancer mortality risk is assumed to be 0.112 as reported by Cheng et al. (2006, 5231221.
bTo calculate the extra cancer risk (ER) and OSF for any TCDD daily oral intake (D):

1.	For D in ng/kg-d, look up the corresponding fat concentration (ng/kg = ppt) from the conversion chart
(nongestational lifetime dose metrics) in Appendix C.4.1.

2.	Calculate the AUC in ppt-yrs by multiplying the fat concentration by 70 years.

3.	Calculate Extra Risk (ER) using the following equation:

ER = [exp(AUC x 6.04E-6) x 0.112 - 0.112] - 0.888.

4.	Calculate the OSF (mg/kg-d)"1 = 1E6 x (ER D).

Example for risk at the RfD: D = 7 x 10"4 ng/kg-d; fat concentration = 6.93 ng/kg;

AUC = 70 years x 6.93 ppt = 485 ppt-year;

ER = exp(485 ppt-year x 6.04E-6 (ppt-yr)"1) x 0.112 - 0.112) 0.888 = 3.7 x 10"4
OSF = 1E6 ng/mg x (3.7 x io~4 + 7 x io-4 ng/kg-d) = 5.3 x 105 (mg/kg-d)"1.

This document is a draft for review purposes only and does not constitute Agency policy.

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Table ES-2. Tumor points of departure and oral slope factors using blood
concentrations

Study

Sex/species: tumor sites

BMDLmmn"
(ng/kg-day)

OSF
(per mg/kg-day)

NTP, (1982,
543764)

Male mice: liver adenoma and carcinoma,
lung

1.1E-03

9.4E+6

Toth et al.,
CI 979. 197109")

Male mice: liver tumors

1.9E-03

5.2E+6

NTP, (1982,

543764")

Female mice: liver adenoma and carcinoma,
thyroid adenoma, subcutaneous
fibrosarcoma, all lymphomas

5.3E-03

1.9E+6

NTP, (1982,

543764")

Female rats: liver neoplasitc nodules, liver
adenoma and carcinoma, adrenal cortex
adenoma or carcinoma, thyroid follicular cell
adenoma

5.7E-03

1.8E+6

Kociba et al.,
CI978. 001818")

Female rats: liver adenoma carcinoma, oral
cavity, lung

7.3E-03

1.4E+6

NTP, (1982,

543764")

Male rats: thyroid follicular cell adenoma,
adrenal cortex adenoma

9.6E-03

1.0E+6

Delia Porta et al.,
(1987. 197405")

Male mice: Hepatocellular carcinoma

3.1E-02

3.2E+5

NTP, (2006,

197605")

Female rats: liver cholangiocarcinoma,
hepatocellular adenoma, oral mucosa
squamous cell carcinoma, lung cystic
keratinizing epithelioma, pancreas adenoma,
carcinoma

2.3E-02

4.4E+5

Kociba et al.,
(1978. 001818")

Male rats: adrenal cortex adenoma, tongue
carcinoma, nasal/palate carcinoma

3.1E-02

3.2E+5

¦'BMDL|n., :,s arc from the multiple tumor analyses, with the exception of Toth et al. (1979, 1971091 and Delia Porta
et al. (1987, 1974051 which are the result of modeling single tumor sites.

This document is a draft for review purposes only and does not constitute Agency policy.

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Figure ES-1. EPA's process to evaluate available epidemiologic studies using
study inclusion criteria for use in the dose-response analysis of TCDD. EPA

applied its TCDD-specific epidemiologic study inclusion criteria to all studies
published on TCDD and DLCs. The studies were initially evaluated using
five considerations regarded as providing the most relevant kind of information needed
for quantitative human health risk analyses. For each study that was published in the
peer-reviewed literature, EPA then examined whether the exposures were primarily to
TCDD and if the TCDD exposures could be quantified so that dose-response analyses
could be conducted. Finally, EPA required that the effective dose and oral exposure
be estimable: (1) for cancer, information is required on long-term exposures, (2) for
noncancer, information is required regarding the appropriate time window of exposure
that is relevant for a specific, nonfatal health endpoint, and (3) for all endpoints, the
latency period between TCDD exposure and the onset of the effect is needed. Only
studies meeting these criteria were included in EPA's TCDD dose-response analysis.

This document is a draft for review purposes only and does not constitute Agency policy.

lv	DRAFT—DO NOT CITE OR QUOTE


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Figure ES-2. EPA's process to evaluate available animal bioassay studies using
study inclusion criteria for use in the dose-response analysis of TCDD. EPA

evaluated all available in vivo mammalian bioassay studies on TCDD. Studies had to be
published in the peer-reviewed literature. Next, to ensure working in the low-dose range
for TCDD dose-response analysis, EPA applied dose requirements to the lowest tested
average daily doses in each study, with specific requirements for cancer (<1 (j,g/kg-day),
and noncancer (<30 ng/kg-day) studies. Third, EPA required that the animals were
exposed via the oral route to only TCDD and that the purity of the TCDD was specified.
Finally, the studies were evaluated using four considerations regarded as providing the
most relevant kind of information needed for quantitative human health risk analyses
from animal bioassay data. Only studies meeting all of these criteria and considerations
were included in EPA's TCDD dose-response analysis.

This document is a draft for review purposes only and does not constitute Agency policy.

lvi	DRAFT—DO NOT CITE OR QUOTE


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Figure ES-4. EPA's process to select and identify candidate PODs from key animal
bioassays for use in noncancer dose-response analysis of TCDD. For each noncancer
endpoint found in the studies that qualified for TCDD dose-response assessment using
the study inclusion criteria, EPA first determined if the endpoint was toxicologically
relevant. If so, EPA determined the NOAEL, LOAEL, and BMDL Human Equivalent
Dose (HED) based on lst-order body burdens for each endpoint. These potential PODs
were examined for statistical relevance and included when the endpoint was observed at
the LOAEL. If the BMDL was less than the LOAEL, and if the endpoint was less than
the minimum LOAEL x 100, EPA then calculated NOAELs, LOAELs, or BMDLs based
on blood concentrations from the Emond rodent PBPK model. Then, for all of the
candidate PODs, HEDs were estimated using the Emond human PBPK model. Finally,
the lowest group of the toxicologically relevant candidate PODs was selected for final
use in derivation of an RfD.

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

lviii DRAFT—DO NOT CITE OR QUOTE


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Cancer Slope Factors for 2,3,7,8-TCDD

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1. INTRODUCTION

Dioxins and dioxin-like compounds (DLCs), including polychlorinated dibenzo-dioxins,
polychlorinated dibenzofurans, and polychlorinated biphenyls are structurally and
toxicologically related halogenated dicyclic aromatic hydrocarbons.7 Dioxins and DLCs are
released into the environment from several industrial sources such as chemical manufacturing,
combustion, and metal processing; from individual activities including the burning of household
waste; and from natural processes such as forest fires. Dioxins and DLCs are widely distributed
throughout the environment and typically occur as chemical mixtures. Additionally, they do not
readily degrade; therefore, levels persist in the environment, build up in the food chain, and
accumulate in the tissues of animals. Human exposure to these compounds occurs primarily
through the ingestion of contaminated foods (Lorber et al., 2009, 543766). although exposures to
other environmental media and by other routes and pathways do occur.

The health effects from exposures to dioxins and DLCs have been documented
extensively in epidemiologic and toxicologic studies. 2,3,7,8-Tetrachlorodibenzo-p-dioxin
(TCDD) is one of the most toxic members of this class of compounds and has a robust
toxicologic database. Characterization of TCDD toxicity is critical to the risk assessment of
mixtures of dioxins and DLCs because it has been selected repeatedly as the "index chemical" to
serve as the basis for standardization of the toxicity of components in a mixture of dioxins and
DLCs. The dose-response information for TCDD is used to evaluate risks from exposure to
mixtures of DLCs (Van et al., 1998, 198345; Van den Berg et al., 2006, 543769; also see the
World Health Organization's Web site for the dioxin toxicity equivalence factors [TEFs]),8
therefore, it is imperative to correctly assess the dose response of TCDD and understand the
uncertainties and limitations therein.

In 2003, the U.S. Environmental Protection Agency (EPA) produced an external review
draft of the multiyear comprehensive reassessment of dioxin exposure and human health effects
entitled, Exposure and Human Health Reassessment of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin
(TCDD) and Related Compounds (U.S. EPA, 2003, 5371221 This draft report, herein called the

For further information on the chemical structures of these compounds, see U.S. EP A (2003, 537122; 2008,

5437741.

8Available at http://www.who.int/ipcs/assessment/tef_update/en/.

This document is a draft for review purposes only and does not constitute Agency policy.

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"2003 Reassessment," consisted of (1) a scientific review of information relating to sources of
and exposures to TCDD, other dioxins, and DLCs in the environment; (2) detailed reviews of
scientific information on the health effects of TCDD, other dioxins, and DLCs; and (3) an
integrated risk characterization for TCDD and related compounds.

In 2004, EPA asked the National Research Council of the National Academy of Sciences
(NAS) to review the 2003 Reassessment. The NAS Statement of Task was as follows

The National Academies' National Research Council will convene an expert committee that will
review EPA's 2003 draft reassessment of the risks of dioxins and dioxin-like compounds to
assess whether EPA's risk estimates are scientifically robust and whether there is a clear
delineation of all substantial uncertainties and variability. To the extent possible, the review will
focus on EPA's modeling assumptions, including those associated with the dose-response curve
and points of departure; dose ranges and associated likelihood estimates for identified human
health outcomes; EPA's quantitative uncertainty analysis; EPA's selection of studies as a basis
for its assessments; and gaps in scientific knowledge. The study will also address the following
aspects of EPA's 2003 Reassessment: (1) the scientific evidence for classifying dioxin as a
human carcinogen; and (2) the validity of the nonthreshold linear dose-response model and the
cancer slope factor calculated by EPA through the use of this model. The committee will also
provide scientific judgment regarding the usefulness of toxicity equivalence factors (TEFs) in
the risk assessment of complex mixtures of dioxins and the uncertainties associated with the use
of TEFs. The committee will also review the uncertainty associated with the 2003
Reassessment's approach regarding the analysis of food sampling and human dietary intake
data, and, therefore, human exposures, taking into consideration the Institute of Medicine's
report Dioxin and Dioxin-Like Compounds in the Food Supply: Strategies to Decrease
Exposure. The committee will focus particularly on the risk characterization section of EPA's
2003 Reassessment report and will endeavor to make the uncertainties in such risk assessments
more fully understood by decision makers. The committee will review the breadth of the
uncertainty and variability associated with risk assessment decisions and numerical choices,
including, for example, modeling assumptions, including those associated with the
dose-response curve and points of departure. The committee will also review quantitative
uncertainty analyses, as feasible and appropriate. The committee will identity gaps in scientific
knowledge that are critical to understanding dioxin reassessment (NAS, 2006, 198441. p. 43,
Box 1-1).

In 2006, the NAS published its review of EPA's 2003 Reassessment entitled Health Risks from
Dioxin and Related Compounds: Evaluation of the EPA Reassessment (NAS, 2006, 198441).

1.1. SUMMARY OF KEY NAS (2006,198441) COMMENTS ON DOSE-RESPONSE
MODELING IN THE 2003 REASSESSMENT

While recognizing the effort that EPA expended to prepare the 2003 Reassessment, the

NAS committee identified three key areas that they believe require substantial improvement to

support a scientifically robust risk assessment. These three key areas are

This document is a draft for review purposes only and does not constitute Agency policy.

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•	transparency and clarity in selection of key data sets for analysis;

•	justification of approaches to dose-response modeling for cancer and noncancer
endpoints; and

•	transparency, thoroughness, and clarity in quantitative uncertainty analysis.

In their Public Summary, the NAS made the following overall recommendations to aid
EPA in addressing their key concerns:

•	EPA should compare cancer risks by using nonlinear models consistent with a receptor
mediated mechanism of action and by using epidemiological data and the new National
Toxicology Program (NTP) animal bioassay data (NTP, 2006, 197605). The comparison
should include upper and lower bounds, as well as central estimates of risk. EPA should
clearly communicate this information as part of its risk characterization (NAS, 2006,
198441. p. 9).

•	EPA should identify the most important data sets to be used for quantitative risk
assessment for each of the four key end points (cancer, immunotoxicity, reproductive
effects, and developmental effects). EPA should specify inclusion criteria for the studies
(animal and human) used for derivation of the benchmark dose (BMD) for different
noncancer effects and potentially for the development of RfD (reference dose) values and
discuss the strengths and limitations of those key studies; describe and define
(quantitatively to the extent possible) the variability and uncertainty for key assumptions
used for each key end-point-specific risk assessment (choices of data set, POD [point of
departure], model, and dose metric); incorporate probabilistic models to the extent
possible to represent the range of plausible values; and assess goodness-of-fit of
dose-response models for data sets and provide both upper and lower bounds on central
estimates for all statistical estimates. When quantitation is not possible, EPA should
clearly state it and explain what would be required to achieve quantitation (NAS, 2006,
198441. p. 9).

•	When selecting a BMD as a POD, EPA should provide justification for selecting a
response level (e.g., at the 10%, 5%, or 1% level). In either case, the effects of this
choice on the final risk assessment values should be illustrated by comparing point
estimates and lower bounds derived from selected PODs (NAS, 2006, 198441. p. 9).

•	EPA should continue to use body burden as the preferred dose metric but should also
consider physiologically based pharmacokinetic modeling as a means to adjust for
differences in body fat composition and for other differences between rodents and
humans (NAS, 2006, 198441. p. 9).

•	Although EPA addressed many sources of variability and uncertainty qualitatively, the
committee noted that the 2003 Reassessment would be substantially improved if its risk
characterization included more quantitative approaches. Failure to characterize

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variability and uncertainty thoroughly can convey a false sense of precision in the
conclusions of the risk assessment (NAS, 2006, 198441. p. 5).

Importantly, the NAS encouraged EPA to calculate an RfD as the 2003 Reassessment
does not contain an RfD derivation. The committee suggested that

... estimating an RfD would provide useful guidance to risk managers to help
them (1) assess potential health risks in that portion of the population with intakes
above the RfD, (2) assess risks to population subgroups, such as those with
occupational exposures, and (3) estimate the contributions to risk from the major
food sources and other environmental sources of TCDD, other dioxins, and DLCs
for those individuals with high intakes (NAS, 2006, 198441, p. 6).

The NAS made many thoughtful and specific recommendations throughout their review;
additional NAS recommendations and comments pertaining to the dose-response assessment of
TCDD will be presented and addressed in various sections throughout this document.

1.2. EPA'S SCIENCE PLAN

In May 2009, EPA Administrator Lisa P. Jackson announced the "Science Plan for
Activities Related to Dioxins in the Environment' ("Science Plan") that addressed the need to
finish EPA's dioxin reassessment and provide a completed health assessment on this high profile
chemical to the American public as quickly as possible.9 The Science Plan states that EPA will
release a draft report that responds to the recommendations and comments included in the NAS
review of EPA's 2003 Reassessment, and that, in this draft report, EPA's National Center for
Environmental Assessment, Office of Research and Development, will provide a limited
response to key comments and recommendations in the NAS report (draft response to comments
report). This draft response is to focus on dose-response issues raised by the NAS and include
analyses of relevant new key studies. The draft response is to be provided for public review and
comment and for independent external peer review by EPA's Science Advisory Board.
Following completion of this report, EPA is to review the impacts of the response to comments
report on its 2003 Reassessment.

9Available at http://www.epa.gov/dioxin/scienceplan.

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This draft document comprises EPA's report that responds both directly and technically
to the recommendations and comments on TCDD dose-response assessment included in the NAS
review of EPA's 2003 Reassessment. This document focuses on TCDD only. Because new data
are analyzed in this report and toxicity values are derived, this document will follow the IRIS
process for review, clearance and completion; however, it is not a traditional IRIS document.
Information developed in this document is intended to not only respond to the NAS review, but
also to expand EPA's knowledge of TCDD cancer and noncancer dose-response based on the
most current literature, existing methods, and adherence to EPA risk assessment guidance
documents. Following completion of this document, EPA will consider its contents as it reviews
the TCDD risk assessment information presented in the 2003 Reassessment and moves forward
towards completion of the dioxin reassessment.

1.3. OVERVIEW OF EPA'S RESPONSE TO NAS (2006,198441) "HEALTH RISKS
FROM DIOXIN AND RELATED COMPOUNDS: EVALUATION OF EPA's 2003
REASSESSMENT"

In their key recommendations, the NAS commented that EPA should thoroughly justify
and communicate approaches to dose-response modeling, increase transparency in the selection
of key data sets, and improve the communication of uncertainty (particularly quantitative
uncertainty). They also encouraged EPA to calculate an RfD. These main areas of improvement
refer to issues specifically related to TCDD dose-response assessment (and uncertainty analysis);
therefore, as noted in the Science Plan, EPA's response to the NAS is particularly focused on
these issues.

EPA thoroughly considered the recommendations of the NAS and responds with
scientific and technical evaluation of TCDD dose-response data via:

•	an updated literature search that identified new TCDD dose-response studies (see
Section 2);

•	a kickoff workshop that included the participation of external experts in TCDD health
effects, toxicokinetics, dose-response assessment and quantitative uncertainty analysis;
these experts discussed potential approaches to TCDD dose-response assessment and
considerations for EPA's response to NAS (U.S. EPA, 2009, 543757. Appendix A);

•	detailed study inclusion criteria and processes for the selection of key studies (see
Section 2.3) and epidemiologic and animal bioassay data for TCDD dose-response
assessment (see Section 2.4.1/Appendix B and Section 2.4.2, respectively);

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•	kinetic modeling to quantify appropriate dose metrics for use in TCDD dose-response
assessment (see Section 3 and Appendices C and D);

•	dose-response modeling for all appropriate noncancer and cancer data sets (see
Section 4.2/Appendix E and Section 5.2.3/Appendix F, respectively);

•	thorough and transparent evaluation of the selected TCDD data for use in the derivation
of an RfD and an oral slope factor (OSF) (see Sections 4.2 and 5.2.3, respectively);

•	the development of an RfD (see Section 4.3);

•	the development of a revised OSF (see Section 5.3) with an updated cancer weight of
evidence determination for TCDD based on EPA's 2005 Cancer Guidelines (2005,
086237") (see Section 5.1.2);

•	consideration of nonlinear dose-response approaches for cancer, including illustrative
RfDs for cancer precursor events and tumors (see Section 5.2.3.4); and

•	discussion of the feasibility and utility of quantitative uncertainty analysis for TCDD
dose-response assessment (see Section 6).

Each of these activities is described in detail in subsequent sections of this document.

In addition to this document, it should be noted that three separate EPA activities address
other TCDD issues, specifically related to the application of dioxin TEFs and to TCDD and DLC
background exposure levels. Information on the application of the dioxin TEFs is published
elsewhere by EPA for both ecological (U.S. EPA, 2008, 543774) and human health risk
assessment (U.S. EPA, 2009, [92196). As a consequence, EPA does not directly address TEFs
herein, but makes use of the concept of toxicity equivalence10 as applicable to the analysis of
exposure dose in epidemiologic studies. Furthermore, this document does not address the NAS
recommendations pertaining to the assessment of human exposures to TCDD and other dioxins.
Information on updated background levels of dioxin in the U.S. population has been recently
reported (Lorber et al., 2009, 543766).

1.3.1. TCDD Literature Update

EPA has developed a literature database of peer-reviewed studies on TCDD toxicity,
including in vivo mammalian dose-response studies and epidemiologic studies. An initial
literature search for studies published since the 2003 Reassessment was conducted by the U.S.
Department of Energy's Argonne National Laboratory (ANL) through an Interagency Agreement

10Toxicity equivalence (TEQ) is the product of the concentration of an individual DLC in an environmental mixture
and the corresponding TCDD TEF for that compound. These products are summed to yield the TEQ of the mixture.

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with EPA. ANL used the online National Library of Medicine database (PubMed) and identified
studies published between the year 2000 and October 31, 2008. Supporting references published
since the release of the 2003 Reassessment were also identified. Supporting studies were
classified as studies pertaining to TCDD kinetics, TCDD mode-of-action, in vitro TCDD studies,
and TCDD risk assessment approaches. The literature search strategy explicitly excluded studies
addressing (1) analytical/detection data and cellular screening assays; (2) environmental fate,
transport and concentration data; (3) dioxin-like compounds and toxic equivalents;
(4) nonmammalian dose-response data; (5) human exposure analyses only, including body
burden data; and (6) combustor or incinerator or other facility-related assessments absent
primary dose-response data. EPA published the initial literature search results in the Federal
Register on November 24, 2008 (73 FR 70999; November 24, 2008) and invited the public to
review the list and submit additional peer-reviewed in vivo mammalian dose-response studies for
TCDD, including epidemiologic studies that were absent from the list (U.S. EPA, 2008, 519261).
Submissions were accepted by the EPA through an electronic docket, email and hand delivery,
and were evaluated for use in TCDD dose-response assessment. The literature search results and
subsequent submissions were used during a 2009 scientific workshop, which was open to the
public and featured a panel of experts on TCDD toxicity and dose-response modeling (discussed
below). Additional studies identified during the workshop and those collected by EPA scientists
during the development of this report through October 2009 have been incorporated into the final
set of studies for TCDD dose-response assessment.

1.3.2. EPA's 2009 Workshop on TCDD Dose Response

To assist EPA in responding to the NAS, EPA and ANL convened a scientific workshop
(the "Dioxin Workshop") on February 18-20, 2009, in Cincinnati, Ohio. The goals of the
Dioxin Workshop were to identify and address issues related to the dose-response assessment of
TCDD and to ensure that EPA's response to the NAS focused on the key issues and reflected the
most meaningful science. The Dioxin Workshop included seven scientific sessions: quantitative
dose-response modeling issues, immunotoxicity, neurotoxicity and nonreproductive endocrine
effects, cardiovascular toxicity and hepatotoxicity, cancer, reproductive and developmental
toxicity, and quantitative uncertainty analysis of dose-response. During each session, EPA asked
a panel of expert scientists to perform the following tasks:

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•	Identify and discuss the technical challenges involved in addressing the NAS comments
related to the dose-response issues within each specific session topic and the TCDD
quantitative dose-response assessment.

•	Discuss approaches for addressing the key NAS recommendations.

•	Identify important published, independently peer-reviewed literature—particularly
studies describing epidemiologic studies and in vivo mammalian bioassays expected to
be most useful for informing EPA's response.

The sessions were followed by open comment periods during which members of the
audience were invited to address the expert panels. The session's Panel Co-chairs were asked to
summarize and present the results of the panel discussions—including the open comment
periods. The summaries incorporated points of agreement as well as minority opinions. Final
session summaries were prepared by the session Panel Co-chairs with input from the panelists,
and they formed the basis of a final workshop report (U.S. EPA, 2009, 543757. Appendix A of
this report). Because the sessions were not designed to achieve consensus among the panelists,
the summaries do not necessarily represent consensus opinions; rather reflect the core of the
panel discussions. Some of the key discussion points from the workshop that influenced EPA's
development of this document are listed below (see Appendix A for detail):

•	In the development of study selection criteria, more relevant exposure-level (i.e., dose)
decision points using tissue concentrations could be defined.

•	A linear approach to body-burden estimation, which was utilized in the 2003
Reassessment (U.S. EPA, 2003, 537122). does not fully consider key toxicokinetic issues
related to TCDD—e.g., sequestration in the liver and fat, age-dependent elimination, and
changing elimination rates over time. Thus, kinetic/mechanistic modeling could be used
to quantify tissue-based metrics. In considering human data, lipid-adjusted serum levels
may be preferable over body burden, although the assumptions used in the back
calculation of the body burden in epidemiologic cohorts are of concern. In considering
rat bioassay data, lipid-adjusted body-burden estimates may be preferable.

•	New epidemiologic studies on noncancer endpoints have been published since the
2003 Reassessment that may need to be considered (e.g., thyroid dysfunction literature
from Wang et al. (2005, 198734) and Baccarelli et al. (2008, 197059)).

•	The 1% of maximal response (ED0i) that was utilized in the 2003 Reassessment has not
typically been used in dose-response assessment. Some alternative ideas were as follows:
(1) the POD should depend on the specific endpoint; (2) for continuous measures, the
benchmark response (BMR) could be based on the difference from control and consider

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1	the adversity level; and (3) for incidence data, the BMR should be set to a fixed-risk

2	level.

3	• The quantitative dose-response modeling for cancer could be based on human or animal

4	data. There are new publications in the literature for four epidemiological cohort studies

5	(Dutch cohort, NIOSH cohort, BASF accident cohort, and Hamburg cohort). The

6	increase in total cancers could be considered for modeling human cancer data. However,

7	non-Hodgkin's lymphoma and lung tumors are the main TCDD-related cancer types seen

8	from human exposure. In reviewing the rat data, the NTP (2006, 197605) data sets are

9	new and can be modeled. Although the liver and lungs are the main target organs,

10	modeling all cancers, as well as using tumor incidence in lieu of individual rats as a

11	measure, should be considered.

12	• Both linear and nonlinear model functions should be considered in the cancer

13	dose-response analysis because there are data and rationales to support use of either

14	below the POD.

15	• For quantitative uncertainty analysis, consider the impacts of choices among plausible

16	alternative data sets, dose metrics, models, and other more qualitative choices. Issues to

17	consider include how much difference these choices make and, also, how much relative

18	credence should be put toward each alternative as a means to gauge and describe the

19	landscape of imperfect knowledge with respect to possibilities for the true dose response.

20	This may be difficult to do quantitatively because the factors are not readily expressed as

21	statistical distributions. However, the rationale for accepting or questioning each

22	alternative in terms of the available supporting evidence, contrary evidence, and needed

23	assumptions, can be delineated.

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25	1.3.3. Overall Organization of EPA's Response to NAS Recommendations

26	The remainder of this document is divided into five sections that address the

27	three primary areas of concern resulting from the NAS (2006, 198441) review. Section 2

28	describes EPA's approach to the recommendation for transparency and clarity during selection of

29	key data sets—including criteria for the selection of key dose-response studies, evaluations of the

30	important epidemiologic studies and animal bioassays, and a summary of the key studies used

31	for subsequent dose-response modeling. Sections 3, 4, and 5 present EPA's response to the NAS

32	recommendation to better justify the approaches used in dose-response modeling of TCDD.

33	Section 3 discusses the toxicokinetic modeling EPA conducted to support the dose-response

34	analyses. Section 4 presents EPA's approach to noncancer data set selection, dose-response

35	modeling, and derivation of an RfD for TCDD, and contains a qualitative discussion of the

36	uncertainties associated with the RfD. Section 5 presents an updated cancer weight-of-evidence

37	summary, EPA's approach to cancer data set selection, dose-response modeling, derivation of an

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1	OSF for TCDD, and a qualitative discussion of the uncertainties associated with the OSF,

2	including an evaluation of illustrative nonlinear approaches to cancer assessment of TCDD.

3	Finally, Section 6 discusses the feasibility of conducting a quantitative uncertainty analysis of

4	TCDD dose response.

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2. TRANSPARENCY AND CLARITY IN Till SELECTION OF KEY DATA SETS

FOR DOSE-RESPONSE ANALYSIS

This section addresses transparency and clarity in the study selection process and
identifies key data sets for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) dose-response analysis.
Section 2.1 summarizes the National Academy of Sciences (NAS) committee's comments
specifically regarding this issue. Section 2.2 presents U.S. Environmental Protection Agency's
(EPA's) response to those comments and describes EPA's approach to ensuring transparency and
clarity in the selection of studies for subsequent dose-response analyses. Section 2.3 describes
the TCDD-specific study inclusion criteria and evaluation process EPA used in this document for
determining the eligibility of both epidemiologic and experimental animal studies for TCDD
dose-response analysis. Section 2.4.1 summarizes epidemiologic data and evaluates the
suitability of these data for TCDD dose-response analyses. Section 2.4.2 summarizes animal
bioassay data that have met the study inclusion criteria for TCDD dose-response assessment.
Finally, Section 2.4.3 identifies key TCDD epidemiologic and animal bioassay studies that were
determined using the study inclusion criteria. Study/endpoint combination data sets for
developing TCDD toxicity values for noncancer and cancer effects are further evaluated in
Sections 4 and 5 of this document, respectively.

2.1. SUMMARY OF NAS COMMENTS ON TRANSPARENCY AND CLARITY IN
THE SELECTION OF KEY DATA SETS FOR DOSE-RESPONSE ANALYSIS

The NAS committee proposed that EPA develop a clear and readily understandable

methodology for evaluating and including epidemiologic and animal bioassay data sets in

dose-response evaluations. The NAS committee recommended the development and application

of transparent initial criteria to judge whether or not specific epidemiologic or animal bioassay

studies be included in TCDD dose-response analysis.

Specific NAS comments on the topic of study evaluation and inclusion criteria include

EPA should specify inclusion criteria for the studies (animal and human) used for
derivation of the benchmark dose (BMD) for different noncancer effects and
potentially for the development of RfD values and discuss the strengths and
limitations of those key studies (NAS, 2006, 198441. p. 27).

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.. .in its [EPA's] evaluation of the epidemiological literature of carcinogenicity, it
did not outline eligibility requirements or otherwise provide the criteria used to
assess the methodological quality of other included studies (NAS, 2006, 198441.
p. 56).

With regard to EPA's review of the animal bioassay data, the committee
recommends that EPA establish clear criteria for the inclusion of different data
sets (NAS, 2006, 198441. p. 191).

.. .the committee expects that EPA could substantially improve its assessment
process if it more rigorously evaluated the quality of each study in the database
(NAS, 2006, 198441. p. 56).

EPA could also substantially improve the clarity and presentation of the risk
assessment process for TCDD.. by using a summary table or a simple summary
graphical representation of the key data sets and assumptions... (NAS, 2006,

198441. p. 56).

2.2. EPA'S RESPONSE TO NAS COMMENTS ON TRANSPARENCY AND CLARITY
IN THE SELECTION OF KEY DATA SETS FOR DOSE-RESPONSE ANALYSIS

EPA agrees with the NAS committee regarding the need for a transparent and clear

process for selecting studies and key data sets for TCDD dose-response analyses. The

delineation of the study selection process and decisions regarding key data sets will facilitate

communication regarding critical decisions made in the TCDD dose-response assessment. In

keeping with the NAS committee's recommendation to use a transparent process and improve

clarity and presentation of the risk assessment process for TCDD, Figure 2-1 overviews the

approach that EPA has used in this document to develop a final list of key cancer and noncancer

studies for quantitative dose-response analysis of TCDD. The steps in Figure 2-1 are further

explained below.

Literature search for in vivo mammalian and epidemiologic TCDD studies
(2000-2008): EPA conducted a literature search to identify peer-reviewed, dose-response
studies for TCDD that have been published since the 2003 Reassessment. This search
included in vivo mammalian and epidemiological studies of TCDD from 2000 to 2008.
Additional details describing the conduct of this literature search are presented in
Section 1.3.1 of this document.

Federal Register Notice—Web publication of literature search for public comment:

In November 2008, EPA published a list of-500 citations from results of this literature
search (U.S. EPA, 2008, 51926D and invited the public to review this preliminary list of
dose-response citations for use in TCDD dose-response assessment. EPA requested that
interested parties identify and submit peer-reviewed studies for TCDD that were absent

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from this list. Two parties identified additional references that were not included in the
2008 Federal Register notice and submitted additional references for EPA to consider.
These references were included in the final TCDD literature database considered by EPA
for TCDD dose-response analysis.

Initial study inclusion criteria development for TCDD in vivo mammalian

bioassays: EPA developed an initial set of draft criteria for evaluating the extensive
TCDD database of in vivo mammalian bioassays. These initial inclusion criteria had
three purposes. First, they provided a transparent and rigorous evaluation of the scientific
quality of each study in EPA's database, a deficiency in the 2003 Reassessment identified
by the NAS committee. Second, given the vast TCDD mammalian bioassay database,
they provided a transparent method for initially screening studies to be considered for
TCDD dose-response analyses. Third, they served as a starting point for discussions of
study inclusion criteria by expert panelists who were convened by EPA for its scientific
workshop on TCDD dose-response analysis (the Dioxin Workshop), described next (also
see the workshop report in Appendix A, U.S. EPA [2009b]).

Dioxin Workshop and expert refinement of TCDD in vivo mammalian bioassay
inclusion criteria: In February 2009, EPA convened "A Scientific Workshop to Inform
EPA's Response to NAS Comments on the Health Effects of Dioxin in EPA's 2003
Dioxin Reassessment." The goals of this 3-day public and scientific workshop were to
identify and address issues related to the dose-response assessment of TCDD. Sessions at
the workshop examined toxicities associated with TCDD, issues related to developing
dose-response estimates based on these data and associated uncertainties. At the
workshop, EPA presented the draft set of study inclusion criteria for evaluating the
extensive TCDD in vivo mammalian bioassay literature and asked workshop panelists to
discuss these criteria and make recommendations for their revision. Further details on
this workshop are presented in Section 1.3.2 of this document, and the complete report
from this workshop is available in Appendix A (U.S. EPA, 2009b), including detailed
summaries of the panels' comments on the inclusion criteria in relation to the various
toxic endpoints that were discussed.

Final development of inclusion criteria for TCDD in vivo mammalian studies: Based
on discussions at the Dioxin Workshop, the initial draft inclusion criteria for evaluating
the TCDD mammalian bioassay literature were revised and are presented in Section 2.3.2
(see Figure 2-3). An initial criterion is that studies for consideration must be publically
available and published in a peer-reviewed scientific journal. Because the methodology
EPA uses to develop reference doses (RfDs) and cancer oral slope factors (OSFs) relies
on identification of studies reporting potential adverse effects at low doses (relative to the
overall database), another important criterion shown in Section 2.3.2 identifies a
maximum value for the lowest TCDD dose tested in a bioassay. This maximum value
was used to eliminate those studies that could not be selected for development of an RfD
or an oral slope factor because tested doses were too high relative to other TCDD
bioassays.

Development of inclusion criteria for epidemiologic studies: Following the Dioxin
Workshop, EPA determined that an evaluation process was also needed for inclusion of
epidemiologic studies for TCDD dose-response assessment. These criteria were

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developed and are detailed in Section 2.3.1 (see Figure 2-2). Analogous to animal
bioassay data, epidemiologic studies for consideration must also be publically available
and published in a peer-reviewed scientific journal. In addition to assessing the
methodological considerations relative to epidemiologic cohorts and studies (e.g.,
statistical power and precision of estimates, consideration of latency periods), key criteria
for use of a study in TCDD dose-response modeling were that the exposure be primarily
to TCDD and that the effective dose and oral exposure are reasonably estimable.

Final literature collection (October 2009): Additional literature was collected as it was
identified by EPA following the Dioxin Workshop through October 2009 to ensure the
consideration of all recently published data for this report.

Studies screened using inclusion criteria: The two sets of TCDD-specific study
inclusion criteria presented in Section 2.3 were used to evaluate all studies included in the
2003 Reassessment, studies identified in the 2000-2008 literature search, studies
identified through public comment and submission, and studies collected in 2009 as
identified by EPA during the development of this document. Section 2.4 presents results
of EPA's evaluation of epidemiologic and mammalian bioassay literature for both cancer
and noncancer endpoints.

Final list of key cancer and noncancer studies for quantitative dose-response
analysis of TCDD: Application of the study inclusion criteria concludes in Section 2.4
with development of a list of key noncancer and cancer studies that were considered for
quantitative dose-response analyses of TCDD in Sections 4 and 5, respectively. In those
sections, points of departure (PODs) are developed and evaluated for all biologically
relevant study/endpoint combinations from these final key study lists, and key data sets
and PODs for the development of TCDD toxicity values are identified.

2.3. STUDY INCLUSION CRITERIA FOR TCDD DOSE-RESPONSE ANALYSIS

One of the three major recom m endati on s made by the NAS (2006, 198441) committee
was that EPA should provide greater clarity and transparency on the selection of studies that
were used in the quantitative dose-response modeling of TCDD in the 2003 Reassessment. In
this section, EPA describes TCDD-specific study inclusion criteria that have been developed to
evaluate epidemiologic studies and animal bioassays for TCDD dose-response assessment.

These criteria reflect EPA's goal of developing an RfD and a cancer OSF for TCDD through a
transparent study selection process; they are intended to be used by EPA for TCDD
dose-response assessment only. These criteria were applied to each of the -500 studies listed in
Preliminary Literature Search Results and Request for Additional Studies on
2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) Dose-Response Studies (U.S. EPA, 2008,

519261): studies identified and submitted by the public and by participants in the Dioxin

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Workshop (U.S. EPA, 2009, 522927); studies included in the 2003 Reassessment, and other
relevant published studies collected by EPA scientists through October 2009.

EPA has undertaken different approaches for epidemiologic versus in vivo animal
bioassay study evaluation and key data set selection. The significant differences between animal
and human health effects data and their use in EPA risk assessment support development of
separate criteria for study inclusion and different approaches to study evaluation. For the vast
majority of compounds on EPA's Integrated Risk Information System (IRIS), cancer and
noncancer toxicity values have been derived using animal bioassay data; therefore, approaches to
dose-response modeling and POD selection from in vivo mammalian bioassays have been
standardized and codified (U.S. EPA, 2000, 052150). The study criteria shown below and in
Figure 2-3 for animal bioassay data reflect EPA's preferences for TCDD-specific study
inclusion, some of which are based on common practices and guidance for POD selection and
RfD and OSF derivation. Far fewer IRIS toxicity values have been derived from human data,
although some examples do exist. For example, benzene, beryllium and compounds, chromium
IV, and 1,3-butadiene have RfDs, Reference Concentrations, Inhalation Unit Risks and/or OSFs
based on occupational cohort data and the methyl mercury RfD is based on high fish consuming
cohorts (U.S. EPA, 2009, 543757). The modeling and interpretation of such human data have
been conducted on a case-by-case basis because each cohort is uniquely defined and has its own
set of exposure conditions, significant confounders, and biases that may need to be considered in
dose-response modeling. For TCDD, not all data are from occupational cohorts, but include
cohorts exposed for relatively short time periods to high concentrations as a consequence of
industrial accidents, a scenario that has not commonly been used to establish EPA toxicity
values.

Because of these differences in data characteristics, divergent selection approaches are
used in this document to present and evaluate the epidemiologic studies (see Section 2.3.1) and
the in vivo animal bioassays (see Section 2.3.2). In Section 2.4.1, all of the available
epidemiologic studies on TCDD are summarized and evaluated for suitability for dose-response
modeling using the TCDD-specific study inclusion criteria below and shown in Figure 2-2; only
studies meeting the inclusion criteria are presented as key studies in Section 2.4.3 (see Tables 2-4
and 2-5 for the cancer and noncancer endpoints, respectively). In Section 2.4.2, because

summarizing and showing the evaluation of the thousands of available animal bioassays on

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TCDD was prohibitive, only studies first meeting the in vivo animal bioassays study inclusion
criteria below (and shown in Figure 2-3) are summarized. These studies are also presented as
key studies in Section 2.4.3 (see Tables 2-6 and 2-7 for cancer and noncancer endpoints,
respectively).

2.3.1. Study Inclusion Criteria for TCDD Epidemiologic Studies

This section identifies the process EPA used to select epidemiologic studies for defining
candidate PODs for TCDD dose-response modeling. These criteria are based on EPA's
approaches for deriving OSFs and RfDs. A discussion of the considerations used in selecting
epidemiologic data for quantitative dose-response modeling is valuable, particularly given EPA's
preference to use high-quality human studies over animal studies because such human studies are
regarded as providing the most relevant information needed for quantitative human health risk
analyses (U.S. EPA, 2005, 086237). As described by Hertz-Picciotto (1995, 065678). key
components needed for the use of an epidemiologic study as a basis for quantitative risk
assessment include issues regarding exposure assessment (a well-quantified exposure assessment
with exposures linked to individuals) and study quality ("strong biases," for example with
respect to inclusion criteria for membership in the cohort and follow-up procedures "ruled out or
unlikely" and "confounding controlled or likely to be limited"). The strength of the association,
either within the full study or within a high exposure subgroup, can also be considered in the
evaluation of suitability for dose-response modeling (Hertz-Picciotto, 1995, 065678). Stayner
et al. (1999, 198654). however, note that even weak associations could be useful in terms of
providing an estimate of a potential upper bound for a quantitative risk estimate.

EPA's method for applying the TCDD study inclusion criteria to epidemiologic data is
detailed below and in Figure 2-2. Based on the framework discussed above, EPA evaluated the
available epidemiologic cohorts and studies based on the five following considerations:

1.	The methods used to ascertain health outcomes are clearly identified and unbiased, with
high sensitivity and specificity.

2.	The risk estimates generated from the study are not susceptible to important biases
arising from an inability to control for potential confounding exposures or other sources
of bias arising from either study design or statistical analysis.

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3.	The study demonstrates an association between TCDD and an adverse health effect
(assuming minimal misclassification of exposure and absence of important biases) with
some suggestion of an exposure-response relationship.

4.	The exposure assessment methodology is clearly described and can be expected to
provide adequate characterization of exposure, with assignment of individual-level
exposures within a study (e.g., based on biomarker data, or based on a
job-exposure-matrix approach). Limitations and uncertainties in the exposure assessment
are considered.

5.	The size and follow-up period of a cohort study are large enough and long enough,
respectively, to yield sufficiently precise estimates for use in development of quantitative
risk estimates and to ensure adequate statistical power to limit the possibility of not
detecting an association that might be present (i.e., to avoid Type II Errors due to failing
to reject the null hypothesis when the null hypothesis is true). Similar considerations
regarding sample size and statistical precision and power apply to case-control studies.

Three specific study inclusion criteria were used to select studies for further evaluation
and potential TCDD quantitative dose-response assessment

1.	The study is published in the peer-reviewed scientific literature and includes an
appropriate discussion of strengths and limitations.

2.	The exposure is primarily to TCDD, rather than dioxin-like compounds (DLCs), and is
properly quantified so that dose-response relationships can be assessed. All
epidemiologic cohorts will have background exposures to DLCs through the food chain
and these exposures are not included in this criterion.

3.	The effective dose and oral exposure must be reasonably estimable. The measures of
exposure must be consistent with the current biological understanding of dose. For
TCDD dose-response assessment, it is critical that reported dose is consistent with a dose
that is likely to be toxicologically relevant. The timing of the measurement of effects
(i.e., the response) also must be consistent with current biological understanding of the
effect and its progression.

For cancer endpoints, EPA assumes that cumulative TCDD dose estimates are
toxicologically relevant measures. Thus, cancer studies must provide information
about long-term TCDD exposure levels. Further, EPA reasons that measures of
cancer occurrence or death need to allow for examination of issues of latency
between the end of effective exposure and cancer detection or death.

For noncancer endpoints, exposure estimates and analysis must allow for examination
of issues of latency and other issues regarding the appropriate time window of
exposure relevant for specific endpoints. Also, to be consistent with the RfD
methodology, the response must be to a nonfatal endpoint.

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Those studies that met these three inclusion criteria (see Sections 2.4.1, 2.4.3, and Appendix B)
were then subjected to further consideration for quantitative dose-response analyses.

2.3.2. Study Inclusion Criteria for TCDD In Vivo Mammalian Bioassays

This section identifies the criteria EPA applied to select nonhuman in vivo mammalian
studies for defining candidate PODs for use in TCDD dose-response modeling. These inclusion
criteria are based on EPA's approaches for deriving OSFs and RfDs from bioassay data
(U.S. EPA, 2005, 086237). EPA agrees with the NAS committee regarding the utility of an oral
RfD and the need for reevaluation of the OSF for TCDD, specifically in light of data that have
been published since the 2003 Reassessment was released. RfDs and OSFs are generally derived
using data sets that demonstrate the occurrence of adverse effects, or their precursors, in
low-dose range for that chemical. RfDs and OSFs are derived from a health protective
perspective for chronic exposures. Thus, when a group of studies is available on a chemical for
which a number of effects are observed at various doses across those studies, the studies using
the lowest exposures that show effects will typically drive the RfD and OSF derivations, all other
considerations being equal. Studies conducted at higher exposures relative to other available
studies are used as supporting evidence for the final RfD or OSF since they were conducted at
doses too high to impact the numeric derivations of toxicity values. EPA expresses RfDs and
OSFs in terms of average daily doses, usually as mg/kg-day and per mg/kg-day, respectively.
Thus, the study inclusion criteria for the animal bioassay data presented in this section include
requirements that average daily exposures in the studies are within a low dose range where,
relative to other studies, they could be considered for development of a toxicity value. These
low-dose requirements do not imply that TCDD studies conducted at higher doses are of poor
quality, simply that they are not quantitatively useful in the development of toxicity values
because other studies with lower exposures will drive the RfD and OSF derivations under current
EPA practice. Because EPA has identified -2,000 studies on TCDD that may be considered for
this purpose, the development and application of these study inclusion criteria has been critical to
moving the risk assessment process forward.

EPA's method for applying study inclusion criteria for mammalian bioassays is detailed
below and in Figure 2-3. The first study inclusion criterion is that the study is published in the
peer-reviewed scientific literature. Then, two specific study inclusion criteria were used to select

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studies for further evaluation and potential TCDD quantitative dose-response analyses and
identification of candidate PODs:

1.	The lowest dose level tested is <1 [j,g/kg-day for cancer studies and <30 ng/kg-day for
noncancer studies.

2.	The study design consists of orally administered TCDD-only doses, and specifies the
purity and matrix used to administer the doses.

Then, EPA evaluated the remaining in vivo animal studies based on the following
four considerations.

1.	The study tests mammalian species, identifying the strain, gender, and age of the tested
animals.

2.	The study clearly documents testing protocol, including dosing frequency, duration, and
timing of dose administration relative to age of the animals.

3.	The overall study design is consistent with standard toxicological principles and
practices. The control group or groups are appropriate, given the testing protocol, and are
well characterized. Clinical and pathological examinations conducted during the study
are endpoint-appropriate, particularly for negative findings.

4.	The magnitude of animal responses is outside the range of normal variability exhibited by
control animals (e.g., greater than or less than one standard deviation).

Those studies that met the aforementioned considerations and inclusion criteria (see
Sections 2.4.2 and 2.4.3) were then subjected to dose-response analysis.

The criteria for dose requirements, although somewhat arbitrary, are intended to be
reasonable cutoffs that restrict the number of studies that would need to be modeled while
ensuring that all study/data set combinations that could be candidates for the cancer slope factor
or RfD were modeled. Thus, the dose range under consideration allows for liberal ranges of
no-observed-adverse-effect levels (NOAELs), lowest-observed-adverse-effect levels (LOAELs),
and benchmark dose lower confidence bound (BMDLs) for assessment of both cancer and
noncancer effects.

For cancer studies, the dose requirements were selected based on an initial evaluation of
available average daily doses administered in TCDD animal bioassays in which adverse effects
were observed. For example, in cancer studies, a sample of the relatively low ranges of tested

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average daily doses include 1-1,000 ng/kg-day (Toth et al., 1979), 1-100 ng/kg-day (Kociba
et al., 1978), 1.43-286 ng/kg-day (NTP, 1982, 543764) and 2.14-71.4 ng/kg-day (NTP, 2006,
197605s) with statistically significant increases in tumor incidence via pair-wise or trend tests
found in all of these studies. The entire range of each these studies is <1 |ig/kg-day. The
linearized multistage model used by EPA to estimate OSFs is most appropriately applied to
studies from which PODs can be estimated as closely as possible to the experimental data. Thus,
given the dose ranges in these studies that are available for modeling, the restriction to
<1 [j,g/kg-day for cancer was considered to be a reasonable cutoff.

For noncancer studies, dose ranges are more complex and vary according to study
endpoint. Examples of the lowest administered doses that might be considered as NOAELs or
LOAELs in POD determinations for noncancer endpoints include 1 ng/kg-day (Toth et al., 1979,
197109). 1.43 ng/kg-day (Cantoni et al., 1981, 197092). 1.07 ng/kg-day (Smialowicz et al., 2008,
198341) 1.43 ng/kg-day (NTP, 1982, 543764) and 2.14 ng/kg-day (NTP, 2006, 197605). Most
of the lowest tested doses in the TCDD studies have been designated as LOAELs (see
Section 4.1). Given the available database, it is likely that the same composite uncertainty factor
(e.g., of 300; 3 for UFA [interspecies], 10 for UFH [intraspecies], and 10 for UFL [LOAEL to
NOAEL]) would be applied to any animal noncancer LOAEL used to derive an RfD for TCDD.
This implies that any study that has a LOAEL of 30 ng/kg-day or more would result in a
candidate RfD that is more than an order of magnitude higher than the example doses of
1-2 ng/kg-day shown here. BMDLs that might be derived from such data also would not be
expected to be lower than these example doses of 1-2 ng/kg-day. Thus, a tested dose
<30 ng/kg-day is considered to be a reasonable cutoff where the lowest tested dose would never
be used as a POD to derive an RfD given that much lower tested doses (associated with adverse
effects) are available from other studies of acceptable quality.

2.4. EVALUATION OF KEY STUDIES FOR TCDD DOSE RESPONSE
2.4.1. Evaluation of Epidemiological Cohorts for Dose-Response Assessment

This section summarizes and evaluates studies for potential use in TCDD dose-response
assessment using the study evaluation considerations and inclusion criteria for epidemiologic
data (see Section 2.3.1). Those studies that meet the study inclusion criteria are are listed later in
this Section in Tables 2-4 and 2-5, for cancer and noncancer, respectively, and are considered in

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the dose-response modeling conducted later in this document (see Sections 4 and 5). The
following sections are organized by epidemiologic cohort. Following a brief summary of each
cohort, its associated studies are then summarized chronologically, assessed for methodological
considerations relative to epidemiologic cohorts and studies (e.g., statistical power and precision
of estimates, consideration of latency periods) and evaluated for suitability for TCDD dose-
response assessment.

2.4.1.1. Cancer

In the 2003 Reassessment, EPA selected three cohort studies from which to conduct a
quantitative dose-response analysis: the National Institute for Occupational Safety and Health
(NIOSH) cohort (Steenland et al., 2001, 197433). the BASF cohort (Ott and Zober, 1996,
198408). and the Hamburg cohort (Becher et al., 1998, 197173). Although these studies were
deemed suitable for quantitative dose-response analysis, the criteria EPA used to reach this
conclusion were unclear. In this section, the study selection criteria and methodological
considerations presented in Section 2.3 are systematically applied to evaluate a number of studies
to determine their suitability for inclusion in dose-response modeling. In addition to the
three cohorts used in previous TCDD quantitative risk assessment, considerations are applied to
other relevant TCDD epidemiological data sets that were identified through a literature review
for epidemiological studies of TCDD and cancer. Study summaries and suitability for
quantitative dose-response analysis evaluations are discussed below.

2.4.1.1.1. Cancer cohorts.

2.4.1.1.1.1. The NIOSH cohort.

In 1978, the NIOSH undertook research that identified workers employed by U.S.
chemical companies that made products contaminated with TCDD between 1942 and 1982.
TCDD was generated in the production of 2,4,5-trichlorophenol and subsequent processes. This
chemical was used to make 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), which was a major
component of the widely-used defoliant, Agent Orange. The NIOSH cohort is the largest cohort
of occupational workers studied to date and has been the subject of a series of investigations
spanning more than two decades. It is important to note that this cohort consists mostly of male
workers that were exposed to TCDD via daily occupational exposure, as compared to an acute

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accidental exposure scenario seen with other cohorts. The investigations have progressed from a
comparison of the mortality patterns of the cohort to the U.S. general population to
dose-response modeling using serum-derived estimates of TCDD that have been
back-extrapolated several decades. Analyses of cancer data from the NIOSH cohort that are
addressed in this section include Fingerhut et al. (1991, 197375). Steenland et al. (1999, 197437;
2001, 1974331 Cheng et al. (2006, 5231221 and Collins et al. (2009, 1976271

2.4.1.1.1.1.1. Fingerhut et al. (1991, 1973751
2.4.1.1.1.1.1.1. Study summary.

The investigation of Fingerhut and her colleagues published nearly two decades ago
attracted widespread attention (Fingerhut et al., 1991, 197375). This retrospective study
examined patterns of cancer mortality for 5,172 workers who comprised the NIOSH cohort,
which combined workers from the company-specific cohorts of Dow Chemical (Ott et al., 1987,
064994)(Cook. 1981) and the Monsanto Company (Zack and Gaffey, 1983, 548783; Zack and
Suskind, 1980, 065005). These workers were employed at 12 plants producing chemicals
contaminated with TCDD. Almost all workers in the cohort (97%) had production or
maintenance jobs with processes involving TCDD contamination. On average, workers were
employed for 2.7 years specifically in processes that involved TCDD contamination, and overall,
were employed for 12.6 years. The mortality follow-up began in 1940 and extended until the
end of 1987. Vital status was determined using records from the Social Security Administration,
the Internal Revenue Service, or the National Death Index. The ascertainment of vital status in
the cohort was nearly complete, with less than 1% of the cohort not followed up until death or
the end of the study period.

Comparisons of mortality were made relative to the U.S. male general population and
expressed using the standardized mortality ratio (SMR) metric and 95% confidence intervals
(CIs). Life-table methods were used to generate person-years of risk accrued by cohort members
at each plant. Person-years and corresponding deaths were tabulated across age, race, and year
of death strata, which permitted the SMRs to be examined for potential confounding from these
three characteristics. No unadjusted SMRs were presented in the paper. Cross-classification of
person-years and deaths was also done across several exposure-related groupings, including
duration of employment, years since first exposure, years since last exposure, and duration of

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exposure. Employment duration was categorized as <5, 5- <10, 10- <15, 15- <20, 20- <25,
25- <30, and >30 years. The variable "years since first exposure" (<10, 10- <20, and >20 years)
was used to evaluate associations in relation to different latency periods. The analysis was
jointly stratified by duration of employment and for varying latency intervals to evaluate whether
cohort members with higher cumulative TCDD levels had higher cancer mortality rates than
those cohort members with lower cumulative levels.

Overall, the cohort of workers had slightly elevated cancer mortality than the general
population (SMR = 1.15, 95% CI = 1.02-1.30). Comparisons to the general population,
however, yielded no statistically significant excess for any site-specific cancer. Cancer mortality
was examined for the subset of workers that worked for at least one year and had a latency
interval of at least 20 years (n = 1,520). The 1-year cut-point was selected based on analyses of
serum levels in a subset of 253 workers which revealed that every worker employed for at least
one year had a lipid-adjusted serum level that exceeded the mean (7 ppt). Relative to the
U.S. general population, statistically significant excesses in cancer mortality were observed for
all cancers (SMR = 1.46, 95% CI = 1.21-1.76), cancers of the respiratory system (SMR = 1.42,
95% CI = 1.03-1.92), and for soft tissue sarcoma (SMR = 9.22, 95% CI = 1.90-26.95) among
this subset of 1,520 male workers. The elevated SMR for soft tissue sarcoma, however, was
based on only three cases in this subset.

SMRs also were generated across joint categories of duration of exposure and period of
latency for deaths from all cancer sites (combined), and cancer of the trachea, bronchus, and
lung. Increased SMRs were observed in strata defined by longer exposure and latency, but no
statistically significant linear trends were found.

2.4.1.1.1.1.1.2. Study evaluation.

This cohort was the largest of four the International Agency for Research on Cancer
(IARC) considered in its 1997 classification of TCDD as a Group 1 human carcinogen (IARC,
1997, 537123). Duration of employment in processes that involved TCDD contamination was
used as a surrogate measure of cumulative exposure. In using this exposure metric, Fingerhut
et al. (1991, 197375) assumed that TCDD exposures were equivalent at all production plants.
Doses for individual cohort members were not reconstructed for these analyses, although they
were in subsequent analyses of this cohort.

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Workers in this cohort also were exposed to other chemicals, which could lead to bias
due to confounding if these exposures were associated with both TCDD exposure and the health
outcomes being examined. At one plant, workers were exposed to 4-aminobiphenyl. Previous
investigators also reported that workers at another plant were exposed to 2,4,5-T and
2,4-dichlorophenoxyacetic acid (2,4-D) (Bond et al., 1988, 197183; Bond et al., 1989, 064967;
Ott et al., 1987, 064994). Although this study did not examine the impact of confounding by
other occupational coexposures, subsequent analyses of this cohort showed that associations
between cumulative TCDD and all cancer mortality persisted after excluding workers exposed to
pentachlorophenols from the analyses (Steenland et al., 1999, 197437). Removal of workers
who died from bladder cancer also did not substantially change the dose-response association
between TCDD and cancer mortality from all other sites combined. This finding suggests that
exposures to 4-aminobiphenyl did not confound the association between cancer mortality and
TCDD exposure. Overall, there is little evidence of confounding by these co-exposures among
this cohort, however, exposure to other possible confounders, such as dioxin-like compounds,
was not examined.

The study collected no information on smoking behavior of the workers, and therefore,
the SMRs do not account for any differences in the prevalence of smoking that might have
existed between the workers and the general population. For several reasons, however, the
inability to take into account smoking is unlikely to have been an important source of bias. First,
mortality from other smoking-related causes of death such as nonmalignant respiratory disease
were not more common in the cohort than in the general population (SMR = 0.96,
95% CI = 0.54-1.58). Second, stratified analyses of workers with at least a 20-year latency
(assuming this subset shared similar smoking habits) revealed that excesses were apparent only
among those who were exposed for at least 1 year. Specifically, when compared to the general
population, the SMR among workers exposed for at least 1 year with a latency of 20 years was
1.46, (95% CI = 1.21-1.76) while those exposed for less than 1 year had an SMR of 1.02
(95%) CI = 0.76-1.36). Third, for comparisons of cancer mortality between blue-collar workers
and the general population, smoking is unlikely to explain cancer excesses of greater than
10-20% (Siemiatycki et al., 1988, 198556). Finally, the investigators found no substantial
changes in the results for lung cancer when risks were adjusted for smoking histories obtained in
1987 from 223 workers employed at two plants. These data were used to adjust for the expected

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number of lung cancer deaths expected in the entire cohort (Fingerhut et al., 1991, 197375).
Following this adjustment, a small change was observed in the SMR for lung cancer in the
overall cohort from 1.11 (95% CI = 0.89-1.37) to 1.05 (95% CI = 0.85-1.30). Similarly, only a
slight change in the SMR for lung cancer in the higher exposure subcohort was noted from an
SMR of 1.39 (95% CI = 0.99-1.89 to 1.37 (95% CI = 0.98-1.87).

The use of death certificate information from the National Death Index is appropriate for
identifying cancer mortality outcomes. For site-specific cancers such as soft tissue sarcoma,
however, the coding of this underlying cause of death is more prone to misclassification (Percy
et al., 1981, 004891). Indeed, a review of tissues from four men concluded to have died from
soft-tissue sarcoma determined that two deaths had been misclassified (Fingerhut et al., 1991,
197375). A review of hospital data revealed that two other individuals had soft tissue sarcomas
that were not identified by death certificate information. The use of death certificate information
to derive SMRs for cancer as a whole is likely not subject to significant bias; the same might not
hold true, however, for some site-specific cancers such as soft tissue sarcoma.

Using the SMR metric to compare an occupational cohort with the general population is
subject to what is commonly referred to as the "healthy worker effect" (Choi, 1992, 594250; Li
and Sung, 1999, 198427). The healthy worker effect is a bias that arises because those healthy
enough to be employed have lower morbidity and mortality rates than the general population.
The healthy worker effect is likely to be larger for occupations that are more physically
demanding (Aittomaki et al., 2005, [97139; Checkoway et al., 1989, 027173). and the healthy
worker effect is considered to be of little or no consequence in the interpretation of cancer
mortality (McMichael, 1976, 073484; Monson, 1986, 001410). Few cancers are associated with
a prolonged period of poor health that would affect employability long before death. Also
recognized is that, as the employed population ages, the magnitude of the healthy worker effect
decreases as the absolute reduction in mortality becomes relatively smaller in older age groups
(McMichael, 1976, 073484). The mortality follow-up of occupational cohorts generally spans
several decades, which should minimize the associated healthy worker effect in such studies.

Bias could also be introduced in that workers who are healthier might be more likely to stay
employed and therefore accrue higher levels of exposure. In the NIOSH cohort, however,
mortality was ascertained for those who could have left the workforce or retired by linking
subjects to the National Death Index. Although internal cohort comparisons can minimize the

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potential for the healthy worker effect for the reasons presented above, for cancer outcomes, the
SMR statistic is a valuable tool for characterizing whether occupational cohort are more likely to
die of cancer than the general population. Moreover, stratified analyses across categories of
duration of exposure, or latency periods within a cohort can yield important insights about which
workers are at greatest risk. Perhaps most important, subsequent analyses of the NIOSH cohort
that presented risk estimates derived from external comparisons using the SMR were remarkably
consistent with rate ratios derived using an internal referent (Steenland et al., 1999, [97437Y

2.4.1.1.1.1.1.3. Suitability of data for TCDD dose-response modeling.

This cohort meets most of the identified considerations for conducting a quantitative
dose-response analysis for mortality from all cancer sites combined. The NIOSH cohort is the
largest cohort of TCDD-exposed workers, exposure characterization at an individual level is
possible but not available in this particular study, and the follow-up period is long enough to
evaluate latent effects. Although there is no direct evidence of any important sources of bias,
confounding may be present due to a lack of consideration of dioxin-like compounds. For the
purpose of quantitative dose-response modeling, it is important to note that subsequent studies of
this cohort adopted methods that greatly improved the characterization of TCDD exposure in this
cohort and increased the follow-up interval (Cheng et al., 2006, 523122; Steenland et al., 2001,
197433). As such, for all practical purposes, due consideration for dose-response modeling
should focus on the more recently developed data sets.

For quantitative dose-response modeling for individual cancer sites, the data are much
more limited. A statistically significant positive association with TCDD was noted only for soft-
tissue sarcoma among those with more than 1 year of exposure and 20 years of latency
(SMR = 9.22, 95% CI = 1.90-26.95). However there were only three deaths from soft tissue
sarcoma among this exposed component of the cohort, and four deaths in total in the overall
cohort. Also, misclassification of outcome for soft-tissue sarcoma through death registries is
well recognized and supported with additional review of tissue from two of the men.

Specifically, tissues from the four men who died of soft-tissue sarcoma revealed that only two of
these cases were coded correctly.

Although subsequent analyses of the NIOSH cohort did not show evidence of
confounding by other occupational exposures, the design of this initial publication of the NIOSH

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cohort did not allow for examination of exposures to other possible confounders, such as dioxin-
like compounds. Duration of exposure was used as a surrogate for cumulative TCDD exposure;
therefore, effective doses could not be estimated. Therefore, dose-response modeling was not
conducted for this study.

2.4.1.1.1.1.2. Steenland et al. (1999, 197437).

2.4.1.1.1.1.2.1. Study summary.

A subsequent analysis of the NIOSH cohort extended the follow-up interval of Fingerhut
et al. (1991, 197375) by 6 years (i.e., from 1940-1993) and improved characterization of TCDD
exposure (Steenland et al., 1999, 197437). A key distinction from the work of Fingerhut et al.
(1991, 197375) was the exclusion of several workers that had been included in the previous
mortality analyses. The authors excluded 40 workers who were either female, had never worked
in TCDD-exposed departments, or had missing date of birth information. An additional
238 workers were excluded as occupational data for characterizing duration of exposure were
lacking, preventing their use in a subcohort dose-response analysis. This subcohort was further
reduced by excluding workers from four plants (n = 591) because the information on the degree
of TCDD contamination in work histories was limited, preventing the characterization of TCDD
levels by job type. Thirty-eight additional workers were excluded from the eight remaining
plants because TCDD contamination could not be estimated. Finally, 727 workers were
excluded because they had been exposed to pentachlorophenol. In total, exposures were
assigned to 3,538 (69%) members of the overall cohort, a cohort substantially reduced from the
5,172 on which Fingerhut et al. (1991, 197375) reported. Steenland et al. (1999, 197437) also
evaluated the mortality experience of a subcohort of 608 workers with chloracne who had no
exposure to pentachlorophenol.

For each worker, a quantitative exposure score for each day of work was calculated based
on the concentration of TCDD (j_ig/g) present in process materials, the fraction of the day
worked, and a qualitative contact level based on estimates of the amount of TCDD exposure via
dermal absorption or inhalation. The authors derived a cumulative measure of TCDD exposure
by summing the exposure scores across the working lifetime history for each worker. The
authors validated this cumulative exposure metric indirectly by comparing values obtained for
workers with and without chloracne. Such a validation is appropriate, given that chloracne is

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considered a clinical sign of exposure to high doses of dioxin (e.g., Ott et al., 1993, 594322).
The median exposure score among those with chloracne was 11,546 compared with 77 among
those without (Steenland and Deddens, 2003, 198587).

Cancer mortality was compared using two approaches. As in Fingerhut et al. (1991,
197375), external comparisons were made to the U.S. general population using the SMR
statistic. The authors adjusted the SMR statistics for race, age, and calendar time. They also
applied life-table methods to characterize risks across the subcohort of 3,538 workers with
exposure data by categorizing the workers into seven cumulative exposure groups. The
cut-points for these categories were selected so that the number of deaths in each category was
nearly equal to optimize study power. Life-table analyses were extended further to consider a
15-year lag interval, which in a practical sense means that person-years at risk would not begin
to accrue until 15 years after the first exposure occurred. The person-years and deaths that
occurred in the first 15 years were included in the lowest exposure grouping. The Cox
proportional hazards model was used to characterize risk within the cohort. Cox regression was
used to provide an estimate of the hazard ratios and the 95% CIs for ischemic heart disease, all
cancers combined, lung cancer, smoking related cancers, and all other cancers. The authors also
performed Cox regression analyses using the seven categories of exposure, adjusting the
regression coefficients for year of birth and age. The regression models were run for both
untagged and lagged (15 years) cumulative exposure scores.

Overall, when compared with the U.S. general population, a slight excess of cancer
mortality (from all sites) was noted in the 5,132 cohort study population (SMR = 1.13,
95% CI = 1.02-1.25). This result did not substantially differ from the earlier finding that
Fingerhut et al. (1991) published (SMR = 1.15, 95% CI = 1.03-1.30). Site-specific analyses
revealed statistically significant excesses relative to the U.S. general population for bladder
cancer (SMR = 1.99, 95% CI = 1.13-3.23) and for cancer of the larynx (SMR = 2.22,
95% CI = 1.06-4.08). In the chloracne subcohort (n = 608), SMRs of 1.25
(95% CI = 0.98-1.57) and 1.45 (95% CI = 0.98-2.07) were found for all cancer sites and for
lung cancer, repectively, relative to the general population. The authors also found statistically
significant excesses for connective and soft tissue sarcomas (SMR =11.32,
95% CI = 2.33-33.10) and for lymphatic and hematopoietic malignancies (SMR = 3.01,
95% CI = 1.43-8.52).

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External comparisons made by grouping workers into septiles of cumulative TCDD
exposure and generating an SMR for each septile using the U.S. population as the referent group
suggested a dose-response relationship. For all cancer sites combined, workers in the highest
exposure score category had an SMR of 1.60 (95% CI = 1.15-1.82); increases also were
observed in the sixth (SMR = 1.34) and fifth (SMR = 1.15) septiles. The two-sided^-value
associated with the test for trend for cumulative TCDD exposure was statistically significant
(p = 0.02). A similar approach for lung cancer revealed virtually the same pattern. The
incorporation of a 15-year latency for the analyses of all cancer deaths, in general, produced
slightly higher SMRs across the septiles, although a slight attenuation of effect was noted in the
highest septile (SMRim|agged = 1.60 vs. SMRiagged = 1.54). For a 15-year lag, the lung cancer
SMRs were mixed compared to the untagged results with some septile exposure categories
increasing and others decreasing relative to the lowest exposure group.

For the internal cohort comparisons using Cox regression analyses higher hazard ratios
were found among workers in the higher exposure categories than in the lowest septile. The
linear test for trend, however, was not statistically significant (p = 0.10). The associations across
the septiles for the untagged exposure for the internal cohort comparisons were not as strong as
for the external cohort comparisons. The opposite was true, however, for cumulative exposures
lagged 15 years.

Relative to the lowest septile, stratified analyses revealed increased hazard ratios in the
upper septiles of the internal cohort comparisons for both smoking- and nonsmoking-related
forms of cancer. The test for linear trend was statistically significant for all other cancers (after
smoking-related cancers were excluded). These analyses suggest that the overall cancer findings
were not limited to an interaction between TCDD and smoking. Additional sensitivity analyses
by the authors indicated the findings for smoking-related cancers were largely unaffected by the
exclusion of bladder cancer cases. This observation suggests that the exposure to
4-aminobiphenyl, which occurred at one plant and might have contributed to an increased
number of bladder cancers, did not substantially bias the dose-response relationship between
TCDD and all cancers combined.

The investigators also evaluated the dose-response relationship with a Cox regression
model separately for each plant using internal cohort comparisons and found some heterogeneity.

This finding is not unexpected particularly given the relatively small number of cancer deaths at

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each plant, and given that exposures were quite low for one plant at which no positive
association was found. The variability among plants was taken into account by modeling plant
as a random effect measure in the Cox model, which produced little change in the slope
coefficient (P = 0.0422 vs. P = 0.0453).

2.4.1.1.1.1.2.2. Study evaluation.

This study represents a valuable extension of that by Fingerhut et al. (1991, 197375).
Internal comparisons were performed to help minimize potential biases associated with using an
external comparison group (e.g., healthy worker effect, and differences in other risk factors
between the cohort and the general population). That similar dose-response relationships were
found for internal and external comparison populations suggests that the bias due to the health
worker effect in the cohort might be minimal for cancer mortality. More importantly, the
construction of the cumulative exposure scores provides an improved opportunity to evaluate
dose-response relationships compared with the length of exposure and duration of employment
metrics that Fingerhut et al. (1991, 197375) used.

A potential limitation of the NIOSH study was the inability to account for cigarette
smoking. If cigarette smoking did contribute to the increased cancer mortality rates in this and
other cohorts, increased cancer mortality from exposure to TCDD would be expected only for
smoking-attributable cancers. This study demonstrates associations with TCDD for both
smoking- and nonsmoking-related cancers, including a stronger association for
nonsmoking-related cancers. Therefore, the data provide evidence that associations between
TCDD and cancer mortality are not likely due to cigarette smoking.

The findings regarding latency should be interpreted cautiously as the statistical power in
the study to compare differences across latency intervals was limited. Caution also should be
heeded, given that latency intervals can vary on an individual basis as they are often
dose-dependent (Guess and Hoel, 1977, 197464s). The evaluation of whether TCDD acts as
either an initiating or promoting agent (or both) is severely constrained by the reliance on cancer
mortality data rather than incidence data. This constraint is due to the fact that survival time can
be quite lengthy and can vary substantially across individuals and by cancer subtype. For
example, the 5-year survival among U.S. males for all cancer sites combined ranged between 45
and 60% (CIegg et al., 2002, 594267). When only mortality data are available, evaluating the

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time between when individuals are first exposed and when they are diagnosed with cancer is
nearly impossible.

Starr (2003, 59427:0 suggested that Steenland et al. (1999, 197437s) focused too heavily
on the exposures that incorporated a 15-year period of latency and that those who experienced
high exposures would inappropriately contribute person-years to the lowest exposure group
"irrespective of how great the workers' actual cumulative exposure scores may have been."

Most cancer deaths would, however, typically occur many years postemployment. Given that
the follow-up interval of the cohort was long and the average exposure duration was 2.7 years, at
the time of death, person-years for those with high cumulative exposures would be captured
appropriately. The median 5-year survival for all cancers is approximately 50% (Clegg et al.,
2002, 594267). so applying a minimum latency of 5 years when using cancer mortality rather
than cancer incidence data is needed to assure that the exposure metric is capturing exposures
that occur before diagnoses. Increasing this latency period, for example to 10 or 15 years, would
eliminate consideration of exposures that occur in the period between tumor occurrence and
tumor detection (diagnosis), and allows for an appropriate focus on exposures that act either
early or late in the pathogenic process. If the association of TCDD with cancer is causal, effects
might become apparent only at high exposures and with adequate latency. As such, IARC has
concluded that a latency interval of 15 years could be too short (IARC, 1997, 537123). EPA
considers the Steenland et al. (1999, 197437) presentation to be balanced in that they provided
the range in lifetime excess risk estimated across the various models used. The authors' finding
that the models with a 15-year lag provided a statistically significant improvement in fit based on
the chi-square test statistic should not be readily dismissed.

2.4.1.1.1.1.2.3. Suitability of data for TCDD dose-response modeling.

This study meets most of the epidemiological considerations for conducting a
quantitative dose-response analysis for mortality from all cancer sites combined. This study
excludes a large number of workers who were exposed to pentachlorophenol, thus eliminating
the potential for bias from this exposure and used an improved methodology for assigning TCDD
exposures to the workers. However, given that exposures to other dioxin-like compounds were
not described, it is unclear if the exposures among this cohort were primarily to TCDD.
Therefore, dose-response modeling was not pursued for this study, but was for the subsequent

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NIOSH study by Steenland et al. (2001, 197433). which did examine exposure to dioxin-like
compounds.

2.4.1.1.1.1.3. Steenland et al. (2001, 197433).

2.4.1.1.1.1.3.1. Study summary.

In 2001, Steenland et al. published a risk analysis using the NIOSH cohort that for the
first time incorporated serum measures in the derivation of TCDD exposures for individual
workers. The authors applied the same exclusion criteria to the entire cohort of workers across
the 12 plants in the Steenland et al. (1999, 197437) study, which left 3,538 workers for which
risk estimates could be calculated. Cumulative TCDD serum levels were estimated on an
individual basis for all 3,538 workers by developing predictive models that used a subset of
170 workers for which both serum measures and TCDD exposures scores were available
(Steenland et al., 2001, 197433). Unlike previous analyses of the NIOSH cohort that considered
several different mortality outcomes, the analyses presented in Steenland et al. (2001, 197433)
focused exclusively on mortality from all cancers sites combined. The authors observed
256 cancer deaths in the cohort during the follow-up interval that extended from 1942 until the
end of 1993. All risks estimated in the Steenland et al. (2001, 197433) study were based on
internal cohort comparisons.

Characterization of TCDD exposure levels among the workers was based on serum
measures obtained in 1988 from 199 workers who were employed in one of the eight plants. The
researchers restricted the development of the model to include only those workers whose
measured serum levels were deemed to be greater than the upper range of background levels
(10 ppt), which resulted in 170 workers.

The authors developed a regression model that could estimate the level of TCDD at the
time of last exposure for the 170 workers. The model was developed based on the estimated
half-life of TCDD, the known work history of each worker, a pharmacokinetic model for the
storage and excretion of TCDD, and exposure scores for each job held by each worker over time.
The resulting equation follows

yiast exposure >>1988 exp(kAt)	(Eq. 2-1)

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The first-order elimination rate constant (X) was based on a half-life of 8.7 years
previously reported for the Ranch Hands cohort (Michalek et al., 1996, 198893). The
background rate of TCDD exposure was assumed to be 6.1 parts per trillion (ppt), which was
based on the median level in a sample of 79 unexposed workers in the NIOSH cohort (Piacitelli
et al., 1992, 197275). This value was subtracted when TCDD values were back-extrapolated,
and then added again after the back-extrapolation was completed. A background level of 5 ppt
also was used in some of the analyses with minimal demonstrable effects on the results.
Sensitivity analyses also were incorporated to consider a 7.1-year half-life estimate that had been
developed for the earlier Ranch Hands study (Pirkle et al., 1989, 197861).

After back-extrapolating to obtain TCDD serums levels at the time of last exposure, the
investigators estimated cumulative (or "area under the curve") TCDD serum levels for every
cohort member. This estimation procedure was the same method Flesch-Janys et al. (1998,
197339) applied to the Hamburg cohort to derive a coefficient for relating serum levels to
exposure scores. The "area under the curve" approach integrates time-specific serum levels over
the employment histories of the individual workers. The slope coefficient was estimated using a
no-intercept linear regression model. This model is based on the assumption that a cumulative
score of zero is associated with no serum levels above background.

Cox regression was also used to model the continuous measures of TCDD. A variety of
exposure metrics were considered that took into account different lags, nonlinear relationships
(e.g., log-transform and cubic spline), as well as threshold and nonthreshold exposure metrics.
Categorical analyses were used to evaluate risks across TCDD exposure groups, while different
shapes of dose-response curves were evaluated through the use of lagged and untagged
continuous TCDD measures. Categorical analyses of TCDD exposure were conducted using the
Cox regression model to derive estimates of relative risk (RR) as described by hazard ratios and
95% CIs. The reference group in this analysis was those workers in the lowest septile
cumulative exposure grouping (<335 ppt-years). The septiles were chosen based on cumulative
serum levels that considered no lag and also a 15-year lag.

The investigators also conducted dose-response analyses using the toxicity equivalence
(TEQ) approach. The TEQ is calculated as the sum of all exposures to dioxins and furans
weighted by the potency of each specific compound. In this study, TCDD was assumed to be
account for all dioxin exposures in the workplace. For background TEQ levels, the investigators

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used a value of 50 ppt in the dose-response modeling. This is based on the assumption that
TCDD accounted for 10% of the toxicity of all dioxins and furans (WHO, 1988, 594278). and is
equivalent to using a background level of 5 ppt/yr that was used in the derivation of cumulative
serum TCDD levels. A statistically significant dose-response pattern was observed for all cancer
mortality and TCDD exposure based on log of cumulative TEQs with a 15-year lag. A
comparison of the overall model chi-square values indicated that the fit of this model was not as
good as that for TCDD.

The hazard ratios among workers grouped by categories of cumulative TCDD exposure
(lagged 15 years) suggested a dose-response relationship. Steenland et al. (2001, 197433) found
statistically significant excesses in the higher exposure categories compared to the lowest septile.
The RR was 1.82, 95% CI = 1.18-2.82 for the sixth septile (7,568-20,455 ppt-years) and 1.62,
95% CI = 1.03-2.56) for the seventh septile (>20,455 ppt-years). Cox regression indicated that
log TCDD serum concentrations (lagged 15 years) was positively associated with cancer
mortality (P = 0.097, standard error (P) = 0,032, p < 0.003). A statistically significant
improvement in fit was observed when a 15-year lag interval was incorporated into the model
compared to a model with no such lag [Model % with 4 degrees of freedom (df) = 7.5], Results
were similar when using a half-life of 7.1 years rather than 8.7 years. The excess lifetime risk of
death from cancer at age 75 for TCDD intake (per 1.0-picogram per kilogram [pg/kg] of body
weight (BW) per day) was about 0.05-0.9%) above a background lifetime risk of cancer death of
12.4%). The results from the best-fitting models provide lifetime risk estimates within the ranges
derived using data from the Hamburg cohort (Becher et al., 1998, 197173).

In both categorical and continuous analyses of TCDD based on a linear exposure metric,
the dose-response pattern tailed off at high exposures suggesting nonlinear effects. This
phenomenon could be due to saturation effects (Stayner et al., 2003, 054922) or, alternatively,
could have resulted from increased exposure misclassification of higher exposures (Steenland
et al., 2001, 197433). As the authors highlighted, some of the highest exposures might have
been poorly estimated as they occurred in workers exposed to short-term high exposures during
the clean-up of a spill. The choice of a linear model to develop data from a single time point can
also result in exposure misclassification in those individuals that have differences in the length of
exposure (Emond et al., 2005, 197317). Misclassification would be less likely at low
concentrations where dose-dependent elimination is minimal.

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2.4.1.1.1.1.3.2. Study evaluation.

An important consideration in the Steenland et al. (2001, 197433) study was the use of a
small subset of workers (n = 170) to infer exposures for the remainder of the cohort. This subset
comprised surviving members of the cohort (in 1988), and therefore, their age distribution would
have differed from the rest of the cohort. Furthermore, these workers were employed at a single
plant, at which the work histories were less detailed than at other plants; thus, the development of
the exposure scores differed between this plant and that of the others. Also, many of the workers
at this plant had the same job title and were employed during the same calendar period. The use
of serum data from this subset adds a level of uncertainty that is not readily characterized.

Despite this limitation, the use of these sera data to derive cumulative measures for all cohort
workers has merit given the strong correlation observed between the exposure scores, and TCDD
serum levels estimates at the time of last exposure (Spearman r = 0.90).

The authors performed an extensive series of sensitivity analyses and considered several
alternative exposure metrics to the simple linear model. The lifetime excess risk above
background was nearly twice as high for the log cumulative serum measures with a 15-year lag
when compared to the piecewise linear models with no lag. An important observation was that
the exposure metric based on cumulative serum (lagged 15 years) did not fit the data as well as
the cumulative exposure score used in earlier analyses (Steenland et al., 1999, 197437). A priori,
one would expect that a better fit would be obtained with serum-based measures because serum
levels are a better measure of relevant biological dose. As the authors noted, inaccuracies
introduced in estimating the external-based exposure scores could have contributed to a poorer
fit of the data. Alternatively, exposure misclassification error could be introduced if serum
samples based on the 170 workers were not representative of the entire cohort. Although the
serum-based measures did not fit the data as well as the exposures scores, the authors regarded
them as providing a reasonable fit based on an improvement in log likelihood of 3.99 (between
the log cumulative serum model and the log cumulative exposure score model). Moreover, the
serum-based measures enabled better characterization of risk in units (pg/kg-day) that can be
used in regulation exposures.

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2.4.1.1.1.1.3.3. Suitability of data for TCDD dose-response modeling.

This study meets all of the epidemiological considerations for conducting a quantitative
dose-response analysis for mortality from all cancer sites combined. As mentioned previously,
the NIOSH cohort is the largest assembled to date for which TCDD-related risks of cancer
mortality can be estimated. The use of serum-based measures provides an objective measure of
TCDD exposure. Repeated measures in other study populations have provided reasonable
estimates of the half-life of TCDD, which permitted back-extrapolation of exposures.

The authors have made extensive efforts to evaluate a wide variety of nonlinear and
linear models with varying lengths of latency and log transformations. The model chi-square test
statistics were fairly similar for the log cumulative serum (15-year lag) (Model %2(4df) = 11.3)
model and the piecewise linear model (no lag) (Model %2(5df) = 12.5). These models, however,
produced results with twofold differences in lifetime excess risks. These differences underscore
the importance of characterizing uncertainty in modeling approaches when conducting
dose-response analysis.

The Steenland et al. (2001, 197433) study characterizes risk in terms of pg/kg of body
weight per day. Given that tolerable daily intake dioxin levels are typically expressed in pg/kg
of body weight (WHO, 1988, 594278). the presentation of risks in terms of these units is an
important advance from the earlier analyses that used exposure scores (Steenland et al., 1999,
197437). Many of the Steenland et al. (2001, 197433) findings are consistent with earlier work
from this cohort, which is not surprising given that exposures scores were used to derive serum-
based levels for the cohort. The findings of excess lifetime risks obtained for the best- fitting
model are also consistent with those derived from the Hamburg cohort (Becher et al., 1998,
197173). This study meets the epidemiological considerations noted previously as there is no
evidence that the study is subject to bias from confounding due to cigarette smoking or other
occupational exposures. Given the considerable efforts to measure effective dose to TCDD
among the study participants, this study also meets the requisite dose-response modeling criteria
and will be used in quantitative dose-response analyses of cancer mortality.

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2.4.1.1.1.1.4. Cheng et al. (2006, 523122).

2.4.1.1.1.1.4.1. Study summary.

Cheng et al. (2006, 523122) undertook a subsequent quantitative risk assessment of
3,538 workers in the NIOSH cohort using serum-derived estimates of TCDD. This
dose-response analysis was published after the 2003 Reassessment document was released. The
goal of this study was to examine the relationship between TCDD and cancer mortality (all sites
combined) using a new estimate of dose that estimated TCDD as a function of both exposure
intensity and age using a kinetic model. This physiologically based pharmacokinetic model has
been termed the "concentration- and age-dependent elimination model" (CADM) and was
developed by Ay 1 ward et al. (2005, 197014). This model describes the kinetics of TCDD
following oral exposure to humans by accounting for key processes affecting kinetics by
simulating the total concentration of TCDD based on empirical consideration of hepatic
processes (see Section 3.3). An important feature of this kinetic model is that it incorporates
concentration- and age-dependent elimination of TCDD from the body; consequently, the
effective half-life of TCDD elimination varies based on exposure history, body burden, and age
of the exposed individuals. The study was motivated by the reasoning that back-calculations of
TCDD using a first-order elimination model and a constant half-life of 7-9 years underestimated
exposures to TCDD among workers. This underestimate, in turn, would result in overestimates
of the carcinogenic potency of TCDD.

As with the earlier Steenland et al. (2001, 197433) analyses, the cohort follow-up period
was extended from 1942 until the end of 1993 and work histories were linked to a job exposure
matrix to obtain cumulative TCDD scores. Two cumulative serum lipid exposure metrics (in
ppt-years) were constructed using the data obtained from the sample of 170 workers. The first
replicated the metric used in a previous analysis of the cohort (Steenland et al., 2001, 197433)
and was based on a first-order elimination model with an 8.7-year half-life (Michalek et al.,
1996, 198893). The second metric was based on CADM and had two first-order elimination
processes (Ay 1 ward et al., 2005, 197114). This metric assumes that the elimination of TCDD in
humans occurs at a faster rate when body concentrations are high and at slower rates in older
individuals (Ay 1 ward et al., 2005, 197114; Ay 1 ward et al., 2005, 197014). The model was
optimized using individuals for which serial measures of serum TCDD were available. These
measures were obtained from 39 adults with initial serum levels between 130 and 144,000 ppt

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(Ay 1 ward et al., 2005, 197014). This group included 36 individuals who had been exposed in the
Seveso accident and 3 exposed in Vienna, Austria. In practice, for serum levels greater than
1,000 ppt, the effective half-life would be less than 3 years, and for serum TCDD levels less than
50 ppt, the effective half-life would be more than 10 years (Ay 1 ward et al., 2005, 197014).
Results from the model indicate that men eliminate TCDD faster than women do as
demonstrated previously by Needham et al. (1994, 200030). These age- and
concentration-dependent processes were assumed to operate independently on TCDD in hepatic
and adipose tissues, and TCDD levels in liver and adipose tissue were assumed to be a nonlinear
function of body concentration. Cheng et al. (2006, 523122) calibrated CADM using a dose of
156 ng per unit of exposure score and assumed a background exposure rate of 0.01 ng/kg-month.
The average TCDD ppt-years derived from CADM with a 15-year lag was 4.5-5.2 times higher
than with the first-order elimination model. The two metrics, however, were highly correlated
based on a Pearson correlation coefficient of 0.98 (p < 0.001). Comparisons of fit between the
CADM and first-order elimination model were made using R2 values and presented in Aylward
et al. (2005, 197014).

Cheng et al. (2006, 523122) compared the mortality experience of NIOSH workers to the
U.S. general population using the SMR statistic. SMR statistics also were generated separately
for each of the 8 plants and for all plants combined. Cox regression models were used to analyze
internal cohort dose-response. These models used age as the time variable, and penalized
smoothing spline functions of the CADM metric also were considered. The possible
confounding effects of other occupational exposures and other regional population differences
were assessed by repeating analyses after excluding one plant at a time. Lagged and untagged
TCDD exposures were analyzed separately, and stratified analyses compared risk estimates for
smoking- and nonsmoking-related cancers. Cheng et al. (2006, 523122) adjusted the slope
estimates derived from the Cox model for potential confounding effects of race and year of birth.

Overall, a statistically significant excess in all cancer mortality in the cohort occurred
relative to the general population (SMR = 1.17, 95% CI = 1.03-1.32). The plant-specific SMRs
ranged from 0.62-1.87, with a statistically significant excess evident only for plant 10
(SMR = 1.87, 95% CI = 1.35-2.52). For lung cancer mortality, the overall SMR was not
statistically significant (SMR = 1.11, 95% CI = 0.89-1.37). A statistically significant excess for
lung cancer also was found for plant 10 (SMR = 2.35, 95% CI = 1.44-3.64). The SMRs between

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smoking- (SMR = 1.22, 95% CI = 1.01-1.45) and nonsmoking-related cancers (SMR = 1.12,
95% CI = 0.94-1.33) were comparable.

For the internal cohort analyses of serum-derived measures, the authors were able to
replicate the one-compartmental model used previously (Steenland et al., 2001, 197433). As had
been noted by Steenland et al. (2001, 197433). an inverse-dose-response pattern was seen for
individuals with high exposures (above 95th percentile); this type of pattern is often seen in
occupational studies (Stayner et al., 2003, 054922). Excluding these data produced a stronger
association between TCDD and all-cause mortality. In fact, only when the upper 2.5% or 5% of
observations was removed did a statistically significant positive association become evident with
the untransformed data. Similarly, when the model incorporated a lag of 15 years, a statistically
significant association was noted only for the untransformed TCDD ppt-years with the upper 5%
of observations removed. Stratified analyses revealed little difference between smoking- and
nonsmoking-related cancers, and the removal of one plant at a time from the analyses of TCDD
ppt-years changes did not substantially change the slope.

2.4.1.1.1.1.4.2. Study evaluation.

The authors reported that CADM provided an improved fit over the one-compartmental
model, but presented no evidence regarding any formal test of statistical significance. A
comparison of R2 values presented in Ay 1 ward et al. (2005, 197014). however, does reveal that
the R2 value increased from 0.27 (first-order compartmental model with an 8.7-year half-life) to
0.40 for CADM. TCDD exposures estimated using CADM were approximately fivefold higher
than the one-compartmental model estimates among cohort members with higher levels of
exposure. Differences in exposure estimates between the two metrics were less striking among
individuals with lower TCDD exposures. The net effect was that CADM produced a 6- to
10-fold decrease in estimated risks compared to estimates previously reported (Steenland et al.,
2001, 197433). Nonetheless, the estimates produced by CADM span more than two orders of
magnitude under various assumptions. Further uncertainties arise from between-worker
variability of TCDD elimination rates, possible residual confounding, and the variability
associated with the use of data obtained from other cohorts. Nevertheless, the use of the CADM
model to estimate TCDD exposure is considered a significant advantage over the previous first-

order body burden calculations.

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2.4.1.1.1.1.4.3. Suitability of data for TCDD dose-response modeling.

The value of including the NIOSH cohort data has already been established based on
investigations published by Steenland et al. (1999, 197437; 2001, 197433). The decision to
include data from the quantitative dose-response analysis that Cheng et al. (2006, 523122)
conducted relates to the added value that the CADM exposure estimates would provide. The
earlier modeling work of Ay 1 ward et al. (2005, 197014) provided some support for a modest
improvement of the fit of CADM over the first-order compartmental model, and they also
confirmed previous studies that found that TCDD elimination rates varied by age and sex.

Recent work by Kerger et al. (2006, 198651) also demonstrates that the half-life for TCDD is
shorter among Seveso children than the corresponding half-life for adults, and that body burdens
influence the elimination of TCDD in humans. That estimates of half-lives among men have
been remarkably consistent, with mean estimates ranging between 6.9 and 8.7 years
(Flesch-Janys et al., 1996, 197351; Michalek et al., 2002, 199579; Needham et al., 2005,

594295; Pirkle et al., 1989, 197861), however, is noteworthy. Based on the underlying strengths
of the NIOSH cohort data and efforts by Cheng et al. (2006, 523122) to improve estimates of
effective dose, these data support further dose-response modeling.

2.4.1.1.1.1.5. Collins et al. (2009, 197627).

2.4.1.1.1.1.5.1. Study summary.

In a recent study, Collins et al. (2009, 197627) investigated the relationship between
serum TCDD levels and mortality rates in a cohort of trichlorophenol workers exposed to
TCDD. These workers were part of the NIOSH cohort having accounted for approximately 45%
of the person-years in an earlier analysis (Bodner et al., 2003, 197135). The investigators
completed an extensive dioxin serum evaluation of workers employed by the Dow Chemical
plant in Midland, Michigan, that made 2,4,5-trichlorophenol (TCP) from 1942 to 1979 and
2,4,5-T from 1948 to 1982. Collins et al. (2004, 197267) developed historical TCDD exposure
estimates for all TCP and 2,4,5-T workers. This study represents the largest group of workers
from a single plant ever studied for the health effects of TCDD. Little information on how vital
status was ascertained, either in this paper or in the Bodner et al. (2003, 197135) report of
mortality in this cohort. Although the authors indicate that death certificates were obtained from

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the states in which the employees died, whether vital status was ascertained from company
records or through record linkage to the National Death Index is unclear.

The follow-up interval for these workers covered the period between 1942 and 2003.
Thus, the study included 10 more years of follow-up than earlier investigations of the entire
NIOSH cohort. Serum samples were obtained from 280 former workers collected during
2004-2005. A simple one-compartment first-order pharmacokinetic model and elimination rates
as estimated from the BASF cohort were used (Flesch-Janys et al., 1996, 1973511 The "area
under the curve" approach was used to characterize workers' exposures over the course of their
working careers and provided a cumulative measure of exposure. Analyses were performed with
and without 165 of the 1,615 workers exposed to pentachlorophenol to evaluate the impact of
these exposures.

External comparisons of cancer mortality rates to the general U.S. population were made
using SMRs. Internal cohort comparisons of exposure-response relationships were made using
the Cox regression model. This model used age as the time variable, and was adjusted for year
of hire and birth year. Only those causes of death for which an excess was found based on the
external comparisons or for which previous studies had identified a positive association were
selected for dose-response analyses.

A total of 177 cancer deaths were observed in the cohort. For the external comparison
with the U.S. general population, overall, no statistically significant differences were observed in
all cancer mortality among all workers (SMR = 1.0, 95% CI = 0.8-1.1). Results obtained after
excluding workers exposed to pentachlorophenol were similar (SMR = 0.9, 95% CI = 0.8-1.1).
Excess mortality in the cohort were found for leukemia (SMR = 1.9, 95% CI = 1.0-3.2) and soft
tissue sarcoma (SMR = 4.1, 95% CI = 1.1-10.5). Although not statistically significant SMRs for
other lymphohemopoietic cancers included non-Hodgkin's lymphoma SMR =1.3; 95%CI = 0.6,
2.5) and Hodgkin's disease (SMR = 2.2; 95% CI = 0.2, 6.4).

Internal cohort comparisons using the Cox regression model were performed for all
cancers combined, lung cancer, prostate cancer, leukemia, non-Hodgkin's lymphoma, and
soft-tissue sarcoma. Whether the internal comparisons excluded those workers exposed to
pentachlorophenol is not entirely clear from the text or accompanying table, but presumably they
do not. The RR was 1.002 (95% CI = 0.991-1.013) for all cancer mortality per 1 ppb-year
increase in cumulative TCDD exposure was not statistically significant. Except for soft tissue

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sarcomas, no statistically significant exposure-response trends were observed for any cancer site.
For soft tissue sarcoma, analyses were based on only four deaths.

2.4.1.1.1.1.5.2.	Study evaluation.

A key limitation of this study is that SMRs were not derived for different periods of
latency for the external comparison group analysis. The original publication on the NIOSH
cohort found that SMRs increased when a 20-year latency period was incorporated (Fingerhut
et al., 1991, 197375). and similar patterns have been observed in other occupational cohorts
(Manz et al., 1991, 199061; Ott and Zober, 1996, 198101) and among Seveso residents
(Consonni et al., 2008, 524825). Additionally, dose-response analyses showed marked increases
in slopes with a 15-year latency period (Cheng et al., 2006, 523122; Steenland and Deddens,
2003, 198587). In this context, the absence of an elevated SMR for cancer mortality is
consistent with previous findings of the NIOSH cohort. While the cohort did have sufficient
follow-up, no evaluation of possible latent effects was presented and this is a major limitation of
this study. Further, the evaluation of the exposure metrics should be expanded from what was
presented in Collins et al. (2009, 197627) due to the previous analyses of the same workers
finding positive associations between cancer mortality and TCDD (Steenland et al., 2001,
197433).

Unfortunately, the Collins et al. (2009, 197627) study did not include a categorical
analysis of TCDD exposure and cancer mortality. This categorical analysis would have enabled
an evaluation of whether a nonlinear association exists between TCDD exposure and cancer risk.
The analyses of both Cheng et al. (2006, 523122) and Steenland et al. (2001, 197433) suggest an
attenuation of effects at higher doses, and several investigations have considered log-transformed
associations as a means to address nonlinearity. Also, the earlier plant-specific dose-response
analyses of Steenland et al. (2001, 197433) are not consistent with the findings for the Midland
plant that Collins et al. (2009, 197627) presented. These differences could be due to differences
in the construction of exposure metrics, additional follow-up, or lagging of exposures.

2.4.1.1.1.1.5.3.	Suitability of data for dose-response modeling.

The Collins et al. (2009, 197627) study uses serum levels to derive TCDD exposure
estimates and does not appear to be subject to important biases. The reliance on data from one

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plant offers some advantages over the multiplant analyses, as heterogeneity in exposure to other
occupational agents would be lower. The number of individuals who provided serum samples
(,n = 280) is greater than the 170 individuals used to derive TCDD estimates for the NIOSH
cohort. The authors found a statistically signficant dose-response trend for soft tissue sarcoma
mortality and TCDD exposures. Therefore, this study is considered for quantitative
dose-response analysis.

2.4.1.1.1.2. The BASF cohort.

In 1953, dioxin contamination occurred as a result of an autoclave accident during the
production of trichlorophenol at the BASF plant in Ludwigshafen, Germany. A second dioxin
incident occurred in 1988 that was attributed to the blending of thermoplastic polyesters with
brominated flame retardants. Of the two events, the one on November 13, 1953, was associated
with more severe acute health effects, including chloracne that resulted in immediate
hospitalizations for seven workers. These adverse events were not linked to TCDD until 1957
when TCDD was identified as a byproduct of the production of trichlorophenol and was shown
to induce chloracne (Zober et al., 1994, 197572). Zober and colleagues (1998, 594300) noted
that with the 1988 accident, affected individuals did not exhibit clinical symptoms or chloracne,
but rather were identified through "analytical measures." In both instances, efforts were made to
limit the potential for exposure to employees.

2.4.1.1.1.2.1. Thiess and Frentzel-Beyme (1977, 594302) and Thiess et al. (1982, 064999).
2.4.1.1.1.2.1.1. Study summary.

A study of the mortality of workers employed at the BASF plant was first presented in
1977 (Thiess and Frentzel-Beyme, 1977, 594302) with subsequent updates in both 1982 (Thiess
et al., 1982, 064999). and in 1990 (Zober et al., 1990, 197604). In the first published paper
(Thiess et al., 1982, 064999). 74 employees involved in the 1953 accident were traced and their
death certificate information extracted. Of these, 66 suffered chloracne or severe dermatitis.
Observed deaths were compared to the expected number using three external reference groups:
the town of Ludwigshafen (n = 180,000), the district of Rhinehessia-Palatinate (n = 1.8 million),
and the Federal Republic of Germany (n = 60.5 million). Another comparison group was
assembled by selecting age-matched employees taken from other cohorts under study. This

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additional comparison was aimed at avoiding potential biases associated with healthy worker
effect when using an external referent.

During a follow-up interval of up to 26 years (1953-1979), 21 individuals died. Of
these, seven deaths were from cancer. The expected number of cancer deaths derived for the
three external comparison groups ranged between 4.1 and 4.2, producing an SMR of 1.7
(p-values ranged between 0.12 and 0.14). Excess mortality was found for stomach cancer based
on the external comparisons (p < 0.05); however, this was based on only three cases. No other
statistically significant excesses were found with the external comparisons made to the other
cohorts of workers.

2.4.1.1.1.2.1.2.	Study evaluation.

In the Thiess et al. (1982, 064999) study, no TCDD exposures were derived for the
workers, thus no dose-reconstruction was performed. The findings from this study are limited by
the small size of the cohort. The 74 workers followed in this cohort represent the smallest
number of workers across the occupational cohorts (Becher et al., 1998, 197173; Fingerhut et al.,
1991, 197375; Hooiveld et al., 1998, 197829; McBride, 2009, 198490; McBride et al., 2009,
197296; Michalek and Pavuk, 2008, 199573; Steenland et al., 2001, 197433) that have
investigated TCDD exposures and cancer mortality. Mechanisms of follow-up were excellent as
all individuals were traced, and death certificates were obtained from all deceased workers.

Although the study does compare the mortality experience to other occupational cohorts,
the paper provides insufficient information to adequately interpret the associated findings. For
example, a description of these occupations is lacking making it impossible to determine whether
these cohorts were exposed to other occupational carcinogens that might have confounded the
associations between TCDD exposure and cancer mortality.

2.4.1.1.1.2.1.3.	Suitability of data for TCDD dose-response modeling.

Subsequent data assembled for the BASF cohort provide more detailed exposure
characterization and also include information for 243 male workers employed at the plant. As
such, this study did not meet the considerations for further dose-response analysis.

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2.4.1.1.1.2.2. Zober et al. (1990, 1976041
2.4.1.1.1.2.2.1. Study summary.

Zober et al. (1990, 197604) also examined the mortality patterns of 247 individuals
involved in the 1953 accident at the BASF plant. As detailed in their paper, the size of the
original cohort was expanded by efforts to locate all individuals who were exposed in the
accident or during the clean-up. Three approaches were followed in assembling the cohort.
Sixty-nine cohort members were identified from the company physician's list of employees
exposed as a result of the accident (Subcohort CI). Sixty-six of these workers were included in
the original study population of workers Thiess et al. (1982, 064999) examined.

Eighty-four other workers who were potentially exposed to TCDD due to their involvement in
demolitions or operations were added to the cohort. This group included 43 firemen, 18 plant
workers, 7 bricklayers, 5 whitewashers, 4 mechanics, 2 roofers, and 5 individuals in other
occupations (Subcohort C2). The cohort was further augmented through the Dioxin
Investigation Program, which sought to locate those who were involved in the 1953 accident and
were still alive in 1986. Current and former workers enrolled in the study were asked to identify
other current or former coworkers (including deceased or retired) who might have been exposed
from the accident. This third component of 94 workers (Subcohort C3) included 27 plant
workers, 16 plumbers, 10 scaffolders, 10 professionals, 7 mechanics, 6 transportation workers,
5 bricklayers, 5 laboratory assistant, 3 insulators, and 5 individuals in other occupations. A
medical examination was performed for those identified through the Dioxin Investigation
Program, and blood measures were obtained for 28 of these workers.

External comparisons of the workers' mortality experience to the general population of
the Federal Republic of West Germany were made using SMRs. Person-years were tabulated
across strata defined by calendar period, sex, and age group. Sixty-nine deaths including
twenty-three from cancer were detected among the workers during the 34-year follow-up period
(November 17, 1953 through December 31, 1987). Cause-specific death rates for these same
strata were available for the Federal Republic of West Germany. Stratified analyses were
conducted to examine variations in the SMRs according to years since first exposure (0-9,
10-19, and >20 years) for each of the three subcohorts, as well as 114 workers with chloracne.

Although it was consistent in magnitude with findings from the NIOSH cohort, a
statistically significant SMR for all cancer mortality was not observed (SMR = 1.17,

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90% CI = 0.80-1.66). The SMRs for each of the three subcohorts varied substantially. For

Subcohorts CI, C2, and C3, the SMRs were 1.30 (90% CI = 0.68-2.26), 1.71

(90% CI = 0.96-2.83), and 0.48 (90% CI = 0.13-1.23), respectively. The SMRs increased

dramatically when analyses were restricted to those with 20 or more years since first exposure in

Subcohort CI (SMR = 1.67, 90% CI = 0.78-3.13) and Subcohort C2 (SMR = 2.38,

90% CI = 1.18-4.29). Meanwhile, in a subgroup analysis of those with chloracne, for the period

of 20 or more years after first exposure, a statistically significant excess in cancer mortality was

noted (SMR = 2.01; 90% CI = 1.22-3.15).

2.4.1.1.1.2.2.2.	Study evaluation.

An important limitation of the study is the manner in which the cohort was constructed.
Subcohort C3 was constructed by identifying individuals who were alive in 1986. This resulted
in 97 active and retired employees who participated in the program, with 94 included in the
analysis. Although these individuals did identify other workers who might have also retired or
died, inevitably, some individuals who had died were not included in the cohort. This would
serve to underestimate the SMRs that were generated with external comparisons to the German
population. Indeed, cancer mortality rates in this subcohort were about half of what would have
been expected based on general population rates (SMR = 0.48, 90% CI = 0.13-1.23).
Additionally, more than half of Subcohort C2 were firemen (43 of 84), who would likely have
been exposed to other carcinogens as a consequence of their employment. Quantitative analyses
of epidemiologic data for firefighters have demonstrated increased cancer risk for several
different forms of cancer (Youakim, 2006, 197295). Therefore, potential confounding from
other occupational exposures of the firefighters could have contributed to the higher SMR in
Subcohort C2 cohort and is a concern. Data on cigarette smoking were not available either. No
excess for nonmalignant respiratory disease was found, however, suggesting this might not be an
important source of bias.

2.4.1.1.1.2.2.3.	Suitability of data for TCDD dose-response modeling.

As with the Thiess et al. (1982, 064999) publication, worker exposure was not estimated.
Lack of exposure estimates precludes a quantitative dose-response analysis using these data.

Also, the study design is not well suited to characterization of risk using the SMR statistic.

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Mortality is also likely under-ascertained in the large component of the cohort that was
constructed through the identification of surviving members of the cohort.

2.4.1.1.1.2.3. Ott and Zober (1996, 198101V
2.4.1.1.1.2.3.1. Study summary.

Ott and Zober (1996, 198101) extended the analyses of the BASF cohort to include
estimates of individual-level measures of TCDD. The researchers also investigated associations
with cancer mortality and identified incident cancer cases. The cohort follow-up period of
39 years extended until December 31, 1992, adding 5 years to a previous study (Zober et al.,
1990, 197604). Ott and Zober (1996, 198101) identified incident cases of cancer using
occupational medical records, death certificates, doctor's letters, necropsy reports, and
information from self-reported surveys sent to all surviving cohort members. Self-reported
cancer diagnoses were confirmed by contacting the attending physician.

This study characterized exposure by two methods: (1) determining chloracne status of
the cohort members and (2) estimating cumulative TCDD ([j,g/kg) levels. In 1989, serum
measures were sought for all surviving members of the 1953 accident, and serum TCDD levels
were quantified for 138 individuals. These serum levels were used to estimate cumulative
TCDD concentrations for all 254 members of the accident cohort. Ott et al. (1993, 594322)
published a description of the exposure estimation procedure, which was a regression model that
accounted for the circumstances and duration of individual exposure. The average internal
half-life of TCDD was estimated to be 5.8 years based on repeated serum sampling of
29 individuals. The regression model allowed for this half-life to vary according to the
percentage of body fat, and yielded half-lives of 5.1 and 8.9 years among those with 20% and
30% body fat, respectively. Previous analyses of this cohort had used a half-life of 7.0 years (Ott
et al., 1993. 594322).

TCDD half-life has been reported to increase with percentage of body fat in both
laboratory mammals (Geyer et al., 1990, 197700) and humans (Zober and Papke, 1993, 197602).
Ott and Zober (1996, 198101) contend that observed correlations with chloracne severity and
cumulative estimates of TCDD exposure indirectly validated this exposure metric. Specifically,
the mean TCDD concentration for those without chloracne was 38.4 ppt; for those with moderate
and severe forms of chloracne, the mean was 420.8 ppt and 1,008 ppt, respectively.

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Unlike for the NIOSH cohort, individual-level data were collected for other cancer risk
factors. These factors included body mass index at time of first exposure, history of
occupational exposure to P-naphthylamine and asbestos, and history of smoking. Smoking data
were available for 86% of the cohort. SMRs were based on the external referent population of
West Germany. For cancer incidence, Ott and Zober (1996, 198101) generated standardized
incidence ratios (SIRs) using incidence rates for the state of Saarland (1970-1991) as the
external referent. They calculated SMRs (and SIRs) for three categories of cumulative TCDD
levels: <0.1 (J,g/kg, 0.1-0.99 |ig/kg and >1 |ig/kg. The Cox regression model was used to
characterize risk within the cohort using a continuous measure of TCDD. These analyses
considered the potential confounding influence of age, smoking, and body mass index using a
stepwise regression modeling approach. The Cox modeling employed a stratified approach
using the date of first exposure to minimize possible confounding between calendar period and
exposure. The three first exposure groups were exposure within the first year of the accident,
exposure between 1 year after the accident and before 1960, and exposure after 1959. The Cox
regression estimates were presented in terms of conditional risk ratios (i.e., hazard ratios adjusted
for body mass index, smoking and age).

Although no statistically significant excesses relative to the general population were
detected for all cancer mortality, there was some suggestion of an exposure-response
relationship. In the 0.1-0.99 (J,g/kg and >1 (J,g/kg exposure groups, the all cancer SMRs were 1.2
(95% CI = 0.5-2.3) and 1.6 (95% CI = 0.9-2.6), respectively. Higher SMRs for cancer (all sites
combined) were also found with an increased interval since exposure first occurred.

Specifically, when observed versus expected counts of cancer were compared in the time interval
20 years after first exposure, the SMR in the highest exposure group (>1 (J-g/kg) was 1.97
(95%) CI = 1.05-5.36). An excess in lung cancer also was noted with the same lag in this
exposure group (SMR = 3.06, 95% CI = 1.12-6.66). For cancer incidence, a statistically
significant increased SIR for lung cancer was observed in the highest exposure category
(SIR = 2.2, 95% CI = 1.0-4.3), but no other statistically significant associations were detected
for any other cancer site. No cases of soft-tissue sarcoma were found among the cohort members
in this analysis.

Based on internal cohort comparisons, Cox regression models also were used to generate
hazard ratios as measures of relative risk for TCDD exposures following adjustment for

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smoking, age and body mass index. A statistically significant association between TCDD dose
(per |ig/kg) and cancer mortality was detected (RR = 1.22, 95% CI = 1.00-1.50), but not for
cancer incidence (RR = 1.11, 95% CI = 0.91-1.35). Statistically significant findings were
observed for stomach cancer mortality (RR = 1.46, 95% CI = 1.13-1.89) and incidence
(RR= 1.39, 95% CI = 1.07-1.69).

The Ott and Zober (1996, 198101) study also compared the relationship between TCDD
exposure categories and cancer mortality from all sites combined according to smoking status.
Associations were noted between increased exposure to TCDD and mortality from cancer among
smokers, but not among nonsmokers or former smokers.

2.4.1.1.1.2.3.2. Study evaluation.

The Ott and Zober (1996, 198101) study characterizes exposure to TCDD at an
individual level. Therefore, unlike in past studies involving this cohort, these data can provide
an opportunity for conducting quantitative dose-response modeling. As with the more recent
studies involving the NIOSH cohort, serum samples were obtained from surviving cohort
members and then used to back-extrapolate TCDD values for all cohort members. In the BASF
cohort, however, serum data were available for a much higher percentage of cohort members
(54%) than in the NIOSH cohort (5%). An additional study strength was the collection of
questionnaire data, which allowed for the potential confounding from cigarette smoking and
body mass index to be examined.

The Ott and Zober (1996, 198101) study also evaluates the relationship between TCDD
and cancer incidence. Most cohort studies of TCDD-exposed workers have relied solely on
mortality outcomes. The availability of incidence data better allows for period of latency to be
described, and moreover, to characterize risks associated with cancers that typically have long
survival periods. The authors provide few details on the expected completeness of ascertainment
for incident cancer cases, which makes determining any associated bias difficult. They do,
however, suggest that nonfatal cancers are more likely to have been missed in the earlier part of
the follow-up. The net result of differential case ascertainment over time makes evaluating
differences in risk estimates across different periods of latency impossible.

The small sample size of the cohort (n = 243 men) likely limited the statistical power to
detect small associations for some of the exposure measures. This also effectively limited the

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ability to analyze dose-response relationships quantitatively, particularly across strata such as
time since exposure. For site-specific analyses, the cancer site with the most cancer deaths was
the respiratory system (n = 11). Thus, quantitative dose-response analysis using these cohort
data would be limited to the evaluation of all cancer sites combined.

The most important limitation of this study is related to the construction of the
third component of the cohort. As mentioned earlier, this cohort was assembled by actively
seeking out surviving members of the cohort in the mid-1980s. The mortality experience of this
cohort is much lower than that of the general population over the entire follow-up, a result that is
expected given that the individuals were known to be alive as of 1986. The net result is likely an
underestimate of the SMR.

2.4.1.1.1.2.3.3. Suitability of data for TCDD dose-response modeling.

This study was included in the quantitative dose-response modeling for the
2003 Reassessment (U.S. EPA, 2003, 537122). The characterization of exposure data and
availability of other risk factor data at an individual level are appropriate for use in quantitative
dose-response analyses.

2.4.1.1.1.3. The Hamburg cohort

The Hamburg cohort has been the subject of several cancer risk assessments. As with the
NIOSH and BASF cohorts, analyses have progressed from basic comparisons of mortality
experience to general population rates to more sophisticated internal cohort analyses involving
the reconstruction of TCDD exposures using serum measures. This cohort consists of
approximately 1,600 workers who were employed in the production of herbicides at a plant in
Hamburg, Germany during 1950-1984 (Becher et al., 1998, 197173; Flesch-Janys et al., 1995,
197261). The herbicides produced included 2,4,5-T, P-hexachlorocyclohexane and lindane. The
production of TCP and 2,4,5-T was halted in 1954 following a chloracne outbreak. The plant
ceased operations in 1984. Approximately 20 different working areas were identified, which, in
turn, were grouped into five main areas based on putative TCDD exposure levels. One working
area was deemed to be extremely contaminated, having TCDD exposures at least 20-fold higher
than in other areas. In this section, the studies undertaken in this cohort that have examined
cancer mortality are summarized.

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2.4.1.1.1.3.1. Manz et al. (1991, 199061V
2.4.1.1.1.3.1.1. Study summary.

Manz et al. (1991, 199061) investigated patterns of mortality in the Hamburg cohort.
The study population consisted of 1,583 workers (1,184 men, 399 women) who were employed
for at least three months between 1952 and 1989. Casual workers were excluded as they lack
sufficient personal identifying information thereby not allowing for associations with mortality
outcomes to be examined. Vital status was determined using community-based registries of
inhabitants throughout West Germany. Cause of death until the end of 1989 was determined
from medical records for all cancer deaths and classified based on the ninth revision of the
International Classification of Diseases (WHO, 1978, 594329). Although Manz et al. (1991,
199061) present some data on cancer incidence for the cohort, the data are incomplete as
information was available on only 12 cases; 93 cancer deaths were observed in the cohort.

In this study, the authors used information on production processes to group workers into
categories of low, medium, or high exposure to TCDD. This information was based on TCDD
concentrations in precursor materials, products, waste, and soil from the plant grounds, measured
after the plant closed in 1984. The distribution of workers into the low, medium, and high
exposure groups was 186, 901, and 496, respectively. The authors examined the validity of the
three exposure categories using a separate group of 48 workers who provided adipose tissue
samples. The median exposure of the 37 volunteers in the high group was 137 and 60 ng/kg in
the remaining 11. Information about chloracne in the cohort was incomplete, and, therefore, was
not used as a marker of TCDD exposure. Other surrogate measures of exposure were considered
in this study, including duration of exposure and year of first employment. For the latter
measure, employment that began after 1954 was assumed to result in much lower exposures
given that production of 2,4,5-T and TCP stopped in 1954.

External comparisons of cancer mortality were made by calculating SMRs using the
general population of West Germany as a referent. Comparisons of mortality in the cohort also
were made to a separate cohort of 3,417 gas supply workers to avoid bias from a healthy worker
effect. Vital status and cause of death in the gas supply workers were determined using the same
methods as used in the Hamburg cohort. SMRs were calculated relative to both referent
populations (West Germany and gas supply workers) across low, medium, and high TCDD
exposure groups. The comparison of mortality to the gas supply workers, however, extended

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only until the end of 1985, whereas, comparisons to the general population extended until 1989.
Stratified analyses were undertaken to calculate SMRs for each of the three exposure groups for
categories of duration of employment (<20 versus >20 years) and date of entry into the cohort
(<1954 vs. >1954).

When compared to the general population, overall cancer mortality was elevated in male
cohort members (SMR = 1.24, 95% CI = 1.00-1.52) but not in females (SMR = 0.80,
95% CI = 0.60-1.05). A two-fold increase in female breast cancer mortality was noted although
it did not achieve statistical significance at the alpha level of 0.05 (SMR = 2.15,
95% CI = 0.98-4.09). The SMR among men was further increased when analyses were
restricted to workers who were employed for at least 20 years (SMR = 1.87,
95% CI = 1.11-2.95). Analyses restricted to those in the highest exposure group produced an
even higher SMR for those with at least 20 years of employment (SMR = 2.54,
95% CI = 1.10-5.00). Statistically significant excesses in risk were detected among those who
first worked before 1954, but not afterward. Furthermore, a dose-response trend was observed
across increasing exposure categories in the subset of workers employed before 1954. The
SMRs using the cohort of gas supply workers as the referent group for the low, medium, and
high groups in this subset were 1.41 (95% CI = 0.46-3.28), 1.61 (95% CI = 1.10-2.44), and 2.77
(95% CI = 1.59-4.53), respectively. This finding is consistent with what was known about
TCDD exposures levels at the plant, namely, that TCDD concentrations were much higher
between 1951 and 1954, with subsequent declining levels after 1954.

Generally speaking, patterns of excess mortality were similar when the cohort of gas
workers was used as a reference group. The overall SMR for men was 1.39
(95%CI= 1.10-1.75); and was 1.82 (95% CI = 0.97-3.11) when analyses were restricted to
workers with 20 or more years of employment. A dose-response trend also was observed across
exposure categories when analyses were restricted to those employed for at least 20 years. In
particular, with these analyses, no cancer deaths were observed among those in the lowest
exposure group, while the SMRs in the middle and high exposure groups were 1.36
(95% CI = 0.50-2.96) and 3.07 (95% CI = 1.24-6.33).

SMRs also were generated for several site-specific cancers relative to the West German
general population and the gas worker cohort. No statistically significant excesses were
observed using the general population reference. In contrast, statistically significant excesses

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were observed for lung cancer (SMR = 1.67, 95% CI = 1.09-2.44) and hematopoietic system
cancer (SMR = 2.65, 95% CI = 1.21-5.03) relative to the gas workers cohort.

2.4.1.1.1.3.1.2.	Study evaluation.

The Manz et al. (1991, 199061) findings indicate an excess of all cancer mortality among
the workers with the highest exposures, particularly those who worked for at least 20 years and
were employed before 1954. The findings across categories of exposure within the subsets of
workers employed for at least 20 years and before 1954, particularly using the cohort of gas
supply workers, are consistent with a dose-response relationship. These elevated cancer
mortality rates found among those employed before 1954 were likely due to higher TCDD
exposures. Other carcinogenic coexposures, such as benzene, asbestos, and dimethyl sulfate,
could have occurred among this population. Given that no substantial changes in the production
processes at the Hamburg plant occurred after 1954, comparable levels of these coexposures
would be expected before and after 1954. Exposures to these other chemicals varied across
different departments/groups; therefore, confounding was unlikely since a strong association
between concentrations of these chemicals and TCDD exposures was not evident. No
information, however, was presented on potential exposure to other dioxin-like compounds
which may confound the associations that were detected.

Detailed information on workers' smoking behaviors was not collected. Limited
evidence indicated, however, that smoking prevalence between the Hamburg cohort and the gas
supply workers cohort was quite similar. A nonrepresentative sample of 361 workers in the
Hamburg cohort and the sample of 2,860 workers in the gas supply cohort indicated that the
self-reported smoking prevalence was 73% and 76%, respectively. This suggests that the
two cohorts are comprised predominantly of smokers. The similarity in overall smoking
prevalence indicates that comparisons of cancer mortality between the two groups are not unduly
influenced by an inability to adjust for smoking.

2.4.1.1.1.3.1.3.	Suitability of data for TCDD dose-response modeling.

The data compiled for the Manz et al. (1991, 199061) study do satisfy many of the
considerations for conducting quantitative dose-response analysis; health outcomes appear to be
ascertained in an unbiased manner, and exposure was characterized on an individual-level basis.

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However, as demonstrated in later studies, there was a large dioxin-like compound component
that was not quantified or assessed in this study. Dose-response associations between TCDD and
cancer mortality were detected, with stronger associations observed with increased periods of
latency and for those who first worked when TCDD was at higher levels.

The size of the cohort, although not as large as the NIOSH cohort, does offer sufficient
statistical power to evaluate TCDD-related risk for cancers from all cancer sites. The data are
limited, however, for characterizing cancer risks among women; only 20 cancer deaths occurred
in the 399 women included in the cohort. It is unlikely that the findings are biased by
confounding due to cigarette smoking since dose-response patterns were strengthened when
comparisons were made to the cohort of gas supply workers rather the general population
referent where smoking rates were likely lower. The inability to account for other occupational
exposure when TCDD exposures were much higher (pre-1955) could result in confounding if
these other exposures were related to TCDD and the health outcomes under consideration. This
data set would be suitable for quantitative dose-response modeling if the exposure
characterization of the cohort could be improved using biological measures of dose.

2.4.1.1.1.3.2. Flesch-Janys et al. (1995, 1972611
2.4.1.1.1.3.2.1. Study summary.

In 1995, Flesch-Janys et al. (1995, 197261) published an analysis of the male employees
from the Hamburg cohort that extended the follow-up to 40 years (1952-1992). Inclusion of
these three additional years of follow-up resulted in a sample size of 1,189 male workers.

The authors estimated a quantitative exposure variable for concentrations of TCDD in
blood at the end of exposure (i.e., when employment in a department ended) and above German
median background TCDD levels. The TCDD exposure assessment defined 14 production
departments according to TCDD levels in various products in the plant, in waste products, and in
various buildings. The time (in years) each worker spent in each department then was
calculated. Concentrations of TCDD were determined in 190 male workers using serum
(n = 142) and adipose tissue samples (n = 48). The authors used a first-order kinetic model to
calculate TCDD levels at the end of exposure for the 190 workers with available poly chlorinated
dibenzo-p-dioxin (PCDD) and -furan (PCDF) at various time points. Half-lives were calculated
from an elimination study of 48 workers from this cohort, and the median TCDD background

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level was estimated at 3.4 ng/kg blood fat from the German population (Flesch-Janys et al.,
1994, 197372; Papke et al., 1994, 198279). Using the one-compartment, first-order kinetic
model, the half-life of TCDD was estimated to be 6.9 years (Flesch-Janys, 1997, 197305).
Increased age and higher body fat percentage were associated with increased TCDD half-life,
while smoking was associated with a higher decay rate for most of the congeners examined
(Flesch-Janys et al., 1996, 197351). Cumulative TCDD exposures were estimated by summing
exposures over the time spent in all production departments and were expressed in terms of
ng/kg of blood fat. The authors also applied a metric of total toxicity equivalence (TOTTEQ) as
the weighted sum of all congeners where weights were TEQs that denoted the toxicity of each
congener relative to TCDD.

Similar to previous analyses on this cohort, comparisons were made using an external
referent group of workers from a gas supply company (Manz et al., 1991, 199061). In contrast to
previous analyses where SMR statistics were generated using this "external" reference, however,
Flesch-Janys et al. (1995, 197261) used Cox regression. The Cox regression models treated the
gas worker cohort as the referent group, and six exposure groups were defined by serum-derived
cumulative TCDD estimates. The groups were determined by using the first four quintiles with
the upper two exposure categories corresponding to the ninth and tenth deciles of the cumulative
TCDD. Internal cohort comparisons used those workers in the lowest quintile as the referent
group, as opposed to the cohort of gas workers. A similar approach was used to model TEQs.
No known TCDD exposures occurred in the gas workers, so they were assigned exposures based
on the median background levels in the general population. RRs were calculated based on
exposure above background levels; in other words, background levels were assumed to be
equivalent across all workers and also for those employed by the gas supply company. The RRs
derived using the Cox model were adjusted for total duration of employment, age, and year when
employment began.

The Cox regression with the cohort of gas workers as the referent exposure group yielded
a linear dose-response relationship between cumulative TCDD exposure and cancer mortality for
all sites combined (p < 0.01). The RRs for all-cancer mortality were 1.59, 1.29, 1.66, 1.60, 1.70,
and 3.30. For four of the six categories (excluding the referent group), the RRs were statistically
significant (p < 0.05); in the highest TCDD exposure category (344.7-3,890.2 ng/kg) the RR
was 3.30 (95% CI = 2.05-5.31). Similar findings were evident with TOTTEQ. A dose-response

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pattern for all cancer mortality (p < 0.01) based on the internal cohort comparisons was also
detected.

The authors performed an additional analysis to evaluate the potential confounding role
of dimethylsulfate. Although no direct measures of dimethyl sulfate were available, the
investigators repeated analyses by excluding 149 workers who were employed in the department
where dimethylsulfate was present. A dose-response pattern persisted for TCDD (p < 0.01), and
those in the highest exposure group (344.7-3,890.2 ng/kg of blood fat) had a RR of 2.28
(95% CI= 1.14-4.59).

2.4.1.1.1.3.2.2. Study evaluation.

The Flesch-Janys et al. (1995, 197261) study used serum-based measures to determine
cumulative exposure to TCDD at the end of employment for all cohort members. They used the
standard one-compartment, first-order kinetic model and samples obtained from 190 male
workers. This quantitative measure of exposure permits an estimation of a dose-response
relationship.

Confounding for other occupational exposures is unlikely to have biased the results. A
dose-response relationship persisted after excluding workers exposed to dimethylsulfate. Other
potential exposures of interest included benzene and isomers of hexachlorocyclohexane.
Exposure to these agents, however, was highest in the hexachlorocyclohexane and lindane
department, where TCDD exposures were lower. Confounding was unlikely due to exposure to
these chemicals, since a strong association between concentrations of these chemicals and TCDD
exposures was not evident (due to considerable variability in concentrations across different
departments/groups). As outlined earlier, the study findings are unlikely to be biased for
cigarette smoking as cigarette smoking in the cohort was similar to that in the comparison
population. Moreover, more recent analyses of serum-based TCDD exposure measures found no
correlation with smoking status in this cohort (Flesch-Janys et al., 1995, 197261)—a necessary
condition for confounding.

The authors used an exposure metric that described cumulative TCDD exposure of
workers at the time they were last exposed. As a result, the authors were unable to characterize
risks associated with this metric for different periods of latency despite a sufficient follow-up

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period. Subsequent analyses constructed time-dependent measures of cumulative TCDD and
accounted for excretion of TCDD during follow-up.

In contrast to most risk assessments of TCDD exposure, this study modeled the
relationship between other dioxin-like compounds and the risk of cancer mortality using the
TOTTEQ metric.

2.4.1.1.1.3.2.3. Suitability of data for TCDD dose-response modeling.

The data used in this study satisfy most of the considerations developed for performing a
quantitative dose-response analysis. However, latency period was not examined in this study.
Dose-response analyses were, therefore, limited to a subsequent study of this cohort (Becher
et al., 1998, 1971731 which did examine latency.

2.4.1.1.1.3.3. Flesch-Janys et al. (1998, 1973391
2.4.1.1.1.3.3.1. Study summary.

Flesch-Janys et al. (1998, 197339) undertook another analysis on this cohort that
incorporated additional sera data for 275 workers (39 females and 236 males). The follow-up
period was the same as that used in the 1995 analyses, with mortality follow-up extending until
December 31, 1992. Analyses were based on 1,189 males who were employed for at least
3 months from January 1, 1952 onward. The authors continued this dose-response analysis to
address limitations in their previous work. One limitation was that the previous method did not
account for the elimination of TCDD while exposures were being accrued during follow-up. A
second limitation was that the amount of time workers spent in different departments was not
considered. In the 1998 study, the "area under the curve" approach was used because it accounts
for variations in concentrations over time and reflects cumulative exposure to TCDD. The
authors used a first-order kinetic model to link blood levels and working histories to derive
department-specific dose rates for TCDD. The TCDD background level of 3.4 ng/kg blood fat
for the German population was used (Papke et al., 1994, 198279). The dose rates were applied
to estimate the concentration of TCDD at every point in time for all cohort members. A
cumulative measure expressed as ng/kg blood fat multiplied by years was calculated and used in
the SMR analysis. SMRs were calculated using general population mortality rates for the
German population between 1952 and 1992. No lag period was incorporated into the derivation

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of the SMRs. The SMRs were estimated for the entire cohort and for exposure groups based on
quartiles obtained from the area under the curve. Linear trend tests were also performed. The
overall SMR for cancer mortality in the cohort was 1.41 (95% CI = 1.17-1.68). This SMR value
was higher than the SMR of 1.21 reported for this same cohort with 3 fewer years of follow-up
(Manz et al., 1991, 199061). In terms of site-specific cancer mortality, excesses were found for
respiratory cancer (SMR = 1.71, 95% CI = 1.24-2.29) and rectal cancer (SMR = 2.30,
95% CI = 1.05-2.47). Increased risk for lymphatic and hematopoietic cancer (SMR = 2.16,
95%) CI = 1.11-3.17) were also noted largely attributable (SMR = 3.73, 95%>CI= 1.20-8.71)to
lymphosarcoma (i.e., non-Hodgkin's lymphoma). A dose-response relationship was observed
across quartiles of cumulative TCDD for all-cancer mortality (p < 0.01). The SMRs for these
quartiles were 1.24, 1.34, 1.34, and 1.73. Dose-response relationships were not observed for
lung cancer or hematopoietic cancers using this same metric. Dose-response relationships were
not observed with cumulative TEQ for any of the cancer sites examined (i.e., all cancers, lung
cancer, hematopoietic cancer).

2.4.1.1.1.3.3.2.	Study evaluation.

The approach used in the Flesch-Janys et al. (1998, 197339) study offers a distinct
advantage over earlier analyses involving the same cohort. Three more years of follow-up were
available, and the characterization of exposure using the "area under the curve" better captures
changes in cumulative exposure using a person-years approach rather than cumulative TCDD at
the time of last exposure. As noted previously, other occupational exposures or cigarette
smoking are unlikely to have biased the study findings. A sufficient length of follow-up had
accrued, and dose-response associations were evident. Dioxin-like compounds were evaluated in
this study. For TCDD, the mean concentration was 101.3 ng/kg at the time of measurement. For
other higher chlorinated congeners, the corresponding mean (without TCDD) was 89.3 ng/kg.

2.4.1.1.1.3.3.3.	Suitability of data for TCDD dose-response modeling.

The data used in this study satisfy most of the considerations developed for performing a
quantitative dose-response analysis. However, latency was not examined in this study.
Dose-response analyses were, therefore, limited to a subsequent study of this cohort (Becher

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et al., 1998, 197173) which did examine latency and supersedes the Flesch-Janys et al. (1998,
197339) study.

2.4.1.1.1.3.4. Becher et al. (1998, 197173).

2.4.1.1.1.3.4.1. Study summary.

The Becher et al. (1998, 197173) quantitative cancer risk assessment for the Hamburg
cohort was highlighted in the 2003 Reassessment as being appropriate for conducting
dose-response analysis. The integrated TCDD concentration over time, as estimated in the
Flesch-Janys et al. (1998, 197339) study, was used as the exposure variable. Estimates of the
half-life of TCDD based on the sample of 48 individuals with repeated measures were
incorporated into the model that back-calculated TCDD exposures to the end of the employment
(Flesch-Janys et al., 1996, 197351). This method took into account the age and body fat
percentage of the workers. In Becher et al. (1998, 197173), the analysis used the estimate of
cumulative dose (integrated dose or area under the curve) as a time-dependent variable.

Poisson and Cox regression models were used to characterize dose-response
relationships. Both models were applied to internal comparisons where a person-years offset
was used and to an external comparison where an offset of expected number of deaths was used.
The person-years offset was used to account for varying person-time accrued by workers across
exposure categories. The use of the expected number of deaths as an offset allows risks to be
described in relation to that expected in the general population. Within each classification cell of
deaths and person-years, a continuous value TCDD and TEQ levels based on the geometric mean
were entered into the Poisson model. For the Cox model, accumulated dose was estimated based
on area under the curve for TCDD, TEQ, TEQ without TCDD, and P-hexachlorocyclohexane.
These other coexposure metrics were adjusted for in the Cox regression analyses. Other
covariates considered included in the models were year of entry, year of birth, and age at entry
into the cohort. A background level of 3.4 ng/kg blood fat for the German population was used
(Papke et al., 1994, 198279). A variety of latencies was evaluated (0, 5, 10, 15, and 20 years),
and attributable risk and absolute risk were estimated. The unexposed cohort of gas workers was
used for most internal analyses.

Internal and external comparisons using the Poisson model found positive associations
with TCDD exposure and mortality from all cancers combined. The slope associated with the

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continuous measure of TCDD ((J,g/kg blood fat x years) for the internal comparison was 0.027
(p < 0.001), which decreased to 0.0156 (p = 0.07) after adjusting for age and calendar period.
The slope for the external comparison was 0.0163 (p = 0.055); this estimate was not adjusted for
other covariates. For TEQ, the slopes based on the internal comparisons were 0.0274 (p < 0.001)
in the univariate model and 0.0107 (p = 0.175) in the multivariate model after adjusting for age
and calendar period. The external estimate of slope for TEQ was 0.0109 (p = 0.164). Cox
regression of TCDD across six exposure categories, with a lag of 0 years, found a statistically
significant linear trend (p = 0.03) and those in the upper exposure group had a RR of 2.19
(95% CI = 0.76-6.29). These estimates were adjusted for year of entry, age at entry, and
duration of employment. A similar pattern was observed with the Cox regression analysis of
TEQ; the linear test for trend, however, was not statistically significant at the alpha level of 0.05
(p = 0.06).

Cox regression models that included both TCDD and TEQ (excluding TCDD) were
applied. In this model, the slope (P) for TCDD was 0.0089 (p = 0.058), while the coefficient for
TEQ (excluding TCDD) was -0.024 (p = 0.70). This suggests that confounding by other
dioxin-like compounds was unlikely and the increased risk of cancer was due to TCDD
exposure. For all TEQs combined, the slope was 0.0078 (p = 0.066).

The authors used multiple Cox models to evaluate the effect of latency. The slope
estimates for both TCDD and TEQ increased dramatically with increasing latency. The slope
estimates for TCDD increased from 0.0096 to 0.0160 (p < 0.05) when latency was increased
from 0 to 20 years. Similar changes in the TEQ slopes were noted (0.0093 to 0.0157).
Evaluations of dose-response curves found that the best-fitting curve was concave in shape,
thereby yielding higher risk at low exposure. Differences between the fit of the class of models
considered [i.e., RR(x,P) = exp (P log(kx = 1))], however, were small.

Attributable risks were generated only for TCDD, as the data suggested no effects with
other TEQs. The additional lifetime risk of cancer assuming a daily intake of 1 pg TCDD/kg
body weight/day was estimated to range between 0.001 and 0.01.

2.4.1.1.1.3.4.2. Study evaluation.

The Becher et al. (1998, 197173) study represent perhaps the most detailed analyses
performed on any cohort to date. The findings were robust, as similar patterns were found with

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and without using the gas supply worker cohort as the referent group. Exposures to other
potential confounding coexposures, such as dioxin-like compounds, were taken into account, and
workers with exposure to other carcinogens (e.g., lindane) were excluded. Furthermore, latency
was examined in this study, unlike earlier studies of this cohort.

2.4.1.1.1.3.4.3. Suitability of data for TCDD dose-response modeling.

This study was included in the quantitative dose-response modeling for the
2003 Reassessment (U.S. EPA, 2003, 537122). The data in the Becher et al. (1998, 197173^
study are suitable for conducting quantitative dose-response modeling. The exposure data
capture cumulative exposure to TCDD as well as exposures to other dioxin-like compounds.
The length of the follow-up is sufficient, and the study appears to not be subject to confounding
or other types of biases. Therefore, this study is utilized in quantitative dose-response analysis.

2.4.1.1.1.4. The Seveso cohort

Several studies have evaluated the morbidity and mortality effects of residents exposed to
TCDD following a July 10, 1976, accidental release through an exhaust pipe at a chemical plant
in the town of Meda near Seveso, Italy. The released fluid mixture contained 2,4,5-T, sodium
trichlorophenate, ethylene glycol, and sodium hydroxide. Vegetation in the area showed
immediate signs of damage, and in the days following the accident, residents developed nausea,
headaches, eye irritation, and dermal lesions, particularly children.

This accident transported TCDD up to 6 km from the plant. Soil samples taken near the
plant revealed average levels of TCDD that ranged from 15.5 [j,g/m2to 580.4 (j,g/m2 in the most
contaminated area near the plant (referred to as Zone A) (Bertazzi et al., 2001, 197005). Zone A
covered 87 hectares and extended 2,200 m south from the plant. Another, more distant
contaminated zone (Zone B) covering 270 hectares also had contaminated soil levels, but the
TCDD concentration range was much lower (1.7-4.3 (J,g/m3). A reference zone (Zone R), which
surrounded the two contaminated areas, had lower TCDD soil levels (range: 0.9-1.4 (J,g/m3) and
included approximately 30,000 residents. Following the accident, most residents in Zone A left
the area. Although residents in Zone B remained, they were under strict regulations to avoid
consuming homegrown products. In total, 736, 4,737, and 31,800 individuals lived in Zones A,
B, and R, respectively. Within days of the accident, 3,300 animals (mostly poultry and rabbits)

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were found dead. Emergency slaughtering was undertaken to prevent TCDD from entering the
food chain, and within 2 years more than 80,000 animals had been slaughtered. Mechanisms
were put into place for long-term follow-up of these residents. Unlike the other studies based on
occupational cohorts, the follow-up of this population allows for risks to be characterized for
females.

The mortality studies from Seveso published to date have not incorporated serum TCDD
levels that were measured in individuals. Needham et al. (1997) describe the collection of serum
samples from a sample of the exposed population and control subjects in 1976. In 1988, human
exposure to TCDD was assessed by measuring small volumes of serum remaining from medical
examinations done in 1976. An examination of these data revealed some of the highest serum
TCDD levels ever reported, that the half-life of TCDD in this population was between 7 and
8 years, and that half-life varied between women and men. The half-life of TCDD in serum was
longer in women (~9 years) than in men (-7 years) (Needham et al., 1994, 200030). In this
report, the findings of studies that characterized cancer risks in relation to exposure to TCDD
from the 1976 accident are highlighted. These studies include comparisons of cancer mortality
rates to the general population based on zone of residence at the time of accident (Bertazzi et al.,
2001, 197005; Consonni et al., 2008, 524825). More recent work done by Warner et al. (2002,

189) investigated the relationship between serum-based measures of TCDD and breast cancer
among participants in the Seveso Women's Health Study (SWHS).

2.4.1.1.1.4.1. Bertazzi et al. (2001, 197005).

2.4.1.1.1.4.1.1. Study summary.

Several studies have reported on the mortality experience of Seveso residents. The more
recent publications having a longer follow-up of the cohort are evaluated here. In 2001, the
findings from a 20-year mortality study of Seveso residents was published (Bertazzi et al., 2001,
197005). The Bertazzi et al. (2001, 197005) study was an extension of the 10- and 15-year
follow-ups for mortality (Bertazzi et al., 1989, 197013; Bertazzi et al., 1997, 197097; Pesatori
et al., 1998, 523076) and the 10-year follow-up for cancer incidence (Bertazzi et al., 1993,
192445).

In this cohort, TCDD exposures were assigned to the population using a three-level
categorical variable representative of the individual's place of residence (Zones A, B, or R) at the

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time of the accident or when the person first became a resident of the zone, if that was after
1976. An external comparison to the province of Lombardy was made by generating rate ratios
(RR) using Poisson regression techniques. Person-years of follow-up were tabulated across
strata defined by age, zone of residence, duration of residence, gender, calendar time, and
number of years that had elapsed since the time of exposure. Mortality rates during the
preaccident period also were compared to evaluate potential changes in rates due to the accident
and to evaluate whether patterns were consistent before and after the accident.

No overall excess in mortality rates from all cancer sites combined was observed in
Zones A or B (combined) when compared to the reference population of Lombardy
(n = 9 million residents) (RR = 1.0, 95% CI = 0.9-1.2). Analyses of site-specific cancer
mortality revealed statistically significant excesses among residents in Zones A or B (combined)
for cancer of the rectum (RR = 1.8, 95% CI = 1.0-3.3) and lymphatic and hematopoietic
malignancies (RR = 1.7, 95% CI = 1.2-2.5). Lymphatic and hematopoietic malignancies were
elevated in women (RR = 1.8, 95% CI = 1.1-3.2) and in men (RR = 1.7, 95% CI = 1.0-2.8).

Analyses stratified by the number of years since first exposure (i.e., 1976) revealed
higher risk among men with an increased number of years elapsed. Similar to other studies, the
RR for all cancers (combined) was 1.3 (95% CI = 1.0-1.7) among men 15-20 years after first
exposure. No such increase after 15 years postexposure, however, was noted in women
(RR = 0.8, 95% CI = 0.6-1.2).

2.4.1.1.1.4.1.2. Study evaluation.

Ascertainment of mortality appears to be excellent. Vital status was established using
similar methods for both the exposed and reference populations. No individual data were
collected and, therefore, the possibility that confounding by individual characteristics such as
cigarette smoking cannot be entirely dismissed. Bertazzi et al. (2001, 197005) do note that the
sociodemographic characteristics of residents in the three zones were similar based on
independently conducted surveys, and no differences in chronic respiratory disease were found
across the different zones. If excess mortality was attributable to cigarette smoking, such
excesses would be expected to be evident during the entire study period. Latency analyses
revealed elevated risks 15-20 years postaccident. Finally, no excesses were observed for other
smoking-related cancers of the larynx, esophagus, pancreas, and bladder. The observed excesses

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in all cancer mortality do not appear to be attributed to differential smoking rates between the
two populations.

To examine potential for bias due to noncomparability in the two study populations, a
comparison of cancer mortality rates between the Seveso regions and the reference population of
Lombardy was conducted. Elevated rates for brain cancer mortality were noted in Seveso
relative to Lombardy, but the higher rates of leukemia mortality were found in Lombardy
relative to Seveso. That no excess was reported for all cancer sites combined lends credence to
the hypothesis that the exposure to TCDD from the accident increased rates of cancer after a
sufficient period of latency.

Stratified analyses were performed across several categorical variables including gender
and time since exposure. The numbers of cancer site-specific deaths are quite small in many of
the 5-year increments since first exposure. The study, therefore, has limited statistical power to
detect differences in mortality rates among the comparison groups for many cancer sites.

Bertazzi et al. (2001, 197005) assigned exposures based on zone of residence. Soil
sampling within each zone revealed considerable variability in TCDD soil levels within each
zone. Moreover, some individuals would have left the area shortly after the accident, and
determining the extent to which individuals in Zone B who were subject to the recommendations
near the time of the accident adhered to them is difficult. As a result, exposure misclassification
is possible, and the use of individual measures of TCDD level in serum is preferred over zone of
residence for determining exposure. As noted by the authors, the study is better suited to "hazard
identification" than to quantitative dose-response analysis.

2.4.1.1.1.4.1.3. Suitability of data for TCDD dose-response modeling.

Given the variability in soil TCDD levels within each zone and the lack of individual
level, no effective dose can be estimated for quantitative dose-response analyses. Uncertainty in
identifying the critical exposure window for the Seveso cohort is a key limitation. The
evaluation of this study indicates that this study is not suitable for quantitative dose-response
analysis.

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2.4.1.1.1.4.2. Warner et al. (2002, 197489V
2.4.1.1.1.4.2.1. Study summary.

To date, Warner et al. (2002, 197489) is the only published investigation of the
relationship between serum-based measures of TCDD and cancer in Seveso. Eligible
participants from the Seveso Women's Heath Study (SWHS; see Section 2.4.1.2.1.4 for details)
were women who, at the time of the accident in 1976, were 40 years of age or younger, had lived
in one of the most highly contaminated zones (A or B), and had adequate sera collected soon
after the explosion. Enrollment in SWHS was begun in March 1996 and lasted until July 1998.
Of the total 1,271 eligible women, 981 agreed to participate in the study. Cancer cases were
identified during interview and confirmed through review of medical records. Information on
other risk factors including reproductive history and cigarette smoking was obtained through
interview.

Serum volumes greater than 0.5 mL collected between 1976 and 1981 volume were
analyzed. Most sera were collected in 1976/77 (n = 899); samples were collected in 1978-1981
for 54 women, and in 1996/97 for 28 women. For most samples collected after 1977, serum
TCDD levels were back-extrapolated using a first-order kinetic model with a 9-year half-life
(Pirkle et al., 1989, 197861). For 96 women with undetectable values, a serum level that was
equal to one-half the detection level was used.

Analyses were based only on women who provided serum samples; no extrapolation of
values to a larger population was done. Risks were therefore generated using data collected at an
individual level. Serum TCDD was analyzed as both a continuous variable and a categorical
variable. The distribution of serum TCDD levels of the 15 cases of breast cancer was examined
in relation to the distribution of all women in the SWHS. The median exposure was slightly
higher among with the 15 cases of breast cancer (71.8 ppt) compared to those without (55.1 ppt),
and the exposure distribution among breast cancer cases appeared to be shifted to the right (i.e.,
the exposures were higher but followed the same distribution); however, no formal test of
significance was conducted.

Warner et al. (2002, 197489) used Cox proportional hazards modeling techniques to
evaluate risk of breast cancer in relation to TCDD serum levels while controlling for a variety of
potential risk factors. In all, 21 women had been diagnosed with cancer, and of these, 15 cases
were cancer of the breast. The analysis revealed that for every 10-fold increase in TCDD

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log-serum levels (e.g., from 10 to 100 ppt) the risk of breast cancer increased by 2.1
(95% CI = 1.0-4.6). Risk estimates also were generated across four categories (<20, 20.1-44,
44.1-100, >100 ppt), with the lowest category used as the reference. The RRs estimated in the
third and fourth highest exposure categories were 4.5 (95% CI = 0.6-36.8) and 3.3
(95%) CI = 0.4-28.0). Although statistical significance was not achieved for either category,
likely because of the small number of cases, the greater than threefold risk evident in both
categories is worth noting. Given that the reference category had only one incident case
underscores the limited inferences that can be drawn from these analyses. The authors adjusted
for numerous potential confounders, but observed no differences between the crude and adjusted
results; the authors, therefore, presented unadjusted risks.

2.4.1.1.1.4.2.2. Study evaluation.

The findings from the Warner et al. (2002, 197489) study differ from reports in earlier
studies in which mortality outcomes noted the absence of an SMR association. The design of
this study is much stronger than earlier ones, given the improved characterization of exposure,
the ability to compare incidence rates within the cohort, the ability to control for potential
confounding variables at an individual level, and the availability of incident outcomes. The use
of incident cases (versus mortality data) should also help minimize potential bias due to disease
survival. Another important advantage was the ability to measure TCDD near the time of the
accident, thereby reducing the potential for exposure measurement error.

A potentially important limitation of the Warner et al. (2002, 197489) study was that
information was collected only from those who were alive as of March 1996. Therefore, TCDD
and other relevant risk factor data could not be collected for those who had previously died of
breast cancer. Thirty-three women could not participate because they were either too ill or had
died. Of these, three died of breast cancer. Given that there were only 15 breast cancer cases,
the exclusion of these 3 cases could have dramatically impacted the findings in either direction.

Another limitation was that, at the time of the follow-up, most women were still
premenopausal and therefore, most of the cohort (average age = 40.8 years) had not yet attained
the age of greater risk of breast cancer (average age at diagnosis among the cases in this cohort
was 45.2 years). Although comparable data from Italy were not found, the median age of
diagnosis for breast cancer among U.S. women from 2003-2007 was 61 years (Altekruse et al.,

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2010). An ongoing follow-up of the cohort should be completed by 2010, which should allow
for increased number of incident breast cancers to be identified. Given that the current analyses
were based only on 15 incident cases, this will substantially improve the statistical power of the
study. A secondary benefit is that the increased follow-up will allow for an investigation of
possible differential effects according to the age the women were at the time of exposure.

2.4.1.1.1.4.2.3. Suitability of data for TCDD dose-response modeling.

Several aspects of the Warner et al. (2002, 197489) study are weaknesses in the
consideration of this study for further dose-response modeling. Only 15 cases of breast cancer
were available, and no increases in risk were found with serum TCDD exposures between 20.1
and 44 ppt (n = 2) when compared to those with <20 ppt (n = 1). The average age at the time of
enrollment was 40.8 years while the average age at diagnosis among the cases was 45.2 years.
As most women had not yet reached the age when breast cancer cases are typically diagnosed,
additional follow-up of the cohort would improve the quantitative dose-response analysis and
strengthen this study. A key strength of this study, however, is that Warner et al. (2002, 197489)
includes an investigation of the relationship between individual serum-based measures of TCDD
and cancer in Seveso. Despite the weaknesses, this study meets the evaluation considerations
and criteria for inclusion and will be analyzed for quantitative dose-response modeling.

2.4.1.1.1.4.3. Pesatori et al. (2003, 197001).

2.4.1.1.1.4.3.1. Study summary.

Pesatori et al. (2003, 197001) published a review of the short- and long-term studies of
morbidity and mortality outcomes in the Seveso cohort in 2003. This paper presented cancer
incidence data from 1977 to 1991 for Seveso males and females residing in Zones A, B and R
relative to an external population (i.e., uncontaminated areas). Mortality data are also presented
for a 20-year follow-up (1976-1996) relative to the reference population. As in the original
Bertazzi et al. (2001, 197005) study, RRs were estimated using Poisson regression. No
associations were noted for zone of residence and all cancer mortality for either males or
females. Although no cases were reported in Zones A and B, soft tissues sarcoma was associated
with residence in males from Zone R (RR = 2.6, 95% CI = 1.1-6.3). Among males, residence in
Zones A and B was associated with lymphatic and hematopoietic cancer (RR = 1.9,

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95% CI = 1.1-3.1). This increased risk was due primarily to non-Hodgkin's lymphoma, which
accounted for 8 of the 15 incidence cases (RR = 2.6, 95% CI = 1.3-5.3). Among females,
increased incidence of multiple myeloma (RR = 4.9, 95% CI = 1.5-16.1), cancer of the vagina
(RR = 5.5, 95% CI = 1.3-23.8), and cancer of the biliary tract (RR = 3.0, 95% CI = 1.1-8.2) was
associated with residence in Zones A and B.

2.4.1.1.1.4.3.2.	Study evaluation.

Study limitations of the Pesatori et al. (2003, 197001) study included exposure
misclassification from the use of an ecological measure of exposure (region of residency at time
of accident) and low statistical power for some health endpoints. For e.g., all of the RRs
presented above for specific cancer mortality among females in the Pesatori et al. (2003, 197001)
study were based on fewer than five incident cases.

2.4.1.1.1.4.3.3.	Suitability of data for TCDD dose-response modeling.

As with the studies of mortality among Seveso residents, the Pesatori et al. (2003,

197001) study does not capture TCDD exposure on an individual basis, and soil TCDD levels
considerably vary within each zone. Therefore, the quality of the exposure data is insufficient
for estimating the effective dose needed for quantitative dose-response analysis.

2.4.1.1.1.4.4. Baccarelli et al. (2006, 197036).

2.4.1.1.1.4.4.1. Study summary.

Given previous findings from Seveso, Baccarelli et al. (2006, 197036) examined t( 14; 18)
translocations in the DNA of circulating lymphocytes of healthy dioxin-exposed individuals.
These translocations are associated with the development of cancer, namely follicular
lymphomas. The study included 211 healthy subjects of the Seveso area, and 101 who had
developed chloracne. The investigators analyzed data from 72 high-TCDD plasma level
individuals (>10 ppt) and 72 low-TCDD plasma levels (<10 ppt). A three-level categorical
variable was used to evaluate dose-response. This variable was developed by dividing those
with exposures >10 ppt into two groups: 10- <50 ppt, and 50-475.0 ppt. Trained interviewers
administered a questionnaire that collected data on demographic characteristics, diet, and
residential and occupational history.

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The prevalence of t(14; 18) was estimated as those individuals having a t(14; 18) positive
blood sample divided by the t(14; 18) frequency (number of copies per million lymphocytes).
Baccarelli et al. (2006, 197036) found that the frequency of t( 14; 18) was associated with plasma
TCDD levels, but no association between TCDD and the prevalence of t(14; 18) was detected.

2.4.1.1.1.4.4.2.	Study evaluation.

Whether the frequency of t(14; 18) associated with plasma TCDD levels translates into an
increased risk of lymphoma is uncertain as prospective data of TCDD on those who developed
non-Hodgkin's lymphoma are lacking. Moreover, the t(14; 18) translocation could be an
important event in the pre-B stage cell that contributes to tumorigenicity, however subsequent
exposure to carcinogenic agents might be necessary for t(14; 18) cells to develop into a
malignancy (Hoglund et al., 2004, 199130).

2.4.1.1.1.4.4.3.	Suitability of data for TCDD dose-response modeling.

Given that current TCDD plasma levels were measured for this study, it is unclear if the
effects of lymphocyte translocations may be due to initial high exposure or are a function of the
cumulative exposure for a longer exposure window. Additionally, whether the frequency of
t(14; 18) associated with plasma TCDD levels translates into an increased risk of lymphoma is
unknown. Dose-response analysis for this outcome, therefore, was not conducted.

2.4.1.1.1.4.5. Consonni et al. (2008, 524825).

2.4.1.1.1.4.5.1. Study summary.

Consonni et al. (2008, 524825) analyzed cancer mortality in the Seveso cohort with the
addition of a 25-year follow up period. Similar analytic methods as Pesatori et al. (2003,

197001) were applied with 25 years of follow-up added to the analysis (Consonni et al., 2008,
524825). An important addition in this paper was the presentation of RRs for Zone R, which had
the lowest TCDD levels. Poisson regression models were used to calculate RRs of mortality
using Seregno as the reference population. Cancer deaths observed in Zones A and B were 42
and 244, respectively.

No statistically significant differences in all cancer mortality relative to the reference
population were noted in any of the zones (Zone A: RR = 1.03, 95% CI = 0.76-1.39; Zone B:

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RR = 0.92, 95% CI = 0.81-1.05; Zone R: RR = 0.97, 95% CI = 0.92-1.02). Statistically
significant excesses in mortality from non-Hodgkin's lymphoma (RR = 3.35,
95% CI = 1.07-10.46) and multiple myeloma (RR = 4.34, 95% CI = 1.07-17.52) were observed
in the area with the highest TCDD levels (Zone A). No other statistically significant increases in
cancer mortality relative to the reference population were apparent. The absence of elevated
breast cancer mortality among women in this study was noteworthy, as this finding differs from
the results of a study of Seveso women for which TCDD exposures were estimated using serum
samples (Warner et al., 2002, 197489).

2.4.1.1.1.4.5.2.	Study evaluation.

Although no individual-level data on smoking were available, the potential for
confounding is likely minimal. Independent smoking surveys found that the smoking prevalence
rates in Desio, one of cities affected by the accident, were similar to those in districts just outside
the study area (Cesana et al., 1995, 594366). As mentioned earlier, one would expect elevated
RRs over the entire study period if smoking had biased the study results, and not just after
15-20 years since exposure to TCDD.

2.4.1.1.1.4.5.3.	Suitability of data for TCDD dose-response modeling.

The lack of individual-level exposure data precludes quantitative dose-response modeling
using these data.

2.4.1.1.1.5. Chapaevsk study.

Industrial contamination of dioxin in the Chapaevsk region of Russia has been the focus
of research on the environmentally-induced cancer and other adverse health effects. The
Chapaevsk region is located in the Samara region of Russia and has a population of 83,000. The
region is home to a chemical plant that produced lindane and its derivatives between 1967 and
1987, which are believed to be responsible for local dioxin contamination. Soil sampling has
demonstrated a strong gradient of increased TCDD concentrations with decreased proximity to
the chemical plant (Revich et al., 2001, 199843).

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2.4.1.1.1.5.1. Revich et al. (2001, 199843V

2.4.1.1.1.5.1.1.	Study summary.

Revich et al. (2001, 199843) used a cross-sectional study to compare mortality rates of
Chapaevsk residents to two external populations of Russia and the region of Samara. Mortality
rates for all cancers combined among males in Chapaevsk were found to be 1.2 times higher
when compared to the Samara region as a whole and 1.3 times higher than Russia. Similar to
other studies, statistically significant excess was noted in men (SMR = 1.8, 95% CI = 1.6-1.9)
but not in women (SMR = 0.9, 95% CI = 0.8-1.1). Among men, the excess was highest for the
smoking-related cancers of the lung (SMR = 3.1, 95% CI = 2.6-3.5) and larynx (SMR = 2.3,
95% CI = 1.2-3.8) and urinary organs (SMR = 2.6, 95% CI = 1.7-3.6). Among females, there
was no increased SMR for all cancer sites combined, but excesses for breast cancer (SMR = 2.1,
95% CI = 1.6-2.7) and cancer of the cervix (SMR = 1.5, 95% CI = 1.0-3.1) were statistically
significant.

Revich et al. (2001, 199843) also compared age-standardized cancer incidence rates in
Chapaevsk to those in Samara. Although statistical tests examining these differences were not
reported, higher incidence rates were observed for all cancers combined, cancer of the lip, cancer
of the oral cavity, and lung and bladder cancer among males in Chapaevsk. Considerably lower
cancer incidence rates also were observed for prostate cancer, cancer of the esophagus, and
leukemia/lymphoma among males from Chapaevsk. Among females, incidence rates were
higher in 1998 for all cancers in Chapaevsk when compared to Russia and the Samara region, an
observation that appears somewhat counter to the presented SMR of 0.9 for all cancer mortality
from 1995-1998. Like mortality, rates of breast cancer incidence among women in Chapaevsk
were higher than in Russia, as were rates of cervical cancer. Leukemia/lymphoma rates were
higher among women in Chapaevsk than in those who lived in the reference populations of
Samara and Russia. This finding is contrary to the finding for males who had lower rates of
leukemia/lymphoma in Chapaevsk.

2.4.1.1.1.5.1.2.	Study evaluation.

Although the Revich et al. (2001, 199843) findings suggest TCDD exposures in
Chapaevsk are quite high relative to other parts of the world (Akhmedkhanov, 2002, 197140).
evaluation of health outcomes to date have been based on ecological data only. This analysis did

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not adjust for the influence of other risk factors (e.g., smoking, reproductive characteristics) that
could contribute to increased cancer rates for lung cancer in men and breast cancer in women.
Given that both the SMRs and SIRs for cancer outcomes vary considerably between men and
women, this suggests the possibility that occupational exposures might be a contributing factor in
these adverse health outcomes.

Future research in Chapaevsk includes plans to conduct a breast cancer case-control
study. Women who were born from 1940 onward and who have been diagnosed with breast
cancer before the age of 55 were included in the study, although the plan to characterize TCDD
using serum is uncertain (Revich et al., 2005, 198777).

2.4.1.1.1.5.1.3. Suitability of data for TCDD dose-response modeling.

This study did not meet the considerations and criteria for inclusion in a quantitative
dose-response assessment. Given the lack of exposure data on an individual basis, no effective
dose can be estimated for this study population. As such, no dose-response modeling was
conducted.

2.4.1.1.1.6. The Air Force Health {"Ranch Hands" cohort) study.

Between 1962 and 1971, the U.S. military sprayed herbicides over Vietnam to destroy
crops that opposition forces depended upon, to clear vegetation from the perimeter of U.S. bases,
and to reduce the ability of opposition forces to hide. These herbicides were predominantly a
mixture of 2,4-D, 2,4,5-T, picloram, and cacodylic acid (Institute of Medicine, 2006, 594374). A
main chemical sprayed was Agent Orange, which was a 50% mixture of 2,4-D and 2,4,5-T.
TCDD was produced as a contaminant of 2,4,5-T and had levels ranging from 0.05 to 50 ppm
(Institute of Medicine, 1994, 594376). A series of studies have investigated cancer outcomes
among Vietnam veterans. A review of military records to characterize exposure to
Agent Orange led Stellman and Stellman (1986, 594380) to conclude that assignment of
herbicide levels should not be based solely on self-reports or a crude measure such as military
branch or area of service within Vietnam. Investigations have been performed on the Ranch
Hands cohort, which consisted of those who were involved in the aerial spraying of
Agent Orange between 1962 and 1971. More elaborate methods were used to characterize
exposures among these individuals, and these studies are summarized below.

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2.4.1.1.1.6.1. Akhtar et al. (2004, 197141V
2.4.1.1.1.6.1.1. Study summary.

Akhtar et al. (2004, 19714 0 investigated the incidence of cancer in the Ranch Hand
cohort, which was published after the release of the 2003 Reassessment document (U.S. EPA,
2003, 537122). The Ranch Hand Unit was responsible for aerial spraying of herbicides,
including Agent Orange, in Vietnam from 1962 to 1971. Cancer incidence in the Ranch Hand
cohort were compared to a cohort that included other Air Force personnel who served in
Southeast Asia during the same period but were not involved in the spraying of pesticides.

Health outcomes were identified during the postservice period that extended from the time each
veteran left Southeast Asia until December 31, 1999. In contrast to previous analyses of this
cohort, the Akhtar et al. (2004, 19714 0 study took into account concerns that both the
comparison and spraying cohorts had increased risks of cancer, and addressed the possibility that
workers with service in Vietnam or Southeast Asia might have increased cancer risk. The
authors addressed the latter concern by adjusting risk estimates for the time spent in Southeast
Asia and for the proportion of time spent in Vietnam.

The Ranch Hand cohort comprised 1,196 individuals, and the comparison cohort had
1,785 individuals. The comparison cohort was selected by matching date of birth, race, and
occupation (i.e., officer pilot, officer navigator, nonflying officer, enlisted flyer, or enlisted
ground personnel). TCDD levels were determined using serum levels collected from veterans
who completed a medical examination in 1987. For those who did not have a serum measure
taken in 1987, but provided one in subsequent years, TCDD levels were back-extrapolated to
1987 using a first-order kinetic model that assumed a half-life of 7.6 years. Those with
nonquantifiable levels were assigned a value of the limit of detection divided by the square root
of 2. A total of 1,009 and 1,429 individuals in the Ranch Hand and comparison cohorts,
respectively, provided serum measures that were used in the risk assessment. Veterans also were
categorized according to the time their tours ended. This date corresponded to changes in
herbicide use. These categories were before 1962 or after 1972 (no herbicides were used),
1962-1965 (before Agent Orange was used), 1966-1970 (when Agent Orange use was greatest),
and 1971-1972 (after Agent Orange was used). Information on incident cases of cancer in the
cohort was determined from physical examinations and medical records. Some malignancies
were discovered at death and coded from the underlying causes of death as detailed on the death

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certificate. A total of 134 and 163 incident cases of cancer were identified in the Ranch Hand
and comparison cohort, respectively. Akhtar et al. (2004, 197141) describe case ascertainment
verified by record review as being complete.

External comparisons were made based on the expected cancer experience derived from
U.S. national rates using SIRs and the corresponding 95% confidence interval. Person-years and
events were tabulated by 5-year calendar and age intervals.

When compared to the general population, no statistically significant excesses in all
cancer incidence were observed for either the Ranch Hand (SIR = 1.09, 95% CI = 0.91-1.28) or
the comparison cohort (SIR = 0.94, 95% CI = 0.81-1.10). Statistically significant differences
were found for three site-specific cancers in the Ranch Hands cohort relative to the general
population. Excesses were noted for malignant melanoma (SIR = 2.33, 95% CI = 1.40-3.65)
and prostate cancer (SIR = 1.46, 95% CI = 1.04-2.00). In contrast, a reduced SIR was found for
cancers of the digestive system (SIR = 0.61, 95% CI = 0.36-0.96). The excess in prostate cancer
was also noted in the comparison cohort (SIR = 1.62, 95% CI = 1.23-2.10) relative to the
general population. External comparisons were repeated by restricting the cohorts to the period
when Agent Orange was used (1966-1970). Again, no statistically significant excesses in all
cancer incidence were noted in the Ranch Hand (SIR = 1.14, 95% CI = 0.95-1.37) or
comparison cohort (SIR = 0.94, 95% CI = 0.80-1.11). Statistically significant excesses
continued to be observed for malignant melanoma (SIR = 2.57, 95% CI = 1.52-4.09) and
prostate cancer (SIR = 1.68, 95% CI = 1.19-2.33) in the Ranch Hand component of the cohort.
No other statistically significant differences were found among Ranch Hands personnel.

For internal cohort analyses, veterans were assigned to one of four exposure categories.
Those in the comparison cohort were assigned to the "comparison category." Ranch Hand
veterans that had TCDD serum levels <10 ppt were assigned to the "background" category.

Those with a TCDD levels >10 ppt had their TCDD level estimated at the end of their Vietnam
service with a first-order kinetic model that used a half-life of 7.6 years. These
back-extrapolated values that were less than 118.5 ppt were assigned to a "low" exposure group,
while those with values above 118.5 ppt were classified as "high" exposure. Akhtar et al. (2004,
197141) used Cox regression models to describe risks across the exposure groups using the
comparison category as the reference. Risks were adjusted for age at tour, military occupation,
smoking history, skin reaction to sun exposure, and eye color. Internal cohort analyses were

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restricted to those who spent no more than 2 years in Southeast Asia and Ranch Hand workers
who served exclusively in Vietnam, and the comparison cohort who served exclusively outside
of Vietnam.

Statistically significant excesses of cancer incidence (all sites combined) were observed
in the highest two exposure groups. A statistically significant trend test (p = 0.04) was detected
based on the RRs for the background-, low-, and high- exposure groups: 1.44
(95% CI = 0.82-2.53); 2.23 (95% CI = 1.24-4.00), and 2.02 (95% CI = 1.03-3.95). For
malignant melanoma, the RRs across the three increasing exposure categories were 2.99, 7.42,
and 7.51. The corresponding risk estimates for prostate cancer were 1.50, 2.17, and 6.04.

2.4.1.1.1.6.1.2. Study evaluation.

An important strength of this study is the manner in which TCDD exposure was
estimated. Serum data were available for most veterans, and therefore, generalizing exposure
from a small sample of cohort members is not a concern as was the case with the NIOSH and
Hamburg cohorts. Back-extrapolating to derive past exposures was based on a methodology that
has been applied in many of the cohorts, thereby facilitating risk comparisons. An additional
strength of the study is the examination of incidence as a measure of disease occurrence rather
than mortality.

In contrast to the previous analysis (Ketchum et al., 1999, 198120) the analysis by Akhtar
et al. (2004, 197141) was restricted to individuals who spent no more than 2 years in Southeast
Asia. Previous research had demonstrated that increased time spent in Southeast Asia was
associated with an increased risk of cancer. Confounding might have been introduced given that
the comparison cohort spent much more time in Southeast Asia than the Ranch Hands. To
illustrate, the median number of days spent in Southeast Asia was 790 for comparison cohort
members, and the median days for the Ranch Hand cohort in the background, low, and high
exposure groups were 426, 457, and 397, respectively. After restricting to those who spent at
most 2 years, statistically significant associations were observed for all cancer sites combined,
prostate cancer, and malignant melanoma using the internal cohort comparisons.

An important issue in the study is the high correlation between 2,4,5-T and 2,4-D, given
that both were used in equal concentrations in Agent Orange. As a result, distinguishing the
effects of each is impossible. This point is relevant, given that 2,4-D has been associated with

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prostate cancer in several studies. As a result, the dose-response association with prostate cancer
might be due to 2,4-D exposure and not TCDD. This issue also has implications for the
interpretation of the dose-response pattern for all cancer sites combined, given that incident
prostate cancers accounted for 4 of the 12 incident cases in the high-exposure group.

2.4.1.1.1.6.1.3. Suitability of data for TCDD dose-response modeling.

The ascertainment of incident cases and characterization of exposure to TCDD based on
serum measures are strong features of the cohort. Confounding by 2,4-D is a major concern.
Since delineating the independent effects of other Agent Orange contaminants is not possible,
quantitative dose-response analysis was not conducted on this study.

2.4.1.1.1.6.2. Michalek and Pavuk (2008, 1995731
2.4.1.1.1.6.2.1. Study summary.

Michalek and Pavuk (2008, 199573) recently published an updated analysis of the
incidence of cancer and diabetes in the cohort of Ranch Hand veterans. As with the Akhtar et al.
(2004, 197141) analysis, the study included a comparison cohort of other Air Force veterans who
served in Southeast Asia at the same time but were not involved with the spraying of herbicides.
This study extended previous analyses (Henriksen et al., 1997, 197645; Ketchum et al., 1999,
198120) by addressing the number of days of herbicide spraying, calendar period of service, and
the time spent in Southeast Asia. Veterans who attended at least one of five examinations were
eligible for inclusion. Incident cancer cases also were identified from medical records.

The methods used to determine TCDD exposures were as described above in the review
of the Akhtar et al. (2004, 197141) study. Blood measures also were taken in 1992, 1997, and
2002 for subjects with no quantifiable TCDD levels in 1987, those who refused in 1987, and
those new to the study. TCDD dose at the end of service in Vietnam was assigned to Ranch
Hands that had TCDD levels above background using a a first-order kinetic model and constant
half-life of 7.6 years. Each veteran was then assigned to one of four dose categories: comparison
veteran, background (i.e., Ranch Hands with 1987 levels of TCDD <10 ppt), low (Ranch Hands
with 1987 levels of TCDD 10.1-91 ppt), and high (Ranch Hands with 1987 levels of TCDD
>118.5 ppt). Serum TCDD estimates are available for 1,597 veterans in the comparison cohort,

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and 986 veterans in the Ranch Hand cohort. The comparison cohort was selected by matching
on date of birth, race, and occupation of the Ranch Hands.

Michalek and Pavuk (2008, 199573s) used Cox regression to characterize risks of cancer
incidence across the three upper exposure categories using the comparison category as the
referent group. Risk estimates were adjusted for year of birth, race, smoking, body mass index at
the qualifying tour, military occupation, and skin reaction to sun exposure. Tests for trend for
increased risk of cancer were conducted by testing the continuous covariate logioTCDD.

Overall, no association between the TCDD exposure categories and RR of all-site cancer
was observed. Those in the highest exposure group had an RR of 0.9 (95% CI = 0.6-1.4).
Stratified analyses by calendar period of service showed more pronounced risk for those who
served before 1986 (when higher amounts of Agent Orange were used). A statistically
significant dose-response trend (p < 0.01) was observed for cancer risk and logioTCDD
exposure. The RRs for the background, low, and high groups used in these comparisons were
0.7 (95% CI = 0.4-1.3), 1.7 (95% CI = 1.0-2.9), and 1.5 (95% CI = 0.9-2.6). A statistically
significant increase, however, was noted when analyses were restricted to those who had sprayed
for at least 30 days before 1967 and spent time in Southeast Asia (RR = 2.2, 95% CI = 1.1-4.4).

2.4.1.1.1.6.2.2.	Study evaluation.

Michalek and Pavuk (2008, 199573) used the same study population that Akhtar et al.
(2004, 197141). and so it has the same strengths and limitations as noted above. The follow-up,
however, extends an additional 5 years (until the end of 2004). The findings for the
dose-response analyses were not as compelling as the earlier Akhtar et al. (2004, 197141)
findings.

2.4.1.1.1.6.2.3.	Suitability of data for TCDD dose-response modeling.

The key limitation precluding dose-response analysis for the Michalek and Pavuk (2008,
199573) study is the possible confounding from the inability to control for 2,4-D and other
agents used in Agent Orange. As such, quantitative dose-response analysis was not conducted
on this study.

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2.4.1.1.1.7. Other studies of potential relevance to dose-response modeling.

2.4.1.1.1.7.1. Hooiveld et al. (1998, 197829)—Netherlands workers.

2.4.1.1.1.7.1.1. Study summary.

Hooiveld et al. (1998, 197829) re-analyzed the mortality experience of a cohort of
workers employed in two chemical plants in the Netherlands using 6 additional years of
follow-up from an earlier study (Bueno et al., 1993, 196993). The cohort consisted of those
employed between 1955 and June 30, 1985, and vital status was ascertained until
December 31, 1991 (i.e., 36 years of follow-up). These cohort members were involved in the
synthesis and formulation of phenoxy herbicides, of which the main product was
2,4,5-trichlorophenoxyacetic acid and monochloroacetic acid. This cohort, with a shorter
follow-up interval than the original study (t' Mannetje et al., 2005, 197593), was included in the
IARC international cohort. The cohort consisted of 1,167 workers, of which 906 were known to
be alive at the end of the follow-up. The average length of follow-up was 22.3 years, and only
10 individuals were lost to follow-up.

The authors used detailed occupational histories to assign exposures. Workers were
classified as exposed to phenoxy herbicides or chlorophenols and contaminants if they worked in
selected departments (i.e., synthesis, finishing, formulation, packing, maintenance/repair,
laboratory, chemical effluent waste, cleaning, shipping-transport, or plant supervision); were
exposed to the accident in 1963; or were exposed by proximity (i.e., if they entered an exposed
department at least once a week). The 1963 accident was the result of an uncontrolled reaction
in the autoclave in which 2,4,5-trichlorophenol was synthesized; an explosion resulted, with
subsequent release of PCDDs that included TCDD. Based on these methods of exposure
assignment, 562 workers were deemed to be exposed to phenoxy herbicides or chlorophenols,
and 567 were unexposed. Due to limited information, 27 workers were classified as having
unknown exposure.

TCDD exposures also were assigned using serum measured on a sample of workers who
were employed for at least 1 year and first started working before 1975. Dioxin-like compounds
including PCDDs were also measured in the serum samples but were not analyzed for this study.
Of the 144 subjects who were invited to provide samples, 94 agreed. TCDD levels were
back-extrapolated to the time of maximum exposure using a one-compartment, first-order kinetic
model that used a half-life estimate of 7.1 years. The mathematical model used was

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ln(TCDDmax) = ln(TCDD) + lag x ln(2)/7.1. The lag was defined as the number of years since
last exposure for those exposed by virtue of their normal job duties. For those exposed as a
result of the accident in 1963, the lag was defined as the number of years since the accident
occurred.

The authors made external comparisons of cohort mortality to the Netherlands population
using the SMR statistics. Poisson regression was used to perform internal cohort comparisons
using unexposed workers as the referent. RRs (measured using rate ratios) generated from the
Poisson model also were used to compare mortality based on low, medium, and high TCDD
serum-derived categories. The Poisson model included the following covariates as adjustment
factors: age, calendar period at end of follow-up, and time since first exposure.

When compared to the general population, workers had an excess mortality from cancer
(SMR = 1.5, 95% CI = 1.1-1.9), based on 51 cancer deaths. Generally, no excesses were
observed for site-specific cancers. The exception included eight deaths from cancers of the
urinary organs (SMR = 3.9, 95% CI = 1.7-7.6). Although not statistically significant, SMRs
comparable in magnitude to other studies were detected for non-Hodgkin's lymphoma
(SMR = 3.8, 95% CI = 0.8-11.0) and Hodgkin's disease (SMR = 3.2, 95% CI = 0.1-17.6). A
statistically significant excess of cancer mortality (n = 20 deaths among occupational workers)
also was also observed relative to the general population when analyses were restricted to those
exposed as a result of the 1963 accident (SMR = 1.7, 95% CI = 1.1-2.7). Three deaths from
prostate cancer were also noted among these workers (SMR = 5.2, 95% CI = 1.1-15.3), but no
excess was observed with any other cancer site.

Internal cohort comparison also demonstrated an increased risk of all cancer mortality
among those exposed to phenoxy herbicides, chlorophenols, and contaminants relative to those
unexposed (RR = 4.1, 95% CI = 1.8-9.0). A statistically significant increased risk was also
noted for respiratory cancer mortality (RR = 7.5, 95% CI = 1.0-56.1). Analyses across
categories of TCDD exposure revealed excesses in cancer mortality for all cancer sites
combined; however, no dose-response trend was apparent.

2.4.1.1.1.7.1.2. Study evaluation.

Several other studies that have characterized cohorts by TCDD levels have used the area
under the curve approach and thus have derived an exposure metric that is time dependent.

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Hooiveld et al. (1998, 197829) instead created an exposure metric to capture the maximum
exposure attained during the worker's employment. Characterizing risks using this metric
assumes that other TCDD exposures accrued during a workers' lifetime are not relevant
predictors of cancer risk.

2.4.1.1.1.7.1.3. Suitability of data for TCDD dose-response modeling.

One study limitation is that although dioxin-like compounds were measured in the serum
samples, Hooiveld et al. (1998, 197829) reported associations with mortality for TCDD only.
There is some utility to examining dose-response analyses using alternative exposure metrics as
those constructed in this cohort. However, the small number of identified cancer deaths,
limitations in terms of the exposure assignment (based on nonrepresentative sample, and
maximum exposure level) and concern over potential confounding by co-exposures preclude
using these data for a dose-response analysis.

2.4.1.1.1.7.2. t' Mannetje et al. (2005, 197593)—New Zealand herbicide sprayers.
2.4.1.1.1.7.2.1. Study summary.

t" Mannetje et al. (2005, 197593) described the mortality experience of a cohort of New
Zealand workers who were employed in a plant located in New Plymouth. The plant produced
phenoxy herbicides and pentachlorophenol between 1950 and the mid-1980s. This study
population also was included in the international cohort of producers and sprayers of herbicides
that was analyzed by I ARC (Kogevinas et al., 1997, 198598; Saracci et al., 1991, 199190). In
this 2005 study, analyses were restricted to those who had worked at least 1 month; clerical,
kitchen, and field research staff were excluded. The authors followed up 1,025 herbicide
producers and 703 sprayers from 1969 and 1973, respectively, until the end of 2000.

The cohort consisted of two components: those involved with the production of
herbicides and those who were sprayers. For the herbicide producers, exposures were
determined by consulting occupational history records; no direct measures of exposure were
available. Each department of employment was assigned to one of 21 codes as in the IARC
international cohort (Saracci et al., 1991, 199190). Industrial hygienists and factory personnel
with knowledge of potential exposures in this workforce classified each job according to
potential to be exposed to TCDD, other chlorinated dioxins, and phenoxy herbicides. Exposure

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was defined as a dichotomous variable (i.e., exposed and unexposed). Among producers, 813
were classified as exposed, with the remaining 212 considered unexposed.

The "sprayer" component of the cohort includes those who were registered in the national
registry of applicators at any time from January 1973 until the end of 1984. For the sprayers,
detailed occupational information was lacking. Exposure was, therefore, based on an exposure
history questionnaire completed in a previous study of congenital malformations (Smith et al.,
1982, 198586). This questionnaire, administered to 548 applicators in 1980 and 232 applicators
in 1982, achieved a high response rate (89%). Participants were asked to provide information
about 2,4,5-T-containing product use on an annual basis from 1969 up to the year the survey was
completed. As the use of 2,4,5-T ceased in the mid-1980s, data on occupational exposure to
TCDD among these workers are fairly complete. Virtually all sprayers (699 of 703) were
exposed to TCDD, higher chlorinated dioxins, and phenoxy herbicides.

Deaths among workers were identified through record linkage to death registrations in the
New Zealand Health Information Service. Electoral rolls, drivers' licenses, and social security
records also were consulted to confirm identified deaths. External comparisons of mortality
were made to the New Zealand population using the SMR statistic. The mortality follow-up for
the producers began on January 1, 1969 and extended until December 31, 2000. For the
sprayers, the follow-up period extended from January 1, 1973 until December 31, 2000. A total
of 43 cancer deaths occurred in the producer group and 35 cancer deaths occurred in the sprayer
group in the cohort. Where possible, stratified analyses by duration of employment and
department were conducted. The departments examined for producers included synthesis,
formulation and lab, maintenance and waste, packing and transport, other, and unexposed.

SMRs were generated using the New Zealand population as an external referent. A linear test
for trend was applied to evaluate dose-response trends according to categories of duration of
employment. Stratified analyses also were also done for sprayers who started working before
1973, as TCDD levels in 2,4,5-T produced at the New Zealand plant dropped dramatically after
1973. Although an SMR was presented for female producers, given that only one cancer death
was observed, this study can provide no insight on differential risks between the sexes.

Among TCDD-exposed producers, for all cancers combined, no statistically significant
excess mortality was found when compared to the general population (SMR = 1.24,
95% CI = 0.90-1.67). No dose-response trend in the SMRs for all cancers was observed with

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duration of employment (p = 0.44). No statistically significant elevated SMR was observed in
any of the duration of employment categories for any of the six specific departments examined.
A statistically significant positive linear trend, however, was noted among synthesis workers
(p = 0.04). There was some suggestion of reduced mortality in the upper exposure levels for
workers in the formulation and lab departments. For sprayers, the SMR for all cancer sites
combined was not elevated relative to the New Zealand general population (SMR = 0.82,
95% CI = 0.57-1.14), nor was a dose-response pattern observed with increasing duration of
employment (p = 0.86). Additionally, no statistically significant excess in cancer mortality for
all sites combined was evident in workers who were first employed either before 1973
(SMR = 0.75, 95% CI = 0.50-1.07) or from 1973 on (SMR = 1.81, 95% CI = 0.59-4.22). For
site-specific analyses of cancer mortality, an excess of multiple myeloma was observed among
production workers relative to the general population (SMR = 5.51, 95% CI = 1.14-16.1). This
SMR was based on three deaths. No statistically significant excess (or deficit) of mortality was
found for any other cancer site examined in either the sprayers or the producers.

2.4.1.1.1.7.2.2. Study evaluation.

The physical activity demands of spraying contribute to a healthy worker effect that
manifests itself in a lower SMR based on both external comparisons to the general population as
a referent, and the SMR generated for the producers in the cohort. The analyses conducted using
a simple dichotomy of exposure and duration of employment are limited, as nearly all of the
sprayers were unexposed.

The dose-response pattern with duration of employment coupled with the observation
that higher levels of exposure to TCDD occurred among workers in the synthesis department is
an important finding. These workers were also exposed to several other contaminants, however,
that include processing chemicals, technical products, intermediates, and byproducts (Kauppinen
et al., 1993, 594388). These included phenoxy herbicides and dioxin-like compounds such as
chlorinated dioxins. Since the dichotomous exposure measure was based on exposure to TCDD,
chlorinated dioxins and phenoxy herbicides, the associated dose-response analyses presented in
this study should be interpreted cautiously in light of the inability to either characterize or control
for these potential confounders. As such, these co-exposures might have contributed to the
dose-response pattern observed with increased duration of employment in the synthesis workers.

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2.4.1.1.1.7.2.3. Suitability of data for TCDD dose-response modeling.

Although the study authors completed a subsequent analysis of this cohort using
serum-derived TCDD (McBride, 2009, 198490). the lack of individual-level TCDD exposures
precludes dose-response modeling.

2.4.1.1.1.7.3. McBride et al. (2009, 198490)—New Zealand herbicide sprayers.

2.4.1.1.1.7.3.1. Study summary.

McBride et al. (2009, 198490) recently published the mortality experience of the New
Zealand cohort in relation to serum estimates of TCDD levels. This study included
1,599 workers who were employed between 1969 and November 1, 1989, which was the date
that 2,4,5-T was last used. As in their study published earlier in the same year (McBride et al.,
2009, 197296), the follow-up period extended from the first day of employment until
December 31, 2004. Vital status was ascertained through record linkage to the New Zealand
Health Information Service Mortality Collection and the Registrar General's Index to Deaths for
deaths up to 1990.

All current and former workers who lived within 75 km of the plant were invited to
provide serum samples. A total of 346 of the eligible workers (68%) provided samples, which
represented 22% of the overall study population (346/1599). Based on the serum measures, 70%
(241/346) had been exposed to TCDD. This percentage is similar to the estimated 71% of
workers who were deemed to have been exposed based on a review of occupational records. The
mean serum TCDD value was 9.9 ppt. The highest exposures were observed for those employed
in the trichlorophenol operation (23.4 ppt). Values among unexposed workers averaged 4.9 ppt,
which is close to the background level of 3.9 ppt among individuals of similar age in the New
Zealand general population (Bates et al., 2004, 197113). Details on smoking histories of
individuals were also collected for the 346 individuals who provided serum, allowing for an
examination of the potential confounding role that smoking might have on derived risk estimates
for TCDD.

Cumulative exposure to TCDD as a time-dependent metric was estimated for each
worker. A detailed description of the methods used to derive TCDD exposure was described in
Ay 1 ward et al. (2009, 197187). The qualitative TCDD scores available for those with serum
measures were used to estimate the cumulative exposures based on a half-life of approximately

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7 years. A time-dependent estimate of TCDD exposure was derived and the area under the curve
was used to obtain cumulative workplace TCDD exposure above background levels. Model
performance appears modest as the model explained only 30% of the variance (adjusted R2)
when these TCDD exposure estimates were compared with actual serum levels (Aylward et al.,
2009, 197187V

As with previous analyses of the cohort (McBride et al., 2009, 197296; t' Mannetje et al.,
2005, 1975931 external comparisons to the New Zealand general population were made using
the SMR statistic. The SMR statistic also was used to compare mortality across four exposure
groups relative to the general population, as defined by the serum TCDD estimates: 0-68.3,
68.4-475.0, 475.1-2085.7, and >2085.8 ppt-month. The proportional hazards model also was
used to conduct internal cohort comparisons across these same four exposure groups. In these
analyses, age was used as the time variable, and the covariates of date of hire, sex, and birth year
were included in the proportional hazards model. The cut-points for these four exposure
categories were chosen so that approximately equal numbers of deaths were included in each
category.

Consistent with earlier SMR analyses of the same cohort, no increased cancer mortality
was observed among "ever" exposed workers in this cohort when compared to the general
population (SMR =1.1, 95% CI = 0.9-1.4). No statistically significant excess was noted for any
of the site-specific cancers, although there was some suggestion of increased risk of soft tissue
sarcoma (SMR = 3.4, 95% CI = 0.1-19.5), multiple myeloma (SMR = 2.2, 95% CI = 0.2-8.1),
non-Hodgkin's lymphoma (SMR = 1.6, 95% CI = 0.3-4.7), and cancer of the rectum
(SMR = 2.0, 95% CI = 0.7-4.4). No statistically significant increases in cancer mortality (all
sites combined) was found in any of the four exposure categories as measured by the SMR
statistic, nor was a dose-response trend noted with increasing exposure categories. No
dose-response trends (based on SMR analyses) were noted for five site-specific cancers
examined (i.e., digestive organs, bronchus, trachea and lung, soft tissue sarcomas, lymphatic and
hematopoietic tissue, and non-Hodgkin's lymphoma), although SMRs for three of the
four exposure categories exceeded 2.0 for non-Hodgkin's lymphoma.

In contrast to the external cohort comparisons, the RRs generated with the proportional
hazards model supported a dose-response trend, as rate ratios increased across increasing TCDD
exposure categories. The RRs and their 95% confidence intervals relative to the lowest of the

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four groups were 1.05 (95% CI = 0.48-2.26), 1.38 (95% CI = 0.64-2.97) and 1.58

(95% CI = 0.71-3.52). Neither the linear (p = 0.29) or quadratic (p = 0.82) test for trend,

however, was statistically significant. An increased risk of lung cancer mortality was observed

in the highest TCDD exposure category relative to the lowest (RR = 5.75,

95% CI = 0.76-42.24). The tests for trend for lung cancer, however, also were not statistically

significant.

A smoking survey was administered to a sample of surviving workers of this cohort, and
smoking prevalence was found to be slightly higher among those with higher cumulative
exposure (61%) compared to lower exposures (51-56%). These minor differences in smoking
prevalence unlikely was a strong enough confounder to explain the fivefold increase in risk of
lung cancer found in the highest exposure category. Although the smoking data assessment was
a strength of the study, it was limited to only sample of workers and was not available for those
who died of lung cancer.

2.4.1.1.1.7.3.2. Study evaluation.

Given high rates of emigration, loss to follow-up (22%) was a potential concern in this
study. If comparable emigration rates did occur among the general population then the SMRs
would be underestimated. It is unclear to what extent emigration occurred among the general
population and whether emigration in both the worker and general populations was dependent on
health status. If emigration rates were comparable among these two populations, the associated
bias from the under-ascertainment of mortality in the lost to follow-up group would likely
attenuate a positive association between TCDD and cancer mortality. Among the worker
population, there was not much evidence of differential loss to follow-up with respect to
exposure as average exposures were lower (3.2 ppt) among those loss to follow up compared to
those with complete follow-up (5.7 ppt). Previous studies among this population also found
slightly higher loss to follow-up rates among the unexposed (23%) compared to the exposed
(17%>) workers (t' Mannetje et al., 2005, 197593).

McBride et al. (2009, 198490) did not present results using a continuous measure of
TCDD exposure (lagged or untagged) as was done in most other occupational cohorts.
Additionally, the modeling did not consider the use of different periods of latency.

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2.4.1.1.1.7.3.3. Suitability of data for TCDD dose-response modeling.

There is no evidence that the authors considered exposure metrics that are consistent with
environmental cancer-causing agents such as exposure modeling that takes latency into account.
Given that past occupational cohort studies of TCDD-exposed workers have consistently
demonstrated stronger association with lag interval of 15 years, such an approach should be
applied to this cohort. This precludes this study from consideration for quantitative
dose-response modeling.

2.4.1.1.1.7.4. McBride et al. (2009, 197296)—New Zealand herbicide sprayers.

2.4.1.1.1.7.4.1. Study summary.

McBride et al. (2009, 197296) published an updated analysis of the mortality of the New
Zealand cohort. The follow-up period was from January 1, 1969 to December 31, 2004
extending the previous study by an additional 4 years. In contrast to the previous study where
the cohort comprised individuals employed for at least 1 month prior to 1982 (or 1984)
(t' Mannetje et al., 2005, 197593). the cohort in this study consisted of all those who worked at
least one day between January 1, 1969 and October 1, 2003. This resulted in a cohort of
1,754 workers, of which 247 died in the follow-up interval. Seventeen percent of the cohort
members were lost to follow-up, which could be a source of selection bias if loss to follow-up
was related to both the exposure metrics and the health outcome of interest. Previous data from
this cohort (t' Mannetje et al., 2005, 197593). however, showed fairly comparable loss to follow-
up rates among the unexposed (23%) and the exposed populations (17%).

Comparisons to the New Zealand general population were made using the SMR statistic.
Stratified analyses were conducted by duration of employment (<3 months, >3 months), sex,
latency (<15 years, >15 years), and period of hire (<1976, >1976). The authors defined latency
as the period between the day last worked and the earliest of date of death, date of emigration or
loss to follow-up, or December 31, 2004.

The overall SMR for mortality from all cancer sites combined relative to the New
Zealand population was 1.01 (95% CI = 0.85-1.10). Although not statistically significant there
was suggestion of an increased risk of rectal cancer (SMR = 2.03; 95%CI = 0.88-4.01) among
the employees. SMRs for lymphatic and hematopoietic cancers (overall SMR = 1.21,
95% CI = 0.52-2.39) included 3.12 (95% CI = 0.08-17.37) for Hodgkin's disease,

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1.59 (95% CI = 0.43-4.07) for non-Hodgkin's lymphoma and 3.73, 95% CI = 1.20-8.71), and
1.66 (95%) CI = 0.20-5.99) for multiple myeloma. No statistically significant excess of cancer
mortality was noted among workers employed for <3 months (SMR = 1.19,

95% CI = 0.65-2.00), or for >3 months (SMR = 0.98, 95% CI = 0.75-1.26). A statistically
significant excess of digestive cancers was found for those who worked fewer than 3 months
relative to the New Zealand population (SMR = 2.52, 95% CI = 1.15-4.78). No excesses were
observed for any site-specific cancers when analyses were restricted to those who worked for 3
or more months. No statistically significant elevated SMRs were found for all cancers
(combined) either for a latency period of fewer than 15 years (SMR = 1.14, 95% CI = 0.72-1.71)
or a latency period of >15 years (SMR = 0.96, 95% CI = 0.72-1.26). Similarly, no statistically
significant excess in cancer mortality was observed for all cancer sites combined, or any
site-specific cancer when analyses were stratified by date of hire (<1976, >1976) or by sex. The
SMR among women who were employed at the site was 0.68 (95% CI = 0.45-1.00).

2.4.1.1.1.7.4.2.	Study evaluation.

High rates of emigration in New Zealand (9% among workers in the cohort) contributed
to a fairly high loss to follow-up (22% among workers) during the study period. The loss to
follow-up would reduce the overall mortality estimates among the workers, which could
underestimate the SMRs if loss to follow-up (and health status) was not comparable in the
general population. For example, it is unclear if workers and the general population who
emigrated were sicker than those remaining in the cohort. Previous data from the cohort workers
suggests that loss to follow-up rates were slightly higher among the low and unexposed
populations (McBride, 2009, 198490; t' Mannetje et al., 2005, 197593) worker population, so
presumably the highly exposed workers were not lost to follow-up more so than other workers.

2.4.1.1.1.7.4.3.	Suitability of data for TCDD dose-response modeling.

This study extended the mortality follow-up and included stratified analyses to
investigate effect modification by period of latency, sex, and date of hire. A key limitation was
the lack of direct measures of exposure for study participants which precluded estimating
effective dose needed for dose-response modeling. This study did not meet the considerations
and criteria for inclusion in quantitative dose-response analysis.

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2.4.1.1.2.	Key characteristics of epidemiologic cancer studies

See Table 2-1 at the end of the chapter for a comparison of the length of follow-up,
latency period used, the half-life for TCDD used, and the fraction of TEQs accounted for by
TCDD (when applicable) for each study.

2.4.1.1.3.	Feasibility of TCDD cancer dose-response modeling—summary discussion by
cohort

2.4.1.1.3.1. Usins the NIOSH cohort in dose-response modelin2.

It is important to evaluate the NIOSH cohort in cancer dose-response modeling of TCDD.
This cohort is the largest assembled to date, direct measures of TCDD based on sampling are
available, and the lengthy follow-up interval allows for latent effects to be taken into account.
Further, although this cohort consists mostly of male workers, these workers were occupationally
exposed to TCDD daily, as compared to the acute accidental exposures of other occupational
cohorts. Although the most recent analyses of a subset of the NIOSH cohort showed no
association between serum TCDD levels and cancer mortality, the study authors did not examine
latency effects (Collins et al., 2009, 197627). Incorporation of latency intervals is important in
light of the stronger dose-response relationships that consistently have been observed with a
15-20 year latency interval in previous investigations of the NIOSH and other cohorts
(Steenland et al., 2001, 197433).

Most published studies of the NIOSH cohort did not evaluate exposures to dioxin-like
compounds. An exception is the analysis by Steenland et al. (2001, 197433). Although
Steenland et al. (2001, 197433) did not incorporate individual-level data on dioxin-like
compounds, based on their previous work (Piacitelli et al., 1992, 197275) they assumed that TEQ
occupational exposures occurred as a result of TCDD alone in this population. TCDD exposures
provided a better fit to the data than the TEQ-based metric, and 15-year latencies improved the
fit for both metrics (relative to untagged exposures). The lifetime risk estimates for an increase
in 10 TEQs (pg/kg of body weight/day/sex) ranged from 0.05-0.18%. The value added for this
measure is the incorporation of the contribution of other dioxin-like compounds to the
background rates.

Blue collar workers, such as those in the NIOSH cohort, typically have higher rates of
smoking than the general population (Bang and Kim, 2001, 197081; Lee et al., 2007, 594391).

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This potential source of confounding would be expected to produce a higher SMR for lung
cancer mortality, and could contribute to the excess noted in the cohort with longer lag intervals.
This bias, however, likely is not large as no statistically significant excess of nonmalignant
respiratory mortality was found in these workers. Any associated bias from smoking would be
expected to be smaller for comparisons conducted within the cohort, as fellow workers would be
expected to be more homogeneous with respect to their risk factor profile than with an external
general population referent group. Stratified analyses using both internal and external
comparison groups also did not identify important differences in associations with TCDD
exposure between smoking and nonsmoking cancers. Thus, fatal cancer risk estimates reported
for workers in the NIOSH cohort appear to provide a reasonable estimate of the carcinogenic
potency of TCDD.

Although the Steenland et al. (2001, 197433) study did not directly account for the
possible confounding effects of other occupational exposure, the authors did address this source
of potential bias. No known occupational exposures to carcinogens occurred, with the exception
of 4-aminobiphenyl, which occurred at one plant. Two deaths from mesothelioma also occurred
in the cohort, so some exposure to asbestos might also have occurred in the cohort (Fingerhut
et al., 1991, 197375). The statistical analyses suggested that the inability to control for other
occupational exposures would not have unduly affected risk estimates generated from internal
cohort comparisons. For instance, the removal of one plant at a time from the analysis did not
materially change dose-response estimates generated from the Cox model (Cheng et al., 2006,
523122). Moreover, adding a variable to represent plant in the Cox regression had little impact
on the risk estimates. Given that other occupational exposures varied by plant, a change in risk
estimates would be expected if such exposures were strong confounders.

The Cheng et al. (2006, 523122) analysis provides important information about the
impact of applying kinetic models to the data. The CADM TCDD kinetic model resulted in
dramatic decreases in the TCDD cancer mortality risk estimates when compared to the one-stage
compartmental model that had been applied. Although Cheng et al. (2006, 523122) suggested
that the CADM model provides a better fit to the data than the typically used simple
one-compartmental model, statistical comparisons of model fit were not reported. Therefore,
there is value in presenting the range in risk estimates across different models when
characterizing dose-response relationships.

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Finally, the half-life of TCDD is generally recognized to vary according to body fat
percentage, data that were not available for the NIOSH workers. The inability to account for
between-worker variability in body fat would introduce exposure measurement error. That body
fat percentage would not be expected to correlate with cumulative exposure to TCDD exposure,
however, would limit the potential for misclassification bias. The effect of any nondifferential
exposure measurement error likely would serve to attenuate the risk estimates of the study.

2.4.1.1.3.2. Usins the BASF cohort in dose-response modelin2.

The availability of blood lipid data for TCDD allows for characterization of cumulative
TCDD exposures in the BASF cohort. TCDD blood lipid data were collected for 90% of the
surviving members of the cohort (138 of 154) and these serum measures were used to generate
TCDD exposure estimates for all 254 cohort members. Therefore, the potential for
misclassification from extrapolating these exposures to the entire cohort may not be as likely as
for the NIOSH cohort where sera data were available for only a small fraction of workers. These
data were, however, collected long after the accident (36 years) and had to be back-extrapolated
to derive the initial exposures.

The data on this cohort included several risk factors such as cigarette smoking and body
mass index. One advantage is that cumulative TCDD levels by body mass index can be
estimates on an individual-level basis. As expected, the derived cumulative measures appear to
compare well with severity scores of chloracne. The finding that more pronounced risks are
found 15-20 years after first exposure are also consistent with findings from several other
cohorts (Bertazzi et al., 2001, 197005; Fingerhut et al., 1991, 197375; Manz et al., 1991,

1990611

One key limitation of the BASF cohort is its relatively small sample size (n = 243), which
limits the ability to evaluate dose-response relationships for site-specific cancers. Also, the
quality of the ascertainment of cancer incidence cannot be readily evaluated as the geographic
area of the cohort is not covered by a tumor registry. Ott and Zober (1996, 19810'Q state that
nonfatal cancers could have been more likely to be missed in early years, which could partially
contribute to the larger standardized incidence ratio found for cancer with longer latencies.
Commenting on risk differences derived from incident and decedent cancer outcomes is difficult.
Among those comprising the cohort, the ascertainment of incident outcomes was recognized to

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be less complete in early years. Although the ascertainment of mortality outcomes was generally
regarded to be good among the 243 workers, some workers who died or moved likely were
missed when the cohort was constructed. These deaths would have been more likely to have
occurred several years before the second component of the cohort was assembled.

The use of the SMR statistic for this study population is associated with important
sources of uncertainties. Deaths were surely missed, particularly for the third component of the
cohort that accounts for approximately 38% (94/247) of the entire cohort; this factor would serve
to underestimate the overall SMR. As mentioned before, this component of the cohort was
assembled through the recruitment of workers known to be alive in 1986. Despite this limitation,
the characterization of exposure data and availability of other risk factor data at an individual
level allow the development of quantitative dose-response analyses.

2.4.1.1.3.3. Usins the Hamburg cohort in dose-response modeling.

The Hamburg cohort lacked data on cigarette smoking, and, therefore, effect estimates
could not be adjusted for this covariate. Additional analyses that excluded lung cancers resulted
in an even stronger dose-response relationship between all cancer mortality and TCDD. Serum
levels of TCDD also were also not associated with smoking status in a subgroup of these workers
(Flesch-Janys et al., 1995, 197261) suggesting that smoking is not likely a confounder of the
association between all cancer mortality and TCDD.

An important limitation of the cohort is the reliance on blood and tissue measurements of
190 workers that likely represent a highly selective component of the cohort. This subset of
workers was identified at the end of the observation period, and therefore, excludes workers who
died or could not be traced. There are uncertainties in deriving department- and period-specific
estimates for a period that extends over three decades using this number of workers.

Additionally, the criteria applied to the reference population could have introduced some bias.
Workers were included only in the reference group if they had been employed for at least
10 years in a gas supply industry. The criteria were much different for the workers who were
exposed to TCDD (only 3 months of employment). As a result, the reference group likely would
be more susceptible to the healthy worker effect. Internal cohort comparisons, which should be
void of such bias, however, generally produced results similar to those based on the external
comparison population. Therefore, the Becher et al. (1998,	T) study meets the criteria and

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additional epidemiological considerations which allowed for development of quantitative
dose-response analyses.

2.4.1.1.3.4. Usins the Seveso cohort in dose-response modelin2.

Unlike many of the occupational cohorts that were examined, data from the Seveso
cohort are representative of a residential population whose primary exposure was from a single
TCDD release. A notable exception is the BASF cohort where workers were exposed primarily
through two accidents that occurred in the plant. The Seveso data, therefore, might permit
cancer dose-response investigations in women and children.

Uncertainty in identifying the critical exposure window for most of the outcomes related
to the Seveso cohort is a key limitation. An important feature of the Seveso cohort, however, is
that TCDD levels were much lower among those in the highest exposure zones in Seveso
(medians range from 56-136 ng/kg) (Eskenazi et al., 2004, 197160) than those in the
occupational cohorts who had TCDD exposures that were sometimes more than 1,000 ng/kg.
Given these dramatic differences in exposures, the standardized mortality ratios (after
incorporating a 15-20 year latency period) for all cancer sites combined are remarkably similar
between the Seveso and the occupational cohort analyses. Perhaps more importantly, the data
from Seveso might be more relevant for extrapolating to lower levels, given that exposures to
TCDD are two orders of magnitude higher than background levels (Smith and Lopipero, 2001,
198585).

The Warner et al. (2002, 197489) study found a positive association between serum
levels of TCDD and breast cancer. As noted previously, ascertainment of incident cases for all
cancers would allow for a dose-response relationship to be evaluated. Moreover, future breast
cancer analyses in this cohort should strengthen the quantitative dose response analyses of this
specific cancer site. The strengths of the Warner et al. (2002, 197489) study outlined earlier
suggest that this study should be considered for cancer dose-response modeling.

Earlier Seveso studies likely are unsuitable for conducting quantitative risk assessment.
These previous studies used an indirect measure of TCDD exposure, namely, zone of residence.
Soil concentrations of TCDD varied widely in these three zones (Zone A: 15.5-580.4 ppt;

Zone B: 1.7-4.3 ppt; and Zone R: 0.9-1.4 ppt), which could have resulted in considerable
exposure misclassifi cation. The Warner et al. (2002,. !9) study greatly improved the

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characterization of TCDD exposure using serum measures, and also allowed for control of
salient risk factors that may have resulted in bias due to confounding.

At this time it is unclear whether any study has examined the relationship between cancer
and serum estimates of TCDD among Seveso males exposed from the 1976 accident.

2.4.1.1.3.5.	Usins the Chapaevsk related data in dose-response modelins.

Currently, individual-level exposure data are lacking for residents of this area and there is
no established cohort for which cancer outcomes can be ascertained. These limitations,
therefore, preclude the inclusion of Chapaevsk data in a quantitative dose-response analysis.

2.4.1.1.3.6.	Usins the Ranch Hands cohort in dose-response modelins.

An important limitation of the Ranch Hands cohort for TCDD and cancer dose-response
modeling is an inability to isolate TCDD effects from the effects of other agents found in the
associated herbicides. Exposure to other dioxin-like compounds was not estimated in this study
and could confound the previously reported associations. As such, dose-response analyses on
this population were not conducted.

2.4.1.1.4. Discussion of general issues related to dose-response modeling
2.4.1.1.4.1. Ascertainment of exposures.

Several series of epidemiological data have used serum measures to estimate TCDD
levels. Serum data offer a distinct advantage in that they provide an objective means to
characterize TCDD exposure at the individual level. The serum measures in the occupational
cohorts, however, are limited in two important ways. First, these samples are generally collected
from small subsets of the larger cohorts; therefore, using these measures to extrapolate to the
remainder of the cohort could introduce bias due to exposure misclassification. The
second limitation is related to estimating the half-life of TCDD. As noted previously, exposures
to TCDD were back-extrapolated several decades from serum samples collected among
surviving members of several cohorts. This approach was used in the NIOSH, Ranch Hands,
BASF, New Zealand, and Hamburg cohorts. The reported half-life of TCDD among these
populations was reported between 7.1 to 9.0 years and shown to vary with several individual
characteristics including age, body fat composition, and smoking. The derivation of half-lives
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from a sample of workers, and application of these estimates to retrospectively characterize
exposure can introduce uncertainty into the lifetime exposure estimates. It is important to note,
however, that sensitivity analyses results in several studies have been fairly consistent when
evaluating the impact of half-life of TCDD (Flesch-Janys et al., 1995, 197261; Steenland et al.,

2001,197433).

A unique advantage of the Seveso study is that serum measures were taken shortly after
the accident, and therefore characterization of TCDD exposure in this population does not
depend on assumptions needed to back-extrapolate exposures several decades.

2.4.1.1.4.2.	Latency intervals.

Many of the epidemiological studies indicate stronger associations between TCDD and
cancer outcomes once a latency period has been considered. Generally, risks are higher when a
lag period of 15-20 years is included. As noted previously, this observation is consistent with
many other environmental carcinogens such as radon, radiation, and cigarette smoking. That
recent exposures do not contribute to increased cancer risk provides some support that the
initiation and promotion phases might occur many years before death making recent exposures
irrelevant for these analyses. The ability to discriminate between models of varying latency,
however, was limited in many studies. The application of biologically based modeling could
provide additional important insights on which phase(s) of carcinogenesis TCDD exerts an
influence. Such modeling, however, would necessitate having data on an individual-level basis.
Ideally, this modeling would use cancer incident data rather than mortality outcomes, given that
for many cancers, the median survival time exceeds 5 years.

2.4.1.1.4.3.	Use of the SMR metric.

The occupational cohorts and the studies in Seveso and Chapaevsk have made inferences
regarding the effects of TCDD on mortality using the SMR. When compared to the general
population, the healthy worker effect may result in a downward bias in the SMR. This often can
manifest as SMRs less than 1 for several causes of mortality. The effect of this bias is, however,
generally lower for cancer outcomes. Cancer outcomes, whether incidence or death, typically
occur later in life and do not generally affect an individual's ability to work at earlier ages.

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There are several approaches that can be taken to minimize potential biases introduced by
the healthy worker effect, which would account for workers being healthier than the general
population. Comparisons of mortality (or cancer incidence) can be made to other cohorts of
similar workers. If done properly, this can allow for some control of characteristics such as
sociodemographic characteristics and smoking as the two populations can be matched by these
factors. However, it may be the case that other working populations are exposed to other
harmful exposures, thereby making it difficult to estimate risk associated with a specific agent
(such as TCDD) in the cohort of interest. A second and preferred approach to control for the
healthy worker effect, should it prove feasible, is to conduct comparisons of health outcomes in
relation to exposure within the cohort. These comparisons are less likely to be influenced by
other potential confounding variables such as smoking, socioeconomic status, and other
occupational exposures that are generally more homogeneous within the cohort relative to
external populations. Moreover, the mechanisms used to identify health outcomes and follow
individuals over time are generally applied in the same manner to all cohort members. Taken
together, where different comparisons have been made to generate risk estimates, those that have
been conducted using internal cohort comparisons are preferable.

In addition to potential bias from the health worker effect, the comparison of SMRs
between studies is not always straightforward and is not recommended by some (Myers and
Thompson, 1998, 594395; Rothman, 1986, 046091). The SMR is the ratio of the observed
number of deaths to the expected number of deaths and is often referred to as the method of
indirect standardization. The expected number of deaths is estimated by multiplying the number
of person-years tabulated across individuals in the cohort, stratified by age, by rates from a
reference population that are available for the same strata. Therefore, each population cohort
will have an estimated number of cases derived using a different underlying age structure. As
outlined by Rothman (1986, 046091). the mortality rates might not be directly comparable to
each other, although the impact of such bias will be much less if the age-distribution of the
cohorts is similar. While it might be reasoned that the TCDD exposed workers would have
similar age distributions this is in fact not the case (Becher et al., 1998, 197173; Ott et al., 1993,
594322; Thiess et al., 1982, 064999). This may be due to exposure occurring both chronically,
as well as from acute exposures due to accidental releases that happened at various times at
different plants. This is evident with the Hamburg and the BASF cohorts, as most individuals

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comprising the BASF cohort were employed at the time of the accident (1953/1954), while most
of the Hamburg cohort (852/1048) was employed after 1954; the follow-up of these cohorts
ended at approximately the same time.

The method of direct standardization allows for a more meaningful comparison of
mortality rates to be made between cohorts. With this approach, weights (usually based on age
and sex) are drawn from a standard population and are, in turn, applied to disease rates for the
same strata observed in the cohort of interest. A comparison of weighted rates between different
cohorts would then be based on the same population standard.

Despite these limitations in comparing SMRs between studies, Armstrong (1995,

594397) argues that the comparisons are valid if the underlying stratum specific rates in each
exposure grouping are in constant proportion to external rates. Comparisons of the SMRs
between studies will be biased only if there is an interaction between age and TCDD (i.e., the RR
of disease due to exposure differs by age). For cancer outcomes, the finding that associations
become stronger after a period of latency is incorporated into the analyses suggests that this
assumption does not hold true. That is, risk estimates would be lower among young workers.
Similarly, for noncancer outcomes, some of the data from the Seveso cohort suggests differential
effects according to the age at exposure.

The use of the SMR might also be biased in that workers exposed to TCDD could be
subject to more intensive follow-up than the general population, and as a result, differential
coding biases with cause of death might occur. Moreover, some cohorts (e.g., the BASF cohort)
have been assembled, in part, by actively seeking out survivors exposed to accidental releases of
dioxins. As such, they would not include persons who have died or who were lost to follow-up.
This would result in underascertainment of deaths and SMRs developed from these data. The
use of an internal cohort comparison offers distinct advantages to overcome potential sources of
selection bias. Given these uncertainty about comparability across the different studies,
conducting a meta-analysis of cancer outcomes for TCDD using the SMR statistic is not
warranted for this analysis.

2.4.1.1.4.4. AH cancers versus site-specific.

An important consideration for quantitative dose-response modeling is the application of
models for all cancers combined, or for site-specific cancers. Consistency is often lacking for

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site-specific cancers, which might be due in large part to the relatively small number of cases
identified for site-specific cancers in the cohorts. Although the risk estimates produced for all
cancer sites have important limitations and uncertainties, the data are far more consistent in
terms of the magnitude of an association and latency intervals. The IARC evaluation has put
forth the possibility of a pleuripotential mode of action between TCDD and the occurrence of
cancer. Despite the criticism of this assertion by some (Cole et al., 2003, 197626). the general
consistency of an increased risk for all-cancer mortality across the occupational cohorts when
latency intervals have been incorporated, provides adequate justification for dose-response
quantification of all cancer sites combined.

2.4.1.1.4.5. Summary of epidemiologic cancer study evaluations for dose-response
modeling.

All epidemiologic cancer studies summarized above were evaluated for suitability of
quantitative dose-response assessment using the TCDD-specific considerations and study
inclusion criteria. The results of this evaluation are summarized in a matrix style array (see
Table 2-2) at the end of this section, and descriptively in Appendix B. Table 2-4 summarizes the
key epidemiologic cancer studies suitable for further TCDD dose-response analyses.

2.4.1.2. Noncancer

In this section, the available epidemiological data that could be used in a dose-response
analysis for noncancer endpoints are evaluated. Because many of the key studies also evaluated
cancer outcomes, the noncancer studies are presented in the same order as presented in
Section 2.4.1.1. Generally, the strengths and limitations of the cancer studies also apply to the
noncancer outcomes. In this section, key features of these studies that have direct relevance to
modeling of noncancer outcomes in particular are highlighted. To reduce redundancy, a detailed
overview of many of these cohorts and studies are not provided here. Instead, the reader should
refer to Section 2.4.1.1.1.

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2.4.1.2.1. Noncancer cohorts.

2.4.1.2.1.1. The NIOSH cohort.

2.4.1.2.1.1.1. Steenland et al. (1999, 197437).

2.4.1.2.1.1.1.1.	Study summary.

The 1999 published report of NIOSH workers exposed to TCDD also conducted external
cohort comparisons to the U.S. general population using SMRs for mortality outcomes other than
cancer (Steenland et al., 1999, 197437). Analyses are based on 3,538 workers employed at
8 plants from 1942 to 1984. SMRs were based on a mortality follow-up that was extended until
the end of 1993. Cox regression analyses were used to compare mortality risk in relation to
TCDD exposure within the cohort.

2.4.1.2.1.1.1.2.	Study evaluation.

Overall, no statistically significant differences in all-cause mortality (SMR = 1.03,
95% CI = 0.97-1.08) were observed. Mortality from ischemic heart disease (SMR = 1.09,
95% CI = 1.00-1.20) and accidents (SMR= 1.25, 95% CI = 1.03-1.50) was slightly elevated.
Based on the external comparison population, the dose-response relationship for ischemic heart
disease observed with the SMRs calculated across TCDD exposure septiles was not statistically
significant (p = 0.14). Overall, excess risk was not evident for diabetes, cerebrovascular disease,
or nonmalignant respiratory disease using the external population comparisons. Internal cohort
comparisons using the Cox regression model were performed using 0 and 15-year lag intervals.
A dose-response trend was observed for the derived ratios across the untagged cumulative
TCDD exposure septiles for ischemic heart disease (p = 0.05) and diabetes (p = 0.02). For
ischemic heart disease mortality, those in the upper two septiles had rate ratios of 1.57
(95% CI = 0.96-2.56) and 1.75 (95% CI = 1.07-2.87), respectively, relative to those in the
lowest septile. In contrast, an inverse dose-response relationship was observed for diabetes
mortality. The inverse association found for diabetes is inconsistent with the positive association
reported in the Ranch Hands study (Michalek and Pavuk, 2008, 199573). However, previous
reports have questioned the use of death certificates as the means to ascertain outcome as
diabetes may be under-reported especially among descendents with diabetes who die from cancer
(McEwen and TRIAD, 2006, 594400).

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2.4.1.2.1.1.1.3. Suitability of data for TCDD dose-response modeling.

The inverse association with diabetes precludes dose-response analysis for this outcome.
The dose-response relationship between TCDD exposure and ischemic heart disease mortality
was not statistically significant at the alpha level of 0.05 and was not observed in other cohorts.
Furthermore, fatal outcomes are not a suitable basis for development of an RfD. For these
reasons, dose-response analysis for this outcome is precluded.

2.4.1.2.1.1.2. Collins et al. (2009, 197627V
2.4.1.2.1.1.2.1. Study summary.

Collins et al. (2009, 197627) recently described the mortality experience of Dow
employees who worked in Midland, Michigan. This plant produced 2,4,5-trichlorophenol
between 1942 and 1979, and 2,4,5-T between 1948 and 1982. The cohort consisted of
1,615 workers exposed to TCDD from as early as 1942; the follow-up of the cohort extended
until 2003.

TCDD exposures were derived using serum samples obtained from 280 surviving
individuals. A simple one-compartment, first-order pharmacokinetic model was used to estimate
time-dependent TCDD measures. The area under the curve approach was then applied to
estimate cumulative TCDD exposure above background. A half-life of 7.2 years for TCDD
based on earlier work was incorporated into the exposure estimation (Flesch-Janys et al., 1996,
197351).

Collins et al. (2009, 197627) made an external comparison of the mortality rates of the
cohort to the U.S. general population using the SMR statistic. Noncancer causes of death
included all causes, diabetes, cerebrovascular disease, nonmalignant respiratory disease, cirrhosis
of the liver, and accidents. Overall, no statistically significant difference in all-cause mortality of
these workers was detected when compared to the general population (SMR = 0.9,
95% CI = 0.9-1.0). Except for cirrhosis of the liver (SMR = 0.4, 95% CI = 0.1-0.8), no
differences were found for any of the noncancer causes of death relative to the general
population.

Internal cohort analyses based on cumulative measures of TCDD were conducted for
mortality from diabetes, ischemic heart disease, and nonmalignant respiratory disease using the
Cox regression model. These models adjusted for possible confounders such as year of hire and

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birth year. No statistically significant association was found between continuous measure of
TCDD and these causes of death.

2.4.1.2.1.1.2.2.	Study evaluation.

Given that the external comparisons may result in bias from the healthy worker effect,
results from the internal cohort comparisons using the Cox regression model are preferred.

These analyses were performed for diabetes, ischemic heart disease, and nonmalignant
respiratory disease. TCDD levels for these workers were estimated using a simple
one-compartment pharmacokinetic model (Ay 1 ward et al., 2007, 197175). The hazard ratios
generated from the Cox regression model were not statistically significant for any of the
three noncancer outcomes modeled.

2.4.1.2.1.1.2.3.	Suitability of data for TCDD dose-response modeling.

No association of an increased risk for an adverse effect was observed with any of the
noncancer outcomes. In addition, since noncancer mortality was the endpoint being examined,
dose-response modeling based on this population was not conducted.

2.4.1.2.1.2. The BASF cohort

2.4.1.2.1.2.1. Ott and Zober (1996, 198101V
2.4.1.2.1.2.1.1. Study summary.

In 1996, Ott and Zober published a report on the mortality experience of the cohort of
243 BASF male workers who were accidentally exposed to 2,3,7,8-TCDD in 1954 or in the clean
up that followed. The mortality follow-up of this cohort extended until the end of 1992.

External comparisons of mortality were made to the German population using the SMR statistic.
Internal cohort comparisons were also made by estimating cumulative TCDD for the cohort
using serum measures that were obtained from 138 workers. Ott et al. (1993, 594322) provided
a detailed account of the methodology to estimate TCDD. Briefly, a cumulative measure of
TCDD expressed in |ig/kg was derived, by first estimating the half-life of TCDD using
individuals who had repeated serum measures; the half-life was estimated to be 5.8 years.
Individual-level data on body fat were used to account for the influence of body fat on decay
rates. Half-life estimates of TCDD varied (range: 5.1-8.9 years) and were dependent on body fat

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composition (20% and 30%, respectively). This approach differed from previous analysis of this
cohort that used a constant 7-year half-life (Ott et al., 1993, 594322). TCDD levels at the time of
serum sampling were then estimated as the product of TCDD concentration in blood lipid and
the total lipid weight for each worker. Nonlinear models then were applied to estimate the
contribution of duration of exposure to TCDD dose extrapolated to the time of exposure.

External comparisons to the German population using the SMR statistic also were
examined across dose categories. The noncancer causes of death examined by Ott and Zober
(1996, 198101) included all-cause mortality, diseases of the circulatory system, ischemic heart
disease, diseases of the digestive system, external causes, suicide, and residual causes of death.
Overall, no statistically significant differences in the SMR with the general population for
all-causes of death (SMR = 0.9, 95% CI = 0.7-1.1) were found. No statistically significant
differences were noted for any of the other causes of death examined.

Ott and Zober (1996, 198101) performed internal cohort comparisons using the Cox
regression model. These analyses found no dose-response patterns when cause-specific
mortality was examined across increasing cumulative TCDD exposure categories. Although an
inverse association for diseases of the respiratory system (SMR =0.1, 95% CI = 0.0-0.8) was
detected, it was based only on 1 reported case. Many of these comparisons are limited by small
sample sizes as 92 deaths occurred in the cohort, and of these, 31 were from cancer. Also, the
third component of the cohort was identified primarily from former employees who were alive in
1986. As a result, the SMR based on the general population might be underestimated by the
exclusion of deceased workers.

2.4.1.2.1.2.1.2. Study evaluation.

As noted previously, caution should be exercised in the interpretation of SMR values of
noncancer outcomes as they could be influenced by the healthy worker effect. Although the
mechanism of identifying vital status appears to be excellent and unbiased, SMRs might be
underestimated for the cohort due to the manner in which they were constructed. Specifically, a
large component of the cohort was assembled by actively seeking out former workers who were
known to be alive in 1986.

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2.4.1.2.1.2.1.3. Suitability of data for TCDD dose-response modeling.

No dose-response patterns were observed between TCDD and the noncancer outcomes in
the Ott and Zober (1996, 198101) study. Therefore, dose-response modeling was not conducted.

2.4.1.2.1.3. The Hamburg cohort

2.4.1.2.1.3.1. Flesch-Janys et al. (1995, 1972611

2.4.1.2.1.3.1.1.	Study summary.

Flesch-Janys et al. (1995, 197261) reported on the mortality experience of a cohort of
individuals employed by an herbicide-producing plant in Hamburg, Germany, covering the
period 1952 to 1992. As described in more detail in Section 2.4.1.1.1.3, the authors developed a
cumulative measure of TCDD using serum measures from 190 workers. This study also
examined the relationship between total TEQ and mortality. In the study population, the mean
TEQ without TCDD was 155 ng/kg, and for the mean TEQ including TCDD was 296.5 ng/kg.

Risks relative to the unexposed referent group of gas workers were estimated using Cox
regression across six exposed TCDD groups (i.e., the first four quintiles, and the ninth and
tenth deciles). A linear dose-response relationship was found with all causes of mortality and
cardiovascular mortality (p < 0.01). The RR for all cardiovascular deaths in the upper exposure
category was 1.96 (95% CI = 1.15-3.34), although there was no evidence of a linear
dose-response trend (p = 0.27). The dose-response relationship was most marked for ischemic
heart disease, with a RR of 2.48 (95% CI = 1.32-4.66) in the highest exposure group. A
dose-response relationship was also observed across TEQ groupings for all cause mortality,
cardiovascular disease mortality, and ischemic heart disease mortality. The authors did not
perform joint modeling of TEQ (without TCDD) and TCDD, so determining the extent that
dioxin-like compounds contributed to an increased risk of mortality is not possible.

2.4.1.2.1.3.1.2.	Study evaluation.

The Flesch-Janys et al. (1995, 197261) study lacks information on other potential risk
factors for cardiovascular disease, which could result in confounding if those risk factors are also
related to TCDD exposure. Dose-response patterns were strong, however, and persisted across
numerous TCDD (and TEQ) exposure categories based on the use of an external reference group
(i.e., gas workers) or based on the internal comparison. The findings based on the internal

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comparison are noteworthy in that these groups should be more homogenous with respect to
confounding factors. As noted previously, the poor correlation between TCDD and smoking
among workers and similar smoking prevalence between the workers and the external gas
company workers suggest that smoking was not likely a confounder of the TCDD and
cardiovascular disease relationship. No other evaluation of noncancer mortality outcomes has
been undertaken in this cohort since 1995.

A strength of the Flesch-Janys et al. (1995, 19726:0 study was that it included the
collection of blood serum measures, which provided an objective measure of TCDD exposure.
Blood serum data, however, were obtained only for 16% of the cohort. The assumption of the
first-order kinetic elimination model is critical, given that measures were taken at the end of
follow-up. The model also assumed the half-life of TCDD was 6.9 years. If the kinetics are not
first order, or if the half-life estimate is inaccurate, estimates of TCDD levels during exposure
would be biased, particularly for workers having longer periods between exposure and PCDD
and PCDF assays. Sensitivity analyses completed by the authors suggest that such bias is not
likely to present because the results were unaffected when different model assumptions regarding
kinetic and half-lives were examined. The lack of an impact on RR estimates with varying
half-life estimates was similar to findings by Steenland et al. (2001, 197433).

2.4.1.2.1.3.1.3. Suitability of data for TCDD dose-response modeling.

Despite the aforementioned study strengths, the study focused on fatal outcomes such as
all cause mortality, cardiovascular disease mortality, and ischemic heart disease mortality. As
such, dose-response analysis was not conducted since these outcomes are not suitable for
development of an RfD.

2.4.1.2.1.4. The Seveso Women's Health Study (SWHS).

Eskenazi et al. (2000, 197lo2) presented an overview of the SWHS. The SWHS is the
first comprehensive epidemiologic study of the reproductive health of a female population
exposed to TCDD. The primary objective of the SWHS is to investigate the relationship of
TCDD and several reproductive endpoints, including endometriosis, menstrual cycle
characteristics, birth outcomes, infertility, and age at menopause. A second phase of follow-up

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that focuses on osteoporosis, thyroid hormone, breast cancer, diabetes, and metabolic syndrome
is expected to be completed in 2010.

Women were eligible for participation in the SWHS if they resided in Zones A and B (the
most contaminated areas) at the time of the explosion, were 40 years of age or younger at the
time of the explosion in 1976, and samples of their blood were collected and stored between
1976 and 1980. The enrollment of women in the SWHS began in March 1996 and continued
until July 1998. Of the 1,271 eligible women, 17 could not be found, 21 had died, and 12 were
too ill to participate. Of the 96% of the remaining women, 80% (n = 981) participated in the
study. Participation in the SWHS included a blood draw and an interview by a trained nurse who
was blind to subjects' TCDD level and zones of residence at the time of the accident. The
interview included detailed information on potential confounders including occupational,
medical, and reproductive, and pregnancy history. Also, women who were premenopausal were
asked to undergo a vaginal ultrasound and pelvic exam and to complete a daily diary on
menstruation.

Depending on the health outcome under study, TCDD exposures were characterized for
the women at different times. For example, TCDD exposure levels were estimated at the time of
the accident for some studies and at the time of conception for others. The SWHS study
population has been used to investigate associations between maternal TCDD levels and the
following health outcomes: menstrual cycle characteristics (Eskenazi et al., 2002, 197168);
endometriosis (Eskenazi et al., 2002, _ [); birth outcomes (Eskenazi et al., 2003, 197158);
age at menarche (Warner et al., 2004, 197490); age at menopause (Eskenazi et al., 2005,

197166); uterine leiomyomas (Eskenazi et al., 2007, 197170); and ovarian function (Warner
et al., 2007, 197486). An evaluation of the studies in chronological order is presented in this
section.

2.4.1.2.1.4.1. Eskenazi et al. (2002, 197168)—Menstrual cycle characteristics.

2.4.1.2.1.4.1.1. Study summary.

Eskenazi et al. (2002, ^ ) evaluated serum TCDD exposures in relation to several
menstrual cycle characteristics in the SWHS. A total of 981 women who were 40 years of age or
younger at the time of the accident comprised the SWHS. The following exclusion criteria was
applied 44 years of age or older, women with surgical or natural menopause, those with Turner's

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syndrome, and those who in the past year had been pregnant, breastfed, or used an intrauterine
device or oral contraceptives.

A trained interviewer collected data on menstrual cycle characteristics using a
questionnaire. Women were asked to indicate how long their cycles were, whether the cycles
were regular (e.g., irregular cycle defined as length varied by more than 4 days), how many days
the menstrual flow lasted, and whether this flow was "scanty, moderate, or heavy." Information
was also collected on obstetric and gynecological conditions. TCDD exposures were derived
from serum samples collected in 1976-1985. The authors selected the earliest available serum
sample, and back-extrapolated to 1976 values using either the Filser model (Kreuzer et al., 1997,
198088) for women aged 16 years or younger in 1976 (n = 20) or the first-order kinetic model
(n = 6) (Pirkle et al., 1989, 1978611

Serum TCDD levels were transformed using the loglO scale, and the relationships
between these levels and length of menstrual cycle and days of menstrual flow were examined
using linear regression. The authors applied logistic regression to characterize the risk between
logioTCDD and heaviness of flow or regularity of cycle. In these analyses, moderate or heavy
flow and regular cycle were used as the reference categories. Stratified analysis was performed
by menarcheal status at the time of the accident.

Overall, the association with TCDD exposure (per 10-fold increase) and length of
menstrual cycle was not statistically significant for premenarcheal (P = 0.93, 95% CI = -0.01,
1.86) women or postmenarcheal women (P = -0.03, 95% CI = -0.61, 0.54). The corresponding
estimates found for days of menstrual flow were P = 0.18 (95% CI = -0.15, 0.51) and P = 0.16
(95%) CI = -0.18, 0.50), respectively. Reduced flow was not associated with TCDD when
compared to moderate or heavy flow (odds ratio [OR] = 0.84, 95% CI = 0.44, 1.61); effect
modification by menarcheal status, however, was evident (p = 0.03). Specifically, women
exposed to TCDD who were premenarcheal had lower odds of reduced flow, while those
exposed to TCDD who were postmenarcheal did not. These findings counter the hypothesis that
TCDD exposure is related to ovarian dysfunction. Finally, statistically significant ORs were
found between serum TCDD levels (per 10-fold increase) and having an irregular cycle
(OR = 0.46, 95%) CI = 0.23, 0.95). This inverse association was evident in both premenarcheal
women (OR = 0.50, 95% CI = 0.18, 1.38) and postmenarcheal women (OR = 0.41,
95% CI = 0.15, 1.16).

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2.4.1.2.1.4.1.2.	Study evaluation.

Overall, the findings from the Eskenazi et al. (2002, 8) study suggest that
exposures to TCDD can affect menstrual cycle characteristics among women who were exposed
before menarche. Exposures to TCDD were well characterized using serum samples available
on an individual-level basis, and the design allowed for the influence of other risk factor data to
be controlled for in regression analyses. Analysis of TCDD levels and the length of menstrual
cycle in premenarcheal women produced associations that were largely not statistically
significant at the alpha level of 0.05, but may have some biological significance. However, it is
unclear whether the endpoints that were measured constitute adverse health outcomes as they are
not definitive markers of ovarian dysfunction. Another source of uncertainty is measurement
error due to the subjective nature of menstrual flow reporting. Any resulting misclassification of
the outcome should be nondifferential, as the measurement error is unlikely to be dependent on
TCDD exposure.

2.4.1.2.1.4.1.3.	Suitability of data for TCDD dose-response modeling.

The lack of a clear adverse health outcome related to TCDD exposure is a weakness of
this study. Although it is difficult to define the critical window of exposure for quantitative
exposure calculations, it can be estimated for the women that were premenarcheal at the time of
the accident as 13 years. Therefore, this study is suitable for further consideration for
quantitative dose-response modeling.

2.4.1.2.1.4.2. Eskenazi et al. (2002, 197164)—Endometriosis.

2.4.1.2.1.4.2.1. Study summary.

The SWHS provided the opportunity to investigate the association between serum TCDD
levels and endometriosis (Eskenazi et al., 2002, 197164). The rationale the authors provided for
undertaking this study was the experimental animal studies that suggested an association, the
high prevalence of endometriosis among infertile women where breast milk concentrations of
dioxin are high, and the unknown etiology of endometriosis. The study consisted of 601 women
who were younger than 30 years at the time of the Seveso accident. Stored sera that had been
collected between 1976 and 1980 were also available for these women.

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Given that laparoscopy could not be performed on women unless clinically indicated, no
"gold" standard was available for endometriosis diagnosis. Based on the results of a validation
study they conducted in a clinical population, the researchers classified women as having
endometriosis based on symptom report, gynecologic exam results, and vaginal ultrasound.

TCDD was measured in sera in 1976 for 93% of the women. Values for women whose
serum TCDD levels were collected after 1977 and had values exceeding 10 ppt were
back-extrapolated to 1976 using either the Filser model (<16 years of age) (Kreuzer et al., 1997,
198088) or a first-order kinetic model (>16 years) (Pirkle et al., 1989, 197861). These estimates
of TCDD were then modeled as both continuous (on a log scale) and categorical (<20, 20.1-100,
and >100 ppt) exposures.

Polytomous logistic regression was applied within the cohort used to generate RRs. In
relation to women in the lowest exposure category, the RR for endometriosis among women in
the middle and upper categories was 1.2 (90% CI = 0.3-4.5) and 2.1 (90% CI = 0.5-8.0),
respectively. The trend tests were not statistically significant for either the categorical (p = 0.25)
and continuous measures of TCDD (p = 0.84).

2.4.1.2.1.4.2.2.	Study evaluation.

It is important to note that disease misclassification could have led to an underestimate of
the true risk of endometriosis if this misclassification was not differential with respect to TCDD
exposure. Also, younger women were likely to be under-represented as those who had never
been sexually active could not be examined due to cultural reasons. Other dioxin-like
compounds (PCDD, PCDFs, or poly chlorinated biphenyls [PCBs]) were not considered because
of small serum volumes, but any potential TEQ exposures occurring in the population were
thought to be mostly attributable to TCDD in the exposed women.

2.4.1.2.1.4.2.3.	Suitability of data for TCDD dose-response modeling.

Given that no statistically significant dose-response patterns were observed with either
log-transformed or across TCDD exposure categories, and that the elevated risks among those
with higher exposures had very wide confidence intervals (that included unity) quantitative
dose-response analyses were not recommended for this outcome.

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2.4.1.2.1.4.3. Eskenazi et al. (2003, 197158)—Adverse birth outcomes.

2.4.1.2.1.4.3.1. Study summary.

Eskenazi et al. (2003, 197158) examined the relationship between serum TCDD levels
and birth outcome measures. Analyses were based on 745 of the 981 women enrolled in the
SWHS who reported having been pregnant (n = 1,822). Most of these pregnancies
(888 pregnancies among 510 women) occurred after the accident. Analysis of spontaneous
abortions was restricted to 769 pregnancies among 476 women that did not end in abortion or in
ectopic or molar pregnancy. Congenital anomalies were evaluated for the 672 pregnancies that
did not end in spontaneous abortion. For the birth outcomes of fetal growth and gestational age,
analysis was performed using 608 singleton births from women without hypertensive pregnancy
disorders.

TCDD exposures were based on serum measures, most of which were taken shortly after
the accident. Serum was collected in 1976-1977 for 413 women, between 1978 and 1981 for
12 women, and in 1996 for 19 women. TCDD exposures based on serum samples collected from
1977 onward were back-extrapolated to 1976.

Statistical analyses were performed on pregnancies that ended between 1976 and the time
of interview. A continuous measure of logioTCDD (base 10 scale) was used to investigate
associations with adverse birth outcomes. Logistic regression was used to characterize the
relationship between TCDD exposure spontaneous abortions, small for gestational age, and
preterm birth (<37 weeks gestation). Linear regression was used to describe the relationship
between TCDD and birth weight (in grams) and gestational age (in weeks).

The risk estimates were adjusted for a series of characteristics that included sex of infant,
history of low birth weight child, maternal height, maternal body mass index, maternal
education, maternal smoking during pregnancy, and parity. No association was evident between
TCDD serum levels and spontaneous abortion for pregnancies between 1976 and 1998
(OR = 0.8, 95% CI = 0.6-1.2), or those between 1976 and 1984 (OR = 1.0, 95% CI = 0.6-1.6).
No statistically significant associations (ORs ranged from 1.2-1.8) were found between
logio TCDD levels and preterm delivery, small for gestational age. Although the mean change in
birth weight for pregnancies between 1976 and 1984 was fairly large (P = -92, 95% CI = -204
to 19), it also was not statistically significant at the alpha level of 0.05.

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2.4.1.2.1.4.3.2.	Study evaluation.

This study was well-designed with well characterized exposures. Statistically significant
associations were not evident, although the birth-weight findings should be pursued with further
follow-up of the cohort. As the authors point out, those who were most vulnerable at the time of
the accident (the youngest) had not yet completed their childbearing years. While the study
lacked exposure data for the fathers, the authors indicated that only a small proportion were
believed to have high exposures to TCDD. The key limitation of the study was a reliance on
self-reported measures of pregnancy history, which may lead to some misclassification of the
birth outcomes. The observation that a large proportion of Seveso women had a voluntary
abortion because of fears of possible birth defects due to exposures from the accident suggest an
awareness bias is possible as a result of differential reporting of birth outcomes according to
exposure status.

2.4.1.2.1.4.3.3.	Suitability of data for TCDD dose-response modeling.

No statistically significant associations were found in the study; in addition, possible
awareness bias could have influenced the self-reported measures of birth outcomes. Therefore,
quantitative dose-response assessment was not considered for this study.

2.4.1.2.1.4.4. Warner et al. (2004, 197490)—Age at menarche.

2.4.1.2.1.4.4.1. Study summary.

Warner et al. (2004, 197490) examined the relationship between TCDD and age at
menarche in the SWHS cohort. As described earlier in this report, the SWHS comprised
981 participants. This study was restricted only to those who were premenarcheal at the time of
the accident (n = 282). The proportional hazards model was used to model TCDD exposures and
age at menarche. Age at menarche was determined by questionnaire administered by a trained
interviewer. Covariates examined as potential confounders included height, weight, body mass
index, athletic training at the time of interview, smoking, and alcohol consumption.

TCDD exposures were determined using serum samples collected from 257 of these
women between 1976 and 1977. For the remaining women, TCDD levels were quantified from
measures collected between 1978 and 1981 (n = 23) and in 1996 (n = 2). TCDD levels were
back-extrapolated to the time of the explosion in 1976. TCDD was modeled as both a

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continuous variable (logioTCDD) and a categorical variable based on quartile values (<55.9,
56-140.2, 140.3-300, >300 ppt). The lowest group was further subdivided into those with levels
<20, and >20 ppt; this cut-point represented background levels found in a sample of women
living in an unexposed area.

No association was found between the continuous measure of TCDD and age at
menarche (hazard ratio [HR] = 0.95, 95% CI = 0.83-1.09). Analyses restricted to those who
were younger than 8 in 1976 produced similar results (HR = 1.08, 95% CI = 0.89-1.30).
Additionally, no dose-response trend was observed with categorical measures of TCDD among
all women, as well as those under the age of 8. Although not statistically significant at the alpha
level of 0.05, TCDD exposures were later reported to be associated with age of menarche
(HR = 1.20, 95% CI = 0.98-1.60) when analyses were restricted to 84 women under the age of 5
at the time of the accident (Warner and Eskenazi, 2005).

2.4.1.2.1.4.4.2.	Study evaluation.

An important strength of the Warner et al. (2004, 197490) study is the ability to
characterize TCDD exposures using serum samples that were collected shortly after the accident
occurred. The outcome of interest, age at menarche, was determined by asking women "At what
age did you get your first menstrual period?" Recent work suggests that self-reported measures
of age at menarche decades later have modest agreement with responses provided during
adolescence with recall varying by education and by history of an adverse birth outcome (Cooper
et al., 2005, 594401). In the Seveso study, bias would be introduced if recall varied according to
exposure levels.

2.4.1.2.1.4.4.3.	Suitability of data for TCDD dose-response modeling.

Although the TCDD exposure characterization of study subjects was based on serum
data, and no major biases were introduced from the study design, the analyses produced largely
null associations. Therefore, quantitative dose-response assessment was not considered for this
study.

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2.4.1.2.1.4.5. Eskenazi et al. (2005, 197166)—Age at menopause.

2.4.1.2.1.4.5.1. Study summary.

Eskenazi et al. (2005, 197166) evaluated the relationship between age at onset of
menopause and serum levels of TCDD among women in the SWHS. Of the 981 women who
agreed to participate in SWHS, this analysis was restricted to those who had not reached natural
menopause before the time of the accident and who were at least 35 years of age at the time of
the interview. The recruitment and interview of women occurred approximately 20 to 22 years
after the accident (March 1996-July 1998).

The population was divided into quintiles of serum TCDD levels for the categorical
analysis. For most women (n = 564), TCDD levels were estimated from samples provided in
1976-1977. For the remaining women included in these analyses, TCDD levels were estimated
from samples collected between 1978 and 1982 (n = 28) and between 1996 and 1997 (n = 24).
As noted previously, exposure levels for women with post-1977 detectable levels of TCDD were
back-extrapolated to 1976 using either the first-order kinetic model (Pirkle et al., 1989, 197861)
(>16 years at time of accident) or the Filser model (<16 years at time of accident) (Kreuzer et al.,
1997, 198088). Women were classified as premenopausal if they were still menstruating or if
they had amenorrhea as a result of pregnancy or lactation (at the time of interview) with an
indication of subsequent menstruation based on maintained diaries or further examination.
Subjects for which amenorrhea had persisted for at least 1 year with no apparent medical
explanation were classified into a natural menopause category. The category, surgical
menopause, pertained to women with a medically confirmed hysterectomy or an oophorectomy.
Finally, impending menopause was defined for subjects in which menstruation had been absent
for 2 months, but who provided evidence of subsequent menstruation, or had a secretory
endometrial lining, or indicated less predictable cycles in the previous 2-5 years. If participants'
menopausal status could not be determined, they were grouped into the "other" category. This
category included those for whom status could not be determined due to current use of oral
contraceptives, hormone replacement therapy, or previous cancer chemotherapy.

Statistical analysis was based on both a continuous measure of log-transformed TCDD
exposures and categories based on quintiles (<20.4 ppt; 20.4-34.2 ppt; 34.3-54.1 ppt;

54.2-118.0 ppt; >118.0 ppt). The Cox model was used to generate hazard ratios as estimates of
relative risks and their 95% confidence intervals examining natural menopause as the outcome.

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Several covariates previously identified as associated with menopausal status in the literature
were considered as potential confounders. These covariates included body mass index, physical
activity, premenopausal smoking, education, marital status, history of heart disease and other
medical conditions, and other reproductive characteristics.

The RRs were found to increase across the second through fourth quintiles (RRs =1.1,
1.4, and 1.6, respectively) of serum TCDD categories in relation to those in the lowest category,
but not in the upper quintile (RR = 1.0, 95% CI = 0.6-1.8). A statistically significant test of
trend was detected across the first four quartiles (p = 0.04) but not across all five quintiles
(p = 0.44). A statistically significant association with onset of menopause was not detected
(RR = 1.02, 95% CI = 0.8-1.3) based on the logTCDD continuous measure.

2.4.1.2.1.4.5.2.	Study evaluation.

The categorical exposure results from this study support a nonmonotonic
dose-related-association for earlier menopause with increased serum TCDD levels up to
approximately 100-ppt TCDD serum, but not above. Eskenazi et al. (2005, 197166s) speculated
that the inverse "U" shape of the dose-response relationship is explained by the mimicking of
hormones at lower doses of a chemical, while at higher levels the toxic effect of a chemical does
not have the capacity to either inhibit or stimulate hormonal effects.

A study limitation is the potential for residual confounding due to adjustment based on
current smoking status and not at the time of onset of menopause. It is unclear to what extent
smoking status may differ between these two time periods and whether smoking is related to
TCDD exposures in this cohort. Exposures to other dioxin-like compounds were not considered
in this study because of small serum volumes, but any potential TEQ exposures occurring in the
exposed population were thought to be mostly attributable to TCDD in the exposed women.

2.4.1.2.1.4.5.3.	Suitability of data for TCDD dose-response modeling.

To date, this study is the only one that has examined the relationship between TCDD
levels and onset of menopause. Although the findings suggest the possibility of a nonlinear
dose-response function, the logioTCDD exposure metric was not statistically significant, nor
were any category-specific hazard ratios statistically significant relative to the lowest category.
Therefore, a quantitative dose-response analysis was not undertaken.

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2.4.1.2.1.4.6. Warner et al. (2007, 197486)—Ovarian function.

2.4.1.2.1.4.6.1.	Study summary.

Warner et al. (2007, 197486) investigated the association between serum TCDD levels
and ovarian function in subjects in the SWHS who were younger than 40 in 1976 and for whom
sera collected after the accident had been stored. These women were recruited from March 1996
until July 1998. Ovarian function analysis was limited to 363 women between 20 and 40 years
of age and who were not using oral contraceptives. Of these, 310 underwent transvaginal
ultrasound and were included in the functional ovarian cyst analysis. Ninety-six women were in
the preovulatory stage of their menstrual cycles and were included in the follicle analysis. For
the hormone analysis, 126 women who were in the last 2 weeks of their cycle were included.

The authors used logistic regression to examine the relationship between TCDD and the
prevalence of ovarian follicles greater than 10 mm. Linear regression models examined the
continuous outcome variables: number of ovarian follicles >10 mm and diameter of dominant
ovarian follicle. Covariates considered for inclusion in the model were age at ultrasound, age at
accident, age at menarche, marital status, parity, gravidity, lactation history, current body mass
index, age at last birth, and smoking history. For the serum hormone analyses, estradiol and
progesterone were measured in blood at the time of interview. Ovulation status was defined as a
dichotomous variable (yes/no) based on a serum progesterone cut-point value of 3 ng/mL.

The adjusted ORs across categories of TCDD exhibited no dose-response trend for the
presence of follicles in relation to TCDD in the follicular phase; also, no statistically significant
differences were noted in any of the upper exposure categories relative to those in the lowest.
The adjusted OR for the continuous measure of logioTCDD was 0.99 (95% CI = 0.4-2.2). A
similar nonstatistically significant finding was found for logioTCDD in relation to ovulation in
both the luteal (OR = 0.99, 95% CI = 0.5-1.9) and mid-luteal phases (OR = 1.03,
95%) CI = 0.4-2.7). Analyses of progesterone and estradiol also were not related to serum
TCDD levels for either the luteal or mid-luteal phases (p = 0.51 andp = 0.47).

2.4.1.2.1.4.6.2.	Study evaluation.

The investigators found no relationship between serum TCDD levels and serum
progesterone and estradiol levels among women who were in the luteal phase at the time of

blood draw. No association with number of ovarian follicles detected from ultrasound.

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Although no association was found, the authors suggested that the lack of significant results
could be because the women in SWHS were all exposed postnatally and the relevant and critical
time period for an effect might be in utero (animal studies support relevance of in utero
exposures).

2.4.1.2.1.4.6.3. Suitability of data for TCDD dose-response modeling.

One limitation of the study was the lack of examination of confounding by dioxin-like
compounds. The absence of associations between TCDD and adverse health effects in this study
precludes conducting quantitative dose-response analyses.

2.4.1.2.1.4.7. Eskenazi et al. (2007, 197170)—Uterine leiomyoma.

2.4.1.2.1.4.7.1. Study summary.

Associations between TCDD exposures and uterine leiomyoma (i.e., fibroids) were also
examined among 956 women in the SWHS (Eskenazi et al., 2007, 197170). The sample
population was based on the on the original 981 SWHS participants excluding 25 women
diagnosed with fibroids before the date of the accident (July 10, 1976). Women who previously
had fibroids were identified both through the administered questionnaire and the review of
medical records. Transvaginal ultrasounds were performed for 634 women to determine if they
had fibroids at the time of follow-up. Similar to other SWHS studies, exposure to TCDD was
estimated using serum collected from women shortly after the time of the accident, between
1978 and 1981 and in 1996. TCDD levels were back-extrapolated to 1976 levels.

The study authors performed statistical analyses using two definitions of fibroids as
outcome measures. The first was fibroids detected before the study, and the second was fibroids
detected via ultrasound. A proportional odds method Dun son and Baird (2001, 197248)
developed was used to model the cumulative odds of onset of fibroids. This method combines
historical and current information of diagnoses of fibroids. Continuous and categorical measures
of TCDD were modeled. Regression models were adjusted for known or suspected risk factors
of fibroids including parity, family history of fibroids, age at menarche, body mass index,
smoking, alcohol use, and education.

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2.4.1.2.1.4.7.2.	Study evaluation.

Categorical measures of TCDD suggested an inverse dose-response relationship with the
onset of fibroids. Relative to those with TCDD levels less than 20 ppt, those having TCDD
exposures between 20.1 and 75.0 ppt and greater than 75.0 ppt had RRs of 0.58
(95% CI = 0.41-0.81), and 0.62 (95% CI = 0.44-0.89), respectively. The continuous measure of
logioTCDD produced a hazard ratio of 0.83 (95% CI = 0.65-1.07).

2.4.1.2.1.4.7.3.	Suitability of data for TCDD dose-response modeling.

The inverse association between TCDD and uterine fibroids supports the possibility of an
anti-estrogenic effect of TCDD. The observed direction of the reported associations precludes
quantitative dose-response modeling.

2.4.1.2.1.5. Other Seveso noncancer studies.

2.4.1.2.1.5.1. Bertazzi et al. (1989, 197013); Consonni et al. (2008, 524825)—Mortality
outcomes.

2.4.1.2.1.5.1.1. Study summary.

Several studies have evaluated the mortality of Seveso residents exposed to TCDD
following the 1976 accident. The earlier section of this report described the designs of these
studies and discussed their findings as they relate to cancer mortality. In this section, some of
the findings for other causes of death are described. A key feature of these studies is that
patterns of mortality among Seveso residents were investigated according to their zone of
residence at the time of explosion relative to general population rates.

A 10-year mortality follow-up of residents of Seveso was published in 1989 (Bertazzi
et al., 1989, 197013). Poisson regression was used to derive RRs for those who had lived in
Zone A at the time of explosion using a referent group consisting of inhabitants who had lived in
the uncontaminated study area. Between 1976 and 1986, no statistically significant difference
was observed in all-cause mortality relative to the general population among those who lived in
the most highly exposed area (Zone A) at the time of the accident. This finding was evident in
both males (RR = 0.86, 95% CI = 0.5-1.4) and females (RR =1.14, 95% CI = 0.6-2.1). A
statistically significant excess in circulatory disease mortality was found among males relative to
those in the referent population (RR = 1.75, 95% CI = 1.0-3.2); this increased risk was more

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pronounced when the follow-up period was restricted to the first 5 years after the accident
(1976-1981) (RR = 2.04, 95% CI = 1.04-4.2). Between 1982 and 1986, the RR decreased
substantially and was not statistically significant (RR = 1.19, 95% CI = 0.4-3.5). Among
females, a risk similar in magnitude was detected for circulatory disease mortality although it
was not statistically significant (RR = 1.89, 95% CI = 0.8-4.2). Contrary to the calendar
period-specific findings for males, the excess of circulatory mortality among females occurred
between 1982 and 1986 (RR = 2.91, 95% CI = 1.1-7.8) and not between 1976 and 1981
(RR = 1.12, 95% CI = 0.3-4.5). The number of deaths in this cohort with the 10 years of
follow-up was relatively small; in Zone A, 16 deaths were observed among males and 11 among
females.

The most recently published account of the mortality experience of Seveso residents
provides further information on follow-up of these residents until the end of 2001 (25 years after
the accident) (Consonni et al., 2008, 524825). Three exposure groups were considered: Zone A
(very high contamination), Zone B (high contamination), and Zone R (low contamination). The
reference population consisted of those residents who lived in unaffected surrounding areas, as
well as residents of five nearby towns. The authors used Poisson regression to compare
mortality rates for each zone relative to the reference population.

For all causes of death, no excess was found in Zone A, B, or R relative to the reference
population. Statistically significant excesses were noted for those who lived in Zone A relative
to the reference population for chronic rheumatic heart disease (RR = 5.74,
95% CI = 1.83-17.99) and chronic obstructive pulmonary disease (RR = 2.53,
95% CI = 1.20-5.32). These risks, however, were based on only 3 and 7 deaths, respectively.
For those in Zone A, no statistically significant excesses in mortality were noted for diabetes,
accidents, digestive diseases, ischemic heart disease, or stroke. Among Zone A residents,
stratified analysis by time since accident showed increased rates of circulatory disease 5-9 years
since the accident (RR = 1.84, 95% CI = 1.09-3.12). Increased mortality from diabetes relative
to the reference population was noted among females who lived in Zone B (RR = 1.78,
95% CI = 1.14-2.77).

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2.4.1.2.1.5.1.2.	Study evaluation.

The ascertainment of mortality in this cohort is nearly complete. Misclassification of
some health outcomes, such as diabetes, may occur due to use of death certificate data.

The characterization of exposure is based on zone of residence. Soil sampling indicated
considerable variability in TCDD soil levels, and therefore, the generation of risks based on zone
of residence likely does not accurately reflect individual exposure. Exposure misclassification
might also occur because residency in the areas does not necessarily reflect whether the
individual would have been present in the area at the time the accident occurred. Any exposure
misclassification would likely be nondifferential which would tend to bias the risk estimates
towards the null.

Although some excess of circulatory disease mortality was found, the finding was not
consistent between men and women. Moreover, excess circulatory disease mortality was more
pronounced among men within the first 5 years of exposure, while, for women, the excess was
more pronounced in years 5-10. Numerous other risk factors for circulatory disease were not
controlled for in these analyses and may be confounders if related to TCDD exposure. Taken
together, the possibility that TCDD increased circulatory disease mortality based on these data is
tenuous at best.

2.4.1.2.1.5.1.3.	Suitability of data for TCDD dose-response modeling.

There is considerable uncertainty in these data due to the potential for outcome and
exposure misclassification. The lack of the individual-level TCDD levels and the examination of
fatal outcomes reported in this study are not a suitable basis for development of an RfD. For
these reasons, dose-response analysis for this outcome is not conducted.

2.4.1.2.1.5.2. Mocarelli et al. (1996, 197637; 2000,197448)—Sex ratio.

2.4.1.2.1.5.2.1. Study summary.

A letter to the editor was the first report of a possible change in the sex ratio from dioxin
among Seveso residents following the July 10, 1976 accident (Mocarelli et al., 1996, 197637).
The authors reported that 65% (n = 48) of the 74 total births that had occurred from April 1977
to December 1984 were females. This male to female ratio of 26:48 (35%) is significantly
different from the worldwide birth ratio of 106 males to 100 females (51%) (James, 1995,

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197722). Between 1985 and 1994, the Seveso male to female ratio leveled out at 60:64 (48%).
The authors suggested that the finding supported the hypothesis that dioxin might alter the sex
ratio through several possible mechanistic pathways.

Mocarelli et al. (2000, 197448) later reported on an investigation between serum-based
TCDD measures in parents and the sex ratio of offspring. In this study, serum samples were
collected from mothers and fathers who lived in the areas at the time of the explosion, were
between the ages of 3 and 45 at the time of the explosion, and produced offspring between
April 1, 1977 and December 31, 1996. The study population included 452 families and
674 offspring, and serum measures were available for 296 mothers and 239 fathers. An estimate
of TCDD at the time of conception was also examined in relation to male to female birth ratios.
TCDD exposure estimates between the years of 1976 and 1996 were estimated using Filser's
model (Kreuzer et al., 1997, 198088).

Mocarelli et al. (2000, 197448) used chi-square test statistics to compare observed sex
ratio to an expected value of 0.51 in this Seveso population. Concentrations of TCDD were
modeled as categorical variables in several ways. First, a dichotomous variable was used
whereby unexposed parents were defined as those who lived outside Zones A, B, and R or had a
serum TCDD concentration of less than 15 ppt; parents with exposures of 15 ppt or higher were
considered exposed. Second, a trichotomous exposure variable was created that consisted of
parents who (1) lived outside Zones A, B, and R or had serum concentrations of less than 15 ppt,
(2) had serum concentrations of 15-80 ppt, and (3) had serum concentrations that exceeded
80 ppt. These cut-points were chosen as they represented tertiles based on the distribution of
TCDD among parents. Analyses were conducted separately for paternal and maternal TCDD
levels.

The overall proportion of 0.49 male births (based on male to female ratio of 328:346) was
not significantly different from the expected proportion of 0.51 (p> 0.05). Statistically
significant differences were found, however, if both parents had TCDD levels >15 ppt (sex
ratio = 0.44) or just the father had serum TCDD levels >15 ppt (sex ratio = 0.44). No
statistically significant differences were found when the fathers had TCDD levels less than
15 ppt, irrespective of the maternal levels. A dose-response pattern in the sex ratio was found
across the paternal exposure categories. That is, the sex ratio decreased with increased paternal
TCDD levels (linear test for trend, p = 0.008). In the unexposed group, the sex ratio (male to

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female) was 0.56 (95% CI = 0.49-0.61), while in the highest exposure group
(281.0-26,400.0 ppt) the corresponding sex ratio was 0.38 (95% CI = 0.28-0.49).

Stratified analyses by age at paternal exposure revealed that the sex ratio was altered to a
greater degree among fathers who were younger than 19 at the time of the explosion. The male
to female ratio among the unexposed fathers was 0.56 (95% CI = 0.50-0.62), while it was 0.38
(95% CI = 0.30-0.47) for those younger than 19 when exposed and 0.47 (95% CI = 0.41-0.53)
for those exposed after 19. Regardless of the age at the time of exposure, however, fathers who
were exposed had a statistically significantly different birth ratio (they were more likely to father
girls) than those who were unexposed (p < 0.05).

Separate analysis of birth ratios based on paternal TCDD exposure estimated at the time
of conception did not show the same dose-response pattern but did show strong evidence of
consistently decreased male births relative to females. More specifically, the male to female
birth ratios among the four successive quartiles (first through fourth) were 0.41, 0.33, 0.33,
and 0.46.

2.4.1.2.1.5.2.2. Study evaluation.

Mocarelli et al. (2000, 197448) based the characterization of TCDD exposure on serum
samples, which is an objective method for characterizing dose. Unlike for the occupational
cohorts, serum measures for this study were taken close to the time of the accident, and
therefore, back-extrapolation of TCDD exposures is unnecessary. Exposure received before the
age of 19 at the time of the explosion were more strongly associated with a reduced male to
female ratio than those received after the age of 19. The cut off age of 19 seems to be somewhat
arbitrary, resulting in a highly uncertain critical exposure window. TCDD levels at the time of
conception did not demonstrate a dose-response relationship, but paternal exposures resulted in
consistently reduced male to female birth ratios (range: 0.33-0.46).

The study findings are unlikely to be influenced by age at conception as these values
were found, on average, to be similar across calendar years. This suggests that age at conception
was not an important confounder and that the birth ratio findings may be related to paternal
exposures.

The methods used to identify births appear to be appropriate. Even if some
under-ascertainment of births occurred, there is no reason to believe that ascertainment would be

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related to TCDD exposure and the sex of the baby. Therefore, no bias is suspected due to
incomplete birth ascertainment.

2.4.1.2.1.5.2.3. Suitability of data for TCDD dose-response modeling.

TCDD exposures were well-characterized, and internal cohort analyses demonstrate
association between paternal TCDD levels at the time of the accident and birth ratio. However,
the change in sex ratio was only statistically significant when exposure occurred before 19 years
of age. It is impossible to identify the relevant time interval over which TCDD dose should be
considered for dose-response analysis; specifically, it is difficult to discern whether the different
sex ratio is a consequence of the initial peak exposure before 19 years of age or a function of the
average cumulative exposure over this entire exposure window. Assuming the initial high
exposure is the correct exposure window, using the initial exposures in a dose-response model
would yield LOAELs that are too high to be relevant to factor into the RfD calculation. The
differences between the two dose estimates are quite large. Dose-response analysis for this
outcome, therefore, was not conducted.

2.4.1.2.1.5.3. Baccarelli et al. (2002, 197062; 2004, 197045)—Immunologic effects.
2.4.1.2.1.5.3.1. Study summary.

The relationship between TCDD and immunological effects was evaluated in a sample of
Seveso residents (Baccarelli et al., 2002, 197062; Baccarelli et al., 2004, 197045). Both studies
were based on findings from 62 individuals who were randomly selected from Zones A and B.
An additional 59 subjects were chosen from the surrounding noncontaminated areas. Residency
was based on where subjects lived at the time of the accident (July 10, 1976) (Landi, 1998,
594409). Frequency matching ensured that the two groups of subjects were similar with respect
to age, sex, and cigarette smoking status.

TCDD levels were determined by mass spectrometric analysis of plasma samples.

TCDD levels at the time of sampling were obtained, and estimates of levels at the time of the
accident also were estimated by assuming an 8.2-year half-life (Landi, 1998, 5944091 The
plasma was also used to characterize levels of the immunoglobulins (Ig) IgG and IgM and the
complement components C3 and C4. One subject was excluded due to lack of an immunological

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evaluation. Analyses are, therefore, based on 58 subjects in the noncontaminated areas and
62 individuals from the contaminated areas.

Nonparametric tests were applied to test for differences between the two groups.

Multiple regression also was used to describe the relationship between the variables. Adjustment
was made for several potentially confounding variables that were collected via a questionnaire.

An inverse association was noted with increasing TCDD levels and plasma IgG levels;
this result remained statistically significant after adjusting for other potential confounding
variables in the regression models. Specifically, the slope coefficient andp-value for the
unadjusted model were -0.35 (p = 0.0002) and for the adjusted model the p-v alue was 0.0004.
The authors did not present the slope coefficient for the adjusted model in either paper but noted
minimal differences between the adjusted and unadjusted results. In the 2004 analysis, the
authors present IgG, IgM, IgA, C3, and C4 median and interquartile values across TCDD
exposure quintiles. Decreased levels of IgG were observed in the highest exposure groups.
Specifically, the median values across the five quintiles (for lowest to highest) were 1,526;
1,422; 1,363; 1,302; and 1,163. The Kruskal-Wallis test for differences across the TCDD
categories was statistically significant {p = 0.002), which is consistent with the findings for the
continuous measures of TCDD. This finding persisted after excluding those subjects with
inflammatory diseases and those who used antibiotics or nonsteroidal anti-inflammatory drugs.
For the other plasma measures, no dose-response relationship was apparent based on median
values for IgM, IgA, C3, or C4 across TCDD quintiles. The authors highlight the need for
additional research, particularly given the excess of lymphatic tumors noted in the area.

Exposure to other dioxin-like compounds for both the TCDD and nonexposed areas were
reported to be at background levels.

2.4.1.2.1.5.3.2. Study evaluation.

Both TCDD exposure and health outcome measures are well characterized. TCDD
exposures, in particular, are based on current serum measures and, therefore, are not dependent
on assumptions needed to back-extrapolate to earlier time periods of exposure.

A dose-response relationship between TCDD and IgG is well documented for the
unadjusted model, but no details are provided on the change in the slope coefficient when other
covariates were added to the model.

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Interpreting the inverse association between TCDD exposure and IgG in terms of clinical
significance is not possible. The IgG values reported are much higher than those subjects with
antibody immunodeficiency disorders.

2.4.1.2.1.5.3.3. Suitability of data for TCDD dose-response modeling.

Although the data support an inverse dose-response association between IgG and TCDD,
because the relationship cannot be described in terms of clinical relevance with respect to a
specific adverse health outcome, these data were not suitable for quantitative dose-response
modeling.

2.4.1.2.1.5.4. Landi et al. (2003, 198362)—Gene expression.

2.4.1.2.1.5.4.1. Study summary

The impact of TCDD on the aryl hydrocarbon receptor (AhR) was evaluated by Landi
et al. (2003, 198362) in a population-based study of Seveso residents. AhR, a mechanistically
based biomarker of dioxin response, must be present for manifestation of most of the toxic
effects of TCDD, including tumor promotion and immunological and reproductive system effects
(Safe, 1986; Puga et al., 2000). AhR activates the transcription of several metabolizing enzymes
in addition to certain genes (Whitlock, 1999). The primary objective of the study was to
determine whether plasma levels of TCDD and TEQ are associated with the AhR-dependent
pathway in lymphocytes among Seveso residents. The genes involved in the pathway that were
examined included: AhR, aryl hydrocarbon receptor nuclear translocator, CYPA1A1 and
CYP1B1 transcripts, and CYPlAl-associated 7-ethoxyresorufin O-deethylase (EROD).

Study recruitment occurred from December 1992 to March 1994. A total of 62 subjects
were randomly chosen from the highest exposed zones in Seveso (Zones A and B), while 59
were chosen from the noncontaminated area (non-ABR). Those chosen from the
noncontaminated zone were matched by age, sex, and smoking. Assignment of zones was based
on place of residence where subjects lived at the time of the accident in 1976. Subjects provided
data via questionnaire on a variety of sociodemographic and behavioral risk factors, including
cigarette smoking. Multivariate models were adjusted for a variety of confounders including;
adjustment for age, gender, date of assay, actin expression, postculture viability, experimental
group, and cell growth.

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TCDD levels were determined using high-resolution gas chromatography, and 21 other
dioxins, or dioxin-like compounds, were measured to examine TEQ. Eleven measurements
taken on the 121 subjects were deemed inadequate and excluded, but no further information was
provided on these exclusions. Nine subjects from Zone B and fourteen subjects from Zone ABR
had TCDD levels below that of detection, and were assigned a value equal to the lipid-adjusted
detection limit divided by the square root of 2. The toxic equivalent for the mixture of
dioxin-like compounds (i.e., TEQ) was calculated by summing the products of the concentration
of each congener by its specific toxic equivalency factor.

The subjects provided between 5 and 50 mL of whole blood, which was centrifuged to
separate mononuclear cells. The cells were frozen and later thawed. Cells were cultured,
removed from the culture medium, and resuspended in a stimulation medium, 14 mL of which
was used for RNA analysis. Reverse transcription-PCR was conducted and EROD was assayed.
Differences in gene expression and EROD activity observed for various cell culture conditions
were compared using paired t-tests. The unpaired Student's t-test was applied to test for
differences between groups, while a Bonferroni factor was used to account for multiple
comparisons. Data for continuous variables were log-transformed.

TCDD accounted for 26% of the TEQ among the study subjects, but varied by zone (35%
in zone A and 18% in zone non-ABR). After adjusting for potential confounding, AhR was
inversely related to plasma TCDD levels in uncultured cells (p < 0.03) and in mitogen-stimulated
cells (p < 0.05). EROD was lower in cells cultured from subjects with higher plasma TCDD and
TEQ levels, and the corresponding continuous measure of EROD was statistically significant
(p < 0.05). No statistically significant associations with TCDD or TEQ were found with ARNT
or CYP1B1 in uncultured cell medium, nor with CYP1A1 or CYP1B1 in mitogen-stimulated
cells. In general, females had lower AhR transcripts and higher levels of dioxin.

Collectively, the findings suggest that TCDD exposure might reduce AhR expression in
unstimulated cells. Therefore, TCDD could exert an influence on the AhR pathway regulation.

2.4.1.2.1.5.4.2. Study evaluation.

The study used biologically based measures of both TCDD exposures and biomarkers or
AhR. Subject recruitment was based on randomly sampling of the cohort study population;
some individuals with severe medical illnesses were excluded (Landi, 1998, 594409). Although

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few details are provided on the number of subjects excluded for these reasons, given the
objective nature of the biomarker outcomes that were evaluated, such exclusions are unlikely to
be an important source of bias. The exclusion rates were also reported to be low and comparable
across the zones (five subjects from the noncontaminated zone non-ABR and four subjects from
zone B).

A strength of the study was the examination of other dioxin-like compounds via the TEQ
analysis. A limitation of the study included the relatively small number of subjects which
resulted in the grouping of several covariates, including TCDD exposures, into a small number
of categories. As such, slope coefficients derived from modeling continuous measures were
emphasized in the data presentation. Another key limitation of the study is the uncertainty of
how effects on AhR translate into subsequent development of cancer and other chronic health
effects.

2.4.1.2.1.5.4.3. Suitability of data for TCDD dose-response modeling.

It is unclear how associations between AhR biomarkers and TCDD levels translate into
an increased risk of cancer. Dose-response analysis for this outcome, therefore, was not
conducted.

2.4.1.2.1.5.5. Alaluusua et al. (2004, 197142)—Developmental dental effects.

2.4.1.2.1.5.5.1. Study summary.

Alaluusua et al. (2004, 197142) examined the relationship between TCDD and dental
defects, dental caries, and periodontal disease among Seveso residents who were children at the
time of the accident. Subjects were randomly selected from those individuals who had
previously provided serum samples in 1976, which was shortly after the accident. A total of
65 subjects who were less than 9.5 years of age at the time of the accident, and who lived in
Zones A, B, or R were invited to participate. Recruitment was initiated 25 years after the time of
the Seveso accident. An additional 130 subjects from the surrounding area (outside Zones A, B,
or R or "non-ABR zone") having the same age restriction were recruited. Subjects were
frequency matched for age, sex, and education. Questionnaires were administered to these
individuals to collect detailed information on dental and medical histories, education, and
smoking behaviors. Ten subjects who had completed at least high school were randomly

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excluded from the non-ABR zone to create groups with similar educational profiles.

Participation rates for the ABR and non-ABR zones were 74 and 58%, respectively.

One dentist who was blind to the patients' TCDD exposure levels assessed dental
aberrations. Dental caries was assessed using recommendations of the World Health
Organization. Periodontal status was described following a detailed evaluation of the surfaces of
the teeth. A radiographic examination was done to identify missing teeth, alveolar bone loss,
deformities in the roots, and jaw cysts.

Comparisons of the presence of dental enamel defects according to exposure status were
performed using logistic regression. Chi-square test statistics were applied to compare the
distributions in the prevalence of dental defects across several categorical covariates (i.e.,
education, age, and serum TCDD level). For those who were younger than 5 at the time of the
accident, dental defects were more prevalent among patients in zone ABR (42%) than those in
the non-ABR zone (26%) (p = 0.14). Zone ABR is characterized by higher levels of soil TCDD
levels relative to non-ABR. Serum levels permitted an improved characterization of risk as they
were available at an individual level, rather than using a zone of residence. Defect prevalence
was highest among those in the upper serum TCDD category (700-26,000 ng/kg) with 60% of
subjects having dental defects. The continuous measure of serum TCDD was associated with
developmental dental defects (p = 0.007) and hypodontia (p = 0.05).

2.4.1.2.1.5.5.2. Study evaluation.

Although the subjects with serum measures were selected randomly, no direct measures
of TCDD were made in subjects from the unexposed area (i.e., non-ABR zones). That those who
resided in the non-ABR areas had lower TCDD exposures would be a reasonable assumption.
Alaluusua et al. (2004, 1971421 however, provide few details about the sampling frame used to
identify these participants. Despite this fact, it is important to note that a dose-response pattern
was observed between TCDD exposure and presence of developmental defects in the ABR
population alone (p = 0.016). This finding is based on 27 subjects with developmental dental
defects. This positive association provides support for a quantitative dose-response modeling of
dental aberrations. The numbers of such subjects are small, however, with one, five, and
nine subjects having defects in the exposure groups of 31-226, 238-592, and
700-26,000 ng/kg TCDD, respectively.

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TCDD exposures were characterized using serum measures for those who resided in
zone ABR in 1976 (near the time of the accident). The authors could not account for additional
exposure to TCDD across subjects that might have occurred since the time of the accident, so
there is considerable uncertainty in delineating the critical exposure window for the reported
effects. In addition, the lack of exposure data for those in the non-ABR zone, however, makes
interpretation of the findings difficult. This difficulty is particularly evident, given that the
prevalence of dental defects was less among those in the low exposure category of zone ABR
(31-226 ng/kg TCDD) (10%) when compared to those in the non-ABR zone (26%).

2.4.1.2.1.5.5.3. Suitability of data for TCDD dose-response modeling.

Most of the considerations for conducting a dose-response analysis have been satisfied
with the study population, although, exposure assessment uncertainties are a limitation of this
study. For example, it is difficult to discern whether these health effects are a consequence of
the initial high exposure during childhood or a function of the cumulative exposure for this entire
exposure window beginning at the early age. If the latter is true, averaging exposure over the
critical window would add considerable uncertainty to effective dose estimates given the large
difference between initial TCDD body burden and body burden at the end of the critical
exposure window. Despite the uncertainty in defining the critical window of exposure,
dose-response analysis was conducted for this outcome.

2.4.1.2.1.5.6. Baccarelli et al. (2005, 197053)—Chloracne.

2.4.1.2.1.5.6.1. Study summary.

Baccarelli et al. (2005, 197053) published findings from a case-control study of
110 chloracne cases and 211 controls. The authors collected information on pigment
characteristics and an extensive list of diseases. This study was performed to yield information
about the health status of chloracne cases, TCDD-chloracne exposure response, and factors that
could modify TCDD toxicity. TCDD was measured from plasma. Following adjustment for
confounding, TCDD was associated with chloracne (OR = 3.7, 95% CI = 1.5-8.8), and the risk
of chloracne was considerably higher in subjects younger than 8 at the time of the accidents
(OR = 7.4, 95%) CI = 1.8-30.3). Among individuals with lighter hair, the association between
TCDD and chloracne was stronger than among those with darker hair.

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2.4.1.2.1.5.6.2.	Study evaluation.

Although a dose-response association was observed, chloracne is a rare health outcome
likely only to occur among those highly exposed.

2.4.1.2.1.5.6.3.	Suitability of data for TCDD dose-response modeling.

Given the very high TCDD levels needed to cause chloracne (e.g., Ott et al., 1993,
594322)1 quantitative dose-response modeling to characterize risks for the general population
with much lower TCDD exposures would be of little value. Therefore, quantitative
dose-response assessment for the Baccarelli et al. (2005, 197053) study was not conducted.

2.4.1.2.1.5.7. Baccarelli et al. (2008, 197059)—Neonatal thyroid hormone levels.
2.4.1.2.1.5.7.1. Study summary.

Baccarelli et al. (2008, 197059) investigated the relationship between thyroid function
and TCDD among offspring of women of reproductive age who were exposed in the
1976 accident. This health endpoint is relevant because thyroid function is important for energy
metabolism and nutrients and for stimulating growth and development of tissues. Neonatal
thyroid function at birth is evaluated through blood thyroid-stimulating hormone (b-TSH).

The study population was drawn from 1,772 women who were identified as having lived
in the highly contaminated areas (Zones A or B) at the time of the accident or between
July 10, 1976 and December 31, 1947; were of fertile age (born after 1947); and were alive as of
January 1, 1994. A random sample of 1,772 unexposed women who lived in the reference area
was selected using frequency matching by year of birth to the exposed women, and residency in
the reference area at the time of the accident. The reference area represents the noncontaminated
areas that surround the three zones of decreasing exposure (Zones A, B and R). In total,
55,576 women had lived in the reference area. Population registry offices (n = 472) were
contacted to detect children born to these women. Records could be traced for virtually all
subjects (1761/1772 exposed; 1762/1772 unexposed). Children born outside the Lombardy area
were excluded as b-TSH could not be obtained for them. This accounted for 156 of the
1,170 children identified. The analyses were based on the remaining 56, 425, and 533 singletons
born between January 1, 1994, and June 30, 2005 in Zone A, B, and from the reference area,
respectively.

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Thyroid function is tested in all newborns by b-TSH measures in the region of Lombardy
where Seveso is located. These measures are obtained from blood samples taken 72 hours after
birth using a standardized protocol. The b-TSH levels were log transformed to approximate a
normal distribution. Linear regression analysis was used to conduct test for trends in mean
b-TSH levels across different covariates. Logistic regression was used to assess associations
between elevated b-TSH levels defined by the cutpoint of 5 [j,U/mL and residence in particular
zones of contamination. The 5 |iU/mL cutpoint for TSH measurements in neonates was
recommended by WHO (1994) for use in neonatal population surveillance programs. Although
WHO established the standard for increased neonatal TSH in the context of iodine deficiency
disease, the toxicological implications are the same for TCDD exposure and include increased
metabolism and clearance of T4. Generalized estimating equations were used to adjust the
standard errors of the ORs for correlation between siblings.

The mean levels of b-TSH were positively associated with average soil TCDD
concentrations in the three areas (Zone A: 1.66 [j,U/mL; Zone B: 1.35 [j,U/mL; and Zone R:
0.98 (j,U/mL) (p < 0.001). Plasma TCDD levels also were shown to be much higher in a group of
51 newborns that had b-TSH levels >5 |iU/mL. Compared to the reference population, adjusted
ORs were elevated for Zone B (OR = 1.90, 95% CI = 0.94-3.86) and Zone A (OR = 6.63,
95% CI = 2.36-18.6). These ORs were adjusted for gender, birth weight, birth order, maternal
age at delivery, hospital, and type of delivery. The adjusted ORs however differed only slightly
from those that were unadjusted (Zone B, OR = 1.79, 95% CI = 0.92-3.50; Zone A OR = 6.60,
95% CI = 2.45-17.8). Of the risk factors considered, both gender and birth weights were
associated with neonatal b-TSH.

The paper also included an analysis of children born to 109 women who were part of the
Seveso Chloracne Study (Baccarelli et al., 2005, 197053). A total of 5 1 children were born to
38 of these women, of these 12 lived in Zone A, 10 in Zone B, 20 in Zone R, and 9 from the
reference population. Several congeners including TCDD were measured in maternal plasma.
TCDD levels were extrapolated to the date of delivery using a first-order pharmacokinetic model
(Michalek et al., 1996, 198893). The elimination rate used was 9.8 years based on the mean
half-life estimate from a previous study of women in the Seveso region (Michalek et al., 2002,
199579). TEQs were calculated for a mixture of dioxin-like compounds by multiplying the
concentration of each congener by its toxicity equivalence factor. The maternal average TEQ

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was 44.8 ppt (range: 11.6-330.4) among 51 mothers. The measurement of noncoplanar PCBs
occurred only later in the study (1996) and, therefore, total mean TEQs (i.e., including the sum
of PCDDs, PCDFs, coplanar PCBs, and noncoplanar PCBs) are available only on a subset
(n = 37) of the population. Dioxin-like congeners were examined in this study as several studies
suggest associations between the sum of PCBs, or individual congeners having decreased
thyroxine (T4; Longnecker et al., 2000, 201463; Sandau et al., 2002, 594406). and increased
TSH (Alvarez-Pedrerol et al., 2008, 594407; Chevrier et al., 2007, 5944081 The following
confounders were examined by the authors in the plasma dioxin models: maternal body mass
index, smoking habits, alcohol consumption, and neonatal age in hours at b-TSH measurement.

The authors used a linear model to examine the association between maternal TCDD
levels and b-TSH. The standardized regression coefficient obtained from this model was 0.47
(p < 0.001). For the evaluation of TEQs, a similar association was noted for PCDDs, PCDFs,
and coplanar PCBs (n = 51, P = 0.45, p = 0.005) but not with noncoplanar PCBs (n = 37,
P = 0.16,p = 0.45). Multivariate regression models that were adjusted for several covariates
(i.e., gender, birth weight, birth order, maternal age at delivery, hospital, and type of delivery)
found statistically significant associations with plasma TCDD, PCDDs, PCDFs, and coplanar
PCBs, but not with noncoplanar PCBs. The sum of all total TEQs from the measured
compounds was not statistically significant (n = 37, P = 0.31 ,p = 0.14).

2.4.1.2.1.5.7.2.	Study evaluation.

The Baccarelli et al. (2008, 197059) study satisfies the epidemiological considerations
and criteria for determining whether dose-response modeling should be pursued. The outcome is
well defined, and a dose-response pattern was observed. The study also contained a substudy
that characterized TCDD and exposures to other dioxin-like congeners and used serum measures
for a sample of mothers. Results were consistent among the zone of residence analysis and the
substudy based on serum measures.

2.4.1.2.1.5.7.3.	Suitability of data for TCDD dose-response modeling.

Given the potential for exposure misclassification due to variability in TCDD soil levels
within each zone, modeling should rely on individual-level TCDD exposures derived from the
serum sampling substudy. The study data provide an opportunity for quantitative dose-response

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analyses as the critical exposure window of 9 months can be used for exposure assessment
purposes.

2.4.1.2.1.5.8. Mocarelli et al. (2008, 199595)—Sperm effects.

2.4.1.2.1.5.8.1. Study summary.

Mocarelli et al. (2008, 199595) examined the relationship between TCDD and endocrine
disruption and semen quality in a cohort of Seveso men. A total of 397 subjects of the eligible
417 males (<26 years old in 1976) from Zone A and nearby contaminated areas were invited to
participate. Frozen serum samples were used to derive TCCD exposures. Also, 372 healthy
blood donors not living in the TCCD-contaminated area were invited to participate. The
researchers collected a health questionnaire and semen samples from participants. Analyses
were based on 257 individuals in the exposed group and 372 in the comparison group.

Semen samples were collected postmasturbatory at home. Ejaculate volume, sperm
motility, and sperm concentration were measured on these samples. Fasting blood samples also
were collected from the subjects for reproductive hormone analyses, including 17P-estradiol
(E2), follicle stimulating hormone (FSH), inhibin B, luteinizing hormone (LH), and testosterone.

The researchers estimated serum concentrations of TCDD from samples provided in
1976-1977, and also in 1997-1998 for individuals whose earlier samples had TCDD values that
exceeded 15 ppt. Serum concentrations for the comparison group were assumed to be less than
15 ppt in 1976 and 1977 and <6 ppt in 1998/2002 on the basis of serum results for residents in
uncontaminated areas. The exposed and comparison groups were divided into three groups
based on their age in 1976: 1-9, 10-17, and 18-26 years. Mocarelli et al. (2008, 199595)
applied a general linear model to the sperm and hormone data and included exposure status, age,
smoking status, body mass index, and occupational exposures as covariates. The study authors
thoroughly addressed the potential for confounding.

Men exposed between the ages of 1 and 9 had reduced semen quality 22 years later.
Reduced sperm quality included decreases in sperm count (p = 0.025), progressive sperm
motility (p = 0.001), and total number of motile sperm (p = 0.01) relative to the comparison
group. The opposite pattern was observed for several indices of semen quality among those aged
10-17 at the time of the accident; this included a statistically significant increase in sperm count
(p = 0.042). The clinical significance of this increase is unknown. For the hormone analyses,

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those in the exposed group had lower serum E2 levels, and higher follicle stimulating hormone
concentrations. Neither testosterone levels nor inhibin B concentrations were associated with
TCDD exposure.

2.4.1.2.1.5.8.2.	Study evaluation.

The findings of the Mocarelli et al. (2008, 199595) study support the hypothesis that
exposure to TCDD in infancy/prepuberty reduces sperm quality. The changes in serum E2 and
FSH concentrations are of unknown clinical significance, and cannot be considered adverse.
Although most semen analysis studies have low compliance rates in general population samples
(20-40%) (Jorgensen et al., 2001, 594402; Muller et al., 2004, 594403), the compliance rate in
this study was much higher (60%). Given that the compliance rates were similar between the
exposed and comparison groups and the strong differences detected across the two age groups,
selection bias appears unlikely in this study.

2.4.1.2.1.5.8.3.	Suitability of data for TCDD dose-response modeling.

Health outcomes are well defined in the Mocarelli et al. (2008, 199595) study, and
exposures are well characterized using serum data. Because the men exposed to elevated TCDD
levels between the ages of 1 and 9 had reduced semen quality 22 years later, it is difficult to
identify the relevant time interval over which TCDD dose should be considered. Specifically, it
is difficult to discern whether this effect is a consequence of the initial high exposure between
1 and 9 years of age or a function of the cumulative exposure for this entire exposure window
beginning at the early age. However, the differences between these two dose estimates (the
initial high exposure versus the cumulative exposure for the 9 year window) are minimal (i.e.,
within an order of magnitude). Despite the uncertainty in estimating the critical window of
exposure, dose-response analysis for this outcome was conducted.

2.4.1.2.1.6. The Chapaevsk study.

2.4.1.2.1.6.1. Revich et al. (2001, 199843)—Mortality and reproductive health.

2.4.1.2.1.6.1.1. Study summary.

Revich et al. (2001, 199843) describe a series of investigations that have evaluated
adverse health outcomes among residents of Chapaevsk where ecological measures of TCDD

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have been noted to be higher than expected. In the earlier cancer section of this report, the
cross-sectional comparisons of mortality that the authors carried out between Chapaevsk
residents and a general population reference were described. Although the general focus of this
paper is on cancer, the authors examined other adverse health outcomes.

For all-cause mortality, rates were found to be higher in Chapaevsk relative to the Samara
region and other nearby towns. The magnitude of this increase, however, was not quantified in
the review by Revich. Cardiovascular mortality accounted for nearly two-thirds of women's
deaths and almost half of those among men. The rates of cardiovascular mortality among
Chapaevsk men have been reported to be 1.14 times higher than those in Russia.

Revich et al. (2001, 199843) also reported on the occurrence of adverse reproductive
events. Although the authors indicated that official medical information was used to make
comparisons between regions, no details were provided about data quality, completeness, or
surveillance differences across areas. The presented rates for reproductive health outcomes
should be interpreted cautiously. A higher rate of spontaneous abortions (24.4 per
100 pregnancies finished by delivery) was found in Chapaevsk women relative to rates that
ranged between 10.6 and 15.2 found in five other areas. The frequency of preeclampsia also was
found to be higher in Chapaevsk women (44.1/100) relative to other towns, as was the proportion
of low birth-weight babies and preterm births. The percentage of newborns with low birth
weight was slightly larger in Chapaevsk (7.1%) when compared to other towns in Samara
(5.1-6.2%); observed differences, however, were not statistically significant. The authors also
reported on the sex ratio of newborns born between 1983 and 1997. These ratios (boys:girls)
were highly variable and ranged between 0.79 and 1.29. Given the annual variability of this ratio
on a year-to-year basis, it is unclear if this is largely due to natural fluctuations and to what
extent this may result from prior TCDD (or other contaminants) exposure TCDD and other
contaminants.

2.4.1.2.1.6.1.2. Study evaluation.

The review by Revich et al. (2001, 199843) highlights analyses that have been
undertaken using largely cross-sectional data. Although soil sampling measures appear to
demonstrate decreasing levels of TCDD in the soil with increasing distance from the plant, at this
time, no individual-level TCDD exposure data are available. Increased rates of mortality relative

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to the Samara region in Russia were observed among Chapaevsk men for all cancer sites
combined; this excess risk however, was not observed among women. Although the authors
provide compelling evidence of increased adverse events among residents of Chapaevsk, the
study lacks a discussion about the validity of comparing health data across regions, and suffers
from inherent limitations from ecological studies such as exposure misclassification.

2.4.1.2.1.6.1.3. Suitability of data for TCDD dose-response modeling.

As with the cancer outcomes presented in this study, the data for noncancer outcomes are
limited by the absence of TCDD levels on an individual-level basis and information on other
potential confounding variables that could have biased the comparisons. Additional studies are
being undertaken to evaluate the relationship between TCDD and the sexual and physical
development of boys. The cross-sectional nature of the data that were presented does not
provide the necessary level of detail needed to estimate effective dose given the lack of
individual-level exposure data. Therefore, a quantitative dose-response analysis was not
conducted.

2.4.1.2.1.7. The Air Force Health {"Ranch Hands" cohort) study.

2.4.1.2.1.7.1. Michalek and Pavuk (2008, 199573)—Diabetes.

2.4.1.2.1.7.1.1. Study summary.

Michalek and Pavuk (2008, 199573) examined both the incidence of cancer and the
prevalence of diabetes in the cohort of Ranch Hand workers exposed to TCDD. As noted
previously, these veterans were responsible for aerial spraying of Agent Orange in Vietnam
between 1962 and 1971. Exposure to TCDD was estimated using serum collected from
participants in 1987 and assayed for TCDD. Exposure to TCDD was estimated using a
first-order pharmacokinetic model with a half-life of 7.6 years and provided an estimate of
TCDD at the end of the tour of duty in Vietnam. Veterans were grouped into four categories:
comparison, background, low, and high. Diabetes was identified from diagnoses during the
post-Vietnam era from medical records. Overall, no differences were shown in the RR of
diabetes between the Ranch Hand unit and the reference group (RR = 1.21, p = 0.16). Stratified
analyses by days of spraying (<90 days, >90 days), however, revealed a significant increase in
risk of diabetes (RR = 1.32,/? = 0.04) among those who sprayed for at least 90 days. A dose-

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response relationship was also evident when loglOTCDD was modeled in the combined cohort.
Also, stratification by calendar period showed a dose-response relationship for those whose last
year of service was during or before 1969.

2.4.1.2.1.7.1.2.	Study evaluation.

The Michalek and Pavuk (2008, 199573) study provides an opportunity to characterize
risks of diabetes as the study is not subject to some of the potential bias of case ascertainment
based on death certificates (D'Amico et al., 1999, 197389). The quality of the TCDD exposure
estimates is high, given that serum data were available at an individual-level basis for all Ranch
Hand and comparison veterans used in the cohort. Although disentangling the effects of 2,4-D
and TCDD is not possible because their concentrations in Agent Orange are equivalent, 2,4-D
has not been associated with diabetes.

2.4.1.2.1.7.1.3.	Suitability of data for TCDD dose-response modeling.

The reported dose-response relationship between TCDD and diabetes is supported by
study strengths including the use of the individual-level level TCDD serum measures and the
identification of diabetes through medical records are important strengths of the Michalek and
Pavuk (2008, 199573) study. Nonetheless, the possible confounding from the inability to control
for 2,4-D and other agents used in Agent Orange precludes a quantitative dose-response analysis.

2.4.1.2.1.8. Other noncancer studies of TCDD.

2.4.1.2.1.8.1. Ryan et al. (2002, 198508)—Sex ratio.

2.4.1.2.1.8.1.1. Study summary.

Ryan et al. (2002, 198508) conducted an investigation on the sex ratio in offspring of
children of pesticide workers who were involved with the production of trichlorophenol and the
herbicide 2,4,5-T in Ufa, Bashkortostan, Russia. Ufa was the site of a state agrochemical plant
that has been in operation since the 1940s. Between 1961 and 1988, the plant employed more
than 600 workers, most in their early 20s. Females, however, accounted for about 15% of the
workforce that produced 2,4,5-T and 30% for 2,4,5-trichlorophenol.

Serum samples previously taken in 1992 among 60 men, women, and children from the
factory and city of Ufa showed TCDD exposures that were approximately 30 times higher than

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background levels (Ryan and Schecter, 2000, 594412). Blood data were subsequently measured
on a sample of 20 workers between 1997 and 2000, and on 23 2,4,5-trichlorophenol workers
between 1997 and 2001. In all, 84 individuals who provided blood samples formed the basis of
the analysis in this study. Of these, 55 were exposed to 2,4,5-T and 29 were exposed to
2,4,5-trichlorophenol.

Ryan et al. (2002, 198508) reviewed company records for these workers to determine the
number, sex, and date of birth of any children; birth data were available for 198 workers.
Awareness of the study led other workers who had not provided serum to provide information on
births that occurred 9 months after the time of first employment in the factory.

The authors calculated descriptive statistics for the 198 workers and compared them to
values for the city of Ufa between 1959 and 1996. Tests of statistical significance were made
using the z-test, and the chi-square test. The observed proportion of male births (0.40) among
the factory workers was much lower than that for the city of Ufa (0.51) (p < 0.001). Stratified
analyses revealed that this lower ratio was observed only among those paternally exposed to
TCDD. Specifically, the proportion of male births among exposed fathers was 0.38 and among
exposed mothers was 0.51. This pattern was observed in both the workers exposed to 2,4,5-T
(proportion of male births = 0.40) and 2,4,5-trichlorophenol (proportion of male births = 0.35).

2.4.1.2.1.8.1.2. Study evaluation.

The Ryan et al. (2002, 198508) findings are consistent with earlier work completed for
Seveso residents (Mocarelli et al., 2000, 197448). Although serum measures were available for
84 individuals, no dose-response of birth ratios was performed using exposure quantified at an
individual-level basis. This approach would have been preferred and consistent with that which
Mocarelli et al. (2000, 197448) used. All comparisons were made using an external comparison
group, namely the sex ratio observed in Ufa between 1959 and 1996.

Although serum measures were used to describe TCDD exposure for a sample of the
workers, individual-level dose estimates were not calculated for the study population.
Specifically, exposures were characterized many years after exposure, and no attempt was made
to back-extrapolate to the time of conception. The two groups of workers in the study also
reportedly had high exposure levels of 1,2,3,7,8-pentachlorodibenzo-p-dioxin. So, the group

level exposure classification (by plant) did not allow consideration of confounding due to other

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dioxin-like compounds. Another limitation of the study is that the study population is likely
nonrepresentative of all workers employed at the plant. Participants included only those willing
to provide serum samples and those who volunteered to participate in the study after learning
about it in a public forum. If participation was dependent on TCDD exposures and the
reproductive health of these subjects, then bias may have occurred.

2.4.1.2.1.8.1.3. Suitability of data for TCDD dose-response modeling.

The findings are notable in their consistency with those found in Seveso residents by
Mocarelli et al. (2000, 197448). For the Ryan et al. (2002, 198508) study, serum data were
quantified at an individual-level basis. Risk estimates, however, were not derived in relation to
these exposures but instead in two separate subgroups (2,4,5-T and 2,4,5-trichlorophenol
workers). This important limitation precludes the use of these data for quantitative
dose-response modeling.

2.4.1.2.1.8.2. Kang et al. (2006, 199133)—Long-term health effects.

2.4.1.2.1.8.2.1. Study summary.

Kang et al. (2006, 199133) investigated the relationship between self-reported health
measures and serum-based measures of TCDD in a group of 1,499 Vietnam veterans and a
control group of 1,428 non-Vietnam veterans. The study subjects were identified from

(1)	reports of Army Chemical Corps detachments in Vietnam between 1966 and 1971,

(2)	personnel records of individuals involved in chemical operations who were on active duty
between 1971 and 1974, and (3) class rosters of personnel who were trained at Fort McClellan in
Alabama between 1965 and 1973. The comparison group was selected so that branch of service,
time period, and military occupation were similar to those of the subjects with the exception that
they did not serve in Vietnam. Although 2,872 Vietnam veterans and 2,732 non-Vietnam
veterans were identified as potential subjects, those who were deceased as of December 1998
and those who had previously participated in a pilot study were excluded. The study targeted
2,247 Vietnam and 2,242 non-Vietnam veterans.

Exposure to TCDD was characterized for subsets of the study population that provided
blood samples, specifically 795 of 1,085 (73%) Vietnam veterans and 102 of 157 (65%)

non-Vietnam veterans. Details on these individuals selected for participation in the serum dioxin

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study were not presented. The authors did state, however, that due to economic constraints, only
897' serum samples could be analyzed. Blood specimens were collected in 1999-2000 at
individuals' homes. TCDD concentrations were analyzed by laboratory staff blind to the group
status (i.e., Vietnam or non-Vietnam) of the study subjects.

Prevalent health outcomes were ascertained by self-reported information on selected
conditions diagnosed by a medical doctor. The following conditions were included: diabetes,
hepatitis (all types combined), heart disease, all cancer, nonmalignant chronic respiratory
diseases, and hypertension. Health-related quality of life was evaluated using the SF-36 survey
instrument (Ware et al., 1993, 004687).

Eligible veterans whose current residences (4,119 total) could be identified were
contacted for study participation. Survey participation rates were 72.9% for Vietnam veterans,
yielding data for 1,499 individuals, and 69.2% for non-Vietnam veterans, yielding data for
1,428 non-Vietnam veterans. The survey data showed that, relative to non-Vietnam veterans,
Vietnam veterans were more likely to be regular smokers and to be obese. They also were more
likely to be enlisted personnel, and a much higher proportion was 51 years of age or older
(83.4%) vs. 58.4%>). After adjusting for age, race, smoking status, rank, and body mass index, the
prevalence of self-reported health conditions was found to be statistically significantly higher in
the Vietnam group. The adjusted odds ratios (OR) were as follows: diabetes, OR =1.16
(95% CI = 0.91, 1.49); hepatitis, OR= 1.85 (95% CI = 1.30, 2.64); heart condition, OR= 1.09
(95%o CI = 0.87, 1.38); all cancer, OR = 1.46 (95% CI = 1.02, 2.10); nonmalignant respiratory
condition, OR = 1.41 (95% CI = 1.13, 1.76); and hypertension, OR= 1.06 (95% CI = 0.89, 1.27).

For those with Vietnam service, the mean serum TCDD concentrations were higher
among those who reported spraying herbicides (4.3 parts per thousand [ppt]) than those who did
not (2.7 ppt) (p < 0.001). The investigators did not back-extrapolate serum levels to the time
when individuals last sprayed. The adjusted ORs (adjusted for age, cigarette smoking, body
mass index, rank, and race) for most chronic health conditions examined revealed increased
prevalence among Vietnam sprayers relative to non-Vietnam sprayers. These ORs were:
diabetes, OR = 1.49 (95% CI =1.10, 2.02); hepatitis, OR = 1.40 (95% CI = 0.92, 2.12); heart
condition, OR = 1.41 (95% CI = 1.06, 1.89); all cancer, OR = 1.36 (95% CI = 0.91, 2.04);
nonmalignant respiratory condition, OR = 1.57 (95% CI = 1.20, 2.07); and hypertension,
OR = 1.26 (95% CI = 1.00, 1.58).

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The investigators also examine the possibility of over-reporting of chronic health
conditions by comparing the prevalence of self-reported conditions among 357 Vietnam sprayers
who mean serum TCDD levels of 2.5 ppt compared to those who had levels less than 2.5 ppt.
Prevalence of diabetes, heart condition, and hypertension, was higher among those with mean
serum TCDD levels of 2.5 ppt, although no levels of statistical significance were reported. Data
for cancer were not presented.

2.4.1.2.1.8.2.2. Study evaluation.

Because data were collected from only half of the individuals in the study target
population, there is some potential for selection bias in this study. First, the study excluded those
who had died before 1999, excluding potentially important TCDD-related adverse health effects
that could result in death more than two decades after veterans had been actively spraying.
Second, survey participation rates were modest: 72.9% for Vietnam veterans and 69.2% for
non-Vietnam veterans. If those in poorer health were less inclined to participate, the prevalence
of the selected chronic health conditions would be understated. Selection bias due to study
participation could also be possible if, for example, those in poorer health also had high (or
lower) exposures than those not participating in the study. The lack of direct evidence of
differential participation and reports of comparable prevalence rates of hypertension and diabetes
to other general populations suggests that selection bias may be minimal.

Because the data collected are cross-sectional, they are ill-suited for evaluating the
relationship between the timing of exposure and the onset of disease. Whether any of the data
could help identify when the chronic health conditions were diagnosed is unclear. Given the
long period covered by the study, many of the self-reported health conditions likely were
diagnosed some time ago, perhaps closer to the time of potential TCDD exposure. Such detail is
needed to characterize health risks associated with specific TCDD levels, particularly given that
TCDD levels have been demonstrated to decrease from time of last exposure.

An important strength of the study is the availability of blood sera for a subset of the
study population, which allows for an objective determination of TCDD exposure. That serum
TCDD levels were available for only 897 subjects, however, limits the ability to examine the
relationship between measures of TCDD and prevalence of health outcomes without restricting

the sample size or extrapolating exposure levels to the whole study population. For example,

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among sprayers with available TCDD exposure data only 60 cases of diabetes and 69 cases of
heart disease were examined relative to exposure. Also, the small number of cancers precluded a
cancer site-specific analysis. Moreover, whether these TCDD levels are representative of the
larger eligible population is difficult to gauge, given that deceased veterans and those whose
current residences could not be determined were excluded.

The study relied on self-reported measures of disease prevalence. The ascertainment of
chronic health conditions using self-reported data can be fraught with difficulties. For example,
the sensitivity of self-reported data when compared to medical diagnosis has been shown to be
poor for conditions such as diabetes and hypertension (Okura et al., 2004). As Kang et al. (2006,
199133) state, prevalence studies are not be well suited to examine rare diseases with short
survival times such as cancer. In addition, self-reports of physician-diagnosed cancers by study
subjects often lacks the sensitivity needed in most epidemiological studies as they can be
influenced by a variety of factors including age and education (Navarro et al., 2006).

The potential for biases in the reporting of health outcomes between the sprayers and the
non-Vietnam veterans (i.e., differential by TCDD exposure status) also is plausible, given the
public attention that spraying of Agent Orange has received. Although the authors examined
whether over-reporting was related to outcome prevalence among herbicide sprayers (prior to
collection and determination of actual TCDD serum levels), the possibility exists that these
subjects reporting could be influenced by their perceived level of exposure from herbicide
spraying. The authors also examined the potential for misreported diabetes by conducting a
medical records review of 362 veterans. Seventy-nine percent of the self-reported diabetes cases
were confirmed with medical records. The documentation rate was also comparable between the
Vietnam veterans and the non-Vietnam veterans suggesting that differential reporting was not an
issue for this health outcome.

Because the Vietnam veterans group comprised professional sprayers, it is not
unreasonable to assume that they would have been exposed to other potentially harmful agents
either during their service in Vietnam, or from the end of their service to when they provided
data in 1999-2000. This study did not control for other, potentially relevant occupational
exposures.

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2.4.1.2.1.8.2.3. Suitability of data for TCDD dose-response modeling.

Although the study demonstrates increased prevalence of several chronic health
conditions, these findings should be interpreted with caution due to potential for selection and
recall biases. The lack of demonstrated dose-response relationships with cancer or other
outcomes precluded the use of these data for characterizing the dose response from TCDD.

2.4.1.2.1.8.3. McBride et al. (2009, 198490; 2009, 197296)—Noncancer mortality.
2.4.1.2.1.8.3.1. Study summary.

The McBride et al. (2009, 198490) mortality study of New Zealand workers employed as
producer or sprayers with potential exposure to TCDD was described earlier in this report.

These individuals were employed at a plant that manufactured 2,4,-dichlorophenoxyacetic acid,
and later 2,4,5-T and 4-chloro-2-methyphenoxyacetic acid. In 1987, the plant closed and 2,4,5-T
production ceased in 1988.

The cohort consisted of 1,754 individuals who were employed for at least one day at the
New Plymouth site between January 1, 1969, and October 1, 2003. Vital status was determined
until the end of 2004. Comparisons of mortality were made to the New Zealand general
population using the SMR statistic. Exposure was characterized by duration of employment.
Person-years of follow-up were tabulated across strata defined by age, calendar period, duration
of employment, sex, latency, and period of hire. Analyses were stratified to compare risks by
duration of employment (<3 or >3 months), latency (<15 or >15 years), and period of hire
(<1976, >1976).

Overall, no statistically significant differences in all-cause mortality relative to the
general population were found among those who worked for at least 3 months (SMR = 0.92,
95% CI = 0.80-1.06) or for less than 3 months (SMR= 1.23, 95% CI = 0.91-1.62). No
statistically significant excesses were found for mortality from diabetes, cerebrovascular disease,
heart diseases, or accidents. The incorporation of a latency period of 15 years revealed no
statistically significant excesses for these same causes of death. Similarly, no excesses for any
cause of death were noted among those who were hired either before or after 1976.

In subsequent analyses of the same cohort that used estimated TCDD levels from serum
samples, McBride et al. (2009, 197296) found no excesses for all-cause mortality or mortality
from diabetes or heart disease.

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2.4.1.2.1.8.3.2.	Study evaluation.

For the McBride et al. (2009, 198490) study, the size of the cohort is large enough to
characterize mortality risks relative to the general population for most common causes of deaths.
An important limitation of this study is the loss to follow-up of a substantial percentage of
workers (22%). This would have impacted statistical power by reducing the number of deaths
among the workers. If this incomplete ascertainment of mortality outcomes did not occur in a
similar fashion with the general population then the SMR may also be biased.

For noncancer causes of death, the use of the SMR statistic is more likely to be
influenced by the healthy-worker effect. Therefore, the findings obtained for these outcomes
should be interpreted with caution. Subsequent analyses published by the same authors
(McBride et al., 2009, 197296) provide improved characterization of TCDD exposure using
serum samples.

2.4.1.2.1.8.3.3.	Suitability of data for dose-response analysis.

Overall, no associations were evident between surrogate measures of TCDD (duration of
employment, year of hire) and noncancer mortality outcomes. Further, the use of mortality
endpoints is inconsistent with EPA RfD methodology. As such, these data do not support further
use in a quantitative dose-response analysis.

2.4.1.2.1.8.4. McBride et al. (2009, 197296)—Noncancer mortality.

2.4.1.2.1.8.4.1. Study summary.

McBride et al. (2009, 197296) further analyzed the cohort of New Zealand workers to
include estimates of TCDD exposure based on serum samples. Current and former employees
who were still alive and living within 75 km of the site were asked to provide serum samples.
Samples were collected from 346 workers representing 22% (346/1599) of the entire study
population. These serum measures were used to estimate cumulative TCDD levels for all
workers. The exposure assessment approach by Flesch-Janys et al. (1996, 197351) was used to
estimate time-dependent exposures based on area under the curve models. This was based on a
one-compartment first-order kinetic model with a half-life of 7.2 years.

Comparisons of mortality were made to the general population using the SMR statistic.
The Cox proportional hazards model was used to conduct an internal cohort analysis across

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four categories of cumulative TCDD levels for diabetes and ischemic heart disease mortality.
The RRs generated from these models were adjusted for sex, hire year, and birth year. No
diabetes deaths were observed among women, and therefore, analysis of this outcome was
limited to men.

Relative to the general population, no difference in the all-cause mortality experience was
observed in exposed cohort members (SMR = 1.0, 95% CI = 0.9-1.2). Similarly, no excess in
these workers was observed for heart disease (SMR =1.1, 95% CI = 0.9-1.5); cerebrovascular
disease (SMR = 1.1, 95% CI = 0.6-1.9); diabetes (SMR =0.7, 95% CI = 0.2-2.2); or
nonmalignant respiratory disease (SMR = 0.8, 95% CI = 0.4-1.4). For the internal cohort
analysis, the RR associated with cumulative categorical TCDD measure was 1.0 for both
diabetes and ischemic heart disease.

2.4.1.2.1.8.4.2. Study evaluation.

The McBride et al. (2009, 197296) study extends the earlier work the same authors
completed in two ways. First, serum measures were used to estimate cumulative TCDD with
methodology that has been applied to several other cohorts of workers exposed to TCDD.

Second, the authors used regression analyses that examined individual-level TCDD exposures in
relation to various outcomes as part of the internal cohort comparisons. For noncancer
outcomes, no dose-response associations with TCDD were observed with the internal
comparisons. Also, as found with earlier analyses of this same cohort, no excess noncancer
mortality relative to the New Zealand general population was observed.

Associations between TCDD and diabetes have been found previously in TCDD-exposed
populations, most notably in the Ranch Hands cohort (Michalek and Pavuk, 2008, 199573). In
this cohort, only five deaths from diabetes were identified, and of these, only three occurred
among those who were exposed to TCDD. The study, therefore, has limited statistical power to
characterize associations between TCDD and mortality from diabetes. Further, the identification
of diabetes deaths is subject to misclassification errors due to under-reporting (McEwen and
TRIAD, 2006, 594400).

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2.4.1.2.1.8.4.3. Suitability of data for TCDD dose-response modeling.

McBride et al. (2009, 197296)) found no statistically significant associations in any of the
noncancer causes of death. Furthermore, the use of mortality endpoints is inconsistent with EPA
RfD methodology. Therefore, the data were not suitable for quantitative dose-response analysis
for these outcomes.

2.4.1.2.2. Feasibility of dose-response modeling for noncancer.

Relatively few study populations permit quantitative dose-response modeling to be
performed for noncancer outcomes. The serum collected among Seveso men and women
provide an opportunity to characterize risks for several health conditions in relation to TCDD
exposure. The collection of these serum samples, shortly after the accident does not require the
back-extrapolation of TCDD levels as in the occupational cohorts, which should reduce the
exposure assessment uncertainty and minimize the potential for exposure misclassification.

An added feature of the SWHS is the detailed collection of other risk factor data from
trained interviewers. These data allow for risk estimates to be adjusted for potential confounding
variables. For the evaluations of reproductive health outcomes, this adjustment is critical given
there are various documented risk factors for the different outcomes that were examined. For
some health outcomes, continued follow-up of the cohort is needed, given that several of the
Seveso studies suggest that those exposed at a very young age might be more susceptible to
subsequent adverse health effects.

The findings of positive associations and dose-response relationships with serum-based
measures of TCDD suggest several noncancer health outcomes could be associated with TCDD
exposure. These health outcomes include neonatal thyroid function, sex ratio, diabetes, and
semen quality. Although findings have suggested an association between TCDD and age at
menopause, they were not statistically significant and no dose-response trend was observed.
Weak or nonstatistically significant associations have been noted for endometriosis and
menstrual cycle characteristics and do not support quantitative dose-response analyses.

Associations between TCDD exposure and cardiovascular disease have been noted in
some, but not all, of the occupational cohorts, and also shortly after the accident among Seveso
residents. Findings from the cohort studies based on external comparisons using the SMR
statistic should be interpreted cautiously due to potential bias from the healthy worker effect.

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Because the magnitude of the healthy worker bias is recognized to be larger for cardiovascular
diseases than for cancer outcomes, risk estimates in some occupational cohorts might be
underestimated for cardiovascular outcomes. Information on cardiovascular risk factors
generally was not captured in these studies, and sensitivity analyses were generally designed to
examine risk estimates generated for cancer outcomes.

2.4.1.2.3. Summary of epidemiologic noncattcer study evaluations for dose-response
modeling.

All epidemiologic noncancer studies summarized above were evaluated for suitability of
quantitative dose-response assessment using the TCDD-specific considerations and study
inclusion criteria. The results of this evaluation are summarized in a matrix style array (see
Table 2-3) at the end of the chapter, and descriptively in Appendix B. The key epidemiologic
noncancer studies suitable for further TCDD dose-response assessment are presented in
Table 2-5.

2.4.2. Summary of Animal Bioassay Studies Included for TCDD Dose-Response Modeling

This section summarizes studies that have already met the in vivo animal bioassay TCDD
study inclusion criteria (see Section 2.3.2). These studies are listed later in this section in
Tables 2-6 and 2-7, for cancer and noncancer, respectively, and are considered in the
dose-response modeling conducted later in this document (see Sections 4 and 5). The following
sections are organized by reproductive studies, developmental studies, and general toxicity
studies (subdivided by duration). They summarize the experimental protocol, the results, and the
NOAELs and LOAELs EPA has identified for each study.

To evaluate and discuss studies consistently, doses were converted to nanograms per
kilogram body weight per day (ng/kg-day) and were also adjusted for continuous exposure.

Some doses were adjusted based on daily dietary intake and body weight. For these studies,
EPA uses 10% of an animal's body weight as the daily feed rate. More commonly, doses were
adjusted from 5 days/week to a 7 days/week standard adjustment, in which case administered
doses were multiplied by 5 and divided by 7 to obtain continuous doses. To adjust for weekly
dosing, the weekly administered doses were multiplied by the administration frequency per week
(in days) and divided by 7 to give continuous doses.

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Other exposure protocols used a single loading dose followed by weekly maintenance
doses. To adjust these doses, the loading dose was added to the maintenance doses multiplied by
the administration frequency, and this sum was divided by the exposure duration to give a
continuous dosing rate. The doses administered in single dose studies were not averaged over
the observation period.

2.4.2.1. Reproductive Studies

2.4.2.1.1. Bowman et al (1989, 543744; 1989, 543745) (and related Schantz and Bowman
(1989, 198104): Schantz et al (1986, 088206)).

Female rhesus monkeys (6 to 10 years old; 8 per treatment) were exposed to 0 or 5 ppt
(for 3.5 years), or 25 ppt (for 4 years) TCDD (purity not specified) (Bowman et al., 1989,

543744; Bowman et al., 1989, 543745; Schantz and Bowman, 1989, 198104; Schantz et al.,
1986, 088206). Female monkeys were mated to unexposed males after 7 months (Cohort I) and
27 months (Cohort II) of exposure, then again 10 months postexposure (Cohort III). The average
daily doses to mothers were equivalent to 0, 0.15, and 0.67 ng/kg-day. The 0.67 ng/kg-day dose
group had reduced reproductive rates in both Cohorts I (p < 0.001) and II (p < 0.025; Bowman
et al., 1989, 543744). The mean number of days of offspring survival (p < 0.023) also decreased.
No effects on birth weight or growth, or physical evidence of toxicity (Bowman et al., 1989,
543745) were observed. Behavioral effects were observed in the offspring (Cohort I: 7, 6, and
0 offspring, respectively; Cohort II: 3, 5, and 0 offspring, respectively; Cohort III: 6, 7, and 3,
respectively). In the 0.67 ng/kg-day dose group, the number of offspring was insufficient to
form a group in either Cohorts I or II. Offspring in the 0.15 ng/kg-day dose group had alterations
in social behavior of the mother-infant pairs (mothers had increased care giving, which appeared
to be an effect of the infants and not due to the treatment of the mother) and peer group of the
offspring after weaning (Cohort I offspring were more dominant or aggressive and exhibited
more self-directed behavior; Bowman et al., 1989, 543745). The performance of learning tasks
was inversely related to the level of TCDD in the body fat. Schantz and Bowman (1989,

198104) examined effects using discrimination-reversal learning (RL) and delayed spatial
alteration (DSA). RL detected effects in the 0.15 ng/kg-day group as measured by retarded
learning of the shape reversal (p < 0.05), but DSA did not. Schantz et al. (1986, 088206)
combined the cohorts and looked at 5, 5, and 3 mother-infant pairs in the 0, 0.15, and

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0.67 ng/kg-day groups, respectively. They found that TCDD-exposed mother-infant pairs spent
more time in close, social contact compared to the controls (mutual ventral contact,/* < 0.025;
nipple contact,/* < 0.01) and infants had reduced locomotor activity (p < 0.05), but the
dose-effect was complex. Of note is that the control groups contained fewer males than did the
TCDD-exposed groups.

In a follow-up study, Rier et al. (2001, 199843) examined the DLC levels of sera
collected from some monkeys in this study. They reported that animals in this study had
elevated serum PCB77 and PCB126 levels and an increased serum TEQ. In fact, the fractional
contribution of serum TCDD levels to total serum TEQ was 30% in treated animals. In this
study, it is not possible to determine the contribution of TCDD alone to the developmental effect
due to the background contamination; thus, EPA has not developed a TCDD LOAEL from the
study.

2.4.2.1.2. Franc et al. (2001,197353).

To study the effects of subchronic, low-dose exposure to TCDD on the regulation and
expression of the aryl hydrocarbon receptor (AhR), Franc et al. (2001, 197353) used rodent
models with varying sensitivities to TCDD. Female Sprague-Dawley rats, inbred Long-Evans
rats, and outbred Han/Wistar rats (8 per dose group) were dosed via oral gavage with 0, 140,
420, or 1,400 ng/kg TCDD (>99% purity) dissolved in corn oil once every 2 weeks for 22 weeks
(0, 10, 30, and 100 ng/kg-day average daily doses). Animals were sacrificed 10 days after the
final dosing. Body weights were recorded biweekly and just before sacrifice. After sacrifice,
liver and thymus weights were determined. Liver tissue samples were removed and either frozen
for RNA isolation followed by semiquantitative RT-PCR or homogenized and prepared for
subcellular fraction analysis. Radioligand binding and immunoblotting techniques were used to
measure AhR levels, and RT-PCR analysis was used to assess mRNA levels of AhR, aryl
hydrocarbon nuclear receptor (ARNT), and CYP1A1.

Long-Evans rats exhibited significant (p < 0.001) decreased weight gain over time as
compared to Sprague-Dawley and Han/Wistar rats as determined by repeated measures analysis
of variance (ANOVA). Because body weight gain varied indirectly with TCDD exposure, liver
and thymus tissue weights were normalized to body weight for data analysis. TCDD exposure
led to a significant (p < 0.05) increase in relative liver weights at all three TCDD doses and in all

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three rat strains, compared to the control groups. At the upper end of the TCDD dose range,
Sprague-Dawley rats dosed with 100 ng/kg-day showed the greatest increase in relative liver
weights (160% of the control values), while relative liver weights in Long-Evans and Han/Wistar
rats were similar to each other, and also were elevated above control values by 10-20%. At the
30 and 100 ng/kg-day doses, the relative thymus weights were significantly lower (p < 0.05) in
all rat strains compared to their corresponding controls, but the 10 ng/kg-day dose did not
produce a statistically significant effect in any strain. However, absolute thymus weight was
higher at all doses in Han/Wistar rats, which also had a higher control thymus weight.

Supporting observed differences in baseline TCDD sensitivity among the rat strains, liver
AhR levels in the control groups as measured by radioligand binding were similar for Sprague
Dawley and Han/Wistar rats, but were approximately two-fold higher for Long-Evans rats. A
significant (p < 0.05) two-fold, dose-dependent increase in radioligand binding of liver AhR was
observed at all TCDD doses relative to the control in Sprague-Dawley rats. At the 30 ng/kg-day
dose, the AhR level for Long-Evans rats was significantly (p < 0.05) increased to approximately
250% of the control level.

AhR protein levels measured in the liver cytosol by immunoblotting were highest in the
10 and 30 ng/kg-day TCDD dose groups for all three rat strains. Significant (p < 0.05) increases
in AhR levels were observed in the Sprague-Dawley rats that received 30 ng/kg-day, and in
Long-Evans rats that received either 10 or 30 ng/kg-day. A significant (p < 0.05) decrease in
AhR protein level was observed only at the 100 ng/kg-day dose in Han/Wistar rats. Liver AhR
protein was not detectable by immunoblotting in nuclear extracts for any strain or dose. The
study authors assert that AhR levels measured in cytosol correspond to measures in whole-tissue
lysates as demonstrated in their previous work.

Based on RT-PCR analysis, all three rat strains showed similar responses in liver AhR
mRNA following TCDD exposure. Liver AhR mRNA levels increased significantly (p < 0.05)
as compared to control levels in all rat strains at 10 and 30 ng/kg-day and in Long-Evans rats at
100 ng/kg-day. The study authors observed that statistically significant increases in AhR mRNA
levels in the liver were not always associated with statistically significant increases in AhR levels
for a given strain and dose, but that the opposite (increases in AhR levels associated with
increases in AhR mRNA levels) was always true. Changes in liver ARNT mRNA levels tended
to increase with increasing TCDD dose, and the increases were significant (p < 0.05) in the

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30 ng/kg-day dose groups of Long-Evans and Han/Wi star rats. At the 100 ng/kg-day TCDD
dose, all rat strains showed a decrease in ARNT mRNA in the liver relative to controls with
significant (p < 0.05) differences for the 100 ng/kg-day TCDD dose groups of Sprague-Dawley
and Han/Wistar rats. Liver CYP1A1 mRNA induction was not detectable in control animals. A
significant (p < 0.05) increase in liver CYP1A1 mRNA was observed in all rat strains
administered 10 or 30 ng/kg-day TCDD. Liver CYP1A1 mRNA levels also were significantly
(p < 0.05) elevated above controls in the 100 ng/kg-day groups although not to the same extent
as in the 30 ng/kg-day groups. For all rat strains, the largest up-regulation for AhR and ARNT
mRNA levels occurred in the 30 ng/kg-day TCDD dose groups.

The NOAEL for TCDD identified in this study is 10 ng/kg-day TCDD. At 10 ng/kg-day
TCDD, the change in relative liver weight, while significantly (p < 0.05) increased in
Sprague-Dawley rats, was determined (from Figure 5 in Franc et al., 2001, 197353) to be less
than 10% and judged by EPA not to be biologically relevant. Also, at 10 ng/kg-day TCDD, the
change in relative thymus weight, was not statistically significantly decreased in
Sprague-Dawley, Han-Wistar or Long-Evans rats. The study LOAEL is 30 ng/kg-day, based on
statistically and biologically significant increases in relative liver weight in Sprague-Dawley and
Long-Evans rats and statistically and biologically significant decreases in relative thymus weight
in Sprague-Dawley, Han-Wistar and Long-Evans rats.

2.4.2.1.3. Hochstein et al. (2001,197544).

Adult female mink (12/treatment group) were administered dietary concentrations of
0.0006 (control), 0.016, 0.053, 0.180, or 1.40 ppb TCDD (purity >99.8%) for 132 days
(Hochstein et al., 2001, 197544). This dose is estimated to be equivalent to 0.03 (control), 0.8,
2.65, 9, and 70 ng/kg-day assuming a food consumption of 5% of body weight per day. Females
were mated with unexposed males beginning on treatment day 35. Females were allowed to
mate every fourth day during a 29-day mating period or until a confirmed mating. Mated
females were presented with a second male either the day after initial mating or 8 days later. In
the 70 ng/kg-day group, the treated animals were lethargic after 4 to 5 weeks, with several
having bloody (tarry) stools near the end of the trial. Two animals in the 70 ng/kg-day dose
group died prior to study termination. These animals had lost a large percentage of their body
weight (24-43%), and had pale yellow livers and intestinal hemorrhages. Histopathology from

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both mink indicated marked diffuse hepatocellular vacuolation. The mean body weight
decreased in all treatment groups including the control (losing an average of 3.29% of initial
body weight), compared to a dose-dependent loss of up to 26% in the 70 ng/kg-day group.
Mating and reproduction were considered subnormal in all groups. The number of females that
gave birth in the 0.03 (control), 0.8, 2.65, 9, and 70 ng/kg-day dose groups were 5/12, 0/12, 3/12,
8/12, and 0/11, respectively. The study authors speculated that the subnormal breeding and
reproductive performances in the control females likely were due to the indoor environment in
which the mink were housed. In the three groups that gave birth, there was a dose-dependent
decrease in kit body weight at birth, which was significant (p < 0.05) in the 9 mg/kg-day group
compared to the controls. The body weight in the kits was not significantly different at 3 or
6 weeks after birth. Three-week survival rates of 71, 47, and 11% were recorded for kits in the
0.03 (control), 2.65, and 9 ng/kg-day dose groups, respectively. Six-week kit survival rates were
62, 29, and 11% in the 0.03 (control), 2.65, and 9 ng/kg-day dose groups, respectively.

In the adult females, clinical signs of toxicity were noted in the 70 ng/kg-day group near
the end of the study and included alopecia and notably thickened, deformed, and elongated
toenails. There was a dose-dependent decrease in plasma total solids, total protein, and
osmolality that reached statistical significance (p < 0.05) in the two highest exposure groups.
Anion gap was significantly decreased (p < 0.05) and alanine aminotranferase was significantly
increased in the 70 ng/kg-day group compared to the controls. At terminal sacrifice, there was a
dose-related decrease in body weight. There was a dose-related increase in liver weight that
reached statistical significance (p < 0.05) in the 70 ng/kg-day dose group. The brains of 42% of
the animals in the 70 ng/kg-day dose group had localized accumulation of lymphatic cells within
the meninges with mild extension into the adjacent neuropil and mild gliosis. Of the 10 mink
surviving to study termination in the 70 ng/kg-day group, 3 had periportal hepatocellular
vacuolation. These same brain and liver lesions were not observed in the control mink.

As there were no litters produced in the low-dose group and pregnancy outcomes were
not dose related, the 0.8 ng/kg-day exposure level does not inform the choice of NOAEL or
LOAEL. Thus, the LOAEL for this study is 2.65 ng/kg-day (132-day maternal exposure
duration) based on reduced kit survival (47% of control at 6 weeks). A NOAEL cannot be
determined for this study.

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2.4.2.1.4.	Hutt et al. (2008.198268).

Hutt et al. (2008, 198268) conducted a 3-month study investigating changes in
morphology and morphogenesis of pre-implantation embryos as a result of chronic exposure to
TCDD in female rats. The study authors administered 0 or 50 ng/kg TCDD (>99% purity) in
corn oil via oral gavage to groups of 3 pregnant Sprague-Dawley rats on gestation days 14 and
21 and on postnatal days 7 and 14. The resulting female pups were divided into groups of 3 and
administered 0 or 50 ng/kg TCDD (>99% purity) in corn oil (equivalent TCDD doses of 0 and
7.14 ng/kg-day) on postnatal day 21 and weekly thereafter until they reached 3 months of age.
Pups were then mated, fertilization was verified, and pre-implantation embryos were harvested
4.5 days later. Pre-implantation embryos were examined using immunofluorescence microscopy
to determine blastomere abnormalities.

No significant difference as compared to the control in pre-implantation embryotoxicity
was observed following exposure to TCDD. Morphologically normal pre-implantation embryos
were significantly (p < 0.05) reduced in 50 ng/kg TCDD exposed rats (15 of 41, 36.6%)
compared to the control group (31 of 39,19.5%). Pre-implantation embryos of TCDD-exposed
rats included irregularities in mitotic spindles (13 of 18 were monopolar), chromosome patterns
in metaphase, blastomere size and shape, blastomere nuclei shape in interphase, f-actin, and
cytokinesis. The study authors concluded that the compaction stage of pre-implantation
embryogenesis is the most sensitive following exposure to TCDD.

A LOAEL for this study is 50 ng/kg (7.14 ng/kg-day adjusted dose) for a significantly
(p < 0.05) lower proportion of morphologically normal pre-implantation embryos during
compaction stage in female Sprague-Dawley pups weekly for 3 months. A NOAEL cannot be
determined for this study.

2.4.2.1.5.	Ikeda et al. (2005,197834).

Ikeda et al. (2005, 197834) studied the effect of repeated TCDD exposure to F0 dams on
the male gonads of F1 generation and sex ratio in the F2 generation. Twelve female Holtzman
rats were treated with a single dose of 400 ng/kg TCDD (>98% purity) orally, via gavage,
followed by weekly treatment doses of 80 ng/kg TCDD (16.5 ng/kg-day adjusted for continuous
exposure of 10 weeks; specified 2 weeks premating, assumed 1 week for successful mating,
3 weeks of gestation, and specified 4 weeks to weaning) during mating, pregnancy, and

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lactational periods (total exposure duration approximately 10 weeks). Corn oil served as the
control in another group of 12 dams. Four dams were sacrificed on gestation day (GD) 20 to
evaluate the in utero toxicity of TCDD. Litter sizes from the remaining eight dams were
examined on postnatal day (PND) 2, and some of the F1 offspring were sacrificed to estimate
TCDD tissue concentrations. The remaining offspring were weaned on PND 28. Some of the F1
(number not specified) offspring were mated with untreated females on PND 98, following
which, litter size, sex ratio, weight, and anogenital distance of F2 pups were examined on
PND 2. Mated and unmated F1 males were sacrificed and the testes, epididymis, seminal
vesicle, and the ventral prostate were weighed; the cauda epididymis was weighed and examined
for sperm count.

All fetuses in the control and TCDD group as a result of in utero exposure in the
F0 generation survived. Litter size, sex ratio, and anogenital distance in the F1 generation on
PND 2 were not altered as a result of in utero TCDD exposure. Pup weight was significantly
(p < 0.05) lower in the TCDD-treated group than in controls. TCDD concentration in the
adipose tissue of the F0 dams on GD 20 was significantly (p < 0.05) higher than in the liver.
Adipose TCDD was significantly (p < 0.01) reduced at weaning, however, compared to
concentrations on GD 20. F1 pup liver TCDD concentration increased significantly (p < 0.01)
and was higher on PND 28 than PND2. The liver weight in F1 males increased by 14-fold at
PND 28 compared to PND 2, implying a transfer of approximately 850 pg of TCDD from the
dam to the F1 pup livers during lactation. TCDD also was detected in pup adipose tissue on
PND 28. Body weight of TCDD-exposed F1 males was significantly (p < 0.001) lower than
control males at weaning (PND 28). No significant differences in testis and cauda epididymis
weights were observed between the control and treated groups. Ventral prostate weight in the
F1 males exposed to TCDD, however, was approximately 60% lower than controls. No change
in weight of the body, brain, testes, cauda epididymis, or seminal vesicle was observed at
PND 120. Ventral prostate weight, however, was 16% lower than that of the control group
(p < 0.001). Sperm count in the cauda epididymis of the F1 males was not affected by TCDD
exposure.

Examination of F2 generation litters indicated no significant differences in litter size, pup
body weight, and anogenital distance between TCDD-treated or vehicle control groups. The
percentage of male F2 pups born to maternally and lactationally TCDD-exposed males was

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significantly (p < 0.05) lower (38%) than those sired by control group males (52%). Every
female mated with maternally TCDD-exposed F1 males delivered more female than male pups.

A LOAEL for TCDD of 16.5 ng/kg-day for an estimated 10 week exposure duration in
F0 rat dams is identified in this study for decreased development of the ventral prostate in the
F1 generation (60% lower than controls) and for significantly (p < 0.05) altered sex ratio
(decreased percentage of males) in the F2 generation. A NOAEL cannot be determined for this
study.

2.4.2.1.6. Ishihara et al. (2007, 197677).

Ishihara et al. (2007, 197677) examined the effect of repeated TCDD exposure of
F0 males on the sex ratio of F1 offspring. Seven-week-old male ICR mice (n = 127) were
divided into three groups and treated via gastric intubation with an initial loading dose of either 2
or 2,000 ng TCDD/kg BW or an equivalent volume of sesame oil (vehicle) as control, followed
by a weekly maintenance doses of 0, 0.4, or 400 ng/kg until the animals were 12 weeks old.
One week after the last exposure, the animals were mated with untreated female mice. On the
day a vaginal plug was identified, F0 male mice were sacrificed and major organs including
testes, epididymis, and liver were removed and weighed. Organ tissues also were examined for
histopathological and immunohistochemical changes. Treatment levels, averaged over the
6 week period from start of treatment to mating (five maintenance doses), were 0, 0.095, and
950 ng/kg-day for the control, low dose and high dose groups, respectively.

All TCDD-treated males successfully impregnated untreated females and yielded viable
offspring. Mortality, pup weights, and mating and fertility indices were not affected by TCDD
exposure. There were no significant differences in body weights or in relative weights of testes,
epididymis, or livers in the TCDD-treated F0 males compared to the control group. The livers of
some animals (number not specified) in the high-dose group, however, were larger and heavier
than in the controls or the low-dose group. Hence, tissues from the high-dose animals were
selected for detailed immunohistochemical examination.

General histopathological findings in the TCDD-treated groups showed no changes in
cell morphology in germ, Sertoli, and Leydig cells of the testes. Arrangement of the germ cells
was normal and there was no difference in the epididymis spermatozoon number in either of the
TCDD-treated groups compared to controls. Livers of some of the animals in the high-dose

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group however, showed enlarged and vacuolated areas in the centrilobular area when compared
to the low-dose group and the control group. Immunohistochemical and quantitative
immunohistological findings showed a marked increase in staining intensity for cytochrome
P450 (CYP)l A1 in the cytoplasm of the hepatocytes in the centrilobular area of the high-dose
TCDD group compared to the cells in the low-dose and the control groups. In addition,
proportions of immunoreactive CYP1A1 areas in the liver sections of the high-dose group were
higher than in the low-dose and control groups. The proportions of immunoreactive CYP1A1
also varied across animals (n = 33) in the high-dose group.

In addition to the above findings, there was a dose-related decrease in the male/female
sex ratio. The proportion of male offspring of the high-dose group was significantly lower
(p < 0.05) than that observed in controls (46.2% versus 53.1%, respectively). Hepatic
immunoreactive CYP1A1 staining levels in individual F0 males were strongly correlated with
the sex ratio of their offspring.

A LOAEL for TCDD of 950 ng/kg-day for a 6 week exposure duration of F0 male mice
is identified for significantly (p < 0.05) decreased male/female sex ratio (i.e., higher proportion
of female offspring) in the F1 generation. The NOAEL is 0.095 ng/kg-day.

2.4.2.1.7. Latchoumyclindane and Muthur (2002,197498) (and related: Latchoumycandane
et al. (2002,198365: 2002,197839: 2003, 543746)).

Latchoumycandane and Mathur (2002, 197498) conducted a study to determine whether
treatment with vitamin E protected rat testes from TCDD-induced oxidative stress. Groups of
albino male Wistar rats (n = 6) were administered an oral dose of 0 (vehicle alone) 1, 10, or
100 ng TCDD/kg-day for 45 days, while another group of animals (n = 6) was co-administered
TCDD at the same doses, along with vitamin E at a therapeutic dose of 20 mg/kg-day for
45 days. At study termination, animals were fasted overnight, weighed, and sacrificed. Testis,
epididymis, seminal vesicles, and ventral prostate were removed, weighed, and preserved for
further examination. The left testis was used to determine daily sperm production, while the
right testis was used for biochemical studies. Superoxide dismutase, catalase, glutathione
reductase, and glutathione peroxidase activity were measured in the testes, along with production
of hydrogen peroxide and lipid peroxidation.

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Body weights of TCDD-treated rats did not differ significantly from the control group.
Testis, epididymis, seminal vesicle, and ventral prostate weights in the TCDD-treated groups,
however, decreased significantly (p < 0.05) when compared to controls. None of these changes
were observed in the TCDD-exposed groups receiving vitamin E. There was a dose-related
decrease in daily sperm production (p < 0.05) in all three TCDD-treated groups when compared
to the control group. In contrast, the TCDD treatment groups that also received vitamin E did
not show any significant changes in daily sperm production compared to the controls. The
TCDD-treated groups also showed significantly (p < 0.05) lower activities of the antioxidant
enzymes (superoxide dismutase, catalase, glutathione reductase, and glutathione peroxidase) than
the control group. Levels of hydrogen peroxide and lipid peroxidation increased significantly
(p < 0.05) in the testes of the rats treated with TCDD compared to the corresponding controls.
The TCDD-treated groups that had been co-administered vitamin E show no difference in
antioxidant enzyme activities or in reactive oxygen species production when compared with
controls.

A LOAEL for TCDD of 1.0 ng/kg-day for a 45-day exposure duration in rats is identified
in this study for significantly (p < 0.05) reduced sperm production and significantly (p < 0.05)
decreased reproductive organ weights. A NOAEL cannot be determined for this study.

2.4.2.1.8. Murray et al. (1979,197983).

Male (10-16 per treatment) and female (20-32 per treatment) Sprague-Dawley rats were
administered diets containing TCDD (purity >99%) to achieve daily concentrations of 1, 10, or
100 ng/kg-day through three generations. After 90 days of treatment, F0 rats were mated to
produce Fla offspring. Thirty-three days after weaning of the last F la litter, the F0 rats were
mated again to produce Fib offspring. Some F0 rats were mated a third time for a cross-mating
study. The Fib and F2 rats were mated at about 130 days of age to produce the F2 and
F3 generations. No clinical signs of toxicity or changes in body weight and food consumption
were observed in F0 rats during the 90 days of treatment before mating. The 100 ng/kg-day
group was discontinued due to the lack of offspring. In the three surviving offspring (all males),
no changes in appearance, body weight, or food consumption occurred. A dose of 10 ng/kg-day
caused a consistent decreased body weight in both sexes of F1 and F2 rats, which was associated
with decreased food consumption. A significant (p < 0.05) decrease in fertility in F1 and F2 rats

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occurred, but not in F0 rats, administered 10 ng/kg-day. The number of live pups and gestational
survival index were significantly (p < 0.05) decreased in the 100 ng/kg-day F0 rats and in the
10 ng/kg-day F1 and F2 rats. The gestational survival index also was significantly (p < 0.05)
decreased in F2 rats administered 1 ng/kg-day. Postnatal survival was significantly (p < 0.05)
reduced only in F2 rats administered 10 ng/kg-day. Growth (as measured by body weight) was
affected at 10 ng/kg-day only in the third generation. In the 10 ng/kg-day group, a significant
(p < 0.05) decrease in relative thymus weight and increase in liver weight also occurred in F3 rats
(weights were not measured in F2 rats). Additionally, mating 100 ng/kg-day TCDD-treated
females with untreated males increased the percent of implants resorbed as assessed by uterine
histopathology.

The reproductive LOAEL is 10 ng/kg-day, based on a significant (p < 0.05) decrease in
fertility (33-37% lower than controls); decrease in the number of live pups (18-27% lower than
controls); decrease in gestational survival (10-11% lower than controls); decrease in postnatal
survival (32% lower than controls); and decreased postnatal body weight (14—19% lower than
controls at weaning) in one or more generations. The reproductive NOAEL is 1 ng/kg-day.

2.4.2.1.9. Rier et al (1993,199987:1995,198566).

Reir et al. (1993, 199987; 1995, 198566) examined the impact of chronic TCDD
exposure on endometriosis in monkeys. Female rhesus monkeys (eight animals per treatment
group) were exposed to 0, 5, or 25 ppt TCDD (purity not specified) in feed for 4 years.
Previously, Bowman et al. (1989, 543745) determined that these dietary concentrations were
equivalent to 0, 0.15, and 0.67 ng/kg-day, respectively. Ten years after termination of TCDD
treatment, the presence of endometriosis was determined via laparoscopic surgical procedure,
and the severity of the disease was assessed. The study authors reported that three monkeys in
the 0.67 ng/kg-day exposure group died at 7, 9, and 10 years after termination of TCDD
treatment. Autopsy results attributed the deaths to widespread and severe peritoneal
endometriosis (all three monkeys) along with obstruction of the colon (one monkey) and
blockage of the jejunum (one monkey). Other deaths also occurred in the control group (1 death
from birthing complications and another from an unknown cause); in the 0.15 ng/kg-day dose
group (1 death due to natural causes with no endometriosis), and in the 0.67 ng/kg-day dose
group (1 death due to a breeding fight with no incidence of endometriosis). At study

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termination, 17 live animals plus the 3 that had previously died of endometriosis were evaluated
(total n = 20).

Incidence of endometriosis was significantly (p < 0.05) higher than in the control group
with 71 and 86 % incidence rates in the 0.15 and 0.67 ng/kg-day dose groups, respectively,
compared to 33% in the control group. Severity of endometriosis was also significantly
(p < 0.001) correlated with TCDD dose. Staging by rAFS indicated that untreated control
animals had either minimal or no incidence of endometriosis. In comparison, endometriosis was
absent in 2 of the 7 monkeys in the 0.15 ng/kg-day dose group, while only 1 of the 7 animals in
the high dose group was disease free. Moderate-to-severe disease was observed in 3 of the
7 animals in the 0.15 ng/kg-day dose group and 5 of the 7 animals in the 0.67 ng/kg-day dose
group. Moderate-to-severe disease was not observed in the control group. The authors also
compared the incidence and severity of endometriosis in TCDD-exposed animals with
304 normal, non-neutered females with no dioxin exposure and reported that the disease was not
present in monkeys that were less than 13 years of age, while the disease rate was 30% among
animals 13 years of age or older. The study authors report that these findings are in agreement
with human and rhesus studies demonstrating that the prevalence of detectable endometriosis can
increase with advanced age.

As noted previously, in a follow-up study, Rier et al. (2001, 198776) examined the DLC
levels of sera collected from some monkeys in this study. They reported that animals in this
study had elevated serum PCB77 and PCB126 levels and an increased serum TEQ; the fractional
contribution of serum TCDD levels to total serum TEQ was 30% in treated animals. They also
reported that the severity of the endometriosis corresponded to the serum PCB77 concentrations
rather than total TCDD. In this study, it is not possible to determine the contribution of TCDD
alone to the endometriosis due to the background contamination; thus, EPA has not developed a
TCDD LOAEL from the study.

2.4.2.1.10. Shi et al (2007,198147).

Pregnant Sprague-Dawley rat dams (3 per treatment group) were administered 0, 1,5, 50,
or 200 ng/kg TCDD (purity >99%) in corn oil by gavage on GD 14 and GD 21 and on PND 7
and PND 14 for lactational exposure to pups (Shi et al., 2007, 198147). Ten female pups per
treatment were selected and administered TCDD weekly at the same dose levels through their

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reproductive lifespan (approximately 11 months). The corresponding equivalent daily TCDD
doses are 0, 0.14, 0.71, 7.14, and 28.6 ng/kg-day. Vaginal opening was slightly but significantly
(p < 0.05) delayed in 28.6 ng/kg-day females. Vaginal opening was also delayed, but not
significantly, in the 0.14 and 7.14 ng/kg-day groups. Reproductive senescence with normal
cyclicity was significantly (p < 0.05) accelerated beginning at 9 months in 7.14 and
28.6 ng/kg-day females. Serum estradiol concentrations were decreased at all time points across
the estrous cycle in a dose-dependent manner with a statistically significant decrease (p < 0.05)
in all but the lowest dose group. TCDD exposure, however, did not affect the number or size
distribution of ovarian follicles; responsiveness of the pituitary gland to gonadotropin-releasing
hormone, or serum profiles of FSH, LH, or progesterone.

A LOAEL for TCDD of 0.71 ng/kg-day for an 11-month exposure duration was
identified in this study based on significantly (p < 0.05) decreased estradiol levels in offspring.
The NOAEL for this study is 0.14 ng/kg-day.

2.4.2.1.11. Yangetal. (2000,198590).

Yang et al. (2000, 198590) studied the impact of TCDD exposure on the incidence and
severity of endometriosis in female rhesus monkeys. Groups of 7- to 10-year old nulliparous
cynomolgus monkeys were treated with 0 (n = 5), 1, 5, or 25 (n = 6 per group) ng/kg BW TCDD
5 days per week via gelatin capsules for 12 months. Because the monkeys received one capsule
5 days per week, the doses adjusted for continuous exposure were 0, 0.71, 3.57, and
17.86 ng/kg-day. Prior to TCDD administration, all animals had endometriosis induced during
days 12-14 of the menstrual cycle by auto-transplantation of endometrial-strips in multiple
abdominal sites. All TCDD-treated and control groups were laparoscopically examined during
months 1,3, and 6 to monitor the survival of endometrial implantations and to obtain peritoneal
fluid to determine the concentration and immunotype of endometrial growth regulator cytokines
interleukin-6 (IL-6) and interleukin-6 soluble receptor (IL-6sR). Because insufficient peritoneal
fluids were present in the treated and control monkeys, however, the study authors collected
blood samples at 6 and 12 months during laparoscopy for routine hematology and to assess the
circulating levels of IL-6 and IL-6sR. All animals were sacrificed at 12 months, and circulating
levels of gonadal steroids also were measured at the time of necropsy.

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No changes were observed among treatment levels in general toxicological endpoints
such as body weight changes, food consumption, hematological endpoints, general activity
levels, and caretaker interaction. In addition, TCDD did not impact circulating levels of gonadal
steroids measured during necropsy. Similarly, there were no differences in the number of
menstrual cycles, the length of the menstrual cycle, and bleeding intervals. Endometrial implants
were found in at least one site in all TCDD-treated and control monkeys during the
first laparoscopic examination. Follow-up laparoscopies revealed that there was a continuous
loss of endometrial implants over time in each dose group. At the 1-, 3-, and 6-month
examination, the number of endometrial losses was not significantly different among different
dose groups. At the 12-month examination, however, a significantly (p < 0.05) higher rate of
survival of endometrial implants was observed in the 3.57 and 17.86 ng/kg-day dose groups
compared to the control group. The highest rate of endometrial implant survival was observed in
the ovaries regardless of the dose group. In contrast, all lesions disappeared from the left broad
ligament, whereas two on the right broad ligament and one on the uterine fundus survived.

There was a dose-dependent divergence in the growth response of endometrial implants
following TCDD exposure. Both the maximum and minimum implant diameters in the
17.86 ng/kg-day dose group were significantly (p < 0.05) larger compared to controls. In
contrast, the maximum and minimum implant diameters in the 0.71 ng/kg-day dose group were
significantly (p < 0.05) smaller compared to controls. TCDD did not impact implant diameters
in the 3.57 ng/kg-day dose group when compared to controls. Histological examinations
revealed that endometrial glands and stromal cells were present in all surviving implants.

Sections examined in the 17.86 ng/kg-day of TCDD possessed cystic endometrial glands that
were more frequently observed in this dose group compared to other groups including controls.
In addition, circulating levels of IL-6 were significantly (p < 0.05) lower in monkeys exposed to
17.86 ng/kg-day TCDD both at 6 and 12 months compared to the control group. In contrast,
circulating levels of IL-6sR were significantly (p < 0.05) higher in animals treated with 3.57 and
17.86 ng/kg-day TCDD at 6 months, while the levels were higher only in the 17.86 ng/kg-day
TCDD group at 12 months.

A LOAEL for TCDD of 17.86 ng/kg-day for a 1 year exposure duration was identified in
this study for significantly (p < 0.05) increased endometriosis induced by endometrial implant
survival, significantly (p < 0.05) increased maximum and minimum implant diameters, and

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growth regulatory cytokine dysregulation (as assessed by significantly decreased IL-6 levels,
p < 0.05). ANOAEL of 3.57 ng/kg-day is identified in this study.

2.4.2.2. Developmental Studies
2.4.2.2.1. Amin et al. (2000,197169).

Am in et al. (2000, 197169) studied the impact of in-utero TCDD exposure on the
reproductive behavior in male pups. Groups of pregnant Harlan Sprague-Dawley rats (n = 108
divided into 4 cohorts; number of animals in the TCDD treatment group is ~3 per dose group)
were dosed via gavage with 0, 25, or 100 ng/kg-day TCDD (purity >98%) in corn oil on GDs
10-16. On the day of birth (PND 0), pups were examined for gross abnormalities and the
number of live pups, their weights, and sex were recorded from each litter. Litters consisting of
more than eight pups were reduced to eight, comprised of four males and four females when
possible. Litters consisting of fewer than five pups were excluded from the study to minimize
between-litter differences in growth rate, maternal behavior, and lactational exposure. After this
exclusion, approximately 10 to 11 litters per exposure group remained. All pups were weaned
on day 21 and one male and one female were retained to assess reproductive development, play
behavior, reproductive behavior, and saccharin preference behavior. Both male and female pups
were tested for saccharin preference between 189 and 234 days of age. A saccharin preference
test was conducted for 8 days. For the first 4 days, rats were provided bottles containing tap
water, and on days 5 and 6 the animals were provided a bottle containing water and a bottle
containing 0.25% saccharin solution. On days 7 and 8, the animals were provided water and a
bottle containing 0.50% of saccharin solution. A 0.50% saccharin solution was used because
previous studies have reported that male rats exhibited a greater reduction in preference for this
saccharin concentration compared to females, hence the sex difference in preference is more
marked at this saccharine dose.

None of the treated dams exhibited any signs of toxicity as a result of exposure to TCDD.
Gestational body weight, liver weight, litter size and percent live births were all comparable to
the corresponding control group. Birth rate and weaning weight of the pups also were not
affected by TCDD exposure. Sex-related water consumption, however, was significantly
(p < 0.001) affected during the first 4 days with female pups drinking more water per 100 g of
body weight compared to the respective male counterparts. Saccharin consumption was

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significantly (p < 0.001) affected, with females consuming greater amounts of saccharin solution
per 100 g body weight compared to the corresponding males. Additionally, both male and
female pups drank significantly (p < 0.001) more of the 0.25% saccharin solution compared to
the 0.50% saccharin solution. Females of all exposure groups consumed less of both the 0.25
and 0.50%) saccharin solution compared to the same-sex control group. Comparisons of each
exposure group to the control group indicated that only the high TCDD exposure group
(100 ng/kg-day) different significantly (p < 0.05) compared to control in the consumption of
0.25%o saccharin solution. In contrast, for the 0.50% saccharin solution, both the low and high
TCDD dose groups differed significantly (p < 0.05 andp < 0.01, respectively) compared to the
control group. The saccharin preference of TCDD-exposed male rats did not differ from that of
the male control group. The TCDD-exposed females' preference for saccharin solution,
however, was significantly reduced in both the 25 (p < 0.05) and the 100 ng/kg-day (p < 0.005)
dose group compared to that of the female controls. The study authors state that the reduction in
saccharin consumption and preference in females could be due to the anti-estrogenic action of
TCDD and that recent research reports suggest that TCDD can decrease the level of estrogen
receptor (ER) mRNA by blocking the ability of ER to transactivate from the estrogen response
element.

A LOAEL for TCDD of 25 ng/kg-day for 7 days of gestational exposure is identified for
significantly (p < 0.05) decreased preference in the consumption of 0.25% saccharin solution. A
NOAEL cannot be determined for this study.

2.4.2.2.2. Bell et al. (2007,197041).

Bell et al. (2007, 197041) examined the reproductive effects of TCDD in rats exposed
during development. Female CRL:WI (Han) rats were treated with TCDD (99% purity;
dissolved in acetone) in the diet at concentrations of 0 (acetone alone; n = 75), 28, 93, or
530 (n = 65/group) ng TCDD/kg diet, which provided average doses of 0, 2.4, 8, or
46 ng/kg-day, respectively. Rats were exposed to TCDD 12 weeks prior to mating, during
mating, and through pregnancy. Dams were switched to the control diet after parturition. Litters
from pregnant dams were reduced to a maximum size of eight on PND 4 and to five males (if
possible) on PND 21. These males were left untreated until sacrificed (25/group, one/litter) on
PND 70, while all remaining animals were sacrificed on PND 120. All sacrificed animals were

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necropsied and received a seminology examination. Prior to sacrifice, during weeks 12 and 13,
20 animals from each dose group were tested for learning ability and motor activity, and were
also administered a functional observation battery. During postnatal week 16, groups of 20 male
F1 rats from each treatment group were paired with untreated virgin females for 7 days, and
mated females were killed on GD 16 and examined for terminal body weights, pregnancy status,
number of corpora lutea, and number of intrauterine implantations.

The study authors found no evidence of direct maternal toxicity from exposure to TCDD.
In the high-dose groups, 8 of 27 dams suffered complete litter loss compared to 3 dams in the
control group, but the difference was not statistically significant. Pup survival at PND 4 was also
lower in the high-dose group, but the difference again was not statistically significant.

A dose-related decrease in mean pup body weight was observed on PND 1, and this trend
continued throughout the lactation period. High-dose male pups had lower body weights when
compared to controls at PND 21, with this trend continuing over the course of the study.
Balanopreputial separation (BPS) was significantly (p < 0.05) delayed compared to controls in
all three treatment groups by 1.8, 1.9, and 4.4 days in the low-, medium-, and high-dose groups,
respectively. The study authors reported that adjustment for lower body weights observed at
PND 21 and PND 42 did not affect the estimate of delay in BPS. No adverse effects from
maternal treatment were observed on learning or in functional observational battery performance.
Offspring in the high-dose group exhibited less activity when compared to controls (p < 0.05)
when they were subjected to a test of motor activity for 30 minutes.

The median precoital time was 2-3 days for all 20 F1 males that were mated during
postnatal week 16. The uterine and implantation data were similar in all dose groups and there
were no significant differences in the proportion of male offspring between groups. Epididymal
sperm counts and sperm motility did not differ significantly between dose groups in animals
sacrificed during postnatal week 10. The mean number of spermatids was significantly lower
(14%;/? < 0 .05) and the proportion of abnormal sperm was significantly (p < 0.05) higher in the
high-dose group when compared to controls on PND 70. These effects, however, were not seen
in animals sacrificed on PND 120.

Terminal body weights were significantly (p < 0.05) decreased in the high-dose group
(6.9 %) compared to controls on PND 120, while the depression in body weight in the
medium-dose group (5.5%) was not statistically significant. At PND 70, the relative and

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absolute testis weight of the high-dose group was less than the controls (12 and 18%,
respectively). Absolute spleen weight in the high-dose group was significantly higher (8%) on
PND 70, and increased significantly (p < 0.05) by 1-3% on PND 120 in all dose groups
compared to controls. Kidney weight in the low and medium-dose groups was significantly
(p < 0.05) greater than in controls (-2%) at PND 120. In addition to these organs, ventral
prostate (9.4%) and relative liver (—4.5%) weights were significantly (p < 0.05) higher than
controls on PND 120 in the medium- and low- and high-dose groups, respectively. On
PND 120, absolute brain weight was significantly (p < 0.05) less than the control in the
medium-dose group, while relative brain weight was significantly (p < 0.05) higher than the
control in the low- and high-dose group. Histological examination revealed no unusual findings.

A LOAEL for TCDD of 2.4 ng/kg-day following an estimated 17 week exposure duration
of dams was identified in this study for significantly (p < 0.05) delayed BPS. A NOAEL was not
identified in this study.

2.4.2.2.3. Franczak et al. (2006,197354).

Franczak et al. (2006, 197354) examined the impact of chronic TCDD exposure on the
onset of reproductive senescence in female rats. Pregnant Sprague-Dawley rats
(n = 2-3/dose group) were fed 50 or 200 ng/kg TCDD (>99% purity) or corn oil vehicle
(4 mL/kg) orally on GD 14 and 21 and PND 7 and 14 to provide in utero and lactational
exposure to TCDD. On PND 21, female pups (n = 7/dose group) were weaned and were
subsequently given weekly doses of 50 or 200 ng/kg-week TCDD by gavage (7.14 or
28.6 ng/kg-day adjusted for continuous exposure; administered doses divided by 7) or corn oil
vehicle. Exposure continued for up to 8 months, and animals were observed for changes in
estrus cycle at 4, 6, and 8 months. Rats were sacrificed at 8 months of age when the
TCDD-treated animals had entered the transition to reproductive senescence. Following
sacrifice, diestrus concentrations of serum LH, FSH, progesterone, and estradiol were measured,
and the ovaries were collected for examination.

Estrus cycles at 4 months exhibited normal cyclicity in both TCDD-exposed groups and
did not differ significantly from the control group. At 6 months, however, there was a tendency
(p< 0.1) toward loss of normal estrus cyclicity in animals treated with TCDD. At the 8 month
observation, estrus cyclicity was significantly (p < 0.05) different in both dioxin-exposed groups

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compared to controls (cumulative TCDD exposure is reported as 1.7 and 8 |ig/kg for the 50 and
200 ng/kg dose groups, respectively). The study authors noted that although the low-dose
animals showed an increased prevalence of prolonged cycles, persistent estrus or diestrus was
observed in only 10% of the rats. Conversely, approximately 50% of the rats exhibited loss of
cyclicity in the high-dose group. There were no changes in the number and size distribution of
ovarian follicles or the number of corpora lutea at either dose. Progesterone levels at 8 months
tended to be higher (p < 0.08) in animals receiving either 7.14 or 28.6 ng/kg-day TCDD
compared to controls, while serum estradiol concentrations were significantly (p < 0.03) lower at
diestrus. Serum LH levels in TCDD-treated animals were comparable to those in the control
group, while FSH levels were elevated in rats receiving 7.14 ng/kg-day TCDD, but not in the
28.6 ng/kg-day dose group.

A LOAEL for TCDD of 7.14 ng/kg-day for an 8-month exposure duration was identified
for significantly (p < 0.03) decreased serum estradiol levels. A NOAEL cannot be determined
for this study.

2.4.2.2.4. Hojo et al. (2002,198785) (and related: Zareba et al. (2002,197567)).

Hojo et al. (2002, 198785) studied the impact of prenatal exposure to TCDD on sexually
dimorphic behavior in rats. Thirty-six pregnant Sprague-Dawley rats were assigned according to
a randomized block design to groups receiving 0, 20, 60, or 180 ng/kg TCDD (98% purity) on
GD 8. Litters from pregnant dams were culled to 5 females and 5 males on PND 4 and allowed
to wean normally, at which time 5, 5, 6, and 5 litters from the 0, 20, 60, and 180 ng/kg TCDD
treatment groups, respectively, were maintained for examination of behavioral response.
Offspring were exposed to TCDD (from a single maternal exposure) for about 35 days through
gestation and lactation. After weaning at PND 21, offspring were fed ad libitum until PND 80, at
which time a fixed amount of food was supplied daily to maintain constant body weights. At
90 days old, the rats in these treatment groups were trained to press a lever to obtain food pellets
using two operant behavior procedures. Initially, each lever press was reinforced. The
fixed-ratio (FR) requirement was then increased every fourth session from the initial setting of 1
to values between 6 and 71. The responses for 30 days were studied under a multiple schedule
combining FR 11 and another schedule requiring a pause of at least 10 sec between responses
(differential reinforcement of low rate, or DRL 10-sec)

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Pup and dam body weights were not affected by TCDD exposure, and all pups were
successfully trained in the lever-press response within 3-4 days. Analyses of the FR procedure
data indicated that the male pups responded at a lower rate at all TCDD doses when compared to
the control group. In case of female pups, all TCDD-treated groups responded at a higher rate
than controls. None of these results were, by themselves, however, statistically significant.
Examination of the FR 11 and DRL 10-second data indicated that when considering the FR
component of this multiple procedure, males from all three treatment groups responded at lower
rates when compared to the controls. Conversely, all female pups responded at a higher rate than
controls. In addition, the treatment-by-sex interaction was significant (p = 0.036), with the
60 ng/kg female pups responding at a higher rate than the 60-ng/kg male pups. Examination of
the delayed response component in the multiple FR 11 and DRL 10-sec procedures indicated that
almost all TCDD treatment groups were affected. Like the FR component, male pups at all
TCDD dose groups responded at a lower rate compared to controls, while female pups at all dose
groups responded at a higher rate than controls. There was also a significant (p = 0.001)
sex-by-treatment interaction for the DRL 10-sec similar to the FR component. Following
behavioral testing, the animals were sacrificed and cortical depth measurements were taken in
selected right and left brain regions. Reduced cortical thickness and altered brain morphometry
were observed in both male and female offspring in the 180-ng/kg exposure group when
compared to controls (reported in a separate article; Zareba et al., 2002, 197567).

A nominal LOAEL for TCDD of 20 ng/kg for a single exposure on GD 8 is established
for this study based on abrogation of sexually dimorphic neurobehavioral responses. A NOAEL
cannot be derived for this study.

2.4.2.2.5. Kattainen et al. (2001,198952).

Pregnant Line A, B, and C rats derived from Han/Wi star and Long-Evans rats
(4-8 pregnant dams/strain/treatment group) were administered a single gavage dose of 0, 30,
100, 300, or 1,000 ng/kg TCDD (purity >99%) in corn oil on GD 15 (Kattainen et al., 2001,
198952). On PND 1, the litters were culled to three males and three females. Offspring were
weaned on PND 28. Female pups were sacrificed on PND 35 and male pups were sacrificed on
PND 70. TCDD treatment did not affect body weight or cause clinical signs of toxicity in the
dams. In Line B offspring, body weights in the 1,000 ng/kg group were slightly decreased

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during PND 1-7, while Line C offspring had slightly decreased body weights throughout the
study period (data were not provided). The development of the third molar was affected the
most in Line C offspring. In 5 of 10 Line C females and 6 of 10 Line C males treated with
1,000 ng/kg TCDD, the lower third molar did not develop. In comparison, 1 of 19 Line A
females and 1 of 18 Line B females administered 1,000 ng/kg TCDD lacked the third molar at
sacrifice. Third molars were present in all the controls and all male Line A and B offspring
administered 1,000 ng/kg. Due to the lack of eruption of the third molar in the majority of
Line B and C control females (only 30% erupted), however, the effects of TCDD on third molar
eruption could only be evaluated in Line A female offspring (with 94% eruption). There was a
dose-dependent decrease in the eruption of the lower third molar in Line A female offspring with
a significant (p < 0.05) decrease observed in the 300 and 1,000 ng/kg dose groups. In the male
offspring, any third molar that developed erupted by PND 70. The mesiodistal length of the
existing lower third molar was reduced in a dose-dependent manner in both genders of all
three rat lines. In Line A and C females, the decrease was significant (p < 0.05) at all doses. The
size of the second molars was also significantly decreased with 1,000 ng/kg (p < 0.05) in all but
Line C males.

A developmental LOAEL for TCDD of 30 ng/kg for maternal exposure on GD 15 is
established for this study, based on impaired tooth development (significantly reduced
mesiodistal length of the lower third molar by approximately 12% to 38% \p < 0.05]). A
NOAEL could not be determined.

2.4.2.2.6. Keller et al. (2007,198526: 2008,198531: 2008,198033).

Keller et al. (2007, 198526; 2008, 198531; 2008, 198033) conducted three separate
experiments to assess the impact of TCDD on molar tooth development using different mouse
strains. In Experiment 1, Keller et al. (2007, 198526) used six inbred mouse strains (C57BL/6J,
BALB/cByJ, A/J, CBA/J, C3H/HeJ, and C57BL/10J) known to possess high affinity ligand-
binding aryl hydrocarbon receptor alleles (6), two with bl alleles (C57BL/6J and CBA/J), and
four with b2 alleles (BALB/cByJ, A/J, C3H/HeJ, and CBA/J). Females (number not specified)
from each strain were mated with males of the same strain. On GD 13, each pregnant female
was assigned to one of the four dose groups and treated with 0, 10, 100, or 1,000 ng TCDD/kg
BW via oral gavage. The control group received corn oil. GD 13 was chosen for dosing because

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the first morphological signs of tooth development occur on GD 11. The first visible signs of the
Ml (molar) occur on GDs 13-14 followed by final cuspal morphology, which is determined on
GD 15. The F1 offspring of females from each strain were weaned and separated by sex at PND
28 and were euthanized at PND 70. Each F1 mouse was examined for the presence or absence
of both maxillary (M3) and mandibular third molars (M3) on both the left and right sides. In
addition, all mice were scored as either normal or variant in Mi morphology for both molar rows.

In Experiment 2 (Keller et al., 2008, 198531). dams from six inbred mouse strains
(C57BL/6J, BALB/cByJ, A/J, CBA/J, C3H/HeJ, and C57BL/10J) were orally dosed on GD 13
with 0, 10, 100, or 1,000 ng TCDD/kg BW in corn oil. GD 13 was used as the dosing day
because it coincided with the formation of Meckel's cartilage (a major signal center) in the
mouse mandible that is followed shortly by intramembranous bone formation on GD 15. The
A/J mouse strain was abandoned because the authors had difficulty rearing the offspring from
this strain. All offspring (n = 4 or 5 per treatment group) from the remaining strains were
euthanized at 70 days of age. Mandible size and shape from all selected offspring were
examined using geometric morphometric methods to assess the impact of TCDD exposure.

In Experiment 3 (Keller et al., 2008, 198033). dams from six inbred mouse strains
(C57BL/6J, BALB/cByJ, A/J, C3H/HeJ, CBA/J, and C57BL/10J) were treated with a single oral
dose of 0, 10, 100, or 1,000 ng TCDD/kg-BW in corn oil. GD 13 was chosen as the dosing day
because the first visible signs of the first molar (Ml) occurs on GDs 13-14 and the final cuspal
morphology (the pattern of projections on the chewing surface of the tooth) is not determined
until after GD 15. Similar to Experiment 2, the A/J mouse strain was abandoned due to
difficulty in rearing offspring. All offspring (n = 107-110 in each of the five strains for all
treatment groups) were euthanized at 70 days of age and their molar size, shape, and asymmetry
traits were examined using geometric morphometric methods.

In Experiment 1, all four M3s were present in all dose groups in mice from C57BL/6J,
BALB/cByJ, and C57BL/10J strains. A similar response was observed in the A/J strain mice
with only 3 of 51 F1 mice exhibiting missing third molars. Approximately one-third of the mice
from the CBA/J and C3H/HeJ strains, however, were missing at least one M3 or M3 molar. The
numbers of CBA/J mice missing one or both M3 or M3 molars were 0/29, 2/21, 6/29, and 30/30
in the 0, 10, 100, and 1,000 ng/kg groups, respectively. In the C3H/Hej animals, the numbers
missing one or both molars were 1/24, 3/28, 1/26, and 30/36, respectively.

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Maternal TCDD exposure was also found to affect the frequency of Mi variants, but only
in the C57BL/10J strain, and the dose-response relationship was nonmonotonic. The proportions
of variants observed in the 0, 10, 100, and 1,000 ng/kg dose groups were 33, 68, 59, and 58%,
respectively.

A LOAEL for TCDD of 10 ng/kg maternal exposure on GD 13 is identified for this study
for increased incidence (33%) of the Mi variant in the C57BL/10J mouse strain. A NOAEL
cannot be determined in this study.

In Experiment 2 TCDD exposure of dams did not affect offspring survival or 10-week
body weight in any of the inbred mouse strains used. Analysis of variance (ANOVA) indicated
that although mandible size in both male and female offspring varied significantly (p < 0.0001)
among strains, it was not affected by TCDD exposure. In contrast, analysis of covariance
indicated that TCDD exposure significantly (p = 0.0033) decreased the mandible size in male
offspring in the C3H/HeJ strain at all treatment groups. The mean mandible size was similar
across all treatment groups in both sexes in all strains with male offspring exhibiting larger
mandibles compared to females. Males in the C3H/HeJ strain exhibited a significant (level not
reported) downward trend in mandible size throughout all treatment groups. Females in the
C3H strain also showed a similar trend in mandible size, but the trend was not significant.
ANOVA on mandible shape indicated that males had significantly (p < 0.0001) different
mandible shape in strain x treatment groups. In contrast, in female offspring, although the
mandible shape was significantly (p < 0.0001) different due to strains, treatment groups, and
litter, the strain x treatment interaction was not significant. Male offspring from the C3H/HeJ
and C57BL/6J mouse strains appear to be more sensitive to TCDD than BALB/cByJ or
CBA/J mice, with the C57BL/10J strain exhibiting intermediate sensitivity. In addition to these
analyses, Procrustes distance analysis also indicated that C3H/HeJ mice had the greatest
response to the highest dose of TCDD, followed by the C57BL/6J strain. Female offspring in the
C3H/HeJ and C57BL/6J strains also exhibited the largest change in Procrustes distance with
TCDD exposure. This trend, however, was not statistically significant (p = 0.29).

A LOAEL for TCDD of 10 ng/kg maternal exposure on GD 13 was identified for this
study for significantly (p = 0.0033) decreased mandible shape and size in male C3H/HeJ mice.
A NOAEL cannot be determined in this study.

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In Experiment 3, effect of TCDD exposure on offspring survival or body weight was not
reported. Three-way ANOVA results showed significant (p < 0.0001) differences in molar size
among strains, sexes, and litters, but not between treatment groups. Molar size difference in
sex x strain interaction was significant (p = 0.03), whereas differences in sex x treatment and
sex x strain x treatment were not significant. Additionally, molar size in treatment x strain
interaction also was not statistically significant. Based on these results, the authors reported that
molar size varied significantly (p < 0.0001) among all five strains tested, with all strains
exhibiting similar trends in all four treatment groups. Strain differences in molar size were more
apparent in male offspring. A hormesis-like trend in molar size was observed in all strains
(except in BALBc/ByJ) and sexes with an increase at the 100 ng/kg dose and a decrease in the
1,000 ng/kg dose. In addition to lack of difference in molar size for all treatment groups in all
strains, fluctuating asymmetry in molar size also did not increase with increasing doses of
TCDD.

In contrast to these results on molar size, the Procrustes ANOVA indicated that molar
shape was significantly (p < 0.0001) affected by strain, sex, treatment, and litter size. Molar
shape in sex x strain and sex x strain x treatment interactions was also highly significant
(p < 0.0001). Based on these results, the authors concluded that differences between males and
females varied based on the strain, and that the effect of TCDD exposure on each strain also
differed for male and female offspring. Because molar shape in treatment x strain interaction
was significant (p < 0.0001), differences in molar shape between the three treatment groups and
the control group were analyzed for each strain using nonorthogonal contrasts. In male
offspring, contrasts between the control group and 1,000 ng/kg were statistically significant only
in the C3H/HeJ (p < 0.0001) and CBA/J (p < 0.03) strains. These results suggest that these
two strains are most susceptible to TCDD effect on molar shape, and similar results were
observed in female offspring of these two strains. The contrast in molar shape between the
control and the 100 ng/kg treatment group for the female C57BL/6J mice also was statistically
significant (p = 0.0096). On the whole, when considering Procrustes distance results for molar
shape, the C3H/HeJ male offspring had the largest response at the low and high doses, while the
female offspring had the largest response at low and mid doses. This observation in male
C3H/HeJ mice is consistent with that of TCDD-induced changes in mandible size from Keller
et al. (2008, 198531V

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A LOAEL for TCDD of 10 ng/kg maternal exposure on GD 13 is identified for this study
for significant (p < 0.0001) differences in molar shape in male C3H/HeJ mice. A NOAEL
cannot be determined in this study.

2.4.2.2.7. Kuchiiwa et al. (2002,198355).

Kuchiiwa et al. (2002, 198355) studied the impact of in utero and lactational TCDD
exposure on serotonin-immunoreactive neurons in raphae nuclei on F1 male mouse offspring.
Twenty-one adult female ddY mice (seven per treatment group) were administered TCDD
(99.1% purity) by oral gavage once a week for 8 weeks at doses of 0, 4.9, or 490 ng/kg (0, 0.7, or
70 ng/kg-day average daily dose; administered doses divided by 7) or an equivalent volume of
olive oil vehicle (6.7 mL/kg) by gavage. Immediately following the final treatment, the mice
were housed with untreated male mice for mating. At approximately 20-21 days after mating,
3 female mice from each dose group, including the control group gave birth to 10-12 offspring.
One day after birth, each litter was culled to 10 offspring to accommodate similar lactational
TCDD exposure. On PND 28, the offspring were weaned, and three offspring from each TCDD
exposed group and the control group were selected for an immunocytochemical examination at
42 days of age. Following sacrifice of these offspring, the brain of each animal was removed
and every second serial section of the brain was processed for immunocytochemistry. In
addition to the serial sections of the brain, cells from 18 offspring (6 males per treatment group)
were used to assess the number of cells in the dorsal and median raphe nucleus, the
supralemniscal area, and the Nucleus raphe magnus.

Examination of external morphology, birth, and postnatal body weights indicated that
there were no differences between the male TCDD-exposed offspring and the control male
offspring. TCDD-exposed males, however, were aggressive toward other normal mice and were
also hypersensitive to soft touch.

Serotonin-immunoreactive neurons were found to be distributed throughout the entire
brainstem in 42-day-old males, and the general pattern in the TCDD-exposed animals was
consistent with those observed in control male offspring. Serotonergic neurons were identified
and counted in the caudal linear nucleus, the median and dorsal raphe nucleus, Nucleus raphe
pontis, interpeduncular nucleus, supralemniscal area, pedunculopontine segmental nuclei, deep
mensencephalic nucleus, Nucleus raphe magnus, pallidus, and obscurus, dorsal and medial to the

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facial nucleus and the ventrolateral medulla. Results from computerized cell counts (n = 6)
showed an average of 1,573.3 immunoreactive neurons in the raphe nuclei from the control
group versus 716.3 and 419.8 neurons in the low- and high-dose offspring, respectively. The
numbers of immunoreactive neurons in the individual raphe nuclei (dorsalis, medianus, magnus,
and B9) from the TCDD-exposed offspring were significantly (p < 0.01) lower than control
values, with the degree of reduction being dose-related.

In the absence of other relevant neurotoxicity endpoints, reduced serotonin is not an
adverse endpoint of toxicological significance in and of itself, thus, neither a NOAEL nor a
LOAEL can be established for this study. A lowest-observed-effect level (LOEL) of
0.7 ng/kg-day for an 8-week exposure duration is identified in this study for a significantly
(p < 0.01) lower number of serotonin-immunoreactive neurons in the raphe nuclei of male
offspring. A no-observed-effect level (NOEL) cannot be determined for this study.

2.4.2.2.8. Li et al. (2006,199059).

Pregnant and pseudopregnant (obtained by mating normal estrous female mice with
vasectomized male mice) NIH mice (10 per treatment group) were exposed to 0, 2, 50, or
100 ng/kg-day of TCDD (purity 99%) during early gestation (GDs 1-8), preimplantation
(GDs 1-3), or peri-implantation to postimplantation (GDs 4-8) (Li et al., 2006). On GD 9,
animals were evaluated. The two highest TCDD doses (50 and 100 ng/kg-day) caused
significant (p < 0.05) early embryo loss independent of gestational exposure time. At
100 ng/kg-day, however, the embryo loss was greater when administered during GDs 1-8 or
GDs 1-3 compared to GDs 4-8 (p < 0.01). Uterine weight was significantly decreased in the
pseudopregnant mice when administered 50 or 100 ng/kg-day TCDD during GDs 1-8
(p < 0.001) or 1-3 (p < 0.01), but was only decreased at 100 ng/kg-day in pseudopregnant mice
when administered during GDs 4-8 (p < 0.01). Estradiol levels were increased at all TCDD
treatment levels (100% at the lowest dose), but statistical significance was not indicated. All
doses at all treatment times resulted in a significant reduction (p < 0.01) in serum progesterone
levels, with a 45% decrease at the lowest dose. Because the hormone effects were observed
following 4 days of treatment, the nominal doses were averaged over the entire test period of
8 days prior to measurement. The resulting average daily doses of TCDD were 0, 1, 25, and
50 ng/kg-day.

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A LOAEL of 2 ng/kg-day administered for 4 to 8 days is established in this study for a
significant (p < 0.01) decrease in progesterone (45% above control) and an approximate 2-fold
increase in estradiol levels (significance not indicated). A NOAEL cannot be determined.

2.4.2.2.9.	Markowski et al. (2001,197442).

Pregnant Holtzman rats (4-7 per treatment group) were administered a single gavage
dose of 0, 20, 60, or 180 ng/kg TCDD (purity not specified) in olive oil on GD 18 (Markowski
et al., 2001, 197442). One female rat from each liter (4-7 per treatment group) was assigned to
training on a wheel apparatus to respond on a lever for brief opportunities to run. Once animals
responded to an FR1 schedule of reinforcement, the requirement for lever pressing was increased
to FR2, FR5, FR10, FR20, and FR30 schedules. After each training session, the estrous cycle
stage was determined. Maternal body weight, length of gestation, number of pups per litter, and
sex distribution within litters were unaffected by treatment. For each of the FR schedules, there
was a significant dose-related (p = 0.0001) decrease in the number of earned run opportunities,
lever response rate, and total number of revolutions in the wheel in the adult female offspring.
There was no correlation between estrous cycle and responding for access to wheel running.

The developmental LOAEL for this study is a single dose of 20 ng/kg administered on
GD 18 for neurobehavioral effects. A NOAEL cannot be determined for this study.

2.4.2.2.10.	Miettinen et al. (2006,198266).

Miettinen et al. (2006, 198266) administered a single oral dose of 0, 30, 100, 300, or
1,000 ng/kg TCDD (purity >99%) in corn oil on GD 15 to pregnant Line C rats. The offspring
(24-32 per treatment group) were assigned to a sugar-rich cariogenic diet (via feed and drinking
water) and were orally inoculated three separate times with fresh cultures of Streptococcus
mutans. Three control groups varied with regard to TCDD exposure and administration of a
cariogenic diet. Two of the control groups received no TCDD, and the offspring were either
maintained on a normal diet without inoculation with S. mutans (C 1; n = 48) or were given the
cariogenic diet with S. mutans inoculation (C2; n = 42). The final control group was maternally
exposed to 1,000 ng/kg TCDD with offspring fed a normal diet without S. mutans inoculation
(C3; n = 12). TCDD did not affect the maternal or offspring body weight. Survival of the
offspring was reduced in the 1,000 ng/kg dose group (50-58%) survival compared to 83-95%) in

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CI and C2, respectively). All offspring administered 1,000 ng/kg were missing all lower
third molars. Two animals (8%) in the 100 ng/kg group were missing one of their lower
third molars. All doses, except the 100 ng/kg dose, caused a significant (p < 0.05) increase in the
number of caries lesions compared to group C2 (60, 79, 76, 83, and 91% in the C2, 30, 100, 300,
and 1,000 ng/kg groups, respectively). Group C3 (1,000 ng/kg TCDD exposure, normal diet)
animals also had increased caries lesions compared to CI (8% versus 0%, respectively). There
were no changes in tooth mineral composition that could explain the increase in caries
susceptibility.

The developmental LOAEL from this study is a single dose of 30 ng/kg administered on
GD 15 based on the significant (p < 0.05) increase in dental caries in pups (30% above control).
A NOAEL cannot be determined from this study.

2.4.2.2.11. Nohara et al. (2000, 200027).

Pregnant Holtzman rats were administered 0, 12.5, 50, 200, or 800 ng/kg TCDD in corn
oil by gavage on GD 15 (Nohara et al., 2000, 200027). On PND 2, five males were randomly
selected from each litter and dose group. TCDD was detected in the thymus, spleen, and bone
marrow of the male pups on PND 21 and PND 49. TCDD was still detected in the thymus and
spleen on PND 120 but the levels decreased over time. The TCDD concentration was highest in
the thymus at all time points. There were no changes in the body, thymus, or spleen weights of
the male offspring on PND 5, PND 21, PND 49, or PND 120. On PND 5, there was a 200-fold
increase in CYP1 Al in the thymus of the high-dose male pups. CYP1 Al was only slightly
increased in the spleen. This induction decreased through PND 49. There was a slight (not
statistically significant) dose-dependent decrease in thymus cellularity in the male offspring at
PND 120. Spleen cellularity at PND 49 decreased in a dose-dependent manner (15—50% of the
control), with a statistically significant (p < 0.05) decrease observed in the high-dose group. A
slight but not significant reduction in spleen cellularity was noted in the high-dose group at
PND 21. The same effect was not observed at PND 120, nor was there any change in the percent
of B or T cells in the spleen. No changes in cytokine levels were observed in the 800-ng/kg
group.

Although a change in spleen cellularity on PND 49 (puberty) was observed, this effect
was transient and there were no coexisting changes in the percentage of splenic lymphocytes,

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spleen weight, and cytokine levels. Therefore, a developmental NOAEL of a single dose of
800 ng/kg administered on GD 15 is identified for this study. A LOAEL is not established.

2.4.2.2.12. Ohsako et al. (2001,198497).

Pregnant Holtzman rats (6 per treatment group) were administered 0, 12.5, 50, 200, or
800 ng/kg TCDD (purity >99.5%) in corn oil by gavage on GD 15 (Ohsako et al., 2001,

198497). On PND 2, five males were randomly selected from each litter. Two male offspring
from each litter were sacrificed on PND 49 and PND 120. Neither maternal nor male offspring
body weight was affected by TCDD treatment. TCDD was detected in both fat and testes at all
dose levels (including controls) with highest levels found in fat. There were no apparent
treatment-related effects on testicular weight, epididymal weight, daily sperm production, cauda
epididymal sperm reserves, luteinizing hormone, follicle stimulating hormone, or testosterone
levels. There was, however, a clear dose-dependent decrease in urogenital complex weight and
ventral prostate weight at both PND 49 and PND 120. For male offspring, statistically-
significant (p < 0.05) decreases were noted in urogenital complex weight at PND 120 in the 200
and 800 ng/kg groups, in ventral prostate weight at PND 49 in 800 ng/kg group, and at PND 120
in the 200 and 800 ng/kg groups. There was also a dose-dependent decrease in anogenital
distance (the length between the base of the genital tubercle and the anterior edge of the anus);
the decrease was not statistically significant at PND 49. At PND 120, however, male offspring
in all but the lowest dose group had significantly (p < 0.05) reduced anogenital distance
compared to the control animals. There was also a dose-dependent increase in 5aR-II mRNA
expression in the ventral prostate on PND 49 with significant increases (p < 0.05) in the 200 and
800 ng/kg animals. There was a significant (p < 0.01) decrease in the androgen receptor mRNA
in the ventral prostate on PND 49 at all doses tested. Similar effects were not observed on
PND 120 or in the caput epididymis on PND 49.

The developmental LOAEL for this study is a single dose of 50 ng/kg administered on
GD 15 for significantly (p < 0.01) reduced anogenital distance in male offspring (approximately
14%). The NOAEL for this study is 12.5 ng/kg.

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2.4.2.2.13. Schantz et al (1996,198781).

Schantz et al. (1996, 198781) studied the impact of in utero TCDD exposure on spatial
learning in male and female pups. Groups of pregnant Harlan Sprague-Dawley rats (// = 108,
divided into 4 cohorts; number of animals in each TCDD group approximately 4 per treatment
group) were dosed via gavage with 0, 25, or 100 ng/kg-day TCDD (purity >98%) in corn oil on
GDs 10-16. On the day of birth (post natal day [PND] 0), the pups were examined for gross
abnormalities and the number of live pups, weight, and sex were recorded for each litter. On
PND 2, litters were culled to eight animals and were balanced to include four males and
four females whenever possible. To minimize litter-size effects, litters with fewer than five pups
were excluded from the study. The exclusion of these litters resulted in 10-11 litters per
treatment group. Pups were weaned on PND 21 and one male and one female pup from each
litter were maintained for the learning tests. Pups were tested 5 days per week for spatial
learning and memory in a radial arm maze and a T-maze. A radial arm maze working memory
test and a T-maze DSA task were used a part of the testing process.

TCDD treatment did not affect dam gestational weight gain, dam liver weight, gestation
length, litter size, percentage of live births, birth weight, or postnatal growth of the pups
observed during the course of the study. Exposed pups, however, exhibited some signs of
toxicity in all exposure groups. Thymus weight was decreased and liver weight was increased in
the 100 ng/kg-day TCDD dose group. Also, liver microsomal 7-ethoxyresorufin-O-deethylase
(EROD) activity was markedly induced in pups from both the 25 and 100 ng/kg-day dose
groups. In the radial maze test, rats from all TCDD exposure groups displayed a significant
(p < 0.01) learning behavior as shown by progressively fewer errors from the first block of
sessions through the fourth session. The treatment by sex and treatment by session block
interactions were not significant. Comparisons between the average number of errors per session
block in the TCDD-exposed and control group indicated that both the 25 and the 100 ng/kg-day
dose groups made significantly (p < 0.05 andp < 0.001, respectively) fewer errors compared to
the control group. TCDD did not significantly affect adjacent arm selection behavior as
measured by C statistic; hence the reduction in errors observed did not appear to be accounted
for by an increased tendency to run into adjacent arms. Female pups had a significant (p < 0.05)
shorter radial arm maze latency, however, compared to the male pups. In the T-maze test,

TCDD did not significantly affect the percent of correct performance. All exposure groups

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performed best at the shortest delay, which showed a decline as the length of the intertrial delay
interval was increased. Additionally, all treated groups improved their performance over a
three-block session period. This finding indicated that animals in all groups could learn the task.
These observations were confirmed by a highly significant main effect of delay (p < 0.001) and
highly significant main effect of session blocks (p < 0.001). At the shortest 15-second delay,
average percent correct performance increased from 75 to 92%, while at the longest 40-second
delay, the average percent correct performance increased from 62 to 82%. A significant
(p < 0.05) main effect of exposure was evident in latency to respond in the T-maze.

Comparisons of the exposed group to control group, however, indicated that none of the
individual exposure groups differed significantly from the controls. Because no clear pattern
was observed in the various exposure groups, differences in latency to respond had no impact on
learning of the task.

Based on these results, the study authors state that the fact TCDD seems to have a
facilitatory effect on radial arm maze learning in rats should be interpreted with caution and
needs further evaluation using different and more varied learning tasks. No toxicologically
adverse endpoints were concurrently examined. Thus, a LOAEL and a NOAEL cannot be
determined for this study.

2.4.2.2.14. Seo et al. (1995, 197869).

To study developmental effects of TCDD on thyroid hormone levels, time-mated female
Sprague-Dawley rat dams (n = 10-14/treatment group) were administered 25 or 100 ng/kg-day
of TCDD (>98%) pure) in corn oil via gavage from GDs 10-16. Vehicle controls received
equivalent amounts of corn oil. The study also investigated PCB treatment outcomes. At birth,
pups were weighed and grossly examined for abnormalities. At 2 days of age, litters with fewer
than 5 pups were excluded from the analysis and the remaining litters were culled to 4 males and
4 females. Each treatment group contained 10 or 11 litters. Pups remained with the dams until
weaning. At weaning, 4-6 pups were retained for neurobehavioral tests (which were not
reported as part of this study). The remaining offspring were sacrificed, which provided
5-9 litters per treatment group. Data were collected from one male and one female where
possible. No signs of toxicity were evident in the dams; measurements on dams included
gestational weight gain, liver weight, litter size, and live births. Pup birth weight and weaning

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weight were unaffected by treatment. In pups sacrificed at weaning (21 days old), a significant
(p < 0.05) decrease occurred in thymus weight for the high-dose group, but not in thyroid, liver,
or brain weight. A significant (p < 0.05) decrease (20.4%) was observed in T4 in high-dose
females. Thyroid stimulating hormone and T3 were unaffected by treatment. Uridine
diphosphate (UDP)-glucuronosyl transferase activity towards 4-nitrophenol significantly
(p < 0.05) increased in both treatment groups over control values, and the increase in the
high-dose group was significantly (p < 0.05) greater than in the low-dose group. Liver
microsomal EROD activity was significantly (p < 0.05) increased in both treatment groups, but
is considered to be an adaptive response and not adverse.

A LOAEL of 100 ng/kg-day for decreased thymus weights and decreased thyroxine is
identified for this study. A NOAEL of 25 ng/kg-day is established.

2.4.2.2.15. Simanainen et al. (2004, 198106).

Simanainen et al. (2004, 198106) studied the impact of in utero and lactational TCDD
exposure on the male reproductive system in three rat lines that are differentially sensitive to
TCDD. Groups of 5 to 8 pregnant Line A, B, and C C57BL/6N CYP1A2 dams were given a
single dose of 0, 30, 100, 300, or 1,000 ng/kg of TCDD (purity >99%) in corn oil on GD 15 via
oral gavage. Control animals were similarly dosed with a corn oil vehicle. One day after birth,
litters were randomly culled to include three males and three females to allow uniform postnatal
exposure. Offspring were weaned on PND 28. Dam and pup viabilities were monitored
throughout the study. Pup body weights were determined on PNDs 1, 4, 7, 14, and 28.
Anogenital distance and crown-rump length were measured on PNDs 1 and 4. On day 70, pups
were sacrificed and trunk blood was collected. Serum was collected for testosterone analysis.
The testes, cauda of the right epididymis, ventral prostrate, seminal vesicles, and thymus was
dissected and weighed. Absolute and relative organ weights were determined, and cauda
epididymis and testes were also preserved for sperm count analysis.

TCDD caused no mortality or overt signs of toxicity to the dams. Pup survival from
implantation to the day after birth also was not affected by TCDD exposure. Survival from the
day of implantation to the day after birth, however, was uncharacteristically lower in control
Line B rats (41%), resulting in a significant difference compared with the two lowest doses (30
and 100 ng/mg TCDD). The average survival percentage in the controls for Line A, B, and C

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rats was 85% (range 80-86%); 64% (41—86%); and 74% (63—85%); respectively. Percentage of
male pup survival in each line between PND 1 and PND 28 was 99% except for Line B males
exposed to 30 ng/kg TCDD and Line C males exposed to 30 or 100 ng/kg, where male survival
rate averaged 81% (range 81—83%). On PND 70, a significant (p < 0.05) reduction in body
weight was observed only in Line B and C rats at 1,000 ng/kg. In pups exposed to 1,000 ng/kg
TCDD, both absolute and relative weight of the ventral, anterior, and dorsolateral prostrate
decreased in all three lines at most postnatal time points measured. The change was most
consistent and significant (p < 0.05) in the ventral lobe. Animals exposed to 1,000 ng/kg TCDD
had an average decrease in absolute weight of the anterior prostrate of 37, 32, and 34% in
Lines A, B and C, respectively. Additionally, the average dorsolateral prostrate weight was also
decreased by 34, 28, and 39% in Lines A, B, and C, respectively. The effect on the ventral
prostrate was reversible with the only significant (p < 0.05) decrease in weight observed in
Line B rats at PND 70 in the 1,000 ng/kg TCDD dose group. The authors reported that TCDD
had no consistent effects on the weight of seminal vesicles. The absolute weights of the testis
and epididymis showed a significant (p < 0.05) increase on PNDs 28-49, but the relative testis,
epididymis, and cauda epididymis weights remained unchanged. In pups exposed to
1,000 ng/kg TCDD, severe malformation, including small caput and cauda and degeneration of
corpus epididymis, was observed. Malformations in the epididymis were observed in 6 of
44 Line C male rat offspring and 3 of 47 Line A male rat offspring. In Line A, B, and C rats at
PND 70in the 1,000 ng/kg TCDD dose group, daily sperm production was reduced by 9, 25, and
36%) and cauda epididymal sperm reserves were reduced by 18, 42, and 49%, respectively.

Daily sperm reduction (17%) was significant (p < 0.05) in Line C rats at a TCDD dose of
300 ng/kg and in Line B and C rats at 1,000 ng/kg. A reduction in cauda epididymal sperm
reserves (25%) was significant (p < 0.05) in Line C rats at 300 and 1,000 ng/kg TCDD.

A LOAEL for TCDD of 300 ng/kg is identified for reduction in daily sperm production
and cauda epididymal sperm reserves in Line C rats. A NOAEL of 100 ng/kg is identified for
this study.

2.4.2.2.16. Sugita-Konishi et al. (2003,198375).

Sugita-Konishi et al. (2003, 198375) examined the immunotoxic effects of lactational
exposure to TCDD in newborn mice. Eight pregnant female C57BL/6NCji mice were

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administered 0, 1.8, or 18 ng/L of TCDD via drinking water from parturition to weaning of the
offspring (for a total of 17 days). Based on an average water intake of 14-16 mL/day, the
average daily intake of TCDD for the dams was 1.14 and 11.3 ng/kg-day in the low- and
high-dose groups, respectively. In male offspring sacrificed at weaning (21 days after birth),
there was a statistically-significant (p < 0.05) decrease in relative spleen weight and a
statistically-significant (p < 0.005) increase in thymic CD4+ cells in the high-dose group. The
changes in relative spleen weight and thymic CD4+ cells were dose related, but effects in the
low-dose group did not achieve statistical significance. Changes in spleen weight and CD4+ cell
numbers were not observed in the female offspring. In a separate experiment, offspring infected
with Listeria monocytogenes following lactational TCDD exposure exhibited a statistically
significant increase in serum tumor necrosis factor alpha (TNF-a) 2 days after infection in both
sexes in the low- (p < 0.05) and high-dose (p < 0.005) groups. There was also a statistically
significant increase in serum interferon gamma in Listeria-infected high-dose females (p < 0.05).
The number of bacteria in the spleen was also significantly increased (p < 0.05) 2 days after
infection in the high-dose females compared to the controls, but not in males. Listeria levels in
the spleen returned to control levels by 4 days after infection in both sexes.

Based on these results, a LOAEL for TCDD of 11.3 ng/kg-day following a 17 day
exposure to dams was identified for significantly (p < 0.05) decreased spleen weight (in male
pups), a significant (p < 0.005) increase in thymic CD4+ cells (in male pups), and for increased
susceptibility to Listeria monocytogenes (in male and female pups). The NOAEL for this study
is 1.14 ng/kg-day.

2.4.2.3. Acute Studies

2.4.2.3.1. Burleson et al. (1996, 196998).

Burleson et al. (1996, 196998) studied the impact of TCDD exposure on mice that were
challenged with the influenza virus 7 days after treatment with TCDD. Groups of 8-week-old
female B6C3F1 mice (n = 20, 2 replicate groups) were treated one time with 0, 1,5, 10, 50, 100,
or 6,000 ng/kg TCDD (purity >99%, dissolved in corn oil) via oral gavage. In addition to the
treated groups, randomly selected animals were assigned as a sentinel group and screened for
numerous pathogens. Results of all tests performed on this sentinel group were negative.

Seven days after TCDD treatment, all animals were lightly anesthetized and infected intranasally

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with a highly lethal influenza A/Hong Kong/8/68 virus (H3N1; passage 14). The animals were
infected with sufficient H3N1 virus to achieve a 30% mortality rate in the control animals.
Animals were observed for mortality and morbidity for 21 days following viral infection.
Six mice from each treatment group were sacrificed on days 3, 9, and 12 postinfection, and body,
thymus, and wet lung weights were recorded. Influenza viral titers were examined by sacrificing
eight mice each at 2 hours and at 1, 4, 6, 7, 8, 9, 10, and 11 days post infection.

Exposure to TCDD resulted in significantly (p < 0.05) increased mortality in the 10, 50,
and 100 ng/kg dose groups. No statistically significant difference in the percentage alive was
observed between these dose groups. TCDD doses of 1 and 5 ng/kg did not alter mortality in
influenza infected animals. A time-related increase in the wet weights of the lungs in infected
mice as a result of increased edema also was reflected in an increase in the lung weight-to-body
weight ratio. The study authors stated that this ratio was not altered as a result of TCDD
exposure. TCDD-only exposures at 1, 10, or 100 ng/kg did not affect thymus weight. Similarly,
animals infected with the influenza virus following TCDD exposure also showed no loss in
thymic weight. Enhanced mortality in TCDD-treated animals was not correlated with an
increase in influenza virus titers. Additionally, animals treated with 1, 10, 100, or 1,000 ng/kg
did not affect pulmonary viral titer assays on days 6, 7, and 8 postinfection. The authors also
concluded that TCDD did not alter Hong Kong virus replication or clearance.

Although these results support immunotoxic effects induced by TCDD, the findings were
not reproduced by Nohara et al. (2002, 199021) using the identical study design, and the
translation of these findings to humans is dubious. Thus, no LOAEL/NOAEL was established.
A LOEL for TCDD of 10 ng/kg for a single exposure is identified for significantly (p < 0.05)
increased mortality in mice infected 7 days later with the influenza virus. The NOEL for this
study is 5 ng/kg.

2.4.2.3.2. Crofton et al. (2005,197381).

Crofton et al. (2005, 197381) studied the impact of TCDD exposure in addition to the
impact of mixtures of thyroid disrupting chemicals and PCBs on serum total thyroxine (TT4)
concentration. Groups of female Long-Evans rats were dosed via oral gavage with 0, 0.1, 3, 10,
30, 100, 300, 1,000, 3,000, or 10,000 ng/kg-day TCDD (purity >99%) in corn oil (n = 14, 6, 12,
6, 6, 6, 6, 6, 6, and 4, respectively) for 4 consecutive days. On the day following the last dose,

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animals were sacrificed, trunk blood was collected, and serum obtained via centrifugation was
assayed for TT4 concentration using standard radioimmunoassay methods.

No visible signs of toxicity or changes in animal body weight as a result of TCDD
exposure were observed. Serum T4 levels showed a dose-dependent decrease, with the levels
dropping sharply beginning at 100 ng/kg-day dose. Percent serum T4 levels were 96.3, 98.6,
99.8, 93.3, 70.9, 62.5, 52.7, 54.7, and 49.1% in the 0.1, 3, 10, 30, 100, 300, 1,000, 3,000, and
10,000 ng /kg-day groups, respectively.

A LOAEL for TCDD of 100 ng/kg-day for 4 consecutive days of exposure is identified in
this study for a reduction in serum T4 levels (70.9% compared to 100% in controls). The
NOAEL for this study is 30 ng/kg-day.

2.4.2.3.3. Kitchin and Woods (1979,198750).

Female Sprague-Dawley rats (nine per control and four per treatment group) were
administered a single dose of 0, 0.6, 2, 4, 20, 60, 200, 600, 2,000, 5,000, or 20,000 ng/kg TCDD
(purity >99%) in corn oil. Animals were sacrificed 3 days after treatment and CYP level and
benzo(a)pyrene hydroxylase activity in the liver were measured. A significant (p < 0.05)
increase in cytochrome P450 levels occurred with doses of 600 ng/kg or greater and in
benzo(a)pyrene hydroxylase activity with doses of 2 ng/kg or greater. Cytochrome P450 was
significantly (p < 0.05) higher 1 month after a single exposure of 2,000 ng/kg (the only dose
measured), but not after 3 or 6 months. Aryl hydrocarbon hydralase (AHH; p < 0.05) and EROD
(p < 0.01) were both significantly increased through 3 months after treatment, and although
elevated at 6 months, the results were not significant.

CYP induction alone is not considered a significant toxicologically adverse effect given
that CYPs are induced as a means of hepatic processing of xenobiotic agents. Thus, no LOAEL
or NOAEL was established for this study because adverse endpoints (e.g., indicators of
hepatotoxicity) were not measured. The acute LOEL, however, is 2 ng/kg based on a significant
(p < 0.05) increase in benzo(a)pyrene hydroxylase activity (37% above control). The NOEL is
0.6 ng/kg.

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2.4.2.3.4.	Lietal. (1997.199060).

Female Sprague-Dawley rats (22 days old; 10 per treatment) were administered a single
oral dose of TCDD (>98% pure) in corn oil via gavage at doses of 3, 10, 30, 100, 300, 1,000,
3,000, 10,000, or 30,000 ng/kg. Vehicle controls received equivalent amounts of corn oil, while
naive controls were sham-treated only. In a preliminary time-course study, animals received a
single dose of 10,000 ng/kg and were sacrificed at 1, 2, 4, 8, 16, 24, 48, and 72 hours. The
time-course study showed two peaks in LH and FSH levels at 1 hour and 24 hours, with a
decrease to control values by 48 hours. Thus, in the dose-response study, animals were
sacrificed at 1 or 24 hours after treatment, blood was collected, and serum FSH and LH were
measured. The dose-response study demonstrated that the peak at 1 hour was related to the
vehicle as the peak also occurred in the vehicle controls, but did not occur in the naive controls.
At 24 hours, FSH was increased at 10 ng/kg and higher (>4-fold increase at 10 ng/kg). Doses of
10 to 1,000 ng/kg showed similar increases (not all reached statistical significance; p < 0.05). A
dose-dependent increase occurred for doses >3000 (p < 0.05) with a maximum increase of
20-fold over the vehicle control. At 24 hours, the LH response significantly (p < 0.05) increased
only for doses >300 ng/kg with a maximum increase of 15-fold above the vehicle control. The
study authors calculated an ED50 of 500 ng/kg for gonadotropin increase. The dose-dependent
release of LH was confirmed in in vitro studies, but did not occur with the same magnitude. The
increase did not occur in calcium-free medium and was unrelated to gonadotropin releasing
hormone.

Based on the increase in serum FSH, the LOAEL was 10 ng/kg and the NOAEL was
3 ng/kg.

2.4.2.3.5.	Lucier et al. (1986,198398).

Adult female Sprague-Dawley rats (six per treatment) were administered a single gavage
dose of TCDD (purity not specified) in either corn oil or contaminated soil at doses of 15, 40,
100, 200, 500, 1,000, 2,000, 5,000 (corn oil), or 5,500 (contaminated soil) ng/kg. Animals were
sacrificed 6 days later and livers were removed for analysis. No clinical signs of acute toxicity
or changes in body weight were observed at any dose. AHH increased in a dose-dependent
manner with significant (p < 0.05) increases observed at 15 ng/kg or greater in corn oil or
40 ng/kg or greater in contaminated soil. Cytochrome P450 was significantly (p < 0.05)

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increased with doses of 1,000 ng/kg or greater in corn oil or 500 ng/kg or greater in contaminated
soil. A dose-dependent increase was observed for UDP glucoronyltransferase (significance of
individual doses not reported), with the results twice as high with corn oil than with
contaminated soil. The authors state that the results indicate bioavailability from soils is 50%.

Because the association between AHH activity and TCDD-mediated hepatotoxicity is
unknown and no adverse endpoints were measured, a LOAEL or NOAEL was not determined
for this study. The acute LOEL for this study is 15 ng/kg, based on the significant (p < 0.05)
increase (80% above control) in AHH. No NOEL is established.

2.4.2.3.6.	Nohara et al. (2002, 199021).

Male and female B6C3F1 (C57BL/6 x C3H), BALB/c, C57BL/6N, and DBA2 mice
(10-40 per treatment group) were administered a single dose of 0, 5, 20, 100, or 500 ng/kg
TCDD in corn oil via gavage. Seven days following TCDD treatment, mice were infected with a
mouse-adapted strain of influenza (A/PR/34/8; H1N1) at a plaque forming unit dose designed to
target approximately 30% mortality in each strain. TCDD did not affect the body weight or
survival in any of the infected mouse strains at any dose.

Therefore, no LOAEL is established in this study. The NOAEL is 500 ng/kg.

2.4.2.3.7.	Simanainen et al. (2003, 198582).

Simanainen et al. (2003, 198582) studied the short-term effects of TCDD exposure to
determine the efficacy and potency relationships among three differentially susceptible rat lines.
The three rat lines used were A, B, and C, which were selectively bred from TCDD-resistant
Han/Wistar and TCDD-sensitive Long-Evans rats. The study authors reported that Line A rats
were most resistant to TCDD acute lethality followed by Line B and C. Groups of five or
six randomly selected rats (sex not specified) were treated with a single oral dose of TCDD
(purity >99%) in corn oil by oral gavage. The dose of TCDD was reported to range between
30 ng/kg and 3,000 |ig/kg for Line A, 30 ng/kg and 1,000 |ig/kg in Line B, and 30 ng/kg and
100 |ig/kg for Line C. Control animals were similarly dosed with a corn oil vehicle. Rats were
sacrificed on day 8 postexposure, and trunk blood was collected and serum separated. Liver and
thymus were removed and weighed, and liver samples were collected and preserved. Liver

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EROD activity, serum aspartate aminotransferase (ASAT) activity, free fatty acid (FFA)
concentration, and total bilirubin concentration were determined. Teeth were also examined.

Relative thymus weights were reduced 25% at 300 ng/kg relative to controls in Line B
rats. Liver enzyme (CYP1 Al) induction, as measured by EROD activity, was evident at all
exposure levels; CYP induction is considered to be an adaptive effect and not adverse in itself.
No other endpoints were affected below 1 |ig/kg in any of the three rat lines.

A LOAEL for TCDD of 300 ng/kg is identified for decreased relative thymus weight in
Line B rats. A NOAEL of 100 ng/kg is identified for this study.

2.4.2.3.8. Simanainen et al. (2002, 201369).

To study the short-term effects of TCDD on hormone levels, adult female Long-Evans
(TCDD-sensitive) and Han/Wistar (TCDD-resistant) rats (n = 9-11/treatment) were administered
a single dose of TCDD (>99% pure) in corn oil via gavage at doses ranging from 30 ng/kg to
100 |ig/kg. Vehicle controls received an equivalent amount of corn oil. The study also
examined other polychlorinated dibenzo-/>dioxins outcomes. Rats were sacrificed on day 8
postexposure, and trunk blood was collected and serum separated. Liver and thymus were
removed and weighed, and liver samples were collected and preserved. Liver EROD activity,
serum ASAT activity, FFA concentration, and total bilirubin concentration were determined.
Teeth were also examined.

Neither FFA or ASAT levels in Han/Wistar rats showed a dose-response relationship. In
Long-Evans rats, however, a significant (p < 0.05) dose-dependent increase in FFA occurred at
300 ng/kg TCDD. Serum ASAT sharply increased in Long-Evans rats between 3,000 and
10,000 ng/kg. Body weight change and relative thymus weights were significantly decreased
(p < 0.05) in Han/Wistar rats with doses >10,000 ng/kg and in Long-Evans rats with doses
>1,000 ng/kg. Liver EROD activity was significantly (p < 0.05) increased with all doses in both
strains. Serum T4 was significantly (p < 0.05) decreased in Long-Evans rats at concentrations
>300 ng/kg, but were not significantly affected in Han/Wistar rats. Serum bilirubin was
significantly (p < 0.05) increased with doses >10,000 ng/kg in Long-Evans rats and
>30,000 ng/kg in Hans/Wistar rats. Both strains of rat showed a dose-dependent increase in
mean severity of incisor tooth defects. The results indicate that TCDD was the most potent
congener tested in both rat strains.

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A LOAEL of 300 ng/kg for decreased T4 in the Long-Evans rat is identified for this
study. A NOAEL of 100 ng/kg is established.

2.4.2.3.9.	Smialowicz et al. (2004,110937).

Smialowicz et al. (2004, 110937) examined the impact of TCDD exposure on
immunosuppression in mice. Groups of female (number not specified) C57BL/6N CYP1A2
(+/+) wild-type mice were administered a single dose of 0, 30, 100, 300, 1,000, 3,000, or
10,000 ng/kg TCDD (purity >99%) in corn oil via oral gavage. Control animals were similarly
dosed with a corn oil vehicle. To assess immune function, 7 days after TCDD administration, all
mice were immunized with sheep red blood cells (SRBCs) via injection into the lateral tail vein.
Five days after immunization, mice were sacrificed, blood was collected, and enzyme-linked
immunosorbant assays were performed. Additionally, spleen, thymus, and liver weights also
were measured.

Body and spleen weights of the wild-type mice were unaffected by the TCDD exposure.
A decrease in thymus weights of the mice appeared to be dose related. Only mice treated with
10,000 ng/kg TCDD, however, showed a statistically significant (p < 0.05) decrease in thymus
weights compared to corresponding controls. Liver weights also showed a dose-related increase
with only animals treated with 3,000 and 10,000 ng/kg TCDD showing statistical significance
(p < 0.05) compared to the control group. The antibody response to SRBCs indicated a
dose-related suppression in the wild-type mice, with animals treated with 1,000, 3,000, and
10,000 ng/kg TCDD showing statistically significant (p < 0.05) suppression compared to the
controls.

A LOAEL for TCDD of 1,000 ng/kg is identified in female C57BL/6N CYP1A2 (+/+)
wild-type mice for significant (p < 0.05) suppression of SRBCs. The NOAEL for this study is
300 ng/kg.

2.4.2.3.10.	Van den Heuvel et al. (1994,197551).

Vanden Heuvel et al. (1994, 197551) examined the dose-response relationship between
TCDD exposure and induction of hepatic mRNA. Groups of 10-week-old female
Sprague-Dawley rats were administered TCDD (purity -99%) in corn oil once at 0, 0.1, 0.05, 1,
10, 100, 1,000, or 10,000 ng/kg-BW. Four days after TCDD treatment, animals were sacrificed

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and livers were excised and preserved. Total hepatic RNA was extracted using guanidine
thiocyanate and DNA was removed using standard phenol-chloroform-isoamyl alcohol
partitioning procedures. Quantitative competitive RNA-PCR method was used to analyze
CYP1 Al, UDP-glucuronosyltransferase I (UGT1), plasminogen activator inhibitor 2 (PAI2),
P-actin, and transforming growth factor a (TGFa). In addition to hepatic mRNA levels,
microsomal protein was assayed for EROD activity and livers were tested for TCDD
concentration.

CYP1 Al mRNA induction levels in the TCDD-treated groups were low in the low-dose
region and sharply increased to plateaus at higher doses. The lowest dose that showed a
statistically significant (p < 0.05) difference compared to controls was the 1 ng/kg dose, which
showed a three-fold increase in CYP1 Al mRNA levels. In contrast, a 130-fold increase
occurred at 100 ng/kg and a 4,000- and 7,000-fold increase occurred at 1,000 and 10,000 ng/kg,
respectively. A slight increase in the CYP1 Al/p-actin levels was observed in the 0.1 ng/kg
group, but this increase was not significant. EROD activity exhibited a pattern similar to
CYP1A1 activity. EROD activity, however, was approximately 100-fold less sensitive
compared to mRNA levels in TCDD-treated groups. Statistical significance (p-value not
provided) in CYP1 Al level was observed at the 100 ng/kg dose compared to the 1 ng/kg dose.
The study authors reported that, despite this difference in CYP1 Al and EROD activity, the
correlation between CYP1A1 enzyme activity and mRNA levels was good. Dose-response
relationships for the induction of UGT1, PAI2, and TGFa mRNA differed from what had been
observed for CYP1 Al mRNA. UGT1 mRNA was induced, but at the much higher dose of
1,000 ng/kg. Additionally, the five-fold maximum induction of UGT1 mRNA was much less
than the 7,000-fold induction observed for CYP1 Al mRNA at the 10,000 ng /kg dose. The
authors state that this could be a result of the constitutive level of UGT1, which is much higher
than CYP1A1, which makes detecting induction of UGT1 in the low dose regions more difficult.
PAI2 and TGFa mRNA were not affected by TCDD in rat liver in the dose range tested. These
results indicate that dioxin-inducible genes have a quite dissimilar dose-response relationship.

Induction of CYP1A1 expression is not considered an adverse effect, as the role of
CYP1A1 in TCDD-mediated hepatotoxicity is unsettled. Therefore, in the absence of other
indicators of hepatotoxicity, a NOAEL/LOAEL cannot be determined for this study. A LOEL

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for TCDD of 1 ng/kg for a single exposure was identified for statistically significant (p < 0.05)
increase in CYP1A1 mRNA levels. The NOEL for this study is 0.1 ng/kg.

2.4.2.4. Subchronic Studies

2.4.2.4.1.	Chu et al. (2001, 521829).

Adult female Sprague-Dawley rats (five per treatment group) were administered TCDD
(purity >99%) in corn oil by gavage at doses of 0, 2.5, 25, 250, or 1,000 ng/kg-day for 28 days
(Chu et al., 2001, 521829). The 1,000 ng/kg-day dose of TCDD caused a significant (p < 0.05)
decrease in body weight gain (36% lower than the control), increase in relative liver weight (40%
greater than the control), and decrease in relative thymus weight (50% lower than the control).
There was a significant (p < 0.05) increase in EROD activity, methoxy resoufin-O-deethylase
(MROD) activity, and UDP-glucuronosyl transferase (UDPGT) activity in the liver of female
rats receiving 250 or 1,000 ng/kg-day TCDD. In addition, significant (p < 0.05) increases in
serum cholesterol were observed in the 250 and 1,000 ng/kg-day dose groups, and liver ascorbic
acid (AA) also was significantly increased in the 1,000 ng/kg-day dose group. There was
~1.5-fold increase in liver glutathione-»Y-transferase (GST), which was not statistically
significant. Other significant (p < 0.05) findings for the 1,000 ng/kg-day group included a
decrease in liver vitamin A (51% lower than the control), an increase in kidney vitamin A
(15.5-fold increase above the control), an increase in liver benzyloxy resoufin-O-deethylase
(BROD, 30-fold increase above control), a decrease in liver pentoxyresoufin-O-deethylase
(PROD, 37%) lower than the control), increase in serum albumin (18% above the control), and a
decrease in mean corpuscular hemoglobin (MCH, 7% below the control) and mean corpuscular
volume (MCV, 7% below the control).

Based on the numerous significant (p < 0.05) liver-related biochemical changes and
significant (p < 0.05) increased relative liver weight, as well as significantly decreased body
weight and relative thymus weight, the LOAEL for 28 days of exposure in this study is
1,000 ng/kg-day and the NOAEL is 250 ng/kg-day.

2.4.2.4.2.	Chu et al., 2007.

Chu et al. (2007) examined the potential impact of TCDD on various organs and the
toxicological impacts as a result of interactions between TCDD and PCBs in rats. Groups of

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female Sprague-Dawley rats (n = 5 per treatment group) were treated daily for 28 days via
gavage with 0, 2.5, 25, 250, or 1,000 ng /kg-day TCDD (purity not specified) dissolved in corn
oil. Body weights were determined three times per week, and clinical observations were made
daily. At study termination, all animals were sacrificed and blood was analyzed for various
biochemical and hematological parameters. Liver, spleen, heart, thymus, brain, and kidneys
were removed and weighed. A small portion of the liver was homogenized and assayed for
BROD; EROD; MROD; and PROD. UDPGT, GST, and ascorbic acid levels also were
measured. Vitamin A levels in the liver, kidney, and lungs were analyzed as free retinol
(vitamin A), and histopathological analysis was conducted on various tissues.

Growth rate and thymic weights in rats treated with 1,000 ng/kg-day TCDD were
significantly (p < 0.05) inhibited compared to the control group. Enzyme analysis indicated that
measured levels of TCDD in the liver correlated with hepatic microsomal enzyme activity. The
authors reported that liver microsomal EROD and MROD activities were significantly (p < 0.05
for EROD activity, significance level for MROD not reported) increased in the 250 and
1,000 ng/kg-day TCDD dose groups compared to the control group. UDPGT levels were
significantly (significance level not reported) increased in the 250 and 1,000 ng/kg-day TCDD
dose groups compared to the controls. Serum albumin levels were significantly (p < 0.05)
increased in the 1,000 ng/kg-day TCDD dose group compared to the control group. Serum
cholesterol levels were significantly (level not reported) increased compared to the control group
at 250 ng/kg-day TCDD dose, while liver ascorbic acid concentrations were significantly (level
not reported) increased in the 1,000 ng/kg-day dose group. Hematological analysis indicated that
hemoglobin, packed cell volume, MCH, MCV, and platelet values were decreased in the
1,000 ng/kg-day TCDD dose group. Significant (p < 0.05) differences were observed only in
MCH and MCV levels compared to the control. Vitamin A levels in the liver and kidney were
significantly (p < 0.05) lower in the 1,000 ng/kg-day TCDD group compared to the control
group. Histopathological evaluation of various tissues indicated that liver, thyroid, and thymus
were the target organs. No TCDD-related affects were found in other tissues. A dose-dependent
alteration in the thymus consisted of reduced thymic cortex and increased medullar volume with
more animals exhibiting these changes at the 250 and 1,000 ng/kg-day dose level compared to
the control group. Alterations in thyroid included reduced follicles, reduced colloid density, and
increased epithelial height. A dose-dependent change in the thyroid was observed, with the

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highest impact evident in reduced follicles and reduced colloid density beginning at a dose of
25 ng/kg-day TCDD. Changes in liver were characterized by accentuated hepatic zones,
anisokaryosis of hepatocytes, increased cytoplasmic density, and vacuolation. These changes
were also dose dependent, with more animals exhibiting these histopathological changes with
increasing TCDD dose. Based on these results, the study authors concluded that exposure to
TCDD resulted in a wide range of adverse effects with the thyroid proving to be most sensitive.

A LOAEL for TCDD of 25 ng/kg for a 28-day exposure is identified for alterations in
thyroid, thymus, and liver histopathology. The NOAEL for this study is 2.5 ng/kg-day.

2.4.2.4.3. DeCaprio et al. (1986, 197403).

Hartley guinea pigs (10 per sex per dose) were administered TCDD (purity not specified)
in the diet for 90 days at concentrations of 0, 2, 10, 76, or 430 ppt (equivalent to 0, 0.12, 0.61,
4.9, and 26 ng/kg-day in males and 0, 0.12, 0.68, 4.86, and 31 ng/kg-day in females calculated by
the study authors using food consumption and body weights). Other animals were administered
the high-dose diet (i.e., 430 ppt) for 11, 21, or 35 days and then administered the control diet
(i.e., no exposure) for the remainder of the 90 days for recovery analysis. Four high-dose males
died and two were sacrificed moribund by day 45; the remaining four animals were sacrificed on
day 46 for necropsy. Four high-dose females also died and two were sacrificed moribund by day
55 with the remaining females sacrificed on day 60 for necropsy. Animals in the 76- and
430-ppt groups had significantly (p < 0.05) reduced body weights. Organ weights were not
obtained in the 430-ppt group due to the early sacrifice, but in the 76-ppt group a significant
decrease in relative thymus weight (p < 0.05) was observed, and relative liver (p < 0.01) and
brain (p < 0.05) weights in males increased. Although a similar trend occurred in the females,
the results were not statistically significant. Males administered 76 ppt in the diet also had a
53% increase in triglycerides (p < 0.05). The same increase was observed in females, but was
not statistically significant. In the recovery groups, mortality during the recovery period after 11
or 21 days of treatment was 10% and after 35 days of treatment was 70%. Animals lost weight
during the treatment period. Although the body weight increased during the recovery period, the
body weight remained low compared to the control for the study duration.

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The LOAEL from this study is 4.9 ng/kg-day for 90 days of exposure, based on
decreased body weight (12-15 %; p<0 .05) and changes in organ weights (10-30%, significant
only in the males). The NOAEL is 0.61 ng/kg-day.

2.4.2.4.4.	Devito et al. (1994,197278).

Female B6C3F1 mice (5 per treatment) were administered 0, 1.5, 4.5, 15, 45, or
150 ng/kg TCDD (98% pure) in corn oil via gavage, 5 days a week for 13 weeks. This dose is
equivalent to 0, 1.07, 3.21, 10.7, 32.1, 107 ng/kg-day (adjusted for continuous exposure,
administered dose multiplied by 5 and divided by 7). Body weight was recorded weekly and
animals were sacrificed 3 days after the last treatment. Examinations were performed on the
lung, skin, uterus, and liver. No differences were observed in the liver or uterus weights or in the
estrogen receptor levels in these two tissues. A dose-dependent increase in EROD activity (an
indicator of CYP1 Al [CYP] induction) in the lung, skin, and liver was observed, with significant
(p < 0.05) increases even at the lowest dose. The TCDD doses used did not achieve maximal
EROD induction. A significant {p < 0.05) increase in liver acetanilide-4-hydroxylase (ACOH;
an indicator of CYP1A2 induction) also was observed with all doses. A maximum induction of
ACOH occurred with doses of 3.21 ng/kg-day and greater. A dose-dependent increase in
specific phosphotyrosyl protein (pp) levels also was observed. Levels of pp34 and pp38 were
significantly {p < 0.05) increased even at the lowest dose, while pp32 reached statistical
significance {p < 0.05) with doses of 4.5 ng/kg-day and above.

The role of CYPs and phosphorylated pp32, pp34, and pp38 in TCDD-mediated toxicity
is unknown, and changes in the activity or function of these proteins are not considered adverse
Therefore, no LOAEL or NOAEL is established. The 13-week LOEL is 1.07 ng/kg-day, based
on a significant {p < 0.05) increase in EROD, ACOH, pp34, and pp38 levels (all increased by at
least 2-fold). No NOEL is established for this study.

2.4.2.4.5.	Fattore et al. (2000,197446).

Fattore et al. (2000, 197446) examined TCDD-induced reduction of hepatic vitamin A
levels in a subchronic rat bioassay on Sprague-Dawley rats. Four experiments were conducted;
Experiments 1, 2, and 3 were conducted in both male and female rats, while Experiment 4 was
conducted only in female rats. The dosing regimens for each experiment were as follows

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Experiment 1: Groups of six Iva:SIV 50 rats (male and female) were maintained on a diet
consisting of 0, 200, 2,000, or 20,000 ng TCDD/kg diet and 3-[j,g vitamin A/kg diet for
13 weeks. Assuming food consumption of 10% of body weight per day, the average daily
doses are 0, 20, 200, and 2,000 ng/kg-day TCDD.

Experiment 2\ Groups of six male and female rats were treated with 0 or
200 ng TCDD/kg-day and 3 jag vitamin A/kg diet for 13 weeks.

Experiment 3. Groups of six male and female rats were fed 0, 200, or
1,000 ng TCDD/kg-day and 3 jag vitamin A/kg diet for 13 weeks.

Experiment 4 Groups of female rats (number not specified; IVA;SIV 50 Sprague-Dawley
strain) were treated with TCDD for 26 and 39 weeks in addition to a 13-week dietary
treatment with 0 or 100 ng TCDD/kg-day and 3 jag vitamin A/kg diet for 13 weeks.

For a 13-week exposure duration employed in all four experiments, male and female rats
were treated at 0, 20, 100 (females only), 200, 1,000, or 2,000 ng/kg-day. In all
four experiments, liver from control and treated animals was analyzed at termination for free
retinol content to determine hepatic vitamin A levels.

Results'.

Experiment 1: Liver and body weights in both treated males and females were significantly
affected at all but the lowest dose tested (20 ng/kg-day). Liver injury was severe, particularly
in female rats treated with 2,000 ng TCDD/kg-day. Dietary intake of vitamin A in male rats
was comparable to intake in controls, except in the 2,000 ng/kg-day group, which showed a
reduction of 16% in the dietary intake of vitamin A compared to controls. There was no
effect of TCDD on vitamin A intake in female rats. Hepatic vitamin A levels showed a
dose-dependent reduction with levels dropping sharply in the 200 and 2,000 ng/kg-day dose
groups, particularly in treated females. The reduction was significant at 200 ng/kg-day
(p < 0.05) and 2,000 ng/kg-day (p < 0.01) in males, and at 200 ng/kg-day (p < 0.5) and
2,000 ng/kg-day (p < 0.001) in females. The reductions ranged from 68-99%) in males and
72-99%) in females when compared to corresponding controls.

Experiment 2\ Changes in liver and body weights were not reported. Hepatic vitamin A
level in males and females were reduced by 70% and 99%, respectively, compared to
controls, in rats receiving 20 ng/kg-day (significance level in females: p < 0.01).

Experiment 3. Similar to the results of Experiments 1 and 2, a dose-related trend of
significantly (p < 0.001) reduced hepatic vitamin A level was observed in both males and
females, with males exhibiting a particularly sharp drop at the 1,000 ng/kg-day dose
compared to controls.

Experiment 4. Females treated with 100 ng/kg-day showed significant reductions in hepatic
vitamin A levels (p < 0.05-0.001) at all three treatment durations (13, 26, and 39 weeks).

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A LOAEL for TCDD of 20 ng/kg-day for a 13-week subchronic exposure was identified
in this study for decreased hepatic vitamin A levels (27 and 24 % lower than the corresponding
control in female and male rats, respectively). This LOAEL is determined using data from
Experiment 1. A NOAEL was not identified in this study.

2.4.2.4.6.	Fox et al. (1993,197344).

Sprague-Dawley rats (6 per sex per dose) were gavaged with TCDD (purity not
specified) in corn oil using a dose-loading regime to achieve and maintain steady-state levels of
0.03, 30, or 150 ng/g in the liver. The regime consisted of an initial loading dose of 5, 2,500, or
12,000 ng/kg followed every 4 days with a maintenance dose of 0.9, 600, or 3,500 ng/kg.
Averaging the doses over the 14 days provides average daily doses of 0.55, 307, and
1,607 ng/kg-day (e.g., 5 ng/kg-day on day 1 and 0.9 ng/kg-day on days 5, 9, and 13 is 5 + 0.9
+ 0.9 + 0.9/14 = 0.55 ng/kg-day). Body weight, liver weight, and liver gene expression were
measured at 7 and 14 days. A significant (p < 0.05) decrease in body weight occurred in
high-dose males (at 14 weeks only) and females (at 7 and 14 days). A significant (p < 0.05)
increase in absolute and relative liver weights was observed in mid- and high-dose males and
females at both 7 and 14 days. Although the liver of treated animals indicated moderate
vacuolization and swelling, there was no indication of necrosis. An increase in gene expression
(clone 1, CYP1 Al, CYP1A2, and albumin) was observed in the mid- and high-dose groups. A
significant (p < 0.05) decrease in labeling index (indication of cell proliferation) occurred in both
females (all doses) and males (high-dose only) during week 1, but not during week 2.

The 14-day LOAEL is 307 ng/kg-day for significant (p < 0.05) increases in absolute and
relative liver weights (25—34%). The NOAEL is 0.55 ng/kg-day.

2.4.2.4.7.	Hassoun et al. (1998,136626).

Female B6C3F1 mice (number not specified) received TCDD (>98% pure) in corn oil
5 days per week for 13 weeks via gavage at doses of 0, 0.45, 1.5, 15, or 150 ng/kg (equivalent to
0, 0.321, 1.07, 10.7, and 107 ng/kg-day adjusted for continuous exposure; administered dose
multiplied by 5 and divided by 7). Three days after the final dose, animals were sacrificed and
brains were removed for oxidative stress testing. Biomarkers for oxidative stress included
production of superoxide anion, lipid peroxidation, and DNA single-strand breaks. A significant

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(p < 0.05) increase was observed in superoxide anion production, lipid peroxidation as measured
by thiobarbituric acid-reactive substances (TBARS), and DNA single-strand breaks with all
doses tested.

No other indicators of brain pathology were assessed, and it is unfeasible to link the
markers of oxidative stress to a TCDD-induced toxicological outcome in the brain. Thus, no
LOAEL/NOAEL was established. The subchronic (13-week) LOEL is 0.32 ng/kg-day, based on
significant (p < 0.05) increases in superoxide anion production (80% above control); lipid
peroxide production (25% above the control); and DNA single-strand breaks (2-fold over the
control). No NOEL is established.

2.4.2.4.8. Hassoun et al. (2000,197431).

Hassoun et al. (2000, 197431) examined the effect of subchronic TCDD exposure on
oxidative stress in hepatic and brain tissues. Groups of 8-week-old female Harlan Sprague-
Dawley rats (6 rats/group) were administered TCDD (98% purity, dissolved in 1% acetone in
corn oil) via gavage at 0, 3, 10, 22, 46, or 100 ng/kg-day, 5 days/week for 13 weeks (0, 2.14,
7.14, 15.7, 32.9, or 71.4 ng/kg-day adjusted for continuous exposure; administered doses were
multiplied by 5 and divided by 7 days/week). Animals were sacrificed at the end of the study
period, and brain and liver tissues were collected and used to determine the production of
reactive oxygen species, lipid peroxidation, and DNA single-strand breaks (SSBs).

A dose-dependent effect was observed in both the liver and brain tissue as a result of
TCDD treatment. Based on the maximal induction of superoxide anion by various doses, more
production of superoxide anion was observed in the liver tissue when compared to the brain
tissue with an observed increase of 3.1- and 2.2-fold respectively, when compared to the control
group. A similar dose-dependent effect was observed in the induction of lipid peroxidation in
TCDD-treated animals with an approximately 1.8-fold increase in lipid peroxidation in both
tissues relative to the corresponding controls. A dose-dependent relationship was also observed
for DNA SSBs in both the hepatic and brain tissues at all TCDD-treated doses compared to
controls. Increases were statistically significant (p < 0.05) beginning at the lowest administered
dose.

Similar to the statement above, because no adverse endpoints were measured, no
LOAEL/NOAEL was established. However, a LOEL for TCDD of 2.14 ng/kg-day for a

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13-week exposure duration was identified in this study for significant increases (p < 0.05) in
superoxide anion, lipid peroxidation, and DNA SSBs in the liver and brain tissues. A NOEL
cannot be determined for this study.

2.4.2.4.9. Hassoun et al. (2003,198726).

Hassoun et al. (2003, 198726) examined the role of antioxidant enzymes in
TCDD-induced oxidative stress in various regions of the rat brain after subchronic exposure.
Groups of 8-week-old female Harlan Sprague-Dawley rats (12 rats/group) were administered
TCDD (98% purity, dissolved in 1% acetone in corn oil) via gavage at 0, 10, 22, or 46 ng/kg-day
(0, 7.14, 15.7, or 32.9 ng/kg-day adjusted for continuous exposure; administered doses were
multiplied by 5 and divided by 7) daily for 13 weeks. Animals were sacrificed at the end of the
study period and the brain was immediately removed and dissected to the following regions:
cerebral cortex (Cc), hippocampus (H), cerebellum (C), and brain stem including midbrain, pons,
and medulla. Four pooled samples from each region per dose (i.e., 3 animals/pooled sample)
were used in the study. Dissected regions were subsequently assayed for lipid peroxidation
(thiobarbituric acid reactive substances, or TBARS), superoxide dismutase, catalase, and
glutathione peroxidase. Because the cytochrome c reduction method was used to determine
superoxide anion (SA) production in brain tissues, superoxide dismutase (SOD) was added to
some of the brain tissue samples that had the highest SA production (tissue homogenates from
Cc and H from rats treated with 46 ng/kg-day TCDD).

A dose-dependent increase in the production of SA was observed in the Cc and H, but
significant changes in SA production were not observed in either the C or the mid-brain, pons, or
medulla brain stem cells. Similar to SA production, there was a dose-dependent increase in the
production of TBARS in the Cc and H regions of the brain, but no significant changes were
observed in either the C or the B sections of the brain. The study authors also measured the
activities of various enzymes as a result of TCDD treatment and reported a dose-dependent
increase in SOD activity in the C and B sections, while there was dose-dependent suppression in
SOD activity in Cc and H. In contrast, catalase activity was significantly (p < 0.05) increased in
H and Cc at the 10 ng/kg-day TCDD dose level compared to controls and the mid- and high-dose
animals. Catalase activity also was increased in a dose-dependent manner in the C section, but
no significant changes in the activity of this enzyme were observed in the B section at any of the

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three TCDD tested doses. The effects of subchronic exposure to different doses of TCDD on
glutathione stimulating hormone peroxidase (GSH-Px) showed a different response compared to
other enzymes. There was a dose-dependent increase in the activity of this enzyme in the C and
B regions of the brain, while a significant increase in the activity of GSH-Px occurred in Cc and
H only at the 10 ng/kg-day TCDD dose. In addition, the activity of this enzyme was suppressed
in a dose-dependent manner in the Cc and H at 22 and 46 ng/kg-day TCDD doses. Based on
these results, the study authors concluded that induction of oxidative stress by TCDD in the rat
brain occurs mainly in the Cc and H regions.

Similar to the statement above, because no adverse endpoints were measured, no
LOAEL/NOAEL was established. However, a LOEL for TCDD of 7.14 ng/kg-day for a
13-week exposure duration was identified for this study for increases in superoxide anion and
lipid peroxidation production, as well as increased activity in SOD, catalase, and GSH-Px.

2.4.2.4.10. Kociba et al. (1976,198594).

Adult Sprague-Dawley rats (12 per sex per treatment group) were administered TCDD
(purity not reported) in corn oil via gavage 5 days per week at doses of 0, 1, 10, 100, or
1,000 ng/kg-day (equivalent to 0, 0.71, 7.14, 71.4, or 714 ng/kg-day averaged over 7 days; 5/7 of
dose). Five animals per group were sacrificed at the end of treatment, and the remaining animals
were observed over 13 weeks post treatment (only initial results for the post-treatment period
were provided in the report). Body weights and food consumption were measured semiweekly.
Hematology and clinical chemistry were measured after 36-37 or 85-86 days of treatment and
59-60 days after termination of treatment. Forty-eight hour urine samples were collected from
select rats from 85-89 days of treatment and 52-56 days after cessation of treatment. Gross and
histopathological exams were conducted on the tissues.

Four high-dose females died during treatment. Two high-dose females and
two high-dose males died during the post-treatment period. Animals treated with 714 ng/kg-day
were less active during the treatment period, which became less evident during the
post-treatment period. Yellow discoloration of the external pinnae also was noted in this group,
both during treatment and during the post-treatment period. A significant (p < 0.05) reduction in
body weight and food consumption was observed in the 71.4 and 714 ng/kg-day groups. The
following significant (p < 0.05) hematology changes were observed in the high-dose

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(714 ng/kg-day) males at all measured time points: decreased packed cell volume, decreased red
blood cells, decreased hemoglobin, increased reticulocytes, and decreased thrombocytes.
Significant (p < 0.05) changes also occurred in the high-dose females, but the only consistent
observation was a decrease in thrombocytes and increased leukocytes. Significant changes in
clinical chemistry (p < 0.05) and urinalysis (p < 0.05) were more consistent between the sexes in
the high-dose group and included increases in total and direct serum bilirubin; increase in serum
alkaline phosphatase; decreased urinary creatinine; and increased urinary coproporphyrin,
uroporphyrin, and delta-amino-levulinic. The following significant (p < 0.05) changes were
observed in the 71.4 ng/kg-day group: decreased packed cell volume (4-9%) in males; decreased
red blood cells (2-10%) in males; decreased hemoglobin (2—13%) in males; increased urinary
coproporphyrin (2.2-fold increase during treatment) in females; increased urinary
delta-amino-levulinic (47% increase during treatment) in females; increased total and direct
serum bilirubin (48—61%) in females; and increased serum alkaline phosphatase (2-fold) in
females. The following significant (p < 0.05) changes in relative organ weights were observed
increased brain weight in 714 ng/kg-day males and females; increased liver weight in males
(71.4 and 714 ng/kg-day) and females (7.14, 71.4, and 714 ng/kg-day); increased spleen weight
in 714-ng/kg-day males and females; decreased thymus weight in 71.4 and 714 ng/kg males and
females; and increased testes weight in 714 ng/kg-day males. Microscopic changes were
observed in the thymus, and in other lymphoid tissues, and in the liver in rats treated with
71.4 ng/kg-day or greater.

The subchronic (13-week) LOAEL is 71.4 ng/kg-day, based on the numerous changes
noted in body weight, hematology, clinical chemistry, urinalysis, and histopathology. The
NOAEL is 7.14 ng/kg-day.

2.4.2.4.11. Matty and Chipman (2002,198098).

Female F344 rats (3 per treatment group) were administered TCDD at concentrations of
0, 2.5, 25, or 250 ng/kg in corn oil via gavage for either 3 consecutive days or 2 days per week
for 28 days (Mally and Chipman, 2002, 198098). The average daily doses for the 28-day study
when adjusted for 7 days a week were 0, 0.71, 7.1, and 71 ng/kg-day (i.e., 2/7 of administered
dose). No clinical signs of toxicity were observed. Histological examination of the liver
revealed no abnormalities. All doses of TCDD reduced the number of connexin (Cx) 32 plaques

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and Cx32 plaque area in the liver, which was considered the target tissue. The reductions were
not statistically significant after the 3-day treatment, but were significant after the 28-day
treatment (p < 0.05). TCDD also caused a reduction in the Cx32 plaque number and area in the
thyroid after 28 days, but the results were not statistically significant. Although the reduction in
Cx32 plaque number and plaque area in the liver and thyroid occurred at all dose levels, there
was no relation to dose. TCDD did not induce hepatocyte proliferation.

In the absence of additional indicators of hepatotoxicity, changes in Cx32 plaques are not
clearly linked to TCDD-mediated hepatotoxicity, nor are they considered an adverse effect.
Additionally, no toxicologically-relevant endpoints were examined. Therefore, a NOAEL or
LOAEL cannot be determined. A 28-day LOEL at the lowest dose of 0.71 ng/kg-day for
significantly (p < 0.05) decreased Cx32 plaque area is evident (approximately 70% of the
controls).

2.4.2.4.12. Slezak et al (2000,199022).

Slezak et al. (2000, 199022) studied the impact of sub chronic TCDD exposure on
oxidative stress in various organs of B6C3F1 female mice. Groups of 8- to 10-week-old female
B6C3F1 mice (number not specified) were administered TCDD (purity >98%, dissolved in corn
oil) via gavage at 0, 0.15, 0.45, 1.5, 15, or 150 ng/kg-day (0, 0.11, 0.32, 1.07, 10.7, or
107.14 ng/kg-day adjusted for continuous exposure) 5 days per week for 13 weeks. Three days
after the last treatment, the animals were sacrificed and organs were removed for the
measurement of oxidative stress indicators including SA, lipid peroxidation (TBARS), and
GSH-Px. Tissue TCDD concentrations also were measured.

The study authors reported that TCDD dose range resulted in overlapping tissue
concentrations for liver, lung, kidney and spleen. Liver had the highest TCDD concentration,
with each tissue demonstrating a dose-dependent increase in TCDD concentration. Compared to
controls, SA production was significantly (p < 0.05) lower at the 0.15 ng/kg-day TCDD dose,
while it was significantly (p < 0.05) higher at 15 and 150 ng/kg-day. A dose-dependent increase
in hepatic TBARS production was observed, although the rate of production was significant
(p < 0.05) only at the highest TCDD administered dose (150 ng/kg-day) compared to controls.
AA also followed the same pattern observed for SA and TBARS with AA production
significantly (p < 0.05) increased at the 15 and 150 ng/kg-day TCDD doses. Contrary to the SA,

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TBARS, and AA responses, GSH levels were decreased at 0.15 ng/kg-day, were increased at
0.45 and 150 ng/kg-day, and did not change at 1.5 or 15 ng/kg-day when compared to the control
group. Unlike the liver, there was no significant increase in SA production in the lung at any of
the TCDD tested doses; a dose dependent reduction, however, was observed at 0.45, 15, and
150 ng/kg-day compared to controls. GSH and AA production was decreased at 0.15 ng/kg-day,
while AA production was significantly (p < 0.05) increased at 15 and 150 ng/kg-day. Kidney
SA production showed a statistically significant (p < 0.05) increase only at the 15 and
150 ng/kg-day doses. GSH, like the liver and the lung, exhibited a decrease in production
following treatment at 0.15 ng/kg-day with this trend continuing at 0.45 and 1.5 ng/kg-day. AA
levels were significantly (p < 0.05) lower at all subchronic doses, except at 1.5 ng/kg-day dose.
SA levels in the spleen differed little from the control group at any of the TCDD doses. Total
GSH was higher only at the 150 ng/kg-day dose level, while the AA levels were significantly
(p < 0.05) decreased at 0.15, 1.5, and 150 ng/kg-day.

Similar to the statements regarding the Hassoun et al. studies above, because no adverse
endpoints were measured, no LOAEL/NOAEL was established. Therefore, a NOAEL or
LOAEL cannot be determined. However, a NOEL and LOEL of 1.07 and 10.7 ng/kg-day,
respectively, are identified in this study for increases in superoxide anion in the liver.

2.4.2.4.13. Smialowicz et al. (2008,198341).

Female B6C3F1 mice (8-15 per treatment group) were administered TCDD (purity
>98%) in corn oil by gavage at doses of 0, 1.5, 15, 150, or 450 ng/kg-day, 5 days a week for
13 weeks (1.07, 10.7, 107, or 321 ng/kg-day, adjusted for continuous exposure; i.e., 5/7 of the
dose) (Smialowicz et al., 2008, 198341). Mice were immunized 3 days after the final TCDD
exposure with an intravenous injection of an optimal concentration of 4 x 107 SRBCs and
sacrificed 4 days later. No TCDD-related effects on body weight were observed. There was a
dose-related decrease in relative spleen weight (9-19% lower than control values) with
statistically significant (p < 0.05) decreases at all but the lowest dose. Additionally, there was a
statistically significant (p < 0.05) increase in relative liver weight (5—21%) in all treatment
groups compared to controls. Statistically significant dose-dependent decreases were observed
in the antibody response to SRBCs (24-89% lower than control values), as measured by both the

number of plaque forming cells per 106 cells and plaque forming cells per spleen.

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The 13-week LOAEL for this study is 1.07 ng/kg-day based on a significant (p < 0.05)
increase in relative liver weight (10%) and a significant (p < 0.05) decrease in antibody response
to SRBCs (24%). A NOAEL cannot be determined for this study.

2.4.2.4.14. Van Birgelen et al. (1995,197096:1995,198052)

Van Birgelen et al. (1995, 197096; 1995, 198052) studied the impact of TCDD exposure
on various biochemical endpoints in rats. Groups of 7-week-old female Sprague-Dawley rats
(n = 8 per treatment group) were treated with 0, 200, 400, 700, 5,000, or 20,000 ng/kg TCDD
(purity >99%) in diet for 13 weeks. Daily TCDD intake based on food consumption, diet level,
and mean weight was estimated to be 0, 14, 26, 47, 320, or 1,024 ng/kg-day. Blood samples
were collected from treated animals and assayed for retinol (vitamin A), triiodothyronine, and
total (TT4) and free (FT4) thyroxine. At study termination, the animals were sacrificed and the
liver, thymus, spleen, and kidneys were removed and weighed. Parts of the liver were
homogenized and assayed to determine EROD; CYP1A1; CYP1A2; and UDPGT activity. Liver
samples also were analyzed for retinol content.

TCDD-treated animals showed a dose-related decrease in food consumption. Animals
treated with 1,024 ng/kg-day TCDD consumed 32% less food compared to controls. Similarly, a
dose-related decrease in body weight gain was observed in all animals treated with TCDD.
Animals treated with >47 ng/kg-day of TCDD showed a statistically significant (p < 0.05)
decrease in body weight gain. Relative liver weights were significantly (p < 0.05) increased in
the 320 and 1,024 ng/kg-day TCDD dose groups compared to the controls. Absolute and relative
thymus weights were significantly (p < 0.05) decreased at all TCDD dose groups compared to
the control group. Relative kidney and spleen weights were significantly (p < 0.05) higher in
animals dosed with >47 ng/kg-day of TCDD compared to the control group, with the greatest
increase occurring in animals treated with 1,024 ng/kg-day TCDD (121 and 173%) higher than
controls for kidney and spleen, respectively). Cytochrome P450 enzymes, including EROD,
CYP1A2, CYP1 Al, and UDPGT, exhibited statistically significant (p < 0.05) increases in
activity at all TCDD dose groups compared to the control group. TT4 and FT4 thyroid hormone
concentrations were statistically significantly (p < 0.05) decreased only at TCDD doses
>47 ng/kg-day. A dose-dependent increase was observed in the plasma retinol concentrations
with significant (p < 0.05) increases occurring at >47 ng/kg-day TCDD after a 13-week

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exposure. A dose-dependent reduction in liver retinoid levels also was observed after 13 weeks
of TCDD exposure with the levels dropping significantly (p < 0.05) at all TCDD-treated doses
compared to the control group.

A LOAEL for TCDD of 14 ng/kg for a 13-week exposure is identified for significantly
(p < 0.05) decreased absolute and relative thymus weights and significantly (p < 0.05) decreased
liver retinoid levels. A NOAEL cannot be determined for this study.

2.4.2.4.15. Vos etal., (1973,198367).

Vos et al. (1973, 198367) conducted a study to examine the immune response in
laboratory animals treated with TCDD. In one experiment, 10 female Hartley strain guinea pigs
were orally treated with 8 weekly doses of 0, 8, 40, 200, and 1,000 ng/kg TCDD in corn oil
(purity of TCDD not specified) (0, 1.14, 5.71, 28.6, and 143 ng/kg-day adjusted for continuous
exposure; administered dose divided by 7). At study termination, the animals were sacrificed,
and heart blood was used to determine total leukocyte and differential leukocyte counts. In
another experiment, the effect of TCDD on humoral immunity was determined by injecting
0.1 mL of tetanus toxoid into the right hind-foot pad on day 28 (1 left foot tetanus toxoid,
aluminum phosphate-adsorbed) and again on day 42 (1 left foot tetanus toxoid, unadsorbed).
Blood was collected (n= 10) on days 35 and 49, and the serum tetanus-antitoxin concentrations
were determined using a modified single radial immunodiffusion technique.

All guinea pigs receiving 1,000 ng/kg-day TCDD either died or were killed when
moribund between 24 and 32 days. These animals showed severe weight loss, lymphopenia, and
depletion of the lymphoid organs, especially the thymus. Microscopic observations revealed
severe atrophy of the thymic cortex with substantial destruction of lymphocytes, with the nuclear
debris being engulfed by macrophages. Large cystic Hassall bodies, filled with
polymorphonuclear leukocytes were observed in the medulla. All animals treated with 0, 8, 40,
or 200 ng/kg-day TCDD survived until study termination. Body weight gain was significantly
(p < 0.01) lower in the 200 ng/kg-day group. Absolute thymus weight was significantly reduced
in the 40 and 200 ng/kg-day treatment groups (p< 0.01 andp < 0.05, respectively). In contrast,
relative thymus weight was significantly (p < 0.01) reduced only in the 200 ng/kg-day dose
group. The absolute weight of the superficial cervical lymph nodes was significantly (p < 0.05)
decreased in the 200 ng/kg-day group, while the relative adrenal weight was significantly

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(p < 0.05) increased in the 200 ng/kg-day dose group. Total leukocyte count was significantly
(p < 0.05) decreased in the 40 ng/kg-day dose group and total lymphocyte count was
significantly decreased at 8, 40, and 200 ng/kg-day (p < 0.01 ,p < 0.05, andp < 0.05,
respectively). A significant (p-values not provided) monotonic dose-response relationship was
determined for body weight (decrease), relative thymus weight (decrease), relative adrenal
weight (increase), and total leukocyte and lymphocyte count (decrease). Microscopic
examination of the lymphoid organs and adrenals showed no effects, while slight cortical atrophy
of the thymus was observed at the 200 ng/kg-day dose.

Animals receiving the tetanus toxoid injection showed a small but significant increase in
serum tetanus antitoxin concentrations at the 8 and 40 ng/kg-day dose (p < 0.05 andp< 0.01,
respectively). Measurement at days 49 and 56 indicated that serum antitoxin levels had
decreased sharply and the significant (p < 0.05 on day 49 andp < 0.01 on day 56) effect was
seen only at the 200 ng/kg-day dose level.

A LOAEL for TCDD of 5.71 ng/kg-day for an 8-week exposure is identified in this study
for significantly (p < 0.01) reduced absolute thymus weight, significantly (p < 0.05) reduced
leukocyte and lymphocyte count, and significantly (p < 0.01) increased serum tetanus antitoxin
concentration. The NOAEL for this study is 1.14 ng/kg-day.

2.4.2.4.16. White et al. (1986,197531).

White et al. (1986, 197531) studied the impact of TCDD exposure on serum complement
levels. Groups of female (C57BL/6 x C3H)F1(B6C3F1) mice were treated for 14 consecutive
days with TCDD in corn oil (purity of TCDD not specified) at doses of 0, 10, 50, 100, 500, 1,000
or 2,000 ng/kg-day via gastric intubation (n = 6-8). At study termination, blood was collected
from anesthetized animals and assayed for serum complement activity and complement
component C3 levels.

Serum complement activity between the 10 and 100 ng/kg-day doses was between 69 and
59% compared to the vehicle control group, with all treatment groups being significantly
(p < 0.05) low compared to the vehicle control. In contrast, C3 levels were comparable to the
vehicle control with levels ranging between 98 and 94% of the control group. The higher doses
of 500, 1,000, and 2,000 ng/kg-day, however, produced a marked decrease of the component

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hemolytic activity (45, 35, and 19% of the vehicle control) and of C3 levels (91, 81, and 74 % of
the vehicle control, respectively; significance level at/? < 0.05).

A LOAEL for TCDD of 10 ng/kg-day for a 14-day exposure is identified in this study for
significantly (p < 0.05) lower serum complement activity. A NOAEL cannot be determined for
this study.

2.4.2.5. Chronic Studies (Noncattcer Endpoints)

2.4.2.5.1.	Cantoni et al. (1981,197092).

CD-COBS rats (4 per treatment) were orally administered TCDD (purity not specified)
dissolved in acetone:corn oil (1:6) at doses of 0 (vehicle alone), 10, 100, or 1,000 ng/kg per week
(equivalent to 1.43, 14.3, and 143 ng/kg-day adjusted for continuous exposure, administered
dose by dividing the dose by 7) for 45 weeks. Urine was collected several times during
treatment and tested for porphyrin excretion. Twenty-four hours after the final dose, animals
were sacrificed and their livers, spleens, and kidneys were removed for analysis of total
porphyrins. All treatment groups had a significant (p < 0.05) increase in coproporphyrin
excretion beginning at 6, 3, or 2 months, respectively. Uroporphyrin excretion was significantly
(p < 0.05) increased in the 14.3 ng/kg-day group at 10 months and in the 143 ng/kg-day group
beginning at 6 months. The high-dose group also had a significant (p < 0.05) increase in
excretion of heptacarboxylic methyl ester beginning at 6 months. The high-dose group had a
marked porphyric state beginning at 8 months as indicated by a 70-fold increase above controls
in total urinary porphyrin excretion. This group also had a significant (p < 0.05) increase in total
porphyrins in the liver, kidneys, and spleen.

The 45-week LOAEL for this study is 1.43 ng/kg-day, based on a 2- to 3-fold increase in
urinary coproporphyrin excretion. No NOAEL was established for this study.

2.4.2.5.2.	Croutch et al. (2005,197382).

Croutch et al. (2005, 197382) examined the impact of TCDD exposure on body weight
via insulin-like growth factor (IGF) signaling. Female Sprague-Dawley rats were randomly
assigned in groups of five to initial loading doses of TCDD (purity >98.5%, dissolved in corn
oil) at 0, 12.5, 50, 200, 800, or 3,200 ng/kg-day, followed by treatment with maintenance doses
equivalent to 10% of the initial loading dose every third day to maintain a pharmacokinetic

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steady state throughout the entire study (equivalent to: 14-day average = 0, 1.25, 5, 20, 80, or
320 ng/kg-day; 28-day average = 0, 0.85, 3.4, 13.6, 54.3, or 217 ng/kg-day; 63-day average = 0,
0.60, 2.4, 9.5, 38, or 152 ng/kg-day; and 128-day average dose = 0, 0.51, 2.0, 8.1, 32.5, or
130 ng/kg-day). Following 2, 4, 8, 16, 32, 64, or 128 days of initial dosing, the animals were
sacrificed, livers were removed and weighed, and trunk blood was collected to analyze glucose
content. Rat liver phosphoenolpyruvate carboxykinase (PEPCK) mRNA and protein levels also
were analyzed, and PEPCK activity was measured.

Body weights of TCDD-treated animals decreased after the second week of the
3,200 ng/kg-day TCDD loading dose, with significant differences beginning at week 9. There
was also a statistically significant (p < 0.05) difference in body weights at weeks 10, 11, 13, 18,
and 19 at the highest loading dose (3,200 ng/kg-day). PEPCK activity in the liver was also
decreased in a dose-dependent manner following TCDD administration at approximately
16 days. PEPCK inhibition was statistically significant (p < 0.05) on day 4 in rats treated with
either 800 or 3,200 ng/kg-day TCDD when compared to animals treated with a loading dose of
200 ng/kg-day. A similar statistically significant change was observed in animals treated with
3,200 ng/kg-day on day 16 when compared to the 200 ng/kg-day treatment group. In contrast,
differences in PEPCK activity at other doses or time points were not statistically significant. In
TCDD-treated animals, there was also a dose-dependent decrease in PEPCK mRNA expression
along with a decrease in PEPCK protein levels in the liver. In addition to body weight and
PEPCK activity changes, animals treated with 3,200 ng/kg-day TCDD showed a sharp decline in
circulating IGF-I levels on day 8 compared to the control group (corn oil) and TCDD-treated
animals at lower doses. In the highest dose animals, IGF-I levels continued to decline to 42% of
the control group by day 16 of the study. The IGF-I levels at the highest dose plateaued at an
average decrease of 66% through day 128 when compared to controls. Beginning at day 8, the
decrease in IGF-I was statistically significant at every time point through day 128 compared to
the control group, as well as groups treated with either 12.5 or 50 ng/kg-day TCDD. Similar
statistically significant decreases also were observed for the 800 ng/kg-day TCDD-treated groups
with an initial decrease of 37% on day 16 followed by a further decline to approximately 45%
thereafter compared to controls and the 12.5, 50, and 200 ng/kg-day dose groups. In contrast to
these results, circulating levels of insulin and glucose were unaffected by TCDD treatment, while

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the active or phosphorylated form of AMPK-a protein increased with dose as a result of TCDD
treatment.

A LOAEL for TCDD of 217 ng/kg-day for a 28-day exposure duration (because this
represented the most sensitive time for elicitation of effects) was identified in this study for
decreased body weight, significant (p < 0.05) inhibition of PEPCK activity, and reduced IGF-I
levels (42% lower than the control group). A NOAEL of 54.3 ng/kg-day was identified in this
study.

2.4.2.5.3. Hassoun et al. (2002, 543725).

Hassoun et al. (2002, 543725) examined the potential of TCDD and other dioxin-like
chemicals to induce oxidative stress in a chronic rat bioassay. Groups of six Harlan
Sprague-Dawley female rats were treated with 0, 3, 10, 22, 46, or 100 ng/kg-day TCDD
(98% purity), 5 days a week via gavage for 30 weeks. The administered doses adjusted for
continuous exposure were 0, 2.14, 7.14, 15.7, 32.9, and 71.4 ng/kg-day, respectively
(administered doses were multiplied by 5 and divided by 7). At study termination, hepatic and
brain tissues from all treated rats were divided into two portions and examined for the production
of reactive oxygen species and SSBs in DNA.

When compared to controls, there was a dose-dependent increase in the production of
superoxide anion in TCDD-treated animals ranging from 21-998%) and 66-257%) in hepatic and
brain tissues, respectively. Hepatic tissues had statistically significant (p < 0.05) increases in
superoxide anion production at doses >7.14 ng/kg-day, while the brain tissue had a statistically
significant (p < 0.05) increase over controls at all doses. Similarly, increases in lipid
peroxidation were observed in hepatic and brain tissues with a 481%> increase (p < 0.05) at
71.4 ng/kg-day in the hepatic tissue when compared to controls. The increase in lipid oxidation
in brain tissue ranged from 33-188%) (p < 0.05) in the 2.14-71.4 ng/kg-day dose groups. DNA
SSBs were also observed in both hepatic and brain tissue in all treated groups. When compared
to the control group, there was a dose-dependent statistically significant (p < 0.05) increase in
DNA SSBs ranging from 58-322%) and 29-137%) in hepatic and brain tissues, respectively.
Nonmonotonic dose-response relationships were observed for superoxide production and lipid
peroxidation in liver tissues, with greater-than-linear increases in effect between the two highest
dose levels.

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As stated above, because no adverse endpoints were measured, no LOAEL/NOAEL was
established. However, a LOEL for TCDD of 2.14 ng/kg-day for a 30-week exposure duration is
identified in this study for significant (p < 0.05) increases in superoxide anion, lipid peroxidation
production, and DNA SSBs in the liver and brain tissues. A NOEL cannot be determined for this
study.

2.4.2.5.4. Kociba et al. (1978, 001818).

Sprague-Dawley rats (50 per sex per treatment group) were administered TCDD (purity
>99%) in the diet at doses of 0, 1, 10, or 100 ng/kg-day for 2 years. Body weights and food
consumption were routinely measured. Hematology, clinical chemistry, and urinalysis were
measured after 3, 12, or 23 months of treatment. Animals were routinely palpitated for tumors.
Gross and histopathological exams were conducted on the tissues of dead or dying animals or at
terminal sacrifice. Specific organs also were weighed.

The high-dose females had a statistically significant (p < 0.05) increase in mortality
compared to the controls during the second half of the study. Mortality changes in males were
variable and of questionable toxicological significance. A significant (p < 0.05) reduction in
body weight occurred in the 100 ng/kg-day males and females beginning at 6 months. Mid-dose
females also had reduced body weight, but to a lesser degree during the same time frame. There
were no consistent changes in food consumption. The following significant (p < 0.05)
hematology changes were observed in the high-dose animals: decreased packed cell volume in
males after 3 months and in females after 1 year, decreased red blood cells in females after
1 year and in males at terminal sacrifice, decreased hemoglobin in males after 3 months and in
females after 1 year, and decreased total white blood cell count in females after 1 year. Changes
in clinical chemistry (p < 0.05) occurred only in high-dose females and consisted of an increase
in serum alkaline phosphatase and gamma glutamyl transferase. Significant changes in
urinalysis occurred only in females and included increased urinary coproporphyrin in the mid-
and high-dose groups, increased urinary uroporphyrin in the mid- and high-dose groups, and
increased urinary delta-amino-levulinic acid in the high-dose group. Significant (p < 0.05)
changes in relative organ weights were observed, including increased liver weight in mid- and
high-dose females and decreased thymus weight in high-dose females. Mid- and high-dose rats

showed hepatocellular degeneration and inflammatory and necrotic changes in the liver. Thymic

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and splenic atrophy were noted in high-dose females. An increase in non-neoplastic lung lesions
was noted in mid-dose females and high-dose males and females. High-dose females had an
increase in uterine changes. High-dose males had a significant (p < 0.05) increase in the
incidence of stratified squamous cell carcinomas of the tongue. High-dose males and females
had a significant (p < 0.05) increase in the incidence of squamous cell carcinomas of the hard
palate/turbinates.

The chronic (2-year) LOAEL is 10 ng/kg-day, based on the numerous significant
(p < 0.05) changes noted in coproporphyrin excretion (67% increase above control) and an
increase in liver and lung lesions in female rats. The NOAEL is 1 ng/kg-day.

2.4.2.5.5. Maronyot et al. (1993,198386).

An initiation-promotion study was performed in female Sprague-Dawley rats (8-10 rats
per group). Rats were initiated with saline or diethylnitrosamine (DEN), followed 2 weeks later
by promotion with biweekly administration of TCDD (purity not specified) in corn oil via
gavage for 30 weeks. The doses were stated to be equivalent to 3.5, 10.7, 35.7, or
125 ng/kg-day. Rats were sacrificed 7 days after the final treatment. A significant (p < 0.05)
decrease in body weight occurred in the 125 ng/kg-day group. A significant (p < 0.05) increase
in relative liver weight occurred in the 35.7 and 125 ng/kg-day groups. There was a significant
(p < 0.05) increase in the labeling index in the 125 ng/kg-day group, but only with DEN
initiation. In the TCDD-alone group, a 2-fold increase in labeling index occurred in the
125 ng/kg-day group that did not reach statistical significance. A significant (p < 0.05) trend for
increased alkaline phosphatase levels was observed in TCDD-treated animals, but despite a
50% increase in the highest dose group the increase was not statistically significant. Total
cholesterol and triglycerides were significantly (p < 0.05) higher in the

125 ng/kg-day TCDD-alone group. A significant (p < 0.05) increase in 5'-nucleotidase occurred
in the 35.7 and 125 ng/kg-day TCDD-alone groups. A dose-dependent increase in the incidence
and severity of liver toxicity as measured by microscopic lesions was observed.

The 30-week LOAEL is 35.7 ng/kg-day, based on a significant (p < 0.05) increase in
relative liver weight (12%, accompanied by increases in incidence and severity of liver lesions).
The 30-week NOAEL is 10.7 ng/kg-day.

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2.4.2.5.6.	National Toxicology Program (1982, 543764).

National Toxicology Program (NTP, 1982, 543764) conducted a carcinogenic bioassay of
TCDD on rats and mice. Fifty male and female Osborne-Mendel rats and male and female
B6C3F1 mice were treated twice per week with TCDD (purity not specified) in corn oil via oral
gavage at doses of 0, 5, 25, or 250 ng/kg for rats and male mice (1.4, 7.1, 71 ng/kg-day adjusted
for continuous exposure; administered doses multiplied by 2 and divided by 7) and 0, 20, 100, or
1,000 ng/kg for female mice (5.7, 28.6, or 286 ng/kg-day adjusted for continuous dosing;
administered doses multiplied by 2 and divided by 7) for 104 weeks. Seventy-five rats and mice
of each sex served as vehicle controls. One untreated control group of 25 rats and mice of each
sex was present in the TCDD treatment room and one untreated control group consisting of
25 rats and mice of each sex were present in the vehicle-control room. Animals surviving until
study termination were sacrificed at 105 or 108 weeks. A complete histopathological evaluation
was conducted on all animals.

Survival rates were not affected by TCDD exposure in rats or mice of either sex. Male
rats exhibited a dose-related depression in mean body weight after week 55, while the females
exhibited a dose-related body-weight depression after 45 weeks of TCDD exposure. However,
the magnitude of the body weight response is not indicated. Mean body weights in male and
female mice were comparable to the vehicle control group throughout the bioassay. Noncancer
histopathologic findings included increased incidences of liver lesions (termed toxic hepatitis)
from TCDD exposure, and were detected in the high-dose rats and high-dose mice of each sex.

A LOAEL for TCDD of 1.4 ng/kg-day for a 104-week exposure duration is identified for
increased incidences of liver lesions in mice of both sexes. A NOAEL cannot be determined for
this study.

2.4.2.5.7.	National Toxicology Program (2006,197605).

Female Sprague-Dawley rats (81 control; 82 treatment group) were administered TCDD
(purity >98%) in corn oikacetone (99:1) via gavage at doses of 0, 3, 10, 22, 46, or
100 ng/kg-day, 5 days per week for 105 weeks (0, 2.14, 7.14, 15.7, 32.9, or 71.4 ng/kg-day,
adjusted for continuous exposure) (NTP, 2006, 197605). In addition to this primary group, a
stop group of 50 animals was administered 100 ng/kg-day TCDD in corn oil:acetone (99:1) via
gavage for 30 weeks and then just the vehicle for the remainder of the study. Up to 10 rats per

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dose group were sacrificed and evaluated at 14, 31, or 53 (n = 8) weeks for biologically
noteworthy changes in the incidences of neoplasms or non-neoplastic lesions in the liver, lung,
oral mucosa, uterus, pancreas, thymus, adrenal cortex, heart, clitoral gland, ovary, kidney,
forestomach, bone marrow, mesentery gland, and pituitary gland. All interim sacrifice animals
also received a complete necropsy and microscopic examination, and the following organs were
weighed: the left kidney, liver, lung, left ovary, spleen, thymus (14 weeks only), and thyroid
gland. Out of 53 control animals and 53 or 54 animals per treatment group not used for interim
sacrifice analyses, at study termination the number of surviving animals had declined to 25 in the
control group and to 21, 23, 19, 22, and 21 in five treatment groups, respectively, due to
accidental deaths, moribund animals, or death due to natural causes.

Survival rate was not affected by TCDD treatment. Mean body weights in the high dose
primary study group and the 100 ng/kg stop group were less than the vehicle control group after
week 13 of the study. The mean body weights of animals in the 46 ng/kg-day group were less
than in the vehicle control at study termination (2 years), whereas animals in the 22 ng/kg-day
had lower mean body weights compared to controls during the last 10 weeks of study. In
addition to body weight changes, liver weights were also impacted as a result of TCDD
exposure. Absolute and relative liver weights were significantly (eitherp < 0.01 or p< 0.05)
higher in all dose groups compared to controls at the 14- and 31-week evaluation period, whereas
the relative liver weights were significantly (eitherp < 0.01 or p < 0.05) higher only at
>10 ng/kg-day at 53 weeks.

No clinical findings associated with TCDD treatment were observed. TCDD caused
changes in thyroid hormone levels at 14, 31, and 53 weeks. The following changes were
statistically significant (p < 0.05) compared to the vehicle control: decrease in TT4 at doses
>22 ng/kg-day at 14 and 31 weeks and at doses >46 ng/kg-day at 53 weeks; decrease in FT4 at
doses >22 ng/kg-day at 14 and 31 weeks; increase in total T3 at doses >46 ng/kg-day at 14 and
31 weeks and at doses >10 ng/kg-day at 53 weeks; and increase in TSH at doses >46 ng/kg-day
at 14 weeks. There was a statistically-significant (p < 0.05) increase in hepatocyte proliferation
at 14 weeks (22 ng/kg-day group only); 31 weeks (all doses); and 53 weeks (>46 ng/kg-day).
There were statistically significant (p < 0.01) dose-dependent increases in liver (includes EROD
[CYPlAl-associated] activity; 7-pentoxyresorufin-O-deethylase [PROD; CYP2B-associated]
activity; and acetanilide-4-hydroxylase [CYPlA2-associated] activity) and lung (EROD)

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cytochrome P450 enzyme activities in all treatment groups at all three evaluation periods
compared to the vehicle control group. The largest effect was an 82-fold induction of hepatic
EROD activity in the 46 ng/kg-day group at 31 weeks.

TCDD was detected at the greatest concentration in the liver, followed by fat tissue, with
tissue concentration increasing in both of these tissues in a dose-dependent manner. TCDD
tissue levels generally remained constant after the first measurement at week 14. Pathological
examination at week 14 revealed increased incidences of hepatocellular hypertrophy in animals
administered >10 ng/kg-day TCDD. Examinations at weeks 31 and 53 indicated that incidence
and or severity of hepatocellular hypertrophy was increased at all treatment doses although
incidences were statistically significant (p < 0.05) only at >10 ng/kg-day doses. The incidence of
non-neoplastic hepatic lesions (including inflammation, necrosis, multiple eosinophilic focus,
diffuse fatty change, pigmentation, toxic hepatopathy) in the liver increased at doses
>22 ng/kg-day beginning at 14 weeks. Severity of the lesions increased at 14 weeks at doses
>46 ng/kg-day and were also observed at lower dose levels during later evaluation periods (31
and 53 weeks). By terminal sacrifice, numerous non-neoplastic changes were noted in TCDD
treated rats, even at the lowest dose tested.

Noncancer cardiovascular and pulmonary effects were evident after 2 years of TCDD
exposure. Significantly increased incidences of minimal to mild cardiomyopathy were seen in
male and female rats at >10 ng/kg-day. In the lung, there was a significant (p < 0.01)
dose-dependent increase, when compared to the vehicle control, in the incidence of bronchiolar
metaplasia of the alveolar epithelium at all dose groups in the primary study.

A LOAEL for TCDD of 2.14 ng/kg-day adjusted dose for a 105-week exposure duration
is identified in this study for significantly (eitherp < 0.01 orp< 0.05) increased absolute and
relative liver weights, increased incidence of hepatocellular hypertrophy, and increased incidence
of alveolar to bronchiolar epithelial metaplasia. A NOAEL cannot be determined for this study.

2.4.2.5.8. Rier et al (2001,198776: 2001, 543773).

Female rhesus monkeys (8 per treatment group) were administered 0, 5, or 25 ppt TCDD
(purity not specified) in the diet for 4 years. Previously, Bowman et al. (1989, 543745)
determined that these dietary concentrations were equivalent to 0, 0.15, and 0.67 ng/kg-day,
respectively. Thirteen years after termination of TCDD treatment, serum concentrations of

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TCDD and dioxin-like polyhalogenated aromatic hydrocarbons (PHAH) were measured in
six control monkeys, six monkeys treated with 0.15 ng/kg-day, and three monkeys treated with
0.67 ng/kg-day (Rier et al., 2001, 1987761 Even after 13 years without treatment, there was
significantly (p < 0.05) elevated serum levels of TCDD and other dioxin-like compounds in
treated monkeys. There was a significant increase in triglycerides and total lipids in the serum of
monkeys treated with either 0.15 or 0.67 ng/kg-day, but not in cholesterol or phospholipids. In
addition to these 15 animals, 8 other female monkeys (4 treated with 0.67 ng/kg-day TCDD that
died 7 to 11 years after treatment and 4 lead-treated animals with no history of PHAH exposure)
were evaluated for endometriosis. Elevated serum concentrations of TCDD were not correlated
with endometriosis. Increased serum levels of 3,3',4,4'-tetrachlorobiphenyl (TCB), however,
were associated with the presence and severity of endometriosis (p < 0.05). TCB was found in
none of the animals without endometriosis, including TCDD-treated animals, nor was it found in
control animals with endometriosis. Animals with elevated serum levels of TCB,
pentachlorobiphenyl, and total serum analyte TCDD equivalents (TEQ) had an increased
incidence of endometriosis, but severity was associated only with increased levels of TCB. EPA
did not develop a LOAEL for TCDD for this study, because of DLC contamination.

In a separate study that evaluated the same 15 monkeys 13 years after exposure, Rier
et al. (2001, 543773) examined effects on systemic immunity. Peripheral blood mononuclear
cells (PBMC) obtained from untreated monkeys secreted no detectable levels of TNF-a in
response to T-cell mitogen exposure. There was, however, a significant (p < 0.05)
dose-dependent increase in TNF-a production in PBMC from the TCDD-treated monkeys.
Although PBMC from treated monkeys with endometriosis produced more TNF-a than cells
from unexposed controls without the disease (median 128 pg/mL compared to not detected;
p < 0.01), PBMC from TCDD-treated animals without endometriosis also produced more TNF-a
than controls (median 425 pg/mL, p < 0.067). TNF-a production from the animals without
endometriosis, however, was much more variable and was not statistically significant compared
to controls. In addition, there was a dose-related but statistically insignificant decrease in PBMC
cytotoxicity against natural killer-sensitive RAJI cells in TCDD-treated animals compared to the
unexposed controls. The results were again related to TCDD exposure and not the presence of
endometriosis. TCDD alone was not associated with changes in PBMC surface antigen
expression, but increased serum levels of TCDD. 1,2,3,6,7,8-Hexachlorodibenzofuran and

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3,3',4,4',5-pentachlorobiphenyl were correlated with increased numbers of CD3+/CD25- and
CD3-/CD25+ leukocytes, as well as increased secretion of TNF-a in response to T-cell mitogen
exposure. Although TNF-a production is considered to be a general indicator of inflammation,
relative adversity of increased TNF-a secreted by PBMCs in and of itself cannot be substantiated
in the absence of concurrent physiological measurements of an inflammatory response.

Therefore, neither a LOAEL nor NOAEL can be determined for this study.

2.4.2.5.9. Sewall et al (1993,197889).

Sewall et al. (1993, 197889) examined the impact of TCDD exposure on the hepatic
epidermal growth factor receptor (EGFR) as a critical effect in hepatocarcinogenicity. In
two separate experiments, groups of 6- to 8-week-old female Sprague-Dawley rats were
randomly assigned to the following groups: control group, receiving saline and corn oil; a
promoted group that received four different doses of TCDD along with saline; a DEN-only
initiated control group; and a DEN and TCDD initiated and promoted group that received
four different doses of TCDD. DEN was administered via intraperitoneal injection at a dose of
175 mg/kg [saline (S) vehicle] as the initiating agent to animals that were 70 days old. The
control animals received saline only. In the first experiment, each treatment group (S/TCDD and
DEN/TCDD) that included sham-operated or ovariectomized and intact animals were treated
with TCDD (purity >98%) at 125 ng/kg-day. In the second dose-response experiment,
DEN-initiated and saline control treatment groups (intact animals, 84 days old) were
administered TCDD (purity >98%) in corn oil via oral gavage once every 2 weeks for 30 weeks
at doses equivalent to 0, 3.5, 10.7, 35.7, or 125 ng/kg-day (n = 9). A week after the last
treatment, all animals were sacrificed and livers were harvested and fixed for
immunohistochemistry. Sections of the fixed liver were tested for EGFR binding, EGFR
autophosphorylation, immunolocalization of EGFR, and hepatic cell proliferation.

In the first experiment, intact animals treated with 125 ng/kg-day TCDD exhibited a
65%) reduction in EGFR binding capacity. In contrast, the EGFR equilibrium maximum binding
capacity (Bmax) of the ovariectomized rats was not statistically different from the ovariectomized
control rats, and no changes in the Kd were detected in any treatment group. In the
dose-response experiment with intact animals, a significant (p < 0.05) TCDD dose-dependent
decrease in the Bmax of EGFR was shown. A two-factor, five-level ANOVA indicated that the

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effect of TCDD exposure on EGFR Bmax was significant (p = 0.0001), whereas, the effect of
DEN treatment on EGFR Bmax was not significant. Comparative analysis using Fisher's
protected least significant difference indicated that the lowest TCDD dose resulting in a
statistically significant (p < 0.05) decrease in the EGFR Bmax was 10.7 ng/kg-day S/TCDD
group. At the highest TCDD dose of 125 ng/kg-day, the EGFR Bmax was reduced by 38%
compared to controls in both the DEN initiated and noninitiated groups. A two-factor, five-level
ANOVA showed no significant effect on EGFR Kd in either the DEN- or the TCDD-treated
groups. The EGFR autophosphorylation assay indicated that, with increasing TCDD dose, the
amount of EGFR autophosphorylation in DEN/TCDD-treated animals decreased. The study
authors state that this decrease is similar to the dose-response alterations observed for the EGFR
Bmax. Additionally, EGFR autophosphorylation in control and 125 ng/kg-day noninitiated
animals was similar to the corresponding dose levels for the DEN-treated animals, suggesting
that DEN treatment did not affect the EGFR or the EGFR response to TCDD under the
experimental conditions. The immunolocalization assay indicated that staining was more
apparent in the centrilobular and midzonal regions of the liver in the DEN initiated control
animals, whereas, the amount of hepatocyte plasma membrane staining in DEN/TCDD treated
animals substantially decreased. The cell proliferation assay showed a decrease in the cell
labeling index in the 3.5 ng/kg-day DEN/TCDD dose group that was statistically less (p < 0.05)
than the labeling index for the control group. In contrast, the labeling index for the
125 ng/kg-day DEN/TCDD treatment group was significantly (p < 0.05) higher compared to
controls. Except for the low-dose (3.5 ng/kg-day) group, a clear dose-response trend
(two mid-level doses were not statistically significant) was observed in the other three TCDD
treated groups.

The role of EGFR in TCDD-mediated hepatotoxicity is unknown, and as such, this
endpoint cannot be unequivocally linked to TCDD-induced hepatotoxicity nor labeled as
adverse. Thus, no LOAEL/NOAEL was established. A LOEL for TCDD of 3.5 ng/kg-day for a
30-week exposure duration was identified in this study for a significant (p = 0.0001 using
ANOVA) decrease in EGFR Bmax levels. A NOEL cannot be determined for this study.

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2.4.2.5.10. Sewall et al (1995,198145).

Sevvall et al. (1995, 198145) studied the dose-response relationship for thyroid function
alterations in female rats as a result of TCDD exposure. Groups of female Sprague-Dawley rats
were initiated with DEN at 70 days of age at a dose of 175 mg/kg in a saline vehicle via an i.p.
injection. DEN was administered as a liver-initiating agent for a concurrent study to determine
TCDD promotion of hepatic preneoplastic foci. Saline-treated animals served as controls. At
84 days of age, both the DEN-initiated and the saline-noninitiated groups of animals were
administered TCDD (purity >98%) or corn oil vehicle via oral gavage once every 2 weeks for
30 weeks at dose levels equivalent to 0, 0.1, 0.35, 1.0, 3.5, 10.7, 35.7, or 125 ng/kg-day (n = 9
per group). One week after the last TCDD treatment, the animals were sacrificed and the thyroid
was removed and fixed for further analysis. Blood was drawn from the abdominal aortic vein,
and the serum was isolated and preserved for hormone analysis. Liver was also removed and
prepped for further analysis. Thyroid hormone analysis was performed to determine serum TSH,
T3, and T4 levels using radioimmunoassay kits. Histological examination was conducted on
eosin-stained sections of the thyroid tissue. RNA level in the hepatic tissue was determined
using a reverse transcription polymerase chain reaction (RT-PCR) technique.

TCDD treatment did not affect thyroid weight. A dose-dependent decrease in serum
T4 levels was observed in both noninitiated and DEN-initiated animals with T4 levels dropping
significantly (p < 0.05) at the 35 and 125 ng/kg-day TCDD doses in the noninitiated group.
Compared to the noninitiated control group, DEN alone did not significantly affect T4 levels.
Serum T3 level in the 125 ng/kg-day treatment group was slightly elevated but was not
significantly different from levels in the control group. TSH levels in DEN initiated rats were
increased at a dose of 3.5 ng/kg-day. In the noninitiated group, TSH level in the 125 ng
TCDD/kg-day group was 3.27 ± 0.34 ng/mL (n = 9) compared to 1.3 ± 0.18 ng/mL in the corn
oil control group (n = 7). This result, in conjunction with the T4 data, demonstrates that TCDD
had a similar effect on thyroid hormone levels in both the noninitiated and DEN initiated groups.
Histological sections examined for nodular lesions or neoplasms exhibited thyroid follicular
adenoma in one DEN/corn oil control animal. The DEN/TCDD-treated animals exhibited
diffuse follicular hyperplasia, with the size of colloidal follicles decreasing with TCDD
treatment. Other qualitative DEN/TCDD-related changes included increased frequency of
abnormally shaped follicles. The study authors reported that image analysis demonstrated a

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significant (p = 0.013) TCDD dose-related decrease in mean follicle size along with a significant
(p = 0.001) TCDD dose-related increase in parenchymal area. Additionally, like T4 and TSH
levels, DEN treatment alone or in combination with TCDD did not influence thyroid follicular or
C-cell morphology.

RT-PCR results for UGT1 and CYP1A1 mRNA levels indicated that the amount of
UGT1 mRNA at the 125 ng/kg-day dose was approximately 2.5-fold higher compared to the
concurrent controls. The study authors also stated that the maximal response for the UGT1
mRNA levels was reached at a dose between 1.0 and 3.5 ng TCDD/kg-day. In contrast, the
maximum induction of CYP1A1 mRNA was 260-fold higher at the 125 ng/kg-day compared to
the concurrent controls.

A LOAEL for TCDD of 35 ng/kg-day for a 30-week exposure duration was identified in
this study for a significant (p < 0.05) decrease in T4 levels. The NOAEL for this study is
10.7 ng/kg-day.

2.4.2.5.11. Toth etal. (1979,197109).

Toth et al. (1979, 197109) examined the impact of TCDD exposure on the formation of
liver tumors in male mice. Ten-week-old, outbred Swiss/H/Riop male mice were administered
sunflower oil or TCDD (purity not specified; in sunflower oil) at 0, 7, 700 or 7,000 ng/kg (0, 1,
100, or 1,000 ng/kg-day adjusted for continuous dosing; administered dose divided by 7; n = 38,
44, 44, and 43, respectively) once per week via gastric tube for 1 year. Once exposure had
ceased, animals were followed for the rest of their lives. After spontaneous death or when mice
were moribund, autopsies were performed and all organs were examined histologically.

Average life span in the 1,000 ng/kg-day dose group decreased considerably (72%) when
compared to the control group. TCDD also caused dose-dependent, severe chronic and ulcerous
skin lesions (12, 30, and 58% in the 1, 100, and 1,000 ng/kg-day dose groups, respectively) that
was followed by generalized lethal amyloidosis (12, 23, and 40% in the 1, 100, and
1,000 ng/kg-day dose groups, respectively).

A LOAEL for TCDD of 1 ng/kg-day for 1-year exposure duration was identified in this
study for severe chronic and ulcerous skin lesions (12% higher than controls), and generalized
lethal amyloidosis (12% higher than controls). A NOAEL cannot be determined for this study.

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2.4.2.6. Chronic Studies (Cancer Endpoints)

2.4.2.6.1. Delia Porta et al. (1987,197405).

Delia Porta et al. (1987, 197405) studied the long-term carcinogenic effects of TCDD in
B6C3F1 (C57BL/6JDp x C3Hf/Dp) mice. Six-week-old male and female mice (initially about
15/sex/dose, and increased by approximately 30 to 40 per group within a few weeks) were
administered 0, 2,500, and 5,000 ng/kg TCDD (purity not provided) in corn oil by oral gavage
once per week for 52 weeks (0, 357, and 714 ng/kg-day adjusted for continuous exposure). At
ages 31 to 39 weeks, 41 male mice and 32 female mice in the 2,500 ng/kg dose group were
mistakenly administered a single dose of 25,000 ng/kg TCDD. TCDD treatment for the
2,500 ng/kg dose group was halted for 5 weeks (beginning the week after the 25,000 ng/kg dose
was administered in error) and resumed until exposure was terminated at 57 weeks. Mortality
was observed and body weights recorded at unspecified intervals until 110 weeks of age, when
all surviving animals were sacrificed and necropsied. Histopathological analysis was conducted
on the following organs and tissues: Harderian glands, pituitary, thyroid, adrenals, tongue,
esophagus, and trachea; lungs, liver, pancreas; spleen, kidneys, and bladder; testes, ovaries, and
uterus, mesenteric lymph nodes, small intestine, and all other organs with presumed pathological
changes.

Body weights of both male and female mice exposed to 2,500 and 5,000 ng/kg TCDD
were markedly lower than in the corresponding control groups (statistical significance not
reported). Relative to the controls, a significant (p < 0.001), dose-related decrease in survival
occurred in animals treated with either dose of TCDD. In the subset of animals treated
inadvertently with a single dose of 25,000 ng/kg TCDD, mortality in male mice increased shortly
after this treatment; females, however, did not show a mortality increase following the
inadvertent treatment. This mortality in male mice was associated with subcutaneous edema,
degenerative hepatocyte changes, and bile duct hyperplasia. The incidence of non-neoplastic
lesions (such as amyloidosis of the liver, spleen, adrenals, and pancreas), liver necrosis, and
nephrosclerosis, was increased in mice exposed to TCDD compared to controls (statistical
significance not reported).

The study authors used two statistical tests to analyze tumor incidence. Because of the
increased mortality in treated groups compared to controls, one test, which assumes all tumors
are fatal, overestimated the differences between the treated and control groups. The second test

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assumes that all tumors are incidental and resulted in an underestimation of TCDD effects. Both
tests were used to analyze the results for nonthymic lymphomas and hepatic adenomas and
carcinomas. Incidence of nonthymic lymphomas (6/45, 4/51, and 3/50 in the 0, 2,500, and
5,000 ng/kg dose groups, respectively in males and 17/49, 21/42, and 17/48 in the 0, 2,500, and
5,000 ng/kg dose groups, respectively in females) was significantly (p < 0.05 in males and
p < 0.01 in females) higher in TCDD-treated animals compared to the corresponding controls
using the fatal tumor test. However, the incidental tumor test showed that this higher incidence
was not significant. Similarly, a significantly (p < 0.001) higher incidence of hepatocellular
adenomas occurred in male mice using the fatal tumor test (10/43, 11/51, and 10/50 in the 0,
2,500, and 5,000 ng/kg dose groups, respectively), but the incidence was not significant when
assessed using the incidental tumor test. Hepatocellular carcinomas in males were significant
(p < 0.001) using either the fatal or incidental tumor tests (5/43, 15/51, and 33/50 in the 0, 2,500,
and 5,000 ng/kg dose groups, respectively). In female mice, hepatocellular adenomas were
significant using both the fatal (p < 0.01) and incidental (p < 0.001) tumor tests (2/49, 4/42, and
11/48 in the 0, 2,500, and 5,000 ng/kg dose groups, respectively). Similar results for female
mice were obtained for incidence of hepatocellular carcinomas (1/49, 12/42, and 9/48 in the 0,
2,500, and 5,000 ng/kg dose groups, respectively), which also were significant using both the
fatal (p < 0.01) and incidental (p < 0.05) tumor tests. TCDD-related incidences of other tumor
types in both sexes were uniformly low and comparable in the treatment and control groups.

These results indicate that TCDD is carcinogenic in male and female B6C3F1 mice,
causing hepatocellular adenomas and carcinomas in both sexes.

In addition to the long term bioassay results in mice described by Delia Porta et al. (1987,
197405). carcinogenic effects of TCDD in a neonatal bioassay were reported in the same
publication. Briefly, groups of male and female B6C3F1 and B6CF1 (C57/BL6J x BALB/c)
mice were treated with 0, 1000, 30,000 or 60,000 ng/kg BW TCDD via intraperitoneal (i.p.)
injection beginning at postnatal day 10. Animals were treated once weekly for 5 weeks and then
observed until 78 weeks of age. However, because this study utilized i.p. injection as the route
of TCDD exposure, it does not qualify for further consideration based on the study selection
criterion that the study design consist of orally administered TCDD.

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2.4.2.6.2. Kociba et al (1978, 001818).

As discussed above, Kociba et al. (1978, 001818) conducted a lifetime (2-year) feeding
study of male and female Sprague-Dawley rats using doses of 0, 1, 10, and 100 ng/kg-day.

There were 50 males and 50 females in each group.

With respect to the cancer endpoints examined, the most significant finding was an
increase in hepatocellular hyperplastic nodules and hepatocellular carcinomas in female rats.
The incidence of hepatocellular carcinomas was significantly elevated above the control
incidence at the 100 ng/kg-day dose, whereas increased incidence of hyperplastic nodules was
evident in the 10 ng/kg-day dose group.

There have been two reevaluations of slides of liver sections from the Kociba et al. study
(Goodman and Sauer, 1992, 197667; Sauer, 1990, 198829; Squire, 1990, 548781). The Squire
Review was requested by EPA as an independent review of the slides. The Sauer Review was
carried out using refined criteria for the diagnosis of proliferative hepatocellular lesions
(Maronpot et al., 1986, 013967; Maronpot et al., 1989, 548778). Liver tumor incidences for the
three evaluations are compared in Appendix F. Although there are some quantitative differences
between the evaluations, the lowest detectable effect for liver tumor incidence is consistently
observed at 10 ng/kg-day.

In the 10 ng/kg-day dose group, significant increases in the incidence of hyperplastic
nodules of the liver were observed in female rats (18/50 in the Kociba evaluation, 27/50 in the
Squire evaluation). Two females (2/50) had hepatocellular carcinomas. In the 1990 reevaluation
(Goodman and Sauer, 1992, 197667; Sauer, 1990, 198829), nine females (9/50) were identified
with hepatocellular adenomas and none with carcinomas; thus only one-third of the previously
observed "tumors" were identified when using the refined diagnostic criteria. As discussed
below, the tumor reclassification of Goodman and Sauer (1992, 197667) was used in the
dose-response modeling for the Kociba et al. (1978, 001818) data set.

In addition to nodules in the liver, increased incidence of stratified squamous cell
carcinoma of the tongue and nasal turbinates/hard palate, and keratinizing squamous cell
carcinoma of the lung were also observed in female rats in the 100 ng/kg-day dose group.
One possible cause for the induction of lung tumors in the Kociba feeding study may have been
the aspiration of dosed feed into the lungs. However the promotion of lung tumors has been
observed in mice treated systemically by intraperitoneal (i.p.) injections of TCDD (Beebe et al.,

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1995, 548754). In addition the induction of hyperplastic and metaplastic lesions in rats has been
observed following chronic oral gavage treatment with TCDD (Tritscher et al., 2000, 197265).
More recently, chronic oral exposure to HCDD resulted in the induction of lung tumors in treated
female rats (Rozman, 2000, 548758). These data indicate that the induction of lung tumors in
the Kociba was most likely primarily the result of systemic chronic dietary exposure to TCDD
rather than due to a localized exposure to aspired dosed feed.

There was no detectable increase in liver tumor incidences in male rats in any of the dose
groups. The mechanism responsible for dioxin-mediated sex specificity for
hepatocarcinogenesis in rats is not clear, but may involve ovarian hormones (Lucier et al., 1991,
199007).

Although there was no increase in liver tumors in male rats in this study, in the
100 ng/kg-day group, there was an increased incidence of stratified squamous cell carcinoma of
the hard palate/nasal turbinate, stratified squamous cell carcinoma of the tongue, and adenoma of
the adrenal cortex.

Kociba et al. (1978, 001818) had reported that chemically related increases in
preneoplastic or neoplastic lesions were not found in the 1 ng/kg-day dose group. However,
Squire identified two male rats in the 1 ng/kg-day dose group with squamous cell carcinoma of
the nasal turbinates/hard palate, and one of these male rats had a squamous cell carcinoma of the
tongue. These are both rare tumors in Sprague-Dawley rats, and these sites are targets for
TCDD, implying that 1 ng/kg-day may not represent a NOEL. However, no dose-response
relationships were evident for tumors at these sites (Huff et al., 1991, 197981)

There is considerable controversy concerning the possibility that TCDD-induced liver
tumors are a consequence of cytotoxicity. Goodman and Sauer (1992, 197667) have extended
the reevaluation of the Kociba slides to include liver toxicity data and have reported a correlation
between the presence of overt hepatotoxicity and the development of hepatocellular neoplasms in
female rats. With the exception of two tumors in controls and one each in the low- and mid-dose
groups, all liver tumors occurred in livers showing clear signs of toxicity. However, male rat
livers exhibit cytotoxicity in response to high TCDD doses, yet they do not develop liver tumors.
Moreover, both intact and ovariectomized female rats exhibit liver toxicity in response to TCDD,
yet TCDD is a more potent promoter in intact but not ovariectomized rats (Lucier et al., 1991,
199007). Therefore, if cytotoxicity is playing a role in liver tumorigenesis, other factors must

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also be involved. Also, there is little information on the role of cytotoxicity in TCDD-mediated
cancer at other sites such as the lung and thyroid.

2.4.2.6.3.	Toth et al. (1979,197109).

In a study of 10-week-old outbred male Swiss/H/Riop mice, Toth et al. (1979, 197109)
administered oral gavage TCDD doses of 0, 7, 700, and 7,000 ng/kg-day in sunflower oil weekly
for 1 year (0, 1, 100, or 1,000 ng/kg-day adjusted for continuous dosing; see details above). All
mice (100/group) were followed for their entire lives. The study authors identified the effective
number of mice in each group to be the number of surviving animals when the
first tumor-bearing animal was identified. The average lifespan of the control, low, mid and high
dose groups was 588, 649, 633, and 424 days, respectively.

In the 100 ng/kg-day dose group, liver tumor incidence was twice that of the control
group and was statistically significant (p < 0.01%). A dose-related increase in liver tumor
incidence was observed (18, 29, 48, and 30% in the control and three TCDD-treated groups,
respectively) in all treated mice. Increases were not statistically significant, however, at 1 and
1,000 ng/kg-day. The study authors also stated that spontaneous and induced liver tumors were
not histologically different. Additionally, the ratio of benign hepatomas to hepatocellular
carcinomas in the control group was not affected by treatment and an increase was observed only
in the absolute number of liver tumors. Cirrhosis was not observed with the tumors.

2.4.2.6.4.	NTP (1982, 543764).

As discussed above, the NTP (1982, 543764) study was conducted using
Osborne-Mendel rats and B6C3F1 mice (NTP, 1982, 543764). Groups of 50 male rats,

50 female rats, and 50 male mice received TCDD as a suspension in corn oil:acteone (9:1) by
gavage twice each week at doses of 0, 5, 25, or 250 ng/kg-day (daily averaged doses of 0, 1.4,
7.1, or 71 ng/kg-day for rats and male mice and doses of 0, 5.7, 28.6, or 286 ng/kg-day for
female mice.

There were no statistically significant dose-related decreases in survival in any
sex-species group. TCDD-induced malignant liver tumors occurred in the high-dose female rats
and in male and female mice. These can be considered to result from TCDD exposure because
they are relatively uncommon lesions in control Osborne-Mendel rats (male, 1/208; female,

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3/208), are seen in female rats and mice of both sexes, and their increasing incidence with
increasing dose is statistically significant (Cochran-Armitage trend test,/? = 0.004). Because
liver tumors were increased in both sexes of mice, this effect is not female-specific as was
observed in rats. Interestingly, liver tumor incidences were decreased in female rats in both the
NTP and Kociba low doses (not statistically significant compared with controls). For example,
the combined control incidence data were 11/161 (7%) compared with 4/99 (4%) in the low-dose
group.

The incidences of thyroid gland (follicular cell) tumors were increased in all three dose
groups in male rats. Because the responses in the two highest dose groups are highly significant,
the statistically significant elevation of incidence in the lowest dose group (Fisher exact
p-walue = 0.042) is considered to be caused by exposure to TCDD, suggesting that thyroid tumor
incidence may be the most sensitive site for TCDD-mediated carcinogenesis. Because
71 ng/kg-day is above the maximum tolerated dose (MTD) (Huff et al., 1991, 197981). thyroid
tumors occur at doses more than 50 times lower than the MTD.

TCDD-induced neoplasms of the adrenal gland were observed in the 7.1 ng/kg-day/dose
group in male rats and in high-dose female rats. Fibrosarcomas of the subcutaneous tissue were
significantly elevated in high-dose female mice and female rats. One additional tumor type,
lymphoma, was seen in high-dose female mice. Lung tumors were elevated in high-dose female
mice; the increase was not statistically significant when compared with concurrent controls, but
the increase was dose related (Cochran-Armitage trend test,/? = 0.004).

Huff (1992, 548757) concluded, based on the NTP bioassay results, that TCDD was a
complete carcinogen and induced neoplasms in rats and mice of both sexes. As was observed in
the Kociba study (1978, 001818). liver tumors were observed with greater frequency in treated
female rats, but in male rats the thyroid appears to be the most sensitive (increased tumor
incidence at doses as low as 1.4 ng/kg-day).

2.4.2.6.5. NTP (2006.197605).

As discussed above, female Sprague-Dawley rats (53 control; 53 or 54 animals per
treatment group) were administered TCDD (purity >98%) in corn oil:acetone (99:1) via gavage
at doses of 0, 3, 10, 22, 46, or 100 ng/kg-day, 5 days per week for 105 weeks (0, 2.14, 7.14, 15.7,
32.9, or 71.4 ng/kg-day, adjusted for continuous exposure) (NTP, 2006, 197605). In addition to

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this primary group, a stop-dose group of 50 animals was administered 100 ng/kg-day TCDD in
corn oil:acetone (99:1) via gavage for 30 weeks and then just the vehicle for the remainder of the
study. At study termination, the number of surviving animals had declined to 25 in the control
group and to 21, 23, 19, 22, and 21 in five treatment groups, respectively, due to accidental
deaths, moribund animals, or death due to natural causes.

Incidence of hepatocellular adenomas was significantly (p < 0.001) increased in the
100 ng/kg-day dose group in the primary study and exceeded incidences seen in historical
vehicle control range at study termination. A dose-related increase in the incidence of
cholangiosarcoma was seen in the primary study group in animals receiving 22 ng/kg-day or
higher doses of TCDD. The high dose group of 100 ng/kg-day had the highest incidence of
cholangiosarcoma with a significant (p < 0.001) number of animals exhibiting multiple
cholangiosarcomas. Such an incidence was not seen in historical vehicle controls. In contrast,
only two cholangiosarcomas and hepatocellular adenomas were seen in the 100 ng/kg-day group
in the stop-exposure study.

In the lung, at 2 years, there was a significantly (p = 0.002) increased incidence of cystic
keratinizing epithelioma in the 100 ng/kg-day dose group of the primary study, while there were
no epitheliomas in the 100 ng/kg-day group of the stop-exposure study. There was also a
significant (p < 0.01) dose-dependent increase, when compared to the vehicle control, in the
incidence of bronchiolar metaplasia of the alveolar epithelium at all dose groups in the primary
study. Squamous metaplasia was also present in the 46 and 100 ng/kg-day dose groups in the
primary study, and was also observed in the 100 ng/kg-day dose group in the stop-exposure
study.

A positive trend in the incidence of gingival squamous cell carcinoma of the oral cavity
was seen at all doses (except 22 ng/kg-day), with the incidence significantly (p = 0.007) high in
the 100 ng/kg-day dose group. In addition, the occurrence of this lesion in the 46 and
100 ng/kg-day group of the primary study and 100 ng/kg-day group of the stop-exposure study
exceeded the historical control range. The incidence of gingival squamous hyperplasia was
significantly (either p < 0.01 or p< 0.05) increased in all dose groups of the primary study as
well as the 100 ng/kg-day group of the stop-exposure study.

In the uterus, at 2 years, there was a significantly (p = 0.032) higher rate of squamous cell
carcinoma in the 46 ng/kg-day group compared to vehicle controls. In addition there were

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two squamous cell carcinomas in the 100 ng/kg-day group of the stop-exposure study. No
squamous cell carcinomas have been reported in historical vehicle controls.

These results indicate that TCDD is carcinogenic to female Sprague-Dawley rats and
causes tumors at multiple sites.

2.4.3. Summary of Key Data Set Selection for TCDD Dose-Response Modeling

To meet the NAS' concerns regarding transparency and clarity in the identification of
TCDD studies for dose-response assessment, EPA has, in this section, developed and applied
two sets of criteria for animal bioassays and epidemiologic studies. EPA has collected and
evaluated these studies, including studies from the 2003 Reassessment and newer studies found
via literature searches and through public submissions. Tables 2-4 and 2-5 contain the final lists
of key cancer and noncancer studies, respectively, that have met EPA's inclusion criteria for
epidemiologic data. Tables 2-6 and 2-7 provide the final lists of key studies that have met EPA's
inclusion criteria for animal bioassay data for cancer and noncancer studies, respectively.
Collectively, these four tables contain the final set of key studies that EPA has used to develop
noncancer and cancer dose-response assessments for TCDD in Sections 4 and 5 of this
document, respectively. In Sections 4 and 5, additional evaluations are made to determine which
study/endpoint data sets are the most appropriate for development of the RfD and OSF for
TCDD, using statistical criteria, dose-response modeling results and decisions regarding
toxicological relevance of the endpoints. The approaches taken to select the final candidate
study/endpoint data sets are discussed in Sections 4 and 5 and are illustrated in Figures 4-1, 4-2
and and 5-3 of those sections.

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1	Table 2-1. Summary of epidemiological cancer studies (key characteristics)

2

Publication

Length of
follow-up

Latency period

Half-life for TCDD

Fraction of TEQs
accounted for by TCDD

NIOSH cohort studies

Fingerhut et al.
(1991.197375)

1942-1987

0, 20 years

N/A

N/A

Steenland et al.
(1999.197437)

1942-1993

0, 15 years

N/A

N/A

Steenland et al.
(2001,197433)

1942-1993

0, 15 years

8.7 years (Michalek et al.,
1996, 198893)

TCDD accounted for all
occupational TEQ; 10% of
background

Cheng et al.
(2006.523122)

1942-1993

0, 10, 15 years

8.7 years (Michalek et al.,
1996. 198893). and CADM
(Avlward et al.. 2005. 197114)

N/A

Collins et al.
(2009.197627)

1942-2003

None

7.2 years (Flesch-Janys et al.,
1996.197351)

N/A

BASF cohort studies

Thiess et al.
(1982. 064999)

1953-1980

None

N/A

N/A

Zoberetal.
(1990,197604)

1953-1987

Years since first
exposure: 0-9,
10-19, and 20+

N/A

N/A

Ott and Sober
(1996.198101)

1953-1991

None

5.8 years

N/A

Hamburg cohort studies

Manz et al.
(1991.199061)

1952-1989

None, used
duration of
employment
(<20, >20 years)

N/A

N/A

Flesch-Janys et
al. (1995,

197261)

1952-1992

None

7.2 years

Flesch-Janys et al. (1994,
197372)

Mean TEQ without TCDD
was 155 ng/kg; mean TEQ
with TCDD was 296.5 ng/kg

Flesch-Janys et
al. (1998,
197339)

1952-1992

None

7.2 years Flesch-Janys et al.
(1996. 197351). also used
decay rates that were function
of age and fat composition

Mean concentration of
TCDD was 101.3 ng/kg; for
TEQ (without TCDD) mean
exposure was 89.3 ng/kg



Becher et al.
(1998,197173)

1952-1992

0, 5, 10, 15 and
20 years

7.2 years Flesch-Janys et al.
(1996.197351)took into
account age and fat
composition

Not described

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Table 2-1. Summary of epidemiological cancer studies (key characteristics)
(continued)

Publication

Length of
follow-up

Latency period

Half-life for TCDD

Fraction of TEQs
accounted for
by TCDD

Seveso cohort studies

Bertazzi et al. (2001,
197005)

1976-1996

Periods

postexposure: 0,
0-4, 5-9,
10-14, 15-19
years

N/A

N/A

Warner et al. (2002,
197489)

1976-1998

None

8 years (Pirkle et al.,
1989.197861)

N/A

Pesatori et al. (2003,

197001)

1976-1996

Period

postexposure:
20 years

N/A

N/A

Baccarelli et al. (2006,
197036)

1976-1998

Period

postexposure:
22 years

N/A

N/A

Consonni et al. (2008,

524825)

1976-2001

Periods

postexposure: 0,
0-4, 5-9,
10-14, 15-19,
20-24 years

N/A

N/A

Chapaevsk cohort studies

Revich et al. (2001,
199843)

Cross-

sectional

study

(1995-1998)

N/A

N/A

N/A

Ranch Hand cohort studies

Akhtar et al. (2004,
197141)

1962-1999

None

N/A

N/A

Michalek and Pavuk
(2008,199573)

1962-2004

None, but
stratified by
period of service

7.6 years

N/A

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Table 2-1. Summary of epidemiological cancer studies (key characteristics)
(continued)

Publication

Length of
follow-up

Latency period

Half-life for TCDD

Fraction of TEQs
accounted for
by TCDD

New Zealand cohort studies

t'Mannetje et al. (2005,
197593)

1969-2000

(herbicide

producers);

1973-2000

(herbicide

sprayers)

N/A

N/A

N/A

McBride (2009,
198490)

1969-2004

None

N/A

N/A

McBride et al. (2009,
197296)

1969-2004

None

7 years

N/A

Dutch cohort study

Hoooiveld et al. (1998,

197829)

1955-1991

Periods
postexposure:
0-19 years, >19
years

7.1 years

N/A

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Table 2-2. Epidemiological cancer study selection considerations and criteria









Exposure





















assessment

















Risk



methodology
clear and









Effective dose
& oral





Methods
use to

estimates are
not



adequately
characterizes

Study size
and follow-



Published



exposure
estimable &





ascertain
health

susceptible
to biases

Association
between

individual-
level

up large
enough to



in peer-
reviewed

Exposure
primarily

consistent w/
current





outcomes

were
unbiased.

from
confounding
exposures or

TCDD and

adverse
health effect.

exposures.
Limitations
and

yield precise
estimates of
risk and



literature
with
appropriate

TCDD and
quantified so
that dose-

biological
understanding.
Latency and





highly
sensitive

and
specific.

from study
design or
statistical
analysis.

with
exposure-
response
relationship.

uncertainties
in exposure
assessment
considered.

ensure
adequate
statistical
power.



discussion
of

strengths,
limitations.

response
relationship
can be
assessed.

appropriate
window(s) of
exposure
examined.

Pass for

dose-
response
analyses?

Cancer

Considerations



Criteria

Y/N

NIOSH Cohort Studies





















Fineerhut et al. (1991. 197375)





















all cancer sites, site-specific analyses

a/

X

X

X

a/



a/

X

a/

N

Steenland et al. (1999. 197437)





















all cancer sites combined, site-specific analyses

a/

a/

a/

a/

a/



a/

a/

a/

Na

Steenland et al. (2001. 197433)





















all cancer sites combined

V

a/

a/

a/

V



V

a/

V

Y

Chens etal. (2006. 523122)





















all cancer sites combined

V

V

V

V

V



V

V

V

Y

Collins et al. (2009. 197627)





















all cancer sites combined, site-specific analyses

V

V

V

V

V



V

V

V

Y

BASF Cohort Studies





















Thiess etal. (1982. 064999)





















all cancer sites combined, site-specific analyses

V

X

X

X

X



V

X

X

N

Zoberetal. (1990. 197604)





















all cancer sites combined, site-specific analyses

V

a/

X

X

X



V

X

X

N


-------
Table 2-2. Epidemiological cancer study selection considerations and criteria (continued)



Methods

use to
ascertain

health
outcomes

were
unbiased,
highly
sensitive

and
specific.

Risk
estimates are

not
susceptible
to biases
from
confounding
exposures or
from study
design or
statistical
analysis.

Association
between
TCDD and

adverse
health effect,
with
exposure-
response
relationship.

Exposure
assessment
methodology
clear and
adequately
characterizes
individual-

level
exposures.
Limitations

and
uncertainties
in exposure
assessment
considered.

Study size
and follow-
up large
enough to
yield precise
estimates of
risk and
ensure
adequate
statistical
power.

Published
in peer-
reviewed
literature
with
appropriate
discussion
of

strengths,
limitations.

Exposure
primarily
TCDD and
quantified so
that dose-
response
relationship
can be
assessed.

Effective dose
& oral
exposure
estimable &
consistent w/
current
biological
understanding.
Latency and
appropriate
window(s) of
exposure
examined.

Pass for

dose-
response
analyses?

Cancer

Considerations

Criteria

Y/N

Ott and Zober (1996. 198101)
all cancer sites combined

V

V

V

V

V

V

V

V

Y

Hamburg Cohort



















Manzetal. (1991. 199061)
all cancer sites combines, site-specific analyses

a/

a/

a/

a/

a/

a/

X

a/

N

Flesh-Janvs et al. (2006. 197621)
all cancer sites combined

a/

a/

a/

a/

a/

a/

a/

X

N

Flesh-Janvs et al. (1998. 197339)
all cancer sites combined, site-specific analyses

V

V

V

V

V

V

V

a/

Nb

Becher et al. (1998. 197173)
all cancer sites combined

V

V

V

V

V

V

V

V

Y

Seveso Cohort



















Bertazzi et al. (2001. 197005)
all cancer sites combined, site-specific analyses

a/

a/

a/

X

a/

a/

X

X

N

Pesatori et al. (2003. 197001)
all cancer sites combined, site-specific analyses

V

V

X

X

V

V

X

X

N


-------
Table 2-2. Epidemiological cancer study selection considerations and criteria (continued)









Exposure





















assessment

















Risk



methodology
clear and









Effective dose
& oral





Methods
use to

estimates are
not



adequately
characterizes

Study size
and follow-



Published



exposure
estimable &





ascertain
health

susceptible
to biases

Association
between

individual-
level

up large
enough to



in peer-
reviewed

Exposure
primarily

consistent w/
current





outcomes

were
unbiased,
highly
sensitive

and
specific.

from
confounding
exposures or
from study
design or
statistical
analysis.

TCDD and

adverse
health effect,
with
exposure-
response
relationship.

exposures.
Limitations

and
uncertainties
in exposure
assessment
considered.

yield precise
estimates of
risk and
ensure
adequate
statistical
power.



literature
with
appropriate
discussion
of

strengths,
limitations.

TCDD and
quantified so
that dose-
response
relationship
can be
assessed.

biological
understanding.
Latency and
appropriate
window(s) of
exposure
examined.

Pass for

dose-
response
analyses?

Cancer

Considerations



Criteria

Y/N

Consonni et al. (2008. 524825)





















all cancer sites combined, site-specific analyses

a/

a/

a/

X

a/



a/

X

X

N

Seveso Cohort-Women's Health Study





















Baccarelli et al. (2006. 197036)





















site specific analysis

a/

a/

X

a/

a/



a/

a/

a/

N°

Warner et al. (2002. 197489)





















breast cancer incidence

V

V

a/

a/

V



V

a/

a/

Y

Chapaevsk Study





















Revich et al. (2001. 199843)





















all cancer sites combined, site-specific analyses

X

X

X

X

V



X

X

X

N

Ranch Hands Cohort





















Akhtar et al. (2004. 197141)





















all cancer sites combined, site-specific analyses

a/

X

a/

a/

V



a/

X

a/

N

Michalek and Pavuk (2008. 199573)





















all cancer sites combined

V

X

V

V

V



V

X

V

N


-------
Table 2-2. Epidemiological cancer study selection considerations and criteria (continued)









Exposure



















assessment



















methodology







Effective dose







Risk



clear and







& oral





Methods

estimates are



adequately

Study size





exposure





use to

not



characterizes

and follow-

Published



estimable &





ascertain

susceptible

Association

individual-

up large

in peer-

Exposure

consistent w/





health

to biases

between

level

enough to

reviewed

primarily

current





outcomes

from

TCDD and

exposures.

yield precise

literature

TCDD and

biological





were

confounding

adverse

Limitations

estimates of

with

quantified so

understanding.





unbiased,

exposures or

health effect,

and

risk and

appropriate

that dose-

Latency and





highly

from study

with

uncertainties

ensure

discussion

response

appropriate

Pass for



sensitive

design or

exposure-

in exposure

adequate

of

relationship

window(s) of

dose-



and

statistical

response

assessment

statistical

strengths,

can be

exposure

response



specific.

analysis.

relationship.

considered.

power.

limitations.

assessed.

examined.

analyses?

Cancer

Considerations

Criteria

Y/N

Others



















Hooiveld et al. (1998. 197829)



















all cancer sites combined, site-specific analyses

a/

a/

a/

a/

X

a/

a/

X

N

t'Mannetie et al. (2005. 197593)



















all cancer sites combined, site-specific analyses

a/

X

a/

a/

a/

X

X

X

N

McBride et al. (2009. 197296)



















all cancer sites combined, site-specific analyses

V

X

X

V

X

a/

X

X

N

Mc Bride et al. (2009, 198490)



















all cancer sites combined, site-specific analyses

V

a/

X

V

X

V

a/

a/

Nd

"This study has been superseded and updated by Steenland et al. (2001, 1974331.

' Becher et al. (1998, 1971731') assessed this same cohort taking cancer latency into account, thereby superseding this study.

°It is unknown whether the frequency of t(14;18)translocations in lymphocytes relates specifically to an increased risk of non-Hodgkin's lymphoma. Given this

lack of obvious adverse effect, dose-response analyses for this outcome were not conducted.
dNo dose-response associations were noted.

a/ = Consideration/criteria satisfied; X= Consideration/criteria not satisfied.


-------
Table 2-3. Epidemiological noncancer study selection considerations and criteria











Exposure
assessment









Effective dose







Risk



methodology
clear and

Study size
and







& oral exposure
estimable &





Methods

estimates



adequately

follow-up







consistent w/





use to

are not



characterizes

large







current





ascertain

health
outcomes

were
unbiased.

susceptible
to biases
from
confounding
exposures

Association

between
TCDD and

adverse
health effect.

individual-

level
exposures.
Limitations
and

enough to
yield
precise
estimates
of risk and



Published in
peer-
reviewed
literature
with

Exposure
primarily
TCDD and
quantified so
that dose-

biological
understanding.
Latency and
appropriate
window(s) of





highly
sensitive

and
specific.

or from
study design
or statistical
analysis.

with
exposure-
response
relationship.

uncertainties in
exposure
assessment
considered.

ensure
adequate
statistical
power.



appropriate
discussion ol
strengths,
limitations.

response
relationships
can be
assessed.

exposure
examined for a
Nonfatal
endpoint.

Pass for

dose-
response
analyses?

Noncancer

Considerations



Criteria

Y/N

NIOSH Cohort





















Steenland et al. (1999. 197437)





















mortality (noncancer) -ischemic heart disease

a/

X

a/

a/

a/



a/

X

X

N

Collins et al. (2009. 197627)





















mortality (noncancer)

a/

a/

X

a/

a/



a/

a/

X

N

BASF Cohort





















Ott and Zober (1996. 198101)





















mortality (noncancer)

V

a/

X

V

V



V

a/

X

N

Hamburg Cohort





















Flesch-Janvs etal. (1995. 197261)





















mortality (noncancer)

V

V

a/

V

V



V

V

X

N

Seveso Cohort-Women's Health Study





















Eskenazi et al. (2002. 197168)





















menstrual cycle characteristics

V

V

a/

V

V



V

V

a/

Y

Eskenazi et al. (2002. 197164)





















endometriosis

X

X

X

V

X



V

V

X

N

Eskenazi et al. (2003. 197158)





















birth outcomes

X

X

X

V

a/



V

V

X

N


-------
Table 2-3. Epidemiological noncancer study selection considerations and criteria (continued)









Exposure
assessment









Effective dose







Risk



methodology
clear and

Study size
and







& oral exposure
estimable &





Methods

estimates



adequately

follow-up







consistent w/





use to

are not



characterizes

large







current





ascertain

health
outcomes

were
unbiased,

susceptible
to biases
from
confounding
exposures

Association

between
TCDD and

adverse
health effect,

individual-

level
exposures.
Limitations
and

enough to
yield
precise
estimates
of risk and



Published in
peer-
reviewed
literature
with

Exposure
primarily
TCDD and
quantified so
that dose-

biological
understanding.
Latency and
appropriate
window(s) of





highly
sensitive

and
specific.

or from
study design
or statistical
analysis.

with
exposure-
response
relationship.

uncertainties in
exposure
assessment
considered.

ensure
adequate
statistical
power.



appropriate
discussion ol
strengths,
limitations.

response
relationships
can be
assessed.

exposure
examined for a
Nonfatal
endpoint.

Pass for

dose-
response
analyses?

Noncancer

Considerations



Criteria

Y/N

Warner et al. (2004, 197490)





















age at menarche

a/

a/

X

a/

a/



a/

a/

X

N

Eskenazi et al. (2005, 197166)





















age at menopause

a/

a/

X

a/

a/



a/

a/

X

N

Warner et al. (2007, 197486)





















ovarian function

V

V

X

V

V



V

V

X

N

Eskenazi et al. (2007. 197170)





















uterine leiomyoma

V

V

a/

V

V



V

V

X

Na

Seveso Cohort-Other Studies





















Bertazzi et al. (2001. 197005)





















mortality (noncancer)

V

V

X

X

V



V

X

X

N

Consonni et al. (2008, 524825)





















mortality (noncancer)

a/

a/

X

X

a/



a/

X

X

N

Mocarelli et al. (2000. 197448)





















sex ratio

V

V

a/

a/

V



X

a/

X

Nb


-------
Table 2-3. Epidemiological noncancer study selection considerations and criteria (continued)









Exposure
assessment









Effective dose







Risk



methodology
clear and

Study size
and







& oral exposure
estimable &





Methods

estimates



adequately

follow-up







consistent w/





use to

are not



characterizes

large







current





ascertain

health
outcomes

were
unbiased.

susceptible
to biases
from
confounding
exposures

Association

between
TCDD and

adverse
health effect.

individual-

level
exposures.
Limitations
and

enough to
yield
precise
estimates
of risk and



Published in
peer-
reviewed
literature
with

Exposure
primarily
TCDD and
quantified so
that dose-

biological
understanding.
Latency and
appropriate
window(s) of





highly
sensitive

and
specific.

or from
study design
or statistical
analysis.

with
exposure-
response
relationship.

uncertainties in
exposure
assessment
considered.

ensure
adequate
statistical
power.



appropriate
discussion ol
strengths,
limitations.

response
relationships
can be
assessed.

exposure
examined for a
Nonfatal
endpoint.

Pass for

dose-
response
analyses?

Baccarelli et al. (2002. 197062; 2004. 197045)





















immunological effects

a/

a/

a/

a/

a/



a/

a/

X

N

Landi et al. (2003. 198362)





















gene expression

a/

a/

X

a/

X



a/

X

X

N

Alaluusua et al. (2004. 197142)





















oral hygiene

V

V

V

V

V



V

V

V

Y

Baccarelli et al. (2005. 197053)





















chloracne

a/

a/

a/

a/

a/



a/

a/

a/

N°

Baccarelli et al. (2008. 197059)





















neonatal thyroid function

V

V

V

X

V



V

V

a/

Y

Mocarelli et al. (2008. 199595)





















semen quality

V

V

V

a/

V



V

V

V

Y

Chapaevsk Study





















Revich et al. (2001. 199843)





















mortality (noncancer) and reproductive health

V

X

X

X

V



V

X

X

N

Ranch Hands Cohort





















Michalek and Pavuk (2008. 199573)





















diabetes

V

X

a/

a/

V



V

X

a/

N


-------
Table 2-3. Epidemiological noncancer study selection considerations and criteria (continued)









Exposure





















assessment









Effective dose











methodology

Study size







& oral exposure







Risk



clear and

and







estimable &





Methods

estimates



adequately

follow-up







consistent w/





use to

are not



characterizes

large







current





ascertain

susceptible

Association

individual-

enough to



Published in

Exposure

biological





health

to biases

between

level

yield



peer-

primarily

understanding.





outcomes

from

TCDD and

exposures.

precise



reviewed

TCDD and

Latency and





were

confounding

adverse

Limitations

estimates



literature

quantified so

appropriate





unbiased,

exposures

health effect,

and

of risk and



with

that dose-

window(s) of





highly

or from

with

uncertainties in

ensure



appropriate

response

exposure

Pass for



sensitive

study design

exposure-

exposure

adequate



discussion ol

relationships

examined for a

dose-



and

or statistical

response

assessment

statistical



strengths,

can be

Nonfatal

response



specific.

analysis.

relationship.

considered.

power.



limitations.

assessed.

endpoint.

analyses?

Other





















Rvanetal. (2002, 198508)





















sex ratio

X

X

X

X

a/



a/

X

X

N

Kansetal. (2006. 199133)





















long-term health consequences

X

X

X

a/

a/



a/

X

X

N

McBride et al. (2009. 198490)





















mortality (noncancer)

X

X

X

a/

X



V

a/

X

N

Mc Bride et al. (2009. 197296)





















mortality (noncancer)

X

a/

X

V

X



V

X

X

N

aCategorical measures of TCDD suggest an inverse association between TCDD exposure and uterine fibroids. The observed direction of the reported

associations precluded quantitative dose-response modeling.
bThe somewhat arbitrary cut off age of 19 for statistically significant exposure associations results in a highly uncertain critical exposure window. It is difficult
to determine whether effects are a consequence of the initial high exposure during childhood or a function of the cumulative exposure for this entire exposure
window. The differences between these two dose estimates are quite large.

°Chloracne is recognized to occur following high TCDD exposure levels. This study provides limited relevance to TCDD RfD development, as exposure levels

observed in the general population are much lower.
a/ = Consideration/criteria satisfied. X = Consideration/criteria not satisfied.


-------
Table 2-4. Epidemiological studies selected for TCDD cancer dose-response modeling





Location,







No. of









Health

time

Cohort

Exposure

Exposure

cases/

Effect Measure/







outcome

period

description

assessment

measures

deaths

RR (95% CI)

Risk factors

Comments

Reference

Mortality

USA,

NIOSH cohort

Cumulative

No exposure

256

The slope (P) was

Available: age,

Confounding by

Cheng et al.

from all

1942-1993

including 3,538

serum lipid

categories

cancer

3.3 x 10"6 for lag

year of birth, and

smoking was

(2006,

cancers



occupationally

TCDD

provided

deaths

of 15 years

race

considered indirectly

523122')





exposed male

concentrations





excluding upper



by analysis of







workers at 8

(CSLC) based





5% of TCDD

Risks adjusted for:

smoking-related and







plants in the

on work





exposures.

year of birth, age,

smoking-unrelated







United States;

histories, job-





The slopes ranged

and race

cancers.







256 cancer

exposure





two orders of



Other occupational







deaths

matrix, and





magnitude



exposures were









concentration





depending on



considered indirectly









and age-





modeling



by repeated analyses









dependent two-





assumption



removing one plant









compartment









at a time.









model of









Based on indirect









elimination









evaluation, there









kinetics









was no clear



















evidence of



















confounding.



Mortality

USA,

NIOSH cohort

CSLC based on

CSLC





Available: date of

Included in

Steenland et

from all

1942-1993

including 3,538

work histories,

(ppt-years)





birth and age

U.S. EPA (2003,

al. (2001,

cancers



male workers,

job-exposure

<335

64

1.00



537122)

197433s)





256 cancer

matrix, and a

335-520

29

1.26 (0.79-2.00)

Adjusted for: date









deaths

simple one-

520-1,212

22

1.02 (0.62-1.65)

of birth, and age











compartment

1,212-2,896

30

1.43 (0.91-2.25)

was used as time











first-order

2,896-7,568

31

1.46 (0.93-2.30)

scale in Cox











pharmacokineti

7,568-20,455

32

1.82(1.18-2,82)

model











c elimination

>20,455

48

1.62 (1.03-2,56)













model with 8.7-



















year half-life














-------
Table 2-4. Epidemiological studies selected for TCDD cancer dose-response modeling (continued)





Location,







No. of









Health

time

Cohort

Exposure

Exposure

cases/

Effect Measure/







outcome

period

description

assessment

measures

deaths

RR (95% CI)

Risk factors

Comments

Reference

Mortality

Hamburg,

Boehringer

Cumulative

Categorical

124





Included in

Becher et

from all

Germany,

cohort including

TCDD serum

exposures







U.S. EPA (2003,

al. (1998,

cancers

production

approximately

lipid

(Cox model)







537122')

197173s)

combined

period was

1,189 workers

concentrations

0-
-------
Table 2-4. Epidemiological studies selected for TCDD cancer dose-response modeling (continued)





Location,







No. of









Health

time

Cohort

Exposure

Exposure

cases/

Effect Measure/







outcome

period

description

assessment

measures

deaths

RR (95% CI)

Risk factors

Comments

Reference

Mortality

Ludwig-

BASF cohort,

Cumulative

Internal

Internal



Available: age,

Included in

Ottand

and

shafen,

243 men

TCDD serum

comparisons

cohort



BMI, smoking

U.S. EPA (2003,

Zober

incidence

Germany,

exposed from

lipid

based on

analysis



status and history

537122s)

(1996,

for all

1954-1992

accidental

concentrations

continuous



Date of 1st TCDD

of occupational



198101)

cancers



release that

expressed in

measure of

31

exposure

exposure to

Positive associations



combined,



occurred in

|ig/kg based on

TCDD.

cancer

1.22 (95% CI:

dlUllldllL'

noted for digestive



as well as



1953 during

TCDD half-life



deaths

1.00-1.50)

amines and

cancer, but not for



for specific



production of

of 5.1-8.9 years,







asbestos

respiratory cancer



cancer sites



trichlorophenol,

Cox regression



47













or who were

model



incident

1.11 (95% CI:



Associated between







involved in





cancers

0.91-1.35)



TCDD and







clean-up











increased SMRs







activities





External





found only among











External

cohort





current smokers











comparisons

analyses

















exposure







Last published











categories:

Deaths

SMRs



account of this











<0.1,

8

0.8 (0.4-1.6)



cohort











0.1-0.99,

8

1.2 (0.5-2.3)















1.0-1.99

8

1.4 (0.6-2.7)















>2 ng/kg

7

2.0 (0.8-4.0)








-------
Table 2-4. Epidemiological studies selected for TCDD cancer dose-response modeling (continued)





Location,







No. of









Health

time

Cohort

Exposure

Exposure

cases/

Effect Measure/







outcome

period

description

assessment

measures

deaths

RR (95% CI)

Risk factors

Comments

Reference

Breast

Italy

981 women

TCDD serum



Cases



Available:

Included in

Warner et

cancer

1976-1998

from zones A

lipid

<20 ppt

1

1.0

gravidity, parity,

U.S. EPA (2003,

al. (2002,

incidence



and B with

concentrations

20.1-44 ppt

2

1.0 (0.1-10.8)

age at first

537122)

197489s)





available

(ppt) collected

44.1-100 ppt

7

4.5 (0.6-36.8)

pregnancy, age at









archive serum

between 1976

>100 ppt

5

3.3 (0.4-28.0)

last pregnancy,









samples, 15

and 1981. For







lactation, family









breast cancer

most samples

LogioTCDD

15

2.1 (1.0-4.6)

history of breast









cases

collected after

also modeled





cancer, age at











1977, serum

as continuous





menarche, current











TCDD levels

variable





body mass index,











were back-







oral contraceptive











extrapolated







use, menarcheal











using a first-







status at











order kinetic







explosion,











model with a 9-







menopause status











year half-life.







at diagnosis,



















height, smoking,



















alcohol



















consumption.



















Adjusted for age,



















which was used as



















time scale in Cox



















model; other



















covariates were



















evaluated but



















were not



















identified as



















confounders.






-------
Table 2-4. Epidemiological studies selected for TCDD cancer dose-response modeling (continued)





Location,







No. of









Health

time

Cohort

Exposure

Exposure

cases/

Effect Measure/







outcome

period

description

assessment

measures

deaths

RR (95% CI)

Risk factors

Comments

Reference

Mortality

Midland,

Subset of

Cumulative

Part per

177

The slope of a

Hazard ratios

Confounding by

Collins et

from all

Michigan,

NIOSH cohort

serum lipid

billion-year

cancer

proportional

adjused for age,

smoking was not

al. (2009,

cancers

USA.

including 1,615

TCDD

estimates of

deaths

hazards

year of birth, and

considered directly

197627)

and

Follow-up

occupationally

concentrations

cumulative



regression model

hire year.

due to a lack of data.



specific

period:

exposed male

based on work

TCDD



for fatal soft

Stratified analyses

Relatively long



cancer

1942-2003.

workers at 1

histories, job-

exposure



tissue sarcoma

used to examine

follow-up period



types

Serum

plant in the

exposure



was 0.05872

potential impact

(average = 36





collection

United States;

matrix, and





(95% CI not

of

years).





period:

177 cancer

concentration





provided but for

pentachlorophenol

Potential outcome





2004-2005

deaths

and age-





Chi-square

exposure on

misclassification for









dependent two-





p = 0.0060) for

mortality.

soft tissue sarcoma









compartment





every 1-part per



due to potential









model of





billion-year



inaccuracies on









elimination





increase in



death certificates.









kinetics. Serum





cumulative



Data analyzed from









samples were





exposure of



one plant reduces









obtained from





TCDD. Slope



heterogeneity









280 former





estimates for all



associated with









workers





fatal cancers, fatal



multiplant analyses.









collected during





lung, fatal



More serum samples









2004-2005.





prostate, fatal



(n = 280) analyzed















leukemias and



than used to derive















fatal non-Hodgkin



TCDD estimates for















lymphomas were



other NIOSH cohort















not statistically



analyses.















significant








-------
Table 2-5. Epidemiological studies selected for TCDD noncancer dose-response modeling













No. of









Health

Location,

Cohort

Exposure

Exposure

cases/

Effect Measure/







outcome

time period

description

assessment

measures

deaths

RR (95% CI)

Risk factors

Comments

Reference

b-TSH

Italy, 1976;

Population-

Based on zone

Population-



Population-based

Available: gender,

An association with

Baccarelli

measured 72

children,

based study:

of residence,

based study:



study

birth weight, birth

serum TCDD levels

et al. (2008,

hours after

1994-2005

1,041

estimated mean





Mean b-TSH

order, maternal age

of mothers was

197059)

birth from a



singletons

values from a







at delivery,

found with b-TSH



heel pick



(56 from

previous study.

Reference

533

Reference:

hospital, type of

among the 51 births



(routine



zone A, 425

Maternal



births

0.98 (95% CI:

delivery.

in the plasma dioxin



screening for



from zone B

plasma TCDD





0.90-1.08)



study.



all newborns in



and 533 from

levels estimated

Zone B

425

Zone B:

There was limited





the region



reference)

at the date of
delivery using a
first-order
pharmacokineti
c model and



births

1.66 (95% CI:

evidence of









born between





1.19-2.31)

confounding, so









Jan. 1, 1994-

Zone A

56

Zone A:

mean TSH results









June 30,



births

1.35 (95% CI:

presented here are









2005.

elimination rate





1.22-1.49)

unadjusted.









Plasma

estimated in

















dioxin study:

Seveso women

Plasma



Association











51 children
born to 38
women of
fertile age
who were

(half-life =9.8
years).

dioxin
study:
Continuous
maternal



between neonatal
b-TSH with
plasma TCDD:
adjusted p = 0.75











part of the



plasma



(p< 0.001)











Seveso



TCDD















Chloracne



















Study.
















-------
Table 2-5. Epidemiological studies selected for TCDD noncancer dose-response modeling (continued)













No. of









Health

Location,

Cohort

Exposure

Exposure

cases/

Effect Measure/







outcome

time period

description

assessment

measures

deaths

RR (95% CI)

Risk factors

Comments

Reference

Sperm conc.

Italy, 1976,

135 exposed

Serum TCDD

TCDD



Mean values

Available: age,

Results stratified by

Mocarelli

(million/mL)

1998

(from zone

(in ppt) from

quartiles



were compared

abstinence time,

timing of exposure

et al. (2008,

Progressive



A) and 184

1976-1977





between the

smoking status,

(1-9 yrs old vs.

199595)

motility (%)



nonexposed

samples (for





exposed and

education, alcohol

10-17 yrs old in



Serum E2



men aged

exposed men);





comparison

use, maternal

1976).



(pmol/L)



1-26 in 1976

background





groups for sperm

smoking during









were

values were





concentration,

pregnancy,









included.

assumed for





volume, motility

employment status,









These

unexposed men





and count, FSH,

BMI, chronic









subjects were

based on serum





E2, LH, and

exposure to









selected from

analysis of





InhibinB.

solvents and other









the cohort of

residents in







toxic substances.









257 exposed

uncontaminated

















and 372

areas.







Adjusted for









unexposed









smoking status,









people.









organic solvents,



















age at time of tests,



















BMI, alcohol use,



















education,



















employment status



















and abstinence



















(days) for sperm



















data.



















Hormone data not



















adjusted for



















education level,



















employment status,



















and abstinence



















time.






-------
Table 2-5. Epidemiological studies selected for TCDD noncancer dose-response modeling (continued)













No. of









Health

Location,

Cohort

Exposure

Exposure

cases/

Effect Measure/







outcome

time period

description

assessment

measures

deaths

RR (95% CI)

Risk factors

Comments

Reference

Dental defects

Seveso, Italy,

65 subjects

Serum TCDD

Non-ABR



Dental defect %

Available: medical

Dose-response

Alaluusua



Dental

<9.5 years

(ng/kg) from

Zone

10/39

26%

history, age, sex,

pattern observed

et al. (2004,



exams

old at time of

1976 samples

31-226

1/10



education, smoking

with dental defects

197142)



administered

Seveso

for those who

ng/kg



10%



in the ABR zone;





in 2001

explosion

resided in Zone

238-592

5/11





however, the control





among those

and residing

ABR; no serum

ng/kg



45%



population had a





exposed to

in zones

levels for non-

700-26000

9/15





much higher





TCDD in

ABR; 130

ABR residents

ng/kg



60%



prevalence of dental





1976

subjects

(unexposed).









defects (26%) than







recruited

TCDD

<5 years of

25/75





those in the lowest







from the

exposure

age at time







exposure group







non-ABR

represent levels

of accident







(10%).







region

as of 1976





Odds Ratios











(unexposed)

(after accident)

Non-ABR



(among those <5



Also assessed











Zone or



years of age at



hypodontia and











31-226



time of accident)



other dental and oral











ng/kg serum



1.0



aberrations, but











TCDD







these were too rare











238-26,000







to allow modeling











ng/kg serum



2.4(1.3-4.5)



by ABR zone.











TCDD












-------
Table 2-5. Epidemiological studies selected for TCDD noncancer dose-response modeling (continued)













No. of









Health

Location,

Cohort

Exposure

Exposure

cases/

Effect Measure/







outcome

time period

description

assessment

measures

deaths

RR (95% CI)

Risk factors

Comments

Reference

Menstrual

Seveso, Italy,

Women who

Serum TCDD

Interquartile



Lengthening of

Interview data:



Eskenazi et

cycle

follow-up

were <40

(ng/kg) from

range was



the menstrual

medical history,



al. (2002,

characteristics:

interview

years from

1976 samples.

64-322 ppt



cycle by 0.93

personal habits,



197168)

menstrual cycle

conducted in

zones A or B

TCDD





days (95% CI: -

work history,





length.

1996-1997 of

in 1976,

exposure level

TCDD



0.01, 1.86)

reproductive







women

A positive

was back-

examined as





history, age,







exposed to

association

extrapolated to

continuous





smoking, body







TCDD in the

found among

1976 using the

measure





mass index, alcohol







1976

women who

Filser or the

(per 10-fold





and coffee







accident

were pre-

first-order

increase in





consumption,









menarcheal

kinetic models.

serum





exercise, illness,









at the time of



levels).





abdominal









accident









surgeries.









(n = 134)
















-------
Table 2-6. Animal bioassays selected for cancer dose-response modeling



Species/strain

Sex
exposure
route/duration

n

Average daily
dose levels
(ng/kg-day)

Cancer types

Statistical significant tumors
(pairwise with controls or trend tests)

Reference

Mouse/
B6C3F1

Male/Female
Oral gavage once
per week; 52 weeks

Approximat
ely 40 to 50
in each
dose group
including
controls

0,351, and 714

Females and males:
hepatocellular
adenomas and
carcinomas

Liver: adenomas and carcinomas in females
and carcinomas in males (using incidental
tumor statistical test)

Delia Porta et
al. (1987,
197405')

Rat/Sprague-
Dawley

Male/female
Oral-lifetime
feeding; 2 years

50 each
(86 each in
vehicle
control
group)

0, 1, 10, or 100

Females: liver, lung,
oral cavity

Males: adrenal, oral
cavity, tongue

Adrenal cortex: adenoma
Liver: hepatocellular adenoma(s) or
carcinoma(s); hyperplastic nodules
Lung: keratinizing squamous cell carcinoma
Oral cavity: stratified squamous cell
carcinoma of hard palate or nasal turbinates
Tongue: stratified squamous cell carcinoma

Kociba et al.

(1978,

001818);

(Female liver
tumors
analysis
updated in
Goodman and
Sauer, 1992,
197667')

Mouse/
B6C3F1

Male/female
Oral-gavage twice
per week; 104
weeks

50 each
(75 each in
vehicle
control
group)

0, 1.4, 7.1, or 71
for males;
0,5.7, 28.6, or 286
for females

Females:

hematopoietic system,
liver, subcutaneous
tissue, thyroid

Males: liver, lung

Hematopoietic system: lymphoma or
leukemia

Liver: hepatocellular adenoma or carcinoma
Lung: alveolar/bronchiolar adenoma or
carcinoma

Subcutaneous tissue: fibrosarcoma
Thyroid: follicular-cell adenoma

NTP (1982,
543764)

Rat/Osborne-
Mendel

Male/female
Oral-gavage twice
per week; 104
weeks

50 each
(75 each in
vehicle
control
group)

0, 1.4, 7.1, or 71

Females: adrenal,
liver, subcutaneous
tissue, thyroid

Males: adrenal, liver,
thyroid

Adrenal: cortical adenoma, or carcinoma or
adenoma, NOS

Liver: neoplastic nodule or hepatocellular
carcinoma

Subcutaneous tissue: fibrosarcoma

Liver: neoplastic nodule or hepatocellular
carcinoma

Thyroid: follicular-cell adenoma or carcinoma

NTP (1982,
543764)


-------
Table 2-6. Animal bioassays selected for cancer dose-response modeling (continued)

Species/strain

Sex
exposure
route/duration

n

Average daily
dose levels
(ng/kg-day)

Cancer types

Statistical significant tumors
(pairwise with controls or trend tests)

Reference

Rat/Harlan

Sprague-

Dawley

Female
Oral-gavage
5 days per week;
2 years

53 or 54

0,2.14,7.14, 15.7,
32.9, or 71.4

Liver
Lung

Oral mucosa
Pancreas

Liver: hepatocellular adenoma
Liver: cholangiocarcinoma
Lung: cystic keratinizing epithelioma
Oral mucosa: squamous cell carcinoma
Pancreas: adenoma or carcinoma

NTP (2006,

1976051

Mouse/
Outbred
Swiss/H/Riop

Male

Gastric intubation
once per week; 1
year

43 or 44
(vehicle
control
group =
38)

0, 1, 100, or 1,000

Liver

Liver: tumors

Toth et al.

(1979,

1971091


-------
Table 2-7. Animal bioassay studies selected for noncancer dose-response modeling



Species/
strain

Exposure
protocol

Sex
(exposure
group)

n

Average daily
dose levels
(ng/kg-day)

NOAEL
(ng/kg-day)

LOAEL

(ng/kg-day)

Endpoint(s)
examined

LOAEL/NOAEL
Endpoint(s)

Reference

Reproductive toxicity studies

Monkey/
Rhesus

Daily dietary
exposure in
female
monkeys
(3.5-4 years)

F (FO, Fl,
F2, F3)

3 to 7 (Fl)

0,0.15, or 0.67

0.15

0.67

Reproductive
and

developmental
effects

Neurobehavioral effects
(e.g., discrimination-
reversal learning
affected)

Bowman et
al.(1989,
543744; 1989.
543745):
Schantz and
Bowman
(1989. 198104);
Schantz et al.
(1986. 088206)

Rat/Sprague-
Dawley,
Long-Evans,
Han/Wistar

Biweekly oral
gavage
(22 weeks)

Female

8

0, 10, 30 or
100

10

30

Body weight,
relative liver
weight, relative
thymus weight

Increased relative liver
weight in Sprague-
Dawley and Long-Evans
Rats; Increased relative
thymus weight in
Sprague-Dawley,
Han/Wistar and Long-
Evans Rats

Franc et al.
(2001. 197353)

Mink

Daily dietary
exposure
(132 days)

F

12

0.03 (control),
0.8, 2.65, 9, or
70

None

2.65

Reproductive
effects

Reduced kit survival

Hochstein et al
C2001. 197544)

Rat/Sprague-
Dawley

Oral gavage
(GD 14 and
21, postpartum
days 7 and 14),
(Pups: once
per week for 3
months)

Female (FO
andFl)

3 (FO andFl)

0 or 7.14

None

7.14

Developmental
effects

Lower proportion of
morphologically normal
pre-implantation
embryos during
compaction stage

Hutt et al.
(2008, 198258)


-------
Table 2-7. Animal bioassay studies considered for noncancer dose-response modeling (continued)



Species/
strain

Exposure
protocol

Sex
(exposure
group)

n

Average daily
dose levels
(ng/kg-day)

NOAEL
(ng/kg-day)

LOAEL

(ng/kg-day)

Endpoint(s)
examined

LOAEL/NOAEL
Endpoint(s)

Reference

Reproductive toxicity studies (continued)

Rat/Holtzman

Corn oil
gavage (initial
loading dose
followed by
weekly dose
during mating,
pregnancy, and
lactation-
about
10 weeks)

F(F0)
F andM
(F1 and
F2)

12 (F0)
Not specified
(F1 andF2)

0 or 16.5

None

16.5

(maternal
exposure)

Reproductive
and

developmental
effects

Decreased development
of the ventral prostrate
(Fl), decreased sex ratio
(percentage of males)
(F2)

Ikeda et al.

(2005, 197834)

Mouse/ICR

Sesame oil
gavage (initial
loading dose
followed by
weekly doses
for 5 weeks)

M(F0)

42 or 43

0, 0.095, or
950

0.1

100

Reproductive
effects

Decreased male/female
sex ratio (percentage of
males) (Fl)

Ishihara et al.
(2007. 197677')

Rat/Wistar
albino

Olive oil
gavage (daily
for 45 days)

M

6

0, 1, 10, or 100

None

1

Reproductive
effects

Reduced sperm
production, decreased
reproductive organ
weights

Latchoumycan
dane and
Mathur (2007,
197298) and
related

Latchoumycan
dane et al.

(2002, 198365;

2002.	197839:

2003.	5437461


-------
Table 2-7. Animal bioassay studies considered for noncancer dose-response modeling (continued)



Species/
strain

Exposure
protocol

Sex
(exposure
group)

n

Average daily
dose levels
(ng/kg-day)

NOAEL
(ng/kg-day)

LOAEL

(ng/kg-day)

Endpoint(s)
examined

LOAEL/NOAEL
Endpoint(s)

Reference

Reproductive toxicity studies (continued)

Rat/Sprague-
Dawley

Daily dietary
exposure
(3 generations)

F andM,
(FO)

F andM,
(F1 and
F2)

10-32 (FO)
22 (Fl)
28 (F2)

0, 1, 10, or 100

1

10

Reproductive
and

developmental
effects

Decrease in fertility,
decrease in the number
of live pups, decrease in
gestational survival;
decrease in postnatal
survival, decreased
postnatal body weight in
one or more generations

Murray et al.
(1979. 197983s)

Monkey/
Rhesus

Daily dietary
exposure
(4 years)

F

8

0,0.15, or 0.67

None

0.15

Reproductive
effects

Increased incidence of
endometriosis (disease
ranged from moderate to
severe)

Rier et al.

(1993,199987;
1995. 198566)

Rat/Sprague-
Dawley

Maternal corn
oil gavage
(weekly on
GD 14 and 21;
PND 7 and 14)

Offspring corn
oil gavage
(weekly for
11 months)

F (FO)
F (Fl)

3 (FO)
10 (Fl)

0,0.14,0.71,
7.14, or 28.6

0.14

0.71

Reproductive
effects

Decrease serum
estradiol levels (Fl)

Shi et al.
('2007. 198147)

Rhesus

monkey/

Cynomolgus

Fed gelatin
capsules
(5 days/week
for 12 months)

F

6 (treatment)
5 (controls)

0,0.71, 3.57,
or 17.86

17.86

None

Endometriosis
effects

Increased endometrial
implant survival,
increased maximum and
minimum implant
diameters, growth
regulatory cytokine
dysregulation

Yang et al.
C2000. 1985901


-------
Table 2-7. Animal bioassay studies considered for noncancer dose-response modeling (continued)



Species/
strain

Exposure
protocol

Sex
(exposure
group)

n

Average daily
dose levels
(ng/kg-day)

NOAEL
(ng/kg-day)

LOAEL

(ng/kg-day)

Endpoint(s)
examined

LOAEL/NOAEL
Endpoint(s)

Reference

Developmental toxicity studies

Rat/Harlan

Sprague-

Dawley

Corn oil
gavage (GD
10-16

F (F0)

80-88 (Fl)

0, 25, or 100

None

25

Developmental
effects

Decreased preference in
the consumption of
0.25% saccharin
solution (Fl)

Amin et al.

(2000, 197169)

Rat/CRL:WI
(Han)

Maternal daily
dietary

exposure for an
estimated
20 weeks
(12 weeks
prior to mating
through
parturition)

F (F0)
M (Fl)

65 (F0
treatments)
75 (F0
controls) at
study
initiation;
following
interim
sacrifice
~30 animals
were allowed
to litter; Fl
on PND 21
was ~7

0,2.4, 8, or 46

None

2.4

(maternal
exposure)

Reproductive
and

developmental
effects

Delayed BPS (Fl)

Bell et al.

(2007, 197041)

Rat/Sprague-
Dawley

Maternal corn
oil gavage
(GD 14 and
21; PND 7 and
14)

Offspring corn
oil gavage
(weekly for
8 months)

F (F0 and
Fl)

2 or 3 (F0)
7 (Fl)

0,7.14, or 28.6

None

7.14

Developmental
effects

Decreased serum
estradiol levels (Fl)

Franczak et al.

(2006, 197354)


-------
Table 2-7. Animal bioassay studies considered for noncancer dose-response modeling (continued)



Species/
strain

Exposure
protocol

Sex
(exposure
group)

n

Average daily
dose levels
(ng/kg-day)

NOAEL
(ng/kg-day)

LOAEL

(ng/kg-day)

Endpoint(s)
examined

LOAEL/NOAEL
Endpoint(s)

Reference

Developmental toxicity studies

Rat/Sprague-
Dawley

Maternal
single corn oil
gavage (GD 8)

Offspring
exposed during
gestation and
lactation
(35 days)

F(F0)
F andM
(Fl)

12 (FO)
50 or 60 (Fl)

0, 20, 60, or
180

None

20

(maternal
exposure)

Developmental
effects

Abrogation of sexually
dimorphic neuro-
behavioral responses
(Fl)

Hojo et al.
C2002. 198785")
and related
Zareba et al.

(2002, 197567)

Rat/

Han/Wistar
and Long-
Evans

Maternal
single corn oil
gavage
(GD 15)

F(F0)
F andM
(Fl)

4 to 8 (FO)
3F/3M per
treatment
group (Fl)

0, 30, 100,
300, or 1,000

None

30

(maternal
exposure)

Developmental
effects

Reduced mesiodistal
length of the lower third
molar (Fl)

Kattainen et
al. (2001,

198952")

Mouse/
C57BL/6J,
BALB/cByJ,
A/J, CBA/J,
C3H/HeJ, and
C57BL/10J

Maternal
single corn oil
gavage
(GD 13)

F(F0)
F andM
(Fla, b, c)

Dams not
specified
(FO);

23-36 (Fla);
4-5 (Fib);
107-110
(Flc)

0, 10, 100, or
1,000

None

10

(maternal
exposure)

Developmental
effects

Variation in Ml
morphology in
C57BL/10J males and
females (Fla);
decreased mandible
shape and size in
C3H/HeJ males (Fib);
variation in molar shape
in C3H/HeJ males (Flc)

Keller et al.

(2007, 198526:
2008. 198531:
2008. 198033")

Mouse/ddY

Maternal olive
oil gavage
(weekly for
8 weeks prior
to mating)

F(F0)
M (Fl)

7 (FO)

3 (Fl
immuno-
cytochemical
analysis)
6 (Fl cell
number
count)

0,0.7, or 70

None

0.7

(LOEL)

(maternal

exposure)

Neurotoxicity

Decreased serotonin-
immunoreactive neurons
in raphe nuclei of male
offspring (Fl)

Kuchiiwa et
al. (2002,

198355)


-------
Table 2-7. Animal bioassay studies considered for noncancer dose-response modeling (continued)



Species/
strain

Exposure
protocol

Sex
(exposure
group)

n

Average daily
dose levels
(ng/kg-day)

NOAEL
(ng/kg-day)

LOAEL

(ng/kg-day)

Endpoint(s)
examined

LOAEL/NOAEL
Endpoint(s)

Reference

Developmental toxicity studies

Mouse/NIH
(pregnant and
pseudo-
pregnant)

Maternal
sesame oil
gavage daily
for 8 days
(GD 1-8)

F

10

0, 2, 50, or 100

None

2

Developmental
effects

Decreased progesterone
and increased serum
estradiol levels

Li et al. (2006,
199059)

Rat/Holtzman

Maternal
single olive oil
gavage
(GD 18)

F (F0 and
Fl)

4-7 (F0 and
Fl)

0, 20, 60, or
180

None

20

(maternal
exposure)

Behavioral
effects

Decreased training
responses (Fl)

Markowski et
al. (2001,
197442)

Rat/Line C

Maternal
single corn oil
gavage
(GD 15)

F (F0)
F andM
(Fl)

24-32
(treatment)
12-48
(controls)

0, 30, 100,
300, or 1,000

None

30

(maternal
exposure)

Developmental
effects

Increase in dental caries
(Fl)

Miettinen et
al. (2006,

198266s)

Rat/Holtzman

Maternal
single corn oil
gavage
(GD 15)

F (F0)
M (Fl)

Not specified
(F0)

5 males and
3 females
(Fl)

0, 12.5, 50,
200, or 800

800

(maternal
exposure)

None

Immunotoxicity

Decreased spleen
cellularity (Fl)

Nohara et al.

(2000, 200027)

Rat/Holtzman

Maternal
single corn oil
gavage
(GD 15)

F (F0)
M (Fl)

6 (F0)
5 males and
3 females
(Fl)

0, 12.5, 50,
200, or 800

12.5

(maternal
exposure)

50

(maternal
exposure)

Developmental
effects

Decreased anogenital
distance (Fl)

Ohsako et al.
(2001. 198497)

Rat/Harlan

Sprague-

Dawley

Maternal corn
oil gavage
(GD 10-16

F(F0)

~4 (F0);
80-88 (Fl)

0, 25, or 100

None

None

Developmental
effects

Facilitatory effect on
radial arm maze learning
(Fl)

Schantz et al.
fl996. 198781s)

Rat/Sprague-
Dawley

Maternal corn
oil gavage
(GD 10-16)

F andM
(Fl)

-15 (F0);
5-9 (Fl)

0, 25, or 100

25

100

Developmental
effects

Decreased thymus
weight

Seo et al.
(1995. 197869)


-------
Table 2-7. Animal bioassay studies considered for noncancer dose-response modeling (continued)



Species/
strain

Exposure
protocol

Sex
(exposure
group)

n

Average daily
dose levels
(ng/kg-day)

NOAEL
(ng/kg-day)

LOAEL

(ng/kg-day)

Endpoint(s)
examined

LOAEL/NOAEL
Endpoint(s)

Reference

Developmental toxicity studies

Rat/TCDD-

resistant

Han/Wistar

bred with

TCDD-

sensitive

Long-Evans

Maternal corn
oil gavage
(GD 15)

F(F0)
M (Fl)

5-8 (FO)

0, 30, 100,
300, or 1,000

100

300

Reproductive
effects

Reduction in daily
sperm production and
cauda epididymal sperm
reserves

Simanainen et
al. (2004,

198106)

Mouse/C57/6
NCji

Maternal

drinking water

exposure

(daily for

17-day

lactational

period)

F(F0)
F andM
(Fl)

8 (FO)

Not specified
(Fl)

0, 1.14, or 11.3

1.14
(NOEL)
(maternal
exposure)

11.3
(LOEL)
(maternal
exposure)

Immunotoxicity

Increased susceptibility
to Listeria (Fl males
and females); increase in
thymic CD4+ cells
(Fl males); decreased
spleen weight
(Fl males)

Sugita-
Konishi et al.
(2003. 198375)

Acute toxicity studies

Mouse/B6C3Fl

Corn oil
gavage (single
exposure)

F

20

0, 1, 5, 10, 50,
100, or 6,000

5

10

Immunotoxicity

Increased mortality from
influenza infection
7 days after a single
TCDD exposure

Burleson et al.
(1996.196998)

Rat/Long-
Evans

Corn oil

gavage

(4 consecutive
days)

F

14, 6, 12, 6,
6, 6, 6, 6, 6,
and 4,
respectively
in control
and treated
groups

0,0.1,3, 10,
30, 100, 300,
1,000, 3,000,
or 10,000

30

100

Thyroid effects

Reduction in serum T4
levels

Crofton et al.
(2005. 197381)

Rat/Sprague-
Dawley

Corn oil
gavage (single
dose)

F

4 (treated);
9 (control)

0, 0.6, 2, 4, 20,
60, 200, 600,
2,000, 5,000,
or 20,000

0.6

(NOEL)

2

(LOEL)

Enzyme
induction

Increased
benzo(a)pyrene
hydroxylase (BPH)

Kitchin and
Woods (1979,
1987501


-------
Table 2-7. Animal bioassay studies considered for noncancer dose-response modeling (continued)



Species/
strain

Exposure
protocol

Sex
(exposure
group)

n

Average daily
dose levels
(ng/kg-day)

NOAEL
(ng/kg-day)

LOAEL

(ng/kg-day)

Endpoint(s)
examined

LOAEL/NOAEL
Endpoint(s)

Reference

Acute toxicity studies (continued)

Rat/Sprague-
Dawley

Corn oil dose
via oral gastric
intubation
(single dose)

F

10

0, 3, 10, 30,
100, 300,
1,000, 3,000,
10,000, or
30,000

3

10

Hormonal
effects

Increased serum FSH

Lietal. (1997,
1990601

Rat/Sprague-
Dawley

Corn oil
gavage or
TCDD-
contaminated
soil (single
dose)

F

6

0, 15, 40, 100,
200, 500,
1,000, 2,000,
or 5,000 in
corn oil

0, 15, 44, 100,
220, 500,
1,100, 2,000,
or 5,500 in
contaminated
soil

None

15

(LOEL)

Enzyme
induction

Induction of aryl
hydrocarbon
hydroxylase (at low
dose in both treatment
protocols)

Lucier et al.
(1986. 198398')

Mouse/
B6C3F1
(BALB/c
(C57BL/6N
(and DBA2

Corn oil
gavage (single
dose)

M, F

10-40

0, 5, 20, 100,
or 500

500

None

Mortality and
body weight
changes

No increased mortality
of virus-infected mice or
treatment-related
changes in body weight

Nohara et al.
(2002. 199021s)

Rat/TCDD-

resistant

Han/Wistar

bred; TCDD-

sensitive

Long-Evans

Corn oil
gavage (single
dose)

M, F

9-11

30-100,000

100

300

General
toxicological
endpoints, organ
weights, dental
defects

Reduction in serum T4
levels

Simanainen et
al. (2002,
2013691


-------
Table 2-7. Animal bioassay studies considered for noncancer dose-response modeling (continued)



Species/
strain

Exposure
protocol

Sex
(exposure
group)

n

Average daily
dose levels
(ng/kg-day)

NOAEL
(ng/kg-day)

LOAEL

(ng/kg-day)

Endpoint(s)
examined

LOAEL/NOAEL
Endpoint(s)

Reference

Acute toxicity studies (continued)

Rat/TCDD-

resistant

Han/Wistar

bred with

TCDD-

sensitive

Long-Evans

Corn oil
gavage (single
dose)

M, F

5-6

Line A:
30-3,000,000
Line B:
30-1,000,000
Line C:
30-100,000

100

300

General
toxicological
endpoints, organ
weights, dental
defects

Decreased thymus
weight

Simanainen et
al. (2003,

198582.)

Mouse/
C57BL/6N
CYP1A2 (+/+)
wild-type

Corn oil
gavage (single
dose)

F

Not specified

0, 30, 100,
300, 1000,
3000, or
10,000

300

1,000

Immunotoxicity

Decreased antibody
response to SRBCs

Smialowicz et
al. (2004,
1109371

Rat/Sprague-
Dawley

Corn oil
gavage (single
dose)

F

5-15

0,0.05,0.1, 1,
10, 100, 1,000,
or 10,000

0.1

(NOEL)

1

(LOEL)

Liver effects

Increase in hepatic
EROD activity and
CYP1A1 mRNA levels

Vanden et al.
(1994. 197551s)

Subchronic toxicity studies

Rat/Sprague-
Dawley

Corn oil
gavage (daily
for 28 days)

F

5

0, 2.5, 25, 250,
or 1,000

250

1,000

Body and organ
weight changes

Decreased body weight,
increased relative liver
weight and related
biochemical changes,
decreased relative
thymus weight

Chu et al.
(2001. 521829s)

Rat/Sprague-
Dawley

Corn oil
gavage (daily
for 28 days)

F

5

0, 2.5, 25, 250,
or 1,000

2.5

25

Liver effects

Alterations in thyroid,
thymus, and liver
histopathology

Chu et al.,
2007

Guinea pig/
Hartley

Daily dietary
exposure
(90 days)

M, F

10/sex

0,0.12,0.61,
4.9, or 26
(males); 0,
0.12,0.68,
4.86, or 31
(females)

0.61

4.9

Body and organ
weight changes

Decreased body weight
(male and females);
increased relative liver
weights (males);
decreased relative
thymus weight (males)

DeCaprio et
al. (1986,
1974031


-------
Table 2-7. Animal bioassay studies considered for noncancer dose-response modeling (continued)



Species/
strain

Exposure
protocol

Sex
(exposure
group)

n

Average daily
dose levels
(ng/kg-day)

NOAEL
(ng/kg-day)

LOAEL

(ng/kg-day)

Endpoint(s)
examined

LOAEL/NOAEL
Endpoint(s)

Reference

Subchronic toxicity studies (continued)

Mice/B6C3F1

Corn oil

gavage
(5 days/week
for 13 weeks)

F

5

0, 1.07, 3.21,
10.7, 32.1, or
107

None

1.07
(LOEL)

Body and organ
weight changes;
enzyme
induction

Increased EROD,
ACOH and

phosphotyrosyl proteins
at all doses

DeVito et al.
(1994,197278)

Rat/Tva:SIV
50-Sprague-
Dawley

Daily dietary
exposure
(13 weeks)

M, F

6

0, 20, 200, or
2,000

None

20

Liver effects

Reduced hepatic
vitamin A levels

Fattore et al.
(2000. 197446s)



Daily dietary
exposure
(13 weeks)

M, F

6

0 or 200













Daily dietary
exposure
(13 weeks)

M, F

6

0, 200, or
1,000













Daily dietary
exposure
(13 weeks, 26,
and 39 weeks)

F

6

0 or 100











Rat/Sprague-
Dawley

Gavage
loading/
maintenance
doses (every
4 days for
14 days)

M, F

6

0, 0.55, 307, or
1,607

0.57

327

Body and liver
weight changes;
hepatic cell
proliferation

Increased absolute and
relative liver weight

Fox et al.

(1993,197344)

Mouse/
B6C3F1

Corn oil

gavage
(5 days/week
for 13 weeks)

F

Not

specified

0,0.32, 1.07,
10.7, or 107

None

0.32
(LOEL)

Brain effects

Induction of biomarkers
of oxidative stress at all
doses

Hassoun et al.
(1998. 136626')


-------
Table 2-7. Animal bioassay studies considered for noncancer dose-response modeling (continued)



Species/
strain

Exposure
protocol

Sex
(exposure
group)

n

Average daily
dose levels
(ng/kg-day)

NOAEL
(ng/kg-day)

LOAEL

(ng/kg-day)

Endpoint(s)
examined

LOAEL/NOAEL
Endpoint(s)

Reference

Subchronic toxicity studies (continued)

Rat/Harlan

Sprague-

Dawley

Corn oil

gavage
(5 days/week
for 13 weeks)

F

6

0,2.14,7.14,
15.7,32.9, or
71.4

None

2.14
(LOEL)

Liver and brain
effects

Induction of biomarkers
of oxidative stress at all
doses in liver and brain

Hassoun et al.
(2000. 197431s)

Rat/Harlan

Sprague-

Dawley

Corn oil

gavage
(5 days/week
for 13 weeks)

F

12

0,7.14, 15.7,
or 32.9

None

7.14
(LOEL)

Brain effects

Induction of biomarkers
of oxidative stress at all
doses

Hassoun et al.
(2003. 198726s)

Rat/Sprague-
Dawley

Corn oil

gavage
(5 days/week
for 13 weeks)

M, F

12

0,0.71,7.14,
71.4, or 714

7.14

71.4

Liver effects,
body weight
changes, and
hematologic and
clinical effects

Reduced body weight
and food consumption,
slight liver degeneration,
lymphoid depletion,
increased urinary
porphyrins and delta
aminolevulinic acid,
increased serum alkaline
phosphatase and
bilirubin

Kociba et al.
(1976. 198594s)

Rat/F344

Corn oil

gavage
(2 days/week
for 28 days)

F

3

0,0.71,7.14,
or71.4

None

0.71
(LOEL)

Clinical signs
and

histopathology

Decreased Cx32 plaque
number and area in the
liver

Mally and
Chipman
(2002. 198098s)

Mouse/
B6C3F1

Corn oil

gavage
(5 days/week
for 13 weeks)

F

Not specified

0,0.11,0.32,
1.07, 10.7, or
107.14

1.07
(NOEL)

10.7
(LOEL)

Liver, lung,
kidney, and
spleen effects

Increased hepatic
superoxide anion

Slezak et al.
(2000. 199022s)

Mouse/
B6C3F1

Corn oil

gavage
(5 days/week
for 13 weeks)

F

8-15

0, 1.07, 10.7,
107, or 321

None

1.07

Immunotoxicity
and organ
weight

Reduced antibody
response to SRBC,
increased relative liver
weight

Smialowicz et
al. (2008,
198341s)


-------
Table 2-7. Animal bioassay studies considered for noncancer dose-response modeling (continued)



Species/
strain

Exposure
protocol

Sex
(exposure
group)

n

Average daily
dose levels
(ng/kg-day)

NOAEL
(ng/kg-day)

LOAEL

(ng/kg-day)

Endpoint(s)
examined

LOAEL/NOAEL
Endpoint(s)

Reference

Subchronic toxicity studies (continued)

Rat/Sprague-
Dawley

TCDD in diet
(13 weeks)

F

8

0, 14, 26, 47,
320, or 1,024

None

14

Multiple end-
points

Decreased absolute and
relative thymus weights,
decreased liver retinoid
levels

Van Birgelen
(1995,197096;
1995, 198052)

Guinea pig/
Hartley

Corn oil

gavage
(weekly for
8 weeks)

F

10

0, 1.14, 5.71,
28.6, or 143

1.14

5.71

Immunotoxicity

Decreased total
leukocytes and
lymphocyte count,
decreased absolute
thymus and weight,
increase in primary
serum tetanus antitoxin

Vos et al.
(1973. 198367s)

Mouse/
B6C3F1

Corn oil
gavage (daily
for 14 days)

F

6-8

0, 10, 50, 100,
500, 1,000, or
2,000

None

10

Immunotoxicity

Reduction of serum
complement activity

White et al.
(1986. 197531s)

Chronic toxicity studies

Rat/CD-
COBS

Corn oil

gavage
(weekly for
45 weeks)

F

4

0, 1.43, 14.3,
or 143

None

1.43

Hepatic
porphyria

Increased urinary
porphyrin excretion

Cantoni et al.
(1981. 197092s)

Rat/Sprague-
Dawley

Loading/
maintenance
dose (every
3 days for
different
durations up to
128 days)

F

5

0,0.85, 3.4,
13.6, 54.3, or
217

(28-day
duration)

54.3

(28-day

duration)

217

(28-day
duration)

Body weight
changes and
changes in
PEPCK activity
and IGF-I levels

Decreased body weight,
decreased PEPCK
activity, and reduced
IGF-I levels

Croutch et al.
(2005. 197382s)

Rat/Sprague-
Dawley

Corn oil

gavage
(5 days/week
for 30 weeks)

F

6

0,2.14,7.14,
15.7,32.9, or
71.4

None

2.14
(LOEL)

Brain effects

Induction of biomarkers
of oxidative stress at all
doses

Hassoun et al.
C2002. 543725s)


-------
Table 2-7. Animal bioassay studies considered for noncancer dose-response modeling (continued)



Species/
strain

Exposure
protocol

Sex
(exposure
group)

n

Average daily
dose levels
(ng/kg-day)

NOAEL
(ng/kg-day)

LOAEL

(ng/kg-day)

Endpoint(s)
examined

LOAEL/NOAEL
Endpoint(s)

Reference

Chronic toxicity studies (continued)

Rat/Sprague-
Dawley

Daily dietary
exposure
(2 years)

M, F

50

0, 1, 10, or 100

1

10

Multiple

endpoints

measured

Increased urinary
porphyrins,

hepatocellular nodules,
and focal alveolar
hyperplasia

Kociba et al.

(1978, 001818)

Rat/Sprague-
Dawley

Biweekly
gavage
(30 weeks)

F

9

0,3.5, 10.7,
35, or 125

10.7

35

Body and organ

weight changes,

clinical

chemistry,

hepatocellular

proliferation

Increased relative liver
weight

Maronpot et
al. (1993,
1983861

Mouse/
B6C3F1;
Rat/Osborne
Mendel

Corn oil

gavage
(2 days/week
for 104 weeks)

M, F

50

0, 1.4, 7.1, or
71 for rats and
male mice; 0,
5.7, 28.6, or
286 for female
mice

None

1.4

Liver and body
weight changes

Increased incidences of
liver lesions in mice
(males and females)

NTP (1982,
543764)

Rat/Sprague-
Dawley

Corn oil

gavage
(5 days/week
for 105 weeks)

F

53

0,2.14,7.14,
15.7,32.9, or
71.4

None

2.14

Liver and lung
effects

Increased absolute and
relative liver weights,
increased incidence of
hepatocellular
hypertrophy, increased
incidence of alveolar to
bronchiolar epithelial
metaplasia

NTP (2006,
1976051

Monkey/
Rhesus

Daily
dietary
exposure
(4 years)

F

8

0, 0.15, or
0.67

None

0.15

General
toxicological
endpoints and
reproductive
effects

Elevated serum
triglycerides and
total lipids

Rier et al.

(2001, 198776;
2001. 5437731


-------
Table 2-7. Animal bioassay studies considered for noncancer dose-response modeling (continued)

S?
>!

rs
st

5

>!
Si

<5"

st

o
>!

>!

o

Si

§•

to
>!

a
o

cs

o
a

>1

Species/
strain

Exposure
protocol

Sex
(exposure
group)

n

Average daily
dose levels
(ng/kg-day)

NOAEL
(ng/kg-day)

LOAEL

(ng/kg-day)

Endpoint(s)
examined

LOAEL/NOAEL
Endpoint(s)

Reference

Chronic toxicity studies (continued)

Rat/Sprague-
Dawley

Biweekly
gavage
(30 weeks)

F

9

0,3.5, 10.7,
35, or 125

None

3.5

(LOEL)

EGFR kinetics
and auto-
phosphorylation,
hepatocellular
proliferation

Decrease in EGFR
maximum binding
capacity

Sewall et al.

(1993, 197889)

Rat/Sprague-
Dawley

Biweekly
gavage
(30 weeks)

F

9

0,0.1,0.35, 1,
3.5, 10.7, 35,
or 125

10.7

35

Thyroid
function

Decreased serum T4
levels

Sewall et al.

(1995,198145)

Mouse/Swiss/
H/Riop

Sunflower oil
gavage
(weekly for
1 year)

M

38-44

0, 1, 100, or
1,000

None

1

Skin effects

Dermal amyloidosis and
skin lesions

Toth et al.
(1979. 197109s)

to
to

^1

o
o

2;

H J

H S.
W K-

oy

o

c
o

H
W

s

ND = not determined.


-------
1

2

3

4

5

6

7

8

9

10

11

12

13

Figure 2-1. EPA's process to select and identify in vivo mammalian and
epidemiologic studies for use in the dose-response analysis of TCDD. EPA

first conducted a literature search to identify studies published since the 2003
Reassessment. Results were published and additional study submissions were accepted
from the public. Next EPA developed TCDD-specific study inclusion criteria for in vivo
mammalian studies and held a Dioxin Workshop where these criteria were discussed and
refined. Third, EPA developed two final sets of study inclusion criteria, one for in vivo
mammalian studies and another for epidemiologic studies. Finally, EPA applied these
two sets of criteria to all studies from the literature search, public submissions, 2003
Reassessment, and additional studies identified by EPA after the Dioxin Workshop
through October 2009. The studies that met these criteria formed a list of key studies for
EPA's consideration in TCDD dose-response assessment.

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

2-248 DRAFT—DO NOT CITE OR QUOTE


-------
1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

Figure 2-2. EPA's process to evaluate available epidemiologic studies using
study inclusion criteria for use in the dose-response analysis of TCDD. EPA

applied its TCDD-specific epidemiologic study inclusion criteria to all studies published
on TCDD and DLCs. The studies were initially evaluated using five considerations
regarded as providing the most relevant kind of information needed for quantitative
human health risk analyses. For each study that was published in the peer-reviewed
literature, EPA then examined whether the exposures were primarily to TCDD and if the
TCDD exposures could be quantified so that dose-response analyses could be conducted.
Finally, EPA required that the effective dose and oral exposure be estimable: (1) for
cancer, information is required on long-term exposures, (2) for noncancer, information is
required regarding the appropriate time window of exposure that is relevant for a specific,
nonfatal health endpoint, and (3) for all endpoints, the latency period between TCDD
exposure and the onset of the effect is needed. Only studies meeting these criteria were
included in EPA's TCDD dose-response analysis.

This document is a draft for review purposes only and does not constitute Agency policy.

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Figure 2-3. EPA's process to evaluate available animal bioassay studies using study
inclusion criteria for use in the dose-response analysis of TCDD. EPA evaluated all
available in vivo mammalian bioassay studies on TCDD. Studies had to be published in
the peer-reviewed literature. Next, to ensure working in the low-dose range for TCDD
dose-response analysis, EPA applied dose requirements to the lowest tested average daily
doses in each study, with specific requirements for cancer (<1 pg/kg-day) and noncancer
(<30 ng/kg-day) studies. Third, EPA required that the animals were exposed via the oral
route to only TCDD and that the purity of the TCDD was specified. Finally, the studies
were evaluated using four considerations regarded as providing the most relevant kind of
information needed for quantitative human health risk analyses from animal bioassay
data. Only studies meeting all of these criteria and considerations were included in
EPA's TCDD dose-response analysis.

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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3. THE USE OF TOXICOKINETICS IN THE DOSE-RESPONSE MODELING FOR

CANCER AND NONCANCER ENDPOINTS

A key recommendation from the National Academy of Sciences (NAS) for improving the
2003 Reassessment was that U.S. Environmental Protection Agency (EPA) should justify its
approaches to dose-response modeling for cancer and noncancer endpoints. Further, the NAS
suggested that EPA incorporate the most up-to-date and relevant state of the science for
2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) dose-response assessment.

While EPA believes that at the time of its release, the 2003 Reassessment offered a
substantial improvement over the general state-of-the-science regarding dose-response modeling,
EPA agrees with the NAS that the justification of the approaches to dose-response modeling can
be improved and the methodologies updated to reflect the most current EPA practices and
science. In Section 3, EPA describes the use of toxicokinetic (TK)11 information in the
dose-response modeling of TCDD. Section 3.1 summarizes the NAS comments regarding the
use of TK in the dose-response approaches for TCDD. Section 3.2 overviews EPA's responses
to the NAS comments. Section 3.3 discusses TCDD kinetics, including TK models developed to
simulate disposition of this compound in rodents and humans (see Section 3.3.4), alternative
measures of dose that could be used in a TCDD dose-response analysis and uncertainties in the
TCDD dose estimates (see Section 3.3.5). Sections 4 and 5 of this document incorporate the TK
information into noncancer and cancer dose response modeling, respectively.

3.1. SUMMARY OF NAS COMMENTS ON THE USE OF TOXICOKINETICS IN
DOSE-RESPONSE MODELING APPROACHES FOR TCDD

The NAS commented on the appropriate use of TK models in dose-response modeling

for TCDD. Specifically, the committee requested that EPA consider using such models to

provide refined estimates of dose, for example, as the underlying science and predictive

capabilities of these models improved.

[Discussing Kinetic models],. .the committee encourages further development and
use of these models as data become available to validate and further develop them
(NAS, 2006, 198441p. 59).

"Toxicokinetics (TK) is that part of the pharmacokinetics (PK) where toxicity is resulted in the organism.

This document is a draft for review purposes only and does not constitute Agency policy.

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Although the NAS basically agreed with EPA's use of body burden as a dose metric in
the 2003 Reassessment (e.g., see NAS, 2006, 198441, p. 7), the NAS was concerned about the
limitations of first order kinetic models, such as the one used in the 2003 Reassessment, to
estimate TCDD body burdens.

TCDD, other dioxins, and DLCs act as potent inducers of CYP, a property that
can affect both the hepatic sequestration of these compounds and their half-lives.

Hepatic sequestration of dioxin may influence the quantitative extrapolation of the
rodent liver tumor results because the body-burden distribution pattern in highly
dosed rats would differ from the corresponding distribution in humans subject to
background levels of exposure. EPA should consider the possible quantitative
influence of dose-dependent toxicokinetics on the interpretation of animal
toxicological data (NAS, 2006, 198441, p. 129).

The NAS also asked EPA to evaluate the impact of kinetic uncertainty and variability on
dose-response assessment. The NAS committee asked EPA to use TK models to examine both
interspecies and human interindividual differences in the disposition of TCDD, which would
better justify EPA dose-response modeling choices.

The Reassessment does not adequately consider the use of a PBPK model to
define species differences in tissue distribution in relation to total body burden for
either cancer or n on cancer end points (NAS, 2006, 198441. p. 62).

EPA ... should consider physiologically based pharmacokinetic modeling as a
means to adjust for differences in body fat composition and for other differences
between rodents and humans (NAS, 2006, 198441, p. 10).

The Reassessment does not provide details about the magnitudes of the various
uncertainties surrounding the decisions EPA makes in relation to dose metrics
(e.g., the impact of species differences in percentage of body fat on the
steady-state concentrations present in nonadipose tissues). The committee
recommends that EPA use simple PBPK models to define the magnitude of any
differences between humans and rodents in the relationship between total body
burden at steady-state concentrations (as calculated from the intake, half-life,
bioavailability) and tissue concentrations. The same model could be used to
explore human variability in kinetics in relation to elimination half-life. EPA
should modify the estimated human equivalent intakes when necessary (NAS,
2006, 198441. p. 73).

This document is a draft for review purposes only and does not constitute Agency policy.

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Finally, the NAS asked EPA to use TK considerations to better justify its choice of dose

metric.

EPA makes a number of assumptions about the appropriate dose metric and
mathematical functions to use in the Reassessment's dose-response analysis ...
but does not adequately comment on the extent to which each of these
assumptions could affect the resulting risk estimates.. .EPA did not quantitatively
describe how this particular selection affected its estimates of exposure and
therefore provided no overall quantitative perspective on the relative importance
of the selection (NAS, 2006, 198441. p. 5 1).

3.2. OVERVIEW OF EPA'S RESPONSE TO THE NAS COMMENTS ON THE USE OF
TOXICOKINETICS IN DOSE-RESPONSE MODELING APPROACHES FOR
TCDD

In response to the NAS recommendations regarding TCDD kinetics and choice of dose
metrics, this document presents an in depth evaluation of TCDD TK models, exploring their
differences and commonalities and their possible application for the derivation of dose metrics
relevant to TCDD. Initially, EPA discusses the application of first order kinetics to estimate
body burden as a dose metric for TCDD. This first order kinetic model is used to predict TCDD
body burden for all of the studies identified as Key Studies (see Section 2.4); this model uses a
constant half-life to simulate the elimination of TCDD from the body. However, given the
observed data indicating early influence of cytochrome P450 1A2 (CYP1A2) induction and
binding to TCDD in the liver and later redistribution of TCDD to fat tissue, the use of a constant
half-life for TCDD clearance following long term or chronic TCDD exposure is not biologically
supported. Therefore, using half-life estimates based on observed terminal steady state levels of
TCDD will not account for the possibility of an accelerated dose-dependent clearance of the
chemical during early stages following elevated TCDD exposures. The biological processes
leading to dose-dependent TCDD excretion are better described using physiologically based
pharmacokinetic (PBPK) models than by simple first order kinetic models. Additionally, as part
of its preparation for developing this document, EPA evaluated recent TCDD kinetic studies as
NAS advocated. Although the NAS agreed with continued use of body burden metric as the
dose metric of choice, EPA believes that the state-of-the-practice has advanced sufficiently to
justify the consideration of alternative dose metrics (other than administered dose) based on an
application of a physiologically-based TK model.

This document is a draft for review purposes only and does not constitute Agency policy.

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EPA identified a number of advances in the overall scientific understanding of TCDD
disposition; many of these are documented in a summary discussion introducing the section on
TCDD kinetics (see Section 3.3). The increased understanding warranted an evaluation of
current kinetic modeling of TCDD to determine if the use of such models would improve the
dose-response assessment for TCDD. Justification of the final PBPK model choice is detailed in
Section 3.3. Through the choice of a published PBPK model to estimate dose metrics for dioxin,
EPA has addressed several of the NAS concerns. The PBPK model can be applied to estimate
dose metrics other than body burden that may be more directly related to response, e.g., tissue
levels, serum levels, blood concentrations, or dose metrics related to TCDD-protein receptor
binding. The selected PBPK model included explicit description of physiological and
biochemical parameters, therefore, it can also provide an excellent tool for investigating
differences in species uptake and disposition of TCDD. One of the criteria used to select a
PBPK model for TCDD kinetics was the availability of both human and animal models so that
differences in species uptake and disposition of TCDD can be investigated. Additionally, the
PBPK model includes quantitative information that is suitable for addressing the impact of
physiological (e.g., body weight [BW] or fat tissue volume), or biochemical (e.g., induction of
CYP1A2) variability on overall risk of TCDD between species, in response to another area of
concern in the NAS report. The sensitivity analysis and uncertainty in dose metrics derived for
the risk assessment of TCDD are also presented in Section 3.3. Detailed discussion on the
uncertainty in choice of PBPK model-driven dose metrics is also provided in Section 3.3.

3.3. PHARMACOKINETICS (PK) AND PK MODELING

3.3.1. PK Data and Models in TCDD Dose-Response Modeling: Overview and Scope

In general, the use of measures of internal dose in dose-response modeling is considered
to be superior to that of administered dose (or uptake) because the former is more closely related
to the response. The evaluation of internal dose, or dose metric, in exposed humans and other
animals is facilitated by an understanding of pharmacokinetics (i.e., absorption, distribution,
metabolism, and excretion). When measurements of internal dose (e.g., blood concentration,
tissue concentration) are not available in animals and humans, pharmacokinetic models can be
used to estimate them. The available data on the pharmacokinetics of TCDD in animals and

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humans have been reviewed (NAS, 2006, 198441; U.S. EPA, 2003, 537122; van Birgelen and
van, 2000, 523248).

It is evident based on these reviews and other analyses that three distinctive features of
TCDD play important roles in determining its pharmacokinetic behavior, as discussed below:

¦	TCDD is very highly lipophilic and thus is more soluble in fat or other relatively
nonpolar organic media than in water. The //-octanol/water partition coefficient is a
commonly-used measure of lipophilicity equal to the equilibrium ratio of a substance's
concentration in //-octanol (a surrogate for biotic lipid) to the substance's concentration
in water (Leo et al., 1971, 019600). For TCDD, this coefficient is on the order of
10,000,000 or more (ATSDR, 1998, 197033). It follows that the solubility of TCDD in
the body's lipid fraction, i.e., the fatty portions of various tissues, including adipose,
organs, and blood, is extremely high.

¦	TCDD is very slowly metabolized compared to many other organic compounds, with an
elimination half life in humans on the order of years following an initial period of
distribution in the body (Carrier et al., 1995, 197618; Michalek et al., 2002, 199579).
Most laboratory animals used for toxicologic testing tend to eliminate TCDD much more
quickly than people, although even in animals TCDD is eliminated much more slowly
than most other chemicals.

¦	TCDD induces binding proteins in the liver that have the effect of sequestering some
of the TCDD. The ability of TCDD to alter gene expression and the demonstration that
the induction of CYP1A2 is responsible for hepatic TCDD sequestration suggest that
both pharmacokinetic and pharmacodynamic events must be incorporated for a
quantitative description of TCDD disposition (Santostefano et al., 1998, 200001). The
induction of these proteins implies that TCDD tends to be eliminated more rapidly in the
early years following short-term, high-level exposures than it is after those initial levels
have declined. Leung et al. (1988, 198815) and Andersen et al. (1993, 196991), in their
PBPK modeling, had taken into consideration the issue of liver protein binding. Recent
efforts of pharmacokinetic modeling have supported the concentration-dependent
elimination of TCDD in animals and humans (Ay 1 ward et al., 2005, 197014; Emond et
al., 2006, 197316).

Sections 3.3.2 and 3.3.3 present the salient features of TCDD pharmacokinetics in
animals and humans, with particular focus on mechanisms and data of relevance to interspecies
and intraspecies variability. Section 3.3.4 describes the various dose metrics for the
dose-response modeling of TCDD and the characteristics of pharmacokinetic models potentially
useful for estimating these metrics. Finally, Sections 3.3.5 and 3.3.6 summarize the results of
application of pharmacokinetic models to derive dose metrics as well as the uncertainty
associated with the predictions of dose metrics used in dose-response modeling. Dose metrics

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derived via PBPK modeling approaches are utilized in Sections 4 and 5 of this document for
noncancer and cancer TCDD dose-response modeling, respectively.

3.3.2. PK of TCDD in Animals and Humans

3.3.2.1.	Absorption and Bioavailability

When administered via the oral route in the dissolved form, TCDD appears to be well
absorbed. Animal studies indicate that oral exposure to TCDD in the diet or in an oil vehicle
results in the absorption of >50% of the administered dose (Nolan et al., 1979, 543785; Olson et
al., 1980, 197976). Human data from Poiger and Schlatter (1986, 197336) indicate that >87% of
the oral dose (after ingestion of 105 ng [3H]-2,3,7,8-TCDD [1.14 ng/kg BW] in 6 mL corn oil)
was absorbed from the gastrointestinal tract. Lakshmanan et al. (1986, 548729). investigating
the oral absorption of TCDD, suggested that it is absorbed primarily by the lymphatic route and
transported predominantly by chylomicrons.

Oral absorption is generally less efficient when TCDD is more tightly bound in soil
matrices. Based on experiments in miniature swine, Wittsiepe et al. (2007, 548736) reported an
approximately 70% reduction in bioavailability when TCDD was administered in the form of
contaminated soil, relative to TCDD after extraction from the same soil matrix with solvents.
Working with soil from the prominent contamination site at Times Beach, Missouri, Shu et al.
(1988, 548739) reported an oral bioavailability of approximately 43% based on experiments in
rats. Percent dose absorbed by the dermal route is reported to be less than the oral route, whereas
absorption of TCDD by the transpulmonary route appears to be efficient (Banks and Birnbaum,
1991, 548742; see, for example; Banks et al., 1990, 548741; Diliberto et al., 1996, 143712;

Nessel et al., 1992, 548743; Roy et al., 2008, 548747; U.S. EPA, 2003, 537122).

3.3.2.2.	Distribution

TCDD in systemic circulation equilibrates and partitions into the tissues where it is then
accumulated, bound, or eliminated. Whereas the bulk of the body tissues are expected to
equilibrate in a matter of hours, the adipose tissue will approach equilibrium concentrations with
blood much more slowly. Consistent with these assertions, a number of experimental and
modeling studies in rats and humans have shown that TCDD has a large volume of distribution
(Vd), i.e., the apparent volume in which it is distributed. The Vd corresponds to the volume of

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blood plus the product of internal tissue volumes and the corresponding tissue:blood partition
coefficients. This parameter is a key determinant of the elimination rate of TCDD in exposed
organisms. The tissue:blood partition coefficients of TCDD, in turn, are determined by the
relative solubility of TCDD in tissue and blood components (including neutral lipids,
phospholipids, and water).

Column 1 in Table 3-1 presents the tissue:blood partition coefficients for TCDD (Emond
et al., 2005, 197317; Wang et al., 1997, 1046571 Column 3 of this table lists the physical
volume of each tissue, scaled to a person weighing 60 kg. The last column shows the
implications of the tissue volumes and tissue:blood partition coefficients for the effective
volumes of distribution for each tissue and for the body as a whole. It can be seen that, purely on
the basis of solubility space, the fat should be expected to contain about 94% of the TCDD in the
body, and that the body as a whole behaves as if it is about 1,200 liters in terms of
blood-equivalents (i.e., approximately 22-fold larger than its physical volume).

Maruyama et al. (2002, 198448) have published another set of tissue/blood partition
coefficients for TCDD and other dioxin congeners based in part on observations of tissue
concentrations measured in autopsy specimens from eight Japanese people without known
unusual exposures to TCDD. Their estimates of TCDD partition coefficients seem to be rather
large and variable, with a fat:blood value of 247 ± 78 (standard deviation [SD]), a liver:blood
value of 9.8 ± 5.7 and a muscle:blood value of 18 ± 10.6. Depending on time of autopsy, tissue
samples may not be an accurate source of information on observed, in vivo partition coefficients
because weight loss is likely to occur pre and post mortem. In particular, a decline in fat stores
volume could lead to an increased concentration of dioxin in fat in autopsy specimens relative to
what would be observed in vivo.

The calculations shown in Table 3-1 do not include the additional amount that will be
bound to induced proteins in the liver. That induction and binding will tend to increase the
contribution of the liver on the effective volume of distribution (Birnbaum, 1986, 548749).

It is also of interest to point out some basic implications of the data in Table 3-1 for the
expected rates of perfusion-mediated transfer of TCDD between blood and each of the
organ/tissues. The rate of loss from a tissue (occurring primarily via blood flow) and the
corresponding half-life can be calculated using the following equations:

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Rate constant for loss (hour" ^) =	Blood flow (liters / hour)	 (Eq 3^

Tissue volume (liters) x Tissue/Blood Partition Coefficent

t1/2 for tissue perfusion loss =	—	

Rate constant for loss

(Eq. 3-2)

_ ln(2) x Tissue volume (liters) x Tissue/Blood Partition Coefficent

Blood flow (liters/hour)

Because TCDD is highly lipophilic, its concentration in the aqueous portion of the blood
is very small, and TCDD tends to partition from blood components into cellular membranes and
tissues, probably in large part via diffusion. As a result, full equilibrium concentrations of
TCDD are not attained by the end of the transit time through organs from the arterial to venous
blood. For organs in which this occurs, diffusion coefficients or "permeability factors" have
been estimated to assess the fractional attainment of equilibrium concentration that occurs by the
time the blood leaving each organ reaches the venous circulation. Table 3-2 presents the
permeability factors and implications for perfusion half-lives for TCDD, per Emond et al. (2005,
197317; 2006, 197316).

Despite the high lipid bioconcentration potential of TCDD, the adipose tissue does not
always have the highest concentration (Abraham et al., 1988, 199510; Geyer et al., 1986,

064899; Poiger and Schlatter, 1986, 197336). Further, the ratios of tissue:tissue concentrations
of TCDD and related compounds (e.g., the livenadipose ratio) may not remain constant during
nonsteady-state conditions. TCDD concentrations have been observed to decrease more rapidly
in the liver than in adipose tissue. For example, Abraham et al. (1988, 199510) found that the
livenadipose tissue concentration ratio in female Wistar rats exposed to a subcutaneous TCDD
dose of 300 ng/kg decreased from 10.3 at 1 day postexposure to 0.5 at 91 days postexposure. It
should be noted that even at a ratio of 0.5, the amount of TCDD in the liver is greater than that
based on lipid content of the tissue alone, consistent with the presence of hepatic TCDD binding
proteins. The liver/adipose tissue ratio also was dose-dependent, such that the liver TCDD
burden increased from ~11% of the administered dose at low doses (i.e., 1-10 ng/kg) to -37% of
the dose at an exposure level of 300 ng/kg. The increase in TCDD levels in liver, accompanied
by a decrease in concentration in the adipose tissue, is a particular behavior to be considered in
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high dose to low dose extrapolations. This behavior is essentially a result of dose-dependent
hepatic processes, as described below.

3.3.2.3. Metabolism and Protein Binding

The metabolism of TCDD is slow, particularly in humans, and it is thought to be
mediated by the CYP1A2 enzyme that is inducible by TCDD (Olson et al., 1994, 198008;
Ramsey et al., 1982, 548750; Weber et al., 1997, 548753; Wendling et al., 1990, 548751). The
low rate of metabolism in combination with sequestration appear to account for the retention of
TCDD in liver, and these processes collectively contribute to the long half4ife for elimination of
TCDD from the body.

Dynamic changes in TCDD binding in liver and partitioning to fat have been studied
extensively in rats and mice (Diliberto et al., 1995, 197309; 2001, 197238). Figure 3-1 shows
observations by Diliberto et al. (1995, 197309) of the ratio of liver concentrations to adipose
tissue concentrations for mice given doses spread over a 100-fold range and studied at four
different times following exposure. It can be seen that even for the lowest dose studied the
liver:fat concentration ratio is higher than would be expected based on the lipid contents of the
tissues (i.e., 0.06:1, corresponding to the ratio of human liver:blood and fat:blood partition
coefficients; see Table 3-1). Moreover, the relative concentration in the liver consistently rises
with dose, with the steepest rise observed during the first two weeks after dosing. If the
distribution of TCDD were governed solely by passive partitioning into fat, there should be no
such change in relative concentrations with dose. However, data presented in Figure 3-1
illustrate that at longer time points, the ratio of TCDD in the liver to TCDD in fat decreases,
indicating that a redistribution of the chemical occurs as time goes on for each applied dose. The
redistribution of TCDD tissue levels from liver to fat with increasing time suggests that binding
of the chemical in the liver (including via induction of CYP1A2) is an important kinetic
consideration at early exposure points with relatively high applied doses.

Experiments with CYP1A2 "knock-out" mice (i.e., congenic strains differing in only a
single gene that is "knocked out" in one of the strains) indicate that the inducible binding of
TCDD is attributable to CYP 1A2 (Diliberto et al., 1997, 548755; 1999, 143713). As noted
previously, this enzyme is believed to make an important contribution to metabolism of TCDD.
Given the critical role of CYP1A2 induction in the kinetics of TCDD, dose-and time-dependent

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induction of this protein in rats has been examined and modeled (Emond et al., 2004, 197315;
Emond et al., 2006, 197316; Santostefano et al., 1998, 200001; Wang et al., 1997, 104657).
Accordingly, the amount of CYP1A2 in the liver can be computed as the time-integrated product
of inducible production and a simple first-order loss process (Wang et al., 1997, 104657):

dCYP

—-f*L = S(t)K0 - K2CA2t	(Eq. 3-3)

at

where CYP2ai is the concentration of the enzyme, K2 is the rate constant for the first order loss,
Ca2i is the concentration of CYP1A2 in the liver, K0 is the basal rate of production of CYP1A2 in
the liver, and S(t) is a multiplicative stimulation factor for CYP1A2 production in the form of a
Hill-type function:

^nA2 (CAh-TCDD )

(icA2)h +(CAh_TCDD)h

S(t) = 1 + h rCDD „	(Eq. 3-4)

where ICa2 corresponds to the concentration of the aryl hydrocarbon (Ah)-TCDD complex at
which half of the maximum fold stimulation of CYP2A production is reached, and h, the Hill
exponent, determines the curvature of the stimulation in relation to concentration of the
Ah-TCDD complex at relatively low doses. A value of 0.6 as the Hill exponent has been used by
Wang et al. (1997, 104657; 2000, 198738) and Emond et al. (2004, 197315; 2005, 197317; 2006,
1973 16). indicative of a negative cooperation, i.e., the curve is convex-upward (supralinear),
depicting a faster increase in the low-dose region compared to a straight line. Additional
parameters in this expression include IriA2, the maximum fold increase in the CYP1A2 synthesis
rate over the basal rate that can occur at high levels of TCDD, and (Cah-tcdd), the concentration
of TCDD bound to the aryl hydrocarbon receptor (AhR). This concentration in turn depends on
the concentration of TCDD in the liver (Cuf), the concentration of the AhR (Ah/ ,) in liver, and
the dissociation constant for the Ah-TCDD receptor complex, KDAh-

Ahr. x Cnf

C,™ = „ *	(Eq. 3-5)

^DAh ~T~ Lif

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3.3.2.4.	Elimination

Elimination half-lives (i.e., the time taken for the concentration to be reduced to one-half
of its initial level) of TCDD range from 11 days in the hamster to 2,120 days in humans
(U.S. EPA, 2003, 537122). Hepatic metabolism and binding processes, fecal excretion, and
accumulation in adipose tissue collectively determine the dose-dependent elimination half-lives
in various species. Ay 1 ward et al. (2005, 197114) depicted the relationship between the
elimination rate versus initial level of lipid-corrected TCDD in serum for 36 people (see
Figure 3-2). Even though this analysis was done using the initial TCDD level, rather than the
geometric mean or midpoint level in the decline for each person, it indicated a
concentration-dependency of the half-life and elimination of TCDD in exposed individuals.

3.3.2.5.	Interspecies Differences and Similarities

Among the pharmacokinetic determinants of TCDD, some are known to vary markedly
between species whereas others are not characterized sufficiently in this regard. Overall, the
qualitative determinants of the body burden and elimination half-lives appear to be similar across
species. Based on empirical observations for TCDD as well as with other PCDFs, Carrier et al.
(1995, [97618; 1995, 543780) argued that in rats, monkeys, and humans, the dose-dependent
changes in the fraction contained in liver and adipose tissue follow a similar pattern across
species. The authors suggested that the half-saturation body burden is around 100 ng/kg and the
plateau of liver dose (as fraction of body burden) appears to occur around 1,000 ng/kg.

Literature also indicates that AhR is conserved phylogenetically (Fujii-Kuriyama et al., 1995,
543727; Harper et al., 2002, 198124; Nebert et al., 1991, 543728) and is present in mammalian
species, including experimental animals and humans (Lorenzen and Okey, 1991, 198397;
Manchester et al., 1987, 198054; Okey et al., 1994, 548759; Roberts et al., 1985, 198706;

Roberts et al., 1986, 198780). These qualitative similarities in pharmacokinetic determinants and
outcome support the use of animal data to infer general patterns of the pharmacokinetic behavior
of TCDD in humans. However, quantitative differences in determinants, including
physiological, physicochemical, and biochemical, need to be taken into account. Even though
species-specific physiological parameters can be obtained from the literature, key data on
species-specific biochemical parameters (particularly binding constants, maximal capacity,
induction rates, and other parameters) are not available for humans at this time. However, these

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can be inferred by using a pharmacokinetic model fit to in vivo data on the rate of TCDD
elimination from specific compartments in humans (Ay 1 ward et al., 2005, 197014; Carrier et al.,
1995, 197618; Carrier et al., 1995, 543780; Emond et al., 2004, 197315; Emond et al., 2005,
197317; Emond et al., 2006, 197316).

3.3.3. PK of TCDD in Humans: Interindividual Variability

TCDD pharmacokinetics and tissue doses vary across the human population as a function
of the interindividual variability of the key kinetic determinants. Because the NAS comments
focused on health effects associated with chronic, lifetime exposure, the key kinetic determinants
for such exposures include clearance, binding, and temporal changes in volume of distribution.
When considering the interindividual variability in pharmacokinetics and dose metrics of TCDD,
it is important to recognize that the elevated lipid-corrected serum concentrations in highly
exposed persons are associated with greater elimination rates, probably due to greater degrees of
induction of CYP1A2 in the liver and possibly other related metabolic enzymes (Abraham et al.,
2002, 197034; Aylward et al., 2005, 197014; Emond et al., 2006, 197316; Grassman et al., 2000,
548762).

The interindividual variability in fat content is a critical parameter in pharmacokinetic
models given the characteristics of TCDD (see Section 3.3.2). Both metabolic elimination and
elimination via the GI tract depend on the fraction of TCDD in the body that is available outside
of adipose tissue. As body fat content rises, a smaller portion of the total body TCDD will be
contained in the relatively available fraction outside of the adipose tissue. Because elimination
of TCDD by both metabolism and fecal excretion depends on the small proportion of TCDD that
exists outside of fat tissue, people with larger proportions of body fat—including many older
people—will tend to require longer times to reduce TCDD levels by a given proportion than
leaner people (Emond et al., 2006. 197316; Rohde et al., 1999. 548764; Van der Molen et al.,
1998, 548765; Van der Molen, et al., 1996, 548768).

The sections that follow highlight key aspects of interindividual variability in TCDD
pharmacokinetics, with an emphasis on the available data related to elimination half-lives and
volume of distribution.

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3.3.3.1. Life Stage and Gender

The influence of the variability of fat content in human population on the distribution and
clearance of TCDD has been evaluated by several investigators. There are data showing an
inverse dependency of TCDD elimination rate on percent body fat. Figure 3-3 shows this
relationship in a study in which TCDD elimination via feces was measured in six people in
relation to their body fat content (Rohde et al., 1999, 548764). Observations of TCDD
elimination rates in a small number of men and women in the Seveso cohort (Aylward et al.,
2005, 197114) provide a modest opportunity to compare TCDD elimination rates with actual
human data. Based on the partition coefficients reported by Emond et al. (2006, 197316), the
elimination rates for the men in the sampled group are expected to be greater than the elimination
rates in the women. Taking into consideration calculations similar to those shown in Table 3-2,
and fat proportions inferred from body mass indices using the equations of Lean et al. (1996,
548770). the Seveso men studied are expected to have an overall average of about 3.92% of their
TCDD body burden outside of fat, whereas the women are expected to have an average of only
2.36% outside of fat. On this basis, the TCDD elimination rates in the men are expected to be
3.92/2.36 = 1.66 times faster than the elimination rates in the women. By comparison, Michalek
et al. (2002, 199579) reported observed elimination rates in men and women that result in a
slightly lower ratio:

men:0. Ill year1 ±0.010 (std.error) , ^

							— = 1.56	(Eq. 3-6)

women :0.071 year ± 0.010 (std. error)

The central estimates for the elimination rates correspond to half lives of 6.5 and 9.6 years for
men and women, respectively.

A further point of comparison can be derived using the observed body mass index

12

(BMI) and TCDD elimination rate of each of the male Ranch Hand military veterans, whose
TCDD elimination rates were observed between 9 and 33 years after their time in Vietnam. The
average BMI over that time was 29.44 (based on 287 measurements for the 97 veterans,
tabulated in three periods by Michalek et al., 2002, 199579), and their average age was about

12The body mass index, or BMI, is calculated as the body weight in kilograms divided by the square of the height in
meters.

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44.5 for the measurements. Based on these data, the corresponding average estimated percent
body fat is 29.7% using the Lean et al. (1996, 548770) formula for men. The observed average
TCDD elimination rate constant for these men for the period was 0.092 year-1 ± 0.004 (standard
error), corresponding to a half life of 7.5 years. This half life is slightly longer than the central
estimate of the half life of 6.2 years (i.e., ln(2)/0.111) for the smaller group of Seveso males with
their slightly smaller estimated percent body fat. Figure 3-4 shows a simple plot of these data
and a fitted unweighted regression line characterizing the relationship between estimated fat
content and TCDD elimination rates. Variation in metabolic enzyme activities and other routes
of loss is also likely to be important, but there is little human quantitative information available
on these issues.

More recently, Kerger et al. (2006, 198651) estimated the slope of the relationship
between half-life and age to be 0.12 years (95% confidence interval, 0.10-0.14), which
corresponds to the rate of increase in TCDD half-life for each year of age. The authors
speculated that although age explained most of the variance in the individual half-life trends, it
was also correlated with TCDD concentration, BMI, and body fat mass. The regression model
developed by these authors discriminated between the high and low TCDD exposures or
concentrations. Thus, after accounting for the TCDD (concentration x age) term's effect on the
slope of age, the final model for TCDD concentration <700 ppt was

t\ / 2 = 0.35 + 0.12 x Age	(Eq. 3-7)

For TCDD concentration >700 ppt, the final model was:

t\ / 2 = 0.35 + 0.088 x Age	(Eq. 3-8)

where tm is the half-life and Age is the age at time of subsequent sampling. Pharmacokinetic
information relevant to specific age groups is presented in the sections that follow.

3.3.3.1.1. Prenatal period.

Data to estimate TCDD elimination rates for fetuses are not available. Levels of TCDD
in fetal tissues for rats were experimentally estimated at different gestational periods and utilized
in a developmental model by Emond et al. (2004, 197315). There is information on body

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composition that is relevant to prediction of TCDD dose to fetus. These data, summarized as
part of the radiation dosimetry model of the International Commission on Radiological
Protection, are consistent with the idea that early fetuses are nearly all water and less than
1% lipid, and lipid levels rise toward parity with protein near the time of normal delivery.

Bell et al. (2007, 197050) reported that the disposition of TCDD into the fetus shows
dose dependency, with a greater proportion of the dose reaching the fetus at lower doses of
TCDD. Further, both CYP1A1 and CYP1A2 are highly inducible (~103-fold) in fetal liver,
whereas CYP1A2 shows much lower induction (10-fold) in maternal liver. It has been
speculated that this is due to the lower basal levels of CYP1A2 in fetal liver, as compared to
maternal liver (Bell et al., 2007, 197050). The greater relative disposition to the fetus at low
doses may be the result of higher bioavilalibty due to less hepatic sequestration and elimination
in the mother.

3.3.3.1.2. Infancy and childhood.

Hattis et al. (2003, 548773) describe the general pattern of change of body fat content
with age in children. Central tendency values for percent body fat begin at about 12% at birth
and rise steeply to reach about 26% near the middle of the first year of life. Fat content then falls
to reach a minimum of approximately 15% at 5-8 years of age, followed by a sex-dependent
"adiposity rebound" that takes females to about 26% body fat while the males remain near
16-17%) on average by age 20. The interindividual variability distributions about these central
values are complex, as some children experience the "adiposity rebound" earlier than others, and
this creates patterns that are not simply interpretable as unimodal normal distributions. Hattis et
al. (2003, 548773) did find it possible to fit distributions of body fat content inferred from
NHANES skin fold measures to mixtures of two normal distributions for children between age 5
and 18.

At least two groups of authors have published PBPK modeling results indicating
generally more rapid clearance of TCDD in children than in adults, a trend that is consistent with
the generally lower fat content of children (Kreuzer et al., 1997, 198088; Leung et al., 2006,
548779; V an der Molen et al., 2000, 548777). The rapid expansion of the adipose tissue
compartment can contribute, in part, to the reduced apparent half-life in children (Clewell et al.,

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2004, 056269). This reduction may also be due to varying rates of metabolism and/or fecal lipid
excretion (Abraham et al., 1996, 548782; Kerger et al., 2007, 548784).

Furthermore, very young children have different modes and quantities of exposure
compared to adults. Lakind et al. (2000, 198094) characterize distributions of milk intake for
nursing infants to characterize distributions of TCDD exposure. This is also a corresponding
route of loss of TCDD stores for lactating women, as described in Section 3.3.3.2 below.

3.3.3.1.3. Adulthood and old age.

The fraction of fat in relation to body weight in adulthood and old age can be computed
as a function of the BMI and age (e.g.. Lean et al., 1996, 548770):

% Body Fat (males) = 1.33 x BMI + 0.236 x Age - 20.2	(Eq. 3-9)

% Body Fat (females) = 1.21 x BMI + 0.262 x Age - 6.7	(Eq. 3-10)

The above equations are the result of analysis of data based on underwater weighing of
63 men and 84 women (age range 16.8-65.4). The salient observation with respect to TCDD for
these data is that age and BMI-dependent variability in fat content have implications for the
variability in TCDD elimination rates and internal dose among adults.

3.3.3.2. Physiological States: Pregnancy and Lactation

Data on body fat content in pregnant women at various stages of gestation (Pipe et al.,
1979, 548786) have potential implications for TCDD elimination rates during pregnancy, even
though the relationship between these parameters has not been formally analyzed.

Lactation is viewed as an additional route of elimination for some chemicals such as
TCDD. According to a recent study, a breast-feeding woman expels through lactation an
estimated 8.76 kg fat per year [^/(kg/day), 0.8 kg milk/day with an average 3% lipid], and the
partition coefficient between blood lipid and milk fat (£bm) for TCDD is 0.92 (Milbrath et al.,
2009, 198044; Wittsiepe et al., 2007, 548736). The estimated rate of elimination of TCDD due
to breast-feeding (kbfed) can then be computed as follows (Milbrath et al., 2009, 198044):

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k,

'bfed

(Eq. 3-11)

where

A^bfed (unitless) = the fraction of the year during which the woman was actively breast-
feeding;

Assuming no interaction between breast-feeding and other half-life determinants
Milbrath et al. (2009, 198044). the authors predicted a half-life of 4.3 years for TCDD in a
30-year-old, nonsmoking woman with 30% body fat if she did not breast-feed that year, and a
half-life of 1.8 years if she breast-fed for 6 months.

3.3.3.3. Lifestyle and Habits

One of the factors related to lifestyle and habits that could influence TCDD kinetics is
smoking. Smoking has been reported to enhance the elimination of dioxin and dioxin-like
compounds (Ferriby et al., 2007, 548789; Flesch-Janys et al., 1996, 197351). Milbrath et al.
(2009, 198044) accounted for interindividual variation in body composition as well as smoking
habits in an empirical model. The predicted half-life (years) for an individual i as a function of
age, smoking status, and percent body fat i was as follows

Pbf

BW

woman's percent body fat; and
woman's body weight in kg.

where

(0 age)

intercept constant derived from regressed data;

slope constant derived from regressed data;

pbfi

age,

specific age i (years);
individual percent body fat;

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Ptfmfiage,) = reference percent body fat; and

SFj	= the unitless, multiplicative smoking factor.

3.3.3.4. Genetic Traits and Polymorphism

One particular genetic locus that is potentially related to TCDD pharmacokinetics and
tissue dose is the gene for the AhR. Eight candidate AhR polymorphisms have been identified to
date (Connor and Ay 1 ward, 2006, 197632; Harper et al., 2002, 1981241 Given the role of AhR
in regulating the induction of CYP1 isozymes (Baron et al., 1998, 548791; Connor and Ay 1 ward,
2006, 197632; Toide et al., 2003, 548792). the polymorphism might lead to interindividual
differences in metabolic clearance, the significance of which would depend upon the dose, fat
content, and exposure scenario. In this regard, it should be noted that the inducibility of aromatic
hydrocarbon hydroxylase in human tissues has been reported to be highly variable, up to
100-fold (Connor and Ay 1 ward, 2006, 197632; Smart and Daly, 2000, 548794; Wong et al.,
1986, 548795).

Finally, the scientific literature contains values of K& (the dissociation constant of the

TCDD-AhR complex) ranging from about 1 to much higher values (corresponding to lower
binding affinity) (reviewed in Connor and Ay 1 ward, 2006, 197632). This provides suggestive
evidence for a heterogeneous human AhR, with functionally important polymorphisms (Micka et
al., 1997, 548797; Roberts et al., 1986, 198780). even though some of the range may be
attributed to experimental procedural differences and to other factors (Connor and Aylward,
2006, 197632; Harper et al., 2002, 198124; Lorenzen and Okey, 1991, 198397; Manchester et
al., 1987. 198054).

The various pharmacokinetic processes and determinants (see Sections 3.3.2 and 3.3.3),
individually or together, might influence the dose metrics of relevance to the dose-response
modeling of TCDD.

3.3.4. Dose Metrics and Pharmacokinetic Models for TCDD

3.3.4.1. Dose Metrics for Dose-Response Modeling

The dose metric related to a toxicologic endpoint can range from the maximal
concentration, the area under a time-course curve (AUC), or the time-averaged concentration of

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the toxic moiety in the body, blood, or target tissue, to an appropriate measure of the resulting
interactions in the target tissue (e.g., receptor occupancy or functional biomarkers related to
specific effects). A single dose metric, however, is unlikely to be sufficient for all endpoints and
exposure durations. Further, the ideal dose metric chosen on the basis of the mode of action
(MO A) may not be the dose metric for which model predictions can be obtained with a high
level of confidence. Consideration of these issues is critical to the selection of the dose metrics
of relevance to dose-response modeling of TCDD.

Figure 3-5 lists a range of alternative dose metrics for TCDD in terms of their relevance
based on considerations of pharmacokinetic mechanisms and MOA. The administered dose or
daily intake (ng/kg-day) is the least relevant dose metric for dose-response modeling of TCDD.
This dose adjusts only for body weight differences between species. The administered dose,
when used with an uncertainty factor for kinetics (or kinetic adjustment factor, such as BW3 4)
and an uncertainty factor for dynamics, can also account for allometrically-predicted
pharmacokinetic (clearance) and pharmacodynamic differences between species in deriving the
human equivalent dose (HED). In effect, the use of kinetic and dynamic adjustment or
uncertainty factors facilitates the computation of HED. Such a calculation of HED is associated
with the steady-state blood concentration of parent chemical in rats by accounting for species
differences in metabolic clearance. This is generally done by relating to body surface area or
metabolic rates, with no corresponding temporal changes in the volume of distribution (see, for
example, Krishnan and Andersen, 1991, 548799). Such calculations of HED for TCDD may not
be appropriate given that (1) steady-state was not attained in all critical toxicological studies
chosen for the assessment, (2) the clearance is mainly due to enzyme(s) and processes whose
levels/rates do not necessarily vary across species or life stages as a function of body surface
differences, and (3) there is a likelihood of change in volume of distribution over time.
Furthermore, the use of administered dose does not explicitly account for the dose-dependent
elimination of TCDD from tissues as demonstrated in multiple studies (reviewed in
Sections 3.3.2 and 3.3.4). The use of administered dose in TCDD dose-response modeling is
unlikely to facilitate the characterization of the true relationship between the response and the
relevant measures of internal dose that are influenced by dose-dependent elimination and binding
processes. Additionally, the use of administered dose to extrapolate across species or life stages

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would not effectively take into account the differences in fat content or the demonstrated dose-
dependent and species-dependent differences in elimination half-life of TCDD.

Dose metrics for TCDD may include absorbed dose, body burden, serum or whole blood
concentration, tissue concentration, and possibly functional-related metrics of relevance to the
MOA (e.g., receptor occupancy, change in protein levels). These measures can be calculated as
a current (terminal), average (over a defined period), or integral quantity. The applicability of
the integral measures, such as the AUC (i.e., the area under the curve of a plot of blood or
plasma concentration vs. time), traditionally used for analyzing chronic toxicity data, is
questionable in the case of TCDD. This is because of differences in lifespan and uncertainties
regarding the appropriateness of the duration to be specified for averaging the AUC in
experimental animals and humans for certain critical effects (NAS, 2006, 198441).

Among the alternative dose metrics, the absorbed dose accounts for differences in body
weight as well as species-specific differences in bioavailability. Thus, the absorbed dose is
equivalent to body burden. Body burden, or more appropriately the body concentration,
represents the amount of TCDD per kg body weight. TCDD body burdens, like other dose
measures, can be determined as the peak, the average over the period of the bioassays, or the
level at the end of the experiments. Thus, the terminal or average body burdens can be obtained
either using data or pharmacokinetic models and used in dose-response modeling. The body
burden is a measure of TCDD dose that reflects the net impact of bioavailability, uptake,
distribution, and elimination processes in the organism. It is essentially a function of the volume
of distribution and clearance processes, and as such it does take into account the temporal
changes in volume of distribution as well as the concentration-dependent clearance. These are
phenomena that are critical to the understanding of TCDD dose to the target. However, the body
burden may not accurately reflect the tissue dose (NAS, 2006, 198441). and as such does not
allow for analysis of species-specific differences in target organ sensitivity to TCDD. In
essence, the body burden represents only an "overall average" of TCDD concentration in the
body, without regard to the differential partitioning and accumulation in specific tissues,
including the target tissue(s).

Serum (or blood) concentration of TCDD is a dose metric that reflects both the body
burden and the dose to target tissues. Serum or blood concentration, at steady-state, would be
reflective of the impact of clearance processes, and expected to be directly proportional to the

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tissue concentrations of TCDD (NAS, 2006, 198441). This dose metric for lipophilic chemicals
such as TCDD is often expressed as a lipid-normalized value, to adjust for varying serum lipid
content (e.g.; DeKoning and Karmaus, 2000, 548801; Niskar et al., 2009, 548802) (Patterson et
al., 2009), particularly in human biomonitoring studies, thus of relevance to dose-response
modeling; however, the serum lipid-normalized concentrations of TCDD are not routinely
collected and reported in animal toxicologic studies. Serum lipid-adjusted of TCDD
concentration is calculated as the ratio of serum TCDD content over serum lipid content per unit
volume. Alternatively, TCDD serum lipid-normalized calculation can be estimated by using the
formula TL = (2.27 x TC) +TG + 62.3 mg/dL where the total lipid (TL) content of each sample
is estimated from its total cholesterol (TC) and triglyceride (TG) (Patterson et al., 2009). The
lipid-adjusted serum concentration, however, would be reflective of the lipid-adjusted
concentration of TCDD in other organs (reviewed in Ay 1 ward et al., 2008, 197068) depending
upon the extent of steady-state attained and the similarity of lipid composition across tissues in
each species. In essence, the serum lipid-normalized measure is representative of the amount of
TCDD per specified volume of total lipids, whereas the whole blood measure will be reflective
of the ensemble of free, lipid-bound and protein-bound TCDD in plasma and erythrocytes, which
may be species-specific. Even though these dose metrics are thought to be more closely and
directly related to the tissue concentrations associated with an effect, a less direct association
might occur at increasing doses when nonlinear processes dominate the kinetics and distribution
of TCDD into organs such as the liver.

Tissue concentration of TCDD, as free, bound, or total TCDD, is a more relevant
pharmacokinetic measure of dose, given that it provides a measure of exposure of the target cells
to the chemical. In this regard, the CYP1A2-bound fraction may be considered as a relevant
dose metric for certain toxic effects; however, the available data contain mixed results regarding
the mechanistic linkage of this dose metric to toxicity and carcinogenicity (reviewed in Budinsky
et al., 2006, 594248). In such cases, the use of alternative dose metrics (e.g., bound
concentration as well as the serum concentration) in dose-response modeling could be
considered. Other function-related biomarkers and dose metrics could facilitate the additional
consideration of pharmacodynamic aspects reflecting tissue- and species-specific sensitivity.
These metrics represent the most relevant measures of tissue exposure and sensitivity to TCDD.

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Empirical time-course data on the alternative dose metrics of TCDD associated with
epidemiologic and experimental (animal) studies are not available, requiring the use of
pharmacokinetic models to obtain estimates of these dose metrics. These models may be simple,
based on first order kinetics (see Section 3.3.4.2), or more complex based on physiochemical,
biochemical, and physiological parameters for simulating uptake, distribution (including
sequestration to proteins), and clearance of TCDD (see Section 3.3.4.3). Receptor occupancy
and functional biomarkers as dose metrics for TCDD require a clear understanding of mode of
action of TCDD and availability of relvant data. In the absence of such information, these
possible dose metrics can not be utilized at the present time.

3.3.4.2. First-Order Kinetic Modeling

Figure 3-6 illustrates the process of estimating a human-equivalent TCDD oral exposure
from an experimental animal-administered dose, based on the assumption that body burden is the
effective dose metric for TK equivalence across species. The primary assumption is that the
time-weighted average (TWA) TCDD body burden over some critical time period is the
proximate toxicokinetically-effective dose eliciting a toxicologic effect.13 The process consists
of estimating the effective average body burden in the experimental animal over some time tA
(generally the experimental duration) using a TK model, then "back-calculating" a daily human
exposure level that would result in that average body burden over some time tH (the human
equivalent to tj\).

The following closed-form equation is the general formula used to calculate a TCDD
terminal body burden in an experimental animal or human at time (t).

BB(t) = BB(0) +	^a	(Eq. 3-13)

where

BB(t)

BB( 0)
d
k

= the body burden at time t (ng/kg);
= the initial body burden (ng/kg);
= the daily dose (ng/kg-day);
= the whole-body elimination rate (days-1);

13The conversion depicted in Figure 3-6 does not account for toxicodynamic differences between species.

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t = the time at which the body burden is determined (days); and
fa = the fraction of oral dose absorbed (unitless).

7	d a(\ -	fa a

For the experimental animal, BB(t) is RR \ (I) = RR \ (0)e ¦' ¦' H	, and for

kA

humans, this parameter is BBH(t) = BBH (0)e~l¦ 1),
the latter ratio approaches unity, reducing the animal :human conversion factor to the ratio of the
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half-lives. The latter approach was used in the 2003 Reassessment for conversion of animal
cancer slope factors to the human equivalent, where only lifetime exposures are relevant.14

However, for less-than-lifetime exposures eliciting noncancer effects, specific values for
tA and In must be considered. Furthermore, Eq. 3-16 computes dH on the basis of terminal body
burdens at times tA and in. The more representative metric for toxicokinetic equivalence based
on average body burden over the respective time periods is given in Eq. 3-17.

BB(t) = BB(0)- f e-kTdr + d^-~ f (1 -	= BB(0)

tJ	k t J

kt	k	kt

(Eq. 3-17)

On the basis of average body burden as given in Eq. 3-17, is transformed again assuming
minimal initial body burden (BB(0) ~ 0), as follows:

d.



-ri h'lA

~ dA 		

1-

1

_e-kAfA j

*1/2 H

I kAfA
\ 
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higher for earlier exposure periods) and is health protective for effects occurring after
shorter-term exposure.15 Figure 3-7 depicts the relationship of daily dose to TWA body burden
graphically for several exposure duration scenarios. For shorter durations occurring later in life,
the average body burden over the exposure period does not differ substantially from the
steady-state value. Even for half-lifetime exposures, the deviation of the average from steady
state is minimal. Only for lifetime exposures does the difference become more marked, but only
by about 15%. Note that in the 2003 Reassessment, a constant value of 3,000 was used for
BBH(t): dH, based on the relationship of continuous exposure to theoretical steady-state body
burden (t = lifetime, t<: = 2,593 days); this approach, while conservative, does not account for
exposure scenarios of different durations and does not strictly reflect the average body burden
dose metric.

The simulation in Figure 3-7 is based on a unit daily exposure to humans, such that the
target body burden represents BBH(tH)'dH as a general scalar for calculating dH from any given
dA. Table 3-3 shows the resulting TK conversion factors for the rodent species and strains
comprising the bulk of the experimental animals in TCDD studies. Monkey and mink values are
not shown in this table because, for the former, only chronic exposures were evaluated and, for
the latter, no TCDD half-life information is available. Monkey (Rhesus) half-life estimates
range from about 200-500 days. A representative value of 365 days is used for this TCDD
assessment. The dA to dH conversion factor for the chronic monkey exposures (3.5-4 years) in
TCDD studies is 9.2-9.7 (BBA:dA = 279-263).

Application of first order kinetics for the risk assessment of TCDD can only be used to
estimate total body burdens or back-calculate administered dose from experimental data. Body
burden calculations using first order kinetics is based on the assumption of a first order decrease
in the levels of administered dose as function of time. In that sense, any loss of TCDD from the
body is described by using a rate constant that is not specific to any biological process. This
constant is usually estimated from estimates of half-life of TCDD. Assuming a constant half-life
value for the clearance for long-term or chronic TCDD exposure is not biologically supported
given the observed data indicating early influence of CYP1A2 induction and binding to TCDD
and later redistribution of TCDD to fat tissue. Abraham et al. (1988, 199510) found that the
liver:adipose tissue concentration ratio in female Wistar rats exposed to a subcutaneous TCDD

15See the following section (3.3.4.3) for a more detailed discussion of this concept.

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dose of 300 ng/kg decreased from 10.3 at 1 day postexposure to 0.5 at 91 days postexposure.
Consequently, using half-life estimates based on observed steady-state levels of TCDD will not
account for the possibility of accelerated dose-dependent clearance of the chemical at the early
stages and thus would result in estimation of lower administered levels of the chemical. The
dynamic change in half-life due to dose-dependent elimination at the early stages of TCDD
exposure and its later redistribution to fat tissues for steady-state levels is better described using
biologically-based models, such as the PBPK models and concentration- and age-dependent
elimination (CADM) models (Ay 1 ward et al., 2005, 197014; Carrier et al., 1995, 197618; Carrier
et al., 1995, 543780; Emond et al., 2004, 197315; Emond et al., 2005, 197317; Emond et al.,
2006, 197316). Additionally, these models provide estimates for other dose metrics (e.g., serum
or tissue levels) that are more biologically relevant to response than administered dose or total
body burden (see Section 3.3.4.3).

3.3.4.3. Biologically-Based Kinetic Models

The development and evolution of biologically-based kinetic models for TCDD have
been reviewed by EPA (2003, 537122) and Reddy et al. (2005, 594251). The initial PBPK
model of Leung et al. (1988, 198815) was developed with the consideration of TCDD binding to
CYP1A2 in the liver. The next level of PBPK models by Andersen et al. (1993, 196991) and
Wang et al. (1997, 104657) used diffusion-limited uptake and described protein induction by
interaction of DNA binding sites. The models of Kohn et al. (1993, 198601) and Andersen et al.
(1997, 197172) further incorporated extensive hepatic biochemistry and described zonal
induction of CYP by TCDD. TCDD PBPK models have evolved to include detailed descriptions
of gastrointestinal uptake, lipoprotein transport, and mobilization of fat, as well as biochemical
interactions of relevance to organ-level effects (Kohn et al., 1996, 022626; Roth et al., 1994,
198063). Subsequently, developed PBPK models either used constant hepatic clearance rate
(Maruyama et al., 2002, 198448; Wang et al., 1997, 104657; Wang et al., 2000, 198738) or
implemented varying elimination rates as an empirical function of body composition or dose
(Andersen et al., 1993, 196991; Andersen et al., 1997, 197172; Kohn et al., 1996, 022626;
Van der Molen et al., 1998, 548765; Van der Molen et al., 2000, 548777). The more recent
pharmacokinetic models explicitly characterize the concentration-dependent elimination of
TCDD (Ay 1 ward et al., 2005, 197014; Carrier et al., 1995,. ; Carrier et al., 1995, 543780;

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Emond et al., 2004, 197315; Emond et al., 2005, 197317; Emond et al., 2006, 197316). The
biologically-based pharmacokinetic models describing the concentration-dependent elimination
(i.e., the pharmacokinetic models of Ay 1 ward et al. (2005, 197014) and Emond et al. (2005,
197317; 2006, 197316) are relevant for application to simulate the TCDD dose metrics in
humans and animals exposed via the oral route. The rationale for considering the application of
Ay 1 ward et al. (2005, 197014) and Emond et al. (2004, 197315; 2005, 197317; 2006, 197316)
models for estimating dose metrics for possible application to TCDD risk assessment is based on
the following considerations.

•	Both models represent research results from the more recent peer-reviewed publications.

•	Both models are relatively simple and less parameterized than earlier kinetic models for
TCDD. The Ay 1 ward et al. (2005, 197014) model is based on two-time scale TCDD
kinetics described by Carrier et al. (1995, 197618). and the Emond et al. (2004, 197315;
2005, 197317; 2006, 1973 16) PBPK models are reduced versions of earlier complex
PBPK models. Although simple, both the Ay 1 ward et al. (2005, 197014) and Emond et
al. (2004, 197315; 2005, 197317; 2006, 197316) models are still inclusive of important
kinetic determinants of TCDD disposition.

•	Both models are uniquely formulated with dose-dependent hepatic elimination consistent
with the physiological interpretations commonly accepted by the scientific community.

•	Both models and extrapolated human versions were tested against human data collected
in a variety of human exposure scenarios (Ay 1 ward et al., 2005, 197014; Emond et al.,
2005, 197317).

•	Both models are capable of deriving one or more of the candidate dose-metrics that are of
interest to EPA's dose-response assessment of TCDD.

3.3.4.3.1. CADM model.

3.3.4.3.1.1. Model structure.

The pharmacokinetic model of Ay 1 ward et al. (2005, 197014). referred to as the CADM
model in this report, is based on an earlier model developed by Carrier et al. (1995, 197618;
1995, 543780) that describes the dose-dependent elimination and half-lives of polychlorinated
dibenzo-p-dioxins and furans. This model describes the TCDD levels in blood (body), liver, and
adipose tissue. Blood itself is not characterized physically as a separate compartment within the
model, and the distribution of TCDD to tissues other than adipose tissue and liver (usually less
than 4%) is not accounted for by the model. The original structure of the Carrier et al. (1995,

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197618; 1995, 543780) model was modified by Ay 1 ward et al. (2005, 197014) to include TCDD
elimination through partitioning from circulating lipids across the lumen of the large intestine
into the fecal content (see Figure 3-8). The most recent version of the Carrier model (Aylward et
al., 2005, 197014; 2008, 197068) includes fecal excretion of TCDD from two routes:

(1)	elimination from circulating blood lipid through partitioning into the intestinal lumen; and

(2)	elimination of unabsorbed TCDD from dietary intake.

A basic assumption of this model is that metabolic elimination of TCDD is a function of
its current concentration in the liver. The current concentration of TCDD in the liver increases
with increasing body burden in a nonlinear fashion as a result of the induction of (and binding of
TCDD to) specific proteins (i.e., CYP1A2). Consequently, the fraction of TCDD body burden
contained in the liver increases nonlinearly (with a corresponding decrease in the fraction
contained in adipose tissues) with increasing body burden of TCDD (Aylward et al., 2005,
197114; Carrier et al., 1995, 197618).

Of particular note is that the adipose tissue compartment of the model is considered to
represent the lipid contained throughout the body. It then assumes that the concentrations of
TCDD in lipids of plasma and various organs is essentially equivalent to that of adipose tissue,
and as such these concentrations are included in the adipose compartment of the model. Even
though this approximation is fairly reasonable given the available data, there is some concern
that the adipose compartment of this model also includes the lipid content of the liver to some
unknown extent. Removal of lipid volume from the liver would mathematically alter total
hepatic concentration and therefore would affect the estimated levels of the chemical available
for binding to proteins.

Distribution in the body is modeled to occur between hepatic and adipose/lipid
compartments, with the fraction of body burden in liver increasing according to a function that
parallels the induction of the binding protein CYP1A2. Elimination is modeled to occur through
hepatic metabolism (represented as a first-order process with rate constant K that decreases with
age) and through lipid-based partitioning of unmetabolized TCDD across the intestinal lumen
into the gut, which is also modeled as a first-order process. As the body burden increases, the
amount of TCDD in the liver increases nonlinearly, resulting in an increased overall elimination
rate.

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3.3.4.3.1.2.	Mathematical representation.

The CADM model describes the distribution to tissues (including liver and adipose
tissue) based on exchange from blood at time intervals of one month. The model is based on
quasi-steady-state-approximation, and thus it is also based on the consideration that the
intertissue processes reach their equilibrium values "quasi-instantaneously." In this regard,
absorption and internal distribution reflective of kinetics at the cellular level (e.g., diffusion,
receptor binding, and enzyme induction) likely occur on a relatively fast time scale (a few hours
to a few days). However, the overall body concentration (i.e., body burden) varies slowly with
time such that it remains virtually unchanged during short time intervals.

The CADM model does not differentiate between binding to AhR and CYP1A2, and it
lacks explicit descriptions of CYP1A2 induction, a key determinant of TCDD kinetics.

However, the empirical equation in the CADM model is based on five parameters (i.e., fmin, fmax,
K, Wa, and Wi; see Tables 3-4 and 3-5) that allow the successful description of the behavior of
TCDD in liver and adipose tissue (i.e., TCDD half-lives in each compartment increase with
decreasing body burden). This observation implies that the model adequately accounts for the
ensemble of the processes. Essentially, the CADM model describes the rate of change in tissue
concentrations of TCDD as a function of total body burden such that the global elimination rate
decreases with decreasing body burden or administered dose.

3.3.4.3.1.3.	Parameter estimation.

The CADM model is characterized by its simplicity and fewer parameters compared to
physiologically-based models. Reflecting this simplicity, hepatic extraction is computed with a
unified empirical equation that accounts for all relevant processes (i.e., protein induction and
binding).

The key parameters (fmin. fmax, K, and ke) were all obtained by fitting to species-specific
pharmacokinetic data. The physiological parameters (such as tissue weights) used in the model
are within ranges documented in the literature. The fat content is described to vary as a function
of age, sex, and BMI. However, the BMI of the model is not allowed to change during an
individual simulation (which can range from 20 years to 70+ years) when in reality the
percentage of fat in humans changes over time. None of the TCDD-specific parameters were
estimated a priori or independent of the data set simulated by the model.

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3.3.4.3.1.4. Model performance and degree of evaluation.

The CADM model was not evaluated for its capabilities in predicting data sets not used
in its parameterization. In other words, one or more of the key input parameters (fhmin, fhmax, ke,
K) was or were obtained essentially by fitting to the species-specific pharmacokinetic data, such
that there was no "external" validation data set to which the model was applied. Despite the lack
of emphasis on the "external" validation aspect, the authors (Ay 1 ward et al., 2005, [97114);
(Carrier et al., 1995, 197618; Carrier et al., 1995, 543780) have demonstrated the ability of the
model to describe multiple data sets covering a range of doses and species.

The visual comparison of the simulated data to experimental values suggests that the
model could, to an approximate degree, correctly reproduce the whole set of data (e.g.,
pharmacokinetic [PK] profile over a range of dose and time) and not just part of the PK curve,
essentially with the use of a single set of equations and parameters.

The pharmacokinetic data sets for TCDD that were used to calibrate/evaluate the CADM
model by Aylward et al. (2005, _ I; Carrier et al., 1995, ^ , Carrier et al., 1995,

543780) included the following:

•	Adipose tissue and liver concentrations of TCDD following a single oral dose of 1 |ig/kg
in monkeys (McNulty et al., 1982, 543782);

•	Percent dose retained in liver for a total dose of 14 ng in hamsters (Van den Berg et al.,
1986, 543781);

•	Elimination kinetics of TCDD in female Wistar rats following a single subcutaneous dose
of 300 ng/kg (data from Abraham et al., 1988, 199510);

•	Liver and adipose tissue concentrations (terminal measurements) in Sprague-Dawley rats
given 1, 10 or 100 ng TCDD/kg bw during 2 years (Kociba et al., 1978, 001818); and

•	Serum lipid concentrations of TCDD over a period of several years in 54 adults (29 men
and 25 women) from Seveso and in three Austrian patients (Aylward et al., 2005,

197114).

For illustration purposes, Figure 3-9 shows model simulations of rat data from Carrier et
al. (1995, 197618). Figure 3-2 (see Section 3.3.2.4) depicts the human data that were used by the
authors to support the concentration-dependent elimination concept; the model was
parameterized to fit approximately to these data (Aylward et al., 2005, 197114).

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The authors did not report any specialized analyses that quantitatively evaluated the
uncertainty, sensitivity, and/or variability of CADM model parameters and structure.

3.3.4.3.1.5. Confidence in CADM model predictions of dose metrics.

A qualitative level of confidence associated with the predictability and reliability of
absorbed dose and body burden for oral exposures in humans (as well as several animal species)
by this model can be ranked as high (see Table 3-6). This model, however, does not account for
the differential solubility of TCDD in serum lipids and adipose tissue lipids, nor does it account
for the diffusion-limited uptake by adipose tissue. Due to these limitations, the confidence
associated with the predictions of the serum lipid concentration of TCDD is considered medium,
particularly when it is not documented that steady-state is reached during the critical toxicologic
studies and human exposures. Furthermore, the CADM model does not facilitate the
computation of TCDD concentrations in specific internal organs (other than liver and adipose
tissue). The reliability of this model for simulating the liver concentration (free, bound, or total)
of TCDD at low doses is considered to be low. This low confidence level is a result of the
uncertainty associated with the key parameter /hmin- This parameter needs to be re-calibrated for
each study/species/population to effectively represent the free fraction of TCDD in liver and the
amount of TCDD contained in the hepatic lipids and bound to the liver proteins (whose levels
might be reflective of background exposures of various sources; see Carrier et al., 1995,

197618). The uncertainty related to the numerical value of this parameter in animals and
humans—particularly at very low exposures—raises concern regarding the use of this model to
predict TCDD concentration (free, bound, or total) in liver as the dose metric for dose-response
modeling. Although the use of the parameter /hmax permits the prediction of the dose to liver at
high doses, it does not specifically facilitate the simulation of the amount bound to the protein or
level of induction in liver. Because the CADM model is not capable of simulating enzyme
induction based on biologically-relevant parameters, its reliability for predicting the
concentration of TCDD bound specifically to the AhR is not known. Finally, due to the lack of
parameterization or verification with kinetic data in pregnant, lactating, or developing animals or
humans, the CADM model is unlikely to be reliable in the current form for use in predicting
potential dose metrics in these subpopulations or study groups that might form the basis of points
of departure (PODs) for the assessment.

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3.3.4.3.2. PBPK model.

3.3.4.3.2.1. Model structure.

Emond et al. (2004, 197315; 2006, 197316) simplified the eight-compartment rat model
of Wang et al. (1997, 104657) to a four-compartmental model (liver, fat, rest of body and
placenta with fetal transfer) (Emond et al., 2004, 197315), and later to a three-compartment adult
model (liver, fat, rest of the body) (Emond et al., 2006, 197316) (see Figures 3-10 and 3-1 1).
Their rationale for simplification of the model was based on evaluating, critiquing, and
improving all earlier PBPK models by Wang et al. (1997, 104657). In general, the main reason
for the simplification was that extrapolation of a PBPK model to humans with these many (i.e.,
eight compartments) compartments would be problematic due to the limited availability of
relevant human data for validation (Emond et al., 2004, 197315). One major difference from
earlier models, repeatedly emphasized by Emond et al. (2005, 197317; 2006, 197316), was their
description (included in their simplified PBPK models) of the dose-dependent, inducible
elimination of TCDD. The rationale for including TCDD binding and induction of CYP1A2 into
the model was earlier described by Santostefano et al. (1998, 200001).

The most recent version of the rat and human PBPK models developed by Emond et al.
(2006, 197316) describes the organism as a set of three compartments corresponding to real
physical locations—liver, fat, and rest of the body—interconnected by systemic circulation (see
Figure 3-10). The liver compartment includes descriptions of CYP1A2 induction, which is
critical for simulating TCDD sequestration in liver and dose-dependent elimination of TCDD. In
this model, the oral absorption of TCDD from the GI tract accounts for both the lymphatic (70%)
and portal (30%) systems.

The biological relationship between TCDD "sequestration" by liver protein and its
"elimination" by the liver is not entirely clear. TCDD is metabolized slowly by unidentified
enzymes. CYP1A2 is known to metabolize TCDD based on studies in CYP1A2 KO mice
(Diliberto et al., 1997, 548755; 1999, 1 >), in which the metabolic profile is different
compared to wild-type mice. However, since several metabolites appear in the feces of CYP1A2
knock out mice, it is assumed that there are other enzymes involved in TCDD metabolism.

TCDD binds to the AhR and induces not only CYP1A2, but also CYP1A1, CYP1B1, and several
UGTs and transporters (Gasiewicz et al., 2008, 473406). Both hydroxylated and glucuronidated
hydroxyl metabolites are found in the feces of animals treated with TCDD (Hakk et al., 2009,

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594256). Because the exact enzymes involved with TCDD are unknown and yet the metabolism
is induced by TCDD, an assumption of increased the elimination rate of TCDD in proportion to
the induction of CYP1A2 is made. In the PBPK model, CYP1A2 is needed because TCDD
binds to rat, mouse, and human CYP1A2 (Diliberto et al., 1999, 143713; Staskal et al., 2005,
198276). Thus CYP 1A2 induction is necessary to describe TCDD pharmacokinetics due to
TCDD binding. Hence, CYP1A2 can be used as a marker of Ah-receptor induction of "TCDD
metabolizing enzymes." Other models use AhR occupancy as a marker of induction of "TCDD
metabolizing enzymes" (Andersen et al., 1997, 197172; Kohn et al., 2001, 198767).

Figure 3-11 depicts the structure of the rat developmental-exposure PBPK model (Emond
et al., 2004, 197315). This model was developed to describe the relationship between maternal
TCDD exposure and fetal TCDD concentration during critical windows of susceptibility in the
rat. In formulating this PBPK model, Emond et al. (2004, 197315) reduced the original
8-compartment model for TCDD in adult rats by Wang et al. (1997, 104657) to a 4-compartment
(i.e., liver, fat, placenta, and rest of the body) model for maternal rat. Activation of the placental
compartment and a separate fetal compartment occurs during gestation (Emond et al., 2004,
197315).

3.3.4.3.2.2. Mathematical representation.

The key equations of the PBPK model of Emond et al. (2004, 197315) are reproduced in
Text Boxes 3-1 and 3-2, whereas those from Emond et al. (2005, 197317; 2006, 197316) are
listed in Table 3-7. The rate of change of TCDD in the various tissue compartments is modeled
on the basis of diffusion limitation considerations. Accordingly, mass balance equations are
used to compute the rate of change in the tissue (i.e., intracellular compartment) and tissue blood
(i.e., extracellular compartment). The membrane transfer of TCDD is computed using a
permeation coefficient-surface area cross product (PA) for each tissue. Metabolism and binding
of TCDD to the AhR and inducible hepatic protein (CYP1A2) are described in the liver. The
total mass in the liver was then apportioned between free dioxin (Cif) and bound forms of TCDD
(see Figure 3-12). The dose- and time-dependent induction of hepatic CYP1A2 in the liver is
described per Wang et al. (1997, 104657) and Santostefano et al. (1998, 200001). Accordingly,
the amount of CYP1A2 in the liver was computed as the time-integrated product of inducible
production and a simple first-order loss process (Wang et al., 1997, 104657):

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dCYP

= S(t)K0 - K2CA2t	(Eq. 3-19)

at

In this expression, CYPm2 is the concentration of the enzyme (nmol/g), K2 is the rate constant for
the first order loss (hour-1), Ca2i is the concentration of CYP1A2 in the liver (nmol/g), K0 is the
basal rate of production of CYP1A2 in the liver (nmol/g.hr), and S(t) (unitless) is a multiplicative
stimulation factor for CYP1A2 production in the form of a Hill-type function (see
Section 3.3.2.3):

S(t) = 1 +

InA2 (CAh-TCDD )

(ICA2f+(CAh_TCDD)h

(Eq. 3-20)

where, S(t) is the stimulation function, In a 2 is the maximum fold of CYP1A2 synthesis rate over
the basal rate, Cah-tcdd is the concentration of AhR occupied by TCDD, and ICa2 is the
Michaelis-Menten constant of CYP1A2 induction (nM). The dose-dependent or variable
elimination of TCDD was described using the relationship:

KBILE LI =

CYP\A2mduced-CYP\A2basal

CYPIA2

'basal

x Kelv

(Eq. 3-21)

where CYPlA2inciUCed is the concentration of induced CYP1A2 (nmol/mL), CYPlA2baSai is the
basal concentration of CYP1A2 (nmol/mL), and Kelv is the interspecies constant adjustment for
the elimination rate (hour-1).

There are various ways of formulating the dose-dependent elimination as a function of
the level of CYP1A2, and the above equation (used by the authors) can be viewed as one means
of describing this behavior quantitatively. The numerator in the equation above will always be
greater than zero when there is TCDD in the system (including TCDD derived from either
background exposures or defined external sources). Consequently, the rate of elimination will
correspond to a nonzero value for situations involving TCDD exposures. Furthermore, the
numerator in Eq. 3-21 should more appropriately be CYPlA2inciUCed rather than \CYP\h2induced-
CYP\A2Basai] to avoid the problem of lower levels of induction at low doses resulting in a lower

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than basal rate of synthesis of CYP1A2. The above equation, however, does not describe
changes in elimination rate in direct proportionality with the CYP1A2 levels; also, the Kelv value
by itself does not reflect a scalable basal metabolic rate. Rather, these two terms collectively
describe the outcome related to the TCDD elimination processes, based on fitting to observations
in rats (Santostefano et al., 1998, 200001). The impact of CYP1A2 induction and sequestration
on binding and elimination of TCDD is simulated using the Emond et al. (2004, 197315) model.

The gestational model consisted of a fetal compartment, and the transfer of TCDD
between the placental and fetal compartments was described as a diffusion-limited (rather than a
perfusion-limited) process (see Text Boxes 3-1 and 3-2).16

Text Box 3-1.

Variation of Body Weight with Age: B WTjme(g) = B W initial x

( BWmother\7

' 0.41 x Tim e ^
1402.5 + Tim e

Cardiac Output: Oc(mL h) = Occ X 60

v 1,000 j

A factor of 60 corresponds to the conversion of minutes to hours, and 1,000 is the conversion of
body weight from g to kg.

Blood Compartment:

Cb(nmol ml.) =

((Of x Cft>) + (Ore x Creb) + (Oli x Clib) + (Opla x Cplab) + Lymph)) - (Cb x Clru)

Qc

" Diffusion limited, sometimes also known as "membrane limited," means a chemical's movement from one side of
the membrane to the other is limited by the membrane. Thus, the membrane, in this case, is a limiting factor for
uptake. Perfusion limited, also known as "flow limited" indicates that a chemical is so rapidly taken up (e.g., by the
tissue from the blood) that the flow rate is the only limiting factor.

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Text Box 3-2.

Placenta Tissue Compartment
(a) Tissue-blood subcompartment

dAplab ^nm()j _ Qpja(Qa _ Cplab) + PApla(Cplab - Cplafree)
dt

Cplab =

Aplab
Wplab

(b) Tissue cellular matrices

/ h) = PApIafCplab - Cplafree) - dAt>k'-fe> + d^<-P'"
dt	dt	dt

Cpla{nmol / mL) =

Apia

Wpla

Free TCDD Concentration in Placenta

Cplafree{nmol / mL) = Clpla -

(iCplafree x Ppla +

Plabmax x Cplafree
Kdpla + Cplafree

1

2

Dioxin Transfer from Placenta to Fetuses

dAPla _ fet ^nmQj / j^ = CJpla fet x Cpla

dtt

Dioxin Transfer from Fetuses to Placenta

dAfet Pla (imol /h)=	x

dt

Fetal Dioxin Concentration (Fetuses 5 = Per Litter)

dAfet, , .,. dAPla fet dAfet Pla
-{nmol7 /?) = - -

dt

Cfet(fimol / h) =

dt

dt

Afet
Wfet

CfetV (nmol / mL) =

Cfet
Pfet

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3.3.4.3.2.3. Parameter estimation.

Table 3-8 lists the numerical values of the adult rat and human PBPK models of Emond
et al. (2005, 197317; 2006, 197316). The values for key input parameters of the rat gestational
model are summarized in Table 3-8 as well as Figure 3-13.

The parameters for the rat model were obtained primarily from Wang et al. (1997,

104657) except that the value of affinity constant for CYP1A2 was changed from 0.03 to
0.04 nmol/mL to get better fit to experimental data (Emond et al., 2004, 197315) and the variable
elimination parameter (Kelv) was obtained by optimization of model fit to kinetic data from
Santostefano et al. (1998, 200001) and (Emond et al., 2005, 197317; Emond et al., 2006,

1973 16; Wang et al., 1997, 104657). Wang et al. (1997, 104657) used measured tissue weights
whereas the tissue blood flows and tissue blood weights were obtained from International Life
Sciences Institute (ILSI, 1994, 046436). The partition coefficients (which were similar to those
of Leung et al., 1988, 198815; 1990, 192833). the permeability x area (PA) value for tissues, the
dissociation constant for binding to CYP1A2 (ICa2) and the Hill coefficient (h) were estimated
using a two-stage process of fitting to dose-response and time-course data on TCDD tissue
distribution (Wang et al., 1997, 104657). In the initial stage, the experimental data of arterial
blood concentrations were used as input to the individual compartment to estimate the
parameters; then, with the values obtained during stage one as initial estimates, those unknown
parameters were re-estimated by solving the entire model at once using an optimization route
(Wang et al., 1997, 104657). The receptor concentrations and dissociation constant of TCDD
bound to AhR were obtained by fitting the model to TCDD tissue concentration combining with
enzyme data reported by Santostefano et al. (1998, 200001) whereas the basal CYP1A2 in liver
was based on literature data (Wang et al., 1997, 104657).

The parameters for the human PBPK model were primarily based on the rat model
(Emond et al., 2005, 197317; Emond et al., 2006, 197316; Wang et al., 1997, 104657).
Specifically, the blood fraction in the tissues, the tissue:blood partition coefficients, tissue
permeability coefficient, the binding affinity of TCDD to AhR and CYP, and the maximum
binding capacity in the liver for AhR were all set equal to the values used in the rat model. The
species-specific Kelv was estimated by fitting to human data (Emond et al., 2005, 197317).

For the gestational rat model, the parameters describing the growth of the placental and
fetal compartments as well as temporal change in blood flow during gestation were incorporated

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based on existing data. Exponential equations for the growing compartments were used (see
Figure 3-13), except for adipose tissue for which a linear increment based on literature data was
specified. While physiological parameters for the pregnant rat were obtained from the literature,
all other input parameters were set equal to that of nonpregnant rat (obtained from Wang et al.,
1997, 104657). see Tables 3-7 and 3-8. The current version of the rat gestational model contains
parameters for variable elimination from Emond et al. (2006, 197316; Table 3-8), and still
provides essentially the same predictions as the original publication (Emond et al., 2004,
197315V

3.3.4.3.2.4. Model performance and degree of evaluation.

The PBPK model of Emond et al. (2004, 197315; 2005, 197317; 2006, 197316) had
parameters estimated by fitting to kinetic data, such that the resulting model consistently
reproduced the kinetic data. The same model structure with a single set of species-specific
parameters could reproduce the kinetics of TCDD following various doses and exposure
scenarios not only in the rat but also in humans. The simulations of the PBPK model of Emond
et al. (2006, 197316) have been compared with two sets of previously published rat data: blood
pharmacokinetics following a single dose of 10 |ig/kg (the dose corresponding to the mean
effective dose for induction of CYP1A2) (Santostefano et al., 1998, 200001) (see Figure 3-14);
and hepatic TCDD concentrations during chronic exposure to 50, 100, 500, or 1,750 ng/kg
(Walker et al., 1999, 198615) (see Figure 3-15). It is relevant to note that the PBPK model of
Emond et al. (2004, 197315; 2006, 197316) is essentially a reduced version of the Wang et al.
(1997, 104657) model, and it therefore provides simulations of liver and fat concentrations of
TCDD that deviated by not more than 10-15% of those of Wang et al. (1997, 104657). The
nongestational model of Emond et al. (2004, 197315) simulated the kinetic data in liver, fat,
blood and rest of body of female Sprague-Dawley rats given a single dose of 10 |ig TCDD/kg
(data from Santostefano et al., 1996, 594258) and in liver and fat of male Wistar rats treated with
a loading dose of 25 ng4g followed by a weekly maintenance dose of 5 ng TCDD/kg by gavage
(data from Krowke et al., 1989, 198808).

The gestational rat PBPK model simulated the following PK data sets (Emond et al.,
2004, 197315):

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•	TCDD concentration in blood, fat, liver, placenta, and fetus of female Long-Evans rats
given 1, 10, or 30 ng4g, 5 daysAveek, for 13 weeks prior to mating followed by daily
exposure through parturition (Hurst et al., 2000, 198806);

•	TCDD concentration in tissues (liver, fat), blood, placenta and fetus determined on
gestation day (GD) 16 and GD 21 following a single dose of 0.05, 0.8, or 1 (J,g/kg given
on GD 15 to pregnant Long Evans rat (Hurst et al., 2000, 199045);

•	Maternal and fetal tissue concentrations on GD 9, GD 16 and GD 21 after a single dose
of 1.15 jag TCDD/kg given to Long-Evans rats on GD 9 or GD 15 (Hurst et al., 1998,

134516); and

•	Fetal TCDD concentrations determined on GD 19 and GD 21 in rats exposed to
5.6 (.ig TCDD/kg on GD 18 (Li et al., 2006, 199059).

Furthermore, the scaled rat model was shown to be capable of simulating human data
from the Austrian and Seveso subjects (see Figures 3-16 and 3-17). In this regard, it is useful to
note that the computational version of the PBPK model of Emond et al. (2005, 197317; 2006,
197316) also contained the necessary equation to transform the model output of blood
concentration into serum lipid adjusted concentration of TCDD.

The human model of Emond et al. (2005, 197317; Emond model) has advantages for
improving the TCDD dosimetry used in existing human epidemiological studies because the
model predicts the redistribution of TCDD within the body (to stores in fat and liver) based on
physiological principles. However, because the dose-dependency of metabolic elimination in the
Emond model was not calibrated to human data, it is important to review the predictions of this
model using a database of human observations that is as extensive as possible and a spread of
internal TCDD concentrations that is as wide as possible. Thus, presented below is a
juxtaposition of modeled elimination rates from the Emond model with observations for
two highly exposed Austrian patients (severe intoxication of "unknown origin" (Geusau et al.,
2001, 197444)) and nine of 10 Ranch Hand veterans17 used for the original "validation"
comparisons presented in the Emond et al. (2005, 197317).

Figure 3-18 shows the time course of the declines in TCDD serum concentrations in
two highly-exposed Austrian subjects compared with the Emond model results. The comparison
in Figures 3-17 and 3-18 indicates that the Emond model adequately describes the rate of TCDD

17In preliminary comparisons, the simulation run for the 10th Ranch Hand veteran appeared anomalous and was
therefore excluded from this summary.

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elimination for the more highly exposed Austrian patients, but predicts a somewhat faster rate of
decline than that observed for the less heavily exposed patient.

Figure 3-19 shows the results of combining the simulated and observed rates of loss for a
group of Austrian and Ranch Hand subjects evaluated by Emond et al. (2005, 197317). counting
only one data point per person. The X-axis in this figure is the TCDD serum concentration at the
midpoint of the observations for each subject. The error bars in the figure represent ±1 standard
error. The results of this figure illustrate two points: (1) the Emond model simulation (open
squares) are generally very close to the actual data (solid circles) for the nine Ranch hands
(clustered toward lower left corner) and one of the the two Austrian patients (upper right corner);
and (2) both the Emond model simulation results and the actual data show a linear trend and
linear regression lines were plotted, respectively, as shown in Figure 3-19.

Table 3-9 presents the results of regression analyses of the observed rates of decline in
relation to the estimated TCDD serum levels at the midpoint of the observations for each subject
in the Ranch Hand study (see Figure 3-19). These results indicate that some appreciable dose
dependency of TCDD elimination is unequivocally supported. However, the central estimate of
the slope of the relationship between the log of the TCDD elimination rate and the log of the
TCDD level is only about 75% of that expected under the Emond et al. PBPK model
(i.e., 0.092-0.123 = 0.748).

Overall, the conclusion from the above analysis is that the Emond model is reasonable to
use, but the model might be improved by (1) include the two nondose-dependent pathways of
elimination documented in the Geusau papers (GI elimination via the feces and loss via the
sloughing of skin cells), and (2) reducing the extent of loss via the dose-dependent metabolism
pathway from the liver (Geusau et al., 2002, 594259; Harrad et al., 2003, 197324) so that overall
loss rates for the average elimination rates from the Ranch Hand veterans is maintained.

A sensitivity analysis of inputs used to estimate inducible elimination rate for a single
oral dose of 0.001 to 10 ng/kg in the rat indicated that the number of key parameters ranged from
seven at the low dose region to 12 at the high dose (see Figure 3-20)(Emond et al., 2006,

1973 16). The sensitive parameters identified included the oral absorption parameters (KABS),
volumes of liver and adipose tissue (WLIO, WFO), adipose tissue:blood partition coefficient
(PF), and the basal CYP1A2 level (CYP1A2 1A2). At high doses, the most sensitive parameters

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also included those related to the maximal induction of CYP1A2 and AhR binding capacity (see
Figure 3-20) (Emond et al., 2006, 1973161

The gestational rat model described in Emond et al. (2004, 1973151 upon
reparameterization, could simulate the kinetics of TCDD in mice. The initial changes to the rat
model parameters included: rest of the body:blood partition coefficient (PRE), basal
concentration (CYP1 A2_l A2), delay in induction time (CYP1A21TAU) and adipose tissue
permeability coefficient (PAFF), in accordance with Wang et al. (2000, 198738) (see Table 3-8).
Subsequently, four parameters (adipose tissue:blood partition coefficient, CYP1A2 affinity
parameter, GI tract elimination transit constant (hour-1) and the interspecies metabolic parameter
Kelv (hour-1) were re-estimated based on visually fit of model simulations to the PK data from
Diliberto et al. (2001, 1972381 following an oral dose 150 ng TCDD/kg/day, 5 days/week for
17 weeks (see Table 3-7). The resulting mouse model is capable of reproducing the kinetics of
TCDD in the adult (see Figures 3-21 through 3-27), as well as, to a very limited extent, the
kinetics during gestation (see Figure 3-28).

3.3.4.3.2.5. Confidence in PBPK model predictions of dose metrics.

The PBPK model facilitates prediction of absorbed dose, body burden, and blood
concentration of TCDD for oral exposures in adult humans and rats (adult and developing) with
high confidence (see Table 3-10). The model output of blood concentration can be normalized to
lipid content representative of the study group (species, sex, age, lifestage, and diet). However,
the PBPK model of Emond et al. (2004, 197315; 2005, 197317; 2006, 197316) does not simulate
plasma and erythrocyte TCDD concentrations separately, and it predicts tissue concentrations on
the basis of tissue:whole blood partition coefficients and not on the basis of serum
lipid-normalized values.

The reliability of this model for simulating the liver concentration of TCDD in rats is
considered to be high but it is considered to be medium for humans. Although empirical data on
bound or free concentrations were not used to evaluate model performance in humans, the
biological phenomena (consistent with available data) related to the hepatic sequestration,
enzyme induction, and dose-dependent elimination are described in the model. This is one of the
situations where PBPK models are uniquely useful; that is, they permit the prediction of system
behavior based on understanding of the mechanistic determinants, even though the required data
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cannot be directly obtained in the system (e.g., bound concentrations in the liver of exposed
humans). For these dose measures (i.e., bound concentration and total liver concentration), the
level of confidence can be further improved or diminished by the outcome of sensitivity analysis.
In this regard, the results of a focused sensitivity analysis indicate that the most sensitive
parameters of the human model are among the most uncertain (i.e., those parameters for which
estimates were not obtained in humans) with respect to prediction of liver TCDD concentration,
contrary to the animal model (see Section 3.3.6).

With respect to the mouse model, however, the level of confidence is low to medium,
given that it has not been verified extensively with blood, body burden, or tissue concentration
time-course or dose-response data. However, the mouse PBPK model, based on the rat model
that has been evaluated with several PK data sets, has been shown to reproduce well the limited
mouse liver kinetic data (see Figures 3-21 through 3-28; Boverhoff et al., 2005, 594260). The
same model structure has been used for simulating kinetics of TCDD in humans successfully.
Overall, the adult mouse model, given its biological basis combined with its ability to simulate
TCDD kinetics in multiple species, is considered to exhibit a medium level of confidence for
simulating dose metrics for use in high to low dose extrapolation and interspecies (mouse to
human) extrapolation. Even though similar considerations are applicable to gestational model in
mice, the confidence level is considered to be low since very limited comparison with empirical
data has been conducted (see Figure 3-28). Despite the uncertainty in these predictions, the
scaled rat gestational model, given its biological and mechanistic basis, might be of use in
predicting dose metrics in these groups that might form the basis of PODs in certain key studies.

3.3.4.4. Applicability of PK Models to Derive Dose Metrics for Dose-Response Modeling of
TCDD: Confidence and Limitations

Both the CADM and PBPK models describe the kinetics of TCDD following oral
exposure to adult animals and humans by accounting for the key processes affecting kinetics,
including hepatic sequestration phenomena, induction, and nonlinearity in elimination, and
distribution in adipose tissue and liver. Both models can be used for estimating body burdens
and serum lipid adjusted concentrations of TCDD. However, there are several differences
between these two models. The PBPK model calculates the free and bound concentrations of
TCDD in the intracellular subcompartment of tissues. The total or receptor-bound

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concentrations in liver are unambiguous and more easily interpretable with the PBPK model than
with the CADM model. In addition, the PBPK model computes bound and total concentrations
as a function of the free concentration in the intracellular compartment of the tissue. By contrast,
the CADM model simulates the total concentration based on empirical consideration of hepatic
processes. Consequently, the amount of TCDD bound to AhR or CYP1A2 cannot be simulated
with the CADM model. The CADM model computes only the total TCDD concentration in
liver, and describes TCDD elimination through partitioning from circulating lipids across the
lumen of the large intestine into the feces, while the PBPK model accounts for this process
empirically within its hepatic elimination constant. Elimination of TCDD via skin, a minor
process, is not described by either model. Thus, dose-response modeling based on body burden
of TCDD in adult animals and humans can be conducted with either of the models, provided the
duration of the experiment is at least one month, due to limitations in the CADM model. As
shown in Figure 3-29, the predicted slope and body burden over a large dose range are quite
comparable (generally within a factor of two).

Results of simulations of serum lipid concentrations or liver concentrations vary for the
two models to a larger extent (up to a factor of 7), particularly for simulations of short duration.
These differences reflect two characteristics of the PBPK model: first, quasi-steady-state is not
assumed in the PBPK model; second, the serum lipid composition used in the model is not the
same as the adipose tissue lipids. The CADM model does not account for differential solubility
of TCDD in serum lipids and adipose tissue lipids, nor does it account for the diffusion-limited
uptake by adipose tissue. Therefore, the PBPK model would appear to be superior to the CADM
model with respect to the ability to simulate serum lipid and tissue concentrations during
exposures that do not lead to the onset of steady-state condition in the exposed organism.

The CADM model is simple and based on fewer parameters than the PBPK model.
Because the CADM model is constructed by fitting to data, its performance is likely to be
reliable for the range of exposure doses, species, and life stages from which the parameter
estimates were obtained. On the other hand, the PBPK model structure and parameters are
biologically-based and can be adopted for each species and life stage. Accordingly, the PBPK
model has been adopted to simulate the kinetics of TCDD in the fetus and in pregnant rats, as
well as in adult humans and rats (Emond et al., 2004, 197315; Emond et al., 2005, 197317;
Emond et al., 2006, 197316). The time step for calculation and dosing in the CADM model

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corresponds to 1 month. This requirement represents a constraint in terms of the use of this
model to simulate a variety of dosing protocols used in animal toxicity studies. This
requirement, however, is not a constraint with the PBPK models. So, simulating the body
burden and serum lipid concentrations for a longer duration of exposure, either model would
appear to be useful; but the PBPK model would be the tool of choice for simulating alternative
dose metrics of TCDD (e.g., blood concentration, total tissue concentration, bound
concentration) for various exposure scenarios (including single dose studies), routes and life
stages in the species of relevance, to TCDD dose-response assessment, particularly, mice, rats,
and humans.

Two minor modifications, to enhance the biological basis, were made to the PBPK model
of Emond et al. (2006, 1973161 before its use in the computation of dose metrics for TCDD.
The first one involved the recalculation of the volume of the rest of the body as follows:

WRE0 = (0.91 - (WLIB0 x WLI0 + WFB0 x WF0 + WLI0 + WF0)/(1 + WREB0))	(3-22)

where

WRE0 = weight of cellular component of rest of body compartment (as fraction of
body weight);

WLI0 = weight of cellular component of liver compartment (as fraction of body
weight);

WF0 = weight of cellular component of fat compartment (as fraction of body
weight);

WREB0 = weight of the tissue blood component of the rest of body compartment (as
fraction of body weight);

WLIB0 = weight of the tissue blood component of the liver compartment (as fraction
of body weight); and

WFB0 = weight of the tissue blood component of the fat compartment (as fraction of
body weight).

In the original code, the weight of the rest of body compartment was calculated as the
difference between 91% of body weight and the sum total of the fractional volumes of blood,
liver tissue (intracellular component), and adipose tissue (intracellular component). The blood
compartment in the PBPK model is not explicitly characterized with a volume; as a result, the

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total volume of the compartments is less than 91%. The recalculations shown above were used
to address this problem. Given the very low affinity of TCDD for blood and rest of the body,
reparameterizing the model resulted in less than a 1% change in output compared to the
published version of the PBPK model for chronic exposure scenarios (Emond et al., 2006,
197316V

The second minor modification related to the calculation of the rate of TCDD excreted
via urine. The original model code computed the rate of excretion by multiplying the urinary
clearance parameter with the concentration in the rest of the body compartment. Instead, the
code was modified to use the blood concentration in this equation. This resulted in the
re-estimation of the urinary clearance value in the rat and human models but it did not result in
any significant change in the fit and performance of the original model.

The revised parameter estimates of the rat, mouse, and human models are captured in
Table 3-8 with a footnote.

3.3.4.5. Recommended Dose Metrics for Key Studies

The selection of dose metrics for the dose-response modeling of key studies is largely the
result of (1) the relevance of a dose metric on the basis of current knowledge of TCDD's
mechanism of action for critical endpoints and (2) the feasibility and reliability of obtaining the
dose metric with available PK models. Secondarily, the goodness-of-fit of the dose-response
models (which reflects the relationship of the selected internal dose measures to the response)
can be used to inform selection of the most appropriate dose metric for use in deriving TCDD
toxicity values.

Body burden—even though this metric is based on mechanistic considerations—is a
somewhat distant measure of dose with respect to target tissue dose, and this metric represents
the "overall" average concentration of TCDD in the body. However, a benefit of body burden is
that this metric represents a dose measure for which the available PK models can provide highly
certain estimates. Thus, the overall confidence associated with the use of body burden in TCDD
assessment is categorized as medium.

The confidence in the ability of PK models to simulate blood concentration as a dose
metric is high, given that the models have been shown to consistently reproduce whole blood (or
serum lipid-normalized) TCDD concentration profiles in both humans and rats. Considering the

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facts that the PBPK models simulate whole blood rather than the serum lipid-normalized
concentrations of TCDD and that the study-specific values of serum lipid content are not known
with certainty, it is preferable to rely on TCDD blood concentrations as the dose metric. The
blood concentrations, if intended, can be normalized on the basis of appropriate total lipid levels.
However, based on mechanistic considerations, the confidence in their use would be somewhat
lower for hepatic effects. This conclusion reflects the concern regarding the inconsistent
relationship between the two variables with increasing dose levels and the fraction of
steady-state attained at the time of observation. For other systemic effects related to tissue
concentrations, the confidence in the use of TCDD serum or blood concentration is high,
particularly for chronic exposures, given the absence of data on organ-specific nonlinear
mechanisms. In general, the tissue concentration typically cannot be calculated as a reliable dose
metric with either the CADM or the Emond models. One exception is the use of the Emond
PBPK models to estimate levels in liver, a metric that is relevant based on MOA considerations.
However, it is noted that the hepatic TCDD level encompasses free and bound TCDD and it is a
highly complex entity for dose metric considerations. Finally, the AhR-bound concentration
may be evaluated for receptor-mediated effects. This dose metic can be obtained by PBPK
models, although uncertainties associated with lack of data for this dose metric renders it to be of
low confidence (see Table 3-10), The alternative dose metrics for dose-response modeling of
TCDD selected on the basis of MOA and PK modeling considerations are summarized in
Tables 3-11 and 3-12.

These measures of internal dose can be obtained as peak, average, integral (AUC), or
terminal values. For chronic exposures in rodents (ca. 2 years), the terminal and average values
would be fairly comparable under steady-state conditions. For less-than lifetime exposures,
however, the terminal and average values will differ, and therefore an overall average or
integrated value (AUC) would be more appropriate. Similarly, for developmental exposures,
these alternative dose metrics can be obtained with reference to the known or hypothesized
exposure window of susceptibility.

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3.3.5. Uncertainty in Dose Estimates

3.3.5.1. Sources of Uncertainty in Dose Metric Predictions

3.3.5.1.1.	Limitations of available PK data.

3.3.5.1.1.1.	Animal data.

The available animal data relate to blood, liver, and adipose tissue concentrations for
certain exposure doses and scenarios. Although these data are informative regarding the dose-
and time-dependency of TCDD kinetics for the range covered by the specific studies (see
Section 3.3.2), they do not provide the peak, average, terminal, or lipid-normalized values of
dose metrics associated with the key studies selected for this assessment. The limited available
animal PK data are useful, however, in the evaluation of the pharmacokinetic models (see
Section 3.3.4).

3.3.5.1.1.2.	Human data.

The human data on potential dose metrics are restricted to the serum lipid-adjusted
TCDD concentrations associated with mostly uncharacterized exposures (see Sections 3.3.2 and
3.3.3). While these data are useful in estimating half-lives in exposed human individuals, they
do not provide estimates of hepatic clearance or reflect target organ exposure. Some autopsy
data have been used to infer the partition coefficients; however, these data were collected
without quantification of the temporal nature of TCDD uptake (see Section 3.2). Despite the
limitations associated with the available human data, there has been some success in using these
data to infer the half-lives and elimination rates in humans using pharmacokinetic models
(Aylward et al., 2005, 197014; Carrier et al., 1995, 197618; Emond et al., 2006, 197316).

3.3.5.1.2.	Uncertainties associated with model specification.

Uncertainty associated with model specification should be viewed as a function of the
specific application, such as interspecies extrapolation, intraspecies variability, or high dose to
low dose extrapolation. Because the use of pharmacokinetic models in this assessment is limited
to interspecies extrapolation and high dose to low dose extrapolation, it is essential to evaluate
the confidence in predicted dose metrics for these specific purposes. For interspecies
extrapolation, the PBPK and CADM models calculate differences in dose metric between an
average adult animal and an average adult human. Both models have a biologically and

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mechanistically-relevant structure along with a set of parameters with reasonable biological
basis, and reproduce a variety of pharmacokinetic data on TCDD in both rodents and humans.
These models possess low uncertainty with respect to body burden, blood, and TCDD/serum
(lipid) concentration for the purpose of conducting rat to human extrapolation. However, for
other dose metrics, such as free, total, or bound hepatic concentrations, the uncertainty is higher
in the CADM model compared to the PBPK model due to model specification differences related
to the mechanisms of sequestration and induction in the liver (see Section 3.3.3).

For the purpose of high dose to low dose extrapolation in experimental animals,
confidence in both models is high with respect to a variety of dose metrics (see previous
discussion). The high confidence results from the use of the PBPK models to reproduce a
number of data sets covering a wide range of dose levels in rodents (rats, mice) including the
dose ranges of most of the key toxicological studies. Given that the TCDD levels during and at
the end of exposures were not measured in most of the key studies, use of the PBPK models is
preferred because these models account for dose-dependent elimination, induction, and
sequestration. Despite the empirical nature of the specification of these key processes in PBPK
models, they essentially reproduce the dose-dependent behavior in rodents, supporting their use
in deriving dose metrics for dose-response modeling of TCDD. Overall, the confidence in the
use of the alternative dose metrics (identified in Table 3-10) is greater than the confidence in the
use of administered dose for TCDD, for relating to the concentration within tissues to produce an
effect. The administered dose does not take into account interspecies differences in the volume
of distribution and clearance or the complex nonlinear processes determining the internal dose.

The PBPK model of Emond et al. (2006, 197316) could benefit from further refinement
and validation, including a more explicit consideration of nondose-dependent elimination
pathways. As indicated in Section 4, there is some uncertainty associated with the way the
elimination of TCDD is described in the existing human PBPK model. The current model
essentially treats all TCDD elimination as related to dose dependent metabolism in the liver. In
this regard, the classical and more recent PK data on TCDD may be useful in further improving
the confidence in their predictions. However, it is likely that there is nondose-dependent
elimination of TCDD via feces and, to a lesser extent skin; juxtaposition of available elimination
rate data with the PBPK model predictions suggests that the current PBPK model modestly
overestimates the dose dependency of overall TCDD elimination. (The central estimate of the

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slope of the relationship between the log of the TCDD elimination rate and the log of the TCDD
level is only about three-fourths of that expected using the unmodified PBPK model). Emond et
al. (2005, 197317) acknowledge that the model did not describe the elimination of TCDD from
the blood into the intestines, but it indirectly accounted for this phenomenon with the use of the
optimized elimination rate.

3.3.5.1.3. Impact of human interindividual variability.

The sources and extent of human variability suggested by the available data are presented
in Section 3.3.3, although there is some discussion of the impact of individual differences in
body fat content. The CADM model facilitates the simulation of body burden and serum lipid
concentrations on the basis of BMI and tissue weights of people, and the PBPK model simulates
alternative dose metrics in the fetus and in pregnant animals in addition to adult animals and
humans. However, neither of these models has been parameterized for simulation of population
kinetics and distribution of TCDD dose metrics. Therefore, at the present time, a quantitative
evaluation of the impact of human variability on the dose metrics of TCDD is not feasible, and
dose metric-based replacement of the default interindividual factor has not been attempted.

3.3.5.2. Qualitative Discussion of Uncertainty in Dose Metrics

The usefulness of the CADM and PBPK models for conducting dose-response modeling
(rodent bioassays), interspecies (rodent to human) and intraspecies (high-dose to low-dose)
extrapolations is determined by their reliability in predicting the desired dose metrics. The
confidence in the model predictions of dose metrics is dictated by the extent to which the model
has been verified with empirical data relevant to the dose metric, supplemented by sensitivity
and uncertainty analyses. Analysis of sensitivity or uncertainty has not been conducted with the
CADM model. For the PBPK model, Emond et al. (2006, 197316) published the initial results
from sensitivity analyses of acute exposure modeling (see Section 3.3.3). One of the objectives
of a sensitivity analysis that is of highest relevance to this assessment is the identification of the
most critical model parameters with respect to the model output (i.e., dose metric).

If the model simulations have only been compared to entities that do not correspond to
the moiety representing the dose metric, or if the comparisons have only been done for some but
not all relevant dose levels, routes, and species, then the reliability in the predictions of dose

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metric can be an issue. The extent to which model results are uncertain will depend largely upon
the extent to which the dose metric is measurable (e.g., serum concentrations of TCDD) or
inferred (e.g., AhR-bound TCDD concentration).

With respect to TCDD body burden, whole-liver and blood concentration predictions in
the rat model, which are well-calibrated with measured data, uncertainty is relatively low.
Therefore the need for sensitivity and uncertainty analysis is less critical and confidence in these
dose metrics is high. For those dose metrics that are not directly measurable or are less easily
verified by available calibration methods, such as free-liver and AhR-bound concentrations,
sensitivity and uncertainty analyses are crucial for assessing the reliability of model predictions
and confidence is low. For the human model, calibration is largely dependent on blood (LASC)
TCDD meaurements, which are much less extensive than for the rat model. Because the blood
measurements are reported as LASC, uncertainty and variability in serum:blood and fat: serum
ratios also come into play when evaluating the adequacy of the whole-blood TCDD metric.
Furthermore, the human data are mostly representative of much higher exposures than the
environmental exposures of interest to the EPA. Because of these additional uncertainties only
medium confidence can be held in the human model whole-blood TCDD concentration
predictions at higher exposures (observed effect range) and low-to-medium confidence at lower
exposures (background exposure range).

Sensitivity analysis for the Emond rat PBPK model predictions of liver TCDD
concentration indicated that hepatic CYP1A2 concentration is the most sensitive parameter
(Emond et al., 2006, 197316). For the Emond human PBPK model, the absorption parameters,
basal concentration of CYP1A2, and adipose tissue:blood partition coefficients were identified as
highly-sensitive parameters.

Confidence in the Emond rat and human PBPK models at high exposures is medium for
the purpose of rat-to-human extrapolation based on blood concentrations, given that the key
human model parameters are both sensitive and uncertain; confidence is low for lower
exposures. Conversely, confidence in the use of AhR-bound TCDD is low because of the large
uncertainty in the fraction of AhR-bound TCDD in the liver.

With regard to the predictability of body burden, the absorption and excretion parameters
were among the sensitive parameters in the rat. Several other parameters were also identified as
being sensitive in humans. Despite the sensitivity to these parameters and the uncertainty

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associated with individual parameter estimates, the overall confidence in the model predictions
of body burden appears to be high given the reproducibility of empirical data on tissue burdens
and blood concentrations of TCDD in various experiments by both models. Similar conclusions
can be drawn for blood concentration of TCDD predicted by the PBPK model, except that the
assigned value of blood (serum) lipid content will have additional impact on this dose metric to
the extent that the calibration data were in terms of LASC. Variability of total lipid levels and
variability of the contribution of phospholipids and neutral lipids to the total lipid pool across
species, lifestage and study groups is to be expected (Bernert et al., 2007, 594270; Poulin and
Theil, 2001. 5942691

Both conceptual (biological) relevance and prediction uncertainty are important in the
choice of dose metric for dose-response modeling and interspecies extrapolation. Conceptual
relevance has to do with how "close" the metric is to the observed effect, taking into account
both the target tissue and the MOA. In this context, a greater degree of confidence is held for
dose metrics that are more proximate to the event (i.e., specific effect). Prediction uncertainty
reflects the lack of confidence in the model predictions of dose metrics. Tables 3-13 and 3-14
provide a qualitative ranking of the importance and magnitude of each dose metric with respect
to these two sources of uncertainty. Conceptual relevance is low for the use of administered
dose in dose-response modeling because known (non-linear) physiological processes are ignored;
conversely, conceptual uncertainty is much lower for use of internal dose metrics more proximal
to the affected organs.

Table 3-13 presents a cross-walk of relevance, uncertainty and overall confidence
associated with the use of various dose metrics for dose-response modeling of TCDD. As shown
in Table 3-13, blood/serum levels have the highest overall confidence (medium) followed by
body burden (medium to low) for application in dose-response modeling. When using the mouse
PBPK model along with the human model (see Table 3-14), the contribution of the prediction
uncertainty to the overall uncertainty increases due to the limited comparison of the mouse
model simulations with empirical data.

3.3.6. Use of the Emond PBPK Models for Dose Extrapolation from Rodents to Humans

EPA has selected the Emond et al. (2004, 197315; 2005, 197317; 2006, 197316^ PBPK
models, as modified by EPA for this assessment, for establishing toxicokinetically-equivalent

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exposures in rodents and humans.18 The 2003 Reassessment (U.S. EPA, 2003, 537122)
presented a strong argument for using the relevant tissue concentration as the effective dose
metric. However, no models exist for estimation of all relevant tissue concentrations. Therefore,
EPA has decided to use the concentration of TCDD in blood as a surrogate for tissue
concentrations, assuming that tissue concentrations are proportional to blood concentrations.
Furthermore, because the RfD and cancer slope factor are necessarily expressed in terms of
average daily exposure, the blood concentrations are expressed as averages over the relevant
period of exposure for each endpoint. Specifically, blood concentrations in the model
simulations are averaged from the administration of the first dose to the administration of the last
dose plus one dosing interval (time) unit in order to capture the peaks and valleys for each
administered dose. That is, for daily dosing, 24 hours of TCDD elimination following the last
dose is included in the average (the modeling time interval is one hour); for a weekly dosing
protocol, a full week is included. In addition, because of the accumulation of TCDD in fat and
the large differences in elimination kinetics between rodent species and humans, exposure
duration plays a much larger role in TK extrapolation across species than for rapidly-eliminated
compounds. Because of these factors, EPA is using discrete exposure scenarios that relate
human and rodent exposure durations. The use of discrete exposure scenarios was introduced
previously in Section 3.4.4.2 describing first-order kinetic modeling and is further described in
the following paragraphs. This section concludes with a quantitative evaluation of the impact of
exposure duration on the rodent-to-human TK extrapolation from both the human and rodent
"ends" of the process.

Figure 3-30 shows the TCDD blood concentration-time profile for continuous exposure
at 0.01 ng/kg-day, as predicted by the Emond human PBPK model, and the target TCDD
concentrations corresponding to the three discrete exposure scenarios used by EPA in this
document. The target concentrations are those that would be identified in the animal bioassay
studies that correspond to a particular POD (no-observed-adverse-effect level, lowest-observed-
adverse-effect level, or benchmark dose lower confidence bound) established for that bioassay.
That is, the target concentrations represent the toxicokinetically-equivalent internal exposure to
be translated into an equivalent human intake (or FLED).

18The models will be referred to hereafter as the "Emond human PBPK model" and the "Emond rodent PBPK
model," with variations when referring to individual species or components (e.g., gestational).

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For the lifetime exposure scenario, the HED is "matched" to the lifetime average TCDD
blood concentration from a lifetime animal bioassay result by determining the continuous daily
intake that would result in that average blood concentration for humans over 70 years. A table
for converting lifetime-average blood concentrations and other internal dose metrics to human
intake is presented in Appendix C.4.

For the gestational exposure scenario, the effective TCDD blood concentration (usually
the peak) determined for the particular POD in a particular developmental study is matched to
the average TCDD blood concentration over the gestational portion of the human gestational
exposure scenario. The HED is determined as the continuous daily intake, starting from birth
that would result in that average blood concentration over the 9-month gestational period for a
pregnancy beginning at 45 years of age. The choice of 45 years as the beginning age of
pregnancy is health protective of the population in that the daily exposure achieving the target
blood concentration is smaller than for earlier pregnancies. A table for converting average
gestational blood concentrations and other internal dose metrics to human intake for the 45-year-
old pregnancy scenario is presented in Appendix C.4. Also, a comparison of the 45-year old
pregnancy scenario to one beginning at age 25 is presented in Table 3-15. Using the 25 year-old
pregnancy scenario increases the HED by 30 to 60% for typical animal bioassay PODs (3 to
30 ng/kg).

For a less-than-lifetime exposure, the average TCDD blood concentration over the
exposure period in the animal bioassay associated with the POD is matched to the average over
the 5-year period that includes the peak concentration (58 years for an intake of 0.01 ng/kg-day).
The HED is determined as the continuous daily intake that would result in the target
concentration over peak 5-year period. The use of the peak is analogous to the approach in the
2003 Reassessment, where the terminal steady-state body burden played the same role. The
5-year average over the peak is taken to smooth out sharp peaks and more closely approximate a
plateau. The choice of peak is health protective because humans of any age must be protected
for short-term exposures, and the daily intake achieving a given TCDD blood concentration is
smallest when matched to the peak exposure as opposed to an average over shorter durations.
Thus, target concentrations for any exposure duration of less-than-lifetime must be averaged
backwards from the end of the lifetime scenario, rather than from the beginning. The only
exception would be if the short-term endpoints evaluated in the animal bioassay were associated

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with a specific life stage (such as for the gestational scenario). Note that this scenario lumps all
exposures from 1 day to over 1 year in rodents into the same less-than-lifetime category.
Conceptually, duration-specific scenarios could be constructed by defining equivalent rodent and
human exposure durations. However, for the most part, defining duration equivalents across
species is a somewhat arbitrary exercise, not generally based on physiologic or toxicologic
processes, but relying primarily on fraction-of-lifetime conversions. EPA defines "lifetime"
exposure as 2 years and 70 years for rodents and humans, respectively. So, a half-lifetime
equivalence of 1 year in rodents and 35 years in humans is defined easily. Also, considering a
subchronic exposure to be 10-15% of lifetime, leads to an equivalence of 90 days in rodents and
7-10 years in humans. However, in the practical sense with respect to the Emond human PBPK
model predictions, the difference in the dose-to-target-concentration ratios are not significantly
different from the peak 5-year average scenario, differing by less than 5%. A table for
converting less-than-lifetime average blood concentrations and other internal dose metrics to
human intake is presented in Appendix C.4.

The net effect of using three different scenarios for estimating the HED from rodent
exposures is that, for the same target concentration, the ratio of administered dose (to the rodent)
to HED will be larger for short-term exposures than for chronic exposures. Figure 3-31 is
similar to Figure 3-30, except that it shows the relationship of daily intake to a fixed target
TCDD blood concentration level. Figure 3-31 shows that, for human intakes of approximately
0.01 ng/kg-day, the difference in the defined scenarios is 40% or less, with a lifetime-scenario
daily intake of 0.014 ng/kg-day required to reach the same target concentration for a shorter-term
exposure of 0.01 ng/kg-day. The corresponding daily intake for the gestational scenario is
0.011 ng/kg-day. Because of the nonlinearities in the Emond human PBPK model, the
magnitude of the difference between the lifetime and less-than-lifetime exposure scenarios
increases at lower intake levels, but not to a substantial degree.

The differential effect of short- and long-term exposures is much more accentuated at the
rodent end of the exposure kinetic modeling. Analogous to the processes described in the
previous section for first-order body burden (see Section 3.4.2.2), the TCDD blood concentration
for single exposures is essentially the immediate absorbed fraction of the administered dose,
which will be somewhat lower than the administered dose, while for chronic exposure, the

TCDD blood concentration will reflect the long-term accumulation from daily exposure, which

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will be very much larger than the administered dose (expressed as a daily intake). Table 3-16
shows the overall impact of TK modeling on the extrapolation of administered dose to HED,
comparing the Emond PBPK and first-order body burden models. For comparison purposes, the
administered dose is fixed at 1 ng/kg-day for all model runs. Large animal-to-human TK
extrapolation factors (TKEf) are evident for short-term mouse studies, decreasing in magnitude
with increasing exposure duration. The only exception is the slightly lower extrapolation factor
for the mouse 1-day exposure, which is the result of the relatively short TCDD half-life (10 days)
in mice and the use of the peak TCDD blood concentration as representative of single exposures,
compared to the average TCDD blood concentration over the exposure period used for multiple
exposures. The TKEfs are lower for rats because of the slower elimination of TCDD in rats
compared to mice. Also, because of the nonlinear kinetics inherent in the Emond PBPK model,
the span of the HED (13-fold for mice) across these exposure durations is greater than the span
of the lipid-adjusted serum concentration (LASC; 4-fold for mice). Because of the dose-
dependence of TCDD elimination in the Emond model, the TKEf becomes smaller with
decreasing intake. The result of this nonlinearity is that, although Table 3-16 shows much lower
TKefS for the Emond PBPK model than for the first-order body burden metric, at much lower
HED levels the two models give much closer predictions.

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1	Table 3-1. Partition coefficients, tissue volumes, and volume of distribution

2	for TCDD in humans

3

Tissue

Tissue/blood
partition
coefficient

Tissue volume
(liters, for a
60 kg person)

Effective volume of
distribution (Vd—liters of
blood equivalent)

Percent
total Vd

Blood

1

3

3

0.25

Fat

100

11.4

1.140

94.19

Liver

6

1.56

9

0.77

Rest of the body

1.5

38.64

58

4.79

Total

54.6*

1.210

100.00

4

5	*The total tissue volume presented here represents only 91% of body weight because some of the weight and

6	volume of the body is occupied by bone and other structures where TCDD uptake and accumulation do not occur to

7	a significant extent.

8

9	Source: Wang et al. (1997, 104657). Emond et al. (2005, 197317; 2006, 197316).

10

11

12	Table 3-2. Blood flows, permeability factors and resulting half lives (t1^) for

13	perfusion losses for humans as represented by the TCDD PBPK model of

14	Emond et al. (2005,19^32006,197316)

15

Tissue

Permeability (fraction of
compartment blood flow)

Rate constant for
compartmental
elimination (hour1)

ty2 (hrs)

Fat

0.12

0.0049

143

Liver

0.03

0.77

0.90

Rest of the body

0.35

3.84

0.18

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1	Table 3-3. Toxicokinetic conversion factors for calculating human equivalent

2	doses from rodent bioassays

3



Mouse

Rat (Wistar)

Rat (other)

Guinea pig

Half-life (days)3

10

20

25

40

Exposure
duration (days)

Conversion factor (CF)b BBA(tA):dA given in parentheses

1

3882 (0.77)

3815 (0.79)

3802 (0.79)

3783 (0.79)

7

1107 (2.71)

1020 (2.94)

1004 (2.99)

979 (3.07)

14

681 (4.41)

587 (5.11)

569 (5.27)

543 (5.53)

28

453 (6.62)

350 (8.56)

331 (9.06)

303 (9.90)

90

307 (9.76)

186(16.1)

163 (18.4)

130(23.0)

180

282(10.6)

154 (19.5)

129(23.2)

93 (32.1)

365

270(11.1)

141 (21.3)

115(26.0)

77 (38.9)

730

226(11.3)

115 (22.2)

93 (27.4)

60 (42.5)

4

5	aHalf-life for humans = 2,593 days (7.1 years).

6	hdH = dJCF; BBH(tH):dH = 2,185 (1-180 days), 2,202 (365 days), 2,555 (730 days).

This document is a draft for review purposes only and does not constitute Agency policy.

3.57 DRAFT—DO NOT CITE OR QUOTE


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Table 3-4. Equations used in the concentration and age-dependent model
(CADM; Aylward et al., 2005,197014)"

Parameter

Equation

Hepatic
Concentration

(ng/kg)

O (f — f

z^body f ^ max J mm/ body
hepatic jjr min 1 jr

"1 ^ + ^body

Fat

Concentration

(ng/kg)

0 (f - f )*C

~-» z^body & /i / -f 1 maX min/ body

adrpose- ^ I 0 min K + C^

Hepatic
Elimination

Exr _ hepatic = t, . «<1- (/min + (/- C"> ))

^ + ^body

Excretion via
gut of
Unchanged
TCDD

(Exsorption)

Exr_gut = ka*Qa

Change of
TCDD due to
bodyweight
change

ChangeTCDD BW = QlJ

5 - v"> BW(t)

Amount in



body as a
function of

Qbody + dt) ~ Qb0dy (0 = Exr hepatic + Exr gut + ChangeTCDD BW

time



Adipose tissue
growth

1.2 * BMI + (0.23 * Age) -10.8 * sex
100

Change of
hepatic
elimination
constant with
age

K = Ko ~ Klope * Ase

Tor abbreviations and parameter descriptions, see Table 3-5.

This document is a draft for review purposes only and does not constitute Agency policy.

3-58 DRAFT—DO NOT CITE OR QUOTE


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1	Table 3-5. Parameters of the Concentration and Age-Dependent Model

2	(CADM; Aylward et al., 2005,197014)

3

Parameter

Value

Units

Comments/sources

f a

J-hmin

0.01

unitless

Minimum body burden fraction in liver

f a

^-hrnax

0.7

unitless

Maximum body burden fraction in liver

Ka

100

ng/kg

Body burden at half-maximum of fraction
liver

ke

Calculated

per year

ke = ke0 - ke siope*(age) with enforced
minimum of ke mm

keO

0.85

per year

CADM-mean hepatic elimination base rate at
age 0

ke slope

0.011

per year

Change in ke per year of age

V

lxc mm

0.2

per year

Minimum hepatic elimination rate

wa (adipose weight fraction)

Calculated

unitless

wa = [(1.2*BMI)+0.23*Age-10.8*sex]/100

wh (liver body weight fraction)

0.03

unitless

Assumed constant

ka (adipose clearance factor)

0.0025

per month

Passive elimination rate from intestinal tract

Monthly dose

0.15507069

ng

per month

Estimated absorption fraction

0.97

unitless

From Moser and McLaghlan (2001. 198045)

Body weight

70

kg

Standard male weight

Sex

1

unitless

1 = male; 0 = female

Time of administration

840

months



Initial Cbody

0.2

ng/kg

Estimated background young adults UMDES
sampling

Absorbed monthly dose 1

0.150418569

ng

per month

4

5	aThe values of fhmin, fhmax, and K were obtained by best fit of the model simulations to the experimental data with

6	the method of least squares (Aylward et al.. 2005, 197114: Carrier et al.. 1995, 1976181.

This document is a draft for review purposes only and does not constitute Agency policy.

3.59 DRAFT—DO NOT CITE OR QUOTE


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1	Table 3-6. Confidence in the CADMa model simulations of TCDD dose

2	metrics

3

Dose metric

Level of confidence

Administered dose

N/A

Absorbed dose

H

Body burden

H

Serum lipid concentration

M

Total tissue (liver) concentration

L

Receptor occupancy (bound concentration)

N/A

4

5	'Concentration and age-dependent model (Avhvard et al.. 2005, 1970141.

6	H = high, M = medium, L = low, NA = not applicable.

This document is a draft for review purposes only and does not constitute Agency policy.

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1	Table 3-7. Equations used in the TCDD PBPK model of Emond et al. (2006,

2	197316)

3

Aspect

Equation

Body weight
growth with age

uur i \ uur ™ f 0.41 x time )
BW, (g) = BW TOx 	

^1402.5 + time

Cardiac output

( BW Y75

Qc(mL / hr) = QCCAR x 60

A factor of 60 corresponds to the conversion of minutes to hours, and 1,000 is conversion of BW
from grams to kilograms.

Blood

compartment

\{Qf x Cjb) + (Ore x Creb) + (OH xClib) + lymph] (CbxCLURI)

\~sU\tIHWJl / HlL-i 1 —

Qc Qc

Tissue compartment (fat, rest of the body)

Tissue blood
subcompartment

dAtb (nmollmL) = Qt(Ca Ctb) PAt[ctb
Ath

Ctbinmol / mL) =	

Wtb

Tissue cellular
matrices

~~~(nmol/mL) = PAt^Ctb -
At

CtinmollmV) - —

Wt

Liver tissue compartment

Tissue blood
subcompartment

dAlib ^nm()j J mj^ _ Qij((tt f LIBMAXx Clifree ) f CYPlAlx Clifree \\

Clifreeinmol / mL) = Cli - Clifree x PLI + 			 + 			

^ KDLI +Clifree J [KDLI1A2 + Clifree J

Concentration
bound to AhR
in hepatic tissue

, , T, LIBMAXx Clifree

AhRbound (jimol / TTlL) —

KDLI + Clifree

All other induction processes and equations have been described and presented by Wang et al. (1997,

104657s).

This document is a draft for review purposes only and does not constitute Agency policy.

3_61 DRAFT—DO NOT CITE OR QUOTE


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1

Table 3-7. Equations used in the TCDD PBPK model of Emond et al. (2006,
197316) (continued)

Aspect

Equation

Gastrointestinal absorption and distribution of TCDD to the portal lymphatic circulation

Amount of
TCDD
remaining in
lumen cavity

dLu™en (nmoi / = [(KST + KABS) x lumen J + intake

Lumen in the amount of TCDD remaining in the GI tract (nmol); intake is the rate of intake of
TCDD during a subchronic exposure (nmol/hr).

Amount of
TCDD

eliminated in the
feces

dFeces ^nmQ^ x iumen
dt

Absorption rate
of TCDD to the
blood via the
lymphatic
circulation

(jimoi / _ KABS x lumen x 0.7

Absorption rate
of TCDD by the
liver via portal
circulation

dPortal . , ., . „ , ,

	(nmol / nr) = KABS x lumen x 0.3

dt

2

3	Note: Key parameters and abbreviations are defined in Table 3-10.

This document is a draft for review purposes only and does not constitute Agency policy.

3-62 DRAFT—DO NOT CITE OR QUOTE


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Table 3-8. Parameters of the PBPK model for TCDD

S?
>!

§•
rs
st

3

>!
Si

G\
U>

o
<5"

St

o
>!

>!

o

Si

§•
>!

o



Parameter
Description

Symbol

Parameter values

Human
nongestational3

Human
gestational"

Mouse
nongestational

Mouse
gestational

Rat

nongestational

Rat
gestational

Body weight (g)

BW

Calculated

Calculated

23-28b

23-28

125-250b

85-190b

Cardiac output (mL/hour/kg)

QCCAR

15.36cd

Calculated

275°

275°

311.4e

311,4e

Tissue (intracellular) volumes (fraction of BW)

Liver

WLIO

Calculated

Calculated

0.0549f

0.0549f

0.036e

0.036e

Fat

WFO

Calculated

Calculated

0.069e

Calculated

0.069e

Calculated

Tissue blood volumes

Liver (fraction of WLIO)

WLIBO

0.266e

0.266e

0.266e

0.266e

0.266e

0.266e

Fat (fraction of WFO)

WFBO

0.05e

0.05e

0.05e

0.05 e

0.05e

0.05e

Rest of body (fraction of WREO)

WREBO

0.03e

0.03e

0.03e

0.03 e

0.03e

0.03e

Placenta tissue fraction of tissue blood
weight (unitless)

WPLABO

N/A

0.5s

N/A

0.5e

N/A

0.5e

Tissue blood flow (fraction of cardiac output)

Liver

QLIF

0.26°

0.26°

0.16 lf

0.161f

0.183e

0.183e

Fat

QFF

0.05°

0.05°

0.07h

0.07h

0.069e

0.069e

Placenta

QPLAF

N/A

Calculated

N/A

Calculated

N/A

Calculated

Tissue permeability (fraction of tissue blood flow)

Liver

PALIF

0.35e

0.35e

0.35e

0.35e

0.35e

0.35e

Fat

PAFF

0.121

0.121

0.121

0.121

0.091e

0.091e

Placenta diffusional permeability fraction
(unitless)

PAPLAF

N/A

0.3s

N/A

0.03s

N/A

0.3s

Rest of body

PAREF

0.03e

0.03e

0.03e

0.03e

0.0298e

0.0298e


-------
Table 3-8. Parameters of the PBPK model for TCDD (continued)

S?
>!

§•
rs
st

3

>!
Si

G\
4^

o

st

o
>!

>!

o

Si

§•
>!

o



Parameter
Description

Symbol

Parameter values

Human
nongestational3

Human
gestational"

Mouse
nongestational

Mouse
gestational

Rat

nongestational

Rat
gestational

Partition coefficient

Liver

PLI

6e

6e

6e

6e

6e

6e

Fetus/blood partition coefficient (unitless)

PFETUS

N/A

4J

N/A

4J

N/A

4J

Placenta/blood partition coefficient (unitless)

PPLA

N/A

1.5J

N/A

3s

N/A

1.5J

Fat

PF

o
o

o
o

4001

4001

o
o

o
o

Rest of body

PRE

1.5e

1.5e

3k

3k

1.5e

1.5e

Metabolism constants

Urinary clearance elimination (mL/hour)

CLURI

4.17E-081

4.17E-081

0.091

0.091

0.01J

0.01J

Clearance - transfer from mother to fetus
(mL/hour)

CLPLAFET

N/A

16e

N/A

0.171

N/A

0.171

Liver (biliary elimination and metabolism;
hour"1)

KBILELI

Inducible

Inducible

Inducible

Inducible

Inducible

Inducible

Interspecies constant (hour1)

Kelv

0.00111

0.00111

0.41

0.41

0.15e

0.15e

AhR

Affinity constant in liver (nmol/mL)

KDLI

o.r

o.r

o.ooor

o.ooor

o.ooor

o.ooor

Binding capacity in liver (nmol/mL)

LIBMAX

0.35e

0.35e

0.00035e

0.00035e

0.00035e

0.00035e

Placenta binding capacity (nmol/mL)

PLABMAX

N/A

0.2J

N/A

0.0002J

N/A

0.0002J

Affinity constant protein (AhR) in placenta
(nmol/mL)

KDPLA

N/A

0.1J

N/A

0.0001J

N/A

0.0001J


-------
Table 3-8. Parameters of the PBPK model for TCDD (continued)

Parameter
Description

Symbol

Parameter values

Human
nongestational3

Human
gestational"

Mouse
nongestational

Mouse
gestational

Rat

nongestational

Rat
gestational

CYP1A2 induction parameters

Dissociation constant CYP1A2 (nmol/mL)

KDLI2

401

401

0.02'

0.02'

0.04J

0.04J

Degradation process CYP1A2 (nmol/mL)

CYP1A210UTZ

l,600e

l,600e

1.6e

1.6e

1.6e

1.6e

Dissociation constant during induction
(nmol/mL)

CYP1A21EC50

130e

130e

0.13s

0.13s

0.13s

0.13s

Basal concentration of CYP1A2 (nmol/mL)

CYP1A21A2

l,600e

l,600e

1.5k

1.5k

1.6e

1.6e

First-order rate of degradation (hour')

CYP1A21KOUT

o.r

o.r

o.r

o.r

o.r

o.r

Time delay before induction process (hour)

CYP1A21TAU

0.25e

0.25e

1.5k

1.5k

0.25e

0.25e

Maximal induction of CYP1A2 (unitless)

CYP1A21EMAX

9,300'

9,300'

600e

600e

600e

600e

Other constants

Oral absorption constant (hour1)

KABS

0.06'

0.06'

0.48'

0.48'

0.48e

0.48e

Gastric nonabsorption constant (hour1)

KST

0.01m

0.01m

0.30'

0.30'

0.36e

0.36e

aUnits for human nongestational parameters are L rather than mL and kg rather than g where applicable.

' Body weight varies by study (Emond et al.. 2004, 1973151.

°Krishnan and Andersen (2007).

dUnits are L/kg/hr.

eWang et al. (1997, 1046571.

'ILSI (1994, 0464361.

8Fixed.

''Leung et al. (1990, 1928331.

'Optimized.

'Emond et al. (2004, 1973151.

1 Wang et al. (2000, 1987381.

'Lawrence and Gobas (1997, 1990721.

"'Calculated to estimate 87% bioavailability of TCDD in humans (Poiger and Schlatter. 1986, 1973361.


-------
1	Table 3-9. Regression analysis results for the relationship between logio

2	serum TCDD at the midpoint of observations and the logio of the rate

3	constant for decline of TCDD levels using Ranch Hand data

4

Item

Aspect

Value

Summary of fit

RSquare

0.894



RsquareAdj

0.871



Root mean square error

0.044



Mean responses

0.130



Observations (or sum weights)

11

Parameter estimates

Intercept





Estimate

-0.054



Standard deviation

0.026



t ratio

-2.07



Prob>t

0.0679



Log (TCDDpg/g)





Estimate

0.092



Standard error

0.011



t ratio

8.28



Prob>t

<0.0001

5

6

7	Table 3-10. Confidence in the PBPK model simulations of TCDD dose

8	metrics

9

Dose metric

Human model

Rat model

Mouse model

Administered dose

N/A

N/A

N/A

Absorbed dose

H

H

M

Body burden

H

H

M

Serum (blood)concentration

H

H

M

Total liver concentration

M/L

H

M

Receptor occupancy (bound concentration)

L

L

L

10

11	H = high, M = medium, L = low.

This document is a draft for review purposes only and does not constitute Agency policy.

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1	Table 3-11. Overall confidence associated with alternative dose metrics for

2	cancer and noncancer dose-response modeling for TCDD using rat PBPK

3	model

4

End point

Body
burden

Blood or serum
concentration

Liver
concentration

Bound
concentration in
liver

Liver effects

M



H

M/L

Nonhepatic effects

M

H



M/L

5

6	H = high, M = medium, L = low.

7

8

9	Table 3-12. Overall confidence associated with alternative dose metrics for

10	cancer and noncancer dose-response modeling for TCDD using mouse PBPK

11	model

12

End point

Body
burden

Blood or serum
concentration

Liver
concentration

Bound
concentration in
liver

Liver effects

M



M

L

Nonhepatic effects

M

M



L

13

14	H = high, M = medium, L = low.

15

16

17	Table 3-13. Contributors to the overall confidence in the selection and use of

18	dose metrics in the dose-response modeling of TCDD based on rat and

19	human PBPK models

20

Dose metric

Conceptual
Relevance

Prediction
uncertainty

Overall
Confidence

Administered dose

L

NA

L

Body burden

M

M

M-L

Blood concentration

M

L

M

Liver concentration

L

M

L

Receptor (AhR)
occupancy

H

H

L

21

22	H = high, M = medium, L = low, NA = not applicable, ? = if relevant to MOA of response.

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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1	Table 3-14. Contributors to the overall uncertainty in the selection and use

2	of dose metrics in the dose-response modeling of TCDD based on mouse and

3	human PBPK models

4

Dose metric

Conceptual uncertainty

Prediction uncertainty

Administered dose

H

NA

Absorbed dose

H

L

Body burden

M

M

Blood or serum concentration

M

M

Tissue concentration

L

MH

Receptor occupancy

L(?)

H

5

6	H = high, M = medium, L = low, NA = not applicable, ? = if relevant to MOA of response.

7

8

9	Table 3-15. Comparison of human equivalent doses from the Emond human

10	PBPK model for the 45-year-old and 25-year-old gestational exposure

11	scenarios

12

Animal
bioassay POD
(ng/kg-day)

Species

TCDD
blood
concentration21

IIII)

45 year-old

111 1)

25 year-old

25-yr:45-yr
ratio

3

Mouse

8.800E-02

6.79E-04

1.03E-03

1.5

Rat

1.815E-01

1.87E-03

2.98E-03

1.6

30

Mouse

7.115E-01

1.51E-02

2.07E-02

1.4

Rat

1.367E+00

4.22E-02

5.41E-02

1.3

13

14	""Determined from the Emond rodent PBPK models assuming a single exposure on GD13.

This document is a draft for review purposes only and does not constitute Agency policy.

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1	Table 3-16. Impact of toxicokinetic modeling on the extrapolation of

2	administered dose to HED, comparing the Emond PBPK and first-order

3	body burden models

4

Exposure
duration (days)

lst-order BB

Emond PBPK

HED
(ng/kg-day)

TKef

LASC
(ng/kg)

HED
(ng/kg-day)

TKef

Mouse

1

2.57E-4

3,882

75.5

9.49E-4

1,054

14

1.47E-3

681

64.4

8.17E-4

1,224

90

3.25E-3

307

173

3.83E-3

261

365

3.70E-3

270

248

6.66E-3

150

730

4.43E-3

226

263

1.08E-2

93

Rat

1

2.63E-4

3,802

110

1.87E-3

535

14

1.76E-3

569

208

5.22E-3

192

90

6.13E-3

163

599

2.81E-2

36

365

8.68E-3

115

811

4.52E-2

22

730

1.07E-2

93

853

6.47E-2

15

5

This document is a draft for review purposes only and does not constitute Agency policy.

3-69 DRAFT—DO NOT CITE OR QUOTE


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1

2

«

c
•-

>
J

1Z)
=

•—

¦+J
=

u
B
O

u

D	7 Day Liver/Fat

•	14 Day Liver/Fat

A	21 Day Liver/Fat

I	35 Day Liver/Fat

O

C6

0

~

Dose jug/Kg

3

4	Figure 3-1. Liver/fat concentration ratios in relation to TCDD dose at

5	various times after oral administration of TCDD to mice.

6

7	Source: Dilberto et al. (1995, 197309).

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INITIAL SERUM LIPID TCDD LEVEL
(ppt)

1

2	Figure 3-2. First-order elimination rate fits to 36 sets of serial TCDD

3	sampling data from Seveso patients as function of initial serum lipid TCDD.

4

5	Source: Aylward et al. (2005, 197014).

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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% Body Fat

Figure 3-3. Observed relationship of fecal 2,3,7,8-TCDD clearance and
estimated percent body fat.

Source: Rohde et al. (1999, 548764).

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1

5C

u

C5

4>

C5

a

S3

C5

S3

W

—
—

u

H

11.0

10.0

y = - 1.89 + 0.314x RA2 = 0.998

Seveso Females

% Body Fat

2

3

4

5

Figure 3-4. Unweighted empirical relationship between percent body fat
estimated from body mass index and TCDD elimination half-life—combined
Ranch Hand and Seveso observation.

This document is a draft for review purposes only and does not constitute Agency policy.

3-73 DRAFT—DO NOT CITE OR QUOTE


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01
u
c
ra

>

Of

k_

bo

c

"m

ro
m

u
c

Functional biomorkors

Receptor occupancy
Total tissue concentration
Blood or serum concontration

Body burden
Absorbed dose
Intake

1

2	Figure 3-5. Relevance of candidate dose metrics for dose-response modeling,

3	based on mode of action and target organ toxicity of TCDD.

4

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Experimental Applied Dose

Body Burden,iai(/) = BB(0)e k" +

* , d(\-e~u)fa

Body BurdenRat (t)

A

Human

drr = d

h/2A (1

k jt a

)

H ~

tmh (1 - )

Estimated +.
Exposure

v

Body Burden,. (L)

Figure 3-6. Process of estimating a human-equivalent TCDD lifetime average daily oral exposure (dH) from an
experimental animal average daily oral exposure (d\) based on the body-burden dose metric. The arrows
represent mathematical conversions based on toxicokinetic modeling. BBa (TWA animal body burden) and BBh (TWA
human body burden) are assumed to be toxicokinetically equivalent. See text for further explanation.


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1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

Exposure days

Figure 3-7. Human body burden time profiles for achieving a target body
burden for different exposure duration scenarios. BB:d is BBH(tH):dH in

Figure 3-6. The curve depicted using the solid line illustrates the increase in the
human body burden over time for a hypothetical human administered a daily
TCDD dose where the time-weighted average human body burden estimate over
the lifetime is equal to the target body burden attained in a rodent bioassay. When
compared to shorter durations (dashed lines), a higher average daily TCDD dose
is required to yield a time-weighted average human body burden over a lifetime
that is equal to the target body burden attained in a rodent bioassay. The half-
chronic exposure scenario (depicted using a dashed line) is equivalent to a 1-year
exposure in rodents. When compared to a chronic BBH, a lower value of dH is
needed to attain the target body burden in a rodent bioassay when the time-
weighted average is over the last 35 years of life; the dose to plateau ratio is also
smaller (i.e., dH.c < dH.sc to attain the target body burden in a rodent bioassay).
The shorter exposure scenario is equivalent to most other shorter rodent exposure
durations, from 1 day to subchronic, which are indistinguishable with respect to
the BB:d ratio (subchronic shown).

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DISTRIBUTION	ELIMINATION

Figure 3-8. Schematic of the CADM structure.

Source: Aylward et al. (2005, 197014).

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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-IT"

_L

10

100

cb

1000

1	Figure 3-9. Comparison of observed and simulated fractions of the body

2	burden contained in the liver and adipose tissues in rats. fraction contained

3	in liver (observation) (~X./h-sim, fraction contained in liver (simulation) (—);/at,

4	fraction contained in the adipose tissue (observation) (0);/at-sim, fraction contained

5	in the adipose tissue (simulation) (—); and Cb. body concentration in ng TCDD/kg

6	body wt.

7

8	Source: Carrier et al. (1995, 197618); data from Abraham et al. (1988, 199510)

9	measured 7 days after dosing.

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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Blood systemic circulation

1

2

3	Figure 3-10. Conceptual representation of PBPK model for rat exposed to

4	TCDD.

5

6	Source: Emond et al. (2006, 197316).

This document is a draft for review purposes only and does not constitute Agency policy.

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Urinary
excretion

Elimination Gl tract

Figure 3-11. Conceptual representation of PBPK model for rat
developmental exposure to TCDD.

Source: Emond et al. (2004, 1973151

This document is a draft for review purposes only and does not constitute Agency policy.

3-80 DRAFT—DO NOT CITE OR QUOTE


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Figure 3-12. TCDD distribution in the liver tissue.

Source: Wang et al. (1997, 104657).

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

3-81 DRAFT—DO NOT CITE OR QUOTE


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1

2

3

4

5

6

7

8

9

0

1

§
s

2 2 ¦

10	15

Time (e {d.iysi

25

Figure 3-13. Growth rates for physiological changes occurring during
gestation, (a) Placental growth during gestation (calculated for n = 10 placenta).
Experimental data from Sikov (1970, 594274). (b) Blood flow rate in Placental
compartment during gestation. Experimental data from Buelke-Sam et al. (1982,
020478; 1982, 020477). (c) Fat fraction of body weight during gestation.
Experimental data came from Fisher et al. (1989, 065288). and (d) Fetal growth
during gestation. Experimental data obtained from Sikov (1970, 594274).

This document is a draft for review purposes only and does not constitute Agency policy.

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00

3?
>!

§•
C>

ss



>}
&

^3

ss

*3

o

>3
>J

o

53
£

§•
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s
. o

ri

o
s

^n



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o

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o^

H S.

w .s-
o *

o
c
o

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W

Fixed elimination rate
EXPBL

o
o

01
09
©

©
o

i_

©
Q_

0.1-

0.0H

0.001 --

Variable elimination rate
EXPBL

0.0001

0.0001

400 600
Time (hr)

1,000

o
o

©
o

t—

©
Q_

400 600

Time (hr)

1,000

0.0001

400 600

Time (hr)

1,000

Figure 3-14. Comparisons of model predictions to experimental data using a fixed elimination rate model with
hepatic sequestration (A) and an inducible elimination rate model with (B) and without (C) hepatic
sequestration. EXBL, experimental blood levels. Model predictions were compared with the data of Santostefano et
al. (1998, 2000011 where female rats were exposed to a single oral dose of 10 [j,g of TCDD/kg BW. Error bars are ±
SD.

Source: Edmond et al. (2006, 197316).


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1

2

3

4

5

6

7

100.00=,

10.00

1,750 ng TCDD/kg BW
500 ng TCDD/kg BW	~

150ngTCDD/I^BW	*

0.10 =

0.01

JJ

i	i	i	i	i

10 15 20 25 30

Time (week)

35

Figure 3-15. PBPK model simulation of hepatic TCDD concentration (ppb)
during chronic exposure to TCDD at 50,150, 500,1,750 ng TCDD/BW using
the inducible elimination rate model compared with the experimental data
measured at the end of exposure.

Source: Emond et al. (2006, 197316).

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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1

Q

-CBPPTRH

V36564

D

20

Time (year)

Time (year)

m

20

Time (year)

1000000
100000

; 10000

1000
100
10

1

m

-CBPPTRH
V30991

20

Time (year)

30

40

2	Figure 3-16. Model predictions of TCDD blood concentration in 10 veterans

3	(A-J) from Ranch Hand Cohort.

4	Source: Emond et al. (2005, 197317).

This document is a draft for review purposes only and does not constitute Agency policy.

3-85 DRAFT—DO NOT CITE OR QUOTE


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10,000

2

3

1,000

200	300

Blood model predictions (pt #1) v |

Patient 1 Vienna women

1,000

1,100

1,200

1,000,000

100,000

1,000 -J—i—i—i—i—i—i—i—(—i—i—i—i—i—i—i—j—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—t—i—i—i—i—i—i—i—i—i—i—i—i—i—i—»
0	100	200	300	400	500	600	700	800	900 1,000 1,100 1,200

10	Blood model predictions (pt #2) [yj	Patient 2 Vienna women	'

4

5

6	Figure 3-17. Time course of TCDD in blood (pg/g lipid adjusted) for two

7	highly exposed Austrian women (patients 1 and 2). Symbols represent

8	measured concentrations, and lines represent model predictions. These data were

9	used as part of the model evaluation (Geusau et al., 2002, 594259).

10

11	Source: Emond et al. (2005, 197317).

This document is a draft for review purposes only and does not constitute Agency policy.

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1

2

Pgg P

12

Years After Exposure

3

4	Figure 3-18. Observed vs. Emond et al. (2005,197317) model simulated

5	serum TCDD concentrations (pg/g lipid) over time (In = natural log) in two

6	Austrian women. Data from Geusau et al. (2002, 594259).

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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Log(TCDD pg/g at Midpoint Obs)

1

2	Figure 3-19. Comparison of the dose dependency of TCDD elimination in the

3	Emond model vs. observations of nine Ranch Hand veterans and two highly

4	exposed Austrian patients. Circles are observed data.

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

3-88 DRAFT—DO NOT CITE OR QUOTE


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T;

<5

0_

WLIO
WPO
PF
Ksr
KABS

C.YP1A2JGUTZ
CYP1A2JA2

~

~~r

s

~~r
-t

T

T

T

-i -2 0 2
Percent of change

n
10

X
-

»
0_

WLIO
WFO
PF
KST
KABS
KD LI
LIB MAX
KDLI2
CYP1A2_1 OUTZ
CYP1A2JEMAX
CYP1A2_1EC50
CYP1A2_1A2

a

-20

-15

"I	1		1	1	1	1

-10 -5	0	5	10 15 20

Percent of ch-Mige

3

4

5

6

7

Figure 3-20. Sensitivity analysis was performed on the inducible elimination
rate. The analysis was performed at 0.001 |ig/kg (A) and at 10 |ig/kg (B). The
blue and white bars are results from -10% and +10% changes, respectively.

Source: Emond et al. (2006, 197316).

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

3-89 DRAFT—DO NOT CITE OR QUOTE


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S — CB (pg/g)
~ HI Cb measured

100
10

1 	.	;	;	i	;			

0 10	20 30 40 SO	60 70 80 90 100 110 120

v*	Cf (pg/g) Simulated

v Cf (pg/g) measured

0	10 20 30 40 50 60 70 80 90 100 110 120

Figure 3-21. Experimental data (symbols) and model simulations (solid lines)
of (A) blood, (B) liver and (C) adipose tissue concentrations of TCDD after
oral exposure to 150 ng/kg-day, 5 days/week for 17 weeks in mice. Y-axis
represents concentration in pg/g and X-axis represents time in days.

Source: Experimental data were obtained form Diliberto et al. (2001, 197238).















































































0	10	20	30	40	50	60	70	80	90 100 110

This document is a draft for review purposes only and does not constitute Agency policy.

3-90 DRAFT—DO NOT CITE OR QUOTE


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Q.

Q.

C

o

c

d)

o
c
o
o

d)
>

10000000
1000000
100000
10000
1000
100
10

~	Measured

~	Simulated

¦

dt

0.001 0.01

0.1	1	10

Dose (ug/kg)

100

300

1

2	Figure 3-22Comparison of PBPK model simulations with experimental data

3	on liver concentrations in mice administered a single oral dose of 0.001-300

4	jig TCDD/kg. The simulations and experimental data were obtained 24 hour

5	post-exposure.

6

7	Source: Data obtained from Boverhoff et al. (2005, 594260).

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

3-91 DRAFT—DO NOT CITE OR QUOTE


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.

	cb sim ¦ cb measured

	cli sim ¦ cli measured

	cfsim ¦ cf measured





0 -i	1	1	1	1

0.1	1.0	10.0	100.0	1000.0

Dose (ng/kg)

1

2	Figure 3-23. Comparison of model simulations (solid lines) with

3	experimental data (symbols) on the effect of dose on blood (cb), liver (cli) and

4	fat (cf) concentrations following repetitive exposure to 0.1-450 ng TCDD/kg,

5	5 days/week for 13 weeks in mice.

6

7	Source: Data obtained from Diliberto et al. (2001, 197238).

This document is a draft for re\>iew purposes only and does not constitute Agency policy.

3-92 DRAFT—DO NOT CITE OR QUOTE


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y — C6 (pg/g) |
¦y WM Cb measured I

10	20	30	40	50	60	70	30	90	100 110 120

@	Cli (pgg) Sim I

•s Cli (pgg) measured I

0	10 20 30 40 50 60 70 80 90 100 110 120

y	Cf (pg/g) Simulated I

¦j Cf (pg/g) measured I

0 10 20 30 40 50 60 70 80 90 100 110 120

Figure 3-24. Comparison of experimental data (symbols) and model
predictions (solid lines) of (A) blood, (B) liver and (C) adipose tissue
concentrations of TCDD after oral exposure to 1.5 ng/kg-day, 5 days/week
for 17 weeks in mice. Y-axis represents concentration in pg/g and X-axis
represents time in days.

Source: Experimental data were obtained form Diliberto et al. (2001, 197238).

This document is a draft for review purposes only and does not constitute Agency policy.

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A

- Cb (ng/kg)
| measured

B



- Cli (pg/g) I
| measured I

c

- cf (pg/g) |
I measured I

0	200

D

- Feces elimination % dose I
| measured	I

0 200 400

1,200 1,400 1,600 1,800 2,000 2,200

> 	Urinary (% dose) 1

t measured

Figure 3-25. Comparison of experimental data (symbols) and model
predictions (solid lines) of (A) blood concentration, (B) liver concentration,
(C) adipose tissue concentration (D) feces excretion (% dose) and (E) urinary
elimination (% dose) of TCDD after oral exposure to 1.5 ng/kg-day,

5 days/week for 13 weeks in mice. Y-axis represents concentration in pg/g and
X-axis represents time in days.

Source: Experimental data were obtained form Diliberto et al, (2001, 197238).

This document is a draft for review purposes only and does not constitute Agency policy.

3-94 DRAFT—DO NOT CITE OR QUOTE


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A

B

C







¦/ — Cb (pg/g) I
v B| measured |

0	200 400 600 800 1,000 1,200 1,400 1,600 1,800 2,000 2,200

10,000
1,000

v - Cli (pg/g) I
v B measured |

0	200 400 600 800 1,000 1,200 1,400 1,600 1,800 2,000 2,200

f — Cf (pg/g) I
' H measured I

0	200 400 600 800 1,000 1,200 1,400 1,600 1,800 2,000 2,200

D

0	200 400 600

- Feces (%dose) 1
| measured

1,000 1,200 1,400 1,600 1,800 2,000 2,200

1

2

3

4

5

6

7

- Urinary (%dose) I
| measured

0 200 400 600 800 1,000 1,200 1,400 1,600 1,800 2,000 2,200

Figure 3-26. Comparison of experimental data (symbols) and model
predictions (solid lines) of (A) blood concentration, (B) liver concentration,
(C) adipose tissue concentration (D) feces excretion (% dose) and (E) urinary
elimination (% dose) of TCDD after oral exposure to 150 ng/kg-day,
5 days/week for 13 weeks in mice. Y-axis represents concentration in pg/g and
X-axis represents time in days.

Source: Experimental data were obtained form Diliberto et al. (2001, 197238).

This document is a draft for review purposes only and does not constitute Agency policy.

3-95 DRAFT—DO NOT CITE OR QUOTE


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0 5 10 IS 20 25 30 35 40 45 50 55 60 65 70 75

24
22
20
18
16

f s

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75

1

2	Figure 3-27. PBPK model simulations (solid lines) vs. experimental data

3	(symbols) on the distribution of TCDD after a single acute oral exposure to

4	A-B) 0.1, C-D) 1.0 and E-F) 10 jig of TCDD/kg of body weight in mice.

5	Liver and adipose concentration for each dose was measured after 72 hours.

6	Y-axis represents the concentration in tissues (ng/g); insets A, C, and E represent

7	liver tissue, whereas B, D, and F correspond to adipose tissue. X-axis represents

8	the time in hours.

9	Source: experimental data were obtained from Santostefano et al. (1996, 594258).

This document is a draft for review purposes only and does not constitute Agency policy.

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3.2
3
2.8
2.6
2 .4

2.2
2

1.3
1.6

1.4

1.2
1

0-8

0,6
0,4
0.2

y] — Cb (ng/g)
v- ¦ experimental I

280 282 284 286 288 290 292 294 296 298 300 302 304 306 308 310 312 314 316 318 320

0	Cli (ng/g)

¦ experimental I

280 282 284 286 288 290 292 294 296 298 300 302 304 306 308 310 312 314 316 318 320

1

2

3

4

5

6

7

[y]	Cf (ng/g)

|H| Experimental I

280 282 284 286 288 290 292 294 296 298 300 302 304 306 308 310 312 314 316 318 320

Figure 3-28. PBPK model simulation (solid lines) vs. experimental data
(symbols) on the distribution of TCDD after a single dose of 24 ng/kgBW on
GD 12 in mice. Concentrations expressed as ng TCDD/g tissue. (A) maternal
blood, (B) maternal liver and (C) maternal adipose tissue. Y-axis represents the
tissue concentration whereas X-axis represents the time in hours.

Source: Experimental data were obtained from (Abbott et al., 1996, 155093).

This document is a draft for review purposes only and does not constitute Agency policy.

3-97 DRAFT—DO NOT CITE OR QUOTE


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	CADM (human)

	Emond (human)

	CADM (rat)

	Emond (rat)

o>

D>

D)

>
T>
O

m

v

Q.
C

V
T>

m

>
T>

o
m

1
1
1
1
1
1
1
1

.E+07
.E+06
.E+05
.E+04
.E+03
.E+02
.E+01
.E+00

100

Intake (ng/kg-day)

1000

10000

1

2	Figure 3-29. Comparison of the near-steady-state body burden simulated

3	with CADM and Emond models for a daily dose ranging from 1 to

4	10,000 ng/kg-day in rats and humans. The rat model was run for 13 weeks and

5	the human model was run from age 20 to 30. The time-averaged concentration

6	was used for each.

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

3-98 DRAFT—DO NOT CITE OR QUOTE


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2

Q)
C

C

o

c
CD
O
c
o
o

"a
o
o
_Q

a
a

o

o
o
CM

O
LO

o
o

o
LO

peak 5-year average concentration
	ge sta t i^n_aj_^^rage_co n ce n trat io n

lifetime average concentration

Concentration-time profile
Less-than-lifetime scenario
Gestational scenario
Lifetime scenario

ir~

60

20

40

Year

Figure 3-30. TCDD serum concentration-time profile for lifetime, less-than-lifetime and gestational exposure
scenarios, with target concentrations shown for each; profiles generated with Emond human PBPK model.


-------
Q)

Q)
C

C

o

c
CD
O
c
o
o

"a
o
o

_Q

O
Q

O

o
LO
CM

O
O
CM

O
LO

O
O

O
LO

Lifetime scenario
Less-than-lifetime scenario
Gestational scenario
Target concentration

~~r~
40

~T

60

20

Year



Figure 3-31. TCDD serum concentration-time profile for lifetime, less-than-lifetime and gestational exposure
scenarios, showing continuous intake levels to fixed target concentration; profiles generated with Emond human
PBPK model.


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35

4. CHRONIC ORAL REFERENCE DOSE

This section presents U.S. Environmental Protection Agency (EPA)'s response to the
National Academy of Sciences (NAS) recommendations that EPA more explicitly discuss the
modeling of noncancer endpoints and develop a reference dose (RfD) to address noncancer
effects associated with oral 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposures. Section 2
details the selection of the animal studies with the lowest TCDD doses associated with the
development of adverse noncancer effects and the selection of relevant epidemiologic studies of
adverse noncancer health effects. Section 3 discusses the kinetic modeling and estimation of
human equivalent daily oral doses that are used in TCDD RfD development in this section. This
section discusses the modeling of noncancer health effects data associated with TCDD exposure
and the derivation of an RfD. Specifically, Section 4.1 summarizes the NAS comments on
TCDD dose-response modeling and EPA's response, including justification of selected
noncancer effects and statistical characterization of modeling results. Section 4.2 presents the
TCDD dose-response modeling undertaken for identification of candidate points of departure
(PODs) for derivation of an RfD. In Section 4.3, EPA derives an RfD for TCDD. Finally,
Section 4.4 describes the qualitative uncertainties in the RfD.

4.1. NAS COMMENTS AND EPA'S RESPONSE ON IDENTIFYING NONCANCER
EFFECTS OBSERVED AT LOWEST DOSES

The NAS recommended that EPA identify the noncancer effects associated with low dose
TCDD exposures and discuss its strategy for identifying and selecting PODs for noncancer
endpoints, including biological significance of the effects.

With respect to noncancer end points, the committee notes that EPA does not use

a rigorous approach for evaluating evidence from studies... (NAS, 2006,

198441p. 47)

The Reassessment should describe clearly the following aspects:

1.	The effects seen at the lowest body burdens that are the primary focus for any
risk assessment—the "critical effects."

2.	The modeling strategy used for each noncancer effect, paying particular
attention to the critical effects, and the selection of a point of comparison based
on the biological significance of the effect; if the ED0i is retained, then the

This document is a draft for review purposes only and does not constitute Agency policy.

4-1 DRAFT—DO NOT CITE OR QUOTE


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biological significance of the response should be defined and the precision of
the estimate given... (NAS, 2006, 198441 p. 187).

In this document, EPA has developed a strategy for identifying the noncancer data sets
and PODs that represent the most sensitive and biologically relevant endpoints for derivation of
an RfD for TCDD. EPA began this process by using the animal bioassays and human
epidemiologic studies that met its study inclusion criteria as sources of these data sets.

For all epidemiologic studies that were identified as suitable for further quantitative
dose-response analyses in Section 2.4.3, EPA has chosen to identify PODs (i.e., estimates of a
no-observed-adverse-effect level [NOAEL] or lowest-observed-adverse-effect level [LOAEL];
modeling of a benchmark dose lower confidence bound [BMDL] was not possible given the data
presented in these studies). Figure 4-1 shows EPA's process to select and identify candidate
PODs from these key epidemiologic studies. EPA first evaluated the dose-response information
in the study to determine whether it provided an estimate of TCDD dose and an observed
noncancer effect that was relevant for RfD derivation. If such data were available, then EPA
identified a NOAEL or LOAEL as a candidate POD. For each of these, EPA applied a human
kinetic model to estimate the continuous oral daily intake (ng/kg-day) associated with the POD
that could be used in the derivation of an RfD (see Section 4.2). If all of this information was
available, then the result was included as a candidate POD.

Figure 4-2 summarizes the strategy employed for identifying and selecting candidate
PODs from the key animal bioassays identified in Section 2.4.3 for use in noncancer
dose-response analysis of TCDD. For each noncancer endpoint, EPA first evaluated the
toxicologic relevance of each endpoint, rejecting those judged not to be relevant for RfD
derivation. Next, initial PODs (NOAELs, LOAELs, and BMDLs) based on the first-order body
burden metric (see Section 3.3.4.2) and expressed as human-equivalent doses (HEDs) were
determined for all relevant endpoints (summarized in Table 4-3). Because there were very few
NOAELs and BMDL modeling was largely unsuccessful due to data limitations, the next stage
of evaluation was carried out using LOAELs only. Within each study, endpoints not observed at
the LOAEL (i.e., reported at higher doses) with BMDLs greater than the LOAEL were
eliminated from further analysis, as they would not be considered as candidates for the final POD
on either a BMDL or NOAEL/LOAEL basis (i.e., the POD would be higher than the PODs of

This document is a draft for review purposes only and does not constitute Agency policy.

4-2 DRAFT—DO NOT CITE OR QUOTE


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other relevant endpoints). In addition, all endpoints with HED estimates based on LOAELs
(LOAELreds) beyond a 100-fold range of the lowest identified LOAELred were eliminated
from further consideration, as they would not be potential POD candidates either (i.e., the POD
would be higher than the PODs of other relevant endpoints). For the remaining endpoints, EPA
then determined final potential PODs (NOAELs, LOAELs and BMDLs) based on TCDD blood
concentrations obtained from the Emond rodent physiologically based pharmacokinetic (PBPK)
models. HEDs were then estimated for each of these PODs using the Emond human PBPK
model. From these HEDs, a PODred was selected19 for each study as the basis for the candidate
RfD, to which appropriate uncertainty factors (UFs) were applied following EPA guidelines.
The resulting candidate RfDs were then considered in the final selection process for the RfD.
Other endpoints occurring at slightly higher doses representing additional effects associated with
TCDD exposure (beyond the 100-fold LOAEL range) were evaluated, modeled, and included in
the final candidate RfD array20 to examine endpoints not evaluated by studies with lower PODs.
In addition, BMD modeling based on administered dose was performed on all endpoints for
comparison purposes. The final array of selected endpoints is shown in Table 4-4 (summary of
BMD analysis) and Table 4-5 (candidate RfDs).

The NAS recommended that EPA better justify the selection of response levels for
endpoints used to develop risk estimates. The NAS commented on EPA's decision to estimate
an EDoi (effective dose eliciting a 1% response) for noncancer bioassay/data set combinations as
a comparative tool across studies, suggesting that EPA identify and evaluate the levels of change
associated with adverse effects to define the benchmark response (BMR) level for continuous
noncancer endpoints.

The committee notes that the choice of the 1% response level as the POD
substantially affects ... the noncancer analyses.... The committee recommends
that the Reassessment use levels of change that represent clinical adverse effects
to define the BMR level for noncancer continuous end points as the basis for an
appropriate POD in the assessment of noncancer effects (NAS, 2006, 198441.
p. 72).

19In the standard order of consideration: BMDL, NOAEL, and LOAEL.

20However, studies with a lowest dose tested greater than 30 ng/kg-day were not included in the expanded
evaluation.

This document is a draft for review purposes only and does not constitute Agency policy.

4-3 DRAFT—DO NOT CITE OR QUOTE


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The committee concludes that EPA did not adequately justify the use of the
1% response level (the ED0i) as the POD for analyzing epidemiological or animal
bioassay data for ... noncancer effects (NAS, 2006, 198441 p. 18).

In the 2003 Reassessment (U.S. EPA, 2003, 537122). EPA was not attempting to derive
an RfD when it conducted TCDD dose-response modeling. The 2003 Reassessment developed
EDoi estimates for noncancer effects in an attempt to compare disparate endpoints on a
consistent response scale. Importantly, the 2003 Reassessment defined the ED0i as 1% of the
maximal response for a given endpoint, not as a 1% change from control. Because RfD
derivation is one goal of this document, the noncancer modeling effort undertaken here differs
substantially from the modeling in the 2003 Reassessment.

The NAS committee was concerned with the statistical power to determine the shape of
the dose-response curve at doses far below observed dose-response information. EPA agrees
that the shape of the dose-response curve in the low-dose region cannot be determined
confidently when based on higher-dose information. An observed response above background
near (or below) the BMR level is needed for discrimination of the shape of the curve and for
accurate estimation of an EDX or BMDL. Although many of the ED0iS presented in the 2003
Reassessment were near the lowest dose tested, responses at the lowest doses were often high
and much greater than a 1% response (i.e., 1% of the maximum response). The lack of an
observed response near the BMR level is often a problem in interpretation of BMD modeling
results.

In this document, EPA has used a 10% BMR for dichotomous data for all endpoints;
there were no developmental studies that accounted for litter effects, for which a 5% BMR would
be used (U.S. EPA, 2000, 052150). For continuous endpoints in this document, EPA has used a
BMR of 1 standard deviation from the control mean whenever a specific toxicologically-relevant
BMR could not be defined. For the vast majority of continuous endpoints, EPA could not
establish unambiguous levels of change representative of adversity, which EPA defines as "a
biochemical change, functional impairment, or pathologic lesion that affects the performance of
the whole organism, or reduces an organism's ability to respond to an additional environmental
challenge" (U.S. EPA, 2009, 192196). For body and organ weight change, EPA has previously
established a BMR of 10% change, which also is used in this document.

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The NAS commented on EPA's development of ED0i estimates for numerous study/data
set combinations in the 2003 Reassessment, suggesting that EPA had not appropriately
characterized the statistical confidence around such model predictions in the low-response region
of the model.

It is critical that the model used for determining a POD fits the data well,
especially at the lower end of the observed responses. Whenever feasible,
mechanistic and statistical information should be used to estimate the shape of the
dose-response curve at lower doses. At a minimum, EPA should use rigorous
statistical methods to assess model fit and to control and reduce the uncertainty of
the POD caused by a poorly fitted model. The overall quality of the study design
is also a critical element in deciding which data sets to use for quantitative
modeling (NAS, 2006, 198441. p. 18).

EPA should ... assess goodness-of-fit of dose-response models for data sets and
provide both upper and lower bounds on central estimates for all statistical
estimates. When quantitation is not possible, EPA should clearly state it and
explain what would be required to achieve quantitation (NAS, 2006, 198441.
p. 10).

The NAS also commented that EPA report information describing the adequacy of
dose-response model fits, particularly in the low response region. For those cases where
biostatistical modeling was not possible, NAS recommended that EPA identify the reasons.

The Reassessment should also explicitly address the importance of statistical
assessment of model fit at the lower end and the difficulties in such assessments,
particularly when using summary data from the literature instead of the raw data,
although estimates of the impacts of different choices of models would provide
valuable information about the role of this uncertainty in driving the risk estimates
(NAS, 2006, 198441. p. 73).

To address this concern, in this document EPA has reported the standard suite of
goodness-of-fit measures from the benchmark dose modeling software (BMDS 2.1). These
include chi-square^-values, Akaike's Information Criterion (AIC), scaled residuals at each dose
level and plots of the fitted models. In some cases, when restricted parameters hit a bound, EPA
used likelihood ratio tests to evaluate whether the improvement in fit afforded by estimating
additional parameters could be justified. Goodness-of-fit measures are reported for all key data

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sets in Appendix E. (See Section 4.2.4.2 for a more complete description of the benchmark dose
modeling criteria for model evaluation.)

4.2. NONCANCER DOSE-RESPONSE ASSESSMENT OF TCDD

This section describes EPA's current effort to conduct an evaluation of TCDD
dose-response for the noncancer endpoints from studies that met the study inclusion criteria.
Discussions include benchmark dose modeling procedures, kinetic modeling, and POD
candidates for derivation of the RfD. Section 4.2.1 discusses the types of endpoints that are
considered relevant by EPA's Integrated Risk Information System and lists the study/endpoint
combinations that were not considered for the TCDD RfD derivation, with supporting text in
Appendix G. Section 4.2.2 describes how EPA has used physiologically-based pharmacokinetic
(PBPK) modeling to estimate effective internal exposures as an alternative to using administered
doses or body burdens based on first-order kinetics. Section 4.2.3 details the dose-response
analysis of the epidemiologic data, with supporting information on kinetic modeling in
Appendix D. Section 4.2.4 details the dose-response analysis for the animal bioassay data;
Appendix E provides the BMDS input tables (see Section E. 1) and output for all modeling,
including blood concentrations (see Section E.2) and administered dose (see Section E.3).

4.2.1. Determination of Toxicologically Relevant Endpoints

The NAS committee commented on the low dose model predictions and the need to
discuss the biological significance of the noncancer health effects modeled in the 2003
Reassessment. In selecting POD candidates from the animal bioassays for derivation of the
candidate RfDs, EPA had to consider the toxicological relevance of the identified endpoint(s)
from any given study. Some endpoints/effects may be sensitive, but lack general toxicological
significance due to not being clearly adverse (defined in EPA's Integrated Risk Information
System glossary as "a biochemical change, functional impairment, or pathologic lesion that
affects the performance of the whole organism, or reduces an organism's ability to respond to an
additional environmental challenge" (U.S. EPA, 2009, 192196)). being an adaptive response or
not being clearly linked to downstream functional or pathological alterations. For example, CYP
induction alone is not considered a significant toxicological effect given that CYPs are induced
as part of the hepatic metabolism of xenobiotic agents. Additionally, the role of CYP induction

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in hepatotoxicity and carcinogenicity of TCDD is unknown, thus, CYP induction is not
considered a relevant POD without obvious pathological significance. Another example is when
all oxidative stress markers are significantly affected, but no other indicators of brain pathology
are assessed. In this case, it is impracticable to link the markers of oxidative stress to a
toxicological outcome in the brain; thus, this endpoint is not considered a relevant POD
candidate. It is standard EPA practice for RfD derivation to base a reference value on endpoints
that are adverse or are immediate precursors to an adverse effect.

Studies meeting the study selection criteria with endpoints that were not considered for
derivation of a candidate RfD (because they were not considered to be toxicologically relevant
noncancer effects) are: Kitchin and Woods (1979, 198750). Hassoun et al. (1998, 136626; 2000,
197431: 2002, 543725: 2003, 1987261 Burleson et al. (1996, 1969981 Kuchiiwa et al. (2002,
198355). Mally and Chipman (2002, 198098). Vanden Heuvel et al. (1994, 197551). Devi to
et al. (1994, 197278). Lucier et al. (1986, 198398). Sugita-Konishi et al. (2003, 198375). and
Sewall et al. (1993, 197889). Appendix G identifies the endpoints from these studies that were
not considered to be toxicologically relevant for derivation of an RfD (e.g., cytochrome P450
induction, oxidative stress measures, gap junction disruption, mRNA induction, brain serotonin
levels) and provides the rationales for the toxicological relevance decisions on the endpoints.
Note that for many of these studies, other endpoints were examined that are toxicologically
relevant and were considered in the RfD derivation process.

4.2.2. Use of Toxicokinetic Modeling for TCDD Dose-Response Assessment

Given that TCDD accumulates in fat with continuous exposure and is eliminated slowly
from the body, but at very different rates across species, EPA has determined that the standard
UF approach or allometric scaling of body weight for interspecies extrapolation is not
appropriate. Therefore, EPA has decided to use toxicokinetic modeling to estimate an effective
internal dose for equivalence across species. The toxicokinetic models chosen by EPA are the
rodent and human PBPK models described by Emond et al. (2004, 197315: 2006, 197316) and
modified by EPA for this assessment as described in Section 3.3.4 (hereafter referred to as the
"Emond [rodent or human] PBPK model"). Both the rodent and human models have a
gestational component, which allow for more relevant exposure comparisons between general
adult exposures and the numerous gestational exposure studies. Ideally, a relevant tissue

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concentration for each effect would be estimated. However, no models exist for estimation of all
relevant tissue concentrations. As virtually all TCDD is found in the adipose fraction of tissues,
or bound to specific proteins, a preferred approach to developing a dose metric would be to
account for the fat fraction of each tissue and protein binding; however, EPA has decided that the
modeling of such estimates is too uncertain and EPA has not found sufficient data to implement
this approach. Therefore, EPA has decided to use the concentration of TCDD in blood as a
surrogate for tissue concentrations, assuming that tissue concentrations are proportional to blood
concentrations. Furthermore, because the RfD is necessarily expressed in terms of average daily
exposure, the blood concentrations are expressed as averages over the relevant period of
exposure for each endpoint. For the animal bioassay studies, the relevant period of exposure is
the duration of dosing, starting at the age of the animals at the beginning of the study. For
humans, the relevant period of exposure is generally lifetime, which is defined as 70 years by
convention. However, EPA varied the averaging time for the equivalent human blood
concentrations to correspond to the test-animal exposure duration in the following manner.

•	For correspondence with animal chronic exposures,21 the human-equivalent
TCDD blood concentration is assumed to be the 70-year average.

•	For correspondence with animal gestational exposures, the human-equivalent
TCDD blood concentration is assumed to be the average over 45 years for a
female, beginning at birth, plus 9 months of gestational exposure. The choice of
45 years to beginning of pregnancy is health protective of the population in that
the TCDD daily oral intake achieving the target blood concentration is smaller
than for shorter averaging times.22

•	For correspondence with any other animal exposure duration, the
human-equivalent TCDD blood concentration is assumed to be the average over
the equivalent human exposure duration calculated backward from the peak
exposure plateau at or near the end of the 70-year scenario. The average is
determined from the terminal end of the human exposure period because the daily
oral intake achieving the target blood concentration is smaller than for the same
exposure period beginning at birth and is health protective for effects occurring
after shorter-term exposure. The determination of equivalent exposure durations
across species is problematic and somewhat arbitrary, so EPA uses the average
peak blood concentration as the human equivalent for all less-than-chronic animal

21 Assumed to be >75% of nominal lifetime, or about 550 days in rodents.

22See Section 3.3.4.2 for a discussion of this issue, including a comparison of the 45-year old pregnancy scenario to
one beginning at age 25 in Table 3-15.

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exposures (other than gestational).23 For the first-order kinetics model, the
average peak exposure is close to the theoretical steady-state asymptote (see
Section 3.3.4.2). However, for the Emond human PBPK model used by EPA in
this assessment, the timing of the peak exposure is dose-dependent and tends to
decline after 60 years in some cases. Therefore, the 5-year average TCDD blood
concentration that includes the peak ("5-year peak") is used as the relevant
dose-metric for the PBPK model applications.

4.2.3. Noncancer Dose-Response Assessment of Epidemiological Data

The following four epidemiologic studies describing noncancer endpoints were identified
in Section 2.4.3 as studies to be evaluated for development of PODs for derivation of candidate
RfDs: Baccarelli et al. (2008, 197059). Mocarelli et al. (2008, 199595). Alaluusua et al. (2004,
197142) and Eskenazi et al. (2002, 197168). Each of these studies described effects observed in
the Seveso cohort (see detailed study summaries in Section 2.4.1 and Table 2-5). Each study
modeled individual-level human exposure measures and provided information from which EPA
could determine an exposure window over which kinetic models could be used to quantify
TCDD exposures for dose-response assessment. EPA used kinetic information to estimate
group-mean daily TCDD intake rates for the exposure groups presented in these studies (see
Appendix D for details). EPA focused on identifying NOAELs and LOAELs for these studies;
EPA did not conduct Benchmark Dose modeling because the covariates identified by the study
authors could not be incorporated by modeling the grouped response data. EPA's development
of PODs for these studies is described in this section and shown in Table 4-1.

4.2.3.1. Baccarelli et al (2008,197059)

For Baccarelli et al. (2008, 197059). EPA was able to define a LOAEL as the group mean
of 39 ppt TCDD in neonatal plasma for thyroid stimulating hormone (TSH) values above
5 |iU/mL. (See Section 2.4.1.2.1.5.7 for study details.) Baccarelli et al. (2008, 197059) did not
estimate the equivalent oral intake associated with TCDD serum concentrations and gave only
neonatal serum TCDD concentrations for the groups above and below the 5 |iU/mL standard.
The study authors, however, developed a regression model relating the level of TSH in 3-day-old

23By comparison to a half-lifetime equivalent (1 year in rodents, 35 years in humans), the ratio of body burden
(lst-order kinetic model) to oral intake does not differ significantly from the average-peak scenario; all shorter-term
scenarios differ even less (see Section 3.3.4.2). These relationships, with respect to the 5-year peak, hold for the
PBPK model results, as well (see Section 3).

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neonates to TCDD concentrations in maternal plasma at birth (given as lipid-adjusted serum
concentrations, LASC). The authors extrapolated maternal plasma concentrations from previous
measurements using a simple first-order pharmacokinetic model. Because there is limited
information regarding the relationship between maternal and neonatal serum TCDD levels, EPA
determined that there was too much uncertainty in estimating maternal intake from neonatal
TCDD serum concentrations, directly. Therefore, EPA determined the maternal intake at the
LOAEL from the maternal serum-TCDD/TSH regression model by finding the maternal TCDD
LASC at which neonatal TSH exceeded 5 |iU/mL. EPA then used the Emond PBPK model
under the human gestational scenario (see Section 4.2.2) to estimate the continuous daily oral
TCDD intake that would result in a TCDD LASC corresponding to a neonatal TSH of 5 |iU/mL
at the end of gestation; EPA established the resulting maternal intake (0.024 ng/kg-day) as the
LOAEL, shown in Table 4-1 as a candidate POD for derivation of candidate RfDs (PBPK
modeling details are shown in Appendix D).

4.2.3.2. Mocarelli et al. (2008,199595)

Mocarelli et al. (2008, 199595) reported decreased sperm concentrations (20%) and
decreased motile sperm counts (11%) in men who were 1-9 years old in 1976 at the time of the
accident (initial TCDD exposure event) (see Section 2.4.1.2.1.5.8 for study details). Men who
were 10-17 years old in 1976 were not adversely affected. Serum (LASC) TCDD levels were
measured within one year of the initial exposure. Serum TCDD levels and corresponding
responses were reported by quartile, with a reference group of less-exposed individuals assigned
a TCDD LASC value of 15 ppt (which was the mean of individuals outside the contaminated
area). The lowest exposed group mean was 68 ppt (1st quartile). Because effects were detected
only among boys under the age of 10, EPA assumes there is a maximum 10-year critical
exposure window for elicitation of these effects. However, for the exposure profile, with a high
initial pulse followed by an extended period of elimination with only background exposure, the
estimation of an average exposure resulting in the effect is problematic. Therefore, EPA
implemented a procedure for the estimation of the continuous daily TCDD intake associated with
the LOAEL in the Mocarelli et al. (2008, 199595) study using the following 5-step process:

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1.	Using the Emond human PBPK model, the initial (peak) blood TCDD concentrations
associated with the accident were back-calculated based on the time that had elapsed
between the explosion and the serum collection. As serum measurements were taken
within 1 year after the event, a lag time of 0.5 years was assumed.

2.	The oral exposure associated with the peak blood TCDD concentration (peak exposure)
was calculated using the Emond PBPK model.

3.	Starting with the peak exposure and accounting for background TCDD intake, the
average daily blood TCDD concentration experienced by a representative individual in
the susceptible population (boys under 10 years old) was estimated using the Emond
PBPK model. Assuming a uniform distribution of subject ages at the time of the event,
the average age of the exposed male children would be 5 years. Consequently, a critical
exposure window for the cohort was estimated to be, on average, 5 years (i.e., a boy aged
5 years would remain in this exposure window for 5 more years until he was 10 years of
age).

4.	Using the Emond PBPK model, the average daily TCDD intake rate needed to attain the
5-year average blood TCDD concentration in a boy 10 years old was calculated.

5.	The LOAEL POD was calculated as the average of the peak exposure (0.032 ng/kg-day)
and the 5-year average exposure (0.0080 ng/kg-day), resulting in LOAEL of

0.020 ng/kg-day, shown in Table 4-1 as a candidate POD for derivation of a candidate
RfD. However, neither of the extremes was used because (1) the peak exposure does not
account for the continuing internal exposure from TCDD given its slow elimination, and
(2) the 5-year average does not reflect the influence of the much higher peak exposure,
which may be a significant factor in TCDD toxicity (Kim et al., 2003, 199146).

The PBPK modeling details are shown in Appendix D.

4.2.3.3. Alaluusua et al. (2004,19 ^ 142)

For Alaluusua et al. (2004, 1971421 the approach for estimation of daily oral TCDD
intake is virtually identical to the approach used for the Mocarelli et al. (2008, 199595) data.
(See Section 2.4.1.2.1.5.5 for study details.) Alaluusua et al. (2004, 197142) reported dental
effects in male and female adults who were less than 5 years of age at the time of the initial
exposure (1976). For the 75 boys and girls who were less than 5 years old at the time of the
accident, 25 (33%) were subsequently diagnosed with some form of dental enamel defect. For
the 38 individuals who were older than 5, only 2 (5.3%) suffered dental enamel defects at a later
date. A window of susceptibility of approximately 5 years is established. Serum measurements
for this cohort were taken within a year of the accident. Serum TCDD levels and corresponding
responses were reported by tertile, with a reference group of less-exposed individuals assigned a

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TCDD LASC value of 15 ppt (ng/kg); the tertile group means were 130, 383, and 1,830 ppt.
The incidence of dental effects for the reference group was 26% (10/39). The incidence of
dental effects in the 1st, 2nd and 3rd tertile exposure groups was 10% (1/10), 45% (5/11) and
60% (9/15), respectively. EPA judged that the NOAEL and LOAEL were 130 and 383 ppt
TCDD in serum. Following the same procedure used for the Mocarelli et al. (2008, 199595)
study (see Section 4.2.3.2), EPA estimated the continuous daily human oral TCDD intake
associated with each of the tertiles for both peak and average exposure across the critical
exposure window, assuming that the average age of the susceptible cohort at the time of the
accident was 2.5 years. Separate estimates for boys and girls were developed based on both the
peak intake and average intake across the critical exposure window (PBPK modeling details are
shown in Appendix D). The estimated averaged daily oral intakes for the tertiles, averaged for
boys and girls, are 0.20, 1.7, and 30 ng/kg-day for the peak exposure and 0.033, 0.15 and
1.5 ng/kg-day for the critical exposure window average. A study NOAEL at the second tertile of
0.12 ng/kg-day was identified as a candidate POD for derivation of a candidate RfD in Table 4-1.

4.2.3.4. Eskenazi et al. (2002,197168)

The approach used to estimate daily TCDD intake in Eskenazi et al. (2002, 197168)
combines the approaches EPA used for Baccarelli et al. (2008, 197059). Mocarelli et al. (2008,
199595) and Alaluusua et al. (2004, 197142). Eskenazi et al. (2002, 197168) reported menstrual
effects in female adults who were premenarcheal in 1976 at the time of the initial exposure (see
Section 2.4.1.2.1.4.1 for study details). In Rigon et al. (2009), the median age at menarche was
shown to be 12.4 in Italian females with intergenerational decreases in age at menarche. Thus,
EPA established a window of susceptibility of approximately 13 years for this analysis. The
average age of the premenarcheal girls at the time of the initial exposure in 1976 was 6.8 years,
establishing an average critical-window exposure duration of 6.2 years for this cohort. Serum
samples were collected within a year of the accident from this cohort. However, serum TCDD
levels and corresponding responses were not reported by percentile and no internal reference
group was identified. As for Baccarelli et al. (2008, 197059). Eskenazi et al. (2002, 197168)
developed a regression model relating menstrual cycle length to plasma TCDD concentrations
(LASC) measured in 1976. The model estimated that menstrual cycle length was increased
0.93 days for each 10-fold increase in TCDD LASC, with a 95% confidence interval of-0.01 to

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1.86 days. EPA judged a 1-day increase in menstrual cycle length to be adverse; a normal
menstrual cycle length is 28 days. EPA then determined the 1976 TCDD serum level
corresponding to a 29-day menstrual cycle length in the exposed cohort from the regression
model developed by Eskenazi et al. (2002, 197168). Using this serum level, the peak initial
exposure and average exposure over the 6.2 year window were calculated using the Emond
human PBPK model, in the same manner as for Mocarelli et al. (2008, 199595) and Alaluusua
et al. (2004, 197142). The resulting peak TCDD intake is 3.2 ng/kg-day. The average exposure
experienced by this cohort over the critical exposure window is estimated to be 0.12 ng/kg-day.
The average of these two estimates is 1.64 ng/kg-day, which is designated as a LOAEL and
shown in Table 4-1. Because the LOAEL is almost 2 orders of magnitude higher than the
LOAELs for Baccarelli et al. (2008, 197059) and Mocarelli et al. (2008, 199595). it was not
considered further as a candidate POD for derivation of the RfD (PBPK modeling details are
shown in Appendix D).

4.2.4. Noncancer Dose-Response Assessment of Animal Bioassay Data

EPA followed the strategy illustrated in Figure 4-2 to evaluate the animal bioassay data
for TCDD dose-response. For the administered average daily doses (ng/kg-day) in each animal
bioassay, EPA identified NOAELs and/or LOAELs based on the original data presented by the
study author. Section 2.4.2 identifies these values in the study summaries and in Table 2-7.

These became candidate PODs for consideration in the derivation of an RfD for TCDD. The
candidate RfD values associated with these candidate PODs are presented in Table 4-5.
Additional PODs were identified using BMD modeling. All PODs were converted to HEDs
using the Emond PBPK models. The remainder of this Section describes the steps in this process
and concludes with the POD candidates from the animal bioassay data that were considered for
derivation of the RfD.

4.2.4.1. Use of Kinetic Modeling for Animal Bioassay Data

Blood concentrations corresponding to the administered doses in each mouse or rat
bioassay qualifying as a final RfD POD candidate were estimated using the appropriate Emond
rodent PBPK model. In each case, the simulation was performed using the exposure and
observation durations, body weights, and average daily doses from the original studies. For all

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multiple exposure protocols, the time-weighted average blood TCDD concentrations over the
exposure period were used as the relevant dose metric. For single (gestational and
nongestational) exposures, the initial peak blood TCDD concentrations were considered to be the
most relevant exposure metric. Gestational exposures were modeled using the species-specific
gestational component of the Emond rodent PBPK model. Bioassays employing exposure
protocols spanning gestational and postpartum life stages were modeled by sequential
application of the gestational and nongestational models.

The Emond PBPK models do not contain a lactation component, so exposure during
lactation was not modeled explicitly. Only one bioassay (Shi et al., 2007, 198147) considered as
a POD candidate for RfD derivation included exposure during lactation. In Shi et al. (2007,
198147) pregnant animals were exposed weekly to TCDD throughout gestation and lactation.
Exposure was continued in the offspring following weaning for 10 months. For assessment of
maternal effects, the Emond gestational model was used, terminating at parturition. For
assessment of long-term exposure in the offspring, the Emond nongestational model was used,
ignoring prior gestational and lactational exposure, with the assumption that the total exposure
during these periods was small relative to exposure in the following 10 months. The assumption
is conservative in that effects observed in the offspring would be attributed entirely to adult
exposure, which is somewhat less than the actual total exposure.

The model code, input files and PBPK modeling results for each bioassay are reported in
Appendix C. These predicted TCDD blood concentrations were used for benchmark dose
modeling of bioassay response data and determination of NOAELs and LOAELs. BMD
modeling was performed, as described in Section 3.5.2.2.1, by substituting the modeled blood
concentrations for the administered doses and calculating the corresponding BMDL. For each of
these LOAEL, NOAEL, or BMDL blood-concentration equivalents, corresponding HEDs were
calculated using the Emond human PBPK model for the appropriate gestational or nongestational
scenario as described previously (see Section 4.2.2).

4.2.4.2. Benchmark Dose Modeling of the Animal Bioassay Data

Benchmark dose modeling was performed using BMDS 2.1, Build 06/16/09 to estimate
BMDs and BMDLs for each study/endpoint combination. The input data tables for these
noncancer studies are shown in Appendix E, Section E.l, including both administered doses

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(ng/kg-day) and blood concentrations (ng/kg) and either incidence data for the dichotomous
endpoints or mean and standard deviations for the continuous endpoints. (See Section 4.2.4.1
and Sections 3.3.4 and 3.3.5 for a description of the development of TCDD blood concentrations
using kinetic modeling.)

Evaluation of BMD modeling performance, goodness-of-fit, dose-response data, and
resulting BMD and BMDL estimates included statistical criteria as well as expert judgment of
their statistical and toxicological properties. For the continuous endpoints, all available models
were run separately using both the assumption of constant variance and the assumption of
modeled variance. Saturated (0 degrees of freedom) model fits were rejected from consideration.
Parameters in models with power or slope parameters were constrained to prevent supralinear
fits, which EPA considers not to be biologically plausible and which often have undesirable
statistical properties (i.e., the BMDL diverges towards zero). However, if the constrained
parameters were estimated at their lower bounds, the unrestricted model was fit to the data,
primarily for elucidation of the degree of supralinearity present in the data. Depending on the
latter and the magnitude of the BMDL relative to the BMD, unrestricted model fits were
occasionally deemed acceptable. Table 4-2 shows each model and any restrictions imposed.

For the quantal/dichotomous endpoints, all primary BMDS dichotomous models were
run. The alternative dichotomous models were fit to several data sets, but the results were very
sensitive to the assumed independent background response and the fits were not accepted. The
confidence level was set to 95% and all initial parameter values were set to their defaults in
BMDS. For the continuous endpoints, one standard deviation was chosen as the default for the
BMR when a specific toxicologically-relevant BMR could not be defined. For the dichotomous

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endpoints, a BMR of 10% extra risk was used for all endpoints.

The model output tables in Appendix E show all of the models that were run, both
restricted and unrestricted, goodness-of-fit statistics, BMD and BMDL estimates, and whether
bounds were hit for constrained parameters. After all models were run, the one giving the best
fit was selected using the selection criteria in the current BMDS draft guidance (U.S. EPA, 2000,
052150") where possible. Acceptable model fits were those with chi-square goodness-of-fit
/(-values greater than 0.1. For continuous endpoints, a preference was held for models with an
asymptote term (plateau for high-dose response) because continuous measures do not continue to

24There were no developmental studies that accounted for litter effects, for which a 5% BMR would be used.

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rise (or fall) with dose forever; this phenomenon is particularly evident for TCDD. Unbounded
models, such as the power model, must account for the plateauing effect entirely in the shape
parameter, generally resulting in an abnormally supralinear fit. Also, for the continuous
endpoints, the p-walue for the homogenous variance test (Test 2) was used to determine whether
constant variance {p > 0.1) or modeled (nonconstant) variance (p < 0.1) should be used. As
BMDS offers only one variance model, model fits for nonconstant variance models were not
necessarily rejected if the variance model did not fit well (Test 3 p-w alue < 0.05). Within the
group of models with acceptable fits, the selected model was generally the one with the lowest
BMDL, unless the AIC was much higher (ca. +2) than another model. However, particularly for
continuous models, the fit of the model to the control mean and standard deviation and in the
lower response range was assessed. Models with higher BMDLs or AICs but much better fit to
the lower response data were often chosen over the nominally best-fitting model.

For many data sets, no models satisfied the acceptance criteria and no clear BMD/BMDL
selection could be made. In theses cases, model fits were examined on an individual basis to
determine the reasons for the poor fits. On occasion, high doses were dropped and the models
were refit. Also, if a poor fit to the control mean was evident, the model was refit to the data
after fixing the control mean by specifying the relevant parameter in BMDS. However, these
techniques rarely resulted in better fits. If the fit was still not acceptable, the NOAEL/LOAEL
approach was applied to the study/data set combination. Most of the problems with BMD
modeling were a consequence of lack of response data near the BMR; many of the TCDD data
sets failed to show a response near the BMR, whether it was a 10% dichotomous relative change
or a continuous 1 standard deviation change. Responses at the lowest doses were generally much
higher than the BMR, resulting in a lack of anchoring at the critical response levels of interest
causing numerical problems in the estimation of BMDLs.

4.2.4.3. POD Candidates from Animal Bioassays Based on HED and BMD Modeling Results

Table 4-3 summarizes the PODs that EPA estimated for each key animal study included
for TCDD noncancer dose-response modeling. After estimating the blood TCDD concentration
associated with a particular toxicity measure (NOAEL, LOAEL, or BMDL) obtained from a
rodent bioassay, EPA estimated a corresponding HED using the Emond human PBPK model
(described in Section 3). Table 4-3 summarizes the NOAEL, LOAEL, or BMDL (ng/kg) based

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on the administered animal doses for each key bioassay/data set combination. Table 4-3 also
summarizes the continuous daily HED corresponding to these administered doses as 1st order
body burdens and as blood concentrations. The doses in Table 4-3 are defined as follows, all in
units of ng/kg-day:

•	Administered Dose NOAEL: Average daily dose defining the NOAEL for the test species
in the animal bioassay

•	Administered Dose LOAEL: Average daily dose defining the LOAEL for the test species
in the animal bioassay

•	Administered Dose BMDL: BMDL for the test species based on modeling of the
administered doses from the animal bioassay

•	First-Order Body Burden HED NOAEL: Average daily dose defining the NOAEL for
humans derived from the animal bioassay using the first-order kinetics body-burden
model

•	First-Order Body Burden HED LOAEL: Average daily dose defining the LOAEL for
humans derived from the animal bioassay using the first-order kinetics body-burden
model

•	First-Order Body Burden HED BMDL: Human-equivalent BMDL from BMD modeling
of the animal bioassay data using first-order body burdens

•	Blood Concentration HED NOAEL: Average daily dose defining the NOAEL for
humans derived from the animal bioassay using the Emond human PBPK model

•	Blood Concentration HED LOAEL: Average daily dose defining the LOAEL for humans
derived from the animal bioassay using the Emond human PBPK model

•	Blood Concentration HED BMDL: Human-equivalent BMDL from BMD modeling of
the animal bioassay data using the Emond human PBPK model

An evaluation of key BMD analyses is presented in Table 4-4. Tables showing the best
model fit for each study/endpoint combination and the associated BMD/BMDL are shown in
Appendix E. As described above in Section 4.3.4.2, the BMD modeling was largely
unsuccessful, primarily because of a lack of response data near the BMR, poor modeled
representation of control values, or nonmonotonic responses yielding poor fits. The comments
column in Table 4-4 lists reasons for poor results.

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4.3. RfD DERIVATION

Table 4-5 lists all the studies and endpoints considered for derivation of the RfD. These
studies were chosen from the entire list of candidate study/data set combinations (see
Section 2.4.3) based on the toxicologic relevance of the endpoints and covering a range of the
most conservative RfD candidates that includes three of the four human studies.25 Figure 4-3
(exposure-response array) shows all of the endpoints listed in Table 4-5 graphically in terms of
PODs in human-equivalent intake units (ng/kg-day). The human study endpoints are shown at
the far left of the figure and the rodent endpoints are arranged by category to the right. (Note the
two studies in guinea pigs were estimated using first-order body burden kinetics which are not
directly comparable to the PODs based on the mouse, rat and human studies that were generated
from the Emond PBPK model. There are no published models for TCDD disposition in guinea
pigs and EPA did not develop one for this assessment.) Figure 4-4 demonstrates the same
endpoints, arrayed by RfD value, showing the POD, applicable UFs and candidate RfD.

Table 4-5 illustrates the study, species, strain and sex, study protocol, and toxicologic
endpoints observed at the lowest TCDD doses. The table also identifies the human-equivalent
BMDLs (when applicable), NOAELs and LOAELs, as well as the composite UF that applies to
the specific endpoint, and finally, the corresponding candidate RfD.26 The NOAELS, LOAELs,
and BMDLs are presented as HEDs, based on the assumption that blood concentration is the
toxicokinetically-equivalent TCDD dose metric across species and serves as a surrogate for
tissue concentration.27 For rats and mice, these estimates relied on the two Emond PBPK
models—one for the relevant rodent species and one for the human—as described previously
(see Section 3.3.4.3). The two guinea pig studies that are included in Table 4-5 are given in
HED units based on the first-order body burden model described in Section 3.3.4.2; there is
currently no TCDD PBPK model for the guinea pig. The values listed for guinea pigs are not
directly comparable to those for rats and mice but are probably biased low, as first-order body
burden HED estimates for rats and mice are generally 2- to 5-fold lower than the corresponding
PBPK model estimates. The LOAELs for the human studies also rely on the Emond PBPK
model, as described in Sections 4.2.2 and 4.2.3.

25The RfD derived from the study of Eskenazi et al. (2002, 1971681 was outside the RfD range presented in
Table 4-5.

26Extra significant digits are retained for comparison prior to rounding to one significant digit for the final RfD.
27The procedures for estimating HEDs based on TCDD blood concentration are described in the preceding section.

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As is evident from the Table 4-5, very few NOAELs and even fewer BMDLs have been
established for low-dose TCDD studies. BMD modeling was unsuccessful for all of the
endpoints without a NOAEL, primarily because of the lack of dose-response data near the BMR
(see discussion in Section 4.2). Therefore, the RfD assessment rests largely on evaluation of
LOAELs to determine the POD.

The rows in Table 4-5 are arranged in order of increasing candidate RfD magnitude.
Endpoints projected to occur at higher exposure levels are still considered for qualitative support
of the effects shown in Table 4-5.

4.3.1. Toxicological Endpoints

As can be seen in Table 4-5, a wide array of toxicological endpoints has been observed
following TCDD exposure, ranging from subtle developmental effects to overt chronic liver
toxicity. Developmental effects in rodents include dental defects, delayed puberty in males, and
several neurobehavioral effects. Reproductive effects reported in rodents include altered
hormone levels in females and decreased sperm production in males. Immunotoxicity endpoints
such as decreased response to SRBC challenge in mice and decreased delayed-type
hypersensitivity response in guinea pigs are also observed. Longer durations of TCDD exposure
in rodents elicit results such as organ and body weight changes, renal toxicity, and liver and lung
lesions. Adverse effects in human studies are also observed, which include male reproductive
effects, increased TSH in neonates, and dental defects in children. Analogous results have been
observed in animal bioassays for each of these human endpoints.

All but two of the study/endpoint combinations from animal bioassays listed in Table 4-5
are on TCDD-induced toxicity observed in mice and rats; the other two study/endpoint
combinations are effects in guinea pigs. Although the effects of TCDD have been investigated in
several other species (i.e., hamsters, monkeys, and mink), those studies were not included for
final POD consideration because the effect levels were greater than those in Table 4-5, or
because the effects could not be attributed solely to TCDD exposure (i.e., confounding by
dioxin-like compounds [DLCs]).

Three human studies were also included for final POD consideration in the derivation of
an RfD and are presented in Table 4-5 as candidate RfDs. All three human study/endpoint
combinations are from studies on the Seveso cohort. The developmental effects observed in

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these studies were associated with TCDD exposures either in utero or in early childhood between

1	and 10 years of age. Baccarelli et al. (2008, 197059) reported increased levels of TSH in
newborns exposed to TCDD in utero, indicating a possible dysregulation of thyroid hormone
metabolism. Mocarelli et al. (2008, 199595) reported decreased sperm concentrations and
decreased motile sperm counts in men who were 1-9 years old in 1976 at the time of the Seveso
accident (initial TCDD exposure event). Alaluusua et al. (2004, 197142) reported dental effects
in adults who were less than 9.5 years of age at the time of the initial exposure (1976).

4.3.2. Exposure Protocols of Candidate PODs

The studies in Table 4-5 represent a wide variety of exposure protocols, involving
different methods of administration and exposure patterns across virtually all exposure durations
and life stages. Both dietary and gavage administration have been used in rodent studies, with
gavage being the predominant method. Gavage dosing protocols vary quite widely and include
single gestational exposures, multiple daily exposures (for up to 2 weeks, intermittent schedules
that include 5 days/week, once weekly, or once every 2 weeks), and loading/maintenance dose
protocols, in which a relatively high dose is initially administered followed by lower weekly
doses. The intermittent dosing schedules require dose-averaging over time periods as long as

2	weeks, which introduces uncertainty in the effective exposures. In other words, the high unit
dose may be more of a factor in eliciting the effect than the average TCDD tissue levels over
time. Although the loading/maintenance dose protocols are designed to maintain a constant
internal exposure, these protocols are somewhat inconsistent with the constant daily TCDD
dietary exposures associated with human ingestion patterns.

The epidemiologic studies conducted in the Seveso cohort represent exposures over
different life stages including gestation, childhood, and young adulthood. The Seveso exposure
profile is essentially a high initial pulse TCDD exposure followed by a 20-30 year period of
elimination. Effects are realized, or measured, 10-20 years following the initial exposure; the
critical exposure window for susceptibility varies with effect and is often unknown. Therefore,
the effective exposure profiles for the Seveso cohort studies vary considerably. For the
Mocarelli et al. (2008, 199595) and Alaluusua et al. (2004, 197142) studies where early
childhood exposures proximate to the initial event are associated with the outcomes, there is
some uncertainty as to the magnitude of the effective doses. Although the effects are associated

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with TCDD exposure in the first 10 years of life, it is not clear to what extent the initial peak
exposure is primarily responsible for the effects. It is also not clear if averaging exposure over
the critical window is appropriate given the large difference between initial TCDD body burden
and body burden at the end of the critical exposure window. The LOAELs for both Mocarelli
et al. (2008, 199595) and Alaluusua et al. (2004, 197142) are calculated as the average of the
peak exposure and average exposure across the critical exposure window (see Section 4.2 for
details).

For the gestational exposure study (Baccarelli et al., 2008, 197059). the critical exposure
window is strictly defined and relatively short (9 months) and occurs long after the initial
exposure (15-20 years). In addition, the maternal serum TCDD concentrations were measured
10-15 years after the initial exposure and are proximate to the actual pregnancies; consequently,
there is less uncertainty in the kinetic extrapolation between time of measurement and time of
birth (i.e., the critical exposure window). The narrow critical exposure window at a much later
time than the initial exposure (where the TCDD elimination curve is flattening) is assumed to
lead to a relatively steady-state exposure over the critical time period with much less uncertainty
in the magnitude of the effective dose. With the exception of Eskenazi et al. (2002, 197168) (see
Section 4.2), the effective doses for other effects reported for the Seveso cohort (see
Section 2.4.1.1.1.4) have not been quantified and are not represented in Table 4-5 because no
critical exposure windows can be identified or individual exposure estimates were not reported.

4.3.3. Uncertainty Factors (UFs)

The UF column in Table 4-5 shows the composite (total) UF that would be applied to the
POD for each endpoint. For the animal bioassays, a UF of 3 for the toxicodynamic component
of the interspecies extrapolation factor (UFA) was applied to all PODs. For both animal and
human studies, when a NOAEL was used as the POD, a factor of 10 was applied for human
interindividual variability (UFH). For all of the animal bioassay endpoints lacking a NOAEL, a
UF of 10 for the LOAEL-to-NOAEL UF (UFL) was included. For the human LOAELs, a UFL of
3 was applied because sensitive populations were identified. A sub chronic-to-chronic UF (UFS)
of 1 and a database factor (UFD) of 1 are applied to all endpoints. A rationale for each UF is
provided for the derivation of the RfD below.

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4.3.4. Choice of Human Studies for RfD Derivation

For selection of the POD, the human studies are given the highest consideration, as
quality human data are always preferred by the EPA to animal data of comparable quality. The
human studies included in Table 4-5 (Alaluusua et al., 2004, 197142; Baccarelli et al., 2008,

	59; Mocarelli et al., 2008, 199595) each evaluate a segment of the Seveso civilian

population (i.e., not an occupational cohort) exposed directly to TCDD released from an
industrial accident. (The identification of PODs from these studies is detailed in
Sections 4.3.4.1, 4.3.4.2, and 4.3.4.3.) Thus, exposures were primarily to TCDD, the chemical of
concern, with apparently minimal DLC exposures beyond those associated with background
intake,28 making these studies highly appropriate for use in RfD derivation for TCDD. In
addition, health effects associated with TCDD exposures were observed in humans, the species
of concern whose health protection is represented by the RfD, eliminating the uncertainty
associated with interspecies extrapolation. The cohort members who were evaluated included
infants (exposed in utero) and adults who were exposed when they were less than 10 years of
age. These studies considered together associate TCDD exposures with health effects in
potentially vulnerable population subgroups. Their inclusion among the RfDs derived also may
characterize noncancer health effects associated with TCDD exposures in potentially vulnerable
populations, thus accounting for some part of the intraspecies uncertainty in the RfD. Finally,
the two virtually identical RfDs from different endpoints in different studies provide an
additional level of confidence in the use of these data for derivation the RfD for TCDD.

Although the human data are preferred, Table 4-5 presents a number of animal studies
with RfDs that are lower than the human RfDs. To a large extent, this is expected because a
10-fold interspecies uncertainty factor is generally used to extrapolate from test-animal species to
humans, intended to provide a conservative estimate of an RfD that would be derived directly
from human data. Two of the rat bioassays among this group of studies—Bell et al. (2007,
197041; RfD = 1.4E-9 mg/kg day based on delay in the onset of puberty) and NTP (2006,

05; RfD = 4.6E-10 mg/kg day based on liver and lung lesions)—are of particular note.

Both studies were recently conducted. Both were very well designed and conducted, using 30 or

28As an example, note the lack of statistically significant effects reported by Baccarelli et al. (2008, 197059; Figure 2
C and D) in regression models based on either maternal plasma levels of noncoplaner PCBs or total TEQ on
neonatal TSH levels.

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more animals per dose group (see Table 4-6 for a discussion of these studies' strengths and
weaknesses); both also are consistent with and, in part, have helped to define the current state of
practice in the field. Bell et al. (2007, 197041) evaluated several reproductive and
developmental endpoints, initiating TCDD exposures well before mating and continuing through
gestation. NTP (2006, 197605) is the most comprehensive evaluation of TCDD chronic toxicity
in rodents to date, evaluating dozens of endpoints at several time points in all major tissues.

Thus, proximity of the RfDs derived from these two high quality, recent studies provide
additional support for the use of the human data for RfD derivation.

There are several animal bioassay candidate RfDs at the lower end of the RfD range in
Table 4-5 that are more than 10-fold below the human-based RfDs. Two of these studies report
effects that are analogous to the endpoints reported in the three human studies and support the
RfDs based on human data. Specifically, decreased sperm production in Latchoumydandane and
Mathur (2002, 197498) is consistent with the decreased sperm counts and other sperm effects in
Baccarelli et al. (2008, 197059). and missing molars in Keller et al. (2007, 198526; 2008,

198531; 2008, 198033) are similar to the dental defects seen in Alaluusua et al. (2004, 197142).
Thus, because these endpoints have been associated with TCDD exposures in humans, these
animal studies would not be selected for RfD derivation in preference to human data showing the
same effects.

Another characteristic of the remaining studies in the lower end of the candidate RfD
distribution is that they are dominated by mouse studies (comprising 6 of the 8 lowest
rodent-based RfDs). EPA considers the candidate RfD estimates based on mouse data to be
much more uncertain than either the rat or human candidate RfD estimates. The EPA considers
the Emond mouse PBPK model to be the most uncertain of toxicokinetic models used to estimate
the PODs because of the lack of key mouse-specific data, particularly for the gestational
component (see Section 3.3.4.3.2.5). The LOAELreds identified in mouse bioassays are low
primarily because of the large toxicokinetic interspecies extrapolation factors used for mice, for
which there is more potential for error. The ratio of administered dose to HED (Da:HED) ranges
from 65 to 1,227 depending on the duration of exposure. The Da:HED for mice is, on average,
about four times larger than that used for rats. In addition, each one of the mouse studies has
other qualitative limitations and uncertainties (discussed above and in Table 4-6) that make them
less desirable candidates as the basis for the RfD than the human studies.

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4.3.4.1. Identification of POD from Baccarelli et al. (2008, 197059)

Baccarelli et al. (2008, 197059) reported increased levels of TSH in newborns exposed to
TCDD in utero, indicating a possible dysregulation of thyroid hormone metabolism. The study
authors related TCDD concentrations in neonatal blood to TSH levels, reporting group mean
TCDD concentrations associated with TSH levels above or below 5 |i-Units TSH per mL of
serum (5 |iU/mL).

The World Health Organization (WHO, 1994) established the 5 |iU/mL standard as an
indicator of potential iodine deficiency and potential thyroid problems in neonates. Increased
TSH levels are indicative of decreased thyroid hormone (T4 and/or T3) levels. The 5 |iU/mL
"cutoff for TSH measurements in neonates was recommended by WHO (1994) for use in
population surveillance programs as an indicator of iodine deficiency disease (IDD). In
explaining this recommendation, WHO (1994) stated that:

"While further study of iodine replete populations is needed, a cutoff of 5|iU/ml whole
blood... may be appropriate for epidemiological studies of IDD [iodine deficiency
disease.] Populations with a substantial number of newborns with TSH levels above the
cutoff could indicate a significant IDD problem."

For TCDD, the toxicological concern is not likely to be iodine uptake inhibition, but
rather increased metabolism and clearance of T4, as evidenced in a number of animal studies
(e.g., Seo et al., 1995, 197869). Clinically, a TSH level of >4 |iU/mL in a pregnant woman is
followed up by an assessment of free T4, and treatment with L-thyroxine is prescribed if
T4 levels are low (Glinoer and Delange, 2000). This is to ensure a sufficient supply of T4 for the
fetus, which relies on maternal T4 exclusively during the 1st half of pregnancy (Chan et al., 2005;
(Calvo et al., 2002, 051690; Morreale et al., 2000, 019231).

Adequate levels of thyroid hormone also are essential in the newborn and young infant as
this is a period of active brain development (Glinoer and Delange, 2000; Zoeller and Rovet,
2004). Smaller reserves, higher demand, and shorter half-life of thyroid hormones in newborns
and young infants also could make this population more susceptible to the impact of insufficient
levels of T4 (Savin et al., 2003(Greer et al., 2002, 051202; Van Den et al., 1999, 016478).

Thyroid hormone disruption during pregnancy and in the neonatal period can lead to
neurological deficiencies. However, the exact relationship between TSH increases and adverse

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neurodevelopmental outcome is not well defined. A TSH level above 20 [jU/L in a newborn
infant is cause for immediate intervention to prevent mental retardation, often caused by a
malformed or ectopic thyroid gland in the newborn (Glinoer and Delange, 2000; Rovet, 2002;
WHO, 2007). Recent epidemiological data indicate concern for even lower level thyroid
hormone perturbations during pregnancy. For example, Haddow et al. (1999, 002176) reported
that women with subclinical hypothyroidism, with a mean TSH of 13.2 [j,U/L had children with
IQ deficits of up to 4 IQ points on the Wechsler IQ scale. Neonatal TSH within the first
72 hours of birth (as was evaluated by Baccarelli et al., 2008, 197059)is a sensitive indicator of
both neonatal and maternal thyroid status (DeLange et al., 1983). Animal models have recently
indicated that very modest perturbations in thyroid status for even a relatively short period of
time can lead to altered brain development (e.g., Auso et al., 2004; Lavado-Autric et al., 2003;
Sharlin et al., 2008, 2010; Royland et al., 2008).

Baccarelli et al. (2008, 197059) discount iodine status in the population as a confounder,
as exposed and referent populations all lived in a relatively small geographical area. It is
unlikely that there was iodine deficiency in one population and not in the other population based
on iodine levels in the soil.

Baccarelli et al. (2008, 197059) also showed, in graphical form, how the TSH distribution
in each of three categorical exposure groups (reference, zone A, and zone B—representing
increasing TCDD exposure) shifted to higher TSH values with increasing exposure. The
individuals comprising the above 5 |iU/mL group were from all three categorical exposure
groups, not just from the highest exposure group. Therefore, EPA was able to designate a
LOAEL independently of the nominal categorical exposure groups; the LOAEL is designated as
the group mean of 39 ppt TCDD in neonatal plasma as a LOAEL for TSH values above
5 |iU/mL. Using the Emond human PBPK model, the daily oral intake at the LOAEL is
estimated to be 0.024 ng/kg-day (see Section 4.2.3.1). ANOAEL is not defined because it is not
clear what maternal intake should be assigned to the group below 5 |iU/mL.

4.3.4.2. Identification of POD from Mocarelli et al. (2008,199595)

Mocarelli et al. (2008, 199595) reported decreased sperm concentrations (20%) and
decreased motile sperm counts (11%) in men who were 1-9 years old in 1976 at the time of the
Seveso accident (initial TCDD exposure event). The sperm concentrations and motile sperm

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counts in men who were 10-17 years old in 1976 were not affected. Serum (LASC) TCDD
levels were measured within one year of the initial exposure. Serum TCDD levels and
corresponding responses were reported by quartile, with a reference group of less-exposed
individuals assigned a TCDD LASC value of 15 ppt (which was the mean of the TCDD LASC
reported in individuals outside the contaminated area). The lowest exposed group mean was
68 ppt (lsl-quartile). Mean sperm concentrations and motile sperm counts were reduced about
20% from the reference group. Further decrease in these values in the groups exposed to more
than 68 ppt was slight and reached a maximum of about 33%.

Although a decrease in sperm concentration of 20% likely would not have clinical
significance for an individual EPA's concern with the reported decreases in sperm concentration
and total number of motile sperm (relative to the comparison group) is that such decreases
associated with TCDD exposures could lead to shifts in the distributions of these measures in the
general population. Such shifts could result in decreased fertility in men at the low end of these
population distributions. While there is no clear cut-off indicating male fertility problems for
either of these measured effects. A sperm concentration of 20 million/ml is typically used as a
cut-off by clinicians to indicate follow-up for potential reproductive impact in affected
individuals. Low sperm counts are typically accompanied by poor sperm quality (morphology
and motility). For fertile men, between 50% and 60% of sperm are motile (Swan et al., 2003;
Slama et al., 2002; Wijchman et al., 2001). Any impacts on these reported levels could become
functionally significant.

For the 22-31 year-old men exposed to TCDD as a consequence of the Seveso accident,
the mean total sperm concentration was reported by Mocarelli et al. (2008, 199595) to be
53.6 million/ml, with a value of 21.8 million/ml at one standard deviation below the mean. In
the comparison group that consisted of men not exposed to TCDD by the Seveso explosion and
of the same age as the exposed men, the mean total sperm concentration was 72.5 million/ml
(31.7 million/ml at one standard deviation below the mean). In the group exposed due to the
Seveso accident, individuals one standard deviation below the mean are just above the cut-off
used by clinicians, indicating a that a number of individuals in the exposed group likely had
sperm concentrations less than 20 million/ml; EPA could not obtain the individual data to
determine the exact number of men in this category. EPA judged that the impact on sperm

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concentration and quality reported by Mocarelli et al. (2008, 199595) is biologically significant
given the potential for functional impairment.

EPA has designated the lowest exposure group (68 ppt) as a LOAEL, which translates to
a continuous daily oral intake of 0.020 ng/kg-day (see Section 4.2.3.2). The reference group is
not designated as a NOAEL because there is no clear zero-exposure measurement for any of
these endpoints, particularly considering the contribution of background exposure to DLCs,
which further complicates the interpretation of the reference group response as a true "control"
response (see discussion in Section 4.4). However, males less than 10 years old can be
designated as a sensitive population by comparison to older males who were not affected.

4.3.4.3. Identification of POD from Alaluusua et al (2004,197142)

Alaluusua et al. (2004, 197142) reported dental effects in male and female adults who
were less than 9.5 years of age, but not older, at the time of the initial exposure (1976) in Seveso.
EPA used the same approach to estimate daily TCDD intake as was used for the Mocarelli et al.
(2008, 199595) data; a window of susceptibility of about 5 years was established. Serum
measurements for this cohort were taken within a year of the accident. Serum TCDD levels and
corresponding responses were reported by tertile, with a reference group of less-exposed
individuals assigned a TCDD LASC value of 15 ppt (ng/kg); the tertile group means were 130,
383, and 1,830 ppt. Both a NOAEL and LOAEL can be defined for this study. The NOAEL is
0.12 ng/kg-day, corresponding to the TCDD LASC of 130 ppt at the first tertile. The LOAEL is
0.93 ng/kg-day at the second tertile. The children in this cohort less than 5 years old can be
designated as a sensitive population by comparison to older individuals who were not affected
relative to the reference group.

4.3.5. Derivation of the RfD

The two human studies, Baccarelli et al. (2008, 197059) and Mocarelli et al. (2008,
199595), have similar LOAELs of 0.024 and 0.020 ng/kg-day, respectively. Together, these
two studies constitute the best foundation for establishing a POD for the RfD, and are designated
as coprincipal studies. Therefore, increased TSH in neonates in Baccarelli et al. (2008, 197059)
and male reproductive effects (decreased sperm count and motility) in Mocarelli et al. (2008,
199595) are designated as cocritical effects. Although the exposure estimate used in

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determination of the LOAEL for Mocarelli et al. (2008, 199595) is more uncertain than the
Baccarelli et al. (2008, 197059) exposure estimate, the slightly lower LOAEL of
0.020 ng/kg-day from Mocarelli et al. is designated as the POD. A composite UF of 30 is
applied to account for lack of a NOAEL (UFL =10) and human interindividual variability
(UFh = 3); the resulting RfD in standard units is 7 x 10~10 mg/kg-day. Table 4-7 presents the
details of the RfD derivation.

4.4. UNCERTAINTY IN THE RfD

Exposure assessment is a key limitation of the epidemiologic studies (of the Seveso
cohort) used to derive the RfD. The Seveso cohort exposure profile consists of an initial high
dose followed by a drop in body burden to background levels over a period of about 20 years, at
which time the effects were observed. This exposure scenario is a mismatch with the constant
daily intake scenario addressed by the RfD methodology. The determination of an effective
average daily dose from the Seveso exposure scenario requires an understanding of the critical
time-window of susceptibility and the influence of the peak exposure on the occurrence of the
observed effects, particularly when the peak exposure is high relative to the average exposure
over the critical exposure window. For one of the principal studies (Mocaelli et al., 2008,
199595), a maximum susceptibility exposure window can be identified based on the age of the
population at risk. However, the influence of the peak exposure on the effects observed 20 years
later is unknown and the biological significance of averaging the exposure over several years,
with internal exposure measures spanning a 4.5-fold range, is unknown. EPA, in this
assessment, has averaged intermittent exposures for rodent bioassays over weekly dosing
intervals, but the peak and average body burdens varied by less than 50%. EPA has not
developed guidance for larger-interval averaging. Furthermore, because there is an assumption
of a threshold level of exposure below which the effects are not expected to occur, averaging
over large intervals could include below-threshold exposures. The process used by EPA to
estimate the LOAEL exposure for the Mocarelli study is a compromise between the extremes; as
such, there is some uncertainty in the estimate, perhaps in the range of 3- to 10-fold in either
direction. This uncertainty also holds for the LOAEL determined for the dental effects reported
in Alaluusua et al. (2004, 197142) and the increased menstrual cycle length reported in Eskenazi
et al. (2002, ^ > see Section 4.2.3.4); in both of those studies, the uncertainty is greater, as

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the difference between peak and average internal exposures is an order of magnitude or more.
The LOAEL for increased TSH in neonates (Baccarelli et al., 2008, 197059). however, is less
uncertain because the critical exposure window is much narrower (9 months) and the
developmental exposures occurred 10 to 15 years after the initial exposure, when internal TCDD
concentrations for the pregnant women likely were leveling off; that is, exposure over the critical
window was more constant and estimation of the relevant exposures was less uncertain.

However, there is some uncertainty in the magnitude of the exposures because they were
estimated from measurements in sera taken several years prior to pregnancy.

Another source of uncertainty using human epidemiologic data is the lack of completely
unexposed populations. The available TCDD epidemiologic data were obtained by comparing
populations that experienced elevated TCDD exposures to populations that experienced lower
exposures, rather than to a population with no TCDD exposure. An additional complicating
factor is coexposure to DLCs, which can behave in the same way as TCDD. Although the
accidental exposure to the Seveso women's cohort was primarily to TCDD, background
exposure was largely to DLCs.29 Eskenazi et al. (2004, 197160) reported that TCDD comprised
only 20% of the total toxicity equivalence (TEQ) in the serum of the reference group that was
not exposed as a result of the factory explosion, which implies that the effective background
TEQ exposure was approximately 5-fold higher.

The higher background exposure could be significant at the lower TCDD exposure levels,
with the effect diminishing as TCDD exposure increased. For dose-response modeling, the
effect of a higher background dose (i.e., total TEQ), if included, would be to shift the response
curve to the right (responses associated with higher exposures) but, primarily, would reduce the
spread of the exposures, which would tend to alter the shape of the dose response towards
sublinear. Both the right shift and the more sublinear shape would result in higher EDX
estimates, such as BMDs and BMDLs, from fitting dose-response models. However, for
determination of a LOAEL, which is the case for all the human studies in Table 4-5, the impact
may be minimal, as the LOAEL depends only on establishing that an effect of sufficient

29Moccarelli (2001, 197002) reported the release from the Seveso plant to contain a mixture of TCDD. ethylene
glycol and sodium hydroxide. As these chemicals are not thought to persist in the environment or in the body,
coexposure to these additional contaminants along with TCDD would not have a significant impact on longer-term
TCDD dose-response. For acute exposure, male reproductive or thyroid hormone effects are not evident for
ethylene glycol (U.S. EPA. 2009, 1921961. It is unlikely that sodium hydroxide, being primarily a caustic agent,
would cause these effects.

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magnitude was observed at some TCDD exposure level. In this case, the effect of the increased
effective background exposure would be to inflate the "control" (zero-TEQ) response, providing
the threshold for the response had been exceeded. The potential impact of an inflated control
response would be to mask a significant effect of the added TCDD exposure, when the latter
effect is determined by comparison to the reference group response. To compensate for this,
EPA has been somewhat conservative in interpreting the magnitude of responses defining
LOAELs for the Seveso cohort studies. The actual magnitude of the impact of the DLC
background exposure is impossible to assess without knowing the true (TEQ-free) background
response.

A primary strength of the TCDD database is that analogous effects have been observed in
animal bioassays for most of the human endpoints, increasing the overall confidence in the
relevance to humans of the effects reported in rodents and the association of TCDD exposure
with the effects reported in humans. Table 4-5 shows that low dose TCDD exposures are
associated with a wide array of toxicological endpoints in rodents including developmental
effects, reproductive effects, immunotoxicity and chronic toxicity. Effects reported in human
studies are similar, including male reproductive effects, increased TSH in neonates and dental
defects in children; other human health effects such as female reproductive effects and chloracne
have been observed at higher exposures (see Section 2.4.1). Other effects reported in rodent
studies such as liver toxicity and overt immunological endpoints have not been reported in
human studies. However, with respect to immunological effects, Baccarelli et al. (2002, 197062;
2004, 197045) evaluated immunoglobin and complement levels in the sera of TCDD-exposed
individuals from the Seveso cohort and found slightly reduced immunoglobulin in the highest
exposure groups but no effect on other immunoglobulins or on C3 or C4 complement levels.
The latter finding indicates that at least one immunological measure in humans is not a sensitive
endpoint, as it is for mice, with large reductions in serum complement at low exposure levels
(White et al., 1986, 197531s).

Although there is a substantial amount of qualitative concordance of effects between
rodents and humans, quantitative concordance is not evident in Table 4-5. The differential
sensitivity of mice and humans for the serum complement endpoint is one example. Other
examples of differential sensitivity are developmental dental effects and thyroid hormonal
dysregulation. Developmental dental defects are relatively sensitive effects in rodents, appearing

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at exposure levels in mice (Keller et al., 2007, 198526; Keller et al., 2008, 198531; Keller et al.,
2008, 198033) more than an order of magnitude lower than effect levels in humans (Alaluusua et
al., 2004, 197142). In contrast, thyroid hormone effects are seen in rats (Crofton et al., 2005,
197381) at 30-fold higher exposures than for humans (Baccarelli et al., 2008, 197059). Male
reproductive effects (sperm production) occur in rats (Latchoumycandane and Mathur, 2002,
197498) and humans (Mocaelli et al., 2008, 199595) at about the same dose. To what extent
these differential sensitivities depend on specifics of the comparison, such as species (mouse vs.
rat), life-stage (e.g., fetal vs. adult), endpoint measure (e.g., thyroxine [T4] vs. TSH) or
magnitude of the lowest dose tested, cannot be determined, so strong conclusions about
quantitative concordance cannot be made.

A number of qualitative strengths and limitations/uncertainties are associated with the top
animal bioassays listed in Table 4-5, as articulated in Table 4-6. Considering the issue of lowest
tested dose, the general lack of NOAELs and acceptable BMDLs is a primary weakness of the
rodent bioassay database. None of the 6 most sensitive rodent studies in Table 4-5, spanning a
30-fold range of LOAELs, had defined NOAELs or BMDLs. NOAELs or BMDLs were
established for only 4 of the next 10 rodent studies. In addition, many of these LOAELs are
characterized by relatively high responses with respect to the control population, so it is not
certain that a 10-fold lower dose (based on the application of UFL of 10) would be approximately
equivalent to a NOAEL. A major reason for the failure of BMD modeling was that the responses
were not "anchored" at the low end (i.e., first response levels were far from the BMR [see
Table 4-4]). Another major problem with the animal bioassay data was nonmonotone and flat
response profiles. The small dose-group sizes and large dose intervals probably contributed to
many of these response characteristics that prevented successful BMD modeling. Larger study
sizes with narrower dose intervals at lower doses are still needed to clarify rodent response to
TCDD.

Lower TCDD doses have been tested in rodents but almost entirely for investigation of
specialized biochemical endpoints30 that EPA does not consider to be adverse health effects (see
Appendix G). There is, however, a fundamental limit to the lowest dose of TCDD that can be
tested meaningfully, as TCDD is present in feed stock and accumulates in unexposed animals
prior to the start of any study. This issue is illustrated by the presence of TCDD in tissues of

30Enzyme induction, oxidative stress indicators, mRNA levels, etc.

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1	unexposed control animals, often at significant levels relative to the lowest tested dose in low

2	dose studies (Bell et al., 2007, 197041; Ohsako et al., 2001, 198497) (Vanden Heuvel et al.,

3	1994, 594318. see Text Box 4-1). Some DLCs also have been measured in animal feeds and are

4	anticipated to accumulate in unexposed test animals further complicating the interpretation of

5	low dose studies.

6

Text Box 4-1. Background levels of TCDD in Control Group Animals

TCDD tissue levels in control animals are rarely reported either explicitly or implicitly. Vanden Heuvel et al.
(1994, 197551). however, reported TCDD concentrations in livers of control animals (10-week-old female
Sprague-Dawley rats) of 0.43 ppt (ng/kg) compared to 0.49 ppt in the livers of animals given a single oral TCDD dose
of 0.1 ng/kg. Assuming proportionality of liver concentration to total body burden, the body burden of untreated
animals was 87.8% of that of treated animals. The equivalent administered dose for untreated animals (do) can be
calculated as equal to 0.878 x (0.1 + do), assuming proportionality of body burden to administered dose and that all
animals started with the same TCDD body burdens. The calculation yields a value of 0.72 ng/kg for d0, which
represents the accumulated TCDD from all sources in these animals prior to being put on and during test. This value
would raise the nominal 0.1 ng/kg TCDD dose 8-fold to 0.82 ng/kg. The next higher dose of 1 ng/kg would be nearly
doubled to 1.72 ng/kg. The impact on higher doses would be negligible, because the ratio of treatment dose to
apparent background exposure levels increases with higher treatment levels. Bell et al. (2007, 197041) reported
slightly higher levels (0.66 ppt) in the livers of slightly older untreated pregnant female Sprague-Dawley rats (mated at
16-18 weeks of age and tested 17 days later).

Ohsako et al. (2001, 198497) reported TCDD concentrations in the fat of offspring of untreated pregnant
Holtzman rats that were 46% of the TCDD fat concentrations in animals exposed in utero to 12.5 ng/kg (single
exposure on GD 15). This level of TCDD would imply a very large background exposure, but quantitation based on
simple kinetic assumptions probably would not reflect the more complicated indirect exposure scenario

Bell et al. (2007, 197041) also reported concentrations of 0.1 and 0.6 ppt TCDD measured in two samples of feed
stock. Assuming that the average of 0.35 ppt is representative of the entire supply of feed stock and a food
consumption factor of 10% of body weight per day, the average daily oral exposure from feed to these animals would
be 0.035 ng/kg. Discrimination of outcomes from longer-term repeated exposures might be problematic at exposure
levels around 0.1 ng/kg-day. Background exposure was not much of an issue for Bell et al. (2007, 197041). as the
lowest TCDD exposure level was 2.4 ng/kg-day (28-day dietary exposure).

NTP (2006, 543749) reported TCDD concentrations in the liver and fat of untreated female S-D rats after 2 years
on test that were 1% and 2.5% of the levels in the liver and fat of the low-dose TCDD treatment group
(2.14 ng/kg-day; (NTP, 2006, 197605)). respectively. Assuming proportionality of fat concentration and oral intake,
control animal exposure would have been approximately 0.05 ng/kg-day, similar to the estimate from Bell et al. (2007,
197041). As for the latter study, background intake for the NTP (2006, 197605) study animals would not have a large
effect on the dose-response assessment given the lowest exposure level of 2.14 ng/kg-day.

In all of these studies, except the 28-day exposure in Bell et al. (2007, 197041). control animals were gavaged
with corn oil vehicle. TCDD concentrations in corn oil were not reported in any of the studies.

7

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1	Table 4-1. POD candidates for epidemiologic studies of TCDD

2

Study

POD (ng/kg-day)

Critical effects

Alaluusua et al. (2004,

197142)

1.2E-0T (NOAEL)

Dental effects in adults exposed to TCDD in childhood

Baccarelli et al. (2008,

197059)

2.4E-02b (LOAEL)

Elevated TSH in neonates

Eskenazi et al. (2002,
1 )

1.64E+00C (LOAEL

Increased length of menstrual cycle in women exposed
to TCDD in childhood

Mocarelli et al. (2008,

199595)

2.0E-02d (LOAEL)

Decreased sperm count and motility in men exposed to
TCDD in childhood

3

4	aMean of peak exposure (0.15 ng/kg-day) and average exposure over 10-year critical window (0.0093 ng/kg-day).

5	bMaternal exposure corresponding to neonatal TSH concentration exceeding 5 |iU/mL.

6	°Mean of peak exposure (3.2 ng/kg-day) and average exposure over 10-year critical window (0.12 ng/kg-day).

7	dMean of peak exposure (0.035 ng/kg-day) and average exposure over 10-year critical window (0.0078 ng/kg-day).

8

9	Table 4-2. Models run for each study/endpoint combination in the animal

10	bioassay benchmark dose modeling

11

Model

Restrictions imposed

Continuous models

Exponential M2-M5,
not grouped

Adverse direction specified according to the response data; power > 1

Hill

Adverse direction is automatic; n> 1

Linear

Adverse direction is automatic; degree of polynomial = 1

Polynomial

Adverse direction is automatic; degree of polynomial unrestricted; restrict the
sign of the power to nonnegative or nonpositive, depending on the direction of
the responses

Power

Adverse direction is automatic; power >1

Dichotomous models

Gamma

Power >1

Logistic

None

Log-Logistic

Slope >1

Log-Probit

None

Multistage

Beta >0, 2nd degree polynomial

Probit

None

Weibull

Power >1

12

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Table 4-3. Summary of key animal study PODs (ng/kg-day) based on three different dose metrics: administered
dose, first-order body burden HED, and blood concentration



Study

Endpoint

Administered dose"

lst-order body burden HEDb

Blood concentration HEDC

NOAEL

LOAEL

BMDLd

NOAEL

LOAEL

BMDLd

NOAEL

LOAEL

BMDLd

Amin et al. (2000,
197169s)

Saccharin preference ratio,
female

—

2.50E+01

5.10E+01

—

2.49E-02

5.08E-02

—

1.71E-01

3.20E-01

Bell et al. (2007,
197041)

Balano-preputial separation
in male pups

—

2.40E+00

2.87E+00

—

1.26E-02

1.50E-02

—

8.83E-02

4.33E-02

Cantoni et al. (1981,

197092s)

Urinary coproporhyrins

—

1.43E+00

1.25E-01

—

1.24E-02

1.09E-03

—

6.51E-02

1.60E-03

Chu et al. (2001,

521829s)

Tissue weight changes

2.50E+02

1.00E+03

—

7.55E-01

3.02E+00

—

—

—

—

Chu et al., 2007

Liver lesions

2.50E+00

2.50E+01

-

7.55E-03

7.55E-02

-

3.56E-02

5.76E-01

-

Crofton et al. (2005,

197381s)

Serum T4

3.00E+01

1.00E+02

3.01E+01

1.92E-02

6.40E-02

1.92E-02

1.72E-01

7.61E-01

1.40E-01

Croutch et al. (2005,

197382s)

Decreased body weight

5.43E+01

2.17E+02

—

2.22E-01

8.89E-01

—

—

—

—

DeCaprio et al.
(1986. 197403s)

Decreased body weight

6.10E-01

4.90E+00

—

4.11E-03

3.30E-02

—

—

—

—

Fattore et al. (2000,
197446s)

Decreased hepatic retinol

-

2.00E+01

-

-

1.23E-01

-

-

8.01E-01

-

Fox et al. (1993,

197344s)

Increased liver weight

5.70E-01

3.27E+02

-

1.42E-03

8.12E-01

-

-

-

-

Franc et al. (2001,

197353s)

Organ weight changes

1.00E+01

3.00E+01

1.59E+00

6.62E-02

1.99E-01

1.05E-02

4.60E-01

1.45E+00

3.37E-02

Franczak et al. (2006,

197354s)

Abnormal estrous cycle

-

7.14E+00

-

-

5.95E-02

-

-

3.25E-01

-

Hojo et al. (2002,

198785s)

DRL response per min

—

2.00E+01

2.70E-01

—

5.26E-03

7.11E-05

—

5.50E-02

7.37E-05

Hutt et al. (2008,

198268s)

Embyrotoxicity

—

7.14E+00

—

—

4.67E-02

—

—

2.57E-01

—


-------
Table 4-3. Summary of key animal study PODs (ng/kg-day) based on three different dose metrics: administered
dose, lst-order body burden HED and blood concentration HED (continued)



Study

Endpoint

Administered dose"

lst-order body burden HEDb

Blood concentration HEDC

NOAEL

LOAEL

BMDLd

NOAEL

LOAEL

BMDLd

NOAEL

LOAEL

BMDLd

Ikeda et al. (2005,

197834s)

Sex ratio

—

1.65E+01

—

—

1.05E-01

—

—

2.75E+00

—

Ishihara et al. (2007,

197677)

Sex ratio

1.00E-01

1.00E+02

-

3.18E-04

3.18E-01

-

-

-

-

Kattainen et al.
(2001. 198952s)

3rd molar length

-

3.00E+01

2.14E+00

-

7.89E-03

5.64E-04

-

8.99E-02

1.71E-03

Keller et al. (2007,
198526: 2008.
198531:2008.

198033s)

Missing mandibular molars



1.00E+01

1.88E+01



2.58E-03

4.85E-03



9.81E-03

1.70E-02

Kociba et al. (1976,

198594s)

Liver and hematologic
effects and body weight
changes

7.14E+00

7.14E+01



4.53E-02

4.53E-01



2.68E-01

3.10E+00



Kociba et al. (1978,

001818s)

Liver and lung lesions,
increased urinary
porphyrins

1.00E+00

1.00E+01

7.30E-01

1.07E-02

1.07E-01

7.84E-03

6.46E-02

6.46E-01

2.00E-02

Latchoumycandane
and Mathur (2002,

197498s)

Sperm production



1.00E+00

1.56E-02



3.87E-03

6.03E-05



1.67E-02

3.83E-05

Li et al. (1997,

199060s)

Increased serum FSH

3.00E+00

1.00E+01

3.60E+03

7.89E-04

2.63E-03

9.47E-01

2.97E-03

1.72E-02

2.38E+01

Li et al. (2006,

199059s)

Hormone levels (serum
estradiol)

-

2.00E+00

1.08E+02

-

9.85E-04

5.33E-02

-

1.57E-03

3.46E-01

Markowski et al.
C2001. 197442s)

FR2 revolutions

-

2.00E+01

7.34E+00

-

6.25E-03

2.29E-03

-

5.14E-02

1.18E-02

Maronpot et al.
(1993. 198386s)

Increased relative liver
weight

1.07E+01

3.50E+01

-

8.97E-02

2.93E-01

—

—

—

—


-------
Table 4-3. Summary of key animal study PODs (ng/kg-day) based on three different dose metrics: administered
dose, lst-order body burden HED and blood concentration HED (continued)



Study

Endpoint

Administered dose"

lst-order body burden HEDb

Blood concentration HEDC

NOAEL

LOAEL

BMDLd

NOAEL

LOAEL

BMDLd

NOAEL

LOAEL

BMDLd

Miettinen et al.
(2006. 198266)

Cariogenic lesions in pups

—

3.00E+01

1.05E+01

—

7.89E-03

2.77E-03

—

8.93E-02

9.32E-03

Murray et al. (1979,

197983s)

Fertility index in f2
generation

1.00E+00

1.00E+01

1.63E+00

9.43E-03

9.43E-02

1.54E-02

2.96E-02

3.88E-01

4.05E-02

NTP (1982. 200870s)

Liver lesions

-

1.39E+00

4.68E+00

-

6.47E-03

2.18E-02

-

2.21E-02

5.20E-02

NTP (2006. 197605s)

Liver and lung lesions

-

2.14E+00

5.04E-01

-

2.34E-02

5.50E-03

-

1.39E-01

7.38E-03

Nohara et al. (2000,

200027s)

Decreased spleen
cellularity

8.00E+02

-

-

2.10E-01

-

-

5.34E+00

-

-

Ohsako et al. (2001,

198497s)

Anogenital distance in
pups

1.25E+01

5.00E+01

9.75E+00

3.29E-03

1.32E-02

2.57E-03

2.75E-02

1.78E-01

1.84E-02

Seo et al. (1995,

197869s)

Decreased thymus weight

2.50E+01

1.00E+02

-

2.49E-02

9.96E-02

-

1.67E-01

9.15E-01

-

Sewall et al. (1995,

198145s)

Serum T4

1.07E+01

3.50E+01

5.16E+00

8.97E-02

2.93E-01

4.33E-02

5.15E-01

1.76E+00

1.84E-01

Shi et al. (2007,

198147s)

Serum estradiol in female
pups

1.43E-01

7.14E-01

2.24E-01

1.23E-03

6.13E-03

1.92E-03

4.71E-03

2.75E-02

4.95E-03

Simanainen et al.
C2002. 201369s)

Decreased serum T4

1.00E+02

3.00E+02

-

2.63E-02

7.89E-02

-

-

-

-

Simanainen et al.
(2003. 198582s)

Decreased thymus weight
and change in EROD
activity

1.00E+02

3.00E+02



2.63E-02

7.89E-02









Simanainen et al.
(2004. 198948s)

Decreased daily sperm
production

1.00E+02

3.00E+02

-

2.63E-02

7.89E-02

-

-

-

-

Smialowicz et al.
(2004. 198948s)

Decreased antibody
response to SRBCs

3.00E+02

1.00E+03

-

7.73E-02

2.58E-01

-

-

-

-

Smialowicz et al.
(2008. 198341s)

PFC per 10A6 cells

—

1.07E+00

4.09E-01

—

5.00E-03

1.91E-03

—

6.38E-03

2.00E-03


-------
Table 4-3. Summary of key animal study PODs (ng/kg-day) based on three different dose metrics: administered
dose, lst-order body burden HED and blood concentration HED (continued)

S?
>!

cs
st

5

>!
Si

st

*3

o
>!

>!

o

Si

§•
>!

. o

rs
o

>!

Study

Endpoint

Administered dose"

lst-order body burden HEDb

Blood concentration HEDC

NOAEL

LOAEL

BMDLd

NOAEL

LOAEL

BMDLd

NOAEL

LOAEL

BMDLd

Tothetal. (1979,

197109s)

Skin lesions

—

1.00E+00

2.15E+02

—

3.70E-03

7.94E-01

—

1.00E-02

2.18E-01

VanBirgelen et al.
(1995. 198052s)

Decreased liver retinyl
palmitate

-

1.40E+01

9.89E+02

-

8.63E-02

6.09E+00

-

5.25E-01

5.00E+00

Vosetal. (1973,

198367s)

Decreased delayed-type
hypersensitivity response
to tuberculin

1.14E+00

5.71E+00



6.43E-03

3.22E-02









White etal. (1986,

197531s)

Decreased serum
complement

-

1.00E+01

3.59E+01

-

2.23E-02

7.98E-02

-

2.83E-02

4.65E-02

Yang et al. (2000,

198590s)

Increased endometrial
implant survival

1.79E+01

—

—

6.74E-01

—

—

—

—

—

U>
-J

o
o

2!

H S.
W K-

oy

o

c
o

H
W

s

aAverage administered daily dose over the experimental exposure period.
bHED based on lst-orderbody burden model described in Section 3.2.4.4.

°HED based on Emond rodent and human PBPK models described in Section 3.3.6.

dBMR = 0.1 for quantal endpoints and 1 standard deviation control mean for continuous endpoints, except for body and organ weights, where BMR = 10%
relative deviation from control mean.

- = value not established or not modeled.


-------
Table 4-4. TCDD BMDL analysis (NOAEL, LOAEL, BMD, and BMDL values given as animal whole blood
concentrations in ng/kg)a



Study

NOAEL/
LOAEL

Endpoint

Control
response

First
responseb

Max
response0

Model fit detail

BMD/
BMDL

Comments

Amin et al.
(2000. 197169)
(rat)

3.38E+00

Saccharin
consumed, female,
(0.25%) (n = 10)



22% |
(0.3 SD)

66% |

Continuous linear,
nonconstant variance
(p = 0.55)

9.15E+00
6.09E+00

BMDL > LOAEL; restricted power
model, constrained parameter hit
lower bound













Continuous power,
nonconstant variance,
unrestricted
(p = NA)

8.37E+00
3.42E+00

Saturated model; supralinear fit
(power = 0.74)





Saccharin
consumed, female
(0.50%) (n = 10)



49% |
(0.7 SD)

80% |

Continuous linear,
nonconstant variance
(p = 0.06)

1.02E+01
6.57E+00

Restricted power model, constrained
parameter hit lower bound













Continuous power,
nonconstant variance,
unrestricted
(p = NA)

6.57E+00
1.15E+00

Saturated model; supralinear fit
(power = 0.40)





Saccharin preference
ratio, female
(0.25%)

(n = 10)



29% |
(1.8 SD)

33% |

Continuous linear,
nonconstant variance
(p = 0.002)

1.16E+01
5.57E+00

BMDL > LOAEL; no response near
BMR; near maximal response at
LOAEL





Saccharin preference
ratio, female
(0.50%)

(n = 10)



39% |
(1.1 SD)

54% |

Continuous linear,
constant variance
(p = 0.14)

8.14E+00
5.11E+00

BMDL > LOAEL; near maximal
response at LOAEL; restricted power
model, constrained parameter hit
lower bound













Continuous power,
constant variance,
unrestricted
(p = NA)

2.60E+00
1.06E-14

Saturated model; supralinear fit
(power = 0.28)


-------
Table 4-4. TCDD BMDL analysis (NOAEL, LOAEL, BMD, and BMDL values given as animal whole blood
concentrations in ng/kga) (continued)



Study

NOAEL/
LOAEL

Endpoint

Control
response

First
response

Max
response

Model fit detail

BMD/
BMDL

Comments

Bell et al.
(2007. 197041)
(rat)

2.20E+00

Balano-preputial
separation in male
pups

(n = 30 [dams])

1/30

5/30

15/30

Dichotomous log-
logistic, restricted
(p = 0.78)

2.25E+00
1.39E+00

Adequate fit; constrained parameter
bound hit; not litter based; selected

Dichotomous log-
logistic, unrestricted
(p = 0.50)

2.00E+00
2.80E-01

Supralinear fit
(slope = 0.93); selected

Cantoni et al.
(1981. 197092)
(rat)

1.85E+00

Urinary uroporhyrins
(n = 4)



2.4-fold t
(5.7 SD)

87-fold t

Continuous
exponential (M2),
nonconstant variance
(p = 0.0003)

3.76E+00
2.76E+00

No response near BMR; poor fits for
all nonconstant variance models;
constant variance poor representation
of control SD; BMDL > LOAEL

Urinary
coproporhyrins
(n = 4)



2.4-fold t
(3.1 SD)

4.0-fold t

Continuous
exponential (M4),
nonconstant variance
(p = 0.49)

5.34E-01
1.80E-01

No response near BMR

Continuous power,
nonconstant variance,
unrestricted
(p = 0.61)

2.77E-02
2.03E-05

Supralinear fit (n = 0.30); poor
model choice for plateau effect

Crofton et al.
(2005. 197381)
(rat)

3.46E+00
9.26E+00

Serum T4,
(n = 4-14)



29% |
(1.9 SD)

51% |

Continuous
exponential (M4),
constant variance
(p = 0.94)

5.19E+00
3.03E+00

No response near BMR


-------
Table 4-4. TCDD BMDL analysis (NOAEL, LOAEL, BMD, and BMDL values given as animal whole blood
concentrations in ng/kga) (continued)



Study

NOAEL/
LOAEL

Endpoint

Control
response

First
response

Max
response

Model fit detail

BMD/
BMDL

Comments

Franc et al.
(2001. 197353)
(rat)

6.58E+00
1.45E+01

S-D Rats, Relative
Liver Weight



8.1% t
(0.58 SD)

55% t

Continuous power,
constant variance
(p = 0.84)

9.47E+00
4.59E+00

Acceptable fit





L-E Rats, Relative
Liver Weight



6.3% t
(0.63 SD)

22% t

Continuous Hill,
nonconstant variance,
restricted
(p = 0.83)

7.72E+00
1.22E+00

Constrained parameter hit lower
bound; otherwise acceptable fit;
selected













Continuous Hill,
nonconstant variance,
unrestricted

(p = N/A)

7.22E+00
1.15E+00

Supralinear fit (power = 0.55)





S-D Rats, Relative
Thymus Weight



9.0% |
(0.11 SD)

77% 4

Continuous
exponential (M4),
nonconstant variance
(p = 0.72)

1.88E+00
9.22E-01

Poor fit for responses in controls and
lowest exposure group













Continuous
polynomial,
nonconstant variance
(p = 0.40)

4.78E+00
3.89E+00

Acceptable fit





L-E Rats, Relative
Thymus Weight



7.7% |
(0.15 SD)

66% 4

Continuous
exponential (M4),
constant variance
(p = 0.23)

2.08E+00
5.93E-01

Poor fit for responses in controls and
lowest exposure group; dose-
response relationship not significant





H/W Rats, Relative
Thymus Weight



3.7% |
(0.10 SD)

51% 4

Continuous
exponential (M2),
constant variance
(p = 0.70)

5.09E+00
3.13E+00




-------
Table 4-4. TCDD BMDL analysis (NOAEL, LOAEL, BMD, and BMDL values given as animal whole blood
concentrations in ng/kga) (continued)



Study

NOAEL/
LOAEL

Endpoint

Control
response

First
response

Max
response

Model fit detail

BMD/
BMDL

Comments

Hojo et al.
(2002. 198785)
(rat)

1.62E+00

DRL reinforce per
min

(n = 12)



55% t
(1.0 SD)

80% t

Continuous
exponential (M4),
constant variance
(p = 0.054)

1.32E+00
2.37E-03

Poor fit; near maximal response at
lowest dose, BMD/BMDL ratio »100





DRL response per
min

(n = 12)



105% 4
(2.4 SD)

105% |

Continuous
exponential (M4),
constant variance
(p = 0.48)

3.81E-01
1.55E-02

No response data near BMR;
maximal response at lowest dose,
BMD/BMDL ratio »20

Kattainen et al.
(2001. 198952s)
(rat)

2.23E+00

3rd molar length in
pups

(n = 4-8)



15% 4
(4.2 SD)

27% |

Continuous Hill,
nonconstant variance,
restricted
(p = 0.02)

3.13E-01
1.68E-01

No response data near BMR;
Constrained parameter lower bound
hit













Continuous Hill,
nonconstant variance,
unrestricted
(p < 0.001)

1.21E-02

BMDL could not be calculated





3rd molar eruption in
pups

(n = 4-8)

1/16

3/17

13/19

Dichotomous log-
logistic, restricted
(p = 0.98)

2.40E+00
1.33E+00

Constrained parameter lower bound
hit













Dichotomous log-
logistic, unrestricted
(p = 0.95)

1.93E+00
1.84E-01

Supralinear fit (slope = 0.91)

Keller et al.
(2007.198526:
2008.198531;
2008.198033)
(mouse)

5.37E-01

Missing molars
(n = 23-36)

0/29

2/23

30/30

Dichotomous 1°
multistage
(p = 0.26)

1.09E+00
7.62E-01

Poor fit at first response level; not
most sensitive endpoint; other
endpoints not amenable to BMD
modeling


-------
Table 4-4. TCDD BMDL analysis (NOAEL, LOAEL, BMD, and BMDL values given as animal whole blood
concentrations in ng/kga) (continued)



Study

NOAEL/
LOAEL

Endpoint

Control
response

First
response

Max
response

Model fit detail

BMD/
BMDL

Comments

Kociba et al.
(1978. (HHSI8)
(rat)

1.55E+00
7.15E+00

Uroporphyrin per
creatinine, females
(» = 5)



15% t
(0.48 SD)

89% t

Continuous linear,
constant variance
(p = 0.79)

1.31E+01
9.29E+00

BMDL > LOAEL; otherwise
adequate fit





Urinary

coproporphyria,

females

(» = 5)



67% t
(5.1 SD)

78% t

Continuous
exponential (M4),
nonconstant variance
(p = 0.01)

1.57E+00
7.18E-01

Poor fit; no response near BMR





Liver lesions
(n = 50)











No data presented





Lung lesions
(n = 50)











No data presented

Latchoumy-
candane and
Mathur (2002,
197498)

7.85E-01

Daily sperm
production

(n = 6)



29% |
(1.0 SD)

41% |

Continuous Hill,
constant variance,
restricted
(p = 0.96)

1.17E-01
1.32E-02

Near maximal response at LOAEL;
constrained parameter bound hit;
standard deviations given in paper
interpreted as standard errors

(rat)











Continuous Hill,
constant variance,
unrestricted

(p = N/A)

9.96E-02
1.23E-09

Slightly supralinear fit (n = 0.92)

Li et al. (1997,
19906(1)

(rat)

2.66E-01
7.99E-01

FSH in female rats
(n = 10)



3.6-fold t
(2.0 SD)

19-fold t

Continuous power,
nonconstant variance,
restricted
(/?<0.01)

2.00E+02
1.36E+02

Power hit lower bound













Continuous power,
nonconstant variance,
unrestricted
(p = 0.003)

1.96E-01
2.48E-02

supralinear fit (power =0.31)


-------
Table 4-4. TCDD BMDL analysis (NOAEL, LOAEL, BMD, and BMDL values given as animal whole blood
concentrations in ng/kga) (continued)



Study

NOAEL/
LOAEL

Endpoint

Control
response

First
response

Max
response

Model fit detail

BMD/
BMDL

Comments

Li et al. (2006,

199059)

(mouse)

1.59E-01

Serum estradiol
(n = 10)



2.0-fold t
(0.8 SD)

2.4-fold t

Continuous linear,
constant variance
(p = 0.16)

1.61E+01
5.38E+00

BMDL > LOAEL; high control CV
(1.25); near maximal response at low
dose; nonmonotonic response; other
model fits are step-function-like





Serum progesterone
(n = 10)



33% |
(2.0 SD)

61% 4

Continuous Hill,
nonconstant variance
(p = 0.39)

9.46E-04
8.01E-11

No response data near BMR; large
CVs (>1) for treatment groups; poor
fit for variance model; Hill
coefficient at lower bound (step-
function)

Markowski et
al. (2001,
197442)

1.56E+00

FR5 run
opportunities

(n = 4-7)



10% |
(0.21 SD)

51% 4

Continuous Hill,
constant variance
(p = 0.94)

1.72E+00
9.08E-01

Constrained parameter upper bound
hit

(rat)











Continuous power,
constant variance,
unrestricted
(p = 0.13)

2.67E+00
1.03E-14

Saturated model; supralinear fit
(power =0.39); BMD/BMDL ratio
»100





FR2 revolutions
(n = 4-7)



9% I
(0.15 SD)

43% 4

Continuous Hill,
constant variance
(p = 0.65)

1.84E+00
5.99E-01

Constrained parameter bound hit
(upper bound)













Continuous power,
constant variance,
unrestricted
(p = 0.16)

5.74E+00
1.03E-14

Supralinear fit (power =0.32)





FR10 run
opportunities

(n = 4-7)



15% 4
(0.24 SD)

57% 4

Continuous
exponential (M2),
constant variance
(p = 0.30)

8.57E+00
2.89E+00

BMDL > LOAEL


-------
Table 4-4. TCDD BMDL analysis (NOAEL, LOAEL, BMD, and BMDL values given as animal whole blood
concentrations in ng/kga) (continued)



Study

NOAEL/
LOAEL

Endpoint

Control
response

First
response

Max
response

Model fit detail

BMD/
BMDL

Comments

Miettinen et al.
(2006. 198266s)
(rat)

2.22E+00

Cariogenic lesions
in pups
(n = 4-8)

25/42

23/29

29/32

Dichotomous log-
logistic, restricted
(p = 0.60)

1.43E+00
5.17E-01

Constrained parameter lower bound
hit; near maximal response at
LOAEL; high control response













Dichotomous log-
logistic, unrestricted
(p = 0.73)

4.94E-02

Supralinear fit (slope = 0.47); BMDL
could not be calculated

Murray et al.
(1979. 197983)
(rat)

1.12E+00
5.88E+00

Fertility in f2 gen.
(no litters)
(n = 20)

4/32

0/20

9/20

Dichotomous
multistage
(p = 0.08)

2.73E+00
1.37E+00

Poor fit; nonmonotonic response; no
response data near BMR

NTP (1982,

200870)

(mouse)

7.67E-01

Toxic hepatitis;

males

(n = 50)

1/73

5/49

44/50

Dichotomous
multistage
(p = 0.04)

2.78E+00
1.34E+00

No acceptable model fits; lowest
BMDL shown

NTP (2006,

197605)

(rat)

2.56E+00

Hepatocyte
hypertrophy
(n = 53-54)

0/53

19/54

52/53

Dichotomous
multistage
(p = 0.02)

9.27E-01
7.91E-01

Poor fits for all models





Alveolar metaplasia
(n = 52-54)

2/53

19/54

46/52

Dichotomous log-

logistic

(P = 0.72)

6.50E-01
3.75E-01

No response near BMR





Oval cell hyperplasia
(n = 53-54)

0/53

4/54

53/53

Dichotomous probit
(p = 0.23)

5.67E+00
4.79E+00

Relatively poor fit for control and
low dose groups; negative response
intercept (same for logistic); BMDL
> LOAEL













Dichotomous Weibull
(p = 0.08)

5.72E+00
4.09E+00

Marginal fit; BMDL > LOAEL


-------
Table 4-4. TCDD BMDL analysis (NOAEL, LOAEL, BMD, and BMDL values given as animal whole blood
concentrations in ng/kga) (continued)



Study

NOAEL/
LOAEL

Endpoint

Control
response

First
response

Max
response

Model fit detail

BMD/
BMDL

Comments

NTP (2006,

197605)

(rat)

2.56E+00
(continued)

Gingival hyperplasia
(n = 53-54)

1/53

7/54

16/53

Dichotomous log-
logistic, restricted
(p = 0.06)

5.85E+00
3.73E+00

Poor fit; constrained parameter bound
hit; BMDL > LOAEL

(continued)











Dichotomous log-
logistic, unrestricted
(p = 0.66)

7.05E-01
1.26E-05

Supralinear fit (slope = 0.37)





Eosinophilic focus,
multiple

(n = 53-54)

3/53

8/54

42/53

Dichotomous probit
(p = 0.46)

5.58E+00
4.86E+00

Relatively poor fit to control
response; BMDL > LOAEL





Liver fatty change,

diffuse

(n = 53-54)

0/53

2/54

48/53

Dichotomous Weibull
(P = 0.72)

3.92E+00
2.86E+00

BMDL > LOAEL; otherwise
adequate fit





Liver necrosis
(n = 53-54)

1/53

4/54

17/53

Dichotomous log-
probit, unrestricted
(p = 0.80)

7.50E+00
3.50E+00

Adequate fit; slightly supralinear;
BMDL > LOAEL





Liver pigmentation
(n = 53-54)

4/53

9/54

53/53

Dichotomous log-
probit
(p = 0.96)

2.46E+00
1.89E+00

Adequate fit





Toxic hepatopathy
(n = 53-54)

0/53

2/54

53/53

Dichotomous
multistage
(p = 0.69)

3.98E+00
3.06E+00

BMDL > LOAEL; otherwise
adequate fit

Ohsako et al.
(2001, 198497)
(rat)

1.04E+00
3.47E+00

Ano-genital distance
in male pups
(» = 5)



12% |
(1.0 SD)

17% |

Continuous Hill,
constant variance,
restricted
(p = 0.15)

2.88E+00
8.03E-01

Constrained parameter lower bound
hit; near maximal response at
LOAEL













Continuous Hill,
constant variance,
unrestricted
(p = 0.056)

3.49E+00
3.05E-01

Supralinear fit (n = 0.59)


-------
Table 4-4. TCDD BMDL analysis (NOAEL, LOAEL, BMD, and BMDL values given as animal whole blood
concentrations in ng/kga) (continued)



Study

NOAEL/
LOAEL

Endpoint

Control
response

First
response

Max
response

Model fit detail

BMD/
BMDL

Comments

Sewall et al.
(1995. 198145)
(rat)

7.11E+00
1.66E+01

Serum T4

(n = 9)



9.1% |
(0.6 SD)

40% |

Continuous Hill,
constant variance,
restricted
(p = 0.90)

1.03E+01
3.60E+00

Constrained parameter hit lower
bound; otherwise acceptable fit;
selected







Continuous Hill,
constant variance,
unrestricted
(p = 0.86)

9.71E+00
1.97E+00

Supralinear fit (power = 0.57)

Shi et al. (2007,

19X147)

(rat)

3.42E-01
1.07E+00

Serum estradiol in
female pups
(n = 10)



38% |
(0.4 SD)

62% |

Continuous
exponential (M4),
nonconstant variance
(p = 0.69)

8.07E-01
3.54E-01

Adequate fit; selected

Smialowicz et
al. (2008,

198341)
(mouse)

4.38E-01

PFC per spleen
(n = 15)



24% |
(0.5 SD)

89% |

Continuous power,
unrestricted,
nonconstant variance
(P = 0.27)

1.19E+01
3.76E+00

BMDL > LOAEL; fit at control and
low dose inconsistent with data;
constrained parameters in other
models hit lower bounds

PFC per 10A6 cells
(« = 8-15)



24% |
(0.5 SD)

9.3-fold |

Continuous power
unrestricted, constant
variance
(p = 0.48)

1.90E+00
2.16E-01

Constant variance test failed;
observed control variance
underestimated by 35%; poor fits for
all nonconstant variance models

Toth et al.
(1979. 197109)
(mouse)

5.73E-01

Skin lesions
(n = 38-44)

0/38

5/44

25/43

Dichotomous log-
logistic, restricted
(p = 0.08)

6.41E+00
4.02E+00

Constrained parameter lower bound
hit

Dichotomous
log-logistic,
unrestricted
(p = 0.74)

5.97E-01
6.77E-02

Supralinear fit (slope = 0.48)


-------
Table 4-4. TCDD BMDL analysis (NOAEL, LOAEL, BMD, and BMDL values given as animal whole blood
concentrations in ng/kga) (continued)



Study

NOAEL/
LOAEL

Endpoint

Control
response

First
response

Max
response

Model fit detail

BMD/
BMDL

Comments

Toth et al.
(1979. 197109)
(mouse)

5.73E-01
(cont.)

Dermal amyloidosis
(n = 38-44)

0/38

5/44

17/43

Dichotomous log-
logistic, restricted
(p = 0.05)

1.50E+01
8.75E+00

Poor fit; constrained parameter lower
bound hit; BMDL > LOAEL

(continued)











Dichotomous log-
logistic, unrestricted
(p = 0.90)

4.84E-01
5.31E-03

Supralinear fit (slope = 0.33)

Van Birgelen et
al. (1995,
19X052)

(rat)

7.20E+00

Hepatitic retinol
(» = 8)



44% |
(0.74 SD)

96% |

Continuous
exponential (M4),
nonconstant variance
(/?<0.01)

2.49E+01
3.36E+00

Poor fit













Continuous power,
nonconstant variance,
unrestricted
(p = 0.01)

3.80E-01
1.39E-02

Poor fit; supralinear fit
(power = 0.14)





Hepatitic retinyl
palmitate (n = 8)



80% |
(1.4 SD)

99% |

Continuous
exponential (M4),
nonconstant variance
(/?<0.01)

1.42E+02
3.65E+01

Poor fit; no response near BMR













Continuous power,
nonconstant variance,
unrestricted
(p = 0.24)

5.26E-02
5.89E-05

Supralinear fit (power = 0.06)


-------
Table 4-4. TCDD BMDL analysis (NOAEL, LOAEL, BMD, and BMDL values given as animal whole blood
concentrations in ng/kga) (continued)

Study

NOAEL/
LOAEL

Endpoint

Control
response

First
response

Max
response

Model fit detail

BMD/
BMDL

Comments

White et al.
(1986. 197531)
(mouse)

1.09E+00

Total hemolytic
complement activity
(CH50)

(» = 8)



41% |
(2.6 SD)

81% |

Continuous
Hill, nonconstant
variance, restricted
(p = 0.002)

8.63E+00
1.50E+00

Poor fit; no response near BMR;
constrained parameter bound hit;
BMDL > LOAEL

Continuous Hill,
nonconstant variance,
unrestricted
(p = 0.07)

1.48E-01
4.35E-03

Supralinear fit (n = 0.25)

aAnimal whole blood concentrations were used to determine the HEDs in Table 4-5.

bMagnitude of response at first dose where response differs from control value (in the adverse direction); continuous response magnitudes given as relative to
control plus change relative to control standard deviation; quantal response given as number affected/total number.

°Magnitude of response maximally differing from control value (in the adverse direction).

S-D = Sprague-Dawley.

SD = standard deviation.


-------
Table 4-5. Candidate points of departure for the TCDD RfD using blood-concentration-based human
equivalent doses



Study

Species, strain
(sex, if not
both)

Protocol

Endpoint

NOAELhed(N) or
BMDLhed (B)
(ng/kg-day)

LOAELhed
(ng/kg-day)

UFa

RfD

(mg/kg-day)

Li et al. (2006,

199059s)

Mouse, NIH (F)

Gavage GD 1-3;
n = 10

Hormone levels in pregnant dams (decreased
progesterone, increased estradiol)

-

1.6E-03

300

5.2E-12

Smialowicz et
al. (2008,
198341)

Mouse, B6C3F1
(F)

90-day gavage;
n = 8-15

Decreased SRBC response



6.4E-03

300

2.1E-11

Keller et al.
(2007. 198526;
2008. 198531;
2008. 198033V3

Mouse, CBA/J
and C3H/HeJ

Gavage GD 13;
n = 23-36 (pups)

Missing molars, mandibular shape changes in
pups



9.8E-03

300

3.3E-11

Toth et al.
(1979. 197109s)

Mouse, Swiss/
H/Riop (M)

1-year gavage;
n = 38-44

Dermal amyloidosis, skin lesions

—

1.0E-02

300

3.3E-11

Latchoumy-
candane and
Mathur (2002,

197498s)

Rat, Wistar (M)

45-day oral
pipetting;

n = 6

Decreased sperm production



1.7E-02

300

5.6E-11

NTP (1982,

200870s)

Mouse, B6C3F1
(M)

2-year gavage;
n = 50

Liver lesions

-

2.2E-02

300

7.4E-11

White et al.
(1986. 197531s)

Mouse, B6C3F1
(F)

14-day gavage;
n = 6-8

Decreased serum complement

-

2.8E-02

300

9.4E-11

Li et al. (1997,

199060s)

Rat, S-D
(F, 22 day-old)

Single gavage;
n= 10

Increased serum FSH

3.0E-03 (N)

1.7E-02

o

o

9.9E-11

DeCaprio et al.
(1986. 197403s)

Guinea pig,
Hartley

90-day dietary;
n = 10

Decreased body weight, organ weight
changes (liver, kidney, thymus, brain)

4.1E-03d(N)

3.3E-02d

o

o

1.4E-10

Shi et al. (2007,

198147s)

Rat, S-D (F)

11-month gavage;
n = 10

Decreased serum estradiol

4.7E-03 (N)
5.0E-03 (B)

2.8E-02

o

o

1.6E-10

Markowski et
al. (2001,

197442)

Rat, Holtzman

Gavage GD 18;
n = 4-7

Neurobehavioral effects in pups (running,
lever press, wheel spinning)



5.1E-02

300

1.7E-10


-------
Table 4-5. Candidate points of departure for the TCDD RfD using blood-concentration-based human
equivalent doses (continued)



Study

Species, strain
(sex, if not
both)

Protocol

Endpoint

NOAELhed(N) or
BMDLhed (B)
(ng/kg-day)

LOAELhed
(ng/kg-day)

UFa

RfD

(mg/kg-day)

Hojo et al.
<2002. 198785')

Rat, S-D

Gavage GD 8;
n = 12

Food-reinforced operant behavior in pups

—

5.5E-02

300

1.8E-10

Vos et al.
(1973. 198367s)

Guinea pig,
Hartley (F)

8-week gavage;
n = 10

Decreased delayed-type hypersensitivity
response to tuberculin

6.4E-03d (N)

3.2E-02d

o

o

2.1E-10

Cantoni et al.
(1981. 197092s)

Rat, CD-COBS
(F)

45-week gavage;
n = 4

Increased urinary porhyrins

-

6.5E-02

300

2.2E-10

Miettinen et al.
(2006. 198266)

Rat, Line C

Gavage GD 15;
n =3-10

Cariogenic lesions in pups

—

8.9E-02

300

3.0E-10

Kattainen et al.
(2001. 198952)

Rat, Line C

Gavage GD 15;
n = 4-8

Inhibited molar development in pups

—

9.0E-02

300

3.0E-10

NTP (2006,

197605s)

Rat, S-D (F)

2-year gavage;
n =53

Liver and lung lesions

-

1.4E-01

300

4.6E-10

Amin et al.
C2000. 197169s)

Rat, S-D

Gavage GD 10-16;
n = 10

Reduced saccharin consumption and
preference

-

1.7E-01

300

5.7E-10

Mocarelli et al.
(2008.199595s)

Human (M)

Childhood

exposure; n = 157

Decreased sperm concentration and sperm
motility, as adults

—

2.0E-02e

30f

6.7E-10

Baccarelli et
al. (2008,

197059s)

Human infants

Gestational
exposure; n = 51

Increased TSH in newborn infants



2.4E-028

30f

8.2E-10

Hutt et al.
(2008. 198268s)

Rat, S-D (F)

13-week dietary;

n = 3

Embryotoxicity

—

2.6E+00

300

8.6E-10

Ohsako et al.
(2001. 198497s)

Rat, Holtzman

Gavage GD 15;
n = 5

Decreased ano-genital distance in male pups

2.8E-02 (N)

1.8E-01

o

o

9.2E-10

Murray et al.
(1979. 197983s)

Rat, S-D

3-generation dietary

Reduced fertility and neonatal survival (f 0
and f 1)

3.0E-02 (N)

3.9E-01

o

o

9.9E-10


-------
Table 4-5. Candidate points of departure for the TCDD RfD using blood-concentration-based human
equivalent doses (continued)

Study

Species, strain
(sex, if not
both)

Protocol

Endpoint

NOAELhed(N) or
BMDLhed (B)
(ng/kg-day)

LOAELm.|)

(ng/kg-day)

UFa

RfD

(mg/kg-day)

Franc et al.
(2001. 197353s)

Rat, Long-Evans
(F)

22-week gavage;
n = 8

Increased Relative Liver Weight; decreased
relative thymus weight

4.6E-01 (N)
3.4E-02 (B)

1.45E+00

o

o

1.1E-09

Chu et al., 2007

Rat, S-D (F)

28-day gavage,
n = 5

Liver lesions

3.6E-02 (N)

5.8E-01

o

o

1.2E-09

Bell et al.
(2007. 197041)

Rat, CRL:WI
(Han) (M)

17-week dietary;
n = 30

Delay in onset of puberty

4.3E-02 (B)

8.8E-02

o

o

1.4E-09

Van Birgelen et
al. (1995,

198052)

Rat, S-D (F)

13-week dietary;
n = 8

Decreased liver retinyl palmitate



5.3E-01

300

1.8E-09

Kociba et al.
(1978. 001818)

Rat, S-D (F)

2-year dietary;
n = 50

Liver and lung lesions, increased urinary
porhyrins

6.5E-02 (N)

6.5E-01

o

o

2.2E-09

Fattore et al.,
(2000. 197446)

Rat, S-D

13-week dietary;

n = 6

Decreased hepatic retinol

—

8.0E-01

300

2.7E-09

Seo et al. (1995,

197869)

Rat, S-D

Gavage GD 10-16;
n = 10

Decreased serum T4 and thymus weight

1.7E-01 (N)

9.1E-01

o

o

5.6E-09

Crofton et al.
(2005. 197381)

Rat, Long-Evans
(F)

4-day gavage;
n = 4-14

Decreased serum T4

1.7E-01 (N)

7.6E-01

o

o

5.7E-09

Sewall et al.
(1995. 198145)

Rat, S-D (F)

30-week gavage;
n = 9

Decreased serum T4

5.2E-01 (N)
1.8E-01 (B)

1.8E+00

o

o

6.1E-09

Alaluusua et al.
(2004. 197142)

Human

Childhood exposure;
n = 48

Dental defects

1.2E-0111 (N)

9.3E-011

3J

3.9E-08

O

c
o

H
ffl

aExcept where indicated, UFA = 3 (for dynamics), UFH = 10, UFL = 10.
bResults from 3 separate studies with identical designs combined.
cUFl = 1 (NOAEL or BMDL).

dHED determined from lst-orderbody burden model; no PBPK model available for guinea pigs.
e Mean of peak exposure (0.0319 ng/kg-day) and average exposure over 10-year critical window (0.00802 ng/kg-day).

fUFH = 3, UFl = 10.

gMaternal exposure corresponding to neonatal TSH concentration exceeding 5 |iU/mL.


-------
Table 4-5. Candidate points of departure for the TCDD RfD using blood-concentration-based human
equivalent doses (continued)

hMean of peak exposure (0.200 ng/kg-day) and average exposure over 10-year critical window (0.0335 ng/kg-day).

'Mean of peak exposure (1.71 ng/kg-day) and average exposure over 10-year critical window (0.153 ng/kg-day).

jUFh = 3.

S-D = Sprague-Dawley.


-------
Table 4-6. Qualitative analysis of the strengths and limitations/uncertainties associated with animal bioassays
possessing candidate points-of-departure for the TCDD RfD

Study

Strengths

Limitations

Remarks

Bell et al. (2007,

197041s)

•	Large sample size of both rat dams and
offspring/dose employed

•	Several developmental effects tested

•	Batch-to-batch variation of up to 30% in TCDD
concentration in the diet

•	Longer-term dosing of dams does not accurately
define gestational period when fetus is especially
sensitive to TCDD-induced toxicity

Study is a significant addition
to a substantial database on the
developmental toxicity of
TCDD in laboratory animals

Cantoni et al.
(1981. 197092s)

• Experiments were designed to test qualitative
and quantitative composition and the course of
urinary excretion in TCDD-induced porphyria

•	Small sample size of rats/dose employed (n = 4)

•	Concurrent histological changes with tissue
porphyrin levels were not examined

•	TCDD used for dosing was of unknown purity

Early study on porphyrogenic
effects of TCDD

DeCaprio et al.
(1986. 197403s)

•	Subchronic oral dosing duration up to 90 days.

•	Male and female guinea pigs tested

•	Relatively small sample size of guinea pigs/dose
employed (n= 10)

•	No histopathological analyses performed

•	TCDD used for dosing was of unknown purity

Limited subchronic study;
PBPK model not available for
estimation of HED

Franc et al.
(2001. 197353s)

•	Three different rat strains with varying
sensitivities to TCDD were utilized (Sprague-
Dawley, Long Evans, Han/Wistar)

•	Longer-term oral dosing up to 22 weeks

•	Relatively small sample size of rats/dose employed
(n = 8)

•	Only female rats were tested

•	Concurrent liver histopathological changes with
liver weight changes were not examined

•	Gavage exposure was only biweekly

Limited subchronic study

Hojo et al. (2002,

198785s)

•	Low TCDD dose levels used allowed for subtle
behavioral deficits to be identified in rat
offspring

•	Preliminary training sessions in operant
chamber apparatuses were extensive

•	Neurobehavioral effects are exposure-related
and cannot be attributed to presence of learning
or discrimination deficits

•	Relatively small sample size of rat dams/dose
employed (n= 12)

•	Small sample size of rat offspring/dose evaluated
(n = 5-6)

•	Neurobehavioral effects induced by TCDD at earlier
or later gestational dosing dates are unknown
because of single gavage administration on GD 8

•	Although BMD analysis was conducted, the model
parameters were not constrained according to EPA
guidance, so the results cannot be used

One of a few neurobehavioral
toxicity studies; somewhat
limited study size


-------
Table 4-6. Qualitative analysis of the strengths and limitations/uncertainties associated with animal bioassays
possessing candidate points-of-departure for the TCDD RfD (continued)

Study

Strengths

Limitations

Remarks

Keller et al.
(2007. 198526;
2008. 198531;
2008. 198033s)

•	Six different inbred mouse strains were utilized

•	Large sample size of mouse
offspring/dose/strain evaluated

•	Low TCDD dose levels used compared to
typical mouse studies allowed for identification
of subtle sensitivity differences in presence of
absence of third molars, variant molar
morphology, and mandible structure in offspring

•	Unknown sample size of mouse dams/dose/strain
employed

•	All inbred strains possessed sensitive b allele at the
Ahr locus (i.e., a potentially resistant subpopulation
was not evaluated for comparison purposes)

•	Morphological dental and mandibular changes
induced by TCDD at earlier or later gestational
dosing dates are unknown because of single gavage
administration on GD 13

•	Difficulties breeding A/J mice led to abandonment
of that strain in the analysis (Keller et al., 2008a, b)

Endpoint similar to effects
observed at higher exposure
levels in humans; HED highly
uncertain using mouse PBPK
model

Latchoumy-
candane and
Mathur (2002,

197498s)

• Compared to epididymal sperm counts, the
testicular spermatid head count provides better
quantitation of acute changes in sperm
production and can indicate pathology

•	Small sample size of rats/dose employed (n = 6)

•	Oral pipette administration of TCDD may be a less
efficient dosing method than gavage

Endpoint has human relevance,
similar to critical effects in
principal human study for RfD

Li et al. (2006,

199059s)

• Female reproductive effects (i.e., early embryo
loss and changes in serum progesterone and
estradiol) were tested at multiple exposure
times—early gestation, preimplantation, and
peri- to postimplantation

•	Small sample size of dams/dose (n = 10)

•	Large dose-spacing interval (25-fold at lowest
2 doses)

Endpoint has human relevance
but HED highly uncertain
using mouse PBPK model

Markowski et al.
(2001. 197442s)

•	Low TCDD dose levels used allowed for subtle
behavioral deficits to be identified in rat
offspring

•	Several training sessions on wheel apparatuses
were extensive

•	Neurobehavioral effects are exposure-related
and cannot be attributed to motor or sensory
deficits

•	Unknown sample size of rat dams/dose employed.

•	Small sample size of rat offspring/dose evaluated
(n = 4-7)

•	TCDD used for dosing was of unknown purity and
origin

•	Only 2 treatment levels

•	Neurobehavioral effects induced by TCDD at earlier
or later gestational dosing dates are unknown
because of single gavage administration on GD 18

One of a few neurobehavioral
toxicity studies; somewhat
limited study size


-------
Table 4-6. Qualitative analysis of the strengths and limitations/uncertainties associated with animal bioassays
possessing candidate points-of-departure for the TCDD RfD (continued)

Study

Strengths

Limitations

Remarks

NTP (1982,

200870s)

•	Large sample size of mice and rats/dose
employed

•	Comprehensive 2-year bioassay that assessed
body weights, clinical signs, and pathological
changes in multiple tissues and organs

•	Elevated background levels of hepatocellular tumors
in untreated male mice

•	Gavage exposure was only 2 days/week

•	Only 2 treatment levels

Comprehensive chronic
toxicity evaluations of TCDD
in rodents; HED highly
uncertain using mouse PBPK
model

NTP (2006,

197605s)

•	Chronic exposure duration with several interim
sacrifices

•	Large number of dose groups with close spacing

•	Large number of animals per dose group

•	Comprehensive suite of endpoints evaluated

•	Comprehensive biochemical, clinical and
histopathological tests and measures

•	Detailed reporting of results, with individual
animal data presented as well as group
summaries

•	Single species, strain and sex

•	Lowest dose tested too high for establishing
NO A F.I.

Study is the most
comprehensive chronic TCDD
toxicity evaluation in rats to
date

Shi et al. (2007,

198147s)

•	Study design evaluated TCDD effects on aging
female reproductive system (i.e., exposure
began in utero and spanned across reproductive
lifespan)

•	Several female reproductive endpoints were
evaluated, including cyclicity, endocrinology,
serum hormone levels, and follicular reserves

• Relatively small sample size of rats/dose employed
(n = 10)

Endpoint similar to effects
observed at higher exposure
levels in humans

Smialowicz et al.
(2008. 19834D

• Sheep red blood cell (SRBC) plaque forming
cell assay is highly sensitive and reproducible
across laboratories when examining TCDD

•	Small sample size of animals/dose (n = 8)

•	Only female mice were tested

•	Thymus and spleen weights were only other
immune response-related endpoints tested

Limited immunotoxicity study

Toth et al. (1979,

197109s)

•	Large sample size of mice/dose employed

•	Chronic exposure duration

•	Reporting of findings is terse and lacks sufficient
detail (e.g., materials and methods, thorough
description of pathological findings, etc.)

•	Limited number of endpoints examined

•	Only male mice were tested

Limited chronic study; HED
highly uncertain using mouse
PBPK model


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Table 4-6. Qualitative analysis of the strengths and limitations/uncertainties associated with animal bioassays
possessing candidate points-of-departure for the TCDD RfD (continued)

Study

Strengths

Limitations

Remarks

Vosetal. (1973,

198367s)

•	Three different animal species tested (guinea
pigs, mice, and rats)

•	Effects of TCDD tested on both cell-mediated
and humoral immunity

•	Small sample size of animals/dose employed in each
experiment (n = 5-10)

•	Only female guinea pigs and rats were tested, and
only male mice were tested

•	Only one experimental assay was utilized to assess
cell-mediated and humoral immunity in each animal
species; humoral immunity was only investigated in
guinea pigs

•	TCDD used for dosing was of unknown purity

Endpoints relevant to humans
but study size limited; PBPK
model not available for
estimation of HED

White et al.
(1986. 197531)

• Total hemolytic complement (CH50) is
representative functional assay of the
complete complement sequence

•	Small sample size of rats/dose employed (n = 6-8)

•	Individual complement factors may be
significantly depleted without affecting
CH50 activity (only C3 is measured)

•	TCDD used for dosing was of unknown purity

Endpoint similar to effects
observed at higher exposure
levels in humans; HED highly
uncertain using mouse PBPK
model


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Table 4-7. Basis and derivation of the TCDD reference dose

Princi

jal study detail

Study

POD (ng/kg-day)

Critical effects

Mocarelli et al. (2008,
199595}

0.020 (LOAEL)

Decreased sperm count (20%) and motility (11%) in
men exposed to TCDD during childhood

Baccarelli et al. (2008,

197059")

0.024 (LOAEL)

Elevated TSH (> 5 |iU/mL) in neonates

RfD derivation

POD

0.020 ng/kg-day (2.0E-8 mg/kg-day)

UF

30 (UFL = 10, UFh = 3)

RfD

7 x 10-10 (7E-10) mg/kg-day (2.0E-8 - 30)

Uncertainty factors

LOAEL-to-NOAEL
(UFl)

10

No NOAEL established; cannot quantify lower exposure
group in Baccarelli et al. (2008. 197059); magnitude of
effects at LOAEL sufficient to require a 10-fold factor.

Human interindividual
variability
(UFh)

3

A factor of 3 (10°'5) is used because the effects were
elicited in sensitive populations. A further reduction to
1 was not made because the sample sizes were relatively
small, which, combined with uncertainty in exposure
estimation, may not fully capture the range of
interindividual variability.

Interspecies extrapolation
(UFa)

1

Human study.

Sub chroni c-to-chroni c

(UFS)

1

Chronic effect levels are not well defined for humans;
however, animal bioassays indicate that developmental
effects are the most sensitive, occurring at doses lower
than other effects noted in chronic studies. Considering
that exposure in the principal studies encompasses the
critical window of susceptibility associated with
development, an UF to account for exposure duration is
not warranted.

Database sufficiency
(UFd)

1

The database for TCDD contains an extensive range of
human and animal studies that examine a
comprehensive set of endpoints. There is no evidence to
suggest that additional data would result in a lower
reference dose.

This document is a draft for review purposes only and does not constitute Agency policy.

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Figure 4-1. EPA's process to select and identify candidate PODs from key
epidemiologic studies for use in the noncancer risk assessment of TCDD. For

each noncancer study that qualified for TCDD dose-response assessment using
the study inclusion criteria, EPA first evaluated the dose-response information
developed by the study authors for whether the study provided noncancer effects
and TCDD dose data for a toxicologically relevant endpoint. If such data were
available, then EPA identified a NOAEL or LOAEL as a candidate POD. Then,
EPA used a human kinetic model to estimate the continuous oral daily intake
(ng/kg-day) for the candidate POD that could be used in the derivation of an RfD
based on the study data. If all of this information was available, then the result
was included as a candidate POD.

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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Figure 4-2. EPA's process to select and identify candidate PODs from key
animal bioassays for use in noncancer dose-response analysis of TCDD. For

each noncancer endpoint reported in the studies that qualified for TCDD
dose-response assessment using the study inclusion criteria, EPA evaluated the
endpoint and eliminated it if it was not toxicologically relevant for RfD deriation.
Then, relevant endpoints not observed at the LOAEL (i.e., reported at higher
doses) with BMDLs greater than the LOAEL were eliminated from further
analysis. Endpoints with LOAELS greater than the minimum LOAEL times 100
also were eliminated from further analysis. Using kinetic modeling, EPA
developed human equivalent doses for each remaining NOAEL/LOAEL/BMDL
associated with selected endpoints and included these as candidate PODs.

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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5. CANCER ASSESSMENT

5.1. QUALITATIVE WEIGHT-OF-EVIDENCE CARCINOGEN CLASSIFICATION
FOR 2,3,7,8-TETRACHLORODIBENZO-jp-DIOXIN (TCDD)

5.1.1. Summary of National Academy of Sciences (NAS) Comments on the Qualitative
Weight-of-Evidence Carcinogen Classification for 2,3,7,8-Tetrachlorodibenzo-
jp-Dioxin (TCDD)

In its charge, the National Academy of Sciences (NAS) was requested to comment
specifically on U.S. Environmental Protection Agency (EPA)'s conclusion that
2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is best characterized as "carcinogenic to humans."
While indicating that distinction between the categories of "carcinogenic to humans" and "likely
to be carcinogenic to humans" is ".. .based more on semantics than on science..." (NAS, 2006,
198441. p. 141) and recommending that EPA "... spend its energies and resources on more
carefully delineating the assumptions used in quantitative risk estimates for TCDD..." (NAS,
2006, 198441. p. 141) rather than on the qualitative cancer descriptor for TCDD, the NAS
provided the following comments:

.. .the classification of dioxin as "carcinogenic to humans" versus "likely to be
carcinogenic to humans" depends greatly on the definition and interpretation of
the specific criteria used for classification, with the explicit recognition that the
true weight of evidence lies on a continuum with no bright line that easily
distinguishes between these two categories. The committee agreed that, although
the weight of epidemiological evidence that dioxin is a human carcinogen is not
strong, the human data available from occupational cohorts are consistent with a
modest positive association between relatively high body burdens of dioxin and
increased mortality from all cancers. Positive animal studies and mechanistic data
provide additional support for classification of dioxin as a human carcinogen.

However, the committee was split on whether the weight of evidence met all the
necessary criteria described in the cancer guidelines for classification of dioxin as
"carcinogenic to humans." EPA should summarize its rationale for concluding
that dioxin satisfies the criteria set out in the most recent cancer guidelines for
designation as either "carcinogenic to humans" or "likely to be carcinogenic to
humans (NAS, 2006, 198441. p. 140).

If EPA continues to designate dioxin as "carcinogenic to humans," it should
explain whether this conclusion reflects a finding that there is a strong association
between dioxin exposure and human cancer or between dioxin exposure and a key
precursor event of dioxin's mode of action (presumably AhR binding). If EPA's
finding reflects the latter association, EPA should explain why that end point

This document is a draft for review purposes only and does not constitute Agency policy.

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(e.g., AhR binding) represents a "key precursor event (NAS, 2006, 198441, p.

141).

5.1.2. EPA's Response to the NAS Comments on the Qualitative Weight-of-Evidence
Carcinogen Classification for TCDD

A cancer descriptor is used to express the conclusion of the weight of evidence regarding
the carcinogenic hazard potential of a compound. EPA agrees with the NAS committee that
cancer descriptors represent points along a continuum of evidence. Relatedly, EPA
acknowledges that there are gradations and borderline situations that cannot be communicated
through a descriptor and are best clarified by a full weight of evidence narrative.

The 2003 Reassessment contains a detailed discussion of TCDD carcinogenicity in both
humans (Part II, Chapter 7a; 8) and animals (Part II, Chapter 6; 8) as well as an overall summary
of TCDD carcinogenicity (Part III, Chapter 2.2.1). Since the release of the 2003 Reassessment,
the database pertaining to TCDD carcinogenicity has been strengthened and expanded by
numerous publications (U.S. EPA, 2008, 5192611 including a new chronic bioassay in female
rats (NTP, 2006, 543749) and several new follow-up epidemiological investigations (see
Section 2.4.1 and references therein). Many of these studies have been published subsequent to
the NAS review. These new data are summarized and evaluated in Section 2.4 of this document.

As noted by the NAS, the 2003 Reassessment was released prior to EPA's publication of
the U.S. EPA Guidelines for Carcinogen Risk Assessment ("2005 Cancer Guidelines"; U.S. EPA,
2005, 086237). Using EPA's guidance at the time of its release (U.S. EPA, 1996, 198087). the
2003 Reassessment determined that the available evidence was sufficient to classify TCDD as a
"human carcinogen." The 1996 guidance suggested "human carcinogen" to be an appropriate
descriptor of carcinogenic potential when there is an absence of conclusive epidemiologic
evidence to clearly establish a cause-and-effect relationship between human exposure and
cancer, but there are compelling carcinogenicity data in animals and mechanistic information in
animals and humans demonstrating similar modes of carcinogenic action.

The 2005 Cancer Guidelines (U.S. EPA, 2005, 086237) are intended to promote greater
use of the increasing scientific understanding of the mechanisms that underlie the carcinogenic
process. The 2005 Cancer Guidelines expand upon earlier guidance applied in the 2003
Reassessment and encourage the use of chemical- and site-specific data versus default options,
the consideration of mode of action information and understanding of biological changes, fuller

This document is a draft for review purposes only and does not constitute Agency policy.

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characterization of carcinogenic potential, and consideration of differences in susceptibility. The
2005 Cancer Guidelines also emphasize the importance of weighing all of the available evidence
in reaching conclusions about the human carcinogenic potential of an agent. As noted above,
additional information on TCDD carcinogenicity has been published since the release of the
2003 Reassessment. This information has expanded the TCDD database and provided additional
support for conclusions made in the 2003 Reassessment regarding the carcinogenic potential of
TCDD.

Under the 2005 Cancer Guidelines (U.S. EPA, 2005, 086237). TCDD is characterized as
carcinogenic to humans, based on the available data as of 2009. The 2005 Cancer Guidelines
indicate that this descriptor is appropriate when there is convincing epidemiologic evidence of a
causal association between human exposure and cancer or when all of the following conditions
are met (a) there is strong evidence of an association between human exposure and either cancer
or the key precursor events of the agent's mode of action, but not enough for a causal
association, and (b) there is extensive evidence of carcinogenicity in animals, and (c) the mode(s)
of carcinogenic action and associated key precursor events have been identified in animals, and
(d) there is strong evidence that the key precursor events that precede the cancer response in
animals are anticipated to occur in humans and progress to tumors, based on available biological
information.

As noted above, the NAS commented that EPA should ".. .explain whether this
conclusion reflects a finding that there is a strong association between dioxin exposure and
human cancer or between dioxin exposure and a key precursor event of dioxin's mode of action
(presumably AhR binding)" (NAS, 2006, 198441). When evaluating the carcinogenic potential
of a compound, EPA employs a weight of evidence approach in which all available information
is evaluated and considered in reaching a conclusion. The following sections provide a summary
of EPA's weight of evidence evaluation for TCDD.

5.1.2.1. Summary Evaluation of Epidemiologic Evidence of TCDD and Cancer

The available occupational epidemiologic studies provide convincing evidence of an
association between TCDD exposure and all cancer mortality. Among the strongest of these are
the studies of over 5,000 U.S. chemical manufacturing workers (the National Institute for
Occupational Safety and Health [NIOSH] cohort) (Ay 1 ward et al., 1997, 594365; Cheng et al.,

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2006, 523122; Collins et al., 2009, 197627; Fingerhut et al., 1991, 197301; Steenland et al.,
1999, 197437; Steenland et al., 2001, 198589); a study of nearly 2,500 German workers involved
in the production of phenoxy herbicides and chlorophenols (the Hamburg cohort) (Becher et al.,

1996,	197121; Becher et al., 1998, 197173; Flesch-Janys et al., 1995, 197261; Flesch-Janys et
al., 1998, 197339; Manz et al., 1991, 199061; Nagel et al., 1994, 594369); a study of more than
2,000 Dutch workers in two plants involved in the synthesis and formulation of phenoxy
herbicides and chlorophenols (the Dutch cohort) (Bueno et al., 1993, 196993; Hooiveld et al.,
1998, 197829); a smaller study of roughly 250 workers involved in a chemical accident cleanup
(the BASF cohort) ed in a chemical accident cleanup (the BASF cohort) (Ott and Zober, 1996,
198101; Thiess et al., 1982, 064999; Zober et al., 1990, 197604); and an international study of
more than 18,000 workers exposed to phenoxy herbicides and chlorophenols (Kogevinas et al.,

1997,	198598; Saracci et al., 1991, 199190) including newer studies of smaller subsets of these
workers (McBride, 2009, 198490; McBride et al., 2009, 197296; t' Mannetje et al., 2005,

197593). The findings from these studies have been thoroughly described either in the 2003
Reassessment or in Section 2.4.1 of this document.

As noted in Section 2.4, there are considerable challenges inherent in addressing potential
sources of confounding from smoking and co-exposure to other carcinogens, (which could
produce inflated or spurious associations), the healthy worker effect, (which could result in
attenuated effects through comparison with a referent background with an inappropriately high
background risk), and quantifying exposure to the populations included in many of these
retrospective studies. The more recent studies of these cohorts have made significant advances
in reducing the potential for bias from the healthy worker effect through use of internal cohort
analyses and/or controlling for potential confounders through statistical adjustment, restriction,
and use of internal comparisons. Although some exposure assessment uncertainties remain,
some of these studies have also collected individual-level TCDD exposure estimates that allow
quantification of effective dose necessary for dose-response modeling. Overall, the occupational
data provide consistent support for an association between exposure to TCDD and increased
cancer mortality.

Additional epidemiologic evidence supporting an association between TCDD exposure
and cancer comes from studies investigating the morbidity and mortality of residents exposed to
TCDD following an accidental release from a chemical plant near Seveso, Italy (the Seveso

This document is a draft for review purposes only and does not constitute Agency policy.

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cohort) (Bertazzi et al., 1989, 197013; Bertazzi et al., 1993, 192445; Bertazzi et al., 1997,

197097; Bertazzi et al., 2001, 197005; Consonni et al., 2008, 524825; Pesatori et al., 1998,
523076; Pesatori et al., 2003, 197001; Warner et al., 2002, 1974891 Pesatori et al. (2003,
197001) and Consonni et al. (2008, 524825) were not available at the time the 2003
Reassessment was released. Among individuals with relatively high exposure at Seveso
(Zones A and B combined), all-cancer mortality in the 20-year post-accident period and all-
cancer incidence in the 15-year post-accident period failed to exhibit significant departures from
the expected 197001). However, an increased risk of all-cancer mortality was noted among men
15-20 years after first exposure; not only is the association similar in magnitude to other studies
(relative risk [RR] = 1.3; 95% confidence interval [CI] = 1.0-1.7) but also emphasizes the
importance of consideration of latency (Bertazzi et al., 2001, 197005). Furthermore, associations
between TCDD and some specific cancer sites were detected in this cohort, including increased
incidence (based on 15 years of follow-up) and mortality (based on 20 years follow-up) from
lymphatic and hematopoietic neoplasms in both males and females from Zones A and B
(Consonni et al., 2008, 524825). This excess was primarily due to non-Hodgkin's lymphoma.
Additionally, there was an increase in lung and rectal cancer mortality in men (Bertazzi et al.,

2001,	197005) and limited evidence of increased liver cancer incidence in women based on the

15-year follow-up study (Bertazzi et al., 1993, 192445). In a separate analysis of 981 women in
Zone A, breast cancer incidence (n = 15) was associated (a 2-fold increase for a 10-fold increase
in serum TCDD) with TCDD measurements first collected in 1976 and 1977 (Warner et al.,

2002,	197489). The authors also reported a 2-3-fold increase in all cancer incidence (n = 21) for
the two upper quartiles of TCDD exposure.

Overall, the newer studies of the Seveso cohort have reported significant increases in
cancer incidence and elevations in cancer mortality that were not evident in earlier studies of this
cohort. While these studies demonstrate an association between TCDD exposure and different
types of cancer, one of the main limitations is the small number of cancer cases to assess
site-specific associations with TCDD exposure. Ongoing studies in that cohort should help
further elucidate potential risk for specific cancer types (and other endpoints) associated with
TCDD exposures among this population.

This document is a draft for review purposes only and does not constitute Agency policy.

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5.1.2.1.1. Evidence for causality.

The evidence for causality for cancer from the human studies is briefly summarized in the
paragraphs that follow and is based on recommendations from the 2005 Cancer Guidelines. It
should be noted that there are methodological limitations of the epidemiologic studies that may
temper some of the conclusions regarding causality. These limitations include limited statistical
power, exposure assessment uncertainty, and lack of control of confounders (e.g., dioxin-like
compounds and smoking) in some studies. There also is additional uncertainty in the evidence
for causality due to the lack of organ specificity in TCDD associated cancers, as the most
consistent results occurred for all-cancer mortality; however, this would be consistent with a
hypothesized carcinogenic mode of action of TCDD as a promoter. Despite these uncertainties,
many of the more recent studies have greatly improved exposure assessments compared to
earlier studies of the same cohorts and have addressed the potential for confounding and other
types of biases.

Temporality—exposure must precede the effect for causal inference. Given the long
induction period for many types of cancers, exposure should precede the effect with a sufficient
latency (i.e., typically 15-20 years for environmental carcinogens). In all the occupational
studies reviewed (with the exception of (McBride, 2009, 198490)1 TCDD exposure has
preceded the effect with sufficient latency to be considered causally associated. In the studies of
the Seveso cohort, the follow-up exposure period has now reached 20 years, a latency sufficient
to address some carcinogenic endpoints. Since most of the studies are based on occupational
exposures or accidental releases into the environment, temporality is more readily established
due to the obvious determination of the specific exposure windows prior to disease onset.

Strength of Association—refers to the magnitude of measures of association such as the
ratio of incidence or mortality (e.g., standardized mortality ratio [SMRs], standardized incidence
ratios, RRs, or odds ratios) in addition to statistical significance considerations. Effect estimates
that are large in magnitude are less likely to be due to chance, bias, or confounding. Reports of
modest risk, however, do not preclude a causal association and may reflect an agent of lower
potency, lower levels of exposure or attenuation due to nondifferential exposure
misclassification. The four occupational cohorts with the highest exposures (NIOSH, Hamburg,
Dutch, and BASF) consistently showed statistically significant, although moderate, elevations in
cancer mortality. When the data were combined, the SMR for all four subcohorts was 1.4

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[95% CI = 1.2-1.6] (IARC, 1997, 537123). Based on findings from the International Agency for
Research on Cancer (IARC) Working Group, increases in all cancer (combined) mortality of the
magnitude reported for TCDD have rarely been found in occupational cohort studies (IARC,
1997, 537123). Although these estimates are higher than the all-cancer mortality results among
Seveso men(RR= 1.1; 95% CI = 1.0-1.3), they are comparable to the risk estimated in this
population (RR = 1.3; 95% CI = 1.0-1.7) 15-20 years after first exposure.31 These consistent
results comparable in magnitude from the occupational cohorts and Seveso population are not
likely due to chance.

The occupational cohort studies also show an increased risk for lung cancer in the
previously mentioned four subcohorts. The relative risk for lung cancer in the combined highly
exposed subcohorts was estimated to be 1.4 (95% CI = 1.1-1.7) (IARC, 1997). This is
consistent with the lung cancer mortality findings for the highest exposed group of men in
Seveso (RR = 1.3; 95% CI = 1.0-1.7). Additionally, there was an increase in rectal cancer
mortality in the Seveso cohort (RR = 2.4; 95% CI = 1.2-4.6) (Bertazzi et al., 2001, 197005) with
a corresponding increase in incidence. Consistent relative risks of more than two were also
detected for rectal cancer in the Hamburg and New Zealand cohorts, but increased risks were not
found in the other cohorts. Although there was limited evidence of increased incidence or
morality from hepatobiliary cancers across the cohorts, liver cancer incidence was elevated in the
15-year post accident period among women in the Seveso cohort (RR = 2.4; 95% CI = 1.1-5.1,
(Warner et al., 2002, 197489)). An association in this population was also detected for between
breast cancer incidence (RR = 2.1; 95% CI = 1.0-4.6) and serum TCDD levels (per a 10-fold
increase in serum TCDD). Although findings were based on small numbers, three- and four-fold
increased risks of soft tissue sarcoma were detected among the NIOSH (Collins et al., 2009,
197627) and New Zealand cohorts (McBride, 2009, 198490). No other cases of this very rare
cancer were detected in the exposed populations from the other cohorts.

31In addition to consideration of statistical significance to address the possibility of random variability (i.e., chance),
many other factors are important to consider when assessing causality using a weight of evidence determination. As
noted in the EPA's Cancer Guidelines, a number of factors besides statistical significance are relevant for assessing
evidence of adverse health effects based on human data. These include strength of association, temporality,
biological gradient (i.e., dose-response concordance), biological plausibility, etc.). In analyzing the body of
information in the literature, the consistency of the magnitude of reported risk estimates (across different studies) is
considered when addressing causality; rather than relying solely on statistical significance.

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Elevated risk of lymphohemopoietic cancer mortality was noted among the Seveso cohort
(RR = 1.7; 95% CI = 1.2, 2.5) (Consonni et al., 2008, 524825). Increased SMRs for
lymphohemopoietic cancer comparable in magnitude (range: 1.6-2.2) were also detected among
the Hamburg and New Zealand occupational cohorts, but limited evidence (range: 1.0 to 1.2) of
increased mortality was found in the BASF, NIOSH and Ranch Hands employees (Akhtar et al.,
2004, 197141: Ott and Zober, 1996, 198101: Steenland et al., 1999, J97437). Most of the
lymphohemopoietic cancer mortality risk was reportedly due to non-Hodgkin's lymphoma in
most of the cohorts. Relative risks for non-Hodgkin's lymphoma among TCDD exposed
populations from the NIOSH, Hamburg, New Zealand, Dutch, and Seveso cohorts ranged from
1.2 to 3.8. Although statistical power was limited in most of these studies, relative risks
exceeded 3.0 for non-Hodgkin's lymphoma in three of these cohorts (Consonni et al., 2008,
524825: Flesch-Janys et al., 1998, 197339: Hooiveld et al., 1998, 197829V

Consistency—the observation of the same site-specific effect across several independent
study populations strengthens an inference of causality. Despite differences across occupational
cohorts, most studies have consistently reported increases in all-cancer mortality with TCDD
exposure. Several of these studies have also reported increases in lung cancer related to TCDD
exposure. As noted above, there is also suggestive evidence of an increased risk in all-cancer
and lung cancer mortality among the Seveso cohort consistent in magnitude to the occupational
cohorts. Elevated risk of lymphohemopoietic cancer mortality consistent in magnitude
(range: 1.6-2.2) was also detected among the Seveso, Hamburg and New Zealand cohorts. An
increased risk for non-Hodgkin's lymphoma was found in two of the occupational cohorts as
well as in the Seveso cohort, although the relative risks largely did not achieve statistical
significance. Among those studies detecting an association, consistent two-fold relative risks
were found for rectal cancer (Bertazzi et al., 2001, 197005: Flesch-Janys et al., 1998, 197339:
McBride, 2009, 198490) and relative risks in excess of three were detected for soft tissue
sarcoma (Collins et al., 2009, 197627: McBride, 2009, 198490).

Biological Gradient—refers to the presence of a dose-response and/or duration-response
between a health outcome and exposure of interest. Several of the occupational cohort studies
(Flesch-Janys et al., 1998, 197339: Manz et al., 1991, 199061: Michalek and Pavuk, 2008,
199573: Ott and Zober, 1996, 198101: Steenland et al., 1999, 197437) found evidence of a
dose-response relationship for all cancers and various TCDD exposure measures. The SMR

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analyses based on internal comparisons within the occupational cohorts show a biological
gradient by comparing highly TCDD exposed workers to low or unexposed workers. A
biological gradient was also demonstrated in the Seveso cohort by comparing highly exposed
individuals (Zones A and B) to individuals in lower exposure zones (Zones C and R). Warner et
al. (2002, 197489) also reported evidence of a dose-response trend for breast cancer and
increasing TCDD exposures.

Biological Plausibility—refers to the observed effect having some biological link to the
exposure. Most evidence suggests that toxic effects of TCDD are mediated by interaction with
the aryl hydrocarbon receptor (AhR). AhR is a highly conserved protein among mammals,
including humans (Fujii-Kuriyama et al., 1995, 543727; Harper et al., 2002, 198124; Nebert et
al., 1991, 5437281 Several hypothesized modes of action have been presented for TCDD-
induced tumors in rodents, all involving AhR activation. The available evidence does not
preclude the relevance of these hypothesized modes of action to humans.

Specificity—as originally intended, refers to increased inference of causation if a single
site effect, as opposed to multiple effects, is observed and associated with exposure. Based on
current biological understanding, this is now considered one of the weaker guidelines for
causality. As stated in the 2005 Cancer Guidelines, given the current understanding that many
agents cause cancer at multiple sites, and cancers have multiple causes, the absence of specificity
does not detract from evidence for a causal effect. Given that the most consistent findings
associating TCDD and cancer are for all-cause cancer mortality, epidemiological evidence
suggests that TCDD lacks specificity for particular tumor sites. A key event in TCDD's mode of
action is binding to and activating AhR; however, downstream events leading to tumor formation
are uncertain and may likely be tissue specific. Given that the AhR is highly conserved among
species and is expressed in various human tissues, the lack of tumor site specificity does not
preclude a determination of causality.

In summary, EPA finds the available epidemiological information provides strong
evidence of an association between TCDD exposure and human cancer that cannot be reasonably
attributed to chance or confounding and other types of bias, and with a demonstration of
temporality, strength of association, consistency, biological plausibility, and a biological
gradient. Additional evidence from animal studies and from mechanistic studies (described
below) provides additional support for the classification of TCDD as carcinogenic to humans.

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5.1.2.2.	Summary of Evidence for TCDD Carcinogenicity in Experimental Animals

An extensive database on the carcinogenicity of TCDD in experimental animals is
described in detail in Part II, Chapter 6 of the 2003 Reassessment. There is substantial evidence
that TCDD is carcinogenic in experimental animals based on long-term bioassays conducted in
both sexes of rats and mice (Kociba et al„ 1978, 001818; NTP, 1982, 594255; NTP, 2006,
543749) and in male hamsters (Rao et al., 1988, 199032). Additionally, National Toxicology
Program (NTP, 2006, 543749) has completed a new chronic bioassay in female Sprague Davvley
rats. These studies are summarized in Section 2.4.2 of this document. All studies have produced
positive results, with TCDD increasing the incidence of tumors at sites distant from the site of
treatment and at doses well below the maximum tolerated dose. In both sexes of rodents, when
administered by different routes and at low doses, TCDD caused tumors at multiple sites; tumors
were observed in liver, lung, lymphatic system, soft tissue, nasal turbinates, hard palate, thyroid,
adrenal, pancreas, and tongue. The most consistent and best characterized carcinogenic
responses to TCDD are in the rodent liver, lung, and thyroid (discussed below in
Section 5.1.2.3).

5.1.2.3.	TCDD Mode of Action

The 2005 Cancer Guidelines defines the term "mode of action" as "a sequence of key
events and processes, starting with interaction of an agent with a cell, proceeding through
operational and anatomical changes, and resulting in cancer formation." A "key event" is an
empirically observable precursor step that is itself a necessary element of the mode of action or is
a biologically based marker for such an element. Mode of action is contrasted with "mechanism
of action," which implies a more detailed understanding and description of events, often at the
molecular level. In the case of TCDD, the terms 'mechanism of action' and 'mode of action' are
often used interchangeably in the scientific literature in reference to TCDD's interaction with the
AhR. A thorough discussion of TCDD's interaction with the AhR can be found in the 2003
Reassessment (Part II, Chapter 2; Part III, Chapter 3), and is summarized below (see
Section 5.1.2.3.1).

Most evidence suggests that the majority of toxic effects of TCDD are mediated by
interaction with the AhR. EPA considers interaction with the AhR to be a necessary, but not
sufficient, event in TCDD carcinogenesis. The sequence of key events following binding of

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TCDD to the AhR and that ultimately leads to the development of cancer is unknown.

Therefore, in the strictest sense, TCDD's interaction with the AhR does not constitute a "mode
of action" as defined by the 2005 Cancer Guidelines because information about the progression
of necessary events is lacking. However, AhR binding and activation by TCDD is considered to
be a key event in TCDD carcinogenesis.

5.1.2.3.1. The aryl hydrocarbon receptor (AhR).

While substantial evidence suggests that most toxic effects of TCDD are mediated by
interaction with the AhR, less is known about the complex responses that result in tumor
formation. Nonetheless, a picture is emerging wherein TCDD is considered a
"receptor-mediated carcinogen" in laboratory animals (see Figure 5-1), acting in a manner
similar to peroxisome proliterators, phorbol esters, or estrogen (Woods et al., 2007, 543735).

TCDD activates the AhR, a member of the basic helix-loop-helix, Per-Arnt-Sim
(bHLH-PAS) family of transcription factors. AhR is present in most cell types and in the
inactivated state is cytosolic and exists in a complex with chaperone proteins, such as heat shock
protein 90 (Hsp90). Binding of TCDD to AhR leads to nuclear translocation and
heterodimerization with its partner protein Arnt, another bHLH-PAS family member. The
AhR: Arnt heterodimer binds to specific cognate DNA sequence elements known as
dioxin/xenobiotic response elements (DRE/XRE) present in the regulatory region of specific
genes. Binding of the AhR: Arnt heterodimer to these elements, and subsequent recruitment of
tissue specific transcriptional coactivator complexes, leads to increased transcription of specific
genes, known as "target genes." There is a battery of genes affected in this manner and targets
include certain xenobiotic-metabolizing enzymes, such as cytochrome P450 (CYP)l Al,

CYP1A2, CYP2B1, and UDP-glucuronosyltransferase (UGT)1A6 (reviewed in Schwartz and
Appel, 2005, 543737). In addition, genes affected by the TC D D/Ah R-com pi ex code for both
inhibitory and stimulatory growth factors; their gene products affect cellular growth,
differentiation and homeostasis and have been shown to contribute to carcinogenicity as well as
other forms of toxicity (reviewed in Popp et al., 2006, 197074).

Detailed molecular biology research has been performed to identify the extent of the
genes regulated by AhR (Woods et al., 2007, 543735): however a complex and still ill-defined
profile remains. The basic physiology of AhR signaling is still poorly understood, despite being

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highly conserved among vertebrate species (reviewed in Hahn, 2002, 099302). In fact, it is now
known that the AhR recognizes a large number of chemical structures, including nonaromatic
and nonhalogenated compounds (Denison and Nagy, 2003, 197226). which supports the
biological role of the AhR as a receptor that helps regulate the expression of genes necessary for
biotransformation of environmental chemicals (i.e., CYP1A1). However, the endogenous
physiological role of AhR is complicated, as evidenced by the numerous studies examining AhR
null (ArH -/-) mice, which demonstrate alterations in the liver, immue system, ovary, heart and
other organs (reviewed in Hahn, 2009, 477460). The endogenous function of AhR remains
unknown.

Given that the AhR is expressed in most tissues (Dolwick et al., 1993, 543762) with
tissue-specificity in terms of level of expression and the profile of target genes, there is
substantial complexity and difficulty associating TCDD-mediated transcription of specific target
genes and tissue-specific toxic responses, including cancer. It is important to note that the extent
of the response of individual TCDD target genes does not correlate with site-specific
tumorigenicity. For example, while TCDD is ineffective as a tumor promoter in ovariectomized
rats and does not stimulate liver cell proliferation in these animals, it is still capable of inducing
CYP1A2 in roughly the same magnitude as in the intact female rats (Lucier, 1991, 198691).
Similarly, CYP1 Al induction by TCDD is very similar in male and female rats even though
males are almost completely resistant to TCDD carcinogenicity (Wyde et al., 2002, 197009).

Some of AhR's effects on gene expression may be the result of interaction with other
transcription factors (such as the retinoblastoma protein(Ge and El fieri nk, 1998, 197702). NF-kB
(Tian et al., 1999, 198378) or with the tyrosine kinase c-Src (Blankenship and Matsumura, 1997,
543751) rather than via direct interaction with DNA. By far the most extensive studies involving
cross-talk between AhR and another transcription factor are those involving the estrogen receptor
alpha (ERa). The anti-estrogenic properties of TCDD have been well-documented, beginning
with the observations that TCDD repressed estradiol function in rat uterus and liver. The
AhR-ERa cross-talk can be manifested at several levels including direct protein interaction,
association of the receptors with the other's response element and altered metabolism of estradiol
by AhR ligand (Takemoto et al., 2004, 543753). The interactions between AhR/Arnt- and
estrogen receptor-dependent signaling pathways, which mediate anti-estrogenic effects of
dioxins and dioxin-like polychlorinated biphenyls (PCBs; Bock, 1994, 543755). is probably

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causal for the well-documented gender-specificity of the carcinogenic effects of these agents
(e.g., hepatocarcinogenicity of TCCD in female as opposed to male rats) (Lucier, 1991, 198691).
In addition, cross-talk between AhR/Arnt and other nuclear receptors, their coactivators, and
corepressors, has been described. In fact, cross-talk has been reported for AhR and numerous
signaling pathways involved in a broad range of physiological processes. The molecular
mechanisms by which the AhR interferes with these signaling networks are multifaceted and
occur at multiple levels of regulation (many beyond transcriptional control)
(Haarmann-Stemmann et al., 2009, 197874). It remains unknown how any of these molecular
pathways involving AhR signaling are linked to TCDD-mediated carcinogenesis.

Pertinent to human risk assessment, there are wide inter- and intraspecies differences in
the toxicological responses to TCDD (Etna et al., 1994, 197313; Poland and Glover, 1990,
543759; Poland et al., 1994, 198439) some of which can be explained by polymorphisms in
AhR. For instance, there is a 10-fold difference in susceptibility to TCDD-induced toxicity
between the TCDD-sensitive C57BL/6 and the TCDD-resistant DBA/2 strains of mice (Poland
and Glover, 1980, 543761) that can be explained by polymorphic variations in the ligand-binding
domain and in the C-terminal region of the AhR molecule of each strain (Dolwick et al., 1993,
543762). Depending on the system examined, the estimated affinity of binding of TCDD (and
related compounds) to the human AhR is about 10-fold lower than that observed to the AhR
from "responsive" rodent species and is comparable to that observed to the AhR from
"nonresponsive" mouse strains (Ramadoss and Perdevv, 2004, 198824). This reduced affinity is
due, in part, to a single amino acid substitution within the ligand binding domain of the human
and "nonresponsive" mouse AhRs (Ramadoss and Perdevv, 2004, 198824). Although the affinity
of binding of TCDD and related compounds to the human AhR is reduced compared with rodent
AhRs, the qualitative and quantitative rank-order potency of these chemicals is similar. The
considerable tissue and species variability in response to TCDD cannot be ascribed solely to
polymorphisms of the AhR gene (Geyer et al., 1997, 543768; Pohjanvirta and Tuomisto, 1994,
543767). further complicating this key event in TCDD-mediated carcinogenesis.

5.1.2.3.1.1. Other AhR considerations.

In addition to the potent agonist TCDD, there are many other exogenous ligands for the
AhR, including certain polycyclic aromatic hydrocarbons, polychlorinated dibenzofurans, and

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PCBs (Bock, 1994, 543755). Several natural and endogenous compounds are also regulators of
AhR (Chiaro et al., 2008, 543771). The classes of endogenous compounds that have been shown
to induce CYP1 and/or activate AhR include: (a) tryptophan metabolites, other indole-containing
molecules, and phenylethylamines (Gielen and Nebert, 1971, 543775); (b) tetrapyrroles such as
bilirubin and biliverdin; (c) sterols such as 7-ketocholesterol and the horse steroid equilenin;
(d) fatty acid metabolites, including at least six different prostaglandins (Seidel et al., 2001,
543776) and lipoxin A4; and (e) the ubiquitous second messenger cAMP (reviewed in McMillan
and Bradfield (2007, 543777) and Barouki et al. (2007, 543778)). Several of these endogenous
and exogeous compounds, including bilirubin, biliverdin, and P-naphthoflavone, that also bind to
the AhR are not carcinogenic in rodent models, therefore, some other key precursor event(s)
need to be identified. Further, the existence of multiple ligands with varying affinity and
responses suggests that "selective receptor modulators" (or SRMs) of the AhR exist. SRMs are
ligands for a receptor that, upon binding, elicit a conformational change in the receptor that
results in differential recruitment of coregulatory molecules to the target gene promoter region,
thereby imparting a different biological activity relative to the prototypical ligand. This
phenomenon has been most studied for nuclear receptors such as the ERa with the classic
example being tamoxifen, which has estrogen-like activity in the uterus but anti-estrogen-like
effects in the breast. Thus, the relative abilities of compounds to stimulate gene expression or
other effects vary in promoter- and cell type-specific manners. It is now apparent that SRMs
exist for the AhR as well (SAhRMs, Fretland et al., 2004, 197357). For example,
6-methyl-l,3,8-trichlorodibenzofuran (6-MCDF), a SAhRM whose structure is similar to that of
TCDD, can induce CYP1 Al gene expression in liver but does not lead to the toxic responses
associated with TCDD (Fritz et al., 2009, 594372). The existence of SAhRMs further
complicates the role of TCDD binding to AhR as a key event in TCDD-mediated
carcinogenicity, and suggests that additional information is necessary to elucidate the
carcinogenic mode of action of TCDD.

TCDD may have dose-dependent modes of action. It has been demonstrated that
AhR-deficient (AhR-/-) mice show no signs of toxicity at doses of TCDD approximating the
lethal dose eliciting 50% response (LD50) dose (200 (J,g/kg) in AhR +/+ mice (Fernandez -
Salguero et al., 1996, 197650). However, a single high exposure of 2,000 (.ig/kg to
AhR-deficient mice produced several minor lesions including scattered necrosis and vasculitis in

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the liver and lungs. These data suggest that a pathway leading to toxicity exists, albeit at very
high doses, that is independent of the AhR. However, these data also indicate that, at least in
mice, the major in vivo effects of TCDD are mediated through the AhR. The finding of
carcinogenicity in hamsters (Rao et al., 1988, 199032) is of special interest since hamsters have
been found to be relatively resistant to the lethal effects of TCDD (Henck et al., 1981, 543779;
Olson et al., 1980, 197976). To date, there have been no chronic bioassay studies of TCDD
carcinogenicity in AhR-deficient transgenic animals.

There are additional insights into the complexity of TCDD's mechanism of action
involving AhR. Some biochemical responses to TCDD treatment in isolated cells have been
reported in cells lacking Arnt, in cells expressing a mutated Arnt protein and in cells with highly
reduced levels of AhR (Kolluri et al., 1999, 548721; Puga et al., 1992, 543784). implying either
a non nuclear role of the AhR in mediating these events or an AhR-independent process.

Additionally, recent studies have linked AhR activation in the absence of exogenous
ligand to a multitude of biological effects, ranging from control of mammary tumorigenesis to
regulation of autoimmunity (Hahn et al., 2009, 548725). Finally, constitutively activated AhR in
rodents has been shown to induce stomach tumors (Andersson et al., 2002, 197101). This
indicates that AhR activation alone (i.e., in the absence of ligand) is sufficient to induce tumors.

5.1.2.3.2. TCDD as a tumor promoter.

The role of TCDD as a tumor promoter is discussed in the 2003 Reassessment (Part II,
Chapter 6). The following is a brief summary of the information regarding TCDD as a tumor
promoter.

Numerous studies have examined the tumor promoting potential of TCDD. Using the
traditional two-stage initiation-promotion study design in the liver, studies have demonstrated
that TCDD is a dose- and duration-dependent liver tumor promoter (Dragan and Schrenk, 2000,
197243; Maronpot et al., 1993, 198386; Pitot et al., 1980, 197885; Teeguarden et al., 1999,
198274; Walker et al., 2000, 198733)(Walker et al., 1998). TCDD has also tested positive for
tumor promoting ability in the two-stage models of mouse skin tumorigenesis (Dragan and
Schrenk, 2000, 197243; I ARC, 1997, 537123). and in the lung (Anderson et al., 1991, 201761;
Beebe et al., 1995, 548754). Overall, the data demonstrate that TCDD is a tumor promoter and
potentially harbors only weak initiating activity.

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TCDD is typically designated as a nongenotoxic and nonmutagenic carcinogen because it
does not damage DNA directly through the formation of DNA adducts, is negative in most
short-term assays for genotoxicity, and is a potent tumor promoter and a weak initiator or
noninitiator in multistage models for chemical carcinogenesis (Clark et al., 1991, 594378;
Flodstrom and Ahlborg, 1991, 548728; Graham et al., 1988, 594375; Lucier, 1991, 198691; Pi tot
et al., 1980, 197885; Poland et al., 1982, 199756). However, mechanisms have been proposed
that support the possibility that TCDD might be indirectly genotoxic, either through the
induction of oxidative stress or by altering the DNA-damaging potential of exogenous and
endogenous compounds, such as estrogens. In addition, there have been numerous reports
demonstrating TCDD-induced modifications of growth factor signaling pathways and cytokines
in experimental animals and cell culture systems. Some of the altered signaling pathways
include those for epidermal growth factor, transforming growth factor alpha, glucocorticoids,
estrogen, tumor necrosis factor-alpha, interleukin 1-beta, plasminogen inactivating factor-2, and
gastrin. Many of these pathways are involved in cell homeostasis, proliferation, and
differentiation and provide plausible mechanisms responsible for the carcinogenic actions of
TCDD. Unfortunately, information on the etiology of the different tumor types is lacking to
equivocally link tumor promotion or indirect genotoxic action of TCDD to a specific mechanism
or mode of TCDD carcinogenesis.

5.1.2.3.3. Hypothesized modes of action of TCDD in rodents.

TCDD has been shown to consistently induce multiple tumors in both sexes in several
rodent species. These tumors are observed in various tissues, including (but not limited to):
liver, lung, thyroid, lymphatic system, soft tissue, nasal turbinates, hard palate, adrenal, pancreas,
and tongue. While the mode of action of TCDD in producing cancer has not been elucidated for
any tumor type, the best characterized carcinogenic actions of TCDD are in rodent liver, lung,
and thyroid. The hypothesized mode of action for each of these three tumor types is briefly
discussed below and is described in Figure 5-2. The hypothesized sequence of events following
TCDD interaction with the AhR is markedly different for each of these three tumor types. No
detailed hypothesized mode of action information exists for any of the other reported tumor
types. Further, no single definitive mode of action of TCDD-mediated carcinogenicity has been
identified.

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5.1.2.3.3.1.	Liver tumors.

The mode of action of TCDD in producing liver cancer in rodents has not been
elucidated. One hypothesized mode of carcinogenic action of TCDD in the liver is mediated
through hepatotoxicity. Generically speaking, TCDD activation of the AhR leads to a variety of
changes in gene expression, which then lead to hepatotoxicity, followed by compensatory
regenerative cellular proliferation and subsequent tumor development (see Figure 5-2). The
details of the mechanism of TCDD-induced hepatotoxicity have not been fully determined but
both CYP induction and oxidative stress have been postulated to be involved (Maronpot et al.,
1993, 198386; Viluksela et al., 2000, 198968). The enhanced cell proliferation arising from
either altered gene expression or hepatotoxicity, or both, may lead to the promotion of
hepatocellular tumors (Whysner and Williams, 1996, 197556). The sensitivity of female rat liver
to TCDD, which apparently does not extend to the mouse, depends on ovarian hormones (Lucier,
1991, 198691; Wyde et al., 2001, 198575). This sensitivity has been ascribed to induction of
estradiol metabolizing enzymes (Graham et al., 1988, 594375) and is hypothesized to lead either
to generation of reactive metabolites of endogenous estrogen or to active oxygen species of
estrogens. Oxidative DNA damage has been implicated in liver tumor promotion (Umemura et
al., 1999. 198001).

A dose-response relationship exists for TCDD-mediated hepatotoxicity, and this parallels
the dose-response relationship for tumor formation (or formation of foci of cellular alteration as a
surrogate of tumor formation). However, the dose-response relationship for other
TCCD-induced responses such as enhanced gene expression is different from the dose-response
for tumor formation in terms of both efficacy and potency (see Popp et al. (2006, 197074) for
review). It is important to note that differences in potency between events (i.e., gene expression
versus cell proliferation) does not necessary imply alternative mechanisms of action.

5.1.2.3.3.2.	Luns tumors.

The mode of action of TCDD in producing lung cancer in rodents (predominantly
keratinizing squamous cell carcinoma, (Larsen, 2006, 548744)) has not been elucidated. One
hypothesized mechanism of the carcinogenic action of TCDD in the lung involves disruption of
retinoid homeostasis in the liver (see Figure 5-2). Retinoic acids and their corresponding nuclear
receptors, the retinoic acid receptors (RARs) and the retinoid X receptors (RXRs), work together

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to regulate cell growth, differentiation, and apoptosis. It is hypothesized that TCDD, through
activation of the AhR, can affect parts of the complex retinoid system and/or other signaling
systems regulated by, and/or cross-talking with, the retinoid system (reviewed in (Nilsson and
Hakansson, 2002, 548746)). These effects are then hypothesized to lead to lung tumor
development; however, the mechanisms underlying this hypothesis are not well-defined.
Pulmonary squamous proliferative lesions have been reported following oral exposure to TCDD
in rats (Tritscher et al., 2000, 197265). In general, squamous metaplasia with some
inflammation is associated with significant forms of injury via inhalation of toxic compounds but
is also seen with vitamin A deficiency (Tritscher et al., 2000, 197265) and gives some credence
to this hypothesis.

Another hypothesized mechanism for the carcinogenic action of TCDD in the lung is
through induction of metabolic enzymes. Through activation of AhR and subsequent induction
of metabolizing enzymes (such as CYP1 Al), TCDD may enhance bioactivation of other
carcinogens in lung (Tritscher et al., 2000, 197265). There have been few studies to support this
hypothesis; however, in a long-term continuous-application study of carcinogenesis using
airborne particulate extract (APE), squamous cell carcinoma occurred in 8 of 17 AhR+/+ mice
(47%) while no tumors were found in AhR-/- mice (Matsumoto et al., 2007, 548748). In
addition CYP1 Al was induced in AhR+/+ mice but not in AhR-/- mice in this study. These
results suggest that AhR plays a significant role in APE-induced carcinogenesis in AhR+/+ mice
and CYP1A1 activation of carcinogenic polycyclic aromatic hydrocarbons (the primary
carcinogenic component of APE) is also of importance.

5.1.2.3.3.3. Thyroid tumors.

The mode of action of TCDD in producing thyroid cancer in rodents has not been
elucidated. It is hypothesized that TCDD increases the incidence of thyroid tumors through an
extrathyroidal mechanism (see Figure 5-2). The prevailing hypothesis for the induction of
thyroid tumors by TCDD involves the disruption of thyroid hormone homeostasis via induction
of Phase II enzymes UGTs in the liver (reviewed in Brouwer et al., 1998, 201801) by an
AhR-dependent transcriptional mechanism (Bock et al., 1998, 548752; Nebert et al., 1990,
548756). This induction of hepatic UGT results in increased conjugation and elimination of
thyroxine (T4), leading to reduced serum T4 concentrations. T4 synthesis is controlled by the

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thyroid stimulating hormone (TSH) which is under negative and positive regulation from the
hypothalamus, pituitary, and thyroid via thyrotrophin-releasing hormone, TSH, T4, and
triiodothyronine. Consequently, the reduced serum T4 concentrations lead to a decrease in the
negative feedback inhibition on the pituitary gland. This would then lead to a rise in secreted
TSH and stimulation of the thyroid. The persistent induction of UGT by TCDD and the
subsequent prolonged stimulation of the thyroid could result in thyroid follicular cell hyperplasia
and hypertrophy of the thyroid, thereby increasing the risk of progression to neoplasia. Increases
in blood TSH levels are consistent with prolonged stimulation of the thyroid and may represent
an early stage in the induction of thyroid tumors identified in animal bioassays. Statistically
significant increases in neonatal blood TSH levels have been recently been reported in children
born to TCDD-exposed mothers in the Seveso cohort (Baccarelli et al., 2008, 197059. discussed
in Section 2.4.1.1.1.4.4). Support for this hypothesis comes from several studies showing that
TCDD decreases serum total thyroxine and free thyroxine concentrations in rats following both
single dose and repeated dose exposures (Bastomsky, 1977, 548760; Brouwer et al., 1998,
201801; Pohjanvirta et al., 1989, 548766; Potter et al., 1983, 548769; Potter et al., 1986, 548771;
Sewall et al., 1995, 198145; Van Birgelen et al., 1995, 198052). Further support comes from
studies of transgenic animals in which TCDD exposure resulted in a marked reduction of total
thyroxin and free T4 levels in the serum of AhR+/- mice but not AhR-/- mice (Nishimura et al.,
2005, 197860). Additionally, gene expression of UGT 1A6, CYP1A1, and CYP1A2 in the liver
was markedly induced by TCDD in AhR+/- but not AhR-/- mice (Nishimura et al., 2005,

197860).

5.1.2.3.4. Summary of TCDD mode of action in rodents.

Overall, there are inadequate data to support the conclusion that any of the particular
mode of action hypotheses described above is operant in TCDD-induced carcinogenesis.
However, the wealth of scientific evidence available indicates that most, if not all, of the
biological and toxic effects of TCDD are mediated by the AhR. Although the receptor may be
necessary for the occurrence of these events, it is not sufficient because other proteins and
conditions are known to affect the activity of the receptor and its ability to alter gene expression
or to induce other effects. Certain studies could be interpreted to indicate AhR-independent
mechanisms, although these studies have not clearly ruled out involvement of the AhR. The

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only consistent, but limited, evidence for TCDD-induced effects that do not involve the AhR
comes from studies using AhR-deficient transgenic animals. Here however, only minor effects
occurred following treatment with extremely high doses of TCDD. Thus, a toxic response to
TCDD has AhR interaction as a key event, but there are various species-, cell-, development-,
gender-, and disease-dependent differences in the cellular milieu that can affect the nature and
extent of the response observed.

The findings that many AhR-modulated effects are regulated with distinct specificity
supports the understanding that the molecular and cellular pathways leading to any particular
toxic event are extremely complex. Precise dissection of these events represents a considerable
challenge, especially in that a toxic response may depend on timely modulation of several genes
rather than of just one particular gene, and possibly modulation of these genes in several rather
than just one cell type or tissue.

While a defined mechanism at the molecular level or a defined mode of action for
TCDD-induced carcinogenicity is lacking, EPA concludes the following

•	interaction with the AhR is a necessary early event in TCDD carcinogenicity in
experimental animals.

•	through interaction with the AhR, TCDD modifies one or more of a number of cellular
processes, such as induction of enzymes, changes in growth factor and/or hormone
regulation, and/or alterations in cellular proliferation and differentiation.

•	AhR activation is anticipated to occur in humans and may progress to tumors. AhR is
present in human cells and tissues, studies using human cells are consistent with the
hypothesis that the AhR mediates TCDD toxicity and no data exist to suggest that the
biological effects of AhR activation by TCDD are precluded in humans.

•	non-AhR mediated carcinogenic effects of TCDD are possible.

5.1.3. Summary of the Qualitative Weight of Evidence Classification for TCDD

Under the 2005 Cancer Guidelines (U.S. EPA, 2005, 086237). TCDD is characterized as
carcinogenic to humans, based on the available data as of 2009. This conclusion is based on

•	Multiple occupational epidemiologic studies showing strong evidence of an association
between TCDD exposure and increased mortality from all cancers.

•	Epidemiological studies showing an association between TCDD exposure and certain
cancers in individuals accidentally exposed to TCDD in Seveso, Italy.

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•	Extensive evidence of carcinogenicity at multiple tumor sites in both sexes of multiple
species of experimental animals.

•	General scientific consensus that the mode of TCDD's carcinogenic action in animals
involves AhR-dependent key precursor events and proceeds through modification of one
or more of a number of cellular processes, such as induction of enzymes, changes in
growth factor and/or hormone regulation, and/or alterations in cellular proliferation and
differentiation.

•	The human AhR and rodent AhR are similar in structure and function and human and
rodent tissue and organ cultures respond to TCDD in a similar manner and at similar
concentrations.

•	General scientific consensus that AhR activation is anticipated to occur in humans and
may progress to cancers.

5.2. QUANTITATIVE CANCER ASSESSMENT

5.2.1. Summary of NAS Comments on Cancer Dose-Response Modeling

5.2.1.1. Choice of Response Level and Characterization of the Statistical Confidence Around
Low Dose Model Predictions

The NAS commented on the low dose model predictions in the 2003 Reassessment,

including EPA's development of ED0i (effective dose eliciting x percent response) estimates for

numerous study/endpoint combinations. The committee also suggested that EPA had not

appropriately characterized the statistical confidence around such model predictions in the low-

response region of the model.

The committee concludes that EPA did not adequately justify the use of the 1%
response level (the ED0i) as the POD for analyzing epidemiological or animal
bioassay data for both cancer and noncancer effects. The committee recommends
that EPA more explicitly address the importance of the selection of the POD and
its impact on risk estimates by calculating risk estimates using alternative
assumptions (e.g., the ED0s) (NAS, 2006, 198441. p. 18)

It is critical that the model used for determining a POD fits the data well,
especially at the lower end of the observed responses. Whenever feasible,
mechanistic and statistical information should be used to estimate the shape of the
dose-response curve at lower doses. At a minimum, EPA should use rigorous
statistical methods to assess model fit, and to control and reduce the uncertainty of
the POD caused by a poorly fitted model. The overall quality of the study design
is also a critical element in deciding which data sets to use for quantitative
modeling (NAS, 2006, 198441. p. 18).

EPA should ... assess goodness-of-fit of dose-response models for data sets and
provide both upper and lower bounds on central estimates for all statistical

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estimates. When quantitation is not possible, EPA should clearly state it and
explain what would be required to achieve quantitation (NAS, 2006, 198441. p.
10).

The NAS also suggested that EPA report information describing the adequacy of dose-
response model fits, particularly in the low-response region. For those cases where biostatistical
modeling was not possible, the NAS recommended that EPA identify the reasons.

The Reassessment should also explicitly address the importance of statistical
assessment of model fit at the lower end and the difficulties in such assessments,
particularly when using summary data from the literature instead of the raw data,
although estimates of the impacts of different choices of models would provide
valuable information about the role of this uncertainty in driving the risk estimates
(NAS, 2006, 198441. p. 73).

5.2.1.2. Model Forms for Predicting Cancer Risks Below the Point of Departure (POD)

The NAS focused much of its review on EPA's derivation of a cancer slope factor.
Specifically, the NAS commented extensively on the selection of the appropriate point of
departure (POD) and the extrapolation of dose response modeling below the POD.

The NAS questioned EPA's choice of a linear, nonthreshold model for extrapolating risk
associated with exposure levels below the POD, concluding that the current scientific evidence
was sufficient to justify the use of nonlinear methods when extrapolating below the POD for
TCDD carcinogenicity. The committee further recommended that EPA include a nonlinear
model for low dose cancer risk estimates as a comparison to the results from the linear model.

The committee concludes that EPA's decision to rely solely on a default linear
model lacked adequate scientific support. The report recommends that EPA
provide risk estimates using both nonlinear and linear methods to extrapolate
below PODs(NAS, 2006, 198441. p. 5).

After reviewing EPA's 2003 Reassessment and additional scientific data
published since completion of the Reassessment, the committee unanimously
agreed that the current weight of scientific evidence on the carcinogenicity of
dioxin is adequate to justify the use of nonlinear methods consistent with a
receptor-mediated response to extrapolate below the POD. The committee points
out that data from NTP released after EPA generated the 2003 Reassessment
provide the most extensive information collected to date about TCDD
carcinogenicity in test animals, and the committee found the NTP results to be

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compelling. The committee concludes that EPA should reevaluate how it models
the dose-response relationships for TCDD... (NAS, 2006, 198441. p. 16).

Because EPA's assumption of linearity at doses below the 1% excess risk level
for carcinogenic effects of TCDD, other dioxins, and DLCs is central to the
ultimate determination of regulatory values, it is important to critically address the
available scientific evidence on the most plausible shape of the dose-response
relationship at doses below the POD (LED0i). On the basis of a review of the
literature, including the detailed review prepared by EPA and presented in Part II
of EPA's Dioxin Risk Assessment and new literature available since the last EPA
review, the committee concludes that, although it is not possible to scientifically
prove the absence of linearity at low doses, the scientific evidence, based largely
on mode of action, is adequate to favor the use of a nonlinear model that would
include a threshold response over the use of the default linear assumption (NAS,
2006, 198441. p. 122).

On the whole, the committee concluded that the empirical evidence supports a
nonlinear dose-response below the ED0i, while acknowledging that the possibility
of a linear response cannot be completely ruled out. The Reassessment
emphasizes the lack of such nonlinear models, hence its adoption of the approach
of linear extrapolation below the POD level. Although this approach remains
consistent with the cancer guidelines (U.S. EPA, 2005, 086237; see also
Appendix B), EPA should acknowledge the qualitative evidence of nonlinear dose
response in a more balanced way, continue to fill in the quantitative data gaps,
and look for opportunities to incorporate mechanistic information as it becomes
available. The committee recommends adopting both linear and nonlinear
methods of risk characterization to account for the uncertainty of dose-response
relationship shape below ED0i (NAS, 2006, 198441. p. 72).

5.2.2. Overview of EPA Response to NAS Comments on Cancer Dose-Response Modeling

EPA agrees with the NAS that the approaches to cancer dose-response modeling for
TCDD should be clearly communicated and justified. Furthermore, due to the abundance of new
information on TCDD carcinogenicity published since the 2003 Reassessment, EPA has
reevaluated the cancer dose-response modeling for TCDD presented in the 2003 Reassessment.
As detailed below in Section 5.2.3, EPA has conducted an updated cancer dose-response
assessment for TCDD that incorporates key NAS recommendations discussed in this document,
reflects the current state-of-the science in cancer dose-response modeling and integrates new
TCDD carcinogenic information. Detailed responses to the NAS comments summarized above
are found in Section 5.2.3.3.

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The 2003 Reassessment presents an extensive dose-response assessment of TCDD and
provides a comprehensive summary of dose-response relationships. The analyses and
discussions synthesized a considerable breadth of data and model types, highlighting the
strengths and weaknesses of the then-available scientific information. Modeling included both
administered dose and steady state body burden dose metrics, taking into account variation in
half-lives of TCDD across species. These body burden calculations used a simple one-
compartment kinetic model based on the assumption of a first-order decrease in the levels of
administered dose as a function of time. An excess risk of 1% was chosen to model the cancer
data, but comparative results were also shown for 5% and 10% excess risk (see Table 8-2 of the
2003 Reassessment). Dose response was also explored thoroughly for a number of in vitro and
biochemical endpoints in addition to the in vivo data analyses, and ranges of these values were
presented (see Figures 8-1, 8-2 and 8-3 of the 2003 Reassessment). Thus, the 2003
Reassessment provides an initial evaluation of the carcinogenic database for TCDD and serves as
the foundation for the analyses presented below.

5.2.3. Updated Cancer Dose-Response Modeling for Derivation of Oral Slope Factor

The following sections describe the dose-response analysis of the cancer data from
epidemiologic cohort studies (see Section 2.4.1 and Table 2-4) and rodent bioassays (see
Section 2.4.2 and Table 2-6), concluding with the derivation of oral slope factors for TCDD
based on epidemiologic data (see Section 5.2.3.1) and rodent bioassay data (see Section 5.2.3.2).

5.2.3.1. Dose-Response Modeling Based on Epidemiologic Cohort Data

The 2003 Reassessment included dose-response analyses and the development of oral
slope factors from the following three occupational cohorts: the NIOSH cohort, the Hamburg
cohort, and the BASF cohort. In this document, EPA determined that specific studies from each
of these cohorts (Becher et al., 1998, 197173; Ott and Zober, 1996, 198408; Steenland et al.,
2001, 198589) met the epidemiologic study inclusion criteria (see Section 2.3.1 and
Section 2.4.1). In Section 5.2.3.1.1, the oral slope factors derived from these studies in the 2003
Reassessment are reviewed. Another study that met the current epidemiologic study inclusion
criteria (Warner et al., 2002, 197489) was also briefly discussed in the 2003 Reassessment, but
an oral slope factor was not derived from that study. In Section 5.2.3.1.2.2, EPA discusses its

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unsuccessful attempt to use the categorical results published by (Warner et al., 2002, 197489) to
develop an oral cancer risk estimate.

Since the publication of the 2003 Reassessment, additional cancer epidemiologic studies
based on these cohorts have been published in the peer-reviewed literature. Of these, Collins et
al. (2009, 197627) and Cheng et al. (2006, 523122) met the epidemiologic study inclusion
criteria (see Section 2.3.1 and Section 2.4.1). In Section 5.2.3.1.2, EPA evaluates the suitability
of deriving an oral slope factor from the Cheng et al. (2006, 523122) study and derives oral slope
factor estimates. Although the Collins et al. (2009, 197627) study met the study inclusion
criteria, EPA could not derive an oral slope factor from that study. In Section 5.2.3.1.2.3, EPA
discusses why an oral cancer risk estimate was not developed using the positive results for the
soft-tissue sarcoma mortality published by Collins et al. (2009, 197627).

5.2.3.1.1. Evaluation of Epidemiologic Studies Used in the 2003 Reassessment for OSF
Derivation.

In the 2003 Reassessment, EPA reported dose-response modeling results for three
epidemiologic studies of human occupational cohorts: the NIOSH cohort with data published by
Steenland et al. (2001, 198589); the Hamburg cohort with data published by Becher et al. (1998,
197173); and the BASF cohort with data published by Ott and Zober (1996, 198408). Each of
these studies is summarized in Section 2.4.1 of this document and in the 2003 Reassessment
(Part II, Chapter 8; Part III, Chapter 5). Furthermore, EPA has evaluated the suitability of these
studies for use in TCDD dose-response modeling and concluded that each of these studies meet
the inclusion criteria for epidemiology studies presented in Section 2.3.1.

Each of these studies reports all cancer mortality as an outcome. Steenland et al. (2001,
198589) and Becher et al. (1998, 197173) analyzed cohorts of primarily male workers who
experienced occupational exposures to TCDD over long periods of time, while Ott and Zober
(1996, 198408) studied a cohort of primarily male workers who were exposed to high TCDD
concentrations at a single point in time due to an industrial accident.

The authors of all three of these studies measured, and then back-extrapolated, TCDD
levels in a subset of workers to estimate exposures during employment and then the authors used
this information to estimate exposures in the remainder of the cohort. These measured TCDD
samples generally were collected decades after the last known occupational exposure. In each

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study, the authors relied on TCDD measures in the cohort to back-calculate serum lipid or body
fat levels of TCDD using a simple one-compartment kinetic model based on the assumption of a
first-order decrease in the levels of exposure dose as a function of time. The assumed half-life of
TCDD used in the models varied from study to study. None of the studies sampled TCDD levels
from the entire cohort; for example, Ott and Zober collected samples from 138/243 workers
(57% of the cohort), which was the highest percentage of workers sampled among the three
studies. Steenland et al. (2001, 198589) and Becher et al. (1998, 197173) used the measured and
back-extrapolated TCDD concentrations to estimate the exposures that were associated with
various occupations within the cohort, and subsequently used this information to develop
exposure matrices (i.e., the TCDD load per unit time for an occupation) that then could be used
to estimate the cumulative dioxin dose for each cohort member. Ott and Zober (1996, 198408)
used regression procedures with data on time spent at various occupational tasks to estimate
TCDD levels for all members of the cohort. Following the estimation of worker exposures in
each of these three studies, the studies' authors divided these cohorts into exposure subgroups
based on the estimated TCDD levels.

In the 2003 Reassessment, EPA identified a POD based on a 1% response in cancer
mortality (ED0i) for the Steenland et al. (2001, 198589). and the Ott and Zober (1996, 198408)
studies. EPA extrapolated from this POD to lower doses using a straight line drawn from the
POD to the origin—zero incremental dose, zero incremental response—to give a probability of
extra risk. Because there was insufficient evidence to support an assumption of nonlinearity,
EPA chose to develop these models using a linear model.

5.2.3.1.1.1. Steenland et al. (2001,19S5S9).

Steenland et al. (2001, 198589) developed dose-response models based on TCDD
exposures and all cancer mortalities from eight plants in the NIOSH cohort (see Section
2.4.1.1.1.1.3 for study details). Serum lipid levels of TCDD in 1988 were measured in
193 workers at one of these plants. Steenland and coauthors relied on a first-order kinetic model
(assuming a constant 8.7 year half-life) to back-extrapolate to serum TCDD levels at the time of
the last occupational exposure. The study authors assigned exposure estimates to each of the
3,538 workers in the cohort based on a job-exposure matrix. This matrix was based on (1) an
estimated level of contact with TCDD, (2) the degree of TCDD contamination of the products

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the workers produced, and (3) the fraction of a workday during which the worker likely
contacted the TCDD-contaminated products. They then estimated each worker's serum TCDD
levels as an area under the concentration curve (AUC) for lipid-adjusted serum levels over time.
The mortality analysis was conducted on 256 cancer decedents.

Several different dose-response models were fit to these data to provide estimates of fatal
cancer risk. The best-fitting model was a Cox regression exposure-response model using the
log(AUC) of TCDD lipid concentration (ppt-year) lagged by 15 years as the exposure metric.
Steenland and colleagues also developed a piecewise linear regression model with no lag, in
which two separate linear slopes were estimated. This analysis assumed a background exposure
of 0.5 pg/kg-day. The lipid concentrations were converted to body burdens by dividing by 4.
The central tendency estimate and lower bound ED0iS from the piecewise linear model and their
associated cancer slope factors for the most sensitive endpoint (male cancer mortality) are
presented in Table 5-1.

5.2.3.1.1.2. Becheretal. (1998.197173).

Based on the Hamburg cohort, Becher et al. (1998, 197173) reported a dose-response
analysis for all fatal cancers combined (see Section 2.4.1.1.1.3.4 for study details). The mortality
analysis was conducted in 1992 on 124 cancer decedents. The exposure variable in the study
was the integrated blood levels for TCDD concentration over time (AUC, ng/kg-years), as
estimated by Flesch-Janys et al. (1998, 197339); these were converted to body burdens by
dividing by 4. Estimates of the half-life of TCDD, based on the sample of 48 individuals with
repeated measures, were incorporated into a model that back-extrapolated TCDD exposures to
the end of the employment after accounting for the workers' ages and body fat percentages.

These estimated exposure measures were then applied to the entire cohort, which consisted of all
1,189 regular male employees who were employed for at least 3 months between 1952 and 1984
at the Boehringer chemical plant in Hamburg, Germany.

Becher et al. (1998, 197173) used a Cox regression approach for the dose-response
modeling and developed three models: a multiplicative model, an additive model, and a power

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model.32 The response variable in each model was the SMR for total cancer mortality. The
models were calculated with lag times of up to 20 years. The multiplicative model provided the
best fit; however, the study authors judged the fits for all three models to be acceptable. The
model results were used to calculate unit risk estimates derived as the risk of cancer death
through age 70 given a daily dose of 1 pg/kg body weight of TCDD minus the risk given no
exposure to TCDD. These calculations were based on background German cancer mortality
rates. The model results were used to calculate cancer risk estimates. The lower bound
estimates on the dose were not available for models published by Becher et al. due to the absence
of statistical parameter measures. The central tendency estimate ED0is from the three statistical
models and their associated cancer slope factors are presented in Table 5-1.

5.2.3.1.1.3. Ott and Zober (1996.198408).

In the 2003 Reassessment, EPA also developed a dose-response analysis based on a study
reported by Ott and Zober (1996, 198408) for cancer incidence and mortality experienced by
243 men, who were exposed to TCDD in 1953 during an accident at the BASF plant in Germany
(see Section 2.4.1.2.1.2.1 for study details). The cohort was followed through 1992. TCDD
blood lipid levels were available for 138 of these men 30 years after the accident. These levels
were back-extrapolated and used to estimate the AUC for TCDD. Body burdens (ng/kg) were
estimated by dividing AUC by 4, and steady-state body burdens were estimated assuming a
constant half-life of approximately 7.1 years.33 Ott and Zober (1996, 198408) used Cox
proportional hazard approaches to estimate both cancer incidence and cancer mortality risk per

32The "multiplicative model" set relative risk (RR) equal to exp(fid), where the dose d is the AUC. The "additive
model" set RR = 1 +fid. and the "power model" set RR = exp(/? log (kd+\)). The values /; and k are estimated
parameters.

33Based on the initial body burden (B0) EPA estimated the body burden at time t using the following formula:

k t

B(t) = B0e c . where ke is an elimination constant equal to ln(2)/(half-life in years). This implies that the AUC at

Br -k T

time T after initial exposure is A UC = — (1 -e e ). T in this case was 39 years (time from the accident in 1953 to

K

the follow-up in 1992). Dividing by a lifetime of 71 years (mean age in 1954, 33 years, plus 38 years from 1954 to
the followup in 1992) yields the lifetime mean body burden as:

D	i

B =	°—(\-e<> \. In the 2003 Reassessment, EPA converted the steady-state body burden to units of equivalent

mean _, , ^	'

i\ke

1	k T

initial dose by dividing by the constant	(l - e e ). With the given values for half-life and T, that constant is

l\ke

0.1411 and l/(the constant) is 7.09.

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unit TCDD dose.34 Ott and Zober reported conditional risk ratios for cancer mortality that were
slightly larger than the conditional risk ratios for cancer incidence, which is counter-intuitive.
The risk of cancer mortality would be expected to be greater than the risk of cancer incidence.
The conditional risk ratio (and 95%CI) for all cancer mortality (1.22; 1.00-1.50) exceeded the
conditional risk ratio for all incident cancer cases (1.11; 0.91-1.35). Similarly, the conditional
risk ratios for digestive cancer mortality (1.46; 1.13-1.89) and respiratory cancer mortality (1.09;
0.70-1.68) were also both larger than the conditional risk ratios for all digestive cancers (1.39;
1.07-1.69) and all respiratory cancers (1.02; 0.65-1.59). As expected, in this cohort, incident
cases exceeded cancer mortality for total cancers (47 vs. 31), digestive cancers (12 vs. 11) and
respiratory cancers (13 vs. 11). Ott and Zober also reported that conditional risks for mortality
for all cancer and lung cancer associated with cigarette smoking were also higher than the
respective incidence risks. In their Cox regression analysis, Becher et al. (1998, 197173) also
report that the regression coefficient for total cancer mortality (0.0096) was slightly larger than
the regression coefficient for total cancer incidence (0.0089). The finding of Ott and Zober and
Becher et al. that the risk of cancer mortality is greater than cancer incidence is possibly due to a
systematic difference in the reference population for incidence vs. the reference population for
mortality. The central tendency estimate and lower bound ED0iS from the modeling and their
associated cancer slope factors are presented in Table 5-1.

5.2.3.1.2. Evaluation of Other Epidemiologic Studies Considered for OSF Derivation.

Three additional epidemiologic studies that met the study inclusion criteria (see
Section 2.3) for use in dose response modeling as set forth in this document are evaluated in this
section for the estimation of cancer risk estimates. These studies were either published after the
Reassessment (Cheng et al. (2006, 523122) and Collins et al., (1996, 197637)). or not used to
derive an OSF in the Reassessment (Warner et al., 2002, 197489). Each study is summarized in
Section 2.4.1.

34The model from Ott and Zober has risk proportional to d"''c with [i = ln(1.22). The corresponding slope for the

mean (steady-state) body burden is 7.0851 * log(1.22) * 0.001 (the 0.001 converts nanograms to micrograms).

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5.2.3.1.2.1. Chens et al. (2006. 523122).

As discussed in Section 2.4.1.1.1.1.4, Cheng et al. (2006, 523122)) analyzed the
relationship between TCDD dose and all cancer mortality for the same subset of NIOSH workers
as analyzed previously by Steenland et al. (2001, 198589). In contrast to Steenland et al., Cheng
et al. (2006, 523122) used the "concentration- and age-dependent elimination model"
(concentration- and age-dependent elimination [CADM], discussed in Section 3.3; see also
Ay 1 ward et al. (2005, 197114)), rather than a constant 8.7-year half-life, and calculated serum-
derived TCDD estimates for use in dose-response analysis. An important feature of CADM is
that it incorporates concentration- and age-dependent elimination of TCDD from the body,
meaning that the effective half-life of TCDD elimination varies based on exposure history, body
burden, and age of the exposed individuals. As discussed in Section 3.3, the use of the CADM
model to simulate TCDD kinetics in the NIOSH cohort results in time-integrated body burden
estimates four to five times greater than those obtained with the simple first-order model, with
smaller differences between the two methods at lower exposures.

Following the estimation of dose using the CADM-derived AUC values, Cheng and
colleagues (Cheng et al., (2006, 523122); the "Cheng analysis") derived dose-response estimates
for the NIOSH cohort using linear Cox regression for both lagged and un-lagged exposure on
various subsets of the data (high-exposures trimmed). The results for the lagged-exposure
analysis are summarized in Table 5-2. For comparison, the Cox regression coefficient from the
analysis conducted by Steenland et al. (2001, 198589), which relied on a first-order elimination
rate model assuming a constant 8.7-year half-life, is also shown in the table. As in Steenland et
al. (2001,198589),35 Cheng et al. (2006, 523122) found a much stronger relationship between
cancer mortality and exposure metrics lagged 15 years compared to the relationships for
unlagged exposures. Cheng et al. (2006, 523122) also noted that the dose-response relationship
plateaued above the 95th percentile of exposure. For exposures lagged 15 years, the regression
coefficient (P) of the linear slope derived by Cheng et al. (2006, 523122) was 3.3 x 10~6 per
ppt-year lipid-adjusted serum TCDD, with a standard error of 1.4 x 10 6 (Table III of Cheng et
al. (2006, 523122)). The upper 5% of the exposure range (individuals >252,950 ppt-year lipid
adjusted serum TCDD) was excluded in estimating this slope. Because this exclusion reduces

35 Lagged exposures modeled only for log-transformed serum concentrations, not for untransformed serum
concentrations in the piece-wise linear model.

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the upper portion of the response where the slope is shallow36, this likely better represents the
slope in the region of the curve where the fatal cancer risk is increasing with dose, which is the
equivalent of dropping the highest dose in an animal bioassay or using a piece-wise linear model
as in Steenland et al. (2001, 198589).

To develop cancer risks for TCDD, EPA used the modeling results of the Cheng analysis,
with conversion to oral intake using the Emond human PBPK model as follows. The slope (ft)
from the Cheng analysis is the slope of the linear relationship between the natural logarithm of
the rate ratio (RR) and the cumulative fat TCDD concentration (fat-AUC). Conceptually, the
slope (P) is similar to an OSF, except that it is expressed in terms of fat-AUC rather than intake.
Also, the slope represents the incremental increase in cancer mortality (expressed as an RR)
above the background TCDD exposure experienced by the NIOSH cohort rather than above zero.
Using the upper 95% bound on (J> and assuming that the slope is the same below the NIOSH
cohort background exposure level (approximately 5 ppt/yr TCDD fat concentration), EPA
calculated risk-specific doses (as daily oral intakes) for TCDD for risk levels of concern to EPA.
The risk-specific doses were estimated from the Emond human PBPK model for the lifetime-
average TCDD fat concentrations corresponding to the fat-AUC predicted by the Cheng et al.
model for each of the risk levels of concern. The steps in this computation are as follows:

•	Background cancer mortality risk estimate (Ro). EPA used an R0 of 0.112 as reported by
Cheng et al. (2006, 523 122)37

•	Total cancer mortality risk in the exposed group associated with a specified (extra) risk
level (RL) of fatal cancer (TRw). A TRm associated with any given extra risk level (e.g.,
0.01, 1 x 10"6) can be calculated using the following relationship for extra risk:

ER = TRrl ~ Rq	(Eq 5_^

\-R0

36	Steenland et al. (2001, 1985891: Steenland and Deddens (2003, 1985871 found a slightly negative slope for the
higher exposures, stating that the phenomenon could be a result of exposure misclassification, depletion of
susceptible individuals or saturation of receptor-mediated processes.

37	In Table IV, Cheng et al. (2006, 5231221 report two estimates of background fatal cancer risk. R0, for males aged
75 years: 0.112 and 0.124. A R0 estimate of 12.4% was used by Steenland et al. (2001, 198589). and 11.2%, as
estimated for all males in the 1999-2001 Surveillance Epidemiology and End Result data set. EPA chose to use the
more recent estimate of 11.2% for the purpose of predicting risk in the current U.S. population.

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• Incremental cancer mortality risk in the exposed population based on a given extra risk

(Rn). Rd, is calculated as the difference between the total risk and background risk and
expressed in terms of RL and R0 by combining Equations 5-2 and 5-1.

Rd = TRrl-R0	(Eq. 5-2)

RD = RLx (\-R0)	(Eq. 5-3)

•	Cumulative TCDD concentration in the fat compartment for a given extra risk (AUCrt
AUCrl is then calculated by taking the natural logarithm of Equation 3 from Cheng et al.
(2006, 523122). rearranging and substituting for RR38 (RR = [RD + R0]/Ro):

AUCrl = In((Rd + R0)IRo)lp*	(Eq. 5-4)

where /?* is the central-tendency regression slope or the 95% upper bound (figs)
determined by summing the regression coefficient (P) and the product of 1.96 and the
standard error of the regression coefficient, yielding an estimate of 6.0 x 10 6 per
ppt-year lipid adjusted serum TCDD, as follows:

P95 = p + \.96*SE	(Eq. 5-5)

•	Continuous daily TCDD intake associated with a given extra risk TDrt 1. Because the fat
concentrations generated by CADM are not linear with oral exposure at higher doses, a
single oral slope factor to be used for all risk levels cannot be obtained; the response is
approximately linear with fat concentrations and oral intake at lower doses. Instead, a
risk-specific DRL must be estimated by converting the respective AUCrl to the
corresponding lifetime daily intake, using an appropriate human toxicokinetic model.
EPA has chosen to use the Emond human PBPK model for this purpose because the
CADM configuration does not facilitate this process and so that the dose conversions are
consistent with those used in the derivation of the RfD. A DRL is obtained from the
Emond model by finding the average lifetime daily intake corresponding to the AUCrl in
the fat compartment.39

Note that there are two nonlinear steps in the estimation of risk-specific doses from the
Cheng et al. model. First, fat-AUC {AUCrl) and the incremental cancer mortality risk (RD) do

38	As defined by Cheng et al. (2006, 523122. p. 1063).

39	Although the NIOSH cohort exposures are reported as LASC, they are treated as fat concentrations in the Cheng
analysis because fat in all tissues are modeled as one compartment (hence equal) in CADM. The translation to oral
intake in the Emond model is from the fat compartment, rather than the serum compartment, even though the serum
and fat compartments are not equivalent, because the regression slope ((3) in the Cheng analysis is in terms of the
(equivalent) fat compartment.

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not have a linear relationship (see Eq. 5-5); however, the relationship becomes virtually linear
below an incremental risk of 10"3 (see Table 5-3). Second, TCDD fat concentration is not linear
with oral intake in the Emond human PBPK model (see Section 3); this relationship also is close
to linear below the 10"5 risk level. The resulting predicted cancer-mortality risk is approximately
linear with daily oral intake at low doses. Table 5-3 shows the AUCrl and DRL based on the
95% upper-bound regression slope {figs) from the Cheng analysis for a number of risk levels of
interest to the EPA. For comparative purposes, EPA has also shown the equivalent oral slope
factor (RL +Drl) for those same risk levels. Table 5-4 also shows analogous results based on
the best estimate of regression coefficient (fi = 3,3 x 10 6) for total fatal cancers from the Cheng
analysis.

5.2.3.1.2.2. Warner et al. (2002.197489).

Warner et al.(2002, 197489) is a study of 981 females exposed to elevated TCDD levels
following the Seveso accident of 1976 (see Section 2.4.1.1.1.4.2 for study details). The TCDD
exposure pattern involving a single period of elevated TCDD exposures followed by an extended
period of lower ambient level TCDD exposures and elimination is similar to that of the BASF
cohort (Ott and Zober, 1996, 198408). TCDD levels, measured or estimated in blood lipids
shortly after the time of the accident, were available for all women. These women were divided
into four exposure groups of <20, 20-44, 44.1-100, and >100 ppt. In this cohort, 21 total
cancers have been observed; 15 of these were breast cancer cases and 3 were thyroid cancer
cases. Cox proportional hazards modeling showed that the hazard ratio for breast cancer
associated with a 10-fold increase in serum TCDD levels (logio (TCDD)) was significantly
increased to 2.1 (95% CI = 1.0-4.6). Rate ratios (95% CI) for cancer incidence in these 4 groups
were 1.0, 1.0 (0.2-5.5), 2.2 (0.5-10.8) and 2.5 (0.5-11.8). Using a Cox proportional hazards
model and assuming continuous exposure, the rate ratio was 1.7 (0.9-3.4) for each 10-fold
increase in serum TCDD; that is, a logio transformation of the exposure estimates in their
analysis was presented. They reported a test for trend ofp = 0.09.

EPA attempted to estimate an ED0i from the modeled results of Warner et al. (2002,
197489) from the statistically significant hazard ratio for breast cancer. However, EPA had to
estimate the slope of the tangent to the log-linear relationship. Because the exponentiated slope
of a log-dose linear relationship is not constant but varies with dose, and because the lowest

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exposure measure was well-above the 1% response region of interest, EPA could not confidently
estimate the tangent to the log-dose linear relationship. The transformation of the logio dose
units to linear units of TCDD yielded an implausibly low EDoi and correspondingly high cancer
risk that was inconsistent with a visual inspection of the untransformed plot. EPA was not
confident in these values for health risk assessment because of uncertainties in the transformation
in the low response region of the original model. Thus, EPA did not derive an ED0i or oral slope
factor for this study.

5.2.3.1.2.3. Collins et al. (2009.197627).

Collins et al. (2009, 197627s) investigated the relationship between serum TCDD levels
and mortality rates in the NIOSH cohort (see Section 2.4.1.1.1.1.5 for study details). The
investigators completed an extensive dioxin serum evaluation of workers employed by the Dow
Chemical plant in Midland, Michigan, that made 2,4,5-trichlorophenol (TCP) from 1942 to 1979
and 2,4,5-T from 1948 to 1982. Collins et al. (2009, 197627) developed historical TCDD
exposure estimates for all 1,615 workers using serum samples from 280 former workers that
were collected during 2004-2005. Investigators calculated a cumulative measure of exposure
using a simple one-compartment first-order pharmacokinetic model and elimination rates as
estimated from the BASF cohort (Flesch-Janys et al., 1996, 197351). The follow-up interval for
these workers covered the period between 1942 and 2003. Thus, the study included 10 more
years of follow-up than earlier investigations of the entire NIOSH cohort. A key limitation of
this study is that the derivation of the SMRs and slope parameters did not include a lag period,
unlike other analyses of the NIOSH cohort (e.g., Cheng et al., 2006, 523122; Steenland et al.,
2001, 198589).

Although results were largely negative, statistically significant mortality in the cohort
was found for soft-tissue sarcoma (SMR = 4.1, 95% CI = 1.1-10.5), based on only four deaths.
A regression coefficient of 0.05872 (standard error not reported), and a hazard ratio of 1.060
(95% CI = 1.017 to 1.106) were reported by Collins et al. (2009, 197627) for soft-tissue sarcoma.
Although it met the dose-response study criteria, EPA could not calculate an upper bound on the
regression coefficient because the standard error was not given. In addition, EPA was unable to
estimate an extra-risk value because the reference population response was not specified. Thus,
EPA did not derive an ED0i or oral slope factor for this study.

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5.2.3.2. Dose-Response Modeling Based on Animal Bioassay Data

Figure 5-3 provides a summary of the process EPA has utilized to select and identify
candidate TCDD OSFs from key animal bioassays that were identified in Section 2.4.3 of this
document. For each in vivo animal cancer study that qualified for TCDD dose-response
assessment using the study inclusion criteria specified in Section 2.3.2, EPA first selected the
species/sex/tumor data set combinations that had been characterized as having statistically
significant increases in tumor incidence by either a pair-wise test between the treated group and
the controls or by a trend test showing increases in tumors with increases in dose. Next, EPA
used the Emond animal kinetic model discussed in Section 3 to estimate blood concentrations
corresponding to each study's average daily administered doses for use in dose response
modeling. Benchmark dose lower confidence bounds (BMDLois) were then estimated for the
blood concentrations by (1) using the multistage cancer model for each species/sex/tumor
combination within each study and (2) using a Bayesian Markov Chain Monte Carlo framework
that assumes independence of tumors, modeling all tumors together for each species/sex
combination within each study. The final selected models were subjected to goodness-of-fit tests
and visual inspections of fit to the raw data. Thus, for each sex/species combination within each
study, this process generated a BMDLoi for each single tumor type and another BMDLoi for the
combined tumors. Finally, using the Emond human kinetic model discussed in Section 3, human
equivalent doses (BMDLreds) were then estimated for each of the BMDLois and, using a linear
extrapolation, OSFs were calculated by OSF = 0.01/BMDLHed- The highest OSF for a
species/sex combination for either a single tumor type or all combined tumors was selected as a
candidate OSF for TCDD cancer assessment. These steps in Figure 5-3 are further described in
detail in the following sections.

5.2.3.2.1. Selection of key data sets.

Based on the study selection criteria outlined in Section 2.3.2 (see Figure 2-3), EPA
selected five animal bioassays for use in the cancer dose-response assessment for TCDD (see
Table 2-6 and Section 2.4.2 for detailed study descriptions). Four of these studies (Delia et al.,
1987, 197405; Kociba et al., 1978, 001818; NTP, 1982, 594255; Toth et al., 1979, 197109). were
evaluated in the 2003 Reassessment, while one study (NTP, 2006, 543749) was published after
the 2003 Reassessment was released. The NTP (2006, 543749) study was specifically called out

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by the NAS (2006, 198441)) report as cancer bioassay data that EPA should evaluate prior to
completing its TCDD dose-response assessment. As discussed below, EPA has chosen to
conduct dose-response modeling for a number of tumor types from each of the sex/species
combinations in these studies in order to maximize the amount of information available to
support OSF derivation. Because tumors occurred in multiple sites in the exposed animals, each
tumor type was considered separately (individual tumor models) and were also combined into
composite tumor incidence dose estimates (multiple tumor models).

The tumor incidence tables for these five bioassays are shown in Tables 5-5 through 5-14
(see Section 2.4.2 for details of these studies). The data in these tables are summarized from
each study's reference publication and are the species/sex/tumor incidence data used for TCDD
dose-response modeling in this report. EPA selected the animal bioassay data sets in Tables 5-5
through 5-14 because they had been characterized by the study authors as having statistically
significant increases in tumor incidence by either a pair-wise test between at least one treated
group and the controls or by a trend test showing increases in tumors with increases in dose. An
exception was made for cases where statistical significance was found in only one dose group
that was not the highest dose group, and there were zero responses in every other dose group
including controls; these datasets were not modeled. For example, in NTP (2006, 543749), EPA
notes that while the uterine tumors were statistically significant at 46 ng/kg using a pair-wise
test, there were no uterine tumors in any other dose group, including the control and high dose
groups, and the trend test was not significant; EPA excluded this tumor type from the analysis.
In addition, datasets with combined tumors for the same site were given priority over subsets of
tumors for that site. For example, in the NTP (1982, 594255) study on female mice, data on
combined hepatocellular adenomas or carcinomas were modeled, but not data on hepatocellular
adenomas alone (not statistically significant) or on hepatocellular carcinomas alone (statistically
significant trend and high dose group). In the case of the Kociba et al. (1978, 001818) female rat
combined hepatocellular adenomas and carcinomas only, EPA used data from a reanalysis of the
pathology slides that was published by Goodman and Sauer (1992, 197667); because the study
authors did not statistically analyze the revised tumor incidence data from their reanalysis, EPA
applied a Fischer's Exact Test to evaluate the statistical significance of those data. In the case of
the NTP (2006, 543749) study only, information was available regarding the length of time that
the animals stayed on test (105 weeks); animals who died within the first year were censored

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from analysis in this document because animals who died within the first year were not
considered to have been alive long enough to develop tumors. Therefore, those animals were not
included in the denominators in Table 5-11. These adjusted incidence data were used in the
analysis of tumor dose-response for NTP (2006, 543749) in this document. The tumor incidence
data in Tables 5-5 through 5-14 include

•	nasal, tongue and adrenal tumors in males (Table 5-5), and liver, nasal and lung tumors in
females from the Kociba et al. (1978, 001818) 2-year study of Sprague-Dawley rats
(Table 5-6),

•	subcutaneous tissue, liver, adrenal and thyroid tumors in females (Table 5-7) and liver,
thyroid and adrenal tumors in males (Table 5-8), from the NTP (1982, 594255) 2-year
study of Osborne-Mendel rats,

•	subcutaneous tissue, hematopoietic system, liver and thyroid tumors in females
(Table 5-9), and lung and liver tumors in males, from the NTP (1982, 594255) 2-year
study of B6C3Fi mice (Table 5-10),

•	liver, oral mucosa, pancreas and lung tumors in females from the NTP (2006, 543749) 2-
year study of Sprague-Dawley rats (Table 5-11),

•	liver tumors in males from the Toth et al. (1979, 197109) 1 -year study of Swiss/H/Riop
mice (Table 5-12), and

•	liver tumors in males (Table 5-13) and females from the Delia Porta et al. (1987, 197405)
52-week study of B6C3Fimice (Table 5-14).

For each cancer endpoint, the reported (administered) doses from each study were converted,
where necessary, to average daily doses in ng/kg-day (e.g., doses administered 5 days/week were
adjusted by multiplying by 5 and dividing by 7 to get average daily doses). These doses were
then subjected to kinetic modeling to generate blood concentrations for use in TCDD dose-
response modeling.

5.2.3.2.2. Dose adjustment and extrapolation methods for selected data sets.

5.2.3.2.2.1. Dose metric estimation for dose-response modelin2.

Tables 5-5 through 5-14 show the blood concentrations that were used in TCDD dose-
response modeling of the animal bioassay data. Based on kinetic analysis (see Section 3), a
choice for whole blood concentration of TCDD was made for the purpose of dose extrapolation
between animals and humans. In order to estimate blood concentrations for each study selected,

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the Emond PBPK model was run using ACSLX® software, version 2.5.0.6 (see Section 3).
Depending on the selected study, either rat or mouse versions of the model were used. In each
case, the simulation was performed using the exposure and observation durations, the body
weights, and the adjusted doses from the original studies. Details of PBPK model input
parameters are given for each study's m-file in Appendix C.2. In the case of Toth et al. (1979,
197109) study, which dosed the animals for a year and then followed up for the lifetime of the
animal, only the one-year simulation was performed. The m-files were used to run the
appropriate PBPK model to estimate time-averaged, maximum, and terminal (end of exposure)
blood concentration (see Appendix C.3). Other model simulated dose metrics such as
concentrations for liver, fat, Ah-receptor bound in liver, body burden, and the time at which the
maximum concentration was reached for each dose metric are also reported for illustrative
purposes in Appendix C.3. The complete results for each study modeled are shown in
Appendix C.3.

5.2.3.2.2.2. Calculation of human equivalent doses (HEDs).

Human equivalent doses (ng/kg-day), corresponding to each BMDL (ng/kg) were
calculated using the Emond human PBPK model (see Section 3) and are denoted as BMDLreds.
The Emond human PBPK model was run for 70 years assuming a constant daily dose starting
from birth. The model concentrations were averaged over both the entire 70 year lifetime
(lifetime average) and over the five years surrounding the peak concentration (five-year average)
(see Section 3.3.1, describing first order body burden estimation). The human equivalent doses
were estimated by adjusting the daily dose model input until the time-averaged whole blood
concentration matched the associated alternative dose BMDL (derived earlier from animal PBPK
model). For animal studies which lasted longer than 540 days, the lifetime average was used; for
studies lasting less than 540 days, the five year average was used. The process was iterative and
continued until the modeled human concentration was within 1% of the BMDL. In general,
however, the concentrations matched to within 0.1%.

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5.2.3.2.3. Dose-response modeling approaches for rodent bioassays.

5.2.3.2.3.1. Modelin2 of individual tumors.

EPA's BMDS Software, version 2.1 was used to estimate the BMDLois for each of the
species/sex/tumor combinations, using the blood concentrations and incidence data shown in
Tables 5-5 through 5-14. Each data set was modeled using the multistage cancer model, and a
BMDLoi in blood concentration was estimated. The multistage model has been used by EPA in
the majority of its quantitative cancer assessments because it is statistically robust and able to
provide good fits to a wide range of dose-response patterns. It is also consistent with the
multistage nature of the carcinogenic process. The mathematical form of the multistage model is

P(d) = 1 - exp[-(^0 + q\d + q2d2 + ... + qgf)]	(Eq. 5-6)

where

P(d) = lifetime excess risk (probability) of cancer at dose d

q, = parameters estimated in fitting the model, i = 1, ...,k.

To estimate the BMDoiS and BMDLois, BMDS was run with all parameters set to their
defaults; up to three degrees of freedom were specified for the dichotomous, multistage cancer
model; and a 95% confidence level. A 1% extra risk benchmark response (BMR) was used for
each tumor type, as this response level was judged to be sufficiently close to the observed
responses (see Section 5.2.3.2.6.11 for an expanded discussion). The BMDLoi (ng/kg) was then
converted to a BMDLred (ng/kg-day) using the Emond human model, and an OSF in units of
(mg/kg-day)-1 was calculated by, OSF = 0.01/BMDLHed x106. Because of the nonlinearity of
blood concentration and ingested dose in the Emond Human PBPK model, the cancer risk is only
approximately linear with the TCDD blood concentration and low TCDD oral ingestion doses,
but is not linear with ingested TCDD at higher doses.40 Thus, to use these estimates in human
health risk assessment, risk-specific TCDD oral intake levels corresponding to the target risk
levels should be calculated, using a procedure similar to that for the slope factors based on
epidemiologic data (see Table 5-3). In the following sections, results are presented for the

40 This situation is analogous to that for the cancer risk modeling of epidemiologic data from the Cheng et al. (2006)
analysis in Section 5.2.3.1.2.1.

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models that provided the best overall fit to the data as judged by comparison of likelihood ratios
for models that had an acceptable fit (chi-squared goodness of fit statisticp > 0.05).

5.2.3.2.3.2. Multiple tumor (Bavesian) models.

Statistically significant increased tumor incidences were observed at multiple sites in
male and/or female rats (Kociba et al., 1978, 001818; NTP, 1982, 594255; NTP, 2006, 543749)
and male and female mice (NTP, 1982, 594255) following oral exposures to TCDD. With this
multiplicity of tumors, the concern is that a potency or risk estimate based solely on one tumor
site (e.g., the most sensitive site) may underestimate the overall cancer risk associated with
exposure to this chemical. Relevant approaches in the 2005 Cancer Guidelines (U.S. EPA, 2005,
086237) for characterizing total risk include the following: (1) analyze the incidence of tumor-
bearing animals, or (2) combine the potencies associated with significantly elevated tumors at
each site. The NRC (1994, 006424) concluded that an approach based on counts of animals with
one or more tumors (tumor-bearing animals) would tend to underestimate overall risk when
tumor types occur independently, and thus an approach based on combining the risk estimates
from each separate tumor type should be used. On independence of tumors, NRC (1994,

006424) stated "... a general assumption of statistical independence of tumor-type occurrences
within animals is not likely to introduce substantial error in assessing carcinogenic potency."

Because potencies are typically upper bound estimates, summing such upper bound
estimates across tumor sites is likely to overstate the overall risk. Therefore, following the
recommendations of the NRC (1994, 006424) and the 2005 Cancer Guidelines (U.S. EPA, 2005,
086237). a statistically valid upper bound on combined risk was derived, assuming
independence, in order to gain some understanding of the overall risk resulting from tumors
occurring at multiple sites. In the case of TCDD, tumors are thought to be independent across
the sites found in these three studies because: (1) they are in different organs and tissues,
specifically liver, lung, thyroid, subcutaneous tissue, oral cavity, tongue, pancreas, adrenal cortex
and the hematopoietic system; (2) different kinds of tumors were found, even within the same
organ (e.g., both cholangiocarcinomas and hepatocellular adenomas were found in female rat
livers in NTP (2006, 543749); and (3) the tumors found in these studies were not progressive
(i.e., they did not metastasize to other sites in the body). It is important to note that this estimate

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of overall potency describes the risk of developing tumors at any combination of the sites and is
not the risk of developing tumors at all sites simultaneously.

For modeling individual tumor data, the multistage model is specified as shown in the
previous section (see Eq. 5-6). Under the assumption of independence, the model for the
combined (or composite) tumor risk is still multistage, with a functional form that has the sum of
stage-specific multistage coefficients as the corresponding multistage coefficient.

Pc(d) = 1 - exp[-(Lq0i + dLqn + cfl.q2i + ... + d"I.qm)\, for i = 1,..., k, (Eq. 5-7)
where k = total number of sites.

The resulting equation for fixed extra risk (BMR) is polynomial in dose (when logarithms
of both sides are taken) and can be solved in a straightforward manner for the combined BMD.
However, the current version of BMDS cannot estimate confidence bounds for this combined
BMD.

Therefore, a Bayesian approach to finding confidence bounds on the combined BMD was
implemented using Win BUGS (Spiegelhalter et al., 2003, 594261). Win BUGS software is freely
available and implements Markov Chain Monte Carlo (MCMC) computations. Use of
WinBUGS has been demonstrated for derivation of a distribution of BMDs for a single
multistage model (Kopylev et al., 2007, 194860) and is easily generalized (Kopylev et al., 2009,
198071) to derive the distribution of BMDs for the combined tumor load, following the NRC
(1994, 006424) methodology described above. The advantage of a Bayesian approach is that it
produces a distribution of BMDs that allows better characterization of statistical uncertainty. For
the current analysis, a diffuse (high variance or low tolerance) Gaussian prior restricted to be
nonnegative was used. The posterior distribution was based on three simulation chains with
50,000 burn-in (i.e., the initial 50,000 iterations were dropped) and a thinning rate of 20,
resulting in 150,000 interactions total. The median and 5th percentile of the posterior distribution
provided the BMD0i (central estimate) and BMDLm (lower bound) for combined tumor load,
respectively.

The methodology above was applied to the statistically significant dose-response data
from Kociba et al. (1978, 001818). NTP (1982, 594255). and NTP (2006, 543749) (see

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Section 2.3.2 for data set selection criteria).41 As with the risk estimates generated for individual
tumor sites, the combined analysis used the internal dose metric, whole blood concentration (see
Section 3). For the combined tumors for each sex/species combination, a BMDLoi in blood
concentrations was estimated. The BMDLoi (ng/kg) was then converted to a BMDLred
(ng/kg-day) using the Emond human model, and an OSF in units of (mg/kg-day) 1 was
calculated by, OSF = 0.01/BMDLHed x 106. Because of the nonlinearity of blood concentration
and ingested dose in the Emond Human PBPK model, the cancer risk is linear only with the
TCDD blood concentration and low TCDD oral ingestion doses, but is not linear with ingested
TCDD at higher doses; a single OSF cannot represent the entire range of risks for oral ingestion.
Thus, to use these estimates in human health risk assessment, risk-specific TCDD oral intake
levels corresponding to the target risk levels should be calculated using a procedure similar to
that for the slope factors based on epidemiologic data (see Table 5-3).

5.2.3.2.4. Results of dose-response modeling for rodent bioassays.

Table 5-15 presents the benchmark dose modeling results for both the individual tumors
and the combined tumors based on TCDD blood concentrations. The ^-values in the table are
for a chi-square goodness of fit statistic with significance ofp > 0.05. Goodness of fit was
acceptable at/? > 0.05 for all models. The difference in log likelihood (dLL) statistic documents
the difference in log likelihoods between stages of the models in cases where the stage is
above 1; it shows the difference between the stage in the table and the lower stage. For example,
for the NTP (2006, 543749) liver cholangiocarcinomas, twice the difference of 2.92 would be
>3.84, the test statistic from the assumed chi-square distribution,42 withp = 0.95, justifying the
choice of 3 stages over 2 stages. The best fitting multistage models include: a 1-stage (linear)
model for all of the individual tumor data sets from Kociba et al. (1978, 0018181 NTP (1982,
594255). and Toth et al. (1979, 197109). for liver carcinomas in females in Delia Porta et al.
(1987, 197405). as well as for the pancreatic and oral mucosa tumors in NTP (2006, 543749); a

41 Because only one turmor site was statistically significantly elevated in both the Delia Porta et al. (1987, 1974051
and Toth et al. (1979, 1971091 (i.e., only increased incideces of liver tumors were statistically significant elevated in
both studies), a multi-tumor analysis was not conducted.

42The chi-square distribution with 1 degree of freedom is the correct distribution only under standard conditions
(e.g., no boundary parameters in null hypothesis). Thus, the correct distribution for the situation where the
parameter of interest is on the boundary, as happens with testing for the order of the multistage model, and, possibly
nuisance parameters (estimated parameters of the model), is very difficult to derive (Self and Liang. 1987, 594398).
Therefore the p-valuc of chi-square with one degree of freedom is used as the best available choice.

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2-stage model for the lung tumors in NTP (2006, 543749) and for liver carcinomas in males from
Delia Porta et al. (1987, 197405); and a 3-stage model for the liver cholangiocarcinoma and liver
adenoma data sets from NTP (2006, 543749). The multi-stage model fit was not significant (p >
0.1) in the NTP (1982, 594255) study for lung tumors in the male mouse (p = 0.09), adrenal
cortex (p = 0.06)and thyroid follicular cell adenomas (p = 0.06) in male rats, and subcutaneous
tissue in female mice (p = 0.09), and was also not significant for liver carcinomas (p = 0.019) in
female mice in Delia Porta et al. (1987, 197405). For the Toth et al. (1979, 197109) liver
tumors, the model fit to all of the data was poor, and the highest dose group was dropped in order
to achieve an acceptable fit (p = 0.29). The BMDois and BMDLois (ng/kg) were estimated from
these multistage models for the individual tumors. BMDois and BMDLois (ng/kg) were also
provided in Table 5-15 for the combined tumors for each sex/species combination within a study.
These were estimated from the distributions of BMDois produced by the Bayesian MCMC
simulation (see Section 5.2.3.1.2.3.2). The BMDois and BMDLois (ng/kg) for the combined
tumors in Table 5-15 are the mean and lower 95% percentile values from these distributions,
respectively.

5.2.3.2.4.1. Individual tumor models.

Table 5-16 shows the BMDLredS (ng/kg-day) that were estimated from the BMDLois in
Table 5-15 using the Emond human model (see Section 5.2.3.1.2.2.2) and the OSFs calculated
by, OSF = 0.01/BMDLhed x 106 to convert the OSF to (mg/kg-day)-1 units. BMDS results,
details of the model fits and dose-response graphics for all endpoints are shown in Appendix F.
Although only the blood concentration results are presented in this section, for comparison
purposes, Appendix F also provides modeling results for the studies' administered average daily
doses. Table 5-16 lists the OSFs in decreasing value. It can be seen that liver tumors in male
mice yield the highest slope factors; OSF values are 5.9 xlO6 and 5.2 xlO6 per mg/kg-day in
NTP (1982, 594255) and Toth et al. (1979, 197109). respectively. The OSFs for the new NTP
(2006, 543749) study in female rats are two orders of magnitude lower, ranging from 1.8 xlO4 to
1.8 xlO5 per mg/kg-day, representing the lowest OSFs for TCDD from the individual tumor
models.

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5.2.3.2.4.2. Multiple tumor (Bavesian) models.

Table 5-17 shows the BMDLHedS (mg/kg-day) that were estimated from the BMDL0iS in
Table 5-15 using the Emond human model (see Section 5.2.3.1.2.2.2) and the OSFs calculated
by, OSF = 0.01/BMDLred x 106 to convert the OSF to (mg/kg-day)-1 units. Table 5-17 lists the
OSFs in decreasing value. It can be seen that the combined liver and lung tumors in male mice
yield the highest OSF value of 9.4 xlO6 per mg/kg-day from NTP (1982, 594255). and the
combined adrenal, tongue and nasal tumors in male rats yield the lowest OSF value of 3.2 x 105
from Kociba et al. (1978, 001818). The OSF for the combined liver, oral mucosa, lung, and
pancreatic tumors in female rats from the newer NTP (2006, 543749) study is 4.4 xlO5.

5.2.3.2.5. Summary evaluation of slope factor estimates from rodent bioassays.

To estimate a range of candidate TCDD OSFs from the animal data, dose-response
modeling of the five chronic rodent bioassays identified in Section 2.4.3 was conducted. Dose-
response modeling was performed using whole blood concentrations, and BMDLred values
(ng/kg-day) were derived for the 28 species/sex/endpoint data sets individually (see Table 5-16)
and for seven species/sex combined tumor data sets (see Table 5-17).

The highest OSFs that have been derived for these animal cancer bioassays using the
multistage models are from the multiple tumor analyses for NTP (1982, 594255; 2006, 543749)
and Kociba et al. (1978, 001818). presented in Table 5-17, and from the individual tumor
analyses for Toth et al. (1979, 197109) liver tumors and Delia Porta et al. (1987, 197405) liver
carcinomas in male mice, presented in Table 5-16. The most sensitive species and sex is male
mice, for which the estimated BMDLred for combined tumors is 1.1 x 10"3 ng/kg-day. This
result, which is derived under the assumption that multiple tumor types occur independently in
the exposed animals, is, as expected, lower than the BMDLred for the most sensitive individual
tumor.

Based on these results, EPA believes that a credible value for the BMDLred derived from
the animal studies lies in the range shown in Table 5-17 between 3.1 x 10"2 and
1.1 x 10 3 ng/kg-day. These values, which correspond to oral slope factor values of 3.2 x io5
and 9.4 x io6 per mg/kg-day, respectively, encompass the range at which elevated cancer risks
can be detected for the most sensitive species, sex, and endpoints in the animal bioassay data.

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As noted above in Sections 5.2.3.1.2.2 and 5.2.3.1.2.3, the cancer mortality risk is strictly
linear only with TCDD blood concentration, such that a single OSF cannot represent the entire
range of risks for oral ingestion. The OSFs shown in Tables 5-16 and 5-17 are based on HEDs
corresponding to the BMDLoi, which are most representative of lower human exposure levels,
including ambient exposures. For higher exposures, the risks increase at a slower rate with
increasing dose and the corresponding OSFs are lower; in those cases, risk-specific doses can be
calculated as previously described (see Section 5.2.3.2.3.2).

5.2.3.2.6. Qualitative uncertainties in slope factor estimates from rodent bioassays.

This section presents a qualitative discussion of the uncertainties associated with
calculating the OSF for TCDD from chronic animal bioassay data. Discussions on the feasibility
of conducting a quantitative uncertainty analysis for TCDD using dose-response methods are
provided in Section 6.4.2 of this document.

5.2.3.2.6.1. Quality of studies relied upon for determining POD.

EPA considers the overall quality and breadth of the studies used for the cancer dose-
response analysis to be excellent. All of the studies were published in the peer-reviewed
literature, and two of them were conducted by NTP (1982, 594255; 2006, 5437491
Kociba et al. (1978, 001818). Delia Porta et al. (1987, 197405) and Toth et al. (1979, 197109)
are older studies, but appear to have been conducted according to good laboratory practice
standards. The control and dose group sample sizes were relatively large, -40-50 animals or
more per group for all of the studies. All five studies exposed the test animals via the oral route
to TCDD alone, as was stipulated in EPA's study inclusion criteria. Collectively, these five
studies reported development of numerous cancer endpoints (tumors) in both sexes in two strains
of rats (Sprague-Dawley and Osborne-Mendel) and two strains of mice (i.e., B6C3Fi,
Swiss/H/Riop). The overall high quality of these studies and the strong, positive association
between TCDD exposure and cancer suggests that study quality is not a major contributing factor
to uncertainty in the risk estimates.

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5.2.3.2.6.2.	Interpretation of results from studies relied upon for determining POD.

As discussed in Section 3.4.3.2.1, questions arose about the interpretation of liver tumor
responses in female rats in the Kociba et al. (1978, 001818) study. Three re-evaluations of the
slides have been reported (Goodman and Sauer, 1992, 197667; Kociba et al., 1978, 001818;
Squire, 1980, 594272). The decision to use the Goodman and Sauer (1992, 197667) evaluation
was based on their use of the most current tumor classification procedures. The incidence of
hepatocellular adenomas and carcinomas (individually and combined), however, did vary
(sometimes widely) for each dose group across the three evaluations. Although the state-of-the-
science is reflected in the Goodman and Sauer analysis, there is some uncertainty in the
interpretation of any post-hoc analysis. No issues have arisen with regard to the interpretation of
the NTP (1982, 594255; 2006, 543749). Delia Porta et al. (1987, 197405) or Toth et al. (1979,
197109) tumor identification and classification.

5.2.3.2.6.3.	Consistency of results across chronic rodent bioassavs.

The existence of five high-quality chronic bioassays for TCDD increases confidence and
reduces uncertainty in the cancer OSFs. Considered together, these studies tested two species
and both sexes of mice and rats, and a wide range of well-characterized tumor types. All five
studies were consistent in observing increases (at some dose level) in rates of liver tumors (in
both species and sexes). While tumors at other sites were observed (and those sites varied across
study, species, and sex), the liver tumors were consistently the most sensitive indicators of
carcinogenic response (with respect to BMDLred estimates). Lung tumors were also
consistently observed across three of the studies, in male mice in the NTP (1982, 594255) study
and in female rats in Kociba et al. (1978, 001818) and NTP (2006, 543749). As discussed above,
the two most sensitive single-tumor endpoints as judged by BMDL0i values were associated with
elevated liver tumor risks, followed by lung, lymphoma or leukemia, thyroid and adrenal
cancers. The consistency of tumor types and sensitivities across endpoints and studies lends
confidence to the multistage modeling results.

5.2.3.2.6.4.	Human relevance of rodent tumor data.

There is some concordance in the tumor responses observed in the rodent test species and
humans, however, the most sensitive tumor site in the animals, the liver, has not been associated

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with cancer from TCDD exposures in humans. On the other hand, lung cancer and leukemia are
found both in the animal studies and in epidemiologic studies of exposed workers. The
consistency across sex, species, and strains in the animal studies suggests that the occurrence of
several of these tumors, in particular, liver and lung tumors is not an idiosyncratic response of a
particular combination of species, strain, or sex. As discussed in Section 5.2.1, the likely AhR
related carcinogenic mechanism is credible for humans as well as for rodent species.

5.2.3.2.6.5.	Relevance of rodent exposure scenario.

Three of the five chronic rodent bioassays exposed the test animals for ~2 years, the
majority of their lifespans. T oth et al. (1979, 197109) exposed the animals only for one year, but
they were kept on the study for a second year before they were evaluated for cancer. The Delia
Porta et al. (1987, 197405) study also exposed the test animals for one year, and a dosing error
occurred during the study. At ages 31 to 39 weeks, 41 male mice and 32 female mice in the
2,500 ng/kg BW dose group were mistakenly administered a single dose of 25,000 ng/kg BW
TCDD. TCDD treatment for the 2,500 ng/kg BW dose group was halted for 5 weeks (beginning
the week after the 25,000 ng/kg BW dose was administered in error) and resumed until exposure
was terminated at 57 weeks. Thus, the large single dose and subsequent period without TCDD
exposure confounds the dose-response relationship for this study. In general, these lifetime
bioassays in animals have long been used by EPA to assess potential lifetime exposures and
effects in humans. However, in the case of TCDD, the half life of TCDD in the body for rats,
mice, and humans is very different (see Section 3). Thus, there is a significant amount of
uncertainty in the use of rat and mouse data to develop OSFs for human cancer risk assessment
of TCDD.

5.2.3.2.6.6.	Impact of background TCDD exposures.

It is known that TCDD has been found in the feed used in animal bioassays, and that this
is a confounding factor, particularly in older studies. The effect of TCDD in the diets of test
species has the potential to be quite significant given the low levels of TCDD at which adverse
effects have been observed. Insofar as that is an issue, the risks associated with TCDD
exposures in the animal bioassays, and therefore the OSFs, would be biased high, which could be
the case for the NTP (1982, 594255). Delia Porta et al. (1987, 197405). Kociba et al. (1978,

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001818) and Toth et al. (1979, 197109) studies. The impact of this issue is that the newer study,
NTP (2006, 543749), accounted for TCDD exposures in the animal feed. Thus, there is likely to
be less uncertainty in the TCDD dose-response information presented in NTP (1982, 594255;
2006, 543749) than in the other four studies conducted before 1990.

5.2.3.2.6.7.	Choice of endpoint for POD derivation.

As noted above, the liver tumor PODs represent the most sensitive single-tumor endpoint
across the five cancer bioassays. Thus, the liver cancer endpoints must be seriously considered
for derivation of a TCDD OSF. As discussed in the previous section, EPA has also developed
Bayesian dose-response estimates for combined tumors, which yield BMDLoi values slightly
lower than those for any individual tumor type. Although it is the most conservative choice to
select the lowest combined tumor POD for OSF derivation, there are uncertainties associated
with the multiple tumor analysis. The assumption of independence of tumors across sites is
reasonable, particularly since the tumors from TCDD do not metastasize. However, the
independence assumption lacks hard evidence and needs further laboratory confirmation.

5.2.3.2.6.8.	Choice of animal-to-human extrapolation method.

The analyses presented here have used the Emond human kinetic model for extrapolating
dose from animals to humans (as discussed in Section 3.4.2). The rationale for this choice is that
the blood concentration metric most accurately reflects the concentration of TCDD in the various
tissues. As discussed in Section 3.4.3.2.4, use of the blood concentration dose metric results in
critical dose estimates (HEDs) that are considerably lower (10- to more than 100-fold) than those
derived based on administered dose. This does not reflect bias in the blood-based measure;
rather it is a reflection of the nonlinear biokinetics of TCDD in the body. EPA has also explored
the impacts of using other dose metrics, including AhR-bound TCDD concentration calculated
based on the Emond model. As discussed in Section 3.4.3.2.6.2, this also results in HED
estimates much lower than those obtained based on administered dose.

5.2.3.2.6.9.	Choice of model for POD and model uncertainty for POD derivation.

The bioassay-based cancer dose-response assessment in this section has used the
multistage model which is the standard model choice for such assessments and has been the basis

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for most of EPA's cancer risk assessments. The multistage model is the standard because it is
the only available model form that allows for low-dose linearity while accommodating
curvilinearity at higher doses and can be readily implemented.

There is some model choice uncertainty associated with instances of lack of fit. When
the multistage model does not adequately describe the observed pattern of responses (typically
determined by examining the p-walue for lack of fit), a decision must be made about possible
adjustments, including the dropping of higher dose groups thought to be less relevant to the
estimation of low-dose slopes. In this analysis, poorer fits (p-values less than 0.10) were
observed in five cases, four from NTP (1982, 594255) and one from Delia Porta et al. (1987,
197405) (see Table 5-15). The lowest BMDLoi associated a low p-w alue (p = 0.09) was for the
lung tumors in the NTP (1982, 594255) male mouse, the third lowest POD behind the liver
PODs in the individual tumor data sets. The other instances were for adrenal cortex and thyroid
follicular cell adenomas in male rats and for subcutaneous tissue in female mice in the NTP
(1982, 594255) study and for liver carcinomas in female mice in Delia Porta et al. (1987,
197405). In those instances, the/>-values were 0.06, 0.06, 0.09, and 0.019, respectively. These
poorly fit data sets provide OSF estimates that are uncertain and also contribute to uncertainty in
the combined tumor PODs from NTP (1982, 594255). The lowest BMDLoi in the combined
tumors is for the male mice combined liver and lung tumors, thus estimates from this sex/species
combination from NTP (1982, 594255) is highly uncertain and impacts its choice as a POD.

5.2.3.2.6.10. Statistical uncertainty in model fits.

Every model fit to a data set is associated with some inherent statistical uncertainty. For
this reason, bounds were calculated and used for OSF derivation (e.g., lower bounds on
benchmark doses, in this case the BMDLois). Those bounds account for uncertainties associated
with finite samples of test animals, both in terms of the number of dose groups and of the
number of animals per dose group. Valid and accepted statistical procedures have been applied
to ascertain the impact of those limitations on the estimates of interest. That being the case, the
statistical uncertainties associated with finite samples have been adequately addressed.

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5.2.3.2.6.11. Choice of risk level for POD derivation.

The BMR level that has been used for the POD in deriving the cancer OSF is one percent
extra risk. A single BMR was chosen for consistency across studies. Also, a BMR of 1% was
judged to be near the range of the observations. For the TCDD animal cancer bioassay data,
although many of the first positive tumor incidence responses (relative to controls) are closer to
10% (some higher), some are as low as 2%. Furthermore, most of the BMDoi values are within a
factor of 3 of the lowest tested dose, and the BMDLoi values are generally less than a factor of 2
below the BMD. Table 5-18 presents a comparison of BMDs, BMDLs and slope factors for 1%,
5% and 10% BMRs from the multi-tumor analyses of NTP (1982, 594255; 2006, 543749) and
Kociba et al. (1978, 001818) and for selected single tumor data sets from Toth et al. (1979,
197109) and Delia Porta et al. (1987, 197405). In Table 5-18, the choice of BMR has little or no
impact on the slope factors based on TCDD blood concentration for the combined or single
tumor incidences selected as representative of each study.43 In contrast, Table 5-19 presents a
comparison of Human Equivalent Dose BMDs, BMDLs and slope factors for 1, 5, and 10%
BMRs from these same datasets. Table 5-19 shows that, when converting the blood
concentration to the equivalent HED, a 2-fold to 4-fold decrease in the OSF is obtained when
using a BMR of 10% rather than 1%. This result is a consequence of the nonlinearity in the
Emond PBPK model at higher doses, where dose-dependent elimination of TCDD in the liver
results in a less-than-proportional increase in blood concentration relative to oral intake. At
lower exposure levels, blood concentration is proportional to oral intake. Therefore, EPA has
chosen the lower BMR of 1% as more representative of the low-dose risk.

5.2.3.3. EPA 'v Response to the NAS Comments on Choice of Response Level and

Characterization of the Statistical Confidence Around Low Dose Model Predictions

The NAS was concerned with the statistical power to determine the shape of the dose
response curve at low doses, well below observed dose-response information. EPA shares this
concern in that the shape of the dose-response curve in the low-dose region cannot be determined
with confidence when based on higher dose information.

43 This will generally be the case for multistage model fits with lst-degree coefficients greater than zero because the
response at the BMDL is virtually linear at BMRs of 10% or less. For model fits dominated by higher-order
coefficients, linearity of response at the BMDL begins at lower BMRs.

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When tumor data are used for dose-response modeling, a POD is obtained from the
modeled tumor incidences. When assessing carcinogenicity using a linear extrapolation
approach from a POD, a balance must be struck between staying within the range of the
observations and obtaining a representative estimate of the low-dose slope. Traditional cancer
bioassays, with approximately 50 animals per group, can typically support modeling down to an
increased incidence of 1-10%; epidemiologic studies, with larger sample sizes, below 1%. For
the TCDD animal cancer bioassay data, most of the low-dose tumor incidence responses are
under 10% (relative to controls), with some as low as 2%. For comparison purposes, BMDs,
BMDLs and OSFs from the animal cancer bioassay benchmark dose modeling assuming 1, 5,
and 10%) extra risk are shown in units of blood concentrations and human equivalent doses in
Tables 5-18 and 5-19, respectively. After evaluating the magnitude of the uncertainty in
BMDLoiS against the impact of using BMDLi0s, EPA has chosen to use a 1% BMR in all cases,
determining that the uncertainty bounds on the BMDLoi values are reasonable.

In the analysis of the animal cancer bioassays presented in this document, the multistage
cancer model was applied with a linear dose extrapolation to zero. EPA used a 1% excess risk
estimate, i.e., a BMDLoi, as the POD for development of candidate TCDD cancer oral slope
factors using a Bayesian multitumor approach (see Section 5.2.3.2. The advantage of a Bayesian
approach is that it produces a distribution of BMDs that allows better characterization of
statistical uncertainty.

Central tendency slope estimates and upper bound oral slope factor estimates are part of
the standard BMDS multistage cancer model and are included in each output file for the animal
bioassay single tumor analyses in Appendix F. Central tendency BMDs are also reported for the
results of the animal bioassay multitumor analysis (see Table 5-15). Central tendency slope
estimates are given for all the qualifying epidemiological studies as well (see Tables 5-1 and
5-4), where possible.

5.2.3.4. EPA 'v Response to the NAS Comments on Model Forms for Predicting Cancer Risks
Below the POD

The NAS offered extensive comments on the cancer dose-response modeling in the 2003
Reassessment. Although epidemiologic and rodent bioassay data are useful for the evaluation of
the dose-response curve within the range of the observed response data, they have traditionally

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not been useful sources of information for identifying a threshold or for estimating the shape of
the dose-response curve below the POD. Rather, mechanistic toxicological data have been the
evidentiary sources of choice for those types of analyses. As noted above, any quantitative
estimation of carcinogenic risk associated with TCDD exposure requires low-dose extrapolation
of experimental data. Unfortunately, the shape of the dose-response curve in the low dose region
is unknown.

Several of the analyses of epidemiological cohort data evaluated the fit of different dose-
response models to the data. Log-dose models accentuate the importance of low-dose low-
magnitude responses and can yield implausible results. The most relevant models used in these
studies are the untransformed-dose Cox regression models. Better results have been obtained in
the cohort analyses when the flattening of the hazard-ratio curve is taken into account. The latter
has been modeled explicitly by Steenland et al. (2001, 198589). who use a piece wise linear
model and implicitly by Cheng et al. (2006, 523122). who drop out a percentage of the high-dose
response data and fit a linear model to the remainder. Importantly, the analyses of the
epidemiologic cohorts presented in Section 5.2.3.1 are limited to evaluation and reanalyses of
published data as reported by the study authors. EPA does not have access to the raw data from
these epidemiologic studies and, therefore, could not conduct de novo analyses.

5.2.3.4.1. Choice of extrapolation approach
5.2.3.4.1.1. TCDD and receptor theory.

TCDD is considered to be a receptor-mediated carcinogen in animals. Nearly all TCDD
experimental data are consistent with the hypothesis that the binding of TCDD to the AhR is the
first step in a series of biochemical, cellular, and tissue changes that ultimately lead to toxic
responses observed in both experimental animals and humans (Part II, Chapter 2 of the 2003
Reassessment). Ligand-receptor binding, like any bimolecular interaction, obeys the law of mass
action as originally formulated by A.J. Clark (Limbird, 1996, 594276). The law of mass action
predicts the fractional receptor occupancy at equilibrium as a function of ligand concentration.
Fractional occupancy (Y) is defined as the fraction of all receptors that are bound to ligand:

y _ [TCDD - AhR ] _ [TCDD - AhR ] _ [TCDD

[AhR ]TOT [AhR ] + [TCDD - AhR ] [TCDD ] + Kd	^ 5_g)

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where [TCDD] is the concentration of the ligand, [AhR] is the concentration of the receptor and
[TCDD-AhR] is the amount of liganded receptor. The equilibrium dissociation constant Kd
describes the affinity of the interaction and is the concentration of TCDD that results in 50%
receptor occupancy. This simple equation defines a rectangular hyperbola, which is the
characteristic shape of the vast majority of biological dose-response relationships.

In certain cases, no response occurs even when there is some receptor occupancy. This
suggests that there may be a threshold phenomenon that reflects the biological "inertia" of the
response (Ariens et al., 1960, 594279). In other cases, a maximal response occurs well before all
receptors are occupied, a phenomenon that reflects receptor "reserve" (Stephenson, 1956,
594280). Therefore, the law of mass action cannot by itself fully explain the effect or response
observed after TCDD interacts with AhR. The ligand-receptor complex is associated with a
signal transduction or effector system. In the case of the AhR, this effector system can be
considered to be the transcriptional machinery itself. The key feature of this formulation is that a
response is proportional, or a function of, the number of receptors occupied.

Furthermore, for a ligand such as TCDD that elicits multiple receptor-mediated effects,
one cannot assume that the binding-response relationship for a simple effect (such as enzyme
induction) will necessarily be identical to that for a different and more complex effect (such as
cancer). The cellular cascades of events leading to different complex responses (e.g., altered
immune function, developmental effects, or cancer) are different, and other rate-limiting events
likely influence the final biological outcome resulting in different dose-response curves. Thus,
even though TCDD binding to AhR is assumed to be the initial event leading to a spectrum of
biological responses, TCDD-AhR binding data may not always correlate with the dose-response
relationship observed for particular effects.

A receptor-based mechanism would predict that, except in cases where the concentration
of TCDD is already high (i.e., [TCDD]~Kd), incremental exposure to TCDD will lead to some
increase in the fractional occupancy of AhR. However, as discussed above, it cannot be assumed
that an increase in receptor occupancy will necessarily elicit a proportional increase in all
biological response(s), because numerous molecular events contributing to the biological
endpoint are integrated into the overall response. That is, the final biological response could be
considered as an integration of a series of interdependent dose-response curves with each curve

dependent on the molecular dosimetry for each particular step. Dose-response relationships that

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will be specific for each endpoint must be considered when using mathematical models to
estimate the risk associated with exposure to TCDD. It remains a challenge to develop models
that incorporate all the complexities associated with each biological response as the modes of
action for various toxicological endpoints appear to vary greatly. For TCDD, extensive
experimental data from studies using animal and human tissues indicate that cell- or tissue-
specific factors determine the quantitative relationship between receptor occupancy and the
ultimate biological response. This would suggest that the parameters for each mathematical
model might only apply to a single biological response within a given tissue and species, making
extrapolation to other systems challenging.

5.2.3.4.1.2. Low-dose extrapolation: threshold or no threshold?

As indicated in the 2005 Cancer Guidelines,44 toxicity reference values for human
noncancer endpoints have historically been estimated based on a no-observed-adverse-effect
level (NOAEL) or lowest-observed-adverse-effect level (LOAEL) from animal bioassay studies.
This terminology suggests a biological population threshold beneath which no harm is
anticipated. Reference values such as the oral reference dose (RfD) or inhalation reference
concentration (RfC) are derived by applying uncertainty factors (UFs) to a POD. Depending on
the nature of available data and modeling choice, a POD can be selected from values other than
an NOAEL or LOAEL, such as an EDX, or a benchmark dose (BMD) or its BMDL. An RfD is
described as "likely to be without appreciable risk" but the probabilistic language has not as yet
been operationalized. There is no quantitative definition of "appreciable" and no mechanism to
compute risk as a function of dose, so as to ascertain that the risk is indeed not appreciable. The
risk at the RfD is not calculated, and it cannot be calculated within the current UF framework.
Instead, a hazard quotient is computed as the ratio of a given exposure to the RfD, or a margin of
exposure is estimated as the ratio of the POD to the human exposure level.

Cancer endpoints are predominantly thought to have no population biological threshold.
Although the terminology "threshold/nonthreshold" is still common in cancer dose-response

44As stated in the 2005 Cancer Guidelines (U.S. EPA. 2005, 086237): "For effects other than cancer, reference
values have been described as being based on the assumption of biological thresholds. The Agency's more current
guidelines for these effects (U.S. EPA. 1996, 594399: U.S. EPA. 1998, 0300211 however, do not use this
assumption, citing the difficulty of empirically distinguishing a true threshold from a dose-response curve that is
nonlinear at low doses."

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discussions, the 2005 Cancer Guidelines propose a different terminology, whereby "nonlinear
models" are those whose dose-response slope is zero at or above zero. In the natural language,
and indeed in data analysis, it is difficult to distinguish the following situations:

•	The response approaches zero as dose goes to zero, versus

•	The response slope goes to zero as dose goes to zero (nonlinear model).

This use of "nonlinear" is acknowledged to be idiosyncratic.45 The NAS review (NAS,
2006, 19844H does not consistently apply the terminology from the 2005 Cancer Guidelines, nor
does it consistently distinguish the above two circumstances: ".. .the observed data are more
consistent with a sublinear response that approaches zero at low doses rather than a linear dose
response" (NAS, 2006, 198441). The point of a nonlinear model in the sense of the 2005 Cancer
Guidelines is that the response slope approaches zero. Both linear and nonlinear responses
approach zero at low dose (in the absence of background). Since the terms "linear," "sublinear,"
and "nonlinear" invite confusion in this context, the following terminology is used in this
document:

Threshold Model. There is some threshold dose T > 0 such that the probability of
response for any dose less than or equal to T is zero, and the probability is nonzero for
any dose greater than T.

Linear/ Linear above Threshold Model. For the linear model, the probability of response
is proportional to the dose. For the linear over threshold model, the probability of
response is zero for a dose below the threshold, and it is proportional to the excess dose
over the threshold otherwise. Note that under the EPA cancer guidelines, the linear
above threshold model is classified as a nonlinear model.

Nonlinear Model. Any model that is not linear.

Supralinear/ Supralinear above Threshold Model. For the supralinear model, the slope of
the probability of response decreases as dose increases; in other words, the second
derivative of the response curve is negative. For the supralinear above threshold model,

45

From the 2005 Cancer Guidelines (U.S. EPA. 2005, 086237): "The term 'nonlinear' is used here in a narrower
sense than its usual meaning in the field of mathematical modeling. In these cancer guidelines, the term 'nonlinear'
refers to threshold models (which show no response over a range of low doses that include zero) and some
nonthreshold models (e.g., a quadratic model, which shows some response at all doses above zero). In these cancer

guidelines, a nonlinear model is one whose slope is zero at (and perhaps above) a dose of zero	Use of nonlinear

approaches does not imply a biological threshold dose below which the response is zero."

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the second derivative is negative above the threshold, and the response probability is zero
below the threshold.

Sublinear/Sublinear above Threshold Model. For the sublinear model, the slope of the
probability of response increases as dose increases; in other words, the second derivative
of the response curve is positive. For the sublinear above threshold model, the second
derivative is positive above the threshold, and the response probability is zero below the
threshold.

Zero Slope at Zero Model. The slope of the response curve is zero at or above dose zero.

All of these models may be understood in an individual or population sense. According
to the 2005 Cancer Guidelines, the trigger for applying the basic RfD methodology for cancer
endpoints is sufficient evidence for the "zero slope at zero" model for the population. By
definition, any sublinear, supralinear, or linear model above the threshold i s a zero slope at zero
("ZS@Z") model.

The relation between individual and population models is not immediately evident.

Figure 5-4 shows dose-response curves of the probability of response vs. dose for different
models dose-response shapes. The left panel in Figure 5-4 shows a supralinear dose-response
curve; the rate of increase of the response probability goes down as dose increases, or in the strict
mathematical sense, the second derivative is negative. The middle panel shows a sublinear dose-
response curve; the second derivative is positive. In this case the slope at zero is zero (ZS@Z).
However, sublinearity, in the strict mathematical sense, by itself does not imply that the slope at
zero is zero. The probit dose-response model shown in the right graph is sublinear and has
positive slope at zero (the log-probit model is zero slope at zero).

If individuals in a population have different dose-response curves, then the population
dose-response curve is obtained by averaging all these dose-response curves over the population.
The shape of the population dose-response curve will generally be quite different from the
individual curves. Figure 5-5 is a simple depiction of the relationship of individual vs.
population dose response. The left panel in Figure 5-5 shows dose-response curves for seven
individuals, each with a supralinear dose-response curve above individual-specific thresholds.
Averaging these curves gives the dashed dose-response curve, which is nearly linear. The graph
on the right is similar, except that the individual dose-response curves are linear above individual
thresholds. The population curve is quadratic and zero slope at zero applies.

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Of course these are not the only possibilities; in general, the population dose-response
curve depends on (1) the distribution of individual thresholds in the neighborhood of zero, (2) the
dose-response curve for each individual, and (3) the dose metric. Under EPA's Cancer
Guidelines, the zero-slope-at-zero criterion applies strictly to ingested dose, but the other two
factors (distribution of individual thresholds and dose-response curve for each individual) need
to be established before a zero slope at zero dose can be established. Otherwise the default linear
extrapolation to zero approach applies.

On the nature or the distribution of individual thresholds, often referred to as the
population tolerance distribution, there is ongoing debate as to how receptor kinetics influence
the shape of that distribution. Even within an individual, there is a lack of consensus as to
whether receptor kinetics confer linear or sublinear attributes to downstream events, or whether
receptor kinetics, themselves, are linear, sublinear, or supralinear. Whatever the nature of the
form of receptor kinetics, it may have little or no influence on the ultimate population response.
The kinetics of receptors is in the domain of the individual, rather than the population. As
described previously, receptor kinetics are governed by the law of mass action, which leads to a
low-dose proportional response model, generally modeled by some form of Hill function, the
low-dose linear form being Michaelis-Menten kinetics. There is no a priori reason to believe
that the shape of the dose-response curve in an individual has any relationship to the shape of the
population response, particularly for quantal endpoints. Lutz and Gay lor (2008, 594297) present
an argument for considering the population response in terms of the more traditional tolerance
distribution, which is likely the result of more variable factors than the shape of receptor kinetics.
Perhaps more to the point, receptor activation is only the first of many events in the path to the
apical event (a tumor in this example). Because there are undoubtedly numerous additional
downstream events that must occur before the apical effect is observed, there are many
opportunities for interindividual variability to become manifest in the tolerance distribution.

Even at the first step, a more likely contributor to interindividual variability than the shape of the
response is the dose resulting in the response, as measured by the ED50 (Km in the Michaelis-
Menten formulation), which shifts the response curve. Factors that influence shifts in response
curves are generally modeled as normal or log-normal distributions and may confer a log-normal
shape on the population tolerance distribution, particularly if there are a number of dependent
sequential steps or distinct subpopulations (Hattis and Burmaster, 1994, 594301; Hattis et al.,

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1999, 594299; Lutz, 1999, 594298), although other distributions could be equally likely (Crump
etal., 2010. 380192).

To see how the discussion over threshold/nonthreshold might play out for TCDD,
consider the equilibrium dissociation constant Kd for TCDD, which measures the binding affinity
of TCDD to the AhR. Lower values indicate higher binding affinity and (other things being
equal) greater risk. For Han/Wistar rats, the value Kd = 3.9 is reported (standard deviation not
given); human values are reported as Kd = 9.6 ±7.8 (0.3 - 38.8 with 15 of 67 donors without
detectable binding) (Connor and Ay 1 ward, 2006, 197632). If AhR binding is the rate-limiting
step for carcinogenesis, then the majority of a human population may be less susceptible than
Han/Wistar rats, whereas a population threshold, if it exists, might still be well below the
Han/Wistar rat threshold, given the large variability in the human Kd estimate (see also Section
6.4.2.9). The NAS contends that an AhR-mediated mode of action indicates a threshold dose-
response relation (NAS, 2006, 198441). Presumably, the value of the threshold, if it exists,
depends on the AhR binding affinity. Arguing for a population threshold in this case requires
two types of information:

1.	The distribution of the individual thresholds induced by, among other things, the
individual Rvalues; and

2.	The dose-response function for values above the threshold induced by Kd.

Without this information, the shape of the population dose-response curve cannot be
determined with any confidence and the default linear relationship applies; response probability
is modeled as a linear function of dose, for dose near zero. However, from the 2005 Cancer
Guidelines: "When adequate data on mode of action provide sufficient evidence to support a
nonlinear mode of action for the general population (emphasis added) and/or any subpopulations
of concern, a different approach—a reference dose/reference concentration that assumes that
nonlinearity—is used." In current terminology, the reference dose methodology applies if there
is sufficient evidence supporting a "zero slope at zero" model; otherwise, the linear nonthreshold
model applies by default.

In principle, the choice between the above models could fall within the purview of dose-
response modeling. However, standard statistical methods encounter well-known difficulties in

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detecting thresholds. Without going into detail, suffice to say that the maximum likelihood
estimate of response probability when no responses are observed in a finite sample is always
zero. That said, some researchers have attempted to identify thresholds (Aylward et al., 2003,
594305; Mackie et al., 2003, 594303) or nonlinearity (Hoel and Portier, 1994, 198741) by means
of parameter estimation of appropriate models. A review of 344 rodent bioassays on 315
chemicals led to the following conclusion by Hoel and Portier (1994, 198741):

We have also found that the oft-held belief that genotoxic compounds typically
follow a linear dose-response pattern and that nongenotoxic compounds follow a
nonlinear or threshold dose response pattern is not supported by the data. In fact
we find the opposite with genotoxic compounds differing from linearity more
often than nongenotoxic compounds.

The choice between a linear and "zero slope at zero" model in current practice does not
fall under dose-response model fitting, it is made on the basis of a structured narrative as set
forth in the 2005 Cancer Guidelines (U.S. EPA, 2005, 086237):

In the absence of sufficiently, scientifically justifiable mode of action information,
EPA generally takes public health-protective, default positions regarding the
interpretation of toxicologic and epidemiologic data: animal tumor findings are
judged to be relevant to humans, and cancer risks are assumed to conform with
low dose linearity. ... The linear approach is used when: (1) there is an absence of
sufficient information on modes of action or (2) the mode of action information
indicates that the dose-response curve at low dose is or is expected to be linear.

Where alternative approaches have significant biological support, and no
scientific consensus favors a single approach, an assessment may present results
using alternative approaches. A nonlinear approach can be used to develop a
reference dose or a reference concentration.

5.2.3.4.1.3. Extrapolation method.

The 2005 Cancer Guidelines (U.S. EPA, 2005, 086237) emphasize that the method used
to characterize and quantify cancer risk from a chemical is determined by what is known about
the MOA of the carcinogen and the shape of the cancer dose-response curve.

The NAS was critical of EPA's decision to apply linear low-dose extrapolation for
TCDD cancer assessment in the 2003 Reassessment and encouraged the use of a nonlinear
approach. The 2005 Cancer Guidelines state that a nonlinear approach should be used when

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"there are sufficient data to ascertain the mode of action and conclude that it is not linear at low
doses and the agent does not demonstrate mutagenic or other activity consistent with linearity at
low doses."

Receptor modeling theory (as outlined in the 2003 Reassessment, Part II, Chapter 8)
indicates that exogenous compounds which operate through receptor binding mechanisms, such
as TCDD, will follow a linear dose-response binding in the 1-10% receptor occupancy region.
This theory has been supported by empirical findings and suggests that the proximal biochemical
effects (such as enzyme induction) and transcriptional reactions for TCDD may also follow
linear dose-response kinetics. More distal toxic effects could take any one of multiple forms
(i.e., linear, sublinear, supralinear or threshold) depending on (1) the toxic mechanism;
(2) location on the dose-response curve; and (3) interactions with other processes such as
intracellular protein binding and cofactor induction/repression.

In the case of TCDD, many adverse effects experienced at low exposure levels have too
much data variability to distinguish on a statistical basis (goodness-of-fit) between dose-response
curve options, and whether the dose-response is linear, sublinear or supralinear. For tumor
responses, with the exception of squamous cell carcinoma of the oral mucosa and adenomas or
carcinomas of the pancreas, which were fit with a linear multistage model, the tumor endpoints
in the NTP (2006, 543749) study using female Sprague-Dawley (S-D) rats are all best fit with a
sublinear model (i.e., the multistage model fits to tumor incidence data were second or third
degree; see Table 5-15 and Appendix F). For all tumor incidence data from three of the other
cancer bioassays that met the study inclusion criteria (Kociba et al., 1978, 001818; NTP, 1982,
594255; Toth et al., 1979, 197109). the multistage model fit was linear (first degree), when based
on either administered dose or modeled blood concentrations (see Appendix F). For Delia Porta
et al. (1987, 197405). the female liver carcinomas were linear (first degree), but the female liver
adenomas and the male liver carcinomas were best modeled using a second degree model (see
Table 5-15).

Another issue of potential importance when evaluating the shape of the dose-response
curve for low dose effects is the concept of "interacting background." The concept of interacting
background refers to a pathological process in the exposed population that shares a causal
intermediate with the toxicant being evaluated. On this issue, a recent NAS committee (NAS,
2009, 594307) contended that

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.. .the current EPA practice of determining "nonlinear" MO As does not account
for mechanistic factors that can create linearity at low dose. The dose-response
relationship can be linear at a low dose when an exposure contributes to an
existing disease process Crump et al., 1976, 003192; Lutz, 1990, 000399. Effects
of exposures that add to background processes and background endogenous and
exogenous exposures can lack a threshold if a baseline level of dysfunction occurs
without the toxicant and the toxicant adds to or augments the background process.

Thus, even small doses may have a relevant biologic effect. That may be difficult
to measure because of background noise in the system but may be addressed
through dose-response modeling procedures. Human variability with respect to
the individual thresholds for a nongenotoxic cancer mechanism can result in
linear dose-response relationships in the population (Lutz, 2001, 053426; NAS,
2009, 594307.

AhR activation could be considered a causal intermediate in several disease processes.
Recent studies have linked AhR activation in the absence of exogenous ligand to a multitude of
biological effects, ranging from control of mammary tumorigenesis to regulation of
autoimmunity (reviewed in Hahn et al., 2009, 548725). While the level of background activation
of AhR by endogenous compounds (or exogenous compounds other than TCDD) in the human
population is unknown, given the ubiquitous nature of several of the known endogenous and
exogenous AhR ligands, it is reasonable to assume that a certain baseline level of AhR activation
exists in the population. The degree to which TCDD exposure augments this baseline level of
AhR activation is unknown.

The 2005 Cancer Guidelines (U.S. EPA, 2005, 086237) recommend that the method used
to characterize and quantify cancer risk from a chemical be determined by what is known about
the mode of action of the compound and the shape of the cancer dose-response curve. The linear
approach is used if there is sufficient evidence supporting linearity or if the mode of action is not
understood (U.S. EPA, 2005, 086237). In the case of TCDD, (1) the mode of action of TCDD-
induced carcinogenesis beyond potential AhR activation is unknown; (2) information is lacking
to determine the shape of the dose-response curves at low doses for various adverse endpoints
(including cancer) in humans or experimental animals; (3) there is undoubtedly a certain level of
interacting background (i.e., AhR activation by endogenous ligands) in the human population;
(4) many of the rodent cancer dose-response relationships (Kociba et al., 1978, 001818; NTP,
1982, 594255; Toth et al., 1979, 197109) are consistent with low-dose linearity (first degree
multistage model fit) when based on either administered dose or modeled blood concentrations;

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and (5) higher human interindividual variability compared to experimental rodents will tend to
shift the shape of the dose-response towards linear (relative to rodents). None of these
suggestions of linearity, however, is conclusive (see next section for additional detail). The true
shape of the dose-response curve remains unknown. Therefore, in the absence of sufficient
evidence to the contrary or evidence to support nonlinearity, to estimate human carcinogenic risk
associated with TCDD exposure EPA assumed a linear low-dose extrapolation approach.

5.2.3.4.1.4. Discussion of low-dose linearity.

Any quantitative estimation of carcinogenic risk associated with TCDD exposure requires
low-dose extrapolation of high dose experimental and epidemiologic data. Unfortunately,
despite the availability of the extensive database on the biological effects of TCDD, the shape of
the dose-response curve in the low-dose region is not known. This situation is not unique to
TCDD. For most carcinogens the available biological data do not provide sufficient mechanistic
information to determine the shape of the dose-response relationship at doses below the levels
where direct experimental or epidemiologic data are available. EPA's Guidelines for Carcinogen
Risk Assessment (2005, 086237) recognize this situation and describe approaches the Agency
uses for dose response assessment in cancer risk assessments depending on the available
scientific database. EPA's basic approach makes a distinction between "low-dose linear" and
"nonlinear" dose response patterns. This distinction is important to understand as it addresses
the potential response at low dose, not the empirical pattern of response seen in the available
(often high dose) tumor data. To put matters simply, under a low-dose-linear model, the
estimated risk due to the carcinogen exposure is approximately proportional to the dose received
(at low dose). In mathematical terms, a low-dose-linear model is one whose slope is greater than
zero at a dose of zero (U.S. EPA, 2005, 086237; footnote, p. 1-11). Importantly, a low-dose-
linear model need not be linear at higher doses, and this is consistent with upward curving
responses (e.g., linear-quadratic) and downward curving (plateauing) responses that may be seen
various cancer studies. In EPA's terminology a "nonlinear" dose-response, refers to situations
where there is not a linear component in the response at low-dose. In this context, a "nonlinear
model" is one whose slope is zero at (and perhaps above) a dose of zero (ibid). Nonlinear
response patterns can include threshold models where there is no response below a defined dose

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1	level, or other patterns where response at low dose otherwise decreases rapidly as compared to a

2	low-dose-linear model.

3	As stated in the previous section, the low-dose linear approach for the TCDD

4	carcinogenicity assessment in this document is based on EPA's scientific baseline inference

5	("default") regarding dose-response modeling. EPA believes that the mode of action is not

6	known, so is using the default linear extrapolation approach specified by EPA's cancer

7	guidelines.

8	Nonetheless, there are biological data on TCDD that help inform the appropriateness of

9	low-dose-linear risk extrapolation for this compound. Furthermore, there is utility in

10	summarizing scientific reasoning that supports the approach of low-dose linearity as an

11	appropriate scientific baseline inference ("default") for carcinogen risk assessment.

12	The issues pertaining to low-dose linearity were discussed in the report of a recent state-

13	of-the-science workshop on issues in low-dose risk extrapolation held by U.S. EPA and Johns

14	Hopkins Risk Science and Public Policy Institute in 2007 (White et al., 2009, 622764). This

15	report states:

16

17	The complex molecular and cellular events that underlie the actions of agents that

18	lead to cancer and noncancer outcomes are likely to be both linear and nonlinear.

19	At the human population level, however, biological and statistical attributes tend

20	to smooth and linearize the dose-response relationship, obscuring thresholds that

21	might exist for individuals. Most notable of these attributes are population

22	variability, additivity to preexisting disease or disease processes, and background

23	exposure-induced disease processes; measurement error also undoubtedly

24	contributes to this phenomenon. The linear appearance of the population-level

25	dose-response function does not presume that the dose-response relationship is

26	necessarily linear for individuals (Lutz, 1990, 000399; 2001, 053426; Lutz et al.,

27	2005, 087763). but may reflect a distribution of individual thresholds. These

28	attributes are likely to explain, at least in part, why exposure-response models of

29	the relationship between cancer or noncancer health effects and exposure to

30	environmental toxicants with relatively robust human health effects databases at

31	ambient concentrations (e.g., ozone and particulate matter air pollution, lead,

32	secondhand tobacco smoke, radiation) do not exhibit evident thresholds, even

33	though the MO As include nonlinear processes for key events NRC (2005);

34	U.S. EPA (2006, 088089; 2006, 157071; 2006, 090110); U.S. DHHS (2004,

35	056384).

36

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Original arguments in favor of low-dose linearity for carcinogen risk assessment
(including for ionizing radiation, as developed from human data) are based on the occurrence of
damage (often termed "hits") to DNA and the inference that resulting mutations would
contribute to cancer development. These arguments envisioned direct damage to DNA;
however, based on subsequent advances in mechanistic understanding, damage to DNA by
"secondary" reactive molecules (not just direct hits to DNA by radiation or other agents) is also
considered to play a major role. TCDD is not thought to produce DNA damage directly.
However, DNA damage may result subsequent to increased formation of reactive molecules
(reactive oxygen species (ROS) and metabolites of endogenous compounds). Thus, the presence
of low-dose linearity by this pathway would depend on whether such reactive molecules were
produced at low dose and whether that increased formation was proportional to dose. If that
were the case for TCDD, which is still unknown, arguments in favor of low-dose linearity
remain similar to those for direct-acting agents.

The kinetics of ligand receptor binding, and then the attachment of a receptor/ligand
complex to a promoter region of DNA are biochemical processes where low-dose linearity can
occur. Simple receptor binding interactions are often modeled using Michaelis-Menten
relationships which are linear at low dose. Thus, the early key events in a process of a receptor-
mediated toxicity pathway may often be expected to be low-dose linear. However, as in any
toxicity process, the ultimate shape of the dose-response relationship for an apical46 toxicity
endpoint will depend on all the processes involved, not just receptor kinetics. These issues were
considered by NRC (NAS, 2009, 594307) which included as an indication for non-threshold
dose response: "The fact that in receptor-mediated events, even at very low doses a chemical can
occupy receptor sites and theoretically perturb cell functions (such as signal transduction or gene
expression) or predispose the cell to other toxicants that bind to or modulate the receptor systems
(such as organochlorines and the aryl hydrocarbon receptor or endocrine disruptors and
hormonal binding sites)." The role of these factors for TCDD has not been fully elucidated.

Two other factors supporting low-dose linearity discussed in the workshop described by
White et al. (2009, 622764) are additivity to background processes (dose additivity) and the
magnitude of human heterogeneity.

46 An apical endpoint is an observable outcome in a whole organism, such as a clinical sign or pathologic state, that
is indicative of a disease state that can result from exposure to a toxicant (NAS, 2007).

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Concerning dose additi vity. Crump et al. (1976, 003192) argued in the context of a
carcinogenic response that if the carcinogenic process resulting from exposure to an exogenous
agent (e.g., TCDD) is already operant in causing background responses, then the effect of the
exposure is to augment this process in a dose-additive fashion. The additional response caused
by the exposure is expected to increase approximately linearly with exposure at low exposures
(i.e., be low-dose linear). The NRC Science and Decisions report (NAS, 2009, 594307)
examined the issue of additivity to background, in particular calling attention to a need for
systematic consideration of endogenous processes related to disease development as well as
additivity to other exogenous exposures.47 While the baseline activity (unexposed to exogenous
agents) of AhR is not well understood, the effects of exogenous agents need to be considered in
terms of how they add on to or modulate baseline physiological processes instead of considering
TCDD or other exogenous ligands to be "acting in a vacuum."

The issue of human heterogeneity relative to the rodents used in bioassays has been
discussed at length in the literature and will not be repeated here (see also relevant text in
Section 5.2.3.4.1.3). However, as discussed by NAS (2009, 594307). even in situations where
processes thought to be nonlinear are precursors to the development of cancer in test animals, a
different situation may result in humans: "However, given the high prevalence of those
background processes, and given the multitude of chemical exposure and high variability in
human susceptibility, the results may still be manifested as low-dose linear dose-response
relationships in the human population." The population dose-response will be influenced by
heterogeneities in the population that affect internal dose as well as response. First, even if there
is strong curvilinearity in the dose-response curve in the dose range of relevance to human
exposures, there may be large differences across individuals in the doses at which transitions in
the shape of the dose-response curve occur. Greater variability in response to exposures would
be anticipated in heterogeneous populations than in inbred laboratory species under controlled
conditions (due to, e.g., genetic variability, disease status, age, and nutrition). The effect of
increased heterogeneity will be a broadening of the dose-response curve (i.e., less rapid fall-off
of response with decreasing dose) in diverse human populations and, accordingly, a greater

47 It may be noted that when there are multiple exogenous exposures, it may be difficult to ascertain which exposure
came first. However, the point is that if a combination of endogenous and exogenous factors is operative in causing
biological response, then an additional small, dose additive, exposure can be predicted to cause a proportionate
change in response.

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potential for risks from low-dose exposures (Lutz et al., 2005, 087763; Zeise et al., 1987,
060867). The degree to which heterogeneity must be increased to "linearize" sublinear
responses of varying degrees has not yet been established.

Interpreting the shape of animal bioassay dose-response model fits always involves
assumptions about the shape of the response in the unobserved range (i.e., low dose). Cancer
bioassays can provide relatively little information on actual dose-response patterns below the
point of departure. However, it is generally not possible to either exclude or affirm low-dose
linear components statistically based upon empirical modeling of the dose-response data.48
Dose-response modeling can, however, be useful in describing the size of a linear component in
the response that is compatible with study data. As an example, NRC (NAS, 2006, 198441)
advised EPA to examine the results of the NTP (2006, 543749) study as indicating nonlinearity
of the observed tumor response. Among the tumors seen in the NTP bioassay, the dose-response
shape for cholangiosarcoma is notably curvilinear in the dose range of the observed tumor
response. Figure 5-6 shows the multistage modeling of the cholangiosarcoma data from the NTP
bioassay. The BMDL is calculated at an extra risk of 0.01. Even though the MLE dose response
is nonlinear (lst-degree coefficient is zero), the dose-response curve pertaining to the statistical
upper bound on risk (calculated here as the 95% lower confidence bound on dose) is
approximately linear below the 0.01 benchmark level and roughly superposes on the EPA default
linear extrapolation (see Figure 5-6B). For the oral squamous cell carcinoma (SCC) tumor data
(plot not shown), the MLE dose-response curve itself displays low-dose linearity (lst-degree
coefficient is greater than zero) and the EPA low-dose linear extrapolation is indistinguishable
from the upper bound curve. These observations are consistent with the findings of
Subramaniam et al. (2006), that for the large majority of chemicals, straight line extrapolation of
risk from the BMDL provides slope factor values very similar to those obtained by using an
upper bound on the multistage model risk estimate. Furthermore, in this assessment, EPA has
chosen to derive oral slope factors based on combined tumor incidence whenever possible,
modeling them under an assumption of independence. A Bayesian analysis is used in this
document to develop PODs based on combined tumor risk across the significantly elevated
tumor types observed in this bioassay (see Section 5.2.3.2.3.2). As a result of this analysis, the

48 EPA policy is to allow for low-dose linearity in the modeling of tumors if a non-linear MOA has not been
established.

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central estimate for the composite dose-response curve shows little curvilinearity and the MLE
dose-response curve is substantially linear below a 0.1 extra risk level (see Figure 5-7A and
5-7B; see also Section 5.2.3.2.6.11).

The results here provide a comparison of EPA's linear (straight line) dose-response
estimates with the degree of linearity seen in the fitted dose-response curves and the statistical
upper bounds on these curves. To do this the fitted model needs to allow for the possibility of
both curvilinearity at high dose and linearity at low dose. The multistage model has these
properties, which is among its advantages for application in carcinogen risk assessment. Most
other models commonly used to fit data in the observed range do not have this property.49

One other issue relative to the determination of linearity arises in the visual interpretation
of dose-response plots. The common practice of plotting receptor kinetics data on semi-
logarithmic plots for scale convenience has unfortunately led to difficulties in the interpretation
of the shape of these relationships. An example is presented using the modeling study of Kohn
and Mel nick (2002, 199104). which was cited by NRC (NAS, 2006, 198441) in its review of
EPA's dioxin assessment as an example of nonlinear behavior at low dose: "Response is a
function of the number of occupied and activated receptors, which typically exhibit steep dose-
response relationships. For example, Kohn and Mel nick (2002, 199104) modeled the shape of
the dose-response relationship for receptor-mediated responses, using the estrogen receptor and
various xenoestrogens as a model receptor and ligands, respectively. The model included a
variety of assumptions with regard to receptor number, ligand binding affinity, and partial
agonist activities, yet in every instance clear sublinear responses were observed at low doses."
However, as shown in Figure 5-8, the apparent strong upward curvature of the low-dose
relationship is no longer seen when the results are plotted on an arithmetic scale. Instead, the
system may be seen as providing an example of close to linear behavior in the low-dose region.

49 The standard Hill models do not: A Hill model is only linear at low dose when the Hill parameter is equal to 1
(and in that case the Hill model is linear over the full dose range until the high dose region of "saturation" where the
km parameter results in downward curvature). Thus, while the Hill model is a valuable tool for fitting data in the
observed experimental range, it is not helpful in illustrating the potential for low-dose response. However, some
have considered a dose-additive version of the Hill model which would allow for low-dose linearity.

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5.2.3.4.1.5. Consideration of nonlinear methods.

While the 2005 Cancer Guidelines deem linear extrapolation to be most appropriate for
TCDD, EPA has carefully considered the NAS recommendation to provide risk estimates using
both linear and nonlinear methods.

The 2005 Cancer Guidelines state

For cases where the tumors arise through a nonlinear mode of action, an oral
reference dose or an inhalation reference concentration, or both, should be
developed in accordance with EPA's established practice for developing such
values ... This approach expands the past focus of such reference values
(previously reserved for effects other than cancer) to include carcinogenic effects
determined to have a nonlinear mode of action.

In this section, EPA presents two illustrative examples of RfD development for
carcinogenic effects of TCDD. Each of these examples focuses on data derived from animal
bioassays as described in Section 2.4.2.

5.2.3.4.1.5.1. Illustrative RfDs based on tumorigenesis in experimental animals.

TCDD has been shown to be a multisite carcinogen in both sexes of several species of
experimental animals. It also has been shown to be carcinogenic to humans. Most of the
available quantitative human epidemiologic data related to TCDD carcinogenesis are for all
cancer mortality. Mortality is a frank effect and is generally considered to be inappropriate for
RfD development, therefore, the illustrative example below utilizes available evidence from
experimental animals. Table 5-20 presents candidate PODs and RfDs for TCDD carcinogenicity
based on combined tumor responses from the animal bioassays described in Section 2.4.2. The
PODs from the NTP (2006, 549255; 2006, 543749) and Kociba et al. (1978, 0018m animal
studies were derived from Bayesian multitumor dose-response modeling (as described in
Section 5.2.3.2, Table 5-17) using a BMR of 1%. Because only TCDD-induced liver tumors
were reported by Toth et al. (1979, 197109). the BMR of 1% (POD) from that study was
generated using a first degree linear multistage model (see Table 5-15). TCDD-induced liver
tumors were reported by Delia Porta et al. (1987, 197405). with the male mouse producing the
lowest BMR of 1% (POD) using a second degree linear multistage model (see Table 5-15).
Following BMD modeling, BMDLhedS were then estimated (see Tables 5-16 and 5-17) using the

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TCDD whole-blood-concentration dose metric from the Emond model as described in Section 3.
The illustrative RfDs were derived by dividing the BMDLredS by appropriate uncertainty
factors. In each instance, a total UF of 30 was applied, comprising factors of 3 for the
toxicodynamic component of the interspecies extrapolation factor (UFA) and a factor of 10 for
human interindividual variability (UFH).

As shown in Table 5-20, the illustrative RfDs for TCDD-induced tumors range from
3.6E-1 1 for liver and lung tumors in male mice (NTP, 1982, 594255) to 1.0E-9 for adrenal
cortex, tongue and nasal/palate tumors in male rats (Kociba et al., 1978, 001818). This
illustrative RfD range for TCDD tumorigenesis falls within the range of candidate RfDs for
noncancer TCDD effects presented in Table 4-5.

5.2.3.4.1.5.2. Illustrative RfDs based on hypothesized key events in TCDD's MO As for liver
and lung tumors.

As described in Section 5.1, most evidence suggests that the majority of toxic effects of
TCDD are mediated by interaction with the AhR. EPA considers interaction with the AhR to be
a necessary, but not sufficient, event in TCDD carcinogenesis. The sequence of key events
following binding of TCDD to the AhR and that ultimately leads to the development of cancer is
unknown. While the mode of action of TCDD in producing cancer has not been elucidated for
any tumor type, the best characterized carcinogenic actions of TCDD are in rodent liver, lung,
and thyroid. The hypothesized sequence of events following TCDD interaction with the AhR is
markedly different for each of these three tumor types. Additionally, no detailed hypothesized
mode of action information exists for any of the other reported tumor types.

The endpoints selected for this illustration were evaluated to provide insight into the
quantitative relationships between tumor development and precursor events in TCDD-induced
carcinogenesis. The endpoints described below may or may not be biologically adverse in
themselves; the intent herein was to consider TCDD-induced biochemical and cellular changes
that could lead to subsequent tumor development.

In the following exercise, illustrative RfDs were derived for key events in TCDD's
hypothesized modes of action in the liver and lung. No appropriate dose-response data were
identified for key events in TCDD's hypothesized MOA for thyroid tumors in a

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sex/species/strain that has been shown to develop thyroid tumors (i.e., female B6C3F1 mice and
male and female Osborne-Mendel rats (NTP, 1982, 594255)).

As this is an illustrative exercise only, only studies that were originally identified in
Section 2 for potential noncancer dose-response modeling were evaluated here (see Section 2.4.2
for study details). There may be additional studies available in the literature that would further
inform the dose-response assessment of these endpoints.

Additionally, for animal model consistency, only results from studies conducted in
female S-D rats are presented here. The majority of the available information on TCDD
carcinogenicity (and TCDD carcinogenic precursor events) comes from studies conducted in
female S-D rats and the most recent TCDD carcinogenicity study was conducted in female S-D
rats (NTP, 2006, 197605). While both Kociba et al. (1978, 001818) and NTP (2006, 543749)
have conducted TCDD carcinogenicity studies in female S-D rats, different substrains were used;
this difference in substrain may have resulted in the different carcinogenic responses reported
from the two studies. While the carcinogenicity of TCDD in female S-D rats has been well
characterized, this animal model does not exhibit the full suite of tumor responses reported for
TCDD (for instance, female S-D rats have not been shown to develop thyroid tumors).
Additionally, the most sensitive single tumor response in female S-D rats from NTP (2006,
543749) is squamous cell carcinoma of the oral mucosa (see Section 5.2.3.2), a tumor type for
which no mode of action information exists. Therefore, the illustrative RfDs described below
may not be protective against all tumor types.

For each endpoint, PODs for illustrative cancer RfD development were identified as
described for the noncancer RfD derivation in Section 4. Briefly, for the endpoints identified
below, the NOAELreds and/or LOAELreds were determined based on EPA analysis of the
original data presented by the study author (see Section 2.4.2 for details) and by application of
the Emond PBPK models as described in Section 3.3.4. BMDLreds were determined as
described in Section 4.2 for all data sets amenable to BMD modeling. Modeling outputs for the
endpoints are presented in Appendices E and G as noted in Table 5-21. The illustrative RfDs
were derived by dividing the POD by appropriate uncertainty factors as indicated in Table 5-21.
5.2.3.4.1.5.2.1. Liver tumors.

Figure 5-9 presents one hypothesized mode of action for TCDD-induced liver tumors in
rats. TCDD activation of the AhR leads to a variety of changes in gene expression, including

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increased CYP1A1 mRNA and subsequent increases in CYP1A1 activity. These alterations in
gene expression are hypothesized to lead to hepatotoxicity, followed by compensatory
regenerative cellular proliferation and subsequent tumor development. The details of the
mechanism of TCDD-induced hepatotoxicity have not been fully determined but both CYP
induction and oxidative stress have been postulated to be involved (Maronpot et al., 1993,
198386; Viluksela et al., 2000, 198968). Additionally, oxidative DNA damage has been
implicated in liver tumor promotion (Umemura et al., 1999, 1980011 The enhanced cell
proliferation arising from either altered gene expression or hepatotoxicity, or both, could be the
principal factor leading to promotion of hepatocellular tumors (Whysner and Williams, 1996,
197556).

A dose-response relationship exists for TCDD-mediated hepatotoxicity, and this parallels
the dose-response relationship for tumor formation (or formation of foci of cellular alteration as a
surrogate of tumor formation). However, the dose-response relationship for other
TCCD-induced responses such as enhanced gene expression is different from the dose-response
for tumor formation in terms of both efficacy and potency (see Popp et al. (2006, 197074) for
review).

A representative endpoint for each of the hypothesized key events following AhR
activation for TCDD-induced liver tumors was identified and is shown in Figure 5-9. Illustrative
RfDs based on each representative endpoint are shown in Table 5-21.

5.2.3.4.1.5.2.2. Lung tumors.

Far less is known about TCDD's mode of action in the lung. Figure 5-10 presents two
hypothesized modes of action for TCDD-induced lung tumors in rats. The first hypothesized
mode of action of TCDD in the lung involves disruption of retinoid homeostasis in the liver.
Retinoic acids and their corresponding nuclear receptors, the RARs and the RXRs, work together
to regulate cell growth, differentiation, and apoptosis. It is hypothesized that TCDD, through
activation of the AhR, can affect parts of the complex retinoid system and/or other signaling
systems regulated by, and/or cross-talking with, the retinoid system (reviewed in (Nilsson and
Hakansson, 2002, 548746)). These effects are then hypothesized to lead to lung tumor
development, however the mechanisms underlying this hypothesis are not well-defined. The
second hypothesized mechanism for the carcinogenic action of TCDD in the lung is through

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induction of metabolic enzymes. Through activation of AhR and subsequent induction of
metabolizing enzymes (such as CYP1A1), TCDD may enhance bioactivation of other
carcinogens in lung (Tritscher et al., 2000, 197265). However, there are few studies to support
this hypothesis.

Representative endpoints could only be identified for two of the hypothesized key events
following AhR activation for TCDD-induced lung tumors. These endpoints are presented in
Figure 5-10. Illustrative RfDs based on each of these two representative endpoints are shown in
Table 5-21. There is insufficient information to form any conclusions on the quantitative
progression to tumorigenicity or on the relative protection afforded by preventing the key events
shown.

5.2.3.4.1.5.2.3. Limitations of illustrative RfDs based on hypothesized key events in TCDD's
MO As for liver and lung tumors.

A trend for increasing RfD values that follows the progression of endpoints towards the
production of tumors is evident. However, there are a number of factors that prevent making
strong conclusions based on this exercise. These limitations include the following

•	This example addresses only two tumor types in one species, strain and sex (female S-D
rats), with little information available on the hypothesized mode of action for lung
tumors. No mode of action information is available for the most sensitive tumor type in
this animal model (squamous cell carcinoma of the oral mucosa). Therefore, it is
possible that the illustrative RfDs presented in this example would not be protective
against all tumor types in female S-D rats. Importantly, other animal models have been
shown to be more sensitive to TCDD-induced carcinogenesis based on combined tumor
analysis (see Section 5.2.3.2); an RfD based on tumorigenesis in this animal model may
not be protective against tumorigenesis in other, more sensitive, animal models (or, by
extension, in humans).

•	Several of the BMDLs are based on poorly-fitting models, such that the RfD is based on
a LOAEL (or LOEL), which is not a particularly good measure for comparison across
endpoints (e.g., LOAELs are dependent on dose spacing in bioassays). Furthermore, the
hepatotoxicity BMDL based on a dichotomous 10% BMR, is not directly comparable to
all the other BMDLs based on a continuous 1 standard-deviation BMR (Crump, 2002,
035681). In addition, as the earlier effects (CYP induction, cellular proliferation) are not
considered to be necessarily adverse in themselves, the BMR of 1 standard-deviation
from the mean may not be the best choice for determining a POD based on biological
signficance. The use of the 1 standard-deviation BMR for the illustrative examples is
primarily for comparison on an equal-magnitude-of-response basis across endpoints.

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•	The endpoints selected as representative of each hypothesized key event may not be the
most appropriate choices. These particular endpoints were chosen because they were the
most sensitive indicator (i.e., lowest POD) from the available data or were the only
available choice based on a lack of data for other effects related to the hypothesized key
event.

•	The optimum timing of these events may not be reflected in the endpoints selected.
Almost certainly, changes in gene expression are early events, such that a single
exposure should be relevant, as in the mRNA changes reported after a single TCDD
exposure (Vanden Heuvel et al., 1994, 594318). although it is not known whether the
magnitude of these changes would be altered after longer-term exposure, or whether
longer-term exposure would be more relevant to downstream events. Similarly, single
exposures for induction of CYP enzymes would seem to relevant as a measure of the
immediate effect, but it may be longer-term repeated CYP activity that is important for
longer-term downstream events; Table 5-21 shows a nominal order-of-magnitude
difference in effect levels for similar effect magnitudes (ca. 20-fold) from single
exposures (Kitchin and Woods, 1979, 198750) and long-term exposures (53-weeks;
NTP, 2006, 543749). The relevant exposure durations for oxidative stress and later
effects are longer term, so a measurement of oxidative stress at 90-days in a rodent may
be appropriate; Wyde et al. (2001, 198575) suggest that induction of 8-oxo-dG DNA
adducts are a result of longer-term oxidative stress because of the lack of effect of single
exposures. Hepatotoxicity and hepatocellular proliferation events would appear at
successively later times, but the effective exposure levels would depend heavily on the
endpoints chosen to represent those events and the time at which they were measured.
The toxic hepatopathy endpoint reported in NTP (2006, 543749). is a general measure of
mild to moderate liver toxicity, but is measured only at the end of the study when tumors
have already appeared. Hepatocyte hypertrophy, measured at 31 weeks may be more
duration-relevant, but may not indicate actual hepatocellular toxicity.

•	The lowest of the tested doses may well be much higher, given that all animal diets are
contaminated to a certain extent by TCDD, resulting in initial TCDD body burdens in all
animals. Vanden Heuvel et al. (1994, 594318) reported TCDD liver concentrations in
control animals almost as high as for the low-dose group, which could equate to a
significant increase in the actual exposure experienced by the low-dose group. A similar
effect on the low-dose group (0.45 ng/kg) in Kitchin and Woods (1979, 198750) is
possible, although they did not report control animal tissue concentrations. Higher
exposure levels or longer-term exposures would not be affected to the same degree, as
administered TCDD levels would likely be large compared to initial body burden or low-
level feed stock exposure.

Given the limitations described above, establishing an unambiguous progression of
effects is extremely problematic given the lack of sufficient data. Identifying a RfD that could
be considered to be protective against tumorigenesis in humans based on these data and models
is subject not only to the determination of effective low doses for the RfDs in Table 5-21 but also

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to the determination of effective exposures that could be considered to be protective of all other
tumor types in female S-D rats as well as all other animal models. The latter would entail
identifying precursors that are sufficient in themselves for progression to tumorigenesis for all
tumor types. Given the disparate sequence of hypothesized key events following TCDD-induced
AhR activation for the tumor types for which some information is available, AhR
binding/activation is the only key event that is likely to be shared across tumor types. No
appropriate quantitative data on AhRbinding/activation by TCDD in relevant animal models
were located; therefore, an illustrative RfD based on TCDD AhR activation could not be
developed.

Simon et al. (2009, 594321) present a similar analysis for the liver tumors observed in the

NTP (2006, 		_|) study, showing a progression of effects from early biochemical events to

irreversible liver toxicity, culminating in tumorigenesis. While illustrative of the putative tumor-
promoting MOA for TCDD, the limitations of using such an approach within the context of an
assessment of the overall carcinogenic risk of TCDD as detailed above still apply. Simon and
colleagues also present RfDs for liver tumors and several precursor endpoints. All the RfDs
presented in Simon et al. (2009, 594321) are essentially equivalent and are 1 to 3 orders of
magnitude higher than the RfDs for equivalent endpoints presented in Table 5-21. These
discrepancies are partly due to the fact that the Emond PBPK models (Emond et al., 2004,
197315; Emond et al., 2005, 197317; Emond et al., 2006, 197316; see also Section 3.3.4) used in
this document predicts lower TCDD intakes for similar tissue concentrations than the CADM
kinetic model (Ay 1 ward et al., 2005, 197014; Carrier et al., 1995, 197618) used by Simon and
colleagues. However, a larger contributor to these discrepancies is the use of a chemical-specific
adjustment factor (CSAF) of 0.1 for the toxicodynamic component of the interspecies
uncertainty factor by Simon et al. (2009, 594321). while EPA used an uncertainty factor of 3.
EPA does not find that the in vitro evidence presented by Simon et al. in support of a CSAF of
0.1 for interspecies toxicodynamics meets the burden of proof necessary for a reduction in this
uncertainty factor.

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5.3. DERIVATION OF THE TCDD ORAL SLOPE FACTOR AND CANCER RISK
ESTIMATES

EPA was able to derive candidate OSFs for all cancer mortality from human
epidemiologic studies as well as for individual and combined tumor incidence from rodent
cancer bioassays. Each of these studies was selected for TCDD dose-response modeling using
the study inclusion criteria outlined in Section 2. The derivation of these OSFs can be found for
the epidemiologic data in Section 5.2.3.1 and for the rodent bioassay data in Section 5.2.3.2.

The OSFs based on epidemiologic studies from three cohorts ranged from 3.75 x io5 to
2.5 x 106 per mg/kg-day (see Tables 5-1 and 5-3). For the animal data, OSFs based on
individual tumors were developed for 28 study/sex/endpoint combinations, and the results ranged
from 1.8 x 104 to 5.8 x 106 per mg/kg-day (see Table 5-16). The OSFs based on combined
tumors were developed for 7 study/sex combinations, and the results ranged from 3.2 x 105 to
9.4 x io6 per mg/kg-day (see Table 5-17). Figure 5-11 demonstrates the range of these OSFs in
units of per mg/kg-day. The human study OSFs are shown at the far left of the figure, and the
rodent endpoints are arranged by species to the right. For comparison with the other studies, the
OSF from Cheng et al. (2006, 523122) is based on a 1 10~6 risk level (Table 5-3).

As recommended by expert panelists at EPA's 2009 Dioxin Workshop (U.S. EPA, 2009,
522927) and in the 2005 Cancer Guidelines (U.S. EPA, 2005, 086237). EPA has chosen to give
higher consideration to the human epidemiologic data rather than the animal bioassay data in
developing an OSF for TCDD. Candidate OSFs derived from the human data are consistent with
the animal bioassay OSFs; specifically, the human OSFs fall within the same range as the animal
bioassay OSFs. Because all the human and animal studies were considered to be of high quality
and yielded similar ranges of OSFs, EPA has chosen to rely on the epidemiologic data for OSF
derivation.

The strengths and limitations of the five epidemiological studies meeting the inclusion
criteria for cancer dose-response modeling are summarized in Table 5-22. Among the human
studies, the occupational TCDD exposures in the NIOSH and Hamburg cohorts are assumed to
be reasonably constant over the duration of occupational exposure. In contrast, the TCDD
exposure patterns in the Seveso and BASF cohorts are associated with industrial accidents; as a
consequence, the exposure patterns are acute, high dose followed by low-level background
exposure. Such exposure patterns similar to those experienced by the BASF and Seveso cohorts

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have been shown to yield higher estimates of risk when compared to constant exposure scenarios
with similar total exposure magnitudes (Kim et al., 2003, 199146; Murdoch and Krewski, 1988,
548718; Murdoch et al., 1992, 548719). Thus, EPA has judged that the NIOSH and Hamburg
cohort response data are more relevant than the BASF and Seveso data for assessing cancer risks
from continuous ambient TCDD exposure in the general population.

The NIOSH (Cheng et al., 2006, 523122; Steenland et al., 2001, 198589) and Hamburg
(Becher et al., 1998, 197173s) cohort studies report cumulative TCDD levels in the serum for
cohort members. The most significant difference among the Cheng et al. (2006, 523122)
analysis and those of Steenland et al. (2001, 198589) and Becher et al. (1998, 197173) is the
method used to back-extrapolate exposure concentrations based on serum TCDD measurements.
Steenland et al. (2001, 198589) and Becher et al. (1998, 197173) back-extrapolated exposures
and body burdens using a first-order model with a constant half-life. In contrast, Cheng et al.
(2006, 523122) back-extrapolated body burdens using a kinetic modeling approach that
incorporated concentration- and age-dependent elimination kinetics.

Although all three of these are high-quality studies, the kinetic modeling used by Cheng
et al. (2006, 523122) is judged to better reflect TCDD pharmacokinetics, as currently
understood, than the first-order models used by Steenland et al. (2001, 198589) and Becher et al.
(1998, 197173). EPA believes that the representation of physiological processes provided by
Cheng et al. (2006, 523122) is more realistic than the assumption of simple first-order kinetics
and this outweighs the attendant modeling uncertainties. Furthermore, the use of kinetic
modeling is consistent with recommendations both by the NAS and the Dioxin Workshop panel.

However, as discussed in Section 3.3.2, the kinetic model that they employed does have
certain limitations, including the fact that it has been calibrated based on a relatively small
number of human subjects. In addition, their kinetic model does not allow body mass index
(BMI; and hence fat content) to vary with age, which may bias the model results. Nonetheless,
EPA prefers the increased technical sophistication of the dose estimates used in the cancer
mortality risk estimates derived from Cheng et al. (2006, 523122) to those derived from
Steenland et al. (2001, 198589).

EPA, therefore, has decided to use the results of the Cheng et al. (2006, 523122)
study for derivation of the TCDD OSF based on total cancer mortality as calculated by
EPA using data and models from the Cheng et al. (2006, 523122) study as described in

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Section 5.2.3.1.2. Although the OSF is only strictly defined for exposures above the
background exposure experienced by the NIOSH cohort, which was assumed to be 0.5
pg/kg-day TCDD, or 5 pg/kg-day total TEQ, EPA assumes that the slope (risk vs. blood
concentration) is the same below those background exposure levels as it is above. Table 5-3
shows the oral slope factors at specific target risk levels (OSFRLs) which range from
1.1 x 10s to 1.3 x 106 per (mg/kg-day). EPA recommends the use of an OSF of 1 x 106 per

	£		q

(mg/kg-day) when the target risk range is 10 to 10 . Although EPA prefers the human
data, EPA also presents a number of OSFs derived from rodent bioassays. Most of these
animal studies are of note, because in general they were well-designed and conducted. In
particular, the NTP (2006, 543749) study was recently conducted and represents the most
comprehensive evaluation of TCDD chronic rodent toxicity to date.

5.3.1. Uncertainty in Estimation of Oral Slope Factors from Human Studies

A fair amount of uncertainty is associated with the estimation of slope factor values and
cancer risk specific doses for TCDD based on the epidemiological studies. In some instances,
the influence of a given factor is theoretically amenable to analysis, but such investigation is
limited by the availability of sufficiently detailed data to support such an analysis. In other
cases, only very broad ranges can be placed on the uncertainty associated with a given feature of
the analysis, or uncertainties must be discussed qualitatively.

The following four sources of uncertainty are addressed in this section: uncertainty in
exposure estimates in the epidemiologic studies (see Section 5.3.1.1), uncertainty in the shape of
the dose-response curve (see Section 5.3.1.2), uncertainty in extrapolating risks below exposure
levels in the reference population (see Section 5.3.1.3), uncertainty in cancer risk estimates
arising from background DLC exposure (see Section 5.3.1.4) and uncertainty in cancer risk
estimates arising from occupational coexposures to DLCs (see Section 5.3.1.5). Section 5.3.2
explores other sources of uncertainty in the epidemiologic risk estimates including the use of
cancer mortality rather than cancer incidence data in the derivation of the oral slope factor,
possible influences of inter-individual variability in TCDD kinetics, and exposures to other
occupational carcinogens.

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5.3.1.1. Uncertainty in Exposure Estimation

The major technical challenge within each of the epidemiological studies was developing
relevant and precise estimates of exposure. While Warner et al.(2002, 197489) collected blood
samples relatively close to the time of the Sevesso accident and could reasonably estimate peak
exposures based on these collected samples, in the case of the Becher et al. (1998, 197173). Ott
and Zober (1996, 198408). Steenland et al. (2001, 198589). and Cheng et al. (2006, 523122)
studies, the major exposure issues included the following

•	Selecting (an) appropriate dose metric(s) for dose-response modeling,

•	Estimating serum TCDD levels for the entire cohort based on measurements from a
smaller number of the subjects in the cohort collected long after the occupational
exposures had occurred, and then assigning exposures to the remaining members of the
cohort based on qualitative job classifications.

•	Estimating time-weighted average tissue doses (e.g., lipid-average serum concentration
over time) based on single samples taken at one point in time. (Except for the Becher et
al. (1998, 197173) analysis where one of the study strengths was their estimate of TCDD
half life, which utilized repeated measurements from a subset of their cohort).

In the Becher et al. (1998, 197173), Steenland et al. (2001, 198589), and Cheng et al.
(2006, 523122) studies, dose-response modeling was performed using ppt-years 1 ipid-adjusted
serum concentration as the primary dose metric for TCDD; serum TCDD was the only direct
measurement of exposure or dose that was available. In addition, as discussed in Section 3.3.4,
serum concentration is a reasonable index of total tissue concentration (target organ dose), and
lipid-adjusted serum concentration provides a reasonable index of TCDD in the fatty components
of tissues. Ott and Zober (1996, 198408) used ng/kg body weight at the time of the accident as
the primary dose metric, and U.S. EPA (2003, 537122) later converted these to units of ppt-years
lipid-adjusted serum concentration.

The decision to use cumulative serum concentrations (ppt-years) as the primary dose
metric for carcinogenicity is based on the understanding that time weighted concentrations (over
a chronic exposure period) are the most appropriate dose measures for cancer risk assessment.
This may not be strictly true if cancer induction by TCDD is considered to be a "threshold
process." However, as discussed in Section 5.2, there are reasonable grounds to believe that the

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assumption of low-dose linearity is reasonable for TCDD, especially when calculating
population risks where the effects of interindividual variability must be taken into account.

In addition to the issue of low-dose thresholds, the rationale for using cumulative dose
metrics also can fail at high doses if the adverse response in question involves a step that is
saturable (e.g., where there is a maximum level of response that cannot be exceeded owing to a
rate-limited process). There is some evidence for such a phenomenon in the NIOSH cohort
where cancer risks in the highest exposure group (>50,000 ppt-years) appear to saturate, and the
response decreases at this level (Steenland et al., 2001, 198589). Steenland et al. (2001, 198589)
suggest that the apparent saturation of dose-response in this cohort may be due, at least partially,
to exposure misclassification among the highest exposed individuals, rather than to an actual
reduction in response per unit exposure.

The uncertainty associated with differences in the exposure patterns is important to
consider across the five epidemiologic studies. Steenland et al. (2001, 198589). Cheng et al.
(2006, 523122). and Becher et al. (1998, 197173) studied cohorts exposed to elevated TCDD
levels over a long period of time, while Ott and Zober (1996, 198408) and Warner et al.(2002,
197489) studied cohorts exposed to TCDD levels significantly above background at one point in
time but the exposures and likely the TCDD body burdens declined significantly following these
periods of elevated exposure. Both these chronic and acute exposures can be analyzed in terms
of cumulative exposure to TCDD. Use of such a metric requires an assumption that the "actual"
cancer potency associated with a cumulative dose where much of the dose is received at a single
point in time and then gradually eliminated would be similar to the cancer potency of the same
cumulative dose received over a longer period of time and also gradually eliminated. While EPA
believes that such an assumption is not unreasonable, the experiment of Kim et al. (2003,
199146). which showed statistically significant increase in liver effects due to a peak TCDD
dose when compared to chronically-dosed Sprague-Dawley rats administered the same levels of
TCDD when measured as a cumulative dose, suggests that additional analyses of cumulative and
peak TCDD dose measures may need to be conducted.

There are uncertainties associated with the approaches used to estimate TCDD exposures
in the members of the occupational epidemiologic studies for which no measurement data were
available. To impute TCDD levels for workers without measured samples, all four occupational
epidemiologic studies matched workers for whom measured TCDD samples had never been

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reported to workers with measured TCDD levels based on job histories. The NIOSH cohort is
used to illustrate some of the uncertainties. In the NIOSH cohort, the subset of workers (roughly
5% of the total cohort) with blood serum data comprised surviving members of the cohort (in
1988), and therefore, their age distribution likely differed from the rest of the cohort. For each
worker in this subset, the following data were available: (1) job classification information,
(2) employment history, and (3) serum TCDD measures. All of the workers in this subset were
employed at a single plant where the work histories were less detailed than at other plants, and
many of the workers at this plant had the same job title and were employed during the same
calendar period. There is an assumption that workers with same job title and work history were
exposed to the same TCDD levels within a plant and across plants; this obviously does not
account for exposure heterogeneity.

Both Steenland et al. (2001, 198589) and Cheng et al. (2006, 523122) addressed the
potential for exposure measurement error in TCDD estimates and possible exposure
misclassification. For the highest exposure workers, Steenland et al. (2001, 198589) and Cheng
et al. (2006, 523122) found weak, "noisy," and/or negative exposure-response relationships.
Steenland et al. (2001, 198589) suggests that possible explanations for this observation include
the saturation of effects at the upper end of the dose-response curve, instability of the TCDD
exposure estimates based on the limited number of highly exposed individuals, and the increased
probability of exposure misclassification for workers whose job histories indicate the highest
exposures. As Steenland et al. (2001, 198589) reported, some of the highest exposures might
have been inaccurately estimated because they occurred in workers exposed to short-term, high-
dose exposures during spill clean-up. Cheng et al. (2006, 523122) used sensitivity analyses to
examine this measurement error issue and evaluated the potential for exposure misclassification
by using ln-transformed TCDD ppt-years. The authors removed all observations with exposures
within the lower and upper 1, 2.5, or 5th percentiles of the TCDD ppt-year distribution and also
removed observations within just the upper 1, 2.5, or 5th percentile of TCDD ppt-years. These
sensitivity analyses yielded results similar to those reported in the primary analysis. An
additional concern is that exposure errors might distort the exposure distribution in the
population, which generally spreads the response out over a wider dose range. This serves to
increase the variance of the regression model, altering both the POD and the corresponding OSF.

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Becher et al. (1998, 197173) only considered workers from a single plant but their
analysis included workers employed in five different job locations within the plant. The
influence of worker location on slope factor estimates does not appear to be further explored and
may represent a source of uncertainty.

To estimate long-term body burden metrics from the serum TCDD measurements,
Steenland et al. (2001, 198589) employed simple first order kinetic elimination rate model with a
half-life of 8.7 years. Limitations of this approach include (1) the average elimination half-life
among the study subjects may not be 8.7 years given differences between the study population
and the Ranch Hand population from which the value was estimated, (2) use of a single-value
estimate fails to take into account the inherent variability in elimination half life among the
individual workers, and (3) it fails to take into account variations in elimination kinetics
throughout the lifetime of the exposed worker due to change in body fat, age, etc. The impact of
these potential sources of bias on the estimates of time-integrated body burden cannot be
quantitatively assessed. However, Steenland et al. (2001, 198589) noted that modest changes in
elimination half-life (to 7.1 years) had only a very small impact on risk estimates.

Cheng et al. (2006, 523122) estimated past body burdens using the CADM approach
(described in Section 3) (Aylward et al., 2005a, b) rather than a half-life estimate. As noted
above, the incorporation of concentration- and age-dependent elimination into this approach has
significant advantages over the use of a constant elimination half-life. However, as discussed in
Section 3.3, the CADM has only been subject to limited testing against human validation data
sets, so the degree to which its advantages are realized in practice cannot be easily assessed.

There are no available human data in the low dose region, the region of interest to this
assessment, to compare with the CADM (or Emond) model predictions.

Becher et al. (1998, 197173) developed half life estimates based on multiple TCDD
blood measures in 48 individuals from this cohort. These half life estimates were then used to
back calculate TCDD concentrations at the end of each worker's employment, accounting for
age and percentage of body fat. This cohort-specific information may provide a better exposure
estimate than Steenland et al. (2001, 198589) or Ott and Zober (1996, 198408) who used similar
kinetic approaches. However, the comparison of the accuracy of the exposure estimates across
the cohorts is not easily assessed. There are several assumptions and important uncertainties
involved in modeling TCDD exposures in these cohorts. The study authors have invoked

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different kinetic assumptions when extrapolating measured levels of TCDD in sera backward in
time to estimate higher chronic or peak dosage (i.e., there is uncertainty in these back-
calculations that includes assumptions regarding elimination kinetics). There is also uncertainty
in applying such estimates to other members of the cohort based on similar characteristics (e.g.,
job category).

5.3.1.2. Uncertainty in Shape of the Dose-Response Curve

Another source of uncertainty is the nature of the dose-response curve in the low dose
region of interest for risk assessment for environmental exposures (e.g., <1 pg/kg-day). The
epidemiologic data are based on occupational studies in which exposures were often several
orders of magnitude higher than environmental exposures. In these studies, data from the low
dose region are quite sparse, and only one study examined uncertainty due to the low dose
region. Steenland and Deddens (2003, 198587) attempted to analyze this region specifically by
fitting threshold curves to the NIOSH data in which there was no extra risk from exposure until
some specific level. However, this model did not fit as well as models without a threshold. In
general, the usual assumption of linearity in the low dose region seems reasonable when using
epidemiologic data given the lack of data in this region that precludes the rejection of linearity.

There is uncertainty in the extrapolation of the OSF to the low dose region (e.g.,
<5 pg/kg-day). EPA developed the cancer assessment in this document assuming the slope in the
low-dose region of the dose-response curve is linear; the decision was made due to the lack of
sufficient evidence to support an assumption of nonlinearity as outlined in the EPA's Cancer
Guidelines (U.S. EPA, 2005, 086237). Similarly, there is uncertainty as to whether a threshold
exists for TCDD-induced toxicity leading to tumorigenesis and the dose associated with such a
threshold, if it exists, is unknown. EPA chose to model this dose-response without a threshold
because there is insufficient evidence to support an assumption of a threshold.

It also is noteworthy that the shapes of the exposure-response in several of these studies,
based on the published statistical models, is indicative of a response that tends to tail off or
"plateau" at high cumulative exposures to TCDD. This phenomenon has been seen in many
studies of occupational carcinogens, and may reflect a number of things including exhaustion of
people susceptible to cancer, saturation of biological pathways which are part of the pathway to

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cancer, and increased error measurement of dose at high levels biasing dose-response towards
the null (Stayner et al., 2003, 054922).

5.3.1.3. Uncertainty in Extrapolating Risks below Reference Population Exposure Levels

Another source of uncertainty in using human epidemiologic data is due to the lack of
completely unexposed populations; there are no human populations that have zero dioxin
exposure. The cancer exposure responses modeled in all epidemiologic cohorts, whether
primarily exposed via occupational or environmental exposures, can be evaluated with
confidence only above the lowest exposed group (i.e., the reference population). There are
substantial uncertainties associated with estimating cancer risks from background exposures of
TCDD and DLCs because these risks are aggregated in the overall background risk of the
referent population, to which outcomes of cohort subjects experiencing higher dioxin exposures
are compared. Therefore, the risk modeled from the epidemiologic data is unavoidably the
incremental risk above a background exposure to dioxins in the general environment (assumed to
be primarily from food intake). Typically, serum TCDD levels in the general populations in the
geographic locations and times at which the epidemiologic studies were undertaken have been
reported to be on the order of 5 to 20 ppt (Mocarelli et al., 1991, 199600)(WHO. 1998; Pin sky
and Lorber, 1998). Hence, the extra risks should be considered as those incurred by added
exposure above these background exposures, which then introduces uncertainty associated in the
cancer slope factor estimate at exposures below background levels. EPA assumes that the slope
of the risk curve below the background exposure experienced by the epidemiologic study cohorts
is the same as the (modeled) slope above those background exposure levels; data do not exist to
test this assumption.

Also, background TCDD/DLC exposures experienced by the epidemiologic study cohorts
have been estimated to be much larger (5 to 10-fold) than current background levels. Lorber et
al. (2009, 543766) estimate that current U.S. intake rates are roughly 0.58 pg TEQ/kg-day at the
50th percentile and suggest that human TEQ ingestion exposures likely peaked in the 1970's.
Steenland et al. (2001, 198589). presumably based in part on WHO (1998), estimated
background intake rates to be 5 pg TEQ/kg-day for the NIOSH cohort. As a result, the
assessment of cancer mortality risk at current background exposure levels is also subject to
extrapolation uncertainty.

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5.3.1.4. Uncertainty in Cancer Risk Estimates Arising from Background DLC Exposure

None of the slope factors presented in this document, whether based on epidemiologic
studies or animal bioassays, takes into account the impact of background exposure to DLCs.
Background DLC exposure can be estimated for only one of the animal cancer bioassays NTP
(2006, 543749). Background TCDD and DLC exposure for the rats in the NTP (2006, 543749)
does not appear to have been significant, with respect to the magnitude of administered doses
(see Section 5.3.2.1). However, given the trend towards lower exposures to TCDD in recent
years, the TCDD/DLC exposure may have been much higher in the older studies (e.g., Kociba et
al., 1978, 001818; NTP, 1982,	1; Toth et al., 1979, •). The impact of background

TCDD/DLC exposure on the cancer risk modeling of any of the bioassay data would be to
increase the dose term associated with each response; consequently, increasing the magnitude of
the BMDL, with a proportional reduction in the magnitude of the slope factor, although the
effect would probably be small (see Section 5.3.2.1). Note that the shift in dose increases the
estimated low doses proportionately more than the higher doses, potentially obscuring the
relationship between dose and response in the low dose region.

Background dioxin exposure for the epidemiologic cohorts, however, could have been
substantial with respect to the TCDD exposures in the reference populations used in the
modeling. As an example, the background dioxin intake the NIOSH cohort, which is the basis
for the oral slope factor described previously in this section (5.3), was estimated to be
0.5 pg/kg-day for TCDD and 10 times higher (5 pg/kg-day) for total TEQ (Steenland et al., 2001,
197433)(WHO. 1998). WHO (1998) estimated that TCDD comprised only about 5 to 10% of
total TEQ from exposure to DLCs in food, based on DLC exposure estimates and TEFs available
at that time. Eskenazi et al. (2004, 197160) estimated that TCDD was 20% of total TEQ in the
serum of the reference population in the Seveso Women's Health Study from measurements
taken in 1976. Based on more recent estimates (Lorber et al., 2009, 543766). TCDD is about
10% of total TEQ in human serum in the United States. Steenland et al. (2001, 198589) assumed
a (cumulating) background exposure of 5-6 ppt TCDD and 50 ppt total TEQ per year in serum
for their analysis of the NIOSH cohort cancer mortality response. The resulting cumulative
background exposures, particularly for total TEQ, are large compared to the lower cumulative
occupational exposures over the life-time of the cohort (birth to death or end of follow-up).

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Crump et al. (2003, 197384). based on Steenland et al. (2001, 198589), assumed a cumulative
background serum concentration of 3,000 ppt-year for total TEQ (50 ppt/year x 60 years), which
is much larger than the lower NIOSH cohort occupational TCDD exposures. The latter, when
grouped in cumulative TCDD serum-concentration septiles Steenland et al. (2001, 197433),
range from 260 to 850 ppt-yr in the first few septiles. Conceivably, the much larger background
exposure could have a somewhat larger effect on the slope factor than for the relatively lower
background exposure in the animal bioassays. Because the Cheng et al. (2006, 523122)
modeling does not account for background TEQ, the resulting slope factor is biased high. None
of the published analyses of the NIOSH cohort data (Cheng et al., 2006, 523122; Crump et al.,
2003, 197384; Steenland et al., 2001, 198589) present an analysis that addresses the effect of
background TEQ exposure on the modeled risk.50 Given the data and modeling results currently
available, the EPA could not find an approach for expressing the quantitative impact with any
accuracy or confidence.

5.3.1.5. Uncertainty in Cancer Risk Estimates Arising from Occupational DLC Coexposures

The slope factor estimates are based on an assumption that occupational exposure was
entirely to TCDD, with no explicit consideration of the risk attributable to occupational DLCs.
Because TCDD typically occurs as a component of a mixture with other DLCs that are assumed
to affect cancer risk through dose addition, the assumption that the exposures are entirely TCDD
could lead to a positive bias in the slope factor estimates derived from these epidemiologic
studies, if the estimates are confounded by other exposures to DLCs and the TEQ dose is larger
than the fraction accounted for by TCDD alone. The magnitude of the potential bias can be
estimated in a general way through the estimation of risks for plausible mixtures of DLCs and
TCDD exposures in the cohort with the same composition as the Steenland et al. (2001, 198589)
and Cheng et al. (2006, 523122) studies, but the detailed data required to perform such an
analysis on the NIOSH cohort are not available. In addition to the slope factor estimated for
TCDD, Becher et al. (1998, 197173) also evaluated the slope based on TEQs. They found a
dose-response effect for TCDD but not for TEQ (excluding TCDD) which suggests that
confounding by DLCs did not occur.

50 Steenland et al. (2001, 1974331 present a TEQ analysis but for a scenario where total TEQ is 10 times the TCDD
exposure for both background and occupational exposure.

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5.3.2. Other Sources of Uncertainty in Risk Estimates from the Epidemiological Studies

Other aspects of the Steenland et al. (2001, 198589). Cheng et al. (2006, 523122). Becher
et al. (1998, 197173). and Ott and Zober (1996, 198408) studies that are not directly associated
with TCDD or DLCs may contribute uncertainty to the cancer slope factor estimates. This
section lists several of these and discusses their potential directional bias in slope. General issues
associated with potential confounding effects also were discussed in the 2003 Reassessment
(U.S. EPA, 2003, 537122).

All of the studies that meet the criteria (with the exception of Warner et al., 2002,
189) measure cancer mortality rather than cancer incidence. This likely biases the slope
factor downward relative to a slope calculated for cancer incidence, the typical basis of EPA
cancer slope factors. In the NIOSH cohort, roughly one-third of the fatal cancers were identified
as lung cancer. Because of the high case mortality rate associated with lung cancer during the
period of cohort evaluation (e.g., the 5-year relative survival rates for lung cancer were less than
10% before 1973 and were less thanl5% before 1995 (Horner et al., 2009), the slope factor
estimated for cancer mortality might not be much lower than that calculated for cancer incidence.
This assumes that the outcome of a cancer incident (i.e., cancer mortality) is independent of
occupational TCDD exposure levels. Estimation of cancer incidence in the general population
associated with TCDD exposure would require assumptions related to the relative survival and
age-specific cancer risks in the exposed population compared to the NIOSH cohort or the
Hamburg cohort; insufficient data are available to support such an analysis.

The routes of TCDD exposures in the occupational cohorts include dermal and inhalation
exposures (Steenland et al., 1999, 197437). the U.S. population is assumed to be primarily
exposed through the intake of TCDD and DLCs in foods). Given the persitence of TCDD in the
body, differences in exposure routes may not be significant, but route-specific effects can not be
precluded. The directional bias on the slope factor that is associated with this uncertainty is not
known.

Occupational exposures to other carcinogens could lead to uncertainty in the slope factor.
For example, in addition to TCDD, the Hamburg cohort was also exposed to
hexachlorocyclohexane (HCH), which IARC classified as possibly carcinogenic to humans, and
lindane, which EPA (2001) stated had "suggestive evidence of carcinogenicity, but not sufficient
to assess human carcinogenic potential." While such co-exposures would not bias the exposure

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metric (i.e., not dose additive), to the extent that they were correlated with TCDD exposure, the
cancer mortality risk attributed to TCDD would be overestimated,biasing the slope factor high
because all cancers are attributed to TCDD. To examine this, Cheng et al. (2006, 523122)
assessed the impact of possible confounding by conducting excluding individual plants in the
modeling. If the estimated cancer risks as a function of exposure did not change too much when
specific facilities were left out, then confounding was deemed unlikely. Cheng et al. (2006,
523122) likewise found little variation in risks based on these analyses.

There is adequate evidence to believe age, gender, and body fat content all can have a
significant impact on elimination kinetics and consequent cancer risks associated with TCDD
exposure (U.S. EPA, 2003, 537122). While the authors evaluating the Hamburg cohort
accounted for such impacts in their kinetic analysis, interindividual kinetic differences were not
considered in evaluations of other cohorts.

There may be gender differences that affect susceptibility to TCDD exposure. The
cohorts analyzed by Steenland et al. (2001, 198589). Cheng et al. (2006, 523122). Ott and Zober
(1996, 198408) and Becher et al. (1998, 197173) were comprised almost exclusively of men.

This precluded systematically addressing differences between males and females in these studies.
Further, because EPA could not develop an estimate from the Warner et al. (2002, 197489)
cohort, none of the studies analyzed here for cancer dose-response contained a significant
percentage of women. Thus, the generalizability of the slope factor estimates to women is
uncertain.

Finally, of these cancer cohorts only the Seveso cohort included children. The unique
sensitivities of infants, toddlers, and children cannot be addressed based on information in the
occupational cohorts, although the increases in cancer risk in the Seveso cohort, to date, appear
to be modest. Aside from differences in exposure patterns and body fat content, the unique
developmental status of children may result in a substantially different profile of cancer risks
(and magnitudes of those risks) than can be addressed by simply compensating on the basis of
differences in body weight, food intake, etc. Further, because EPA could not develop an
estimate from the Warner et al. (2002, 197489) cohort, none of the studies for cancer dose-
response analyzed contained a significant percentage of women. Thus, the generalizability of the
slope factor estimates to women and children is uncertain.

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A number of other factors are routinely evaluated in cancer epidemiology studies, but
appear likely to have little impact on the direction of the slope factor; however, they likely
increase overall variability either in the dose or response. These include smoking and lifestyle
factors. Intraindividual variation in TCDD kinetics and susceptibility also could affect the
relationship between exposure and cancer risk. In each of these cases, it is difficult to determine
the directional bias these factors introduce into the derivation of the slope factor, unless
somehow they are correlated with with occupational dioxin exposures.

5.3.2.1. Effect of Added Background TEQ on TCDD Dose-Response

A source of uncertainty for TCDD dose-response modeling is the impact that background
exposures of TCDD and other DLCs might have on the modeling output. As mentioned
previously in Text Box 4-1, NTP (2006, 543749) presented measurements of TCDD in the fat of
control animals. To study the potential impact of background TCDD and total TEQ on the
cancer dose-response modeling for the NTP (2006, 197605) study, EPA has estimated
background levels of TCDD and TEQ (based on total TCDD, PeCDF and PCB126) from the
mixture study to serve as surrogates for background exposures in the TCDD-only study (limit of
detection too high for control level measurements). Background doses were estimated as:

Chemicalt(B) = Chem^ifa^Mc)/™'l x(Eq 5.9)
TCDD\fatTCDD J

where

Chemicali(B)

Chemicali(fatMc)

TCDD(fatxcDD)

DosexcDD

TEF;

= estimate of background exposure to Chemical i in ng/kg units of TCDD
blood concentrations at 105 weeks, for i = TCDD, PeCDF and PCB126.

= mean pg/g of Chemical i in the fat tissues of the control animals at
105 weeks in mixtures study (NTP, 2006, 		_j).

= mean pg/g of TCDD in the fat tissues of the 3 ng/kg dose group at
105 weeks in the TCDD study (NTP, 2006, 197605).

= 2.56 ng/kg TCDD blood concentration for the 3 ng/kg dose group in the
TCDD study (from the Emond rat PBPK modeling of NTP, 2006,
197605)

= Toxicity Equivalence Factor for Chemical i (from Van den berg et al.
(2006, 543769)).

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Assuming simple proportionality of blood TCDD concentrations between controls and
low-dose (3 ng/kg) animals, the TEF-adjusted ratio of each congener (Chemical z) in control-
animal fat to low-dose-animal fat is multiplied by the modeled TCDD blood concentration for
the low-dose animals to obtain an equivalent background exposure in the dose metric (ng/kg
whole blood) used to calculate all the OSFs in this assessment. For total TEQ, the estimates
across the three congeners are summed. The total TEQ estimates are biased somewhat high
because they are based on terminal (2-year) measurements rather than representing lifetime
averages. Background exposures are then added to the modeled TCDD blood concentrations for
several different background exposure scenarios (see Table 5-23) prior to conducting
Benchmark-Dose (BMD) modeling.

BMD modeling was conducted for the cholangiocarcinoma endpoint in the TCDD study
(NTP, 2006, 197605). This was done for scenarios that added the following estimated TCDD or
TEQ background doses to the TCDD study doses: background TCDD only, total estimated TEQ,
twice the total TEQ and ten times the background TCDD (see Table 5-23). These doses may
bound the potential background exposures as TCDD has been thought to represent about 10% of
all TEQs at environmental levels (WHO, 1998). Table 5-24 shows that, as expected, adding to
the exposure term increases the BMDL (and decreases the OSF) and also shifts the shape of the
dose-response slope slightly towards sublinear (see Appendix I). However, at these background
exposure levels relative to the administered dose levels, there is very little quantitative impact on
the cancer dose-response modeling for the NTP (2006, 197605) study. Even with the most
extreme assumption that background TCDD is only 10% of total background TEQ, the BMDL
changes by only 12%. Assuming that background exposures were higher for older studies (e.g.,
Kociba et al., 1978, 001818; NTP, 1982, 594255), the impact would be somewhat higher, but
unless the background exposures were substantially higher than the lower tested doses (ca.
1-10 ng/kg-day), a significant change in the dose-response modeling results would not be
expected.51

However, as discussed previously, background TEQ exposures were likely very high
with respect to the lower occupational TCDD exposure levels as reported in the epidemiologic
studies. Table 5-25 shows the relative increase in exposure levels (as cumulative serum TCDD

51 Note that the situation is different for single-exposure studies where accumulated body burden from background
exposures could be higher than the lowest administered dose (see Tex Box 4.1 in Section 4.4).

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concentrations) for the NIOSH cohort septiles assuming that total background TEQ is 10 times
background TCDD and that 50 ppt TEQ per year is accumulated in serum (Crump et al., 2003,

84; Steenland et al., 2001, 198589). Although definitive quantitative analyses have not yet
been published or designed, the impact on modeled TCDD risk from these studies could be
substantial. The expectation for the direction of the effect would be the same as for the animal
bioassays; adding to the exposure magnitude without changing the response would decrease the
unit risk.

5.3.3. Approaches to Combining Estimates from Different Epidemiologic Studies

Meta-analyses and pooled analyses are two common approaches for combining
epidemiologic study data. Meta-analyses are a useful way to combine epidemiologic data from
different studies and derive a common estimate of effect, particularly when there are a large
number of comparable studies that are fairly homogenous as to make them possible to combine.
A meta-analysis often involves a weighted average of effect measures, dose-response
coefficients, orEDoiS.

Unlike a meta-analysis, a pooled analysis combines the original exposure and health
outcome data across multiple studies, enabling a fit of new models to the data which were not
used in the original publications. Whereas a pooled analysis of the four different cohorts
considered here would be useful to explore the functional form and fit of models (either
statistical or multistage) across all four cohorts, this would entail a lengthy undertaking and is not
being contemplated here, due in part to concerns about the confidence in the results of such an
undertaking.

5.3.3.1. The Crump et al. (2003,197384) Meta-analysis

Crump et al. (2003, 197384) published a meta-analysis that incorporated data from the
three studies EPA used in the quantitative dose-response modeling presented in the 2003
Reassessment (U.S. EPA, 2003, 537122). These three study populations were the NIOSH
(Steenland et al., 2001, 197433). the Hamburg (Becher et al., 1998, 197173). and the BASF (Ott
and Zober, 1996, 198408) cohorts. The data for the NIOSH study included six additional years
of follow-up and improved TCDD exposure estimates that had not been applied to EPA's dose-
response modeling in the 2003 Reassessment. This study examined the relationship between

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24

25

26

27

28

29

30

31

TCDD exposure and all-cancer mortality. SMR statistics that had been used in all three studies
were applied.

The Crump et al. (2003, 197384) analysis was based on published data, and therefore,
selection of the dose metric was limited to how aggregated data had been presented in the
publications. For the NIOSH component of the analysis, the exposure data were based on
worker-specific data and specific processes performed at each plant (Steenland et al., 2001,
i ). The previous approach assigned workers that had broad categories of exposure
duration with the same cumulative serum level, and did not take into account the particular plant
or the job assignment within the plant. The Crump et al. (2003, 197384) approach did take into
account when exposure occurred in relation to the follow-up interval. The TCDD exposure
metric used was a cumulative serum lipid concentration (CSLC). For the Hamburg cohort,
Crump et al. (2003, 197384) used an average value from the exposure ranges provided in Flesch-
Janys et al. (1998, 197339). For the BASF cohort, arithmetic averages for the dose categories
were converted to TCDD CSLC intakes by dividing them by 0.25 (average body fat of 25%) and
a decay rate that corresponded to a half-life of 7 years.

The outcome variable for the dose-response modeling was all cancer mortality, and
CSLC was the independent variable. Crump et al. (2003, 197384) performed a series of trend
tests to determine the lowest dose for which a statistically significant trend in SMR could be
shown and all other lower doses. These tests also examined the highest dose in which there was
no statistically significant trend using data from this dose and all other lower doses. Estimates of
EDio, EDos, and ED0i for TEQ with respect to the lifetime probability of dying from cancer were
calculated. This calculation assumed a first-order elimination process with a half-life of
7.6 years, a 50% systemic uptake of ingested dioxin, that dioxin concentration in serum lipid is a
suitable measure for dioxin concentration in all lipid, and that all dioxin is sequestered in lipid
(which comprises 25% of body weight). Age-specific mortality rates in the presence of dioxin
exposure were then generated. Life-table methodology was used to calculate lifetime risks of
cancer mortality.

Based on the modeling results, the hypothesis of a baseline SMR of 1.0 was rejected, and
the linear model produced an SMR estimate of 1.17 (95% CI = 1.04-1.30) from these studies.
The dose-response curves for the three studies were not homogeneous. Namely, the points from
the BASF cohort fell below the predicted curve. Because the heterogeneity was not judged to be

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29

30

31

extreme by different statistical tests, however, the investigators used a common model in a
combined analysis of the data from the three studies. The linear model provided an adequate fit
of the data, and the slope associated with CSLC-ppt was 6.3 x io~6 (95% CI = 8.8 x io~7 to
1.3 x 10~5). Based on goodness of fit analysis, the preferred estimate of ED0i was 45 pg/kg-day,
which was six times higher than the estimate of 7.7 pg/kg-day derived by Steenland et al. (2001,
198589V

5.3.3.2. EPA 'v Decision Not to Conduct a Meta-analysis

From a statistical perspective, meta-analyses may not be very reliable when applied to a
small number of studies. Crump et al. (2003, 197384) used only three studies. Had EPA
undertaken a meta-analysis for the studies that met its criteria, most of the weight would come
from the two large studies on the NIOSH and Hamburg cohorts. However, such an analysis
relies on an assumption of a normally distributed between-study effect. This normality
assumption cannot be assessed with only three observations, yet the meta-analysis estimate is
highly sensitive to this distributional assumption (Higgins et al., 2009, 594339). Because of this
limitation and the imprecision of the between-study variance estimate, statisticians often
recommend forgoing meta-analysis in favor of discussing the individual studies when few
studies are available (Cox, 2006, 594342; Higgins et al., 2009, 594339). Based on these
considerations, EPA decided not to undertake a meta-analysis in this document.

As noted previously. Crump et al. (2003, 197384) has conducted a meta-analysis of the
three cohorts considered here, i.e., the NIOSH, Hamburg, and BASF cohorts. However, Crump
et al. modeled SMR data in which the cohorts were compared to the general population, rather
than on internal exposure-response analyses as relied upon in this document. Their analysis
included a total of 15 different SMRs from the three studies. A prior analysis of the dose-
responses by Becher et al. (1998, 197173) was used (i.e., the categorical SMR analysis by
Flesch-Janys et al. (1998, 197339)). Additionally, a prior analysis of the NIOSH cohort
(Steenland et al., 1999, 197437) in which SMRs were calculated was used. Crump et al. (2003,

	84) found that a linear dose-response gave a good fit to the data, and used that for deriving

an EDoi. However, they found that a supra-linear dose-response provided a better fit to the data,
but rejected the supra-linear model (a power model) because of an infinite slope at zero dose. In
the original publications by Becher et al. (1998, 197173) and Steenland et al. (2001, 198589).

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1	both observed a supra-linear dose-response trend. Crump et al. (2003, 197384) concluded that

2	the EDoi was 45 pg/kg-day, six times higher than the ED0i of 7.7 pg/kg-day calculated by

3	Steenland et al. (2001, 198589) using the same dietary units (pg/kg-day).

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Table 5-1. Cancer slope factors calculated from Becher et al. (1998,197173),
Steenland et al. (2001,197433) and Ott and Zober (1996,198408) from 2003
Reassessment Table 5-4

Study

EDoi (LEDoi)
(ng/kg)

Cancer slope factor per
ng/kg-day above
background3 (UCL)

Hamburg cohort
Power model

Becher et al. (1998. 197173)

6 (N.A.)

5.1 (N.A.)

Hamburg cohort

Additive model

Becher et al. (1998. 197173)

18.2 (N.A.)

1.6 (N.A.)

Hamburg cohort
Multiplicative model
Becher et al. (1998. 197173)

32.2 (N.A.)

0.89 (N.A.)

NIOSH cohort
Piecewise linear model
Steenland et al. (2001. 198589)

18.6 (11.5)

1.5 (2.5)

BASF cohort, from Ott and Zober
(1996. 198408). multiplicative

50.9 (25.0)

0.57 (1.2)

aAssumes 25% of body weight is lipid; in humans 80% of dioxin dose is absorbed from the normal
diet; the TCDD half-life is 7.1 years in humans. Background all cancer mortality rate calculated
through lifetable analysis to 75 years. Summary results are for male all cancer risk, because the
male lifetime (to 75 years) all cancer risk is greater than for females, leading to correspondingly
higher cancer slope factors. As detailed in Part III, Chapter 8, RelRisk(ED0i) = 0.99 +

0.01/Risk(0 dose)- Based on the manner in which the dose-response data were calculated using Cox
regression rate ratio analyses, risks are given as cancer slope factors for 1 pg/kg-day above
background, assumed 5 ppt TCDD in lipid.

UCL = upper confidence limit.

Source: U.S. EPA (U.S. EPA. 2003, 537122: Part III. Chapter 5. Table 5-4)

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1	Table 5-2. Cox regression coefficients and incremental cancer-mortality risk

2	for NIOSH cohort data

3

Model

Cox regression
coefficient estimate
(ppt-year)"1

Incremental risk3

Steenland et al.(2001. 197433) (untagged exposures)

Piecewise linear

1.5 x 10 5

7.0 x 10 4

Cheng et al. (Cheng et al.. 2006. 523122) (exposures lagged 15 vears)

Linear, lower 95% of observations

3.3 x 10 6b

1.2 x 10 4

Linear, full data

1.7 x I0~8c

6.3 x 10~7

4

5	aCompared to internal reference population (lowest exposure group),with a cancer mortality rate of 0.214; assumes

6	background exposure of 5 ppt per year serum-lipid TCDD concentration.

7	hp < 0.05.

8	cp< 0.05.

9	dNot statistically significant (p > 0.05).

10

11	Source: Cheng et al. (2006, 523122: Table IV).

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21

Table 5-3. Comparison of fat concentrations, risk specific dose estimates and
associated oral slope factors based on upper 95th percentile estimate of
regression coefficient3 of all fatal cancers reported by Cheng et al. (2006,
523122) for selected risk levels

Risk level
(RL)

AUCrl
(ppt-yr)

FATrL
(ng/kg)

Risk specific doseb
(Drl) (ng/kg-day)

Equivalent oral slope
factors (OSFrl) per
(mg/kg-day)

1 x 10~2

1.262 x 104

1.803 x 102

8.79 x 10~2

1.1 x 105

5 x 10~3

6.432 x 103

9.189 x 101

3.14 x 10~2

1.6 x 105

1 x 10~3

1.307 x 103

1.867 x 101

2.88 x 10~3

3.5 x 105

5 x 10~4

6.546 x 102

9.352 x 10°

9.56 x 10~4

5.2 x 105

1 x 10~4

1.311 x io2

1.873 x 10°

1.29 x 10~4

7.8 x 105

5 x 10~5

6.558 x 101

9.368 x 10"1

5.52 x 10~5

9.1 x io5

1 x 10~5

1.312 x 101

1.874 x 10_1

8.94 x 10~6

1.1 x io6

5 x 10~6

6.559 x 10°

9.370 x 10"2

4.25 x 10~6

1.2 x 106

1 x 10~6

1.312 x 10°

1.874 x 10~2

8.08 x 10~7

1.2 x 106

5 x 10~7

6.559 x 10"1

9.370 x 10"3

4.00 x 10~7

1.3 x 106

1 x 10~7

1.312 x 10_1

1.874 x 10~3

7.92 x 10~8

1.3 x 106

a Based on regression coefficient of Cheng et al. (2006, 523122. Table III), excluding observations in the upper 5%
range of the exposures; where reported (3 = 3.3 x 10 6 ppt-years and standard error = 1.4 x 10 6. Upper 95th
percentile estimate of regression coefficient (P95) calculated to be 6.04 x 10 6 = (3.3 x 10 6) + 1.96 x (1.4 x 10 6);
background cancer mortality risk is assumed to be 0.112 as reported by Cheng et al. (2006, 5231221.
bTo calculate the extra cancer risk (ER) and OSF for any TCDD daily oral intake (D):

5.	For D in ng/kg-d, look up the corresponding fat concentration (ng/kg = ppt) from the conversion chart
(nongestational lifetime dose metrics) in Appendix C.4.1.

6.	Calculate the AUC in ppt-yrs by multiplying the fat concentration by 70 years.

7.	Calculate Extra Risk (ER) using the following equation:

ER = [exp(AUC x 6.04E-6) x 0.112 - 0.112] - 0.888.

8.	Calculate the OSF (mg/kg-d)"1 = 1E6 x (ER D).

Example for risk at the RfD: D = 7 x 10"4 ng/kg-d; fat concentration = 6.93 ng/kg;

AUC = 70 years x 6.93 ppt = 485 ppt-year;

ER = exp(485 ppt-year x 6.04E-6 (ppt-yr)"1) x 0.112 - 0.112) - 0.888 = 3.7 x 10"4
OSF = 1E6 ng/mg x (3.7 x io~4 + 7 x io-4 ng/kg-d) = 5.3 x 105 (mg/kg-d)"1.

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1	Table 5-4. Comparison of fat concentrations, risk specific dose estimates and

2	associated central tendency slope estimates based on best estimate of

3	regression coefficient3 of all fatal cancers reported by Cheng et al. (2006,

4	523122) for selected risk levels

5

Risk level
(RL)

AUCrl,
(ppt-yr)

FATrL
(ng/kg)

Risk specific dose
(Drl) (ng/kg-day)

Central
tendency slope

estimates
(mg/kg-day)1

1 x 1(T2

2.312 x 104

3.303 x 102

2.21 x KT1

4.5 x 104

1 x l(T3

2.393x 103

3.419 x 101

6.97 x 10~3

1.4 x 105

1 x l(T4

2.402 x 102

3.431 x 10°

2.74 x 10~4

3.7 x 105

1 x l(T5

2.403 x 101

3.432 x 10_1

1. 74 x 10~5

5.7 x 105

1 x l(T6

2.403 x 10°

3.432 x 10~2

1.50 x 10~6

6.7 x 105

1 x l(T7

2.403 x 10_1

3.432 x 10~3

1.46 x 10~7

7.0 x 105

6

7	'Based on regression coefficient of Cheng et al (2006, 523122: Table III) excluding observations in the upper 5%

8	range (>252,950 ppt-year lipid adjusted serum TCDD) of the exposures; where reported (3 = 3.3 x 10 6 ppt-years;

9	background cancer mortality risk is assumed to be 0.112 as reported by Cheng et al. (2006, 5231221.

10

11

12	Table 5-5. Kociba et al. (1978, 001818) male rat tumor incidence data3 and

13	blood concentrations for dose-response modeling

14

Morphology: topography

Vehicle control
(ng/kg)

Low dose
(ng/kg)

Medium dose
(ng/kg)

High dose
(ng/kg)

0

1.56

7.16

38.72

Stratified squamous cell
carcinoma of hard palate or nasal
turbinates

0/85

0/50

0/50

4/5 0b

Stratified squamous cell
carcinoma of tongue

0/85

1/50

1/50

3/50b

Adenoma of adrenal cortex

0/85

0/50

2/50

5/5 0b

15

16	"Source: Kociba et al.(1978, 001818: Table 4).

17	Statistically significant by Fischer Exact Test (p < 0.05).

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1	Table 5-6. Kociba et al. (1978, 001818) female rat tumor incidence data3 and

2	blood concentrations for dose-response modeling

3

Morphology: topography

Vehicle control
(ng/kg)

Low dose
(ng/kg)

Medium dose
(ng/kg)

High dose
(ng/kg)

0

1.55

7.15

38.56

Hepatocellular adenoma(s) or
carcinoma(s)

2/86

1/50

9/5 0a

18/45b

Stratified squamous cell
carcinoma of hard palate or
nasal turbinates

0/86

0/50

1/50

4/49b

Keratinizing squamous cell
carcinoma of lung

0/86

0/50

0/50

7/49b

4

5	"Source: Kociba et al. (1978, 001818: Table 5). Incidence for Hepatocellular adenomas or carcinomas is from

6	Goodman and Sauer (Goodman and Sauer. 1992, 197667: Table 1); EPA calculated statistical significance as the

7	study authors did not provide this.

8	Statistically significant by Fischer Exact Test (p < 0.05).

9

10

11	Table 5-7. NTP (1982, 594255) female rat tumor incidence data" and blood

12	concentrations for dose-response modeling

13

Morphology: topography

Vehicle control
(ng/kg)

Low dose
(ng/kg)

Medium dose
(ng/kg)

High dose
(ng/kg)

0

1.96

5.69

29.75

Subcutaneous tissue: fibrosarcoma

0/75

2/50

3/50

4/49b

Liver: neoplastic nodule or
hepatocellular carcinoma

5/75c

1/49

3/50

14/49b

Adrenal: cortical adenoma, or
carcinoma or adenoma, NOS

1l/73c

9/49

5/49

14/46b

Thyroid: follicular-cell adenoma

3/73c

2/45

1/49

6/47

14

15	"Source: NTP (1982, 594255: Table 10).

16	Statistically significant by Fischer Exact Test (p < 0.05).

17	Statistically significant trend by Chochran-Armitage test (p < 0.05).

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1	Table 5-8. NTP (1982, 594255) male rat tumor incidence data3 and blood

2	concentrations for dose-response modeling

3

Morphology: topography

Vehicle control
(ng/kg)

Low dose
(ng/kg)

Medium dose
(ng/kg)

High dose
(ng/kg)

0

1.96

5.70

29.87

Liver: neoplastic nodule or
hepatocellular carcinoma

0/74b

0/50

0/50

3/50

Thyroid: follicular-cell adenoma or
carcinoma

l/69b

5/48c

8/5 0C

1 l/50c

Adrenal cortex: adenoma

6/72

9/50

12/49b

9/49

4

5	"Source: NTP(1982, 594255: Table 9).

6	Statistically significant trend by Chochran-Armitage test (p < 0.05).

7	Statistically significant by Fischer Exact Test (p < 0.05).

8

9

10	Table 5-9. NTP (1982, 594255) female mouse tumor incidence data3 and

11	blood concentrations for dose-response modeling

12

Morphology: topography

Vehicle control
(ng/kg)

Low dose
(ng/kg)

Medium dose
(ng/kg)

High dose
(ng/kg)

0

1.95

5.84

32.06

Subcutaneous tissue: fibrosarcoma

l/74b

1/50

1/48

5/47c

Hematopoietic system: lymphoma
or leukemia

18/74b

12/50

13/48

20/47c

Liver: hepatocellular adenoma or
carcinoma

3/73b

6/50

6/48

1 l/47c

Thyroid: follicular-cell adenoma

0/69b

3/50

1/47

5/46c

13

14	"Source: NTP (1982, 594255: Table 15).

15	Statistically significant trend by Chochran-Armitage test (p < 0.05).

16	Statistically significant by Fischer Exact Test (p < 0.05).

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1	Table 5-10. NTP (1982, 594255) male mouse tumor incidence data3 and

2	blood concentrations for dose-response modeling

3

Morphology: topography

Vehicle control
(ng/kg)

Low dose
(ng/kg)

Medium
dose (ng/kg)

High dose
(ng/kg)

0

0.77

2.27

11.24

Lung: alveolar/bronchiolar adenoma
or carcinoma

10/7 lb

2/48

4/48

13/50

Liver: hepatocellular adenoma or
carcinoma

15/73b

12/49

13/49

27/50c

4

5	"Source: NTP (1982, 594255: Table 14).

6	Statistically significant trend by Chochran-Armitage test (p < 0.05).

7	Statistically significant by Fischer Exact Test (p < 0.05).

8

9

10	Table 5-11. NTP (2006,197605) female rat tumor incidence data" and blood

11	concentrations for dose-response modelingb

12

System:

morphology:

topography

Vehicle
control
(ng/kg)

Low
dose
(ng/kg)

Low-med
dose (ng/kg)

Median

dose
(ng/kg)

Med-high
dose (ng/kg)

High dose
(ng/kg)

0

2.56

5.69

9.79

16.57

29.70

Liver:

cholangiocarcinoma

0/49c

0/48

0/46

1/50

4/49

25/53c

Liver:

hepatocellular
adenoma

0/49c

0/48

0/46

0/50

1/49

13/53c

Oral mucosa:
squamous cell
carcinoma

l/49c

2/48

1/46

0/50

4/49

10/5 3c

Pancreas: adenoma
or carcinoma

0/48c

0/48

0/46

0/50

0/48

3/51

Lung: cystic
keratinizing
epithelioma

0/49c

0/48

0/46

0/49

0/49

9/52c

13

14	'Source: NTP (2006. 197605: Table A3a).

15	incidence adjusted for animals <365 days on study.

16	Statistically significant by Poly-3 Test (p < 0.05).

17

18

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1	Table 5-12. Toth et al. (1979,197109) male mouse tumor incidence data3 and

2	blood concentrations for dose-response modeling

3

Morphology: topography

Vehicle control
(ng/kg)

Low dose
(ng/kg)

Medium dose
(ng/kg)

High dose
(ng/kg)

0

0.57

14.21

91.21

Liver tumors

7/38

13/44

21/44b

13/43

4

5	"Source: Toth et al. (1979, 197109: Table 1).

6	Statistically significant by Chi2 Test (p < 0.01).

7

8

9	Table 5-13. Delia Porta et al. (1987,197405) male mouse tumor incidence

10	data3 and blood concentrations for dose-response modeling

11

Morphology: topography

Vehicle control
(ng/kg)

Low dose
(ng/kg)

High dose
(ng/kg)

0

38.00

67.77

Hepatocellular carcinoma

5/43

15/5lb

33/50b

12

13	"Source: Delia Porta et al. (1987, 197405: Table 4).

14	Statistically significant by Chi2 Test (p < 0.05).

15

16

17	Table 5-14. Delia Porta et al. (1987,197405) female mouse tumor incidence

18	data3 and blood concentrations for dose-response modeling

19

Morphology: topography

Vehicle control
(ng/kg)

Low dose
(ng/kg)

High dose
(ng/kg)

0

37.59

66.97

Hepatocellular adenoma

2/49

4/42b

1l/48b

Hepatocellular carcinoma

1/49

12/42b

9/4 8b

20

21	"Source: Delia Porta et al. (1987, 197405: Table 4).

22	Statistically significant by Chi2 Test (p < 0.05).

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Table 5-15. Comparison of multi-stage modeling results across cancer bioassays using blood concentrations

Study

Species

Sex

Morphology: topography

Multi-stage modeling:3
stage, GoF />-valuc, LL difference

BMDoi
(ng/kg)

BMDLoi

(ng/kg)

Delia
Porta et
al.

(1987,
197405)

Mouse

Male

Hepatocellular carcinoma

2,/? = 0.52

7.14

1.17

Female

Hepatocellular adenoma

2,/? = 0.86

14.49

2.34

Hepatocellular carcinoma

\.p = 0.019

2.30

1.54

Kociba
et al.

(1978,

001818)

Rat

Male

Stratified squamous cell carcinoma of hard palate or nasal turbinates

\,p = 0.81

5.76

2.79

Stratified squamous cell carcinoma of tongue

\,p = 0.47

6.09

2.60

Adenoma of adrenal cortex

l,p= 0.78

3.25

1.85

Combined tumors Bayesian analysis



1.57

0.96

Female

Hepatocellular adenoma(s) or carcinoma(s)

l,p = 0.24

0.70

0.50

Stratified squamous cell carcinoma of hard palate or nasal turbinates

l,p = 0.97

4.51

2.34

Keratinizing squamous cell carcinoma of lung

l,p = 0.63

3.14

1.79

Combined tumors Bayesian analysis



0.51

0.37

NTP

(1982,

594255)

Rat

Female

Subcutaneous tissue: fibrosarcoma

\,p = 0.18

3.13

1.38

Liver: neoplastic nodule or hepatocellular carcinoma

\,p = 0.22

1.17

0.74



Adrenal: cortical adenoma, or carcinoma or adenoma, NOS

\,p = 0.34

1.61

0.81

Thyroid: follicular-cell adenoma

\,p = 0.57

3.38

1.55

Combined tumors Bayesian analysis



0.46

0.31

Male

Liver: neoplastic nodule or hepatocellular carcinoma

\,p = 0.85

6.14

2.70

Thyroid: follicular-cell adenoma or carcinoma

\,p = 0.06

1.21

0.70

Adrenal cortex: adenoma

\,p = 0.06

3.98

1.22

Combined tumors Bayesian analysis



0.74

0.44


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Table 5-15. Comparison of multi-stage modeling results across cancer bioassays using blood concentrations (continued)

Study

Specie
s

Sex

Morphology: topography

Multi-stage modeling:3
stage, GoF />-value, LL difference

BMDoi
(ng/kg)

BMDLoi

(ng/kg)

NTP

(1982,

594255)

Mouse

Female

Subcutaneous tissue: fibrosarcoma

l,p = 0.93

3.40

1.69

Hematopoietic system: lymphoma or leukemia

l,p = 0.98

1.14

0.61

cont.

Liver: hepatocellular adenoma or carcinoma

l,p = 0.34

1.49

0.83

Thyroid: follicular-cell adenoma

1 ,p = 0.09, no improvement with
higher orders

3.05

1.44

Combined tumors Bayesian analysis



0.44

0.29

Male

Lung: alveolar/bronchiolar adenoma or carcinoma

l,p = 0.09

2.53

0.41

Liver: hepatocellular adenoma or carcinoma

l,p = 0.93

0.21

0.14

Combined tumors Bayesian analysis



0.16

0.11

NTP

(2006,

197605)

Rat

Female

Liver: cholangiocarcinoma

3,p = 0.99, dLL = 2.93

7.57

4.13

Liver: hepatocellular adenoma

3,p = 0.93, dLL = 2.10

10.22

6.53



Oral mucosa: squamous cell carcinoma

l,p = 0.27

2.20

1.39

Pancreas: adenoma or carcinoma

l,p= 0.64

10.52

4.63

Lung: cystic keratinizing epithelioma

2,p = 0.51, dLL = 3.55

8.30

5.24

Combined tumors Bayesian analysis



1.18

0.78

Toth et
al.

(1979,
197109)

Mouse

Male

Liver: tumors

l,p = 0.29

0.37

0.21

*Analysis uses a chi-square goodness of fit statistic for differences in the log likelihoods (p > 0.05).


-------
1	Table 5-16. Individual tumor points of departure and slope factors using

2	blood concentrations

3

Study

Tumor Site (Sex/Species)

BMDLhed
(ng/kg-day)

OSF
(per mg/kg-day)

NTP (1982. 594255s)

Liver: adenoma or carcinoma (male mice)

1.7E-03

5.8E+6

Tot.het.al. (1979. 197109^

Liver tumors (male mice)

1.9E-03

5.2E+6

NTP. (1982. 594255V

Lung: adenoma or carcinoma (male mice)

8.7E-03

1.1E+6

Kocibaetal. (1978. 001818)

Liver: adenoma or carcinoma (female rats)

1.2E-02

8.6E+5

NTP (1982. 594255s)

Hematopoietic: lymphoma or leukemia (female
mice)

1.6E-02

6.4E+5

NTP (1982. 594255V

Thyroid: follicular cell adenoma (male rats)

1.9E-02

5.2E+5

NTP (1982. 594255s)

Liver: neoplastic nodule or hepatocellular
carcinoma (female rats)

2.1E-02

4.8E+5

NTP (1982. 594255s)

Adrenal: cortical adenoma or carcinoma or
adenoma, NOS (female rats)

2.4E-02

4.1E+5

NTP (1982. 594255s)

Liver: adenoma or carcinoma (female mice)

2.5E-02

4.0E+5

Delia Porta et al. (1987. 197405s)

Hepatocellular carcinoma (male mice)

3.1E-02

3.2E+5

NTP (1982. 594255V

Adrenal cortex: adenoma (male rats)

4.5E-02

2.2E+5

Delia Porta et al. (1987,
197405V

Hepatocellular carcinoma (female mice)

4.9E-02

2.0E+5

NTP (1982. 594255s)

Subcutaneous fibrosarcoma (female rats)

5.4E-02

1.8E+5

NTP (2006. 197605s)

Oral mucosa: squamous cell carcinoma (female
rats)

5.5E-02

1.8E+5

NTP (1982. 594255V

Thyroid: adenoma (female mice)

5.7E-02

1.7E+5

NTP (1982. 594255s)

Thyroid: follicular cell adenoma (female rats)

6.5E-02

1.5E+5

NTP (1982. 594255s)

Subcutaneous fibrosarcoma (female mice)

7.4E-02

1.4E+5

Kociba et al. (1978. 001818s)

Lung: carcinoma (female rats)

8.0E-02

1.2E+5

Kociba et al. (1978. 001818s)

Adenoma of adrenal cortex (male rats)

8.5E-02

1.2E+5

Delia Porta et al. (1987. 197405s)

Hepatocellular adenoma (female mice)

9.4E-02

1.1E+5

Kociba et al. (1978. 001818s)

Nasal/Palate: carcinoma (female rats)

1.2E-01

8.2E+4

Kociba et al. (1978. 001818s)

Tongue: carcinoma (male rats)

1.4E-01

7.0E+4

NTP (1982. 594255s)

Liver: neoplastic nodule or hepatocellular
carcinoma (male rats)

1.5E-01

6.6E+4

Kociba et al. (1978. 001818s)

Nasal/Palate: carcinoma (male rats)

1.6E-01

6.3E+4

NTP C2006. 197605s)

Liver: cholangiocarcinoma (female rats)

2.9E-01

3.5E+4

NTP (2006. 197605s)

Pancreas: adenoma or carcinoma (female rats)

3.4E-01

2.9E+4

NTP (2006. 197605s)

Lung: cystic keratinzing epithelioma (female rats)

4.1E-01

2.4E+4

NTP (2006. 197605s)

Liver: hepatocellular adenoma (female rats)

5.6E-01

1.8E+4

This document is a draft for review purposes only and does not constitute Agency policy.

5-104 DRAFT—DO NOT CITE OR QUOTE


-------
1

2	Table 5-17. Multiple tumor points of departure and slope factors using blood

3	concentrations

4

Study

Sex/species: tumor sites

BMDLhed
(ng/kg-day)

OSF
(per mg/kg-day)

NTP (1982. 594255s)

Male mice: liver adenoma and carcinoma, lung

1.1E-03

9.4E+6

NTP (1982. 594255s)

Female mice: liver adenoma and carcinoma, thyroid
adenoma, subcutaneous fibrosarcoma, all lymphomas

5.3E-03

1.9E+6

NTP (1982. 594255s)

Female rats: liver neoplasitc nodules, liver adenoma
and carcinoma, thyroid follicular cell adenoma,adrenal
cortex adenoma or carcinoma

5.7E-03

1.8E+6

Kociba et al. (1978,

001818s)

Female rats: liver adenoma carcinoma, oral cavity,
lung

7.3E-03

1.4E+6

NTP (1982. 594255s)

Male rats: thyroid follicular cell adenoma, adrenal
cortex adenoma

9.6E-03

1.0E+6

NTP (2006. 197605s)

Female rats: liver cholangiocarcinoma, hepatocellular
adenoma, oral mucosa squamous cell carcinoma, lung
cystic keratinizing epithelioma, pancreas adenoma,
carcinoma

2.3E-02

4.4E+5

Kociba et al. (1978,

001818s)

Male rats: adrenal cortex adenoma, tongue carcinoma,
nasal/palate carcinoma

3.1E-02

3.2E+5

5

This document is a draft for review purposes only and does not constitute Agency policy.

5-105 DRAFT—DO NOT CITE OR QUOTE


-------
Table 5-18. Comparison of cancer BMDs, BMDLs, and slope factors for combined or selected individual tumors
for 1, 5, and 10% extra risk

Study

Species

Sex

BMDoi
(ng/kg)

BMDLoi
(ng/kg)

SF01
(ng/kg) 1

bmd05

(ng/kg)

bmdl05

(ng/kg)

sf05

(ng/kg) 1

BMD10
(ng/kg)

BMDL10
(ng/kg)

SF10
(ng/kg) 1

Kociba

(1978,

001818V

Rat

Female

4.9E-01

3.8E-01

2.7E-02

2.5E+00

1.9E+00

2.7E-02

4.9E+00

3.8E+00

2.7E-02

Male

1.5E+00

9.6E-01

1.0E-02

7.2E+00

4.8E+00

1.0E-02

1.5E+01

9.6E+00

1.0E-02

NTP

(1982,

594255V

Rat

Female

4.4E-01

3.2E-01

3.2E-02

2.2E+00

1.6E+00

3.2E-02

4.4E+00

3.2E+00

3.2E-02

Male

6.9E-01

4.5E-01

2.2E-02

3.5E+00

2.2E+00

2.2E-02

6.9E+00

4.5E+00

2.2E-02



Mouse

Female

4.3E-01

3.0E-01

3.4E-02

2.1E+00

1.5E+00

3.4E-02

4.3E+00

3.0E+00

3.4E-02

Male

1.5E-01

1.1E-01

9.4E-02

7.7E-01

5.4E-01

9.4E-02

1.5E+00

1.1E+00

9.4E-02

NTP

(2006,

197605V

Rat

Female

1.1E+00

7.8E-01

1.3E-02

4.8E+00

3.6E+00

1.4E-02

8.2E+00

6.6E+00

1.5E-02

Delia Porta
et al.

(1987,

197405V

Mouse

Male

7.1E+00

1.2E+00

8.5E-03

1.4E+01

5.0E+00

1.0E-02

2.0E+01

9.7E+00

1.0E-02

Female

2.3E+00

1.5E+00

6.5E-03

1.0E+01

6.8E+00

7.3E-03

2.1E+01

1.4E+01

7.1E-03

Toth et al.,
(1979

197109V

Mouse

Male

3.7E-01

2.1E-01

4.8E-02

1.9E+00

1.1E+00

4.7E-02

3.9E+00

2.2E+00

4.6E-02

aCombined tumors, Bayesian analysis.
bHepatocellular carcinomas for both males and females,
hepatocellular carcinomas.

TCDD blood concentrations from Emond rodent PBPK models.
SF = BMR BMDLbmr, where BMR = 0.01, 0.05, or 0.10.


-------
Table 5-19. TCDD human-equivalent dose (HED) BMDs, BMDLs, and oral slope factors (OSF) for 1, 5, and 10%
extra risk

Study

Species

Sex

BMDoi
(ng/kg-d)

BMDLoi
(ng/kg-d)

OSF01
(ng/kg-d) 1

bmd05

(ng/kg-d)

bmdl05

(ng/kg-d)

osf05

(ng/kg-d) 1

BMD10
(ng/kg-d)

BMDL10
(ng/kg-d)

OSF10
(ng/kg-d) 1

Kociba

(1978,

001818V

Rat

Female

1.1E-02

7.4E-03

1.4E+00

1.3E-01

8.6E-02

5.8E-01

3.8E-01

2.59E-01

4.0E-01

Male

5.9E-02

3.1E-02

3.3E-01

6.6E-01

3.6E-01

1.4E-01

1.8E+00

9.7E-01

1.0E-01

NTP

(1982,

594255V

Rat

Female

9.7E-03

5.8E-03

1.7E+00

1.1E-01

6.6E-02

7.6E-01

3.2E-01

1.9E-01

5.2E-01

Male

1.9E-02

9.7E-03

1.0E+00

2.2E-01

1.1E-01

4.5E-01

6.2E-01

3.3E-01

3.1E-01



Mouse

Female

9.1E-03

5.4E-03

1.9E+00

1.1E-01

6.0E-02

8.3E-01

3.0E-01

1.8E-01

5.7E-01

Male

1.9E-03

1.2E-03

8.3E+00

2.2E-02

1.3E-02

3.8E+00

6.4E-02

3.8E-02

2.7E+00

NTP

(2006,

197605V

Rat

Female

4.1E-02

2.3E-02

4.4E-01

3.6E-01

2.4E-01

2.1E-01

7.9E-01

5.7E-01

1.8E-01

Delia Porta
et al.

(1987,

197405V

Mouse

Male

5.2E-01

3.1E-02

3.2E-01

1.7E+00

3.8E-01

1.3E-01

2.8E+00

1.0E+00

1.0E-01

Female

9.2E-02

4.9E-02

2.0E-01

1.1 E+00

6.0E-01

8.3E-02

2.9E+00

1.7E+00

5.9E-02

Toth et al.
(1979,

197109V

Mouse

Male

5.1E-03

1.9E-03

5.3 E+00

6.7E-02

2.7E-02

1.9E+00

2.0E-01

8.5E-02

1.2 E+00

2! ^

H S.
W K-

oy

o

c
o

H
W

aCombined tumors, Bayesian analysis.
bHepatocellular carcinomas for both males and females,
hepatocellular carcinomas.

HEDs from Emond human PBPK model corresponding to blood concentration BMDs and BMDLs in Table F3-1.
OSF = BMR BMDLbmr, where BMR = 0.01, 0.05, or 0.10.


-------
Table 5-20. Illustrative RfDs based on tumorigenesis in experimental animals

Study

Species, strain
(sex)

Protocol

Endpoint

BMDLhed3
(ng/kg-day)

RID1'

(mg/kg-day)

NTP (1982,
594255s)

Mouse, B6C3F1,
male

2-year gavage;
n = 50

Liver adenoma and carcinoma, lung

1.1E-3

3.6E-11

Toth et al.
(1979. 197109s)

Mouse, Swiss/
H/Riop, male

1-year gavage
(1-year average);
n = 38-44

Liver tumors

1.9E-3

6.3E-11

NTP (1982,
594255s)

Mouse, B6C3F1,
female

2-year gavage;
n = 50

Liver adenoma and carcinoma, thyroid adenoma,
subcutaneous fibrosarcoma, all lymphomas

5.3E-3

1.7E-10

NTP (1982,

594255s)

Rat, Osborne-
Mendel, female

2-year gavage;
n = 50

Liver neoplasitc nodules, thyroid follicular cell adenoma,
liver adenoma and carcinoma, adrenal cortex adenoma or
carcinoma

5.7E-3

1.9E-10

Kociba et al.
(1978. 001818s)

Rat, S-D, female

2-year dietary;
n = 50

Liver adenoma carcinoma, oral cavity, lung

7.3E-3

2.4E-10

NTP (1982,
594255s)

Rat, Osborne-
Mendel, male

2-year gavage;
n = 50

Thyroid follicular cell adenoma, adrenal cortex adenoma

9.6E-3

3.2E-10

Delia Porta et al.
(1987. 197405s)

Mouse, B6C3F1,
male

1-year gavage;
n = 40-50

Hepatocellular carcinoma

3.1E-02

1.0E-9

NTP (2006,

197605s)

Rat, S-D, female

2-year gavage;
n = 53

Liver cholangiocarcinoma, hepatocellular adenoma, oral
mucosa squamous cell carcinoma, lung cystic keratinizing
epithelioma, pancreas adenoma, carcinoma

3.1E-2

1.0E-9

Kociba et al.
(1978. 001818s)

Rat, S-D, male

2-year dietary;
n = 50

Adrenal cortex adenoma, tongue carcinoma, nasal/palate
carcinoma

3.1E-2

1.0E-9

H J

H S.
W K-

oy

o

c
o

H
W

aBMR = 0.01.

bUF = 30; UFa = 3, UF„ = 10.


-------
Table 5-21. Illustrative RfDs based on hypothesized key events in TCDD's MOAs for liver and lung tumors

Key event

Endpoint and exposure duration

NO(A)ELhed
(ng/kg-day)

LO(A)ELhed
(ng/kg-day)

BMDLhed3
(ng/kg-day)

RID1'

(mg/kg-day)

Study

Liver tumors

Changes in gene expression

CYP1A1 mRNA,
1 day

1.8E-05

3.4E-04

2.3E-030
(Appendix H)

6E-13d'e

Vanden Heuvel et al.
(1994.594318)

Changes in gene expression

Benzo(a)pyrene hydroxylase (BPH)
activity (CYP1A1), 1 day

9.2E-04

6.0E-03

4.6E-04cd

(Appendix H)

2E-llde

Kitchin and Woods
(1979. 198750)

EROD (CYP1A1), 53 weeks

none

1.4E-01

9.5E-03C

(Appendix H)

3E-10e

NTP (2006. 197605)

Oxidative stress

DNA single-strand breaks,
90 days

none

3.3E-02

2.2E-02C

(Appendix H)

7E-10e

Hassoun et al. (2000,

197431)

TBARS, 90 days

—

—

4.4E-02

(Appendix H)

2E-09e

Hassoun et al. (2000,

197431)

Cytochrome C reductase, 90 days

—

—

8.8E-02

(Appendix H)

3E-09e

Hassoun et al. (2000,

197431)

Hepatotoxicity

Toxic hepatopathy,
2 years

none

1.4E-01

1.8E-010
(Appendix E)

5E-09f

NTP (2006. 197605)

Hepatocyte hypertrophy, 31 weeks

9.3E-02

3.3E-01

8.8E-03

(Appendix E)

3E-10e

NTP (2006. 197605)

Hepatocellular proliferation

Labeling index,
31 weeks

none

1.4E-01

6.6E-020

(Appendix H)

2E-09e

NTP (2006. 197605)

Lung tumors

Metabolic enzyme induction

EROD (CYP1A1), 53 weeks

none

1.4E-01

2.9E-040

(Appendix H)

1E-Ile

NTP (2006. 197605)

Retinoid homeostatsis

Hepatic retinol and retinyl
palmitate, 90 days

none

1.1E+00

1.7E-010

(Appendix E)

6E-09e

Van Birgelen et al.
(1995. 198052)

aBMR for continuous endpoints—1 standard deviation; for quantal endpoints—10%.

bBolded NOAEL, LOAEL, or BMDL is selected POD; poorly-fitting BMDLs above the LOAEL not used.

°Poor BMD model fit or no good model fit.

dCouldbe higher depending on the effect of background exposureoor (see Section 5.3.2.1).

eUF = 30; UFa = 3; UFH = 10.

fUF = 300; UFA = 3; UFH = 10; UFL = 10.


-------
1	Table 5-22. Comparison of principal epidemiological studies

2

Strengths

Weaknesses

Study

Cumulative TCDD levels in the serum were
estimated on an individual-level basis for
the 3,538 workers.

Evaluated effect of lag periods (0 and 15
years).

Measured and back-extrapolated TCDD
concentrations to refine and quantify job
exposure matrices, which were then used to
estimate dioxin cumulative dose for each
member of their entire cohort.

Internal cohort comparisons (Cox regression
model).

Background exposure estimated.

•	Exposure to other chlorinated hydrocarbons
(dioxin like compounds).

•	Extrapolation of dose from a small subset
(roughly 5%, n = 170) of the cohort.

•	Serum fat or body fat levels of TCDD were
back-calculated using a simple first-order
model. Half-life of TCDD is variable but
simulated as a constant. Changes in the lipid
fraction of body weight or presence/absence
of genetic differences in humans that alter the
distribution and metabolism of TCDD were
not considered.

•	Serum lipid levels of TCDD in 1988 were
measured only at one of the eight plants in
the study. No follow-up measures. The
estimates of dose are based on blood samples
taken decades after exposure.

NIOSH cohort
Steenland et al.
(2001. 197433)

Cumulative TCDD levels in the serum were
estimated on an individual-level basis for
the 3,538 workers.

TCCD dose estimates were simulated with a
kinetic model that included considerations
of exposure intensity and age-dependent
body weight and fat levels.

Evaluated effect of lag periods (0 and 15
years).

Background exposure estimated.

Stratified risk estimates for smoking and
nonsmoking.

Race and age adjustments.

Internal cohort noted an inverse-dose
response for high-exposure groups and thus
excluded the data resulting in stronger
associations.

•	Extrapolation of dose from a small subset
(roughly 5%, n = 170) of the cohort.

•	The authors reported the CADM model
provided an improved fit over the one-
compartmental model, but no evidence was
reported regarding any formal test of
statistical significance.

•	Serum lipid levels of TCDD in 1988 were
measured only at one of the eight plants in
the study. No follow-up measures. The
estimates of dose are based on blood samples
taken decades after exposure.

•	Exposure to other chlorinated hydrocarbons
(dioxin like compounds).

•	No consideration for recent exposures to
TCDD, changes in the lipid fraction of body
weight or presence/absence of genetic
differences in humans that alter the
distribution and metabolism of TCDD could
cause misclassification.

NIOSH cohort
Cheng et al.
(2006. 523122)

This document is a draft for review purposes only and does not constitute Agency policy.

5-110 DRAFT—DO NOT CITE OR QUOTE


-------
1

Table 5-22 Comparison of principal epidemiological studies (continued)

Strengths

Weaknesses

Study

•	Repeated TCDD measures in serum in 48
individuals. Used to estimate half-life for
study cohort. Took into account the age
and body fat percentage of the workers.
Measured and back-extrapolated TCDD
concentrations to quantify exposures for the
remaining cohort members using 5 different
working areas of the plant

•	Evaluated effect of lag periods up to 20
years.

•	Multiple statistical models used to evaluate
fatal cancer slope estimates.

•	Background exposure estimated.

•	Exposure to other chlorinated hydrocarbons
(dioxin like compounds), HCH, and lindane.

•	Extrapolation of dose from a small subset
(roughly 4%, n = 1,189) of the cohort.

•	Serum fat or body fat levels of TCDD were
back-calculated using a simple first-order
model. Presence/absence of genetic
differences in humans that alter the
distribution and metabolism of TCDD were
not considered.

•	Serum lipid levels of TCDD for only 275
workers.

Becher et al.
(1998. 197173);
Hamburg
Cohort

•	Both internal and external analyses.

•	Adjustment for age, BMI, and smoking.

•	Both cancer incidence and cancer mortality
data available, although results somewhat
discordant, with steeper dose-response seen
for cancer mortality.

•	Acute dose due to accident may not be
comparable to chronic dose accumulated over
a long time, as in most environmental
exposures.

•	Relatively small number of cancer deaths
compared to NIOSH and Hamburg cohorts
(n = 31).

•	Serum TCDD levels measured 30 years after
accident, requiring extrapolation back in time
to estimate cumulative dose over time.

•	Serum TCDD levels measured only on a
sample of the cohort (138 out of 243),
requiring assumptions about similarities in
exposure scenario for other workers to
estimate their exposure

Ott and Zober
(1996. 198408)

This document is a draft for review purposes only and does not constitute Agency policy.

5-111 DRAFT—DO NOT CITE OR QUOTE


-------
Table 5-22 Comparison of principal epidemiological studies (continued)

Strengths

Weaknesses

Study

•	TCDD levels measured in all 891 members
of this female cohort.

•	Most TCDD measurements based on
observed levels in stored serum at the time
of the accident in 1976, no extrapolation
needed to estimate past levels.

•	Internal analyses.

•	Evaluates female cancer incidence, other
studies evaluate male cancer mortality.

•	Presumed adjustment for age and potential
breast cancer confounders (15 of 21 cancers
were breast cancer).

•	Acute dose due to accident may not be
comparable to chronic dose accumulated over
a long time, which is typical of most
environmental exposures.

•	Did not evaluate different lag periods.

•	Not clear if any adjustment for confounders.

•	Small number of cancers (n = 21).

•	Doses known in 1976, require assumptions
about excretion over time to estimate
cumulative dose (9 year half life assumed),
presumed metric of primary interest. No
more recent TCDD concentration data used.

•	Reported logio transformation of the exposure
estimates in their regression analysis.

Warner et al.
(2002. 197489)

1

2

3	Table 5-23. Added background TEQ exposures to blood TCDD/TEQ

4	concentrations in ratsa

5

Background TEQ added

None

Est. TCDD onlyb

Est. TEQC

2x Est. TEQd

10x Est. TCDDe

0

0.064

0.19

0.38

0.64

2.56

2.62

2.75

2.94

3.20

5.69

5.75

5.88

6.07

6.33

9.79

9.85

9.98

10.1

10.5

16.6

16.7

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17.2

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29.8

29.9

30.1

30.3

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7	"Background exposures estimated from NTP (2006, 543749); rat TCDD concentrations from NTP (2006, 197605)').

8	' Estimated from TCDD fat concentration measurements in NTP (2006, 543749).

9	"Estimated from combined TCDD. PeCDF. and PCB-126 fat concentration measurements in NTP (2006, 543749).

10	dAssumes that measured congeners comprise 50% of actual TEQ exposure.

11	"Assumes that TCDD comprises 10% of total background TEQ exposure.

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1	Table 5-24. Effect of added background TEQ exposure on BMDL0i for

2	cholangiocarcinomas in rats (NTP, 2006,197605)

3

Background TEQa

Added exposure
(ng/kg blood TEQ)

BMDL0ib
(ng kg blood)

Nonec

0

4.14

Est. TCDD only

0.064

4.19

Est. TEQ

0.19

4.30

2x Est. TEQ

0.38

4.45

10x Est. TCDD

0.64

4.65

4

5	Scenarios as in Table 5-20.

6	'Multistage model results from BMDS version 2.1.1 (see Appendix I for modeling details).

7	°Same result as for the single tumor modeling presented previously in this section.

8

9

10	Table 5-25. NIOSH cohort septile data with added TEQ background3

11

Septile

TCDD serum level

(ppt-yr)

TCDD + background TEQ
(ppt-yr)

Relative increase
(%)

1

260

2,960

1,040

2

402

3,102

770

3

853

3,553

320

4

1,895

4,595

140

5

4,420

7,120

60

6

12,125

14,825

20

7

59,838

62,538

5

12

13	'Septile data from Steenland et al. (2001, 1974331: cumulative background TEQ estimate from Crump et al.

14	(2003, 1973841: both based on estimates by WHO (1998).

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Cell-type specific
factors (kinases,
cofactors etc.)

TCDD



AHR

Post-translational
modification

Binding to other
transcription factors
(Rb, ERa)

Altered
Cell Cycle
Regulation

Altered
Metabolism

Figure 5-1. Mechanism of altered gene expression by AhR. The regulation of
gene expression by TCDD in mammalian cells requires binding of the xenobiotic
to the aryl hydrocarbon receptor (AhR). The AhR is part of a multi-protein
complex that includes heat shock proteins and various kinases and other post-
translational modifying factors. Upon ligand binding, the AhR heterodimerizes
with the aryl hydrocarbon receptor nuclear translocator (Arnt) and binds to dioxin
response elements (DREs) found in target genes. Alternatives to DRE-dependent
gene expression exist whereby the AhR complex associates with other
transcription factors and results in a cross-talk between these systems. The
culmination of regulation of AhR targets genes (both increases ad decreases in
transcription) results in an alteration in cellular phenotypes, including changes in
intracellular metabolism and changes in cell cycle regulation.

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Liver

Lung

Thyroid

TCDD

I

AhR

TCDD

J

AhR

I

I

Co-carcinogens

Changes in
Gene Expression

M

Oxidative
Stress

Hepatotoxicity 		

Cellular
Proliferation

~

Adenoma

and
Carcinoma

Changes in
Gene£flflgg>ion

Metabolic

Retinoid	Enzymes

Homeostasis	(Cyps, COX2)

¦		 Toxicity 	

'*• Proliferation

~

Adenoma

and
Carcinoma

Liver

Decreased T4

i

Increased-fTSH

	|	>

Proliferation

Thyroid

Adenoma

and
Carcinoma

Figure 5-2. TCDD's hypothesized modes of action in site-specific carcinogenesis. See text for details. In each
instance, the solid arrows depict pathways that are well-established and are associated with low uncertainty. The
dashed arrows represent connections that are less established and are associated with higher uncertainty.


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Figure 5-3. EPA's process to select and identify candidate OSFs from key
animal bioassays for use in the cancer risk assessment of TCDD.

For each cancer study that qualified for TCDD dose-response assessment using the study inclusion criteria,
EPA first selected the species/sex/tumor combinations with statistically significant increases in tumor
incidence by either a pair-wise test between the treated group and the controls or by a trend test showing
increases in tumors with increases in dose. Next, EPA used an animal kinetic model to estimate blood
concentrations corresponding to the study average daily administered doses for use in dose response
modeling. BMDL0i's were then estimated for the blood concentrations by, (1) using the linearized
multistage model for each species/sex/tumor combination within each study, and (2) using the linearized
multistage model within a Bayesian Markov Chain Monte Carlo framework that assumes independence of
tumors and modeling all tumors together for each species/sex combination within each study. Using the
human kinetic model, human equivalent doses (BMDLheDs) were then estimated for each of the BMDL„iS
and oral slope factors were calculated by OSF = 0.01/BMDLhed- The lowest OSF for a species/sex
combination for either a single tumor type or all tumors combined was selected as a candidate OSF for
TCDD risk assessment.

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Supralinear(Weibull): Pr(d)=l-exp(-dA0.7)

0.2	0.4	0.6	0.8	1

Dose

Dose

Probit model: Sublinear, NOT ZS@S:



0.16



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Dose

1

2

3	Figure 5-4. Dose-response model shape

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Individuals with supralinear above threshold, and population DR curve

1

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0.04

tu

H

s

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a

to

u 0.03

£ 002
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0.1

u
n

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0.08

0.06

^ 0.04

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0.02

Dose

Figure 5-5. Comparison of individual and population dose-response curves;
a simple illustration.

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A. Full response range

Multistage Cancer Model with 0.95 Confidence Level

dose

09:48 04/22 2010

B. Low-dose region

Cholangiosarcoma low dose

Blood Cone (ng/kg)

Figure 5-6. Multistage benchmark dose modeling of NTP (2006, 197605)
cholangiosarcoma data.

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A. Full response range

Composite Risk of Dioxin in NTP (2006a) female rats

EXPERIMENTAL DOSE RANGE

B. Low-dose region

Composite Risk of Dioxin in NTP (2006a) female rats around BMD01

DOSE

Figure 5-7. Multistage benchmark dose modeling of NTP (2006, 197605)
combined tumor data.

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A.

Kohn and Melnick (2002) Figure 5 on log Scale (KR.X=3300)

B.

Kohn and Melnick (2002) Figure 5 on Arithmetic Scale (KR.X=3300)

i	r

20	30

Concentration X in nM

5.0	10.0

log 10 Concentration X in nM

Figure 5-8. Estrogen receptor-mediated response-modeling plot from Kohn
and Melnick (2002,199104): low-dose region shown.

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Liver

TCDD

1

AhR

I

Changes in

gene ex

oression

Oxidative
stress

Hepatotoxicity***'

^•....^Hepatocellular
proliferation

CYP1A1 mRNA, 1 day
Vanden Heuvel etal., 1994

EROD (CYP1A1), 53 weeks
NTP, 2006

TBARS, 90 days
Hassoun et al., 2000

Toxic hepatopathy, 2 years
NTP, 2006

Labeling index, 31 weeks
NTP, 2006

Adenoma

and
carcinoma

Figure 5-9. Representative endpoints for each of the hypothesized key events
following AhR activation for TCDD-induced liver tumors.

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Lung

1

2

3

4

5

Hepatic retinol, 90 days
Van Birgelen et al., 1995a

TCDD

I

AhR

Cocarcinogens

Changes in

gene ex

— Retinoid
homeostatsis

pression

Metabolic

enzymes
(Cyps, COX2)

•~Tox

city*	

EROD (CYP1A1), 53 weeks
NTP, 2006

'^Proliferation

Adenoma

and
carcinoma

Figure 5-10. Representative endpoints for two hypothesized key events
following AhR activation for TCDD-induced lung tumors.

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Cancer Slope Factors for 2,3,7,8-TCDD

to

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Figure 5-11. Candidate oral slope factor array.


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6. FEASIBILITY OF QUANTITATIVE UNCERTAINTY ANALYSIS
FROM NAS EVALUATION OF THE 2003 REASSESSMENT

6.1. INTRODUCTION

This section focuses on the third area for improvement in the 2003 Reassessment that was
identified by the National Academy of Sciences (NAS) review committee (NAS, 2006, 198441),
i.e., improving transparency, thoroughness, and clarity in quantitative uncertainty analysis.
Although the NAS committee summarized the shortfalls in the 2003 Reassessment categorically,
the elaborations within their report often contain the qualification "if possible" and do not take a
position with regard to the feasibility of many of its suggestions. With appreciation for the
extent of information available for dioxin, the goal of this section is to circumscribe the
feasibility of a data-driven quantitative uncertainty analysis for TCDD dose-response
assessment. Following brief highlights of the evolution of quantitative uncertainty analysis for
such applications, this section lays out definitions of key terms, reviews EPA's position
regarding cancer and noncancer endpoints, summarizes the NAS critique, and evaluates the
feasibility of quantitative uncertainty analysis for TCDD within the framework of EPA's
noncancer RfD and cancer slope factor dose-response methodologies.

6.1.1. Historical Context for Quantitative Uncertainty Analysis

The basic methods of probabilistic risk assessment (PRA) were developed in the
aerospace program in the 1960s, and they found their first full-scale application in the
U.S. Nuclear Regulatory Commission's (U.S. NRC's) Reactor Safety Study of1975—including
accident consequence analysis and uncertainty analysis (U.S. NRC, 1975, 543729). This study,
commonly referred to as the Rasmussen Report after its lead author, is considered to be the first
modern PRA. In the aftermath of the 1979 Three Mile Island accident, a new generation of
PRAs appeared in which some of the methodological problems of the 1975 study were avoided.
These advances were reflected in the Commission's Fault Tree Handbook (U.S. NRC, 1981,
543730) and PRA guide (U.S. NRC, 1983, 543732), which shored up and standardized much of
the risk assessment methodology. An extensive chapter of the latter was devoted to uncertainty
and sensitivity analysis. These documents formed the basis for standards and guidelines

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established by other agencies, including the U.S. Department of Energy (U.S. DOE, 1992,
543733) and National Aeronautics and Space Administration (NASA, 2002, 543734).

In 1991, a set of U.S. NRC studies known as NUREG 1150 used structured expert
judgment to quantify uncertainty and set new standards for uncertainty analysis, in particular
with regard to expert elicitation (U.S. NRC, 1991, 543736). This was followed by a joint
U.S.-European Union (EU) program for quantifying uncertainty in accident consequence models.
Expert judgment methods were further elaborated in those evaluations, as well as screening,
dependence modeling and sensitivity analysis (EC, 2009, 543738). Studies building off of this
work have performed a large-scale uncertainty analysis of European consequence models and
provided extensive guidance on identifying important variables; selecting, interviewing and
combining experts; propagating uncertainty; inferring distributions on model parameters; and
communicating results, as documented by Goossens et al. (1996, 548727; 1997, 543752; 1998,
548726; 2001, 548730; 2001, 548731; 2001, 548732; 2001, 548735; 2001, 548737; 2001,
548738; 2001, 548734) and others (Brown et al., 1997, 543739; Harper et al., 1995, 202317;
2002, 198124).

The National Research Council (NRC) has been a persistent voice in urging the
government to enhance its risk assessment methodology beginning with its report on risk
assessment in the federal government (NRC, 1983, 194806). The Council"s 1989 report.
Improving Risk Communication, inveighed against minimizing the existence of uncertainty and
noted the importance of considering the distribution of exposure and sensitivities in a population
(NRC, 1989, 000858). The issue of uncertainty was a clear concern in subsequent reports,
including those assessing human exposure to airborne pollutants (NRC, 1991, 037823). Building
on its evaluation of Issues in Risk Assessment (NRC, 1993, 078637). the landmark study Science
and Judgment in Risk Assessment (NRC, 1994, 006424) gathered many of these themes in a plea
for quantitative uncertainty analysis as "the only way to combat the false sense of certainty
which is caused by a refusal to acknowledge and (attempt to) quantify the uncertainty in risk
predictions." A subsequent report, Estimating the Public Health Benefits of Proposed Air
Pollution Regulations (NRC, 2002, 035312). identified three barriers to the broad acceptance of
recent EPA health benefit analyses: (1) the large amount of uncertainty inherent in these
analyses, (2) the manner in which EPA deals with this uncertainty, and (3) "... projected health
benefits are often reported as absolute numbers of avoided death or adverse health outcomes

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without a context of population size or total numbers of outcomes." The Council encouraged
EPA to "explore alternative options for incorporating expert judgment into its probabilistic
uncertainty analyses."

In an early 2009 report, Science and Decisions: Advancing Risk Assessment, the NRC
committee on improving risk analysis encouraged EPA to harmonize approaches for cancer and
noncancer dose-response assessment (NRC, 2009, 194810). which involves uncertainty issues
discussed in this section. Even more recently, EPA released a draft white paper, Using
Probabilistic Methods to Enhance the Role of Risk Analysis in Decision Making (U. S. EPA,
2009, 522927). Although not focused specifically on quantitative uncertainty analysis, there is
overlap with the issues treated here, and relevant insights are anticipated from ongoing efforts in
this area.

6.1.2. Definition of Terms

For purposes of this study, the following definitions are adopted:52

Uncertainty Characterization. This consists of a Structured Uncertainty Narrative and, if
the uncertainty is supported by quantitative models, Quantitative Uncertainty Analysis.

Structured Uncertainty Narrative. This identifies the assumptions conditional on which
uncertainty is to be characterized and delineates the type of arguments with supporting
evidence that buttress these assumptions.

Quantitative Uncertainty Analysis. This is a quantification of the uncertainty attending
the use of quantitative models. It applies to a mathematical model of physical
phenomena, some of whose parameter values are not known with certainty. A joint
distribution is assigned to uncertain model parameters and propagated through the model
to yield a joint distribution over the model output. Thus, a quantitative uncertainty
analysis always has a joint distribution over model outputs as its result.

Joint Distribution/Marginal Distribution. For a set of uncertain quantities, a joint
distribution is an assignment of probabilities (or probability densities) for each possible
combination of values of these quantities. Each uncertain quantity has a marginal
distribution, that is, an assignment of probabilities (or probability densities) to each
possible value of that quantity. Assigning a marginal distribution to each quantity is not
equivalent to assigning a joint distribution to the set of quantities, unless the quantities
are independent; in this case the joint distribution is just the product of the margins.

52Many of these definitions are standard terms in probability and statistics, as described in Saltelli et al. (2000,
543756). Cox (2006, 5943421. Kurowicka and Cooke (2006, 543758). and NRC (2007, 543748); some are reflected
in current Agency practice (U.S. EPA. 2009, 522927).

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Qualitative/Informal Uncertainty Analysis. This assembles the arguments and evidence
and provides an assessment of their plausibility in terms of verbal modifiers. The
meaning of verbal modifiers such as "likely/unlikely" or "plausible/implausible" in the
natural language53 is indeterminate and context dependent. The way in which these
qualifiers combine in the natural language requires critical attention from a quantitative
viewpoint. (For example, if A is likely and B is likely and C is likely, is A and B and C
likely?) It is sometimes claimed that the probability formalism does not capture the way
people reason with uncertainty, and many alternatives have been proposed.54

This is not the place to discuss foundational issues, except to remark that the practitioner
wishing to depart from the standard probability formalism should carefully explore the
whole range of alternatives and critically examine the operational meaning of the
primitive notions.

Sensitivity Analysis. If a quantitative model uses "nominal values" (approximations of the
real values) for various input parameters, a sensitivity analysis is performed by choosing
different values for these parameters and re-running the model to assess the impact of
changes in these parameters on model output. Applicable methods include one- and
two-at-a-time methods, design of experiments and Morris's method (Saltelli et al., 2000,
543756). They aim at estimating first- and perhaps higher-order effects with a minimal
number of model runs, by systematically varying the nominal values. In large
uncertainty analyses, sensitivity analysis is used to screen variables for in-depth
uncertainty quantification, and thus is part of a quantitative uncertainty analysis
(Kurowicka and Cooke, 2006, 543758). As a note, the NAS committee report (NRC,
2006) does not distinguish between uncertainty and sensitivity analysis. In fields which
have not developed a tradition in uncertainty quantification, the spread of values
generated by a sensitivity analysis is sometimes presented as a representation of
uncertainty (Murphy et al., 2004, 543741). The question of whether this is or is not the
case is moot so long as the uncertainty on model input parameters is not quantified.
Systematically varying input values is not the same as sampling input parameter values
from their uncertainty distributions. In any event, a systematic approach to parameter
variation is essential; simply choosing a few values of interest and generating different
output is of limited scientific benefit and inevitably raises questions of selection bias.

That said, if alternative values are commonly used and therefore recommend themselves,
then running these through the models can help sensitize users to parameter variations
and their impacts on model outputs.

53Natural language denotes any discourse in which the meaning of the words is not formalized; rather, these words
are just "as they come in off the street" with whatever meaning a participant may give them.

54Before the advent of personal computers, various shorthand techniques were developed for computing system risk.
In control theory, schemes of 'interval probabilities' were proposed which could be propagated through a system to
yield bounds on system reliability. Whereas these bounds originally reflected accuracy of shorthand approximations
of complex formulae, their offspring have been proposed as quantifications of uncertainty. Alternative notions of
uncertainty are also proposed with the goal of simplifying the assessment and computational burden or capturing
putative features of uncertainty which are overlooked in probability theory. These include possibility theory, fuzzy
numbers, qualitative algebra, imprecise probabilities, belief functions, certainty factors, and the like. Nonmonotonic
reasoning systems attempt to capture reasoning about knowledge, or reasoning from partial knowledge; they include
default logic, defeasible logic, abductive logic, and autoepistemic logic, to name a few.

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Cognitive Uncertainty. This concerns uncertainty regarding what is the case. Not
knowing "what is the case" may be conceived as uncertainty over the set of all
possibilities, sometimes expressed as 'uncertainty over the set of possible worlds.'
Uncertainty over possible worlds may be represented formally as probability; that is, the
uncertainty of a given situation is represented as a number between zero and one, and the
uncertainty of either of two mutually exclusive situations is the sum of the uncertainties
of each situation.55 Two interpretations or operationalizations of the probability
formalism are current: the objective or frequentist interpretation and the subjective or
Bayesian interpretation. These interpretations are not mutually exclusive, as subjective
probabilities can and often do track relative frequencies.

Volitional Uncertainty. This concerns uncertainty regarding what to do. In the natural
language, being unsure which course of action to choose is also called "uncertainty."
Insofar as uncertainty on the best course of action can be translated into a claim about the
state of the world, volitional uncertainty can be translated into cognitive uncertainty. For
example, a regulatory body charged with setting a speed limit is obliged to make a
decision. The decision may be cautious or reckless, well or poorly motivated, wise or
foolish; but it cannot be true or false. Since the decision makes no claim about the state
of the world, it cannot be uncertain in the cognitive sense. The uncertainty cannot be
analyzed by sampling from some distribution. However, if the decision is based on the
claim that the chosen speed limit minimizes accidents while maintaining a prescribed
traffic volume, that claim may be uncertain and may be subjected to quantitative
uncertainty analysis. A discretionary decision of a regulatory body may entrain cognitive
uncertainty, but it becomes amenable for quantitative uncertainty analysis only when it is
linked to a claim about the state of the world.

Aleatoric/Epistemic Uncertainty. This terminology has become standard in the technical
uncertainty analysis literature, and it has been called Variability/Uncertainty in some
areas, particularly dealing with human populations. A variable whose uncertainty is
aleatoric for a given population takes different, uncertain, values for each member of the
population. If its uncertainty is epistemic, it takes the same uncertain value for all
members of the population. Issues involving uncertainty and variability or epistemic and
aleatory uncertainty translate into issues of dependence, when conducting a quantitative
uncertainty analysis (see Section 6.1.3.3). In its Science and Judgment report, NRC
(1994, 006424) correctly remarks that "the amount of variability is generally itself an
uncertain parameter." It is natural to ask whether a given uncertainty is aleatoric or
epistemic, whereas it is awkward to ask whether this uncertainty is uncertain or
variable—which explains the preference for the epistemic/aleatoric terminology.

55These are known collectively as Kolmogorov's probability axioms. The additivity of probability for exclusive
alternatives states, e.g., that the probability of an unseen object being red or green is the sum of the probability that it
is red and the probability that it is green. This of course assumes that "red" and "green" are clearly defined, such
that nothing can be simultaneously red and green. Many alternative representations of uncertainty contest this
additivity property.

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6.1.3. Key Elements of a Quantitative Uncertainty Analysis

The uncertainty propagation can be performed by some rough estimation, as for example
the delta method (Oehlert, 1992, 543742). or in rare cases it can be performed analytically, as in
simple error propagation.56 Most often, however, it will be performed using Monte Carlo
simulation. A joint distribution is assigned to the parameters of a quantitative model and then
propagated through the model by sampling repeatedly from this joint distribution, computing
model output and generating a distribution of model output. Every uncertainty analysis is
conditional on initial assumptions. A "complete" uncertainty analysis is an unattainable goal; the
best that can be done in practice is to identify and motivate the assumptions that are used. This
section is not a how-to guide, but a to-do list of key elements of any quantitative uncertainty
analysis.57

6.1.3.1.	Quantitative Model

The starting point of any quantitative uncertainty analysis is a mathematical model or
procedure for calculating quantities of interest. A structured narrative explains the choice of
quantitative models. If some values of input parameters for this calculation are not known with
certainty, then the question arises: "What is the uncertainty attending the use of this model?"

This is the question a quantitative uncertainty analysis seeks to answer.

6.1.3.2.	Marginal Distributions over Model Parameter

If the model parameters are directly measurable with sampling error, then the sampling
distribution may itself be used in the quantitative uncertainty analysis. If the model parameters
are fit to data that are sampled from a known or hypothesized distribution, then by resampling
this distribution and refitting the model, distributions over the model parameters may be
constructed. Physically-based simulation models, such as pharmacokinetic models or
environmental transport models, may be solved analytically if equilibrium reaction rates (the

56Simple measurement error is often represented by adding a normally distributed random variable with mean zero
to a "true" value. If several measurements are performed in succession, and the errors on each measurement are
assumed to be independent, then the error induced by adding the measurement results is also a normally distributed
random variable whose mean is zero and whose variance is the sum of the variances on the individual
measurements.

57These key elements of quantitative uncertainty analysis are discussed in many publications such as Saltelli et al.
(2000, 5437561. Cox (2006, 5943421. Kurowicka and Cooke (2006, 5437581. NRC (2007, 5437481 and EPA (2009,
5229271.

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transfer coefficients) are constant. If these rates are not constant, as when concentrations are
near saturation levels, then simulating the pharmacokinetics or transport is indicated. Structured
expert judgment has been applied for uncertainty quantification within the engineering
community since the time of the Rasmussen Report (U.S. NRC, 1975, 543729). More recently,
this approach has been "test-driven" by EPA in assessing health effects of fine particulates
(Walker et al., 1999, 198615). and its potential application has been identified in the Agency's
Guidelines for Carcinogen Risk Assessment, commonly referred to as the Cancer Guidelines
(U.S. EPA, 2005, 086237).58

6.1.3.3. Dependence between Parameter Uncertainties: Aleatoric and Epistemic (Uncertainty
and Variability)

Two uncertain quantities are independent if knowledge about one of them does not alter
our uncertainty regarding the other. The quantities are dependent if they are not independent.
The role of dependence modeling in quantitative uncertainty analysis must be addressed. To
illustrate, cigarette smoking and body fat are both thought to influence biomarkers for toxic
response to dioxin exposure, such as ethoxyresorufin-O-deethylase (EROD) activity (Pereg et al.,
2002, 199797). In an individual sampled at random from a target population, both percent body
fat and whether (and how much) he or she smokes are uncertain.59 However, these uncertainties
are not independent, inasmuch as smokers tend to have less body fat (Vanni et al., 2009,

543754).

Issues involving uncertainty and variability, or epistemic and aleatory uncertainty,
translate into issues of dependence when conducting a quantitative uncertainty analysis. For
example, a constant used to estimate the biokinetic behavior of dioxin may be uncertain. If it is
believed to be the same for every member of the population, the uncertainty is termed

58The EPA (2005, 0862371 cancer guidelines state: "In many of these scientific and engineering disciplines,
researchers have used rigorous expert elicitation methods to overcome the lack of peer-reviewed methods and
data...." These cancer guidelines are flexible enough to accommodate the use of expert elicitation to characterize
cancer risks, as a complement to the methods presented in the cancer guidelines. According to NRC (2002,

0353121. the rigorous use of expert elicitation for the analyses of risks is considered to be quality science."

59Because dioxins generally distribute to body fat/lipid, the percent body fat is often used to estimate body burden; a
default value of 25% is common (Connor and Ayhvard. 2006, 1976321. However, body fat percentage varies
widely between individuals, from a minimum essential level (e.g., 2% for men, 10% for women) to obesity (e.g.,
38% or more for men, 42% for women). Considering that current estimates suggest 30% of the U.S. population are
obese, an uncertainty analysis of dioxin risk in this population should sample individuals from their gender/body fat
distribution and correlate this with other known or suspected covariates influencing toxic response (such as diet,
smoking, natural and endogenous ligands, disease, and age).

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"epistemic." In a quantitative uncertainty analysis, this factor would be sampled from its
uncertainty distribution on each Monte Carlo run and used for all members of the population.
Body fat, in contrast, is aleatoric. We do not sample one value from the body fat distribution and
use this value for all members of the population on each Monte Carlo run. Instead we sample a
body fat value for each individual on each run. Because body fat is correlated with other
relevant variables (e.g., smoking, gender, age, and socioeconomic status), all of these variables
should be sampled in a manner that reflects their dependences. Kinetic constants whose
uncertainty is epistemic are completely correlated across individuals: if the value is 0.5 for one
individual, it is 0.5 for everyone. Body fat values vary from individual to individual, and they
are correlated through a host of other variables.

6.1.3.4. Model Uncertainty

All models, being idealizations, are false; on this there is no uncertainty to quantify.
However, the choice of model may constrain the ability to represent uncertainty in observable
phenomena. Thus, in a linear low-dose model, uncertainty over a cancer slope factor may be
quantified, but uncertainty regarding changes in slope at distinct low-dose regimes cannot be
captured. When the model choice imposes severe and potentially unwelcome constraints on
uncertainty quantification, this must be addressed. Distributions over model parameters may be
selected and evaluated based on their ability to reflect uncertainty distributions over observable
phenomena predicted by the models.60 In such cases, the uncertainty propagated through the
quantitative model is not strongly model-dependent. In other cases, multiple model alternatives
may be applied, whose "probability of being the true model" is known or assumed. Since
different models can always be regarded as specializations of more general models, the
distinction between parameter and model uncertainty is sometimes more apparent than real. For
example, as illustrated in the EPA Benchmark Dose Software (BMDS) (U.S. EPA, 2000,
052150s). the multistage and Weibull dose-response models both contain the model Pr(x) = y +
(1 - y) (1 - e ^l x) as a submodel, to which they collapse if other parameters are zero (multistage)
or one (Weibull). Recalling that the function 1/(1 + x) is first-order equivalent to (1 - x) for

60 Such techniques were first used on a large scale in the U.S. NRC-EU joint uncertainty analysis of consequence
models for accidents at nuclear power plants, see Goossens et al. (1996, 548727: 2001, 548737: 2001, 548738: 2001,
548731: 2001, 548732: 2001, 5487351 (Bock et al.. 1998, 5487521.

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small x, the same may be said for logistic models as well. In this case, these models could easily
be parameterized within one family, rendering the choice between them a choice of parameter
values. Similarly, the choice between sub-, supra-, and linear models is sometimes reduced to
parameter estimation within a more general class of model (Hoel and Portier, 1994, 198741).

In other cases, the reduction of model uncertainty to parameter uncertainty is less natural.
For example, according to the "chemoprotection model" of Greenlee et al. (2001, 0154001
dioxin's binding to the aryl hydrocarbon receptor (AhR) inhibits proliferation in tumor cells and
thus suppresses mammary tumors. Dose-dependent protection and cancer induction can both be
true, each applying to different tissues. Although mathematical models exhibiting these twin
features have been suggested (e.g., Kohn and Mel nick, 2002, 199104). these models are not yet
readily estimable from data, and the choice between them is referred to the structured narrative.

6.1.3.5.	Sampling Method

All sampling on a computer is "pseudo random." Significant issues arise in choosing a
method for sampling high-dimensional distributions with dependence. If evaluating the
quantitative model is very time consuming, various "quasi random" schemes may be applied,
including Latin hypercube sampling, importance sampling, and Hammersley sampling. These
methods involve trade-offs between economy and accuracy of the dependence modeling.

6.1.3.6.	Method for Extracting and Communicating Results

When a large quantitative uncertainty analysis has been performed, the method for
identifying important contributors and communicating this information to users is not
straightforward. Analysts have proposed many ways to quantify the uncertainty contribution of
one variable, or set of variables, on others,61 and the analyst's decision at this juncture may
strongly impact the "take-home" message from the study. An importance measure that averages

61A few examples may suffice. The standard Pearson correlation coefficient measures the linear dependence
between two variables, positive or negative. The rank or Spearman correlation coefficient measures the monotone
dependence. The correlation ratio measures the (unsigned) variance contribution of an explanatory variable on a
target variable. The regression coefficient measures the expected change in standard (not natural!) units of a target
variable, per standard unit change in an explanatory variable, and assumes this expected change is independent of
the values of the explanatory variables. Multiple correlation measures the correlation between a given variable and
its best linear predictor based on another set of variables. The partial correlation of two variables given a set of
other variables is their correlation after discounting the influence of the other variables. The correlation ratio,
multiple correlation, and the regression coefficient are not symmetric; the correlation ratio and multiple correlation
are always non-negative (Kurowicka and Cooke. 2006, 543758: Saltelli et al.. 2000, 543756).

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over an entire sample space may obscure the features of real interest. For example, the drivers of
cancer induction at low doses might be different from the drivers at high doses. If the drivers of
low-dose cancer induction are of interest, then importance measures that average over all doses
should not be considered.

6.2. EPA APPROACHES FOR ORAL CANCER AND NONCANCER ASSESSMENT

Different types of toxicity information have historically been used in EPA's oral cancer
and noncancer dose-response assessments, although efforts to harmonize these approaches are
ongoing. For oral exposures, noncancer endpoints are commonly assessed using the RfD
methodology to derive "an estimate (with uncertainty spanning perhaps an order of magnitude) of
a daily oral exposure to the human population (including sensitive subgroups) that is likely to be
without an appreciable risk of deleterious effects during a lifetime." In contrast, cancer
endpoints are commonly assessed using a dose-response function with the probability of excess
risk above background modeled as a linear function of dose, for doses down to zero. The RfD
method relies on a POD. The cancer dose-response method uses a POD if the linear model is
chosen. From the Cancer Guidelines, cancer endpoints can also be assessed using the RfD
methodology if the proof burden is satisfactorily met (as described in Section 5.2.3.4.1.2).

Toxicity reference values have typically been derived for human noncancer endpoints
based on a no-observed-adverse-effect level (NOAEL) or lowest-observed-adverse-effect level
(LOAEL) from animal bioassay studies. This terminology suggests a biological population
threshold beneath which no harm is anticipated. Reference values such as the oral RfD or
inhalation reference concentration are derived by applying uncertainty factors (UFs) to a POD.
Depending on the nature of available data and modeling choice, a POD can be selected from
values other than a NOAEL or LOAEL, such as an EDX (effective dose eliciting x percent
response), or a benchmark dose (BMD) or its lower confidence bound (BMDL). The BMD is
the dose that induces a benchmark response (BMR), which is often chosen to represent a 5 or
10% increase in excess risk above background. The POD is divided by one or more uncertainty
factors that represent knowledge gaps (see Section 6.4.1.2 for details on specific types of UFs).

An RfD is described as "likely to be without appreciable risk" but the probabilistic
language has not as yet been operationalized. A quantitative definition of "appreciable" has not
been articulated, and methods to compute risks above the RfD as a function of dose have not

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been designated for use by the EPA; thus, it is not current practice to ascertain that the risk is
indeed not appreciable. In addition, different participants in discussions over
threshold/nonthreshold models for dioxin may have different perspectives regarding how to
define "appreciable risk." Under the current POD/UF framework, dose-response functions are
not provided for calculating the actual risk at or above the RfD. Instead, to provide a "risk
indicator" for use in screening for health hazards, a hazard quotient (HQ) is computed as the
ratio of a given oral exposure to the RfD, or a margin of exposure (MOE) is estimated as the
ratio of the POD to the human exposure level.

For the cancer endpoint, an oral cancer slope factor may be derived for human health risk
assessment, typically based on tumor incidence data from an animal bioassay or on cancer
incidence or deaths from an epidemiologic study. In the EPA Cancer Guidelines, cancer is
predominantly thought to have no population biological threshold and a linear extrapolation to
zero is applied from the POD based on extra risk above background, i.e., the probability of the
endpoint decreases linearly in dose from the POD to zero or to a population background level. In
the absence of sufficient information on the cancer mode of action (MOA), the linear model is
applied as a default. The linear model also can be applied when there is sufficient MOA
evidence supporting this choice for low-dose cancer induction. Cancer endpoints could also be
evaluated using a "nonlinear" model. In this case, the proof burden clearly rests on the nonlinear
model; there must be sufficient evidence to override the health-protective default or
scientifically-based choice of a linear model, as described in the Cancer Guidelines. These
Guidelines state, "When adequate data on mode of action provide sufficient evidence to support
a nonlinear mode of action for the general population (emphasis added) and/or any
subpopulations of concern, a different approach—a reference dose/reference concentration that
assumes that nonlinearity—is used." In current terminology, the RfD methodology applies to the
cancer endpoint if there is sufficient evidence supporting a "zero slope at zero" model;
otherwise, the linear nonthreshold model applies by default. (See Section 5.2.3 for a detailed
discussion of linear vs. nonlinear extrapolations below the observed data, population vs.
individual thresholds, and how the Cancer Guidelines are applied in choosing dose-response
model forms for risk assessment.)

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6.3. HIGHLIGHTS OF NAS REVIEW COMMENTS ON UNCERTAINTY
QUANTIFICATION FOR THE 2003 REASSESSMENT

The NAS (2006, 198441; 2006, 543760) identified a number of uncertainty
characterization issues for the 2003 Reassessment; key sources of uncertainty for which
quantification is suggested are highlighted in Table 6-1. The discussion in this section focuses
on comments related to dose response.

There are several nuances in the NAS position relative to the need for substantial
improvement in transparency, thoroughness, and clarity in quantitative uncertainty analysis for
the 2003 Reassessment. These nuances concern whether the nonlinear model (note that the NAS
committee uses "sublinear" and "nonlinear" interchangeably) is scientifically better supported
than the linear model, and if the sublinear model is better supported, whether this is based on
data or on apodictic knowledge (knowledge without uncertainty) of the MOA. The NAS
committee does not distinguish between individual and population dose-response models;
however the criteria from the EPA Cancer Guidelines clearly apply to population models.
Assuming that the AhR-mediated MOA implies a threshold for each individual, the step to a
population "zero slope at zero" model requires the following, as identified and discussed in detail
in Section 5.2.3.:

1.	The distribution of the individual thresholds induced by the MOA, and

2.	The dose-response function for values above the thresholds.

This information can either come from data or from known information of the MOA, but
the burden of proof clearly rests on the nonlinear model. This section summarizes the NAS
committee's overall positions. Responses to specific suggestions are given in Section 6.4 and
summarized in Section 6.5. Several excerpts of specific comments from NAS (2006, 198441)
illustrate key issues.

The NAS committee favors the nonlinear model with a threshold:

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.. .the committee concludes that, although it is not possible to scientifically prove
the absence of linearity at low doses, the scientific evidence, based largely on
mode of action, is adequate to favor the use of a nonlinear model that would
include a threshold response over the use of the default linear assumption.

(p. 122)

The committee does not state whether the threshold applies to the population, or whether each
individual has his/her own threshold.

The NAS also comments on whether the nonlinear model should be used to compare with
the linear default:

Because the committee concludes that the data support the hypothesis that the
dose-response relationship for dioxin and cancer is sublinear, it recommends that
EPA include a nonlinear model for cancer risk estimates but also use the current
linear models for comparative purposes, (p. 16)

The committee does not suggest what the (population/individual) threshold might be, nor how it
might be supported on the basis of data. Rather, the apodictic knowledge that there is a
(population/individual) threshold places the dioxin risk assessment within the RfD framework,
using a HQ or MOE as the basis for indicating the potential risks from exposure. The committee
further asks for a quantitative characterization of the range of uncertainty:

The committee determined that the available data support the use of a nonlinear
model, which is consistent with receptor-mediated responses and a potential
threshold, with subsequent calculations and interpretation of MOEs. EPA's sole
use of the default assumption of linearity and selection of ED0i as the only POD
to quantify cancer risk does not provide an adequate quantitative characterization
of the overall range of uncertainties associated with the final estimates of cancer
risk. (p. 24)

Regarding the Cancer Guidelines' requirement of sufficient evidence to use a nonlinear
approach for cancer risk assessment, the committee indicates that quantitative evidence will not
decide the linearity/nonlinearity (nonthreshold/threshold) issue, but knowledge (without
uncertainty) of the MOA should be used:

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Quantitative evidence of nonlinearity below the point of departure (POD), the
ED0i62 will never be available because the POD is chosen to be at the bottom end
of the available dose-response data. ... EPA should give greater weight to
knowledge about the mode of action and its impact on the shape of the
dose-response relationship, (p. 178)

The comment continues, with the committee implicitly acknowledging that there is no
evidence arguing against linearity, but that the lack of evidence should not justify using the linear
model.

The committee considers that the absence of evidence that argues against linearity
is not sufficient justification for adopting linear extrapolation, even over a dose
range of one to two orders of magnitude or to the assumption of linearity through
zero, which would not normally be applied to receptor-mediated effects, (p. 178)

In addition, the committee recommended that EPA explore both linear and nonlinear
approaches to TCDD cancer assessment:

On the whole, the committee concluded that the empirical evidence supports a
nonlinear dose response below the EDoi, while acknowledging that the possibility
of a linear response cannot be completely ruled out. The Reassessment
emphasizes the lack of such nonlinear models, hence its adoption of the approach
of linear extrapolation below the POD level. Although this approach remains
consistent with the cancer guidelines...., EPA should acknowledge the qualitative
evidence of a nonlinear dose response in a more balanced way, continue to fill in
the quantitative data gaps, and look for opportunities to incorporate mechanistic
information as it becomes available. The committee recommends adopting both
linear and nonlinear methods of risk characterization to account for the
uncertainty of dose-response relationship shape below EDoi (p. 72).

In this document, EPA has applied its own guidance on cancer risk assessment and
adopted linearity (and an assumption of no threshold) as a health-protective default approach in
the absence of sufficient evidence of MO A involving a threshold for all tumors resulting from
TCDD exposures (volitional uncertainty). (Note that the NAS report appears to view the
absence of evidence as imposing a burden of proof on the linear model [cognitive uncertainty];
see Sections 5.2.3.4.1.2 and 6.2 regarding the burden of proof.) In addition, the NAS
committee's request to apply nonlinear methods for the cancer assessment is addressed, in

62 Eeffective dose (ED) is the dose corresponding to a X% increase (in this case a 1%) in an adverse effect such as a
concer endpoint, relative to the control response.

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Section 5.2.3.4.1.4 of this document. That evaluation describes the application of nonlinear
methods to TCDD data and presents two illustrative examples of RfD development for
carcinogenic effects: one based on tumorigenesis in experimental animals, and the other on
hypothesized key events in TCDD's MO As for liver and lung tumors.

The thrust of the NAS remarks regarding transparency, thoroughness and clarity in
quantitative uncertainty analysis relevant to dose-response can be summarized as follows:

1.	The uncertainty of cancer risks due to dioxin exposure should be quantified.

2.	Dioxin cancer risk should be treated either as a threshold phenomenon, thus following the
basic RfD methodology, or should be modeled using a sublinear dose-response function
below the observed data, with the linear model used for comparison.

3.	The POD should be subjected to quantitative uncertainty analysis.

A similar point of view has been indicated by others.63 Detailed suggestions regarding specific
improvements for quantitative uncertainty analysis in the 2003 Reassessment are outlined in the
next section and summarized in Section 6.5.

6.4. FEASIBILITY OF CONDUCTING A QUANTITATIVE UNCERTAINTY
ANALYSIS FOR TCDD

This section focuses on uncertainty analysis for TCDD dose response, which involves a

range of issues as highlighted in Table 6-1.

6.4.1. Feasibility of Conducting a Quantitative Uncertainty Analysis under the RfD
Methodology

This discussion applies to all noncancer endpoints of TCDD, and to cancer endpoints
insofar as they fall under the RfD methodology. An RfD is obtained through the following steps:

1.	Choose a POD, then

2.	Apply uncertainty factors (UFs) to account for knowledge shortfalls.

' "For example, from Popp et al. (2006, 1970741. "Overall, the evidence indicates that (1) TCDD causes cancer via a
receptor-mediated process; (2) this dose-response is non-linear; and (3) a threshold region exists for TCDD-induced
cancer below which adverse effects are unlikely to occur."

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The method of uncertainty factors harkens back to the engineering practice of safety
factors (Lehman and Fitzhugh, 1954, 003195). To illustrate, if the reference load for an
engineered structure is X, then engineers might design the structure to withstand load 3X, using a
safety factor of 3 to create a margin of safety. If the structure functions in a corrosive
environment, another factor could be multiplied to guarantee safety for that condition, and
another factor could be applied for heat, another for vibrations, and so on. The choice of values
is simply based on good engineering practice, i.e., reflecting what has worked in the past.
Although safety factors are still common in engineering, they are giving way to probabilistic
design in many applications. The reason is that compounding safety factors quickly leads to
overdesigning. Compounding safety margins for spaceflight systems may render them too heavy
to fly. As our understanding of a system increases, it becomes possible to guarantee the requisite
safety by leveraging our scientific understanding of the materials and processes. That of course
requires formulating clear probabilistic safety goals and developing the techniques to
demonstrate compliance.

The engineering community has never sought to account for uncertainty by treating
safety factors as random variables and assigning them (marginal) distributions; such an approach
would not counteract the overdesigning inherent in safety factors. Many authors, including the
recent national committee for Science and Decisions (NRC, 2009, 194810). have advocated just
such a probabilistic approach to the apparent "overdesigning" of the RfD when multiple UFs are
used in its derivation.

The NAS committee that evaluated the 2003 Reassessment does not discuss how to
perform uncertainty analysis. But their call for substantial improvement in quantitative
uncertainty analysis with TCDD falling under the RfD framework entails examining the
feasibility of quantitative uncertainty analysis within this framework. (Note that the EPA
Integrated Risk Information System (IRIS) database uses uncertainty factors without
probabilistic interpretations; some context for this is offered in Section 6.4.1.2.)

6.4.1.1. Feasibility of Conducting a Quantitative Uncertainty Analysis for the Point of
Departure

The POD plays a role in both the noncancer RfD methodology and the cancer
dose-response methodology. The POD can be selected from various options, such as a NOAEL

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or LOAEL, a BMDL, or an EDX. The feasibility of quantitative uncertainty analysis for each of
these three options is considered below.

By definition, the NOAEL is the highest of the tested doses in a toxicological experiment
that is judged not to have caused an adverse effect (with dose expressed as a dose rate, in
mg/kg-day). A quantitative uncertainty analysis for a NOAEL or LOAEL encounters the
following problem. In an experiment involving a small, positive response, the probability of
seeing no response can be calculated using a binomial model with the number of exposed
animals and the observed number of responses. However, in an experiment with no response,
the probability of having observed a response cannot be calculated without assuming a response
probability. Such an assumption could not be based on observed data. The probability of a
higher NOAEL or higher LOAEL can be computed, but not that of a lower NOAEL or LOAEL.
In other words, the probability that an experiment with a positive result may have yielded a null
response can be estimated, but not the probability that an experiment with a null response might
have yielded a positive response.64

In addressing uncertainty quantification for a BMDL or EDX, two questions must be
distinguished regarding the response:

1.	What is the distribution of possible doses that causes an x% increase over background?

2.	What is the distribution for possible values of increase over background caused by a
given dose?

The BMD is defined as the dose that realizes a BMR. It is an estimate from bioassay data
that requires choosing a BMR and fitting a dose-response curve. The BMR, being a choice, is
not amenable to quantitative uncertainty analysis, but the choice can be motivated in a structured
narrative. The BMDL is the lower confidence limit on the dose that realizes a BMR (e.g., 95%)
that can be found based on the uncertainty in the parameters of the dose-response relationship.
Thus, the BMDL is addressed to the first question above, and represents in this case the
95% lower confidence band of the distribution of possible doses causing an x% increase over
background. In the standard approach, the uncertainty captured by the BMDL is sampling

64The probability associated with a null response is often estimated by fitting a dose-response model to the data.

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uncertainty conditional on the truth of the dose-response model. Different models might fit the
data equally well yet lead to different BMDLs.

The BMDL is also influenced by the constraints imposed on the parameter fitting.
Suppose that the slope is expected to be greater than one, and that the maximum likelihood
estimate of the slope is slightly greater than one. Since the constraint is not binding, the
constrained and unconstrained model would have the same Akaike Information Criterion and
would be equivalent in this sense. However, computing the BMDL with the slope constraint can
lead to very different values than without this constraint. In the latter case, slope values less than
one contribute to the uncertainty in the dose causing the BMR (see Cooke, 2009, 543763).

The EDX can also be taken as a POD. It is similar in spirit to the BMD; however, as used
here, the term EDX applies when the dose causing an x% extra risk over background has actually
been observed, not estimated from a fitted dose-response model.65 The observations are subject
to sample fluctuations, and if the experiment on which the EDX is based were repeated, different
values might be found. It is helpful to consider a numerical example. Suppose a background
response rate of 10% is established based on many observations of nonexposed individuals. In a
given experiment, involving say 100 individuals given dose 14 individuals responded. The
percent increase x over background (extra risk) is found by solving:

14/100 = 10/100 + x x 90/100, or x = 4.4%.

We conclude that d = ED4 4. We may assume that if the experiment were repeated with 100 new
individuals sampled independently from the whole population, the response would be given by a
binomial distribution with parameters (14, 100). The number of responses might be greater or
smaller than four, there is a 16% chance of observing 10 or fewer responses. The response to
dose d would not be distinguished from the background in that case, and a higher dose would be
used for the POD.

The uncertainty analysis of EDX as the POD involves addressing the second question
above, without a quantitative dose-response model. A quantitative uncertainty analysis is
hampered, however, by the possibility that dose d would produce a response less than or equal to

65This definition of EDX is adopted to distinguish the modeled response (BMD) and the observed response (EDX),
and it is more restrictive than usages common in the literature.

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the background, in which case the POD is indeterminate—another experiment with a different
dose would be chosen as the POD. A true quantitative uncertainty analysis of EDX as the POD
would thus require a full bioassay experimental design, with binomial sampling of response rates
at each dose level in the assay. Absent that, quantitative uncertainty analysis is not possible.

The interplay of choice and estimation ingredients in the POD depends on the type of
POD. The main features of the above discussion are captured in Table 6-2. This table notes that
the BMDL captures the uncertainty caused by sampling fluctuations given that the dose-response
model is true. Other methods are available to compute the BMDL using (1) model-independent,
observable uncertainty; (2) nonparametric Bayesian dose-response models; or (3) Bayesian
model averaging (Cooke, 2009, 543763). Only the EDX can be subject to a quantitative
uncertainty analysis, and then only if a full bioassay data set is available.

6.4.1.2. Feasibility of Conducting a Quantitative Uncertainty Analysis with Uncertainty
Factors

Uncertainty factors are chosen based on a structured narrative characterizing knowledge
shortfalls involving the following issues:

1.	Interspecies extrapolation (UFA: from animal data to humans).

2.	Intraspecies extrapolation (UFH: to account for human interindividual variability,
considering sensitive subgroups).

3.	LOAEL to NOAEL extrapolation (UFL: to estimate the dose corresponding to no adverse
effect, from a reported LOAEL).

4.	Subchronic to chronic extrapolation (UFS: to estimate effects of chronic exposures, from
a subchronic study).

5.	Database deficiency (UFD: to extrapolate from an incomplete data set, e.g., in terms of
endpoints assessed or study design, i.e., from a poor to a sufficient or rich data context).

The standard chronic RfD can represent a sensitive human (H) response to a toxic
substance under chronic (C) exposure conditions. Suppose a BMDL POD were based on animal
(A) data from a subchronic (S) study. The database for that chemical could be rich (R), e.g.,
involving multiple (and at least sensitive) species/strains, both sexes, multiple life stages, with
multiple endpoints observed under sound study designs. Or the data could be poor (P), with
limited measurements from only a subchronic animal study (ASP) forming the basis for

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estimating a general reference value for humans (including sensitive subgroups) under chronic
exposure conditions. For that case, the UF method would be applied as follows:

A SP

RfD =	—		(Eq. 6-1)

UFaxUFsxUFdxUFh

where UFA, UFS, UFD, and UFH are the uncertainty factors for extrapolating from animals to
humans (UFA), subchronic to chronic exposure conditions (UFS), without adequate endpoint
coverage (UFD), and considering sensitive human subpopulations (UFH). It is possible to assign
distributions to the UFs in Eq. 6-1, and to perform a Monte Carlo analysis to produce a
quantitative uncertainty distribution over the dose or value likely to be without appreciable risk
to humans for chronic exposures. Many authors have proposed such an approach,66 and the
recent NRC (2009, 194810) report on science and decisions encourages EPA to move in this
direction.

The idea of using a Monte Carlo analysis to develop quantitative uncertainty distributions
for the RfD is simple, but the data on which the UFs are based and the assumptions that would
need to be made should be further explored. For example, it is assumed that the extrapolation
from subchronic to chronic exposure (UFS) is the same whether applied to animals or humans,
and whether applied to sufficient (rich) or deficient (poor) data contexts. Swartout et al. (1998,
093460) noted "Within the current RfD methodology, UFS does not consider differences among
species, endpoints, or severity of effects; the same factor is applied in all cases." In addition, due
to the paucity of relevant human data, the same authors suggested the use of other endpoints as
surrogates in estimating the extrapolation from animals to humans, UFa- Further, few data exist

66There has been considerable work on giving a probabilistic interpretation of the UFs, including by Abdel-Rahman
and Kadry (1995), Vermeire et al. (1999), Baird et al. (1996), Swartout et al. (1998, 093460). Slob and Pieters
(1998, 087256). Evans and Baird (1998), Calabrese and Gilbert (1993), Calabrese and Baldwin (1995), Hattis et al.
(2002, 548720). Kang et al. (2000, 548722). and Pekelis et al. (2003, 548723). These evaluations can be considered
to frame what might be called a random chemical approach. Several authors adduce properties based on log normal
distributions. Insightful studies by Kodell and Gay lor (1999;)(Gaylor and Kodell. 2000, 548724) suggest that
uncertainty factors are independent log normal variables. Combining uncertainty factors involves multiplying the
median values, and combining the "error factors" according to the formula KSxH = exp[1.6449 x V((js2 + (jH2)],
where cr/ aH2 are the variances of ln(UFs) and ln(UFH). Thus UFS x UFH is a lognormal variable with Median(UFs
x UFh) = Median(UFs) x Median(UFH), and 95th percentile given by Median(UFs x UFH) xKSxE. If Us and UH
each have an error factor or 10, then the error factor of UFS x UFH is not 100 but 25.95. Several authors suggest that
multiplying uncertainty factors might over-protect. Recent proposals from the National Research Council reflect the
random chemical concept, and they inherit its problems (NRC. 2009, 194810).

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in humans to accurately portray the interindividual variability represented by UFH. Much of the
data gathered to date on distributions of UFs have aggregated across other extrapolations; that is,
data from subchronic to chronic ratios are aggregated over different species and different data
contexts. Finally, it may be noted that an important issue is the data on which empirical
distributions of response ratios are based. Brand et al. (1999, 007629; 2001, 543765) studied the
sampling behavior of response ratios and raised concerns with regard to their informativeness.

Detailed analyses of the data underlying a Monte Carlo uncertainty analysis of Eq. 6-1
would afford the possibility of verifying at least some of the assumptions and numerical
estimations such an analysis must make. Even if the assumption that the same UFS is applicable
for all species, endpoints, and effect severities is thought to be biological plausible, the question
of whether a given set of chemicals reflects this assumption, and hence they are suitable for a
Monte Carlo analysis of Eq. 6-1, can only be decided by data evaluation. Data are the ultimate
arbiter of whether quantitative uncertainty analysis with uncertainty factors, as currently
envisioned, has sufficient evidentiary support.

6.4.1.3. Uncertainty Reduction Using Quantitative Data for Species Extrapolation

Expressing dose in units of exposure that are more closely related to target tissue than to
contact with administered feed (or an environmental medium) can reduce uncertainty in
extrapolations of dose, route or species. This concept underlies EPA's establishment of the
Inhalation Reference Concentration Methodology (U.S. EPA, 1994, 006488). Under this
method, species differences in tissue exposure for inhalation toxicants serve as the basis for
interspecies adjustments of dose. Likewise, the International Programme on Chemical Safety
(IPCS) has established guidance for chemical-specific adjustment factors (IPCS, 2005), which
also uses a measure of internal exposure (dose) to normalize (e.g., make equivalent) the dose
between species. Certain more recent IRIS values also reflect such an approach, with
data-derived extrapolation factors replacing default adjustments. Under such approaches, the
relationship between external exposure and target tissue exposure is determined in each species,
and the applied doses are normalized on the basis of the same level of the internal tissue
exposure. One distinction between the two approaches is that the IPCS (2005) approach is
based on the attainment of the same levels of the toxicant in the blood (the central compartment)
rather than in the actual target tissue (a consideration based in part on the fact that typically the

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only data available to evaluate a human toxicokinetic model will be venous blood
concentrations, rather than concentrations in a responding tissue or organ). Further, it has been
shown that species differences in internal dosimetry are more a function of species differences
in blood solubility than differences in tissue solubility—that is, once distributed to blood,
species differences in tissue exposure are less likely to be based on species differences in tissue
solubility.

The approach to development of interspecies extrapolation factors for inter- and
intraspecies extrapolation of effective dose for the oral RfD for dioxin, which is described in
Sections 3 and 4 of this document, is in agreement with both of these approaches. All tissues in
the body are exposed to dioxin via the bloodstream. Even in instances where the specific target
tissues for observed effects may be other than the tissue where the effect is observed (e.g.,
effects mediated through the endocrine system), this biologically-based approach remains valid
and reduces uncertainty in dose extrapolation. The approach to extrapolation of dosimetry—on
the basis of circulating levels of dioxin in blood—makes optimal use of human
exposure-response data, human biomonitoring data, and toxicokinetic modeling to estimate
equivalent exposures for humans and test species without requiring that the target tissue be
conclusively identified. The decision to base animal-to-human extrapolation on circulating
levels of dioxin in blood, as predicted by a well-evaluated PBPK model, reduces some potential
sources of uncertainty.

6.4.1.4. Conclusion on Feasibility of Quantitative Uncertainty Analysis with the RfD
Approach

A quantitative uncertainty analysis of the POD is not feasible for PODs based on
NOAELs or LOAELs. For the BMDL, such an analysis is not appropriate because the BMDL is
already a quantile from an uncertainty distribution of the BMD. However, this uncertainty
distribution can be obtained in different ways that capture different aspects of uncertainty.
Quantitative uncertainty analysis is feasible if the POD is based on the EDX (as defined above)
and is supported by a full set of bioassay data. A quantitative uncertainty analysis based on a
probabilistic interpretation of uncertainty factors in their present form invokes strong
assumptions. The data on which the distributions of uncertainty factors are based could be used
to check at least some of these assumptions.

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6.4.2. Feasibility of Conducting a Quantitative Uncertainty Analysis for TCDD under the
Dose-Response Methodology

Quantitative uncertainty analysis starts with a mathematical model and seeks to quantify
the uncertainty attending the use of this model. Dose-response relations are mathematical
models expressing the probability of response as a mathematical function of dose. For several
decades, the uncertainty attending the use of dose-response models has been an abiding concern
in many sectors, including the chemical and nuclear industries as well as the public health sector.
Given a set of animal bioassay data, quantifying dose-response uncertainty may be approached in
different ways. The differences reflect different types of uncertainty that are captured. A recent
evaluation enumerates the following possible methodologies (Bussard et al., 2009, 543770"):

Benchmark Dose Modeling (BMD): Choose the 'best' model, and assess
uncertainty assuming this model is true. Supplemental results can compare
estimates obtained with different models, and sensitivity analyses can investigate
other modeling issues.

Probabilistic Inversion with Isotonic Regression (PI-IR): Define
model-independent 'observational' uncertainty, and look for a model that captures
this uncertainty by assuming the selected model is true and providing for a
distribution over its parameters.

Non-Parametric Bayes (NPB): Choose a prior mean response (potency)
curve (potentially a "non-informative prior") and a precision parameter to express
prior uncertainty over all increasing dose-response relations, and update this prior
distribution with the bioassay data.

Bayesian Model Averaging (BMA) (as considered here): Choose an
initial set of models, and then estimate the parameters of each model with
maximum likelihood. Use classical methods to estimate parameter uncertainty,
given the truth of the model. Determine a probability weight for each model
using the Bayes Information Criterion, and use these weights to average the model
results.

The first of the above methods involves standard classical statistical methods and
captures sampling uncertainty conditional on the truth of the model used. The other methods are
"exotic" in the sense that they attempt to capture uncertainty that is not conditional on the truth
of a given model. All have been subjected to peer review and published, but they do not enjoy
the wide usage of the standard classical methods. The Bayesian models involve subjective
choices of prior distributions. Insofar as the final result is largely independent of the choice of

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prior, these methods conform to the current starting point of focusing on data-driven methods
and not appealing to structured expert judgment. (Structured expert judgment can also be
considered an exotic method; an explanation of this approach falls outside the scope of this
report.)

A quantitative uncertainty analysis of TCDD capturing uncertainty in extrapolating data
from animal bioassays to human reference values together with consideration of epidemiological
data from studies of workers (routine exposures) or the general public (including dietary
exposures and those reflecting discrete poisonings or accidental releases) would raise many
issues. The major issues are summarized below.

6.4.2.1. Feasibility of Quantitatively Characterizing the Uncertainties Encountered when
Determining Appropriate Types of Studies (Epidemiological, Animal, Both, and
Other)

The risk assessor must choose the data set(s) that will serve as a starting point for
dose-response modeling. With respect to TCDD, a wealth of animal bioassay data exist in the
scientific literature, across species ranging from rats, mice, guinea pigs, and hamsters to mink,
dogs and monkeys, and a variety of tissues, organs, and systems. In addition, a considerable
amount of human data is available from clinical/case reports, accidental releases, and
occupational exposures, including epidemiological data for several cohorts. As detailed in
Sections 2, 4 and 5, some of the main sources of uncertainty in the TCDD epidemiological data
include the healthy worker effect, confounding and exposure misclassification. Epidemiological
data are usually attended with large uncertainties regarding the doses actually received by
individuals. The difficulty in characterizing individual-level exposures largely stems from
having limited internal measures of TCDD exposure, as biomonitoring data may only be
available for one point in time or on a subset of the exposed population. Although there is little
direct evidence of strong confounding in the cohorts of TCDD and dioxin-like compounds, some
of the confounders that have been evaluated in a few of the epidemiological studies include
gender, body mass index, age, cigarette and alcohol consumption, and hair and eye color
(Baccarelli et al., 2005, 197053: 2006, 197036: Eskenazi et al., 2002, 197168: 2002, 197164:
Pereg et al., 2002, 199797). As discussed in Section 5 on TCDD carcinogenicity, an additional
limitation of the epidemiological evidence includes the lack of organ specificity, as many of the

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studies have shown associations between TCDD exposure and all-cause mortality. With
disagreement in the literature over the nature, scope, and quality of the epidemiological data for
TCDD, given the lack of precedent for a multisite carcinogen without particular sites
predominating, some have urged caution in the interpretation of the epidemiological data based
on small relative risks Popp et al. (2006, 197074).

Despite these uncertainties, the EPA Cancer Guidelines express a clear preference for
epidemiological studies over animal data. The question here is whether quantitative uncertainty
analyses based on either a collection of bioassay data or on several epidemiological studies can
be combined in some overall uncertainty assessment. Diverse human studies are sometimes
combined into a meta-analysis, and the issues arising in this regard are instructive. A primary
challenge of meta-analytical approaches is combining heterogeneous effects that may result from
studies of different populations, study designs or analytical techniques. The question of whether
uncertainty arising from combining such different studies can be taken into account in
quantitative uncertainty analysis is similar to that of accounting for uncertainty due to missing
covariates in Cox regression (see Section 6.4.2.2).

Existing standard statistical tools are insufficient to address this issue, as they quantify
uncertainty in model parameters estimated from data. However, exotic methods, such as
Bayesian methods, probabilistic inversion, or structured expert judgment may be applicable.
These methods can be applied when a quantitative model predicts other phenomena, even though
these phenomena could not be used to estimate the model. The question of whether such
methods could remain sufficiently tethered to data, or whether structured expert judgment is
unavoidable, is a subject for future research.

6.4.2.2. Uncertainty in TCDD Exposure/Dose in Epidemiological Studies

Uncertainties in epidemiological studies arise from a variety of study characteristics.
There are many types of epidemiological study designs which determine the data structure,
including intervention trials, case-control studies, cohort studies and cross-sectional studies. A
variety of mathematical models some of these can be used to analyze epidemiological data; some
of these includes Cox proportional hazard, Poisson regression, linear and logistic regression.
The model outputs are based on different measures of association such as rate ratios, risk ratios,
odds ratios, and standardized mortality ratios (SMRs, ratio of observed to expected deaths).

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Exposure uncertainties often concern back-casted exposures based on current serum lipid
concentrations, estimated/self reported dietary habits, fish consumption, placenta lipid
concentrations, and other measures.

Uncertainty in exposure is often dealt with by coarsely grouping a cohort into exposed
and unexposed groups. The output of such a study can be coarse grained in a similar way;
instead of computing dose-dependent risk estimates, standard mortality ratios might be used to
compare the exposed and unexposed groups. Packages computing the outputs routinely produce
confidence intervals that reflect sampling fluctuations (e.g., can indicate the potential for chance
to explain the association), assuming truth of the model. Additional uncertainty could be
factored in with exotic methods. A significant issue in epidemiological studies is the effect of
omitted covariates. Omitted covariates in Cox regression will bias the estimates of effects of
included covariates. If the omitted covariates are independent of the included covariates, the bias
is toward zero in absolute value (Bretagnolle and Huber-Carol, 1988, 543772); if the omitted
covariates are not independent, little can be inferred.

With regard to individual studies, it might be possible to identify specific opportunities
for uncertainty quantification. This is illustrated here using the study of Steenland et al. (2001,
198589) of more than 3,500 male workers exposed to TCDD-contaminated products at eight
U.S. chemical plants. Each worker was assigned an exposure score based on an estimated level
of contact with TCDD, the degree of TCDD contamination of product at each plant over time,
and the fraction of a workday in contact with the product. For 170 workers, the serum TCDD
levels were also measured. The serum levels were back-extrapolated to the last time of exposure
using a constant biological half life, and regressed on the exposure scores. This regression
model was used to predict the dose in all workers, and predicted dose was correlated with cancer
mortality. Figure 6-1 shows a scatter plot of back-casted versus predicted TCDD serum levels
for the 170 workers on which the regression was based.

Given a predicted TCDD level, the uncertainty on the back-casted TCDD value could be
inferred from such data by various techniques. A key question is whether the actual cancer
mortalities among 170 back-casted workers are randomly placed in the conditional distribution
given predicted TCDD. Imagine, in other words, that the mortalities among the 170 back-casts
are colored red in Figure 6-1. At any given level of TCDD prediction, are the red points evenly
distributed, or are they shifted to the right? In principle, the correlation between mortality and

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back-casted TCDD level, given the predicted level, could be estimated. This amounts to
estimating heteroscedasticity in the regression model.67 Then, for each of the 3,538 workers,
given his predicted TCDD level, we could sample a back-casted TCDD level, appropriately
correlating with mortality, and recompute the dose response analysis. Repeating this many times
we could build up a distribution for excess lifetime cancer mortality risk.

It is instructive to step through similar issues with regard to biological half life,
background and body fat. The Steenland et al. (2001, 197433s) analysis assumed a constant
TCDD biological half life (8.7 years). A distribution over this half life could plausibly be
developed from published sources. Assuming this half life is constant for all workers, but
uncertain (epistemic uncertainty), this distribution could easily supplement the previous
distribution: first sample a half life (to be applied to all workers), then estimate the regression
model for this half life, and sample back-casted TCDD levels given each worker's exposure
score, taking account of correlation with mortality. This works if the half life uncertainty is
epistemic. However, since the half life is estimated from data, it is more reasonable to suppose
that the half life varies from worker to worker (aleatoric uncertainty). Here again the correlation
with mortality must be taken into account, indeed it seems reasonable to suppose that the
256 cancer deaths involved workers with longer half lives. However, there is no way ex post of
determining the biological half life in the deceased workers.

The potential impact of uncertainty regarding background exposure and body fat is likely
similar to the uncertainty of estimating the half life of TCDD. Steenland et al. (2001, 197433)
held the background level constant at the median level (6.1 ppt, range 2.0 to 19.7) for
79 nonexposed workers from whom blood was also drawn (see also Section 6.4.2.4). The full
distribution of TCDD levels for these nonexposed workers could be used as well. Is it
reasonable to suppose that responsive workers (i.e., those exhibiting the response) have
background levels that are sampled randomly from this distribution, or might they not plausibly
come from the high end of the distribution? The analysis also assumed a constant percentage of
body fat (30%), whereas body fat percentage varies in the general population, e.g., for men this
has been reported to range from 2 to 38% or more (see Footnote in Section 6.1.3.3). The body

67 Heteroscedasticity occurs when the variance of the dependent variable in a regression analysis varies across the
data, violating the assumption of equal variance commonly used in many regression models.

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fat distribution in the worker population could have been ascertained, but again the question
arises, are the responsive workers sampled randomly from this distribution?

These three factors, variable half life, variable background, and variable body fat
percentage, might combine to make the effective dose level among the responsive workers
significantly higher than would appear in a study that assumes these factors to be constant.
However, such concerns cannot be addressed in a quantitative uncertainty analysis, unless cancer
mortality can be correlated with these variables. In an optimal study design, this information
could be retrieved from the data. However, in most observational epidemiological studies such
data are not available, and it might be possible to estimate these correlations in some other
defensible manner, in which case the effect of exposure uncertainty could be quantified and
propagated. Such an analysis would involve substantial effort and should not be undertaken
under assumptions that are themselves implausible. Protocols for epidemiological studies do not
currently require such uncertainty quantification. In any event, Steenland et al. (2001, 197433)
should be recognized for conscientiously identifying these key issues.

6.4.2.3. Uncertainty in Toxicity Equivalence (TEQ) Exposures in Epidemiological Studies

Toxicity equivalence factors (TEFs) are used to infer the health effects of dioxin-like
compounds based on their relative potencies compared to TCDD. These factors are not known
with certainty, and the question arises whether uncertainty in TEFs can be incorporated into a
quantitative uncertainty analysis. The process of deriving TEFs applied by the World Health
Organization (WHO, 2005, 198739) is described in Van den Berg et al. (2006, 543769).
Distributions of relative potencies (REPs) were developed from the scientific literature, with
preference for in vivo studies, as supplemented by in vitro studies. An expert panel used a
consensus process to select a TEF value for each congener, in half log steps "Thus, the TEF is a
central value with a degree of uncertainty assumed to be at least ± half a log, which is one order
of magnitude. However, it should be realized that TEF assignments are usually within the 50th to
75th percentile of the REP distribution, with a general inclination toward the 75th percentile in
order to be health protective" (Van den Berg et al., 2006, 543769) (see Figure 6-2 of this
document).

The WHO considers the uncertainty in TEFs to span one order of magnitude (presumably
log uniformly distributed). It would be tempting to use the distributions in Figure 6-2 to quantify

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uncertainty in the TEFs in a quantitative uncertainty analysis. However, the issue of dependence
in this case is daunting. For example, should values of 1,2,3,7,8,-pentachlorodibenzofuran and
2,3,4,7,8-pentachlorodibenzofuran be sampled independently? The choice of dependence
structure will have a large effect. As described by (Van den Berg et al., 2006, 543769). the
differences in REPs reflect differences in dosing regimens, species, endpoints, mechanisms, and
calculation methods. In a quantitative uncertainty analysis one must insure that these are not
double counted.

Reasons for significant differences in REPs for the same congener can be caused
by the use of different dosing regimens (acute vs. subchronic), different endpoints,
species, and mechanisms (e.g., tumor promotion caused by at least two different
mechanisms as for mono-ort/zo-substituted PCBs), as well as different methods
used for calculating REPs. Thus, different methodological approaches used in
different studies clearly provide uncertainties when deriving and comparing REPs.
If future study designs to derive REPs were more standardized and similar, the
variation in REPs when using the same congener, endpoint, and species might be
expected to be smaller (Van den Berg et al., 2006, 543769).

Although the TEFs themselves and the distributions underlying them are based on expert
judgment, it is possible to incorporate these into a quantitative uncertainty analysis; however, it
is not simply a matter of taking the distributions in Figure 6-2 to predict the results, with
uncertainty, of exposure to dioxin4ike compounds. The issues of dependence and double
counting must first be addressed. Inasmuch as the distributions are the result of expert judgment,
this would reasonably involve structured expert judgment as well. (Procedures for this type of
assessment have been developed and applied, and it would entail a significant level of effort.)

6.4.2.4. Uncertainty in Background Feed Exposures in Bioassays

TCDD is not produced intentionally but rather is formed as a byproduct of volcano
eruptions, forest fires, manufacturing of steel and certain chemicals (including some pesticides
and paints), pulp and paper bleaching, exhaust emissions, and incineration. It enters the food
supply primarily via aerial transport and deposition of emissions, and it bioaccumulates in animal
fat. In general, food of animal origin contributes to about 80% of the overall human exposure.
For example, Schecter et al. (1997, 198396) measured dioxins in pooled food samples collected
in 1995 from supermarkets across the United States. Reported as parts per trillion (ppt) toxicity

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equivalences (TEQs), fresh water fish had the highest level (1.43); followed by butter (1.07);
hotdog/bologna (0.54); ocean fish (0.47); cheese (0.40); beef (0.38); eggs (0.34); ice cream
(0.33); chicken (0.32); pork (0.32); milk (0.12); and vegetables, fruits, grains, and legumes
(0.07). More recent exposure studies indicate dietary levels have decreased over time. Values
reported for the early 2000s by Lorber et al. (2009, 543766). in ppt TEQ, are: fish (0.33); beef
(0.12); dairy, other than milk (0.079); eggs (0.06); pork (0.036); poultry (0.018); other meat
(0.058); and milk (0.012).

These results illustrate that a person's dietary intake of dioxins depends on the relative
intake of foods with high or low levels of contamination, and human background levels will vary
accordingly. The same applies to experimental animals in bioassays, although in those cases the
background intake can in principle be controlled. Some of the effects of TCDD and other AhR
agonists in enhancing the early initiation stages of cancers are considered to occur as a result of
prenatal exposures that are not included in the standard National Toxicology Program (NTP)
bioassay protocol (Brown et al., 1998, 051311; Muto et al., 2001, 548713). Further, to enhance
reproducibility and keep statistical fluctuations to a minimum, the standard NTP assays are
deliberately run on groups of animals that are relatively uniform genetically, fed uniform diets,
and have the minimum possible exposures to toxicants other than the agent(s) being tested. This
tends to reduce the potential for observing the consequences of potential interactive effects that
might occur in the diverse human population with its variety of dietary and other exposures to a
wide range of potentially interacting substances and conditions.

A critical question is the extent to which the background exposure influences the
dose-response curve, and how this background should be taken into account. One idea,
articulated in the recent NRC (2009, 194810) report on science and decisions, involves an
"interacting background."68 This can be implemented by computing a virtual dose B which,
according to the selected dose-response model, would explain a chosen fraction of the
background response. If the chosen model for dose 8 is f(8), the model can be adapted to

68"Effects of exposures that add to background processes and background endogenous and exogenous exposures can
lack a threshold if a baseline level of dysfunction occurs without the toxicant and the toxicant adds to or augments
the background process. Thus, even small doses may have a relevant biologic effect. That may be difficult to
measure because of background noise in the system but may be addressed through dose-response modeling
procedures" (NRC, 2009).

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account for an interacting background by writing P(S) = f(5 + B) - f(B). This can alter the
model's behavior at zero dose.

For example, if f(8) = 8n/(8n + EC so'1), the derivative d(f)/d(8) is nSn 'ECso'VfS11 + ECso")2,
which goes to zero as 8—>0, if n > 1. However, replacing 8 with (8 + B) evidently changes the
derivative at zero to nBn 'ECso'VfB'1 + ECso")- This model is not yet estimable from data, as we
have no way of choosing from the available animal data the fraction of background response to
be explained by the model when applied to humans (although judgments could be made if we
had better information about the details of the processes that are involved in causing various
human health effects). However, as a conceptual model, it serves to remind us that the manner
of accounting for background exposures can influence a model's behavior in the low-dose
region. (Note that sensitivity analyses can be done showing the consequences of assuming
different amounts of interacting background within the context of a specific nonlinear model.)

6.4.2.5.	Feasibility of Quantifying the Uncertainties Encountered When Choosing Specific
Studies and Subsets of Data (e.g., Species and Gender)

Species, strain, gender, life stage, and other characteristics of experimental animals are
selected for a given study based on previous knowledge (e.g., of the species sensitivity,
availability of strains having little genetic variation for the endpoints in question, relevance of
the MO A, and degree to which the endpoints are similar for humans). Many other decisions are
made in designing a bioassay study; will the animals be sacrificed at the termination of the study
(if not a lifetime study), or will they be allowed to live out their natural lives? What dosing
regimen should be applied? How will the animals be fed and handled? Although such questions
may engender uncertainty in the minds of the experimenters, and reviewers; such uncertainty is
not amenable for quantitative uncertainty analysis unless and until there are quantitative models,
with parameters estimable from data, that can predict the effect of these choices on the response
function.

6.4.2.6.	Feasibility of Quantifying the Uncertainties Encountered when Choosing Specific
Endpoints for Dose-Response Modeling

Standard experimental protocols guide the selection of exposure/dosing conditions for a
given bioassay, including the amount, delivery vehicle, route, timing, dosing frequency and

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duration, and dose spacing. The goal is to find the dose range where the experimental animals
begin to respond adversely, to help anchor the lower end of the dose-response relationship, and
to avoid multiple experiments in which all or none of the animals respond. A common
recommendation is that the dose levels be chosen such that the increments in probability of
response are roughly equal. Hence, the choice of endpoint, dose spacing, and number of animals
should be made with these factors in mind. Of particular importance is the number of animals at
each dose level in relation to the choice of endpoint and probability of response. Using more
animals at the lower dose levels increases the probability of seeing some animals respond; on the
other hand, it will give higher weight to the low-dose responses in model fitting and uncertainty
quantification. Including many low-dose groups in a study with no expected response can
produce a bias in the event of model mis-specification (see Text Box 6-1). The conclusion with
regard to the feasibility of this quantitative uncertainty analysis echoes that of the previous
paragraph: such uncertainty is not amenable for quantitative analysis unless and until there are
quantitative models, with parameters estimable from data, that predict the effect of these choices
on the response function.

6.4.2.7. Feasibility of Quantifying the Uncertainties Encountered when Choosing a Specific
Dose Metric (Trade-Off between Confidence in Estimated Dose and Relevance of
MOA)

The concept of dose is not straightforward. To review, the Cancer Guidelines provide the
following taxonomy:

•	Exposure is contact of an agent with the outer boundary of an organism.

•	Exposure concentration is the concentration of a chemical in its transport or
carrier medium at the point of contact.

•	Dose is the amount of a substance available for interaction with metabolic
processes or biologically significant receptors after crossing the outer boundary of
an organism.

•	Potential dose is the amount ingested, inhaled, or applied to the skin.

•	Applied dose is the amount of a substance presented to an absorption barrier and
available for absorption (although not necessarily having yet crossed the outer
boundary of the organism).

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Text Box 6-1. Model Mis-Specification and Maximum Likelihood Estimation.

The maximum likelihood estimate (MLE) is widely used in statistics because of its attractive properties: //"the
true model generating the data is from the class whose parameters are being estimated, then under regularity
conditions, the expected MLE converges to the true value, and its variance converges to zero. The caveat against
what is called "mis-specification" is very important and easily overlooked. An illustration can be extracted from
the NTP (2006a) data for female rat tumor incidence of cholangiocarcinoma, representative of the data which
persuaded the NAS committee that the cancer dose response for dioxin was "sublinear."

NTP (2006a) Female Rat Tumor Incidence Data for Cholangiocarcinoma

Blood concentration (ng/kg)

2.56

5.69

9.79

16.57

29.70

Number exposed

48

46

50

49

53

Number responding

0

0

1

4

25

Relative frequency

0

0

0.02

0.08

0.47

The Hill model with MLE in this case has zero slope at zero. The default Linear Low Dose (LLD) model fits a
Hill model to doses with positive responses, but it extrapolates linearly from the lowest observed nonzero response
frequency. Both models have the same two parameters, but the parameter values of the Hill model used in the LLD
model are different from those in Hill model fit to all doses, including doses with zero response. Although the null
responses are expected on the LLD model, the Hill model has greater log likelihood since it gives higher probability
to the null responses (see below).

NTP (2006a) Female Rat Tumor Incidence Data for Cholangiocarcinoma:
Low-Dose Linear and Hill Models

Blood concentration (ng/kg)

2.56

5.69

9.79

16.57

29.70

Number exposed

48

46

50

49

53

Response probability: Linear Low Dose (LLD)

0.005

0.012

0.014

0.09

0.47

Response probability: Hill model

0.00009

0.0017

0.013

0.09

0.47

Probability of cohort null response: LLD

0.77

0.58







Probability of cohort null response: Hill

0.99

0.92







Log Likelihood

LLD

2.46





Hill

2.16





Suppose, for the sake of illustration, that the data were generated with the response probabilities from the LLD
model. The Hill model would be mis-specified in this case, as the model generating the data is not a Hill model.
Because of the small cohort size, the probability of null responses is such that the Hill model has greater likelihood
than the LLD model with probability (based on bootstrapping) about 0.43, even though the latter, by construction,
is the true model. Averaging over many simulated responses from the LLD model, the Hill model underestimates
the response probabilities for doses 2.56 and 5.69 by factors of 7.5 and 2.1 respectively. In the event of such mis-
specification, the bias in the Hill model would be aggravated by including more 50-rat experiments with doses
lower than 2.56.

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•	Absorbed dose is the amount crossing a specific absorption barrier (e.g., the
exchange boundaries of skin, lung, and digestive tract) through uptake processes.

•	Internal dose is a more general term, used without respect to specific absorption
barriers or exchange boundaries. Delivered dose is the amount of the chemical
available for interaction by any particular organ or cell

Due to their greater causal proximity to the affected organs, using the absorbed dose or
internal dose would yield statistically more powerful results and enable more precise predictions
than potential dose. If it is not possible to measure these or they were not measured during the
conduct of the study (as is commonly the case), then other available dose metrics, such as
potential dose or exposure, are used. Due to toxicokinetic variability, different individuals
receiving the same exposure may not have the same absorbed dose. Hence, use of either
exposure or exposure concentration adds variability to the predicted results. The dose metric
should be selected that (1) has the most proximate possible causal relation to the production of an
adverse health endpoint, and (2) can be readily related to the units of (external) exposure that
will be the basis for assessing human exposures.

6.4.2.8. Feasibility of Quantifying the Uncertainties Encountered When Choosing Model
Type and Form

The EPA (2009, 522927)draft white paper on probabilistic methods notes: "There is no
consensus on any one well-accepted general methodology for dealing with model uncertainty,
although there are various examples of efforts to do so." Model uncertainty was introduced in
Section 6.1.3.4. Many statistical techniques are available to evaluate model adequacy or to
choose a "best" model. Although it is tempting to qualify such deliberations as "uncertainty that
a model is true," one must remember that all models, being idealizations, are false. Ultimately,
one is interested in uncertainty with regard to observable phenomena, not with regard to models.
Models are merely tools for describing the phenomena. Nonetheless, the choice of a model
constrains the ways in which uncertainty can be represented, so the question is how to deal with
these constraints. A recent study of uncertainty modeling in dose response (Cooke, 2009,
543763) addresses precisely this issue and provides technical details to frame possible options.

Before exploring exotic approaches to model uncertainty (i.e., those not yet widely used
in dose-response analyses), one feature in the standard statistical treatment of uncertainty must

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be appreciated. Consider a model based on experimental data, typically bioassay data, in which
a certain number of study subjects are exposed to varying doses of a test substance, and in which
the numbers of subjects exhibiting a response are tallied. Values for the parameters in the model
are chosen by the principle of maximal likelihood: those values are chosen which render the data
as likely as possible. According to standard practice, a model is chosen that best fits the data
according to one of the accepted criteria, such as reduced R2, or the Akaike Information
Criterion. There might be many incompatible models that are nearly as good.

One can ask the following: If the experiments on which the model is based were repeated,
sampling the same number of experimental subjects from the distribution posited by the model,
how much could our parameter estimates change? This is described by a joint distribution over
the model's parameters, which captures sampling uncertainty under the assumption that the
model is true. Now, all models are false, and as our sample sizes grow the lack of fit in the
model becomes increasingly apparent. At the same time, the sample fluctuations in parameter
estimates—assuming the model is true—become smaller and smaller. In very large
epidemiological studies, standard statistical methods can produce razor-thin confidence bands in
this way, which fail to capture experts' uncertainty regarding observable phenomena.69

The exotic methods sketched in the beginning of Section 6.4.2 may be viewed as attempts
to deal with this feature. Probabilistic inversion methods were deployed on a large scale in the
joint U.S. NRC-EU uncertainty analyses noted in Section 6.1. Distributions over model
parameters are intended to capture an antecedently defined uncertainty over observable
phenomena predicted by the model. This method was applied in dispersion and deposition
modeling and further environmental transport models (including uptake) for radionuclides. In
most cases, the observable uncertainty was based on structured expert judgment, but it has also
been based on binomial uncertainty in bioassay studies. A potential drawback is that it may not
prove possible to capture the observable uncertainty in this way with a classically best-fitting
model, and new models may be required.

Nonparametric Bayesian methods arose in the biomedical and reliability fields. They
start with a prior distribution over all nondecreasing dose-response functions, and update these

69See, for example, Tuomisto et al. (2008, 548715. Table 6) for a comparison of experts' uncertainty in health
effects of fine particulates with uncertainties derived from sampling uncertainty from large epidemiological studies.
Although the experts generally agree with the studies' central estimates, their uncertainty bands are often much
wider than those surrounding the published estimates.

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with observations from a bioassay. No further assumptions regarding parametric form are
introduced, but the prior distribution remains important for doses outside the range of
observations. Bayesian model averaging starts with a prior distribution over a set of candidate
models, and updates this distribution with bioassay data. The method is flexible and intuitive,
though attenuation of the effect of the prior on the posterior must be verified.

All these approaches represent attempts to capture "extramodel uncertainty," that is,
uncertainty that is not conditional on the truth of the model. This is an active research area, and
improvements in methods for capturing extramodel uncertainty in quantitative uncertainty
analysis are anticipated. A major effort with regard to TCDD dose-response would be indicated
when the strengths and weakness of the exotic methods are well understood.

6.4.2.9. Threshold MOA for Cancer

The NAS committee avers that knowledge of the AhR binding MOA implies that there is
a response threshold for TCDD cancer induction. The differences between individual and
population thresholds are not discussed, but the following two possibilities are distinguishable:

1.	The threshold is the same for each individual; since human variability in AhR binding
affinity is rather large (see Section 5.2.3.3), this entails that the threshold is not affected
by the binding affinity.

2.	The threshold varies across individuals and is related to the individual AhR binding
affinity.

These two positions are different. As shown in Section 5.2.3 it is quite possible that each
individual in a population has a threshold, whereas the population dose-response relation is
linear. Because the NAS committee does not distinguish which of these positions it holds, the
feasibility of quantitative uncertainty analysis is examined here for both.

i.	Quantitative uncertainty analysis concerns a mathematical model. In case (1), this model
would show how the existence of the AhR binding would induce a threshold,
independently of the strength of the binding. Assessing the feasibility of quantitative
uncertainty analysis must await the elaboration of such a model.

ii.	In case (2), it must be shown that the distribution of thresholds, and the dose-response
function above the threshold, are able to induce a population "zero slope at zero dose"
(ZS@Z) model. Recall, the burden of proof is on this (ZS@Z) model. Scoping the

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population variability with regard to AhR-mediated mechanisms in general, and dioxin
sensitivity in particular, is an active area of research. It involves phenotyping human
AhR-mediated responsiveness and relating this to polymorphisms in the human
population. Harper et al. (2002, 198124) report that a 10-fold variation in binding
affinity of AhR for TCDD in human placental tissue did not reveal any polymorphisms,
suggesting that the relation between phenotypical and genotypical variation is tenuous.
Tuomisto et al. (1999, 548717) demonstrate large variations in efficacy in two rat strains
whose binding affinity is similar (Long-Evans, Kd = 3.4, Han/Wistar, Kd = 3.9 (as also
discussed in Connor and Ay 1 ward, 2006, 197632)). and they also show that this variation
is endpoint-specific. The responses in both strains are similar for cytochrome P450
(CYP)l Al induction, but very dissimilar for thymus atrophy, serum bilirubin, and
mortality. Toide et al., (2003, 548792) suggest that common biochemical measures of
EROD activity might be mediated by CYP1B1 and CYP1A2. The differences in serum
bilirubin at doses around 10 |ig/kg are about a factor of 30. Han/Wistar rats seldom die at
this dose, while mortality of Long Evans rats is about 50%. The mechanisms are not
understood.

Although the mass action dose-response model does not have a threshold, it is possible
that certain enzymes block the receptor binding, and until these are overwhelmed, no response
occurs. The availability of such enzymes may vary from individual to individual, and may or
may not covary with the dissociation constant, Kd. Pursuing these lines of research may result in
a convincing demonstration of a population (ZS@Z) model. Such a model would express the
individual threshold in terms of parameters that could be estimated with uncertainty from the
data.

6.4.2.10. Feasibility of Quantifying the Uncertainties Encountered when Selecting the BMR

The NAS committee explicitly requested that the uncertainty attending the choice of a
BMR be quantified. Although selecting relevant alternative values for the BMR may provide
information of interest, it does not constitute a quantitative analysis of uncertainty. The
alternative values must be sampled from some uncertainty distribution. Since this concerns
volitional uncertainty, there is no underlying distribution from which to sample, unless the
choice of BMR is related to some claim about the state of the world.

However, in response to the NAS concerns, this document provides some limited
quantitative comparisons of BMR choices. BMDs, BMDLs and OSFs from the animal cancer
bioassay benchmark dose modeling assuming 1, 5, and 10% extra risk are compared in units of
blood concentrations and human equivalent doses in Tables 5-18 and 5-19, respectively. In

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addition, MLE and upper bound slope factor estimates based on Cheng et al. (2006, 523122) are
presented (see Tables 5-3 and 5-4). For the noncancer effects, key animal study PODs
(ng/kg-day) are shown based on different dose metrics: administered dose, first-order body
burden HED, and blood concentration (see Tables 4-3 and 4-4).

6.5. CONCLUSIONS REGARDING THE FEASIBILITY OF QUANTITATIVE
UNCERTAINTY ANALYSIS

In this section the main conclusions regarding the feasibility of quantitative uncertainty
analysis are summarized in relation to specific suggestions made by the NAS committee (see
Section 6.5.1). Following this, a suggested research agenda for moving forward in this area is
provided (see Section 6.5.2).

6.5.1. Summary of NAS Suggestions and Responses

On page 130 of their report (NAS, 2006, 198441), NAS makes specific suggestions
regarding uncertainty quantification. These are reformatted and presented in italics below.
Following each suggestion, a summary of the discussion in this section is given, with reference
to the section in which it is addressed.

EPA should have addressed quantitatively the following sources of uncertainty:

• Basis for risk quantification:

1.	bioassay data,

2.	occupational cohort data.

Response: (1) Classical statistical methods yield distributions on model parameters
which reflect sample fluctuations, assuming that the model is true. This type of
uncertainty is taken into account in the BMDL. Exotic methods can account for
uncertainty which is not conditional on the truth of a model, at least for bioassay data
(see Section 6.4.2). (2) For epidemiological data, the dose reconstruction often involves
assumptions which may support data driven uncertainty analysis, if sufficient data can
be retrieved. Examples discussed above include back-casted TCDD level, biological
half life, body fat and background (see Section 6.4.2.2). Uncertainty in the choice of
bioassay data sets or choice of occupational cohort data sets is volitional, and is not
quantified by sampling an input distribution. To be amenable for quantitative
uncertainty analysis, the choice must be linked to a statement about the state of the
world (see Section 6.1.1).

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•	Epidemiology data to use:

1.	risk estimate developed with data aggregatedfrom all suitable studies,

2.	risk estimate or estimates developed using each study individually.

•	Factors affecting extrapolation from occupational to general population cohorts,

including differences in baseline health status, age distribution, the healthy worker
survivor effect, and background exposures.

Response: (1) Quantitative uncertainty analysis based on meta-analysis data poses
challenges owing to differences in study protocols. Exotic methods might take us further,
the question is whether the restriction to data driven methods (as opposed to expert
judgment or Bayesian methods) could be maintained (see Sections 6.4.2.2 and 6.4.2.3).
(2) If the general population is characterized by distributions over known confounders
whose coefficients are estimated from the epidemiological studies, then uncertainty over
these coefficients can be extracted with the methods mentioned in Section 6.4.2.1.
Uncertainty due to missing covariates is intractable for data driven uncertainty analysis
(see Section 6.4.2.2).

•	Bioassay data to use:

1.	risk estimate developed with the single data set implying the greatest risk (that is,
single study, tumor site, gender),

2.	risk estimate developed with multiple data sets satisfying an a priori set of
selection criteria.

Response: (1) Uncertainty in choice of data sets is volitional and is not quantified by
sampling an input distribution. To be amenable for quantitative uncertainty analysis the
choice must be linked to a statement about the state of the world (see Section 6.1.1).
(2) The issue here is similar to the meta-analysis addressed in (2.a).

•	Dose-response model:

1.	linear dose response,

2.	nonlinear dose.

Response: (1) When low dose extrapolation is done using a linear model by default, the
uncertainty is volitional. To be amenable for quantitative uncertainty analysis, the choice
must be linked to a statement about the state of the world (see Section 6.1.1). The EDX as
POD for the linear extrapolation can be subjected to quantitative uncertainty analysis, if
based on sufficient bioassay data. (2) With respect to nonlinear dose response, it is
possible that human thresholds exist, and that the distribution of thresholds can be
characterized in the human population. In as much as the mechanisms for this are not yet
understood, there is no quantitative model expressing threshold as a function of
parameters which could be estimated, with uncertainty, from data. This currently limits
the application of uncertainty quantification (see Section 6.4.2.9).

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•	Dose metric:

1.	average daily intake,

2.	area under the blood concentration-time curve,

3.	lifetime average body burden,

4.	peak body burden,

5.	other.

Response: (1-5) The dose metric is chosen to maximize causal proximity to the endpoint,
while maintaining the link to measured exposure (see Section 6.4.2.7). There may be
uncertainty with regard to which metric is optimal. If an inappropriate metric is chosen
in a bioassay study, this would be expressed in noisier responses which would tend to
suppress the dependence of endpoint on dose. A data driven quantitative uncertainty
analysis of dose metric would require a mathematical model expressing endpoints as a
function, inter alia, of dose metric, with parameters estimated from data.

•	Dose metric—biological measure:

1.	free dioxin,

2.	bound dioxin.

Response: (1-2) The issue is whether all TCDD available for AhR binding, or only the
bound TCDD, should be used as a dose metric. Binding affinity is determined by more
factors than genetic polymorphisms and these other factors are poorly understood (see
Section 6.4.2.9). A quantitative uncertainty analysis must await the formulation of a
quantitative model expressing binding affinity in terms of parameters which can be
estimated from data.

•	POD:

1.

ED io,

2.

EDos,

3.

EDoi

Response: (1-3) Uncertainty in choosing a POD is volitional. Uncertainty in the value
of an EDX can be quantified in a data driven manner if sufficient bioassay data is at hand
(see Section 6.4.1.1).

• Value from ED distribution to use:

1.	ED,

2.	lower confidence bound value for the ED (LED),

3.	upper confidence boundfor the ED (UED).

This document is a draft for review purposes only and does not constitute Agency policy.

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39

Response: (1-3) Given that uncertainty on the POD is quantified, a distribution of the
slopes of a linear low dose extrapolation is readily derived, and hence a distribution of a
risk specific dose.

• Where alternative assumptions or methodologies could not be ruled out as implausible or
unreasonable, EPA could have estimated the corresponding risks and reported the
impact of these alternatives on the risk assessment results. The potential impacts offour
sources of uncertainty are discussed below.

1.	The full range ofplausible parameter values for the dose-response functions used
to characterize the dose-response relationship for the three occupational cohort
studies selected by EPA (Becher et al., 1998, 197173; Ott and Zober, 1996,
198483; Steenland et al., 2001, 197433)).

2.	Use of other points of departure, not just the ED0i (or LED0i), to develop a CSF.

3.	Alternative dose-response functional forms as well as goodness of fit of all
models, especially at low doses.

4.	Uncertainty introduced by estimation of occupational exposures.

Response: (1) The study of Steenland et al. (2001, 197433) was selected to illustrate the
possibilities and limitations of quantitative uncertainty analysis for this type of study (see
Section 6.4.2.2). (2) The possibilities for uncertainty quantification with regard to the
POD are discussed in Section 6.4.1.1 and in the POD bullet above. (3) Goodness of fit at
any measured dose is evaluated in standard packages. There may be different models
with comparable goodness of fit at observed doses which differ strongly at doses outside
the measured range. Extra model uncertainty, that is, uncertainty which is not conditional
on the truth of any given model, is addressed by the exotic methods (see Section 6.4.2).
(4) The feasibility of quantifying uncertainty in occupational exposure is study specific.
The example of Steenland et al. (2001, 197433) was discussed in some detail (see
Section 6.4.2.2). In general, the problem is not so much quantifying the exposure
uncertainty, but in quantifying the dependence between the endpoints and the exposure
uncertainty.

6.5.2. How Forward? Beyond RfDs and Cancer Slope Factors to Development of
Predictive Human Dose-Response Functions

Uncertainty quantification is an emerging area in science. There are many examples of
highly vetted and peer-reviewed uncertainty analyses based on structured expert judgment.

Under this process, experts in effect synthesize a wide diversity of information in generating
their subjective probability distributions. Where considerable data exist for an environmental
pollutant, such as for the well-studied TCDD, it is natural to ask whether these extensive data can
be leveraged more directly in uncertainty quantification. This is an area where research could be
focused. The requisite knowledge does not yet exist, but there are promising lines of attack. It is

This document is a draft for review purposes only and does not constitute Agency policy.

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32

33

34

therefore not a question of convening blue-ribbon panels to reveal the proper approach; instead
multiple approaches should be encouraged, to try out new ideas and share experiences.

An important idea that has been pioneered in Europe is to organize bench-test exercises
where different approaches are applied to a common problem. This focuses the discussion on
real issues and builds a community of capable practitioners. Such initiatives have proven much
more productive than simply supporting individual researchers to explore their ideas.

Areas for which bench-test exercises might be appropriate include:

•	Testing "exotic" methods for capturing model uncertainty;

•	Combining bioassay and epidemiological data for uncertainty quantification;

•	Assessing applicability of structured expert judgment, e.g., for low-dose extrapolation;
and

•	Conducting dependence modeling, dependence inference, and dependence elicitation
(such as with regard to TEFs).

Looking beyond compounds for which considerable data exist, there will always be a
need to evaluate new substances. The target will be a simple method that:

1.	Can yield predictions of toxicological indicators with uncertainty via a valid probabilistic
mechanism;

2.	Could evolve from approaches based on similarities (such as a random chemical model)
under which the new substance could be seen as a random sample from a reference
distribution of chemicals considered sufficiently similar, e.g., in terms of structure,
physicochemical properties, and biological activity (potency); and

3.	Is consistent with current risk assessment science and approaches, peer-reviewed and
accepted as EPA policy.

This last feature is important because advancements in risk assessment approaches should
extend logically from current methodology based on data analysis and scientific methods. For
example, the discussion surrounding uncertainty factors suggests that a probabilistically valid
inference system could substantially differ from the current system. Nonetheless, to meld with
current practice, it must initialize on the current system and allow this system to evolve in a
measured fashion. Ideally, methodological changes should be undertaken in a forum where such
issues are being addressed and not within an assessment of a single chemical.

This document is a draft for review purposes only and does not constitute Agency policy.

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1	Additional research topics relevant to dioxin that could further inform health assessments

2	include population variability of biokinetic constants, threshold mechanisms for the mass action

3	model, and low-frequency polymorphisms (e.g., less than 1%). Further data and improved

4	methodologies in these areas, combined with developments illustrated elsewhere in this report,

5	will help reduce uncertainties and strengthen our understanding of potential health implications

6	of environmental contaminants.

This document is a draft for review purposes only and does not constitute Agency policy.

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1

2

Table 6-1. Key sources of uncertainty

Selection of endpoint and of species/strain, gender, life stage, other subject characteristics

-	critical effect

-	sensitivity (e.g., species, life stage)

	- human relevance	

Selection of key study(ies): human data and bioassays (strength, inclusion criteria)

-	epidemiological studies, clinical/case reports (exposure estimate)

-	adequacy of study design, statistical power (exposure term, histopathology)

-	human relevance of bioassays (TK, MO A, endpoint)

	- data uncertainty, confidence in data; database deficiencies	

Use of TK, dosimetry; body burden; species differences, cross-species extrapolation

-	bioavailability, dose dependence

-	half life, life stage, body fat, other compartments, age, other factors

-	body burden (peak, steady state, lifetime average)

-	physiologically-based pharmacokinetic (PBPK) modeling

	- scaling (human equivalents), adjustments (default and nondefault; with TP)	

Selection of dose metric

-	intake (averaging time)

-	background (what place on the dose-response curve)

-	free vs. receptor-bound TCDD

-	tissue-specific concentration

	- lipid-normalized level	

Selection of POD

-	selection (e.g., NOAEL/LOAEL, BMDL, ED0i, 05,10)

-	derivation method (e.g., BMD)

-	choice of model form (e.g., Hill, Weibull)

	- statistical uncertainty at/confidence in POD	

Selection of dose-response model (e.g., biologically based, multistage) and of BMR

-	biological plausibility, MOA

-	model type and form, alternative functional forms

-	range of plausible parameter values

	- goodness of fit, especially at low doses	

Selection of low-dose extrapolation approach

-	linear/nonlinear

	- threshold/nonthreshold	

Human population variability

-	subpopulations (e.g., occupational, general public, sensitive groups)

-	polymorphisms

-	life stage, other features

	- individual vs. population threshold	

Characterization of risk/effect

-	adversity of effect (vs. in normal range of variation and adaptation)

-	uncertainty factors (TK; TD; chemical-specific vs. default; justification)

-	consistency of methods for endpoints with common MOA

-	back-extrapolation from occupational data

	- MOE, RfD; beyond a point estimate for SF	

3	PBPK = physiologically-based pharmacokinetic; SF = slope factor; TD = toxicodynamic;

4	TK = toxicokinetic. (Other acronyms are as defined elsewhere within this section.)

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1	Table 6-2. PODs and amenability for uncertainty quantification

2

POD

Data profile

Choice

Uncertainty quantification

LOAEL

Experimental dose
level from set of
exposure-response data

Choose set of

exposure-response

measurements

No

NOAEL

Experimental dose
level from set of
exposure-response data

Choose set of

exposure-response

measurements

No

BMDL

Estimate from
bioassay data

Choose BMR, choose
dose-response relation

No, the BMDL is a quantile of
an uncertainty distribution
assuming that the
dose-response model is true

EDX

Estimate from set of
exposure-response data

Choose bioassay
experiments to estimate EDX

Yes, if full bioassay data are
available

3

This document is a draft for review purposes only and does not constitute Agency policy.

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1

2

3

4

5

6

7

8

9

10000.0

1000.0

Q

Q 00.0

u

0)

u

8>

CL

1.0

0.1

'

w. ••

i .<#•>.

o i	• 	

:	jsp

o	J	• • •

10.0:

i i i -*171	1—i—rrri rn	r m:

Tvnf

0.1	1,0	10.0 100.0 1000.0 10000.0 100000.0

Back-Extrapolated TCDD

Figure 6-1. Back-casted vs. predicted TCDD serum levels for a worker
subset.

Source: Steenland et al. (2001, 197433).

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LEGEND

12378-PeCDD
123478-HxCDD
123789-HxCDD
1234678-HpCDD
OCDD
TCDF
12378-PeCDF
23478-PeCDF
123478-HxCDF
123678-HxCDF
234678-HxCDF
OCDF

h

H

10th 25th: 50th 75th 90th

who1996tef

3]—I

b

I	HE

I

i—rn—
i>+

3—I'

0.00001

0.0001	0.001	0.01

Relative Potencies (REPs)

0.1

PCB-77
q PCB-126

a

PCB-169

PCB-105
PCB-114
PCB-118
PCB-123
PCB-156
PCB-157
PCB-189

i—m—i

:—i

i	c

KB"

O

i	cn:

LEGEND

4-CTH

HT^H

10th 25th; 50th 75th 90th

who1998tef

0.0000001 0.000001 0.00001	0.0001	0.001	0.01	0.1	1

Relative Potencies (REPs)

Figure 6-2. Distribution of in vivo unweighted REP values in the 2004
database.

Source: Van den Berg et al. (2006, 543769). reprinted with permission from Haws

etal. (2006,198416)-

This document is a draft for review purposes only and does not constitute Agency policy.

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3

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This document is a draft for review purposes only and does not constitute Agency policy.

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2	constitutively active dioxin/aryl hydrocarbon receptor induces stomach tumors. PNAS, 99: 9990-9995. 197101

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17	moderately to highly exposed adults from Seveso, Italy, and Vienna, Austria, and impact on dose estimates for the

18	NIOSH cohort. JExpo Anal Environ Epidemiol, 15: 51-65. 197114

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25	Aylward LL; Hays SM; Karch NJ; Paustenbach DJ (1997). Relative susceptibility of animals and humans to the

26	cancer hazard posed by 2,3,7,8-tetrachlorodibenzo-p-dioxin using internal measures of dose. Environ Sci Tech, 31:

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28	Baccarelli A; Giacomini SM; Corbetta C; Landi MT; Bonzini M; Consonni D; Grillo P; Patterson DG; Pesatori AC;

29	Bertazzi PA (2008). Neonatal thyroid function in Seveso 25 years after maternal exposure to dioxin. PLoS Med, 5:

30	el61. 197059

31	Baccarelli A; Hirt C; Pesatori AC; Consonni D; Patterson DG Jr; Bertazzi PA; Dolken G; Landi MT (2006). t(14; 18)

32	translocations in lymphocytes of healthy dioxin-exposed individuals from Seveso, Italy. Carcinogenesis, 27: 2001-

33	2007.197036

34	Baccarelli A; Mocarelli P; Patterson DG Jr; Bonzini M; Pesatori AC; Caporaso N; Landi MT (2002). Immunologic
3 5	effects of dioxin: new results from Seveso and comparison with other studies. Environ Health Perspect, 110:1169-

36	1173.197062

37	Baccarelli A; Pesatori AC; Consonni D; Mocarelli P; Patterson DG Jr; Caporaso NE; Bertazzi PA; Landi MT
3 8	(2005). Health status and plasma dioxin levels in chloracne cases 20 years after the Seveso, Italy accident. Br J
39	Dermatol, 152: 459-465. 197053

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1	Baccarelli A; Pesatori AC; Masten SA; Patterson DG Jr; Needham LL; Mocarelli P; Caporaso NE; Consonni D;

2	Grassman JA; Bertazzi PA; Landi MT (2004). Aryl-hydrocarbon receptor-dependent pathway and toxic effects of

3	TCDD in humans: a population-based study in Seveso, Italy. Toxicol Lett, 149: 287-293. 197045

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8	Banks YB; Brewster DW; Birnbaum LS (1990). Age-related changes in dermal absorption of 2,3,7,8-

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26	initiated mouse lung tumors following single or multiple low dose exposure to 2,3,7,8- tetrachlorodibenzo-p-dioxin.

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40	effects of dioxin exposure: a 20-year mortality study. Am J Epidemiol, 153: 1031-1044. 197005

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1	Bertazzi PA; Zocchetti C; Guercilena S; Consonni D; Tironi A; Landi MT; Pesatori AC (1997). Dioxin exposure

2	and cancer risk: A 15-year mortality study after the "Seveso accident". Epidemiology, 8: 646-652. 197097

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11	Bock KW; Gschaidmeier H; Heel H; Lehmkoster T; Miinzel PA; Raschko F; Bock-Hennig B (1998). AH receptor-

12	controlled transcriptional regulation and function of rat and human UDP-glucuronosyltransferase isoforms. Adv

13	Enzyme Regul, 38: 207-222. 548752

14	Bodner K; Collins J; Bloemen L; Carson M (2003). Cancer risk for chemical workers exposed to 2,3,7,8-

15	tetrachlorodibenzo-p-dioxin. Occup Environ Med, 60: 672-675. 197135

16	Bond GG; McLaren EA; Brenner FE; Cook RR (1989). Incidence of chloracne among chemical workers potentially

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40	and 2,2-bis(p-chlorophenyl)-l,l,l-trichloroethane. J Biol Chem, 246: 5189-5198. 543775

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1	Goodman DG; Sauer RM (1992). Hepatotoxicity and carcinogenicity in female Sprague-Dawley rats treated with

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DRAFT

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May 2010
External Review Draft

APPENDIX A
Dioxin Workshop Report

NOTICE

THIS DOCUMENT IS AN EXTERNAL REVIEW DRAFT. It has not been formally released
by the U.S. Environmental Protection Agency and should not at this stage be construed to
represent Agency policy. It is being circulated for comment on its technical accuracy and policy
implications.

National Center for Environmental Assessment
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, OH


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EPA/600/R-09/027
May 2009

Summary of U.S. EPA
Dioxin Workshop

February 18-20, 2009

Cincinnati, Ohio

National Center for Environmental Assessment
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, OH 45268


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DISCLAIMER

This document summarizes the discussions presented at the Dioxin Workshop in
February 2009, in Cincinnati, OH, as documented by the Session Co-Chairs. This document is
not all inclusive or binding. Conclusions and recommendations to the U.S. EPA may not
represent full consensus. The views expressed in this document are those of the Dioxin
Workshop Panelists and do not necessarily reflect the views and policies of the U.S.
Environmental Protection Agency. Mention of trade names or commercial products does not
constitute endorsement or recommendation for use.

Preferred Citation:

U.S. Environmental Protection Agency (U.S. EPA). (2009) Summary of U.S. EPA Dioxin Workshop:

February 18-20, 2009. U.S. Environmental Protection Agency, National Center for Environmental Assessment,
Cincinnati, OH. EPA/600/R-09/027.

This document is a draft for review purposes only and does not constitute Agency policy.

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TABLE OF CONTENTS

DIOXIN WORKSHOP TEAM	A-iv

ACKNOWLEDGMENTS	A-iv

INTRODUCTION	A-l

REFERENCES	A-2

SCIENTIFIC WORKSHOP TO INFORM THE TECHNICAL WORK PLAN FOR U.S.

EPA'S RESPONSE TO NAS COMMENTS ON THE HEALTH EFFECTS OF
DIOXIN PRESENTED IN U.S. EPA'S DIOXIN REASSESSMENT	A-3

SESSION 1: QUANTITATIVE DOSE-RESPONSE MODELING ISSUES	A-3

SESSION 2: IMMUNOTOXICITY	A-6

SESSION 3 A: DOSE-RESPONSE FOR NEUROTOXICITY AND

NONREPRODUCTIVE ENDOCRINE EFFECTS	A-8

SESSION 3B: DOSE-RESPONSE FOR CARDIOVASCULAR TOXICITY

AND HEPATOTOXICITY	A-l 1

SESSION 4A: DOSE-RESPONSE FOR CANCER	A-13

SESSION 4B: DOSE-RESPONSE FOR

REPRODUCTIVE/DEVELOPMENTAL TOXICITY	A-16

SESSION 5: QUANTITATIVE UNCERTAINTY ANALYSIS OF DOSE-

RESPONSE	A-20

APPENDIX A: 2009 U.S. EPA DIOXIN WORKSHOP AGENDA	A-24

APPENDIX B: 2009 U.S. EPA DIOXIN WORKSHOP QUESTIONS TO GUIDE

PANEL DISCUSSIONS	A-31

APPENDIX C: 2009 U.S. EPA DIOXIN WORKSHOP DRAFT SELECTION
CRITERIA TO IDENTIFY KEY IN VIVO MAMMALIAN STUDIES THAT
INFORM DOSE-RESPONSE MODELING FOR

2,3,7,8-TETRACHLORODIBENZO-p-DIOXIN (TCDD)	A-34

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DIOXIN WORKSHOP TEAM

The Dioxin Workshop Team, under the leadership of Peter W. Preuss, Director, NCEA,
comprised the following members:

National Center for Environmental Assessment, Office of Research and Development,
U.S. Environmental Protection Agency, Cincinnati, OH 45268
Belinda S. Hawkins
Janet Hess-Wilson
Glenn Rice
Jeff Swartout
Linda K. Teuschler
Bette Zwayer

Argonne National Laboratory, Argonne, IL 60439
Maryka H. Bhattacharyya
Andrew Davidson
Mary E. Finster
Margaret M. MacDonell
David P. Peterson

ACKNOWLEDGMENTS

The Track Group, Alexandria, VA 22312
Kara Hennigan
Alan Minton
Brandy Quinn

ECFlex, Inc., Fairborn, OH 45324
Dan Heing
Heidi Glick
Amy Prues
Lana Wood

IntelliTech Systems, Inc., Fairborn, OH 45324
Cris Broyles
Luella Kessler
Stacey Lewis
Linda Tackett

This document is a draft for review purposes only and does not constitute Agency policy.

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INTRODUCTION

This document provides a summary of the Scientific Workshop to Inform EPA's
Response to National Academy of Science Comments on the Health Effects of Dioxin in EPA's
2003 Dioxin Reassessment. The U.S. Environmental Protection Agency (U.S. EPA) and
Argonne National Laboratories (ANL), through an inter-Agency agreement with the U.S.
Department of Energy, convened this scientific workshop ("Dioxin Workshop") on February
18-20, 2009, in Cincinnati, Ohio. The goals of the Dioxin Workshop were to identify and
address issues related to the dose-response assessment of 2,3,7,8-tetrachlorodibenzo-p-dioxin
(TCDD). This report summarizes the discussions and conclusions from this workshop.
Previously, at the request of the U.S. EPA, the National Academy of Sciences (NAS) prepared a
report, Health Risks from Dioxin and Related Compounds: Evaluation of the EPA Reassessment
(NAS, 2006), which made a number of recommendations to improve the U.S. EPA's risk
assessment for TCDD (U.S. EPA, 2003). The 3-day Dioxin Workshop was convened
specifically to ensure that the U.S. EPA's response to the NAS recommendations focuses on the
key issues and reflects the most meaningful science.

The Dioxin Workshop included seven scientific sessions:

(1)	Session 1:

(2)	Session 2:

(3)	Session 3A

(4)	Session 3B

(5)	Session 4A

(6)	Session 4B

(7)	Session 5:

Quantitative Dose-Response Modeling Issues
Immunotoxicity

Dose-Response for Neurotoxicity and Nonreproductive Endocrine Effects
Dose-Response for Cardiovascular Toxicity and Hepatotoxicity
Dose-Response for Cancer

Dose-Response for Reproductive/Developmental Toxicity
Quantitative Uncertainty Analysis of Dose-Response

During each session, the U.S. EPA asked a panel of expert scientists to:

•	identify and discuss the technical challenges involved in addressing the key NAS
comments on the TCDD dose-response assessment in the U.S. EPA Reassessment
(U.S. EPA, 2003);

•	discuss approaches for addressing the key NAS comments; and

•	identify important published, independently peer-reviewed literature, particularly studies
describing epidemiologic and in vivo mammalian bioassays, which are expected to be
most useful for informing the U.S. EPA's response.

The sessions were followed by open comment periods during which members of the
audience were invited to address the Panels. At the conclusion of the open comment periods, the
Panel Co-Chairs were asked to summarize and present the results of the panel discussions. The
summaries could include minority opinions stated by panelists. The main points derived from
the session summaries were used to prepare this document. Additionally, this document includes
a list of the session panelists and their affiliations and three appendices. Appendix A presents
the Dioxin Workshop Agenda. Appendix B identifies the charge questions presented to the
Panel. Appendix C describes draft study selection criteria proposed by the Dioxin Workshop
Team for consideration by the workshop panelists.

This document is a draft for review purposes only and does not constitute Agency policy.

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REFERENCES

NAS (National Academy of Sciences). 2006. Health Risks from Dioxin and Related
Compounds: Evaluation of the EPA Reassessment. National Academies Press, Washington, DC
(July). Available at http://www.nap.edu/catalog.php7record id=l 1688.

U.S. EPA (U.S. Environmental Protection Agency). 2003. Exposure and Human Health
Reassessment of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) and Related Compounds. NAS
review draft, Volumes 1-3 (EPA/600/P-00/001Cb, Volume 1). U.S. Environmental Protection
Agency, National Center for Environmental Assessment, Washington, DC (December).
Available at http://www.epa.gov/nceawwwl/pdfs/dioxin/nas-review/.

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SCIENTIFIC WORKSHOP TO INFORM I II I TECHNICAL WORK PLAN FOR U.S.
EPA'S RESPONSE TO NAS COMMENTS ON THE HEALTH EFFECTS OF DIOXIN
PRESENTED IN U.S. EPA'S DIOXIN REASSESSMENT

Dioxin Workshop Co-Chairs: Peter W. Preuss and Glenn Rice

The Dioxin Workshop session summaries were prepared by the session panel Co-Chairs
with input from the panelists, as requested by the U.S. EPA prior to the workshop. The Co-
Chairs subsequently presented these summaries to all of the workshop participants during
designated periods at the workshop. In these summaries, the U.S. EPA asked that the Co-Chairs
summarize the key issues from the panel discussions. Because the sessions were not designed to
achieve consensus among the panelists, the summaries do not necessarily represent consensus
opinions; rather, they reflect the essence of the panel discussions. Some of the specific points
may represent the views of multiple panelists, while others only the views of a single panelist.
Prior to the summarizations, there were opportunities for public comments on the discussion
topics. Some Co-Chairs met with their sessions' panelists after their sessions ended to develop
these summaries, while others developed reports based on their personal notes. Because Session
5 was the last session of the workshop—with little time provided to develop the summary—the
Co-Chairs circulated a draft for comment by the Session 5 panelists after the workshop, prior to
finalizing the session summary. The U.S. EPA collected the session summaries and then
prepared this document. A draft of this document was distributed to all of the session Co-Chairs
to provide them with a final opportunity to comment and make revisions. Finally, it should be
noted that U.S. EPA was not prescriptive to the session Co-Chairs with respect to the format of
the presentation materials and provided no specific instructions, resulting in unique formats
among the session summaries.

SESSION 1: QUANTITATIVE DOSE-RESPONSE MODELING ISSUES

This session discussed the general dose-response modeling issues related to TCDD.

Many of these issues were highlighted by NAS (2006). There was a general introductory
presentation on TCDD kinetics, including information and uncertainties pertaining to the
conversion of administered doses in animals to human body burden (BB) and additivity to
background issues. This presentation was followed by a Panel discussion on the state of the
science regarding dioxin dose-response modeling issues.

Session 1 Panelists (Session Co-Chairs are identified by asterisk)

•	Bruce Allen, Bruce Allen Consulting

•	Lesa Aylward, Summit Toxicology

•	Roger Cooke, Resources for the Future

•	Kenny Crump, Louisiana Tech University

•	MikeDeVito, U.S. EPA

•	Dale Hattis, Clark University

•	Rick Hertzberg, Biomath Consulting

•	Rob McDowell, U.S. Department of Agriculture

•	Jim Olson, State University of New York, University at Buffalo

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•	*Lorenz Rhomberg, Gradient

•	Woody Setzer, U.S. EPA

•	*Jeff Swartout, U.S. EPA

Please note that the use of the term "concluded" or "recommended" in this summary does not mean that a consensus
was reached. Session Summaries were written from the material prepared by the non-EPA/ANL Co-Chair and
represent a synopsis of the panel discussions.

Key Study Selection Criteria

The Panel discussed the advantages and disadvantages of using key study criteria
(Appendix C). They concluded that a priori criteria foster transparency and consistency, and
could deflect a posteriori criticism. However, the Panel also acknowledged that having a priori
criteria could introduce the potential for excluding useful data. Although the key study criteria
provided by the U.S. EPA listed studies using TCDD only as a criterion, the Panel posed the
possibility of using closely related dioxin-like compounds (DLCs) as surrogates for TCDD. The
criterion for use of data from mammalian studies only was one criterion that received generalized
support due to the lack of extrapolation protocols for nonmammalian species. The Panel also
discussed the specific exposure-duration criterion and asked if there should be a preference for
longer-term rather than acute studies. The Panel made three suggestions to modify U.S. EPA's
key study selection criteria:

(1)	Define more relevant exposure-level (i.e., dose) cut points using tissue concentrations.

(2)	Reword statistical criteria to include do-it-yourself analysis.

(3)	Reword the response criteria to clarify "outside of normal range."

Dose Metrics

The Panel discussed the relative merits of various measures of dose for modeling TCDD
dose response. One general conclusion was that tissue concentration (TC) is the preferred
metric, especially lipid-adjusted TC, because this measure more closely approximates exposures
close to the target tissue when compared to administered doses. However, the Panel
acknowledged that these data are often unavailable. They further noted that BB, which is
defined as the concentration of TCDD in the body (ng/kg body weight) (U.S. EPA, 2003), might
be useful as a surrogate for TC provided the two measures were proportional.

The Panel suggested that a linear approach to BB estimation, which was utilized by
U.S. EPA (2003), is too simplistic because this approach does not take into account toxicokinetic
issues related to TCDD—e.g., sequestration in the liver and fat, age-dependent elimination, and
changing elimination rates over time. The Panel recommended the use of kinetic/mechanistic
modeling to the extent possible to quantify tissue-based metrics.

The Panel raised the issue of whether the preferred dose metric would be different for
different endpoints and exposure durations. This led to the Panel's comment that the peak
exposure might be a more important metric than average BB for variable exposure scenarios.
Given this discussion about different exposure durations being relevant to a specific endpoint,
the Panel suggested that the U.S. EPA also consider peak measures in dose-response modeling.

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The last point raised in this part of the discussion centered on the possibility of dose
errors in experimental studies. The Panel highlighted the need for the U.S. EPA to consider dose
error (i.e., uncertainty in the x-axis of the dose-response curve) when using dose surrogates.

Dose-Response Modeling of Mammalian Bioassays

The Panel considered several issues related to dose-response modeling of mammalian
bioassay data for TCDD: supralinearity and incomplete response data ("anchoring"), defining the
benchmark response (BMR) level with respect to establishing the point of departure (POD), and
the use of threshold modeling—as further explained below.

The Panel discussed the specific issues of supralinearity and anchoring raised by the
U.S. EPA with respect to modeling noncancer endpoints. The panel recognized that, for many of
the most sensitive endpoints, the response at the lowest dose is high (e.g., quantal responses
above 25% and continuous endpoints differ substantially from the mean, often implying 100%
incidence in the treated animals). This lack of response anchoring at the low end of the dose-
response curve (near the BMR) results in the higher responses determining the shape of the
curve.

The Panel asked whether new tools might be needed or whether the current tools could be
applied differently. In the context of developing new tools, the Panel emphasized the need for
collaboration between biologists and mathematicians. When discussing application, the Panel
suggested that the problem with supralinearity might be overcome by simply dropping the
requirement for using the lower bound on the Benchmark Dose. In addition, the Panel posed
several more approaches for further consideration in dose-response modeling by the U.S. EPA:

(1)	Combine similar data sets to fill in data gaps.

(2)	Use mechanistic approaches to model the data gaps.

(3)	Dichotomize continuous data.

Finally, the Panel acknowledged that, in certain situations, there simply may not be enough
information to provide meaningful answers.

The Panel discussed the BMR level for establishing a POD in the context of deriving a
Reference Dose (RfD). The Panel generally agreed that, while the effective dose level (ED0i)
used in the 2003 Reassessment may be useful for comparative analysis across endpoints, the
EDoi estimates developed for all endpoints considered in the Reassessment were not appropriate
for deriving an RfD because they were not based on the effect's adversity. The panel noted that
EDoi also is much lower than typical EPA BMR levels. The Panel recommended that the U.S.
EPA work to define endpoint-specific BMRs based on the consideration of adversity. Given that
the same uncertainty factor framework is applied to all PODs, the Panel emphasized the need for
consistency in BMRs; numerical consistency is needed for quantal BMRs and consistency in the
choice of biological relevance should be applied for continuous BMRs.

The Panel generally discouraged threshold modeling by stating that thresholds are very
difficult to pin down and suggested that the lower bound may always be zero.

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Dose-Response Modeling of Epidemiological Studies

The Panel noted that many studies have been published with measured concentrations of
TCDD that could be used for dose reconstruction. In this discussion, the Panel acknowledged
that use of these data would entail dealing with toxicity equivalence (TEQ) issues and
pharmacokinetic (PK) modeling. Pertaining to the use of these data for quantitative risk
assessment by the U.S. EPA, the Panel posed the question, "At what point does indirect or
confounded human data supersede controlled animal bioassay data?", or alternatively, "How
much human data uncertainty can we tolerate?" The Panel suggested, at the least, that the
epidemiologic data could be used to "ground-truth" the animal bioassay modeling results.

Supporting Information

The Panel acknowledged that Ah receptor (AhR) binding affinities are not necessarily
tied to endpoint sensitivity, but they reiterated the need to consider mechanistic modeling to aid
in developing appropriate dose metrics or filling in data gaps in the existing dose-response data.

References

NAS (National Academy of Sciences). 2006. Health Risks from Dioxin and Related
Compounds: Evaluation of the EPA Reassessment. National Academies Press, Washington, DC
(July). Available at http://www.nap.edu/catalog.php?record id=l 1688.

U.S. EPA (U.S. Environmental Protection Agency). 2003. Exposure and Human Health
Reassessment of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) and Related Compounds. NAS
Review Draft (EPA/600/P-00/001Cb). U.S. Environmental Protection Agency, National Center
for Environmental Assessment, Washington, DC. Available at
http://www.epa.gov/nceawwwl/pdfs/dioxin/nas-review/.

SESSION 2: IMMUNOTOXICITY

The U.S. EPA plans to consider development of a quantitative dose-response assessment
for the immunologic effects associated with TCDD exposure. Such an assessment would be
based on information in U.S. EPA (2003), NAS (2006) and key studies identified in this
workshop. The purpose of this session was to identify and discuss key issues pertaining to dose-
response assessment for dioxin-induced immunologic effects.

Session 2 Panelists (Session Co-Chairs are identified by asterisk)

•	Roger Cooke, Resources for the Future

•	Rob Goble, Clark University

•	*Belinda Hawkins, U.S. EPA

•	Nancy Kerkvliet, Oregon State University

•	Manolis Kogevinas, Centre for Research in Environmental Epidemiology

•	Robert Luebke, U.S. EPA

•	Paolo Mocarelli, University of Milan

•	* Allen Silverstone, State University of New York, Upstate Medical University

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•	Courtney Sulentic, Wright State University

•	Nigel Walker, National Institute of Environmental Health Sciences

Please note that the use of the term "concluded" or "recommended" in this summary does not mean that a consensus
was reached. Session Summaries were written from the material prepared by the non-EPA/ANL Co-Chair and
represent a synopsis of the panel discussions.

Key Study Selection Criteria

The Panel first addressed the Key Study Selection Criteria proposed by the U.S. EPA
(Appendix C). The Panel raised the issue that the key study criteria do not apply to most studies
designed to investigate immunotoxicity, including those used to calculate ED0iS (U.S. EPA,
2003). The Panel observed that most dioxin immunotoxicity studies are relatively high dose
(>200 ng/kg-d) acute studies and/or use parenteral rather than oral administration.

The Panel discussed several studies often considered important for assessing the
immunotoxic effects of TCDD exposure. The Oughton et al. (1995) mouse bioassay was
discussed and, although the study does meet the proposed criteria, it could not be considered a
key study; specifically, the Panel contended that since there were no functional alterations
observed or measured in this bioassay, the changes in cellular phenotypes are only "suggestive"
of immune alterations and cannot be regarded as having immunopathologic significance.

The Panel discussed two additional studies for further consideration by the U.S. EPA:

•	Baccarelli et al. (2002). The Panel discussed this as a potentially key human
epidemiological study that should be reviewed and considered further by the U.S. EPA.
It measured the level of IgG, demonstrating a significant decline relative to dioxin body
burdens.

•	Smialowicz et al. (2008). The Panel noted that this study identified the antibody response
to sheep red blood cells (SRBCs) as the critical effect, labeling this protocol as a
functional assay. The Panel stated that if modeled, the U.S. EPA could calculate the
BMR for this endpoint as 1 standard deviation from the control mean.

References

Baccarelli, A., P. Mocarelli, D.G. Patterson et al. 2002. Immunologic effects of dioxin: New
results from Seveso and comparison with other studies. Environ. Health Perspect.
110(12): 1169-1173.

NAS (National Academy of Sciences). 2006. Health Risks from Dioxin and Related
Compounds: Evaluation of the EPA Reassessment. National Academies Press, Washington, DC
(July). Available at http://www.nap.edu/catalog.php7record id=l 1688.

Oughton, J.A., C.B. Pereira, G.K. Dekrey, J.M. Collier, A.A. Frank and N.I. Kerkvliet. 1995.
Phenotypic analysis of spleen, thymus, and peripheral blood cells in aged C57BI/6 mice
following long-term exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin. Toxicol. Sci. 25(l):60-69.

This document is a draft for review purposes only and does not constitute Agency policy.

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Smialowicz, R.J., M.J. DeVito, W.C. Williams and L.S. Birnbaum. 2008. Relative potency
based on hepatic enzyme induction predicts immunosuppressive effects of a mixture of
PCDDS/PCDFS and PCBS. Toxicol. Appl. Pharmacol. 227(3):477-484.

U.S. EPA (U.S. Environmental Protection Agency). 2003. Exposure and Human Health
Reassessment of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) and Related Compounds. NAS
Review Draft (EPA/600/P-00/001Cb). U.S. Environmental Protection Agency, National Center
for Environmental Assessment, Washington, DC. Available at
http://www.epa.gov/nceawwwl/pdfs/dioxin/nas-review/.

SESSION 3A: DOSE-RESPONSE FOR NEUROTOXICITY AND NONREPRODUCTIVE
ENDOCRINE EFFECTS

The U.S. EPA plans to consider development of a quantitative dose-response assessment
for neurological and/or nonreproductive endocrine effects associated with TCDD exposure.

Such an assessment would be based on information in U.S. EPA (2003), NAS (2006) and key
studies identified in this workshop. The purpose of this session was to identify and discuss key
issues pertaining to dose-response assessment for dioxin-induced neurological and/or
nonreproductive endocrine effects.

Session 3A Panelists (Session Co-Chairs are identified by asterisk)

•	*Maryka Bhattacharyya, Argonne National Laboratory

•	Mike DeVito, U.S. EPA

•	Mary Gilbert, U.S. EPA

•	Rob Goble, Clark University

•	Nancy Kerkvliet, Oregon State University

•	Fumio Matsumura, University of California-Davis

•	Paolo Mocarelli, University of Milan

•	Chris Portier, National Institute of Environmental Health Sciences

•	Lorenz Rhomberg, Gradient

•	Allen Silverstone, State University of New York, Upstate Medical University

•	Marie Sweeney, National Institute of Occupational Safety and Health

•	*Bernie Weiss, University of Rochester

Please note that the use of the term "concluded" or "recommended" in this summary does not mean that a consensus
was reached. Session Summaries were written from the material prepared by the non-EPA/ANL Co-Chair and
represent a synopsis of the panel discussions.

What Are the Key Questions Regarding These Endpoints?

The Panel used the following question to initiate discussion: "Are there identifiable
indices of neurotoxicity and nonreproductive endocrine effects in animal studies and human
populations? " Under this discussion topic, the Panel discussed three endpoints: neurotoxicity
(with focus on developmental exposures), thyroid dysfunction (e.g., thyroid hormone deficits),
and diabetes. The Panel also addressed the relevance of windows of vulnerability to each

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endpoint. The Panel acknowledged that, in some cases, the window of exposure may precede the
window of expression of toxicity.

Epidemiological Study Selection

Developmental Neurotoxicity

The Panel recognized that an unusual feature for this endpoint is that there are sufficient
human data for dose-response modeling (e.g., Dutch children [Huisman et al., 1995; Patandin et
al., 1999] and U.S. children [Jacobson and Jacobson, 1996]) and there is an internal dose metric
(serum concentrations). Additionally, the Panel discussed recent studies that address this
endpoint in humans (from Japan [reference not provided] and Holland [e.g., Koopman-Esseboom
et al., 1996; Vreugdenhil et al., 2002]). For continued investigation into this endpoint, the Panel
raised two issues to the U.S. EPA:

•	Conduct an evaluation of whether a modeled effect can be attributed to TCDD and not
some other persistent organic pollutant (POP), although the Panel recognized that it is
unlikely U.S. EPA will be able to distinguish among these exposures because other POPs
are intrinsic confounders in the Dutch study.

•	Allow animal data to inform the dose-response modeling of epidemiological data.

Thyroid Dysfunction

The Panel identified the availability of human data for this endpoint (e.g., Calvert et al.,
1999; Koopman-Esseboom et al., 1994). Much of the thyroid dysfunction literature has been
published since the 2003 Reassessment (e.g., Wang et al., 2005; Baccarelli et al., 2008). The
Panel also noted the availability of an internal dose metric (serum concentrations). Additionally,
the Panel discussed the mechanistic studies in animals that link TCDD to thyroid dysfunction.
For continued investigation into this endpoint, the Panel raised three issues for the U.S. EPA to
consider:

•	Consider the newly available human data since the Reassessment.

•	Investigate and clarify of the role of TCDD-induced thyroid dysfunction in
developmental neurotoxicity.

•	Evaluate and determine whether an effect can be attributed to TCDD or other
contaminants.

Diabetes

The Panel discussed that data suggest that diabetes incidence in those under 55 years old
may be associated with exposure to PCBs. They acknowledged that whether this is a dioxin-like
compound (DLC) mediated effect or whether other POPs are responsible is still undetermined.
The Panel also acknowledged that no animal model exists for the investigation of xenobiotic-
induced diabetes, and that separating the injury dose level from the current body burdens would
depend on good pharmacokinetics in humans. For continued investigation into this endpoint, the
Panel listed two issues for the U.S. EPA to consider:

•	Results from the Anniston study and the Great Lakes Fishermen study (references not
provided) should be examined for dose metrics (both studies examine human PCB
exposures).

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• Changes of adipose tissue status need to be considered, given that dieting can cause
release of lipid-soluble contaminants.

References

Baccarelli, A., S.M. Giacomini, C. Corbetta et al. 2008. Neonatal thyroid function in Seveso 25
years after maternal exposure to dDioxin. PLoS Med. 5(7):el61.
doi: 10.1371/journal.pmed. 0050161.

Calvert, G.M., M.H. Sweeney, J. Deddens and D.K. Wall. 1999. Evaluation of diabetes
mellitus, serum glucose, and thyroid function among United States workers exposed to
2,3,7,8-tetrachlorodibenzo-p-dioxin. Occ. Env. Med. 56:270-276.

Huisman, M., C. Koopman-Esseboom, V. Fidler et al. 1995. Perinatal exposure to
polychlorinated biphenyls and dioxins and its effect on neonatal neurological development.

Early Hum. Devel. 41(2): 111-127.

Jacobson, J.L. and S.W. Jacobson. 1996. Intellectual impairment in children exposed to
polychlorinated biphenyls in utero. N. Engl. J. Med. 335:783-789.

Koopman-Esseboom, C., N. Weisglas-Kuperus, M.A.J. deRidder, C.G. Van derPaauw,
L.G.M.Th. Tuinstra and P.J.J. Sauer. 1996. Effects of polychlorinated biphenyl/dioxin exposure
and feeding type on infants' mental and psychomotor development. J. Pediatr. 97(5):700-706.

Koopman-Esseboom, C., D.-C. Morse, N. Weisglas-Kuperus et al. 1994. Effects of dioxins and
polychlorinated biphenyls on thyroid hormone status of pregnant women and their infants.
Pediatr. Res. 36:468-473.

Patandin, S., C.I. Lanting, P.G.H. Mulder, E.R. Boersma, P.J.J. Sauer and N. Weisglas-Kuperus.
1999. Effects of environmental exposure to polychlorinated biphenyls and dioxins on cognitive
abilities in Dutch children at 42 months of age. J. Pediatr. 134:33-41.

NAS (National Academy of Sciences). 2006. Health Risks from Dioxin and Related
Compounds: Evaluation of the EPA Reassessment. National Academies Press, Washington, DC
(July). Available at http://www.nap.edu/catalog.php7record id=l 1688.

U.S. EPA (U.S. Environmental Protection Agency). 2003. Exposure and Human Health
Reassessment of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) and Related Compounds. NAS
Review Draft (EPA/600/P-00/001Cb). U.S. Environmental Protection Agency, National Center
for Environmental Assessment, Washington, DC. Available at
http://www.epa.gov/nceawwwl/pdfs/dioxin/nas-review/.

Vreugdenhil, H.J., C.I. Lanting, P.G. Mulder, E.R. Boersma and N. Weisglas-Kuperus. 2002.
Effects of prenatal PCB and dioxin background exposure on cognitive and motor abilities in
Dutch children at school age. J. Pediatr. 140:48-56.

This document is a draft for review purposes only and does not constitute Agency policy.

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Wang S.L., P.H. Su, S.B. Jong, Y.L. Guo, W.L. Chou and O. Papke. 2005. In utero exposure to
dioxins and polychlorinated biphenyls and its relations to thyroid function and growth hormone
in newborns. Environ. Health Perspect. 113:1645-1650.

SESSION 3B: DOSE-RESPONSE FOR CARDIOVASCULAR TOXICITY AND
HEPATOTOXICITY

The U.S. EPA plans to consider development of a quantitative dose-response assessment
for cardiovascular and/or hepatic effects associated with TCDD exposure. Such an assessment
would be based on information in U.S. EPA (2003), NAS (2006) and key studies identified in
this workshop. The purpose of this session was to identify and discuss key issues pertaining to
dose-response assessment for dioxin-induced cardiovascular and/or hepatic effects.

Session 3B Panelists (Session Co-Chairs are identified by asterisk)

•	Bob Budinksy, Dow Chemical

•	Manolis Kogevinas, Centre for Research in Environmental Epidemiology

•	Rob McDowell, U.S. Department of Agriculture

•	Jim Olson, State University of New York, University at Buffalo

•	Marian Pavuk, Agency for Toxic Substances and Disease Registry

•	*Jeff Swartout, U.S. EPA

•	*Mary Walker, University of New Mexico

•	Nigel Walker, National Institute of Environmental Health Sciences

Please note that the use of the term "concluded" or "recommended" in this summary does not mean that a consensus
was reached. Session Summaries were written from the material prepared by the non-EPA/ANL Co-chair and
represents a synopsis of the panel discussions.

Key Study Selection Criteria

The Panel initially focused on the draft key study selection criteria offered by the
U.S. EPA (Appendix C). The panel recommended that for cardiovascular effects, which are not
usually observed in rodents, the use of knockout mouse models (ApoE KO and LDLR KO) be
moved to the "primary" column because only these studies establish the cardiovascular toxicity
model in mice.

The panel also was concerned that the gavage procedure can increase mouse blood
pressure. Consequently, the panel recommended that gavage studies not be used for the blood
pressure endpoint (i.e., only dietary dosing studies should be considered).

Human Health Endpoints

In relation to the hepatic endpoint, the Panel acknowledged the large body of dose
response information on hepatic effects in rodents and that enzyme (mostly CYP1 Al) induction
was a sensitive effect. However, the Panel cited the lack of linkage of CYP1A1 to downstream
events, which complicates the toxicological interpretation of this endpoint, and concluded that

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the more important liver effects in rodents are probably on the "road to cancer." The Panel noted
that hepatic effects were not seen in the epidemiological studies, but acknowledged that these
studies were not designed to detect them.

In relation to the cardiovascular endpoint, the Panel identified hypertension and ischemic
heart disease (IHD) as two key endpoints from the epidemiological studies. The Panel
recommended that the U.S. EPA perform a meta-analysis of these data. The Panel also
commented that recent animal studies support the observations linking TCDD exposure to IHD
and hypertension. In particular, the National Toxicology Program (NTP) study shows
inflammatory and structural effects on resistant vascular arterioles (NTP, 2006). Additional
evidence from the study suggests that the vascular effects may be CYP1A1-dependent. The
Panel suggested that the NTP study data might be used as a surrogate for dose-response
modeling of hypertension and that such an approach would be supported by data on the role of
AhR in vascular function and remodeling.

POD Issues

The Panel was not supportive of 1% of maximal response (ED0i), which was utilized in
the 2003 Reassessment. The Panel concluded that the POD should depend on the specific
endpoint and recommended the following to the U.S. EPA:

•	For continuous measures, base the BMR on difference from control. Consider the
adversity level—at what point does the endpoint become adverse?

•	For incidence data, set the BMR to a fixed-risk level.

Supporting Information

The Panel posed several suggestions to the U.S. EPA for reducing uncertainty and
improving the knowledge base for TCDD toxicity.

•	Use in vitro data to define uncertainties, such as the relative sensitivity between rodents
and humans and around the definition of a POD.

•	Consider studies on dioxin-like compounds (DLCs).

•	Use PK modeling to define the dose metric for hepatic effects.

•	Use body burden or serum concentrations for cardiovascular endpoints.

Finally, the Panel recommended that U.S. EPA finish the reassessment quickly and establish a
definitive plan to review and incorporate new data as they become available.

References

NAS (National Academy of Sciences). 2006. Health Risks from Dioxin and Related
Compounds: Evaluation of the EPA Reassessment. National Academies Press, Washington, DC
(July). Available at http://www.nap.edu/catalog.php7record id=l 1688.

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NTP (National Toxicology Program). 2006. Toxicology and Carcinogenesis Studies of
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) (CAS No. 1746-01-6) in Female Harlan Sprague-
Dawley Rats (Gavage Studies). U.S. Department of Health and Human Services. NTP TR 521.
Research Triangle Park, NC (April).

U.S. EPA (U.S. Environmental Protection Agency). 2003. Exposure and Human Health
Reassessment of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) and Related Compounds. NAS
Review Draft (EPA/600/P-00/001Cb). U.S. Environmental Protection Agency, National Center
for Environmental Assessment, Washington, DC. Available at
http://www.epa.gov/nceawwwl/pdfs/dioxin/nas-review/.

SESSION 4A: DOSE-RESPONSE FOR CANCER

The U.S. EPA plans to consider development of a quantitative dose-response assessment
for cancer associated with TCDD exposure. Such an assessment would be based on information
in U.S. EPA (2003), NAS (2006) and key studies identified in this workshop. The purpose of
this session was to identify and discuss key issues pertaining to dose-response assessment for
dioxin-induced cancer.

Session 4A Panelists (Session Co-Chairs are identified by asterisk)

•	Lesa Aylward, Summit Toxicology

•	Kenny Crump, Louisiana Tech University

•	Dale Hattis, Clark University

•	* Janet Hess-Wilson, U.S. EPA

•	Karen Hogan, U.S. EPA

•	Manolis Kogevinas, Centre for Research in Environmental Epidemiology

•	Marian Pavuk, Agency for Toxic Substances and Disease Registry

•	Chris Portier, National Institute of Environmental Health Sciences

•	Lorenz Rhomberg, Gradient

•	Jay Silkworth, General Electric

•	*Nigel Walker, National Institute of Environmental Health Sciences

Please note that the use of the term "concluded" or "recommended" in this summary does not mean that a consensus
was reached. Session Summaries were written from the material prepared by the non-EPA/ANL Co-chair and
represent a synopsis of the panel discussions.

Key Study Selection

The Panel discussed both human and rodent studies. In reviewing the epidemiological
data, the Panel agreed the EPA should focus on four cohort studies (Dutch cohort, NIOSH
cohort, BASF accident cohort, and Hamburg cohort) and pointed out that there are numerous
updates and reevaluations of data now in the literature and others will be published soon. The
Panel stated that it is appropriate for the U.S. EPA to consider the increase in total cancers for
modeling human cancer data, however, Non-Hodgkin's lymphoma, and lung tumors are the main
TCDD-related cancer types seen in humans exposed to TCDD. The Panel suggested the U.S.
EPA focus the quantitative dose-response modeling on the human data.

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In reviewing the rat data, the Panel identified four new NTP rodent cancer bioassays with
liver and lungs as the main target organs. However, they suggested that dose-response modeling
efforts should model "all cancers" from these NTP data sets as well and use tumor incidence—
not individual rats as measures.

Key Study Selection Criteria

The Panel discussed whether data for TCDD only should be used or if PCB126 could be
used to develop a dose-response curve. From this discussion, the Panel reached a general
agreement that limiting the dose-response modeling and cancer assessment to TCDD only would
be the best approach.

Regarding the oral dosing regimens, the Panel discussed the differences in results from
different bioassays. They concluded that there were insufficient data to pick between oral feed
(Kociba et al., 1978) and oral gavage (NTP, 2006) studies, but stated "If all aspects of studies
were equal, an oral feed study is preferred." However, given that current data sets are not equal,
they agreed that U.S. EPA should consider both feed and gavage studies.

The Panel put forth the recommendation that studies that include initiation-promotion
model data and TgAC transgenic model data from oral exposure studies should be excluded from
the primary category in the key study selection criteria (Appendix C lists the draft study selection
criteria distributed prior to the meeting). Studies from both classifications should be moved to
the second tier.

The Panel was also unsupportive of the "response magnitude outside the range of normal
variability" criterion, as they did not believe it was applicable to a cancer endpoint.

Critical Endpoints to Consider

The Panel recognized that the MOA for TCDD includes cell growth/differentiation
dysregulation, that different endpoints (tumor types) across species may be expected, and that
there are differences in tumor sites across species. The Panel further acknowledged that there is
insufficient information to determine if rodent tumor types observed are relevant to humans.
Thus, the Panel suggests the following:

• U.S. EPA should consider all the observed cancer endpoints in its evaluation.

Nonlinear (aka threshold) Versus Linear Dose-Response Modeling

The Panel agreed that NTP bioassays appear to demonstrate nonlinear dose response, but
they expressed concern about using animal data to infer slope and dose response for humans.
The Panel pointed out that there are differences in slopes across different bioassays, and
specifically, that some appear linear while others appear nonlinear. Given the observation of
both nonlinear vs. linear, the Panel concluded that neither could be ruled out for extrapolation
below the POD simply based on the available data. One panelist noted that U.S. EPA Cancer
Guidelines (U.S. EPA, 2005) state that only if one can demonstrate that the MOA has a threshold
dose-response shape, and can exclude all other potential linear MO As, can one use a nonlinear
model. Lastly, the Panel noted that there are data and rationales to support use of both linear and

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nonlinear response below POD. From this discussion, the Panel raised one possibility to the U.S.
EPA:

•	Both linear and nonlinear model functions should be considered in the dose-response
analysis.

Dose Metrics

In considering human data, the Panel expressed a preference for lipid-adjusted serum
levels over body burden (BB), and they expressed concerns over the assumptions used in the
back calculation of the BB in the epidemiologic cohorts. In considering the rat data, the Panel
supported the use of BB—especially lipid-adjusted BB. The Panel, however, did express
concern over the sequestering of TCDD in liver and then the use of liver levels in BB
calculations.

Supporting Information—Biologically-Based Dose-Response (BBDR) Models and MOA

The Panel discussed BBDR. Though once considered an attractive proposition, BBDR
models may mask uncertainty within the models, necessitating them to be used with greater
caution. The Panel suggested two issues for the U.S. EPA to consider:

•	If there is a published model, use it if it is valid—do not generate a new model.

•	Focus on the actual experimental data to drive the analysis.

References

Kociba, R.J., D.G. Keyes, J.E. Beyer et al. 1978. Results of a two-year chronic toxicity and
oncogenicity study of 2,3,7,8-tetrachlorodibenzo-p-dioxin in rats. Toxicol. Appl. Pharmacol.
46:279-303.

NAS (National Academy of Sciences). 2006. Health Risks from Dioxin and Related
Compounds: Evaluation of the EPA Reassessment. National Academies Press, Washington, DC
(July). Available at http://www.nap.edu/catalog.php7record id=l 1688.

NTP (National Toxicology Program). 2006. Toxicology and Carcinogenesis Studies of
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) (CAS No. 1746-01-6) in Female Harlan Sprague-
Dawley Rats (Gavage Studies). U.S. Department of Health and Human Services. NTP TR 521.
Research Triangle Park, NC (April).

U.S. EPA (U.S. Environmental Protection Agency). 2003. Exposure and Human Health
Reassessment of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) and Related Compounds. NAS
Review Draft (EPA/600/P-00/001Cb). U.S. Environmental Protection Agency, National Center
for Environmental Assessment, Washington, DC. Available at
http://www.epa.gov/nceawwwl/pdfs/dioxin/nas-review/.

U.S. EPA (U.S. Environmental Protection Agency). 2005. Guidelines for Carcinogen Risk
Assessment. U.S. Environmental Protection Agency Risk Assessment Forum.
EPA/630/P-03/001F.

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SESSION 4B: DOSE-RESPONSE FOR REPRODUCTIVE/DEVELOPMENTAL
TOXICITY

The U.S. EPA plans to consider development of a quantitative dose-response assessment
for reproductive and developmental effects associated with TCDD exposure. Such an
assessment would be based on information in U.S. EPA (2003), NAS (2006) and key studies
identified in this workshop. The purpose of this session was to identify and discuss key issues
pertaining to dose-response assessment for dioxin-induced reproductive and developmental
effects.

Session 4B Panelists (Session Co-Chairs are identified by asterisk)

•	Barbara Abbott, U.S. EPA

•	Bruce Allen, Bruce Allen Consulting

•	Roger Cooke, Resources for the Future

•	George Daston, Procter & Gamble

•	MikeDeVito, U.S. EPA

•	Rob Goble, Clark University

•	*Fumio Matsumura, University of California-Davis

•	Paolo Mocarelli, University of Milan

•	Brian Petroff, University of Kansas

•	*Glenn Rice, U.S. EPA

•	Marie Sweeney, National Institute of Occupational Safety and Health

•	Mary Walker, University of New Mexico

•	Bernie Weiss, University of Rochester

Please note that the use of the term "concluded" or "recommended" in this summary does not mean that a consensus
was reached. Session Summaries were written from the material prepared by the non-EPA/ANL Co-Chair and
represent a synopsis of the panel discussions.

A Major Question Posed During this Workshop Session was "Are Human Embryos and
Infants Less Sensitive to Dioxin Exposures Than Some Experimental Animals?"

The Panel recognized that animal data show a wide range of species sensitivity to dioxin
for a given developmental or reproductive endpoint. Presently, there are data for some endpoints
that show that human sensitivity is comparable to experimental animals (e.g., semen quality),
and for other endpoints the data demonstrate that humans are insensitive compared to other
species (e.g., cleft palate). Lastly, the Panel recognized that there are some endpoints for which
relative human sensitivity remains uncertain.

Key Study Selection

The Panel reviewed the charge questions (Appendix B), discussed them, and listed two
issues for the U.S. EPA to consider:

•	Concerning key study determination, use a stepwise approach that is dependent upon the
information available and needed to address the question.

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•	Concerning the key studies informing the POD and the POD endpoint choice, use the
POD to depart from what is certain and use a high-confidence study that has found
effects at a low enough level at which other effects are protected.

The Panel also developed Table 1, based on the information presented in this session. Table 1
identifies specific reproductive and developmental effects of concern, listing whether an effect
has been observed in test animals and epidemiologic cohorts. It also identifies the EDi0
estimated by the U.S. EPA (2003) for health effects observed in rodent bioassays. If the U.S.
EPA did not report an EDi0 for an effect, the table identifies a study where the effect was
reported and the lowest study dose where the effect was observed. Table 1 also identifies the
epidemiologic cohort where the specific reproductive and developmental effects were observed.

Epidemiological Study Utility

The Panel reviewed the charge questions (Appendix B), discussed them, and made two
suggestions to the U.S. EPA:

•	Concerning the ability of epidemiological studies to inform critical effects, start with
concordance across species (including humans) for the spectrum of effects.

•	Concerning the ability of epidemiological studies to inform dose-response modeling, start
with the epidemiology and then go to animal data if the dose response has not been well
characterized for an endpoint of interest and compare to animal data as a reality check.

Animal Model Utility

The Panel reviewed and discussed the charge questions (Appendix B). Table 1, which
identifies the effects that occur in animals and also have relevance to humans, summarizes much
of this discussion. Regarding the influence of mode of action (MO A) on animal model choice,
the Panel concluded that by evaluating concordance among health effects reported in
epidemiologic and animal bioassay data, the U.S. EPA could identify a set of plausible
reproductive and developmental effects to consider. Actual animal and human MOA
information is helpful in that it creates comfort with the animal models and in defining the
boundaries of possible effects.

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TABLE 1



Reproductive/Developmental Effects of Concern for Human Health

Endpoint

Rodent
(ED 10 ng/kg-d)

Human

Notes

Sperm Count/Motility

Yes (6.2-28;
66-200)

Yes

EDio bases Mabley et al. (1992a,b) caudal
sperm count and daily sperm production
range from 6.2-28; Gray et al. (1997)
epididymal sperm count and total testis sperm
counts range from 66-200.

Sex Ratio

No

Yes, Seveso



Delayed Puberty Males

Yes (94)

Yu-cheng

EDio basis rat male puberty delay Gray et al.
(1997). Need to qualify epidemiology data
because of cohort PCDD/PCDFs exposures.

Delayed Puberty in Females

Yes

No in Seveso

Gray and Ostby (2002) report delayed
puberty in female offspring of pregnant rats
receiving a single dose of 1 |ig TCDD/kg on
GD 15.

Cleft Palate

Yes(6300-6400)

No

EDio basis Birnbaum et al. (1989).

Premature Senescence

Yes

No, Seveso

Franczak et al. (2006) report that rats
prematurely entered reproductive senescence,
after receiving cumulative TCDD doses as
low as 1.7 jig TCDD/kg. They considered
first occurrence of prolonged interestrous
interval (>6 d) as evidence of onset of
reproductive senescence.

Hormones E2

Yes

Yes, Males—
Seveso

Li et al. (1995) report serum estradiol-17f^
(E2) concentrations induced by equine
Chorionic Gonadotropin injection were
significantly elevated in female rats orally
administered 10 (ig/kg TCDD onPND 22.
While E2 decreased dramatically in control
animals during the preovulatory LH surge, it
did not in TCDD-treated rats.

Low Birth Weight

Yes (190)

Suggestive
effect in Seveso
in first 8 years
after exposure

EDio basis Gray et al. (1997).

Reproductive Cycling
(prolongation)

Yes

Yes, Seveso
Prepubertal
exposure

Franczak et al. (2006) report loss of normal
cyclicity in female rats at 8 months of age
following a cumulative dose of 1.7 jig
TCDD/kg.

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Supporting Information

The Panel reviewed the charge questions (Appendix B), discussed them, and made two
suggestions to the U.S. EPA:

•	Concerning deviation from default approaches for noncancer endpoints, there needs to be
a careful assessment of the POD and the application of uncertainty factors in light of
PK/pharmacodynamics (PD), population characteristics and variability, and MOA
information.

•	Concerning the MOA's ability to clarify endpoint and the incorporation of a cascade of
cellular event into dose-response for noncancer endpoint, any study that helps inform the
dose response should be considered—including studies not specific to dioxins.
Complicated mechanistic models need not be developed. Standard dose-response models
can be applied. One can look at the cascade of events in a stepwise, simple way.

References

Birnbaum, L.S., M.W. Harris, L.M. Stocking et al. 1989. Retinoic acid and 2,3,7,8-
tetrachlorodibenzo-p-dioxin selectively enhance teratogenesis in C57BL/6N mice. Toxicol.

Appl. Pharmacol. 98:487-500.

Franczak, A., A. Nynca, K.E. Valdez, K.M. Mizinga and B.K. Petroff 2006. Effects of acute
and chronic exposure to the aryl hydrocarbon receptor agonist 2,3,7,8-tetrachlorodibenzo-
p-dioxin on the transition to reproductive senescence in female Sprague-Dawley rats. Biol.
Reprod. 74:125-130.

Gray, L.E. and J.S. Ostby. 2002. In utero 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) alters
reproductive morphology and function in female rat offspring. Toxicol. Appl. Pharmacol.
133(2):285-294.

Gray, L.E., J.S. Ostby and W.R. Kelce. 1997. A dose-response analysis of the reproductive
effects of a single gestational dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin in male Long Evans
Hooded rat offspring. Toxicol. Appl. Pharmacol. 146:11-20.

Li, X., D.C. Johnson and K.K. Rozman. 1995. Reproductive effects of 2,3,7,8-
tetrachlorodibenzo-p-dioxin (TCDD) in female rats: ovulation, hormonal regulation, and possible
mechanism(s). Toxicol. Appl. Pharmacol. 133:321-327.

Mably, T.A., D.L. Bjerke, R.W. Moore et al. 1992a. In utero and lactational exposure of male
rats to 2,3,7,8-tetrachlorodibenzo-p-dioxin. 3. Effects on spermatogenesis and reproductive
capability. Toxicol. Appl. Pharmacol. 114:118-126.

Mably, T.A., R.W. Moore, R.W. Goy et al. 1992b. In utero and lactational exposure of male
rats to 2,3,7,8-tetrachlorodibenzo-p-dioxin. 2. Effects on sexual behavior and the regulation of
luteinizing hormone secretion in adulthood. Toxicol. Appl. Pharmacol. 114:108-117.

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NAS (National Academy of Sciences). 2006. Health Risks from Dioxin and Related
Compounds: Evaluation of the EPA Reassessment. National Academies Press, Washington, DC
(July). Available at http://www.nap.edu/catalog.php7record id=l 1688.

U.S. EPA (U.S. Environmental Protection Agency). 2003. Exposure and Human Health
Reassessment of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) and Related Compounds. NAS
Review Draft (EPA/600/P-00/001Cb). U.S. Environmental Protection Agency, National Center
for Environmental Assessment, Washington, DC. Available at
http://www.epa.gov/nceawwwl/pdfs/dioxin/nas-review/.

SESSION 5: QUANTITATIVE UNCERTAINTY ANALYSIS OF DOSE-RESPONSE

This session addressed the uncertainty analysis to be considered for the dose-response
assessments. The session opened with a presentation on current estimates of dioxin exposure
levels. Then it focused on the factors to include in the scope of an uncertainty analysis including
dioxin kinetics.

Session 5 Panelists (Session Co-Chairs are identified by asterisk)

•	Bruce Allen, Bruce Allen Consulting

•	Lesa Aylward, Summit Toxicology

•	Roger Cooke, Resources for the Future

•	Kenny Crump, Louisiana Tech University

•	MikeDeVito, U.S. EPA

•	Dale Hattis, Clark University

•	*Rick Hertzberg, Biomath Consulting

•	Nancy Kerkvliet, Oregon State University

•	Leonid Kopylev, U.S. EPA

•	Rob McDowell, U.S. Department of Agriculture

•	Lorenz Rhomberg, Gradient

•	Woody Setzer, U.S. EPA

•	Marie Sweeney, National Institute of Occupational Safety and Health

•	*Linda Teuschler, U.S. EPA

Please note that the use of the term "concluded" or "recommended" in this summary does not mean that a consensus
was reached. Session Summaries were written from the material prepared by the non-EPA/ANL Co-Chair and
represent a synopsis of the panel discussions.

The Panel summarized the NAS comments regarding uncertainty. Areas for improvement
include:

•	Ensure "transparency, thoroughness, and clarity in quantitative uncertainty analysis."

•	Describe and define (quantitatively to the extent possible) the variability and uncertainty
for key assumptions used for each key endpoint-specific risk assessment, including
choices of data set, point of departure, dose-response model, and dose metric.

•	Incorporate probabilistic models to represent the range of plausible values.

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•	Assess goodness-of-fit of dose-response models.

•	Provide upper and lower bounds on central tendency estimates for all statistical estimates.

•	When quantification is not possible, clearly state it, and explain what would be required
to achieve quantification.

Identification of Important Uncertainties

The Panel reviewed the charge questions (Appendix B), discussed them, and listed eight
issues for consideration by the U.S. EPA:

•	Concerning species and strain differences in the U.S. EPA's Response to NAS, current
U.S. EPA procedures do not take this into account when selecting one data set for risk
assessment. Issues include "Where are humans in the distribution of potencies that can
be generated? How likely is it that human response is similar to the selected data? Can
we infer inter-individual variability from these differences?"

•	Concerning the use of animal data for cross species extrapolation to humans (PK and PD
uncertainties), issues to consider include differences in distribution and responses
following bolus doses from those of subchronic and chronic protocols; uncertainty in
liver doses due to sequestration; differences in receptor binding affinity among
congeners; and age factors (e.g., assumption of a lifetime constant daily dose for a cancer
extrapolation).

•	Concerning the description of AhR response, biochemical changes occur at lower doses
than toxicological changes. There should be an effort to identify the biochemical changes
that would mark Ah receptor binding to inform the BMR, and, thus, prevent toxicity.

•	Concerning model uncertainty, the mathematical model choice depends on endpoint.
There should be an effort towards determining what is the most sensitive endpoint(s) for
humans and conducting animal studies to model that endpoint(s).

•	Concerning exposure and dose response in human studies, ensure enough similarity to
current human exposure profiles (mixture composition) so that a dose-response
assessment can be done. Incorporate new epidemiological studies. Evaluate
concordance with animal data and consistency across studies. Panel-acknowledged
uncertainties include exposure estimates from person to person, shape of human dose-
response curve, healthy worker effect, and age dependence.

•	Concerning POD determination, uncertainty factors are inherently mathematically
inconsistent and that should be conveyed in the discussion of uncertainties when
interpreting the POD.

•	Concerning dose metric, tissue concentration is preferred. It should be evaluated against
a background of variability in AhR-binding expression. There is uncertainty in what
level of binding should be considered, in different cell types, tissues, life stage
(development). The relationship between dose metric and causation of adverse effects
should be examined.

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Low-Dose Extrapolation

The Panel reviewed the charge questions and discussed them (Appendix B). The Panel
concluded that curve-fitting uncertainty (for a given dataset, dose metric, and model) can be
characterized and is useful, but, by itself, it is an incomplete characterization of uncertainty. The
Panel acknowledged the difficulty of fully characterizing uncertainty, especially quantitatively.
Some panelists argued that the problem is insurmountable and that no meaningful uncertainty
analysis is likely to be performable. Other panelists contended that, the difficulties
notwithstanding, "good-faith" efforts to do something practical and forthright to characterize
uncertainty in low-dose extrapolation would be useful and important. The Panel clarified "good
faith" as meaning a characterization that is useful and not misleading to decision makers and is
inclusive of approaches that have meaningful support in the scientific community as a whole.
Being in "good faith" is more important than being complete (i.e., addressing every uncertain
element), especially since completeness is not a realistic goal. From this discussion, the Panel
listed four issues for consideration by the U.S. EPA:

•	Review alternative data sets, dose metrics, and models to see where consequential
uncertainties and impacts on low-dose implications arise.

•	Consider the impacts of choices among plausible alternative data sets, dose metrics,
models, and other more qualitative choices—issues include how much difference the
choices make and also how much relative credence should be put to each alternative as a
way of gauging and describing the landscape of imperfect knowledge

regarding possibilities for the true dose-response.

¦	Hard to do quantitatively, since the factors are not readily expressed as statistical
distributions, but can describe the rationale for believing/doubting each alternative in
terms of available supporting evidence, contrary evidence, and needed assumptions.

¦	Expert judgment methods may be helpful in characterizing the relative weights of
scientific credibility among alternatives. The expert judgment process, when
conducted systematically, can be thought of as adding data to the assessment of
credibility of alternatives, rather than as just an opinion poll.

¦	Information on plausibility of alternative low-dose extrapolation approaches can
come from external considerations of mode of action, and not just from statistical
success at fitting particular (high-dose) data sets.

•	Characterizing uncertainty through a variety of approaches could be tried, and their
relative merits and shortcomings discussed, as a way forward.

•	Consider the sources of potential error, particularly in epidemiological data (e.g., TEF
uncertainty and variation in congener mixtures) and if possible quantify their impact on
the dose-response assessment.

Considerations for Conducting Uncertainty Analysis

Overall, the Panel was split on whether U.S. EPA should do quantitative uncertainty
analyses. The Panel noted that if done on only some of the uncertainties, then results would be
misleading and could be misused. Ultimately, the Panel listed seven issues for consideration by
the U.S. EPA:

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•	The Panel recapped what some consider as being the first integrated risk assessment, with
structured expert judgment and uncertainty analysis, i.e., the Rasmussen Report
(WASH-1400; U.S. Nuclear Regulatory Commission, 1975). In their discussion of the
report, the Panel noted that in addition to standard event tree/fault tree modeling, this
report also tackled difficult model uncertainty issues involved in accident progression,
dispersion of released pollutants in the atmosphere, environmental transport, exposure,
health, and economic impacts. And though the Panel also recognized that this method
was no longer state-of-the-art, the Panel contended that it represents a good example of a
structured approach and methodology that could be built upon.

•	The Panel also discussed TEQs used in epidemiological studies, based on intake, and
recognized that the key uncertainty in what was measured was not just intake but also
involved PK/PD issues. The Panel acknowledged that the TEQ system is regularly used
on a concentration basis, but they expressed concern that the qualification becomes lost.
TEQs ignore pharmacokinetics and the common practice of rounding to orders of
magnitude introduces more error.

•	Structure the risk assessment along MOA steps—identify key biochemical measures
(-5-10) common across toxic endpoints and identify the degree of meaningful change in
effect or effect variance. Make a table with all options for data set, model, etc.; make
best estimates/choices and determine which of these choices matter the most to the
answer.

•	Use expert panels—expert judgment can be collected scientifically (procedures are
published). But there are known biases; central tendency estimates work much better
than extremes.

•	Use supporting studies to fill in critical data gaps—Info filling methods do exist (e.g., PK
modeling). Put short-term studies into the "supporting info" category (unless, of course,
the risk assessment is for acute exposures, such as chemical spills).

•	Be creative in the analysis of uncertainty. Intermediate steps between AhR binding and
the end processes can be hypothesized based on data, experiences, and analogies related
to other chemicals.

•	The 2003 Reassessment presented potency estimates on wide variety of
endpoints/models; needed to be more transparent in that discussion. Statistical graphics
can be used to convey uncertainties.

Reference

U.S. Nuclear Regulatory Commission. 1975. Reactor Safety Study: An Assessment of Accident
Risks in U.S. Commercial Nuclear Power Plants. WASH-1400 (NUREG-75-014). Washington,
DC.

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APPENDIX A: 2009 U.S. EPA DIOXIN WORKSHOP AGENDA

SCIENTIFIC WORKSHOP
TO INFORM THE TECHNICAL WORK PLAN FOR U.S. EPA'S RESPONSE TO
NAS COMMENTS ON THE HEALTH EFFECTS OF DIOXIN
PRESENTED IN U.S. EPA'S DIOXIN REASSESSMENT

Cincinnati, OH

Date: February 18-20, 2009

BACKGROUND/WORKSHOP OBJECTIVE

At the request of the U.S. Environmental Protection Agency (U.S. EPA), the National
Academy of Sciences (NAS) prepared a report, Health Risks from Dioxin and Related
Compounds: Evaluation of the EPA Reassessment (NAS, 2006), that made a number of
recommendations to improve the U.S. EPA's risk assessment for 2,3,7,8-tetrachlorodibenzo-
/;-dioxin (TCDD). In response, the U.S. EPA will prepare a technical report that addresses key
comments on the dose-response assessment for TCDD. The U.S. EPA intends to develop its
response through a transparent process that provides multiple opportunities for input.

To assist in this effort, a Workshop will be held to inform the U.S. EPA's evaluation of
the NAS recommendations. The Workshop will be open to the public. At the Workshop, the
U.S. EPA will solicit input from expert scientists and the public.

The goal of the Workshop is to ensure that the U.S. EPA's response to the NAS
comments focuses on the key issues and reflects the most meaningful science. The three main
objectives of the Workshop are to (1) identify and discuss the technical challenges involved in
addressing the NAS key comments on the TCDD dose-response assessment in the U.S. EPA
Reassessment (U.S. EPA, 2003), (2) discuss approaches for addressing these comments, and
(3) identify key published, independently peer-reviewed literature, particularly studies describing
epidemiologic and in vivo mammalian bioassays, which are expected to be most useful for
informing the U.S. EPA response.

Workshop participants will be encouraged to think broadly about the body of scientific
information that can be used to inform the U.S. EPA's response and to participate in open
dialogue regarding ways in which the science can best be used to address the key dose-response
issues. This Workshop is similar to scientific workshops being conducted under the new review
process for the National Ambient Air Quality Standards (NAAQS)1 that assess health-related
information for criteria pollutants.

1 Please see http://www.epa.gov/ttn/naaas/ for more information on the new NAAQS review process.

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The Workshop discussions are expected to build upon two prior publications:

1.	Exposure and Human Health Reassessment of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin
(TCDD) and Related Compounds (U.S. EPA, 2003). This external review draft
provides a comprehensive reassessment of dioxin exposure and human health effects.
This "dioxin reassessment" was submitted in October 2004 to the National Academy
of Sciences (NAS) for review.

2.	Health Risks from Dioxin and Related Compounds: Evaluation of the EPA
Reassessment (NAS, 2006).

Workshop participants are encouraged to review both of these documents and other
relevant materials (e.g., the National Toxicology Program report on TCDD [NTP, 2006]) before
the meeting because they provide important insights into the key questions and challenges.

There are a number of open comment periods that are intended to facilitate a broad discussion of
the issues.

Scientists with significant expertise and experience relevant to the health effects of
TCDD or dioxin-like compounds and associated topics will be asked to serve on "expert panels"
for discussions throughout the Workshop. Workshop panelists will include a wide range of
experts representing many scientific areas needed to assess TCDD dose-response (e.g.,
epidemiology, human and animal toxicology, nuclear receptor biology, dose-response modeling,
risk assessment, and uncertainty analysis). The Workshop panelists will be asked to highlight
significant and emerging research and to make recommendations to the U.S. EPA regarding the
design and scope of the technical response to NAS comments on the dose-response analysis for
TCDD—including, but not limited to, recommendations for evaluating associated uncertainty.
Open comment periods will follow each panel discussion session. Public participation will be
encouraged by way of these designated open comment periods and, also, by participation in the
scientific poster session planned for the second evening (February 19).

U.S. EPA will use the input received during this Workshop as the foundation for its
development of a technical work plan for responding to the NAS comments on the TCDD dose-
response analysis. The work plan will outline the schedule, process, and approaches for
evaluating the relevant scientific information and addressing the key issues. The work plan also
will identify the key literature to be utilized in U.S. EPA's response.

As a follow-on activity to this Workshop, a panel is being established under the Federal
Advisory Committee Act (FACA) to guide and review the U.S. EPA's response to NAS
comments. The FACA panel will be asked to conduct a consultation with the Agency on the
draft technical work plan. At the same time, the public will also have the opportunity to provide
comments to the FACA panel on the work plan. The final technical work plan will guide the
development of the technical report that will constitute the U.S. EPA's response to NAS
comments. During the development of this response, the U.S. EPA will seek advice from the
FACA panel and the public several times. Finally, the FACA panel will be asked to review the
technical report in a public forum.

The preliminary Agenda presented on the following pages may be revised prior to the
Workshop following review by the session Co-Chairs; the dates and general timing of the

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sessions, however, will not change. A final Agenda and a set of charge questions, intended to
provide general direction for the Workshop discussions, will be posted on the Workshop Internet
site (http://cfpub.epa.gov/ncea/cfrn/recordisplav.cfm?deid=199923) prior to the meeting.

A poster session will be held on the evening of the second day (February 19). The
purpose of this poster session is to provide a forum for scientists to present recent studies
relevant to TCDD dose-response assessment and to encourage open discussion about these
presentations.

REFERENCES

NAS (National Academy of Sciences). 2006. Health Risks from Dioxin and Related
Compounds: Evaluation of the EPA Reassessment. National Academies Press, Washington, DC
(July). Available at http://www.nap.edu/catalog.php7record id=l 1688.

NTP (National Toxicology Program). 2006. Toxicology and Carcinogenesis Studies of
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) (CAS No. 1746-01-6) in Female Harlan Sprague-
Dawley Rats (Gavage Studies). U.S. Department of Health and Human Services. NTP TR 521.
Research Triangle Park, NC (April).

U.S. EPA (U.S. Environmental Protection Agency). 2003. Exposure and Human Health
Reassessment of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) and Related Compounds, NAS
review draft, Volumes 1-3 (EPA/600/P-00/001Cb, Volume 1). U.S. Environmental Protection
Agency, National Center for Environmental Assessment, Washington, DC (December).
Available at http://www.epa.gov/nceawwwl/pdfs/dioxin/nas-review/.

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WORKSHOP AGENDA

Day 1

8:00-9:00	Registration

9:00-9:30	Welcome/Purpose of Meeting/Document Development Process

9:30-9:45	Panel Comments/Questions on Charge

9:45-2:45	Session 1: Quantitative Dose-Response Modeling Issues

(Hall of Mirrors)

9:45-10:10 Background/Introductory Remarks

10:10-10:35 TCDD Kinetics: Converting Administered Doses in Animals to
Human Body Burdens

Presenter: Michael Devito

10:35-11:30	Panel Discussion

11:30-1:00	Lunch

1:00-2:00	Panel Discussion cont.

2:00-2:45	Open Comment Period

2:45-3:05	Break

3:05-5:15	Session 2: Immunotoxicitv (Hall of Mirrors)

3:05-3:15	Background/Introductory Remarks

3:15-4:45	Panel Discussion

4:45-5:15	Open Comment Period

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Day 2

8:00-8:30	Report-Outs for Sessions 1 and 2 (Hall of Mirrors)

8:00-8:15 Report-Out for 1: Quantitative Dose-Response Modeling Issues
8:15-8:30 Report-Out for 2: Immunotoxicity

8:30-11:30 Sessions 3A and 3B (concurrent sessions)

8:30-11:30	Session 3A: Dose-Response for Neurotoxicity and

Nonreproductive Endocrine Effects (Hall of Mirrors)

8:30-8:45 Background/Introductory Remarks

8:45-11:00 Panel Discussion
11:00-11:30 Open Comment Period

8:30-11:30	Session 3B: Dose-Response for Cardiovascular Toxicity and

Hepatotoxicity (Rookwood Room)

8:30-8:45 Background/Introductory Remarks

8:45-11:00 Panel Discussion

11:00-11:30 Open Comment Period

11:30-1:00 Lunch

1:00-2:00	Report-Outs for Sessions 3A and 3B (Hall of Mirrors)

The structure of the session report-outs will include the following:

Summary of session presentation including minority opinion

¦	Public comments

¦	Discussion

1:00-l: 15 Report-Out for 3A: Dose-Response for Neurotoxicity and
Nonreproductive Endocrine Effects

1:15-1:30 Open Comment Period

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1:30—1:45 Report-Out for 3B: Dose-Response for Cardiovascular Toxicity and
Hepatotoxicity

1:45-2:00 Open Comment Period

2:00-5:15	Sessions 4A and 4B (concurrent sessions)

2:00-5:15	Session 4A: Dose-Response for Cancer (Hall of Mirrors)

2:00-2:15	Background/Introductory Remarks

2:15-4:45	Panel Discussion

4:45-5:15	Open Comment Period

2:00-5:15	Session 4B: Dose-Response for

Reproductive/Developmental Toxicity (Rookwood Room)

2:00-2:15	Background/Introductory Remarks

2:15-4:45	Panel Discussion

4:45-5:15	Open Comment Period

6:45-8:15	Poster Session (Rosewood Room)

Day 3

8:30-9:30	Report-Outs for Sessions 4A and 4B (Hall of Mirrors)

8:30-8:45 Report-Out for 4A: Dose-Response for Cancer
8:45-9:00 Open Comment Period

9:00-9:15 Report-Out for 4B: Dose-Response for Reproductive/Developmental
Toxicity

9:15-9:30 Open Comment Period

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9:30-3:30	Session 5: Quantitative Uncertainty Analysis of Dose-

Response (Hall of Mirrors)

9:30-9:40 Background/Introductory Remarks

9:40-10:10 Evidence of a Decline in Background Dioxin Exposures in Americans
Between the 1990s and 2000s

Presenter: Matt Lorber

10:10-10:30	Break

10:30-11:30	Panel Discussion

11:30-1:00	Lunch

1:00-2:15	Panel Discussion cont.

2:15-2:30	Break

2:30-3:00	Open Comment Period

3:00-3:15	Report-Out for 5: Quantitative Uncertainty Analysis of Dose-
Response

3:15-3:30 Closing Remarks
3:30	Adjourn

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APPENDIX B: 2009 U.S. EPA DIOXIN WORKSHOP
QUESTIONS TO GUIDE PANEL DISCUSSIONS

SESSION 1
Dose Metric

Considering all of the endpoints or target tissues, and species that U.S. Environmental Protection
Agency (U.S. EPA)'s dose-response modeling might evaluate, what are the best measures of
dose (e.g., ingested, tissue concentrations, body burden, receptor occupancy, other surrogate) and
why?

Developing Dose-Response Models from Mammalian Bioassays

How best can the point of departure (POD) be determined when the response range is
incompletely characterized (i.e., high response at the lowest dose or low response at the highest
dose; observed in several key 2,3,7,8-Tetrachlorodibenzo-p-Dioxin [TCDD] studies)?

If considered to be biologically plausible, how can a threshold be incorporated into a dose-
response function (e.g., for TCDD cancer data)?

How can nonmonotonic responses be incorporated into the dose-response function?

Developing Dose-Response Models from Epidemiological Studies

How can the epidemiological data be utilized best to inform the TCDD exposure-response
modeling? Which epidemiological studies are most relevant?

Supporting Information

For those toxicological endpoints that are Ah receptor-mediated, how would the receptor kinetics
influence the shape of the dose-response curve? How would downstream cellular events affect
the shape of the dose-response curve? How can this cascade of cellular events be incorporated
into a quantitative model of dose-response?

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SESSIONS 2, 3A, 3B, 4A, AND 4B

Key Study Selection

For this endpoint, what refinements should be made to the draft criteria for selection of key
studies?

What are the specific effects of concern for human health for this endpoint?

Based on the draft criteria for the selection of key studies, what are the key studies informing the
shape of the dose-response curve above the POD and the choice of the POD for this endpoint?

Epidemiological Study Utility

How and to what extent do the epidemiological data inform the choice of critical effect?

How can the epidemiological data inform the quantitative dose-response modeling?

Animal Model Utility

Are there types of effects observed in animal models that are more relevant to humans than
others? To what extent does information on mode of action (MOA) influence the choice of
animal model (species, strain, sex)?

Supporting Information

Are there studies that establish a sufficient justification for departure from the default procedures
that address the shape of the dose-response curve below the POD under the cancer guidelines?

Are there studies that establish a sufficient justification for departing from U.S. EPA's default
approaches for noncancer endpoints?

To what extent can MO A information clarify the identification of endpoints of concern and dose-
response metric for this endpoint? How can the cascade of cellular events for this endpoint be
incorporated into a quantitative model of dose response?

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SESSION 5

For cancer and noncancer TCDD dose-response assessments, U.S. EPA is interested in
developing a quantitative uncertainty analysis addressing both parameter and model uncertainty,
if feasible. Uncertainties will include, among others, choice of endpoint; underlying study
uncertainties; choice of dose metric; interspecies extrapolations such as kinetic uncertainties; and
choice of dose-response model, including threshold models. The U.S. EPA is currently
examining techniques and tools for uncertainty analysis—including Bayesian and frequentist
approaches.

Identification of Important Uncertainties

What are the major uncertainties pertaining to modeling the animal data?

Consider the dose metric (species or tissue specificity), vehicle of administration,
exposure frequency, exposure duration, and POD determination (e.g., benchmark
response selection or no-observed-adverse-effect level/lowest-observed-adverse-effect
level identification).

What are the major uncertainties pertaining to dose-response modeling below the POD?

Consider how receptor kinetics and downstream cellular event information might be used
to bound the uncertainties associated with dose-response modeling below the POD.

What are the major uncertainties in cross-species extrapolation (e.g., half-lives, tissue
distribution, and toxicodynamics)?

Consider the primary species dosed with TCDD: mice, hamsters, rats, guinea pigs, and
monkeys.

What are the major uncertainties pertaining to intrahuman variability?

Consider what data sets would be useful to represent sensitive subpopulations.

What are other significant sources of uncertainty for the cancer and noncancer assessments?
Considerations for Conducting Uncertainty Analysis

What data sets could be used to quantify uncertainties in cancer and noncancer TCDD dose-
response assessments?

Consider dioxin-like compound dose-response data.

Consider MOA information.

What are the appropriate techniques for the TCDD dose-response uncertainty analysis, and what
are their respective strengths and weaknesses of these approaches as applied to TCDD?

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APPENDIX C: 2009 U.S. EPA DIOXIN WORKSHOP DRAFT SELECTION CRITERIA TO IDENTIFY KEY IN
VIVO MAMMALIAN STUDIES THAT INFORM DOSE-RESPONSE MODELING FOR
2,3,7,8-TETRACHLORODIBENZO-/>-DIOXIN (TCDD)a

Study Feature

Selection Rationale

Primaryb

Secondaryc

Currently Excluded

Chemical, purity,
matrix/medium

TCDD-only doses included, purity specified,
matrix in which TCDD is administered is identified

TCDD purity or matrix not clearly identified

Studies of dioxin-like compounds
(DLCs) or mixtures

Peer review

Independently peer-reviewed, publicly available

Supplementary materials accompanying
peer-reviewed publication

Not formally peer-reviewed; literature
not publicly available

Study design,
execution, and
reporting

Clearly documented and consistent with standard
toxicological principles, testing protocols,
and practice (i.e., endpoint-appropriate,
particularly for negative findings)

Testing protocol provides incomplete
coverage of relevant endpoint-specific
measures, particularly for negative findings

Studies not meeting standard
principles and practices

Study subject:
species, strain, and
sensitivity for given
endpoint; litter; life
stage; gender

Mammalian species

Strain and gender identified

Animal age at beginning of treatment identified

Litter confounders (within/between) accounted for

Mammalian species, in vivo, but only
studying an artificially sensitive subject
(e.g., knockout mouse)

Non-mammalian or not in vivo

Exposure route

Oral

Parenteral (e.g., intravenous, intramuscular,
intraperitoneal, subcutaneous)

Inhalation, dermal, ocular

Dose level

Lowest dose <200 ng/kg-d for noncancer
endpoints and <1 pg/kg-d for cancer

Lowest dose >200 ng/kg-d for noncancer
endpoints, or >1.0 [jg/kg-d for cancer



Exposure frequency,
duration, and timing

Dosing regimen characterized and explained



Characterization/explanation
missing or cannot be determined

Controls

Appropriate and well characterized

Effect reported, but with no negative control



Response

Effect relevant to human health
Magnitude outside range of normal variability

Precursor effects, or adaptive responses
potentially relevant to human health

Lethality

Statistical evaluation

Clearly described and appropriate to the endpoint
and study design (e.g., per error variance,
magnitude of effect)

Limited statistical context



a NAS (2006) commented that the selection of data sets for quantitative dose-response modeling needed to be more transparent. These draft criteria are
offered for consideration at the kickoff workshop. These criteria would be used to identify candidate studies of non-human mammals that would be used to
define the point-of-departure (POD). These criteria are not designed for hazard identification or weight-of-evidence determinations. Studies addressing data
other than direct TCDD dose-response in mammals (including toxicokinetic data on absorption, distribution, metabolism, or elimination; information on
physiologically-based pharmacokinetic [PBPK] modeling, and mode of action data) will be evaluated separately.
b Presents preliminary draft criteria for evaluating a study being considered for estimating a POD in a TCDD dose-response model.

c Presents preliminary draft criteria that could qualify a study as primary with support from other lines of evidence (e.g., PBPK modeling), when no study for an
endpoint meets the "primary" criteria.


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DRAFT

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May 2010
External Review Draft

APPENDIX B

Evaluation of Cancer and Noncancer
Epidemiological Studies for Inclusion in
TCDD Dose-Response Assessment

NOTICE

THIS DOCUMENT IS AN EXTERNAL REVIEW DRAFT. It has not been formally released
by the U.S. Environmental Protection Agency and should not at this stage be construed to
represent Agency policy. It is being circulated for comment on its technical accuracy and policy
implications.

National Center for Environmental Assessment
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, OH


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CONTENTS—Appendix B: Evaluation of Cancer and Noncancer Epidemiological Studies
for Inclusion in TCDD Dose-Response Assessment

LIST OF TABLES	B-iii

APPENDIX B. EVALUATION OF CANCER AND NONCANCER
EPIDEMIOLOGICAL STUDIES FOR INCLUSION IN

TCDD DOSE-RESPONSE ASSESSMENT	B-l

B.l. EVALUATION 01 CANCER STUDIES	B-l

B.l.l. NIOSH Cohort Studies	B-l

B.l.2. BASF Cohort Studies	B-8

B.l.3. The Hamburg Cohort	B-ll

B.l.4. The Seveso Cohort Studies	B-16

B.l.5. The Chapaevsk Study	B-22

B. 1.6. The Air Force Health ("Ranch Hands") Study	B-23

B. 1.7. Other Studies of Potential Relevance to Dose-Response Modeling	B-26

B.2. EVALUATION OF NONCANCER STUDIES	B-31

B.2.1. NIOSH Cohort	B-3 1

B.2.2. BASF Cohort	B-33

B.2.3. Hamburg Cohort	B-35

B.2.4. The Seveso Women's Health Study	B-36

B.2.5. Other Seveso Noncancer Studies	B-45

B.2.6. Chapaevsk Study	B-55

B.2.7. Air Force Health ("Ranch Hands") Study	B-56

B.2.8. Other Noncancer Studies of Dioxin	B-57

B.3. REFERENCES	B-61

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LIST OF TABLES

B-l. Fingerhut et al., 1991—All cancer sites, site-specific analysis	B-l

B-2. Steenland et al., 1999—All cancer sites combined, site-specific analysis	B-2

B-3. Steenland et al., 2001—All cancer sites combined	B-4

B-4. Cheng et al., 2006—All cancer sites combined	B-5

B-5. Collins et al., 2009—All cancer sites combined, site-specific analysis	B-6

B-6. Zober et al., 1990—All cancer sites combined, site-specific analysis	B-8

B-7. Ott and Zober, 1996—All cancer sites combined	B-9

B-8. Manz et al., 1991—All cancer sites combined, site-specific analyses	B-l 1

B-9.	Flesch-Janys et al., 1995; Flesch-Janys et al., 1996 erratum—All cancer sites

combined	B-12

B-10. Flesch-Janys et al., 1998—All cancer sites combined, site-specific analysis	B-13

B-ll. Becher et al., 1998—All cancer sites combined	B-15

B-12. Bertazzi et al., 2001—All cancer sites combined, site-specific analyses	B-16

B-13. Pesatori et al., 2003—All cancer sites combined, site-specific analyses	B-17

B-14. Consonni et al., 2008—All cancer sites combined, site-specific analyses	B-18

B-15. Baccarelli et al., 2006—Site-specific analysis	B-20

B-16. Warner et al., 2002—Breast cancer incidence	B-21

B-17. Revich et al., 2001—All cancer sites combined, and site-specific analyses	B-22

B-18. Akhtar et al., 2004—All cancer sites combined and site-specific analyses	B-23

B-l9. Michalek and Pavuk, 2008—All cancer sites combined	B-25

B-20. 't Mannetje et al., 2005—All cancer sites combined, site specific analyses	B-26

B-21. McBride et al., 2009b—All cancer sites combined, site-specific analysis	B-27

B-22. McBride et al., 2009a—All cancer sites combined, site-specific analysis	B-28

B-23. Hooiveld et al., 1998—All cancer sites combined, site-specific analysis	B-29

B-24. Steenland et al., 1999—Mortality (noncancer)	B-31

B-25. Collins et al., 2009—Mortality (noncancer)	B-32

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LIST OF TABLES (continued)

B-26.	Ott and Zober, 1996—Mortality (noncancer)	B-33

B-27.	Flesch-Janys et al., 1995; Flesch-Janys et al., 1996 erratum—Mortality

(noncancer)	B-35

B-28.	Eskenazi et al., 2002a—Menstrual cycle characteristics	B-36

B-29.	Eskenazi et al., 2002b—Endometriosis	B-38

B-30.	Eskenazi et al., 2003—Birth outcomes	B-39

B-31.	Warner et al., 2004—Age at menarche	B-40

B-32.	Eskenazi et al., 2005—Age at menopause	B-41

B-33.	Warner et al., 2007—Ovarian function	B-43

B-34.	Eskenazi et al., 2007—Uterine leiomyoma	B-44

B-35.	Mocarelli et al., 2008—Semen quality	B-45

B-36.	Mocarelli et al., 2000—Sex ratio	B-46

B-37.	Baccarelli et al., 2008—Neonatal thyroid function	B-48

B-38.	Alaluusua et al., 2004—Oral hygiene	B-49

B-39.	Bertazzi et al., 2001—Mortality (noncancer)	B-50

B-40.	Consonni et al., 2008—Mortality (noncancer)	B-52

B-41.	Baccarelli et al., 2005—Chloracne	B-53

B-42.	Baccarelli et al, 2002 and 2004—Immunological effects	B-54

B-43.	Revich et al., 2001—Mortality (noncancer) and reproductive health	B-55

B-44.	Michalek and Pavuk, 2008—Diabetes	B-56

B-45.	McBride et al., 2009a—Mortality (noncancer)	B-57

B-46.	McBride et al., 2009b—Mortality (noncancer)	B-59

B-47.	Ryan et al., 2002—Sex ratio	B-60

This document is a draft for review purposes only and does not constitute Agency policy.

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1	APPENDIX B. EVALUATION OF CANCER AND NONCANCER

2	EPIDEMIOLOGICAL STUDIES FOR INCLUSION IN TCDD

3	DOSE-RESPONSE ASSESSMENT

4

5

6	B.l. EVALUATION OF CANCER STUDIES

7	B.1.1. NIOSH Cohort Studies

8

9	Table B-l. Fingerhut et al., 1991—All cancer sites, site-specific analysis

10

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. The data sources to ascertain vital status and cause of death
information were the Social Security death files, the National Death Index, and the Internal
Revenue Service. Vital status could be determined for 98% of the cohort.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration not satisfied. While the authors provide compelling arguments that suggest
risks are not unduly biased by lack of cigarette smoking data, they acknowledge potential
biases that could exist for other occupational exposure (e.g., asbestos) for which data were
lacking.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration not satisfied. There was not a statistically significant linear trend of increasing
mortality with increased duration of exposure.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration not satisfied. This study used duration of exposure, at an individual level, as a
surrogate measure of TCDD. Duration of exposure determined by number of years workers
were involved in processes involving TCDD contamination. Exposure was determined by
reviewing, at each plant, operating conditions, job duties, records of TCDD levels in industrial
hygiene samples, intermediate reactants, products, and wastes. Exposure assessment was
limited and the uncertainty related to exposure measures not fully addressed.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied. This is the largest of the occupational cohorts that has been exposed
to TCDD. The cohort consisted of 5,172 workers and a total of 265 cancer deaths. Site-
specific mortality analyses, including soft tissue sarcoma (n = 4), was limited by small
numbers.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

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Response

Criteria satisfied. New England Journal of Medicine, 1991;324:212-218. Authors address
the possibility of bias from lack of control for potential confounders such as smoking and other
occupational exposures. They address limitations of using death certificates for identifying
certain causes of deaths, and limitations of using duration of employment as an exposure
metric.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria not satisfied. Since this study used duration of exposure as the exposure metric,
dose-response relationships cannot be quantified.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported
dose-is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined.

Response

Criteria satisfied. Models incorporated period of latency, and a surrogate measure of
cumulative TCDD exposure was modeled. The follow-up interval was sufficiently long
(1942-1987).





Conclusion

Overall, quantitative exposure data are lacking on an individual-level basis. Further
dose-response analysis should consider updated data for this cohort that includes serum-based
measures of TCDD, in addition to an extension of the follow-up period. Given these
limitations, this study is not further evaluated for TCDD dose-response assessment.

Table B-2. Steenland et al., 1999—All cancer sites combined, site-specific
analysis

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. The study evaluated mortality from all cancer sites (combined). As
described in the paper, the sources of vital status and cause of death information were received
from the Social Security death files, the National Death Index, and the Internal Revenue
Service. Vital status was known for 99.4% of the cohort members, cause of death information
is available for 98% of the decedents.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration satisfied. Occupational exposure to asbestos and 4-aminobiphenyl contributed
to some excess cancer, but no evidence of confounding for the relationship between TCDD
and all cancer mortality was detected following removal of workers who died of bladder
cancer. No information is available for cigarette smoking, although dose-response patterns
were stronger for nonsmoking related cancers. This finding suggests that smoking is not
responsible for excess cancer risk that was observed in the cohort.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

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Response

Consideration satisfied. When a 15-year lag interval was incorporated into the exposure
metric a statistically significant dose-response pattern was observed for all cancer sites
combined with both a continuous measure of TCDD (p = 0.05) as well as one that was
log-transformed (p < 0.001).

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration satisfied. The study conducted detailed sensitivity analyses and evaluated
different assumptions regarding latency, log-transformed TCDD exposures, and half-life
values for TCDD.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied. This is the largest of the occupational cohorts with exposures to
TCDD. The cohort consisted of 5,132 male workers and a total of 377 cancer deaths. This
permits characterization of risk for all cancer sites (combined).





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied. Journal of the National Cancer Institute, 1999; 91(9):779-786. The authors
discussed the potential for bias from smoking, and other occupational exposures for which
data for both were lacking at an individual basis.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria satisfied. Exposure scores assigned on an individual level using a job-exposure
matrix. The job-exposure matrix was based on estimated factor of contact with TCDD in each
job, level of TCCD contamination of materials at each plant over time, and proportion of day
worker could be in contact with materials. These factors were multiplied together to derive a
daily exposure score, which was accumulated over the working history of each worker to
obtain a cumulative measure of TCDD.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined.

Response

Criteria satisfied. The follow-up of the cohort extended from 1942 until the end of 1993.
Greater than 25 years of follow-up have accrued in cohort allowing for latency to be
examined. Different assumptions on the half-life of TCDD were evaluated and produced
similar results. Latency intervals were incorporated, with strongest associations noted with an
interval of 15 years.





Conclusion

This study meets the criteria and considerations noted above but has been superseded and
updated by Steenland et al. (2001). Therefore, this study was not considered for further
dose-response analyses.

1

2

3

4

5

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1	Table B-3. Steenland et al., 2001—All cancer sites combined

2

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. The study evaluated mortality from all cancer sites (combined). As
described by Steenland et al., (1999) the sources of vital status and cause of death information
were received from the Social Security death files, the National Death Index, and the Internal
Revenue Service. Vital status was known for 99.4% of the cohort members, cause of death
information is available for 98% of the decedents.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration satisfied. Occupational exposure to asbestos and 4-aminobiphenyl contributed
to some excess cancer, but no evidence of confounding for the relationship between TCDD
and all cancer mortality was detected following removal of workers who died of bladder
cancer. No information is available for cigarette smoking, although dose-response patterns
were similar between smoking and nonsmoking related cancers.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration satisfied. Increased risk estimates were observed in the higher cumulative
exposure categories. The dose-response curve was not linear at higher doses.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration satisfied.

Exposure metrics considered included cumulative TCDD, loglOTCDD, average exposure, and
a cubic spline model was also evaluated. Exposure response relationships were also evaluated
using TEQs. Exposure scores were assigned on an individual level using a job-exposure
matrix. The job-exposure matrix was based on estimated factor of contact with TCDD in each
job, level of TCCD contamination of materials at each plant over time, and proportion of day
worker could be in contact with materials. Serum levels were measured in 199 workers at one
of 8 plants in 1998. Different estimate of the half-life of TCDD were used, and similar results
were produced. The paper presented a range in risk estimates thereby conveying the range of
uncertainties in risk estimates derived using different measures of exposure.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied. This is the largest of the occupational cohorts with exposures to
TCDD. The cohort consisted of 3,538 male workers and a total of 256 cancer deaths.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied Am JEpidem, 2001, 154(5)451-458. However, additional details to assess
uncertainties associated with characterizing serum data in a subset of workers to remainder of
cohort are lacking.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

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Response

Criteria satisfied. The metrics considered included cumulative TCDD, loglOTCDD, average
exposure, and a cubic spline model was also evaluated. Exposure response relationships were
also evaluated using TEQs. Serum lipid TCDD measurements from 170 workers whose
TCDD levels were greater than 10 ppt (the upper ranges of a background level) were used
along with JEM information, work histories, and a pharmacokinetic elimination model to
estimate dose rates per unit exposure score. In this regression model, the estimated TCDD
level at the time of last exposure was modeled as a function of exposure scores. The
coefficient relating serum levels and exposure scores was then used to estimate serum TCDD
levels over time from occupational exposure (minus the background level) for all
3,538 workers. Time-specific serum levels were then integrated over time to derive a
cumulative serum lipid concentration due to occupational exposure for each worker.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined.

Response

Criteria satisfied. Greater than 25 years of follow-up have accrued in cohort allowing for
latency to be examined. Different assumptions on the half-life of TCDD were evaluated
producing similar results.





Conclusion

Overall, criteria have been satisfied. This study was modeled in the 2003 Reassessment and is
considered for further dose-response evaluations herein.

Table B-4. Cheng et al., 2006—All cancer sites combined

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. The study evaluated cancer mortality. The vital status and the
information regarding the cause of death were extracted from the Social Security death files,
the National Death Index, and the Internal Revenue Service (Steenland et al., 1999). Vital
status was known for 99.4% of the cohort members, while cause of death information is
available for 98% of the decedents.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration satisfied. This is the same data set used in the Steenland et al., (2001) paper.
Occupational exposure to asbestos and 4-aminobiphenyl contributed to some excess cancer,
but no evidence of confounding for the relationship between TCDD and all cancer mortality
was detected following removal of workers who died of bladder cancer. No information is
available for cigarette smoking, although dose-response patterns were similar between
smoking and nonsmoking related cancers.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration satisfied. Slope coefficients are available for all cancers combined under a
varying set of assumptions. Little evidence of an association was found when lag interval was
not taken into account. Associations strengthened with incorporation of a 10 to 15 year lag
interval. Dose-response was nonlinear at higher exposures, suggesting a nonlinear
relationship or increased exposure misclassification at higher levels.

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4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration satisfied. Compared to the 1st order models, the concentration, and age
dependent model (CADM) provided a better fit for the serum sampling data. CADM model
exposure estimates are higher than those based on an age only, constant 8.7-year half-life
model. As discussed by Aylward et al. (2005b), model exposure estimates are influenced not
only by choice of elimination model, but also by choices in regression procedure (e.g., log
transformation, use of intercept, and incorporation of background dose term). Other
limitations or uncertainties in exposure assessment include the following

•	Job-exposure matrix based on limited sampling data, and subjective judgment on contact
times and factors

•	Inability to take into account interindividual variability in TCDD elimination kinetics

•	Dose-rate regressions are based on a small sample of the cohort with serum measures;
therefore, regression results may not be representative of remainder of the cohort.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied. Largest cohort of TCDD exposed workers. The risk estimates are
based on a total of 256 cancer deaths.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied. Risk Analysis, 2006; 4:1,059-1,071. Additional details to assess
uncertainties associated with characterizing serum data can be found in Aylward et al.
(2005b); Risk Anal. 25(4):945-956.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria satisfied. Cumulative serum lipid concentrations were estimated for each worker. No
other dioxin-like compounds were assessed in this analysis.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined.

Response

Criteria satisfied. Concentration and age-dependence of TCDD elimination and
two compartments (hepatic and adipose tissue) were taken into account when estimating
TCDD exposures. Nearly 50 years of follow-up were available permitting an evaluation of
latency.





Conclusion

This study met the main criteria and considerations. The study is considered for further
dose-response analyses.

Table B-5. Collins et al., 2009—All cancer sites combined, site-specific
analysis

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

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Response

Consideration satisfied. Vital status complete for all but two workers.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration satisfied. No information collected on smoking status, but no excess in lung
cancer or nonmalignant respiratory diseases noted. Analyses took into account potential for
exposure to pentachlorophenol.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration satisfied. No dose-response pattern was observed with all cancer sites
combined, however, a dose-response pattern was observed with soft tissue sarcoma. The study
found no association between TCDD and death from most types of cancer.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration satisfied. The authors used these serum from 280 former TCP workers to
estimate historical exposure levels of TCDD, furans, and polychlorinated biphenyls for all
1,615 workers. Exposure assessment included detailed work history, industrial hygiene
monitoring, and the presence of chloracne cases among groups of workers. This data was
integrated into a 1-compartment, first-order pharmacokinetic to determine the average TCDD
dose associated with jobs in each group, after accounting for the presence of background
exposures estimated from the residual serum TCDD concentration in the sampled individuals.
The authors did not evaluate departures from linearity, or examine skewness at higher
exposures. Exposure levels were not provided.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied. Largest study of workers employed in one center, and a total of
177 deaths from cancer were observed. Limited precision in the relative risk estimate was
noted for soft tissue sarcoma and TCDD exposures.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied. Published in Am J Epidemiol, 2009, 170(4):501-506. The authors discuss
limitations of using death certificates for identifying deaths from soft tissue sarcoma for which
a positive association was noted, assumptions in exposure characterization, and effects of
cigarette smoking.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria satisfied. This study has the largest number of serum samples obtained from a specific
plant.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined.

Response

Criteria satisfied. Although specific analyses of latency were not reported, this cohort had a
sufficient Icnalh of follow-up for cnnccr mortality outcomes

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The authors found a statistically significant dose-response trend for soft tissue sarcoma
mortality and TCDD exposures. The all-tumor results are not amenable to dose-response
analysis because they found no effect. Therefore, this study is considered for quantitative
dose-response analysis for the soft tissue sarcoma mortality results, only.

1

2	B.1.2. BASF Cohort Studies

3

4	Table B-6. Zober et al., 1990—All cancer sites combined, site-specific

5	analysis

6

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. A large component of the cohort (94 out of 247 workers) was
assembled by actively seeking out workers who were alive in 1986 through the "Dioxin
Investigation Programme." As a result, it is likely a number of deaths were missed due to the
recruitment of survivors. This underascertainment is supported by much lower all cancer
SMR one component of the cohort (SMR = 0.48, 95% CI: 0.13-1.23) relative to the general
population.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration satisfied. See above discussion of underascertainment in mortality for some of
the cohort members. Although it is likely that other coexposures occurred (e.g., among
firefighters), confounding could only occur if these coexposures were associated with both the
endpoint and exposure (TCDD) being considered.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration not satisfied. Workers were not categorized on the basis of their exposure, but
rather their mortality experience compared to control cohort and the general population. The
design of the study does not allow for dose-response to be examined.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration not satisfied. Although years since first exposure was examined, exposure
assessment was based on working in various occupational cohorts. Since there was no
quantitative assignment of TCDD exposures, the associated uncertainties could not be
evaluated.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration not satisfied. There were only 23 cancer deaths in the entire cohort. As such,
this study lacked adequate statistical power to detect cancer mortality differences that were
moderate in magnitude.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

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Response

Criteria satisfied. Int Arch Occup Envir Health, 1990,62:139-157. The authors address
issues related to the healthy worker effect, multiple comparisons, smoking, and small size of
the cohort.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria not satisfied. Risks were derived by comparing mortality rates of the three cohort
subsets relative to a control cohort and the general population by time since first exposure
categories. Workers were not assigned exposures. There were no quantitative estimates of
TCDD exposure.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined.

Response

Criteria not satisfied. While the study was able to indirectly look at variations in risk estimates
related to latency by using time since exposure, there were no quantitative estimates of TCDD
exposure.





Conclusion

This study is not suitable for dose-response analysis, as it failed the inclusion criteria. Most
notably, the lack of exposure data does not permit the use of these data for a dose-response
analysis.

Table B-7. Ott and Zober, 1996—All cancer sites combined

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. Mortality ascertainment appeared to be fairly complete. The
ascertainment of cancer incidence is more difficult to judge as geographical area not covered
by a cancer registry.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration satisfied. Information was collected on smoking status, body mass index, and
other occupational exposures, however a large portion of the cohort was firefighters who may
have been exposed to other occupational carcinogens. However, the recruitment of survivors
may results in under-ascertainment of mortality.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration satisfied. Increased cancer incidence was observed in the highest TCDD
cumulative exposure category. Risks were most pronounced when a period of 20 years since
first exposure was incorporated into the model.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

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Response

Consideration satisfied. Cumulative measure of TCDD expressed was derived from serum
measures. Exposure was also estimated by chloracne status of the cohort members. The
authors have not addressed the potential implication of deriving TCDD exposure estimates for
the whole cohort using sera data that were available for only about half of the cohort.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied. For all cancer sites combined, there were 31 deaths. It is the smallest
of the occupational cohorts, but the deaths can be grouped into quartiles to allow for
evaluation of dose-response relationships.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied. Occupational and Environmental Medicine, 1996,53:606-612. A large
component of the cohort (94 out of 247 workers) was assembled by actively seeking out
workers who were alive in 1986 through the "Dioxin Investigation Programme." As a result,
it is likely a number of deaths were missed due to the recruitment of survivors. This
underascertainment is supported by much lower all cancer SMR one component of the cohort
(SMR = 0.48, 95% CI: 0.13-1.23) relative to the general population (Zober et al., 1990).

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria satisfied. Serum samples, taken in 1989, were available for 138 surviving workers out
of 254 and allowed for cumulative TCDD levels to be estimated using regression techniques in
the remainder of the cohort.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined.

Response

Criteria satisfied. Exposure assignment took into the affect that body mass index had on
TCDD half-lives. TCDD levels estimates through back-extrapolation of serum levels based on
half-life estimates obtained from previous studies. Latency was considered with stronger
association observed in external comparisons incorporating a latency of 20 years. The
follow-up of the cohort was lengthy (>50 years).





Conclusion

Given a part of the cohort was based solely on survivors in the in the mid-1980s, the SMR
statistic derived from this study underestimates excess mortality relative to the general
population. The cohort also includes some firefighters who are recognized to be exposed to
other carcinogenic agents—these exposures may be confounding the associations that were
reported. However, exposure to TCDD was quantified and the effective dose and oral
exposure estimable. Overall, criteria have been satisfied. This study was modeled in the 2003
Reassessment and is considered for further dose-response evaluations herein.

1

2

3

4

5

6

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1

2

3

4

5

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. Deaths were identified through medical records of the cohort
members. A review of death certificates of the identified cancer deaths found a high degree of
concordance (51/54). One of the 136 noncancer death certificates examined indicated an
"occult" neoplasm.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration satisfied. Smoking data were similar between exposed and nonexposed cohort
based on independent samples. Occupational exposure for which individual data are lacking
unlikely to explain dose-response with TCDD.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration satisfied. Dose-response patterns across three levels of exposure observed
among those who started work before 1954, and among those who worked for 20 years or
longer. Dose-response patterns not evident across whole cohort, among those with less than
20 years of employment, or among those who started after 1954.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration satisfied. Categorical exposures were based on TCDD concentrations in
precursor materials, products, waste, and soil from the plant grounds, measured after the plant
closed in 1984. Exposure uncertainty examined using a separate group of 48 workers who
provided adipose tissue samples. Other surrogate measures of exposure were considered in
this study, including duration of exposure and year of first employment.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied. For all cancer sites combined, there were 65 cancer deaths for the
comparison to the comparison cohort of gas workers. The study is underpowered to look at
site-specific cancers.





1 Ciilciia

Siud\ is published in I lie peei'-iv\ icuoil scientific lilci'.iliiiv and lias an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied. Lance,1 1991, 338:959-964. The authors discussed potential for
misclassification using death certificates, healthy worker effect and their related use of a
comparison cohort of gas supply workers, other occupational exposures present at the plant,
potential impact and the lack of smoking data.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria not satisfied. Exposure consisted of a large DLC component that was not quantified.
Given crude TCDD exposure categorization data, no quantitative exposure metric was derived.

This document is a draft for review purposes only and does not constitute Agency policy.

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B.1.3. The Hamburg Cohort

Table B-8. Manz et al., 1991—All cancer sites combined, site-specific
analyses


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3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined.

Response

Criteria satisfied. Exposure metrics were constructed that took into account duration of
exposure, and periods when exposure was highest. However, exposure estimates did not
consider lagged exposure.





Conclusion

This study is not amenable to further TCDD dose-response analysis and is not considered
further here because it consisted of a large DLC component that was quantified and no
quantitative exposure metric was derived. The dose-response patterns of risks observed across
the three exposure groups provide compelling support for an association between TCDD and
cancer mortality, particularly, given the associations observed when analyses restricted to
those who were hired when TCDD exposures were known to be much higher, and among
those who worked for at least 20 years. Subsequent studies improved the exposure assessment
through the use of serum measures.

Table B-9. Flesch-Janys et al., 1995; Flesch-Janys et al., 1996 erratum—All
cancer sites combined

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. Medical records used to identify deaths over the period 1952-1992.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration satisfied. Similarity in smoking rates between control cohort and the exposed
workers was similar based on independent surveys. Occupational exposures to benzene, and
dimethyl sulfate were unlikely to bias dose-response pattern observed as these exposures
occurred in production departments with low-medium levels of exposure.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration satisfied. Dose-response relationship observed across 6 exposure categories,
with the cohort of gas supply workers used as the referent.

4. Consideration

Consideration satisfied. Exposure assessment methodology is clear and adequately
characterizes individual-level exposures. The limitations and uncertainties in the exposure
assessment are considered.

Response

The exposure measure was an integrated TCDD concentration over time estimate that
back calculated TCDD exposures to the end of the employment. Categorical and continuous
TCDD exposures were examined in relation to the health outcome. These efforts improve the
exposure assessment of earlier studies.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied. For all cancer sites combined, there were 124 deaths in the exposed
cohort, and 283 in the cohort of gas supply workers. No site-specific cancers were examined
in this paper.

This document is a draft for review purposes only and does not constitute Agency policy.

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1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied. Am J Epidemiol, 1995, 1442:1165-1175. The authors discuss the potential
role of other occupational exposures (i.e., dimethyl sulfate, solvents, and benzene), smoking,
and suitability of the comparison cohort of gas supply workers.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria satisfied. Serum and adipose tissues were used to estimate TCDD exposure in
190 workers. A one-compartment first-order kinetic model was used to estimate exposure at
end of exposure for these workers. Regression methods were then used to estimates TCDD
exposures for all workers.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined.

Response

Criteria not satisfied. Exposure was based on half-life estimates from individuals with
repeated serum measures. Other dioxin-like compounds were considered with the TOTTEQ
exposure metric. No consideration, however, was given to latency or lagged exposures.





Conclusion

The exposure data used within this study are well-suited to a dose-response analysis given the
associations observed, the characterization of exposure using serum, and quality of
ascertainment of cancer outcomes. However, subsequent methods have been applied to the
cohort to derive different exposures to TCDD using area under the curve approaches, which
updates the analysis herein. Therefore, subsequent studies (i.e., Becher et al., 1998) will
supersede this evaluation.

Table B-10. Flesch-Janys et al., 1998—All cancer sites combined, site-
specific analysis

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. Mortality follow-up was extended until the end of 1992, an increase
in 3 years from previous analyses of the cohort.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration satisfied. Exposure was well characterized using sera data. While serum
samples provided only from a subsample of surviving workers, these levels were consistent
with expected levels in different production departments. The authors examined other
potential occupational coexposures (e.g., p-hexachlorocyclohexane) and indirectly examined
the potential effect of smoking on the associations that were detected.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

This document is a draft for review purposes only and does not constitute Agency policy.

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Response

Consideration satisfied. A dose-response relationship across quartiles of TCDD was observed
with cancer mortality based on the SMR statistic (SMRs = 1.24, 1.34, 1.34, 1.73), and a linear
test for trend was statistically significant (p = 0.01).

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration satisfied. The exposure measure was an integrated TCDD concentration over
time estimate that back-calculated TCDD exposures to the end of the employment.

Categorical and continuous TCDD exposures were examined in relation to the health outcome.
These efforts improve the exposure assessment of earlier studies.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied. For all cancer sites combined, there were 124 cancer deaths.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied. Environ Health Perspect, 1998, 106(2):655-662. The authors address
uncertainties in the estimation of exposure, describe the potential for confounding from
(3-2,4,5-T, hexachlorocyclohexane, and cigarette smoking. In fact, they showed that blood
levels of TCDD were not associated with smoking in a subsample suggesting little bias from
lack of smoking data.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria satisfied. Serum samples, taken from 190 workers were used to derive TCDD levels
for the entire cohort. Methods used to estimate exposure took into account elimination of
TCDD during employment periods when exposure took place, and the methods of the area
under the curve was used as it takes into account variations in concentration over time, and
reflects cumulative exposure.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined.

Response

Criteria satisfied. Exposure estimated based on half-lives observed in individuals with
repeated samples. Area under the curve approach was used which is an improvement from
past characterizations of exposure in this cohort.





Conclusion

The study provides data suitable for dose-response modeling. Derivation of exposure was
done using current understanding of elimination of TCDD. Estimates of risks were derived
from external comparisons to the general population that are unlikely to be biased by healthy
worker effect, but risks generated using internal cohort comparisons would be preferable.
Becher et al., (1998) assessed this same data taking cancer latency into account, therefore
Flesch-Janys et al., (1998) will not be further considered for dose-response modeling.

1

2

3

4

5

This document is a draft for review purposes only and does not constitute Agency policy.

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1	Table B-ll. Becher et al., 1998—All cancer sites combined

2

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. Medical records used to identify deaths over the period 1952-1992.
The follow-up interval was lengthy.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration satisfied. Risks adjusted for exposures to TEQ, (3-hexachlorbenzene, and
employment characteristics. Smoking was shown to be similar to the comparison cohort of
gas workers.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration satisfied. A variety of exposure measures for both TCDD and TEQs found
positive associations with cancer mortality.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration satisfied. The exposure measure was an integrated TCDD concentration over
time estimate that back-calculated TCDD exposures to the end of the employment.

Categorical and continuous TCDD exposures were examined in relation to the health outcome.
Different models explored the shape of the dose-response curve. These efforts improve the
exposure assessment of earlier studies.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied. For all cancer sites combined, there were 124 cancer deaths.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied. Environ Health Perspect, 1998, 106(2):663-670. The authors discuss
uncertainties associated with their use of exposure metrics, inability to evaluate effects for
PCDD/Fs other than dioxin due to high correlations with (3-HCH, and inability to characterize
risks associated with exposures in children.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria satisfied. The authors derived a measure of cumulative dose as a time-dependent
variable ("area under curve") using serum measures available in a sample of 275 workers.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined.

Response

Criteria satisfied. TCDD levels estimates through back-extrapolation of serum levels based on
half-life estimates obtained from previous studies. Latency was considered, and a variety of
exposure metrics including nonlinear relationships were evaluated.





This document is a draft for review purposes only and does not constitute Agency policy.

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In this paper, a variety of exposure metrics were found to be positively associated with cancer
mortality. The additional lifetime risk of cancer corresponded to a daily intake of lpg ranged
between .01 and 0.001. This study was modeled in the 2003 Reassessment and is considered
for further dose-response evaluations herein.

1	B.1.4. The Seveso Cohort Studies

2

3	Table B-12. Bertazzi et al., 2001—All cancer sites combined, site-specific

4	analyses

5

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. Mortality appears to be well captured from the vital statistics
registries in the region (99% complete). Vital status was ascertained using similar methods for
both the exposed and reference populations. Both cancer and noncancer mortality outcomes
were evaluated. Ideally, would have evaluated incident rather than decedent outcomes for
cancer.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration satisfied. Individual-level data on potential confounders (i.e., age, calendar
period, and gender) were adjusted for. Information from other independent surveys suggests
similarity between smoking behaviors across the regions. Comparison of cancer mortality
rates before the time of the accident between the regions also revealed no differences.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration satisfied (for all cancers combined). No statistically significant excesses noted
in Zone A, or Zone B relative to reference area. Evidence of an exposure-response
relationship was detected for lymphatic and hematopoietic tissues by number of years since
first exposure.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration not satisfied. Subjects were assigned to one of the zones (A, B, R, or reference)
based on official residence on the day of the accident or at entry into the area. Exposure
misclassification is likely and lack of individual-level data precludes an examination of this
source of error.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied. In total, 27, and 222, cancer deaths were found among residents of
Zones A, and B, respectively. This allowed examined of gender-specific effects.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

This document is a draft for review purposes only and does not constitute Agency policy.

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Response

Criteria satisfied. Am J Epidemiol, 2001 Jun 1; 153(11): 1031—1044. Authors discuss
completeness of mortality ascertainment, diagnostic accuracy of death certificates particularly
with respect to diabetes, limited available of blood dioxin measures that did not permit
estimation of TCDD dose on an individual-level basis.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria not satisfied. Individual-level exposure data are unavailable. Exposure based on place
of residence at time of the explosion. Soil sampling performed indicated considerable
variability in TCDD levels within each region. In addition, place of residency at time of
explosion does not ensure individuals were at their home around the time of the accident.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined.

Response

Criteria not satisfied. An ecological measure of exposure (region of residency at time of
accident) was used to categorize individuals according to their possible exposure. Latencies
were considered. While such an approach has value for identifying wherever excesses
occurred among highly exposed populations, it is not precise enough to conduct a quantitative
dose-response analysis.





Conclusion

The lack of individual-level exposure data precludes quantitative dose-response modeling
using these data.

Table B-13. Pesatori et al., 2003—All cancer sites combined, site-specific
analyses

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. Mortality was ascertained from 1977-1996, and, as reported in other
related manuscripts, appears to be well captured from the vital statistics registries in the region
(99% complete). Cancer incidence data was available from 1977-1991.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration satisfied. Individual-level data on potential confounders (i.e., age, calendar
period, and gender) were adjusted for.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration not satisfied. Although risk of all cancer mortality was not associated with zone
of residence, increased risk of cancer incidence was observed in Zone A. Among men, excess
lymphatic and hematopoietic cancer incidence was observed in Zone A (primarily to
non-Hodgkin's lymphoma). Soft tissues sarcoma cancer incidence was also associated with
residence in Zone R among males, but not the more highly exposed zones (A and B). Among
females living in Zones A and B, higher rates were observed for multiple myeloma (RR = 4.9,
95% CI = 1.5-16.1), cancer of the vagina (RR = 5.5, 95% CI = 1.3-23.8), and cancer of the
biliary tract (RR = 3.0, 95% CI = 1.1-8.2).

This document is a draft for review purposes only and does not constitute Agency policy.

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4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration not satisfied. Subjects were assigned to one of the zones (A, B, R, or reference)
based on official residence on the day of the accident or at entry into the area. Exposure
misclassification is likely and lack of individual-level data precludes an examination of this
source of error.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied for some endpoints, although several of the cancer specific mortality
results among women were based on very small number of deaths (i.e., <5).





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied. OccupEnvMed, 1998;55:126-131. Authors discuss limitations such as
residency-based exposure assignment, absence of smoking, differential and death certification
in exposed versus nonexposed areas.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria not satisfied. Individual-level exposure data are unavailable. Exposure based on place
of residence at time of the explosion. Soil sampling performed indicated considerable
variability in TCDD levels within each region. In addition, place of residency at time of
explosion does not ensure individuals were at their home around the time of the accident.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined.

Response

Criteria not satisfied. An ecological measure of exposure (region of residency at time of
accident) was used to categorize individuals according to their possible exposure. Latencies
were considered. While such an approach has value for identifying wherever excesses
occurred among highly exposed populations, it is not precise enough to conduct a quantitative
dose-response analysis.





Conclusion

No dose-response patterns evident in the study, and the study lacked quantifiable measures of
TCDD at an individual-level basis. The data are not well suited for dose-response analysis.

Table B-14. Consonni et al., 2008—All cancer sites combined, site-specific
analyses

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. Mortality appears to be well captured from the vital statistics
registries in the region (99% complete). Both cancer and noncancer mortality evaluated,
although diagnostic accuracy of death certificates is likely low. Ideally, would have evaluated
incident rather than decedent outcomes for cancer.

This document is a draft for review purposes only and does not constitute Agency policy.

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2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration satisfied. Individual-level data on potential confounders (i.e., age, calendar
period, and gender) were adjusted for. Comparison of cancer mortality rates before the time of
the accident between the regions also revealed no differences. Information from other
independent surveys suggests similarity between smoking behaviors across the regions.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration satisfied for some outcomes. For all cancer sites combined, no evidence of
dose-response was observed relative to general population across Zones A, B and R. Only
statistically significant excess found in Zone A was for chronic rheumatic disease but based on
only three deaths. Higher cancer excesses were found in Zone A after a latency period was
incorporated; however, no dose-response relationship observed with this latency period.
Evidence of an exposure-response relationship was detected for lymphatic and hematopoietic
tissues by zone of residence.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration not satisfied. Subjects were assigned to one of the zones (A, B, R, or reference)
based on official residence on the day of the accident or at entry into the area. Exposure
misclassification is likely and lack of individual-level data precludes an examination of this
source of error.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied. In total, 42, 244, and 1,848 cancer deaths were found among residents
of Zones A, B, and R respectively.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied. Am J Epidemiol, 2008, 167:847-858. Authors discuss potential for
selection bias, limitation of residential based measure of exposure, similarities of mortality
ascertainment in exposed and referent populations, and multiple testing.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria not satisfied. Individual-level exposure data are unavailable. Exposure based on place
of residence at time of the explosion. Soil sampling performed indicated considerable
variability in TCDD levels within each region. In addition, place of residency at time of
explosion does not ensure individuals were at their home around the time of the accident.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined.

Response

Criteria not satisfied. An ecological measure of exposure (region of residency at time of
accident) was used to categorize individuals according to their possible exposure. Latencies
were considered. While such an approach has value for identifying wherever excesses
occurred among highly exposed populations, it is not precise enough to conduct a quantitative
dose-response analysis.

This document is a draft for review purposes only and does not constitute Agency policy.

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Conclusion

The lack of individual-level exposure data precludes quantitative dose-response modeling
using these data.

Table B-15. Baccarelli et al., 2006—Site-specific analysis

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. Polymerase chain reaction (PCR) methods were used to describe
outcome measures. The prevalence of t(14; 18) was estimated as those individuals having a
t(14; 18) positive blood sample divided by the t(14; 18) frequency (number of copies per
million lymphocytes).

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration satisfied. Questionnaire data were used to collect information on cigarette
smoking. Other potential confounders (age, smoking status, and duration of smoking). In
addition, both exposure and outcome were objectively and accurately measured.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration was not satisfied. Associations were detected between the frequency of t(14;
18) and plasma TCDD levels as well as zone of residence at the time of the explosion. No
association was detected for these exposure measures and prevalence of t(14; 18). A dose-
response trend was detected for TCDD and the mean number of t(14; 18)
translocations/106 lymphocytes, however the relevance of t(14; 18) in lymphocytes to
non-Hodgkin's lymphoma is uncertain.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration satisfied. The authors highlight that exposure metrics represent both past and
current body burdens. They employ several different exposure metrics of TCDD: place of
residence (Zone A, B, R or reference), categorical serum measures, a linear term, log (base 10)
transformed TCDD, and individuals with chloracne diagnosed after the accident.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied. Analyses are made using 72 highly exposed, and 72 low exposed
individuals.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied. Carcinogenesis, 2006, 27(10):2001-2007. The authors discuss the
limitation of using t(14; 18) translocations as an outcome measure, and the uncertain role it
plays in the development of non-Hodgkin's lymphoma.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

This document is a draft for review purposes only and does not constitute Agency policy.

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Response

Criteria satisfied. A total of 144 subjects were included in the study. This included
72 subjects who had low exposures, and 72 who had high exposures based on serum
concentrations.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined.

Response

Criteria satisfied. A variety of measures were employed including current TCDD levels, as
well as surrogates of exposure at the time of the accident.





Conclusion

While an association was observed with the frequency of t(14; 18) translocation, it is uncertain
whether this translates into an increased risk of non-Hodgkin's lymphoma. Given the
speculative nature of this endpoint and lack of demonstrated adverse effect, dose-response
analyses for this outcome were not conducted.

Table B-16. Warner et al., 2002—Breast cancer incidence

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. Diagnoses of incident breast cancer were based on interview and
information from medical records appears thorough. Of the 15 cases of breast cancer, 13 were
confirmed by pathology and the remaining 2 by surgery report only. Three cases of breast
cancer were excluded which represents a large proportion of the total cases identified. This
would reduce sample size and could result in bias if the exclusion was association with TCDD
exposure.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration satisfied. Information was collected on an extensive series of risk factors by
using an interviewer administered questionnaire. Participation rates for the survey were fairly
good (80%).

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration satisfied. Limited evidence (not statistically significant) of a dose-response
when TCDD was analyzed as a categorical variable; only one breast cancer case was in the
referent exposure category. In the analysis of TCDD as a continuous measure (logi0TCDD),
the hazard ratio associated with a 10-fold increase in TCDD serum levels was 2.1
(95% CI: 1.0-4.6).

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration satisfied. Different exposure metrics were considered in these analyses
(categorical, continuous, measures on a log-scale). Exposure data are of high quality as they
are based on serum samples taken among women near the time of the accident. As such,
exposure assignment is not dependent on as many assumption as used in occupational cohorts
were back-extrapolation for many years had to be performed.

This document is a draft for review purposes only and does not constitute Agency policy.

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5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration somewhat satisfied. Inadequate follow-up for cancer limited the number of
cases available. Sample size also limited the conclusions draw from the categorical analysis
based on very few cases for some exposure categories.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied. Paper published in Environ Health Perspect, 2002 Jul, 110(7):625-628. A
major limitation of the study is the small number of incident cases of breast cancer (n = 15),
important strengths of the study include characterization of TCDD using serum collected near
the time of the accident.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria satisfied. Serum was used to estimate TCDD levels in 981 of 1271 eligible women
who had lived in either of the two contaminated sites in 1976. Data represent an objective
measure of TCDD near the time of the exposure. Data obtained near the time of exposure
which minimized the potential for exposure misclassification.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined.

Response

Criteria satisfied. Exposure characterized using serum measures obtained close to the time of
the accident.





Conclusion

While characterization of exposure and availability of other risk factor data at an
individual-level basis are important strengths of this study, small sample size (n= 15 cases)
based on inadequate follow-up is a key limitation. Quantitative dose-response analyses were
conducted using this study, but continued follow-up of the study population or consideration of
all cancer outcomes would be valuable.

1

2

3

4

5

6

7

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration cannot be evaluated. Insufficient details are provided in the paper to gauge the
completeness and coverage of the cancer registry and mortality data. Health outcomes were
studied on the basis of information in the official medical statistics.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration not satisfied. Given that this is an ecological study, bias may be present.

This document is a draft for review purposes only and does not constitute Agency policy.

B-22 DRAFT—DO NOT CITE OR QUOTE

B.1.5. The Chapaevsk Study

Table B-17. Revich et al., 2001—All cancer sites combined, and site-specific
analyses


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3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration cannot be evaluated. Dose-response was not evaluated as exposure was based on
residency in the region vs. no residency.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration not satisfied. No individual-level exposure estimates were used.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied. A total of 476 cancer deaths were observed among males, and 376
cancer deaths observed among females. The precision of the SMRs is demonstrated with fairly
narrow confidence intervals for many causes of death.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria not satisfied. Published in Chemosphere, 2001, 43(4-7):951-966. Authors do not
address the completeness of the mortality follow-up, and whether there are differences in death
registrations between regions. The authors do acknowledge, however, that new investigations
being undertaken would characterize exposure using serum-based measures.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria not satisfied. It is a cross-sectional study that compares mortality rates between
regions. No individual-level exposure data available.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of exposure
are consistent with the current biological understanding of dose. The reported dose is
consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined.

Response

Criteria not satisfied. No individual-level exposure estimates were used in the study.





Conclusion

These cancer data are cross-sectional in nature and not appropriate for a dose-response analysis.

B.1.6. The Air Force Health ("Ranch Hands") Study

Table B-18. Akhtar et al., 2004—All cancer sites combined and site-specific
analyses

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. Cancer incidence and mortality based on information from repeated
medical examinations, medical records and death certificate.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

This document is a draft for review purposes only and does not constitute Agency policy.

B-23 DRAFT—DO NOT CITE OR QUOTE


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Response

Consideration not satisfied. The risk estimates were adjusted for a number of factors
measured on an individual level including smoking. However, analyses are unable to
distinguish between exposure to TCDD and 2,4-D as both were used in equal parts in the
formulation of Agent Orange.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration satisfied. There is evidence of a dose-response for all cancers and for some
site-specific cancers (i.e., malignant melanoma, and prostate cancer).

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration satisfied. High quality exposure data for most veterans was collected, so
extrapolation to other members of the cohort was not required. The serum dioxin
measurements also correlated well with reported skin exposure to herbicide in Vietnam, but
collection of the samples 25 years later required back-extrapolation.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied. In total, 117 incidence cancers identified in the Ranch Hands cohort.
For those sites with a dose-response association, malignant melanoma and prostate cancer,
there were 16 and 34 incident cases, respectively.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied. Published in J Occup Environ Med, 2004, 46(2): 123-136. Authors
highlight that this is only cancer incidence study in US veterans, and the lengthy interval of
follow-up (35-40 years)—both important strengths of the study. They addressed potential
bias from healthy-worker effect, and uncertainties surrounding the estimation of TCDD
exposure (extrapolation 30 years after exposure), as well as exposure to other chemical
exposures. Study uses incident outcomes for cancer.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria satisfied. Individual exposure estimates are based on measurements of dioxin serum
lipid concentrations. They were available for 1,009 Ranch Hands and 1,429 in the
comparison cohort.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined.

Response

Criteria satisfied. TCDD exposures at the end of duty were estimated by back-extrapolating
1987 serum values.





Conclusion

The major limitation of the study is the inability to isolate effects of TCDD from other
chemicals used in the formulation of the herbicides. This limitation precludes dose-response
modeling of the TCDD and cancer outcomes data.

1

2

3

This document is a draft for review purposes only and does not constitute Agency policy.

B-24 DRAFT—DO NOT CITE OR QUOTE


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1	Table B-19. Michalek and Pavuk, 2008—All cancer sites combined

2

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. Cancer incidence was ascertained through the use of medical records.
Death certificate were used to identify some malignancies. Little data is provided on the
number of individuals lost to follow-up, however the same mechanisms of case ascertainment
were applied to both the comparison and Ranch Hand cohorts.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration not satisfied. Information collected from repeated physical examinations
allowed for the adjustment of risk factors such as smoking. Agent Orange was a 50% mixture
of 2,4-D and TCDD; therefore, potential for confounding by other coexposures is likely.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration satisfied for some comparisons. Statistically significant associations were
noted with cancer incidence and TCDD when analyses were restricted to workers who served
at most two years in Southeast Asia and those who sprayed more than 30 days before 1967.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration satisfied. Initial TCDD dose were estimated at the end of the tour of duty for
the Ranch Hands. Individual-level serum dioxin measurements correlated well with
correlated with days of spraying and calendar period of service, but collection of the samples
roughly 20 years later required back-extrapolation.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied. A total of 347 incident cases of cancer were used in the analyses.
For stratified analyses, statistical power is more limited. For example, only 67 incident
cancer in the subset of workers who spent less than 2 years in Southeast Asia, and sprayed for
at least 30 days before 1967.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied J Occup Environ Med 2008; 50:330-340. The authors discuss issues related
to exposure misclassification error, and suggest approaches for improving characterization of
days of spraying. Congener specific data were unavailable, thereby not allowing for congener
specific risks or adjustments to be made.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria satisfied. TCDD data was available for 986 veterans in the Ranch Hand cohort, and
1,597 members of the comparison cohort.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined.

This document is a draft for review purposes only and does not constitute Agency policy.

B-25 DRAFT—DO NOT CITE OR QUOTE


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Response

Criteria satisfied. TCDD exposures at the end of duty were estimated by back-extrapolating
1987 serum values.





Conclusion

Ranch Hand veterans were exposed to other contaminants in the herbicides that were mixed,
thereby making it difficult to determine independent effects of TCDD on cancer. In
particular, 2,4-D has been shown to be associated with some cancers, notable cancer of the
prostate. This limitation precludes dose-response modeling of TCDD and cancer using data
from this cohort.

1

2

3

4

5

6

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. National records for death registrations through the New
Zealand Health Information Service (NZHIS). Subjects not registered as having died during
the study period were confirmed to be actually alive and resident in New Zealand using the
New Zealand Electoral Roll, drivers' license, and social security records.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration not satisfied. Seventeen percent of workers were lost to follow up but it is
unclear if bias resulted. The dichotomous exposure measure was based on exposure to
TCDD, chlorinated dioxins and phenoxy herbicides, so confounding is a possibility by these
coexposures.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration satisfied. Dose-response evidence for duration of employment and elevated
mortality noted only in synthesis workers.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Exposure measures were limited to duration of employment and exposed/unexposed.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied. For all cancer sites combined, there were 43 cancer deaths among the
production workers, and 35 such deaths among the sprayers. Site-specific cancer analyses are
limited by small sample sizes.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria not satisfied Occup Env Med, 2005; 62:34-40. A high percentage of the cohort was
lost to follow-up (17%). The authors fail to mention this important limitation in this paper.

This document is a draft for review purposes only and does not constitute Agency policy.

B-26 DRAFT—DO NOT CITE OR QUOTE

B.1.7. Other Studies of Potential Relevance to Dose-Response Modeling

Table B-20. 't Mannetje et al., 2005—All cancer sites combined, site specific
analyses


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2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria not satisfied. This study used duration of exposure, at an individual level, as a
surrogate measure of TCDD.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined.

Response

Criteria not satisfied. Exposure was defined according to duration, and not concentrations of
TCDD. Latency intervals were not evaluated.





Conclusion

Overall, quantitative exposure data are lacking for TCDD and limited dose-response
relationships were observed across duration of exposure categories. Furthermore,
confounding by coexposures is a possibility. Taken together, these data are not suitable for
inclusion in a dose-response analysis

Table B-21. McBride et al., 2009b—All cancer sites combined, site-specific
analysis

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. The New Zealand Health Information Service Mortality Collection
and the Registrar-General's Index to Deaths. Additional searches were based on the last
known address from the work record; the electoral roll and the habitation index; the telephone
book; the internet; and Terranet property information database. An additional search was
carried out through the Births, Deaths, and Marriages office of the New Zealand Department
of Internal Affairs. Lastly, automated personnel and pension records were also used to locate
past New Plymouth workers and identify some deaths.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration not satisfied. Considerable amount of workers were lost to follow up (22%), but
it is unclear if bias resulted. The dichotomous exposure measure was based on exposure to
TCDD, chlorinated dioxins and phenoxy herbicides, so confounding is a possibility by these
coexposures.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration not satisfied. There was no examination of dose-response effects.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration satisfied. Dichotomous exposure (exposed/unexposed) and duration of
employment were examined from job exposure classification assessed via occupational history
records industrial hygienists/factory personnel knowledge and questionnaires. Authors discuss
limitations in the assignment of exposure among cohort members.

This document is a draft for review purposes only and does not constitute Agency policy.

B-27 DRAFT—DO NOT CITE OR QUOTE


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5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration not satisfied. A low number of deaths (n = 16) may have limited ability to
detect effects small in magnitude and exposure-response relationships.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied. Published in Occup Medicine, 2009; 59(4):255-263. The authors highlight
cohort lost to follow-up, the limited size of the cohort, differences in cohort definitions
between sprayers and producers, and the potential for other exposures during employment at
the plant.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria not satisfied. TCDD exposures were not quantified.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined.

Response

Criteria not satisfied. Effective dose could not be estimated given the lack of individual-level
exposure data.





Conclusion

The study lacks the quantification of exposures at an individual level, precluding dose-
response analysis. This study is not considered further in the dose-response modeling analysis.

Table B-22. McBride et al., 2009a—All cancer sites combined, site-specific
analysis

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. The New Zealand Health Information Service Mortality Collection
and the Registrar-General's Index to Deaths were used to identify deaths. Additional searches
were based on the last known address from the work record; the electoral roll and the
habitation index; the telephone book; the internet; and several other public databases in New
Zealand. An additional search was carried out through the Births, Deaths, and Marriages
office of the New Zealand Department of Internal Affairs. Lastly, automated personnel and
pension records were also used to locate past New Plymouth workers and identify some
deaths.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration satisfied. Workers lost to follow-up were an unlikely source of bias especially
for internal analyses. Confounding by other coexposures (e.g., 2,4,6-TCP) unlikely to have
resulted in bias, due to presumed poor correlation with TCDD.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

This document is a draft for review purposes only and does not constitute Agency policy.

B-28 DRAFT—DO NOT CITE OR QUOTE


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Response

Consideration not satisfied. The linear test for trend for TCDD exposure was not statistically
significant for all cancer sites (combined), as well as lung cancer mortality. Dose-response
relationships were not apparent across quartiles of TCDD exposure for all cancer sites
combined, digestive cancers, lung cancer, soft tissue sarcomas or non-Hodgkin's Lymphoma.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration satisfied. Cumulative exposure to TCDD as a time-dependent metric was
estimated for each worker from serum samples, but the authors did not examine a continuous
measure of TCDD exposure (lagged orunlagged).

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied. Published in J Occup Environ Med 51:1049-1056. This paper discussed the
22% of the cohort lost to follow-up, differences in cohort definitions between sprayers and
producers, and the potential for other exposures during employment at the plant.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria satisfied. Serum measures available for 346 workers were used to derive TCDD
exposures for the entire cohort using the area under the curve approach.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined.

Response

Criteria satisfied. Effective dose could be estimated from serum-derived cumulative exposure
estimates.





Conclusion

Given that no dose-response associations were found, the data are not suited to dose-response
analysis.

Table B-23. Hooiveld et al., 1998—All cancer sites combined, site-specific
analysis

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. Outcomes were mortality. Few deaths expected to be missed since
only 5% of the cohort was lost to follow-up or had emigrated.

This document is a draft for review purposes only and does not constitute Agency policy.

B-29 DRAFT—DO NOT CITE OR QUOTE


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2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration not satisfied. Although dioxin-like compounds (PCDDs, PCDFs, and PCBs)
were measured in the serum samples, these were not incorporated into the analysis. Therefore,
confounding cannot be ruled out as an explanation of the reported association.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration satisfied. A dose-response pattern was observed for internal cohort comparison
for all cancer mortality, with RRs of 5.0 and 5.6 for the medium and high exposure,
respectively. Dose-response patterns evident for lung cancer as well.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration satisfied. Detailed occupational histories to assign dichotomous exposures
(exposed/unexposed) based on maximum exposure levels. Although serum data also collected
for TCDD and other coexposures (PCDDs, PCDFs, and PCBs), study only presents data for
TCDD exposure. TCDD exposures at time of maximum exposure were extrapolated from
measured serum.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration not satisfied for internal cohort comparisons in either men or women. Among
men, only 7 cancer deaths were observed among those in the unexposed part of the cohort, and
51 among exposed workers. For external cohort comparisons, a total of 20 deaths were
observed.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied. Am J Epidemiol, 1998, 147:891-901. The authors address potential
limitations of estimating TCDD exposure from a subsample of surviving workers, lack of
smoking data, the healthy worker effect, and relevance of other occupational exposures.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria satisfied. Serum samples were obtained from 94 of 144 subjects who were asked to
participate in serum measurement study. Of these, a further 44 excluded due to absence due to
holiday or work (n = 22), and nonexposed workers excluded because matching exposed
worker not participating (n = 20). TCDD levels were extrapolated to the time of maximum
exposure.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined.

Response

Criteria not satisfied. Exposures assigned based on levels at maximum exposure. Assignment
of exposure based on nonrepresentative sample of 50 survivors among the occupational cohort.





Conclusion

The small number of identified cancer deaths, limitations in terms of the exposure assignment
(based on nonrepresentative sample, and maximum exposure level) and concern over potential
confounding by coexposures preclude using these data for a dose-response analysis.

This document is a draft for review purposes only and does not constitute Agency policy.

B-30 DRAFT—DO NOT CITE OR QUOTE


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1	B.2. EVALUATION OF NONCANCER STUDIES

2	B.2.1. NIOSH Cohort

3

4	Table B-24. Steenland et al., 1999—Mortality (noncancer)

5

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. The study evaluated mortality from all cancer sites (combined). As
described in the paper, the sources of vital status and cause of death information were received
from the Social Security death files, the National Death Index, and the Internal Revenue
Service. Vital status was known for 99.4% of the cohort members, cause of death information
is available for 98% of the decedents.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration not satisfied. External comparisons for all-cause and cardiovascular mortality
do not appear to be affected by the "healthy worker effect" as similar patterns were observed
with internal cohort comparisons. Nonetheless, internal cohort comparisons are unable to
adjust for many of the individual-level risk factors for cardiovascular disease.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration satisfied. A dose-response relationship was observed with ischemic heart
disease (linear test for trendp = 0.05), and with TCDD on a log-transformed scale the p-valuc
was <0.001.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration satisfied. The study conducted detailed sensitivity analyses and evaluated
different assumptions regarding latency, log-transformed TCDD exposures, and half-life
values for TCDD. Associations were stronger for log-transformed values, and latency
intervals of 15 years.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied. This is the largest of the occupational cohorts with exposures to
TCDD. The cohort consisted of 5,132 male workers and a total of 456 deaths from ischemic
heart disease. This permits characterization of risk for all cancer sites (combined).





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied Journal of the National Cancer Institute, 1999, 91(9):779-786. The authors
discussed the potential for bias from smoking, and other occupational exposures for which
data for both were lacking at an individual basis.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

This document is a draft for review purposes only and does not constitute Agency policy.

B-31 DRAFT—DO NOT CITE OR QUOTE


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Response

Criteria not satisfied. Exposure scores assigned at an individual level based on job-exposure
matrix (JEM). The JEM was based on estimated factor of contact with TCDD in each job,
level of TCCD contamination of materials at each plant over time, and proportion of day
worker could be in contact with materials. These factors were multiplied together to derive a
daily exposure score, which was accumulated over the working history of each worker to
obtain a cumulative measure of TCDD.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined. Response has to be a nonfatal endpoint.

Response

Criteria not satisfied. The follow-up of the cohort extended from 1942 until the end of 1993.
Greater than 25 years of follow-up have accrued in cohort allowing for latency to be
examined. Different assumptions on the half-life of TCDD were evaluated and produced
similar results. Latency intervals were incorporated, with strongest associations noted no lag.
Suggests mechanisms occur at the same time as exposure. However, noncancer mortality is
ik»I a \ iable endpoiiil U» consider for (mllier dose-response anaUsis

Conclusion

TCDD exposures were quantified in this study, and a dose-response relationship was observed
with ischemic heart disease mortality. The sample size was sufficient, and the follow-up
interval was lengthy. However, no individual-level data were available for cardiovascular
conditions, and the inability to adjust for these exposures introduces considerable uncertainty
into the risk estimates. Furthermore, noncancer mortality is not considered a viable endpoint
for dose-response analysis.

Table B-25. Collins et al., 2009—Mortality (noncancer)

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. Vital status complete for all but two workers.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration satisfied. No information collected on smoking status, but no excess in lung
cancer or nonmalignant respiratory diseases noted. Analyses took into account potential for
exposure to pentachlorophenol. External cohort comparisons should be interpreted cautiously
due to healthy worker effect, but internal cohort comparisons should not be influence by this
bias.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration not satisfied. No statistically significant mortality excess for any noncancer
mortality outcome evaluated. This included ischemic heart disease, stroke, nonmalignant
respiratory disease, ulcers, cirrhosis, and external causes of death (accidents). Modeling of
continuous measure of TCDD was not related to diabetes, ischemic heart disease, or
nonmalignant respiratory mortality.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

This document is a draft for review purposes only and does not constitute Agency policy.

B-32 DRAFT—DO NOT CITE OR QUOTE


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Response

Consideration satisfied. The authors used these serum from 280 former TCP workers to
estimate historical exposure levels of TCDD, furans, and polychlorinated biphenyls for all
1,615 workers. Exposure assessment included detailed work history, industrial hygiene
monitoring, and the presence of chloracne cases among groups of workers. This data was
integrated into a 1-compartment, first-order pharmacokinetic to determine the average TCDD
dose associated with jobs in each group, after accounting for the presence of background
exposures estimated from the residual serum TCDD concentration in the sampled individuals.
The authors did not evaluate departures from linearity, or examine skewness at higher
exposures. No presentation of exposure levels was provided.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied. A total of 662 deaths were observed. Of these, 218 were from
ischemic heart disease, and 16 from diabetes (two outcomes for which associations have been
noted elsewhere).





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied. Published in Am J Epidemiol, 2009, 170(4):501-506. The authors discuss
potential for exposure misclassification, large size of the cohort, lengthy follow-up interval,
and large number of workers who provided serum from which TCDD exposures were
estimated.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria satisfied. This study has the greatest number of serum samples obtained from a
specific plant.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined. Response has to be a nonfatal endpoint.

Response

Criteria not satisfied. Noncancer mortality is not a viable endpoint to consider for further
dose-response analysis.





Conclusions

No dose-response associations were noted for noncancer mortality outcomes. The data are,
therefore, not suited for dose-response modeling.

B.2.2. BASF Cohort

Table B-26. Ott and Zober, 1996—Mortality (noncancer)

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. Mortality ascertainment appeared to be fairly complete.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

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Response

Consideration satisfied. Information was collected on smoking status, body mass index, and
other occupational exposures, however a large portion of the cohort was firefighters who may
have been exposed to other occupational carcinogens. However, the recruitment of survivors
may results in under-ascertainment of mortality.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration not satisfied. For external cohort comparisons across the three TCDD exposure
categories, there was no dose-response pattern observed for any of the noncancer causes of
death. Cox regression risk estimates for all cause or circulatory disease mortality when TCDD
was modeled as a continuous variable were not statistically significant.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration satisfied. Cumulative measure of TCDD expressed was derived from serum
measures. Exposure was also estimated by chloracne status of the cohort members. The
authors have not addressed the potential implication of deriving TCDD exposure estimates for
the whole cohort using sera data that were available for only about half of the cohort.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied. For all causes of death, there were 92 deaths, while 37 circulatory
deaths. Many of the cause-specific death had less than 5 deaths in the upper exposure
category.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied. Occup Environ Med, 1996, 53:606-612. A large component of the cohort
was assembled by actively seeking out workers who were alive in the mid 1980s. As a result,
it is likely a number of deaths were missed. This is supported by much lower SMRs in this
component of the cohort published in earlier studies of the cohort. This underascertainment of
mortality results in biased SMR statistics (underestimated). The authors do highlight the value
of the serum based measures to estimate TCDD exposure

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria satisfied. Serum samples, taken in 1989, were available for 138 surviving workers out
of 254 and allowed for cumulative TCDD levels to be estimated using regression techniques in
the remainder of the cohort.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined. Response has to be a nonfatal endpoint.

Response

Criteria not satisfied. Exposure assignment took into the affect that body mass index had on
TCDD half-lives. TCDD levels estimates through back-extrapolation of serum levels based on
half-life estimates obtained from previous studies. Latency was considered with stronger
association observed in external comparisons incorporating a latency of 20 years. The follow-
up of the cohort was lengthy (>50 years). However, noncancer mortality is not a viable
endpoint to consider for further dose-response analysis.





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No associations noted with any noncancer deaths. External comparisons should be treated
cautiously especially for cardiovascular mortality which is recognized to often be biased by
the healthy-worker effect. In the absence of any outcome with an association with TCDD
exposure, dose-response analyses of these data were not undertaken.

1	B.2.3. Hamburg Cohort

2

3	Table B-27. Flesch-Janys et al., 1995; Flesch-Janys et al., 1996 erratum—

4	Mortality (noncancer)

5

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. Medical records used to identify deaths over the period 1952-1992.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration satisfied. Similarity in smoking rates between control cohort and the exposed
workers was similar based on independent surveys. Occupational exposures to benzene, and
dimethyl sulfate were unlikely to bias dose-response pattern observed as these exposures
occurred in production departments with low to medium levels of TCDD exposure.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration satisfied. Dose-response relationship observed for all-cause mortality,
cardiovascular mortality, and ischemic heart disease mortality across 6 exposure categories,
with the cohort of gas supply workers used as the referent. The linear tests for trend for these
three outcomes were all statistically significant (p < 0.05).

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration satisfied. The exposure measures was an integrated TCDD concentration over
time estimate that back-calculated TCDD exposures to the end of the employment.

Categorical and continuous TCDD exposures were examined in relation to the health outcome.
These efforts improve the exposure assessment of earlier studies.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied. For all causes of death combined, there were 414 deaths in the
exposed cohort, and 943 in the cohort of gas supply workers. A total of 157 and 76 deaths
from cardiovascular disease, and ischemic heart disease were noted. The corresponding
number in the cohort of gas supply workers was 459, and 205, respectively.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied. Am J Epidemiol, 1995, 1442:1165-1175. The authors discuss the potential
role of other occupational exposures (i.e., dimethyl sulfate, solvents, benzene), smoking, and
suitability of the comparison cohort of gas supply workers.

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2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria satisfied. Serum and adipose tissues were used to estimate TCDD exposure in
190 workers. A one-compartment first-order kinetic model was used to estimate exposure at
end of exposure for these workers. Regression methods were then used to estimates TCDD
exposures for all workers.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined. Response has to be a nonfatal endpoint.

Response

Criteria not satisfied. Exposure based on half-life estimates from individuals with repeated
serum measures. Other dioxin-like compounds were considered with the TOTTEQ exposure
metric. Noncancer mortality, however, is not a viable endpoint to consider for further dose-
response analysis.





Conclusion

Although, the exposure data used within this study are well-suited to a dose-response analysis
for all-cause and cardiovascular mortality given the associations observed, use of noncancer
mortality endpoint is not amenable for further dose-response analysis.

1	B.2.4. The Seveso Women's Health Study

2

3	Table B-28. Eskenazi et al., 2002a—Menstrual cycle characteristics

4

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. Information was also obtained from medical records for all obstetric
and gynecologic conditions. Information on menstrual cycles was obtained from
questionnaires. Women were asked about length of cycles, regularity, how many days flow
lasted, and heaviness of menstrual flow (scanty, moderate, or heavy). Measurement error is
likely for the subjective nature of self-reported menstrual parameters but specificity and
sensitivity is difficult to ascertain due to lack of validation data for these measures.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration satisfied. Detailed risk factor information was collected from questionnaire,
allowing for the potential confounding influence of many risk factors to be controlled for. The
length of cycle study findings may have been affected by the presence of a few outliers.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration satisfied. A positive dose-response relationship was found with TCDD among
women who were premenarcheal at time of the explosion and longer menstrual cycle. Increased
TCDD resulted in a reduced odds of scanty menstrual flow. No association was noted with
these two outcomes among postmenarcheal women. A decreased risk of irregular cycles was
observed with higher TCDD levels.

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4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Criteria satisfied. Serum concentrations of TCDD offer improved exposure assessment,
although delineating the critical exposure window is challenging given the nature of the very
high initial exposure.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure adequate
statistical power.

Response

Consideration satisfied. Cohort was large enough as analyses were conducted on 301 women.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion of
the strengths and limitations.

Response

Criteria satisfied. Am J Epidemiol, 2002; 156(4) 383-392. Limitations included an inability to
assess affects on menstrual cycle at time body burdens were the highest (at time of the
accident). Also, TCDD was estimated for 1976, not concurrent with their cycles in the previous
year, and a large number of women were excluded due to intrauterine device or oral
contraceptive use. Strengths included population-based nature of study, with characterization
of exposure using serum, and levels of other polychlorinated dibenzo-p-dioxins and
dibenzofurans were at background levels. Findings for length of menstrual cycle may be
unduly influenced by the presence of some outliers.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria satisfied. The study population was based on 301 women as those who were over the
age of 44 were excluded, as well as women with surgical of natural menopause, women with
Turner's syndrome, those who had been pregnant or breastfed in the past year, and those who
had used an intrauterine device or oral contraceptives. For 272 women, TCDD levels were
based on serum data provided in 1976; TCDD levels were back-extrapolated to 1976 levels for
the other 29 women.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of exposure
are consistent with the current biological understanding of dose. The reported dose is consistent
with a toxicologically relevant dose. Latency and appropriate window(s) of exposure
examined. Response had to be a nonfatal endpoint.

Response

Criteria satisfied. Ideally, TCDD exposures would be concurrent with reporting of cycle
characteristics. Herein, TCDD exposures were based on levels in 1976; however, given the
long half-life of TCDD and the same follow-up interval for all women, TCDD exposures in
1976 should correlate well with levels near the time of interview. Further, the critical window
of exposure can be estimated for the women that were premenarcheal at the time of the accident
(13 years).





Conclusion

This study meets all of the criteria and considerations for further dose-response analysis. The
determination of the relevant time interval over which TCDD dose should be considered is
uncertain.

1

2

3

4

5

6

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1	Table B-29. Eskenazi et al., 2002b—Endometriosis

2

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration not satisfied. Results of a pilot study showed that ultrasounds had excellent
specificity and sensitivity for ovarian endometriosis.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design or
statistical analysis.

Response

Consideration not satisfied. More than half of the women were classified as 'uncertain' with
respect to endometriosis disease status.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of an
exposure-response relationship.

Response

Consideration not satisfied. While an increased risk of endometriosis was observed across the
3 TCDD categories, these risks were not statistically significant relative to the lowest exposure
category. The test for trend based on a continuous measure (logi0TCDD) was also not statistically
significant.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Criteria satisfied. Serum concentrations of TCDD offer improved exposure assessment, although
delineating the critical exposure window is challenging given the nature of the very high initial
exposure.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure adequate
statistical power.

Response

Consideration not satisfied. Only a total of 19 cases of endometriosis were identified.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion of
the strengths and limitations.

Response

Criteria satisfied. Environ Health Perspect 2002; 110(7)629-634. Author's highlight that this is
the first study to examine the relationship between TCDD and endometriosis, and the availability
of sera data to estimate TCDD levels. Limitations included the small number of women with
endometriosis, and inability to confirm disease status using laparoscopy. Finally, young women
may have been underrepresented due to cultural difficulties in examining women who had never
been sexually active.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response relationships
can be assessed.

Response

Criteria satisfied. Eligible study subjects were women between 1 month and 40 years of age at
time of accident. These analyses excluded virgins, those with Turner's syndrome, and women
who refused the examination of ultrasound. Serum data were available for the 601 participants on
which the analyses are based. Of these, 559 had serum measures taken in 1976/77, 25 between
1978 and 1981, and 17 women in 1996.

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3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of exposure
are consistent with the current biological understanding of dose. The reported dose is consistent
with a toxicologically relevant dose. Latency and appropriate window(s) of exposure examined.
Response has to be a nonfatal endpoint.

Response

Criteria not satisfied. TCDD exposure was estimated at the time of "conception attempt" using
serum measures, with extrapolation from 1976 levels using half-life assumptions. It is difficult to
identify the relevant time interval over which TCDD dose should be considered for dose-response
analysis. The critical window of exposure is unknown.





Conclusion

The lack of a statistically significant association coupled with a large number of women for which
endometriosis disease status was "uncertain", precludes the use of these data to conduct dose-
response analysis.

1

2

3	Table B-30. Eskenazi et al., 2003—Birth outcomes

4

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration not satisfied. Outcomes were identified through self-reported questionnaires.
Women were found to over-report birth weight, and have a tendency to underreport birth
defects in children. As a large number of women in Seveso underwent voluntary abortion in
the first year after the explosion, an awareness bias may have contributed to differential
reporting of pregnancy histories.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration not satisfied. See above.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration not satisfied. There was no association between spontaneous abortions and
logioTCDD, or with births small for gestational age. An inverse association with birth weight
was noted in first eight years following the accident as were the number of births small for
gestational age; however, none achieved statistical significance atp< 0.05.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Criteria satisfied. Serum concentrations of TCDD offer improved exposure assessment,
although delineating the critical exposure window is challenging given the nature of the very
high initial exposure.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied. For spontaneous abortions there were 769 pregnancies. Fetal growth
and gestational age analysis was carried out on 608 singleton births that occurred post-
explosion.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

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Response

Criteria satisfied. Environ Health Perspect, 2003, lll(7):947-953. The authors highlight
potential limitation of reliance on self-reported data to ascertain pregnancy outcomes. They
also address the relevance of paternal exposures to TCDD on the developing fetus—such
exposure data were not considered in this study.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria satisfied. A total of 745 women in the SWHS had reported getting pregnant, of these
510 women were pregnant after the explosion (888 pregnancies). Analyses of spontaneous
abortions based on 476 women (excludes those with voluntary abortion, ectopic pregnancy, or
molar pregnancy). TCDD measured for 413 women in 1976/77, 12 women between 1978 and
1981, and 1996 for 19 women.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined. Response has to be a nonfatal endpoint.

Response

Criteria not satisfied. TCDD exposures were extrapolated to 1976 values. However, it is
difficult to identify the relevant time interval over which TCDD dose should be considered for
dose-response analysis.





Conclusion

The findings of the study are somewhat limited due to the reliance on self-reported information
for pregnancy outcomes, and lack of paternal exposures. The findings were not statistically
significant. Considered together, quantitative dose-response analyses for this study population
were not undertaken.

Table B-31. Warner et al., 2004—Age at menarche

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. In this study age at menarche was based on retrospective recall 5 to
19 years before the interview. Previous work suggests moderate to high correlations between
actual and recalled menarche, misclassification of outcome would bias risk estimates towards
the null (assuming nondifferential misclassification).

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration satisfied. Data collected from self-reported questionnaires allow for the
potential confounding influence of many risk factors to be taken into account. Some
misclassification of outcome may bias risk estimates towards the null.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration not satisfied. There was no association between TCDD levels and the age at
menarche with either the continuous or categorical measures of TCDD.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

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Response

Criteria satisfied. Serum concentrations of TCDD offer improved exposure assessment,
although delineating the critical exposure window is challenging given the nature of the very
high initial exposure.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied. Cohort was large enough as analyses were performed using
282 women who wore piemennichenl nl Ihe lime of Ihe explosion

1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied. Environ Health Perspect, 2004, 112:1289-1292. Authors discuss use of
pooled serum from residents of the unexposed zone, and that those in lowest exposure group
had high exposures relative with contemporary levels for the area. Strengths of study include
use of serum to estimate TCDD exposure.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria satisfied. The SWHS included women between 1 month and 40 years of age at time of
accident who attempted to get pregnant after the explosion (n = 463). This study is restricted
to those who were premenarcheal at the time of the explosion (n = 282). Serum was collected
for these women, primarily in 1976-1977 (n = 257), between 1978 and 1981 for 23, and in
1996-1997 for the 2 remaining women.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined. Response has to be a nonfatal endpoint.

Response

Criteria not satisfied. TCDD exposures in 1976 were estimated by extrapolation serum levels
obtained after this date using the Filser model. Both categorical and continuous measures of
exposure were modeled. In utero measures of exposure are likely most relevant exposure
based on findings from animal studies.





Conclusion

No association between TCDD levels and age at menarche was found. There may be some
misclassification of age at menarche based on self-report, and biologically, the most relevant
dose as suggested by animal studies occurs in utero. Additionally, it is difficult to identify the
relevant time interval over which TCDD dose should be considered for dose-response analysis.
For these reasons, these data are not suited to a dose-response analysis.

Table B-32. Eskenazi et al., 2005—Age at menopause

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. Outcome measures were obtained based on self-reported data
collected from questionnaires. Studies have shown that self-reports of age at menopause are
reported with accuracy and reliability, and among women with surgical menopause, the self-
reported age correlated well with that on the medical records.

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2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration satisfied. Data obtained from the questionnaire allow for the potential
confounding influence of several potential confounders to be controlled for.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration not satisfied. Although risks of earlier menopause increased in the first
four quintiles, with a statistically significant trend, no increased risk was noted in the highest
exposure category (hazard ratio = 1.0 relative to lowest exposure group). Study authors
suggest this is due to the "inverted U" dose response often seen with hormonally active
compounds. Additionally, no statistically significant association was noted with logi0TCDD
for the individual quintiles.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Criteria satisfied. Serum concentrations of TCDD offer improved exposure assessment,
although delineating the critical exposure window is challenging given the nature of the very
high initial exposure.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied. The study included 616 women. Of these, 260 were premenopausal,
169 classified as natural menopause, 83 as surgical menopause, 24 as impending menopause,
33 as premenopausal, and 58 in an "othef' category.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied. Environ Health Perspect, 113:858-862 (2005). Authors highlight this is
first study to look at relationship between dioxin and age at menopause. Other limitations of
the study include lowest exposure group (< 20.4 ppt) includes exposures level that are far
higher than background, and age at menopause was based on retrospective recall. Strength of
study is ability to characterize TCDD using serum measures.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria satisfied. The Seveso Women's Health Study collected serum sample which allowed
TCDD exposures to be characterized. Those women (n = 616) who had not reached natural
menopause at the time of the accident were included in the study. Serum measures collected
in 1976/77 were available for 564 women, for 28 women, sera was collected between 1978
and 1981, while for 24 women, sera was collected in 1996/97.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined. Response has to be a nonfatal endpoint.

Response

Criteria not satisfied. TCDD levels were estimated at the time of the explosion using available
information on TCDD half-life. However, it is difficult to identify the relevant time interval
over which TCDD dose should be considered for dose-response analysis. The critical window
of exposure can be estimated but is large and highly uncertain.





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Conclusion

The findings do not provide strong support for a dose-response relationship. As such, they are
not well suited to a quantitative dose-response analysis.

Table B-33. Warner et al., 2007—Ovarian function

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. Ovarian cyst analysis based on women who underwent ultrasound
(n = 310). Ovarian follicle analysis based on self-report on menstrual cycle and done in
women in preovulatory cycle (n = 96) at time of ultrasound. Hormonal analysis based on
women in last 14 days of cycle (n = 129).

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration satisfied. Data collected from self-reported questionnaires allow for the
potential confounding influence of many risk factors to be taken into account. Some
misclassification of outcome based on self-reports of menstrual cycle may bias risk estimates
towards the null.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration not satisfied. There was no association between serum TCDD levels and the
number or size of ovarian follicles. TCDD was also not associated wit the odds of ovulation.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Criteria satisfied. Serum concentrations of TCDD offer improved exposure assessment,
although delineating the critical exposure window is challenging given the nature of the very
high initial exposure.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied. Cohort was large enough as analyses were performed using
129 women for ovulation outcome, and hormone analyses based on 87 women in luteal, and
55 in midluteal phases.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied. Environ Health Perspect, 2007,115:336-340. An important limitation cited
by the authors was that women may not have been exposed at critical period (prenatally).
Phases of the cycle may also have been misclassified as this was based on self-reported data.
Strength, first study to have examined ovarian function and TCDD exposures.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria satisfied. The SWHS included women between 1 month and 40 years of age at time of
accident who were between 20-40 years of age and not using oral contraceptives at follow-up
(n = 363).Of these, serum was collected for 330 women between 1976 and 1977, between
1978 and 1982 for 25 women, and between 1996 and 1997 for 8 women.

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3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined. Response has to be a nonfatal endpoint.

Response

Criteria not satisfied. The women may not have been exposed at critical period (prenatally).





Conclusion

No association between TCDD levels and ovarian function was found. There may be some
misclassification of period of the cycle based on self-report, and biologically, the most relevant
dose as suggested by animal studies occurs in utero. For these reasons, these data are not
suited to a dose-response analysis.

Table B-34. Eskenazi et al., 2007—Uterine leiomyoma

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. Outcomes were determined using two definitions: current fibroids, or
past diagnosis of fibroids. For past diagnosis of fibroids, self-reported data and medical
records were used to determine whether women were previously diagnosed with fibroids, these
were confirmed with medical records. A total of 25 women indicated they had never been
diagnosed with fibroids. Medical records indicate a past diagnosis for these women, and they
were classified as such. For current fibroids, this was determined at the time of the interview
for 634 women using transvaginal ultrasound examinations.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration satisfied. In the SWHS questionnaires were administered to the participants and
detailed data for reproductive characteristics, smoking, body mass index, and alcohol use were
collected so risks could readily be adjusted for these covariates.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration satisfied, but inversely. An inverse dose-response pattern with the percentage of
women diagnosed (current and past history—combined) with fibroids across 3 categories of
exposure. Namely, the percentages of women with fibroids in the <20, 20.1-75.0, and
>75.0 ppt categories were 41.1%, 26.8%, and 20.0%, respectively.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration satisfied. A variety of different exposure metrics were considered including
linear, categorical, splines, and logi0TCDD.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied. A total of 251 women were found to have fibroids, and there were 62,
110, and 79 women with fibroids diagnosed in the 3 TCDD exposure categories.





1. Criicria

Study is published in the peer-reviewed scientific lilciaiuic and has an appropriate discussion
of the strengths and limitations.

This document is a draft for review purposes only and does not constitute Agency policy.

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Response

Criteria satisfied. Am J Epidemiol, 2007, 166:79-87. In this study, the authors found an
inverse association between TCDD and uterine leiomyoma risk. The authors highlighted
strengths of the study that included the longitudinal design, serum measures taken at an
individual-level basis and most taken within 2 years of the accident, ability to include
outcomes among those who did not take an ultrasound by using an adapted statistical
approach. An important limitation that was the differences in risk by the stage of development
could not be assessed as all women were exposed postnatally, and only 4 cases were observed
among those who were premenarcheal at the time of exposure.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria satisfied. Final sample consisted of 956 women in the Seveso Women's Health Study
without a history of fibroids. For 872 of these women, serum was collected in 1976 and 1977.
For 56 women, TCDD was measured in women between 1978 and 1981, and for 28 women
the serum was collected in 1996.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined. Response has to be a nonfatal endpoint.

Response

Criteria not satisfied. TCDD exposures were back extrapolated to expected levels in 1976 (at
the time of the accident). However, it is difficult to identify the relevant time interval over
which TCDD dose should be considered for dose-response analysis. The critical window of
exposure is unknown.





Conclusion

The data suggest an inverse (protective) effect between fibroids and exposure to TCDD. As
such, these data are not suited to further dose-response analyses.

B.2.5. Other Seveso Noncancer Studies

Table B-35. Mocarelli et al., 2008—Semen quality

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. Serum levels of TCDD were measured on an individual basis for men
in exposed areas; pooled samples from men in uncontaminated areas were measured to assess
background TCDD exposure levels.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration satisfied. While compliance rates may have introduced some possible bias, this
does not seem likely as different effects noted between the 22-31 and 32-39 year old age
groups. Information collected for other risks factors, which have been used as adjustment
factors in the models.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

This document is a draft for review purposes only and does not constitute Agency policy.

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Response

Consideration satisfied. Figure 3 suggests dose-response relationship among those aged 1-9 at
the time of the accident for sperm concentration and motility.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration satisfied. Serum concentrations of TCDD offer improved exposure assessment,
although delineating the critical exposure window is challenging.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied. Analyses are based on 135 males exposed to TCDD.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied. Environmental Health Perspective s, 2008, 116(l):70-77. The authors
describe strengths associated with characterization of exposure (using serum samples), and
representativeness of study population. Limitation of study includes low compliance (but high
for semen sample studies), namely, 60% among a group of healthy men. The compliance rate
was higher among exposed group (69%).

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria satisfied. Involved males, <16 years old at time of accident.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined. Response has to be a nonfatal endpoint.

Response

Criteria satisfied. TCDD exposures were based on serum samples. Serum samples were
drawn (in 1997/1998) from participants whose 1976 samples were above 15 ppt. Pooled
samples obtained in 1997/98 were used to describe background TCDD levels in
uncontaminated areas. The associated between TCDD exposure and semen quality was found
statistically significant for the boys with 1 and 9 years of age at the time of the accident. This
provides a critical window of exposure to estimate TCDD concentration.





Conclusion

Health outcomes are exposures are well characterized using serum data. However, the men
exposed between the ages of 1 and 9 to elevated TCDD levels had reduced semen quality
22 years later. It is difficult to discern whether this effect is a consequence of the initial high
exposure between 1 and 9 years of age or a function of the cumulative exposure for this entire
exposure window beginning at the early age. Nonetheless, quantitative dose-response analyses
for this outcome were conducted.

Table B-36. Mocarelli et al., 2000—Sex ratio

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. Birth records examined for those who lived in parents who lived in
the area and who provided serum samples.

This document is a draft for review purposes only and does not constitute Agency policy.

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2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration satisfied.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration satisfied. Paternal TCDD exposures were associated with an increased
probability of female births (p = 0.008).

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration satisfied. Serum samples were used to estimate maternal and paternal TCDD
levels. No discussion of exposure levels in reference population.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied. Statistically significant findings achieved.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria not satisfied. The Lancet, 2000, 355:1858-1863. There is no discussion on the
strengths and limitations of this study.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria satisfied. Serum levels of TCDD were obtained from parents using samples provided
in 1976/77. Serum measures available for 296 mothers and 239 fathers.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined. Response has to be a nonfatal endpoint.

Response

Criteria not satisfied. Serum based measures of TCDD were obtained shortly after the
accident. TCDD levels were also extrapolated to the time of conception. However, it is
difficult to identify the relevant time interval over which TCDD dose should be considered for
dose-response analysis. The critical window of exposure is unknown.





Conclusion

The data from this study demonstrate a positive dose-response relationship with paternal
TCDD levels at the time of the accident and increased likelihood for female births. However,
It is difficult to identify the relevant time interval over which TCDD dose should be
considered; specifically, it is difficult to discern whether this effect is a consequence of the
initial high exposure during childhood or a function of the cumulative exposure for this entire
exposure window beginning at the early age. Using the initial exposures in a dose-response
model would yield LOAELs that are too high to be relevant to factor into the RfD calculation.
Dose-response analysis for this outcome is, therefore, was not conducted.

1

2

3

4

5

This document is a draft for review purposes only and does not constitute Agency policy.

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1	Table B-37. Baccarelli et al., 2008—Neonatal thyroid function

2

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. Measures of b-TSH are taken using a standardized protocol 72 hours
after birth. These b-TSH measures are taken on all newborns born in the region of Lombardy of
which Seveso if a part of.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design or
statistical analysis.

Response

Consideration satisfied for component of the study based on plasma dioxin measures. For the
comparisons involving place of residence at the time of the accident, exposure misclassification is
likely given variability in soil TCDD exposure levels within these areas.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of an
exposure-response relationship.

Response

Consideration satisfied. Mean neonatal b-TSH was 0.98|iU/ml [0.90-1.08] in the reference area,
1,35|iU/ml [1.22-1.49] in zone B, and 1,66|iU/ml [1.19-2.31] in zone A (p < 0.001). The plotted
frequency distributions have similar shapes, but have shifted to the right for areas of higher
exposures. Neonatal b-TSH was correlated with current maternal plasma TCDD ((3-0.47,
p < 0.001) in the 51 newborns for which individual maternal serum TCDD values were available.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration satisfied. TEQs were measured among the 38 women for which serum samples
were available and were defined for a mixture of dioxin-like compounds. Maternal mean total
TEQs (PCDDs, PCDFs, coplanar PCBs, and noncoplanar PCBs) was 41.8 ppt. Two measures of
exposure included place of residence at time of accident and plasma samples obtained from
mothers at the time of delivery. Similarities in positive dose-response relationships give stronger
weight to the findings.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure adequate
statistical power.

Response

Consideration satisfied for exposure metric that was based on 'place of residence'. For plasma
based estimate of maternal TCDD there were only 51 mother-child pairs. Only seven children in
total were found to have b-TSH levels in excess of 5 uU/ml; this implies limited statistical power
involving this health outcome.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion of
the strengths and limitations.

Response

Criteria satisfied. PLOS Medicine 2008; 5(7)1133-1142. The authors discuss the strength of the
study related to characterization of exposure using serum sampling, and ability to adjust for
factors related to b-TSH or TCDD levels (gender, birth weight, birth order, maternal age, hospital
and type of delivery). They also highlight that a limitation of study was that the influence of
mother-child dioxin transfer through colostrum could not be assessed because no information on
breastfeeding before b-TSH measurement was available.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response relationships
can be assessed.

This document is a draft for review purposes only and does not constitute Agency policy.

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Response

Criteria satisfied. In the population-based study, eligible women who resided in zones A and B at
the time of the accident (n = 1,772) were matched to nonexposed women. In the study based on
plasma dioxin measurements, participants were the 51 children born to 38 women from zones A,
B, R, or a reference zone for which plasma dioxin measurements were available.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of exposure
are consistent with the current biological understanding of dose. The reported dose is consistent
with a toxicologically relevant dose. Latency and appropriate window(s) of exposure examined.
Response has to be a nonfatal endpoint.

Response

Criteria satisfied. Maternal TCDD levels were estimated at the time of delivery based on plasma
samples, and the critical window of exposure can be defined as the 9 month gestation period.





Conclusion

The data provide an opportunity for quantitative dose-response analyses.

1

2

3

4

Table B-38. Alaluusua et al., 2004—Oral hygiene

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. Ascertainment of dental health was done blind to place of residence,
used standard protocol for caries developed by the WHO, and the clinical examination
supplemented by radiographic examination.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration satisfied. Additional risk factor information was collected on questionnaires.
These factors were considered as adjustment factors. Findings potentially susceptible to
participation biases.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration satisfied. Increased prevalence of developmental enamel effects found with
increased TCDD serum measures. Namely, prevalence in unexposed region was 26%,
whereas in the low, middle, and high TCCD groups the prevalence was 10, 40, and 60%,
respectively.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration satisfied. TCDD exposure level based on serum lipids. No discussion of
exposure levels in reference population.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Criteria satisfied. Despite small numbers, statistically significant findings were achieved.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

This document is a draft for review purposes only and does not constitute Agency policy.

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Response

Criteria satisfied. Environmental Health Perspectives, 2004, 112(13)1313-1318. Authors
mention two important strength of the study: characterization of TCDD exposure using serum
collected shortly after the time of the accident, and the fact that developmental defects are
permanent in nature. Therefore, they represent a health outcome can evaluated years later.
Little discussion was made of the impact of differential compliance rates between the exposed
(74%) and nonexposed (58%) groups. Authors mention two important strength of the study:
characterization of TCDD exposure using serum collected shortly after the time of the
accident, and the fact that developmental defects are permanent in nature. Therefore, they
represent a health outcome can evaluated years later. Little discussion was made of the impact
of differential compliance rates between the exposed (74%) and nonexposed (58%) groups.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria satisfied. Serum levels of TCDD could be estimated for children in exposed areas.
No serum levels were available for reference group of children, and assumption of zero
exposure was made. This seems reasonable.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined. Response has to be a nonfatal endpoint.

Response

Criteria satisfied. It is difficult to discern whether this effect is a consequence of the initial
high exposure during childhood or a function of the cumulative exposure of the entire
exposure window beginning at early age. However, assumptions can be made regarding the
critical window of exposure and the relevant dose can be calculated.





Conclusion

The considerations for conducting a dose-response analysis have been satisfied with the study
population of only those subjects who lived in the ABR zone at the time of the accident;
exposure data are unavailable for those in the referent area. While is difficult to identify the
relevant time interval over which TCDD dose should be considered, quantitative
dose-response analysis for this outcome was conducted.

Table B-39. Bertazzi et al., 2001—Mortality (noncancer)

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied for some causes of death, but not others. Mortality appears to be well
captured from the vital statistics registries in the region (99% complete). Some health
outcomes (e.g., diabetes) are subject to misclassification using death certificate data.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration satisfied. Although individual-level data for individual risk factors are not
available, the potential for confounding is likely minimal. For e.g., independent surveys
suggests similarity between smoking behaviors across the regions. Exposure misclassification
based on place of residency likely to bias risk estimates towards the null.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

This document is a draft for review purposes only and does not constitute Agency policy.

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Response

Consideration not satisfied for most causes of death. An exception was the dose-response
relationship was observed for chronic obstructive pulmonary disease across Zones A, and B.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration not satisfied. Exposure classification was based on the address of the
residence on the date of the accident or when the person first entered the area. Although
TCDD blood levels were also measured, these were not examined with respect to health
outcomes. The lack of individual-level data also precluded an examination of these
uncertainties.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied. A total of 494 noncancer deaths were found among residents of
Zones A, and B, respectively. This allowed examined of gender-specific effects.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied. Am J Epidemiol, 2001, 153:1031-1044. Authors discuss lack of
individual-level exposure data and other risk factors (e.g., smoking), difficulties in
extrapolating to background levels, diagnostic accuracy of using death certificates. Strengths
included similarities between exposed and comparison population for several risk factors,
completeness of follow-up, and consistent methods to identify mortality outcomes in the
exposed and comparison populations.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria not satisfied. Individual-level exposure data are unavailable. Exposure based on place
of residence at time of the explosion. Soil sampling performed indicated considerable
variability in TCDD levels within each region. In addition, place of residency at time of
explosion does not ensure individuals were at their home around the time of the accident.

3. Critieria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined. Response has to be a nonfatal endpoint.

Response

Criteria not satisfied. An ecological measure of exposure (region of residency at time of
accident) was used to categorize individuals according to their possible exposure. Latencies
were considered. While such an approach has value for identifying whether excesses occurred
among highly exposed populations, it is not precise enough to conduct a quantitative dose-
response analysis. Furthermore, noncancer mortality is not a viable endpoint to consider for
further dose-response analysis.





Conclusion

Study is not suitable for dose-response analysis due to mortality as endpoint and lack of
individual-level exposure data.

1

2

3

4

5

This document is a draft for review purposes only and does not constitute Agency policy.

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1	Table B-40. Consonni et al., 2008—Mortality (noncancer)

2

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied for some causes of death, but not others. Mortality appears to be well
captured from the vital statistics registries in the region (99% complete). Some health
outcomes (e.g., diabetes) are subject to misclassification using death certificate data.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration satisfied. Although individual-level data for individual risk factors are not
available, the potential for confounding is likely minimal. For e.g., information from other
independent surveys suggests similarity between smoking behaviors across the regions.
Exposure misclassification based on place of residency is likely to bias risk estimates towards
the null.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration not satisfied. Statistically significant association noted in most highly exposed
area for chronic rheumatic disease and chronic obstructive pulmonary disease. Dose-response
pattern noted across Zones A, B and R for circulatory disease mortality 5-9 years after the
accident.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration not satisfied. Lack of individual-level data precludes an examination of these
uncertainties.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied for some causes of death but not others. For example, only
three deaths from diabetes occurred among residents of Zone A. The limitation related to
statistical power is exacerbated for stratified analyses carried out by number of years since the
accident.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied. Am J Epidemiol, 2008, 167:847-858. Authors discuss potential for
selection bias, limitation of residential based measure of exposure, similarities of mortality
ascertainment in exposed and referent populations, and multiple testing.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria not satisfied. Individual-level exposure data are unavailable. Exposure based on place
of residence at time of the explosion. Soil sampling performed indicated considerable
variability in TCDD levels within each region. In addition, place of residency at time of
explosion does not ensure individuals were at their home around the time of the accident.

This document is a draft for review purposes only and does not constitute Agency policy.

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3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined. Response has to be a nonfatal endpoint.

Response

Criteria not satisfied. An ecological measure of exposure (region of residency at time of
accident) was used to categorize individuals according to their possible exposure. Latencies
were considered. While such an approach has value for identifying whether excesses occurred
among highly exposed populations, it is not precise enough to conduct a quantitative
dose-response analysis. Furthermore, noncancer mortality is not a viable endpoint to consider
for further dose-response analysis.





Conclusion

Study is not suitable further dose-response evaluation due to noncancer moialils ciidpoml

Table B-41. Baccarelli et al., 2005—Chloracne

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. Chloracne cases identified using standardized criteria.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration satisfied.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration satisfied. Plasma TCDD was associated with an increased risk of chloracne.
The odds ratios increased in a dose-response pattern across zone of residence.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration satisfied. Authors discussed implications of differential elimination rates by age
and body growth.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied. A total of 101 chloracne cases were identified, and 211 controls were
selected. Statistically significant findings were observed in several comparisons.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied. British Journal of Dermatology, 2005, 152,459-465. The authors detail the
limited statistical power they had available in the study. They also highlight a strength of the
study that included uniqueness of age and sex distribution of chloracne cases, characterization
of TCDD that could be done using sera samples, and availability of both clinical and
epidemiological data.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

This document is a draft for review purposes only and does not constitute Agency policy.

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Response

Criteria satisfied. TCDD was estimated in both chloracne cases and control using serum
measures.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined. Response has to be a nonfatal endpoint.

Response

Criteria satisfied. Serum based measures of TCDD were obtained shortly after the accident.
Chloracne is thought to be caused by the initial high exposure.





Conclusion

Exposure to TCDD at sufficiently high levels is recognized to cause chloracne. This study
provides limited relevance to dose-response modeling of TCDD as exposure levels typically
observed in the general population are much lower.

Table B-42. Baccarelli et al, 2002 and 2004—Immunological effects

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. Common methods were used to describe blood levels of plasma
immunoglobulins (IgA, IgG, and IgM) and complement components (C3 and C4).

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration satisfied. Both exposure and outcome were objectively and accurately measured.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration satisfied. Plasma IgG levels were inversely related with TCDD.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration satisfied. Both categorical (quintiles) and continuous measures of TCDD were
examined in the dose-response analysis.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied. Analyses are made using 72 highly exposed, and 72 low exposed
individuals.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied. Toxicology letters, 2004, 149:287-293 and Environ Health Perspect, 2002,
110(12): 1169-1173. The authors highlight that few studies have looked at immunological
effects of TCDD in humans, that the current study was able to exclude those with concurrent
medical conditions, and the ability to characterize exposure using serum measures. Limitations
addressed were the uncertainty about the clinical relevance of the dose-response pattern found,
and the relatively small size of the study population.

This document is a draft for review purposes only and does not constitute Agency policy.

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2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria satisfied. A total of 120 subjects were included in the study. This included
62 randomly selected from the high exposed zone, and 58 selected from the reference area.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of exposure
are consistent with the current biological understanding of dose. The reported dose is
consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined. Response has to be a nonfatal endpoint.

Response

Criteria not satisfied. Dose-response relationships were examined using current TCDD levels.
However, it is difficult to identify the relevant time interval over which TCDD dose should be
considered for dose-response analysis.





Conclusion

An inverse dose-response association between IgG and TCDD was observed, however, because
the relationship can not be described in terms of clinical relevance with respect to a specific
health outcome, it is our view that these data are not suited to dose-response modeling.

1

2

3

4

5

6

7

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration cannot be evaluated. Insufficient details are provided in the paper to gauge the
completeness and coverage of the cancer registry and mortality data. Health outcomes were
studied on the basis of information in the official medical statistics

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration not satisfied. It is an ecological study.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration cannot be evaluated. Dose-response was not evaluated as exposure was based on
residency in the region vs. no residency.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration not satisfied. No individual-level exposure estimates were used.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied. Population-based data over several years were used to make ecological
comparisons.





This document is a draft for review purposes only and does not constitute Agency policy.

B-55 DRAFT—DO NOT CITE OR QUOTE

B.2.6. Chapaevsk Study

Table B-43. Revich et al., 2001—Mortality (noncancer) and reproductive
health


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1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied. Published in Chemosphere, 2001, 43(4-7):951-966.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria not satisfied. It is a cross-sectional study that compares mortality rates between
regions. No individual-level exposure data available.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of exposure
are consistent with the current biological understanding of dose. The reported dose is
consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined. Response has to be a nonfatal endpoint.

Response

Criteria not satisfied. No exposure estimates were used in the study.





Conclusion

These cancer data are cross-sectional in nature and not appropriate for a dose-response analysis.

B.2.7. Air Force Health ("Ranch Hands") Study

Table B-44. Michalek and Pavuk, 2008—Diabetes

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. Prevalent diabetes identified from medical records from repeated
medical check-ups. Preferred method of ascertaining outcome relative to use of death
certificates.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration not satisfied. Adjustment was made for a number of risk factors related to
diabetes (e.g., BMI, family history, smoking). However, Agent Orange was a 50% mixture of
2,4-D and TCDD; therefore, potential for confounding by other coexposures is likely.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration satisfied. The RR for an increase in 10 units was 1.29 (p < 0.001), and the risks
across the background, low and high exposure categories, relative to the unexposed were 0.86,
1.45, and 1.68.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration satisfied. Initial TCDD dose were estimated at the end of the tour of duty for
the Ranch Hands. Individual-level serum dioxin measurements correlated well with correlated
with days of spraying and calendar period of service, but collection of the samples roughly
20 years later required back-extrapolation.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

This document is a draft for review purposes only and does not constitute Agency policy.

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Response

Consideration satisfied. There were a total of 439 cases of diabetes identified.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied. J Occup Environ Medicine, 2008, 50:330-340. The authors address
strengths and limitations related to the accuracy of the one-compartment pharmacokinetic
model, impact of the covariate time spent in Southeast Asia, and potential exposure
misclassification on days sprayed.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria not satisfied. TCDD estimates were derived using serum samples. However, Ranch
Hand veterans were exposed to other compounds in the herbicides, such as 2,4-D.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined. Response has to be a nonfatal endpoint.

Response

Criteria satisfied. TCDD levels at the end of service were estimated. Extrapolation was done
using a half-life of 7.6 years. Exposures were grouped into comparison, background, low and
high. This allows for a shape of the dose-response curve to be evaluated. A continuous
measure of TCDD was also examined (logi0TCDD).





Conclusion

Ranch Hand veterans were exposed to other contaminants in the herbicides that were mixed,
thereby making it difficult to determine independent effects of TCDD on diabetes. In our
view, this limitation precludes dose-response modeling of TCDD and diabetes using data from
this cohort.

1

2

3

4

5

6

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. The New Zealand Health Information Service Mortality Collection
and the Registrar-General's Index to Deaths were used to identify deaths. Additional searches
were based on the last known address from the work record; the electoral roll and the
habitation index; the telephone book; the internet; and Terranet property information database.
An additional search was carried out through the Births, Deaths, and Marriages office of the
New Zealand Department of Internal Affairs. Lastly, automated personnel and pension
records were also used to locate past New Plymouth workers and identify some deaths.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration satisfied. Workers lost to follow-up were an unlikely source of bias especially
for internal analyses. Confounding by other coexposures (e.g., 2,4,6-TCP) unlikely to have
resulted in bias, due to presumed poor correlation with TCDD.

This document is a draft for review purposes only and does not constitute Agency policy.

B-57 DRAFT—DO NOT CITE OR QUOTE

B.2.8. Other Noncancer Studies of Dioxin

Table B-45. McBride et al., 2009a—Mortality (noncancer)


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3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration not satisfied. There was no cause of death among those considered for which a
dose-response trend was observed across four exposure categories of TCDD.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration satisfied. Dichotomous exposure (exposed/unexposed) and duration of
employment were examined from job exposure classification assessed via occupational history
records industrial hygienists/factory personnel knowledge and questionnaires.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration not satisfied.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied. Published in J Occup Environ Med, 2009, 51:1049-1056. The other studies
in the cohort highlight the 22% of the cohort lost to follow-up, the limited size of the cohort
tissue sarcomas, differences in cohort definitions between sprayers and producers, and the
potential for other exposures during employment at the plant.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria satisfied. Serum measures available for 346 workers were used to derive TCDD
exposures for the entire cohort using the area under the curve approach.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined. Response has to be a nonfatal endpoint.

Response

Criteria not satisfied. Dichotomous exposure assessment did not allow individual estimates of
dose to be developed. However, noncancer mortality is not a viable endpoint to consider for
further dose-response analysis.





Conclusion

A considerable portion of the cohort was lost to follow-up, and no dose-response associations
noted. As a result, the data are not suited to dose-response analysis.

1

2

This document is a draft for review purposes only and does not constitute Agency policy.

B-58 DRAFT—DO NOT CITE OR QUOTE


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1	Table B-46. McBride et al., 2009b—Mortality (noncancer)

2

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration satisfied. The New Zealand Health Information Service Mortality Collection
and the Registrar-General's Index to Deaths were used to identify deaths. Additional searches
were based on the last known address from the work record; the electoral roll and the
habitation index; the telephone book; the internet; and Terranet property information database.
An additional search was carried out through the Births, Deaths, and Marriages office of the
New Zealand Department of Internal Affairs. Lastly, automated personnel and pension
records were also used to locate past New Plymouth workers and identify some deaths.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration not satisfied. Considerable amount of workers were lost to follow up (22%),
but it is unclear if bias resulted. The dichotomous exposure measure was based on exposure
to TCDD, chlorinated dioxins and phenoxy herbicides, so confounding is a possibility by
these coexposures.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration not satisfied. Because no individual exposure estimates were available for
these analyses, dose-response could not be evaluated.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration satisfied. Consideration satisfied. Dichotomous exposure
(exposed/unexposed) and duration of employment were examined from job exposure
classification assessed via occupational history records industrial hygienists/factory personnel
knowledge and questionnaires. Authors discuss limitations in the assignment of exposure
among cohort members.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

Response

Criteria satisfied. Published in Occup Medicine, 2009, 59(4):255-263. The authors highlight
cohort lost to follow-up, the limited size of the cohort, differences in cohort definitions
between sprayers and producers, and the potential for other exposures during employment at
the plant.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria not satisfied. Exposures were not quantified. The dichotomous exposure measure
was based on exposure to TCDD, chlorinated dioxins and phenoxy herbicides.

This document is a draft for review purposes only and does not constitute Agency policy.

B-59 DRAFT—DO NOT CITE OR QUOTE


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3. Critiera

The effective dose and oral exposure can be reasonably estimated and the measures of
exposure are consistent with the current biological understanding of dose. The reported dose
is consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined. Response has to be a nonfatal endpoint.

Response

Effective dose could not be estimated given the lack of individual-level exposure data.
Noncancer mortality is not a viable endpoint to consider for further dose-response analysis.





Conclusion

The study lacks the quantification of exposures at an individual level, and a considerable
portion of the cohort was lost to follow-up. As a result, the data are not suited to
dose-response analysis.

Table B-47. Ryan et al., 2002—Sex ratio

1. Consideration

Methods used to ascertain health outcomes identified were unbiased, highly sensitive, and
specific.

Response

Consideration not satisfied. Company records were used to identify births, the date of birth,
and the sex of the child. No information was provided on the expected completeness of
identifying births in this manner. Moreover, the study was expanded to include workers who
heard about the study in a public forum. Therefore, the study could be influenced by
participation bias.

2. Consideration

Risk estimates are not susceptible to biases from confounding exposures or from study design
or statistical analysis.

Response

Consideration not satisfied. See above.

3. Consideration

Study demonstrates an association between TCDD and adverse health effect with evidence of
an exposure-response relationship.

Response

Consideration not satisfied. The study compared birth ratios among men and women employed
at the plant to the general population. No categories of exposure were examined.

4. Consideration

Exposure assessment methodology is clear and adequately characterizes individual-level
exposures. The limitations and uncertainties in the exposure assessment are considered.

Response

Consideration not satisfied. This is not relevant as no analyses were done in relation to
exposure levels.

5. Consideration

Study size and follow-up are large enough to yield precise estimates of risk and ensure
adequate statistical power.

Response

Consideration satisfied. For the categories of exposure used (yes/no), and the stratified
analyses by sex and subcohort, the study allows for the birth ratios to be estimated with
sufficient precision.





1. Criteria

Study is published in the peer-reviewed scientific literature and has an appropriate discussion
of the strengths and limitations.

This document is a draft for review purposes only and does not constitute Agency policy.

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Response

Criteria not satisfied. Published in Environ Health Perspect, 2002, 110(11):A699-A701. The
authors discussed the limitations of using serum collected many years after they stopped
working to estimate TCDD exposures when the preferred metric would be TCDD levels at the
time of conception. They did not address issues about the representativeness of the study
participants to the entire cohort of workers, nor did they address the limitation of not being able
to conduct dose-response analyses using individual-level TCDD data.

2. Criteria

Exposure must be primarily TCDD and is properly quantified so that dose-response
relationships can be assessed.

Response

Criteria not satisfied. While serum measures were available for 84 of the 198 participants of
the study, birth ratios were compared between the cohort of 2,4,5-T and 2,4,5-trichlorphgenol
workers relative to the city of Ufa. There was no attempt to derive birth ratios in relation to
exposure levels. The serum data were only used to demonstrate that these workers, on average,
had TCDD levels 30 times higher than Ufa residents.

3. Criteria

The effective dose and oral exposure can be reasonably estimated and the measures of exposure
are consistent with the current biological understanding of dose. The reported dose is
consistent with a toxicologically relevant dose. Latency and appropriate window(s) of
exposure examined. Response has to be a nonfatal endpoint.

Response

Criteria not satisfied. TCDD exposures were based on serum measures taken in some cases
many years after children were born; no attempt was made to back-extrapolate to the time of
conception.





Conclusion

The data are not suitable for dose-response modeling. Risk estimates have not been derived in
relation to TCDD exposure levels. There exist uncertainties about the representativeness of the
participants in relation to the cohort as a whole, and insufficient details are provided to evaluate
the extent in which all births were identified. While these data should not be used for
quantitative dose-response modeling, the much lower M/F birth ratio among exposed fathers is
consistent with the finding by Mocarelli et al, and lends support to those findings.

1

2

3	B.3. REFERENCES

4	Akhtar, FZ; Garabrant, DH; Ketchum, NS; et al. (2004) Cancer in US Air Force veterans of the Vietnam War. J

5	Occup Environ Med 46(2): 123-136.

6	Alaluusua, S; Calderara, P; Gerthoux, PM; et al. (2004) Developmental dental aberrations after the dioxin accident

7	inSeveso. Environ Health Perspect 112(13): 1313-1318.

Aylward, LL; Brunet, RC; Starr, TB; et al. (2005a) Exposure reconstruction for the TCDD-exposed NIOSH cohort
using a concentration- and age-dependent model of elimination. Risk Anal 25(4):945-956.

Aylward, LL; Brunet, RC; Carrier, G; et al. (2005b) Concentration-dependent TCDD elimination kinetics in
humans: toxicokinetic modeling for moderately to highly exposed adults from Seveso, Italy, and Vienna, Austria,
and impact on dose estimates for the NIOSH cohort. J Expo Anal Environ Epidemiol 15(1):51-65.

8	Baccarelli, A; Mocarelli, P; Patterson, DG, Jr.; et al. (2002) Immunologic effects of dioxin: new results from Seveso

9	and comparison with other studies. Environ Health Perspect 110(12): 1169—1173.

10	Baccarelli, A; Pesatori, AC; Masten, SA; et al. (2004) Aryl-hydrocarbon receptor-dependent pathway and toxic

11	effects of TCDD in humans: a population-based study in Seveso, Italy. Toxicol Lett 149(l-3):287-293.

This document is a draft for review purposes only and does not constitute Agency policy.

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1	Baccarelli, A; Pesatori, AC; Consonni, D; et al. (2005) Health status and plasma dioxin levels in chloracne cases

2	20 years after the Seveso, Italy accident. Br J Dermatol 152(3):459-465.

3	Baccarelli, A; Hirt, C; Pesatori, AC; et al. (2006) t(14; 18) translocations in lymphocytes of healthy dioxin-exposed

4	individuals from Seveso, Italy. Carcinogenesis 27(10):2001-2007.

5	Baccarelli, A; Giacomini, SM; Corbetta, C; et al. (2008) Neonatal thyroid function in Seveso 25 years after maternal

6	exposure to dioxin. PLoS Med 5(7): 1133-1142.

7	Becher, H; Steindorf, K; Flesch-Janys, D. (1998) Quantitative cancer risk assessment for dioxins using an

8	occupational cohort. Environ Health Perspect 106(Suppl 2):663-670.

9	Bertazzi, PA; Consonni, D; Bachetti, S; et al. (2001) Health effects of dioxin exposure: a 20-year mortality study.

10	Am J Epidemiol 153(11): 1031-1044.

11	Cheng, H; Aylward, L; Beall, C; et al. (2006) TCDD exposure-response analysis and risk assessment. Risk Anal

12	26:1059-1071.

13	Collins, JJ; Bodner, K; Aylward, LL; et al. (2009) Mortality rates among trichlorophenol workers with exposure to

14	2,3,7,8-tetrachlorodibenzo-p-dioxin. Am J Epidemiol 170(4):501-506.

15	Consonni, D; Pesatori, AC; Zocchetti, C; et al. (2008) Mortality in a population exposed to dioxin after the Seveso,

16	Italy, accident in 1976: 25 years of follow-up. Am J Epidemiol 167(7):847-858.

17	Eskenazi, B; Warner, M; Mocarelli, P; et al. (2002a) Serum dioxin concentrations and menstrual cycle

18	characteristics. Am J Epidemiol 156(4):383-392.

19	Eskenazi, B; Mocarelli, P; Warner, M; et al. (2002b) Serum dioxin concentrations and endometriosis: a cohort study

20	in Seveso, Italy. Environ Health Perspect 110(7):629-634.

21	Eskenazi, B; Mocarelli, P; Warner, M; et al. (2003) Maternal serum dioxin levels and birth outcomes in women of

22	Seveso, Italy. Environ Health Perspect 111(7), 947-953.

23	Eskenazi, B; Warner, M; Marks, AR; et al. (2005) Serum dioxin concentrations and age at menopause. Environ

24	Health Perspect 113(7):858-862.

25	Eskenazi, B; Warner, M; Samuels, S; et al. (2007) Serum dioxin concentrations and risk of uterine leiomyoma in the

26	Seveso Women's Health Study. Am J Epidemiol 166(l):79-87.

27	Fingerhut, MA; Halperin, WE; Marlow, DA; et al. (1991) Cancer mortality in workers exposed to

28	2,3,7,8-tetrachlorodibenzo-p-dioxin. N Engl J Med 324(4):212-218.

29	Flesch-Janys, D; Berger, J; Gurn, P; et al. (1995) Exposure to polychlorinated dioxins and furans (PCDD/F) and

3 0	mortality in a cohort of workers from a herbicide-producing plant in Hamburg, Federal Republic of Germany. Am J

31	Epidemiol 142(11): 1165-1175.

32	Flesch-Janys, D; Becher, H; Gurn, P; et al. (1996) Elimination of polychlorinated dibenzo-p-dioxins and

33	dibenzofurans in occupationally exposed persons. J Tox Environ Health 47(4):363-378.

34	Flesch-Janys, D; Steindorf, K; Gurn, P; et al. (1998) Estimation of the cumulated exposure to polychlorinated

3 5	dibenzo-p-dioxins/furans and standardized mortality ratio analysis of cancer mortality by dose in an occupationally

36	exposed cohort. Environ Health Perspect 106(Suppl 2):655-662.

37	Hooiveld, M; Heederik, DJ; Kogevinas, M; et al. (1998) Second follow-up of a Dutch cohort occupationally

38	exposed to phenoxy herbicides, chlorophenols, and contaminants. Am J Epidemiol 147(9):891-901.

This document is a draft for review purposes only and does not constitute Agency policy.

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1	Manz, A; Berger, J; Dwyer, JH; et al. (1991) Cancer mortality among workers in chemical plant contaminated with

2	dioxin. Lancet 338(8773):959-964.

3	McBride, DI; Collins, JJ; Humphry, NF; et al. (2009a) Mortality in workers exposed to

4	2,3,7,8-tetrachlorodibenzo-p-dioxin at a trichlorophenol plant in New Zealand. J Occup Environ Med

5	51(9):1049-1056.

6	McBride, DI; Burns, CJ; Herbison, GP; et al. (2009b) Mortality in employees at a New Zealand agrochemical

7	manufacturing site. Occup Med (Oxford, England) 59(4):255-263.

8	Michalek, JE; Pavuk, M. (2008) Diabetes and cancer in veterans of Operation Ranch Hand after adjustment for

9	calendar period, days of spraying, and time spent in Southeast Asia. J Occup Environ Med 50(3):330-340.

10	Mocarelli, P; Gerthoux, PM; Ferrari, E; et al. (2000) Paternal concentrations of dioxin and sex ratio of offspring.

11	Lancet 355(9218): 1858-1863.

12	Mocarelli, P; Gerthoux, PM; Patterson, DG, Jr.; et al. (2008) Dioxin exposure, from infancy through puberty,

13	produces endocrine disruption and affects human semen quality. Environ Health Perspect 116(l):70-77.

14	Ott, MG; Zober, A. (1996) Cause specific mortality and cancer incidence among employees exposed to

15	2,3,7,8-TCDD after a 1953 reactor accident. Occup Environ Med 53(9):606-612.

16	Pesatori, AC; Consonni, D; Bachetti, S; et al. (2003) Short- and long-term morbidity and mortality in the population

17	exposed to dioxin after the "Seveso accident". Ind Health 41(3): 127—138.

18	Revich, B; Aksel, E; Ushakova, T; et al. (2001) Dioxin exposure and public health in Chapaevsk, Russia.

19	Chemosphere 43(4-7):951-966.

20	Ryan, JJ; Amirova, Z; Carrier, G. (2002) Sex ratios of children of Russian pesticide producers exposed to dioxin.

21	Environ Health Perspect, 110(11):A699-701.

22	Steenland, K; Piacitelli, L; Deddens, J; et al. (1999) Cancer, heart disease, and diabetes in workers exposed to

23	2,3,7,8-tetrachlorodibenzo-p-dioxin. J Natl Cancer I 91(9):779-786.

24	Steenland, K; Deddens, J; Piacitelli, L. (2001) Risk assessment for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)

25	based on an epidemiologic study. Am J Epidemiol 154(5):451-458.

26	't Mannetje, A; McLean, D; Cheng, S; et al. (2005) Mortality in New Zealand workers exposed to phenoxy

27	herbicides and dioxins. Occup Environ Med 62(l):34-40.

28	Warner, M; Eskenazi, B; Mocarelli, P; et al. (2002) Serum dioxin concentrations and breast cancer risk in the

29	Seveso Women's Health Study. Environ Health Perspect 110(7):625-628.

30	Warner, M; Samuels, S; Mocarelli, P; et al. (2004) Serum dioxin concentrations and age at menarche. Environ

31	Health Perspect 112(13): 1289-1292.

32	Warner, M; Eskenazi, B; Olive, DL; et al. (2007) Serum dioxin concentrations and quality of ovarian function in

33	women of Seveso. Environ Health Perspect 115(3):336-340.

34	Zober, A; Messerer, P; Huber, P. (1990) Thirty-four-year mortality follow-up of BASF employees exposed to

35	2,3,7,8-TCDD after the 1953 accident. Int Arch Occup Environ Health 62(2): 139-157.

This document is a draft for review purposes only and does not constitute Agency policy.

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DRAFT

DO NOT CITE OR QUOTE

May 2010
External Review Draft

APPENDIX C
Kinetic Modeling

NOTICE

THIS DOCUMENT IS AN EXTERNAL REVIEW DRAFT. It has not been formally released
by the U.S. Environmental Protection Agency and should not at this stage be construed to
represent Agency policy. It is being circulated for comment on its technical accuracy and policy
implications.

National Center for Environmental Assessment
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, OH


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CONTENTS—APPENDIX C: Kinetic Modeling

APPENDIX C. kinetic Modeling	C-l

C. 1. LITERATURE SEARCH STRATEGY AND RESULTS—IDENTIFYING
RECENT PUBLICATIONS FOR UPDATING TCDD TOXICOKINETIC

MODEL INPUT PARAMETERS	C-l

C.l.l. Data Bases Searched	C-l

C.1.2. Literature Search Strategy and Approach	C-2

C.1.2.1. Chemical Search Terms—DIALOG Search	C-2

C.1.2.2. Primary Search Terms (Species)—DIALOG Search	C-2

C.1.2.3. Secondary Search Terms (Toxicology)—DIALOG Search	C-3

C.1.3. Citation Screening Procedures and Results	C-3

C. 1.4. References Selected for More Detailed Review for Updating the PBPK

Models	C-6

C.1.5. Brief Descriptions of DIALOG Bibliographic Data Bases Searched	C-8

C.2. TOXICOKINETIC MODELING CODE	C-l 1

C.2.1. Human Standard Model	C-ll

C.2.1.1. Model Code	C-ll

C.2.1.2. Input File	C-l9

C.2.2. Human Gestational Model	C-20

C.2.2.1. Model Code	C-20

C.2.2.2. Input File	C-3 1

C.2.3. Rat Standard Model	C-32

C.2.3.1. Model Code	C-32

C.2.3.2. Input Files	C-40

C.2.4. Rat Gestational Model	C-55

C.2.4.1. Model Code	C-55

C.2.4.2. Input Files	C-65

C.2.5. Mouse Standard Model	C-73

C.2.5.1. Model Code	C-73

C.2.5.2. Input Files	C-81

C.2.6. Mouse Gestational Model	C-85

C.2.6.1. Model Code	C-85

C.2.6.2. Input Files	C-96

C.3. TOXICOKINETIC MODELING RESULTS FOR KEY ANIMAL BIOASSAY

STUDIES	C-98

C.3.1. Nongestational Studies	C-98

C.3.1.1. Cantoni etal. (1981)	C-98

C.3.1.2. Chu et al. (2007)	C-l00

C.3.1.3. Crofton etal. (2005)	C-l02

C.3.1.4. Delia Porta et al. (2001) (female)	C-105

C.3.1.5. Delia Porta etal. (2001) (male)	C-l 07

C.3.1.6. Fattore et al. (2000)	C-l08

C.3.1.7. Franc et al. (2001) Sprague Dawley Rats	C-110

C.3.1.8. Franc etal. (2001) Long-Evans Rats	C-l 11

C.3.1.9. Franc etal. (2001) Hans Wi star Rats	C-113

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CONTENTS (continued)

C.3.1.10. Hassoun et al. (2000)	C-115

C.3.1.11. Hutt et al. (2008)	C-117

C.3.1.12. Kitchin and Woods (1979)	C-118

C.3.1.13. Kociba et al. (1976)	C-121

C.3.1.14. Kociba etal. (1978) Female	C-123

C.3.1.15. Kociba etal. (1978) Male	C-125

C.3.1.16. Latchoumycandane and Mathur (2002)	C-127

C.3.1.17. Li etal. (1997)	C-128

C.3.1.18. Murray et al. (1979) Adult Portion	C-132

C.3.1.19. NTP (1982)—Female Rats, Chronic	C-133

C.3.1.20. NTP (1982)—Male Rats, Chronic	C-135

C.3.1.21. NTP (1982)—Female Mice, Chronic	C-137

C.3.1.22. NTP (1982)—Male Mice, Chronic	C-138

C.3.1.23. NTP (2006) 14 Weeks	C-140

C.3.1.24. NTP (2006) 31 Weeks	C-142

C.3.1.25. NTP (2006) 53 Weeks	C-144

C.3.1.26. NTP (2006) 2 Years	C-146

C.3.1.27. Sewall et al. (1995)	C-148

C.3.1.28. Shi etal. (2007) Adult Portion	C-150

C.3.1.29. Smialowicz et al. (2008)	C-151

C.3.1.30. Toth et al., 1 Year (1979)	C-153

C.3.1.31. Van Birgelen etal. (1995)	C-155

C.3.1.32. Yanden IIeuvel etal. (1994)	C-157

C.3.1.33. White etal. (1986)	C-160

C.3.2. Gestational Studies	C-163

C.3.2.1. Bell et al. (2007)	C-163

C.3.2.2. Haavisto et al. (2006)	C-164

C.3.2.3. Hojo et al. (2002)	C-166

C.3.2.4. Ikeda et al. (2005)	C-167

C.3.2.5. Kattainen et al. (2001)	C-168

C.3.2.6. Keller et al. (2007)	C-170

C.3.2.7. Li et al. (2006) 3-Day	C-171

C.3.2.8. Markowski et al. (2001)	C-173

C.3.2.9. Mietinnen et al. (2006)	C-174

C.3.2.10. Nohara et al. (2000)	C-176

C.3.2.11. Ohsako et al. (2001)	C-177

C.3.2.12. Schantzetal. (1996) and Amin et al. (2000)	C-179

C.3.2.13. Seo etal. (1995)	C-180

C.4. RESPONSE SURFACE TABLES	C-183

C.4.1. Nongestational Lifetime	C-184

C.4.2. Nongestational 5-Year Average	C-192

C.4.3. Gestational	C-198

C.5. REFERENCES	C-204

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APPENDIX C. KINETIC MODELING

C.l. LITERATURE SEARCH STRATEGY AND RESULTS—IDENTIFYING RECENT
PUBLICATIONS FOR UPDATING TCDD TOXICOKINETIC MODEL INPUT
PARAMETERS

The purpose of this literature search was to identify recent publications that address the
input parameters for the physiologically based pharmacokinetic (PBPK) models Aylward and
colleagues (described in articles published in 2005 and 2009) and Emond and colleagues
(described in articles published in 2004, 2005, and 2006). This literature search was part of the
U.S. Environmental Protection Agency (EPA)'s preparation of a response to the National
Academy of Sciences' review (Health Risks from Dioxin and Related Compounds: Evaluation of
the EPA Reassessment, NAS, 2006]) of EPA Exposure and Human Health Reassessment of
2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) and Related Compounds (U.S. EPA, 2003), herein
called the "2003 Reassessment." English-only references from 2003 to May 2009 were searched
using bibliographic data bases relevant to health effects and toxicology of
2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The search focused on toxicokinetic data that
could be used to update the dynamic disposition of 2,3,7,8-TCDD in mice, rats, guinea pigs,
monkeys, and humans.

In the primary search, EPA identified 775 distinct citations based on the literature search
criteria described below. EPA also performed an independent supplemental search to avoid
missing key studies. EPA identified 28 papers for further analysis that appeared on first review
to report data to update the input parameters of the Aylward and Emond PBPK models;
considerations for selection are described in Section C.1.3.

C.l.l. Data Bases Searched

EPA used the following DIALOG bibliographic data bases in the primary search. Brief
descriptions of the DIALOG data bases searched are provided in Section C.l.5.

1.	File 6: NTIS

2.	File 41: Pollution Abstracts

3.	File 55: Biosis

4.	File 153: IPA Toxicology

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5.	File 155: MedLine

6.	File 156: ToxFile

7.	File 157: Biosis Toxicology

8.	File 159: CancerLit

9.	File 336: RTECS

The PUB MED data base was used for the supplemental search.

C.1.2. Literature Search Strategy and Approach

The primary search used a tiered key-word approach, as documented below. The
principal search term was the Chemical Abstract Service Registry Number (CASRN) or specific
chemical name, 2,3,7,8-tetrachlorodibenzo-p-dioxin or 2,3,7,8-TCDD. The next tier of search
terms was species, and finally toxicokinetic keywords, as listed below. The period of the search
was 2003 through May 2009, and articles were limited to English language.

The supplemental PUB MED search was limited to the most recent five years (2004 to
present) and used four combinations of key words:

•	TCDD + pharmacokinetic + humans,

•	TCDD + toxicokinetic + humans,

•	TCDD + pharmacokinetic + animals, and

•	TCDD + toxicokinetic + animals.

C.l.2.1. Chemical Search Terms—DIALOG Search

•	CASRN: 1746-01-6

•	2,3,7,8 -tetrachl orodib enzo-p-di oxin

•	2,3,7,8-TCDD

C. 1.2.2. Primary Search Terms (Species)—DIALOG Search

•	Guinea pig(s)

•	Human(s)

•	Monkey(s)

•	Mouse

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1	• Mice

2	• Rodent(s)

3	• Rat(s)

4

5	C.l.2.3. Secondary Search Terms (Toxicologyj—DIALOG Search

6	* = truncated

7	lw = terms are within 1 word of each other and in the order specified (see search term 32)

8

1.

Absor*

16. Elimin*

32. Mechanism (lw)

2.

ADME

17. Excret*

action

3.

Aryl hydrocarbon

18. Epidemiolog*

33. Metabo*



receptor

19. Feces

34. Oral*

4.

AhR

20. Feed*

35. P450

5.

Bioavail*

21. First order kinetics

36. Partition coefficient

6.

Biliar*

22. Food*

37. PBPK

7.

Biotransform*

23. Gastro*

38. Pharmacodynamic*

8.

Cytochrome

24. Gavage*

39. Pharmacokinetic*

9.	CYP*

10.	CYP1A1

11.	CYP1A2

12.	Diet, dietary, diets

13.	Disposit*

14.	Distrib*

25.	Half-life

26.	Induct*

27.	Ingest*

28.	In silico

29.	Kinetic*

30.	Liver

40.	Physiologically
based

41.	pharmacokinetic

42.	Protein bind*

43.	Toxicokinetic*

44.	Urin*

15.

Drink*

31. Lymph*



1

2	ADME = absorption, distribution, metabolism, elimination; AhR = aryl hydrocarbon receptor; CYP = cytochrome

3	P450.

4

5

6	C.1.3. Citation Screening Procedures and Results

7	Initial DIALOG searches resulted in a very large number of citation hits. Therefore,

8	some title and key word restrictions were applied iteratively to screen out less relevant citations

9	(e.g., requiring some search terms in title, requiring 2,3,7,8-TCDD rather than just TCDD).

10	Then, using reference management software, pooled information obtained from the various

11	DIALOG data bases was screened to remove duplicates. Citations then were numbered

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sequentially (as a unique identifier). Information retrieved included the following (when
available): author(s), publication year, title, source document name, volume, and page numbers.

The DIALOG search and duplicate removal procedure produced 775 unique citations. In
the next step, all 775 citations were screened for potential applicability to updating parameters in
the Aylward and Emond PBPK models. Of these 775 citations, 26 were selected for more
detailed review to determine their potential applicability, and full publications were retrieved.
Two citations were added from the supplemental search, giving a total of 28 articles identified
for further review.

Bibliographic information for the 28 articles selected for full review is provided in the
reference list at the end of this section. Table C-l summarizes the model input parameters
potentially addressed by the selected articles.

During 2003 to May 2009, the authors of the two kinetic models under consideration
published several articles. For the Emond model, which was first published in 2004 (Emond
et al., 2004), two subsequent papers have been published (Emond et al., 2005, 2006). The
Aylward model, which originated from the 1995 papers by Carrier et al. (1995a, b), was later
updated by the same group (Aylward et al., 2005a, b). The major change implemented in the last
two papers was the description of a desorption process in the digestive tract. The transfer rate
described is slow, but for a low body burden of TCDD, this process remains significant. This
concept was reported in 2002 by Moser and McLachlan (2002). The major modifications
expected to update the Emond model are (1) consideration of the desorption process in the
gastrointestinal tract and (2) rearrangement of the elimination constant, which will have a
negligible impact on the simulation. These changes are motivated by plausible observations
reported in the literature.

Because of the body burden found in humans and the importance of selecting an
appropriate dose metric in human risk assessment, the physiological model is an important tool
for assessing the kinetics following exposure to TCDD (Kim et al., 2003). Based on the
literature identified in this search, the major contributions that should be reviewed with respect to
the Aylward and Emond kinetic models are not modes of action or pharmacokinetic mechanisms,
but rather information for verifying or improving the accuracy of some model parameters.

Pharmacokinetics typically refers to four distinct steps including absorption, distribution,

metabolism, and excretion. Physiologically-based models consider each step. In the model each

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step is parameterized to reflect better predictions of the real observations. Occasionally,
reviewing these models is essential to determine if any key processes or parameters might be
described with better accuracy. This perspective underlies the review of the literature described
here. The review indicates TCDD disposition has become recognized as relatively significant
since the publication of the Emond and Aylward models. The literature that provides
information related to improving these models, however, is limited. For the benefit of this
exercise, EPA selected the literature that would likely contribute significantly to model response,
or to clarify or confirm different key issues driving the model results. Regarding the two TCDD
models, the two major issues that should be evaluated with respect to the recent literature
identified are the elimination profile and the induction of CYP1A2.

Reviewing the elimination variation in different species and testing variable elimination
with a data set appears to be appropriate. The literature reports that various factors might
influence elimination rate. Recent publications report the influence of diverse predictors such
age, body fat, or smoking habit on the elimination half-life (Milbrath et al., 2009; Kerger et al.,
2006, 2007). Determining whether using the Milbrath et al. information would help account for
intraspecies variability in elimination rate in the Emond and Aylward kinetic models would be
useful. In 2006, Emond et al. reviewed the influence of body fat mass and CYP1A2 induction on
the pharmacokinetics of TCDD. These two factors appear to contribute significantly to
elimination and their influences seem to be driven by TCDD body burden. Mullerova and
Kopecky (2007) discussed the influence of adipose tissue and the "yoyo" effects on various
diseases that might be influenced by persistent organic pollutant distribution. One group
explored the importance of variable elimination and compared these predictions to first-order
elimination using the Aylward and Emond models and supported these approaches for risk
assessment (Heinzl et al., 2007). Two groups of authors considered a one-compartment model to
derive the elimination half-life (Aylward et al., 2009; Nadal et al., 2008). Comparing the
half-life they obtained using this approach for a range of body burden to the variable elimination
half-life would be interesting.

The second important mechanism driving the distribution and elimination of TCDD is the
induction of CYP1A2, identified as the major ligand protein in liver (Diliberto et al., 1997). For
that process, authors suggested different aspects that should be investigated, including the
importance of the dose metrics in the target tissue and the inducible level of CYP1A2 (Wilkes

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et al., 2008; Staskal et al., 2005). Other papers address the intraspecies variability of lethal
potency in mature species versus the developing fetus (Kransler et al., 2007; Korkalainen et al.,
2004). Still others point out pronounced differences among species (namely, guinea pigs,
hamsters, mice, and rats) (Bohonowych and Denison, 2007), as observed in studies of long-term
effects of low TCDD dose in liver and in studies comparing hepatic accumulation and clearance
of TCDD (Korenaga et al., 2007; Boverhof et al., 2005). The interspecies variation of the
binding affinity constant of AhR also has been reported (Connor and Aylward, 2006; Nohara
et al., 2006).

The articles identified in this literature review should be adequate to update the Aylward
and Emond models, which need to be evaluated according to the same structure of compartments
described in the literature by the two model authors.

C.1.4. References Selected for More Detailed Review for Updating the PBPK Models

Aylward, LL; Brunet, RC; Carrier, G; et al. (2004). Concentration-dependent TCDD elimination
kinetics in humans: toxicokinetic modeling for moderately to highly exposed adults from Seveso,
Italy, and Vienna, Austria, and impact on dose estimates for the NIOSH cohort. J Expo Anal
Environ Epidemiol 15(1):51—65.

Aylward, LL; Brunet, RC; Starr, TB; et al. (2005). Exposure reconstruction for the TCDD-
exposed NIOSH cohort using a concentration- and age-dependent model of elimination. Risk
Anal 25(4):945-956.

Aylward, LL; Bodner, KM; Collins, JJ; et al. (2009). TCDD exposure estimation for workers at
a New Zealand 2,4,5-T manufacturing facility based on serum sampling data. J Expo Sci
Environ Epidemiol, doi: 10.1038/jes.2009.31.

Bohonowych, JE; Denison, MS. (2007). Persistent binding of ligands to the aryl hydrocarbon
receptor. Toxicol Sci 98(1):99-109.

Boverhof, DR; Burgoon, LD; Tashiro, C; et al. (2005). Temporal and dose-dependent hepatic
gene expression patterns in mice provide new insights into TCDD-mediated hepatotoxicity.
Toxicol Sci 85(2): 1048-1063.

Connor, KT; Aylward, LL. (2006). Human response to dioxin: aryl hydrocarbon receptor (AhR)
molecular structure, function, and dose-response data for enzyme induction indicate an impaired
human AhR. J Toxicol Environ Health B 9(2): 147-171.

Heinzl, H; Mittlback, M; Edler, L. (2007). On the translation of uncertainty from toxicokinetic
to toxicodynamic models - the TCDD example. Chemosphere 67(9):S365-S374.

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Irigaray, P; Mejean, L; Laurent, F. (2005). Behaviour of dioxin in pig adipocytes. Food Chem
Toxicol 43(3):457-460.

Kerger, BD; Leung, HW; Scott, P; et al. (2006). Age- and concentration-dependent elimination
half-life of 2,3,7,8-tetrachlorodibenzo-p-dioxin in Seveso children. Environ Health Perspect
114(10): 1596—1602.

Kerger, BD; Leung, HW; Scott, PK; et al. (2007). Refinements on the age-dependent half-life
model for estimating child body burdens of polychlorodibenzodioxins and dibenzofurans.
Chemosphere 67(9):S272-S278.

Kim, AH; Kohn, MC; Nyska, A; et al. (2003). Area under the curve as a dose metric for
promotional responses following 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure. Toxicol Appl
Pharmacol 191(1): 12-21.

Korenaga, T; Fukusato, T; Ohta, M; et al. (2007). Long-term effects of subcutaneously injected
2,3,7,8-tetrachlorodibenzo-p-dioxin on the liver of rhesus monkeys. Chemosphere
67(9):S399-S404.

Korkalainen, M; Tuomisto, J; Pohjanvirta, R. (2004). Primary structure and inducibility by
2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) of aryl hydrocarbon receptor repressor in a TCDD-
sensitive and a TCDD-resistant rat strain. Biochem Biophys Res Communications
315(1): 123-131.

Kransler, KM; McGarrigle, BP; Olson, JR. (2007). Comparative developmental toxicity of
2,3,7,8-tetrachlorodibenzo-p-dioxin in the hamster, rat and guinea pig. Toxicology
229(3):214-225.

Maruyama, W; Yoshida, K; Tanaka, T; et al. (2002). Determination of tissue-blood partition
coefficients for a physiological model for humans, and estimation of dioxin concentration in
tissues. Chemosphere 46(7):975-985.

Maruyama, W; Yoshida, K; Tanaka, T; et al. (2003). Simulation of dioxin accumulation in
human tissues and analysis of reproductive risk. Chemosphere 53(4):301 -313.

Maruyama, W; Aoki, Y. (2006). Estimated cancer risk of dioxins to humans using a bioassay
and physiologically based pharmacokinetic model. Toxicol Appl Pharmacol 214(2): 188-198.

Milbrath, MO; Wenger, Y; Chang, C-W; et al. (2009). Apparent Half-Lives of Dioxins, Furans,
and Polychlorinated Biphenyls as a Function of Age, Body Fat, Smoking Status, and Breast-
Feeding. Environ Health Perspect 117(3):417-425.

Moser, GA; McLachlan, MS. (2002). Modeling digestive tract absorption and desorption of
lipophilic organic contaminants in humans. Environ Sci Technol 36(15):3318-25.

Mullerova, D; Kopecky, J. (2007). White adipose tissue: storage and effector site for
environmental pollutants. Physiol Res 56(4):375-381.

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Nadal, M; Perello, G; Schuhmacher, M; et al. (2008). Concentrations of PCDD/PCDFs in
plasma of subjects living in the vicinity of a hazardous waste incinerator: Follow-up and
modeling validation. Chemosphere 73(6):901-906.

Nohara, K; Ao, K; Miyamoto, Y; et al. (2006). Comparison of the 2,3,7,8-tetrachlorodibenzo-
p-dioxin (TCDD)-induced CYP1A1 gene expression profile in lymphocytes from mice, rats, and
humans: Most potent induction in humans. Toxicology 225(2-3):204-213.

Olsman, H; Engwall, M; Kammann, U; et al. (2007). Relative differences in aryl hydrocarbon
receptor-mediated response for 18 polybrominated and mixed halogenated dibenzo-p-dioxins
and -furans in cell lines from four different species. Environ Toxicol Chem 26(11):2448-2454.

Saghir, SA; Lebofsky, M; Pinson, DM; et al. (2005). Validation of Haber's Rule (doseX
time=constant) in rats and mice for monochloroacetic acid and 2,3,7,8-tetrachlorodibenzo-
p-dioxin under conditions of kinetic steady state. Toxicology 215(l-2):48-56.

Schecter, A; Pavuk, M; Popke, O; et al. (2003). Dioxin, dibenzofuran, and coplanar PCB Levels
in Laotian blood and milk from Agent Orange-sprayed and nonsprayed areas, 2001. J Toxicol
Environ Health A 66(21):2067-2075.

Staskal, DF; Diliberto, JJ; Devito, MJ; et al. (2005). Inhibition of human and rat CYP1A2 by
TCDD and dioxin-like chemicals. Toxicol Sci 84(2):225-231.

Toyoshiba, H; Walker, NJ; Bailer, AJ; et al. (2004). Evaluation of toxic equivalency factors for
induction of cytochromes P450 CYP1A1 and CYP1A2 enzyme activity by dioxin-like
compounds. Toxicol Appl Pharmacol 194(2): 156-168.

Wilkes, JG; Hass, BS; Buzatu, DA; et al. (2008). Modeling and assaying dioxin-like biological
effects for both dioxin-like and certain non-dioxin-like compounds. Toxicol Sci
102(1): 187—195.

1	C.1.5. Brief Descriptions of DIALOG Bibliographic Data Bases Searched

2	The National Technical Information Service (NTIS) database comprises summaries of

3	U.S. government-sponsored research, development, and engineering, plus analyses prepared by

4	federal agencies, their contractors, or grantees. It is the means through which unclassified,

5	publicly available, unlimited distribution reports are made available for sale from 240 agencies.

6	Additionally, some state and local government agencies contribute summaries of their reports to

7	the database. NTIS also provides access to the results of government-sponsored research and

8	development from countries outside the United States. Organizations that currently contribute to

9	the NTIS database include but are not limited to the following: the Japan Ministry of

10	International Trade and Industry (MITI); laboratories administered by the United Kingdom

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Department of Industry; the German Federal Ministry of Research and Technology (BMFT); and
the French National Center for Scientific Research (CNRS).

Pollution Abstracts provides access to environmental information that combines
information on scientific research and government policies in a single resource. Topics of
growing concern are extensively covered from the standpoints of atmosphere, emissions,
mathematical models, effects on people and animals, and environmental action in response to
global pollution issues. This database also contains material from conference proceedings and
hard-to-find summarized documents along with information from primary journals in the field of
pollution.

BIOSIS Previews® contains citations from Biological Abstracts® (BA) and Biological
Abstracts/Reports, Reviews, and Meetings® (BA/RRM) (formerly BioResearch Index®), the
major publications of BIOSIS®. These publications constitute the major English-language
service providing comprehensive worldwide coverage of research in the biological and
biomedical sciences. Biological Abstracts includes approximately 350,000 accounts of original
research yearly from nearly 5,000 primary journal and monograph titles. BA/RRM includes an
additional 200,000+ citations a year from meeting abstracts, reviews, books, book chapters,
notes, letters, and selected reports.

IPA Toxicology provides focused toxicology information on all phases of the
development and use of drugs and on professional pharmaceutical practice. The scope of the
database ranges from the clinical and practical to the theoretical aspects of toxicology literature.
A unique feature of abstracts reporting clinical studies is the inclusion of the study design,
number of patients, dosage, dosage forms, and dosage schedule.

Medical Literature, Analysis, and Retrieval System Online (MEDLINE®), produced by
the U.S. National Library of Medicine (NLM), is NLM's premier bibliographic database. It
contains more than 15 million references to journal articles in life sciences with a concentration
on biomedicine. The broad coverage of the database includes basic biomedical research and the
clinical sciences since 1950, including nursing, dentistry, veterinary medicine, pharmacy, allied
health, and pre-clinical sciences. MEDLINE® also covers life sciences that are vital to
biomedical practitioners, researchers, and educators, including some aspects of biology,
environmental science, marine biology, and plant and animal science, as well as biophysics and
chemistry. MEDLINE® is indexed using NLM's controlled vocabulary, Medical Subject

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Headings (MeSH®). Approximately 400,000 records are added per year, of which more than
76 percent are in English. MEDLINE® contains AIDSLINE, HealthSTAR, Toxline, In Process
(formerly known as Pre-MEDLINE®), In Data Review, and POPLINE.

ToxFile covers the toxicological, pharmacological, biochemical, and physiological
effects of drugs and other chemicals. Adverse drug reactions, chemically induced diseases,
carcinogenesis, mutagenesis, teratogenesis, environmental pollution, waste disposal, radiation,
and food contamination are typical areas of coverage. The databases Environmental Mutagen
Information Center (EMIC), Developmental and Reproductive Toxicology (DART), and Toxic
Substances Control Act Test Submissions (TSCATS) are included in ToxFile. It is not clearly
stated whether the Chemical Carcinogenesis Research Information System (CCRIS), Hazardous
Substances Data Bank (HSDB), or Genetic Toxicology Data Bank (GENE-TOX) are included in
ToxFile. Consequently, a separate, on-line search was conducted to ensure that these databases
were searched.

BIOSIS® Toxicology contains citations from BA and BA/RRM (formerly BioResearch
Index®), the major publications of BIOSIS®, that focus on toxicology and related topics.
Records are drawn from journal articles, conference papers, monographs and book chapters,
notes, letters, and reports, as well as original research. U.S. patent records are also included.

CANCERLIT® is produced by the International Cancer Research DataBank Branch
(ICRDB) of the U.S. National Cancer Institute. The database consists of bibliographic records
referencing cancer research publications dating from 1963 to 2002. Most records contain
abstracts, and all records contain citation information and additional descriptive fields such as
document type and language. Beginning with the June 1983 CANCERLIT update, records from
the MEDLINE® database dealing with cancer topics have been added to CANCERLIT.

The Registry of Toxic Effects of Chemical Substances (RTECS®) is a comprehensive
database of basic toxicity information for over 150,000 chemical substances including
prescription and non-prescription drugs, food additives, pesticides, fungicides, herbicides,
solvents, diluents, chemical wastes, reaction products of chemical waste, and substances used in
both industrial and household situations. Reports of the toxic effects of each compound are
cited. In addition to toxic effects and general toxicology reviews, data on skin and/or eye
irritation, mutation, reproductive consequences and tumorigenicity are provided. Federal
standards and regulations, National Institute for Occupational Safety and Health (NIOSH)

This document is a draft for review purposes only and does not constitute Agency policy.

C-10 DRAFT—DO NOT CITE OR QUOTE


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recommended exposure limits and information on the activities of EPA, NIOSH, National
Toxicology Program (NTP), and Occupational Safety and Health Administration (OSHA)
regarding the substance are also included. The toxic effects are linked to literature citations from
both published and unpublished governmental reports, and published articles from the scientific
literature. The database corresponds to the print version of the RTECS®, formerly known as the
Toxic Substances List, which was started in 1971. Originally prepared by the NIOSH, the
RTECS® database is now produced and distributed by Symyx Technologies, Inc.

C.2. TOXICOKINETIC MODELING CODE (EMOND ET AL., 2005)

C.2.1. Human Standard Model
C.2.1.1. Model Code

PROGRAM: 'Three Compartment PBPK Model for TCDD in Human: Standard Model
(Non-Gestation)'

!HUM_NON_GEST_ICF_F083109.csl

INITIAL !INITIALIZATION OF PARAMETERS
!SIMULATION PARAMETERS ====

CONSTANT EXP_TIME_ON
(HOUR)

CONSTANT EXP_TIME_0FF
(HOUR)

CONSTANT DAY_CYCLE
(HOUR)

CONSTANT BCK_TIME_ON
EXPOSURE BEGINS (HOUR)
CONSTANT BCK_TIME_OFF
EXPOSURE ENDS (HOUR)

0.	! TIME AT WHICH EXPOSURE BEGINS
6.132e5 ! TIME AT WHICH EXPOSURE ENDS

24.0	! NUMBER OF HOURS BETWEEN DOSES

6.132e5	! TIME AT WHICH BACKGROUND

6.132e5	! TIME AT WHICH BACKGROUND

!EXPOSURE DOSES
CONSTANT MSTOTBCKGR
(NG/KG)

CONSTANT MSTOT
CONSTANT DOSEIV
CONSTANT MW
MSTOT_NM = MSTOT/MW
MSTOT_NMBCKGR = MSTOTBCKGR/MW
DOSEIV_NM = DOSEIV/MW
NMOL/KG

0.0

! ORAL BACKGROUND EXPOSURE DOSE

1.0E-7	! ORAL EXPOSURE DOSE (NG/KG)

0.0	! INJECTED DOSE (NG/KG)

322.0	! MOLECULAR WEIGHT (G/MOL)

! CONVERTS THE DOSE TO NMOL/KG
!CONVERTS THE BACKGROUND DOSE TO NMOL/KG

! CONVERTS THE INJECTED DOSE TO

!INITIAL GUESS OF THE FREE CONCENTRATION IN THE LIGAND (COMPARTMENT
INDICATED BELOW) ====

CONSTANT CFLLI0	=0.0	! LIVER (NMOL/L)

This document is a draft for review purposes only and does not constitute Agency policy.

C-11 DRAFT—DO NOT CITE OR QUOTE


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!BINDING CAPACITY (AhR) FOR NON LINEAR BINDING (COMPARTMENT INDICATED
BELOW) ===

CONSTANT LIBMAX	=0.35	! LIVER (NMOL/L)

! PROTEIN AFFINITY CONSTANTS (1A2 OR AhR, COMPARTMENT INDICATED BELOW)

CONSTANT KDLI	=	0.1	! LIVER (AhR) (NMOL/L) WANG

ET AL.. 1997

CONSTANT KDLI2	=	4 0.0	! LIVER (1A2) (NMOL/L) EMOND ET

AL. 2004

!EXCRETION AND ABSORPTION CONSTANTS
CONSTANT KST	=	0.01	! GASTRIC RATE CONSTANT (HR-

1), EMOND ET AL., 2005

CONSTANT KABS	=	0.06	! INTESTINAL ABSORPTION CONSTANT

(HR-1), EMOND ET AL. 2005

!ELIMINATION CONSTANTS
CONSTANT CLURI	=	4.17D-8	! URINARY CLEARANCE (L/HR), EMOND

ET AL., 2005

CONSTANT KELV	=	l.le-3	! INTERSPECIES VARIABLE

ELIMINATION CONSTANT (1/HOUR)

!CONSTANT TO DIVIDE THE ABSORPTION INTO LYMPHATIC AND PORTAL FRACTIONS
CONSTANT A	=0.7	! LYMPHATIC FRACTION,

WANG ET AL. (1997)

!PARTITION COEFFICIENTS
CONSTANT PF	=	1.0e2

WANG ET AL. 1997

CONSTANT PRE	=	1.5

WANG ET AL. 1997

CONSTANT PLI	=	6.0

AL. 1997

! ADIPOSE TISSUE/BLOOD,
! REST OF THE BODY/BLOOD,
! LIVER/BLOOD, WANG ET

!PARAMETERS FOR INDUCTION OF CYP1A2
CONSTANT PAS_INDUC
= NO)

CONSTANT CYP1A2_10UTZ =

OF 1A2 (NMOL/L)

CONSTANT CYP1A2_1A1
(NMOL/L)

CONSTANT CYP1A2_1EC5 0 =

(NMOL/L)

CONSTANT CYP1A2_1A2
(NMOL/L)

CONSTANT CYP1A2_1K0UT =

(H-l)

CONSTANT CYP1A2_1TAU
CONSTANT CYP1A2_1EMAX =

(UNITLESS)

CONSTANT HILL
BINDING EFFECT CONSTANT (UNITLESS)

! DIFFUSIONAL PERMEABILITY FRACTION
CONSTANT PAFF	=	0.12

1.0

1. 6e3

1. 6e3

1. 3e2

1. 6e3

0.1

0.25
9 . 3e3

0.6

! INCLUDE INDUCTION? (1 = YES, 0

! DEGRADATION CONCENTRATION CONSTANT

! BASAL CONCENTRATION OF 1A1

! DISSOCIATION CONSTANT TCDD-CYP1A2

! BASAL CONCENTRATION OF 1A2

! FIRST ORDER RATE OF DEGRADATION

! HOLDING TIME (H)

! MAXIMUM INDUCTION OVER BASAL EFFECT

!HILL CONSTANT; COOPERATIVELY LIGAND
! ADIPOSE (UNITLESS)

This document is a draft for review purposes only and does not constitute Agency policy.

C-12 DRAFT—DO NOT CITE OR QUOTE


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CONSTANT PAREF	=	0.03

CONSTANT PALIF	=	0.35

!TISSUE BLOOD FLOW EXPRESSED AS
CONSTANT QFF	=	0.05

(UNITLESS), KRISHNAN 2008
CONSTANT QLIF	=	0.2 6

! REST OF BODY (UNITLESS)
! LIVER (UNITLESS)

A FRACTION OF CARDIAC OUTPUT =========

! ADIPOSE TISSUE BLOOD FLOW FRACTION

! LIVER (UNITLESS), KRISHNAN 2008

!COMPARTMENT TISSUE BLOOD EXPRESSED AS A FRACTION OF THE TOTAL
COMPARTMENT VOLUME =========

CONSTANT WFB0	=	0.050 ! ADIPOSE TISSUE, WANG ET AL. 1997

CONSTANT WREB0	=	0.030 ! REST OF THE BODY, WANG ET AL. 1997

CONSTANT WLIB0	=	0.266 ! LIVER, WANG ET AL. 1997

!EXPOSURE SCENARIO FOR UNIQUE OR
!NUMBER OF EXPOSURES PER WEEK
CONSTANT WEEK_LACK	=	0.0

(WEEK)

CONSTANT WEEK_PERIOD =	168.0

(HOURS)

CONSTANT WEEK_FINISH =	168.0

!NUMBER OF EXPOSURES PER MONTH
CONSTANT MONTH_LACK =	0.0

(MONTH)

REPETITIVE WEEKLY OR MONTHLY EXPOSURE
! DELAY BEFORE EXPOSURE ENDS
! NUMBER OF HOURS IN THE WEEK
! TIME EXPOSURE ENDS (HOURS)
! DELAY BEFORE EXPOSURE BEGINS

!SET FOR BACKGROUND EXPOSURE===========

!TIME CONSTANT FOR BACKGROUND EXPOSURE===========

CONSTANT Day_LACK_BG	=0.0	! DELAY BEFORE EXPOSURE BEGINS

(HOUR)

CONSTANT Day_PERIOD_BG = 24.0	! LENGTH OF EXPOSURE (HOUR)

!TIME CONSTANT FOR WEEKLY EXPOSURE
CONSTANT WEEK_LACK_BG	= 0.0	! DELAY BEFORE BACKGROUND EXPOSURE

BEGINS (WEEK)

CONSTANT WEEK_PERIOD_BG = 168.0	! NUMBER OF HOURS IN THE WEEK

(HOURS)

CONSTANT WEEK FINISH BG = 168.0	! TIME EXPOSURE ENDS (HOURS)

! CONSTANT USED IN CARDIAC OUTPUT EQUATION
CONSTANT QCC	= 15.36	! (L/KG-H), EMOND ET AL.

2004

! COMPARTMENT LIPID EXPRESSED AS THE FRACTION OF TOTAL LIPID
!Data from Emonds Thesis 2001

CONSTANT F_TOTLIP
(UNITLESS)

CONSTANT B_TOTLIP
CONSTANT RE_TOTLIP
(UNITLESS)

CONSTANT LI_TOTLIP
CONSTANT MEANLIPID

0.8000

0.0057
0.0190

0.0670
974 . 0

! ADIPOSE TISSUE

! BLOOD (UNITLESS)
! REST OF THE BODY

! LIVER (UNITLESS)

END ! END OF THE INITIAL SECTION

DYNAMIC ! DYNAMIC SIMULATION SECTION

This document is a draft for review purposes only and does not constitute Agency policy.

C-13 DRAFT—DO NOT CITE OR QUOTE


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ALGORITHM IALG
CINTERVAL CINT
MAXTERVAL MAXT
MINTERVAL MINT
VARIABLE T
CONSTANT TIMELIMIT
CONSTANT	Y0

SIMULATION
CONSTANT GROWON
GROWTH? (1 = YES, 0 = NO)
CINTXY = CINT
PFUNC = CINT

2	! GEAR METHOD

10.0	! COMMUNICATION INTERVAL

1.0e+10	IMAXIMUM INTERVAL CALCULATION

1.0E-10	!MINIMUM INTERVAL CALCULATION
0.0

1.752e5	!SIMULATION LIMIT TIME (HOUR)

0.0	! AGE (YEARS) AT BEGINNING OF

1.0	! INCLUDE BODY WEIGHT AND HEIGHT

DAY=T/24.0

WEEK =T/168.0

MONTH =T/730 . 0

YEAR=Y 0+T/8760.0

GYR =Y0 + growon*T/8 7 60.0

! TIME IN DAYS
! TIME IN WEEKS
! TIME IN MONTHS
! TIME IN YEARS
TIME FOR USE IN GROWTH EQUATION (YEARS)

DERIVATIVE ! PORTION OF CODE THAT SOLVES DIFFERENTIAL EQUATIONS

! CHRONIC OR SUBCHRONIC EXPOSURE SCENARIO
! NUMBER OF EXPOSURES PER DAY
DAY_LACK	= EXP_TIME_ON

DAY_PERIOD = DAY_CYCLE
DAY_FINISH = CINTXY
MONTH_PERIOD = TIMELIMIT
MONTH FINISH = EXP TIME OFF

DELAY BEFORE EXPOSURE BEGINS (HOURS)
EXPOSURE PERIOD (HOURS)

LENGTH OF EXPOSURE (HOURS)

EXPOSURE PERIOD (MONTHS)

LENGTH OF EXPOSURE (MONTHS)

! NUMBER OF EXPOSURES PER DAY AND MONTH
DAY_FINISH_BG = CINTXY

MONTH_LACK_BG = BCK_TIME_ON !DELAY BEFORE BACKGROUD EXPOSURE BEGINS
(MONTHS)

MONTH_PERIOD_BG = TIMELIMIT	! BACKGROUND EXPOSURE PERIOD (MONTHS)

MONTH_FINISH_BG = BCK_TIME_OFF ! LENGTH OF BACKGROUND EXPOSURE (MONTHS)

B = 1.0-A ! FRACTION OF DIOXIN ABSORBED IN THE PORTAL FRACTION OF THE LIVER

!HUMAN BODY WEIGHT GROWTH EQUATION========

! POLYNOMIAL REGRESSION EXPRESSION WRITTEN
!APRIL 10 2008, OPTIMIZED WITH DATA OF PELEKIS ET AL. 2001
! POLYNOMIAL REGRESSION EXPRESSION WRITTEN WITH
!HUH AND BOLCH 2 0 03 FOR BMI CALCULATION

! BODY WEIGHT CALCULATION

WTO = (0.0006*GYR**3 - 0.0912*GYR**2 + 4.32*GYR + 3.652)

! BODY MASS INDEX CALCULATION

BH = -2D-5*GYR**4+4.2D-3*GYR**3.0-0.315*GYR**2.0+9.7465*GYR+72.098

!HEIGHT EQUATION FORMULATED FOR USE FROM 0 TO 7 0 YEARS

BHM= (BH/10 0.0)	!HUMAN HEIGHT IN METERS (BHM)

HBMI= WTO/(BHM**2.0) ! HUMAN BODY MASS INDEX (BMI)

This document is a draft for review purposes only and does not constitute Agency policy.

C-14 DRAFT—DO NOT CITE OR QUOTE


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! ADIPOSE TISSUE FRACTION

WT0GR= WT0*1.0e3 ! BODY WEIGHT IN GRAMS

WF0= -6.3 6D-2 0*WT0GR**4.0 +1.12D-14*WT0GR**3.0 -5.8D-10*WT0GR**2.0 +1.2D-
5*WT0GR+5.91D-2

! LIVER,VOLUME,

! APPROACH BASED ON LUECKE (2007)

WLI0= (3.59D-2 -(4.76D-7*WT0GR)+(8.50D-12*WT0GR**2.0)-(5.45D-
17*WT0GR**3.0))

WRE0 = (0.91 -(WLIB0*WLI0+WFB0*WF0+WLI0+WF0))/(1.0+WREB0)

!REST OF THE BODY FRACTION; UPDATED FOR

EPA ASSESSMENT

QREF = 1.0-(QFF+QLIF)	!REST OF BODY BLOOD FLOW

QTTQF = QFF+QREF+QLIF	! SUM MUST EQUAL 1

!COMPARTMENT VOLUME (L
WF = WF0 * WTO
WRE = WRE0 * WTO
WLI = WLI0 * WTO
WB=0.07 5*WT0

OR KG) =========

! ADIPOSE

! REST OF THE BODY
! LIVER
! BLOOD

!COMPARTMENT TISSUE BLOOD (L OR KG) =========

WFB = WFB0 * WF	! ADIPOSE

WREB = WREB0 * WRE	! REST OF THE BODY

WLIB = WLIB0 * WLI	! LIVER

!CARDIAC OUTPUT FOR THE GIVEN BODY WEIGHT
QC= QCC*(WTO**0.75)	! [L BLOOD/HOUR]

QF = QFF*QC
[L/HR]

QLI = QLIF*QC
QRE = QREF*QC

! ADIPOSE TISSUE BLOOD FLOW RATE

! LIVER TISSUE BLOOD FLOW RATE [L/HR]
!REST OF THE BODY BLOOD FLOW RATE [L/HR]

QTTQ = QF+QRE+QLI

! TOTAL FLOW RATE [L/HR]

!PERMEABILITY ORGAN FLOW [L/HR] :
PAF = PAFF*QF
PARE = PAREF*QRE
PALI = PALIF*QLI

ADIPOSE

REST OF THE BODY
LIVER TISSUE

! ABSORPTION SECTION
! INTRAVENOUS
IV	= DOSEIV_NM * WTO

MSTTBCKGR = MSTOT_NMBCKGR *WT0
MSTT	= MSTOT NM * WTO

!AMOUNT IN NMOL
!AMOUNT IN (NMOL)
!AMOUNT IN NMOL

!REPETITIVE ORAL BACKGROUND EXPOSURE SCENARIOS
DAY_EX P O S U RE_B G = PULSE(DAY_LACK_BG,DAY_PERIOD_BG,DAY_FINISH_BG)
WEEK_EXPOSURE_BG = PULSE(WEEK_LACK_BG,WEEK_PERIOD_BG,WEEK_FINISH_BG)
MONTH_EXPOSURE_BG = PULSE(MONTH_LACK_BG,MONTH_PERIOD_BG,MONTH_FINISH_BG)

MSTTCH_BG = (DAY_EXPOSURE_BG*WEEK_EXPOSURE_BG*MONTH_EXPOSURE_BG)*MSTTBCKGR
MSTTFR_BG = MSTTBCKGR/CINT

CYCLE BG =DAY EXPOSURE BG*WEEK EXPOSURE BG*MONTH EXPOSURE BG

This document is a draft for review purposes only and does not constitute Agency policy.

C-15 DRAFT—DO NOT CITE OR QUOTE


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! CONDITIONAL ORAL EXPOSURE (BACKGROUND EXPOSURE)
IF (MSTTCH_BG.EQ.MSTTBCKGR) THEN
ABSMSTT_GB= MSTTFR_BG

ELSE

ABSMSTT_GB =0.0
END IF

!REPETITIVE ORAL MAIN EXPOSURE SCENARIO
DAY_EXPOSURE = PULSE(DAY_LACK,DAY_PERIOD,DAY_FINISH)

WEEK_EXPOSURE = PULSE(WEEK_LACK,WEEK_PERIOD,WEEK_FINISH)

MONTH_EXPOSURE = PULSE(MONTH_LACK,MONTH_PERIOD,MONTH_FINISH)

MSTTCH = (DAY_EXPOSURE*WEEK_EXPOSURE*MONTH_EXPOSURE)*MSTT
CYCLE = DAY_EXPOSURE*WEEK_EXPOSURE*MONTH_EXPOSURE
MSTTFR=MSTT/CINT

!CONDITIONAL ORAL EXPOSURE
IF (MSTTCH.EQ.MSTT) THEN

ABSMSTT= MSTTFR
ELSE

ABSMSTT = 0.

END IF

CYCLETOT=INTEG(CYCLE, 0.0)

! MASS Balance CHANGE IN THE LUMEN
RMSTT= -(KST+KABS)*MST+ABSMSTT +ABSMSTT_GB ! RATE OF CHANGE (NMOL/H)
MST = INTEG(RMSTT,0.)	!AMOUNT REMAINING IN GI TRACT

(NMOL)

! ABSORPTION IN LYMPH CIRCULATION
LYRMLUM = KABS*MST*A
LYMLUM = INTEG(LYRMLUM,0.0)

! ABSORPTION IN PORTAL CIRCULATION
LIRMLUM = KABS*MST*B

LIMLUM = INTEG(LIRMLUM,0.0)

! PERCENT OF DOSE REMAINING IN THE GI TRACT
PRCT_remain_GIT = 100.0*MST/(MSTT+1E-30)

!IV ABSORTPION SCENARIO 	

IVR= IV/PFUNC ! RATE FOR IV INFUSION IN BLOOD
EXPIV= IVR * (1.0-STEP(PFUNC))

IVDOSE = integ(EXPIV,0.0)

!SYSTEMIC BLOOD COMPARTMENT
! MODIFICATION OCT 8 2009
CB=(QF*CFB+QRE*CREB+QLI*CLIB+EXPIV+LYRMLUM)/(QC+CLURI) !

CA = CB	!CONCENTRATION (NMOL/L)

!CB=(QF*CFB+QRE*CREB+QLI*CLIB+EXPIV+LYRMLUM-RAURI)/QC !

! CA = CB	! CONCENTRATION (NMOL/L)

This document is a draft for review purposes only and does not constitute Agency policy.

C-16 DRAFT—DO NOT CITE OR QUOTE


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!URINARY EXCRETION BY KIDNEY
! MODIFICATION OCT 8 2009
RAURI = CLURI *CB

AURI = INTEG(RAURI,0.0)

! CONCENTRATION UNIT
PRCT_B = 100.0*CB/(MSTT+1E-30)	! PERCENT OF DOSE

CBSNGKGLIADJ = CB*MW/(0.55*B TOTLIP) !serum concentration in lipid adjust
(PG/G LIPID=PPT)	~

CBPPT = CBSNGKGLIADJ
CBNGKG = CB*MW

CBpptRH = CB*MW*10000/(0.55*MEANLIPID) !SERUM CONCENTRATION IN LIPID ADJUST
(PG/G LIPID=PPT)

AUC CBSNGKGLIADJ=INTEG(CBSNGKGLIADJ,0.0)

!ADIPOSE TISSUE COMPARTMENT
RAFB= QF*(CA-CFB)-PAF*(CFB-CF/PF)
AFB = INTEG(RAFB,0.0)
CFB = AFB/WFB

!TISSUE SUBCOMPARTMENT
RAF = PAF*(CFB-CF/PF)
AF = INTEG(RAF,0.0)

CF = AF/WF

!(NMOL/HR)

!(NMOL)
!(NMOL/KG)

!(NMOL/HR)

!(NMOL)
!(NMOL/KG)

!POST SIMULATION UNIT CONVERSION
CFTOTAL = (AF + AFB)/(WF + WFB) ! TOTAL CONCENTRATION NMOL/ML
PRCT_F = 100.0*CFTOTAL/(MSTT+1E-30)

CFNGKG =CFTOTAL*MW

!REST OF THE BODY COMPARTMENT========

RAREB= QRE*(CA-CREB)-PARE*(CREB-CRE/PRE) !(NMOL/HR)
AREB = INTEG(RAREB,0.0)	!(NMOL)

CREB = AREB/WREB	!(NMOL/KG)

!TISSUE SUBCOMPARTMENT
RARE = PARE*(CREB-CRE/PRE)	!(NMOL/HR)

ARE = INTEG(RARE,0.0)	!(NMOL)

CRE = ARE/WRE	!(NMOL/KG)

!POST SIMULATION UNIT CONVERSION
CRETOTAL = (ARE + AREB)/(WRE + WREB) ! TOTAL CONCENTRATION IN NMOL/ML
PRCT RE = 100.0*CRETOTAL/(MSTT+1E-30) ! PERCENT OF DOSE

!LIVER COMPARTMENT
!TISSUE BLOOD SUBCOMPARTMENT
RALIB = QLI*(CA-CLIB)-PALI*(CLIB-CFLLIR)+LIRMLUM	!(NMOL/HR)

ALIB = INTEG(RALIB,0.0)	!(NMOL)

CLIB = ALIB/WLIB

!TISSUE SUBCOMPARTMENT
RALI = PALI*(CLIB-CFLLIR)-REXCLI	!(NMOL/HR)

ALI = INTEG(RALI,0.0)	!(NMOL)

CLI = ALI/WLI	!(NMOL/KG)

This document is a draft for review purposes only and does not constitute Agency policy.

C-17 DRAFT—DO NOT CITE OR QUOTE


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!FREE TCDD IN LIVER
! MODIFICATION OCTOBER 8 2009
CFLLI= IMPLC(CLI-(CFLLIR*PLI+(LIBMAX*CFLLIR/(KDLI+CFLLIR)) &

+ ( (CYP1A2_103*CFLLIR/(KDLI2+CFLLIR)*PAS_INDUC) ) )-CFLLI, CFLLI0) !
CONCENTRATION OF FREE TCDD IN LIVER
CFLLIR=DIM(CFLLI,0.0)

!MODIFIED FROM:

!PARAMETER (LIVER_1RMN = 1.0E-30)

! CFLLI= IMPLC(CLI-(CFLLIR*PLI+(LIBMAX*CFLLIR/(KDLI+CFLLIR &
+LIVER_1RMN))+((CYP1A2_103*CFLLIR/(KDLI2+CFLLIR &

!	+LIVER_1RMN)*PAS_INDUC)))-CFLLI,CFLLI0)

! CFLLIR=DIM(CFLLI,0.0)

CBNDLI= LIBMAX*CFLLIR/(KDLI+CFLLIR) !CONC OF TCDD BOUDN TO AhR
!CBNDLI= LIBMAX*CFLLIR/(KDLI+CFLLIR+LIVER 1RMN) !CONC BIND

!POST SIMULATION UNIT CONVERSION
CLITOTAL = (ALI + ALIB)/(WLI + WLIB)

PRCT_LI = 100.0*CLITOTAL/(MSTT+1.0E-30)
rec_occ_AHR= 100.0*CFLLIR/(KDLI+CFLLIR+1.0)
OCCUPANCY

PROT_occ_lA2= 100.0*CFLLIR/(KDLI2+CFLLIR)
OCCUPANCY

CLINGKG= CLITOTAL*MW
CBNDLINGKG = CBNDLI*MW

! TOTAL CONCENTRATION IN NMOL/ML

! PERCENT BOUND TO AhR

! PERCENT BOUND TO 1A2

[NG TCDD/KG]

!FRACTION INCREASE OF INDUCTION OF CYP1A2
fold_ind=CYPlA2_10UT/CYPlA2_lA2

VARIATIONOFAC =(CYP1A2_10UT-CYP1A2_1A2)/CYP1A2_1A2

!VARIABLE ELIMINATION BASED ON THE CYP1A2
KBILE_LI_T = Kelv*VARIATIONOFAC!

REXCLI = KBILE_LI_T*CFLLIR*WLI ! DOSE-DEPENDENT RATE OF BILLIARY EXCRETION
OF DIOXIN

EXCLI = INTEG(REXCLI,0.0) !TOTAL AMOUNT OF DIOXIN EXCRETED

!CHEMICAL IN CYP450 (1A2) COMPARTMENT
!PARAMETER FOR INDUCTION OF CYP1A2

CYP1A2_1KINP = CYP1A2_1K0UT*CYP1A2_10UTZ ! BASAL RATE OF CYP1A2 PRODUCTION
SET EQUAL TO BASAL RATE OF DEGRDATION AT STEADY STATE

! MODIFICATION OCTOBER 8 2009
CYP1A2_10UT =INTEG(CYP1A2_1KINP * (1.0 + CYP1A2_1EMAX *(CBNDLI+1.0e-30)**HILL
&

/(CYP1A2_1EC50**HILL + (CBNDLI+1.0e-30)**HILL)) &
- CYP1A2_1K0UT*CYP1A2_10UT, CYP1A2_10UTZ) ! LEVELS OF CYP1A2
! MODEIFIED FROM:

!PARAMETER (CYP1A2_1RMN = le-30)

!CYP1A2_10UT =INTEG(CYP1A2_1KINP * (1 + CYP1A2_1EMAX *(CBNDLI &

!	+CYP1A2 1RMN)**HILL/(CYP1A2 1EC50 + (CBNDLI + CYP1A2 1RMN)**HILL) &

This document is a draft for review purposes only and does not constitute Agency policy.

C-18 DRAFT—DO NOT CITE OR QUOTE


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!	+CYP1A2_1RMN) - CYP1A2_1K0UT*CYP1A2_1&

!	OUT, CYP1A2_10UTZ)

! EQUATIONS INCORPORATING DELAY OF CYP1A2 PRODUCTION (NOT USED IN
SIMULATIONS)

CYP1A2_1R02 = (CYP1A2_10UT - CYP1A2_102)/ CYP1A2_1TAU
CYP1A2_102 =INTEG(CYP1A2_1R02, CYP1A2_1A1)

CYP1A2_1R03 = (CYP1A2_102 - CYP1A2_103)/ CYP1A2_1TAU
CYP1A2_103 =INTEG(CYP1A2_1R03, CYP1A2_1A2)

!CHECK MASS BALANCE
BDOSE= LYMLUM+LIMLUM+IVDOSE

BMASSE = EX C LI+AURI+AFB+AF+AREB+ARE+ALIB+ALI
BDIFF = BDOSE-BMASSE

! BODY BURDEN IN TERMS OF CONCENTRATION (NG/KG)

BBNGKG = (AFB+AF+AREB+ARE+ALIB+ALI)*MW/WT0	!

!COMMAND END OF THE SIMULATION
TERMT (T.GE. TIMELIMIT, 'Time limit has been reached.')

END ! END OF THE DERIVATIVE SECTION
END ! END OF THE DYTNAMIC SECTION
END ! END OF THE PROGRAM

C.2.1.2. Input File

% base file name = "TESTJULY2009.m"

%clear ©variable
output 0clear

prepare 0clear year T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG CBNGKG
%output 0all

% PARAMETERS FOR SIMULATION
CINT = 1 %0.5

% TIME AT WHICH EXPOSURE BEGINS (HOUR)

%324120	% HOUR/YEAR !TIME AT WHICH EXPOSURE

EXP_TIME_ON = 0.
EX P_TIME_0 FF = 613200
ENDS (HOUR)

DAY_CYCLE =24
B C K_TIME_ON = 613200
BEGINS (HOUR)
BCK_TIME_OFF = 613200
ENDS (HOUR)

TIMELIMIT = 613200
(HOUR)

MSTOTBCKGR = 0.

5 NUMBER OF HOURS BETWEEN DOSES (HOUR)

5324120	% TIME AT WHICH BACKGROUND EXPOSURE

5324120	% TIME AT WHICH BACKGROUND EXPOSURE

5324120	%324120	% SIMULATION TIME LIMIT

5 ORAL BACKGROUND EXPOSURE DOSE (UG/KG)

% oral dose oral dose oral dose
MSTOT	= 9.97339283634997E-07

DOSEIV	= 0	%NG/KG

% oral dose oral dose oral dose

ORAL DAILY EXPOSURE DOSE (NG/KG)

MEANLIPID = 730
PAS INDUC= 1

INDUCTION INCLUDED? (1=YES, 0=NO)

This document is a draft for review purposes only and does not constitute Agency policy.

C-19 DRAFT—DO NOT CITE OR QUOTE


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C.2.2. Human Gestational Model

C.2.2.1. Model Code

PROGRAM: 'Three Compartment PBPK Model for TCDD in Human (Gestation)'

! Parameters were change may 16, 2002
! Come from {8MAI_CHR_PRE-EXP_GD}

! Come from {12 Mouse GDJfile

!{{IMPORTANT-IMPORTANT-IMPORTANT-IMPORTANT}}

! REDUCTION OF MOTHER AND FETUS COMPARTMENT
! 2M_R_TCDD_JULY2 0 02 ////(JULY 18,20 02)////

!TCDD_RED_4Species_2003_4	////(APR 8 ,2003)////

!TCDD_RED_4Species_2003_9	////(APR 17 ,2003)////

!TCDD_RED_4Species_2003_12	////(APR 17 ,2003)////

!APRIL 18 2003

!TCDD_4C_4SP_2 0 03	////(APR 18 ,2003)////

! was ''Gest 4 species l.csl'' but update July 2009

!GEST HUM 0 45Y 4 ICF afterKKfix v3 humangestational.csl
!HUM_GESTATIONAL_ICF_F083109.csl
!HUM_GESTATIONAL_ICF_F10 07 0 9.csl

!Legend/Legend/Legend/Legend/Legend/Legend/Legend/Legend/

!Legend for this PBPK model

IMating: control the tenure of exchange between fetus and
IMother and also control imitated tissue growth
!Control: WTFE, WPLA0, QPLAF
!(for rat, mouse, human, and monkey)

!Control transfer from mother to fetus and fetus to mother by TRANSTIME ON
!SWITCH_trans = 0 NO TRANSFER	~

!SWITCH_trans = 1 TRANSFER OCCURS
! These switches are also controlled by mating parameters

INITIAL !

!SIMULATION PARAMETERS
CONSTANT PARA_ZERO
CONSTANT EXP_TIME_ON
CONSTANT EXP_TIME_0FF
CONSTANT DAY_CYCLE
CONSTANT BCK_TIME_ON
BEGINS (HOURS)

CONSTANT BCK_TIME_OFF
(HOURS)

CONSTANT TRANSTIME_ON

AT 9 WEEKS OR 1512 HOURS OF GESTATION

! INTRAVENOUS SEQUENCY
CONSTANT IV_LACK	=0.0

CONSTANT IV_PERIOD	=0.0

!PREGNANCY PARAMETER

= le-30

0.0	!TIME AT WHICH EXPOSURE BEGINS (HOURS)

530.0	!TIME AT WHICH EXPOSURE ENDS (HOURS)

2 4.0	!NUMBER OF HOURS BETWEEN DOSES (HOURS)

0.0	!TIME AT WHICH BACKGROUND EXPOSURE

0.0	!TIME AT WHICH BACKGROUND EXPOSURE ENDS

0.0	!CONTROL TRANSFER FROM MOTHER TO FETUS

This document is a draft for review purposes only and does not constitute Agency policy.

C-20 DRAFT—DO NOT CITE OR QUOTE


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CONSTANT MATTING
CONSTANT PFETUS
CONSTANT CLPLA_FET
(L/HR)

=0.0	!BEGINNING OF MATING (HOUR)

=4.0	!PARTITION COEFFICIENT

= 1.0e-3 !CLEARANCE TRANSFER FOR MOTHER TO FETUS

! CONSTANT EXPOSURE CONTROL

!ACUTE, SUBCHRONIC, CHRONIC EXPOSURE =====

!OR BACKGROUND EXPOSURE (IN THIS CASE 3 TIMES A DAY)===

CONSTANT MSTOTBCKGR	=0.0	! ORAL BACKGROUND EXPOSURE DOSE (NG/KG)

CONSTANT MSTOT	=0.0	! ORAL EXPOSURE DOSE (NG/KG)

!ORAL ABSORPTION

! MSTT= MSTOT/10 0 0 *WT0 *1/322*1000 !AMOUNT IN NMOL
MSTOT NM = MSTOT/MW	!CONVERTS THE DOSE TO NMOL/KG

!INTRAVENOUS ABSORPTION

CONSTANT DOSEIV =0.0	! INJECTED DOSE (NG/KG)

DOSEIV_NM = DOSEIV/MW	! CONVERTS THE INJECTED DOSE TO NMOL/KG

CONSTANT DOSEIVLATE =0.0	!INJECTED DOSE LATE (UG/KG)

DOSEIVNMlate = DOSEIVLATE/MW	!AMOUNT IN NMOL/G

!INITIAL GUESS OF THE FREE CONCENTRATION IN THE LIGAND (COMPARTMENT
INDICATED BELOW)====

CONSTANT CFLLI0	= 0.0	!LIVER (NMOL/L)

CONSTANT CFLPLA0	= 0.0	!PLACENTA (NMOL/L)

!BINDING CAPACITY	(AhR) FOR NON LINEAR BINDING (COMPARTMENT INDICATED
BELOW) (NMOL/L) ===

CONSTANT LIBMAX	=0.35 ! LIVER (NMOL/L)

CONSTANT PLABMAX	= 0.2 !TEMPORARY PARAMETER

!PROTEIN AFFINITY CONSTANTS	(1A2 OR AhR, COMPARTMENT INDICATED BELOW)
(NMOL/ML)===

CONSTANT KDLI = 0.1	!LIVER (AhR) (NMOL/L), WANG ET AL. 1997

CONSTANT KDLI2 = 40.0	!LIVER (1A2) (NMOL/L), EMOND ET AL.
2004

CONSTANT KDPLA =0.1	!ASSUME IDENTICAL TO KDLI (AhR)

!EXCRETION AND ABSORPTION CONSTANT
CONSTANT KST	=0.01	! GASTRIC RATE CONSTANT (HR-1), EMOND ET

AL. 2005

CONSTANT KABS	= 0.06	! INTESTINAL ABSORPTION CONSTANT (HR-1),

EMOND ET AL. (2005)

!INTERSPECIES ELIMINATION CONSTANT
!TEST ELIMINATION VARIABLE, EMOND ET AL. 2005
CONSTANT KELV	=	l.le-3 !4.OD-3	! INTERSPECIES VARIABLE

ELIMINATION CONSTANT (1/HOUR)

! ELIMINATION CONSTANTS
CONSTANT CLURI	= 4.17e-8 ! URINARY CLEARANCE (L/HR), EMOND ET AL.

2005

! CONSTANT TO DIVIDE THE ABSORPTION INTO LYMPHATIC AND PORTAL FRACTIONS
CONSTANT A	=0.7	! LYMPHATIC FRACTION, WANG ET AL. 1997

This document is a draft for review purposes only and does not constitute Agency policy.

C-21 DRAFT—DO NOT CITE OR QUOTE


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!PARTITION COEFFICIENTS

CONSTANT PF	= 1.0e2

CONSTANT PRE	=1.5
1997

CONSTANT PLI	= 6.0

CONSTANT PPLA	=1.5
WANG ET AL. 1997

! ADIPOSE TISSUE/BLOOD, WANG ET AL. 1997
! REST OF THE BODY/BLOOD, WANG ET AL.

! LIVER/BLOOD, WANG ET AL. 19 97
! TEMPORARY PARAMETER NOT CONFIGURED,

!PARAMETER FOR INDUCTION OF CYP

CONSTANT PAS_INDUC
CONSTANT CYP1A2_10UTZ
1A2 (NMOL/L)

CONSTANT CYP1A2_1A1
CONSTANT CYP1A2_1EC5 0
(NMOL/L)

CONSTANT CYP1A2_1A2
CONSTANT CYP1A2_1K0UT
CONSTANT CYP1A2_1TAU
CONSTANT CYP1A2_1EMAX
(UNITLESS)

CONSTANT HILL
BINDING EFFECT CONSTANT

= 1.0
= 1.6e3

= 1.6e3
= 1.3e2

= 1.6e3
= 0.1
= 0.25
= 9.3e3

= 0.6
(UNITLESS)

1A2, WANG ET AL. 1997

! INCLUDE INDUCTION? (1 = YES, 0 = NO)
! DEGRADATION CONCENTRATION CONSTANT OF

! BASAL CONCENTRATION OF 1A1 (NMOL/L)
! DISSOCIATION CONSTANT TCDD-CYP1A2

!BASAL CONCENTRATION OF 1A2 (NMOL/ML)
! FIRST ORDER RATE OF DEGRADATION (H-l)
!HOLDING TIME (H)

! MAXIMUM INDUCTION OVER BASAL EFFECT

!HILL CONSTANT; COOPERATIVELY LIGAND

!DIFFUSIONAL PERMEABILITY FRACTION, WANG ET AL (1997)

CONSTANT PAFF
CONSTANT PAREF
CONSTANT PALIF
CONSTANT PAPLAF

= 0. 12
= 0. 03
= 0.35
= 0.3

ADIPOSE (UNITLESS)

REST OF THE BODY (UNITLESS)
LIVER (UNITLESS)

OPTIMIZED PARAMETER

!TISSUE BLOOD FLOW EXPRESSED AS A FRACTION OF CARDIAC OUTPUT, KRISHNAN 2007
CONSTANT QFF	=0.05	! ADIPOSE TISSUE BLOOD FLOW FRACTION

(UNITLESS), KRISHNAN 2008

CONSTANT QLIF	= 0.26	! LIVER (UNITLESS), KRISHNAN 2008

!===FRACTION OF TISSUE BLOOD WEIGHT Wang et al

(1997)

CONSTANT WFB0
CONSTANT WREB0
CONSTANT WLIB0
CONSTANT WPLAB0

0.050	!ADIPOSE TISSUE, WANG ET AL. 1997

0.030	!REST OF THE BODY, WANG ET AL. 1997

0.266	!LIVER, WANG ET AL. 1997

0.500	!ASSUME HIGHLY VASCULARIZED

! EXPOSURE SCENARIO FOR UNIQUE OR REPETITIVE WEEKLY OR MONTHLY EXPOSURE
! NUMBER OF EXPOSURES PER WEEK

CONSTANT WEEK_LACK	=0.0	!DELAY BEFORE EXPOSURE ENDS (WEEK)

CONSTANT WEEK_PERIOD	= 168.0	! NUMBER OF HOURS IN THE WEEK (HOURS)

CONSTANT WEEK FINISH	= 168.0	! TIME EXPOSURE ENDS (HOURS)

! NUMBER OF EXPOSURES PER MONTH
CONSTANT MONTH LACK	=0.0

!DELAY BEFORE EXPOSURE BEGINS (MONTHS)

CONSTANT FOR BACKGROUND EXPOSURE=

CONSTANT Day_LACK_BG	=0.0

CONSTANT Day_PERIOD_BG =24.0

! DELAY BEFORE EXPOSURE BEGINS (HOURS)
!LENGTH OF EXPOSURE (HOURS)

! NUMBER OF EXPOSURES PER WEEK
CONSTANT WEEK_LACK_BG =0.0
(WEEK)

!DELAY BEFORE BACKGROUD EXPOSURE BEGINS

This document is a draft for review purposes only and does not constitute Agency policy.

C-22 DRAFT—DO NOT CITE OR QUOTE


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CONSTANT WEEK_PERIOD_BG = 168.0
CONSTANT WEEK FINISH BG = 168.0

! NUMBER OF HOURS IN THE WEEK (HOURS)
!TIME EXPOSURE ENDS (HOURS)

! CONSTANT USED IN CARDIAC OUTPUT EQUATION

CONSTANT QCC	= 15.36 ![L/KG-H], EMOND ET AL. 2004

! COMPARTMENT LIPID EXPRESSED AS THE FRACTION OF TOTAL LIPID
!Data from Emonds Thesis 2001

CONSTANT F_TOTLIP
CONSTANT B_TOTLIP
CONSTANT RE_TOTLIP
CONSTANT LI_TOTLIP
CONSTANT PLA_TOTLIP
CONSTANT FETUS TOTLIP

0.8000	! ADIPOSE TISSUE (UNITLESS)

0.0057	! BLOOD (UNITLESS)

0.0190	! REST OF THE BODY (UNITLESS)

0.0670	! LIVER (UNITLESS)

0.019	! PLACENTA (UNITLESS)

0.019	! FETUS (UNITLESS)

CONSTANT MEANLIPID

974

END ! END OF THE INITIAL SECTION

DYNAMIC ! DYNAMIC SIMULATION SECTION

ALGORITHM

CINTERVAL

MAXTERVAL

MINTERVAL

VARIABLE

CONSTANT

CONSTANT

SIMULATION

CONSTANT

IALG
CINT
MAXT
MINT
T

TIMELIMIT
Y0

GROWON

GROWTH? (1=YES, 0=NO)

CINTXY = CINT
PFUNC = CINT

2
0.1
1.0e+10
1.0E-10
0.0
100
0.0

1.0

GEAR METHOD

COMMUNICATION INTERVAL
MAXIMUM CALCULATION INTERVAL
MINIMUM CALCULATION INTERVAL

!SIMULATION LIMIT TIME (HOUR)
! AGE (YEARS) AT BEGINNING OF

! INCLUDE BODY WEIGHT AND HEIGHT

!TIME TRANSFORMATION
DAY= T/24.0
WEEK =T/168.0
YEAR=Y0+T/8760 . 0
GYR =Y0 + growon*T/8 7 60.0
EQUATION

! TIME IN YEARS
! TIME FOR USE IN GROWTH

DERIVATIVE ! PORTION OF CODE THAT SOLVES DIFFERENTIAL EQUATIONS

!====== CHRONIC OR SUBCHRONIC EXPOSURE SCENARIO

! NUMBER OF EXPOSURES PER DAY

DAY_LACK
DAY_PERIOD
DAY_FINISH
MONTH_PERIOD
MONTH FINISH

EXP_TIME_ON
DAY_CYCLE
CINTXY
TIMELIMIT
EXP TIME OFF

DELAY BEFORE EXPOSURE BEGINS
EXPOSURE PERIOD (HOURS)
LENGTH OF EXPOSURE (HOURS)
EXPOSURE PERIOD (MONTHS)
LENGTH OF EXPOSURE (MONTHS)

(HOURS)

! NUMBER OF EXPOSURES PER DAY AND MONTH

This document is a draft for review purposes only and does not constitute Agency policy.

C-23 DRAFT—DO NOT CITE OR QUOTE


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DAY_FINISH_BG	= CINTXY

MONTH_LACK_BG	= BCK_TIME_ON !DELAY BEFORE BACKGROUND EXPOSURE BEGINS
(MONTHS)

MONTH_PERIOD_BG	= TIMELIMIT	!BACKGROUND EXPOSURE PERIOD (MONTHS)

MONTH FINISH BG	= BCK TIME OFF !LENGTH OF BACKGROUND EXPOSURE (MONTHS)

! INTRAVENOUS LATE
IV_FINISH = CINTXY

B = 1-A ! FRACTION OF DIOXIN ABSORBED IN THE PORTAL FRACTION OF THE LIVER

! MOTHER BODY WEIGHT GROWTH EQUATION
! MODIFICATION TO ADAPT THIS MODEL AT HUMAN MODEL

! BECAUSE LINEAR DESCRIPTION IS NOT GOOD ENOUGH FOR MOTHER GROWTH
! MOTHER BODY WEIGHT GROWTH
! HUMAN BODY WEIGHT (0 TO 4 5 YEARS)

! POLYNOMIAL REGRESSION EXPRESSION WRITTEN

!APRIL 10 2008, OPTIMIZED WITH DATA OF PELEKIS ET AL. 2001
! POLYNOMIAL REGRESSION EXPRESSION WRITTEN WITH
!HUH AND BOLCH 2 0 03 FOR BMI CALCULATION

! BODY WEIGHT CALCULATION. UNIT IN KG FOR GESTATIONAL PORTION
WTO = (0.0006*GYR**3 - 0.0912*GYR**2 + 4.32*GYR + 3.652)
!BODY MASS INDEX CALCULATION

BH = -2D-5*GYR**4+4.2D-3*GYR**3.0-0.315*GYR**2.0+9.7465*GYR+72.098
!HEIGHT EQUATION FORMULATED FOR USE FROM 0 TO 7 0 YEARS
BHM= (BH/100.0)!HUMAN HEIGHT IN METER (BHM)

HBMI= WTO/(BHM**2.0) ! HUMAN BODY MASS INDEX (BMI)

!MODIFICATION IN KG

RTESTGEST= T-MATTING ! STARTING TIME FOR FETAL GROWTH
TESTGEST=DIM(RTESTGEST,0.0)

! GROWTH OF FETAL TISSUE

GESTATTION_FE=((4d-15*TESTGEST**4 -3d-ll*TESTGEST**3 +ld-7*TESTGEST**2 -8d-
5*TESTGEST +0.0608))

WTFER= DIM(GESTATTION_FE,0.0) ! FETAL COMPARTMENT WEIGHT
WTFE= WTFER

!///////////////////////////////////////////////////////////////////////
! FAT GROWTH EXPRESSION LINEAR DURING PREGNANCY
! FROM O'FLAHERTY_19 92
!///////////////////////////////////////////////////////////////////////

WT0GR= WT0*1.0e3 ! MOTHER BODY WEIGHT IN G

WF0 =(-6.36D-20*WT0GR**4.0 +1.12D-14*WT0GR**3.0 &

-5.8D-10*WT0GR**2.0+1.2D-5*WT0GR+5.91D-2) ! MOTHER FAT COMPARTMENT

GROWTH

!///////////////////////////////////////////////////////////////////////
! WPLA PLACENTA GROWTH EXPRESSION, SINGLE EXPONENTIAL WITH OFFSET
! FROM O'FLAHERTY_19 92 ! FOR EACH PUP
!///////////////////////////////////////////////////////////////////////

This document is a draft for review purposes only and does not constitute Agency policy.

C-24 DRAFT—DO NOT CITE OR QUOTE


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!SAME EQUATION THEN THE FORST MODEL. BODY WEIGHT KEPT IN G
!A CORRECTION FOR THE BODY WEIGHT (WTO(KG)*1000 = WTOGR)

WPLA0N_HUMAN= (850*exp(-9.434*(exp(-5.23d-4*(TESTGEST)))))
WPLA0R = WPLA0N_HUMAN/WTOGR

WPLA0W = DIM(WPLA0R,0.0) ! PLACENTA WEIGHT
WPLA0=WPLA0W

!///////////////////////////////////////////////////////////////////////
! QPLA PLACENTA GROWTH EXPRESSION, DOUBLE EXPONENTIAL WITH OFFSET
! FROM O'FLAHERTY_19 92
!///////////////////////////////////////////////////////////////////////

QPLAF_HUMAN = SWITCH_trans*( (ld-10*TESTGEST**3.0 -5D-7*TESTGEST**2.0
+0.0 017*TESTGEST+1.1937)/QC)

GEST_QPLAF=DIM(QPLAF_HUMAN,0.0) ! PLACENTA BLOOD FLOW RATE
QPLAF =GEST_QPLAF

! LIVER,VOLUME (HUMAN 0 TO 7 0 YEARS)

! APPROACH BASED ON LUECKE (2007)

WLI0= (3.5 9D-2 -(4.7 6D-7*WT0GR)+(8.5 0D-12*WT0GR**2.0)-(5.4 5D-17*WT0GR**3.0))
! LIVER VOLUME IN GROWING HUMAN

! VARIABILITY OF REST OF THE BODY DEPENDS ON OTHER ORGAN
WRE0 = (0.91-(WLIB0*WLI0+WFB0*WF0+ WPLAB0*WPLA0 + WLI0 + WF0 +
WPLA0))/(1+WREB0)

QREF = 1-(QFF+QLIF+QPLAF)	!REST BODY BLOOD FLOW (ML/HR)

QTTQF = QFF+QREF+QLIF+QPLAF	! SUM MUST EQUAL 1

! COMPARTMENT TISSUE BLOOD VOLUME (L)
WF = WF0 * WTO
WRE = WRE0 * WTO
WLI = WLI0 * WTO
WPLA= WPLA0* WTO

ADIPOSE TISSUE
REST OF THE BODY
LIVER
PLACENTA

! COMPARTMENT TISSUE VOLUME (L)
WFB = WFB0 * WF
WREB = WREB0 * WRE
WLIB = WLIB0 * WLI
WPLAB = WPLAB0* WPLA

ADIPOSE TISSUE
REST OF THE BODY
LIVER
PLACANTA

! TOTAL VOLUME OF COMPARTMENT (L)
WFT = WF
WRET = WRE
WLIT = WLI
WPLAT= WPLAB

TOTAL ADIPOSE TISSUE
TOTAL REST OF THE BODY
TOTAL LIVER TISSUE
TOTAL PLACENTA TISSUE

! CONSTANT USED IN CARDIAC OUTPUT EQUATION

! UNIT CHANGED ON JULY 14 2009 (L/HR)
QC= QCC*(WTO)**0.75

QF = QFF*QC
QLI = QLIF*QC
QRE = QREF*QC
QPLA = QPLAF*QC

ADIPOSE TISSUE BLOOD FLOW RATE (L/HR)
LIVER TISSUE BLOOD FLOW RATE (L/HR)
REST OF THE BODY BLOOD FLOW RATE (L/HR)
PLACENTA TISSUE BLOOD FLOW RATE (L/HR)

This document is a draft for review purposes only and does not constitute Agency policy.

C-25 DRAFT—DO NOT CITE OR QUOTE


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QTTQ = QF+QRE+QLI+QPLA	!TOTAL FLOW RATE (L/HR)

! ========= DIFFUSIONAL PERMEABILITY

PAF = PAFF*QF
PARE = PAREF*QRE
(L/HR)

PALI = PALIF*QLI
PAPLA = PAPLAF*QPLA

FACTORS FRACTION ORGAN FLOW =========

! ADIPOSE TISSUE BLOOD FLOW RATE (L/HR)
! REST OF THE BODY BLOOD FLOW RATE

! LIVER TISSUE BLOOD FLOW RATE (L/HR)
! PLACENTA TISSUE BLOOD FLOW RATE (L/HR)

ABSORPTION SECTION
ORAL

INTRAPERITONEAL

SUBCUTANEOUS

INTRAVENOUS

!BACKGROUND EXPOSURE

!EXPOSURE FOR STEADY STATE CONSIDERATION
!REPETITIVE EXPOSURE SCENARIO

MSTOT_NMBCKGR = MSTOTBCKGR/322	!AMOUNT IN NMOL/G

MSTTBCKGR =MSTOT_NMBCKGR *WT0

DAY_EX P O S U RE_B G = PULSE(DAY_LACK_BG,DAY_PERIOD_BG,DAY_FINISH_BG)
WEEK_EXPOSURE_BG = PULSE(WEEK_LACK_BG,WEEK_PERIOD_BG,WEEK_FINISH_BG)
MONTH_EXPOSURE_BG = PULSE(MONTH_LACK_BG,MONTH_PERIOD_BG,MONTH_FINISH_BG)

MSTTCH_BG = (DAY_EXPOSURE_BG*WEEK_EXPOSURE_BG*MONTH_EXPOSURE_BG)*MSTTBCKGR
MSTTFR_BG = MSTTBCKGR/CINT

CYCLE_BG =DAY_EXPOSURE_BG*WEEK_EXPOSURE_BG*MONTH_EXPOSURE_BG
! CONDITIONAL ORAL EXPOSURE (BACKGROUND EXPOSURE)

IF (MSTTCH_BG.EQ.MSTTBCKGR) THEN
ABSMSTT_GB= MSTTFR_BG

ELSE

ABSMSTT_GB =0.0
END IF

CYCLETOTBG=INTEG(CYCLE_BG,0.0)

!MULTIROUTE EXPOSURE
!REPETITIVE EXPOSURE SCENARIO

MSTT= MSTOT_NM * WTO	!AMOUNT IN NMOL

DAY_EXPOSURE = PULSE(DAY_LACK,DAY_PERIOD,DAY_FINISH)
WEEK_EXPOSURE = PULSE(WEEK_LACK,WEEK_PERIOD,WEEK_FINISH)
MONTH_EXPOSURE = PULSE(MONTH_LACK,MONTH_PERIOD,MONTH_FINISH)

MSTTCH = (DAY_EXPOSURE*WEEK_EXPOSURE*MONTH_EXPOSURE)*MSTT

MSTTFR = MSTT/CINT

This document is a draft for review purposes only and does not constitute Agency policy.

C-26 DRAFT—DO NOT CITE OR QUOTE


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CYCLE = DAY_EXPOSURE*WEEK_EXPOSURE*MONTH_EXPOSURE

SUMEXPEVENT= INTEG (CYCLE,0.0) !NUMBER OF CYCLES GENERATED DURING SIMULATION

! CONDITIONAL ORAL EXPOSURE
IF (MSTTCH.EQ.MSTT) THEN

ABSMSTT= MSTTFR
ELSE

ABSMSTT =0.0
END IF

CYCLETOT=INTEG(CYCLE, 0.0)

! MASS CHANGE IN THE LUMEN

RMSTT= -(KST+KABS)*MST +ABSMSTT +ABSMSTT_GB ! RATE OF CHANGE (NMOL/H)

MST = INTEG(RMSTT,0.0)	!AMOUNT REMAINING IN DUODENUM

(NMOL)

! ABSORPTION IN LYMPH CIRCULATION
LYRMLUM = KABS*MST*A
LYMLUM = INTEG(LYRMLUM,0.0)

! ABSORPTION IN PORTAL CIRCULATION
LIRMLUM = KABS*MST*B
LIMLUM = INTEG(LIRMLUM,0.0)

!IV ABSORPTION SCENARIO	

IV= DOSEIV_NM * WTO !AMOUNT IN NMOL
IVR= IV/PFUNC ! RATE FOR IV INFUSION IN BLOOD
EXPIV= IVR * (1-STEP(PFUNC))

IVDOSE = integ(EXPIV,0.0)

!IV LATE IN THE CYCLE
!MODIFICATION JANUARY 13 2004
IV_RlateR = DOSEIVNMlate*WT0

IV_EXPOSURE=PULSE(IV_LACK,IV_PERIOD,IV_FINISH)

IV_lateT = IV_EXPOSURE *IV_RlateR
IV_late = IV_lateT/CINT

SUMEXPEVENTIV= integ(IV_EXPOSURE,0.0) !NUMBER OF CYCLE GENERATE DURING
SIMULATION

!SYSTEMIC BLOOD COMPARTMENT
! MODIFICATION OCT 8 2009
CB=(QF*CFB+QRE*CREB+QLI*CLIB+EXPIV+LYRMLUM+QPLA*CPLAB+IV_late)/(QC+CLURI) !
CA = CB	! CONCENTRATION (NMOL/L)

!CB=(QF*CFB+QRE*CREB+QLI*CLIB+EXPIV+LYRMLUM+QPLA*CPLAB+IV_late-RAURI)/QC
!(NMOL/L)

!URINARY EXCRETION BY KIDNEY
! MODIFICATION OCT 8 2009
RAURI = CLURI *CB

This document is a draft for review purposes only and does not constitute Agency policy.

C-27 DRAFT—DO NOT CITE OR QUOTE


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AURI = INTEG(RAURI,0.0)

!RAURI = CLURI * CRE
!AURI = INTEG(RAURI,0.0)

!UNIT CONVERSION POST SIMULATION
CONSTANT MW=322 IMOLECULAR WEIGHT (NG/NMOL)

CONSTANT SERBLO =0.55
CONSTANT UNITCORR = 1.0e3

CBSNGKGLIADJ = CB*MW/(0.55*B_TOTLIP) !NG SERUM LIPID ADJUSTED/KG
AUCBS_NGKGLIADJ=integ(CBSNGKGLIADJ,0.)

CBNGKG= CB*MW !NG/KG

PRCT_B = 100.0*CB/(MSTT+1E-30)	!PERCENT OF ORAL DOSE IN BLOOD

PRCT_BIV = 100.0*CB/(IV_RlateR+lE-30) ! PERCENT OF IV DOSE IN BLOOD

!ADIPOSE COMPARMTENT
!TISSUE BLOOD SUBCOMPARTMENT
RAFB= QF*(CA-CFB)-PAF*(CFB-CF/PF)

AFB = INTEG(RAFB,0.0)

CFB = AFB/WFB

!TISSUE SUBCOMPARTMENT
RAF = PAF*(CFB-CF/PF)

AF = INTEG(RAF,0.0)

CF = AF/WF

!UNIT CONVERSION POST SIMULATION
CFTOTAL= (AF + AFB)/(WF + WFB) ! TOTAL CONCENTRATION IN NMOL/ML
PRCT_F = 100.0*CFTOTAL/(MSTT+1E-30) !PERCENT OF ORAL DOSE IN FAT
PRCT_FIV = 100.0*CFTOTAL/(IV_RlateR+lE-30) !PERCENT OF IV DOSE IN FAT
CFNGKG=CFTOTAL*MW ! FAT CONCENTRATION IN NG/KG
AUCF_NGKGH=integ(CFNGKG,0.)

!(NMOL/H)

!(NMOL)
!(NMOL/L)

!(NMOL/H)
!(NMOL)
!(NMOL/L)

!REST OF THE BODY COMPARTMENT
!TISSUE BLOOD SUBCOMPARTMENT
RAREB= QRE *(CA-CREB)-PARE*(CREB-CRE/PRE)
AREB = INTEG(RAREB,0.0)

CREB = AREB/WREB

!TISSUE SUBCOMPARTMENT
RARE = PARE*(CREB - CRE/PRE)
ARE = INTEG(RARE,0.0)

CRE = ARE/WRE
ARETOT = ARE +AREB

!(NMOL/H)
!(NMOL)

(NMOL/L)

!(NMOL/H)
!(NMOL)

(NMOL/L)

!POST SIMULATION UNIT CONVERSION
CRETOTAL= (ARE + AREB)/(WRE + WREB)	! TOTAL CONCENTRATION (NMOL/L)

PRCT_RE = 100.0*CRETOTAL/(MSTT+1E-30) ! PERCENT OF ORAL DOSE IN REST OF BODY
PRCT_REIV = 100.0*CRETOTAL/(IV_RlateR+lE-30) ![ PERCENT OF IV DOSE IN REST
OF BODY

CRENGKG=CRETOTAL*MW	! REST OF THE BODY

CONCENTRATION (NG/KG)

!LIVER COMPARTMENT
!TISSUE BLOOD SUBCOMPARTMENT

This document is a draft for review purposes only and does not constitute Agency policy.

C-28 DRAFT—DO NOT CITE OR QUOTE


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RALIB = QLI*(CA-CLIB)-PALI*(CLIB-CFLLIR)+LIRMLUM ! (NMOL/HR)

ALIB = INTEG(RALIB,0.0)	!(NMOL)

CLIB = ALIB/WLIB	!(NMOL/L)

!TISSUE SUBCOMPARMTENT

RALI = PALI*(CLIB - CFLLIR)-REXCLI	! (NMOL/HR)

ALI = INTEG(RALI,0.0)	!(NMOL)

CLI = ALI/WLI	!(NMOL/L)

!FREE TCDD CONCENTRATION IN LIVER
! MODIFICATION OCTOBER 8 2009
CFLLI= IMPLC(CLI-(CFLLIR*PLI+(LIBMAX*CFLLIR/(KDLI+CFLLIR)) &

+((CYP1A2_103*CFLLIR/(KDLI2+CFLLIR)*PAS_INDUC)))-CFLLI,CFLLI0)
CFLLIR=DIM(CFLLI,0.0) ! FREE TCDD CONCENTRATION IN LIVER
!MODIFIED FROM:

!PARAMETER (LIVER_1RMN = 1.0E-30)

! CFLLI= IMPLC(CLI-(CFLLIR*PLI+(LIBMAX*CFLLIR/(KDLI+CFLLIR &
!+LIVER_1RMN))+((CYP1A2_103*CFLLIR/(KDLI2 + CFLLIR &
!+LIVER_1RMN)*PAS_INDUC)))-CFLLI,CFLLI0)

!CFLLIR=DIM(CFLLI,0.0)

! MODIFICATION OCTOBER 8 2009

CBNDLI= LIBMAX*CFLLIR/(KDLI+CFLLIR) !BOUND CONCENTRATION (NMOL/L)

!POST SIMULATION UNIT CONVERSION
CLITOTAL= (ALI + ALIB)/(WLI + WLIB) ! TOTAL CONCENTRATION (NMOL/L)

PRCT_LI = 100.0*CLITOTAL/(MSTT+1E-30) ! PERCENT OF ORAL DOSE IN LIVER
PRCT_LIIV = 100.0*CLITOTAL/(IV_RlateR+lE-30) ! PERCENT OF IV DOSE IN LIVER
Rec_occ= CFLLIR/(KDLI+CFLLIR)

CLINGKG=CLITOTAL*MW ! LIVER CONCENTRATION IN NG/KG

AUCLI_NGKGH=integ(CLINGKG, 0.0)

CBNDLINGKG = CBNDLI*MW ! BOUND CONCENTRATION IN NG/KG
AUCBNDLI_NGKGH =INTEG(CBNDLINGKG,0.0)

!FRACTION INCREASE OF INDUCTION OF CYP1A2
fold_ind=CYPlA2_10UT/CYPlA2_lA2

VARIATIONOFAC =(CYP1A2_10UT-CYP1A2_1A2)/CYP1A2_1A2

!VARIABLE ELIMINATION BASED ON THE CYP1A2
! MODIFICATION OCTOBER 8 2009

KBILE_LI_T = Kelv*VARIATIONOFAC! ! DOSE-DEPENDENT EXCRETION RATE CONSTANT

REXCLI = KBILE_LI_T*CFLLIR*WLI ! DOSE-DEPENDENT BILLIARY EXCRETION RATE
EXCLI = INTEG(REXCLI,0.0)

!KBILE LI T =((CYP1A2 10UT-CYP1A2 1A2)/CYP1A2 lA2)*Kelv !

!CHEMICAL IN CYP450 (1A2) COMPARTMENT

CYP1A2_1KINP = CYP1A2_1K0UT* CYP1A2_10UTZ ! BASAL PRODCUTION RATE OF CYP1A2
SET EQUAL TO BASAL DEGREDATION RATE

! MODIFICATION OCTOBER 8 2009
CYP1A2_10UT =INTEG(CYP1A2_1KINP * (1.0 + CYP1A2_1EMAX *(CBNDLI+1.0e-30)**HILL
&

/(CYP1A2_1EC50**HILL + (CBNDLI+1.Oe-30)**HILL)) &

This document is a draft for review purposes only and does not constitute Agency policy.

C-29 DRAFT—DO NOT CITE OR QUOTE


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- CYP1A2_1K0UT*CYP1A2_10UT, CYP1A2_10UTZ)

!MODIFIED FROM:

!PARAMETER (CYP1A2_1RMN = 1E-30)

!CYP1A2_10UT =INTEG(CYP1A2_1KINP * (1 + CYP1A2_1EMAX *(CBND&
!LI +CYP1A2_1RMN)**HILL/(CYP1A2_1EC50 + (CBNDLI + CYP1A2_1&
!RMN)**HILL) +CYP1A2_1RMN) - CYP1A2_1K0UT*CYP1A2_1&
!OUT, CYP1A2_10UTZ)

! EQUATIONS INCORPORATING DELAY OF CYP1A2 PRODUCTION (NOT USED IN
SIMULATIONS)

CYP1A2_1R02 = (CYP1A2_10UT - CYP1A2_102)/ CYP1A2_1TAU
CYP1A2_102 =INTEG(CYP1A2_1R02, CYP1A2_1A1)

CYP1A2_1R03 = (CYP1A2_102 - CYP1A2_103)/ CYP1A2_1TAU
CYP1A2_103 =INTEG(CYP1A2_1R03, CYP1A2_1A2)

!PLACENTA COMPARTMENT
!TISSUE BLOOD SUBCOMPARTMENT
RAPLAB= QPLA*(CA - CPLAB)-PAPLA*(CPLAB -CFLPLAR)

APLAB = INTEG(RAPLAB,0.0)

CPLAB = APLAB/(WPLAB+1E-30)

!TISSUE SUBCOMPARTMENT
RAPLA = PAPLA*(CPLAB-CFLPLAR)-RAMPF + RAFPM
APLA = INTEG(RAPLA,0.0)

CPLA = APLA/(WPLA+le-30)

! NEW EQUATION AUGUST 2 8 2 009
PARAMETER (PARA_ZERO = 1.0E-30)

CFLPLA= IMPLC(CPLA-(CFLPLAR*PPLA +(PLABMAX*CFLPLAR/(KDPLA&

+CFLPLAR+PARA_ZERO)))-CFLPLA,CFLPLA0)

CFLPLAR=DIM(CFLPLA,0.0)

!POST SIMULATION UNIT CONVERSION
CPLATOTAL = ((APLAB+APLA)/(WPLAB+WPLA))

PRCT_PLA = (CPLATOTAL/(MSTT+1E-30))*100
PRCT_PLAIV = (CPLATOTAL/(IV_RlateR+lE-30))*100

!FETUS COMPARTMENT
RAFETUS= RAMPF-RAFPM

AFETUS=INTEG(RAFETUS,0.0)

CFETUS=AFETUS/(WTFE+1.0e-30)

CFETOTAL= CFETUS
CFETUS_v = CFETUS/PFETUS

!POST SIMULATION UNIT CONVERSION
CFETUSNGKG = CFETUS*MW	!(NG/KG)

PRCT_FE = 100.0*CFETOTAL/(MSTT+1E-30)

PRCT_FEIV = 100.0*CFETOTAL/(IV_RlateR+lE-30)

!TRANSFER OF DIOXIN FROM PLACENTA TO FETUS
!FETAL EXPOSURE ONLY DURING EXPOSURE

IF (T.LT.TRANSTIME_ON) THEN

SWITCH_trans =0.0
ELSE

SWITCH trans = 1

! NMOL/HR)

! (NMOL)
! (NMOL/ML)

! (NMOL/HR)

! (NMOL)
! (NMOL/ML)

This document is a draft for review purposes only and does not constitute Agency policy.

C-30 DRAFT—DO NOT CITE OR QUOTE


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END IF

!TRANSFER OF DIOXIN FROM PLACENTA TO FETUS
! MODIFICATION 26 SEPTEMBER 2003

RAMPF = (CLPLA_FET*CPLA)*SWITCH_trans
AMPF=INTEG(RAMPF,0.0)

!TRANSFER OF DIOXIN FROM FETUS TO PLACENTA
RAFPM = (CLPLA_FET*CFETUS_v)*SWITCH_trans!

AFPM = INTEG(RAFPM,0.0)

!CHECK MASS BALANCE 	

BDOSE= IVDOSE +LYMLUM+LIMLUM

BMASSE = EXCLI+AURI+AFB+AF+AREB+ARE+ALIB+ALI+APLA+APLAB+AFETUS !
BDIFF = BDOSE-BMASSE

!BODY BURDEN (NMOL)

BODY_BURDEN = AFB +AF+ARE B +ARE +ALIB+ALI+AP LA+AP LAB

!BODY BURDEN CONCENTRATION (NG/KG)

BBNGKG =(AFB+AF+AREB+ARE+ALIB+ALI+AP LA+AP LAB)*MW/WT0

! END SIMULATION COMMAND

TERMT (T.GE. TimeLimit, 'Time limit has been reached.')

END ! END OF THE DERIVATIVE SECTION
END ! END OF THE DYNAMIC SECTION
END ! END OF THE PROGRAM

C.2.2.2. Input File

output 0clear
prepare 0clear T

year CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG CBNGKG

CINT = 1 %168 %100
%EXPOSURE SCENARIO

EXP_TIME_ON
EX P_T I ME_0 F F
DAY_CYCLE
B C K_TIME_ON
(HOUR)

BCK_TIME_OFF
IV_LACK
IV PERIOD

0

401190
24

401190

401190
401190
401190

%GESTATION CONTROL
MATTING	= 393120

TIMELIMIT	= 399840

TRANSTIME_ON	= 394632

GESTATION

%EXPOSURE DOSE
MSTOT	= 9.9733

MSTOTBCKGR	=0. %

DOSEIV	=0. %

%INTEGRATION TIME

% TIME AT WHICH EXPOSURE BEGINS (HOUR)

%TIME AT WHICH EXPOSURE ENDS (HOUR)

^NUMBER OF HOURS BETWEEN DOSES (HOUR)

%TIME AT WHICH BACKGROUND EXPOSURE BEGINS

%TIME AT WHICH BACKGROUND EXPOSURE ENDS (HOUR)

5 BEGINNING OF MATING (HOUR) AT 4 5 YEARS OLD
i;SIMULATION TIME LIMIT (HOUR)

5 TRANSFER FROM MOTHER TO FETUS AT 1512 HOURS

9283634997E-07	% NG OF TCDD PER KG OF BW

0.1	% ORAL BACKGROUND EXPOSURE DOSE (NG/KG)

10

This document is a draft for review purposes only and does not constitute Agency policy.

C-31 DRAFT—DO NOT CITE OR QUOTE


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DOSEIVLATE

= 0. %10

% TRANFER MOTHER TO FETUS CLEARANCE
CLPLA_FET	= 0.001 % MOTHER TO FETUS TRANFER CLEARANCE (L/HR)

C.2.3. Rat Standard Model
C.2.3.1. Model Code

PROGRAM: 'Three Compartment PBPK Model in Rat: Standard Model (Non-Gestation)'

!Rat Dioxin 3C June09 2clean icf afterKKfix v3 ratnongest.csl
!RAT~NON_GEST_ICF_F0 8 310 9.CSL ~	~ ~

!RAT_NON_GEST_ICF_F10 0 60 9.CSL

INITIAL ! INITIALIZATION OF PARAMETERS

!SIMULATION PARAMETERS
CONSTANT PARA_ZERO	=	Id-3 0

CONSTANT EXP_TIME_ON	=	0.0

(HOURS)

CONSTANT EXP_TIME_0FF =	900.0

(HOURS)

CONSTANT DAY_CYCLE	=	9 0 0.0

DOSES (HOURS)

CONSTANT BCK_TIME_ON	=	0.0

EXPOSURE BEGINS (HOURS)

CONSTANT BCK_TIME_OFF =	0.0

EXPOSURE ENDS (HOURS)

! TIME AT WHICH EXPOSURE BEGINS
! TIME AT WHICH EXPOSURE ENDS
! NUMBER OF HOURS BETWEEN
! TIME AT WHICH BACKGROUND
! TIME AT WHICH BACKGROUND

CONSTANT MW=322 IMOLECULAR WEIGHT (NG/NMOL)
CONSTANT SERBLO =0.55
CONSTANT UNITCORR = 1000

! EXPOSURE DOSES
CONSTANT MSTOTBCKGR
(UG/KG)

CONSTANT MSTOT
CONSTANT MSTOTsc
(UG/KG)

CONSTANT DOSEIV

0.0	!ORAL BACKGROUND EXPOSURE DOSE

10	!ORAL EXPOSURE DOSE (UG/KG)

0.0	!SUBCUTANEOUS EXPOSURE DOSE

0.0	! INJECTED DOSE (UG/KG)

!ORAL DOSE
MSTOT_NM
MSTOT NMBCKGR

MSTOT/MW

!AMOUNT IN NMOL/G

MSTOTBCKGR/MW !AMOUNT IN NMOL/G

!INTRAVENOUS DOSE
DOSEIV NM

DOSEIV/MW

!AMOUNT IN NMOL/G

!INITIAL GUESS OF THE FREE CONCENTRATION IN THE LIGAND (COMPARTMENT
INDICATED BELOW)====

CONSTANT CFLLI0	=	0.0	!LIVER (NMOL/ML)

This document is a draft for review purposes only and does not constitute Agency policy.

C-32 DRAFT—DO NOT CITE OR QUOTE


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!BINDING CAPACITY (AhR) FOR NON LINEAR BINDING (COMPARTMENT INDICATED
BELOW) (NMOL/ML) ===

CONSTANT LIBMAX	= 3.5e-4	! LIVER (NMOL/ML), WANG ET AL.

1997

! PROTEIN AFFINITY CONSTANTS (1A2
(NMOL/ML)===

CONSTANT KDLI	= 1.0e-4

ET AL. 1997

CONSTANT KDLI2	= 4.Oe-2

ET AL. 2004

OR AhR, COMPARTMENT INDICATED BELOW)
! LIVER (AhR) (NMOL/ML), WANG
!LIVER (1A2) (NMOL/ML), EMOND

!EXCRETION AND ABSORPTION CONSTANT [RAT]

CONSTANT KST	= 0.36	! GASTRIC RATE CONSTANT (HR-1),

WANG ET AL. (1997)

CONSTANT KABS	= 0.4 8	!INTESTINAL ABSORPTION CONSTANT

(HR-1), WANG ET AL. 1997

!URINARY ELIMINATION CLEARANCE (ML/HR)

CONSTANT CLURI	=	0.01	!URINARY CLEARANCE (ML/HR),

EMOND ET AL. 2004

!INTERSPECIES VARIABLE ELIMINATION
CONSTANT KELV	=	0.15	! INTERSPECIES VARIABLE

ELIMINATION CONSTANT (1/HOUR) (OPTIMIZED), EMOND ET AL. 2004

! CONSTANT TO DIVIDE THE ABSORPTION INTO LYMPHATIC AND PORTAL FRACTIONS

CONSTANT A	=0.7

AL. 1997

!PARTITION COEFFICIENTS
CONSTANT PF	=	100

AL. 1997

CONSTANT PRE	=	1.5

ET AL. 1997

CONSTANT PLI	=	6.0

1997

! LYMPHATIC FRACTION, WANG ET

! ADIPOSE TISSUE/BLOOD, WANG ET
! REST OF THE BODY/BLOOD, WANG
! LIVER/BLOOD, WANG ET AL.

!PARAMETER FOR INDUCTION OF CYP 1A2 [MOUSE] ===
CONSTANT PAS_INDUC	=	1.0

0 = NO)

CONSTANT CYP1A2_10UTZ =	1.6

CONSTANT OF 1A2 (NMOL/ML), WANG ET AL. 1997

CONSTANT CYP1A2_1A1	=	1.6

(NMOL/ML), WANG ET AL. 1997

CONSTANT CYP1A2_1EC5 0 =	0.13

CYP1A2 (NMOL/ML) , WANG ET AL.	19 97

CONSTANT CYP1A2_1A2	=	1.6

(NMOL/ML) Wang et al (1997)

CONSTANT CYP1A2_1K0UT =	0.1

DEGRADATION (H-l), WANG ET AL.	1997

CONSTANT CYP1A2_1TAU
1997

CONSTANT CYP1A2 1EMAX

0.25

600

!	INCLUDE INDUCTION? (1 = YES,

!	DEGRADATION CONCENTRATION

!	BASAL CONCENTRATION OF 1A1

!	DISSOCIATION CONSTANT TCDD-

!	BASAL CONCENTRATION OF 1A2

!	FIRST ORDER RATE OF

!	HOLDING TIME (H), WANG ET AL.

!	MAXIMUM INDUCTION OVER BASAL

EFFECT (UNITLESS), WANG ET AL. 1997

This document is a draft for review purposes only and does not constitute Agency policy.

C-33 DRAFT—DO NOT CITE OR QUOTE


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CONSTANT HILL	=	0.6	!HILL CONSTANT; COOPERATIVELY LIGAND

BINDING EFFECT CONSTANT (UNITLESS)

!TISSUE BLOOD FLOW EXPRESSED AS A FRACTION OF CARDIAC OUTPUT
CONSTANT QFF = 0.069	! ADIPOSE TISSUE BLOOD FLOW

FRACTION (UNITLESS), WANG ET AL. 1997

CONSTANT QLIF = 0.183	! LIVER (UNITLESS), WANG ET AL.

1997

!DIFFUSIONAL PERMEABILITY FRACTION
CONSTANT PAFF	= 0.0910	! ADIPOSE (UNITLESS), WANG ET

AL. 1997

CONSTANT PAREF	= 0.0298	! REST OF THE BODY (UNITLESS),

WANG ET AL. 1997

CONSTANT PALIF	= 0.35	! LIVER (UNITLESS), WANG ET AL.

1997

!FRACTION OF TISSUE VOLUME (UNITLESS)

CONSTANT WLI0	= 0.0360	! LIVER, WANG ET AL. 1997

CONSTANT WF0	= 0.069	! BLOOD, WANG ET AL. 1997

!COMPARTMENT TISSUE BLOOD EXPRESSED AS A FRACTION OF THE TOTAL
COMPARTMENT VOLUME =========

CONSTANT WFB0	= 0.050	! ADIPOSE TISSUE, WANG ET

1997

CONSTANT WREB0	= 0.030	! REST OF THE BODY, WANG

1997

CONSTANT WLIB0	= 0.266	! LIVER , WANG ET AL. 199

!EXPOSURE SCENARIO FOR UNIQUE OR
! NUMBER OF EXPOSURES PER WEEK
CONSTANT WEEK_LACK	=0.0

(WEEK)

CONSTANT WEEK_PERIOD	= 168.0

(HOURS)

CONSTANT WEEK FINISH	= 168.0

AL.
ET AL.
7

REPETITIVE WEEKLY OR MONTHLY EXPOSURE
! DELAY BEFORE EXPOSURE ENDS
! NUMBER OF HOURS IN THE WEEK
! TIME EXPOSURE ENDS (HOURS)

!NUMBER OF EXPOSURES PER MONTH
CONSTANT MONTH_LACK	=0.0	! DELAY BEFORE EXPOSURE BEGINS

(MONTH)

!SET FOR BACKGROUND EXPOSURE=====:
!CONSTANT FOR BACKGROUND EXPOSURE^
CONSTANT Day_LACK_BG	=0.0

(HOURS)

CONSTANT Day_PERIOD_BG =24.0

!NUMBER OF EXPOSURES PER WEEK
CONSTANT WEEK_LACK_BG =0.0
EXPOSURE (WEEK)

CONSTANT WEEK_PERIOD_BG = 168.0
(HOURS)

CONSTANT WEEK FINISH BG = 168.0

! DELAY BEFORE EXPOSURE BEGINS
! LENGTH OF EXPOSURE (HOURS)

! DELAY BEFORE BACKGROUND

!NUMBER OF HOURS IN THE WEEK
! TIME EXPOSURE ENDS (HOURS)

!GROWTH CONSTANT FOR RAT

'CONSTANT FOR MOTHER BODY WEIGHT GROWTH

This document is a draft for review purposes only and does not constitute Agency policy.

C-34 DRAFT—DO NOT CITE OR QUOTE


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CONSTANT BW TO

= 250.0

!CHANGED FOR SIMULATION

! CONSTANT USED IN CARDIAC OUTPUT EQUATION

CONSTANT QCCAR =311.4
AL.

!CONSTANT (ML/MIN/KG), WANG ET

! COMPARTMENT LIPID EXPRESSED AS THE FRACTION OF TOTAL LIPID

CONSTANT F_TOTLIP
CONSTANT B_TOTLIP
CONSTANT RE_TOTLIP
CONSTANT LI TOTLIP

= 0.855
= 0.0033
= 0.019
= 0. 06

END	!END OF THE INITIAL SECTION

DYNAMIC !DYNAMIC SIMULATION SECTION

!ADIPOSE TISSUE (UNITLESS)
!BLOOD (UNITLESS)

!REST OF THE BODY (UNITLESS)
!LIVER (UNITLESS)

ALGORITHM
CINTERVAL
MAXTERVAL
MINTERVAL
VARIABLE
CONSTANT
(HOURS)

CINTXY = CINT
PFUNC = CINT

IALG
CINT
MAXT
MINT
T

TIMELIMIT

2
0.1
1.0e+10
1.0E-10
0.0
900. 0

GEAR METHOD

COMMUNICATION INTERVAL
MAXIMUM CALCULATION INTERVAL
MINIMUM CALCULATION INTERVAL

!SIMULATION TIME LIMIT

!TIME CONVERSION
DAY=T/24.0
WEEK =T/168.0
MONTH =T/730 . 0
YEAR=T/8 7 60.0

TIME IN DAYS
TIME IN WEEKS
TIME IN MONTHS
TIME IN YEARS

DERIVATIVE ! PORTION OF CODE THAT SOLVES DIFFERENTIAL EQUATIONS

!CHRONIC OR SUBCHRONIC EXPOSURE SCENARIO

!NUMBER OF EXPOSURES PER DAY
DAY_LACK	= EXP_TIME_ON

(HOURS)

DAY_PERIOD = DAY_CYCLE
DAY_FINISH = CINTXY
MONTH_PERIOD = TIMELIMIT
MONTH FINISH = EXP TIME OFF

! DELAY BEFORE EXPOSURE BEGINS

EXPOSURE PERIOD (HOURS)
LENGTH OF EXPOSURE (HOURS)
EXPOSURE PERIOD (MONTHS)
LENGTH OF EXPOSURE (MONTHS)

!NUMBER OF EXPOSURES PER DAY AND MONTH

DAY_FINISH_BG = CINTXY
MONTH_LACK_BG = B C K_TIME_ON
EXPOSURE BEGINS (MONTHS)
MONTH_PERIOD_BG = TIMELIMIT
(MONTHS)

MONTH_FINISH_BG = BCK_TIME_OFF
(MONTHS)

!	LENGTH OF EXPOSURE (HOURS)

!	DELAY BEFORE BACKGROUND

!	BACKGROUND EXPOSURE PERIOD

!	LENGTH OF BACKGROUND EXPOSURE

B = 1-A	! FRACTION OF DIOXIN ABSORBED IN

THE PORTAL FRACTION OF THE LIVER

This document is a draft for review purposes only and does not constitute Agency policy.

C-3 5 DRAFT—DO NOT CITE OR QUOTE


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! BODY WEIGHT GROWTH EQUATION========

PARAMETER (BW_RMN = 1.0E-30)

WT0= (BW TO *(1.0+(0.41*T)/(1402.5+T+BW RMN)))

!VARIABILITY OF REST OF THE BODY DEPEND OTHERS ORGAN
WRE0 = (0.91 - (WLIB0*WLI0 + WFB0*WF0 + WLI0 + WF0))/(1.0+WREB0) !REST OF
THE BODY FRACTION; UPDATED FOR EPA ASSESSMENT
QREF = 1.0-(QFF+QLIF)	!REST OF BODY BLOOD FLOW

QTTQF = QFF+QREF+QLIF	! SUM MUST EQUAL 1

!COMPARTMENT VOLUME (G)
WF = WF0 * WTO
WRE = WRE0 * WTO
WLI = WLI0 * WTO

ADIPOSE

REST OF THE BODY
LIVER

!COMPARTMENT TISSUE BLOOD VOLUME
WFB = WFB0 * WF
WREB = WREB0 * WRE
WLIB = WLIB0 * WLI

(G)

ADIPOSE

REST OF THE BODY
LIVER

!CARDIAC OUTPUT FOR THE GIVEN BODY WEIGHT
QC= QCCAR* 60.0*(WTO/UNITCORR)**0.75

! COMPARTMENT BLOOD FLOW (ML/HR)
QF = QFF*QC
QLI = QLIF*QC
QRE = QREF*QC

RATE
QTTQ

= QF+QRE+QLI

ADIPOSE TISSUE BLOOD FLOW RATE
LIVER TISSUE BLOOD FLOW RATE
REST OF THE BODY BLOOD FLOW

! TOTAL FLOW RATE

!PERMEABILITY ORGAN FLOW (ML/HR)
PAF = PAFF*QF
PARE = PAREF*QRE
PALI = PALIF*QLI

ADIPOSE

REST OF THE BODY
LIVER TISSUE

!CONDITIONAL ORAL EXPOSURE (BACKGROUND EXPOSURE)

!EXPOSURE + !REPETITIVE EXPOSURE SCENARIO
IV= DOSEIV_NM * WTO !AMOUNT IN NMOL
MSTT= MSTOT_NM * WTO !AMOUNT IN NMOL
MSTTBCKGR =MSTOT_NMBCKGR *WT0

!REPETITIVE ORAL BACKGROUND EXPOSURE SCENARIOS
DAY_EX P O S U RE_B G = PULSE(DAY_LACK_BG,DAY_PERIOD_BG,DAY_FINISH_BG)
WEEK_EXPOSURE_BG = PULSE(WEEK_LACK_BG,WEEK_PERIOD_BG,WEEK_FINISH_BG)
MONTH_EXPOSURE_BG = PULSE(MONTH_LACK_BG,MONTH_PERIOD_BG,MONTH_FINISH_BG)

MSTTCH_BG = (DAY_EXPOSURE_BG*WEEK_EXPOSURE_BG*MONTH_EXPOSURE_BG)*MSTTBCKGR
MSTTFR_BG = MSTTBCKGR/CINT

CYCLE BG =DAY EXPOSURE BG*WEEK EXPOSURE BG*MONTH EXPOSURE BG

IF (MSTTCH_BG.EQ.MSTTBCKGR) THEN
ABSMSTT_GB= MSTTFR_BG

ELSE

ABSMSTT GB = 0.0

This document is a draft for review purposes only and does not constitute Agency policy.

C-36 DRAFT—DO NOT CITE OR QUOTE


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END IF

!REPETITIVE ORAL MAIN EXPOSURE SCENARIO
DAY_EXPOSURE = PULSE(DAY_LACK,DAY_PERIOD,DAY_FINISH)

WEEK_EXPOSURE = PULSE(WEEK_LACK,WEEK_PERIOD,WEEK_FINISH)

MONTH_EXPOSURE = PULSE(MONTH_LACK,MONTH_PERIOD,MONTH_FINISH)

MSTTCH = (DAY_EXPOSURE*WEEK_EXPOSURE*MONTH_EXPOSURE)*MSTT
CYCLE = DAY_EXPOSURE*WEEK_EXPOSURE*MONTH_EXPOSURE
MSTTFR = MSTT/CINT

SUMEXPEVENT= integ (CYCLE,0.0) INUMBER OF CYCLE GENERATE DURING SIMULATION

!CONDITIONAL ORAL EXPOSURE
IF (MSTTCH.EQ.MSTT) THEN

ABSMSTT= MSTTFR
ELSE

ABSMSTT =0.0
END IF

CYCLETOT=INTEG(CYCLE, 0.0)

!MASS CHANGE IN THE LUMEN
RMSTT = -(KST+KABS)*MST+ABSMSTT +ABSMSTT_GB ! RATE OF CHANGE (NMOL/H)
MST = INTEG(RMSTT,0.0) !AMOUNT OF STAY IN DUODENUM (NMOL)

!ABSORPTION IN LYMPH CIRCULATION
LYRMLUM = KABS*MST*A

LYMLUM = INTEG(LYRMLUM,0.0)

!ABSORPTION IN PORTAL CIRCULATION
LIRMLUM = KABS*MST*B

LIMLUM = INTEG(LIRMLUM,0.0)

!PERCENT OF DOSE REMAINING IN THE GI TRACT
PRCT_remain_GIT = (MST/(MSTT+PARA_ZERO))*100.0

!ABSORPTION of Dioxin by IV route	

IVR= IV/PFUNC ! RATE FOR IV INFUSION IN BLOOD
EXPIV= IVR * (1.0-STEP(PFUNC))

IVDOSE = integ(EXPIV,0.0)

!SYSTEMIC BLOOD COMPARTMENT
! MODIFICATION ON OCTOBER 6, 2009
CB=(QF*CFB+QRE*CREB+QLI*CLIB+EXPIV+LYRMLUM)/(QC+CLURI) !

CA = CB

!URINARY EXCRETION BY KIDNEY
! MODIFICATION ON OCTOBER 6, 2009
RAURI = CLURI *CB

AURI = INTEG(RAURI,0.0)

!CONVERSION EQUATION POST SIMULATION
PRCT_B = (CB/(MSTT+PARA_ZERO))*100.0

This document is a draft for review purposes only and does not constitute Agency policy.

C-37 DRAFT—DO NOT CITE OR QUOTE


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CBNGKG = CB*MW*UNITCORR ![NG/KG]

CBSNGKGLIADJ= (CB*MW*UNITCORR*(1.0/B_TOTLIP)*(1.0/SERBLO))![NG of TCDD
Serum/Kg OF LIPIP]

!ADIPOSE TISSUE COMPARTMENT
! TISSUE BLOOD SUBCOMPARTMENT

RAFB = QF*(CA-CFB)-PAF*(CFB-CF/PF)	!(NMOL/HR)

AFB = INTEG(RAFB,0.0)	!(NMOL)

CFB = AFB/WFB	!(NMOL/ML)
!TISSUE SUBCOMPARTMENT

RAF = PAF*(CFB-CF/PF)	!(NMOL/HR)

AF = INTEG(RAF,0.0)	!(NMOL)

CF = AF/WF	!(NMOL/ML)

!CONVERSION EQUATION POST SIMULATION
CFTOTAL = (AF + AFB)/(WF + WFB)	!TOTAL CONCENTRATION IN NMOL/ML

PRCT_F = (CFTOTAL/(MSTT+PARA_ZERO))*100.0 ! PRCENT OF DOSE IN FAT
CFNGKG = CFTOTAL*MW*UNITCORR	! CONCENTRATION [NG/KG]

!REST OF THE BODY COMPARTMENT
! TISSUE BLOOD SUBCOMPARTMENT

RAREB= QRE*(CA-CREB)-PARE*(CREB-CRE/PRE)	!(NMOL/HR)

AREB = INTEG(RAREB,0.0)	!(NMOL)

CREB = AREB/WREB	!(NMOL/ML)
! TISSUE COMPARTMENT

RARE = PARE*(CREB - CRE/PRE)	!(NMOL/HR)

ARE = INTEG(RARE,0.0)	!(NMOL)
CRE = ARE/WRE !(NMOL/ML)

!CONVERSION EQUATION POST SIMULATION

CRETOTAL= (ARE + AREB)/(WRE + WREB)	! TOTAL CONCENTRATION IN

NMOL/ML

PRCT_RE = (CRETOTAL/(MSTT+PARA_ZERO))*100.0
CTREPGG= CRETOTAL*MW*UNITCORR !(PG/ML)

AUC_REPPG = integ(CTREPGG,0.0)

!LIVER COMPARTMENT
! TISSUE BLOOD COMPARTMENT
RALIB = QLI*(CA-CLIB)-PALI*(CLIB-CFLLIR)+LIRMLUM
ALIB = INTeg(RALIB,0.0)

CLIB = ALIB/WLIB
! TISSUE COMPARTMENT
RALI = PALI*(CLIB-CFLLIR)-REXCLI
ALI = integ(RALI,0.0)

CLI = ALI/WLI

!(NMOL/HR)
!(NMOL)

!(NMOL/HR)

!(NMOL)
!(NMOL/ML)

PARAMETER (LIVER_1RMN = 1.0E-30)

CFLLI= IMPLC(CLI-(CFLLIR*PLI+(LIBMAX*CFLLIR/(KDLI+CFLLIR &
+LIVER_1RMN))+((CYP1A2_103*CFLLIR/(KDLI2+CFLLIR &

+LIVER_1RMN)*PAS_INDUC)))-CFLLIR,CFLLI0) ! FREE TCDD CONCENTRATION IN LIVER
CFLLIR=DIM(CFLLI,0.0)

CBNDLI= LIBMAX*CFLLIR/(KDLI+CFLLIR+LIVER_1RMN) !BOUND CONCENTRATION
This document is a draft for review purposes only and does not constitute Agency policy.

C-3 8 DRAFT—DO NOT CITE OR QUOTE


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!CONVERSION EQUATION POST SIMULATION
CLITOTAL= (ALI + ALIB)/(WLI + WLIB)

NMOL/ML

PRCT_LI = (CLITOTAL/(MSTT+PARA_ZERO))*100.0
rec_occ_AHR= (CFLLIR/(KDLI+CFLLIR+1) )*100 . 0
OCCUPANCY

PROT_occ_lA2= (CFLLIR/(KDLI2+CFLLIR))*100.0
OCCUPANCY

CLINGKG =(CLITOTAL*MW*UNITCORR)

CBNDLINGKG = CBNDLI*MW*UNITCORR
AUCLI_NGKGH=INTEG(CLINGKG, 0.0)

CLINGG=CLITOTAL*MW

!VARIABLE ELIMINATION HALF-LIFE BASED ON THE CONCENTRATION OF CYP1A2
KBILE_LI_T =((CYP1A2_10UT-CYP1A2_1A2)/CYP1A2_1A2)*Kelv ! INDUCED BILIARY
EXCRETION RATE CONSTANT

REXCLI= (KBILE_LI_T*CFLLIR*WLI) ! DOSE-DEPENDENT BILIARY EXCRETION RATE
EXCLI = INTEG(REXCLI,0.0)

!CHEMICAL IN CYP450 (1A2) COMPARTMENT
!===PARAMETER FOR INDUCTION OF CYP1A2

CYP1A2_1KINP = CYP1A2_1K0UT* CYP1A2_10UTZ ! BASAL RATE OF CYP1A2 PRODUCTION
SET EQUAL TO BASAL RATE OF DEGREDATION

! TOTAL CONCENTRATION IN

! PERCENT OF AhR
! PERCENT OF 1A2

! MODIFICATION ON OCTOBER 6, 2009
CYP1A2_10UT =INTEG(CYP1A2_1KINP * (1.0 + CYP1A2_1EMAX *(CBNDLI+1.0e-
30)**HILL &

/(CYP1A2_1EC50**HILL + (CBNDLI+1.Oe-30)**HILL)) &-
- CYP1A2_1K0UT*CYP1A2_10UT, CYP1A2_10UTZ)

! EQUATIONS INCORPORATING DELAY OF CYP1A2 PRODUCTION (NOT USED IN
SIMULATIONS)

CYP1A2_1R02 = (CYP1A2_10UT - CYP1A2_102)/ CYP1A2_1TAU

CYP1A2_102 =INTEG(CYP1A2_1R02, CYP1A2_1A1)

CYP1A2_1R03 = (CYP1A2_102 - CYP1A2_103)/ CYP1A2_1TAU
CYP1A2_103 =INTEG(CYP1A2_1R03, CYP1A2_1A2)

! 	CHECK MASS BALANCE	

BDOSE= LYMLUM+LIMLUM+IVDOSE

BMASSE = EXCLI+AURI+AFB+AF+AREB+ARE+ALIB+ALI
BDIFF = BDOSE-BMASSE

!	BODY BURDEN	

BBNGKG =(((AFB+AF+AREB+ARE+ALIB+ALI)*MW)/(WTO/UNITCORR)) !
! 	END OF THE SIMULATION COMMAND	

TERMT (T.GE. TimeLimit, 'Time limit has been reached.')

END ! END OF THE DERIVATIVE SECTION

END ! END OF THE DYNAMIC SIMULATION SECTION

END ! END OF THE PROGRAM.

This document is a draft for review purposes only and does not constitute Agency policy.

C-39 DRAFT—DO NOT CITE OR QUOTE


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C.2.3.2. Input Files

C.2.3.2.1. Cantoni et al. (1981).

output 0clear
prepare 0clear

prepare T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG CBNGKG

%Cantoni et al. 1981

%protocol: oral exposure 1 dose/week for 45 weeks; female CD-COBS rats

%Rat Dioxin 3C June09 2clean.csl

%RAT_NON_GEST_ICF_F083109.CSL (now 09-11-09)

%dose levels: 0.01, 0.1, 1 ug/kg 1 dose/week for 45 weeks

%dose levels: 10, 100, 1000 ng/kg 1 dose/week for 45 weeks

%dose levels equivalent to: 1.43, 14.3 143 ng/kg 7 days/weeks for 45 weeks

MAXT
CINT

EXP_TIME_ON

EX P_T I ME_0 F F

DAY_CYCLE

B C K_TIME_ON

BCK_TIME_OFF

TIMELIMIT

BW_T0

(g)

o. 01

0.1

0.

7560
168
0.

0.

7560
125

%delay before begin exposure (HOUR)
iTIME EXPOSURE STOP (HOUR)

¦;DELAY BEFORE BACGROUND EXPOSURE (HOUR)
iTIME OF BACKGROUND EXPOSURE STOP (HOUR)
¦;SIMULATION LIMIT TIME (HOUR)

i Body weight at the beginning of the simulation

iEXPOSURE DOSE SCENARIOS	(UG/KG)

%MSTOT =0.01	% exposure dose ug/kg

%MSTOT =0.1	% exposure dose ug/kg

MSTOT =1	% exposure dose ug/kg

C.2.3.2.2. Chu et al (2007).

output 0clear
prepare 0clear

prepare T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG

% Chu et al. 2 0
%protocol: ora
%dose levels: 0
% dose levels =
MAXT
CINT

EXP_TIME_ON
after start of
EX P_T I ME_0 F F
every two weeks
DAY_CYCLE
B C K_TIME_ON
BCK_TIME_OFF
TIMELIMIT
BW_T0

simulation (g) ;

07

1 exposure daily for 28 days

.0025, 0.025, 0.250, 1.0 ug/kg every day for 28 days
2.5, 25, 250, 1000 ng/kg every day for 28 days
= 0. 01
= 0.1

= 0.	%delay before begin exposure (HOUR) 5 weeks

experiment (age = 12 weeks)

= 672.	%TIME EXPOSURE STOP (HOUR); 30 doses, 1

24 .

0.

0.

672 .
200.

once every two weeks

%DELAY BEFORE BACKGROUND EXPOSURE (HOUR)
%TIME OF BACKGROUND EXPOSURE STOP (HOUR)
i;SIMULATION LIMIT TIME (HOUR)

% Body weight at the beginning of the

corresponds to 12 week old female

iEXPOSURE DOSE SCENARIOS (UG/KG)

This document is a draft for review purposes only and does not constitute Agency policy.

C-40 DRAFT—DO NOT CITE OR QUOTE


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%MSTOT	= 0.0025

%MSTOT	= 0.025

%MSTOT	= 0.250

MSTOT	=1.0

% ORAL EXPOSURE DOSE (UG/KG)
% ORAL EXPOSURE DOSE (UG/KG)
% ORAL EXPOSURE DOSE (UG/KG)
% ORAL EXPOSURE DOSE (UG/KG)

C.2.3.2.3. Crofton et al. (2005).

output 0clear
prepare 0clear

prepare T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG

% Crofton et al. 2005

%protocol: oral exposure daily for 4 days

%dose levels: 0.0001, 0.003, 0.01, 0.03, 0.1, 0.3, 1, 3, and 10 ug/kg every
day for four days

%dose levels: 0.1, 3, 10, 30, 100, 300, 1000, 3000, and 10000 ng/kg every day
for four days

MAXT	=	0.01

CINT	=	0.1

EXP_TIME_ON	=	0.

after start of experiment (age

EX P_TIME_0 FF =	96.

every two weeks

DAY_CYCLE	=	24.

B C K_T I ME_ON	=	0.

BCK_TIME_OFF =	0.

TIMELIMIT	=	96.

BW TO	=	250

%delay before begin exposure (HOUR) 5 weeks
12 weeks)

%TIME EXPOSURE STOP (HOUR); 30 doses, 1

% once every two weeks

%DELAY BEFORE BACKGROUND EXPOSURE (HOUR)
%TIME OF BACKGROUND EXPOSURE STOP (HOUR)
%SIMULATION LIMIT TIME (HOUR)

% Body weight at the beginning of the

simulation (g); corresponds to 12 week old female

iEXPOSURE DOSE SCENARIOS (UG/KG)

MSTOT	= 0.0001

%MSTOT	= 0.003

%MSTOT	=0.01

%MSTOT	=0.03

%MSTOT	=0.1

%MSTOT	=0.3

%MSTOT	=1. %

%MSTOT	=3. %

MSTOT	=10. %

% ORAL EXPOSURE DOSE (UG/KG)
% ORAL EXPOSURE DOSE (UG/KG)
% ORAL EXPOSURE DOSE (UG/KG)
% ORAL EXPOSURE DOSE (UG/KG)

>	ORAL EXPOSURE DOSE (UG/KG)

>	ORAL EXPOSURE DOSE (UG/KG)
ORAL EXPOSURE DOSE (UG/KG)
ORAL EXPOSURE DOSE (UG/KG)
ORAL EXPOSURE DOSE (UG/KG)

C.2.3.2.4. Fattore et al. (2000).

output 0clear
prepare 0clear

prepare T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG

% Fattore et al. 2000

%built and check in August 7 2009

%protocol: oral exposure in diet for 13 weeks; SD rats

%dose levels: 0.02, 0.1, 0.2, 2 ug/kg 7 days/week for 13 weeks

%dose levels equivalent to: 20, 100, 200, 2000 ng/kg 7 days/week for 13 weeks

MAXT = 0.01

This document is a draft for review purposes only and does not constitute Agency policy.

C-41 DRAFT—DO NOT CITE OR QUOTE


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CINT =0.1

EXP_TIME_ON

EX P_T I ME_0 F F

DAY_CYCLE

B C K_TIME_ON

BCK_TIME_OFF

TIMELIMIT

BW_T0

(G)

0.

2184
24
0.

0.

2184
150

%TIME AT WHICH EXPOSURE BEGINS (HOUR)
iTIME AT WHICH EXPOSURE ENDS (HOUR)

iTIME AT WHICH BACKGROUND EXPOSURE BEGINS (HOUR)
iTIME AT WHICH BACKGROUND EXPOSURE ENDS (HOUR)
¦;SIMULATION TIME LIMIT (HOUR)

i BODY WEIGHT AT THE BEGINNING OF THE SIMULATION

iEXPOSURE DOSE	SCENARIOS (UG/KG)

%MSTOT	=0.02

%MSTOT	=0.1

%MSTOT	= 0.2

MSTOT	= 2

% EXPOSURE DOSE IN UG/KG
% EXPOSURE DOSE IN UG/KG
% EXPOSURE DOSE IN UG/KG
EXPOSURE DOSE IN UG/KG

C.2.3.2.5. Franc et al. (2001). Sprague Dawley rats

output 0clear
prepare 0clear

prepare T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG CBNGKG

%	Franc et al. 2001

%	Non-gestational rat model

%	dose levels: 0.140, 0.420, and 1.400 ug/kg every 2 weeks for 22 weeks

%	dose levels: 140, 420, and 1400 ng/kg every 2 weeks for 22 weeks

%	dose levels equivalent to 10, 30, and 100 ng/kg/day

MAXT

II

o
o



CINT

II

o



EXP TIME ON

= 0.

%delay before begin exposure (HOUR)

EXP TIME OFF

= 3696.

%TIME EXPOSURE STOP (HOUR)

DAY CYCLE

= 336.



BCK TIME ON

= 0.

%DELAY BEFORE BACGROUND EXPOSURE (HOUR)

BCK TIME OFF

= 0.

%TIME OF BACKGROUND EXPOSURE STOP (HOUR)

TIMELIMIT

= 3696.

%SIMULATION LIMIT TIME (HOUR)

BW TO

= 200.

% Body weight at the beginning of the

simulation (g) ;

corresponds

to approximate weight of females 10 weeks old

iEXPOSURE DOSE	SCENARIOS	(UG/KG)

%MSTOT	=0.14	% ORAL EXPOSURE DOSE (UG/KG)

%MSTOT	=0.42	% ORAL EXPOSURE DOSE (UG/KG)

MSTOT	=1.4	% ORAL EXPOSURE DOSE (UG/KG)

C.2.3.2.6. Franc et al. (2001). Long-Evans rats

output 0clear
prepare 0clear

prepare T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG CBNGKG

%	Franc et al. 2001

%	Non-gestational rat model

%	dose levels: 0.140, 0.420, and 1.400 ug/kg every 2 weeks for 22 weeks

%	dose levels: 140, 420, and 1400 ng/kg every 2 weeks for 22 weeks

%	dose levels equivalent to 10, 30, and 100 ng/kg/day

This document is a draft for review purposes only and does not constitute Agency policy.

C-42 DRAFT—DO NOT CITE OR QUOTE


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54

MAXT

II

o
o

I—1



CINT

II

o

I—1



EXP TIME ON

= 0.

%delay before begin exposure (HOUR)

EXP TIME OFF

= 3696.

%TIME EXPOSURE STOP (HOUR)

DAY CYCLE

= 336.



BCK TIME ON

= 0.

%DELAY BEFORE BACGROUND EXPOSURE (HOUR)

BCK TIME OFF

= 0.

%TIME OF BACKGROUND EXPOSURE STOP (HOUR)

TIMELIMIT

= 3696.

%SIMULATION LIMIT TIME (HOUR)

BW TO

= 190.

% Body weight at the beginning of the

simulation (g) ;

corresponds

to approximate weight of females 10 weeks old

iEXPOSURE DOSE	SCENARIOS	(UG/KG)

%MSTOT	=0.14	% ORAL EXPOSURE DOSE (UG/KG)

%MSTOT	=0.42	% ORAL EXPOSURE DOSE (UG/KG)

MSTOT	=1.4	% ORAL EXP

C.2.3.2.7. Franc et al. (2001). Hans Wistar rats

output 0clear
prepare 0clear

prepare T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG CBNGKG

%	Franc et al. 2001

%	Non-gestational rat model

%	dose levels: 0.140, 0.420, and 1.400 ug/kg every 2 weeks for 22 weeks

%	dose levels: 140, 420, and 1400 ng/kg every 2 weeks for 22 weeks

%	dose levels equivalent to 10, 30, and 100 ng/kg/day

MAXT

II

o
o

I—1



CINT

II

o

I—1



EXP TIME ON

= 0.

%delay before begin exposure (HOUR)

EXP TIME OFF

= 3696.

%TIME EXPOSURE STOP (HOUR)

DAY CYCLE

= 336.



BCK TIME ON

= 0.

%DELAY BEFORE BACGROUND EXPOSURE (HOUR)

BCK TIME OFF

= 0.

%TIME OF BACKGROUND EXPOSURE STOP (HOUR)

TIMELIMIT

= 3696.

%SIMULATION LIMIT TIME (HOUR)

BW TO

= 205.

% Body weight at the beginning of the

simulation (g) ;

corresponds

to approximate weight of females 10 weeks old

iEXPOSURE DOSE	SCENARIOS	(UG/KG)

%MSTOT	=0.14	% ORAL EXPOSURE DOSE (UG/KG)

%MSTOT	=0.42	% ORAL EXPOSURE DOSE (UG/KG)

MSTOT	=1.4	% ORAL EXP

C.2.3.2.8. Hassoun et al. (2000).

output 0clear
prepare 0clear

prepare T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG CBNGKG
% Hassoun et al. 2000

%protocol: oral exposure for 13 weeks; SD rats

%dose levels: 0.003, 0.010, 0.022, 0.046 0.1 ug/kg 5 days/weeks for 13 weeks
%dose levels equivalent to: 3, 10, 22, 46 100 ng/kg 5 days/weeks for 13 weeks
%dose levels equivalent to: 2.14, 7.14, 15.7, 32.9 71.4 ng/kg 7 days/weeks
for 13 weeks

This document is a draft for review purposes only and does not constitute Agency policy.

C-43 DRAFT—DO NOT CITE OR QUOTE


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53

MAXT	= 0.01

CINT	=0.1

EXP_TIME_ON	= 0.

EX P_TIME_0 FF	= 2184.

DAY_CYCLE	= 24.

WEEK_PERIOD	= 168.

WEEK_FINISH	= 119.

B C K_T I ME_ON	= 0.

BCK_TIME_OFF	= 0.

TIMELIMIT	= 2184.

BW_T0	=215.
simulation (g)

idelay before begin exposure (HOUR)
iTIME EXPOSURE STOP (HOUR)

iDELAY BEFORE BACKGROUND EXPOSURE (HOUR)
iTIME OF BACKGROUND EXPOSURE STOP (HOUR)
iSIMULATION LIMIT TIME (HOUR)

% Body weight at the beginning of the

iEXPOSURE DOSE SCENARIOS (UG/KG)

%MSTOT	= 0.003	% exposure dose ug/kg

%MSTOT	= 0.010	% exposure dose ug/kg

%MSTOT	= 0.022	% exposure dose ug/kg

%MSTOT	= 0.046	% exposure dose ug/kg

MSTOT	=0.1	% exposure dose ug/kg

C.2.3.2.9. Hutt et al. (2008).

output 0clear
prepare 0clear

prepare T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG CBNGKG

%	Hutt et al. 2008

%	Non-gestational rat model

%	dose levels: 0.050 ug/kg every week for 13 weeks

%	dose levels: 50 ng/kg every week for 13 weeks

%	dose levels equivalent to 7.14 ng/kg/day

MAXT
CINT

EXP_TIME_ON
EX P_T I ME_0 F F
DAY_CYCLE
B C K_TIME_ON
BCK_TIME_OFF
TIMELIMIT
BW TO

0. 01

0.1

0.

2184 .
168 .
0.

0.

2184 .
4 . 5

idelay before begin exposure (HOUR)

%TIME EXPOSURE STOP (HOUR)

%DELAY BEFORE BACGROUND EXPOSURE (HOUR)
%TIME OF BACKGROUND EXPOSURE STOP (HOUR)

%SIMULATION LIMIT TIME (HOUR)
i Body weight at the beginning of the

simulation (g); corresponds to approximate weight of females 10 weeks old

iEXPOSURE DOSE SCENARIOS (UG/KG)

MSTOT

= 0. 05

ORAL EXPOSURE DOSE (UG/KG)

C.2.3.2.10. Kitchin and Woods (1979)

output 0clear
prepare 0clear

prepare T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG CBNGKG

% Kitchen and Woods 1979
%protocol: single oral gavage

This document is a draft for review purposes only and does not constitute Agency policy.

C-44 DRAFT—DO NOT CITE OR QUOTE


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55

idose levels: 0.0006, 0.002, 0.004, 0.020, 0.060, 0.200, 0.600, 2.000,

5.000, 20.000 ug/kg single
% dose levels = 0.6, 2, 4,
oral gavage

MAXT	=	0.001

CINT	=	0.1

EXP_TIME_ON	=	0.

EX P_TIME_0 FF	=	24.

DAY_CYCLE	=	24.

B C K_T I ME_ON	=	0.

BCK_TIME_OFF	=	0.

TIMELIMIT	=	24.

BW_T0	=	225.
simulation (g)

oral gavage

20, 60, 200, 600, 2000, 5000, 20000 ng/kg single

idelay before begin exposure (HOUR)

%TIME EXPOSURE STOP (HOUR)

% daily

%DELAY BEFORE BACKGROUND EXPOSURE (HOUR)
%TIME OF BACKGROUND EXPOSURE STOP (HOUR)
%SIMULATION LIMIT TIME (HOUR)

% Body weight at the beginning of the

iEXPOSURE DOSE
%MSTOT
%MSTOT
%MSTOT
%MSTOT
%MSTOT
%MSTOT
%MSTOT
%MSTOT
%MSTOT
MSTOT

SCENARIOS (UG/KG)
= 0.0006
= 0.002
= 0.004
= 0.020
= 0.060
= 0.200
= 0.600
= 2.000
= 5.000
= 20.000

i ORAL EXPOSURE DOSE (UG/KG)
i ORAL EXPOSURE DOSE (UG/KG)
% ORAL EXPOSURE DOSE (UG/KG)
% ORAL EXPOSURE DOSE (UG/KG)
% ORAL EXPOSURE DOSE (UG/KG)
ORAL EXPOSURE DOSE (UG/KG)
i ORAL EXPOSURE DOSE (UG/KG)
% ORAL EXPOSURE DOSE (UG/KG)
% ORAL EXPOSURE DOSE (UG/KG)
% ORAL EXPOSURE DOSE (UG/KG)

C.2.3.2.11. Kociba et al. (1976) (13 weeks).

output 0clear
prepare 0clear

prepare T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG CBNGKG

% Kociba et al. 1976.

%built and check in August 7 2009

%protocol: 5 days/week exposure for 13 weeks; SD rats
%Rat Dioxin 3C June09 2clean.csl
%RAT~NON_GEST_ICF_F083109.CSL (now 09-11-09)

%dose levels: 0.001, 0.01, 0.1, 1 ug/kg 5 days/weeks for 13 weeks

%dose levels: 1, 10, 100, 1000 ng/kg 5 days/weeks for 13 weeks

%dose levels equivalent to: 0.714, 7.14, 71.4, 714 ng/kg/d (adj) 7 days/weeks

for 13 weeks

MAXT
CINT

EXP_TIME_ON

EX P_T I ME_0 F F

WEEK_PERIOD

WEEK_FINISH

DAY_CYCLE

B C K_TIME_ON

BCK_TIME_OFF

TIMELIMIT

BW_T0

simulation (g)

0. 001

0.1

0.

2184
168
119
24
0.

0.

2184
180

idelay before begin exposure (HOUR)
iTIME EXPOSURE STOP (HOUR)

iDELAY BEFORE BACGROUND EXPOSURE (HOUR)
iTIME OF BACKGROUND EXPOSURE STOP (HOUR)
iSIMULATION LIMIT TIME (HOUR)
i Body weight at the begeniong of the

This document is a draft for review purposes only and does not constitute Agency policy.

C-45 DRAFT—DO NOT CITE OR QUOTE


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•;EXPOSURE	DOSE SCENARIOS (UG/KG)

iMSTOT	= 0.001

%MSTOT	=0.01

%MSTOT	=0.1

MSTOT	= 1

C.2.3.2.12. Kociba et al. (1978) (female) (104 weeks).

output 0clear
prepare 0clear

prepare T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG

% Kociba et al, 1978.

%built and check in August 7 2009

%protocol: daily dietary exposure for 104 weeks; SD rats
%dose levels: 0.001, 0.01, 0.1 ug/kg 7 days/week for 104 weeks
%dose levels: 1, 10, 100 ng/kg 7 days/week for 104 weeks

MAXT	=	0.01

CINT	=	0.1

EXP_TIME_ON	=	0.

EX P_T I ME_0 F F	=	17472

DAY_CYCLE	=	2 4

B C K_T I ME_ON	=	0.
(HOUR)

BCK_TIME_OFF	=	0.
(HOUR)

TIMELIMIT	=	17472

BW_T0	=	180
SIMULATION (G)

iTIME AT WHICH EXPOSURE BEGINS (HOUR)
iTIME AT WHICH EXPOSURE ENDS (HOUR)

iTIME AT WHICH BACKGROUND EXPOSURE BEGINS

iTIME AT WHICH BACKGROUND EXPOSURE ENDS

iSIMULATION TIME LIMIT (HOUR)
i BODY WEIGHT AT THE BEGINNING OF THE

%EXPOSURE DOSE SCENARIOS (UG/KG)
%MSTOT	= 0.001

%MSTOT	=0.01

MSTOT	=0.1

% EXPOSURE DOSE IN UG/KG
% EXPOSURE DOSE IN UG/KG
% EXPOSURE DOSE IN UG/KG

C.2.3.2.13. Kociba et al (1978) (male) (104 weeks).

output 0clear
prepare 0clear

prepare T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG

% Kociba et al, 1978.

%built and check in August 7 2009

%protocol: daily dietary exposure for 104 weeks; SD rats
%dose levels: 0.001, 0.01, 0.1 ug/kg 7 days/week for 104 weeks
%dose levels: 1, 10, 100 ng/kg 7 days/week for 104 weeks

MAXT

II

o
o

I—1







CINT

II

o

I—1







EXP TIME ON

= 0.

%TIME

AT

WHICH

EXP TIME OFF

= 17472

%TIME

AT

WHICH

DAY CYCLE

= 24







BCK TIME ON

= 0.

%TIME

AT

WHICH

(HOUR)









(HOUR)

This document is a draft for review purposes only and does not constitute Agency policy.

C-46 DRAFT—DO NOT CITE OR QUOTE


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53

54

BCK_TIME_OFF = 0.
(HOUR)

TIMELIMIT	= 17472

BW_T0	= 250

SIMULATION (G)

iTIME AT WHICH BACKGROUND EXPOSURE ENDS

iSIMULATION TIME LIMIT (HOUR)
i BODY WEIGHT AT THE BEGINNING OF THE

•;EXPOSURE	DOSE SCENARIOS (UG/KG)

%MSTOT	= 0.001

%MSTOT	=0.01

MSTOT	=0.1

% EXPOSURE DOSE IN UG/KG
% EXPOSURE DOSE IN UG/KG
EXPOSURE DOSE IN UG/KG

C.2.3.2.14. Latchoumycandane and Mathur (2002).

output 0clear
prepare 0clear

prepare T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG CBNGKG

% Latchoumycandane and Mathur 2002.

%built and check in August 7 2009

%protocol: 1 time per day for 45 days oral gavage
%Rat Dioxin 3C June09 2clean.csl
%RAT~NON_GEST_ICF_F083109.CSL (now 09-11-09)

%dose levels: 0.001, 0.01, 0.1 ug/kg daily for 45 days
%dose levels: 1, 10, 100 ng/kg daily for 45 days

MAXT
CINT

EXP_TIME_ON

EX P_T I ME_0 F F

DAY_CYCLE

B C K_TIME_ON

BCK_TIME_OFF

TIMELIMIT

BW_T0

simulation (g)

0. 01

0.1

0.

1080
24
0.

0.

1080
200

delay before begin exposure (HOUR)

TIME EXPOSURE STOP (HOUR)

DELAY BEFORE BACGROUND EXPOSURE (HOUR)
TIME OF BACKGROUND EXPOSURE STOP (HOUR)
SIMULATION LIMIT TIME (HOUR)

Body weight at the beginning of the

iEXPOSURE DOSE	SCENARIOS (UG/KG)

%MSTOT	= 0.001

%MSTOT	=0.01

MSTOT	=0.1

% exposure dose ug/kg
i; exposure dose ug/kg
exposure dose ug/kg

C.2.3.2.15. Lietal. (1997).

output 0clear
prepare 0clear

prepare T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG

% Li et al 1997
% created 1/10/10
% Non-gestational rat model

% dose levels: 3, 10, 30, 100, 300, 1000, 3000, 10000, 30000 nkd one dose via
gavage, sacrificed 24 hrs later

MAXT	= 0.1

CINT	= 0.1

This document is a draft for review purposes only and does not constitute Agency policy.

C-47 DRAFT—DO NOT CITE OR QUOTE


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53

EXP TIME ON

= 0.

%delay before begin exposure (HOUR)



EXP TIME OFF

= 24.

%TIME EXPOSURE STOP (HOUR)



DAY CYCLE

= 24.





BCK TIME ON

= 0.

%DELAY BEFORE BACKGROUND EXPOSURE

(HOUR)

BCK TIME OFF

= 0.

%TIME OF BACKGROUND EXPOSURE STOP

(HOUR)

TIMELIMIT

= 24.

%SIMULATION LIMIT TIME (HOUR)



BW TO

= 56.5

% Body weight at the beginning of

the

simulation (g)







iEXPOSURE DOSE
MSTOT

SCENARIOS (UG/KG)

= 0.003	% ORAL EXPOSURE DOSE (UG/KG)

%MSTOT

= 0.

01

O

o

ORAL

EXPOSURE

DOSE

(UG/KG)

%MSTOT

= 0.

03

o
o

ORAL

EXPOSURE

DOSE

(UG/KG)

%MSTOT

= 0.

1

o
o

ORAL

EXPOSURE

DOSE

(UG/KG)

%MSTOT

= 0.

3

o
o

ORAL

EXPOSURE

DOSE

(UG/KG)

%MSTOT

= 1.



o
o

ORAL

EXPOSURE

DOSE

(UG/KG)

%MSTOT

= 3.



o
o

ORAL

EXPOSURE

DOSE

(UG/KG)

%MSTOT

= 10



o
o

ORAL

EXPOSURE

DOSE

(UG/KG)

%MSTOT

= 30



o
o

ORAL

EXPOSURE

DOSE

(UG/KG)

C.2.3.2.16. Murray et al. (1979).

output 0clear
prepare 0clear

prepare T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG

% Murray et al 1979

%built and check in August 7 2009

%protocol: dietary exposure for 3 generations (assume 120 day exposure for
each)

%dose levels: 0.001 0.01, 0.1 ug/kg/d
%dose levels: 1, 10, 100 ng/kg/d

MAXT	=	0.01

CINT	=	0.1

EXP_TIME_ON	=	0.

EX P_TIME_0 FF	=	2880

CORRESPONDS TO	12 0	DAYS

DAY_CYCLE	=	24.

B C K_T I ME_ON	=	0.
(HOUR)

BCK_TIME_OFF	=	0.
(HOUR)

TIMELIMIT	=	2880

BW_T0	=	4.5
SIMULATION (G)

%TIME AT WHICH EXPOSURE BEGINS (HOUR)
iTIME AT WHICH EXPOSURE ENDS (HOUR);

OF EXPOSURE

%TIME AT WHICH BACKGROUND EXPOSURE BEGINS

%TIME AT WHICH BACKGROUND EXPOSURE ENDS

i;SIMULATION TIME LIMIT (HOUR)

% BODY WEIGHT AT THE BEGINNING OF THE

iEXPOSURE DOSE SCENARIOS (UG/KG)

%MSTOT
%MSTOT
MSTOT

= 0.001
= 0. 01
= 0.1

% ORAL EXPOSURE DOSE IN UG/KG
i ORAL EXPOSURE DOSE IN UG/KG
ORAL EXPOSURE DOSE IN UG/KG

This document is a draft for review purposes only and does not constitute Agency policy.

C-48 DRAFT—DO NOT CITE OR QUOTE


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C.2.3.2.17. NTP (1982) (female) (chronic).

output 0clear
prepare 0clear

prepare T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG CBNGKG

%NTP 1982

%built and check in August 7 2009

%protocol: twice weekly gavage for 104 weeks + 3 week observation period
%Rat Dioxin 3C June09 2clean.csl
%RAT~NON_GEST_ICF_F083109.CSL (now 09-11-09)

%dose levels: 0.005, 0.025, 0.25 ug/kg biweekly for 104 weeks + 3 week
observation period

%dose levels: 5, 25, 250 ng/kg biweekly for 104 weeks + 3 week observation
period

%dose levels equivalent to: 1.43, 7.14, 71.4 ng/kg/day (adj)

MAXT
CINT

EXP_TIME_ON

EX P_T I ME_0 F F

DAY_CYCLE

B C K_TIME_ON

BCK_TIME_OFF

TIMELIMIT

BW_T0

simulation (g)

0. 01

0.1

0.

17472
84
0.

0.

17472
250

idelay before begin exposure (HOUR)
iTIME EXPOSURE STOP (HOUR)

¦;DELAY BEFORE BACKGROUND EXPOSURE (HOUR)
iTIME OF BACKGROUND EXPOSURE STOP (HOUR)
¦;SIMULATION LIMIT TIME (HOUR)
i Body weight at the beginning of the

iEXPOSURE DOSE SCENARIOS (UG/KG)

%MSTOT	= 0.005	% exposure dose ug/kg

%MSTOT	= 0.025

MSTOT	= 0.25

C.2.3.2.18. NTP (1982) (male) (chronic).

output 0clear
prepare 0clear

prepare T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG CBNGKG

%NTP 1982

%built and check in august 7 2009

%protocol: twice weekly gavage for 104 weeks + 3 week observation period
%Rat Dioxin 3C June09 2clean.csl
%RAT~NON_GEST_ICF_F083109.CSL (now 09-11-09)

%dose levels: 0.005, 0.025, 0.25 ug/kg biweekly for 104 weeks + 3 week
observation period

%dose levels: 5, 25, 250 ng/kg biweekly for 104 weeks + 3 week observation
period

%dose levels equivalent to: 1.43, 7.14, 71.4 ng/kg/day (adj)

MAXT
CINT

EXP_TIME_ON
EX P_T I ME_0 F F
DAY CYCLE

= 0. 01
= 0.1
= 0.
= 17472
= 84

idelay before begin exposure (HOUR)
iTIME EXPOSURE STOP (HOUR)

This document is a draft for review purposes only and does not constitute Agency policy.

C-49 DRAFT—DO NOT CITE OR QUOTE


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58

B C K_TIME_ON
BCK_TIME_OFF
TIMELIMIT
BW_T0

simulation (g)

= 0.
= 0.
= 17472
= 350

¦;DELAY BEFORE BACKGROUND EXPOSURE (HOUR)
iTIME OF BACKGROUND EXPOSURE STOP (HOUR)
¦;SIMULATION LIMIT TIME (HOUR)
i Body weight at the beginning of the

iEXPOSURE DOSE SCENARIOS (UG/KG)

%MSTOT
%MSTOT
MSTOT

= 0.005
= 0.025
0.25

exposure dose ug/kg

C.2.3.2.19. NTP (2006) 14 weeks.

output @clear
prepare @clear

prepare T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG CBNGKG
% NTP 2006

%built and check in August 7 2009
%protocol: oral exposure for 14 weeks; SD rats
%Rat_Dioxin_3C June09_2clean.csl
%RAT_NON_GEST_ICF_F08310 9.CSL (now 09-11-09)

%dose levels: 0.003, 0.010, 0.022, 0.046 0.1 ug/kg 5 days/weeks for 14 weeks
%dose levels equivalent to: 3, 10, 22, 46 100 ng/kg 5 days/weeks for 14 weeks
%dose levels equivalent to: 2.14, 7.14, 15.7, 32.9 71.4 ng/kg 7 days/weeks for

14 weeks







MAXT

= 0.01





CINT

= 0.1





EXP TIME ON

= 0.

%delay before begin exposure (HOUR)

EXP TIME OFF

= 2352

%TIME EXPOSURE STOP (HOUR)



DAY CYCLE

= 24





WEEK PERIOD

= 168





WEEK FINISH

= 119





BCK TIME ON

= 0.

%DELAY BEFORE BACKGROUND EXPOSURE

(HOUR)

BCK TIME OFF

= 0.

%TIME OF BACKGROUND EXPOSURE STOP

(HOUR)

TIMELIMIT

= 2352

%SIMULATION LIMIT TIME (HOUR)



BW TO

= 215

% Body weight at the beginning of

the simulation

(g)







%EXPOSURE DOSE

SCENARIOS (UG/KG)



%MSTOT

= 0.003

% exposure dose ug/kg



%MSTOT

= 0.010

% exposure dose ug/kg



%MSTOT

= 0.022

% exposure dose ug/kg



%MSTOT

= 0.046

% exposure dose ug/kg



MSTOT

II

o

I-1

% exposure dose ug/kg



C.2.3.2.20. NTP (2006) 31 weeks.





output 0clear
prepare 0clear

prepare T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG CBNGKG

% NTP 2006

%built and check in August 7 2009
%protocol: oral exposure for 31 weeks; SD rats
%Rat Dioxin 3C June09 2clean.csl
%RAT_NON_GEST_ICF_F083109.CSL (now 09-11-09)

%dose levels: 0.003, 0.010, 0.022, 0.046 0.1 ug/kg 5 days/weeks for 31 weeks
This document is a draft for review purposes only and does not constitute Agency policy.

C-50 DRAFT—DO NOT CITE OR QUOTE


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52

53

54

55

%dose levels equivalent to: 3, 10, 22, 46 100 ng/kg 5 days/weeks for 31 weeks
%dose levels equivalent to: 2.14, 7.14, 15.7, 32.9 71.4 ng/kg 7 days/weeks
for 31 weeks

MAXT	= 0.01

CINT	=0.1

EXP_TIME_ON	= 0.

EX P_TIME_0 FF	= 52 0 8

DAY_CYCLE	= 2 4

WEEK_PERIOD	= 168

WEEK_FINISH	= 119

B C K_T I ME_ON	= 0.

BCK_TIME_OFF	= 0.

TIMELIMIT	= 5208

BW_T0	=215
simulation (g)

%delay before begin exposure (HOUR)
iTIME EXPOSURE STOP (HOUR)

%DELAY BEFORE BACKGROUND EXPOSURE	(HOUR)

%TIME OF BACKGROUND EXPOSURE STOP	(HOUR)
i;SIMULATION LIMIT TIME (HOUR)

% Body weight at the beginning of	the

iEXPOSURE DOSE SCENARIOS (UG/KG)

%MSTOT	= 0.003	% exposure dose ug/kg

%MSTOT	= 0.010	% exposure dose ug/kg

%MSTOT	= 0.022	% exposure dose ug/kg

%MSTOT	= 0.046	% exposure dose ug/kg

MSTOT	=0.1	% exposure dose ug/kg

C.2.3.2.21. NTP (2006) 53 weeks.

output 0clear
prepare 0clear

prepare T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG CBNGKG

% NTP 2006

%built and check in August 7 2009
%protocol: oral exposure for 53 weeks; SD rats
%Rat Dioxin 3C June09 2clean.csl
%RAT~NON_GEST_ICF_F083109.CSL (now 09-11-09)

%dose levels: 0.003, 0.010, 0.022, 0.046 0.1 ug/kg 5 days/weeks for 53 weeks
%dose levels equivalent to: 3, 10, 22, 46 100 ng/kg 5 days/weeks for 53 weeks
%dose levels equivalent to: 2.14, 7.14, 15.7, 32.9 71.4 ng/kg 7 days/weeks
for 53 weeks

MAXT	= 0.01

CINT	=0.1

EXP_TIME_ON	= 0.

EX P_T I ME_0 F F	= 8904

DAY_CYCLE	= 2 4

WEEK_PERIOD	= 168

WEEK_FINISH	= 119

B C K_T I ME_ON	= 0.

BCK_TIME_OFF	= 0.

TIMELIMIT	= 8904

BW_T0	=215
simulation (g)

%delay before begin exposure (HOUR)
iTIME EXPOSURE STOP (HOUR)

%DELAY BEFORE BACKGROUND EXPOSURE	(HOUR)

%TIME OF BACKGROUND EXPOSURE STOP	(HOUR)
i;SIMULATION LIMIT TIME (HOUR)

% Body weight at the beginning of	the

%EXPOSURE DOSE SCENARIOS (UG/KG)

%MSTOT	= 0.003	% exposure dose ug/kg

%MSTOT	= 0.010	% exposure dose ug/kg

This document is a draft for review purposes only and does not constitute Agency policy.

C-51 DRAFT—DO NOT CITE OR QUOTE


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49

50

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53

54

%MSTOT
%MSTOT
MSTOT

= 0. 022
= 0. 046
= 0.1

% exposure dose ug/kg

% exposure dose ug/kg
% exposure dose ug/kg

C.2.3.2.22. NTP (2006) 2 year.

output 0clear
prepare 0clear

prepare T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG

% NTP 2006

%built and check in August 7 2009

%protocol: oral exposure for 105 weeks; SD rats

%dose levels: 0.003, 0.010, 0.022, 0.046, 0.1 ug/kg 5 days/week for 105
weeks

%dose levels equivalent to: 3, 10, 22, 46, 100 ng/kg 5 days/week for 105
weeks

%dose levels equivalent to: 2.14, 7.14, 15.7, 32.9, 71.4 ng/kg 7 days/week
for 105 weeks

MAXT	=	0.01

CINT	=0.1

EXP_TIME_ON	=	0.

EX P_TIME_0 FF	=	17 64 0

DAY_CYCLE	=	2 4

WEEK_PERIOD	=	168

WEEK_FINISH	=	119

B C K_T I ME_ON	=	0.
(HOUR)

BCK_TIME_OFF	=	0.

TIMELIMIT	=	17640

BW_T0	=215
SIMULATION (G)

iTIME AT WHICH EXPOSURE BEGINS (HOUR)
iTIME AT WHICH EXPOSURE ENDS (HOUR)

iTIME AT WHICH BACKGROUND EXPOSURE BEGINS

iTIME AT WHICH BACKGROUND EXPOSURE ENDS (HOUR)
iSIMULATION TIME LIMIT (HOUR)
i BODY WEIGHT AT THE BEGINNING OF THE

iEXPOSURE DOSE SCENARIOS (UG/KG)

%MSTOT
%MSTOT
%MSTOT
%MSTOT
MSTOT

= 0.003
= 0.010
= 0.022
= 0. 046
0.1

EXPOSURE DOSE IN UG/KG

% EXPOSURE DOSE IN UG/KG
% EXPOSURE DOSE IN UG/KG

% EXPOSURE DOSE IN UG/KG
% EXPOSURE DOSE IN UG/KG

C.2.3.2.23. Sewall et al. (1995).

output 0clear
prepare 0clear

prepare T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG CBNGKG

% Sewall et al. 1995

%Rat Dioxin 3C June09 2clean.csl

%RAT~NON_GEST_ICF_F083109.CSL (now 09-11-09)

%protocol: gavage every 2 weeks for 30 weeks

%dose levels: 0.049, 0.1498, 0.49, and 1.75 ug/kg every 2 weeks

%dose levels: 3.5, 10.7, 35, and 125 ng/kg/d or 49, 149.8, 490, and 1750

ng/kg every 2 weeks

MAXT	= 0.01

CINT	= 0.1

This document is a draft for review purposes only and does not constitute Agency policy.

C-52 DRAFT—DO NOT CITE OR QUOTE


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EXP_TIME_ON	= 0.

after start of experiment

EX P_T I ME_0 F F

every two weeks

DAY_CYCLE

B C K_TIME_ON

BCK_TIME_OFF

TIMELIMIT

BW TO

=	5040

=	336.

=	0.

=	0.

=	5040

=	250

%delay before begin exposure (HOUR) 5 weeks
(age = 12 weeks)

%TIME EXPOSURE STOP (HOUR); 30 doses, 1

% once every two weeks
%DELAY BEFORE BACKGROUND EXPOSURE (HOUR)
%TIME OF BACKGROUND EXPOSURE STOP (HOUR)
%SIMULATION LIMIT TIME (HOUR)

% Body weight at the beginning of the

simulation (g); corresponds to 12 week old female

iEXPOSURE DOSE SCENARIOS (UG/KG)

%MSTOT
%MSTOT
%MSTOT
MSTOT

= 0.049
= 0. 1498
= 0.49
= 1.75

% ORAL EXPOSURE DOSE (UG/KG)
% ORAL EXPOSURE DOSE (UG/KG)
i ORAL EXPOSURE DOSE (UG/KG)
ORAL EXPOSURE DOSE (UG/KG)

C.2.3.2.24. Shi et al. (2007), adult portion.

output 0clear
prepare 0clear

prepare T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG

% Shi et al 2007

%built and check in August 7 2009
%protocol: gavage once per week for 322 days

%dose levels: 0.001, 0.005, 0.05 and 0.2 ug TCDD:kg body weight by gavage
once per week

%dose levels: 1, 5, 50 and 200 ng/kg ng TCDD:kg body weight by gavage once
per week

% dose equivalent adjusted 0.143, 0.714, 7.14 and 28.6 ng/kg/d

MAXT
CINT

EXP_TIME_ON
EX P_T I ME_0 F F
CORRESPONDS TO
DAY_CYCLE
B C K_TIME_ON
BEGINS (HOUR)
BCK_TIME_OFF
(HOUR)
TIMELIMIT
BW_T0

SIMULATION (G)

= 0.0001
= 0.1
= 504 .
= 7728
DAYS
168 .

0.

322

= 0.

% TIME AT WHICH EXPOSURE BEGINS (HOUR)
iTIME AT WHICH EXPOSURE ENDS (HOUR);

OF EXPOSURE

TIME AT WHICH BACKGROUND EXPOSURE

TIME AT WHICH BACKGROUND EXPOSURE ENDS

7728
4 . 5

i;SIMULATION TIME
% BODY WEIGHT AT

LIMIT (HOUR)
THE BEGINNING OF THE

iEXPOSURE DOSE SCENARIOS (UG/KG)

%MSTOT
%MSTOT
%MSTOT
MSTOT

= 0.001	% ORAL EXPOSURE DOSE IN UG/KG

= 0.005	% ORAL EXPOSURE DOSE IN UG/KG

=0.05	% ORAL EXPOSURE DOSE IN UG/KG

=0.2	% ORAL EXPOSURE DOSE IN UG/KG

C.2.3.2.25. Van Birgelen et al (1995).

output 0clear
prepare 0clear

This document is a draft for review purposes only and does not constitute Agency policy.

C-53 DRAFT—DO NOT CITE OR QUOTE


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prepare T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG

% Van Birgelen et al. (1995)

%protocol: daily dietary exp
%dose levels: 0.0135, 0.0264,
weeks

% dose levels = 13.5, 26.4, 46.9, 320, 1024 ng/kg every day for 13 weeks
MAXT	= 0.01

CINT	= 0.1

EXP_TIME_ON	= 0.

EX P_TIME_0 FF = 2184.

DAY_CYCLE	= 24.

B C K_T I ME_ON	= 0.

BCK_TIME_OFF = 0.

TIMELIMIT	= 2184.

BW_T0	= 150.

simulation (g)

osure for 13 weeks
0.0469, 0.320, 1.024 ug/kg every day for 13

idelay before begin exposure (HOUR)

%TIME EXPOSURE STOP (HOUR)

% once every two weeks

%DELAY BEFORE BACKGROUND EXPOSURE (HOUR)
%TIME OF BACKGROUND EXPOSURE STOP (HOUR)
%SIMULATION LIMIT TIME (HOUR)

% Body weight at the beginning of the

iEXPOSURE
%MSTOT
%MSTOT
%MSTOT
%MSTOT
MSTOT

DOSE SCENARIOS (UG/KG)
= 0.0135
= 0.0264
= 0. 0469
= 0.320
= 1. 024

ORAL EXPOSURE DOSE (UG/KG)
i ORAL EXPOSURE DOSE (UG/KG)
% ORAL EXPOSURE DOSE (UG/KG)
i ORAL EXPOSURE DOSE (UG/KG)
ORAL EXPOSURE DOSE (UG/KG)

C.2.3.2.26. Vanden Heuvel et al. (1994).

output 0clear
prepare 0clear

prepare T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG CBNGKG

% Vanden Heuvel et al. 1994.

%built and check in August 7 2009

%protocol: single gavage

%Rat Dioxin 3C June09 2clean.csl

%RAT_NON_GEST_ICF_F083109.CSL (now 09-11-09)

%dose levels:0.00005, 0.0001, 0.001, 0.010, 0.1, 1, 10 ug/kg/d

%dose levels equivalent to: 0.05, 0.1, 1, 10, 100, 1000, 10000 ng/kg/d

MAXT
CINT

EXP_TIME_ON

EX P_T I ME_0 F F

DAY_CYCLE

B C K_TIME_ON

BCK_TIME_OFF

TIMELIMIT

BW_T0

simulation (g)

0. 001

0.1

0.

24

24

0.

0.

24

250

%delay before begin exposure (HOUR)
iTIME EXPOSURE STOP (HOUR)

%DELAY BEFORE BACKGROUND EXPOSURE	(HOUR)

%TIME OF BACKGROUND EXPOSURE STOP	(HOUR)
%SIMULATION LIMIT TIME (HOUR)

% Body weight at the beginning of	the

iEXPOSURE DOSE SCENARIOS (UG/KG)

iMSTOT	= 0.00005	% exposure dose ug/kg

iMSTOT	= 0.0001	%	exposure dose ug/kg

iMSTOT	= 0.001	%	exposure dose ug/kg

iMSTOT	=0.01	%	exposure dose ug/kg

This document is a draft for review purposes only and does not constitute Agency policy.

C-54 DRAFT—DO NOT CITE OR QUOTE


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54

%MSTOT
%MSTOT
MSTOT

= 0.1
= 1
= 10

% exposure dose ug/kg
% exposure dose ug/kg
% exposure dose ug/kg

C.2.4. Rat Gestational Model
C.2.4.1. Model Code

PROGRAM: 'Three Compartment PBPK Model for TCDD in Rat (Gestation)'

! Parameters were change May 16, 2002
! Come from {8MAI_CHR_PRE-EXP_GD}

! Come from {12 Mouse GDJfile

!{{IMPORTANT-IMPORTANT-IMPORTANT-IMPORTANT}}

! REDUCTION OF MOTHER AND FETUS COMPARTMENT
! 2M_R_TCDD_JULY2 0 02 ////(JULY 18,20 02)////
!TCDD_RED_4Species_2003_4	////(APR 8 ,2003)////

!TCDD_RED_4Species_2003_9	////(APR 17 ,2003)////

!TCDD_RED_4Species_2003_12	////(APR 17 ,2003)////

!APRIL 18 2003

!TCDD_4C_4SP_2 0 03	////(APR 18 ,2003)////

! was ''Gest 4 species l.csl'' but update July 2009

!DevTCDD4Species ICF afterKKfix v3 ratgest.csl
!RAT_GESTATIONAL_ICF_F083109.csl
!RAT_GESTATIONAL_ICF_F10 0 60 9.csl

!Legend/Legend/Legend/Legend/Legend/Legend/Legend/Legend/

!Legend for this PBPK model

IMating: control the tenure of exchange between fetus and
IMother and also control imitated tissue growth
!Control: WTFE, WFO, WPLA0, QPLAF,WTO
!(for rat, mouse, human, and monkey)

!Control transfer from mother to fetus or fetus to mother by TRANSTIME ON
!SWITCH_trans = 0 NO TRANSFER	~

!SWITCH_trans = 1 TRANSFER OCCURS
!Gest off = 1
!Gest on= 0 . 0
! These switches are also controlled by mating parameters

INITIAL !

!SIMULATION PARAMETERS ====
CONSTANT PARA_ZERO	= 1E-30

CONSTANT EXP_TIME_ON	=0.0

CONSTANT EXP_TIME_0FF	= 530

CONSTANT DAY_CYCLE	= 2 4.0

CONSTANT BCK_TIME_ON	=0.0
BEGINS (HOURS)

CONSTANT BCK_TIME_OFF	=0.0
(HOURS)

CONSTANT TRANSTIME_ON	= 144.0
AT GESTATIONAL DAY 6

TIME AT WHICH EXPOSURE BEGINS (HOURS)
TIME AT WHICH EXPOSURE ENDS (HOURS)
NUMBER OF HOURS BETWEEN DOSES (HOURS)
TIME AT WHICH BACKGROUND EXPOSURE

! TIME AT WHICH BACKGROUND EXPOSURE ENDS

!CONTROL TRANSFER FROM MOTHER TO FETUS

This document is a draft for review purposes only and does not constitute Agency policy.

C-55 DRAFT—DO NOT CITE OR QUOTE


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!UNIT CONVERSION
CONSTANT MW=322 ! MOLECULAR WEIGHT (NG/NMOL)
CONSTANT SERBLO =0.55
CONSTANT UNITCORR = 1000

!INTRAVENOUS SEQUENCE
constant IV_LACK	=0.0

constant IV PERIOD	=0.0

!PREGNANCY PARAMETER ====

CONSTANT MATTING	=0.0	!BEGINNING OF MATING (HOUR)

CONSTANT N_FETUS	= 10.0	!NUMBER OF FETUS PRESENT

!CONSTANT EXPOSURE CONTROL ===========

!ACUTE, SUBCHRONIC, CHRONIC EXPOSURE =====

!OR BACKGROUND EXPOSURE (IN THIS CASE 3 TIMES A DAY)===

CONSTANT MSTOTBCKGR	=0.0	! ORAL BACKGROUND EXPOSURE DOSE (UG/KG)

CONSTANT MSTOT	=0.0	! ORAL EXPOSURE DOSE (UG/KG)

!ORAL ABSORPTION
MSTOT NM = MSTOT/MW

! CONVERTS THE DOSE TO NMOL/G

!INTRAVENOUS ABSORPTION
CONSTANT DOSEIV	=0.0

DOSEIV_NM = DOSEIV/MW
CONSTANT DOSEIVLATE =0.0

DOSEIVNMlate = DOSEIVLATE/MW

! INJECTED DOSE (UG/KG)

! CONVERTS THE INJECTED DOSE TO NMOL/G

! INJECTED DOSE LATE (UG/KG)

!AMOUNT IN NMOL/G

!INITIAL GUESS OF	THE FREE CONCENTRATION IN THE LIGAND (COMPARTMENT
INDICATED BELOW)====

CONSTANT CFLLI0	=0.0 !LIVER (NMOL/ML)

CONSTANT CFLPLA0	=0.0 !PLACENTA (NMOL/ML)

!BINDING CAPACITY	(AhR) FOR NON LINEAR BINDING (COMPARTMENT INDICATED
BELOW) (NMOL/ML) ===

CONSTANT LIBMAX	= 3.5E-4 ! LIVER (NMOL/ML), WANG ET AL. 1997

CONSTANT PLABMAX	= 2.OE-4 !TEMPORARY PARAMETER

! PROTEIN AFFINITY	CONSTANTS (1A2 OR AhR, COMPARTMENT INDICATED BELOW)
(NMOL/ML)===

CONSTANT KDLI	= 1.0E-4 !LIVER (AhR) (NMOL/ML), WANG ET AL. 1997

CONSTANT KDLI2	= 4.OE-2 !LIVER (1A2) (NMOL/ML), EMOND ET AL. 2004

CONSTANT KDPLA	= 1.0E-4 !TEMPORARY PARAMETER; ASSUME IDENTICAL TO
KDLI (AhR)

!EXCRETION AND ABSORPTION CONSTANT
CONSTANT KST	= 0.36	! GASTRIC RATE CONSTANT (HR-1), WANG ET

AL. 1997

CONSTANT KABS	= 0.48	!INTESTINAL ABSORPTION CONSTANT (HR-1) ),

WANG ET AL. 1997

! ELIMINATION CONSTANTS
CONSTANT CLURI	=0.01	! URINARY CLEARANCE (ML/HR), EMOND ET

AL. 2004

This document is a draft for review purposes only and does not constitute Agency policy.

C-56 DRAFT—DO NOT CITE OR QUOTE


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! INTERSPECIES
CONSTANT kelv
CONSTANT (1/HOUR)

ELIMINATION VARIABLE

=0.15	! INTERSPECIES VARIABLE ELIMINATION

! CONSTANT TO DIVIDE THE ABSORPTION INTO LYMPHATIC AND PORTAL FRACTIONS
CONSTANT A	=0.7	! LYMPHATIC FRACTION, WANG ET AL. 1997

!PARTITION COEFFICIENTS

CONSTANT PF	= 100

CONSTANT PRE	=1.5
1997

CONSTANT PLI	=6.0

CONSTANT PPLA	=1.5
WANG ET AL. 1997

! ADIPOSE TISSUE/BLOOD, WANG ET AL. 1997
! REST OF THE BODY/BLOOD, WANG ET AL.

! LIVER/BLOOD, WANG ET AL. 19 97
! TEMPORARY PARAMETER NOT CONFIGURED,

!PARAMETER FOR INDUCTION OF CYP

CONSTANT PAS_INDUC	=1.0

CONSTANT CYP1A2_10UTZ	=1.6
1A2 (NMOL/ML)

CONSTANT CYP1A2_1A1	=1.6

CONSTANT CYP1A2_1EC5 0	=0.13
(NMOL/ML)

CONSTANT CYP1A2_1A2	=1.6

CONSTANT CYP1A2_1K0UT	=0.1

CONSTANT CYP1A2_1TAU	= 0.25

CONSTANT CYP1A2_1EMAX	= 600
(UNITLESS)

CONSTANT HILL	=0.6

BINDING EFFECT CONSTANT	(UNITLESS)

1A2, WANG ET AL. 1997

! INCLUDE INDUCTION? (1 = YES, 0 = NO)
! DEGRADATION CONCENTRATION CONSTANT OF

! BASAL CONCENTRATION OF 1A1 (NMOL/ML)
! DISSOCIATION CONSTANT TCDD-CYP1A2

BASAL CONCENTRATION OF 1A2 (NMOL/ML)

FIRST ORDER RATE OF DEGRADATION (H-l)
HOLDING TIME (H)

MAXIMUM INDUCTION OVER BASAL EFFECT

!HILL CONSTANT; COOPERATIVELY LIGAND

!DIFFUSIONAL PERMEABILITY FRACTION

CONSTANT PAFF
CONSTANT PAREF
AL. 1997
CONSTANT PALIF
CONSTANT PAPLAF

0.0910	!ADIPOSE (UNITLESS), WANG ET AL. 1997

0.0298	!REST OF THE BODY (UNITLESS), WANG ET

0.3500	!LIVER (UNITLESS), WANG ET AL. 1997

0.3	!TEMPORARY PARAMETER NOT CONFIGURED

!FRACTION OF TISSUE WEIGHT =========

CONSTANT WLI0	= 0.0360 !LIVER, WANG ET AL. 1997

!TISSUE BLOOD FLOW EXPRESSED AS A FRACTION OF CARDIAC OUTPUT
CONSTANT QFF	= 0.069 ! ADIPOSE TISSUE BLOOD FLOW FRACTION

(UNITLESS), WANG ET AL. 1997

CONSTANT QLIF	= 0.183 !LIVER (UNITLESS), WANG ET AL. 1997

!COMPARTMENT TISSUE BLOOD EXPRESSED AS A FRACTION OF THE TOTAL COMPARTMENT

VOLUME

CONSTANT WFB0
CONSTANT WREB0
CONSTANT WLIB0
CONSTANT WPLAB0

0.050	!ADIPOSE TISSUE, WANG ET AL. 1997

0.030	!REST OF THE BODY, WANG ET AL. 1997

0.266	!LIVER, WANG ET AL. 1997

0.500	!TEMPORARY PARAMETER NOT CONFIGURED

!EXPOSURE SCENARIO FOR UNIQUE OR REPETITIVE WEEKLY OR MONTHLY EXPOSURE
!NUMBER OF EXPOSURES PER WEEK
CONSTANT WEEK_LACK	=0.0	!DELAY BEFORE EXPOSURE ENDS (WEEK)

This document is a draft for review purposes only and does not constitute Agency policy.

C-57 DRAFT—DO NOT CITE OR QUOTE


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CONSTANT WEEK_PERIOD = 168	! NUMBER OF HOURS IN THE WEEK (HOURS)

CONSTANT WEEK_FINISH = 168	! TIME EXPOSURE ENDS (HOURS)

!NUMBER OF EXPOSURES PER MONTH

CONSTANT MONTH_LACK =0.0	!DELAY BEFORE EXPOSURE BEGINS (MONTHS)

!CONSTANT FOR BACKGROUND EXPOSURE===========

CONSTANT Day_LACK_BG =0.0	!DELAY BEFORE EXPOSURE BEGINS (HOURS)

CONSTANT Day_PERIOD_BG =24	!LENGTH OF EXPOSURE (HOURS)

!NUMBER OF EXPOSURES PER WEEK
CONSTANT WEEK_LACK_BG	=0.0	!DELAY BEFORE BACKGROUD EXPOSURE BEGINS

(WEEKS)

CONSTANT WEEK_PERIOD_BG = 168	!NUMBER OF HOURS IN THE WEEK (HOURS)

CONSTANT WEEK FINISH BG = 168	!TIME EXPOSURE ENDS (HOURS)

!INITIAL BODY WEIGHT
CONSTANT BW_T0	= 250

CONSTANT RAT10_RATF_MOUSEF =1.0
GESTATIONAL DAY 22

! WANG ET AL. 1997

!RATIO OF FETUS MOUSE/RAT AT

! COMPARTMENT LIPID EXPRESSED AS THE FRACTION OF TOTAL LIPID, POULIN ET AL
2000

CONSTANT F_TOTLIP	= 0.855

CONSTANT B_TOTLIP	= 0.0023

CONSTANT RE_TOTLIP	= 0.019
(UNITLESS)

CONSTANT LI_TOTLIP	= 0.060

CONSTANT PLA_TOTLIP	= 0.019

CONSTANT FETUS TOTLIP	= 0.019

! ADIPOSE TISSUE (UNITLESS)

! BLOOD (UNITLESS)

! REST OF THE BODY

! LIVER (UNITLESS)

END

! END OF THE INITIAL SECTION

DYNAMIC ! DYNAMIC SIMULATION SECTION

ALGORITHM IALG	=	2

CINTERVAL CINT	=	0.1

MAXTERVAL MAXT	=	1.0e+10

MINTERVAL MINT	=	1.0E-10

VARIABLE T	=	0.0

CONSTANT TIMELIMIT	=	100
CINTXY = CINT

GEAR METHOD

COMMUNICATION INTERVAL
MAXIMUM CALCULATION INTERVAL
MINIMUM CALCULATION INTERVAL

!SIMULATION LIMIT TIME (HOURS)

PFUNC

= CINT

!TIME CONVERSION
DAY	= T/24

WEEK	= T/168

MONTH	= T/730

YEAR	= T/87 60

TIME IN DAYS
TIME IN WEEKS
TIME IN MONTHS
TIME IN YEARS

DERIVATIVE ! PORTION OF CODE THAT SOLVES DIFFERENTIAL EQUATIONS

!CHRONIC OR SUBCHRONIC EXPOSURE SCENARIO =======

!NUMBER OF EXPOSURES PER DAY
DAY_LACK	= EXP_TIME_ON ! DELAY BEFORE EXPOSURE BEGINS (HOURS)

DAY_PERIOD	= DAY_CYCLE	! EXPOSURE PERIOD (HOURS)

DAY FINISH	= CINTXY	! LENGTH OF EXPOSURE (HOURS)

This document is a draft for review purposes only and does not constitute Agency policy.

C-58 DRAFT—DO NOT CITE OR QUOTE


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MONTH_PERIOD
MONTH FINISH

TIMELIMIT
EXP TIME OFF

! EXPOSURE PERIOD (MONTHS)
! LENGTH OF EXPOSURE (MONTHS)

!NUMBER OF EXPOSURES PER DAY AND MONTH

DAY_FINISH_BG
MONTH_LACK_BG
(MONTHS)

MONTH PERIOD BG

TIMELIMIT

CINTXY
BCK TIME ON

!DELAY BEFORE BACKGROUD EXPOSURE BEGINS

!BACKGROUND EXPOSURE (MONTHS)

MONTH_FINISH_BG = BCK_TIME_OFF !LENGTH OF BACKGROUND EXPOSURE (MONTHS)

!INTRAVENOUS LATE
IV_FINISH = CINTXY

B = 1-A ! FRACTION OF DIOXIN ABSORBED IN THE PORTAL FRACTION OF THE LIVER

!FETUS,VOLUME,FETUS,VOLUME,FETUS,VOLUME,FETUS,VOLUME,FETUS,VOLUME,FETUS,VOLUM
E

! FROM OFLAHERTY_19 92

RTESTGEST= T-MATTING
TESTGEST=DIM(RTESTGEST,0.0)

WTFER_RODENT= (2.3d-3*EXP(1.49d-2*(TESTGEST))+1.3d-2)*Gest_on
WTFER = (WTFER_RODENT*RATIO_RATF_MOUSEF*N_FETUS)

WTFE = DIM(WTFER,0.0)

FAT,VOLUME,FAT,VOLUME,FAT,VOLUME,FAT,VOLUME,FAT,VOLUME,FAT,VOLUME,FAT,VOLUME
! FAT GROWTH EXPRESSION LINEAR DURING PREGNANCY
! FROM O'FLAHERTY_19 92

WF0= (((9.66d-5*(TESTGEST))*gest_on)+0.069)

! PLACENTA,VOLUME, PLACENTA,VOLUME, PLACENTA,VOLUME, PLACENTA,VOLUME
! WPLA PLACENTA GROWTH EXPRESSION, SINGLE EXPONENTIAL WITH OFFSET
! FROM O'FLAHERTY_19 92 ! FOR EACH PUP

WPLA0N_RODENT = (0.6/(1+(5d+3*EXP(-0.0225*(TESTGEST)))))*N_FETUS
WPLA0R = (WPLA0N_RODENT/WT0)*Gest_on
WPLA0 = DIM(WPLA0R,0.0)

! PLACENTA,FLOW RATE, PLACENTA,FLOW RATE, PLACENTA,FLOW RATE, PLACENTA,FLOW
RATE

! QPLA PLACENTA GROWTH EXPRESSION, DOUBLE EXPONENTIAL WITH OFFSET
! FROM O'FLAHERTY_19 92

QPLARF = (1.67d-7 *exp(9.6d-3*(TESTGEST)) &

+1.6d-3*exp(7.9d-3*(TESTGEST))+0.0)*Gest_on*SWITCH_trans
QPLAF=DIM(QPLARF,0.0)	!FRACTION OF FLOW RATE IN PLACENTA

! GESTATION CONTROL
IF (T.LT.MATTING) THEN
Gest off = 1.0
Gest on= 0 . 0

ELSE

Gest off = 0.0

This document is a draft for review purposes only and does not constitute Agency policy.

C-59 DRAFT—DO NOT CITE OR QUOTE


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Gest on =1.0
END IF

MOTHER BODY WEIGHT GROWTH EQUATION========

MODIFICATION TO ADAPT THIS MODEL AT HUMAN MODEL

BECAUSE LINEAR DESCRIPTION IS NOT GOOD ENOUGH FOR MOTHER GROWTH
MOTHER BODY WEIGHT GROWTH

PARAMETER (BW_RMN = 1.0E-30)

WT0= BW_T0 *(1+(0.41*T)/(1402.5+T+BW_RMN))

! VARIABILITY OF REST OF THE BODY DEPENDS ON OTHER ORGANS
WRE0 = (0.91 - (WLIB0*WLI0 + WFB0*WF0 +WPLAB0*WPLA0 + WLI0 + WF0 +
WPLA0))/(1+WREB0) ! REST OF THE BODY FRACTION; UPDATED FOR EPA ASSESSMENT
QREF = 1-(QFF+QLIF+QPLAF)	!REST OF BODY BLOOD FLOW RATE (ML/HR)

QTTQF = QFF+QREF+QLIF+QPLAF	! SUM MUST EQUAL 1

! COMPARTMENT VOLUME (ML OR G)
WF = WF0 * WTO
WRE = WRE0 * WTO
WLI = WLI0 * WTO
WPLA= WPLA0* WTO

ADIPOSE TISSUE
REST OF THE BODY
LIVER
PLACENTA

! COMPARTMENT TISSUE BLOOD	(ML OR G)

WFB = WFB0 * WF	!

WREB = WREB0 * WRE	!

WLIB = WLIB0 * WLI	!

WPLAB = WPLAB0* WPLA	!

ADIPOSE TISSUE
REST OF THE BODY
LIVER
PLACANTA

! CARDIAC OUTPUT FOR THE GIVEN BODY WEIGHT (ML/H) =========

!QC= QCCAR* 60*(WTO/1000.0)**0.75
CONSTANT QCC=18684.0	! EQUIVALENT TO 311.4 * 60

QC= QCC*(WTO/UNITCORR)**0.75

!COMPARTMENT BLOOD FLOW RATE (ML/HR)

QF = QFF*QC	!ADIPOSE TISSUE BLOOD FLOW RATE

QLI = QLIF*QC	!LIVER TISSUE BLOOD FLOW RATE

QRE = QREF*QC	!REST OF THE BODY BLOOD FLOW RATE

QPLA = QPLAF*QC	!PLACENTA TISSUE BLOOD FLOW RATE

QTTQ = QF+QRE+QLI+QPLA !TOTAL FLOW RATE

!PERMEABILITY ORGAN FLOW (ML/HR)
PAF = PAFF*QF
PARE = PAREF*QRE
PALI = PALIF*QLI
PAPLA = PAPLAF*QPLA

ADIPOSE TISSUE
REST OF THE BODY
LIVER TISSUE
PLACENTA

ABSORPTION SECTION
ORAL

INTRAPERITONEAL
INTRAVENOUS

!REPETITIVE ORAL BACKGROUND EXPOSURE SCENARIO

This document is a draft for review purposes only and does not constitute Agency policy.

C-60 DRAFT—DO NOT CITE OR QUOTE


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MSTOT_NMBCKGR = MSTOTBCKGR/MW	! CONVERTS THE BACKGROUND DOSE TO NMOL/G

MSTTBCKGR =MSTOT_NMBCKGR *WT0

DAY_EX P O S U RE_B G = PULSE(DAY_LACK_BG,DAY_PERIOD_BG,DAY_FINISH_BG)
WEEK_EXPOSURE_BG = PULSE(WEEK_LACK_BG,WEEK_PERIOD_BG,WEEK_FINISH_BG)
MONTH_EXPOSURE_BG = PULSE(MONTH_LACK_BG,MONTH_PERIOD_BG,MONTH_FINISH_BG)

MSTTCH_BG = (DAY_EXPOSURE_BG*WEEK_EXPOSURE_BG*MONTH_EXPOSURE_BG)*MSTTBCKGR
MSTTFR_BG = MSTTBCKGR/CINT

CYCLE_BG =DAY_EXPOSURE_BG*WEEK_EXPOSURE_BG*MONTH_EXPOSURE_BG

! CONDITIONAL ORAL EXPOSURE (BACKGROUND EXPOSURE)

IF (MSTTCH_BG.EQ.MSTTBCKGR) THEN
ABSMSTT_GB= MSTTFR_BG

ELSE

ABSMSTT_GB =0.0
END IF

CYCLETOTBG=INTEG(CYCLE_BG,0.0)

!REPETITIVE ORAL EXPOSURE SCENARIO

MSTT= MSTOT_NM * WTO	!AMOUNT IN NMOL

DAY_EXPOSURE = PULSE(DAY_LACK,DAY_PERIOD,DAY_FINISH)

WEEK_EXPOSURE = PULSE(WEEK_LACK,WEEK_PERIOD,WEEK_FINISH)

MONTH_EXPOSURE = PULSE(MONTH_LACK,MONTH_PERIOD,MONTH_FINISH)

MSTTCH = (DAY_EXPOSURE*WEEK_EXPOSURE*MONTH_EXPOSURE)*MSTT
MSTTFR = MSTT/CINT

CYCLE = DAY_EXPOSURE*WEEK_EXPOSURE*MONTH_EXPOSURE

SUMEXPEVENT= INTEG (CYCLE,0.0) !NUMBER OF CYCLE GENERATE DURING SIMULATION

! CONDITIONAL ORAL EXPOSURE
IF (MSTTCH.EQ.MSTT) THEN

ABSMSTT= MSTTFR
ELSE

ABSMSTT =0.0
END IF

CYCLETOT=INTEG(CYCLE, 0.0)

! MASS CHANGE IN THE LUMEN
RMSTT= -(KST+KABS)*MST +ABSMSTT +ABSMSTT_GB ! RATE OF CHANGE (NMOL/H)

MST = INTEG(RMSTT,0.0)	!AMOUNT REMAINING IN DUODENUM

(NMOL)

! ABSORPTION IN LYMPH CIRCULATION
LYRMLUM = KABS*MST*A
LYMLUM = INTEG(LYRMLUM,0.0)

! ABSORPTION IN PORTAL CIRCULATION

This document is a draft for review purposes only and does not constitute Agency policy.

C-61 DRAFT—DO NOT CITE OR QUOTE


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LIRMLUM = KABS*MST*B
LIMLUM = INTEG(LIRMLUM,0.0)

! 	IV EXPOSURE 	

IV= DOSEIV_NM * WTO !AMOUNT IN NMOL
IVR= IV/PFUNC ! RATE FOR IV INFUSION IN BLOOD
EXPIV= IVR * (1.0-STEP(PFUNC))

IVDOSE = integ(EXPIV,0.0)

!	IV LATE IN THE CYCLE

! MODIFICATION ON January 13 2004
IV_RlateR = DOSEIVNMlate*WT0

IV_EXPOSURE=PULSE(IV_LACK,IV_PERIOD,IV_FINISH)

IV_lateT = IV_EXPOSURE *IV_RlateR
IV_late = IV_lateT/CINT

SUMEXPEVENTIV= integ (IV_EXPOSURE,0.0) !NUMBER OF CYCLE GENERATE DURING
SIMULATION

!SYSTEMIC CONCENTRATION OF TCDD

! MODIFICATION ON OCTOBER 6, 2009
CB= (QF*CFB+QRE*CREB+QLI*CLIB+EXPIV+LYRMLUM+QPLA*CPLAB+IV_late)/(QC+CLURI) !
CA = CB ! CONCENTRATION (NMOL/ML)

!URINARY EXCRETION BY KIDNEY
! MODIFICATION ON OCTOBER 6, 2009
RAURI = CLURI *CB

AURI = INTEG(RAURI,0.0)

!UNIT CONVERSION POST SIMULATION
CBSNGKGLIADJ=(CB*MW*UNITCORR*(1.0/B_TOTLIP)*(1.0/SERBLO))![NG of TCDD
Serum/Kg OF LIPIP]

AUCBS_NGKGLIADJ=integ(CBSNGKGLIADJ,0.0)

PRCT_B = (CB/(MSTT+1E-30))*100.0 !PERCENT OF ORAL DOSE IN BLOOD
PRCT_BIV = (CB/(IV_RlateR+lE-3 0))*100.0 ! PERCENT OF IV DOSE IN BLOOD
CBNGKG= CB*MW*UNITCORR

!ADIPOSE COMPARTMENT
! TISSUE BLOOD COMPARTMENT
RAFB= QF*(CA-CFB)-PAF*(CFB-CF/PF)
AFB = INTEG(RAFB,0.0)
CFB = AFB/WFB
! TISSUE COMPARTMENT
RAF = PAF*(CFB-CF/PF)
AF = INTEG(RAF,0.0)

CF = AF/WF

!(NMOL/H)
!(NMOL)

(NMOL/ML)

!(NMOL/H)
!(NMOL)
!(NM/ML)

This document is a draft for review purposes only and does not constitute Agency policy.

C-62 DRAFT—DO NOT CITE OR QUOTE


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!UNIT CONVERSION POST SIMULATION
CFTOTAL= (AF + AFB)/(WF + WFB) ! TOTAL CONCENTRATION IN NMOL/ML
CFTFREE = CFB + CF !TOTAL FREE CONCENTRATION IN FAT (NM/ML)

PRCT_F = (CFTOTAL/(MSTT+1E-30))*100.0 ! PERCENT OF ORAL DOSE IN FAT
PRCT_FIV = (CFTOTAL/(IV_RlateR+lE-30))*100.0 ! PERCENT OF IV DOSE IN FAT
CFNGKG=CFTOTAL*MW*UNITCORR ! FAT CONCENTRATION NG/KG
AUCF_NGKGH=integ(CFNGKG, 0.0)

!REST OF THE BODY COMPARTMENT
RAREB= QRE *(CA-CREB)-PARE*(CREB-CRE/PRE) !(NMOL/H)

AREB = INTEG(RAREB,0.0)	!(NMOL)

CREB = AREB/WREB	!(NMOL/H)
!TISSUE COMPARTMENT

RARE = PARE*(CREB - CRE/PRE)	!(NMOL/H)

ARE = INTEG(RARE,0.0)	!(NMOL)

CRE = ARE/WRE	!(NMOL/ML)

!UNIT CONVERSION POST SIMULATION
CRETOTAL= (ARE + AREB)/(WRE + WREB)	! TOTAL CONCENTRATION IN

NMOL/ML

PRCT_RE = (CRETOTAL/(MSTT+1E-30))*100.0 ! PERCENT OF ORAL DOSE IN REST OF
THE BODY

PRCT_REIV = (CRETOTAL/(IV_RlateR+lE-30))*100.0 !PERCENT OF IV DOSE IN
REST OF THE BODY

CRENGKG=CRETOTAL*MW*UNITCORR ! REST OF THE BODY CONCENTRATION IN NG/KG

!LIVER COMPARTMENT
!TISSUE BLOOD COMPARTMENT
RALIB = QLI*(CA-CLIB)-PALI*(CLIB-CFLLIR)+LIRMLUM !

ALIB = INTEG(RALIB,0.0)	!(NMOL)

CLIB = ALIB/WLIB	!(NMOL/ML)

!TISSUE COMPARTMENT
RALI = PALI*(CLIB - CFLLIR)-REXCLI	! (NMOL/HR)

ALI = INTEG(RALI,0.0)	!(NMOL)

CLI = ALI/WLI	!(NMOL/ML)

!FREE TCDD CONCENTRATION IN LIVER COMPARTMENT
PARAMETER (LIVER_1RMN = 1.0E-30)

CFLLI= IMPLC(CLI-(CFLLIR*PLI+(LIBMAX*CFLLIR/(KDLI+CFLLIR &
+LIVER_1RMN))+((CYP1A2_103*CFLLIR/(KDLI2 + CFLLIR &
+LIVER_1RMN)*PAS_INDUC)))-CFLLI,CFLLI0)

CFLLIR=DIM(CFLLI,0.0) ! FREE CONCENTRATION IN LIVER

CBNDLI= LIBMAX*CFLLIR/(KDLI+CFLLIR+LIVER_1RMN) !BOUND CONCENTRATION

!VARIABLE ELIMINATION BASED ON THE CYP1A2
KBILE_LI_T =((CYP1A2_10UT-CYP1A2_1A2)/CYP1A2_1A2)*Kelv ! INDUCED BILIARY
EXCRETION RATE CONSTANT IN LIVER

REXCLI = KBILE_LI_T*CFLLIR*WLI ! DOSE-DEPENDENT BILIARY EXCRETION RATE
EXCLI = INTEG(REXCLI,0.0)

!UNIT CONVERSION POST SIMULATION

CLITOTAL= (ALI + ALIB)/(WLI + WLIB) ! TOTAL CONCENTRATION IN NMOL/ML

PRCT_LI = (CLITOTAL/(MSTT+1E-30))*100

PRCT_LIIV = (CLITOTAL/(IV_RlateR+lE-30))*100.0

This document is a draft for review purposes only and does not constitute Agency policy.

C-63 DRAFT—DO NOT CITE OR QUOTE


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Rec_occ= CFLLIR/(KDLI+CFLLIR)

CLINGKG=CLITOTAL*MW*UNITCORR ! LIVER CONCENTRATION NG/KG

AUCLI_NGKGH=INTEG(CLINGKG, 0.0)

CBNDLINGKG = CBNDLI*MW*UNITCORR

AUCBNDLI NGKGH =INTEG(CBNDLINGKG,0.0)

!CHEMICAL IN CYP450 (1A2) COMPARTMENT
CYP1A2 1KINP = CYP1A2 1KOUT* CYP1A2 10UTZ

! MODIFICATION ON OCTOBER 6, 2009
CYP1A2_10UT =INTEG(CYP1A2_1KINP * (1.0 + CYP1A2_1EMAX *(CBNDLI+1.0e-30)**HILL
&

/(CYP1A2_1EC50**HILL + (CBNDLI+1.0e-30)**HILL)) &
- CYP1A2_1K0UT*CYP1A2_10UT, CYP1A2_10UTZ)

! EQUATIONS INCORPORATING DELAY OF CYP1A2 PRODUCTION (NOT USED IN
SIMULATIONS)

CYP1A2_1R02 = (CYP1A2_10UT - CYP1A2_102)/ CYP1A2_1TAU
CYP1A2_102 =INTEG(CYP1A2_1R02, CYP1A2_1A1)

CYP1A2_1R03 = (CYP1A2_102 - CYP1A2_103)/ CYP1A2_1TAU
CYP1A2_103 =INTEG(CYP1A2_1R03, CYP1A2_1A2)

! TRANSFER OF DIOXIN FROM PLACENTA TO FETUS
! FETAL EXPOSURE ONLY DURING EXPOSURE

IF (T.LT.TRANSTIME_ON) THEN

SWITCH_trans =0.0
ELSE

SWITCH_trans =1.0
END IF

!TRANSFER OF DIOXIN FROM PLACENTA TO FETUS
! MODIFICATION 26 SEPTEMBER 2003

CONSTANT PFETUS= 4.0 !

CONSTANT CLPLA_FET =0.17 !

RAMPF = (CLPLA_FET*CPLA) *SWITCH_trans
AMPF=INTEG(RAMPF,0.0)

!TRANSFER OF DIOXIN FROM FETUS TO PLACENTA
RAFPM = (CLPLA_FET*CFETUS_v)* SWITCH_trans !

AFPM = INTEG(RAFPM,0.0)

! TCDD IN PLACENTA (MOTHER) COMPARTMENT
RAPLAB= QPLAMCA - CPLAB) - PAPLA* (CPLAB -CFLPLAR)

APLAB = INTEG(RAPLAB,0.0)

CPLAB = APLAB/(WPLAB+1E-30)

RAPLA = PAPLA*(CPLAB-CFLPLAR)-RAMPF + RAFPM
APLA = INTEG(RAPLA,0.0)

CPLA = APLA/(WPLA+le-30)

! NMOL/H)
! (NMOL)
! (NMOL/ML)
! (NMOL/H)

! (NMOL)
! (NMOL/ML)

This document is a draft for review purposes only and does not constitute Agency policy.

C-64 DRAFT—DO NOT CITE OR QUOTE


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PARAMETER (PARA_ZERO = 1.0E-30)

CFLPLA= IMPLC(CPLA-(CFLPLAR*PPLA +(PLABMAX*CFLPLAR/(KDPLA&

+CFLPLAR+PARA_ZERO)))-CFLPLA,CFLPLAO)

CFLPLAR=DIM(CFLPLA, 0.0)

!UNIT CONVERSION POST SIMULATION
CPLATOTAL= (APLA + APLAB)/((WPLA + WPLAB)+le-30)! TOTAL CONCENTRATION IN
NMOL/ML

PRCT_PLA = (CPLATOTAL/(MSTT+1E-30))*100

PRCT PLAIV = (CPLATOTAL/(IV RlateR+lE-30) )* 100

!FETUS COMPARTMENT
RAFETUS= RAMPF-RAFPM

AFETUS=INTEG(RAFETUS,0.0)

CFETUS=AFETUS/(WTFE+1E-30)

CFETOTAL= CFETUS
CFETUS_v = CFETUS/PFETUS

! UNIT CONVERSION POST SIMULATION
CFETUSNGKG = CFETUS*MW*UNITCORR	!(NG/KG)

AU C_FEN GKGH = INTEG(CFETUSNGKG,0.0)

PRCT_FE = (CFETOTAL/(MSTT+1E-30))*100
PRCT FEIV = (CFETOTAL/(IV RlateR+lE-30) )* 100

! 	CONTROL MASS BALANCE	

BDOSE= IVDOSE +LYMLUM+LIMLUM

BMASSE = EXCLI+AURI+AFB+AF+AREB+ARE+ALIB+ALI+APLA+APLAB+AFETUS
BDIFF = BDOSE-BMASSE

!BODY BURDEN (NG)

BODY_BURDEN = AFB +AF+ARE B +ARE +ALIB+ALI+AP LA+AP LAB !

BBFETUSNG	= AFETUS*MW*UNITCORR ! UNIT (NG)

! BODY BURDEN IN TERMS OF CONCENTRATION (NG/KG)

BBNGKG =( ( (AFB+AF+AREB+ARE+ALIB+ALI+AP LA+AP LAB)/WTO)*MW*UNITCORR) !
AUC BBNGKGH=INTEG(BBNGKG,0.0)

! 	COMMAND OF THE END OF SIMULATION	

TERMT (T.GE. TimeLimit, 'Time limit has been reached.')
END ! END OF THE DERIVATIVE SECTION
END ! END OF THE DYNAMIC SECTION
END ! END OF THE PROGRAM

C.2.4.2. Input Files
C.2.4.2.1. Bell et al. (2007).

%clear variable
output 0clear

prepare 0clear T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CFETUSNGKG AUCLI_NGKGH
AUCF_NGKGH AUCBS_NGKGLIADJ AUC_BBNGKGH AUC_FENGKGH CBNDLINGKG AUCBNDLI_NGKGH
CBNGKG AUC CBNGKGH

This document is a draft for review purposes only and does not constitute Agency policy.

C-65 DRAFT—DO NOT CITE OR QUOTE


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%output 0nciout=l T BBFETUSNG %AJS turned off 9/21/09
%Bell et al. 2007 (rat species)

%protocol: daily dietary dose for 12 weeks followed by a two-week mating
time and 21-day gestation period
%DevTCDD4Species.csl

%RAT_GESTATIONAL_ICF_F083109.csl (now 09-11-09)

%dose levels: 0.0024, 0.008, 0.046 ug/kg/d with 0.00003 ug/kg/d background
%dose levels: 2.4, 8, 46 ng/kg/d with 0.03 ng/kg/day background

i;EXPOSURES SCENARIOS

MAXT
CINT

EXP_TIME_ON
EXP TIME OFF

0. 01

0.1

0

2856

exposure + 2 weeks for mating + 21

DAY_CYCLE

B C K_TIME_ON

BCK_TIME_OFF

IV_LACK

IV_PERIOD

TIMELIMIT

BW_T0

MATTING

TRANSTIME_ON

N FETUS

24
0.

2856.

505.

505.

2856

85

2352
2496
10

iEXPOSURE DOSE SCENARIOS (UG/KG)
MSTOT	= 0.00243

delay before begin exposure (HOUR)

TIME EXPOSURE STOP (HOUR) 12 weeks
days gestation with exposure

DELAY BEFORE BACKGROUND EXPOSURE (HOUR)
% TIME OF BACKGROUND EXPOSURE STOP (HOUR)

SIMULATION LIMIT TIME (HOUR)

BEGINNING MATING (HOUR)

SHOULD BE MATING TIME + 6 DAYS(144 HOURS)

iMSTOT

iMSTOT = 0.0461

% ORAL EXPOSURE DOSE (UG/KG)
= 0.008	% ORAL EXPOSURE DOSE (UG/KG)

% ORAL EXPOSURE DOSE (UG/KG)

C.2.4.2.2. Haavisto et al. (2006).

%clear variable
output 0clear

prepare 0clear T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CFETUSNGKG AUCLI_NGKGH
AUCF_NGKGH AUCBS_NGKGLIADJ AUC_BBNGKGH AUC_FENGKGH CBNDLINGKG AUCBNDLI_NGKGH
CBNGKG AUC CBNGKGH

%Haavisto et al. 2006

%protocol: single dose on GD 13

%dose levels: 0.04, 0.2, and 1.0 ug/kg on GD 13

%dose levels: 40, 200, and 1,000 ng/kg on GD 13

MAXT = 0.001
CINT =0.1

%EXPOSURES SCENARIOS
EXP_TIME_ON	=312

EX P_TIME_0 FF	= 335

DAY CYCLE	=24

TIME AT WHICH EXPOSURE BEGINS (HOUR)
TIME AT WHICH EXPOSURE ENDS (HOUR)

This document is a draft for review purposes only and does not constitute Agency policy.

C-66 DRAFT—DO NOT CITE OR QUOTE


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B C K_TIME_ON
BEGINS (HOUR)
BCK_TIME_OFF
ENDS (HOUR)
IV_LACK
IV_PERIOD
TIMELIMIT
BW_T0
MATTING
TRANSTIME_ON
HOURS)

N FETUS

= 0.

= 0.

= 505
= 505
= 336
= 190
= 0.
= 144.

= 10

iEXPOSURE DOSE	SCENARIOS (UG/KG)

%MSTOT	=0.04

%MSTOT	= 0.2

MSTOT	=1.0

TIME AT WHICH BACKGROUND EXPOSURE
TIME AT WHICH BACKGROUND EXPOSURE

SIMULATION LIMIT TIME (HOUR)

BEGINNING MATTING (HOUR)

SHOULD BE MATTING TIME + 6 DAYS(144

i ORAL EXPOSURE DOSE (UG/KG)
i ORAL EXPOSURE DOSE (UG/KG)
ORAL EXPOSURE DOSE (UG/KG)

C.2.4.2.3. Hojo et al (2002).

%clear variable
output 0clear

prepare 0clear T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CFETUSNGKG AUCLI_NGKGH
AUCF_NGKGH AUCBS_NGKGLIADJ AUC_BBNGKGH AUC_FENGKGH CBNDLINGKG AUCBNDLI_NGKGH
CBNGKG AUC_CBNGKGH
%Hojo et al. 2002

%protocol: single oral dose at GD8
%DevTCDD4Species . csl

%RAT_GESTATIONAL_ICF_F083109.csl (now 09-11-09)
%RAT_GESTATIONAL_ICF_F092009.csl (now 09-21-09
%dose levels: 0.02 0.06, 0.18 ug/kg at GD8
%dose levels: 20, 60, 180 ng/kg at GD8

% author provided the body weight for each group at the beginning og
gestation (g)

%20 ng/kg BW = 271g
%60 ng/kg BW = 275g
%180 ng/kg BW = 262g

%EXPOSURES SCENARIOS
MAXT= 0.001
CINT =0.1

EXP_TIME_ON	=192

EX P_TIME_0 FF	= 216

DAY_CYCLE	=24

B C K_T I ME_ON	= 0.

BCK_TIME_OFF	= 0.

IV_LACK	= 5 05

IV_PERIOD	= 505

TIMELIMIT	= 216

% BW_T0	= 190

MATTING	= 0.

TRANSTIME_ON	= 144.
HOURS)

N FETUS	=10

delay before begin exposure (HOUR)

TIME EXPOSURE STOP (HOUR)

DELAY BEFORE BACGROUND EXPOSURE (HOUR)
TIME OF BACKGROUND EXPOSURE STOP (HOUR)

SIMULATION LIMIT TIME (HOUR)

BEGINNING MATTING (HOUR)

SHOULD BE MATTING TIME + 6 DAYS(144

This document is a draft for review purposes only and does not constitute Agency policy.

C-67 DRAFT—DO NOT CITE OR QUOTE


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%EXPOSURE DOSE SCENARIOS (UG/KG)

%MSTOT
% BW_T 0

%MSTOT
% BW_T 0

MSTOT
BW TO

= 0. 02
= 275

= 0. 06
= 262

= 0. 18
= 278

% ORAL EXPOSURE DOSE (UG/KG)
% 20 ng/kg BW = 271g

% ORAL EXPOSURE DOSE (UG/KG)
%60 ng/kg BW = 275g

5 ORAL EXPOSURE DOSE (UG/KG)
i;180 ng/kg BW = 262g

C.2.4.2.4. Ikeda et al. (2005).

%clear variable
output 0clear

prepare 0clear T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CFETUSNGKG AUCLI_NGKGH
AUCF_NGKGH AUCBS_NGKGLIADJ AUC_BBNGKGH AUC_FENGKGH CBNDLINGKG AUCBNDLI_NGKGH

%Ikeda et al. 2005 (rat species)

%protocol: loading dose of 400 ng/kg followed by weekly maintenance doses of
80 ng/kg for 6 weeks,

%dose levels: 0.4 ug/kg/day followed by weekly 0.08 ug/kg/day
%dose levels: 400 ng/kg/day followed by weekly 80 ng/kg/day

%EXPOSURES SCENARIOS
MAXT	=. 1

CINT	=0.1 ?

EXP_TIME_ON	= 0

EX P_T I ME_0 F F	= 1008

MATING (2 WEEKS) + MATING

DAY_CYCLE
B C K_TIME_ON
(HOUR)

BCK_TIME_OFF
(HOUR)

IV_LACK
IV_PERIOD
TIMELIMIT
BW_T0
MATTING
TRANSTIME_ON
N FETUS

= 168
= 0.

= 167.

= 505.
= 505.
= 1008
= 250
= 504
= 648
= 10

% TIME AT WHICH EXPOSURE
% TIME AT WHICH EXPOSURE
(1 WEEK) + GESTATION (3 WEEKS)
% WEEKLY CYCLE
% TIME AT WHICH BACKGROUND

BEGINS (HOUR)

ENDS (HOUR); PRE-

EXPOSURE BEGINS

TIME AT WHICH BACKGROUND EXPOSURE ENDS

b SIMULATION TIME LIMIT (HOUR)

BEGINNING OF MATING (HOUR)

SHOULD BE MATING TIME + 6 DAYS (144 HOURS)

iEXPOSURE DOSE SCENARIOS (UG/KG)
MSTOT	=0.08

MSTOTBCKGR	=0.32

5 ORAL EXPOSURE DOSE IN UG/KG
BACKGROUND EXPOSURE IN UG/KG

C.2.4.2.5. Kattainen et al. (2001).

%clear variable
output 0clear

prepare 0clear T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CFETUSNGKG AUCLI_NGKGH
AUCF_NGKGH AUCBS_NGKGLIADJ AUC_BBNGKGH AUC_FENGKGH CBNDLINGKG AUCBNDLI_NGKGH
CBNGKG AUC CBNGKGH

This document is a draft for review purposes only and does not constitute Agency policy.

C-68 DRAFT—DO NOT CITE OR QUOTE


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%Kattainen et al. 2001
%protocol: single gavage at GD15
%DevTCDD4Species . csl

%RAT_GESTATIONAL_ICF_F083109.csl (now 09-11-09)
%dose levels: 0.03 0.1, 0.3, 1 ug/kg at GD15
%dose levels: 30, 100 300, 1000 ng/kg at GD15

MAXT=0.001
CINT =0.1

%EXPOSURES SCENARIOS

EXP_TIME_ON	= 336

EX P_TIME_0 FF	= 360

DAY_CYCLE	=24

B C K_T I ME_ON	= 0.
(HOUR)

BCK_TIME_OFF	= 0.
(HOUR)

IV_LACK	= 5 05

IV_PERIOD	= 505

TIMELIMIT	= 360

BW_T0	= 190

MATTING	= 0.

TRANSTIME_ON	= 144.
HOURS)

N FETUS	=10

delay before begin exposure (HOUR)
TIME EXPOSURE STOP (HOUR)

DELAY BEFORE BACKGROUND EXPOSURE

TIME OF BACKGROUND EXPOSURE STOP

SIMULATION LIMIT TIME (HOUR)

BEGINNING MATTING (HOUR)

SHOULD BE MATTING TIME + 6 DAYS(144

•;EXPOSURE	DOSE SCENARIOS (UG/KG)

%MSTOT	=0.03

%MSTOT	=0.1

%MSTOT	=0.3

MSTOT	= 1

ORAL EXPOSURE DOSE	(UG/KG)

ORAL EXPOSURE DOSE	(UG/KG)

ORAL EXPOSURE DOSE	(UG/KG)

ORAL EXPOSURE DOSE	(UG/KG

C.2.4.2.6. Markowski et al. (2001).

%clear variable
output 0clear

prepare 0clear T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CFETUSNGKG AUCLI_NGKGH
AUCF_NGKGH AUCBS_NGKGLIADJ AUC_BBNGKGH AUC_FENGKGH CBNDLINGKG AUCBNDLI_NGKGH
CBNGKG AUC CBNGKGH

%Markowski et al. 2001
%protocol: single gavage at GD18
%DevTCDD4Species . csl

%RAT_GESTATIONAL_ICF_F083109 . csl (now 09-11-09)
%dose levels: 0.02 0.06, 0.18 ug/kg at GD18
%dose levels: 20, 60, 180 ng/kg at GD18

•;EXPOSURES SCENARIOS
MAXT=0 . 0001
CINT =0.1

EXP_TIME_ON	= 4 08

EX P_T I ME_0 F F	=4 32

DAY_CYCLE	=24

B C K_T I ME_ON	= 0.

BCK TIME OFF	= 0.

delay before begin exposure (HOUR)

TIME EXPOSURE STOP (HOUR)

DELAY BEFORE BACKGROUND EXPOSURE (HOUR)
TIME OF BACKGROUND EXPOSURE STOP (HOUR)

This document is a draft for review purposes only and does not constitute Agency policy.

C-69 DRAFT—DO NOT CITE OR QUOTE


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IV_LACK	= 5 05

IV_PERIOD	= 505

TIMELIMIT	= 432

BW_T0	= 190

MATTING	= 0.
TRANSTIME_ON = 144.

N FETUS	=10

% SIMULATION LIMIT

% BEGINNING MATING
% SHOULD BE MATING

TIME (HOUR)

(HOUR)

TIME + 6 DAYS(144 HOURS)

iEXPOSURE DOSE SCENARIOS

%MSTOT
%MSTOT
MSTOT

= 0. 02
= 0. 06
= 0. 18

(UG/KG)

% ORAL EXPOSURE DOSE (UG/KG)
% ORAL EXPOSURE DOSE (UG/KG)
% ORAL EXPOSURE DOSE (UG/KG)

C.2.4.2.7. Miettinen et al. (2006).

%clear variable
output 0clear

prepare 0clear T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CFETUSNGKG AUCLI_NGKGH
AUCF_NGKGH AUCBS_NGKGLIADJ AUC_BBNGKGH AUC_FENGKGH CBNDLINGKG AUCBNDLI_NGKGH
CBNGKG AUC CBNGKGH

%Miettinen et al. 2006

%protocol: single oral dose at GD15

%DevTCDD4Species . csl

%RAT_GESTATIONAL_ICF_F083109 . csl (now 09-11-09)
%dose levels: 0.03 0.1, 0.3, 1 ug/kg at GD15
%dose levels: 30, 100, 300, 1000 ng/kg at GD15

MAXT=0.01

CINT =0.1	%

%EXPOSURES SCENARIOS

EXP TIME ON

=

336

O
O

delay before begin exposure (HOUR)

EXP TIME OFF

=

360

O
O

TIME EXPOSURE STOP (HOUR)

DAY CYCLE

=

24





BCK TIME ON

=

0.

O
O

DELAY BEFORE BACKGROUND EXPOSURE (HOUR)

BCK TIME OFF

=

0.

O
O

TIME OF BACKGROUND EXPOSURE STOP (HOUR)

IV LACK

=

505





IV PERIOD

=

505





TIMELIMIT

=

360

O
O

SIMULATION LIMIT TIME (HOUR)

BW TO

=

180





MATTING

=

0.

O
O

BEGINNING MATING (HOUR)

TRANSTIME ON

=

144 .

O
O

SHOULD BE MATING TIME + 6 DAYS(144 HOURS)

N FETUS

=

10





iEXPOSURE DOSE SCENARIOS	(UG/KG)

%MSTOT =0.03	% ORAL EXPOSURE DOSE (UG/KG)

%MSTOT =0.1	% ORAL EXPOSURE DOSE (UG/KG)

%MSTOT =0.3	% ORAL EXPOSURE DOSE (UG/KG)

MSTOT =1	% ORAL EXPOSURE DOSE (UG/KG)

C.2.4.2.8. Nohara et al. (2000).

%clear variable
output 0clear

This document is a draft for review purposes only and does not constitute Agency policy.

C-70 DRAFT—DO NOT CITE OR QUOTE


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prepare 0clear T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CFETUSNGKG AUCLI_NGKGH
AUCF_NGKGH AUCBS_NGKGLIADJ AUC_BBNGKGH AUC_FENGKGH CBNDLINGKG AUCBNDLI_NGKGH
CBNGKG AUC_CBNGKGH

%Nohara et al. 2000

%protocol: single gavage at GD15

%DevTCDD4Species.csl

%RAT_GESTATIONAL_ICF_F083109.csl (now 09-11-09)

%dose levels: 0.0125, 0.050, 0.2, or 0.8 ug TCDD:kg body weight by gavage on
GD15 .

%dose levels: 12.5, 50, 200, or 800 ng TCDD:kg body weight by gavage on GD15.
MAXT=0.01

CINT =0.1	%

%EXPOSURES

SCENARIOS





EXP TIME ON

=

336

O
O

delay before begin exposure (HOUR)

EXP TIME OFF

=

360

O
O

TIME EXPOSURE STOP (HOUR)

DAY CYCLE

=

24





BCK TIME ON

=

0.

O
O

DELAY BEFORE BACKGROUND EXPOSURE (HOUR)

BCK TIME OFF

=

0.

O
O

TIME OF BACKGROUND EXPOSURE STOP (HOUR)

IV LACK

=

505





IV PERIOD

=

505





TIMELIMIT

=

360



% SIMULATION LIMIT TIME (HOUR)

BW TO

=

180





MATTING

=

0.



% BEGINNING MATTING (HOUR)

TRANSTIME ON

=

144 .

% SHOULD BE MATTING TIME + 6 DAYS(144 HOURS)

N FETUS

=

10





iEXPOSURE DOSE SCENARIOS (UG/KG)

%MSTOT
%MSTOT
%MSTOT
MSTOT

= 0.0125	% ORAL EXPOSURE DOSE (UG/KG)

= 0.050 % ORAL EXPOSURE DOSE (UG/KG)
=0.2	% ORAL EXPOSURE DOSE (UG/KG)

=0.8	% ORAL EXPOSURE DOSE (UG/KG)

C.2.4.2.9. Ohsako et al. (2001).

%clear variable
output 0clear

prepare 0clear T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CFETUSNGKG AUCLI_NGKGH
AUCF_NGKGH AUCBS_NGKGLIADJ AUC_BBNGKGH AUC_FENGKGH CBNDLINGKG AUCBNDLI_NGKGH
CBNGKG AUC CBNGKGH

iOhsako et al. 2001

^protocol: single oral dose at GD15
•;DevTCDD4Species . csl
oRAT_GESTATIONAL_ICF_F083109.csl
oRAT_GESTATIONAL_ICF_F0 92 0 0 9.csl
idose levels: 0.0125, 0.05, 0.2,

(now 09-11-09)
(now 09-21-09)
0.8 ug/kg at GD15

idose levels: 12.5, 50, 200, 800 ng/kg at GD15

%EXPOSURES SCENARIOS
MAXT=0.01

CINT =0.1	%

EXP TIME ON	= 360	% delay before begin exposure (HOUR)

EXP TIME OFF = 384	% TIME EXPOSURE STOP (HOUR)

This document is a draft for review purposes only and does not constitute Agency policy.

C-71 DRAFT—DO NOT CITE OR QUOTE


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DAY_CYCLE	=24

B C K_T I ME_ON	= 0.

BCK_TIME_OFF	= 0.

IV_LACK	= 5 05

IV_PERIOD	= 505

TIMELIMIT	= 384

BW_T0	= 200

MATTING	= 0.

TRANSTIME_ON	= 144.
HOURS)

N FETUS	=10

DELAY BEFORE BACKGROUND EXPOSURE (HOUR)
TIME OF BACKGROUND EXPOSURE STOP (HOUR)

SIMULATION LIMIT TIME (HOUR)

BEGINNING MATTING (HOUR)

SHOULD BE MATTING TIME + 6 DAYS(144

iEXPOSURE DOSE SCENARIOS (UG/KG)

%MSTOT
%MSTOT
%MSTOT
MSTOT

0.0125	% ORAL EXPOSURE DOSE (UG/KG)

0.05	% ORAL EXPOSURE DOSE (UG/KG)

0.20	% ORAL EXPOSURE DOSE (UG/KG)

=0.80	% ORAL EXPOSURE DOSE (UG/KG)

C.2.4.2.10. Schantzetal. (1996) andAmin et al. (2000).

%clear variable
output 0clear

prepare 0clear T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CFETUSNGKG AUCLI_NGKGH
AUCF_NGKGH AUCBS_NGKGLIADJ AUC_BBNGKGH AUC_FENGKGH CBNDLINGKG AUCBNDLI_NGKGH
CBNGKG AUC_CBNGKGH

%Amin et al. 2000 (rat species) and Schantz et al. 1996
%protocol: daily doses on GDs 10 to 16
%DevTCDD4Species.csl

%RAT_GESTATIONAL_ICF_F083109.csl (now 09-11-09)

%dose levels: 25 and 100 ng/kg/day
%dose levels: 0.025 and 0.100 ug/kg/day

i;EXPOSURES SCENARIOS

MAXT
CINT

EXP_TIME_ON
EX P_T I ME_0 F F
to 16
DAY_CYCLE
B C K_TIME_ON
BCK_TIME_OFF
IV_LACK
IV_PERIOD
TIMELIMIT
BW_T0
MATTING
TRANSTIME_ON
N FETUS

0. 001
0.1 =?
240.
384 .

24

1000.

1000.

505.

505.

384 .

250.

0

144 .

10

% TIME AT WHICH EXPOSURE BEGINS (HOUR)
i TIME AT WHICH EXPOSURE ENDS (HOUR) GD 10

weekly cycle

% DELAY BEFORE BACKGROUND EXPOSURE (HOUR)
% TIME OF BACKGROUND EXPOSURE STOP (HOUR)

% SIMULATION LIMIT TIME (HOUR)

BEGINNING MATTING (HOUR)

% SHOULD BE MATTING TIME + 6 DAYS(144 HOURS)

ORAL EXPOSURE DOSE (UG/KG)

iEXPOSURE DOSE SCENARIOS (UG/KG)

%MSTOT	= .025

MSTOT	= .100

MSTOTBCKGR	=0 % Background Exposure (UG/KG)

This document is a draft for review purposes only and does not constitute Agency policy.

C-72 DRAFT—DO NOT CITE OR QUOTE


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C.2.4.2.11. Seoetal. (1995).

%clear variable
output 0clear

prepare 0clear T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CFETUSNGKG AUCLI_NGKGH
AUCF_NGKGH AUCBS_NGKGLIADJ AUC_BBNGKGH AUC_FENGKGH CBNDLINGKG AUCBNDLI_NGKGH
CBNGKG AUC CBNGKGH

%Seo et al. 1995

%protocol: daily doses on GDs 10-16
%DevTCDD4Species.csl

%RAT_GESTATIONAL_ICF_F083109.csl (now 09-11-09)
%dose levels: 0.025 and 0.1 ug/kg on GDs 10-16
%dose levels: 25 and 100 ng/kg on GDs 10-16

MAXT = 0.01
CINT =0.1

%EXPOSURES SCENARIOS

EXP_TIME_ON	= 24 0

EX P_T I ME_0 F F	= 384

DAY_CYCLE	=24

B C K_T I ME_ON	= 0.
BEGINS (HOUR)

BCK_TIME_OFF	= 0.
ENDS (HOUR)

IV_LACK	= 5 05

IV_PERIOD	= 505

TIMELIMIT	= 384

BW_T0	= 190

MATTING	= 0.

TRANSTIME_ON	= 144.
HOURS)

N FETUS	=10

TIME AT WHICH EXPOSURE BEGINS (HOUR)
TIME AT WHICH EXPOSURE ENDS (HOUR)

TIME AT WHICH BACKGROUND EXPOSURE

TIME AT WHICH BACKGROUND EXPOSURE

SIMULATION LIMIT TIME (HOUR)

BEGINNING MATTING (HOUR)

SHOULD BE MATTING TIME + 6 DAYS(144

•;EXPOSURE DOSE SCENARIOS (UG/KG)
%MSTOT	= 0.025

MSTOT	=0.1

% ORAL EXPOSURE DOSE (UG/KG)
ORAL EXPOSURE DOSE (UG/KG)

C.2.5. Mouse Standard Model
C.2.5.1. Model Code

PROGRAM: 'Three Compartment PBPK Model for TCDD in Mice: Standard Model (Non-
Gestation)'

IMice Dioxin 3C June09 1 icf afterKKfix v3 mousenongest.csl
!MICE~NON_GESTAT_ICF_F0831097csl	~ ~

!MICE_NON_GESTAT_ICF_F0 93 0 0 9.csl
!MICE_NON_GESTAT_ICF_Fl0 0 609.csl

INITIAL ! INITIALIZATION OF PARAMETERS
!SIMULATION PARAMETERS ====

This document is a draft for review purposes only and does not constitute Agency policy.

C-73 DRAFT—DO NOT CITE OR QUOTE


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CONSTANT PARA_ZERO	= 1D-30

CONSTANT EXP_TIME_ON	=	0.0	! TIME AT WHICH EXPOSURE BEGINS

(HOURS)

CONSTANT EXP_TIME_0FF = 2832	! TIME AT WHICH EXPOSURE ENDS

(HOURS)

CONSTANT DAY_CYCLE	=24	! NUMBER OF HOURS BETWEEN DOSES

(HOURS)

CONSTANT BCK_TIME_ON	=	0.0	! TIME AT WHICH BACKGROUND EXPOSURE

BEGINS (HOURS)

CONSTANT BCK_TIME_OFF =	0.0	! TIME AT WHICH BACKGROUND EXPOSURE

ENDS (HOURS)

CONSTANT MW=322 ! MOLECULAR WEIGHT (NG/NMOL)

CONSTANT SERBLO =0.55
CONSTANT UNITCORR = 1000

!CONSTANT EXPOSURE CONTROL ===========

!ACUTE, SUBCHRONIC, CHRONIC	EXPOSURE =====

!OR BACKGROUND EXPOSURE (IN	THIS CASE 3 TIMES A DAY)===

CONSTANT MSTOTBCKGR	=	0.0	!ORAL BACKGROUND EXPOSURE DOSE

(UG/KG)

CONSTANT MSTOT	=	0.15	!ORAL EXPOSURE DOSE (UG/KG)

CONSTANT MSTOTsc	=	0.0	! SUBCUTANEOUS EXPOSURE DOSE

(UG/KG)

!ORAL ABSORPTION
MSTOT_NM	= MSTOT/MW !AMOUNT IN NMOL/G

! INTRAVENOUS ABSORPTION
CONSTANT DOSEIV =0.0	!INJECTED DOSE (UG/KG)

DOSEIV_NM = DOSEIV/MW ! CONVERTS THE INJECTED DOSE TO NMOL/G

!INITIAL GUESS OF THE FREE CONCENTRATION IN THE LIGAND (COMPARTMENT
INDICATED BELOW)====

CONSTANT CFLLI0	=	0.0	!LIVER (NMOL/ML)

!BINDING CAPACITY (AhR) FOR NON LINEAR BINDING (COMPARTMENT INDICATED
BELOW) (NMOL/ML)

CONSTANT LIBMAX	=	3.5e-4	! LIVER (NMOL/ML), WANG ET AL.

1997

! PROTEIN AFFINITY CONSTANTS (1A2 OR AhR, COMPARTMENT INDICATED BELOW)
(NMOL/ML)===

CONSTANT KDLI	=	1.0e-4	!LIVER (AhR)(NMOL/ML), WANG ET AL.

1997

CONSTANT KDLI2	=	2.Oe-2	!LIVER (1A2 ) (NMOL/ML) , EMOND ET AL.

2004

!===EXCRETION AND ABSORPTION CONSTANT (OPTIMIZED)

CONSTANT KST	= 0.3 ! GASTRIC RATE CONSTANT (HR-1),

CONSTANT KABS	= 0.48 !INTESTINAL ABSORPTION CONSTANT (HR-1) ),

WANG ET AL. 1997

! ELIMINATION CONSTANTS

CONSTANT CLURI	=	0.09 ! URINARY CLEARANCE (ML/HR)

This document is a draft for review purposes only and does not constitute Agency policy.

C-74 DRAFT—DO NOT CITE OR QUOTE


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! ==test elimination variable

constant kelv	=	0.4	! INTERSPECIES VARIABLE ELIMINATION

CONSTANT (1/HOUR)

! CONSTANT TO DIVIDE THE ABSORPTION INTO LYMPHATIC AND PORTAL FRACTIONS
CONSTANT A	=0.7	! LYMPHATIC FRACTION, WANG ET AL.

1997

!PARTITION COEFFICIENTS OPTIMIZED
CONSTANT PF	= 400

CONSTANT PRE	= 3

AL. 2 0 0 0

CONSTANT PLI	= 6

! ADIPOSE TISSUE/BLOOD
! REST OF THE BODY/BLOOD, WANG ET

! LIVER/BLOOD, WANG ET AL. 19 97

!===PARAMETER FOR INDUCTION OF CYP 1A2

CONSTANT PAS_INDUC=
CONSTANT CYP1A2_10UTZ
(NMOL/ML)

CONSTANT CYP1A2_1A1 =
CYP1A2_1EC5 0
CYP1A2_1A2 =
CYP1A2_1K0UT
CYP1A2_1TAU
CYP1A2 1EMAX

5

13
5
1
5

CONSTANT
CONSTANT
CONSTANT

CONSTANT	_

CONSTANT CYP1A2_1EMAX = 600
(UNITLESS)

CONSTANT HILL	=0.6

EFFECT CONSTANT (UNITLESS)

!DIFFUSIONAL PERMEABILITY
CONSTANT PAFF	=0.12

CONSTANT PAREF =0.03
CONSTANT PALIF =0.35

! INCLUDE INDUCTION? (1 = YES, 0 = NO)
! DEGRADATION CONCENTRATION CONSTANT OF 1A2

! BASAL CONCENTRATION OF 1A1 (NMOL/ML)

! DISSOCIATION CONSTANT TCDD-CYP1A2 (NMOL/ML)
! BASAL CONCENTRATION OF 1A2 (NMOL/ML)

! FIRST ORDER RATE OF DEGRADATION (H-l)

HOLDING TIME (H)

! MAXIMUM INDUCTION OVER BASAL EFFECT

!HILL CONSTANT; COOPERATIVELY LIGAND BINDING

FRACTION

ADIPOSE (UNITLESS), WANG ET AL.
REST OF THE BODY (UNITLESS)
LIVER (UNITLESS)

2000

!COMPARTMENT TISSUE BLOOD VOLUME =========

CONSTANT WLI0	= 0.0549 ! LIVER, ILSI 1994

CONSTANT WF0	= 0.069 ! ADIPOSE

!TISSUE BLOOD FLOW EXPRESSED AS A FRACTION OF CARDIAC OUTPUT
CONSTANT QFF = 0.070	! ADIPOSE TISSUE BLOOD FLOW FRACTION

(UNITLESS), LEUNG ET AL. 1990

CONSTANT QLIF = 0.161	! LIVER (UNITLESS) ILSI ET AL. 1994

!COMPARTMENT TISSUE BLOOD EXPRESSED AS A FRACTION OF THE TOTAL
COMPARTMENT VOLUME

CONSTANT WFB0 = 0.050
CONSTANT WREB0 = 0.030
CONSTANT WLIB0 = 0.266

ADIPOSE TISSUE, WANG ET AL. 1997
REST OF THE BODY, WANG ET AL. 1997
LIVER, WANG ET AL. 19 97

! EXPOSURE SCENARIO FOR UNIQUE OR REPETITIVE WEEKLY OR MONTHLY EXPOSURE
! NUMBER OF EXPOSURES PER WEEK
CONSTANT WEEK_LACK =0.0	! DELAY BEFORE EXPOSURE ENDS (WEEK)

CONSTANT WEEK_PERIOD = 168	! NUMBER OF HOURS IN THE WEEK (HOURS)

CONSTANT WEEK_FINISH = 120 ! TIME EXPOSURE ENDS (HOURS)

! NUMBER OF EXPOSURES PER MONTH
CONSTANT MONTH LACK =0.0 ! DELAY BEFORE EXPOSURE (MONTH)

This document is a draft for review purposes only and does not constitute Agency policy.

C-75 DRAFT—DO NOT CITE OR QUOTE


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!SET FOR BACKGROUND EXPOSURE===========

!CONSTANT FOR BACKGROUND EXPOSURE===========

CONSTANT Day_LACK_BG =0.0	! DELAY BEFORE EXPOSURE BEGINS (HOURS)

CONSTANT Day_PERIOD_BG =24 ! LENGTH OF EXPOSURE (HOURS)

! NUMBER OF EXPOSURES PER WEEK

CONSTANT WEEK_LACK_BG =0.0
CONSTANT WEEK_PERIOD_BG = 168
CONSTANT WEEK FINISH BG = 168

DELAY BEFORE BACKGROUD EXPOSURE (WEEK)
NUMBER OF HOURS IN THE WEEK (HOURS)

TIME EXPOSURE ENDS (HOURS)

!GROWTH CONSTANT FOR RAT AND MOUSE
!CONSTANT FOR MOTHER BODY WEIGHT GROWTH ======

CONSTANT BW_T0 = 20	!CHANGED FOR SIMULATION

!CONSTANT USED IN CARDIAC OUTPUT EQUATION, HADDAD 2001
CONSTANT QCCAR =275	!CONSTANT (ML/MIN/KG)

! COMPARTMENT LIPID EXPRESSED AS THE FRACTION OF TOTAL LIPID

CONSTANT F_TOTLIP = 0.855
CONSTANT B_TOTLIP = 0.0033
CONSTANT RE_TOTLIP = 0.019
CONSTANT LI TOTLIP =0.06

!ADIPOSE TISSUE (UNITLESS)
!BLOOD (UNITLESS)

!REST OF THE BODY (UNITLESS)
!LIVER (UNITLESS)

END ! END OF THE INITIAL SECTION

DYNAMIC ! DYNAMIC SIMULATION SECTION

ALGORITHM
CINTERVAL
MAXTERVAL
MINTERVAL
VARIABLE
CONSTANT
(HOURS)

CINTXY = CINT
PFUNC = CINT

IALG
CINT
MAXT
MINT
T

TIMELIMIT

2	!GEAR METHOD

1.0	!COMMUNICATION INTERVAL

1.0e+10	IMAXIMUM CALCULATION INTERVAL

1.0E-10	!MINIMUM CALCULATION INTERVAL

0.0	!HOUR

2904.0	!SIMULATION TIME LIMIT

!TIME CONVERSION

DAY
WEEK
MONTH
YEAR

= T/24.0
= T/168.0
= T/730.0
= T/87 60.0

TIME IN DAYS
TIME IN WEEKS
TIME IN MONTHS
TIME IN YEARS

!NMAX =MAX(T,CTFNGKG)
nmax =max(T,CFNGKG)

DERIVATIVE ! PORTION OF CODE THAT SOLVES DIFFERENTIAL EQUATIONS

!CHRONIC OR SUBCHRONIC EXPOSURE SCENARIO
!NUMBER OF EXPOSURES PER DAY

DAY_LACK	= EXP_TIME_ON

DAY_PERIOD = DAY_CYCLE
DAY_FINISH = CINTXY
MONTH_PERIOD = TIMELIMIT
MONTH FINISH = EXP TIME OFF

DELAY BEFORE EXPOSURE BEGINS
EXPOSURE PERIOD (HOURS)
LENGTH OF EXPOSURE (HOURS)
EXPOSURE PERIOD (MONTHS)
LENGTH OF EXPOSURE (MONTHS)

(HOURS)

This document is a draft for review purposes only and does not constitute Agency policy.

C-76 DRAFT—DO NOT CITE OR QUOTE


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!NUMBER OF EXPOSURES PER DAY AND MONTH
DAY_FINISH_BG = CINTXY

MONTH_LACK_BG = BCK_TIME_ON ! DELAY BEFORE BACKGROUD EXPOSURE BEGINS
(MONTHS)

MONTH_PERIOD_BG = TIMELIMIT	! BACKGROUND EXPOSURE PERIOD (MONTHS)

MONTH_FINISH_BG = BCK_TIME_OFF ! LENGTH OF BACKGROUND EXPOSURE (MONTHS)

! FRACTION OF DIOXIN ABSORBED IN THE PORTAL FRACTION OF THE LIVER
B = 1.0-A

!GROWTH UP EQUATION (G)

PARAMETER (BW_RMN = 1.0E-30)

WT0= (BW_T0 *(1.0+(0.41*T)/(1402.5+T+BW_RMN) ) )

! VARIABILITY OF REST OF THE BODY DEPENDS ON OTHER ORGANS
!REST OF THE BODY FRACTION; UPDATED FOR EPA ASSESSMENT
WRE0 = (0.91 - (WLIB0*WLI0 + WFB0*WF0 + WLI0 + WF0))/(1+WREB0)

! REST OF THE BODY BLOOD	FLOW FRACTION

QREF = 1.0-(QFF+QLIF)	!REST OF BODY BLOOD FLOW (ML/HR)

!SUMMATION OF BLOOD FLOW	FRACTION (SHOULD BE EQUAL TO 1)

QTTQF = QFF+QREF+QLIF	! SUM MUST EQUAL 1

!COMPARTMENT VOLUME (G)
WF = WF0 * WTO
WRE = WRE0 * WTO
WLI = WLI0 * WTO

ADIPOSE

REST OF THE BODY
LIVER

!COMPARTMENT TISSUE BLOOD	(G)

WFB = WFB0 * WF	! ADIPOSE

WREB = WREB0 * WRE	! REST OF THE BODY

WLIB = WLIB0 * WLI	! LIVER

!CARDIAC OUTPUT FOR THE GIVEN BODY WEIGHT
QC= QCCAR* 60*(WTO/1000.0)**0.75

QF = QFF*QC	! ADIPOSE TISSUE BLOOD FLOW RATE (ML/HR)

QLI = QLIF*QC	! LIVER TISSUE BLOOD FLOW RATE (ML/HR)

QRE = QREF*QC	! REST OF THE BODY BLOOD FLOW RATE (ML/HR)

QTTQ = QF+QRE+QLI !TOTAL FLOW RATE (ML/HR)

!PERMEABILITY ORGAN FLOW (ML/HR) =======

PAF = PAFF*QF	! ADIPOSE TISSUE

PARE = PAREF*QRE	! REST OF THE BODY

PALI = PALIF*QLI	! LIVER TISSUE

!ABSORPTION SECTION
! ORAL

!BACKGROUND EXPOSURE

!EXPOSURE FOR STEADY STATE CONSIDERATION
!REPETITIVE EXPOSURE SCENARIO

MSTOT_NMBCKGR = MSTOTBCKGR/322 !AMOUNT IN NMOL/G

This document is a draft for review purposes only and does not constitute Agency policy.

C-77 DRAFT—DO NOT CITE OR QUOTE


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MSTTBCKGR =MSTOT_NMBCKGR *WT0

!REPETITIVE ORAL BACKGROUND EXPOSURE SCENARIOS
DAY_EX P 0 S U RE_B G = PULSE(DAY_LACK_BG,DAY_PERIOD_BG,DAY_FINISH_BG)
WEEK_EXPOSURE_BG = PULSE(WEEK_LACK_BG,WEEK_PERIOD_BG,WEEK_FINISH_BG)
MONTH_EXPOSURE_BG = PULSE(MONTH_LACK_BG,MONTH_PERIOD_BG,MONTH_FINISH_BG)

MSTTCH_BG = (DAY_EXPOSURE_BG*WEEK_EXPOSURE_BG*MONTH_EXPOSURE_BG)*MSTTBCKGR
MSTTFR_BG = MSTTBCKGR/CINT

totalBG= integ (MSTTCH_BG,0.0)

CYCLE BG =DAY EXPOSURE BG*WEEK EXPOSURE BG*MONTH EXPOSURE BG

!CONDITIONAL ORAL EXPOSURE (BACKGROUND EXPOSURE)
IF (MSTTCH_BG.EQ.MSTTBCKGR) THEN
ABSMSTT_GB= MSTTFR_BG

ELSE

ABSMSTT_GB =0.0
END IF

!EXPOSURE + !REPETITIVE EXPOSURE SCENARIO
IV= DOSEIV_NM * WTO !AMOUNT IN NMOL
MSTT= MSTOT_NM * WTO !AMOUNT IN NMOL

DAY_EXPOSURE = PULSE(DAY_LACK,DAY_PERIOD,DAY_FINISH)

WEEK_EXPOSURE = PULSE(WEEK_LACK,WEEK_PERIOD,WEEK_FINISH)
MONTH_EXPOSURE = PULSE(MONTH_LACK,MONTH_PERIOD,MONTH_FINISH)

MSTTCH = (DAY_EXPOSURE*WEEK_EXPOSURE*MONTH_EXPOSURE)*MSTT
CYCLE = DAY_EXPOSURE*WEEK_EXPOSURE*MONTH_EXPOSURE

SUMEXPEVENT= integ (CYCLE,0.0)*cint INUMBER OF CYCLE GENERATE DURING
SIMULATION

MSTTFR = MSTT/CINT

! CONDITIONAL ORAL EXPOSURE
IF (MSTTCH.EQ.MSTT) THEN

ABSMSTT= MSTTFR
ELSE

ABSMSTT =0.0
END IF

CYCLETOT=INTEG(CYCLE, 0.0)

!MASS CHANGE IN THE LUMEN
RMSTT= -(KST+KABS)*MST+ABSMSTT +ABSMSTT_GB ! RATE OF CHANGE (NMOL/H)
MST = INTEG(RMSTT,0.0) !AMOUNT OF STAY IN DUODENUM (NMOL)

!ABSORPTION IN LYMPH CIRCULATION
LYRMLUM = KABS*MST*A
LYMLUM = INTEG(LYRMLUM,0.0)

!ABSORPTION IN PORTAL CIRCULATION

This document is a draft for review purposes only and does not constitute Agency policy.

C-78 DRAFT—DO NOT CITE OR QUOTE


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LIRMLUM = KABS*MST*B

LIMLUM = INTEG(LIRMLUM,0.0)

!PERCENT OF DOSE REMAINING IN THE GI TRACT
PRCT_remain_GIT = (MST/(MSTT+1E-30))*100

RFECES = KST*MST + REXCLI

FECES = INTEG(RFECES,0.0)
prctFECES = (FECES/(BDOSE_TOTAL+lE-30))*100

!ABSORPTION OF DIOXIN BY IV ROUTE	

IVR= IV/PFUNC ! RATE FOR IV INFUSION IN BLOOD
EXPIV= IVR * (1.0-STEP(PFUNC))

IVDOSE = integ(EXPIV,0.0)

!SYSTEMIC BLOOD CONCENTRATION (NMOL/ML)
! MODIFICATION ON OCTOBER 6, 2009
CB=(QF*CFB+QRE*CREB+QLI*CLIB+EXPIV+LYRMLUM)/(QC+CLURI) !
CA = CB

!URINARY EXCRETION BY KIDNEY
! MODIFICATION ON OCTOBER 6, 2009
RAURI = CLURI *CB

AURI = INTEG(RAURI,0.0)

prctAURI = (AURI/(BDOSE_TOTAL+lE-30))*100

!UNIT CONVERSION POST SIMULATION
PRCT_B = (CB/(MSTT+1E-30))*100 ! PERCENT OF DOSE/G TISSUE
CBNGKG=CB*MW*UNITCORR

CBSNGKGLIADJ= (CB*MW*UNITCORR*(1.0/B_TOTLIP)*(1.0/SERBLO))![NG of TCDD
Serum/Kg OF LIPIP]

CBPMOL_KG= CB*UNITCORR*UNITCORR
CBNGG = CB*MW

!ADIPOSE TISSUE COMPARTMENT
! TISSUE BLOOD SUBCOMPARTMENT
RAFB = QF*(CA-CFB)-PAF*(CFB-CF/PF)
AFB = INTEG(RAFB,0.0)
CFB = AFB/WFB

!TISSUE SUBCOMPARTMENT
RAF = PAF*(CFB-CF/PF)
AF = INTEG(RAF, 0.0)

CF = AF/WF

!CONCENTRATION IN PMOL/KG

(NMOL/HR)
!(NMOL)
(NMOL/ML)

(NMOL/HR)
!(NMOL)
(NMOL/ML)

!POST SIMULATION UNIT CONVERSION
CFTOTAL = (AF + AFB)/(WF + WFB) ! TOTAL CONCENTRATION IN FAT(NM/ML)
PRCT_F = (CFTOTAL/(MSTT+1E-30))*100 ! PERCENT OF DOSE IN FAT
CFNGKG = CFTOTAL*MW*UNITCORR
CFUGG=(CFTOTAL*MW)/UNITCORR

CFPMOL_KG= CFTOTAL*UNITCORR*UNITCORR	!CONCENTRATION IN PMOL/KG

CFNGG = CFTOTAL*MW

!REST OF THE BODY COMPARTMENT
!TISSUE BLOOD SUBCOMPARTMENT

This document is a draft for review purposes only and does not constitute Agency policy.

C-79 DRAFT—DO NOT CITE OR QUOTE


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RAREB= QRE*(CA-CREB)-PARE*(CREB-CRE/PRE)	!(NMOL/HR)

AREB = INTEG(RAREB,0.0)	!(NMOL)

CREB = AREB/WREB	!(NMOL/ML)
!TISSUE SUBCOMPARTMENT

RARE = PARE*(CREB - CRE/PRE)	!(NMOL/HR)

ARE = INTEG(RARE,0.0)	!(NMOL)

CRE = ARE/WRE	!(NMOL/ML)

!POST SIMULATION UNIT CONVERSION
CRETOTAL= (ARE + AREB)/(WRE + WREB)	! CONCENTRATION AT STEADY

STATE

PRCT RE = (CRETOTAL/(MSTT+1E-30))*100

!LIVER COMPARTMENT
!TISSUE BLOOD SUBCOMPARTMENT
RALIB = QLI*(CA-CLIB)-PALI*(CLIB-CFLLIR)+LIRMLUM
ALIB = INTeg(RALIB,0.0)

CLIB = ALIB/WLIB

!TISSUE SUBCOMPARTMENT
RALI = PALI*(CLIB-CFLLIR)-REXCLI
ALI = integ(RALI,0.0)

CLI = ALI/WLI

!(NMOL/HR)
!(NMOL)

!(NMOL/HR)

!(NMOL)
!(NMOL/ML)

!FREE TCCD CONCENTRATION IN LIVER (NMOL/ML)

PARAMETER (LIVER_1RMN = 1.0E-30)

CFLLI= IMPLC(CLI-(CFLLIR*PLI+(LIBMAX*CFLLIR/(KDLI+CFLLI &
+LIVER_1RMN))+((CYP1A2_103*CFLLIR/(KDLI2+CFLLIR &
+LIVER_1RMN)*PAS_INDUC)))-CFLLI,CFLLI0)

CFLLIR=DIM(CFLLI,0.0) ! FREE CONCENTRATION IN LIVER

CBNDLI= LIBMAX*CFLLIR/(KDLI+CFLLIR+LIVER_1RMN) !BOUND CONCENTRATION

!POST SIMULATION UNIT CONVERSION
CLITOTAL= (ALI + ALIB)/(WLI + WLIB)!

PRCT_LI = (CLITOTAL/(MSTT+1E-30))*100 ! PERCENT OF DOSE IN LIVER
rec_occ_AHR= (CFLLIR/(KDLI+CFLLIR+1E-30))*100.0 ! PERCENT OF AhR OCCUPANCY
PROT_occ_lA2= (CFLLIR/(KDLI2+CFLLIR))*100.0 ! PERCENT OF 1A2 OCCUPANCY
CLINGKG =(CLITOTAL*MW*UNITCORR)

CBNDLINGKG = CBNDLI*MW*UNITCORR
CLIUGG=(CLITOTAL*MW)/UNITCORR

CLIPMOL_KG= CLITOTAL*UNITCORR*UNITCORR	!CONCENTRATION IN PMOL/KG

CLINGG = CLITOTAL*MW

!Fraction increase of induction of CYP1A2
fold_ind=(CYP1A2_10UT/CYP1A2_1A2)

VARIATIONOfAC =(CYP1A2_10UT-CYP1A2_1A2)/CYP1A2_1A2

!VARIABLE ELIMINATION BASED ON THE CYP1A2
KBILE_LI_T =((CYP1A2_10UT-CYP1A2_1A2)/CYP1A2_1A2)*Kelv !INDUCED BILIARY
EXCRETION RATE CONSTANT

REXCLI= (KBILE_LI_T*CFLLIR*WLI) !DOSE-DEPENDENT EXCRETION RATE
EXCLI = INTEG(REXCLI,0.0)

!CHEMICAL IN CYP450 (1A2) COMPARTMENT

This document is a draft for review purposes only and does not constitute Agency policy.

C-80 DRAFT—DO NOT CITE OR QUOTE


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!EQUATION FOR INDUCTION OF CYP1A2
CYP1A2_1KINP = CYP1A2_1K0UT* CYP1A2_10UTZ

! MODIFICATION ON OCTOBER 6, 2009
CYP1A2_10UT =INTEG(CYP1A2_1KINP * (1.0 + CYP1A2_1EMAX *(CBNDLI+1.0e-30)**HILL
&

/(CYP1A2_1EC50**HILL + (CBNDLI+1.0e-30)**HILL)) &
- CYP1A2_1K0UT*CYP1A2_10UT, CYP1A2_10UTZ)

! EQUATIONS INCORPORATING DELAY OF CYP1A2 PRODUCTION (NOT USED IN
SIMULATIONS)

CYP1A2_1R02 = (CYP1A2_10UT - CYP1A2_102)/ CYP1A2_1TAU

CYP1A2_102 =INTEG(CYP1A2_1R02, CYP1A2_1A1)

CYP1A2_1R03 = (CYP1A2_102 - CYP1A2_103)/ CYP1A2_1TAU
CYP1A2_103 =INTEG(CYP1A2_1R03, CYP1A2_1A2)

! MASS BALANCE CONTROL
BDOSE= LYMLUM+LIMLUM+IVDOSE

BMASSE = EX C LI+AURI+AFB+AF+AREB+ARE+ALIB+ALI
BDIFF = BDOSE-BMASSE

! AMOUNT TOTAL PRESENT IN THE GI TRACT
BDOSE_TOTAL =LYMLUM+LIMLUM+FECES

!BODY BURDEN IN NG
Body burden =(AFB+AF+AREB+ARE+ALIB+ALI)*MW

!BODY BURDEN CONCENTRATION (NG/KG)

BBNGKG =(((AFB+AF+AREB+ARE+ALIB+ALI)*MW)/(WTO/UNITCORR)) !

!COMMAND FOR END OF SIMULATION
TERMT (T.GE. TimeLimit, 'Time limit has been reached.')

END ! END OF THE DERIVATIVE SECTION
END ! END OF THE DYNAMIC SECTION
END ! END OF PROGRAM

C.2.5.2. Input Files

C.2.5.2.1. Delia Porta (1987) (female)

output 0clear
prepare 0clear

prepare T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG CBNGKG

% Delia Porta 1987 for female mice.

%dose levels: 2.5 and 5 ug/kg/week for 52 weeks
%dose levels: 2500 and 5000 ng/kg/week for 52 weeks
%dose levels equivalent to: 357 and 714 ng/kg/d

MAXT = 0.01
CINT =0.1
EXP_TIME_ON
EX P_T I ME_0 F F
DAY_CYCLE
BCK TIME ON

0.

8736

168

0.

idelay before begin exposure (HOUR)
iTIME EXPOSURE STOP (HOUR)

¦;DELAY BEFORE BACGROUND EXPOSURE (HOUR)

This document is a draft for review purposes only and does not constitute Agency policy.

C-81 DRAFT—DO NOT CITE OR QUOTE


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BCK_TIME_OFF	= 0.	%TIME OF BACKGROUND EXPOSURE STOP (HOUR)

TIMELIMIT	= 8736	%SIMULATION LIMIT TIME (HOUR)

BW TO	= 20	% Body weight at the beginning of the simulation

(g); corresponds to 6 weeks of age and taken from Figure 3

%EXPOSURE DOSE SCENARIOS (UG/KG)

%MSTOT	=2.5	% exposure dose ug/kg

MSTOT	=5.0	% exposure dose ug/kg

C.2.5.2.2. Delia Porta (1987) (male)

output 0clear
prepare 0clear

prepare T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG CBNGKG

% Delia Porta 1987 for male mice.

%dose levels: 2.5 and 5 ug/kg/week for 52 weeks
%dose levels: 2500 and 5000 ng/kg/week for 52 weeks
%dose levels equivalent to: 357 and 714 ng/kg/d

MAXT = 0.01
CINT =0.1
EXP_TIME_ON
EX P_T I ME_0 F F
DAY_CYCLE
B C K_TIME_ON
BCK_TIME_OFF
TIMELIMIT
BW TO

0.

8736
168
0.

0.

8736
26

idelay before begin exposure (HOUR)
iTIME EXPOSURE STOP (HOUR)

¦;DELAY BEFORE BACGROUND EXPOSURE (HOUR)
iTIME OF BACKGROUND EXPOSURE STOP (HOUR)
¦;SIMULATION LIMIT TIME (HOUR)

i Body weight at the beginning of the simulation

(g); corresponds to 6 weeks of age and taken from Figure 3

%EXPOSURE DOSE SCENARIOS (UG/KG)

%MSTOT	=2.5	% exposure dose ug/kg

MSTOT	=5.0	% exposure dose ug/kg

C.2.5.2.3. NTP (1982) (female) (chronic)

%RAT2.m

%clear variable
output 0clear
prepare 0clear

prepare T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG CBNGKG
% output 0nciout=168 T SUMEXPEVENT

% NTP 1982.

%built and check in September 20, 2009
%protocol: twice weekly gavage for 104 weeks
%Rat Dioxin 3C June09 2clean 2.csl
%MICE_NON_GESTAT_ICF_F083109.csl
%MICE_NON_GESTAT_ICF_F092009.csl (now 09-20-09)

%dose levels: 0.02, 0.1, 1 ug/kg/biweekly, ug/kg for 104 weeks
%dose levels: 20, 100, 1000 ng/kg/biweekly,ng/kg for 104 weeks
%dose levels equivalent to: 5.71, 28.57, 285.1 ng/kg/d

This document is a draft for review purposes only and does not constitute Agency policy.

C-82 DRAFT—DO NOT CITE OR QUOTE


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MAXT = 0.01
CINT =0.1
EXP_TIME_ON
EX P_T I ME_0 F F
DAY_CYCLE
B C K_TIME_ON
BCK_TIME_OFF
TIMELIMIT
BW_T0

(g)

o.

17472
84
0.

0.

17472
23

idelay before begin exposure (HOUR)

%TIME EXPOSURE STOP (HOUR)

¦;DELAY BEFORE BACGROUND EXPOSURE (HOUR)
iTIME OF BACKGROUND EXPOSURE STOP (HOUR)
%SIMULATION LIMIT TIME (HOUR)
i Body weight at the beginning of the simulation

iEXPOSURE DOSE SCENARIOS (UG/KG)

%MSTOT	=0.02	% exposure dose ug/kg

%MSTOT	=0.1	% exposure dose ug/kg

MSTOT	=1.0	% exposure dose ug/kg

C.2.5.2.4. NTP (1982) (male) (chronic).

%RAT2.m

%clear variable
output 0clear
prepare 0clear

prepare T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG CBNGKG
% output 0nciout=168 T SUMEXPEVENT

% NTP 1982.

%built and check in September 20, 2009
%protocol: twice weekly gavage for 104 weeks
%Rat Dioxin 3C June09 2clean 2.csl
%MICE_NON_GESTAT_ICF_F083109.csl
%MICE_NON_GESTAT_ICF_F092009.csl (now 09-20-09)

%dose levels: 0.005, 0.025, 0.25 ug/kg/biweekly, ug/kg for 104 weeks
%dose levels: 5, 25, 250 ng/kg/biweekly,ng/kg for 104 weeks
%dose levels equivalent to: 1.4, 7.1, 71 ng/kg/d

MAXT = 0.01





CINT =0.1





EXP TIME ON

= 0.

%delay before begin exposure (HOUR)

EXP TIME OFF

= 17472

%TIME EXPOSURE STOP (HOUR)

DAY CYCLE

= 84



BCK TIME ON

= 0.

%DELAY BEFORE BACGROUND EXPOSURE (HOUR)

BCK TIME OFF

= 0.

%TIME OF BACKGROUND EXPOSURE STOP (HOUR)

TIMELIMIT

= 17472

%SIMULATION LIMIT TIME (HOUR)

BW TO

= 25

% Body weight at the beginning of the simulation

iEXPOSURE DOSE SCENARIOS (UG/KG)

%MSTOT	= 0.005	% exposure dose ug/kg

%MSTOT	= 0.025	% exposure dose ug/kg

MSTOT	=0.25	% exposure dose ug/kg

C.2.5.2.5. Smialowicz et al. (2008).

output 0clear

This document is a draft for review purposes only and does not constitute Agency policy.

C-83 DRAFT—DO NOT CITE OR QUOTE


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prepare 0clear

prepare T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG CBNGKG

% Smialowicz et al. 2008.

%built and check in August 7 2009

%protocol: oral gavage 5 days/week for 13 weeks
%Mice Dioxin 3C June09 l.csl

%MICE~NON_GESTAT_ICF_F083109.csl (now 09-11-09)

%dose levels: 0, 0.0015, 0.015, 0.15, 0.45 ug/kg

%dose levels: 0, 1.5, 15, 150, 450 nkd (0, 1.07, 10.7, 107, 321 nkd adj)

MAXT	= 0.01

CINT	=0.1

TIMELIMIT	= 2184

EXP_TIME_ON	= 0.

EX P_TIME_0 FF	= 2184

DAY_CYCLE	= 2 4

WEEK_PERIOD	= 168

WEEK_FINISH	= 119

B C K_TIME_ON	= 0.

BCK_TIME_OFF	= 0.

BW_T0	=28

(g)

iSIMULATION LIMIT TIME (HOUR)
idelay before begin exposure (HOUR)
iTIME EXPOSURE STOP (HOUR)

¦;DELAY BEFORE BACGROUND EXPOSURE (HOUR)

iTIME OF BACKGROUND EXPOSURE STOP (HOUR)

i Body weight at the beginning of the simulation

iEXPOSURE DOSE SCENARIOS
%MSTOT	= 0.0015

%MSTOT = 0.015
%MSTOT = 0.150
MSTOT = 0.450

(UG/KG)

% exposure dose (ug/kg)
% exposure dose (ug/kg)
% exposure dose (ug/kg)
% exposure dose (ug/kg)

C.2.5.2.6. Toth et al. (1979) (1 year).

output 0clear
prepare 0clear

prepare T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG CBNGKG

% Toth et al. 1979
%built and check in August 7 2009
%protocol: weekly gavage for 1 year
%Mice Dioxin 3C June09 l.csl

%MICE_NON_GESTAT_ICF_F083109.csl (now 09-11-09)

%dose levels: 7, 700, 7000 ng/kg 1/week for 52 weeks (1 year)
%dose levels: 0.007, 0.7, 7 ug/kg 1/week for 52 weeks (1 year)
%dose equivalent: 1, 100, 1000 ng/kg/day

MAXT	= 0.01

CINT	=0.1

TIMELIMIT = 8760
EXP_TIME_ON = 0.
EX P_TIME_0 FF = 8760
DAY_CYCLE = 168
WEEK_PERIOD = 8760
WEEK_FINISH = 8760
B C K_TIME_ON = 0.
BCK TIME OFF = 0.

idelay before begin exposure (HOUR)
i2208 %TIME EXPOSURE STOP (HOUR)

¦;DELAY BEFORE BACGROUND EXPOSURE (HOUR)
iTIME OF BACKGROUND EXPOSURE STOP (HOUR)

This document is a draft for review purposes only and does not constitute Agency policy.

C-84 DRAFT—DO NOT CITE OR QUOTE


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BW_T0

(g)

= 27

% Body weight at the beginning of the simulation

%EXPOSURE DOSE SCENARIOS (UG/KG)

%MSTOT = 0.007	% exposure dose (ug/kg)

%MSTOT =0.7	% exposure dose (ug/kg)

MSTOT =7	% exposure dose (ug/kg)

C.2.5.2.7. White et al (1986).

output 0clear
prepare 0clear

prepare T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CBNDLINGKG

% White et al 1986

%built and check in August 7 2009

%protocol: oral exposure single dose

%dose levels: 0.714, 3.57, 7.14, 35.71, 71.43, 142.86 ng /kg/d ug/kg 1/day
for 14 consecutive days

%dose have been modified following Jeff email on Friday August 21 2009
%dose levels: 10, 50, 100, 500, 1000, 2000 ng /kg/d ug/kg 1/day for 14
consecutive days

%dose levels: 0.010, 0.050, 0.100, 0.500, 1.0, 2.0 ug /kg/d ug/kg 1/day for
14 consecutive days

MAXT

=

o
o

I—1

CINT

=

0.1

TIMELIMIT

=

336

EXP TIME ON

=

0.

EXP TIME OFF

=

336

DAY CYCLE

=

24

WEEK PERIOD

=

336

WEEK FINISH

=

336

BCK TIME ON

=

0.

BCK TIME OFF

=

0.

BW TO

=

23

iTIME AT WHICH EXPOSURE BEGINS (HOUR)
iTIME AT WHICH EXPOSURE ENDS (HOUR)

iTIME AT WHICH BACKGROUND EXPOSURE BEGINS (HOUR)
iTIME AT WHICH BACKGROUND EXPOSURE ENDS (HOUR)
i BODY WEIGHT AT THE BEGINNING OF THE SIMULATION

(G)

iEXPOSURE
%MSTOT
%MSTOT
%MSTOT
%MSTOT
%MSTOT
MSTOT

DOSE SCENARIOS
= 0.010
= 0.050
= 0.100
= 0.500
= 1
= 2	%

(UG/KG)

% EXPOSURE DOSE IN UG/KG
i EXPOSURE DOSE IN UG/KG
i EXPOSURE DOSE IN UG/KG
i EXPOSURE DOSE IN UG/KG
i EXPOSURE DOSE IN UG/KG
EXPOSURE DOSE IN UG/KG

C.2.6. Mouse Gestational Model
C.2.6.1. Model Code

PROGRAM: 'Three Compartment PBPK Model for TCDD in Mice (Gestation)'

! Parameters were change may 16, 2002
! Come from {8MAI_CHR_PRE-EXP_GD}

This document is a draft for review purposes only and does not constitute Agency policy.

C-85 DRAFT—DO NOT CITE OR QUOTE


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! Come from {12 Mouse GDJfile

!{{IMPORTANT-IMPORTANT-IMPORTANT-IMPORTANT}}

! REDUCTION OF MOTHER AND FETUS COMPARTMENT
! 2M_R_TCDD_JULY2 0 02 ////(JULY 18,20 02)////
!TCDD_RED_4Species_2003_4	////(APR 8 ,2003)////

!TCDD_RED_4Species_2003_9	////(APR 17 ,2003)////

!TCDD_RED_4Species_2003_12	////(APR 17 ,2003)////

!APRIL 18 2003

!TCDD_4C_4SP_2 0 03	////(APR 18 ,2003)////

! was ''Gest 4 species l.csl'' but update July 2009

!DevTCDD4Species ICF afterKKfix v3 ratgest.csl
!MICE_GESTATIONAL_ICF_F092309.csl ~
!MICE_GESTATIONAL_ICF_Fl00 609. csl

!Legend/Legend/Legend/Legend/Legend/Legend/Legend/Legend/

!Legend for this PBPK model

IMating: control the tenure of exchange between fetus and
IMother and also control imitated tissue growth
!Ctrl: WTFE, WFO, WPLA0, QPLAF,WTO
!(for rat, mouse, human, and monkey)

!Control transfer from mother to fetus and fetus to mother by TRANSTIME ON
!SWITCH_trans = 0 NO TRANSFER	~

!SWITCH_trans = 1 TRANSFER OCCURS
!Gest off = 1
!Gest on= 0.

! These switches are also controlled by mating parameters
INITIAL !

!SIMULATION PARAMETERS ====
CONSTANT PARA_ZERO	= 1E-30

CONSTANT EXP_TIME_ON	= 288.

CONSTANT EXP_TIME_0FF	= 504

CONSTANT DAY_CYCLE	= 504.

CONSTANT BCK_TIME_ON	=0.0
BEGINS (HOURS)

CONSTANT BCK_TIME_OFF	=0.0
(HOURS)

CONSTANT TRANSTIME_ON	= 144
AT GESTATIONAL DAY 6

! TIME AT WHICH EXPOSURE BEGINS (HOURS)
! TIME AT WHICH EXPOSURE ENDS (HOURS)
! NUMBER OF HOURS BETWEEN DOSES (HOURS)
! TIME AT WHICH BACKGROUND EXPOSURE

! TIME AT WHICH BACKGROUND EXPOSURE ENDS

!CONTROL TRANSFER FROM MOTHER TO FETUS

!UNIT CONVERSION
CONSTANT MW=322 ! MOLECULAR WEIGHT (NG/NMOL)
CONSTANT SERBLO =0.55
CONSTANT UNITCORR = 1000

!INTRAVENOUS SEQUENCY
constant IV_LACK	=0.0

constant IV_PERIOD	=0.0

!PREGNANCY PARAMETER ====

CONSTANT MATTING	=0.0	!BEGINNING OF MATING (HOUR)

This document is a draft for review purposes only and does not constitute Agency policy.

C-86 DRAFT—DO NOT CITE OR QUOTE


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CONSTANT N_FETUS	=10	!NUMBER OF FETUS PRESENT

!CONSTANT EXPOSURE CONTROL ===========

!ACUTE, SUBCHRONIC, CHRONIC EXPOSURE =====

!OR BACKGROUND EXPOSURE (IN THIS CASE 3 TIMES A DAY)===

CONSTANT MSTOTBCKGR	=0.0	! ORAL BACKGROUND EXPOSURE DOSE (UG/KG)

CONSTANT MSTOT	=0.0	! ORAL EXPOSURE DOSE (UG/KG)

!ORAL ABSORPTION
MSTOT NM = MSTOT/MW

!CONVERTS THE DOSE TO NMOL/G

! INTRAVENOUS ABSORPTION
CONSTANT DOSEIV	=0.0

DOSEIV_NM = DOSEIV/MW
CONSTANT DOSEIVLATE =0.0

DOSEIVNMlate = DOSEIVLATE/MW

! INJECTED DOSE (UG/KG)

! CONVERTS THE INJECTED DOSE TO NMOL/G

! INJECTED DOSE LATE (UG/KG)

!AMOUNT IN NMOL/G

!INITIAL GUESS OF THE FREE CONCENTRATION IN THE LIGAND (COMPARTMENT
INDICATED BELOW)====

CONSTANT CFLLI0	=0.0 !LIVER (NMOL/ML)

CONSTANT CFLPLA0	=0.0 !PLACENTA (NMOL/ML)

!BINDING CAPACITY	(AhR) FOR NON LINEAR BINDING (COMPARTMENT INDICATED
BELOW) (NMOL/ML) ===

CONSTANT LIBMAX	= 3.5E-4 ! LIVER (NMOL/ML), WANG ET AL. 1997

CONSTANT PLABMAX	= 2.OE-4 !TEMPORARY PARAMETER

! PROTEIN AFFINITY CONSTANTS (1A2 OR AhR, COMPARTMENT INDICATED BELOW)
(NMOL/ML)===

CONSTANT KDLI	= 1.0E-4 !LIVER (AhR) (NMOL/ML), WANG ET AL. 1997

CONSTANT KDLI2	= 4.OE-2 !LIVER (1A2) (NMOL/ML), EMOND ET AL. 2004

CONSTANT KDPLA	= 1.0E-4 !TEMPORARY PARAMETER (AhR)

!EXCRETION AND ABSORPTION	CONSTANT

CONSTANT KST	=	0.3 ! GASTRIC RATE CONSTANT (HR-1)

CONSTANT KABS	=	0.48 !INTESTINAL ABSORPTION CONSTANT (HR-1) ),

WANG ET AL. 1997

! ELIMINATION CONSTANTS

CONSTANT CLURI	=	0.09 ! URINARY CLEARANCE (ML/HR)

!TEST ELIMINATION VARIABLE
constant kelv	=	0.4	! INTERSPECIES VARIABLE ELIMINATION

CONSTANT (1/HOUR)

! CONSTANT TO DIVIDE THE ABSORPTION INTO LYMPHATIC AND PORTAL FRACTIONS
CONSTANT A	=0.7	! LYMPHATIC FRACTION, WANG ET AL. 1997

!PARTITION COEFFICIENTS
CONSTANT PF	= 400

CONSTANT PRE	= 3

CONSTANT PLI	= 6

CONSTANT PPLA	= 3

! ADIPOSE TISSUE/BLOOD

! REST OF THE BODY/BLOOD, WANG ET AL. 2000
! LIVER/BLOOD, WANG ET AL. 19 97
! TEMPORARY PARAMETER NOT CONFIGURED

!PARAMETER FOR INDUCTION OF CYP 1A2, WANG ET AL. 1997 OR OPTIMIZED
CONSTANT PAS INDUC	= 1	! INCLUDE INDUCTION? (1 = YES, 0 = NO)

This document is a draft for review purposes only and does not constitute Agency policy.

C-87 DRAFT—DO NOT CITE OR QUOTE


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CONSTANT CYP1A2_10UTZ = 1.6
1A2 (NMOL/ML) (OPTIMIZED)
CONSTANT CYP1A2_1A1
WANG ET AL . (2 000)

CONSTANT CYP1A2_1EC5 0
(NMOL/ML)

CONSTANT CYP1A2 1A2

= 1.5
= 0. 13

= 1.5

(NMOL/ML),WANG ET AL.	(2000)

CONSTANT CYP1A2_1K0UT	=0.1

CONSTANT CYP1A2_1TAU	=1.5
. (2000)

CONSTANT CYP1A2_1EMAX	= 600
(UNITLESS)

CONSTANT HILL	=0.6
BINDING EFFECT CONSTANT (UNITLESS)

! DEGRADATION CONCENTRATION CONSTANT OF

! BASAL CONCENTRATION OF 1A1 (NMOL/ML),

! DISSOCIATION CONSTANT TCDD-CYP1A2

!BASAL CONCENTRATION OF 1A2

! FIRST ORDER RATE OF DEGRADATION (H-l)
!HOLDING TIME (H) (OPTIMIZED), WANG ET AL

! MAXIMUM INDUCTION OVER BASAL EFFECT

!HILL CONSTANT; COOPERATIVELY LIGAND

!DIFFUSIONAL PERMEABILITY FRACTION, WANG ET AL. 1997
CONSTANT PAFF	=0.12 !ADIPOSE (UNITLESS) OPTIMIZED, WANG ET AL.

2000

CONSTANT PAREF	=0.03 !REST OF THE BODY (UNITLESS)

CONSTANT PALIF	=0.35 !LIVER (UNITLESS)

CONSTANT PAPLAF	=0.03 !TEMPORARY PARAMETER NOT CONFIGURED

!FRACTION OF TISSUE WEIGHT =========

CONSTANT WLI0	= 0.0549 !LIVER ILSI (1994)

!TISSUE BLOOD FLOW EXPRESSED AS A FRACTION OF CARDIAC OUTPUT CONSTANT QFF
= 0.070 ! ADIPOSE TISSUE BLOOD FLOW FRACTION (UNITLESS), LEUNG ET AL. 1990
CONSTANT QLIF	= 0.161 !LIVER (UNITLESS), ILSI 1994

!COMPARTMENT TISSUE BLOOD EXPRESSED AS A FRACTION OF THE TOTAL COMPARTMENT
VOLUME

CONSTANT WFB0	= 0.050 IADIPOSE TISSUE, WANG ET AL. 1997

CONSTANT WREB0	= 0.030 !REST OF THE BODY, WANG ET AL. 1997

CONSTANT WLIB0	= 0.266 !LIVER, WANG ET AL. 1997

CONSTANT WPLAB0	= 0.500 !TEMPORARY PARAMETER NOT CONFIGURED

!EXPOSURE SCENARIO FOR UNIQUE OR REPETITIVE WEEKLY OR MONTHLY EXPOSURE

!NUMBER OF EXPOSURES	PER WEEK

CONSTANT WEEK_LACK	=0.0

CONSTANT WEEK_PERIOD	= 168

CONSTANT WEEK FINISH	= 168

!DELAY BEFORE EXPOSURE ENDS (WEEK)
! NUMBER OF HOURS IN THE WEEK (HOURS)
! TIME EXPOSURE ENDS (HOURS)

!NUMBER OF EXPOSURES PER MONTH
CONSTANT MONTH LACK	=0.0

!DELAY BEFORE EXPOSURE BEGINS (MONTH)

!CONSTANT FOR BACKGROUND EXPOSURE=

CONSTANT Day_LACK_BG	=0.0

CONSTANT Day_PERIOD_BG =24

! DELAY BEFORE EXPOSURE BEGINS (HOUR)
!LENGTH OF EXPOSURE (HOUR)

!NUMBER OF EXPOSURES PER WEEK

CONSTANT WEEK_LACK_BG
CONSTANT WEEK_PERIOD_BG
CONSTANT WEEK FINISH BG

0.0
168
168

!DELAY BEFORE BACKGROUD EXPOSURE (WEEK)
! NUMBER OF HOURS IN THE WEEK (HOURS)
!TIME EXPOSURE ENDS (HOURS)

!INITIAL BODY WEIGHT

This document is a draft for review purposes only and does not constitute Agency policy.

C-88 DRAFT—DO NOT CITE OR QUOTE


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CONSTANT BW_T0	=30

CONSTANT RAT10_RATF_MOUSEF = 0.2
GESTATIONAL DAY 22

! WANG ET AL. 1997

!RATIO OF FETUS MOUSE/RAT AT

! FOR RAT (1) AND FOR MOUSE (0.2)

!COMPARTMENT LIPID EXPRESSED AS THE FRACTION OF TOTAL LIPID, POULIN ET AL.
2000

CONSTANT F_TOTLIP
CONSTANT B_TOTLIP
CONSTANT RE_TOTLIP
(UNITLESS)

CONSTANT LI_TOTLIP
CONSTANT PLA_TOTLIP
CONSTANT FETUS TOTLIP

855

0033

019

060
019

= 0.019

! ADIPOSE TISSUE (UNITLESS)

! BLOOD (UNITLESS)

! REST OF THE BODY

! LIVER (UNITLESS)
! PLACENTA (UNITLESS)
! FETUS (UNITLESS)

END

! END OF THE INITIAL SECTION

DYNAMIC ! DYNAMIC SIMULATION SECTION

ALGORITHM

CINTERVAL

MAXTERVAL

MINTERVAL

VARIABLE

CONSTANT

IALG
CINT
MAXT
MINT
T

TIMELIMIT

CINTXY = CINT

2
0.1
1.0e+10
1.0E-10
0.0
313

GEAR METHOD

COMMUNICATION INTERVAL
MAXIMUM CALCULATION INTERVAL
MINIMUM CALCULATION INTERVAL

!SIMULATION LIMIT TIME (HOUR)

PFUNC

= CINT

!TIME CONVERSION

DAY
WEEK
MONTH
YEAR

= T/24
= T/168
= T/730
= T/87 60

TIME IN DAYS
TIME IN WEEKS
TIME IN MONTHS
TIME IN YEARS

DERIVATIVE ! PORTION OF CODE THAT SOLVES DIFFERENTIAL EQUATIONS

!CHRONIC OR SUBCHRONIC EXPOSURE SCENARIO
!NUMBER OF EXPOSURES PER DAY

DAY_LACK
DAY_PERIOD
DAY_FINISH
MONTH_PERIOD
MONTH FINISH

= EXP_TIME_ON
= DAY_CYCLE
= CINTXY
= TIMELIMIT
= EXP TIME OFF

DELAY BEFORE EXPOSURE BEGINS (HOURS)
EXPOSURE PERIOD (HOURS)

LENGTH OF EXPOSURE (HOURS)

EXPOSURE PERIOD (MONTHS)

LENGTH OF EXPOSURE (MONTHS)

!NUMBER OF EXPOSURES PER DAY AND MONTH

DAY_FINISH_BG
MONTH_LACK_BG
(MONTHS)

MONTH_PERIOD_BG
MONTH FINISH BG

= CINTXY
= B C K_TIME_ON

= TIMELIMIT
= BCK TIME OFF

!DELAY BEFORE BACKGROUD EXPOSURE BEGINS

!BACKGROUND EXPOSURE PERIOD (MONTHS)
!LENGTH OF BACKGROUND EXPOSURE (MONTHS)

!INTRAVENOUS LATE
IV_FINISH = CINTXY

B = 1-A ! FRACTION OF DIOXIN ABSORBED IN THE PORTAL FRACTION OF THE LIVER

This document is a draft for review purposes only and does not constitute Agency policy.

C-89 DRAFT—DO NOT CITE OR QUOTE


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!FETUS,VOLUME,FETUS,VOLUME,FETUS,VOLUME,FETUS,VOLUME,FETUS,VOLUME,FETUS,VOLUM
E

! FROM OFLAHERTY_19 92

RTESTGEST= T-MATTING
TESTGEST=DIM(RTESTGEST,0.0)

WTFER_RODENT= (2.3d-3*EXP(1.49d-2*(TESTGEST))+1.3d-2)*Gest_on
WTFER = (WTFER_RODENT*RATIO_RATF_MOUSEF*N_FETUS)

WTFE = DIM(WTFER,0.0)

!

FAT,VOLUME,FAT,VOLUME,FAT,VOLUME,FAT,VOLUME,FAT,VOLUME,FAT,VOLUME,FAT,VOLUME
! FAT GROWTH EXPRESSION LINEAR DURING PREGNANCY
! FROM O'FLAHERTY_19 92

WF0= (((9.66d-5*(TESTGEST))*gest_on)+0.069)

! PLACENTA,VOLUME, PLACENTA,VOLUME, PLACENTA,VOLUME, PLACENTA,VOLUME
! WPLA PLACENTA GROWTH EXPRESSION, SINGLE EXPONENTIAL WITH OFFSET
! FROM O'FLAHERTY_19 92 ! FOR EACH PUP

WPLA0N_RODENT = (0.6/(1+(5d+3*EXP(-0.0225*(TESTGEST)))))*N_FETUS
WPLA0R = (WPLA0N_RODENT/WT0)*Gest_on
WPLA0 = DIM(WPLA0R,0.0)

! PLACENTA,FLOW RATE, PLACENTA,FLOW RATE, PLACENTA,FLOW RATE, PLACENTA,FLOW
RATE

! QPLA PLACENTA GROWTH EXPRESSION, DOUBLE EXPONENTIAL WITH OFFSET
! FROM O'FLAHERTY_19 92

QPLARF = (1.67d-7 *exp(9.6d-3*(TESTGEST)) &

+1.6d-3*exp(7.9d-3*(TESTGEST))+0.0)*Gest_on*SWITCH_trans
QPLAF=DIM(QPLARF,0.0)	!FRACTION OF FLOW RATE IN PLACENTA

! GESTATION CONTROL
IF (T.LT.MATTING) THEN
Gest off = 1
Gest on= 0 . 0
ELSE ~

Gest off = 0.0
Gest on =1
END IF ~

! MOTHER BODY WEIGHT GROWTH EQUATION========

! MODIFICATION TO ADAPT THIS MODEL AT HUMAN MODEL

! BECAUSE LINEAR DESCRIPTION IS NOT GOOD ENOUGH FOR MOTHER GROWTH
! MOTHER BODY WEIGHT GROWTH

PARAMETER (BW_RMN = 1.0E-30)

WT0= BW_T0 *(1.0+(0.41*T)/(1402.5+T+BW_RMN))

! VARIABILITY OF REST OF THE BODY DEPENDS ON OTHER ORGANS
WRE0 = (0.91 - (WLIB0*WLI0 + WFB0*WF0 +WPLAB0*WPLA0 + WLI0 + WF0 +
WPLA0))/(1.0+WREB0) ! REST OF THE BODY FRACTION; UPDATED FOR EPA ASSESSMENT

This document is a draft for review purposes only and does not constitute Agency policy.

C-90 DRAFT—DO NOT CITE OR QUOTE


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QREF = 1.0-(QFF+QLIF+QPLAF)
(ML/HR)

QTTQF = QFF+QREF+QLIF+QPLAF

!REST OF BODY BLOOD FLOW RATE
! SUM MUST EQUAL 1

! COMPARTMENT VOLUME (ML OR G)
WF = WF0 * WTO
WRE = WRE0 * WTO
WLI = WLI0 * WTO
WPLA= WPLAO* WTO

ADIPOSE TISSUE
REST OF THE BODY
LIVER
PLACENTA

! COMPARTMENT TISSUE BLOOD	(ML OR G)

WFB = WFBO * WF	!

WREB = WREBO * WRE	!

WLIB = WLIBO * WLI	!

WPLAB = WPLABO* WPLA	!

ADIPOSE TISSUE
REST OF THE BODY
LIVER
PLACANTA

! CARDIAC OUTPUT FOR THE GIVEN BODY WEIGHT
!QC= QCCAR* 60*(WTO/1000.0)**0.75
CONSTANT QCC=16500	! EQUIVALENT TO 275 * 60

QC= QCC*(WTO/UNITCORR)**0.75

!COMPARTMENT BLOOD FLOW RATE (ML/HR)

QF = QFF*QC

QLI = QLIF*QC

QRE = QREF*QC

QPLA = QPLAF*QC

QTTQ = QF+QRE+QLI+QPLA

!ADIPOSE TISSUE BLOOD FLOW RATE
!LIVER TISSUE BLOOD FLOW RATE
!REST OF THE BODY BLOOD FLOW RATE
!PLACENTA TISSUE BLOOD FLOW RATE
!TOTAL FLOW RATE

!PERMEABILITY ORGAN FLOW (ML/HR)
PAF = PAFF*QF
PARE = PAREF*QRE
PALI = PALIF*QLI
PAPLA = PAPLAF*QPLA

ADIPOSE TISSUE
REST OF THE BODY
LIVER TISSUE
PLACENTA

ABSORPTION SECTION
ORAL,

INTRAPERITONEAL,
INTRAVENOUS

!REPETITIVE ORAL BACKGROUND EXPOSURE SCENARIO

MSTOT_NMBCKGR = MSTOTBCKGR/322	!AMOUNT IN NMOL/G

MSTTBCKGR =MSTOT_NMBCKGR *WT0

DAY_EX P O S U RE_B G = PULSE(DAY_LACK_BG,DAY_PERIOD_BG,DAY_FINISH_BG)
WEEK_EXPOSURE_BG = PULSE(WEEK_LACK_BG,WEEK_PERIOD_BG,WEEK_FINISH_BG)
MONTH_EXPOSURE_BG = PULSE(MONTH_LACK_BG,MONTH_PERIOD_BG,MONTH_FINISH_BG)

MSTTCH_BG = (DAY_EXPOSURE_BG*WEEK_EXPOSURE_BG*MONTH_EXPOSURE_BG)*MSTTBCKGR
MSTTFR_BG = MSTTBCKGR/CINT

CYCLE_BG =DAY_EXPOSURE_BG*WEEK_EXPOSURE_BG*MONTH_EXPOSURE_BG

! CONDITIONAL ORAL EXPOSURE (BACKGROUND EXPOSURE)

This document is a draft for review purposes only and does not constitute Agency policy.

C-91 DRAFT—DO NOT CITE OR QUOTE


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IF (MSTTCH_BG.EQ.MSTTBCKGR) THEN
ABSMSTT_GB= MSTTFR_BG

ELSE

ABSMSTT_GB =0.0
END IF

CYCLETOTBG=INTEG(CYCLE_BG,0.0)

!REPETITIVE ORAL EXPOSURE SCENARIO

MSTT= MSTOT_NM * WTO	!AMOUNT IN NMOL

DAY_EXPOSURE = PULSE(DAY_LACK,DAY_PERIOD,DAY_FINISH)

WEEK_EXPOSURE = PULSE(WEEK_LACK,WEEK_PERIOD,WEEK_FINISH)
MONTH_EXPOSURE = PULSE(MONTH_LACK,MONTH_PERIOD,MONTH_FINISH)

MSTTCH = (DAY_EXPOSURE*WEEK_EXPOSURE*MONTH_EXPOSURE)*MSTT
MSTTFR = MSTT/CINT

CYCLE = DAY_EXPOSURE*WEEK_EXPOSURE*MONTH_EXPOSURE

SUMEXPEVENT= INTEG (CYCLE,0.0)/cint !NUMBER OF CYCLES GENERATED DURING
SIMULATION

! CONDITIONAL ORAL EXPOSURE
IF (MSTTCH.EQ.MSTT) THEN

ABSMSTT= MSTTFR
ELSE

ABSMSTT =0.0
END IF

CYCLETOT=INTEG(CYCLE, 0.0)

! MASS CHANGE IN THE LUMEN
RMSTT= -(KST+KABS)*MST +ABSMSTT +ABSMSTT_GB ! RATE OF CHANGE (NMOL/H)

MST = INTEG(RMSTT,0.0)	!AMOUNT REMAINING IN DUODENUM

(NMOL)

! ABSORPTION IN LYMPH CIRCULATION
LYRMLUM = KABS*MST*A
LYMLUM = INTEG(LYRMLUM,0.0)

! ABSORPTION IN PORTAL CIRCULATION
LIRMLUM = KABS*MST*B
LIMLUM = INTEG(LIRMLUM,0.0)

	IV EXPOSURE 	

IV= DOSEIV_NM * WTO !AMOUNT IN NMOL
IVR= IV/PFUNC ! RATE FOR IV INFUSION IN BLOOD
EXPIV= IVR * (1.0-STEP(PFUNC))

IVDOSE = integ(EXPIV,0.0)

!	IV late in the cycle

This document is a draft for review purposes only and does not constitute Agency policy.

C-92 DRAFT—DO NOT CITE OR QUOTE


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! MODIFICATION ON January 13 2004
IV_RlateR = DOSEIVNMlate*WTO

IV_EXPOSURE=PULSE(IV_LACK,IV_PERIOD,IV_FINISH)

IV_lateT = IV_EXPOSURE *IV_RlateR
IV_late = IV_lateT/CINT

SUMEXPEVENTIV= integ (IV_EXPOSURE,0.0) !NUMBER OF CYCLE GENERATE DURING
SIMULATION

!SYSTEMIC CONCENTRATION OF TCDD
! MODIFICATION ON OCTOBER 6, 2009
CB=(QF*CFB+QRE*CREB+QLI*CLIB+EXPIV+LYRMLUM+QPLA*CPLAB+IV_late)/(QC+CLURI) !
CA = CB ! CONCENTRATION (NMOL/ML)

!URINARY EXCRETION BY KIDNEY
!MODIFICATION ON OCTOBER 6, 2009
RAURI = CLURI *CB

AURI = INTEG(RAURI,0.0)

!UNIT CONVERSION POST SIMULATION
CBSNGKGLIADJ=(CB*MW*UNITCORR*(l/B_TOTLIP)*(1/SERBLO))![NG of TCDD Serum/Kg
OF LIPIP]

AUCBS_NGKGLIADJ=integ(CBSNGKGLIADJ,0.0)

PRCT_B = (CB/(MSTT+1E-30))*100 ! PERCENT OF ORAL DOSE IN BLOOD
PRCT_BIV = (CB/(IV_RlateR+lE-30))*100 ! PERCENT OF IV DOSE IN BLOOD
CBNGKG= CB*MW*UNITCORR
CBNGG = CB*MW

!ADIPOSE COMPARTMENT
! TISSUE BLOOD COMPARTMENT
RAFB= QF*(CA-CFB)-PAF*(CFB-CF/PF)
AFB = INTEG(RAFB,0.0)
CFB = AFB/WFB
! TISSUE COMPARTMENT
RAF = PAF*(CFB-CF/PF)
AF = INTEG(RAF,0.0)

CF = AF/WF

!(NMOL/H)
!(NMOL)
!(NMOL/ML)

!(NMOL/H)
!(NMOL)

(NMOL/ML)

!UNIT CONVERSION POST SIMULATION
CFTOTAL= (AF + AFB)/(WF + WFB) ! TOTAL CONCENTRATION IN NMOL/ML
CFTFREE = CFB + CF !TOTAL FREE CONCENTRATION IN FAT (NM/ML)

PRCT_F = (CFTOTAL/(MSTT+1E-30))*100 ! PERCENT OF ORAL DOSE IN FAT
PRCT_FIV = (CFTOTAL/(IV_RlateR+lE-30))*100 ! PERCENT OF IV DOSE IN FAT
CFNGKG=CFTOTAL*MW*UNITCORR ! FAT CONCENTRATION IN NG/KG

AUCF_NGKGH=integ(CFNGKG, 0.0)

CFNGG = CFTOTAL*MW

!REST OF THE BODY COMPARTMENT
RAREB= QRE *(CA-CREB)-PARE*(CREB-CRE/PRE)
AREB = INTEG(RAREB,0.0)

CREB = AREB/WREB
!TISSUE COMPARTMENT
RARE = PARE*(CREB - CRE/PRE)
ARE = INTEG(RARE,0.0)

(NMOL/H)
!(NMOL)
!(NMOL/H)

(NMOL/H)
(NMOL)

This document is a draft for review purposes only and does not constitute Agency policy.

C-93 DRAFT—DO NOT CITE OR QUOTE


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CRE = ARE/WRE

!(NMOL/ML)

!UNIT CONVERSION POST SIMULATION
CRETOTAL= (ARE + AREB)/(WRE + WREB)	! TOTAL CONCENTRATION IN

NMOL/ML

PRCT_RE = (CRETOTAL/(MSTT+1E-30))*100 ! PERCENT OF ORAL DOSE IN REST OF
BODY

PRCT_REIV = (CRETOTAL/(IV_RlateR+lE-30))*100 ![ PERCENT OF IV DOSE IN
REST OF THE BODY ]

CRENGKG=CRETOTAL*MW*UNITCORR ! REST OF THE BODY CONCENTRATION IN NG/KG

!LIVER COMPARTMENT
!TISSUE BLOOD COMPARTMENT
RALIB = QLI*(CA-CLIB)-PALI*(CLIB-CFLLIR)+LIRMLUM !

ALIB = INTEG(RALIB,0.0)	!(NMOL)

CLIB = ALIB/WLIB	!(NMOL/ML)

!TISSUE COMPARTMENT
RALI = PALI*(CLIB - CFLLIR)-REXCLI	! (NMOL/HR)

ALI = INTEG(RALI,0.0)	!(NMOL)

CLI = ALI/WLI	!(NMOL/ML)

!FREE TCDD IN LIVER COMPARTMENT
PARAMETER (LIVER_1RMN = 1.0E-30)

CFLLI= IMPLC(CLI-(CFLLIR*PLI+(LIBMAX*CFLLIR/(KDLI+CFLLIR &
+LIVER_1RMN))+((CYP1A2_103*CFLLIR/(KDLI2 + CFLLIR &
+LIVER_1RMN)*PAS_INDUC)))-CFLLI,CFLLI0)

CFLLIR=DIM(CFLLI,0.0) ! FREE CONCENTRATION IN LIVER

CBNDLI= LIBMAX*CFLLIR/(KDLI+CFLLIR+LIVER_1RMN) !BOUND CONCENTRATION

!VARIABLE ELIMINATION BASED ON THE CYP1A2
KBILE_LI_T =((CYP1A2_10UT-CYP1A2_1A2)/CYP1A2_1A2)*Kelv ! INDUCED BILIARY
EXCRETION RATE CONSTANT

REXCLI = KBILE_LI_T*CFLLIR*WLI ! DOSE-DEPENDENT EXCRETION RATE
EXCLI = INTEG(REXCLI,0.0)

!UNIT CONVERSION POST SIMULATION

CLITOTAL= (ALI + ALIB)/(WLI + WLIB) ! TOTAL CONCENTRATION IN NMOL/ML
PRCT_LI = (CLITOTAL/(MSTT+1E-30))*100 ! PERCENT ORAL DOSE IN LIVER
PRCT_LIIV = (CLITOTAL/(IV_RlateR+lE-30))*100 ! PERCENT IV DOSE IN LIVER
Rec_occ= CFLLIR/(KDLI+CFLLIR)

CLINGKG=CLITOTAL*MW*UNITCORR ! LIVER CONCENTRATION IN NG/KG

AUCLI_NGKGH=INTEG(CLINGKG, 0.0)

CBNDLINGKG = CBNDLI*MW*UNITCORR

AUCBNDLI_NGKGH =INTEG(CBNDLINGKG,0.0)

CLINGG = CLITOTAL*MW

!CHEMICAL IN CYP450 (1A2) COMPARTMENT
CYP1A2_1KINP = CYP1A2_1K0UT* CYP1A2_10UTZ ! BASAL RATE OF CYP1A2 PRODUCTION
SET EQUAL TO BASAL RATE OF DEGREDATION

! MODIFICATION ON OCTOBER 6, 2009
CYP1A2_10UT =INTEG(CYP1A2_1KINP * (1.0 + CYP1A2_1EMAX *(CBNDLI+1.0e-30)**HILL
&

/(CYP1A2_1EC50**HILL + (CBNDLI+1.0e-30)**HILL)) &

This document is a draft for review purposes only and does not constitute Agency policy.

C-94 DRAFT—DO NOT CITE OR QUOTE


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- CYP1A2_1K0UT*CYP1A2_10UT, CYP1A2_10UTZ)

! EQUATIONS INCORPORATING DELAY OF CYP1A2 PRODUCTION (NOT USED IN
SIMULATIONS)

CYP1A2_1R02 = (CYP1A2_10UT - CYP1A2_102)/ CYP1A2_1TAU
CYP1A2_102 =INTEG(CYP1A2_1R02, CYP1A2_1A1)

CYP1A2_1R03 = (CYP1A2_102 - CYP1A2_103)/ CYP1A2_1TAU
CYP1A2_103 =INTEG(CYP1A2_1R03, CYP1A2_1A2)

! TRANSFER OF DIOXIN FROM PLACENTA TO FETUS
! FETAL EXPOSURE ONLY DURING EXPOSURE

IF (T.LT.TRANSTIME_ON) THEN

SWITCH_trans =0.0
ELSE

SWITCH_trans = 1
END IF

!TRANSFER OF DIOXIN FROM PLACENTA TO FETUS
! MODIFICATION 26 SEPTEMBER 2003

CONSTANT PFETUS= 4 !

CONSTANT CLPLA_FET =0.17 !

RAMPF = (CLPLA_FET*CPLA) *SWITCH_trans
AMPF=INTEG(RAMPF,0.0)

!TRANSFER OF DIOXIN FROM FETUS TO PLACENTA
RAFPM = (CLPLA_FET*CFETUS_v)* SWITCH_trans !

AFPM = INTEG(RAFPM,0.0)

! TCDD IN PLACENTA MOTHER COMPARTMENT

RAPLAB= QPLA*(CA - CPLAB) - PAPLA* (CPLAB -CFLPLAR) ! NMOL/H)

APLAB = INTEG(RAPLAB,0.0)	! (NMOL)

CPLAB = APLAB/(WPLAB+1E-30)	! (NMOL/ML)

RAPLA = PAPLA*(CPLAB-CFLPLAR)-RAMPF + RAFPM	! (NMOL/H)

APLA = INTEG(RAPLA,0.0)	! (NMOL)

CPLA = APLA/(WPLA+le-30)	! (NMOL/ML)

PARAMETER (PARA_ZERO = 1.0E-30)

CFLPLA= IMPLC(CPLA-(CFLPLAR*PPLA +(PLABMAX*CFLPLAR/(KDPLA&

+CFLPLAR+PARA_ZERO)))-CFLPLA,CFLPLA0)

CFLPLAR=DIM(CFLPLA,0.0)

!UNIT CONVERSION POST SIMULATION
CPLATOTAL= (APLA + APLAB)/((WPLA + WPLAB)+le-30)! TOTAL CONCENTRATION IN
NMOL/ML

PRCT_PLA = (CPLATOTAL/(MSTT+1E-30))*100
PRCT_PLAIV = (CPLATOTAL/(IV_RlateR+lE-30))*100
CPLANGG = CPLATOTAL*MW

!FETUS COMPARTMENT
RAFETUS= RAMPF-RAFPM
AFETUS=INTEG(RAFETUS,0.0)

This document is a draft for review purposes only and does not constitute Agency policy.

C-95 DRAFT—DO NOT CITE OR QUOTE


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CFETUS=AFETUS/(WTFE+1E-30)

CFETOTAL= CFETUS
CFETUS_v = CFETUS/PFETUS

! UNIT CONVERSION POST SIMULATION
CFETUSNGKG = CFETUS*MW*UNITCORR	!(NG/KG)

AU C_FEN GKGH = INTEG(CFETUSNGKG,0.0)

PRCT_FE = (CFETOTAL/(MSTT+1E-30))*100
PRCT_FEIV = (CFETOTAL/(IV_RlateR+lE-30))*100
CFETUSNGG = CFETOTAL*MW

! 	CONTROL MASS BALANCE	

BDOSE= IVDOSE +LYMLUM+LIMLUM

BMASSE = EXCLI+AURI+AFB+AF+AREB+ARE+ALIB+ALI+APLA+APLAB+AFETUS
BDIFF = BDOSE-BMASSE

!BODY BURDEN (NG)

BODY_BURDEN = AFB +AF+ARE B +ARE +ALIB+ALI+AP LA+AP LAB !

BBFETUSNG	= AFETUS*MW*UNITCORR ! NG

! BODY BURDEN IN TERMS OF CONCENTRATION (NG/KG)

BBNGKG =( ( (AFB+AF+AREB+ARE+ALIB+ALI+AP LA+AP LAB)/WTO)*MW*UNITCORR) !
AUC BBNGKGH=INTEG(BBNGKG,0.0)

! 	COMMAND OF THE END OF SIMULATION	

TERMT (T.GE. TimeLimit, 'Time limit has been reached.')

END ! END OF THE DERIVATIVE SECTION
END ! END OF THE DYNAMIC SECTION
END ! END OF THE PROGRAM

C.2.6.2. Input Files
C.2.6.2.1. Keller et al. (2007).

%clear variable
output 0clear

prepare 0clear T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CFETUSNGKG AUCLI_NGKGH
AUCF_NGKGH AUCBS_NGKGLIADJ AUC_BBNGKGH AUC_FENGKGH CBNDLINGKG AUCBNDLI_NGKGH
CBNGKG AUC CBNGKGH

% output 0nciout=lO T SUMEXPEVENT wtO
%Keller et al. 2007

%protocol: single oral dose at GD13
%DevTCDD4Species.csl
%MICE_GESTATIONAL_ICF_F092309.csl
%dose levels: 0.01, 0.100 1 ug/kg at GD13
%dose levels: 10, 100 1000 ng/kg at GD13

•;EXPOSURES SCENARIOS
MAXT=0 . 01
CINT =0.1

EXP_TIME_ON	= 312.

EX P_TIME_0 FF	= 336

DAY_CYCLE	=24

BCK TIME ON	=0.

delay before begin exposure (HOUR)

TIME EXPOSURE STOP (HOUR)

DELAY BEFORE BACGROUND EXPOSURE (HOUR)

This document is a draft for review purposes only and does not constitute Agency policy.

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55

BCK_TIME_OFF	= 0.

IV_LACK	= 5 05

IV_PERIOD	= 505

TIMELIMIT	= 336

BW_T0	= 24

MATTING	= 0.

TRANSTIME_ON	= 144.
HOURS)

N FETUS	=10

%EXPOSURE DOSE SCENARIOS (UG/KG)

TIME OF BACKGROUND EXPOSURE STOP (HOUR)

SIMULATION LIMIT TIME (HOUR)

BEGINNING MATTING (HOUR)

SHOULD BE MATTING TIME + 6 DAYS(144

%MSTOT
%MSTOT
MSTOT

= 0. 01
= 0.1
1

% ORAL EXPOSURE DOSE (UG/KG)
% ORAL EXPOSURE DOSE (UG/KG)
ORAL EXPOSURE DOSE (UG/KG)

C.2.6.2.2. Li et al. (2006).

%TO BE USED AFTER THE
%clear variable
output 0clear

prepare 0clear T CLINGKG CFNGKG CBSNGKGLIADJ BBNGKG CFETUSNGKG AUCLI_NGKGH
AUCF_NGKGH AUCBS_NGKGLIADJ AUC_BBNGKGH AUC_FENGKGH CBNDLINGKG AUCBNDLI_NGKGH
CBNGKG AUC_CBNGKGH
% output 0nciout=lO T SUMEXPEVENT
%Li et al.2006

%protocol: daily oral dose from GDI to GD3
%DevTCDD4Species.csl
%MICE_GESTATIONAL_ICF_F092309.csl

%dose levels: 0.002, 0.050, 0.10 ug/kg/day at GDI to GD3
%dose levels: 2, 50, 100 ng/kg/day from GDI to GD3

•;EXPOSURES SCENARIOS
MAXT=0 . 01
CINT =0.1
EXP_TIME_ON
EXP TIME OFF

= 0.
= 72

% delay before begin exposure (HOUR)
_ _	% TIME EXPOSURE STOP (HOUR) 2 HOURS LESS THAN

GD3 put 70 to be sure 3 doses will be administrate

% BECAUSE i STARTED TIME 0 FOR GDI

DAY_CYCLE
B C K_TIME_ON
BCK_TIME_OFF
IV_LACK
IV_PERIOD
TIMELIMIT
days
BW_T0
MATTING
TRANSTIME_ON
HOURS)

N FETUS

= 24
= 0.
= 0.
= 505
= 505
= 72.

= 27
= 0.
= 144.

= 10

DELAY BEFORE BACGROUND EXPOSURE (HOUR)
TIME OF BACKGROUND EXPOSURE STOP (HOUR)

SIMULATION LIMIT TIME (HOUR) Run for 3

BEGINNING MATTING (HOUR)

SHOULD BE MATTING TIME + 6 DAYS(144

iEXPOSURE DOSE SCENARIOS (UG/KG)

iMSTOT
iMSTOT

= 0.002
0. 05

% ORAL EXPOSURE DOSE (UG/KG)
ORAL EXPOSURE DOSE (UG/KG)

This document is a draft for review purposes only and does not constitute Agency policy.

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1	MSTOT	=0.10	% ORAL EXPOSURE DOSE (UG/KG)

2

3	C.3. TOXICOKINETIC MODELING RESULTS FOR KEY ANIMAL BIOASSAY

4	STUDIES

5	The simulated TCDD serum-adjusted lipid concentrations reported in this appendix for

6	the rodent bioassays were converted to TCDD concentrations in rodent whole blood. Initially,

7	EPA multiplied the serum-adjusted lipid concentrations by 0.0033, the ratio of lipid content to

8	total serum volume, then by 0.55, the value of the hematocrit. This product yields the TCDD

9	concentration in whole rodent blood as predicted by the PBPK model. EPA assumed that the

10	same whole blood TCDD concentration would result in the same effects in humans and rodents.

11	This conversion accomplishes the following:

12	1. Allows the human equivalent dose (HED) to be based on equivalent blood concentration

13	(that represents serum plus erythrocyte TCDD), which is proportional to tissue exposure;

14	2. Avoids criticism that the total blood concentration is normalized to serum lipid alone in

15	an unbalanced way (thus EPA does not contradict Centers for Disease Control and

16	Prevention (CDC) data or methods);

17	3. Factors out any impact of the lipid content used in the PBPK model; and

18	4. TCDD concentration in whole blood is encouraged for use in the assessments by the NAS

19	(NAS, 2006, p. 43); see additional information in Section 3.3.

20

21	C.3.1. Nongestational Studies

22	C.3.1.1. Cantoni et al. (1981)

Type:

Rat

Dose:

10, 100, 1000 ng/kg/week

Strain:

CD-COBS rats

Route:

Oral gavage exposure

Body weight:

BW set to 125g

Regime:

1 dose/week for 45 weeks

Sex:

Female

Simulation

7,560 hours





time:

(45 weeks)

23

WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1.43

Emond

1.85

^ 70 7.^02 hours')

1 82

CADM

-

-

-

14.29

Emond

8.84

26.6 (@ 7,392 hours)

7.97

This document is a draft for review purposes only and does not constitute Agency policy.

C-98 DRAFT—DO NOT CITE OR QUOTE


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CADM

-

-

-

142.86

Emond

50.0

227 (@ 7,392 hours)

41.9

CADM

-

-

-

LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1.43

Emond

247

328 (@ 7,398 hours)

242

CADM

374

431

431

14.29

Emond

2,176

2,860 (@ 7,231 hours)

1,928

CADM

3,884

4,330

4,330

142.86

Emond

20,500

26,978 (@ 7,399 hours)

17,255

CADM

39,067

43,329

43,329

FA T CONCENTRA TIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1.43

Emond

175

200 (@ 7,431 hours)

181

CADM

250

280

244

14.29

Emond

837

937 (@ 7,427 hours)

807

CADM

1,209

1,352

1,167

142.86

Emond

4,741

5,374 (@ 7,424 hours)

4,349

CADM

10,050

11,224

9,734

BODY BURDEN (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1.43

Emond

26.1

31.7 (@ 7,398 hours)

26.3

CADM

32.0

35.0

35.0

14.29

Emond

170

210 (@ 7,230 hours)

156

CADM

225

243

243

142.86

Emond

1,337

1,695 (@ 7,398 hours)

1,151

CADM

2,106

2,266

2,266

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-99 DRAFT—DO NOT CITE OR QUOTE


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BOUND LIVER (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1.43

Emond

6.04

7.76 (@. 7,396 hours)

6.01

CADM

-

-

-

14.29

Emond

23.7

29.1 (@. 7,228 hours)

22.2

CADM

-

-

-

142.86

Emond

66.8

80.0 ( a 1 hours)

63.4

CADM

-

-

-

1

2

3	C.3.1.2. Chuetal. (2007)

Type:

Rat

Dose:

2.5, 25, 250, and 1,000 ng/kg-day

Strain:

Sprague-Dawley

Route:

Oral exposure

Body weight:

200 g

Regime:

1 dose per day for 28 days

Sex:

Female

Simulation time:

672 hours

WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

2.5

Emond

1.26

2.35 (@. 648 hours)

1.88

CADM

-

-

-

25

Emond

7.66

15.3 (@, 648 hours)

10.4

CADM

-

-

-

250

Emond

48.8

113 (@, 648 hours)

63.7

CADM

-

-

-

1,000

Emond

169

418 (@, 648 hours)

222

CADM

-

-

-

LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

2.5

Emond

148

268 ( a 652 hours)

255

CADM

-

-

-

25

Emond

1,777

2,953 (@. 653 hours)

2,806

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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250

Emond

19,232

30,262 (@. 653 hours)

28,668

CADM

-

-

-

1,000

Emond

77,819

120,400 (@. 653 hours)

113,890

CADM

-

-

-

FA T CONCENTRA TIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

2.5

Emond

108

180 ( a 668 hours)

180

CADM

-

-

-

25

Emond

660

1,020 (@. 659 hours)

1,015

CADM

-

-

-

250

Emond

4,210

6,433 (@. 655 hours)

6,354

CADM

-

-

-

1,000

Emond

14,576

22,610 (@. 655 hours)

22,280

CADM

-

-

-

BODY BURDEN (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

2.5

Emond

16.1

27.5 (@. 652 hours)

26.9

CADM

-

-

-

25

Emond

138

222 ( a 652 hours)

214

CADM

-

-

-

250

Emond

1,239

1,935 (@. 652 hours)

1,842

CADM

-

-

-

1,000

Emond

4,801

7,444 (@. 652 hours)

7,067

CADM

-

-

-

BOUND LIVER (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

2.5

Emond

4.15

6.51 (@, 652 hours)

6.21

CADM

-

-

-

25

Emond

20.5

28.5 (@. 652 hours)

27.4

CADM

-

-

-

250

Emond

63.3

76.0 (@. 652 hours)

74.7

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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1,000

Emond

90.2

99.0 (@. 653 hours)

98.3

CADM

-

-

-

1 C.3.1.3. Crofton et ah (2005)

Type:

Rats

Dose:

0, 0.1, 3, 10, 30, 100, 300, 1000, 3000,
and 10,000 ng/kg-day

Strain:

Long Evans

Route:

Oral exposure

Body weight:

4 weeks old
BW set to 190 g

Regime:

One dose per day for four days

Sex:

Female

Simulation time:

96 hours

2	The CADM model was not ran because the dosing duration is lower than the resolution of the model (1 week)

3

WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

0.1

Emond

0.0202

0.041 (@. 72 hours)

0.0244

CADM

-

-

-

3

Emond

0.488

1.10 ( a 72 hours)

0.582

CADM

-

-

-

10

Emond

1.38

3.40 ( a 72 hours)

1.62

CADM

-

-

-

30

Emond

3.46

9.44 72 hours)

3.93

CADM

-

-

-

100

Emond

9.26

29.0 72 hours)

10.2

CADM

-

-

-

300

Emond

23.1

81.8 ( a 72 hours)

24.5

CADM

-

-

-

1000

Emond

65.7

260 ((ai 72 hours)

68.2

CADM

-

-

-

3000

Emond

181

764 ( a 72 hours)

187

CADM

-

-

-

10,000

Emond

583

2,527 (@. 72 hours)

607

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-102 DRAFT—DO NOT CITE OR QUOTE


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LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

0.1

Emond

0.919

1.55 ((ci\ 75 hours)

1.18

CADM

-

-

-

3

Emond

37.4

62.6 ( a 76 hours)

53.3

CADM

-

-

-

10

Emond

145

242 11 hours)

214

CADM

-

-

-

30

Emond

494

818 ((ai 78 hours)

742

CADM

-

-

-

100

Emond

1,839

3,025 78 hours)

2,793

CADM

-

-

-

300

Emond

5,925

9,692 78 hours)

9,028

CADM

-

-

-

1000

Emond

20,717

33,738 79 hours)

31,564

CADM

-

-

-

3000

Emond

63,511

103,140 79 hours)

96,545

CADM

-

-

-

10,000

Emond

212,890

344,910 79 hours)

321,960

CADM

-

-

-

FA T CONCENTRA TIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

0.1

Emond

1.00

1.93 ( a 96 hours)

1.93

CADM

-

-

-

3

Emond

24.6

45.9 ((ai 96 hours)

45.9

CADM

-

-

-

10

Emond

70.3

129 ((ci\ 96 hours)

129

CADM

-

-

-

30

Emond

177

317 ( a 96 hours)

317

CADM

-

-

-

100

Emond

480

838 ( a 96 hours)

838

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-103 DRAFT—DO NOT CITE OR QUOTE


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300

Emond

1,206

2,065 (@ 96 hours)

2,065

CADM

-

-

-

1000

Emond

3,452

5,836 (@ 96 hours)

5,836

CADM

-

-

-

3000

Emond

9,522

16,050 (@ 96 hours)

16,050

CADM

-

-

-

10,000

Emond

30,657

51,918 (@ 96 hours)

51,918

CADM

-

-

-

BODY BURDEN (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

0.1

Emond

0.138

0.224 (@ 79 hours)

0.223

CADM

-

-

-

3

Emond

4.04

6.56 ((ai 78 hours)

6.44

CADM

-

-

-

10

Emond

13.3

21.5 (@ 78 hours)

21.0

CADM

-

-

-

30

Emond

39.3

63.5 ((ai 78 hours)

61.5

CADM

-

-

-

100

Emond

129

208 ( a 78 hours)

200

CADM

-

-

-

300

Emond

384

618 ( a 11 hours)

590

CADM

-

-

-

1000

Emond

1,270

2,041 (@ 77 hours)

1,942

CADM

-

-

-

3000

Emond

3,793

6,094 (@ 77 hours)

5,784

CADM

-

-

-

10,000

Emond

12,595

20,226 (@ 77 hours)

19,154

CADM

-

-

-

BOUND LIVER (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

0.1

Emond

0

0.115 (@ 75 hours)

0

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-104 DRAFT—DO NOT CITE OR QUOTE


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3

Emond

2

2.47 (@. 76 hours)

2

CADM

-

-

-

10

Emond

4

6.42 ( a 76 hours)

5

CADM

-

-

-

30

Emond

10

14.1 ( a 76 hours)

12

CADM

-

-

-

100

Emond

22

29.9 (@. 76 hours)

27

CADM

-

-

-

300

Emond

41

51.9 ( a 77 hours)

49

CADM

-

-

-

1000

Emond

68

80.2 (@, 1 hours)

77

CADM

-

-

-

3000

Emond

90

98.6 ((ci\ 1 hours)

96

CADM

-

-

-

10,000

Emond

104

108 ( a 1 hours)

107

CADM

-

-

-

1

2

3	C.3.1.4. Delia Porta et a I. (2001) (female)

Type:

Mouse

Dose:

2,500 and 5,000 ng/kg-week (equivalent
to 357 and 714 ng/kg-day)

Strain:

B6C3

Route:

Gavage

Body weight:

6 weeks old (BW
20g)

Regime:

Once a week for 52 weeks

Sex:

Female

Simulation time:

8,736 hours

4	The C ADM model was not ran because the study duration is longer than the allowed model duration

5

WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

357

Emond

67.0

741 (@. 8,568 hours)

46.8

CADM

-

-

-

714

Emond

37.6

374 (@. 8,568 hours)

27.2

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-105 DRAFT—DO NOT CITE OR QUOTE


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LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

357

Emond

50,269

70,070 (@. 8,577 hours)

37,389

CADM

-

-

-

714

Emond

25,422

35,352 (@. 8,577 hours)

19,105

CADM

-

-

-

FA T CONCENTRA TIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

357

Emond

25,235

28,559 (@. 8,589 hours)

22,498

CADM

-

-

-

714

Emond

14,162

15,914 (@. 8,590 hours)

12,810

CADM

-

-

-

BODY BURDEN (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

357

Emond

5,473

7,247 (@. 8,574 hours)

4,335

CADM

-

-

-

714

Emond

2,878

3,774 (@. 8,574 hours)

2,318

CADM

-

-

-

BOUND LIVER (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

357

Emond

71.5

99.1 ( a 2 hours)

65.4

CADM

-

-

-

714

Emond

56.4

88.6 (@, 2 hours)

50.4

CADM

-

-

-

1

2

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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1 C.3.1.5. Delia Porta et ah (2001) (male)

Type:

Mouse

Dose:

2,500 and 5,000 ng/kg-week (equivalent to
357 and 714 ng/kg-day)

Strain:

B6C3

Route:

Gavage

Body weight:

6 weeks old (BW 26g)

Regime:

Once a week for 52 weeks

Sex:

Male

Simulation time:

8,736 hours

2	The C ADM model was not ran because the study duration is longer than the allowed model duration

3

WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

357

Emond

67.8

787 (@. 8,568 hours)

47.0

CADM

-

-

-

714

Emond

38.0

398 (@. 8,568 hours)

27.3

CADM

-

-

-

LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

357

Emond

50,397

70,052 (@. 8,577 hours)

37,483

CADM

-

-

-

714

Emond

25,493

35,347 (@. 8,577 hours)

19,155

CADM

-

-

-

FA T CONCENTRA TIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

357

Emond

25,516

28,851 (@. 8,589 hours)

22,861

CADM

-

-

-

714

Emond

14,306

16,061 (@. 8,590 hours)

12,999

CADM

-

-

-

BODY BURDEN (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

357

Emond

5,504

7,282 (@. 8,574 hours)

4,368

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-107 DRAFT—DO NOT CITE OR QUOTE


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714

Emond

2,894

3,791 (@. 8,574 hours)

2,335

CADM

-

-

-

BOUND LIVER (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

357

Emond

71.6

99.2 (@. 2 hours)

65.4

CADM

-

-

-

714

Emond

56.4

88.6 (@, 2 hours)

50.4

CADM

-

-

-

1

2

3	C.3.1.6. Fattore et al. (2000)

Type:

Rat

Dose:

20, 200, 2,000 ng/kg-day

Strain:

Sprague Dawley

Route:

Oral in the diet

Body weight:

7 weeks old (BW
150g)

Regime:

Every day for 13 weeks

Sex:

Female and male

Simulation time:

2,184 hours

4

WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

20

Emond

9.59

15.0 (@ 2,160 hours)

11.1

CADM

-

-

-

200

Emond

57.6

102 (@. 2,160 hours)

63.9

CADM

-

-

-

2,000

Emond

476

903 ( a 2,160 hours)

522

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-108 DRAFT—DO NOT CITE OR QUOTE


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LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

20

Emond

2,448

3,228 (@. 2,164 hours)

3,078

CADM

4,471

5,639

5,639

200

Emond

24,136

30,245 (@. 2,164 hours)

28,709

CADM

45,337

56,499

56,499

2,000

Emond

234,170

288,020 (@. 2,164 hours)

272,590

CADM

454,031

565,103

565,103

FA T CONCENTRA TIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

20

Emond

890

1,113 (@ 2,166 hours)

1,101

CADM

1,545

1,796

1,756

200

Emond

5,355

6,542 (@. 2,165 hours)

6,430

CADM

13,351

15,604

15,292

2,000

Emond

44,176

54,246 (@. 2,165 hours)

53,140

CADM

131,259

153,534

150,516

BODY BURDEN (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

20

Emond

187

242 (@. 2,164 hours)

233

CADM

261

324

324

200

Emond

1,556

1,940 (@. 2,164 hours)

1,850

CADM

2,496

3,084

3,084

2,000

Emond

14,432

17,797 (@ 2,164 hours)

16,891

CADM

24,836

30,674

30,674

BOUND LIVER (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

20

Emond

24.9

29.8 (@. 2,164 hours)

28.8

CADM

-

-

-

200

Emond

69.4

76.0 (@. 2,164 hours)

74.7

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-109 DRAFT—DO NOT CITE OR QUOTE


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2,000

Emond

104

106 (@ 2,164 hours)

106

CADM

-

-

-

1

2

3	C.3.1.7. Franc et ah (2001) Sprague Dawley Rats

Type:

Rats

Dose:

140, 420, and 1400 ng/kg every two weeks
(equivalent to 10, 30, and 100 ng/kg-day)

Strain:

Sprague Dawley,

Route:

Oral gavage

Body weight:

200 g (10 weeks old)

Regime:

Once every two weeks for 22 weeks

Sex:

Female

Simulation
time:

3,696 hours

4

WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

10

Emond

6.59

34.6 (@ 3,360 hours)

5.52

CADM

-

-

-

30

Emond

14.5

98.1 (@ 3,360 hours)

11.3

CADM

-

-

-

WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

100

Emond

36.4

315 (@ 3,360 hours)

26.4

CADM

-

-

-

LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

10

Emond

1,447

2,458 (@ 3,368 hours)

1,150

CADM

2,616

3,620

2,174

30

Emond

4,228

7,161 (@ 3,368 hours)

3,120

CADM

7,936

10,899

6,510

100

Emond

13,821

23,417 (@ 3,368 hours)

9,658

CADM

26,564

36,361

21,703

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-l 10 DRAFT—DO NOT CITE OR QUOTE


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FA T CONCENTRA TIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

10

Emond

619

787 (@. 3,417 hours)

560

CADM

966

1,230

759

30

Emond

1,362

1,741 (@3,415 hours)

1,161

CADM

2,448

3,203

1,849

100

Emond

3,430

4,464 (@. 3,412 hours)

2,755

CADM

7,573

10,052

5,606

BODY BURDEN (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

10

Emond

119

177 (@. 3,366 hours)

99.5

CADM

159

212

133

30

Emond

308

472 (@. 3,366 hours)

240

CADM

450

603

367

100

Emond

921

1,445 (@. 3,366 hours)

671

CADM

1,462

1,969

1,181

BOUND LIVER (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

10

Emond

18.6

32.9 ((ci\ 1 hours)

16.4

CADM

-

-

-

30

Emond

33.7

59.2 ((ci\ 1 hours)

29.0

CADM

-

-

-

100

Emond

57.5

86.9 ((ci\ 1 hours)

50.4

CADM

-

-

-

1

2

3	C.3.1.8. Franc et ah (2001) Long-Evans Rats

Type:

Rats

Dose:

140, 420, and 1400 ng/kg every two weeks
(equivalent to 10, 30, and 100 ng/kg-day)

Strain:

Long-Evans

Route:

Oral gavage

Body weight:

190 g (10 weeks old)

Regime:

Once every two weeks for 22 weeks

Sex:

Female

Simulation
time:

3,696 hours

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-l 11 DRAFT—DO NOT CITE OR QUOTE


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WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

10

Emond

6.58

34.2 (@. 3,360 hours)

5.52

CADM

-

-

-

30

Emond

14.5

97.0 (@. 3,360 hours)

11.3

CADM

-

-

-

100

Emond

36.4

312 (@ 3,360 hours)

26.4

CADM

-

-

-

LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

10

Emond

1,447

2,458 (@. 3,368 hours)

1,150

CADM

2,616

3,620

2,174

30

Emond

4,228

7,161 (@ 3,368 hours)

3,121

CADM

7,936

10,899

6,510

100

Emond

13,821

23,421 (@. 3,368 hours)

9,659

CADM

26,564

36,361

21,703

FA T CONCENTRA TIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

10

Emond

619

788 (@. 3,417 hours)

560

CADM

966

1,230

759

30

Emond

1,362

1,742 (@. 3,414 hours)

1,160

CADM

2,448

3,203

1,849

100

Emond

3,429

4,466 (@. 3,412 hours)

2,752

CADM

7,573

10,052

5,606

BODY BURDEN (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

10

Emond

119

177 (@. 3,366 hours)

99.5

CADM

159

212

133

30

Emond

308

472 (@. 3,366 hours)

240

CADM

450

603

367

100

Emond

921

1,445 (@. 3,366 hours)

671

CADM

1,462

1,969

1,181

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-l 12 DRAFT—DO NOT CITE OR QUOTE


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BOUND LIVER (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

10

Emond

18.6

32.9 {(cf 1 hours)

16.4

CADM

-

-

-

30

Emond

33.7

59.2 {(cf 1 hours)

29.0

CADM

-

-

-

100

Emond

57.5

86.9 (@, 1 hours)

50.4

CADM

-

-

-

1

2

3	C.3.1.9. Franc et al. (2001) Hans Wistar Rats

Type:

Rats

Dose:

140, 420, and 1400 ng/kg every two weeks
(equivalent to 10, 30, and 100 ng/kg-day)

Strain:

Hans Wistar

Route:

Oral gavage

Body weight:

205 g (10 weeks old)

Regime:

Once every two weeks for 22 weeks

Sex:

Female

Simulation
time:

3,696 hours

4

WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

10

Emond

6.59

34.7 (@. 3,360 hours)

5.52

CADM

-

-

-

30

Emond

14.5

98.7 (@. 3,360 hours)

11.3

CADM

-

-

-

100

Emond

36.4

317 (@ 3,360 hours)

26.4

CADM

-

-

-

LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

10

Emond

1,447

2,458 (@. 3,368 hours)

1,150

CADM

2,616

3,620

2,174

30

Emond

4,228

7,160 (@ 3,368 hours)

3,120

CADM

7,936

10,899

6,510

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-l 13 DRAFT—DO NOT CITE OR QUOTE


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100

Emond

13,821

23,416 (@ 3,368 hours)

9,658

CADM

26,564

36,361

21,703

FA T CONCENTRA TIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

10

Emond

619

787 (@3,418 hours)

560

CADM

966

1,230

759

30

Emond

1,363

1,741 (@3,415 hours)

1,162

CADM

2,448

3,203

1,849

100

Emond

3,431

4,463 (@3,412 hours)

2,757

CADM

7,573

10,052

5,606

BODY BURDEN (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

10

Emond

119

177 (@ 3,366 hours)

99.5

CADM

159

212

133

30

Emond

308

472 (@ 3,366 hours)

240

CADM

450

603

367

100

Emond

921

1,446 (@ 3,366 hours)

671

CADM

1,462

1,969

1,181

BOUND LIVER (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

10

Emond

186

^2 9 (f(f> 1 hours')

164

CADM

-



-

30

Emond

33.7

5l> 2 u/ 1 hum's)



CADM

-



-

100

Emond

57.5

86.9 (@ 1 hours)

50.4

CADM

-



-

This document is a draft for review purposes only and does not constitute Agency policy.

C-114 DRAFT—DO NOT CITE OR QUOTE


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1 C.3.1.10. Hassoun et ah (2000)

Type:

Rat

Dose:

0, 3, 10, 22, 46, 100 ng/kg/day (2.14, 7.14,
15.7, 32.9, and 71.4 ng/kg/day adjusted doses)

Strain:

Sprague Dawley

Route:

Oral gavage

Body weight:

8 weeks old
(BW=215g)

Regime:

5 days/week for 13 weeks

Sex:

Female

Simulation
time:

2184 hours

2

WHOLE BLOOD CONCENTRATLONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

2.14

Emond

1.94

3.12 (@ 2,112 hours)

1,303.17

CADM

-

-

-

7.14

Emond

4.6136

7.71 (@ 2,112 hours)

2,901.26

CADM

-

-

-

15.7

Emond

8.147

14.2 (@ 2,112 hours)

4,947.3

CADM

-

-

-

32.9

Emond

14.009

25.8 (@2,112 hours)

8,277

CADM

-

-

-

71.4

Emond

25.34

49.7 (@2,112 hours)

14,637

CADM

-

-

-

LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

2.14

Emond

266.8

399 (@2,116 hours)

349

CADM

-

-

-

7.14

Emond

888

1,259 (@2,117 hours)

1,079

CADM

-

-

-

15.7

Emond

1,948.499

2,689 (@2,117 hours)

2,278.182

CADM

-

-

-

32.9

Emond

4,055.031

5,484 (@2,117 hours)

4,607.265

CADM

-

-

-

71.4

Emond

8,774.97

11,692 (@2,117 hours)

9,754.31



CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-l 15 DRAFT—DO NOT CITE OR QUOTE


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FA T CONCENTRA TIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

2.14

Emond

179.2

243 ( a 2,126 hours)

234.9

CADM

-

-

-

7.14

Emond

427

553 (@ 2,124 hours)

528

CADM

-

-

-

15.7

Emond

755

958 (@ 2,123 hours)

908

CADM

-

-

-

32.9

Emond

1,299

1,627 (@ 2,122 hours)

1,529

CADM

-

-

-

71.4

Emond

2,349.892

2,928 (@ 2,121 hours)

2,727.240

CADM

-

-

-

BODY BURDEN (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

2.14

Emond

27.425

38.9 (@ 2,116 hours)

35.720

CADM

-

-

-

7.14

Emond

76.87

105 (@2,116 hours)

93.67

CADM

-

-

-

15.7

Emond

153.1

205 (@2,116 hours)

180.2

CADM

-

-

-

32.9

Emond

295

390 (@2,116 hours)

339

CADM

-

-

-

71.4

Emond

600

785 (@2,116 hours)

674

CADM

-

-

-

BOUND LIVER (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

2.14

Emond

6

8.48 (@2,116 hours)

8

CADM

-

-

-

7.14

Emond

13.7242

17.5 (@2,116 hours)

15.7348

CADM

-

-

-

15.7

Emond

21.9703

27.1 (@2,116 hours)

24.4047

CADM

-

-

-

32.9

Emond

32.817

39.2 (@2,116 hours)

35.608

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-l 16 DRAFT—DO NOT CITE OR QUOTE


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71.4

Emond

47.54

55.0 (@ 2,116 hours)

50.63

CADM

-

-

-

1

2

3	C.3.1.11. Hutt et al. (2008)

Type:

Rat

Dose:

50 ng/kg-week

Strain:

Sprague-Dawley

Route:

Oral gavage

Body weight:

4.5 g

Regime:

1/week for 13 weeks

Sex:

Female

Simulation
time:

2,184 hours (weekly exposure)

4

WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

7.14

Emond

4.49

8.86 (@. 2,016 hours)

4.71

CADM

-

-

-

LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

7.14

Emond

867.4

1,363 (@ 2,021 hours)

928.1

CADM

1,678

2,007

2,007

FA T CONCENTRA TIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

7.14

Emond

423.6

555 (@. 2,040 hours)

459.9

CADM

730

787.1

769

BODY BURDEN (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

7.14

Emond

76

108 (@. 2,022 hours)

81

CADM

108

126

126

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-l 17 DRAFT—DO NOT CITE OR QUOTE


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BOUND LIVER (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

7.14

Emond

14

19.4 (@. 2,020 hours)

14

CADM

-

-

-

1

2

3	C.3.1.12. Kitchin and Woods (1979)

Type:

Rats

Dose:

0, 0.6, 2, 4, 20, 60, 200, 600, 2000, 5000,
20,000 ng/kg/day

Strain:

Sprague-Dawley

Route:

Oral exposure

Body weight:

200 to 250 g (BW set
to 225 g)

Regime:

Single dose

Sex:

Female

Simulation
time:

24 hours*

4	* 1 week is the minimum that can be simulated with the C ADM model, so the CADM model was not used.

5

WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)

Model

Metric

Time-weighted Ave

Max

Terminal

0.6

Emond

0.0645

0.126 ((ai 0 hours)

0.0441

CADM

-

-

-

2

Emond

0.202

0.421 ( a 0 hours)

0.137

CADM

-

-

-

4

Emond

0.384

0.841 ((ai 0 hours)

0.258

CADM

-

-

-

20

Emond

1.61

4.21 ( a 0 hours)

1.04

CADM

-

-

-

60

Emond

4.15

12.6 (@, 0 hours)

2.55

CADM

-

-

-

200

Emond

11.6

42.1 ((ci\ 0 hours)

6.61

CADM

-

-

-

600

Emond

30.3

126 ( a 0 hours)

15.8

CADM

-

-

-

2000

Emond

90.9

422 ( a 0 hours)

42.8

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-l 18 DRAFT—DO NOT CITE OR QUOTE


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5000

Emond

218

1,056 ( a 0 hours)

96.9

CADM

-

-

-

20000

Emond

863

4,233 ( a 0 hours)

365

CADM

-

-

-

LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)

Model

Metric

Time-weighted Ave

Max

Terminal

0.6

Emond

2.95

3.81 ( a 4 hours)

2.31

CADM

-

-

-

2

Emond

10.5

12.9 {(cf 4 hours)

8.69

CADM

-

-

-

4

Emond

22.2

26.3 ( a 4 hours)

18.9

CADM

-

-

-

20

Emond

128

143 ( a 6 hours)

118

CADM

-

-

-

60

Emond

420

463 ( a 8 hours)

406

CADM

-

-

-

200

Emond

1,523

1,666 ( a 9 hours)

1,526

CADM

-

-

-

600

Emond

4,821

5,258 (@. 10 hours)

4,932

CADM

-

-

-

2000

Emond

16,603

18,080 (@. 11 hours)

17,226

CADM

-

-

-

5000

Emond

41,971

45,674 (@. 11 hours)

43,803

CADM

-

-

-

20000

Emond

167,820

182,580 (@. 11 hours)

175,890

CADM

-

-

-

FA T CONCENTRA TIONS (ng/kg)

Dose
(ng/kg-day)

Model

Metric

Time-weighted Ave

Max

Terminal

0.6

Emond

1.60

2.47 (@. 24 hours)

2.47

CADM

-

-

-

2

Emond

5.07

7.71 (@. 24 hours)

7.71

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-l 19 DRAFT—DO NOT CITE OR QUOTE


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4

Emond

9.68

14.6 (@, 24 hours)

14.6



CADM

-

-

-

20

Emond

41.7

60.7 ( a 24 hours)

60.7



CADM

-

-

-

60

Emond

110

155 ((ci\ 24 hours)

155



CADM

-

-

-

200

Emond

317

427 (@. 24 hours)

427



CADM

-

-

-

600

Emond

851

1,102 (@ 24 hours)

1,102



CADM

-

-

-

2000

Emond

2,620

3,276 ( a 24 hours)

3,276



CADM

-

-

-

5000

Emond

6,361

7,816 (@. 24 hours)

7,816



CADM

-

-

-

20000

Emond

25,401

30,827 (@. 24 hours)

30,827



CADM

-

-

-

BODY BURDEN (ng/kg)

Dose
(ng/kg-day)

Model

Metric

Time-weighted Ave

Max

Terminal

0.6

Emond

0.322

0.341 {(cf 9 hours)

0.338

CADM

-

-

-

2

Emond

1.07

1.14 {(cf 8 hours)

1.12

CADM

-

-

-

4

Emond

2.14

2.27 (@, 8 hours)

2.23

CADM

-

-

-

20

Emond

10.6

11.3 (@. 8 hours)

11.0

CADM

-

-

-

60

Emond

31.7

33.8 (@, 7 hours)

32.8

CADM

-

-

-

200

Emond

105

112 ( a 1 hours)

108

CADM

-

-

-

600

Emond

315

337 ( a 1 hours)

324

CADM

-

-

-

2000

Emond

1,049

1,123 (@ 7 hours)

1,074

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-120 DRAFT—DO NOT CITE OR QUOTE


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5000

Emond

2,621

2,806 ( a 1 hours)

2,680

CADM

-

-

-

20000

Emond

10,468

11,215 (@,7 hours)

10,693

CADM

-

-

-

BOUND LIVER (ng/kg)

Dose
(ng/kg-day)

Model

Metric

Time-weighted Ave

Max

Terminal

0.6

Emond

0.216

0.309 ((ai 3 hours)

0.159

CADM

-

-

-

2

Emond

0.668

0.975 ((ci\ 3 hours)

0.494

CADM

-

-

-

4

Emond

1.25

1.86 (@, 3 hours)

0.927

CADM

-

-

-

20

Emond

4.87

7.67 ((ci\ 2 hours)

3.66

CADM

-

-

-

60

Emond

11.2

18.3 ((ci\ 2 hours)

8.55

CADM

-

-

-

200

Emond

25.1

40.8 (@, 1 hours)

19.7

CADM

-

-

-

600

Emond

45.8

68.2 (@, 1 hours)

37.6

CADM

-

-

-

2000

Emond

73.3

93.1 ((ci\ 1 hours)

64.7

CADM

-

-

-

5000

Emond

90.9

104 ( a 1 hours)

84.7

CADM

-

-

-

20000

Emond

106

110 ( a 1 hours)

104

CADM

-

-

-

1

2

3	C.3.1.13. Kocibaetal (1976)

Type:

Rats

Dose:

1, 10, 100, 1000 ng/kg-day

Strain:

Sprague-Dawley
(Spartan)

Route:

Diet exposure

Body weight:

170-190 g(bw=180g)

Regime:

5 days/week for 13 weeks

Sex:

Female

Simulation
time:

2,184 hours
(13wk exposed)

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-121 DRAFT—DO NOT CITE OR QUOTE


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WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

0.714

Emond

0.859

1.38 (@ 2,112 hours)

1.13

CADM

-

-

-

7.143

Emond

4.61

7.62 (@ 2,112 hours)

5.27

CADM

-

-

-

WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

71.43

Emond

25.3

48.8 (@ 2,112 hours)

26.6

CADM

-

-

-

714.3

Emond

181

403 (@2,112 hours)

184

CADM

-

-

-

LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

0.714

Emond

88.3

140 (@2,116 hours)

126

CADM

89.0

192

12.1

7.143

Emond

888

1,259 (@2,117 hours)

1,079

CADM

970

2,007

29.0

71.43

Emond

8,776

11,693 (@2,117 hours)

9,756

CADM

9,841

20,170

88.0

714.3

Emond

86,329

112,580 (@2,117 hours)

92,835

CADM

98,617

201,814

455

FA T CONCENTRA TIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

0.714

Emond

79.4

114 (@2,129 hours)

111

CADM

120

190

43.0

7.143

Emond

427

553 (@2,124 hours)

528

CADM

456

787

67.0

71.43

Emond

2,348

2,925 (@2,121 hours)

2,720

CADM

3,036

5,748

117

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-122 DRAFT—DO NOT CITE OR QUOTE


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714.3

Emond

16,815

21,126 (@ 2,120 hours)

19,233

CADM

28,382

55,013

274

BODY BURDEN (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

0.714

Emond

10.8

16.1 (@ 2,116 hours)

15.1

CADM

11.5

20.0

3.75

7.143

Emond

76.9

105 (@ 2,116 hours)

93.6

CADM

65.3

126

6.22

71.43

Emond

600

785 (@2,116 hours)

673

CADM

553

1,113

12.0

714.3

Emond

5,366

6,960 (@2,116 hours)

5,842

CADM

5,401

10,967

37.0

BOUND LIVER (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

0.714

Emond

2.89

4.17 (@2,116 hours)

3.81

CADM

-

-

-

7.143

Emond

13.7

17.5 (@2,116 hours)

15.7

CADM

-

-

-

71.43

Emond

47.5

55.0 (@2,116 hours)

50.6

CADM

-

-

-

714.3

Emond

93.4

98.2 (@2,117 hours)

95.7

CADM

-

-

-

1

2

3	C.3.1.14. Kociba et al. (1978) Female

Type:

Rats

Dose:

0, 1, 10, 100 ng/kg-day

Strain:

Sprague-Dawley
(Spartan)

Route:

Diet exposure

Body weight:

170-190 g (bw=180)

Regime:

7 days/week for 104 weeks

Sex:

Female

Simulation time:

17,472 hours

4

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-123 DRAFT—DO NOT CITE OR QUOTE


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WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1

Emond

1.55

1.92 (@. 17,448 hours)

1.69

CADM

-

-

-

10

Emond

7.15

9.25 (@. 17,448 hours)

7.16

CADM

-

-

-

100

Emond

38.6

57.5 (@. 17,448 hours)

37.1

CADM

-

-

-

LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1

Emond

192

226 (@. 17,452 hours)

218

CADM

292

333

333

10

Emond

1,618

1,742 (@. 17,452 hours)

1,665

CADM

2,981

3,342

3,342

100

Emond

14,892

15,673 (@. 17,452 hours)

14,907

CADM

29,917

33,432

33,432

FA T CONCENTRA TLONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1

Emond

147

165 (@. 17,457 hours)

164

CADM

196

229

181

10

Emond

680

713 (@. 17,454 hours)

706

CADM

861

1,015

789

100

Emond

3,663

3,788 (@. 17,454 hours)

3,731

CADM

6,756

7,939

6,203

BODY BURDEN (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1

Emond

21.2

24.3 (@. 17,452 hours)

23.8

CADM

26.0

27.0

27.0

10

Emond

131

140 (@. 17,452 hours)

136

CADM

169

176

176

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-124 DRAFT—DO NOT CITE OR QUOTE


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100

Emond

989

1,039 (@. 17,452 hours)

994

CADM

1,546

1,601

1,601

BOUND LIVER (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1

Emond

5.11

5.77 (@. 17,452 hours)

5.59

CADM

-

-

-

10

Emond

20.0

21.1 (@. 17,452 hours)

20.4

CADM

-

-

-

100

Emond

59.9

61.5 (@. 17,452 hours)

60.1

CADM

-

-

-

1

2

3	C.3.1.15. Kocibaetal. (1978) Male

Type:

Rats

Dose:

0, 1, 10, 100 ng/kg-day

Strain:

Sprague-Dawley
(Spartan)

Route:

Diet exposure

Body weight:

Body weight
approximated to be
250 g

Regime:

7 days/week for 104 weeks

Sex:

Male

Simulation time:

17,472 hours

4

WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1

Emond

1.56

1.96 (@. 17,448 hours)

1.70

CADM

-

-

-

10

Emond

7.16

9.35 (@. 17,448 hours)

7.11

CADM

-

-

-

100

Emond

38.7

59.3 (@. 17,448 hours)

37.1

CADM

-

-

-

LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1

Emond

194

229 (@. 17,452 hours)

221

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-125 DRAFT—DO NOT CITE OR QUOTE


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10

Emond

1,616

1,723 (@. 17,452 hours)

1,649

CADM

-

-

-

100

Emond

14,898

15,671 (@. 17,452 hours)

14,912

CADM

-

-

-

FA T CONCENTRA TIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1

Emond

148

167 (@. 17,456 hours)

166

CADM

-

-

-

10

Emond

680

709 (@. 17,454 hours)

703

CADM

-

-

-

100

Emond

3,677

3,803 (@. 17,453 hours)

3,747

CADM

-

-

-

BODY BURDEN (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1

Emond

21.4

24.6 (@. 17,452 hours)

24.1

CADM

-

-

-

10

Emond

131

139 (@. 17,452 hours)

134

CADM

-

-

-

100

Emond

991

1,041 (@. 17,452 hours)

995

CADM

-

-

-

BOUND LIVER (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1

Emond

5.15

5.83 (@. 17,452 hours)

5.64

CADM

-

-

-

10

Emond

20.0

21.0 (@. 17,452 hours)

20.3

CADM

-

-

-

100

Emond

60.0

61.5 (@. 17,452 hours)

60.1

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-126 DRAFT—DO NOT CITE OR QUOTE


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1 C.3.1.16. Latchoumycandane and Mathur (2002)

Type:

Rat

Dose:

0, 1, 10, lOOng/kg-day

Strain:

Wistar

Route:

Oral gavage

Body weight:

45 days old
(BW set to 200g)

Regime:

1/day for 45 days

Sex:

Male

Simulation
time:

1,080 hours (daily exposure)

2

WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1

Emond

0.785

1.37 (@. 1,056 hours)

1.18

CADM

-

-

-

10

Emond

4.65

8.18 (@. 1,056 hours)

6.18

CADM

-

-

-

100

Emond

27.3

53.9 (@. 1,056 hours)

33.8

CADM

-

-

-

LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1

Emond

78.5

138 (@. 1,060 hours)

133

CADM

116

217

217

10

Emond

902

1,423 (@. 1,060 hours)

1,358

CADM

1,669

2,550

2,550

100

Emond

9,579

14,015 (@. 1,061 hours)

13,306

CADM

17,681

25,915

25,915

FA T CONCENTRA TLONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1

Emond

69.8

113 (@. 1,072 hours)

113

CADM

150

220

220

10

Emond

416

608 (@. 1,065 hours)

604

CADM

744

1,009

1,009

100

Emond

2,448

3,425 (@. 1,062 hours)

3,380

CADM

5,719

7,866

7,866

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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BODY BURDEN (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1

Emond

9.56

15.9 (@. 1,060 hours)

15.6

CADM

14.0

22.2

22.2

10

Emond

76.7

117 (@. 1,060 hours)

113

CADM

106

157

157

100

Emond

646

933 (@. 1,060 hours)

891

CADM

988

1,439

1,439

BOUND LIVER (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1

Emond

2.64

4.12 (@. 1,060 hours)

3.96

CADM

-

-

-

10

Emond

13.7

18.8 (@. 1,060 hours)

18.1

CADM

-

-

-

100

Emond

48.6

59.0 (@. 1,060 hours)

57.5

CADM

-

-

-

1

2

3	C.3.1.17. Li et al (1997)

Type:

Rats

Dose:

0, 3, 10, 30, 100, 300, 1000, 3000,
10000, 30000 ng/kg/day

Strain:

Sprague-Dawley

Route:

Gastric intubation

Body weight:

22 day old, 55 to 58 g
(BW set to 56.5 g)

Regime:

One dose for one day

Sex:

Female

Simulation time:

24 hours

4	The CADM model was not ran because the dosing duration is lower than the resolution of the model (1 week)

5

WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)

Model

Metric

Time-weighted Ave

Max

Terminal

3

Emond

0.266

0.470 ((ci\ 1 hours)

0.180

CADM

-

-

-

10

Emond

0.799

1.57 ((ci\ 1 hours)

0.535

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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30

Emond

2.10

4.68 ( a 1 hours)

1.37

CADM

-

-

-

100

Emond

5.87

15.6 ((ci\ 1 hours)

3.68

CADM

-

-

-

300

Emond

15.0

46.8 (@, 0 hours)

8.83

CADM

-

-

-

1,000

Emond

43.3

156 ( a 0 hours)

23.4

CADM

-

-

-

3,000

Emond

120

469 ( a 0 hours)

59.9

CADM

-

-

-

10,000

Emond

386

1,570 ((ci\ 0 hours)

182

CADM

-

-

-

30,000

Emond

1,172

4,762 ( a 0 hours)

535

CADM

-

-

-

LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)

Model

Metric

Time-weighted Ave

Max

Terminal

3

Emond

14.7

18.6 (@, 4 hours)

11.9

CADM

-

-

-

10

Emond

55.0

65.2 {(cf 5 hours)

47.6

CADM

-

-

-

30

Emond

185

210 (@, 6 hours)

170

CADM

-

-

-

100

Emond

690

768 ( a 1 hours)

666

CADM

-

-

-

300

Emond

2,248

2,473 (@. 8 hours)

2,240

CADM

-

-

-

1,000

Emond

7,938

8,671 ( a 9 hours)

8,094

CADM

-

-

-

3,000

Emond

24,474

26,639 (@. 9 hours)

25,267

CADM

-

-

-

10,000

Emond

82,349

89,464 ((ai 9 hours)

85,597

CADM

-

-

-

30,000

Emond

245,610

265,670 (@. 10 hours)

255,390

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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FA T CONCENTRA TIONS (ng/kg)

Dose
(ng/kg-day)

Model

Metric

Time-weighted Ave

Max

Terminal

3

Emond

8.75

12.7 (@. 24 hours)

12.7

CADM

-

-

-

10

Emond

26.6

38.0 (@. 24 hours)

38.0

CADM

-

-

-

30

Emond

70.8

98.9 ((ai 24 hours)

98.9

CADM

-

-

-

100

Emond

202

273 ( a 24 hours)

273

CADM

-

-

-

300

Emond

530

689 ( a 24 hours)

689

CADM

-

-

-

1,000

Emond

1,573

1,958 (@. 24 hours)

1,958

CADM

-

-

-

3,000

Emond

4,433

5,358 (@. 24 hours)

5,358

CADM

-

-

-

10,000

Emond

14,428

17,119 (@ 24 hours)

17,119

CADM

-

-

-

30,000

Emond

44,361

51,948 (@ 22 hours)

51,898

CADM

-

-

-

BODY BURDEN (ng/kg)

Dose
(ng/kg-day)

Model

Metric

Time-weighted Ave

Max

Terminal

3

Emond

1.60

1.70 {(cf 8 hours)

1.68

CADM

-

-

-

10

Emond

5.33

5.66 (@, 8 hours)

5.56

CADM

-

-

-

30

Emond

15.9

16.9 (@, 8 hours)

16.5

CADM

-

-

-

100

Emond

52.8

56.2 {(cf 1 hours)

54.5

CADM

-

-

-

300

Emond

158

169 ( a 1 hours)

163

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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1,000

Emond

525

561 (a 1 hours)

539

CADM

-

-

-

3,000

Emond

1,574

1,684 ( a 1 hours)

1,611

CADM

-

-

-

10,000

Emond

5,240

5,610 ((ci\ 1 hours)

5,360

CADM

-

-

-

30,000

Emond

15,758

16,815 (@. 7 hours)

16,041

CADM

-

-

-

BOUND LIVER (ng/kg)

Dose
(ng/kg-day)

Model

Metric

Time-weighted Ave

Max

Terminal

3

Emond

0.89

1.37 ((ci\ 3 hours)

0.64

CADM

-

-

-

10

Emond

2.58

4.10 ((ci\ 2 hours)

1.88

CADM

-

-

-

30

Emond

6.37

10.5 ((ci\ 2 hours)

4.71

CADM

-

-

-

100

Emond

15.54

25.9 ((ci\ 2 hours)

11.77

CADM

-

-

-

300

Emond

31.25

50.1 ((ci\ 1 hours)

24.57

CADM

-

-

-

1,000

Emond

56.75

79.8 ((ci\ 1 hours)

47.62

CADM

-

-

-

3,000

Emond

81.28

98.4 ((ci\ 1 hours)

73.32

CADM

-

-

-

10,000

Emond

99.77

108 ( a 1 hours)

95.68

CADM

-

-

-

30,000

Emond

107.69

111 (a 1 hours)

106.24

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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1 C.3.1.18. Murray et ah (1979) Adult Portion

Type:

Rat

Dose:

1,10, and 100 ng/kg-day

Strain:

Sprague Dawley

Route:

Diet oral dose

Body weight:

BW set to 4.5 g

Regime:

Once per day for 120 days

Sex:

Female

Simulation time:

2880 hours

2

WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1

Emond

1.12

1.51 (@ 2,856 hours)

1.42

CADM

-

-

-

10

Emond

5.88

7.59 (@. 2,856 hours)

6.75

CADM

-

-

-

100

Emond

32.7

44.3 (@. 2,856 hours)

36.0

CADM

-

-

-

LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1

Emond

128

180 (@. 2,859 hours)

173

CADM

-

-

-

10

Emond

1,273

1,618 (@. 2,860 hours)

1,540

CADM

-

-

-

100

Emond

12,601

15,281 (@. 2,860 hours)

14,460

CADM

-

-

-

FA T CONCENTRA TIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1

Emond

106

139 (@. 2,865 hours)

138

CADM

-

-

-

10

Emond

556

665 (@. 2,864 hours)

657

CADM

-

-

-

100

Emond

3,095

3,604 (@. 2,862 hours)

3,534

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-132 DRAFT—DO NOT CITE OR QUOTE


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BODY BURDEN (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1

Emond

14.8

20.0 ((ai 2,860 hours)

19.6

CADM

-

-

-

10

Emond

105

130 (@. 2,860 hours)

126

CADM

-

-

-

100

Emond

837

1,003 (@. 2,860 hours)

957

CADM

-

-

-

BOUND LIVER (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1

Emond

3.77

4.95 (@. 2,859 hours)

4.77

CADM

-

-

-

10

Emond

17.1

20.3 (@. 2,859 hours)

19.5

CADM

-

-

-

100

Emond

55.3

60.9 (@. 2,860 hours)

59.4

CADM

-

-

-

1

2

3	C.3.1.19. NTP (1982)—Female Rats, Chronic

Type:

Rat

Dose:

10, 50 and 500 ng/kg/wk,
two doses per week

Strain:

Osborne-Mendel

Route:

Oral exposure

Body weight

6 weeks old
(BW set to 25 Og)

Regime:

Biweekly

(Simulation has been perform using female BW

Sex:

Female

Simulation time

17,472 hours (104 weeks of exposure)

4

WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1.4

Emond

1.96

3.11 (@. 17,220 hours)

1.94

CADM

-

-

-

7.1

Emond

5.69

11.0 (@ 17,388 hours)

5.40

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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71

Emond

29.8

82.2 (@. 17,388 hours)

26.9

CADM

-

-

-

LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1.4

Emond

265

308 (@. 17,226 hours)

265

CADM

15,318

20,170

7,102

7.1

Emond

1,175

1,338 (@. 17,394 hours)

1,117

CADM

30,700

40,353

14,200

71

Emond

10,734

12,182 (@. 17,395 hours)

9,882

CADM

30,700

40,353

14,200

FA T CONCENTRA TIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1.4

Emond

186

200 (@. 17,328 hours)

193

CADM

4,655

5,748

2,107

7.1

Emond

541

569 (@. 17,409 hours)

544

CADM

9,064

11,224

3,964

71

Emond

2,826

2,973 (@. 17,404 hours)

2,769

CADM

17,879

22,172

7,671

BODY BURDEN (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1.4

Emond

27.9

31.1 (@. 17,225 hours)

28.4

CADM

855

1,113

403

7.1

Emond

99.4

110 (@. 17,393 hours)

96.7

CADM

1,695

2,208

787

71

Emond

729

814 (@. 17,393 hours)

683

CADM

3,375

4,395

1,556

BOUND LIVER (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1.4

Emond

6.37

7.26 (@. 17,224 hours)

6.38

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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7.1

Emond

16.6

18.5 (@. 17,392 hours)

16.1

CADM

-

-

-

71

Emond

52.7

56.4 (@. 17,393 hours)

50.9

CADM

-

-

-

1

2

3	C.3.1.20. NTP (1982)—Male Rats, Chronic

Type:

Rat

Dose:

10, 50 and 500 ng/kg/wk,
two doses per week

Strain:

Osborne-Mendel

Route:

Oral exposure

Body weight

6 weeks old
(BW set to 350g)

Regime:

Biweekly

(Simulation has been perform using female BW

Sex:

Male

Simulation time

17,472 hours (104 weeks of exposure)

4

WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1.4

Emond

1.96

3.18 (@. 17,388 hours)

1.93

CADM

-

-

-

7.1

Emond

5.70

11.4 (@. 17,388 hours)

5.39

CADM

-

-

-

71

Emond

29.9

87.0 (@. 17,388 hours)

26.9

CADM

-

-

-

LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1.4

Emond

265

306 (@. 17,394 hours)

263

CADM

-

-

-

LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

7.1

Emond

1,174

1,334 (@. 17,394 hours)

1,114

CADM

-

-

-

71

Emond

10,736

12,170 (@. 17,395 hours)

9,881

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-135 DRAFT—DO NOT CITE OR QUOTE


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FA T CONCENTRA TIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1.4

Emond

186

199 (@. 17,412 hours)

193

CADM

-

-

-

7.1

Emond

541

569 (@. 17,409 hours)

544

CADM

-

-

-

71

Emond

2,836

2,983 (@. 17,404 hours)

2,784

CADM

-

-

-

BODY BURDEN (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1.4

Emond

27.8

30.9 (@. 17,393 hours)

28.2

CADM

-

-

-

7.1

Emond

99.5

110 (@. 17,393 hours)

96.6

CADM

-

-

-

71

Emond

730

816 (@. 17,393 hours)

684

CADM

-

-

-

BOUND LIVER (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1.4

Emond

6.36

7.22 (@. 17,392 hours)

6.35

CADM

-

-

-

7.1

Emond

16.6

18.4 (@. 17,392 hours)

16.0

CADM

-

-

-

71

Emond

52.7

56.3 (@. 17,393 hours)

50.9

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-136 DRAFT—DO NOT CITE OR QUOTE


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1 C.3.1.21. NTP (1982)—Female Mice, Chronic

Type:

Mice

Dose:

40, 200 and 2000 ng/kg/wk,
two doses during the week

Strain:

B6C3F1

Route:

Oral exposure

Body weight

6 weeks old
(BW set to 23g)

Regime:

Biweekly

(Simulation has been perform using female BW)

Sex:

Female

Simulation time

17,472 hours (104 weeks of exposure)

2	* The mice chronic exposure could not be simulated with the CADM model because this model simulates for only

3	123 days.

4

WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

5.7

Emond

1.95

4.86 (@. 16,800 hours)

1.82

CADM

-

-

-

28.6

Emond

5.84

19.8 (@. 17,388 hours)

5.17

CADM

-

-

-

286

Emond

32.1

171 (@. 16,884 hours)

26.0

CADM

-

-

-

LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

5.7

Emond

490

582 (@. 16,807 hours)

463

CADM

-

-

-

28.6

Emond

2,236

2,629 (@. 17,395 hours)

2,025

CADM

-

-

-

286

Emond

20,841

24,353 (@. 17,396 hours)

18,182

CADM

-

-

-

FA T CONCENTRA TIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

5.7

Emond

737

785 (@. 17,408 hours)

757

CADM

-

-

-

28.6

Emond

2,213

2,337 (@. 17,404 hours)

2,216

CADM

-

-

-

286

Emond

12,138

12,861 (@. 17,400 hours)

11,775

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-137 DRAFT—DO NOT CITE OR QUOTE


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BODY BURDEN (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

5.7

Emond

91.9

103 (@. 17,393 hours)

91.2

CADM

-

-

-

28.6

Emond

329

370 (@. 17,393 hours)

313

CADM

-

-

-

286

Emond

2,400

2,740 (@. 17,393 hours)

2,176

CADM

-

-

-

BOUND LIVER (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

5.7

Emond

6.18

7.29 (@. 16,805 hours)

5.93

CADM

-

-

-

28.6

Emond

16.3

18.9 (@. 17,393 hours)

15.3

CADM

-

-

-

286

Emond

52.3

67.8 (@, 2 hours)

49.3

CADM

-

-

-

1

2

3	C.3.1.22. NTP (1982)—Male Mice, Chronic

Type:

Mice

Dose:

10, 50 and 500ng/kg/wk,
two doses during the week

Strain:

B6C3F1

Route:

Oral exposure

Body weight

6 weeks old
(BW set to 25g)

Regime:

Biweekly

Sex:

Male

Simulation time

17,472 hours (104 weeks of exposure)

4	* The mice chronic exposure could not be simulated with the CADM model because this model simulates for only

5	123 days.

6

WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1.4

Emond

0.767

1.53 (@. 17,304 hours)

0.749

CADM

-

-

-

7.1

Emond

2.27

5.99 (@. 17,052 hours)

2.11

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-138 DRAFT—DO NOT CITE OR QUOTE


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71

Emond

11.2

46.7 (@. 17,388 hours)

9.59

CADM

-

-

-

LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1.4

Emond

138

165 (@. 17,310 hours)

136

CADM

-

-

-

7.1

Emond

606

722 (@. 17,059 hours)

571

CADM

-

-

-

71

Emond

5,409

6,328 (@. 17,395 hours)

4,805

CADM

-

-

-

FA T CONCENTRA TIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1.4

Emond

290

314 (@. 17,411 hours)

306

CADM

-

-

-

7.1

Emond

860

918 (@. 17,155 hours)

883

CADM

-

-

-

71

Emond

4,257

4,490 (@. 17,402 hours)

4,204

CADM

-

-

-

BODY BURDEN (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1.4

Emond

32.3

36.2 (@. 17,309 hours)

33.3

CADM

-

-

-

7.1

Emond

110

123 (@. 17,057 hours)

108

CADM

-

-

-

71

Emond

710

802 (@. 17,393 hours)

660

CADM

-

-

-

BOUND LIVER (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1.4

Emond

2.56

3.03 (@. 17,309 hours)

2.53

CADM

-

-

-

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7.1

Emond

7.12

8.40 (@. 17,057 hours)

6.82

CADM

-

-

-

71

Emond

27.1

32.4 ((ci\ 2 hours)

25.3

CADM

-

-

-

1

2

3	C.3.1.23. NTP (2006) 14 Weeks

Type:

Rat

Dose:

0, 3, 10, 22, 46, 100 ng/kg-day

Strain:

Sprague Dawley

Route:

Oral gavage

Body
weight:

8 weeks old
(BW=215g)

Regime:

5 days/weeks for 14 weeks

Sex:

Female and male

Simulation time:

2,352 hours (14 weeks)

4

WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

2.14

Emond

1.98

3.15 (a 2.280 hours)

2.39

CADM

-

-

-

7.14

Emond

4.69

7.75 (@. 2,280 hours)

5.30

CADM

-

-

-

15.7

Emond

8.27

14.3 (@. 2,280 hours)

9.02

CADM

-

-

-

32.9

Emond

14.2

25.9 (@. 2,280 hours)

15.1

CADM

-

-

-

71.4

Emond

25.7

49.8 (@. 2,280 hours)

26.6

CADM

-

-

-

LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

2.14

Emond

275

404 (@. 2,284 hours)

354



CADM

-

-

-

7.14

Emond

909

1,270 (@. 2,285 hours)

1,089



CADM

-

-

-

15.7

Emond

1,988

2,703 (@. 2,285 hours)

2,291



CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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32.9

Emond

4,129

5,508 (@. 2,285 hours)

4,628



CADM

-

-

-

71.4

Emond

8,921

11,734 (@ 2,285 hours)

9,792



CADM

-

-

-

FA T CONCENTRA TIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

2.14

Emond

184

246 (@. 2,294 hours)

237

CADM

-

-

-

7.14

Emond

436

557 (@. 2,292 hours)

532

CADM

-

-

-

15.7

Emond

768

962 (@. 2,291 hours)

912

CADM

-

-

-

32.9

Emond

1,319

1,633 (@. 2,289 hours)

1,535

CADM

-

-

-

71.4

Emond

2,385

2,938 (@. 2,289 hours)

2,736

CADM

-

-

-

BODY BURDEN (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

2.14

Emond

28.2

39.4 (@. 2,284 hours)

36.1

CADM

-

-

-

7.14

Emond

78.5

106 (@. 2,284 hours)

94.4

CADM

-

-

-

15.7

Emond

156

206 ( a 2,284 hours)

181

CADM

-

-

-

32.9

Emond

300

391 ( a 2,284 hours)

340

CADM

-

-

-

71.4

Emond

610

788 (@. 2,284 hours)

676

CADM

-

-

-

BOUND LIVER (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

2.14

Emond

6.41

8.55 (@. 2,284 hours)

7.74

CADM

-

-

-

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7.14

Emond

13.9

17.6 (@. 2,284 hours)

15.8

CADM

-

-

-

15.7

Emond

22.2

27.2 (@. 2,284 hours)

24.5

CADM

-

-

-

32.9

Emond

33.2

39.3 (@. 2,284 hours)

35.7

CADM

-

-

-

71.4

Emond

47.9

55.1 (@. 2,284 hours)

50.7

CADM

-

-

-

1

2

3	C.3.1.24. NTP (2006) 31 Weeks

Type:

Rat

Dose:

0, 3, 10, 22, 46, 100 ng/kg-day

Strain:

Sprague Dawley

Route:

Oral gavage

Body
weight:

8 weeks old
(BW=215g)

Regime:

5 days/weeks for 31 weeks

Sex:

Female and male

Simulation time:

5,208 hours (31 weeks)

4

WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

2.14

Emond

2.33

3.25 (@. 3,960 hours)

2.48

CADM

-

-

-

7.14

Emond

5.32

7.89 (@. 3,960 hours)

5.40

CADM

-

-

-

15.7

Emond

9.21

14.5 (@. 3,960 hours)

9.15

CADM

-

-

-

32.9

Emond

15.7

26.2 (@ 5,136 hours)

15.3

CADM

-

-

-

71.4

Emond

28.1

50.4 (@ 5,136 hours)

27.0

CADM

-

-

-

LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

2.14

Emond

341

425 (@. 5,140 hours)

373

CADM

-

-

-

7.14

Emond

1,075

1,308 (@. 3,965 hours)

1,117

CADM

-

-

-

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15.7

Emond

2,296

2,756 (@ 3,965 hours)

2,336

CADM

-

-

-

32.9

Emond

4,696

5,597 (@ 5,141 hours)

4,712

CADM

-

-

-

71.4

Emond

10,033

11,905 (@ 5,141 hours)

9,953



CADM

-

-

-

FA T CONCENTRA TIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

2.14

Emond

220

256 (@ 5,149 hours)

246

CADM

-

-

-

7.14

Emond

501

570 (@ 4,139 hours)

542

CADM

-

-

-

15.7

Emond

868

978 (@ 4,138 hours)

926

CADM

-

-

-

32.9

Emond

1,476

1,657 (@ 5,145 hours)

1,558

CADM

-

-

-

71.4

Emond

2,652

2,978 (@ 5,144 hours)

2,775

CADM

-

-

-

BODY BURDEN (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

2.14

Emond

34.2

41.2 (@5,140 hours)

37.8

CADM

-

-

-

7.14

Emond

91.6

108 (@ 3,964 hours)

96.6

CADM

-

-

-

15.7

Emond

178

209 (@ 3,964 hours)

184

CADM

-

-

-

32.9

Emond

339

398 (@ 5,140 hours)

346

CADM

-

-

-

71.4

Emond

682

799 (@ 5,140 hours)

687

CADM

-

-

-

BOUND LIVER (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

2.14

Emond

7.48

8.83 (@ 5,140 hours)

8.01

CADM

-

-

-

7.14

Emond

15.6

17.9 (@ 3,964 hours)

16.1

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CADM

-

-

-

15.7

Emond

24.3

27.4 (@. 3,964 hours)

24.8

CADM

-

-

-

32.9

Emond

35.7

39.6 (@. 5,140 hours)

36.0

CADM

-

-

-

71.4

Emond

50.9

55.4 (@, 5,140 hours)

51.1

CADM

-

-

-

1

2

3	C.3.1.25. NTP (2006) 53 Weeks

Type:

Rat

Dose:

0,3, 10, 22, 46, lOOng/kg-day

Strain:

Sprague Dawley

Route:

Oral gavage

Body
weight:

8 weeks old
(BW=215g)

Regime:

5 days/weeks for 105 weeks

Sex:

Female and male

Simulation time:

8,904 hours (53 weeks)

4

WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

2.14

Emond

2.46

3.25 (@ 6,312 hours)

2.48

CADM

-

-

-

7.14

Emond

5.53

7.89 (@. 3,960 hours)

5.41

CADM

-

-

-

15.7

Emond

9.54

14.5 (@. 8,832 hours)

9.17

CADM

-

-

-

32.9

Emond

16.2

26.3 (@. 8,832 hours)

15.3

CADM

-

-

-

71.4

Emond

29.0

50.6 (@. 8,832 hours)

27.1

CADM

-

-

-

LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

2.14

Emond

366

426 (@ 6,316 hours)

373

CADM

-

-

-

7.14

Emond

1,134

1,308 (@. 3,965 hours)

1,121

CADM

-

-

-

15.7

Emond

2,406

2,759 (@. 8,837 hours)

2,345

CADM

-

-

-

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32.9

Emond

4,902

5,612 (@ 8,837 hours)

4,727

CADM

-

-

-

71.4

Emond

10,439

11,938 (@ 8,837 hours)

9,985

CADM

-

-

-

FA T CONCENTRA TIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

2.14

Emond

233

256 (@ 6,325 hours)

247

CADM

-

-

-

7.14

Emond

524

570 (@ 4,139 hours)

544

CADM

-

-

-

15.7

Emond

904

980 (@ 8,842 hours)

929

CADM

-

-

-

32.9

Emond

1,533

1,661 (@ 8,841 hours)

1,562

CADM

-

-

-

71.4

Emond

2,749

2,986 (@ 8,840 hours)

2,784

CADM

-

-

-

BODY BURDEN (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

2.14

Emond

36.4

41.2 (@ 6,316 hours)

37.8

CADM

-

-

-

7.14

Emond

96.1

108 (@ 3,964 hours)

96.9

CADM

-

-

-

15.7

Emond

186

210 (@ 8,836 hours)

185

CADM

-

-

-

32.9

Emond

353

399 (@ 8,836 hours)

347

CADM

-

-

-

71.4

Emond

709

801 (@ 8,836 hours)

689

CADM

-

-

-

BOUND LIVER (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

2.14

Emond

7.87

8.84 (@6,316 hours)

8.01

CADM

-

-

-

7.14

Emond

16.2

17.9 (@ 3,964 hours)

16.1

CADM

-

-

-

15.7

Emond

25.1

27.5 (@ 8,836 hours)

24.8

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CADM

-

-

-

32.9

Emond

36.6

39.7 (@. 8,836 hours)

36.1

CADM

-

-

-

71.4

Emond

51.9

55.4 (@. 8,836 hours)

51.1

CADM

-

-

-

1

2

3	C.3.1.26. NTP (2006) 2 Years

Type:

Rat

Dose:

0, 3, 10, 22, 46, 100 ng/kg-day

Strain:

Sprague Dawley

Route:

Oral gavage

Body
weight:

8 weeks old
(BW=215g)

Regime:

5 days/weeks for 105 weeks

Sex:

Female and male

Simulation time:

17,640 hours* (105 weeks)

4	*The CADM model simulates for 104 weeks only (17,472 hours). As a result, the terminal values from the CADM

5	model may be underestimated compared to the Emond model, which considers the full 105 weeks of exposure.

6

WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

2.14

Emond

2.56

3.47 (@. 17,568 hours)

2.62

CADM

-

-

-

7.14

Emond

5.69

7.97 (@. 17,568 hours)

5.46

CADM

-

-

-

15.7

Emond

9.79

14.6 (@. 17,568 hours)

9.22

CADM

-

-

-

32.9

Emond

16.6

26.4 (@. 17,568 hours)

15.4

CADM

-

-

-

71.4

Emond

29.7

50.8 (@. 17,568 hours)

27.1

CADM

-

-

-

LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

2.14

Emond

385

460 (@. 17,572 hours)

403

CADM

632

715

715

7.14

Emond

1,177

1,320 (@. 17,573 hours)

1,135

CADM

2,127

2,387

2,387

15.7

Emond

2,487

2,779 (@. 17,573 hours)

2,361

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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CADM

4,691

5,252

5,252

32.9

Emond

5,051

5,637 (@ 17,573 hours)

4,749

CADM

9,822

10,984

10,984

71.4

Emond

10,734

11,976 (@ 17,573 hours)

10,018

CADM

21,366

23,880

23,880

FA T CONCENTRA TIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

2.14

Emond

243

271 (@ 17,581 hours)

261

CADM

302

355

277

7.14

Emond

541

575 (@ 17,579 hours)

549

CADM

667

787

611

15.7

Emond

930

985 (@ 17,578 hours)

934

CADM

1,242

1,463

1,138

32.9

Emond

1,574

1,667 (@ 17,577 hours)

1,568

CADM

2,369

2,787

2,173

71.4

Emond

2,821

2,995 (@ 17,576 hours)

2,792

CADM

4,890

5,748

4,489

BODY BURDEN (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

2.14

Emond

38.1

44.0 (@ 17,572 hours)

40.4

CADM

46.0

48.0

48.0

7.14

Emond

99.5

109 (@ 17,572 hours)

97.9

CADM

125

130

130

15.7

Emond

192

211 (@ 17,572 hours)

186

CADM

257

267

267

32.9

Emond

364

400 (@ 17,572 hours)

348

CADM

520

538

538

71.4

Emond

729

804 (@ 17,572 hours)

691

CADM

1,110

1,149

1,149

BOUND LIVER (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

2.14

Emond

8.17

9.30 (@ 17,572 hours)

8.43

This document is a draft for review purposes only and does not constitute Agency policy.

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CADM

-

-

-

7.14

Emond

16.6

18.0 (@ 17,572 hours)

16.2

CADM

-

-

-

15.7

Emond

25.6

27.6 (@ 17,572 hours)

24.9

CADM

-

-

-

32.9

Emond

37.3

39.7 (@ 17,572 hours)

36.2

CADM

-

-

-

71.4

Emond

52.7

55.5 (@ 17,572 hours)

51.2

CADM

-

-

-

1

2

3	C.3.1.27. Sewall et al (1995)

Type:

Rat

Dose:

49, 149.8, 490, and 1750 ng/kg every two
weeks or 3.5, 10.7, 35, and 125 ng/kg-day

Strain:

Sprauge-Dawley

Route:

Oral gavage

Body weight:

12 wk old
(BW set to 25 Og)

Regime:

Once every 2 weeks for 30 weeks

Sex:

Female

Simulation time:

5040 hours

4

WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

3.5

Emond

3.29

13.7 (@ 4,704 hours)

2.88

CADM

-

-

-

10.7

Emond

7.11

38.7 (@ 4,704 hours)

5.79

CADM

-

-

-

35

Emond

16.6

120 (@ 4,704 hours)

12.6

CADM

-

-

-

125

Emond

44.7

414 (@ 4,704 hours)

31.4

CADM

-

-

-

LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

3.5

Emond

550

901 (@4,711 hours)

459

CADM

-

-

-

10.7

Emond

1,605

2,632 (@ 4,712 hours)

1,229

CADM

-

-

-

35

Emond

5,072

8,350 (@ 4,712 hours)

3,618

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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CADM

-

-

-

125

Emond

17,683

29,256 (@ 4,713 hours)

12,011

CADM

-

-

-

FA T CONCENTRA TIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

3.5

Emond

310

383 (@ 4,765 hours)

290

CADM

-

-

-

10.7

Emond

670

827 (@ 4,763 hours)

590

CADM

-

-

-

35

Emond

1,569

1,957 (@ 4,760 hours)

1,304

CADM

-

-

-

125

Emond

4,217

5,376 (@ 4,757 hours)

3,303

CADM

-

-

-

BODY BURDEN (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

3.5

Emond

51.4

72.5 (@ 4,710 hours)

45.3

CADM

-

-

-

10.7

Emond

130

189 (@ 4,710 hours)

106

CADM

-

-

-

35

Emond

364

546 (@ 4,710 hours)

274

CADM

-

-

-

125

Emond

1,164

1,793 (@ 4,710 hours)

824

CADM

-

-

-

BOUND LIVER (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

3.5

Emond

10.2

15.8 ( a 2 hours)

9.18

CADM

-

-

-

10.7

Emond

19.8

34.4 (@ 1 hours)

17.0

CADM

-

-

-

35

Emond

37.0

63.2 (a 1 hours)

31.4

CADM

-

-

-

125

Emond

63.1

90.9 ( a 1 hours)

55.2

CADM

-

-

-

1

2

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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1 C.3.1.28. Shi et ah (2007) Adult Portion

Type:

Rat

Dose:

1, 5, 50 and 200 ng/kg

Strain:

Sprague Dawley

Route:

Oral exposure

Body weight:

BW set to 4.5 g

Regime:

Weekly doses for 11 months

Sex:

Female

Simulation time:

8040 hours

2

WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

0.143

Emond

0.342

0.475 (@. 7,561 hours)

0.380

CADM

-

-

-

0.714

Emond

1.07

1.53 (@. 7,560 hours)

1.09

CADM

-

-

-

7.14

Emond

5.23

9.12 (@. 7,560 hours)

4.86

CADM

-

-

-

28.6

Emond

13.9

29.2 (@. 7,560 hours)

12.4

CADM

-

-

-

LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

0.143

Emond

26.1

36.5 (@. 7,564 hours)

29.6

CADM

-

-

-

0.714

Emond

118

159 (@. 7,564 hours)

120

CADM

-

-

-

7.14

Emond

1,068

1,415 (@. 7,565 hours)

970

CADM

-

-

-

28.6

Emond

4,119

5,450 (@. 7,565 hours)

3,574

CADM

-

-

-

FA T CONCENTRA TLONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

0.143

Emond

32.5

40.0 (@. 7,583 hours)

36.7

CADM

-

-

-

0.714

Emond

102

120 (@. 7,584 hours)

106

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-l50 DRAFT—DO NOT CITE OR QUOTE


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7.14

Emond

497

571 (@. 7,584 hours)

475

CADM

-

-

-

28.6

Emond

1,322

1,527 (@. 7,584 hours)

1,217

CADM

-

-

-

BODY BURDEN (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

0.143

Emond

3.94

4.99 (@. 7,566 hours)

4.45

CADM

-

-

-

0.714

Emond

14.0

17.2 (@. 7,566 hours)

14.5

CADM

-

-

-

7.14

Emond

90.8

112 (@ 7,566 hours)

84.4

CADM

-

-

-

28.6

Emond

300

374 (@. 7,566 hours)

266

CADM

-

-

-

BOUND LIVER (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

0.143

Emond

1.18

1.60 (@. 7,563 hours)

1.31

CADM

-

-

-

0.714

Emond

3.62

4.75 (@. 7,563 hours)

3.70

CADM

-

-

-

7.14

Emond

15.6

19.7 (@. 7,564 hours)

14.7

CADM

-

-

-

28.6

Emond

33.5

40.7 (@. 7,564 hours)

31.2

CADM

-

-

-

1

2

3	C.3.1.29. Smialowicz et al. (2008)

Type:

Mice

Dose:

0, 1.5, 15, 150, 450 ng/kg-day

Strain:

B6C3F1

Route:

Oral gavage

Body weight:

13 wk old
(BW set to 28g)

Regime:

5 days/week for 13 weeks

Sex:

Female

Simulation time:

2184

4

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-151 DRAFT—DO NOT CITE OR QUOTE


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WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1.07

Emond

0.438

0.815 (@ 2,112 hours)

0.557

CADM

-

-

-

10.7

Emond

2.46

5.12 (@ 2,112 hours)

2.65

CADM

-

-

-

107

Emond

13.4

36.4 (@ 2,112 hours)

12.7

CADM

-

-

-

321

Emond

31.6

98.6 (@2,112 hours)

28.4

CADM

-

-

-

LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1.07

Emond

67.1

107 (@2,116 hours)

91.5

CADM

59.0

92.0

88.0

10.7

Emond

683

971 (@2,117 hours)

787

CADM

767

1,000

907

107

Emond

6,784

9,010 (@2,117 hours)

7,043

CADM

8,349

10,306

8,998

321

Emond

20,218

26,379 (@2,117 hours)

20,405

CADM

25,344

31,006

26,967

FA T CONCENTRA TIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1.07

Emond

156

229 (@ 2,130 hours)

225

CADM

151

210

204

10.7

Emond

885

1,155 (@2,124 hours)

1,111

CADM

689

815

774

107

Emond

4,831

5,979 (@ 2,120 hours)

5,591

CADM

2,771

3,224

2,937

321

Emond

11,420

14,037 (@2,119 hours)

12,920

CADM

6,337

7,509

6,688

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-l52 DRAFT—DO NOT CITE OR QUOTE


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BODY BURDEN (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1.07

Emond

17.0

25.5 (@ 2,116 hours)

23.9

CADM

21.0

29.0

29.0

10.7

Emond

117

159 (@ 2,116 hours)

141

CADM

119

145

135

107

Emond

852

1,103 (@ 2,116 hours)

923

CADM

727

875

778

321

Emond

2,304

2,958 (@2,116 hours)

2,419

CADM

1,961

2,370

2,080

BOUND LIVER (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1.07

Emond

1.48

2.17 (@2,116 hours)

1.90

CADM

-

-

-

10.7

Emond

7.60

9.86 (@2,116 hours)

8.42

CADM

-

-

-

107

Emond

30.3

36.0 (@2,117 hours)

31.1

CADM

-

-

-

321

Emond

51.1

58.1 (@2,117 hours)

51.8

CADM

-

-

-

1

2

3	C.3.1.30. Toth et al, 1 Year (1979)

Type:

Mice

Dose:

7, 700, 7000 ng/kg/week

Strain:

Swiss/H/Riop

Route:

Oral gavage
In gastric tube

Body weight:

10 weeks old (BW=
27g)

Regime:

1/week for 1 year (365 days)

Sex:

Female and male

Simulation time:

8,760 hours

We did not simulate the scenario using the CADM model because this model can only be run for a maximum of 123
days.

4

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-l53 DRAFT—DO NOT CITE OR QUOTE


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WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1

Emond

0.573

1.61 (@ 8,736 hours)

0.682

CADM

-

-

-

100

Emond

14.2

116 (@ 8,736 hours)

15.7

CADM

-

-

-

1,000

Emond

91.2

1,108 (@ 8,736 hours)

99.3

CADM

-

-

-

LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1

Emond

94.2

131 (@ 8,743 hours)

123

CADM

-

-

-

100

Emond

7,343

10,134 (@ 8,745 hours)

9,604

CADM

-

-

-

1,000

Emond

70,243

97,658 (@ 8,745 hours)

92,506

CADM

-

-

-

FA T CONCENTRA TLONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1

Emond

215

247 (@ 8,613 hours)

245

CADM

-

-

-

100

Emond

5,339

5,914 (@ 8,760 hours)

5,914

CADM

-

-

-

1,000

Emond

34,249

38,828 (@ 8,756 hours)

38,807

CADM

-

-

-

BODY BURDEN (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1

Emond

23.4

28.4 (@ 8,742 hours)

27.9

CADM

-

-

-

100

Emond

929

1,189 (@ 8,742 hours)

1,132

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-l54 DRAFT—DO NOT CITE OR QUOTE


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1,000

Emond

7,569

10,045 (@ 8,742 hours)

9,471

CADM

-

-

-

BOUND LIVER (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

1

Emond

1.93

2.65 (@ 8,741 hours)

2.35

CADM

-

-

-

100

Emond

31.8

58.4 (@ 2 hours)

36.7

CADM

-

-

-

1,000

Emond

78.6

103 ( a 2 hours)

84.8

CADM

-

-

-

1

2

3	C.3.1.31. Van Birgelen et ah (1995)

Type:

Rat

Dose:

0, 13.5, 26.4, 46.9, 320, 1024 ng/kg-
day

Strain:

Sprague Dawley

Route:

Oral gavage

Body weight:

150 g

Regime:

Once per day for 13 weeks

Sex:

Female

Simulation time:

2184 hours (13 weeks)

4

WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

13.5

Emond

7.20

11.1 (@ 2,160 hours)

8.47

CADM

-

-

-

26.4

Emond

11.8

18.6 (@ 2,160 hours)

13.5

CADM

-

-

-

46.9

Emond

18.1

29.6 (@ 2,160 hours)

20.5

CADM

-

-

-

320

Emond

86.4

156 (@2,160 hours)

95.4

CADM

-

-

-

1024

Emond

250

470 (@2,160 hours)

275

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-155 DRAFT—DO NOT CITE OR QUOTE


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LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

13.5

Emond

1,655

2,208 (@ 2,164 hours)

2,107

CADM

-

-

-

26.4

Emond

3,228

4,216 (@ 2,164 hours)

4,017

CADM

-

-

-

46.9

Emond

5,719

7,366 (@ 2,164 hours)

7,008

CADM

-

-

-

320

Emond

38,484

47,999 (@ 2,164 hours)

45,537

CADM

-

-

-

1024

Emond

121,640

150,410 (@ 2,164 hours)

142,510

CADM

-

-

-

FA T CONCENTRA TIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

13.5

Emond

669

843 (@ 2,167 hours)

835

CADM

-

-

-

26.4

Emond

1,092

1,357 (@ 2,166 hours)

1,342

CADM

-

-

-

46.9

Emond

1,680

2,071 (@2,166 hours)

2,045

CADM

-

-

-

320

Emond

8,027

9,816 (@2,165 hours)

9,639

CADM

-

-

-

1024

Emond

23,234

28,519 (@2,165 hours)

27,954

CADM

-

-

-

BODY BURDEN (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

13.5

Emond

132

173 (@ 2,164 hours)

167

CADM

-

-

-

26.4

Emond

240

308 (@ 2,164 hours)

296

CADM

-

-

-

46.9

Emond

404

513 (@2,164 hours)

492

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-l56 DRAFT—DO NOT CITE OR QUOTE


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320

Emond

2,437

3,031 (@ 2,164 hours)

2,887

CADM

-

-

-

1024

Emond

7,521

9,310 (@ 2,164 hours)

8,846

CADM

-

-

-

BOUND LIVER (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

13.5

Emond

19.9

24.2 (@ 2,164 hours)

23.4

CADM

-

-

-

26.4

Emond

29.0

34.3 (@ 2,164 hours)

33.2

CADM

-

-

-

46.9

Emond

38.8

45.0 (@ 2,164 hours)

43.7

CADM

-

-

-

320

Emond

79.1

85.2 (@ 2,164 hours)

84.1

CADM

-

-

-

1024

Emond

97.5

101 (@2,164 hours)

101

CADM

-

-

-

1

2

3	C.3.1.32. Vantlen Heuvel et a I. (1994)

Type:

Rat

Dose:

0.05, 0.1, 1, 10, 100, 1000, 10000 ng/kg/d

Strain:

Sprague Dawley

Route:

Oral gavage

Body
weight:

10 weeks old
(BW 225 to 275g, set
to 25 Og)

Regime:

Single dose

Sex:

Female

Simulation
time:

24 hours *

4	* 1 week is the minimum that can be simulated with the C ADM model, so the CADM model was not used.

5

WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

0.05

Emond

0.01

0.011 (@ 0 hours)

0.0039

CADM

-

-

-

0.1

Emond

0.0113

0.022 (@ 0 hours)

0.008

CADM

-

-

-

1

Emond

0.106

0.215 (@ 0 hours)

0.0723

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-157 DRAFT—DO NOT CITE OR QUOTE


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10

Emond

0.883

2.15 (@, 0 hours)

0.583

CADM

-

-

-

100

Emond

6.45

21.5 {(cf 0 hours)

3.85

CADM

-

-

-

1000

Emond

48.3

216 ( a 0 hours)

23.9

CADM

-

-

-

10000

Emond

435

2,166 ( a 0 hours)

186

CADM

-

-

-

LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

0.05

Emond

0.232

0.315 ((ai 3 hours)

0.173

CADM

-

-

0.0140

0.1

Emond

0.469

0.631 ( a 3 hours)

0.353

CADM

-

-

0.0320

1

Emond

5.08

6.42 {(cf 4 hours)

4.08

CADM

-

-

0.950

10

Emond

60.2

68.7 (@, 5 hours)

54.1

CADM

-

-

52.7

100

Emond

730

800 ( a 9 hours)

719

CADM

-

-

1,342

1000

Emond

8,186

8,919 (@. 11 hours)

8,442

CADM

-

-

15,967

10000

Emond

84,254

91,675 (@. 11 hours)

88,230

CADM

-

-

162,773

FA T CONCENTRA TIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

0.05

Emond

0.138

0.215 (@. 24 hours)

0.215

CADM

-

-

0.780

0.1

Emond

0.274

0.427 (@. 24 hours)

0.427

CADM

-

-

1.57

1

Emond

2.58

3.97 ( a 24 hours)

3.97

CADM

-

-

15.3

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-158 DRAFT—DO NOT CITE OR QUOTE


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10

Emond

22.1

32.8 (@. 24 hours)

32.8

CADM

-

-

125

100

Emond

170

235 ( a 24 hours)

235

CADM

-

-

739

1000

Emond

1,348

1,720 (@. 24 hours)

1,720

CADM

-

-

5,779

10000

Emond

12,500

15,265 (@. 24 hours)

15,265

CADM

-

-

55,825

BODY BURDEN (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

0.05

Emond

0.0269

0.028 ((ai 9 hours)

0.0283

CADM

-

-

0.0450

0.1

Emond

0.0538

0.057 ((ci\ 9 hours)

0.0565

CADM

-

-

0.0900

1

Emond

0.536

0.568 ((ai 9 hours)

0.562

CADM

-

-

0.900

10

Emond

5.32

5.65 ( a 8 hours)

5.55

CADM

-

-

9.00

100

Emond

52.8

56.3 {(cf 1 hours)

54.4

CADM

-

-

90.0

1000

Emond

525

562 ( a 1 hours)

538

CADM

-

-

900

10000

Emond

5,238

5,610 ( a 1 hours)

5,353

CADM

-

-

9,000

BOUND LIVER (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted Ave

Max

Terminal

0.05

Emond

0.0194

0.027 (@. 3 hours)

0.0142

CADM

-

-

-

0.1

Emond

0.0383

0.054 ((ai 3 hours)

0.0281

CADM

-

-

-

1

Emond

0.353

0.506 ((ai 3 hours)

0.261

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-l59 DRAFT—DO NOT CITE OR QUOTE


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10

Emond

2.77

4.24 (@ 2 hours)

2.08

CADM

-

-

-

100

Emond

16.1

26.4 ( a 2 hours)

12.4

CADM

-

-

-

1000

Emond

57.4

80.2 ( a 1 hours)

48.5

CADM

-

-

-

10000

Emond

100

108 ( a 1 hours)

96.1

CADM

-

-

-

1

2

3	C.3.1.33. White et al (1986)

Type:

Mice

Dose:

10, 50, 100, 500, 1000, 2000 ng/kg-day

Strain:

B6C3F1

Route:

Oral gavage

Body weight:

7 weeks old (BW set
to 23g)

Regime:

1/day for 14 days

Sex:

Female

Simulation time:

336 hours

4

WHOLE BLOOD CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted

Ave

Max

Terminal

10

Emond

1.09

2.73 (@ 312 hours)

1.42

CADM

-

-

-

50

Emond

4.08

11.6 (@ 312 hours)

4.98

CADM

-

-

-

100

Emond

7.14

21.7 (@ 312 hours)

8.44

CADM

-

-

-

500

Emond

26.8

96.5 (@312 hours)

29.8

CADM

-

-

-

1,000

Emond

48.7

187 (@312 hours)

53.1

CADM

-

-

-

2,000

Emond

90.6

365 (@312 hours)

97.5

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-160 DRAFT—DO NOT CITE OR QUOTE


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LIVER CONCENTRATIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted
Ave

Max

Terminal

10

Emond

216

375 (@317 hours)

343

CADM

217

468 (336h)

463

50

Emond

1,279

2,164 (@317 hours)

1,997

CADM

1,775

3,261 (336h)

3,261

100

Emond

2,707

4,525 (@ 317 hours)

4,184

CADM

3,999

6,923 (336h)

6,923

500

Emond

14,802

24,165 (@317 hours)

22,383

CADM

22,705

36,362 (336h)

36,362

1,000

Emond

30,278

49,034 (@317 hours)

45,414

CADM

46,309

73,145 (336h)

73,145

2,000

Emond

61,381

98,703 (@317 hours)

91,363

CADM

93,577

146,695 (336h)

146,695

FA T CONCENTRA TIONS (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted
Ave

Max

Terminal

10

Emond

279

507 (@ 336 hours)

507

CADM

316

537 (336h)

537

50

Emond

1,056

1,846 (@ 336 hours)

1,846

CADM

1,029

1,564 (336h)

1,564

100

Emond

1,854

3,195 (@ 333 hours)

3,195

CADM

1,662

2,470 (336h)

2,470

500

Emond

7,008

11,868 (@324 hours)

11,816

CADM

5,711

8,594 (336h)

8,594

1,000

Emond

12,746

21,566 (@ 323 hours)

21,424

CADM

10,498

15,993 (336h)

15,993

2,000

Emond

23,691

40,177 (@ 322 hours)

39,843

CADM

19,990

30,726 (336h)

30,726

This document is a draft for review purposes only and does not constitute Agency policy.

C-161 DRAFT—DO NOT CITE OR QUOTE


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BODY BURDEN (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted

Ave

Max

Terminal

10

Emond

37.7

65.9 (@ 317 hours)

63.8

CADM

47.9

85.9 (336h)

85.9

50

Emond

175

297 (@ 317 hours)

284

CADM

207

342 (336h)

342

100

Emond

338

570 (@ 316 hours)

542

CADM

388

624 (336h)

624

500

Emond

1,597

2,637 (@ 316 hours)

2,480

CADM

1,761

2,754 (336h)

2,754

1,000

Emond

3,137

5,153 (@316 hours)

4,830

CADM

3,455

5,387 (336h)

5,387

2,000

Emond

6,186

10,118 (@316 hours)

9,459

CADM

6,836

10,643 (336h)

10,643

BOUND LIVER (ng/kg)

Dose
(ng/kg-day)
Adjusted dose

Model

Metric

Time-weighted

Ave

Max

Terminal

10

Emond

3.49

5.32 (@316 hours)

4.82

CADM

-

-

-

50

Emond

11.4

16.4 (@317 hours)

15.1

CADM

-

-

-

100

Emond

18.1

25.1 (@317 hours)

23.4

CADM

-

-

-

500

Emond

44.2

56.2 (@317 hours)

53.8

CADM

-

-

-

1,000

Emond

59.3

71.9 (@317 hours)

69.7

CADM

-

-

-

2,000

Emond

74.4

86.1 (@317 hours)

84.3

CADM

-

-

-

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

C-162 DRAFT—DO NOT CITE OR QUOTE


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1	C.3.2. Gestational Studies

2	C.3.2.1. Bell et aL (2007)

Type:

Rat

Dose:

2.4, 8, and 46 ng/kg-day with a 0.03 ng/kg-day
background

Strain:

Han/Wistar

Route:

Diet oral dose

Body weight:

6 weeks
(BW= 85g)

Regime:

Once per day for 12 weeks prior to mating, during the
two week mating period, and during gestation

Sex:

Female

Simulation
time:

2,352 hr (98 days) prior to gestation + 504 hr (21 days)
during gestation for a total simulation of 2,856 hours

3	* Time averages are computed during the gestation period only.

4

WHOLE BLOOD CONCENTRATIONS (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

2.43

2.20

6,295

3.10 (@ 2,352 hours)

2.20

8.03

5.14

14,674

7.31 (@ 2,352 hours)

5.08

46.03

18.4

52,584

28.1 (@ 2,352 hours)

18.1

LIVER CONCENTRATIONS (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

2.43

320

914,290

437 (@ 2,356 hours)

321

8.03

1,040

2,969,800

1,349 (@2,356
hours)

1,042

46.03

5,892

16,829,000

7,289 (@ 2,356
hours)

6,007

FAT CONCENTRATIONS (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

2.43

205

585,530

263 (@ 2,336 hours)

211

8.03

478

1,365,100

589 (@ 2,335 hours)

486

46.03

1,713

4,891,500

2,045 (@ 2,334
hours)

1,745

This document is a draft for review purposes only and does not constitute Agency policy.

C-163 DRAFT—DO NOT CITE OR QUOTE


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BODY BURDEN (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

2.43

33.0

94,390

44.4 (@ 2,836 hours)

43.4

8.03

90.4

258,110

117 (@ 2,836 hours)

114

46.03

422

1,206,500

531 (@ 2,836 hours)

511

FETUS (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

2.43

3.03

8,648

39.6 (@ 2,530 hours)

6.48

8.03

6.65

18,999

86.7 (@ 2,529 hours)

14.4

46.03

20.9

59,794

272 (@ 2,527 hours)

46.0

BOUND LIVER (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

2.43

7.10

20,289

8.98 (@ 2,356 hours)

7.23

8.03

15.1

43,242

18.2 (@ 2,356 hours)

15.4

46.03

39.6

113,070

44.8 (@ 2,356 hours)

40.6

1

2

3	C.3.2.2. Haavisto et al. (2006)

Type:

Rat

Dose:

20, 400, and 1,000 ng/kg

Strain:

Sprague Dawley

Route:

Oral exposure

Body weight

BW = 190 g

Regime:

Single dose on GDI3

Sex:

Female

Simulation time

336 hours

4

WHOLE BLOOD CONCENTRATIONS (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

20

2.86

68.9

8.01 (@312 hours)

1.73

400

11.3

273

40.1 (@312 hours)

6.28

1000

46.9

1,129

202 (@312 hours)

22.8

This document is a draft for review purposes only and does not constitute Agency policy.

C-164 DRAFT—DO NOT CITE OR QUOTE


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LIVER CONCENTRATIONS (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

20

265

6,371

298 (@319 hours)

244

400

1,497

36,005

1,653 (@ 320 hours)

1,462

1000

8,061

193,860

8,832 (@321 hours)

8,147

FAT CONCENTRATIONS (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

20

56.3

1,354

81.9 (@ 336 hours)

81.9

400

232

5,584

321 (@ 336 hours)

321

1000

1,002

24,084

1,313 (@336 hours)

1,313

BODY BURDEN (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

20

21.1

508

22.5 (@319 hours)

21.9

400

105

2,528

112 (@319 hours)

108

1000

524

12,612

561 (@319 hours)

538

FETUS (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

20

8.47

203

11.3 (@ 336 hours)

11.3

400

31.2

751

40.3 (@ 336 hours)

40.3

1000

112

2,689

139 (@ 336 hours)

139

BOUND LIVER (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

20

8.20

197

13.5 (@ 314 hours)

6.03

400

24.9

598

40.8 (@313 hours)

19.1

1000

57.1

1,373

80.1 (@313 hours)

47.7

This document is a draft for review purposes only and does not constitute Agency policy.

C-165 DRAFT—DO NOT CITE OR QUOTE


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1 C.3.2.3. Hojo et al. (2002)

Type:

Rat

Dose:

20, 60 and 180 ng/kg

Strain:

Sprague Dawley

Route:

Oral exposure

Body weight

20 ng/kg BW = 27 lg
60 ng/kg BW = 275g
180 ng/kg BW = 262g

Regime:

Single dose on GD8

Sex:

Female

Simulation time

216 hours

2

WHOLE BLOOD CONCENTRATIONS (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

20

1.62

39.1

4.47 (@ 192 hours)

1.02

60

4.17

100

13.3 (@ 192 hours)

2.50

180

10.7

258

40.3 (@ 192 hours)

5.96

LIVER CONCENTRATIONS (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

20

128

20,554

144 (@ 198 hours)

43.2

60

420

72,340

465 (@ 200 hours)

147

180

1,364

250,820

1,497 (@ 201 hours)

497

FAT CONCENTRATIONS (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

20

32.5

17,253

63.0 (@ 281 hours)

49.4

60

86.4

44,093

161 (@ 284 hours)

124

180

226

108,730

398 (@ 286 hours)

301

BODY BURDEN (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

20

10.6

3,054

11.3 (@ 200 hours)

8.67

60

31.8

8,702

33.8 (@ 199 hours)

23.6

180

95.0

24,747

101 (@ 199 hours)

63.4

This document is a draft for review purposes only and does not constitute Agency policy.

C-166 DRAFT—DO NOT CITE OR QUOTE


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FETUS (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

20

15.9

2,334

18.4 (@ 206 hours)

1.64

60

39.8

5,829

45.7 (@ 205 hours)

4.10

180

96.3

13,866

110 (@ 203 hours)

9.72

BOUND LIVER (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

20

4.88

759

7.74 (@ 194 hours)

1.75

60

11.2

1,848

18.5 (@ 194 hours)

4.26

180

23.6

4,157

38.5 (@ 193 hours)

9.65

1

2

3	C.3.2.4. Ikeda et al. (2005)

Type:

Rat

Dose:

400 ng/kg single dose and 80 ng/kg weekly
maintenance dose

Strain:

Sprague Dawley

Route:

Oral gavage

Body weight:

10 weeks
(BW= 25 Og)

Regime:

400 ng/kg single dose, two weekly maintenance
doses prior to gestation and weekly maintenance
doses during gestation

Sex:

Female

Simulation
time:

504 hr (21 days) prior to gestation + 504 hr (21 days)
during gestation for a total simulation of 1,008 hours

4

WHOLE BLOOD CONCENTRATIONS (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

16.5

22.9

23,086

101 (@ 144 hours)

10.1

LIVER CONCENTRATIONS (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

16.5

7,755

7,817,300

17,016 (@ 150 hours)

2,698

This document is a draft for review purposes only and does not constitute Agency policy.

C-167 DRAFT—DO NOT CITE OR QUOTE


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FAT CONCENTRATIONS (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

16.5

2,087

2,103,900

3,663 (@ 184 hours)

1,028

BODY BURDEN (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

16.5

548

552,590

1,085 (@ 149 hours)

262

FETUS (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

16.5

45.9

46,290

245 (@ 679 hours)

30.2

BOUND LIVER (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

16.5

44.0

44,361

63.8 (@ 149 hours)

26.8

1

2

3	C.3.2.5. Kattainen et al. (2001)

Type:

Rat

Dose:

30, 100, 300, and 1,000 ng/kg

Strain:

Han/Wistar (Kuopio)
and Long/Evans
(Turku/AB) crossing.

Route:

Oral exposure

Body weight:

BW no specify
(BW set to 190g)*

Regime:

Single dose in the GDI5

Sex:

Female

Simulation
time:

360 hours

4	*Derelanko and Hollinger (1995).

5

WHOLE BLOOD CONCENTRATIONS (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

30

2.23

53.7

5.95 (@ 336 hours)

1.36

100

6.25

150

19.8 (@ 336 hours)

3.62

This document is a draft for review purposes only and does not constitute Agency policy.

C-168 DRAFT—DO NOT CITE OR QUOTE


-------
300

16.1

387

59.8 (@ 336 hours)

8.62

1,000

46.9

1,128

200 (@ 336 hours)

22.7

LIVER CONCENTRATIONS (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

30

193

4,648

219 (@ 342 hours)

175

100

713

17,141

793 (@ 344 hours)

680

300

2,298

55,266

2,533 (@ 345 hours)

2,267

1,000

8,055

193,720

8,831 (@345 hours)

8,134

FAT CONCENTRATIONS (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

30

42.8

1,027

62.8 (@ 360 hours)

62.8

100

123

2,964

175 (@ 360 hours)

175

300

327

7,853

446 (@ 360 hours)

446

1,000

981

23,588

1,289 (@ 360 hours)

1,289

BODY BURDEN (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

30

15.9

382

16.9 (@ 343 hours)

16.4

100

52.7

1,266

56.2 (@ 343 hours)

54.3

300

158

3,791

168 (@ 343 hours)

162

1,000

524

12,612

561 (@ 343 hours)

538

FETUS (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

30

4.86

117

6.66 (@ 360 hours)

6.66

100

13.2

317

17.6 (@ 360 hours)

17.6

300

31.5

758

41.2 (@ 360 hours)

41.2

1,000

82.2

1,975

104 (@ 360 hours)

104

This document is a draft for review purposes only and does not constitute Agency policy.

C-169 DRAFT—DO NOT CITE OR QUOTE


-------
BOUND LIVER (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

30

6.57

158

10.7 (@ 338 hours)

4.80

100

15.8

381

26.3 (@ 338 hours)

11.9

300

31.6

760

50.6 (@ 337 hours)

24.7

1,000

57.1

1,373

80.1 (@ 337 hours)

47.7

1

2

3	C.3.2.6. Keller et al. (2007)

Type:

Mouse

Dose:

10, 100, and 1000 ng/kg

Strain:

CBA/J and C3H/HeJ

Route:

Oral

Body weight:

Not specified (24 g
used in the simulation)

Regime:

Single dose at gestation day 13

Sex:

Female

Simulation time:

336 hours

4

WHOLE BLOOD CONCENTRATIONS (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

10

0.537

12.9

1.43 (@312 hours)

0.269

100

4.29

103

14.3 (@312 hours)

1.95

1,000

34.1

820

143 (@312 hours)

12.3

LIVER CONCENTRATIONS (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

10

30.6

737

39.8 (@316 hours)

22.2

100

371

8,922

421 (@319 hours)

317

1,000

4,214

101,360

4,697 (@ 321 hours)

3,940

FAT CONCENTRATIONS (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

10

22.4

538

33.3 (@ 336 hours)

33.3

100

188

4,523

264 (@ 336 hours)

264

1,000

1,591

38,233

2,080 (@ 336 hours)

2,080

This document is a draft for review purposes only and does not constitute Agency policy.

C-170 DRAFT—DO NOT CITE OR QUOTE


-------
BODY BURDEN (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

10

5.57

134

5.99 (@319 hours)

5.72

100

54.3

1,306

59.0 (@318 hours)

54.7

1,000

530

12,747

581 (@318 hours)

524

FETUS (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

10

2.57

61.7

3.80 (@ 336 hours)

3.80

100

21.7

522

30.0 (@ 334 hours)

29.9

1,000

179

4,312

233 (@ 329 hours)

225

BOUND LIVER (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

10

1.74

41.8

3.14 (@315 hours)

1.01

100

11.5

276

23.5 (@314 hours)

6.99

1,000

46.7

1,123

79.8 (@314 hours)

32.9

1

2

3	C.3.2.7. Li et al (2006) 3-Day

Type:

Mouse

Dose:

2, 50, and 100 ng/kg-day

Strain:

NIH

Route:

Oral

Body weight:

25-28 g (used 27 g in
the simulation)

Regime:

Daily exposure from gestation day 1 to
gestation day 8

Sex:

Female

Simulation time:

72 hours

4

WHOLE BLOOD CONCENTRATIONS (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

2

0.159

11.4

0.392 (@ 48 hours)

0.136

50

2.84

205

8.90 (@ 48 hours)

2.38

100

5.12

369

17.3 (@ 48 hours)

4.20

This document is a draft for review purposes only and does not constitute Agency policy.

C-171 DRAFT—DO NOT CITE OR QUOTE


-------
LIVER CONCENTRATIONS (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

2

8.98

647

15.1 (@ 52 hours)

9.10

50

333

23,971

539 (@ 53 hours)

402

100

718

51,738

1,156 (@ 53 hours)

888

FAT CONCENTRATIONS (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

2

17.0

1,227

31.1 (@ 72 hours)

31.1

50

315

22,704

548 (@ 72 hours)

548

100

576

41,460

984 (@ 72 hours)

984

BODY BURDEN (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

2

2.29

165

3.51 (@ 55 hours)

3.43

50

53.6

3,863

82.2 (@ 54 hours)

77.1

100

105

7,598

162 (@ 53 hours)

150

FETUS (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

2

0.00

0

0.000 (@ 72 hours)

0.00

50

0.0

0

0.000 (@ 72 hours)

0.00

100

0.0

0

0.000 (@ 72 hours)

0.00

BOUND LIVER (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

2

0.538

38.8

0.864 (@51 hours)

0.498

50

8.24

594

13.5 (@ 2 hours)

8.16

100

13.6

981

23.7 (@ 2 hours)

13.6

1

2

This document is a draft for review purposes only and does not constitute Agency policy.

C-172 DRAFT—DO NOT CITE OR QUOTE


-------
1 C.3.2.8. Markowski et al. (2001)

Type:

Rat

Dose:

20, 60 and 180 ng/kg

Strain:

Holtzman rats

Route:

Oral exposure

Body weight:

BW no specify
(BW set to 190g)*

Regime:

Single dose in the GD18

Sex:

Female

Simulation
time:

432 hours

2	*Derelanko and Hollinger (1995).

3

WHOLE BLOOD CONCENTRATIONS (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

20

1.56

37.5

3.82 (@ 408 hours)

0.958

60

4.03

97.0

11.5 (@ 408 hours)

2.38

180

10.3

248

34.8 (@ 408 hours)

5.72

LIVER CONCENTRATIONS (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

20

123

2,959

141 (@ 414 hours)

109

60

409

9,843

459 (@ 415 hours)

382

180

1,334

32,086

1,479 (@ 416 hours)

1,295

FAT CONCENTRATIONS (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

20

27.9

670

41.6 (@ 432 hours)

41.6

60

74.0

1,778

107 (@ 432 hours)

107

180

195

4,685

273 (@ 432 hours)

273

BODY BURDEN (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

20

10.6

254

11.2 (@415 hours)

10.9

60

31.7

762

33.8 (@415 hours)

32.7

180

94.7

2,278

101 (@ 415 hours)

97.5

This document is a draft for review purposes only and does not constitute Agency policy.

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FETUS (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

20

1.26

30.2

1.80 (@ 432 hours)

1.80

60

3.21

77.2

4.49 (@ 432 hours)

4.49

180

7.81

188

10.7 (@ 432 hours)

10.7

BOUND LIVER (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

20

4.74

114

7.59 (@410 hours)

3.43

60

11.0

265

18.2 (@410 hours)

8.16

180

23.2

559

38.1 (@ 409 hours)

17.7

1

2

3	C.3.2.9. Mietinnen et al. (2006)

Type:

Rat

Dose:

30, 100, 300 and 1000 ng/kg

Strain:

cross-breeding of
Han/Wistar and Long-
Evans rats

Route:

Oral exposure

Body weight:

BW 11 weeks
(BW set to 180g)

Regime:

Single dose in the GDI5

Sex:

Female

Simulation
time:

360 hours

4

WHOLE BLOOD CONCENTRATIONS (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

30

2.22

53.4

5.87 (@ 336 hours)

1.36

100

6.23

150

19.6 (@ 336 hours)

3.61

300

16.0

386

59.0 (@ 336 hours)

8.61

1,000

46.6

1,123

198 (@ 336 hours)

22.7

This document is a draft for review purposes only and does not constitute Agency policy.

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LIVER CONCENTRATIONS (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

30

193

4,631

219 (@ 342 hours)

174

100

711

17,096

791 (@ 344 hours)

677

300

2,294

55,166

2,530 (@ 345 hours)

2,260

1,000

8,042

193,410

8,820 (@ 345 hours)

8,114

FAT CONCENTRATIONS (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

30

43.0

1,034

63.2 (@ 360 hours)

63.2

100

124

2,984

176 (@ 360 hours)

176

300

329

7,905

449 (@ 360 hours)

449

1,000

987

23,729

1,296 (@ 360 hours)

1,296

BODY BURDEN (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

30

15.9

381

16.9 (@ 343 hours)

16.4

100

52.6

1,266

56.1 (@ 343 hours)

54.3

300

158

3,791

168 (@ 343 hours)

162

1,000

524

12,609

561 (@ 343 hours)

538

FETUS (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

30

4.83

116

6.62 (@ 360 hours)

6.62

100

13.1

315

17.5 (@ 360 hours)

17.5

300

31.3

753

41.0 (@ 360 hours)

41.0

1,000

81.7

1,963

104 (@ 360 hours)

104

BOUND LIVER (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

30

6.56

158

10.7 (@ 338 hours)

4.78

This document is a draft for review purposes only and does not constitute Agency policy.

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100

15.8

381

26.3 (@ 338 hours)

11.9

300

31.6

760

50.5 (@ 337 hours)

24.6

1,000

57.0

1,372

80.1 (@ 337 hours)

47.6

1

2

3	C.3.2.10. Noharaetal. (2000)

Type:

Rat

Dose:

12.5, 50, 200 or 800 ng TCDD/kg

Strain:

Holtzman rats

Route:

Oral exposure

Body weight:

BW no specify
(BW set to 190g)*

Regime:

Single dose in the GDI5

Sex:

Female

Simulation
time:

360 hours

4	*Derelanko and Hollinger (1995).

5

WHOLE BLOOD CONCENTRATIONS (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

12.5

1.03

24.8

2.44 (@ 336 hours)

0.645

50

3.45

82.9

9.78 (@ 336 hours)

2.07

200

11.3

271

39.2 (@ 336 hours)

6.25

800

38.1

918

158 (@ 336 hours)

18.9

LIVER CONCENTRATIONS (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

12.5

73.8

1,776

86.1 (@341 hours)

63.6

50

336

8,084

378 (@ 343 hours)

311

200

1,492

35,890

1,651 (@ 344 hours)

1,454

800

6,389

153,640

7,012 (@ 345 hours)

6,423

FAT CONCENTRATIONS (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

12.5

19.7

473

29.5 (@ 360 hours)

29.5

50

67.6

1,624

97.8 (@ 360 hours)

97.8

200

229

5,504

317 (@360 hours)

317

800

803

19,292

1,061 (@ 360 hours)

1,061

This document is a draft for review purposes only and does not constitute Agency policy.

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BODY BURDEN (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

12.5

6.62

159

7.04 (@ 343 hours)

6.88

50

26.4

635

28.1 (@ 343 hours)

27.3

200

105

2,528

112 (@343 hours)

108

800

420

10,092

449 (@ 343 hours)

430

FETUS (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

12.5

2.25

54.0

3.14 (@ 360 hours)

3.14

50

7.43

179

10.1 (@ 360 hours)

10.1

200

22.8

548

30.1 (@ 360 hours)

30.1

800

68.1

1,638

87.0 (@ 360 hours)

87.0

BOUND LIVER (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

12.5

3.24

77.9

5.12 (@338 hours)

2.32

50

9.66

232

16.0 (@ 338 hours)

7.12

200

24.8

597

40.7 (@ 337 hours)

19.0

800

51.9

1,248

75.0 (@ 337 hours)

42.7

1

2

3	C.3.2.11. Ohsako et al. (2001)

Type:

Rat

Dose:

12.5, 50, 200, and 800 ng/kg-day

Strain:

Holtzmann

Route:

Oral exposure on GDI5

Body weight

10 weeks (200g)

Regime:

Single dose

Sex:

Female

Simulation time

384 hours

4

This document is a draft for review purposes only and does not constitute Agency policy.

C-177 DRAFT—DO NOT CITE OR QUOTE


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WHOLE BLOOD CONCENTRATIONS (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

12.5

1.04

25.0

2.48 (@ 360 hours)

0.649

50

3.47

83.6

9.93 (@ 360 hours)

2.07

200

11.4

273

39.9 (@ 360 hours)

6.26

800

38.4

925

161 (@ 360 hours)

18.9

LIVER CONCENTRATIONS (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

12.5

74.3

1,788

86.5 (@ 365 hours)

64.2

50

338

8,126

379 (@ 367 hours)

314

200

1,497

36,006

1,655 (@ 368 hours)

1,461

800

6,402

153,960

7,025 (@ 369 hours)

6,443

FAT CONCENTRATIONS (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

12.5

19.0

457

28.6 (@ 384 hours)

28.6

50

65.3

1,569

94.7 (@ 384 hours)

94.7

200

221

5,321

307 (@ 384 hours)

307

800

777

18,671

1,029 (@ 384 hours)

1,029

BODY BURDEN (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

12.5

6.63

159

7.05 (@ 367 hours)

6.89

50

26.4

635

28.2 (@ 367 hours)

27.3

200

105

2,529

112 (@ 367 hours)

108

800

420

10,093

449 (@ 367 hours)

430

FETUS (ng/kg) and AUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

12.5

1.65

39.5

2.33 (@ 384 hours)

2.33

This document is a draft for review purposes only and does not constitute Agency policy.

C-178 DRAFT—DO NOT CITE OR QUOTE


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50

5.44

131

7.48 (@ 384 hours)

7.48

200

16.7

401

22.3 (@ 384 hours)

22.3

800

49.9

1,200

64.6 (@ 384 hours)

64.6

BOUND LIVER (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

12.5

3.25

78.3

5.13 (@362 hours)

2.34

50

9.69

233

16.0 (@ 362 hours)

7.16

200

24.9

598

40.7 (@ 361 hours)

19.1

800

51.9

1,249

75.0 (@ 361 hours)

42.8

C.3.2.12. Schantz et al. (1996) and Amin et al. (2000)

Type:

Rat

Dose:

25 and 100 ng/kg-day

Strain:

Sprague Dawley

Route:

Oral exposure

Body weight:

BW not specified
(BW set to 25 Og)

Regime:

Daily doses from GD 10-16

Sex:

Female

Simulation time:

384 hours; time averages are calculated
from the beginning of the dosing

4

WHOLE BLOOD CONCENTRATIONS (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

25

3.38

487

8.63 (@ 360 hours)

4.03

100

10.6

1,522

31.1 (@360 hours)

12.3

LIVER CONCENTRATIONS (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

25

512

73,686

871 (@ 365 hours)

778

100

2,374

341,960

4,012 (@366 hours)

3,665

FAT CONCENTRATIONS (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

25

169

24,323

306 (@ 384 hours)

306

This document is a draft for review purposes only and does not constitute Agency policy.

C-179 DRAFT—DO NOT CITE OR QUOTE


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100

532

76,675

950 (@ 384 hours)

950

BODY BURDEN (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

25

45.1

6,490

76.6 (@ 365 hours)

74.3

100

111

25,438

298 (@ 365 hours)

287

FETUS (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

25

25.2

3,627

30.4 (@ 343 hours)

27.3

100

74.1

10,672

88.1 (@342 hours)

77.9

BOUND LIVER (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

25

9.99

1,439

14.4 (@ 364 hours)

12.8

100

25.2

3,632

34.2 (@ 364 hours)

31.6

1

2

3	C.3.2.13. Seoetal. (1995)

Type:

Rat

Dose:

25 and 100 ng/kg-day

Strain:

Sprague Dawley

Route:

Oral exposure

Body weight:

BW not specified
(BW set to 190g)

Regime:

Daily doses from GD 10-16

Sex:

Female

Simulation time:

384 hours; time averages are calculated
from the beginning of the dosing

4

WHOLE BLOOD CONCENTRATIONS (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

25

3.33

479

8.25 (@ 360 hours)

4.00

100

10.4

1,498

29.6 (@ 360 hours)

12.2

This document is a draft for review purposes only and does not constitute Agency policy.

C-l 80 DRAFT—DO NOT CITE OR QUOTE


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LIVER CONCENTRATIONS (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

25

504

72,592

861 (@ 365 hours)

767

100

2,347

337,970

3,978 (@ 365 hours)

3,627

FAT CONCENTRATIONS (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

25

172

24,807

310 (@384 hours)

310

100

542

78,097

962 (@ 384 hours)

962

BODY BURDEN (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

25

45.0

6,486

76.5 (@ 365 hours)

74.2

100

176

25,387

298 (@ 365 hours)

287

FETUS (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

25

24.7

3,551

29.8 (@ 343 hours)

26.8

100

72.6

10,456

86.6 (@ 342 hours)

76.8

BOUND LIVER (ng/kg) andAUC ((ng/kg) • hr)

Dose
(ng/kg-day)
Adjusted dose

Metric

Time-weighted Ave

Area Under the
Curve

Max

Terminal

25

9.90

1,426

14.3 (@ 364 hours)

12.7

100

25.0

3,607

34.1 (@ 364 hours)

31.4

This document is a draft for review purposes only and does not constitute Agency policy.

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1	Table C-l. Model input parameters potentially addressed by selected

2	articles

3

Articles

Model input parameters potentially addressed

Absorption

Desorption

Distribution

Elimination

Kinetics

Induction CYP1A1

Interspecies
differences

Age Differences

Aryl hydrocarbon
receptor (AhR)

Mode of action

Partition
coefficient

Aylward et al., 2004

•

•

•

•

•













Aylward et al., 2005a, b

•

•

•

•

•













Aylward et al., 2009







•















Bohonowych and Denison, 2007











•

•



•





Boverhof et al., 2005











•

•









Connor and Aylward, 2006













•

•

•





Heinzl et al., 2007





•











•





Irigaray et al., 2005





•







•









Kerger et al., 2006





•



•





•







Kerger et al., 2007















•







Kim et al., 2003





•

















Korenaga et al., 2007











•

•









Korkalainen et al., 2004













•

•







Kransler et al., 2007













•

•







Maruyama et al., 2002

•



•

•















Maruyama et al., 2003

•



•

•















Maruyama and Aoki, 2006

•



•

•















Millbrath et al., 2009





•

•

•



•









Moser and McLachlan, 2002



•



•















Mullerova and Kopecky, 2007





•

















Nadal et al., 2009







•

•













Nohara et al., 2006













•



•





Olsman et al., 2007

















•





Saghir et al., 2005





•

•

•













Schecter et al., 2003







•







•







Staskal et al., 2005











•





•





Toyoshiba et al., 2004





•





•





•





Wilkes et al., 2008











•











4	Partition coefficient estimates and CYP parameter value estimates were derived from Wang et al. (1997, 2000) and

5	Santostefano etal. (1998).

This document is a draft for review purposes only and does not constitute Agency policy.

C-182 DRAFT—DO NOT CITE OR QUOTE


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1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

C.4. RESPONSE SURFACE TABLES

In order to calculate human equivalent doses, the human model must be run with a daily
intake which gives average blood concentrations which match the average concentrations in the
rodent models. However, such calculation can require numerous human model runs with
repeated intake adjustments in order to reach the target blood concentrations. To facilitate this
process, a response surface was created for the human model. In the response surface, numerous
intakes were run and the blood, fat, and body burden average concentrations were recorded.
These tables can then be used to estimate the intake which would give a target blood
concentration. The two closest intakes are found and the intake is estimated by linearly
interpolating between the two doses. Then, this intake is run through the human model to
confirm that the average blood concentration is within a specified tolerance of the target blood
concentration.

For the current analysis, three different response surfaces were created: non-gestational
lifetime to be used with long-term animal bioassays, nongestational five year average runs to be
used with shorter term animal bioassays, and gestationsl to be used with gestational animal
bioassays. All three response sufraces are shown in the following tables.

This document is a draft for review purposes only and does not constitute Agency policy.

C-l 83 DRAFT—DO NOT CITE OR QUOTE


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C.4.1. Nongestational Lifetime

O



Nongestational Lifetime

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden

(ng/kg)

Blood
(ng/kg)

1.00E-09

2.39E-05

8.58E-06

2.52E-07

1.33E-09

3.18E-05

1.14E-05

3.35E-07

1.67E-09

3.98E-05

1.43E-05

4.19E-07

2.00E-09

4.77E-05

1.72E-05

5.03E-07

2.33E-09

5.57E-05

2.00E-05

5.87E-07

2.67E-09

6.36E-05

2.29E-05

6.70E-07

3.00E-09

7.16E-05

2.57E-05

7.54E-07

3.33E-09

7.95E-05

2.86E-05

8.38E-07

3.67E-09

8.74E-05

3.14E-05

9.22E-07

4.00E-09

9.54E-05

3.43E-05

1.01E-06

4.33E-09

1.03E-04

3.72E-05

1.09E-06

4.67E-09

1.11E-04

4.00E-05

1.17E-06

5.00E-09

1.19E-04

4.29E-05

1.26E-06

5.33E-09

1.27E-04

4.57E-05

1.34E-06

5.67E-09

1.35E-04

4.86E-05

1.42E-06

6.00E-09

1.43E-04

5.14E-05

1.51E-06

6.33E-09

1.51E-04

5.43E-05

1.59E-06

6.67E-09

1.59E-04

5.71E-05

1.68E-06

7.00E-09

1.67E-04

6.00E-05

1.76E-06

7.33E-09

1.75E-04

6.29E-05

1.84E-06

7.67E-09

1.83E-04

6.57E-05

1.93E-06

8.00E-09

1.91E-04

6.86E-05

2.01E-06

8.33E-09

1.99E-04

7.14E-05

2.09E-06

8.67E-09

2.07E-04

7.43E-05

2.18E-06

9.00E-09

2.14E-04

7.71E-05

2.26E-06

9.33E-09

2.22E-04

8.00E-05

2.34E-06

9.67E-09

2.30E-04

8.28E-05

2.43E-06

1.00E-08

2.38E-04

8.57E-05

2.51E-06

Nongestational Lifetime

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden

(ng/kg)

Blood
(ng/kg)

1.33E-08

3.17E-04

1.14E-04

3.34E-06

1.67E-08

3.96E-04

1.43E-04

4.18E-06

2.00E-08

4.75E-04

1.71E-04

5.01E-06

2.33E-08

5.54E-04

1.99E-04

5.84E-06

2.67E-08

6.33E-04

2.28E-04

6.67E-06

3.00E-08

7.12E-04

2.56E-04

7.50E-06

3.33E-08

7.91E-04

2.85E-04

8.34E-06

3.67E-08

8.70E-04

3.13E-04

9.17E-06

4.00E-08

9.49E-04

3.41E-04

1.00E-05

4.33E-08

1.03E-03

3.70E-04

1.08E-05

4.67E-08

1.11E-03

3.98E-04

1.17E-05

5.00E-08

1.19E-03

4.27E-04

1.25E-05

5.33E-08

1.26E-03

4.55E-04

1.33E-05

5.67E-08

1.34E-03

4.83E-04

1.41E-05

6.00E-08

1.42E-03

5.12E-04

1.50E-05

6.33E-08

1.50E-03

5.40E-04

1.58E-05

6.67E-08

1.58E-03

5.68E-04

1.66E-05

7.00E-08

1.66E-03

5.96E-04

1.75E-05

7.33E-08

1.73E-03

6.25E-04

1.83E-05

7.67E-08

1.81E-03

6.53E-04

1.91E-05

8.00E-08

1.89E-03

6.81E-04

1.99E-05

8.33E-08

1.97E-03

7.10E-04

2.08E-05

8.67E-08

2.05E-03

7.38E-04

2.16E-05

9.00E-08

2.13E-03

7.66E-04

2.24E-05

9.33E-08

2.21E-03

7.94E-04

2.32E-05

9.67E-08

2.28E-03

8.23E-04

2.41E-05

1.00E-07

2.36E-03

8.51E-04

2.49E-05

1.33E-07

3.14E-03

1.13E-03

3.31E-05

1.67E-07

3.92E-03

1.41E-03

4.13E-05

Nongestational Lifetime

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden

(ng/kg)

Blood
(ng/kg)

2.00E-07

4.70E-03

1.70E-03

4.96E-05

2.33E-07

5.48E-03

1.98E-03

5.78E-05

2.67E-07

6.26E-03

2.26E-03

6.60E-05

3.00E-07

7.04E-03

2.54E-03

7.42E-05

3.33E-07

7.82E-03

2.82E-03

8.24E-05

3.67E-07

8.60E-03

3.10E-03

9.06E-05

4.00E-07

9.38E-03

3.38E-03

9.89E-05

4.33E-07

1.02E-02

3.66E-03

1.07E-04

4.67E-07

1.09E-02

3.95E-03

1.15E-04

5.00E-07

1.17E-02

4.23E-03

1.24E-04

5.33E-07

1.25E-02

4.50E-03

1.31E-04

5.66E-07

1.32E-02

4.78E-03

1.39E-04

5.99E-07

1.40E-02

5.05E-03

1.47E-04

6.33E-07

1.47E-02

5.32E-03

1.55E-04

6.66E-07

1.55E-02

5.60E-03

1.63E-04

6.99E-07

1.63E-02

5.87E-03

1.71E-04

7.32E-07

1.70E-02

6.15E-03

1.79E-04

7.65E-07

1.78E-02

6.42E-03

1.87E-04

7.98E-07

1.85E-02

6.69E-03

1.95E-04

8.32E-07

1.93E-02

6.97E-03

2.03E-04

8.65E-07

2.00E-02

7.24E-03

2.11E-04

8.98E-07

2.08E-02

7.52E-03

2.19E-04

9.31E-07

2.16E-02

7.79E-03

2.27E-04

9.64E-07

2.23E-02

8.07E-03

2.35E-04

9.97E-07

2.31E-02

8.34E-03

2.43E-04

1.01E-06

2.34E-02

8.46E-03

2.47E-04

1.03E-06

2.37E-02

8.59E-03

2.50E-04

1.04E-06

2.41E-02

8.71E-03

2.54E-04

1.06E-06

2.44E-02

8.84E-03

2.58E-04


-------
o



Nongestational Lifetime

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden

(ng/kg)

Blood
(ng/kg)

1.07E-06

2.48E-02

8.97E-03

2.61E-04

1.09E-06

2.52E-02

9.10E-03

2.65E-04

1.11E-06

2.55E-02

9.23E-03

2.69E-04

1.12E-06

2.59E-02

9.37E-03

2.73E-04

1.14E-06

2.63E-02

9.51E-03

2.77E-04

1.16E-06

2.67E-02

9.65E-03

2.81E-04

1.17E-06

2.70E-02

9.79E-03

2.85E-04

1.19E-06

2.74E-02

9.93E-03

2.89E-04

1.21E-06

2.78E-02

1.01E-02

2.93E-04

1.23E-06

2.82E-02

1.02E-02

2.98E-04

1.24E-06

2.87E-02

1.04E-02

3.02E-04

1.26E-06

2.91E-02

1.05E-02

3.06E-04

1.28E-06

2.95E-02

1.07E-02

3.11E-04

1.30E-06

2.99E-02

1.08E-02

3.15E-04

1.32E-06

3.04E-02

1.10E-02

3.20E-04

1.34E-06

3.08E-02

1.12E-02

3.25E-04

1.36E-06

3.13E-02

1.13E-02

3.29E-04

1.38E-06

3.17E-02

1.15E-02

3.34E-04

1.40E-06

3.22E-02

1.16E-02

3.39E-04

1.42E-06

3.26E-02

1.18E-02

3.44E-04

1.44E-06

3.31E-02

1.20E-02

3.49E-04

1.46E-06

3.36E-02

1.22E-02

3.54E-04

1.49E-06

3.41E-02

1.24E-02

3.59E-04

1.53E-06

3.51E-02

1.27E-02

3.70E-04

1.58E-06

3.61E-02

1.31E-02

3.81E-04

1.62E-06

3.72E-02

1.35E-02

3.92E-04

1.67E-06

3.83E-02

1.39E-02

4.03E-04

1.72E-06

3.94E-02

1.43E-02

4.15E-04

1.77E-06

4.05E-02

1.47E-02

4.27E-04

Nongestational Lifetime

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden

(ng/kg)

Blood
(ng/kg)

1.83E-06

4.17E-02

1.51E-02

4.39E-04

1.88E-06

4.29E-02

1.56E-02

4.52E-04

1.94E-06

4.41E-02

1.60E-02

4.65E-04

2.00E-06

4.54E-02

1.65E-02

4.79E-04

2.06E-06

4.67E-02

1.70E-02

4.93E-04

2.12E-06

4.81E-02

1.75E-02

5.07E-04

2.18E-06

4.95E-02

1.80E-02

5.22E-04

2.25E-06

5.09E-02

1.85E-02

5.37E-04

2.32E-06

5.24E-02

1.90E-02

5.52E-04

2.39E-06

5.39E-02

1.96E-02

5.68E-04

2.46E-06

5.55E-02

2.02E-02

5.85E-04

2.53E-06

5.71E-02

2.07E-02

6.02E-04

2.61E-06

5.87E-02

2.13E-02

6.19E-04

2.68E-06

6.04E-02

2.20E-02

6.37E-04

2.76E-06

6.22E-02

2.26E-02

6.55E-04

2.85E-06

6.40E-02

2.33E-02

6.74E-04

2.93E-06

6.58E-02

2.39E-02

6.93E-04

3.02E-06

6.77E-02

2.46E-02

7.13E-04

3.11E-06

6.96E-02

2.53E-02

7.34E-04

3.21E-06

7.16E-02

2.61E-02

7.55E-04

3.30E-06

7.37E-02

2.68E-02

7.76E-04

3.40E-06

7.58E-02

2.76E-02

7.99E-04

3.50E-06

7.80E-02

2.84E-02

8.22E-04

3.61E-06

8.02E-02

2.92E-02

8.45E-04

3.72E-06

8.25E-02

3.01E-02

8.69E-04

3.83E-06

8.48E-02

3.09E-02

8.94E-04

3.94E-06

8.73E-02

3.18E-02

9.20E-04

4.06E-06

8.98E-02

3.27E-02

9.46E-04

4.18E-06

9.23E-02

3.37E-02

9.73E-04

Nongestational Lifetime

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden

(ng/kg)

Blood
(ng/kg)

4.31E-06

9.49E-02

3.47E-02

1.00E-03

4.44E-06

9.76E-02

3.57E-02

1.03E-03

4.57E-06

1.00E-01

3.67E-02

1.06E-03

4.71E-06

1.03E-01

3.77E-02

1.09E-03

4.85E-06

1.06E-01

3.88E-02

1.12E-03

4.99E-06

1.09E-01

3.99E-02

1.15E-03

5.14E-06

1.12E-01

4.11E-02

1.18E-03

5.30E-06

1.15E-01

4.22E-02

1.22E-03

5.46E-06

1.19E-01

4.34E-02

1.25E-03

5.62E-06

1.22E-01

4.47E-02

1.29E-03

5.79E-06

1.25E-01

4.59E-02

1.32E-03

5.96E-06

1.29E-01

4.73E-02

1.36E-03

6.14E-06

1.33E-01

4.86E-02

1.40E-03

6.33E-06

1.36E-01

5.00E-02

1.44E-03

6.52E-06

1.40E-01

5.14E-02

1.48E-03

6.71E-06

1.44E-01

5.28E-02

1.52E-03

6.91E-06

1.48E-01

5.43E-02

1.56E-03

7.12E-06

1.52E-01

5.58E-02

1.60E-03

7.33E-06

1.56E-01

5.74E-02

1.65E-03

7.55E-06

1.61E-01

5.90E-02

1.69E-03

7.78E-06

1.65E-01

6.06E-02

1.74E-03

8.01E-06

1.70E-01

6.23E-02

1.79E-03

8.25E-06

1.74E-01

6.41E-02

1.84E-03

8.50E-06

1.79E-01

6.59E-02

1.89E-03

8.76E-06

1.84E-01

6.77E-02

1.94E-03

9.02E-06

1.89E-01

6.96E-02

1.99E-03

9.29E-06

1.94E-01

7.15E-02

2.05E-03

9.57E-06

2.00E-01

7.35E-02

2.10E-03

9.86E-06

2.05E-01

7.56E-02

2.16E-03


-------
o



Nongestational Lifetime

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden

(ng/kg)

Blood
(ng/kg)

1.02E-05

2.11E-01

7.77E-02

2.22E-03

1.05E-05

2.16E-01

7.98E-02

2.28E-03

1.08E-05

2.22E-01

8.20E-02

2.34E-03

1.11E-05

2.28E-01

8.43E-02

2.41E-03

1.14E-05

2.34E-01

8.67E-02

2.47E-03

1.18E-05

2.41E-01

8.91E-02

2.54E-03

1.21E-05

2.47E-01

9.15E-02

2.61E-03

1.25E-05

2.54E-01

9.41E-02

2.68E-03

1.29E-05

2.61E-01

9.67E-02

2.75E-03

1.32E-05

2.68E-01

9.93E-02

2.82E-03

1.36E-05

2.75E-01

1.02E-01

2.90E-03

1.41E-05

2.83E-01

1.05E-01

2.98E-03

1.45E-05

2.90E-01

1.08E-01

3.06E-03

1.49E-05

2.98E-01

1.11E-01

3.14E-03

1.54E-05

3.06E-01

1.14E-01

3.22E-03

1.58E-05

3.14E-01

1.17E-01

3.31E-03

1.63E-05

3.23E-01

1.20E-01

3.40E-03

1.68E-05

3.31E-01

1.23E-01

3.49E-03

1.73E-05

3.40E-01

1.27E-01

3.58E-03

1.78E-05

3.49E-01

1.30E-01

3.68E-03

1.83E-05

3.58E-01

1.34E-01

3.78E-03

1.89E-05

3.68E-01

1.37E-01

3.88E-03

1.95E-05

3.78E-01

1.41E-01

3.98E-03

2.00E-05

3.88E-01

1.45E-01

4.09E-03

2.06E-05

3.98E-01

1.49E-01

4.20E-03

2.13E-05

4.09E-01

1.53E-01

4.31E-03

2.19E-05

4.20E-01

1.57E-01

4.42E-03

2.25E-05

4.31E-01

1.61E-01

4.54E-03

2.32E-05

4.42E-01

1.66E-01

4.66E-03

Nongestational Lifetime

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden

(ng/kg)

Blood
(ng/kg)

2.39E-05

4.54E-01

1.70E-01

4.78E-03

2.46E-05

4.66E-01

1.75E-01

4.91E-03

2.54E-05

4.78E-01

1.80E-01

5.04E-03

2.61E-05

4.91E-01

1.84E-01

5.17E-03

2.69E-05

5.04E-01

1.89E-01

5.31E-03

2.77E-05

5.17E-01

1.95E-01

5.45E-03

2.86E-05

5.31E-01

2.00E-01

5.59E-03

2.94E-05

5.45E-01

2.05E-01

5.74E-03

3.03E-05

5.59E-01

2.11E-01

5.89E-03

3.12E-05

5.74E-01

2.16E-01

6.05E-03

3.21E-05

5.89E-01

2.22E-01

6.20E-03

3.31E-05

6.06E-01

2.29E-01

6.38E-03

3.41E-05

6.22E-01

2.35E-01

6.54E-03

3.51E-05

6.38E-01

2.41E-01

6.72E-03

3.62E-05

6.54E-01

2.48E-01

6.89E-03

3.73E-05

6.71E-01

2.54E-01

7.08E-03

3.84E-05

6.89E-01

2.61E-01

7.25E-03

3.95E-05

7.07E-01

2.68E-01

7.45E-03

4.07E-05

7.23E-01

2.74E-01

7.62E-03

4.19E-05

7.41E-01

2.82E-01

7.82E-03

4.32E-05

7.60E-01

2.89E-01

8.01E-03

4.45E-05

7.80E-01

2.97E-01

8.22E-03

4.58E-05

8.00E-01

3.05E-01

8.43E-03

4.72E-05

8.20E-01

3.13E-01

8.64E-03

4.86E-05

8.41E-01

3.21E-01

8.86E-03

5.01E-05

8.63E-01

3.29E-01

9.09E-03

5.16E-05

8.84E-01

3.38E-01

9.32E-03

5.31E-05

9.07E-01

3.47E-01

9.55E-03

5.47E-05

9.30E-01

3.56E-01

9.80E-03

Nongestational Lifetime

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden

(ng/kg)

Blood
(ng/kg)

5.64E-05

9.53E-01

3.65E-01

1.00E-02

5.81E-05

9.77E-01

3.75E-01

1.03E-02

5.98E-05

1.00E+00

3.84E-01

1.06E-02

6.16E-05

1.03E+00

3.95E-01

1.08E-02

6.34E-05

1.05E+00

4.05E-01

1.11E-02

6.54E-05

1.08E+00

4.15E-01

1.14E-02

6.73E-05

1.11E+00

4.26E-01

1.17E-02

6.93E-05

1.13E+00

4.37E-01

1.19E-02

7.14E-05

1.16E+00

4.48E-01

1.22E-02

7.36E-05

1.19E+00

4.58E-01

1.25E-02

7.58E-05

1.22E+00

4.70E-01

1.28E-02

7.80E-05

1.25E+00

4.82E-01

1.31E-02

8.04E-05

1.28E+00

4.94E-01

1.34E-02

8.28E-05

1.31E+00

5.07E-01

1.38E-02

8.53E-05

1.34E+00

5.20E-01

1.41E-02

8.78E-05

1.37E+00

5.33E-01

1.45E-02

9.05E-05

1.41E+00

5.47E-01

1.48E-02

9.32E-05

1.44E+00

5.61E-01

1.52E-02

9.60E-05

1.48E+00

5.75E-01

1.55E-02

9.89E-05

1.51E+00

5.90E-01

1.59E-02

1.02E-04

1.55E+00

6.05E-01

1.63E-02

1.05E-04

1.59E+00

6.20E-01

1.67E-02

1.08E-04

1.62E+00

6.36E-01

1.71E-02

1.11E-04

1.66E+00

6.52E-01

1.75E-02

1.15E-04

1.70E+00

6.69E-01

1.79E-02

1.18E-04

1.75E+00

6.86E-01

1.84E-02

1.22E-04

1.79E+00

7.03E-01

1.88E-02

1.25E-04

1.83E+00

7.20E-01

1.93E-02

1.29E-04

1.87E+00

7.39E-01

1.97E-02


-------
o



Nongestational Lifetime

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden

(ng/kg)

Blood
(ng/kg)

1.33E-04

1.92E+00

7.57E-01

2.02E-02

1.37E-04

1.97E+00

7.76E-01

2.07E-02

1.41E-04

2.01E+00

7.96E-01

2.12E-02

1.45E-04

2.08E+00

8.23E-01

2.19E-02

1.50E-04

2.11E+00

8.36E-01

2.22E-02

1.54E-04

2.16E+00

8.57E-01

2.27E-02

1.59E-04

2.23E+00

8.88E-01

2.35E-02

1.63E-04

2.29E+00

9.10E-01

2.41E-02

1.68E-04

2.32E+00

9.24E-01

2.44E-02

1.73E-04

2.37E+00

9.47E-01

2.50E-02

1.79E-04

2.43E+00

9.71E-01

2.56E-02

1.84E-04

2.49E+00

9.96E-01

2.62E-02

1.89E-04

2.55E+00

1.02E+00

2.68E-02

1.95E-04

2.61E+00

1.05E+00

2.75E-02

2.01E-04

2.67E+00

1.07E+00

2.81E-02

2.07E-04

2.76E+00

1.11E+00

2.91E-02

2.13E-04

2.80E+00

1.13E+00

2.94E-02

2.20E-04

2.86E+00

1.16E+00

3.01E-02

2.26E-04

2.95E+00

1.19E+00

3.11E-02

2.33E-04

3.02E+00

1.22E+00

3.18E-02

2.40E-04

3.09E+00

1.25E+00

3.26E-02

2.47E-04

3.14E+00

1.27E+00

3.30E-02

2.55E-04

3.21E+00

1.31E+00

3.38E-02

2.62E-04

3.29E+00

1.34E+00

3.46E-02

2.70E-04

3.39E+00

1.38E+00

3.57E-02

2.78E-04

3.47E+00

1.42E+00

3.65E-02

2.86E-04

3.55E+00

1.45E+00

3.74E-02

2.95E-04

3.61E+00

1.48E+00

3.80E-02

3.04E-04

3.72E+00

1.53E+00

3.91E-02

Nongestational Lifetime

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden

(ng/kg)

Blood
(ng/kg)

3.13E-04

3.80E+00

1.56E+00

4.00E-02

3.22E-04

3.89E+00

1.60E+00

4.10E-02

3.32E-04

3.98E+00

1.64E+00

4.19E-02

3.42E-04

4.07E+00

1.68E+00

4.29E-02

3.52E-04

4.16E+00

1.72E+00

4.38E-02

3.63E-04

4.26E+00

1.77E+00

4.48E-02

3.74E-04

4.35E+00

1.81E+00

4.58E-02

3.85E-04

4.45E+00

1.85E+00

4.69E-02

3.97E-04

4.55E+00

1.90E+00

4.80E-02

4.08E-04

4.66E+00

1.94E+00

4.90E-02

4.21E-04

4.76E+00

1.99E+00

5.01E-02

4.33E-04

4.87E+00

2.04E+00

5.13E-02

4.46E-04

4.98E+00

2.09E+00

5.24E-02

4.60E-04

5.09E+00

2.14E+00

5.36E-02

4.74E-04

5.20E+00

2.19E+00

5.48E-02

4.88E-04

5.32E+00

2.24E+00

5.60E-02

5.02E-04

5.43E+00

2.30E+00

5.72E-02

5.17E-04

5.55E+00

2.35E+00

5.85E-02

5.33E-04

5.68E+00

2.41E+00

5.98E-02

5.49E-04

5.80E+00

2.47E+00

6.11E-02

5.65E-04

5.93E+00

2.53E+00

6.24E-02

5.82E-04

6.06E+00

2.59E+00

6.38E-02

6.00E-04

6.19E+00

2.65E+00

6.52E-02

6.18E-04

6.33E+00

2.71E+00

6.66E-02

6.36E-04

6.46E+00

2.78E+00

6.80E-02

6.55E-04

6.60E+00

2.84E+00

6.95E-02

6.75E-04

6.75E+00

2.91E+00

7.10E-02

6.95E-04

6.89E+00

2.98E+00

7.26E-02

7.16E-04

7.04E+00

3.05E+00

7.41E-02

Nongestational Lifetime

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden

(ng/kg)

Blood
(ng/kg)

7.38E-04

7.20E+00

3.13E+00

7.58E-02

7.60E-04

7.35E+00

3.20E+00

7.74E-02

7.83E-04

7.51E+00

3.28E+00

7.91E-02

8.06E-04

7.61E+00

3.33E+00

8.01E-02

8.30E-04

7.77E+00

3.41E+00

8.19E-02

8.55E-04

7.94E+00

3.49E+00

8.36E-02

8.81E-04

8.11E+00

3.58E+00

8.54E-02

9.07E-04

8.30E+00

3.67E+00

8.74E-02

9.21E-04

8.37E+00

3.70E+00

8.81E-02

9.35E-04

8.46E+00

3.75E+00

8.90E-02

9.49E-04

9.14E+00

4.12E+00

9.62E-02

9.63E-04

9.54E+00

4.33E+00

1.00E-01

9.69E-04

9.70E+00

4.42E+00

1.02E-01

9.77E-04

9.87E+00

4.51E+00

1.04E-01

1.17E-03

1.01E+01

4.58E+00

1.07E-01

1.18E-03

1.02E+01

4.63E+00

1.08E-01

1.20E-03

1.03E+01

4.68E+00

1.09E-01

1.22E-03

1.04E+01

4.73E+00

1.10E-01

1.24E-03

1.05E+01

4.75E+00

1.10E-01

1.26E-03

1.06E+01

4.81E+00

1.11E-01

1.27E-03

1.07E+01

4.86E+00

1.12E-01

1.29E-03

1.08E+01

4.92E+00

1.14E-01

1.31E-03

1.09E+01

4.97E+00

1.15E-01

1.33E-03

1.10E+01

5.03E+00

1.16E-01

1.35E-03

1.11E+01

5.08E+00

1.17E-01

1.37E-03

1.12E+01

5.13E+00

1.18E-01

1.39E-03

1.13E+01

5.18E+00

1.19E-01

1.41E-03

1.14E+01

5.23E+00

1.20E-01

1.43E-03

1.15E+01

5.29E+00

1.21E-01


-------
o



Nongestational Lifetime

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden

(ng/kg)

Blood
(ng/kg)

1.46E-03

1.16E+01

5.34E+00

1.22E-01

1.48E-03

1.17E+01

5.40E+00

1.23E-01

1.50E-03

1.18E+01

5.47E+00

1.25E-01

1.52E-03

1.20E+01

5.54E+00

1.26E-01

1.54E-03

1.21E+01

5.61E+00

1.28E-01

1.57E-03

1.22E+01

5.66E+00

1.29E-01

1.59E-03

1.24E+01

5.73E+00

1.30E-01

1.61E-03

1.25E+01

5.82E+00

1.32E-01

1.64E-03

1.27E+01

5.88E+00

1.33E-01

1.66E-03

1.28E+01

5.95E+00

1.35E-01

1.69E-03

1.29E+01

6.02E+00

1.36E-01

1.71E-03

1.31E+01

6.10E+00

1.37E-01

1.74E-03

1.32E+01

6.17E+00

1.39E-01

1.76E-03

1.33E+01

6.24E+00

1.40E-01

1.79E-03

1.35E+01

6.32E+00

1.42E-01

1.82E-03

1.36E+01

6.39E+00

1.43E-01

1.84E-03

1.38E+01

6.46E+00

1.45E-01

1.87E-03

1.40E+01

6.59E+00

1.47E-01

1.90E-03

1.46E+01

6.95E+00

1.54E-01

2.02E-03

1.50E+01

7.16E+00

1.58E-01

2.08E-03

1.51E+01

7.23E+00

1.59E-01

2.14E-03

1.53E+01

7.31E+00

1.61E-01

2.20E-03

1.56E+01

7.47E+00

1.64E-01

2.27E-03

1.59E+01

7.65E+00

1.68E-01

2.34E-03

1.62E+01

7.82E+00

1.71E-01

2.41E-03

1.66E+01

8.00E+00

1.74E-01

2.48E-03

1.69E+01

8.19E+00

1.78E-01

2.55E-03

1.72E+01

8.38E+00

1.81E-01

2.63E-03

1.76E+01

8.57E+00

1.85E-01

Nongestational Lifetime

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden

(ng/kg)

Blood
(ng/kg)

2.71E-03

1.79E+01

8.77E+00

1.89E-01

2.79E-03

1.83E+01

8.98E+00

1.92E-01

2.87E-03

1.87E+01

9.19E+00

1.96E-01

2.96E-03

1.90E+01

9.41E+00

2.00E-01

3.05E-03

1.94E+01

9.62E+00

2.04E-01

3.14E-03

1.98E+01

9.85E+00

2.08E-01

3.23E-03

2.02E+01

1.01E+01

2.13E-01

3.33E-03

2.06E+01

1.03E+01

2.17E-01

3.43E-03

2.10E+01

1.06E+01

2.21E-01

3.53E-03

2.14E+01

1.08E+01

2.25E-01

3.64E-03

2.18E+01

1.11E+01

2.30E-01

3.75E-03

2.25E+01

1.15E+01

2.37E-01

3.98E-03

2.29E+01

1.17E+01

2.41E-01

4.10E-03

2.32E+01

1.18E+01

2.44E-01

4.22E-03

2.35E+01

1.20E+01

2.48E-01

4.35E-03

2.40E+01

1.23E+01

2.52E-01

4.48E-03

2.44E+01

1.26E+01

2.57E-01

4.61E-03

2.49E+01

1.29E+01

2.63E-01

4.75E-03

2.55E+01

1.33E+01

2.69E-01

4.89E-03

2.61E+01

1.36E+01

2.74E-01

5.04E-03

2.69E+01

1.41E+01

2.83E-01

5.19E-03

2.75E+01

1.45E+01

2.90E-01

5.35E-03

2.83E+01

1.51E+01

2.98E-01

5.51E-03

2.91E+01

1.55E+01

3.06E-01

5.67E-03

2.97E+01

1.59E+01

3.13E-01

5.84E-03

3.03E+01

1.63E+01

3.19E-01

5.93E-03

3.04E+01

1.64E+01

3.20E-01

6.02E-03

3.07E+01

1.65E+01

3.23E-01

6.20E-03

3.15E+01

1.71E+01

3.31E-01

Nongestational Lifetime

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden

(ng/kg)

Blood
(ng/kg)

6.38E-03

3.22E+01

1.76E+01

3.39E-01

6.57E-03

3.28E+01

1.80E+01

3.46E-01

6.77E-03

3.35E+01

1.84E+01

3.53E-01

6.98E-03

3.42E+01

1.89E+01

3.60E-01

7.18E-03

3.50E+01

1.94E+01

3.68E-01

7.40E-03

3.57E+01

1.99E+01

3.76E-01

7.51E-03

3.61E+01

2.02E+01

3.80E-01

7.62E-03

3.63E+01

2.03E+01

3.82E-01

7.85E-03

3.67E+01

2.06E+01

3.87E-01

8.09E-03

3.70E+01

2.07E+01

3.89E-01

8.33E-03

3.75E+01

2.10E+01

3.94E-01

8.58E-03

3.89E+01

2.21E+01

4.09E-01

8.71E-03

3.93E+01

2.24E+01

4.14E-01

8.84E-03

3.97E+01

2.26E+01

4.18E-01

9.10E-03

4.04E+01

2.31E+01

4.25E-01

9.37E-03

4.13E+01

2.38E+01

4.35E-01

9.66E-03

4.21E+01

2.43E+01

4.44E-01

9.94E-03

4.31E+01

2.50E+01

4.53E-01

1.02E-02

4.39E+01

2.56E+01

4.62E-01

1.06E-02

4.47E+01

2.62E+01

4.71E-01

1.09E-02

4.56E+01

2.68E+01

4.80E-01

1.12E-02

4.66E+01

2.75E+01

4.90E-01

1.15E-02

4.75E+01

2.82E+01

5.00E-01

1.19E-02

4.82E+01

2.87E+01

5.07E-01

1.22E-02

4.91E+01

2.94E+01

5.17E-01

1.26E-02

5.00E+01

3.00E+01

5.26E-01

1.30E-02

5.12E+01

3.09E+01

5.39E-01

1.34E-02

5.24E+01

3.19E+01

5.52E-01

1.38E-02

5.36E+01

3.28E+01

5.65E-01


-------
o



Nongestational Lifetime

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden

(ng/kg)

Blood
(ng/kg)

1.42E-02

5.48E+01

3.37E+01

5.77E-01

1.46E-02

5.57E+01

3.44E+01

5.87E-01

1.50E-02

5.68E+01

3.52E+01

5.97E-01

1.55E-02

5.78E+01

3.60E+01

6.08E-01

1.60E-02

5.88E+01

3.67E+01

6.19E-01

1.64E-02

5.97E+01

3.75E+01

6.29E-01

1.69E-02

6.10E+01

3.85E+01

6.42E-01

1.74E-02

6.22E+01

3.95E+01

6.55E-01

1.80E-02

6.34E+01

4.04E+01

6.68E-01

1.85E-02

6.47E+01

4.14E+01

6.81E-01

1.91E-02

6.60E+01

4.25E+01

6.94E-01

1.96E-02

6.73E+01

4.35E+01

7.08E-01

2.02E-02

6.86E+01

4.46E+01

7.22E-01

2.08E-02

7.00E+01

4.57E+01

7.36E-01

2.14E-02

7.13E+01

4.69E+01

7.51E-01

2.21E-02

7.28E+01

4.81E+01

7.66E-01

2.28E-02

7.42E+01

4.93E+01

7.81E-01

2.34E-02

7.57E+01

5.05E+01

7.97E-01

2.41E-02

7.71E+01

5.18E+01

8.12E-01

2.49E-02

7.87E+01

5.31E+01

8.28E-01

2.56E-02

8.02E+01

5.44E+01

8.44E-01

2.64E-02

8.18E+01

5.58E+01

8.61E-01

2.72E-02

8.33E+01

5.71E+01

8.77E-01

2.80E-02

8.50E+01

5.86E+01

8.95E-01

2.88E-02

8.67E+01

6.01E+01

9.12E-01

2.97E-02

8.83E+01

6.16E+01

9.30E-01

3.06E-02

9.03E+01

6.34E+01

9.50E-01

3.15E-02

9.21E+01

6.50E+01

9.69E-01

3.24E-02

9.40E+01

6.67E+01

9.89E-01

Nongestational Lifetime

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden

(ng/kg)

Blood
(ng/kg)

3.34E-02

9.57E+01

6.83E+01

1.01E+00

3.44E-02

9.74E+01

6.99E+01

1.03E+00

3.54E-02

9.92E+01

7.15E+01

1.04E+00

3.65E-02

1.01E+02

7.32E+01

1.06E+00

3.76E-02

1.03E+02

7.51E+01

1.08E+00

3.87E-02

1.05E+02

7.69E+01

1.10E+00

3.99E-02

1.07E+02

7.89E+01

1.13E+00

4.11E-02

1.09E+02

8.09E+01

1.15E+00

4.23E-02

1.11E+02

8.30E+01

1.17E+00

4.36E-02

1.14E+02

8.53E+01

1.20E+00

4.49E-02

1.16E+02

8.76E+01

1.22E+00

4.63E-02

1.18E+02

8.99E+01

1.24E+00

4.76E-02

1.21E+02

9.22E+01

1.27E+00

4.91E-02

1.23E+02

9.46E+01

1.29E+00

5.05E-02

1.25E+02

9.70E+01

1.32E+00

5.21E-02

1.28E+02

9.95E+01

1.34E+00

5.36E-02

1.30E+02

1.02E+02

1.37E+00

5.52E-02

1.33E+02

1.05E+02

1.40E+00

5.69E-02

1.35E+02

1.07E+02

1.43E+00

5.86E-02

1.38E+02

1.10E+02

1.45E+00

6.03E-02

1.41E+02

1.13E+02

1.48E+00

6.22E-02

1.43E+02

1.16E+02

1.51E+00

6.40E-02

1.46E+02

1.19E+02

1.54E+00

6.59E-02

1.49E+02

1.22E+02

1.57E+00

6.79E-02

1.52E+02

1.25E+02

1.60E+00

7.00E-02

1.55E+02

1.28E+02

1.63E+00

7.21E-02

1.58E+02

1.31E+02

1.66E+00

7.42E-02

1.61E+02

1.35E+02

1.69E+00

7.64E-02

1.64E+02

1.38E+02

1.73E+00

Nongestational Lifetime

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden

(ng/kg)

Blood
(ng/kg)

7.87E-02

1.67E+02

1.42E+02

1.76E+00

8.11E-02

1.71E+02

1.46E+02

1.80E+00

8.35E-02

1.74E+02

1.50E+02

1.83E+00

8.60E-02

1.78E+02

1.54E+02

1.87E+00

8.86E-02

1.81E+02

1.58E+02

1.90E+00

9.13E-02

1.85E+02

1.62E+02

1.94E+00

9.40E-02

1.88E+02

1.66E+02

1.98E+00

9.68E-02

1.92E+02

1.70E+02

2.02E+00

9.97E-02

1.96E+02

1.75E+02

2.06E+00

1.03E-01

1.99E+02

1.79E+02

2.10E+00

1.06E-01

2.03E+02

1.84E+02

2.14E+00

1.09E-01

2.07E+02

1.89E+02

2.18E+00

1.12E-01

2.11E+02

1.94E+02

2.22E+00

1.16E-01

2.15E+02

1.99E+02

2.27E+00

1.19E-01

2.20E+02

2.04E+02

2.31E+00

1.23E-01

2.24E+02

2.10E+02

2.36E+00

1.26E-01

2.28E+02

2.15E+02

2.40E+00

1.30E-01

2.33E+02

2.21E+02

2.45E+00

1.34E-01

2.38E+02

2.27E+02

2.50E+00

1.38E-01

2.42E+02

2.33E+02

2.55E+00

1.42E-01

2.47E+02

2.39E+02

2.60E+00

1.46E-01

2.52E+02

2.46E+02

2.65E+00

1.51E-01

2.57E+02

2.52E+02

2.70E+00

1.55E-01

2.62E+02

2.59E+02

2.75E+00

1.60E-01

2.67E+02

2.66E+02

2.81E+00

1.65E-01

2.72E+02

2.73E+02

2.86E+00

1.70E-01

2.78E+02

2.80E+02

2.92E+00

1.75E-01

2.83E+02

2.88E+02

2.98E+00

1.80E-01

2.89E+02

2.95E+02

3.04E+00


-------
o



Nongestational Lifetime

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden

(ng/kg)

Blood
(ng/kg)

1.86E-01

2.94E+02

3.03E+02

3.10E+00

1.91E-01

3.00E+02

3.12E+02

3.16E+00

1.97E-01

3.06E+02

3.20E+02

3.22E+00

2.03E-01

3.12E+02

3.28E+02

3.28E+00

2.09E-01

3.18E+02

3.37E+02

3.35E+00

2.15E-01

3.25E+02

3.46E+02

3.42E+00

2.22E-01

3.31E+02

3.56E+02

3.48E+00

2.28E-01

3.38E+02

3.65E+02

3.55E+00

2.35E-01

3.44E+02

3.75E+02

3.62E+00

2.42E-01

3.51E+02

3.86E+02

3.70E+00

2.49E-01

3.58E+02

3.96E+02

3.77E+00

2.57E-01

3.65E+02

4.07E+02

3.85E+00

2.65E-01

3.73E+02

4.18E+02

3.92E+00

2.72E-01

3.80E+02

4.29E+02

4.00E+00

2.81E-01

3.88E+02

4.41E+02

4.08E+00

2.89E-01

3.95E+02

4.53E+02

4.16E+00

2.98E-01

4.03E+02

4.65E+02

4.24E+00

3.07E-01

4.11E+02

4.77E+02

4.33E+00

3.16E-01

4.19E+02

4.90E+02

4.41E+00

3.25E-01

4.28E+02

5.04E+02

4.50E+00

3.35E-01

4.36E+02

5.18E+02

4.59E+00

3.45E-01

4.45E+02

5.32E+02

4.68E+00

3.56E-01

4.54E+02

5.47E+02

4.78E+00

3.66E-01

4.63E+02

5.62E+02

4.87E+00

3.77E-01

4.72E+02

5.77E+02

4.97E+00

3.89E-01

4.82E+02

5.93E+02

5.07E+00

4.00E-01

4.91E+02

6.09E+02

5.17E+00

4.12E-01

5.01E+02

6.26E+02

5.28E+00

4.25E-01

5.11E+02

6.43E+02

5.38E+00

Nongestational Lifetime

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden

(ng/kg)

Blood
(ng/kg)

4.37E-01

5.22E+02

6.61E+02

5.49E+00

4.50E-01

5.32E+02

6.79E+02

5.60E+00

4.64E-01

5.43E+02

6.98E+02

5.71E+00

4.92E-01

5.65E+02

7.37E+02

5.95E+00

5.07E-01

5.76E+02

7.57E+02

6.07E+00

5.22E-01

5.88E+02

7.78E+02

6.19E+00

5.54E-01

6.12E+02

8.22E+02

6.44E+00

5.71E-01

6.25E+02

8.44E+02

6.58E+00

5.88E-01

6.37E+02

8.68E+02

6.71E+00

6.05E-01

6.50E+02

8.92E+02

6.84E+00

6.23E-01

6.64E+02

9.17E+02

6.98E+00

6.61E-01

6.91E+02

9.68E+02

7.27E+00

6.81E-01

7.05E+02

9.95E+02

7.42E+00

7.02E-01

7.20E+02

1.02E+03

7.57E+00

7.23E-01

7.34E+02

1.05E+03

7.73E+00

7.44E-01

7.49E+02

1.08E+03

7.89E+00

7.67E-01

7.65E+02

1.11E+03

8.05E+00

7.90E-01

7.80E+02

1.14E+03

8.21E+00

8.13E-01

7.97E+02

1.17E+03

8.38E+00

8.38E-01

8.13E+02

1.21E+03

8.56E+00

8.63E-01

8.30E+02

1.24E+03

8.73E+00

8.89E-01

8.47E+02

1.28E+03

8.91E+00

9.16E-01

8.65E+02

1.31E+03

9.10E+00

9.43E-01

8.83E+02

1.35E+03

9.29E+00

9.71E-01

9.01E+02

1.39E+03

9.48E+00

1.00E+00

9.20E+02

1.43E+03

9.68E+00

1.06E+00

9.58E+02

1.51E+03

1.01E+01

1.09E+00

9.78E+02

1.55E+03

1.03E+01

1.13E+00

9.99E+02

1.59E+03

1.05E+01

Nongestational Lifetime

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden

(ng/kg)

Blood
(ng/kg)

1.16E+00

1.02E+03

1.64E+03

1.07E+01

1.19E+00

1.04E+03

1.68E+03

1.10E+01

1.23E+00

1.06E+03

1.73E+03

1.12E+01

1.27E+00

1.09E+03

1.78E+03

1.14E+01

1.31E+00

1.11E+03

1.83E+03

1.17E+01

1.34E+00

1.13E+03

1.88E+03

1.19E+01

1.38E+00

1.16E+03

1.94E+03

1.22E+01

1.43E+00

1.18E+03

1.99E+03

1.24E+01

1.47E+00

1.21E+03

2.05E+03

1.27E+01

1.51E+00

1.23E+03

2.11E+03

1.30E+01

1.56E+00

1.26E+03

2.17E+03

1.32E+01

1.61E+00

1.28E+03

2.23E+03

1.35E+01

1.65E+00

1.31E+03

2.29E+03

1.38E+01

1.70E+00

1.34E+03

2.36E+03

1.41E+01

1.75E+00

1.37E+03

2.42E+03

1.44E+01

1.81E+00

1.40E+03

2.49E+03

1.47E+01

1.86E+00

1.43E+03

2.56E+03

1.50E+01

1.92E+00

1.46E+03

2.64E+03

1.54E+01

1.97E+00

1.49E+03

2.71E+03

1.57E+01

2.03E+00

1.52E+03

2.79E+03

1.60E+01

2.09E+00

1.56E+03

2.87E+03

1.64E+01

2.16E+00

1.59E+03

2.95E+03

1.67E+01

2.22E+00

1.62E+03

3.03E+03

1.71E+01

2.29E+00

1.66E+03

3.12E+03

1.75E+01

2.36E+00

1.70E+03

3.21E+03

1.79E+01

2.43E+00

1.73E+03

3.30E+03

1.82E+01

2.50E+00

1.77E+03

3.40E+03

1.86E+01

2.58E+00

1.81E+03

3.49E+03

1.91E+01

2.65E+00

1.85E+03

3.59E+03

1.95E+01


-------
o



Nongestational Lifetime

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden

(ng/kg)

Blood
(ng/kg)

2.73E+00

1.89E+03

3.70E+03

1.99E+01

2.82E+00

1.93E+03

3.80E+03

2.04E+01

2.90E+00

1.98E+03

3.91E+03

2.08E+01

2.99E+00

2.02E+03

4.03E+03

2.13E+01

3.08E+00

2.07E+03

4.14E+03

2.17E+01

3.17E+00

2.11E+03

4.26E+03

2.22E+01

3.26E+00

2.16E+03

4.38E+03

2.27E+01

3.36E+00

2.21E+03

4.51E+03

2.32E+01

3.46E+00

2.26E+03

4.64E+03

2.38E+01

3.57E+00

2.31E+03

4.77E+03

2.43E+01

3.67E+00

2.36E+03

4.91E+03

2.49E+01

3.78E+00

2.42E+03

5.05E+03

2.54E+01

3.90E+00

2.47E+03

5.20E+03

2.60E+01

4.01E+00

2.53E+03

5.35E+03

2.66E+01

4.13E+00

2.58E+03

5.50E+03

2.72E+01

4.26E+00

2.64E+03

5.66E+03

2.78E+01

4.39E+00

2.70E+03

5.83E+03

2.85E+01

4.52E+00

2.77E+03

6.00E+03

2.91E+01

4.65E+00

2.83E+03

6.17E+03

2.98E+01

4.79E+00

2.90E+03

6.35E+03

3.05E+01

4.94E+00

2.96E+03

6.53E+03

3.12E+01

5.08E+00

3.03E+03

6.72E+03

3.19E+01

5.24E+00

3.10E+03

6.92E+03

3.27E+01

5.39E+00

3.18E+03

7.12E+03

3.34E+01

5.56E+00

3.25E+03

7.33E+03

3.42E+01

5.72E+00

3.33E+03

7.54E+03

3.50E+01

5.89E+00

3.41E+03

7.76E+03

3.58E+01

6.07E+00

3.49E+03

7.98E+03

3.67E+01

6.25E+00

3.57E+03

8.22E+03

3.76E+01

Nongestational Lifetime

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden

(ng/kg)

Blood
(ng/kg)

6.44E+00

3.65E+03

8.45E+03

3.85E+01

6.63E+00

3.74E+03

8.70E+03

3.94E+01

6.83E+00

3.83E+03

8.95E+03

4.03E+01

7.04E+00

3.92E+03

9.21E+03

4.13E+01

7.25E+00

4.02E+03

9.48E+03

4.23E+01

7.47E+00

4.11E+03

9.76E+03

4.33E+01

7.69E+00

4.21E+03

1.00E+04

4.43E+01

7.92E+00

4.32E+03

1.03E+04

4.54E+01

8.16E+00

4.42E+03

1.06E+04

4.65E+01

8.40E+00

4.53E+03

1.10E+04

4.77E+01

8.66E+00

4.64E+03

1.13E+04

4.88E+01

8.92E+00

4.75E+03

1.16E+04

5.00E+01

9.18E+00

4.87E+03

1.19E+04

5.13E+01

9.46E+00

4.99E+03

1.23E+04

5.25E+01

9.74E+00

5.11E+03

1.26E+04

5.38E+01

1.00E+01

5.22E+03

1.30E+04

5.50E+01

1.00E+01

5.24E+03

1.30E+04

5.51E+01

1.34E+01

6.64E+03

1.72E+04

6.99E+01

1.67E+01

8.04E+03

2.14E+04

8.47E+01

2.00E+01

9.45E+03

2.56E+04

9.94E+01

2.33E+01

1.08E+04

2.97E+04

1.14E+02

2.67E+01

1.22E+04

3.39E+04

1.28E+02

3.00E+01

1.36E+04

3.81E+04

1.43E+02

3.33E+01

1.49E+04

4.22E+04

1.57E+02

3.67E+01

1.63E+04

4.63E+04

1.72E+02

4.00E+01

1.77E+04

5.05E+04

1.86E+02

4.33E+01

1.90E+04

5.46E+04

2.00E+02

4.67E+01

2.04E+04

5.87E+04

2.15E+02

5.00E+01

2.17E+04

6.28E+04

2.29E+02

1

Nongestational Lifetime

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden

(ng/kg)

Blood
(ng/kg)

5.33E+01

2.31E+04

6.69E+04

2.43E+02

5.67E+01

2.45E+04

7.10E+04

2.57E+02

6.00E+01

2.58E+04

7.51E+04

2.72E+02

6.33E+01

2.72E+04

7.92E+04

2.86E+02

6.67E+01

2.85E+04

8.32E+04

3.00E+02

7.00E+01

2.99E+04

8.73E+04

3.14E+02

7.33E+01

3.12E+04

9.13E+04

3.29E+02

7.67E+01

3.26E+04

9.54E+04

3.43E+02

8.00E+01

3.39E+04

9.94E+04

3.57E+02

8.33E+01

3.53E+04

1.03E+05

3.71E+02

8.67E+01

3.66E+04

1.07E+05

3.86E+02

9.00E+01

3.80E+04

1.12E+05

4.00E+02

9.33E+01

3.94E+04

1.16E+05

4.14E+02

9.67E+01

4.07E+04

1.20E+05

4.28E+02

1.00E+02

4.21E+04

1.24E+05

4.43E+02


-------
C.4.2. Nongestational 5-Year
Average

o



Non-gestational 5-year Average

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden
(ng/kg)

Blood
(ng/kg)

1.00E-09

5.18E-05

1.87E-05

5.45E-07

1.33E-09

6.90E-05

2.50E-05

7.26E-07

1.67E-09

8.62E-05

3.12E-05

9.07E-07

2.00E-09

1.03E-04

3.74E-05

1.09E-06

2.33E-09

1.21E-04

4.36E-05

1.27E-06

2.67E-09

1.38E-04

4.99E-05

1.45E-06

3.00E-09

1.55E-04

5.61E-05

1.63E-06

3.33E-09

1.72E-04

6.23E-05

1.81E-06

3.67E-09

1.90E-04

6.86E-05

1.99E-06

4.00E-09

2.07E-04

7.48E-05

2.17E-06

4.33E-09

2.24E-04

8.10E-05

2.36E-06

4.67E-09

2.41E-04

8.72E-05

2.54E-06

5.00E-09

2.58E-04

9.35E-05

2.72E-06

5.33E-09

2.76E-04

9.97E-05

2.90E-06

5.67E-09

2.93E-04

1.06E-04

3.08E-06

6.00E-09

3.10E-04

1.12E-04

3.26E-06

6.33E-09

3.27E-04

1.18E-04

3.44E-06

6.67E-09

3.44E-04

1.25E-04

3.62E-06

7.00E-09

3.61E-04

1.31E-04

3.80E-06

7.33E-09

3.79E-04

1.37E-04

3.98E-06

7.67E-09

3.96E-04

1.43E-04

4.16E-06

8.00E-09

4.13E-04

1.49E-04

4.34E-06

8.33E-09

4.30E-04

1.56E-04

4.52E-06

8.67E-09

4.47E-04

1.62E-04

4.70E-06

9.00E-09

4.65E-04

1.68E-04

4.89E-06

9.33E-09

4.82E-04

1.74E-04

5.07E-06

9.67E-09

4.99E-04

1.80E-04

5.25E-06

1.00E-08

5.16E-04

1.87E-04

5.43E-06

1.33E-08

6.87E-04

2.48E-04

7.22E-06

1.67E-08

8.57E-04

3.10E-04

9.01E-06

2.00E-08

1.03E-03

3.72E-04

1.08E-05

2.33E-08

1.20E-03

4.34E-04

1.26E-05

2.67E-08

1.37E-03

4.96E-04

1.44E-05

3.00E-08

1.54E-03

5.57E-04

1.62E-05

3.33E-08

1.71E-03

6.19E-04

1.80E-05

Non-gestational 5-year Average

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden
(ng/kg)

Blood
(ng/kg)

3.67E-08

1.88E-03

6.81E-04

1.98E-05

4.00E-08

2.05E-03

7.43E-04

2.16E-05

4.33E-08

2.22E-03

8.04E-04

2.34E-05

4.67E-08

2.39E-03

8.66E-04

2.51E-05

5.00E-08

2.56E-03

9.28E-04

2.69E-05

5.33E-08

2.73E-03

9.89E-04

2.87E-05

5.67E-08

2.90E-03

1.05E-03

3.05E-05

6.00E-08

3.07E-03

1.11E-03

3.23E-05

6.33E-08

3.24E-03

1.17E-03

3.40E-05

6.67E-08

3.41E-03

1.23E-03

3.58E-05

7.00E-08

3.57E-03

1.30E-03

3.76E-05

7.33E-08

3.74E-03

1.36E-03

3.94E-05

7.67E-08

3.91E-03

1.42E-03

4.11E-05

8.00E-08

4.08E-03

1.48E-03

4.29E-05

8.33E-08

4.25E-03

1.54E-03

4.47E-05

8.67E-08

4.42E-03

1.60E-03

4.65E-05

9.00E-08

4.59E-03

1.66E-03

4.82E-05

9.33E-08

4.76E-03

1.72E-03

5.00E-05

9.67E-08

4.93E-03

1.79E-03

5.18E-05

1.00E-07

5.09E-03

1.85E-03

5.36E-05

1.33E-07

6.74E-03

2.45E-03

7.09E-05

1.67E-07

8.39E-03

3.05E-03

8.82E-05

2.00E-07

1.00E-02

3.65E-03

1.06E-04

2.33E-07

1.17E-02

4.25E-03

1.23E-04

2.67E-07

1.33E-02

4.85E-03

1.40E-04

3.00E-07

1.50E-02

5.45E-03

1.57E-04

3.33E-07

1.66E-02

6.05E-03

1.75E-04

3.67E-07

1.83E-02

6.65E-03

1.92E-04

4.00E-07

1.99E-02

7.25E-03

2.09E-04

4.33E-07

2.16E-02

7.85E-03

2.27E-04

4.67E-07

2.32E-02

8.45E-03

2.44E-04

5.00E-07

2.49E-02

9.05E-03

2.61E-04

5.33E-07

2.64E-02

9.63E-03

2.78E-04

5.66E-07

2.80E-02

1.02E-02

2.94E-04

5.99E-07

2.96E-02

1.08E-02

3.11E-04

6.33E-07

3.11E-02

1.14E-02

3.28E-04

6.66E-07

3.27E-02

1.19E-02

3.44E-04

6.99E-07

3.43E-02

1.25E-02

3.61E-04

Non-gestational 5-year Average

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden
(ng/kg)

Blood
(ng/kg)

7.32E-07

3.59E-02

1.31E-02

3.77E-04

7.65E-07

3.74E-02

1.37E-02

3.94E-04

7.98E-07

3.90E-02

1.42E-02

4.10E-04

8.32E-07

4.06E-02

1.48E-02

4.27E-04

8.65E-07

4.22E-02

1.54E-02

4.43E-04

8.98E-07

4.37E-02

1.60E-02

4.60E-04

9.31E-07

4.53E-02

1.66E-02

4.77E-04

9.64E-07

4.69E-02

1.71E-02

4.93E-04

9.97E-07

4.85E-02

1.77E-02

5.10E-04

1.01E-06

4.92E-02

1.80E-02

5.17E-04

1.03E-06

4.99E-02

1.82E-02

5.24E-04

1.04E-06

5.06E-02

1.85E-02

5.32E-04

1.06E-06

5.13E-02

1.88E-02

5.40E-04

1.07E-06

5.20E-02

1.90E-02

5.47E-04

1.09E-06

5.28E-02

1.93E-02

5.55E-04

1.11E-06

5.35E-02

1.96E-02

5.63E-04

1.12E-06

5.43E-02

1.99E-02

5.71E-04

1.14E-06

5.51E-02

2.01E-02

5.79E-04

1.16E-06

5.59E-02

2.04E-02

5.88E-04

1.17E-06

5.67E-02

2.07E-02

5.96E-04

1.19E-06

5.75E-02

2.10E-02

6.05E-04

1.21E-06

5.83E-02

2.13E-02

6.13E-04

1.23E-06

5.92E-02

2.16E-02

6.22E-04

1.24E-06

6.00E-02

2.20E-02

6.31E-04

1.26E-06

6.09E-02

2.23E-02

6.40E-04

1.28E-06

6.17E-02

2.26E-02

6.49E-04

1.30E-06

6.26E-02

2.29E-02

6.58E-04

1.32E-06

6.35E-02

2.32E-02

6.68E-04

1.34E-06

6.44E-02

2.36E-02

6.77E-04

1.36E-06

6.53E-02

2.39E-02

6.87E-04

1.38E-06

6.63E-02

2.43E-02

6.97E-04

1.40E-06

6.72E-02

2.46E-02

7.07E-04

1.42E-06

6.82E-02

2.50E-02

7.17E-04

1.44E-06

6.91E-02

2.53E-02

7.27E-04

1.46E-06

7.02E-02

2.57E-02

7.38E-04

1.49E-06

7.12E-02

2.61E-02

7.48E-04

1.53E-06

7.32E-02

2.68E-02

7.70E-04

1.58E-06

7.53E-02

2.76E-02

7.92E-04


-------
o



Non-gestational 5-year Average

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden
(ng/kg)

Blood
(ng/kg)

1.62E-06

7.74E-02

2.84E-02

8.14E-04

1.67E-06

7.96E-02

2.92E-02

8.37E-04

1.72E-06

8.19E-02

3.00E-02

8.61E-04

1.77E-06

8.42E-02

3.09E-02

8.86E-04

1.83E-06

8.66E-02

3.18E-02

9.11E-04

1.88E-06

8.91E-02

3.27E-02

9.37E-04

1.94E-06

9.16E-02

3.36E-02

9.63E-04

2.00E-06

9.42E-02

3.46E-02

9.91E-04

2.06E-06

9.69E-02

3.56E-02

1.02E-03

2.12E-06

9.96E-02

3.66E-02

1.05E-03

2.18E-06

1.02E-01

3.77E-02

1.08E-03

2.25E-06

1.05E-01

3.87E-02

1.11E-03

2.32E-06

1.08E-01

3.98E-02

1.14E-03

2.39E-06

1.11E-01

4.10E-02

1.17E-03

2.46E-06

1.15E-01

4.21E-02

1.20E-03

2.53E-06

1.18E-01

4.33E-02

1.24E-03

2.61E-06

1.21E-01

4.46E-02

1.27E-03

2.68E-06

1.24E-01

4.58E-02

1.31E-03

2.76E-06

1.28E-01

4.71E-02

1.35E-03

2.85E-06

1.32E-01

4.85E-02

1.38E-03

2.93E-06

1.35E-01

4.98E-02

1.42E-03

3.02E-06

1.39E-01

5.13E-02

1.46E-03

3.11E-06

1.43E-01

5.27E-02

1.50E-03

3.21E-06

1.47E-01

5.42E-02

1.54E-03

3.30E-06

1.51E-01

5.57E-02

1.59E-03

3.40E-06

1.55E-01

5.73E-02

1.63E-03

3.50E-06

1.59E-01

5.89E-02

1.68E-03

3.61E-06

1.64E-01

6.05E-02

1.72E-03

3.72E-06

1.68E-01

6.22E-02

1.77E-03

3.83E-06

1.73E-01

6.40E-02

1.82E-03

3.94E-06

1.78E-01

6.58E-02

1.87E-03

4.06E-06

1.83E-01

6.76E-02

1.92E-03

4.18E-06

1.88E-01

6.95E-02

1.97E-03

4.31E-06

1.93E-01

7.15E-02

2.03E-03

4.44E-06

1.98E-01

7.34E-02

2.08E-03

4.57E-06

2.04E-01

7.55E-02

2.14E-03

4.71E-06

2.09E-01

7.76E-02

2.20E-03

4.85E-06

2.15E-01

7.98E-02

2.26E-03

Non-gestational 5-year Average

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden
(ng/kg)

Blood
(ng/kg)

4.99E-06

2.21E-01

8.20E-02

2.32E-03

5.14E-06

2.27E-01

8.42E-02

2.39E-03

5.30E-06

2.33E-01

8.66E-02

2.45E-03

5.46E-06

2.39E-01

8.90E-02

2.52E-03

5.62E-06

2.46E-01

9.14E-02

2.59E-03

5.79E-06

2.53E-01

9.39E-02

2.66E-03

5.96E-06

2.59E-01

9.65E-02

2.73E-03

6.14E-06

2.66E-01

9.92E-02

2.80E-03

6.33E-06

2.74E-01

1.02E-01

2.88E-03

6.52E-06

2.81E-01

1.05E-01

2.95E-03

6.71E-06

2.88E-01

1.07E-01

3.03E-03

6.91E-06

2.96E-01

1.10E-01

3.11E-03

7.12E-06

3.04E-01

1.13E-01

3.19E-03

7.33E-06

3.12E-01

1.16E-01

3.28E-03

7.55E-06

3.20E-01

1.19E-01

3.36E-03

7.78E-06

3.28E-01

1.23E-01

3.45E-03

8.01E-06

3.37E-01

1.26E-01

3.54E-03

8.25E-06

3.46E-01

1.29E-01

3.64E-03

8.50E-06

3.55E-01

1.33E-01

3.73E-03

8.76E-06

3.64E-01

1.36E-01

3.83E-03

9.02E-06

3.74E-01

1.40E-01

3.93E-03

9.29E-06

3.84E-01

1.44E-01

4.04E-03

9.57E-06

3.94E-01

1.48E-01

4.15E-03

9.86E-06

4.05E-01

1.52E-01

4.25E-03

1.02E-05

4.15E-01

1.56E-01

4.36E-03

1.05E-05

4.26E-01

1.60E-01

4.48E-03

1.08E-05

4.37E-01

1.64E-01

4.59E-03

1.11E-05

4.48E-01

1.68E-01

4.71E-03

1.14E-05

4.60E-01

1.73E-01

4.83E-03

1.18E-05

4.72E-01

1.78E-01

4.96E-03

1.21E-05

4.84E-01

1.82E-01

5.08E-03

1.25E-05

4.96E-01

1.87E-01

5.21E-03

1.29E-05

5.09E-01

1.92E-01

5.35E-03

1.32E-05

5.22E-01

1.97E-01

5.49E-03

1.36E-05

5.35E-01

2.02E-01

5.63E-03

1.41E-05

5.49E-01

2.08E-01

5.77E-03

1.45E-05

5.63E-01

2.13E-01

5.92E-03

1.49E-05

5.77E-01

2.18E-01

6.07E-03

Non-gestational 5-year Average

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden
(ng/kg)

Blood
(ng/kg)

1.54E-05

5.92E-01

2.24E-01

6.23E-03

1.58E-05

6.07E-01

2.30E-01

6.38E-03

1.63E-05

6.23E-01

2.36E-01

6.55E-03

1.68E-05

6.38E-01

2.42E-01

6.71E-03

1.73E-05

6.54E-01

2.49E-01

6.88E-03

1.78E-05

6.71E-01

2.55E-01

7.05E-03

1.83E-05

6.88E-01

2.62E-01

7.23E-03

1.89E-05

7.05E-01

2.69E-01

7.41E-03

1.95E-05

7.23E-01

2.75E-01

7.60E-03

2.00E-05

7.41E-01

2.83E-01

7.79E-03

2.06E-05

7.60E-01

2.90E-01

7.99E-03

2.13E-05

7.79E-01

2.97E-01

8.18E-03

2.19E-05

7.98E-01

3.05E-01

8.39E-03

2.25E-05

8.18E-01

3.13E-01

8.60E-03

2.32E-05

8.38E-01

3.21E-01

8.81E-03

2.39E-05

8.59E-01

3.29E-01

9.03E-03

2.46E-05

8.80E-01

3.38E-01

9.25E-03

2.54E-05

9.02E-01

3.46E-01

9.48E-03

2.61E-05

9.24E-01

3.55E-01

9.71E-03

2.69E-05

9.47E-01

3.64E-01

9.95E-03

2.77E-05

9.70E-01

3.73E-01

1.02E-02

2.86E-05

9.94E-01

3.83E-01

1.04E-02

2.94E-05

1.02E+00

3.92E-01

1.07E-02

3.03E-05

1.04E+00

4.02E-01

1.10E-02

3.12E-05

1.07E+00

4.12E-01

1.12E-02

3.21E-05

1.09E+00

4.23E-01

1.15E-02

3.31E-05

1.12E+00

4.35E-01

1.18E-02

3.41E-05

1.15E+00

4.46E-01

1.21E-02

3.51E-05

1.18E+00

4.57E-01

1.23E-02

3.62E-05

1.21E+00

4.68E-01

1.27E-02

3.73E-05

1.24E+00

4.80E-01

1.30E-02

3.84E-05

1.26E+00

4.92E-01

1.33E-02

3.95E-05

1.29E+00

5.04E-01

1.35E-02

4.07E-05

1.32E+00

5.14E-01

1.39E-02

4.19E-05

1.35E+00

5.26E-01

1.42E-02

4.32E-05

1.38E+00

5.39E-01

1.45E-02

4.45E-05

1.41E+00

5.52E-01

1.49E-02

4.58E-05

1.45E+00

5.66E-01

1.52E-02


-------
o



Non-gestational 5-year Average

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden
(ng/kg)

Blood
(ng/kg)

4.72E-05

1.48E+00

5.80E-01

1.56E-02

4.86E-05

1.52E+00

5.94E-01

1.59E-02

5.01E-05

1.55E+00

6.08E-01

1.63E-02

5.16E-05

1.59E+00

6.23E-01

1.67E-02

5.31E-05

1.62E+00

6.38E-01

1.71E-02

5.47E-05

1.66E+00

6.53E-01

1.75E-02

5.64E-05

1.70E+00

6.69E-01

1.79E-02

5.81E-05

1.74E+00

6.85E-01

1.83E-02

5.98E-05

1.78E+00

7.02E-01

1.87E-02

6.16E-05

1.82E+00

7.19E-01

1.91E-02

6.34E-05

1.86E+00

7.36E-01

1.96E-02

6.54E-05

1.90E+00

7.53E-01

2.00E-02

6.73E-05

1.95E+00

7.71E-01

2.05E-02

6.93E-05

1.99E+00

7.90E-01

2.09E-02

7.14E-05

2.04E+00

8.08E-01

2.14E-02

7.36E-05

2.06E+00

8.18E-01

2.16E-02

7.58E-05

2.11E+00

8.37E-01

2.21E-02

7.80E-05

2.15E+00

8.57E-01

2.26E-02

8.04E-05

2.20E+00

8.77E-01

2.31E-02

8.28E-05

2.25E+00

8.98E-01

2.36E-02

8.53E-05

2.30E+00

9.19E-01

2.42E-02

8.78E-05

2.35E+00

9.40E-01

2.47E-02

9.05E-05

2.40E+00

9.62E-01

2.52E-02

9.32E-05

2.46E+00

9.84E-01

2.58E-02

9.60E-05

2.51E+00

1.01E+00

2.64E-02

9.89E-05

2.57E+00

1.03E+00

2.69E-02

1.02E-04

2.62E+00

1.05E+00

2.75E-02

1.05E-04

2.68E+00

1.08E+00

2.81E-02

1.08E-04

2.74E+00

1.10E+00

2.88E-02

1.11E-04

2.80E+00

1.13E+00

2.94E-02

1.15E-04

2.86E+00

1.15E+00

3.00E-02

1.18E-04

2.92E+00

1.18E+00

3.07E-02

1.22E-04

2.98E+00

1.21E+00

3.13E-02

1.25E-04

3.05E+00

1.24E+00

3.20E-02

1.29E-04

3.11E+00

1.26E+00

3.27E-02

1.33E-04

3.18E+00

1.29E+00

3.34E-02

1.37E-04

3.25E+00

1.32E+00

3.41E-02

1.41E-04

3.32E+00

1.35E+00

3.48E-02

Non-gestational 5-year Average

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden
(ng/kg)

Blood
(ng/kg)

1.45E-04

3.45E+00

1.41E+00

3.62E-02

1.50E-04

3.46E+00

1.41E+00

3.63E-02

1.54E-04

3.53E+00

1.45E+00

3.71E-02

1.59E-04

3.67E+00

1.51E+00

3.86E-02

1.63E-04

3.75E+00

1.54E+00

3.94E-02

1.68E-04

3.77E+00

1.55E+00

3.96E-02

1.73E-04

3.86E+00

1.59E+00

4.06E-02

1.79E-04

3.95E+00

1.63E+00

4.15E-02

1.84E-04

4.04E+00

1.67E+00

4.24E-02

1.89E-04

4.13E+00

1.71E+00

4.33E-02

1.95E-04

4.22E+00

1.75E+00

4.43E-02

2.01E-04

4.31E+00

1.79E+00

4.52E-02

2.07E-04

4.44E+00

1.84E+00

4.66E-02

2.13E-04

4.49E+00

1.87E+00

4.72E-02

2.20E-04

4.59E+00

1.92E+00

4.82E-02

2.26E-04

4.72E+00

1.97E+00

4.95E-02

2.33E-04

4.81E+00

2.02E+00

5.05E-02

2.40E-04

4.91E+00

2.06E+00

5.16E-02

2.47E-04

5.00E+00

2.10E+00

5.24E-02

2.55E-04

5.10E+00

2.15E+00

5.35E-02

2.62E-04

5.21E+00

2.19E+00

5.47E-02

2.70E-04

5.33E+00

2.25E+00

5.60E-02

2.78E-04

5.44E+00

2.30E+00

5.71E-02

2.86E-04

5.55E+00

2.35E+00

5.83E-02

2.95E-04

5.66E+00

2.40E+00

5.94E-02

3.04E-04

5.78E+00

2.46E+00

6.07E-02

3.13E-04

5.90E+00

2.51E+00

6.19E-02

3.22E-04

6.02E+00

2.57E+00

6.32E-02

3.32E-04

6.14E+00

2.63E+00

6.44E-02

3.42E-04

6.26E+00

2.68E+00

6.57E-02

3.52E-04

6.39E+00

2.74E+00

6.71E-02

3.63E-04

6.52E+00

2.80E+00

6.84E-02

3.74E-04

6.65E+00

2.87E+00

6.98E-02

3.85E-04

6.78E+00

2.93E+00

7.12E-02

3.97E-04

6.92E+00

3.00E+00

7.26E-02

4.08E-04

7.06E+00

3.06E+00

7.41E-02

4.21E-04

7.20E+00

3.13E+00

7.56E-02

4.33E-04

7.34E+00

3.20E+00

7.71E-02

Non-gestational 5-year Average

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden
(ng/kg)

Blood
(ng/kg)

4.46E-04

7.49E+00

3.27E+00

7.86E-02

4.60E-04

7.64E+00

3.34E+00

8.02E-02

4.74E-04

7.79E+00

3.42E+00

8.18E-02

4.88E-04

7.95E+00

3.49E+00

8.34E-02

5.02E-04

8.10E+00

3.57E+00

8.50E-02

5.17E-04

8.26E+00

3.65E+00

8.67E-02

5.33E-04

8.43E+00

3.73E+00

8.84E-02

5.49E-04

8.59E+00

3.81E+00

9.02E-02

5.65E-04

8.76E+00

3.89E+00

9.19E-02

5.82E-04

8.93E+00

3.98E+00

9.37E-02

6.00E-04

9.11E+00

4.07E+00

9.56E-02

6.18E-04

9.29E+00

4.16E+00

9.74E-02

6.36E-04

9.47E+00

4.25E+00

9.94E-02

6.55E-04

9.65E+00

4.34E+00

1.01E-01

6.75E-04

9.84E+00

4.44E+00

1.03E-01

6.95E-04

1.00E+01

4.54E+00

1.05E-01

7.16E-04

1.02E+01

4.64E+00

1.07E-01

7.38E-04

1.04E+01

4.74E+00

1.09E-01

7.60E-04

1.06E+01

4.84E+00

1.12E-01

7.83E-04

1.08E+01

4.95E+00

1.14E-01

8.06E-04

1.10E+01

5.06E+00

1.16E-01

8.30E-04

1.13E+01

5.17E+00

1.18E-01

8.55E-04

1.15E+01

5.28E+00

1.20E-01

8.81E-04

1.17E+01

5.40E+00

1.23E-01

9.07E-04

1.19E+01

5.52E+00

1.25E-01

9.21E-04

1.20E+01

5.58E+00

1.26E-01

9.35E-04

1.22E+01

5.64E+00

1.27E-01

9.49E-04

1.30E+01

6.23E+00

1.37E-01

9.63E-04

1.38E+01

6.92E+00

1.45E-01

9.69E-04

1.43E+01

7.14E+00

1.50E-01

9.77E-04

1.48E+01

7.34E+00

1.55E-01

9.84E-04

1.52E+01

7.50E+00

1.59E-01

9.91E-04

1.55E+01

7.64E+00

1.63E-01

1.37E-03

1.56E+01

7.50E+00

1.63E-01

1.39E-03

1.57E+01

7.58E+00

1.65E-01

1.41E-03

1.59E+01

7.66E+00

1.66E-01

1.43E-03

1.60E+01

7.75E+00

1.68E-01

1.46E-03

1.62E+01

7.83E+00

1.69E-01


-------
o



Non-gestational 5-year Average

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden
(ng/kg)

Blood
(ng/kg)

1.48E-03

1.63E+01

7.92E+00

1.71E-01

1.50E-03

1.65E+01

8.00E+00

1.73E-01

1.52E-03

1.66E+01

8.09E+00

1.74E-01

1.54E-03

1.68E+01

8.18E+00

1.76E-01

1.57E-03

1.69E+01

8.27E+00

1.78E-01

1.59E-03

1.71E+01

8.36E+00

1.79E-01

1.61E-03

1.73E+01

8.46E+00

1.81E-01

1.64E-03

1.74E+01

8.55E+00

1.83E-01

1.66E-03

1.76E+01

8.64E+00

1.84E-01

1.69E-03

1.78E+01

8.74E+00

1.86E-01

1.71E-03

1.79E+01

8.83E+00

1.88E-01

1.74E-03

1.81E+01

8.93E+00

1.90E-01

1.76E-03

1.83E+01

9.03E+00

1.92E-01

1.79E-03

1.84E+01

9.13E+00

1.93E-01

1.82E-03

1.86E+01

9.23E+00

1.95E-01

1.84E-03

1.88E+01

9.33E+00

1.97E-01

1.87E-03

1.91E+01

9.53E+00

2.00E-01

1.90E-03

1.98E+01

1.01E+01

2.08E-01

1.93E-03

2.05E+01

1.08E+01

2.14E-01

1.96E-03

2.05E+01

1.05E+01

2.14E-01

2.27E-03

2.14E+01

1.09E+01

2.25E-01

2.34E-03

2.18E+01

1.11E+01

2.29E-01

2.41E-03

2.22E+01

1.14E+01

2.33E-01

2.48E-03

2.26E+01

1.16E+01

2.37E-01

2.55E-03

2.31E+01

1.19E+01

2.42E-01

2.63E-03

2.35E+01

1.22E+01

2.46E-01

2.71E-03

2.39E+01

1.24E+01

2.51E-01

2.79E-03

2.44E+01

1.27E+01

2.56E-01

2.87E-03

2.49E+01

1.30E+01

2.61E-01

2.96E-03

2.53E+01

1.33E+01

2.66E-01

3.05E-03

2.58E+01

1.36E+01

2.71E-01

3.14E-03

2.63E+01

1.39E+01

2.76E-01

3.23E-03

2.68E+01

1.42E+01

2.81E-01

3.33E-03

2.73E+01

1.45E+01

2.86E-01

3.43E-03

2.78E+01

1.49E+01

2.91E-01

3.53E-03

2.83E+01

1.52E+01

2.97E-01

3.64E-03

2.88E+01

1.55E+01

3.02E-01

3.75E-03

2.96E+01

1.61E+01

3.10E-01

Non-gestational 5-year Average

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden
(ng/kg)

Blood
(ng/kg)

3.81E-03

2.99E+01

1.63E+01

3.14E-01

3.86E-03

3.00E+01

1.63E+01

3.14E-01

4.22E-03

3.04E+01

1.66E+01

3.19E-01

4.35E-03

3.10E+01

1.69E+01

3.25E-01

4.48E-03

3.16E+01

1.73E+01

3.31E-01

4.61E-03

3.21E+01

1.77E+01

3.37E-01

4.75E-03

3.28E+01

1.81E+01

3.44E-01

4.89E-03

3.34E+01

1.86E+01

3.50E-01

5.04E-03

3.44E+01

1.94E+01

3.60E-01

5.19E-03

3.57E+01

2.06E+01

3.74E-01

5.35E-03

3.72E+01

2.12E+01

3.90E-01

5.51E-03

3.81E+01

2.17E+01

3.99E-01

5.67E-03

3.88E+01

2.23E+01

4.07E-01

5.84E-03

3.95E+01

2.28E+01

4.14E-01

5.93E-03

3.98E+01

2.30E+01

4.18E-01

6.02E-03

4.00E+01

2.33E+01

4.20E-01

6.20E-03

4.10E+01

2.38E+01

4.30E-01

6.38E-03

4.18E+01

2.44E+01

4.38E-01

6.57E-03

4.26E+01

2.49E+01

4.46E-01

6.77E-03

4.34E+01

2.55E+01

4.55E-01

6.98E-03

4.42E+01

2.61E+01

4.63E-01

7.18E-03

4.50E+01

2.67E+01

4.72E-01

7.40E-03

4.59E+01

2.73E+01

4.81E-01

7.51E-03

4.63E+01

2.77E+01

4.85E-01

7.62E-03

4.66E+01

2.78E+01

4.88E-01

7.85E-03

4.71E+01

2.81E+01

4.94E-01

8.09E-03

4.72E+01

2.79E+01

4.95E-01

8.33E-03

4.74E+01

2.83E+01

4.97E-01

8.58E-03

4.93E+01

2.99E+01

5.17E-01

8.71E-03

4.98E+01

3.03E+01

5.22E-01

8.84E-03

5.03E+01

3.06E+01

5.27E-01

9.10E-03

5.13E+01

3.15E+01

5.38E-01

9.37E-03

5.23E+01

3.22E+01

5.49E-01

9.66E-03

5.33E+01

3.29E+01

5.59E-01

9.94E-03

5.44E+01

3.38E+01

5.70E-01

1.02E-02

5.54E+01

3.46E+01

5.81E-01

1.06E-02

5.64E+01

3.54E+01

5.92E-01

1.09E-02

5.75E+01

3.62E+01

6.03E-01

Non-gestational 5-year Average

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden
(ng/kg)

Blood
(ng/kg)

1.12E-02

5.86E+01

3.71E+01

6.14E-01

1.15E-02

5.96E+01

3.79E+01

6.25E-01

1.19E-02

6.05E+01

3.85E+01

6.35E-01

1.22E-02

6.14E+01

3.92E+01

6.43E-01

1.26E-02

6.24E+01

4.01E+01

6.54E-01

1.30E-02

6.38E+01

4.15E+01

6.69E-01

1.34E-02

6.56E+01

4.31E+01

6.87E-01

1.38E-02

6.74E+01

4.42E+01

7.07E-01

1.42E-02

6.87E+01

4.53E+01

7.20E-01

1.46E-02

6.94E+01

4.59E+01

7.28E-01

1.50E-02

7.06E+01

4.69E+01

7.40E-01

1.55E-02

7.19E+01

4.78E+01

7.54E-01

1.60E-02

7.30E+01

4.87E+01

7.66E-01

1.64E-02

7.38E+01

4.96E+01

7.74E-01

1.69E-02

7.55E+01

5.11E+01

7.92E-01

1.74E-02

7.69E+01

5.23E+01

8.07E-01

1.80E-02

7.84E+01

5.36E+01

8.22E-01

1.85E-02

7.99E+01

5.49E+01

8.37E-01

1.91E-02

8.13E+01

5.62E+01

8.53E-01

1.96E-02

8.29E+01

5.75E+01

8.69E-01

2.02E-02

8.44E+01

5.89E+01

8.85E-01

2.08E-02

8.60E+01

6.03E+01

9.01E-01

2.14E-02

8.76E+01

6.18E+01

9.18E-01

2.21E-02

8.92E+01

6.32E+01

9.35E-01

2.28E-02

9.09E+01

6.48E+01

9.53E-01

2.34E-02

9.26E+01

6.63E+01

9.71E-01

2.41E-02

9.44E+01

6.80E+01

9.89E-01

2.49E-02

9.64E+01

6.98E+01

1.01E+00

2.56E-02

9.79E+01

7.13E+01

1.03E+00

2.64E-02

9.98E+01

7.30E+01

1.05E+00

2.72E-02

1.02E+02

7.48E+01

1.07E+00

2.80E-02

1.04E+02

7.66E+01

1.09E+00

2.88E-02

1.06E+02

7.85E+01

1.11E+00

2.97E-02

1.07E+02

8.04E+01

1.13E+00

3.06E-02

1.10E+02

8.28E+01

1.15E+00

3.15E-02

1.12E+02

8.51E+01

1.17E+00

3.24E-02

1.14E+02

8.69E+01

1.20E+00

3.34E-02

1.16E+02

8.88E+01

1.22E+00


-------
o



Non-gestational 5-year Average

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden
(ng/kg)

Blood
(ng/kg)

3.44E-02

1.18E+02

9.08E+01

1.24E+00

3.54E-02

1.20E+02

9.28E+01

1.26E+00

3.65E-02

1.22E+02

9.47E+01

1.28E+00

3.76E-02

1.24E+02

9.73E+01

1.30E+00

3.87E-02

1.27E+02

9.96E+01

1.33E+00

3.99E-02

1.29E+02

1.02E+02

1.35E+00

4.11E-02

1.32E+02

1.04E+02

1.38E+00

4.23E-02

1.34E+02

1.07E+02

1.40E+00

4.36E-02

1.37E+02

1.10E+02

1.43E+00

4.49E-02

1.40E+02

1.13E+02

1.47E+00

4.63E-02

1.43E+02

1.16E+02

1.49E+00

4.76E-02

1.45E+02

1.19E+02

1.52E+00

4.91E-02

1.48E+02

1.22E+02

1.55E+00

5.05E-02

1.51E+02

1.25E+02

1.58E+00

5.21E-02

1.53E+02

1.28E+02

1.61E+00

5.36E-02

1.56E+02

1.31E+02

1.64E+00

5.52E-02

1.59E+02

1.34E+02

1.67E+00

5.69E-02

1.62E+02

1.38E+02

1.70E+00

5.86E-02

1.65E+02

1.41E+02

1.73E+00

6.03E-02

1.69E+02

1.45E+02

1.77E+00

6.22E-02

1.72E+02

1.48E+02

1.80E+00

6.40E-02

1.74E+02

1.52E+02

1.83E+00

6.59E-02

1.78E+02

1.55E+02

1.86E+00

6.79E-02

1.81E+02

1.59E+02

1.90E+00

7.00E-02

1.84E+02

1.63E+02

1.93E+00

7.21E-02

1.88E+02

1.67E+02

1.97E+00

7.42E-02

1.91E+02

1.71E+02

2.01E+00

7.64E-02

1.95E+02

1.76E+02

2.05E+00

7.87E-02

1.99E+02

1.81E+02

2.09E+00

8.11E-02

2.03E+02

1.86E+02

2.13E+00

8.35E-02

2.07E+02

1.90E+02

2.17E+00

8.60E-02

2.11E+02

1.95E+02

2.21E+00

8.86E-02

2.15E+02

2.00E+02

2.25E+00

9.13E-02

2.19E+02

2.05E+02

2.30E+00

9.40E-02

2.23E+02

2.10E+02

2.34E+00

9.68E-02

2.27E+02

2.16E+02

2.38E+00

9.97E-02

2.32E+02

2.22E+02

2.43E+00

1.03E-01

2.36E+02

2.27E+02

2.48E+00

Non-gestational 5-year Average

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden
(ng/kg)

Blood
(ng/kg)

1.06E-01

2.41E+02

2.33E+02

2.52E+00

1.09E-01

2.45E+02

2.39E+02

2.57E+00

1.12E-01

2.50E+02

2.44E+02

2.62E+00

1.16E-01

2.55E+02

2.51E+02

2.67E+00

1.19E-01

2.60E+02

2.57E+02

2.72E+00

1.23E-01

2.65E+02

2.64E+02

2.77E+00

1.26E-01

2.70E+02

2.71E+02

2.83E+00

1.30E-01

2.75E+02

2.78E+02

2.88E+00

1.34E-01

2.80E+02

2.86E+02

2.94E+00

1.38E-01

2.86E+02

2.93E+02

3.00E+00

1.42E-01

2.92E+02

3.01E+02

3.06E+00

1.46E-01

2.97E+02

3.09E+02

3.11E+00

1.51E-01

3.03E+02

3.16E+02

3.17E+00

1.55E-01

3.08E+02

3.24E+02

3.23E+00

1.60E-01

3.14E+02

3.33E+02

3.29E+00

1.65E-01

3.20E+02

3.42E+02

3.36E+00

1.70E-01

3.27E+02

3.51E+02

3.42E+00

1.75E-01

3.33E+02

3.60E+02

3.49E+00

1.80E-01

3.39E+02

3.69E+02

3.56E+00

1.86E-01

3.46E+02

3.79E+02

3.63E+00

1.91E-01

3.53E+02

3.89E+02

3.70E+00

1.97E-01

3.60E+02

3.99E+02

3.77E+00

2.03E-01

3.66E+02

4.09E+02

3.84E+00

2.09E-01

3.73E+02

4.20E+02

3.91E+00

2.15E-01

3.81E+02

4.31E+02

3.99E+00

2.22E-01

3.88E+02

4.43E+02

4.07E+00

2.28E-01

3.96E+02

4.55E+02

4.15E+00

2.35E-01

4.03E+02

4.67E+02

4.23E+00

2.42E-01

4.11E+02

4.79E+02

4.31E+00

2.49E-01

4.20E+02

4.92E+02

4.40E+00

2.57E-01

4.28E+02

5.05E+02

4.48E+00

2.65E-01

4.36E+02

5.19E+02

4.57E+00

2.72E-01

4.45E+02

5.32E+02

4.66E+00

2.81E-01

4.53E+02

5.46E+02

4.75E+00

2.89E-01

4.62E+02

5.61E+02

4.84E+00

2.98E-01

4.71E+02

5.75E+02

4.93E+00

3.07E-01

4.80E+02

5.91E+02

5.03E+00

3.16E-01

4.90E+02

6.07E+02

5.13E+00

Non-gestational 5-year Average

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden
(ng/kg)

Blood
(ng/kg)

3.25E-01

4.99E+02

6.23E+02

5.23E+00

3.35E-01

5.09E+02

6.40E+02

5.34E+00

3.45E-01

5.19E+02

6.57E+02

5.44E+00

3.56E-01

5.30E+02

6.75E+02

5.55E+00

3.66E-01

5.40E+02

6.93E+02

5.66E+00

3.77E-01

5.51E+02

7.12E+02

5.77E+00

3.89E-01

5.62E+02

7.31E+02

5.89E+00

4.00E-01

5.73E+02

7.51E+02

6.00E+00

4.12E-01

5.84E+02

7.71E+02

6.12E+00

4.25E-01

5.96E+02

7.92E+02

6.25E+00

4.37E-01

6.08E+02

8.13E+02

6.37E+00

4.50E-01

6.20E+02

8.35E+02

6.50E+00

4.64E-01

6.32E+02

8.58E+02

6.63E+00

4.92E-01

6.58E+02

9.05E+02

6.89E+00

5.07E-01

6.71E+02

9.29E+02

7.03E+00

5.22E-01

6.85E+02

9.55E+02

7.17E+00

5.54E-01

7.12E+02

1.01E+03

7.46E+00

5.71E-01

7.27E+02

1.04E+03

7.61E+00

5.88E-01

7.41E+02

1.06E+03

7.77E+00

6.05E-01

7.56E+02

1.09E+03

7.92E+00

6.23E-01

7.71E+02

1.12E+03

8.08E+00

6.61E-01

8.03E+02

1.18E+03

8.41E+00

6.81E-01

8.19E+02

1.22E+03

8.58E+00

7.02E-01

8.36E+02

1.25E+03

8.76E+00

7.23E-01

8.53E+02

1.28E+03

8.94E+00

7.44E-01

8.70E+02

1.32E+03

9.12E+00

7.67E-01

8.88E+02

1.36E+03

9.31E+00

7.90E-01

9.06E+02

1.39E+03

9.50E+00

8.13E-01

9.25E+02

1.43E+03

9.69E+00

8.38E-01

9.44E+02

1.47E+03

9.89E+00

8.63E-01

9.63E+02

1.51E+03

1.01E+01

8.89E-01

9.83E+02

1.55E+03

1.03E+01

9.16E-01

1.00E+03

1.60E+03

1.05E+01

9.43E-01

1.02E+03

1.64E+03

1.07E+01

9.71E-01

1.05E+03

1.69E+03

1.10E+01

1.00E+00

1.07E+03

1.73E+03

1.12E+01

1.06E+00

1.11E+03

1.83E+03

1.16E+01

1.09E+00

1.14E+03

1.88E+03

1.19E+01


-------
o



Non-gestational 5-year Average

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden
(ng/kg)

Blood
(ng/kg)

1.13E+00

1.16E+03

1.94E+03

1.21E+01

1.16E+00

1.18E+03

1.99E+03

1.24E+01

1.19E+00

1.21E+03

2.04E+03

1.27E+01

1.23E+00

1.23E+03

2.10E+03

1.29E+01

1.27E+00

1.26E+03

2.16E+03

1.32E+01

1.31E+00

1.29E+03

2.22E+03

1.35E+01

1.34E+00

1.31E+03

2.28E+03

1.38E+01

1.38E+00

1.34E+03

2.35E+03

1.40E+01

1.43E+00

1.37E+03

2.41E+03

1.43E+01

1.47E+00

1.40E+03

2.48E+03

1.46E+01

1.51E+00

1.43E+03

2.55E+03

1.50E+01

1.56E+00

1.46E+03

2.62E+03

1.53E+01

1.61E+00

1.49E+03

2.69E+03

1.56E+01

1.65E+00

1.52E+03

2.77E+03

1.59E+01

1.70E+00

1.55E+03

2.85E+03

1.63E+01

1.75E+00

1.59E+03

2.93E+03

1.66E+01

1.81E+00

1.62E+03

3.01E+03

1.70E+01

1.86E+00

1.66E+03

3.10E+03

1.74E+01

1.92E+00

1.69E+03

3.18E+03

1.77E+01

1.97E+00

1.73E+03

3.27E+03

1.81E+01

2.03E+00

1.77E+03

3.37E+03

1.85E+01

2.09E+00

1.80E+03

3.46E+03

1.89E+01

2.16E+00

1.84E+03

3.56E+03

1.93E+01

2.22E+00

1.88E+03

3.66E+03

1.97E+01

2.29E+00

1.92E+03

3.76E+03

2.02E+01

2.36E+00

1.97E+03

3.87E+03

2.06E+01

2.43E+00

2.01E+03

3.98E+03

2.11E+01

2.50E+00

2.05E+03

4.09E+03

2.15E+01

2.58E+00

2.10E+03

4.21E+03

2.20E+01

2.65E+00

2.15E+03

4.33E+03

2.25E+01

2.73E+00

2.19E+03

4.45E+03

2.30E+01

2.82E+00

2.24E+03

4.58E+03

2.35E+01

2.90E+00

2.29E+03

4.71E+03

2.40E+01

2.99E+00

2.34E+03

4.85E+03

2.46E+01

3.08E+00

2.40E+03

4.98E+03

2.51E+01

3.17E+00

2.45E+03

5.13E+03

2.57E+01

3.26E+00

2.51E+03

5.27E+03

2.63E+01

3.36E+00

2.56E+03

5.42E+03

2.69E+01

Non-gestational 5-year Average

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden
(ng/kg)

Blood
(ng/kg)

3.46E+00

2.62E+03

5.58E+03

2.75E+01

3.57E+00

2.68E+03

5.74E+03

2.81E+01

3.67E+00

2.74E+03

5.90E+03

2.87E+01

3.78E+00

2.80E+03

6.07E+03

2.94E+01

3.90E+00

2.87E+03

6.25E+03

3.01E+01

4.01E+00

2.93E+03

6.42E+03

3.07E+01

4.13E+00

3.00E+03

6.61E+03

3.15E+01

4.26E+00

3.07E+03

6.80E+03

3.22E+01

4.39E+00

3.14E+03

6.99E+03

3.29E+01

4.52E+00

3.22E+03

7.20E+03

3.37E+01

4.65E+00

3.29E+03

7.40E+03

3.45E+01

4.79E+00

3.37E+03

7.62E+03

3.53E+01

4.94E+00

3.45E+03

7.83E+03

3.61E+01

5.08E+00

3.53E+03

8.06E+03

3.69E+01

5.24E+00

3.61E+03

8.29E+03

3.78E+01

5.39E+00

3.69E+03

8.53E+03

3.87E+01

5.56E+00

3.78E+03

8.78E+03

3.96E+01

5.72E+00

3.87E+03

9.03E+03

4.06E+01

5.89E+00

3.96E+03

9.29E+03

4.15E+01

6.07E+00

4.06E+03

9.56E+03

4.25E+01

6.25E+00

4.15E+03

9.84E+03

4.35E+01

6.44E+00

4.25E+03

1.01E+04

4.46E+01

6.63E+00

4.36E+03

1.04E+04

4.56E+01

6.83E+00

4.46E+03

1.07E+04

4.67E+01

7.04E+00

4.57E+03

1.10E+04

4.79E+01

7.25E+00

4.68E+03

1.13E+04

4.90E+01

7.47E+00

4.79E+03

1.17E+04

5.02E+01

7.69E+00

4.91E+03

1.20E+04

5.15E+01

7.92E+00

5.03E+03

1.24E+04

5.27E+01

8.16E+00

5.15E+03

1.27E+04

5.40E+01

8.40E+00

5.28E+03

1.31E+04

5.53E+01

8.66E+00

5.41E+03

1.35E+04

5.67E+01

8.92E+00

5.54E+03

1.39E+04

5.81E+01

9.18E+00

5.68E+03

1.43E+04

5.95E+01

9.46E+00

5.82E+03

1.47E+04

6.10E+01

9.74E+00

5.97E+03

1.51E+04

6.25E+01

1.00E+01

6.10E+03

1.55E+04

6.39E+01

1.00E+01

6.12E+03

1.56E+04

6.41E+01

1

Non-gestational 5-year Average

Intake

(ng/kg/
day)

Fat
(ng/kg)

Body
Burden
(ng/kg)

Blood
(ng/kg)

1.34E+01

7.77E+03

2.05E+04

8.15E+01

1.67E+01

9.43E+03

2.55E+04

9.88E+01

2.00E+01

1.11E+04

3.05E+04

1.16E+02

2.33E+01

1.27E+04

3.54E+04

1.33E+02

2.67E+01

1.43E+04

4.03E+04

1.50E+02

3.00E+01

1.60E+04

4.53E+04

1.67E+02

3.33E+01

1.76E+04

5.02E+04

1.84E+02

3.67E+01

1.92E+04

5.51E+04

2.01E+02

4.00E+01

2.08E+04

6.00E+04

2.18E+02

4.33E+01

2.24E+04

6.49E+04

2.35E+02

4.67E+01

2.40E+04

6.97E+04

2.52E+02

5.00E+01

2.57E+04

7.46E+04

2.69E+02

5.33E+01

2.73E+04

7.94E+04

2.86E+02

5.67E+01

2.89E+04

8.43E+04

3.03E+02

6.00E+01

3.05E+04

8.91E+04

3.19E+02

6.33E+01

3.21E+04

9.39E+04

3.36E+02

6.67E+01

3.37E+04

9.87E+04

3.53E+02

7.00E+01

3.53E+04

1.04E+05

3.70E+02

7.33E+01

3.69E+04

1.08E+05

3.87E+02

7.67E+01

3.85E+04

1.13E+05

4.04E+02

8.00E+01

4.01E+04

1.18E+05

4.20E+02

8.33E+01

4.17E+04

1.23E+05

4.37E+02

8.67E+01

4.33E+04

1.27E+05

4.54E+02

9.00E+01

4.49E+04

1.32E+05

4.71E+02

9.33E+01

4.65E+04

1.37E+05

4.88E+02

9.67E+01

4.81E+04

1.41E+05

5.04E+02

1.00E+02

4.97E+04

1.46E+05

5.21E+02

1.10E+02

5.45E+04

1.60E+05

5.72E+02

1.20E+02

5.94E+04

1.74E+05

6.22E+02


-------
C.4.3. Gestational

o



Gestational

Intake

Fat

Body Burden

Blood

(ng/kg/ day)

(ng/kg)

(ng/kg)

(ng/kg)

1.00E-09

2.81E-05

1.11E-05

2.96E-07

1.33E-09

3.74E-05

1.47E-05

3.94E-07

1.67E-09

4.68E-05

1.84E-05

4.92E-07

2.00E-09

5.61E-05

2.21E-05

5.91E-07

2.33E-09

6.55E-05

2.58E-05

6.89E-07

2.67E-09

7.48E-05

2.95E-05

7.88E-07

3.00E-09

8.42E-05

3.32E-05

8.86E-07

3.33E-09

9.35E-05

3.69E-05

9.84E-07

3.67E-09

1.03E-04

4.05E-05

1.08E-06

4.00E-09

1.12E-04

4.42E-05

1.18E-06

4.33E-09

1.22E-04

4.79E-05

1.28E-06

4.67E-09

1.31E-04

5.16E-05

1.38E-06

5.00E-09

1.40E-04

5.53E-05

1.48E-06

5.33E-09

1.50E-04

5.90E-05

1.57E-06

5.67E-09

1.59E-04

6.26E-05

1.67E-06

6.00E-09

1.68E-04

6.63E-05

1.77E-06

6.33E-09

1.78E-04

7.00E-05

1.87E-06

6.67E-09

1.87E-04

7.37E-05

1.97E-06

7.00E-09

1.96E-04

7.74E-05

2.07E-06

7.33E-09

2.06E-04

8.11E-05

2.16E-06

7.67E-09

2.15E-04

8.47E-05

2.26E-06

8.00E-09

2.24E-04

8.84E-05

2.36E-06

8.33E-09

2.34E-04

9.21E-05

2.46E-06

8.67E-09

2.43E-04

9.58E-05

2.56E-06

9.00E-09

2.52E-04

9.95E-05

2.66E-06

9.33E-09

2.62E-04

1.03E-04

2.75E-06

9.67E-09

2.71E-04

1.07E-04

2.85E-06

1.00E-08

2.80E-04

1.11E-04

2.95E-06

1.33E-08

3.73E-04

1.47E-04

3.93E-06

1.67E-08

4.66E-04

1.84E-04

4.91E-06

2.00E-08

5.59E-04

2.21E-04

5.89E-06

2.33E-08

6.52E-04

2.57E-04

6.87E-06

2.67E-08

7.46E-04

2.94E-04

7.85E-06

3.00E-08

8.39E-04

3.31E-04

8.83E-06

3.33E-08

9.32E-04

3.67E-04

9.81E-06

3.67E-08

1.02E-03

4.04E-04

1.08E-05

4.00E-08

1.12E-03

4.41E-04

1.18E-05

Gestational

Intake

Fat

Body Burden

Blood

(ng/kg/ day)

(ng/kg)

(ng/kg)

(ng/kg)

4.33E-08

1.21E-03

4.78E-04

1.27E-05

4.67E-08

1.30E-03

5.14E-04

1.37E-05

5.00E-08

1.40E-03

5.51E-04

1.47E-05

5.33E-08

1.49E-03

5.88E-04

1.57E-05

5.67E-08

1.58E-03

6.24E-04

1.67E-05

6.00E-08

1.67E-03

6.61E-04

1.76E-05

6.33E-08

1.77E-03

6.97E-04

1.86E-05

6.67E-08

1.86E-03

7.34E-04

1.96E-05

7.00E-08

1.95E-03

7.70E-04

2.05E-05

7.33E-08

2.04E-03

8.07E-04

2.15E-05

7.67E-08

2.14E-03

8.43E-04

2.25E-05

8.00E-08

2.23E-03

8.80E-04

2.35E-05

8.33E-08

2.32E-03

9.17E-04

2.44E-05

8.67E-08

2.41E-03

9.53E-04

2.54E-05

9.00E-08

2.51E-03

9.90E-04

2.64E-05

9.33E-08

2.60E-03

1.03E-03

2.74E-05

9.67E-08

2.69E-03

1.06E-03

2.83E-05

1.00E-07

2.79E-03

1.10E-03

2.93E-05

1.33E-07

3.70E-03

1.46E-03

3.90E-05

1.67E-07

4.62E-03

1.83E-03

4.86E-05

2.00E-07

5.54E-03

2.19E-03

5.83E-05

2.33E-07

6.46E-03

2.55E-03

6.80E-05

2.67E-07

7.37E-03

2.92E-03

7.76E-05

3.00E-07

8.29E-03

3.28E-03

8.73E-05

3.33E-07

9.21E-03

3.64E-03

9.69E-05

3.67E-07

1.01E-02

4.01E-03

1.07E-04

4.00E-07

1.10E-02

4.37E-03

1.16E-04

4.33E-07

1.20E-02

4.74E-03

1.26E-04

4.67E-07

1.29E-02

5.10E-03

1.36E-04

5.00E-07

1.38E-02

5.46E-03

1.45E-04

5.33E-07

1.47E-02

5.82E-03

1.55E-04

5.66E-07

1.56E-02

6.17E-03

1.64E-04

5.99E-07

1.65E-02

6.53E-03

1.73E-04

6.33E-07

1.74E-02

6.88E-03

1.83E-04

6.66E-07

1.83E-02

7.24E-03

1.92E-04

6.99E-07

1.92E-02

7.59E-03

2.02E-04

7.32E-07

2.01E-02

7.95E-03

2.11E-04

7.65E-07

2.09E-02

8.30E-03

2.20E-04

Gestational

Intake

Fat

Body Burden

Blood

(ng/kg/ day)

(ng/kg)

(ng/kg)

(ng/kg)

7.98E-07

2.18E-02

8.66E-03

2.30E-04

8.32E-07

2.27E-02

9.01E-03

2.39E-04

8.65E-07

2.36E-02

9.37E-03

2.49E-04

8.98E-07

2.45E-02

9.72E-03

2.58E-04

9.31E-07

2.54E-02

1.01E-02

2.67E-04

9.64E-07

2.63E-02

1.04E-02

2.77E-04

9.97E-07

2.72E-02

1.08E-02

2.86E-04

1.01E-06

2.76E-02

1.09E-02

2.90E-04

1.03E-06

2.80E-02

1.11E-02

2.95E-04

1.04E-06

2.84E-02

1.13E-02

2.99E-04

1.06E-06

2.88E-02

1.14E-02

3.03E-04

1.07E-06

2.93E-02

1.16E-02

3.08E-04

1.09E-06

2.97E-02

1.18E-02

3.12E-04

1.11E-06

3.01E-02

1.20E-02

3.17E-04

1.12E-06

3.06E-02

1.21E-02

3.22E-04

1.14E-06

3.10E-02

1.23E-02

3.26E-04

1.16E-06

3.15E-02

1.25E-02

3.31E-04

1.17E-06

3.19E-02

1.27E-02

3.36E-04

1.19E-06

3.24E-02

1.29E-02

3.41E-04

1.21E-06

3.29E-02

1.31E-02

3.46E-04

1.23E-06

3.34E-02

1.32E-02

3.51E-04

1.24E-06

3.38E-02

1.34E-02

3.56E-04

1.26E-06

3.43E-02

1.36E-02

3.61E-04

1.28E-06

3.48E-02

1.38E-02

3.67E-04

1.30E-06

3.54E-02

1.40E-02

3.72E-04

1.32E-06

3.59E-02

1.42E-02

3.77E-04

1.34E-06

3.64E-02

1.45E-02

3.83E-04

1.36E-06

3.69E-02

1.47E-02

3.89E-04

1.38E-06

3.75E-02

1.49E-02

3.94E-04

1.40E-06

3.80E-02

1.51E-02

4.00E-04

1.42E-06

3.86E-02

1.53E-02

4.06E-04

1.44E-06

3.92E-02

1.56E-02

4.12E-04

1.46E-06

3.98E-02

1.58E-02

4.18E-04

1.49E-06

4.03E-02

1.60E-02

4.25E-04

1.53E-06

4.15E-02

1.65E-02

4.37E-04

1.58E-06

4.27E-02

1.70E-02

4.50E-04

1.62E-06

4.40E-02

1.75E-02

4.63E-04

1.67E-06

4.53E-02

1.80E-02

4.76E-04


-------
o



Gestational

Intake

Fat

Body Burden

Blood

(ng/kg/ day)

(ng/kg)

(ng/kg)

(ng/kg)

1.72E-06

4.66E-02

1.85E-02

4.90E-04

1.77E-06

4.80E-02

1.91E-02

5.05E-04

1.83E-06

4.94E-02

1.96E-02

5.20E-04

1.88E-06

5.08E-02

2.02E-02

5.35E-04

1.94E-06

5.23E-02

2.08E-02

5.50E-04

2.00E-06

5.38E-02

2.14E-02

5.66E-04

2.06E-06

5.54E-02

2.21E-02

5.83E-04

2.12E-06

5.70E-02

2.27E-02

6.00E-04

2.18E-06

5.87E-02

2.34E-02

6.17E-04

2.25E-06

6.04E-02

2.41E-02

6.35E-04

2.32E-06

6.22E-02

2.48E-02

6.54E-04

2.39E-06

6.40E-02

2.55E-02

6.73E-04

2.46E-06

6.58E-02

2.62E-02

6.93E-04

2.53E-06

6.77E-02

2.70E-02

7.13E-04

2.61E-06

6.97E-02

2.78E-02

7.33E-04

2.68E-06

7.17E-02

2.86E-02

7.55E-04

2.76E-06

7.38E-02

2.94E-02

7.77E-04

2.85E-06

7.60E-02

3.03E-02

8.00E-04

2.93E-06

7.82E-02

3.12E-02

8.22E-04

3.02E-06

8.04E-02

3.21E-02

8.46E-04

3.11E-06

8.27E-02

3.30E-02

8.71E-04

3.21E-06

8.51E-02

3.40E-02

8.96E-04

3.30E-06

8.76E-02

3.50E-02

9.22E-04

3.40E-06

9.01E-02

3.60E-02

9.48E-04

3.50E-06

9.27E-02

3.71E-02

9.76E-04

3.61E-06

9.54E-02

3.81E-02

1.00E-03

3.72E-06

9.82E-02

3.93E-02

1.03E-03

3.83E-06

1.01E-01

4.04E-02

1.06E-03

3.94E-06

1.04E-01

4.16E-02

1.09E-03

4.06E-06

1.07E-01

4.28E-02

1.12E-03

4.18E-06

1.10E-01

4.40E-02

1.16E-03

4.31E-06

1.13E-01

4.53E-02

1.19E-03

4.44E-06

1.16E-01

4.66E-02

1.22E-03

4.57E-06

1.20E-01

4.79E-02

1.26E-03

4.71E-06

1.23E-01

4.93E-02

1.30E-03

4.85E-06

1.27E-01

5.08E-02

1.33E-03

4.99E-06

1.30E-01

5.22E-02

1.37E-03

5.14E-06

1.34E-01

5.37E-02

1.41E-03

Gestational

Intake

Fat

Body Burden

Blood

(ng/kg/ day)

(ng/kg)

(ng/kg)

(ng/kg)

5.30E-06

1.38E-01

5.53E-02

1.45E-03

5.46E-06

1.42E-01

5.69E-02

1.49E-03

5.62E-06

1.46E-01

5.85E-02

1.53E-03

5.79E-06

1.50E-01

6.02E-02

1.58E-03

5.96E-06

1.54E-01

6.19E-02

1.62E-03

6.14E-06

1.59E-01

6.37E-02

1.67E-03

6.33E-06

1.63E-01

6.55E-02

1.72E-03

6.52E-06

1.68E-01

6.74E-02

1.76E-03

6.71E-06

1.72E-01

6.93E-02

1.81E-03

6.91E-06

1.77E-01

7.13E-02

1.86E-03

7.12E-06

1.82E-01

7.33E-02

1.92E-03

7.33E-06

1.87E-01

7.54E-02

1.97E-03

7.55E-06

1.93E-01

7.75E-02

2.03E-03

7.78E-06

1.98E-01

7.97E-02

2.08E-03

8.01E-06

2.03E-01

8.20E-02

2.14E-03

8.25E-06

2.09E-01

8.43E-02

2.20E-03

8.50E-06

2.15E-01

8.67E-02

2.26E-03

8.76E-06

2.21E-01

8.92E-02

2.33E-03

9.02E-06

2.27E-01

9.17E-02

2.39E-03

9.29E-06

2.34E-01

9.43E-02

2.46E-03

9.57E-06

2.40E-01

9.70E-02

2.53E-03

9.86E-06

2.47E-01

9.97E-02

2.60E-03

1.02E-05

2.54E-01

1.03E-01

2.67E-03

1.05E-05

2.61E-01

1.05E-01

2.74E-03

1.08E-05

2.68E-01

1.08E-01

2.82E-03

1.11E-05

2.75E-01

1.11E-01

2.90E-03

1.14E-05

2.83E-01

1.15E-01

2.98E-03

1.18E-05

2.91E-01

1.18E-01

3.06E-03

1.21E-05

2.99E-01

1.21E-01

3.14E-03

1.25E-05

3.07E-01

1.25E-01

3.23E-03

1.29E-05

3.16E-01

1.28E-01

3.32E-03

1.32E-05

3.24E-01

1.32E-01

3.41E-03

1.36E-05

3.33E-01

1.35E-01

3.51E-03

1.41E-05

3.42E-01

1.39E-01

3.60E-03

1.45E-05

3.52E-01

1.43E-01

3.70E-03

1.49E-05

3.61E-01

1.47E-01

3.80E-03

1.54E-05

3.71E-01

1.51E-01

3.90E-03

1.58E-05

3.81E-01

1.55E-01

4.01E-03

Gestational

Intake

Fat

Body Burden

Blood

(ng/kg/ day)

(ng/kg)

(ng/kg)

(ng/kg)

1.63E-05

3.92E-01

1.60E-01

4.12E-03

1.68E-05

4.03E-01

1.64E-01

4.23E-03

1.73E-05

4.13E-01

1.69E-01

4.35E-03

1.78E-05

4.25E-01

1.73E-01

4.47E-03

1.83E-05

4.36E-01

1.78E-01

4.59E-03

1.89E-05

4.48E-01

1.83E-01

4.71E-03

1.95E-05

4.60E-01

1.88E-01

4.84E-03

2.00E-05

4.72E-01

1.93E-01

4.97E-03

2.06E-05

4.85E-01

1.98E-01

5.10E-03

2.13E-05

4.98E-01

2.04E-01

5.24E-03

2.19E-05

5.12E-01

2.10E-01

5.38E-03

2.25E-05

5.25E-01

2.15E-01

5.53E-03

2.32E-05

5.40E-01

2.21E-01

5.68E-03

2.39E-05

5.54E-01

2.27E-01

5.83E-03

2.46E-05

5.69E-01

2.34E-01

5.98E-03

2.54E-05

5.84E-01

2.40E-01

6.14E-03

2.61E-05

6.00E-01

2.47E-01

6.31E-03

2.69E-05

6.16E-01

2.53E-01

6.48E-03

2.77E-05

6.32E-01

2.60E-01

6.65E-03

2.86E-05

6.49E-01

2.67E-01

6.82E-03

2.94E-05

6.66E-01

2.75E-01

7.01E-03

3.03E-05

6.84E-01

2.82E-01

7.19E-03

3.12E-05

7.02E-01

2.90E-01

7.38E-03

3.21E-05

7.20E-01

2.98E-01

7.58E-03

3.31E-05

7.42E-01

3.07E-01

7.80E-03

3.41E-05

7.62E-01

3.15E-01

8.01E-03

3.51E-05

7.82E-01

3.24E-01

8.22E-03

3.62E-05

8.03E-01

3.33E-01

8.44E-03

3.73E-05

8.24E-01

3.42E-01

8.68E-03

3.84E-05

8.45E-01

3.51E-01

8.89E-03

3.95E-05

8.68E-01

3.61E-01

9.12E-03

4.07E-05

8.88E-01

3.69E-01

9.34E-03

4.19E-05

9.11E-01

3.79E-01

9.59E-03

4.32E-05

9.35E-01

3.89E-01

9.83E-03

4.45E-05

9.59E-01

4.00E-01

1.01E-02

4.58E-05

9.83E-01

4.10E-01

1.03E-02

4.72E-05

1.01E+00

4.21E-01

1.06E-02

4.86E-05

1.04E+00

4.33E-01

1.09E-02


-------


Gestational

Intake

Fat

Body Burden

Blood

(ng/kg/ day)

(ng/kg)

(ng/kg)

(ng/kg)

5.01E-05

1.06E+00

4.44E-01

1.12E-02

5.16E-05

1.09E+00

4.56E-01

1.14E-02

5.31E-05

1.12E+00

4.68E-01

1.17E-02

5.47E-05

1.15E+00

4.81E-01

1.21E-02

5.64E-05

1.18E+00

4.93E-01

1.24E-02

5.81E-05

1.21E+00

5.06E-01

1.27E-02

5.98E-05

1.24E+00

5.20E-01

1.30E-02

6.16E-05

1.27E+00

5.34E-01

1.33E-02

6.34E-05

1.30E+00

5.48E-01

1.37E-02

6.54E-05

1.33E+00

5.62E-01

1.40E-02

6.73E-05

1.37E+00

5.77E-01

1.44E-02

6.93E-05

1.40E+00

5.92E-01

1.47E-02

7.14E-05

1.44E+00

6.08E-01

1.51E-02

7.36E-05

1.47E+00

6.24E-01

1.55E-02

7.58E-05

1.51E+00

6.40E-01

1.59E-02

7.80E-05

1.55E+00

6.57E-01

1.63E-02

8.04E-05

1.59E+00

6.74E-01

1.67E-02

8.28E-05

1.63E+00

6.92E-01

1.71E-02

8.53E-05

1.67E+00

7.10E-01

1.75E-02

8.78E-05

1.71E+00

7.28E-01

1.79E-02

9.05E-05

1.75E+00

7.47E-01

1.84E-02

9.32E-05

1.79E+00

7.66E-01

1.88E-02

9.60E-05

1.84E+00

7.86E-01

1.93E-02

9.89E-05

1.88E+00

8.07E-01

1.98E-02

1.02E-04

1.93E+00

8.28E-01

2.03E-02

1.05E-04

1.98E+00

8.49E-01

2.08E-02

1.08E-04

2.03E+00

8.71E-01

2.13E-02

1.11E-04

2.08E+00

8.93E-01

2.18E-02

1.15E-04

2.13E+00

9.16E-01

2.24E-02

1.18E-04

2.18E+00

9.39E-01

2.29E-02

1.22E-04

2.23E+00

9.63E-01

2.34E-02

1.25E-04

2.28E+00

9.87E-01

2.40E-02

1.29E-04

2.34E+00

1.01E+00

2.46E-02

1.33E-04

2.40E+00

1.04E+00

2.52E-02

1.37E-04

2.45E+00

1.06E+00

2.58E-02

1.41E-04

2.51E+00

1.09E+00

2.64E-02

1.45E-04

2.58E+00

1.12E+00

2.72E-02

1.50E-04

2.63E+00

1.15E+00

2.77E-02

Gestational

Intake

Fat

Body Burden

Blood

(ng/kg/ day)

(ng/kg)

(ng/kg)

(ng/kg)

1.54E-04

2.70E+00

1.18E+00

2.83E-02

1.59E-04

2.78E+00

1.21E+00

2.92E-02

1.63E-04

2.84E+00

1.24E+00

2.99E-02

1.68E-04

2.89E+00

1.27E+00

3.04E-02

1.73E-04

2.96E+00

1.30E+00

3.11E-02

1.79E-04

3.03E+00

1.33E+00

3.18E-02

1.84E-04

3.10E+00

1.36E+00

3.26E-02

1.89E-04

3.17E+00

1.40E+00

3.33E-02

1.95E-04

3.25E+00

1.43E+00

3.41E-02

2.01E-04

3.32E+00

1.47E+00

3.49E-02

2.07E-04

3.43E+00

1.52E+00

3.61E-02

2.13E-04

3.51E+00

1.56E+00

3.69E-02

2.20E-04

3.57E+00

1.59E+00

3.75E-02

2.26E-04

3.67E+00

1.63E+00

3.85E-02

2.33E-04

3.77E+00

1.68E+00

3.96E-02

2.40E-04

3.86E+00

1.72E+00

4.05E-02

2.47E-04

3.95E+00

1.76E+00

4.15E-02

2.55E-04

4.04E+00

1.81E+00

4.24E-02

2.62E-04

4.13E+00

1.85E+00

4.34E-02

2.70E-04

4.22E+00

1.90E+00

4.44E-02

2.78E-04

4.32E+00

1.94E+00

4.54E-02

2.86E-04

4.42E+00

1.99E+00

4.64E-02

2.95E-04

4.52E+00

2.04E+00

4.75E-02

3.04E-04

4.62E+00

2.09E+00

4.86E-02

3.13E-04

4.73E+00

2.14E+00

4.97E-02

3.22E-04

4.84E+00

2.20E+00

5.08E-02

3.32E-04

4.95E+00

2.25E+00

5.20E-02

3.42E-04

5.06E+00

2.30E+00

5.31E-02

3.52E-04

5.17E+00

2.36E+00

5.43E-02

3.63E-04

5.29E+00

2.42E+00

5.56E-02

3.74E-04

5.41E+00

2.48E+00

5.68E-02

3.85E-04

5.53E+00

2.54E+00

5.81E-02

3.97E-04

5.65E+00

2.60E+00

5.94E-02

4.08E-04

5.78E+00

2.66E+00

6.07E-02

4.21E-04

5.91E+00

2.73E+00

6.20E-02

4.33E-04

6.04E+00

2.79E+00

6.34E-02

4.46E-04

6.17E+00

2.86E+00

6.48E-02

4.60E-04

6.31E+00

2.93E+00

6.63E-02

Gestational

Intake

Fat

Body Burden

Blood

(ng/kg/ day)

(ng/kg)

(ng/kg)

(ng/kg)

4.74E-04

6.45E+00

3.00E+00

6.77E-02

4.88E-04

6.59E+00

3.07E+00

6.92E-02

5.02E-04

6.74E+00

3.15E+00

7.07E-02

5.17E-04

6.88E+00

3.22E+00

7.23E-02

5.33E-04

7.03E+00

3.30E+00

7.39E-02

5.49E-04

7.19E+00

3.38E+00

7.55E-02

5.65E-04

7.34E+00

3.46E+00

7.71E-02

5.82E-04

7.50E+00

3.54E+00

7.88E-02

6.00E-04

7.67E+00

3.63E+00

8.05E-02

6.18E-04

7.83E+00

3.71E+00

8.22E-02

6.36E-04

8.00E+00

3.80E+00

8.40E-02

6.55E-04

8.17E+00

3.89E+00

8.58E-02

6.75E-04

8.35E+00

3.98E+00

8.77E-02

6.95E-04

8.53E+00

4.08E+00

8.95E-02

7.16E-04

8.70E+00

4.17E+00

9.14E-02

7.38E-04

8.89E+00

4.27E+00

9.33E-02

7.60E-04

9.08E+00

4.37E+00

9.53E-02

7.83E-04

9.27E+00

4.47E+00

9.74E-02

8.06E-04

9.47E+00

4.58E+00

9.94E-02

8.30E-04

9.67E+00

4.69E+00

1.02E-01

8.55E-04

9.88E+00

4.80E+00

1.04E-01

8.81E-04

1.01E+01

4.91E+00

1.06E-01

9.07E-04

1.03E+01

5.03E+00

1.08E-01

9.21E-04

1.04E+01

5.09E+00

1.09E-01

9.35E-04

1.05E+01

5.14E+00

1.10E-01

9.49E-04

1.26E+01

6.31E+00

1.32E-01

1.37E-03

1.38E+01

6.99E+00

1.45E-01

1.39E-03

1.40E+01

7.07E+00

1.46E-01

1.41E-03

1.41E+01

7.15E+00

1.48E-01

1.43E-03

1.42E+01

7.23E+00

1.49E-01

1.46E-03

1.44E+01

7.31E+00

1.51E-01

1.48E-03

1.45E+01

7.39E+00

1.52E-01

1.50E-03

1.46E+01

7.47E+00

1.54E-01

1.52E-03

1.48E+01

7.55E+00

1.55E-01

1.54E-03

1.49E+01

7.64E+00

1.57E-01

1.57E-03

1.51E+01

7.73E+00

1.58E-01

1.59E-03

1.52E+01

7.82E+00

1.60E-01

1.61E-03

1.54E+01

7.91E+00

1.62E-01


-------


Gestational

Intake

Fat

Body Burden

Blood

(ng/kg/ day)

(ng/kg)

(ng/kg)

(ng/kg)

1.64E-03

1.56E+01

8.00E+00

1.63E-01

1.69E-03

1.59E+01

8.19E+00

1.67E-01

1.71E-03

1.60E+01

8.28E+00

1.68E-01

1.74E-03

1.62E+01

8.38E+00

1.70E-01

1.76E-03

1.64E+01

8.47E+00

1.72E-01

1.79E-03

1.65E+01

8.57E+00

1.73E-01

1.82E-03

1.67E+01

8.67E+00

1.75E-01

1.84E-03

1.69E+01

8.77E+00

1.77E-01

1.87E-03

1.74E+01

9.10E+00

1.83E-01

2.34E-03

1.98E+01

1.06E+01

2.08E-01

2.41E-03

2.02E+01

1.08E+01

2.12E-01

2.48E-03

2.06E+01

1.11E+01

2.16E-01

2.55E-03

2.10E+01

1.13E+01

2.21E-01

2.63E-03

2.14E+01

1.16E+01

2.25E-01

2.71E-03

2.19E+01

1.18E+01

2.30E-01

2.79E-03

2.23E+01

1.21E+01

2.34E-01

2.87E-03

2.28E+01

1.24E+01

2.39E-01

2.96E-03

2.32E+01

1.27E+01

2.44E-01

3.05E-03

2.37E+01

1.30E+01

2.48E-01

3.14E-03

2.41E+01

1.33E+01

2.53E-01

3.23E-03

2.46E+01

1.36E+01

2.58E-01

3.33E-03

2.51E+01

1.39E+01

2.63E-01

3.43E-03

2.56E+01

1.42E+01

2.69E-01

3.53E-03

2.61E+01

1.46E+01

2.74E-01

3.64E-03

2.66E+01

1.49E+01

2.79E-01

4.22E-03

2.83E+01

1.60E+01

2.96E-01

4.35E-03

2.88E+01

1.63E+01

3.02E-01

4.48E-03

2.93E+01

1.67E+01

3.08E-01

4.61E-03

2.99E+01

1.71E+01

3.14E-01

4.75E-03

3.05E+01

1.75E+01

3.20E-01

4.89E-03

3.11E+01

1.79E+01

3.26E-01

5.04E-03

3.30E+01

1.92E+01

3.46E-01

5.19E-03

3.41E+01

2.00E+01

3.58E-01

5.35E-03

3.49E+01

2.05E+01

3.66E-01

5.51E-03

3.55E+01

2.10E+01

3.73E-01

5.67E-03

3.62E+01

2.14E+01

3.80E-01

5.84E-03

3.69E+01

2.19E+01

3.87E-01

5.93E-03

3.73E+01

2.22E+01

3.91E-01

Gestational

Intake

Fat

Body Burden

Blood

(ng/kg/ day)

(ng/kg)

(ng/kg)

(ng/kg)

6.02E-03

3.77E+01

2.25E+01

3.95E-01

6.20E-03

3.84E+01

2.30E+01

4.03E-01

6.38E-03

3.92E+01

2.36E+01

4.12E-01

6.57E-03

4.00E+01

2.42E+01

4.20E-01

6.77E-03

4.08E+01

2.48E+01

4.28E-01

6.98E-03

4.16E+01

2.54E+01

4.37E-01

7.18E-03

4.25E+01

2.60E+01

4.45E-01

7.40E-03

4.33E+01

2.66E+01

4.54E-01

7.51E-03

4.37E+01

2.69E+01

4.58E-01

8.33E-03

4.46E+01

2.76E+01

4.68E-01

8.58E-03

4.66E+01

2.91E+01

4.89E-01

8.71E-03

4.74E+01

2.97E+01

4.97E-01

8.84E-03

4.79E+01

3.00E+01

5.02E-01

9.10E-03

4.86E+01

3.06E+01

5.10E-01

9.37E-03

4.95E+01

3.13E+01

5.19E-01

9.66E-03

5.07E+01

3.22E+01

5.32E-01

9.94E-03

5.17E+01

3.30E+01

5.42E-01

1.02E-02

5.27E+01

3.38E+01

5.53E-01

1.06E-02

5.37E+01

3.46E+01

5.63E-01

1.09E-02

5.46E+01

3.53E+01

5.73E-01

1.12E-02

5.58E+01

3.63E+01

5.85E-01

1.15E-02

5.67E+01

3.69E+01

5.94E-01

1.19E-02

5.74E+01

3.75E+01

6.02E-01

1.22E-02

5.85E+01

3.84E+01

6.13E-01

1.26E-02

5.96E+01

3.93E+01

6.25E-01

1.30E-02

6.19E+01

4.12E+01

6.49E-01

1.34E-02

6.32E+01

4.23E+01

6.63E-01

1.38E-02

6.45E+01

4.33E+01

6.76E-01

1.42E-02

6.57E+01

4.44E+01

6.89E-01

1.46E-02

6.64E+01

4.49E+01

6.96E-01

1.50E-02

6.78E+01

4.61E+01

7.11E-01

1.55E-02

6.83E+01

4.66E+01

7.16E-01

1.60E-02

6.96E+01

4.76E+01

7.29E-01

1.64E-02

7.09E+01

4.88E+01

7.43E-01

1.69E-02

7.26E+01

5.02E+01

7.61E-01

1.74E-02

7.40E+01

5.14E+01

7.76E-01

1.80E-02

7.54E+01

5.27E+01

7.90E-01

1.85E-02

7.68E+01

5.39E+01

8.06E-01

Gestational

Intake

Fat

Body Burden

Blood

(ng/kg/ day)

(ng/kg)

(ng/kg)

(ng/kg)

1.91E-02

7.83E+01

5.52E+01

8.21E-01

1.96E-02

7.98E+01

5.66E+01

8.37E-01

2.02E-02

8.13E+01

5.79E+01

8.53E-01

2.08E-02

8.29E+01

5.94E+01

8.69E-01

2.14E-02

8.45E+01

6.08E+01

8.86E-01

2.21E-02

8.61E+01

6.23E+01

9.03E-01

2.28E-02

8.78E+01

6.38E+01

9.20E-01

2.34E-02

8.95E+01

6.54E+01

9.38E-01

2.41E-02

9.12E+01

6.70E+01

9.56E-01

2.49E-02

9.29E+01

6.86E+01

9.75E-01

2.56E-02

9.47E+01

7.03E+01

9.93E-01

2.64E-02

9.65E+01

7.20E+01

1.01E+00

2.72E-02

9.84E+01

7.37E+01

1.03E+00

2.80E-02

1.00E+02

7.55E+01

1.05E+00

2.88E-02

1.02E+02

7.74E+01

1.07E+00

2.97E-02

1.04E+02

7.93E+01

1.09E+00

3.06E-02

1.07E+02

8.20E+01

1.12E+00

3.15E-02

1.09E+02

8.38E+01

1.14E+00

3.24E-02

1.11E+02

8.57E+01

1.16E+00

3.34E-02

1.13E+02

8.76E+01

1.18E+00

3.44E-02

1.15E+02

8.96E+01

1.20E+00

3.54E-02

1.16E+02

9.15E+01

1.22E+00

3.65E-02

1.18E+02

9.35E+01

1.24E+00

3.76E-02

1.21E+02

9.61E+01

1.27E+00

3.87E-02

1.23E+02

9.84E+01

1.29E+00

3.99E-02

1.26E+02

1.01E+02

1.32E+00

4.11E-02

1.28E+02

1.03E+02

1.34E+00

4.23E-02

1.31E+02

1.06E+02

1.37E+00

4.36E-02

1.34E+02

1.09E+02

1.40E+00

4.49E-02

1.36E+02

1.12E+02

1.43E+00

4.63E-02

1.39E+02

1.15E+02

1.45E+00

4.76E-02

1.42E+02

1.18E+02

1.48E+00

4.91E-02

1.44E+02

1.21E+02

1.51E+00

5.05E-02

1.47E+02

1.24E+02

1.54E+00

5.21E-02

1.50E+02

1.27E+02

1.57E+00

5.36E-02

1.52E+02

1.30E+02

1.60E+00

5.52E-02

1.55E+02

1.33E+02

1.63E+00

5.69E-02

1.59E+02

1.37E+02

1.66E+00


-------


Gestational

Intake

Fat

Body Burden

Blood

(ng/kg/ day)

(ng/kg)

(ng/kg)

(ng/kg)

5.86E-02

1.62E+02

1.40E+02

1.69E+00

6.03E-02

1.64E+02

1.43E+02

1.72E+00

6.22E-02

1.67E+02

1.46E+02

1.75E+00

6.40E-02

1.70E+02

1.50E+02

1.79E+00

6.59E-02

1.74E+02

1.54E+02

1.82E+00

6.79E-02

1.77E+02

1.58E+02

1.86E+00

7.00E-02

1.80E+02

1.62E+02

1.89E+00

7.21E-02

1.84E+02

1.66E+02

1.93E+00

7.42E-02

1.87E+02

1.70E+02

1.96E+00

7.64E-02

1.91E+02

1.75E+02

2.00E+00

7.87E-02

1.95E+02

1.79E+02

2.05E+00

8.11E-02

1.99E+02

1.84E+02

2.09E+00

8.35E-02

2.03E+02

1.89E+02

2.13E+00

8.60E-02

2.07E+02

1.93E+02

2.17E+00

8.86E-02

2.11E+02

1.98E+02

2.21E+00

9.13E-02

2.15E+02

2.03E+02

2.25E+00

9.40E-02

2.19E+02

2.08E+02

2.29E+00

9.68E-02

2.23E+02

2.14E+02

2.34E+00

9.97E-02

2.28E+02

2.20E+02

2.39E+00

1.03E-01

2.32E+02

2.25E+02

2.43E+00

1.06E-01

2.36E+02

2.31E+02

2.48E+00

1.09E-01

2.40E+02

2.36E+02

2.52E+00

1.12E-01

2.45E+02

2.42E+02

2.57E+00

1.16E-01

2.50E+02

2.49E+02

2.62E+00

1.19E-01

2.55E+02

2.55E+02

2.67E+00

1.23E-01

2.60E+02

2.62E+02

2.72E+00

1.26E-01

2.65E+02

2.69E+02

2.78E+00

1.30E-01

2.70E+02

2.76E+02

2.83E+00

1.34E-01

2.75E+02

2.83E+02

2.89E+00

1.38E-01

2.81E+02

2.91E+02

2.95E+00

1.42E-01

2.87E+02

2.99E+02

3.00E+00

1.46E-01

2.92E+02

3.06E+02

3.06E+00

1.51E-01

2.97E+02

3.14E+02

3.12E+00

1.55E-01

3.03E+02

3.22E+02

3.18E+00

1.60E-01

3.09E+02

3.30E+02

3.24E+00

1.65E-01

3.15E+02

3.39E+02

3.30E+00

1.70E-01

3.21E+02

3.48E+02

3.37E+00

1.75E-01

3.27E+02

3.57E+02

3.43E+00

Gestational

Intake

Fat

Body Burden

Blood

(ng/kg/ day)

(ng/kg)

(ng/kg)

(ng/kg)

1.80E-01

3.34E+02

3.67E+02

3.50E+00

1.86E-01

3.40E+02

3.76E+02

3.57E+00

1.91E-01

3.47E+02

3.86E+02

3.64E+00

1.97E-01

3.54E+02

3.96E+02

3.71E+00

2.03E-01

3.60E+02

4.06E+02

3.78E+00

2.09E-01

3.68E+02

4.17E+02

3.85E+00

2.15E-01

3.75E+02

4.28E+02

3.93E+00

2.22E-01

3.82E+02

4.40E+02

4.01E+00

2.28E-01

3.90E+02

4.52E+02

4.09E+00

2.35E-01

3.98E+02

4.64E+02

4.17E+00

2.42E-01

4.05E+02

4.76E+02

4.25E+00

2.49E-01

4.13E+02

4.89E+02

4.33E+00

2.57E-01

4.22E+02

5.02E+02

4.42E+00

2.65E-01

4.30E+02

5.15E+02

4.51E+00

2.72E-01

4.38E+02

5.29E+02

4.60E+00

2.81E-01

4.47E+02

5.42E+02

4.68E+00

2.89E-01

4.55E+02

5.56E+02

4.77E+00

2.98E-01

4.64E+02

5.71E+02

4.87E+00

3.07E-01

4.73E+02

5.86E+02

4.96E+00

3.16E-01

4.83E+02

6.03E+02

5.06E+00

3.25E-01

4.92E+02

6.19E+02

5.16E+00

3.35E-01

5.02E+02

6.35E+02

5.26E+00

3.45E-01

5.13E+02

6.53E+02

5.37E+00

3.56E-01

5.23E+02

6.70E+02

5.48E+00

3.66E-01

5.33E+02

6.88E+02

5.59E+00

3.77E-01

5.44E+02

7.07E+02

5.70E+00

3.89E-01

5.55E+02

7.26E+02

5.81E+00

4.00E-01

5.66E+02

7.46E+02

5.93E+00

4.12E-01

5.77E+02

7.66E+02

6.05E+00

4.25E-01

5.88E+02

7.86E+02

6.17E+00

4.37E-01

6.00E+02

8.08E+02

6.29E+00

4.50E-01

6.12E+02

8.30E+02

6.42E+00

4.64E-01

6.24E+02

8.52E+02

6.54E+00

4.92E-01

6.50E+02

8.99E+02

6.81E+00

5.07E-01

6.63E+02

9.23E+02

6.95E+00

5.22E-01

6.76E+02

9.49E+02

7.09E+00

5.54E-01

7.04E+02

1.00E+03

7.38E+00

5.71E-01

7.18E+02

1.03E+03

7.53E+00

Gestational

Intake

Fat

Body Burden

Blood

(ng/kg/ day)

(ng/kg)

(ng/kg)

(ng/kg)

5.88E-01

7.32E+02

1.06E+03

7.68E+00

6.05E-01

7.47E+02

1.08E+03

7.83E+00

6.23E-01

7.62E+02

1.11E+03

7.99E+00

6.61E-01

7.94E+02

1.18E+03

8.32E+00

6.81E-01

8.10E+02

1.21E+03

8.49E+00

7.02E-01

8.27E+02

1.24E+03

8.67E+00

7.23E-01

8.43E+02

1.28E+03

8.84E+00

7.44E-01

8.61E+02

1.31E+03

9.02E+00

7.67E-01

8.78E+02

1.35E+03

9.21E+00

7.90E-01

8.96E+02

1.38E+03

9.40E+00

8.13E-01

9.15E+02

1.42E+03

9.59E+00

8.38E-01

9.33E+02

1.46E+03

9.78E+00

8.63E-01

9.53E+02

1.50E+03

9.99E+00

9.16E-01

9.93E+02

1.59E+03

1.04E+01

9.43E-01

1.01E+03

1.63E+03

1.06E+01

9.71E-01

1.03E+03

1.68E+03

1.08E+01

1.00E+00

1.06E+03

1.72E+03

1.11E+01

1.06E+00

1.10E+03

1.82E+03

1.15E+01

1.09E+00

1.12E+03

1.87E+03

1.18E+01

1.13E+00

1.15E+03

1.92E+03

1.20E+01

1.16E+00

1.17E+03

1.98E+03

1.23E+01

1.19E+00

1.20E+03

2.03E+03

1.25E+01

1.23E+00

1.22E+03

2.09E+03

1.28E+01

1.27E+00

1.25E+03

2.15E+03

1.31E+01

1.31E+00

1.27E+03

2.21E+03

1.33E+01

1.34E+00

1.30E+03

2.27E+03

1.36E+01

1.38E+00

1.33E+03

2.33E+03

1.39E+01

1.43E+00

1.35E+03

2.40E+03

1.42E+01

1.47E+00

1.38E+03

2.46E+03

1.45E+01

1.51E+00

1.41E+03

2.53E+03

1.48E+01

1.56E+00

1.44E+03

2.60E+03

1.51E+01

1.61E+00

1.47E+03

2.68E+03

1.55E+01

1.65E+00

1.51E+03

2.75E+03

1.58E+01

1.70E+00

1.54E+03

2.83E+03

1.61E+01

1.75E+00

1.57E+03

2.91E+03

1.65E+01

1.81E+00

1.61E+03

2.99E+03

1.68E+01

1.86E+00

1.64E+03

3.08E+03

1.72E+01

1.92E+00

1.68E+03

3.16E+03

1.76E+01


-------


Gestational

Intake

Fat

Body Burden

Blood

(ng/kg/ day)

(ng/kg)

(ng/kg)

(ng/kg)

1.97E+00

1.71E+03

3.25E+03

1.79E+01

2.03E+00

1.75E+03

3.34E+03

1.83E+01

2.09E+00

1.79E+03

3.44E+03

1.87E+01

2.16E+00

1.83E+03

3.54E+03

1.91E+01

2.22E+00

1.87E+03

3.64E+03

1.96E+01

2.29E+00

1.91E+03

3.74E+03

2.00E+01

2.36E+00

1.95E+03

3.85E+03

2.04E+01

2.43E+00

1.99E+03

3.95E+03

2.09E+01

2.50E+00

2.04E+03

4.07E+03

2.13E+01

2.58E+00

2.08E+03

4.18E+03

2.18E+01

2.65E+00

2.13E+03

4.30E+03

2.23E+01

2.73E+00

2.17E+03

4.42E+03

2.28E+01

2.82E+00

2.22E+03

4.55E+03

2.33E+01

2.90E+00

2.27E+03

4.68E+03

2.38E+01

2.99E+00

2.32E+03

4.81E+03

2.44E+01

3.08E+00

2.38E+03

4.95E+03

2.49E+01

3.17E+00

2.43E+03

5.09E+03

2.55E+01

3.26E+00

2.48E+03

5.24E+03

2.60E+01

3.36E+00

2.54E+03

5.39E+03

2.66E+01

3.46E+00

2.60E+03

5.54E+03

2.72E+01

3.57E+00

2.66E+03

5.70E+03

2.79E+01

3.67E+00

2.72E+03

5.86E+03

2.85E+01

3.78E+00

2.78E+03

6.03E+03

2.91E+01

3.90E+00

2.84E+03

6.20E+03

2.98E+01

4.01E+00

2.91E+03

6.38E+03

3.05E+01

4.13E+00

2.98E+03

6.56E+03

3.12E+01

4.26E+00

3.04E+03

6.75E+03

3.19E+01

4.39E+00

3.12E+03

6.95E+03

3.27E+01

4.52E+00

3.19E+03

7.15E+03

3.34E+01

4.65E+00

3.26E+03

7.35E+03

3.42E+01

4.79E+00

3.34E+03

7.56E+03

3.50E+01

4.94E+00

3.42E+03

7.78E+03

3.58E+01

5.08E+00

3.50E+03

8.01E+03

3.66E+01

5.24E+00

3.58E+03

8.24E+03

3.75E+01

5.39E+00

3.66E+03

8.47E+03

3.84E+01

5.56E+00

3.75E+03

8.72E+03

3.93E+01

5.72E+00

3.84E+03

8.97E+03

4.02E+01

5.89E+00

3.93E+03

9.23E+03

4.12E+01

Gestational

Intake

Fat

Body Burden

Blood

(ng/kg/ day)

(ng/kg)

(ng/kg)

(ng/kg)

6.07E+00

4.02E+03

9.50E+03

4.22E+01

6.25E+00

4.12E+03

9.77E+03

4.32E+01

6.44E+00

4.22E+03

1.01E+04

4.42E+01

6.63E+00

4.32E+03

1.03E+04

4.53E+01

6.83E+00

4.42E+03

1.06E+04

4.64E+01

7.04E+00

4.53E+03

1.10E+04

4.75E+01

7.25E+00

4.64E+03

1.13E+04

4.86E+01

7.47E+00

4.75E+03

1.16E+04

4.98E+01

7.69E+00

4.87E+03

1.19E+04

5.10E+01

7.92E+00

4.99E+03

1.23E+04

5.23E+01

8.16E+00

5.11E+03

1.26E+04

5.36E+01

8.40E+00

5.24E+03

1.30E+04

5.49E+01

8.66E+00

5.37E+03

1.34E+04

5.62E+01

8.92E+00

5.50E+03

1.38E+04

5.76E+01

9.18E+00

5.63E+03

1.42E+04

5.91E+01

9.46E+00

5.77E+03

1.46E+04

6.05E+01

9.74E+00

5.92E+03

1.50E+04

6.20E+01

1.00E+01

6.05E+03

1.54E+04

6.34E+01

1.00E+01

6.07E+03

1.54E+04

6.36E+01

1.34E+01

7.71E+03

2.04E+04

8.08E+01

1.67E+01

9.35E+03

2.53E+04

9.80E+01

2.00E+01

1.10E+04

3.02E+04

1.15E+02

2.33E+01

1.26E+04

3.52E+04

1.32E+02

2.67E+01

1.42E+04

4.01E+04

1.49E+02

3.00E+01

1.58E+04

4.50E+04

1.66E+02

3.33E+01

1.74E+04

4.98E+04

1.83E+02

3.67E+01

1.90E+04

5.47E+04

2.00E+02

4.00E+01

2.07E+04

5.96E+04

2.17E+02

4.33E+01

2.23E+04

6.44E+04

2.33E+02

4.67E+01

2.39E+04

6.93E+04

2.50E+02

5.00E+01

2.54E+04

7.41E+04

2.67E+02


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1	Murray, FJ; Smith, FA; Nitschke, KD; et al. (1979) Three-generation reproduction study of rats given 2,3,7,8-

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This document is a draft for review purposes only and does not constitute Agency policy.

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33	behavior of TCDD in female Sprague-Dawley Rats. Toxicol Appl Pharmacol 147:151-168.

34	Wang, X; Santostefano, MJ; Devito, MJ; et al. (2000) Extrapolation of a PBPK model for dioxins across dosage

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36	White, KL, Jr; Lysy, HH; McCay, JA; et al. (1986) Modulation of serum complement levels following exposure to

37	polychlorinated dibenzo-p-dioxins. Toxicol Appl Pharmacol 84:209-219.

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This document is a draft for review purposes only and does not constitute Agency policy.

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DRAFT

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May 2010
External Review Draft

APPENDIX D
Epidemiological Kinetic Modeling

NOTICE

THIS DOCUMENT IS AN EXTERNAL REVIEW DRAFT. It has not been formally released
by the U.S. Environmental Protection Agency and should not at this stage be construed to
represent Agency policy. It is being circulated for comment on its technical accuracy and policy
implications.

National Center for Environmental Assessment
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, OH


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CONTENTS—APPENDIX D: Epidemiological Kinetic Modeling

LIST OF TABLES	D-iii

APPENDIX D. EPIDEMIOLOGICAL KINETIC MODELING	D-1

D.l. BACCARELLIET AL. (2008) MODELING	D-l

D. 1.1. Input File for Exposure During Pregnancy	D-l

D.1.2. Table of Results for Baccarelli et al. (2008)	D-l

D.2. MOCARELLI ET AL. (2008) MODELING	D-2

D.2.1. Input File for Exposure for Pulse to Measurement 0.5 Years After the

Seveso Pulse Dose	D-2

D.2.2. Input File for Exposure from Pulse to the End of the Critical Window

3.8 Years After the Seveso Pulse Dose	D-2

D.2.3. Input File for Continuous Exposure for 10 Years	D-3

D.2.4. Tables of Results for Mocarelli et al. (2008)	D-4

D.3. ALALUUSUA ET AL. (2004) MODELING	D-4

D.3.1. Input File for Exposure for Pulse to Measurement 0.5 Years After the

Seveso Pulse Dose	D-4

D.3.2. Input File for Exposure from Pulse to the End of the Critical Window

2.5 Years After the Seveso Pulse Dose	D-5

D.3.3. Input File for Continuous Exposure for 5 Years	D-5

D.3.4. Tables of Results for Alaluusua et al. (2004)	D-6

D.4. ESKANAZI ET AL. (2002) MODELING	D-7

D.4.1. Input File for Exposure for Pulse to Measurement 0.5 Years After the

Seveso Pulse Dose	D-7

D.4.2. Input File for Exposure from Pulse to the End of the Critical Window

6.7 Years After the Seveso Pulse Dose	D-8

D.4.3. Input File for Continuous Exposure for 13 Years	D-8

D.4.4. Tables of Results for Eskanazi et al. (2002)	D-9

D.5. REFERENCES	D-10

This document is a draft for review purposes only and does not constitute Agency policy.

D-ii	DRAFT—DO NOT CITE OR QUOTE


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LIST OF TABLES

D-l. Estimated continuous intake corresponding to maternal serum concentration in

Figure 2A	D-l

D-2. Estimated maximum intake corresponding to maternal serum concentration in

Figure 2A	D-2

D-3. Matching critical window average after pulse to critical window average for

continuous intake run	D-4

D-4. Matching critical window peak after pulse to peak critical window concentration

for continuous intake run	D-4

D-5. Matching critical window average after pulse to critical window average for

continuous intake run	D-6

D-6. Matching critical window peak after pulse to peak critical window

concentration for continuous intake run	D-7

D-7. Matching critical window average after pulse to critical window average for

continuous intake run	D-9

D-8. Matching critical window peak after pulse to peak critical window

concentration for continuous intake run	D-9

This document is a draft for review purposes only and does not constitute Agency policy.

D-iii	DRAFT—DO NOT CITE OR QUOTE


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APPENDIX D. EPIDEMIOLOGICAL KINETIC MODELING

D.l. BACCARELLI ET AL. (2008) MODELING

D.l.l. Input File for Exposure During Pregnancy

CINT = 1 % 168 %100	%integration time

%Exposure scenario

= 0 % delay before begin exposure (HOUR)

= 401190 %TIME EXPO SURE STOP (HOUR)
= 24 %TIME
= 401190 %DELAY BEFORE BACKGROUND EXP (HOUR)
%TIME OF BACKGROUND EXP STOP (HOUR)

EXPTIMEON
EXPTIMEOFF
DAY CYCLE
B CKTIMEON
B CKTIMEOFF =401190
IVLACK =401190
IVPERIOD =401190

%GESTATION CONTROL
MATTING = 262800 % BEGINNING MATTING (HOUR)at 30 years old
TIMELIMIT = 269184 %SIMULATION LIMIT TIME (HOUR)

TRANSTIME ON = 264312 % EXCHANGE MOTHER FETUS 1512 HOUR POST
MATTING

%Exposure dose
MSTOT	=0.021 % ng of TCDD /kg of BW

MSTOTBCKGR =0. %0.1 % ORAL BACKGROUND EXPOSURE DOSE (nG/KG)
DOSEIV = 0. %10
DOSEIVLATE = 0. %10

% TRANFER MOTHER TO FETUS CLEARANCE
CLPLAFET = 0.001 % MOTHER TO FETUS TRANFERT CLE ARAN CE(L/HR)

D.1.2. Table of Results for Baccarelli et al. (2008)

Table D-l. Estimated continuous intake corresponding to maternal serum
concentration in Figure 2A

Variable

Value

Notes

Infant b-TSH

5 uU/mL

BMR

Maternal lipid adjusted serum

270 ng/kg

From Figure 2A

Intake

0.024 ng/kg-day

From Emond model, pregnancy at 30
years

This document is a draft for review purposes only and does not constitute Agency policy.

D-1	DRAFT—DO NOT CITE OR QUOTE


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Table D-2. Estimated maximum intake corresponding to maternal serum
concentration in Figure 2A

Variable

Value

Notes

Infant b-TSH

—

—

Maternal lipid adjusted serum

309.5 ng/kg

Maximum from Figure 2A

Intake

0.030 ng/kg-day

From Emond model, pregnancy at 30
years

D.2. MOCARELLI ET AL. (2008) MODELING

D.2.1. Input File for Exposure for Pulse to Measurement 0.5 Years After the Seveso Pulse
Dose

CINT = 1. %

EXPTIMEON = 54312. % Delay before begin exposure (HOUR) 6.2 years
EXPTIMEOFF = 54335. %324120 % HOUR/YEAR !TIME EXPOSURE STOP
(HOUR) 6.2 years + 23 hours
DAY CYCLE = 24. % TIME

BCK TIME ON = 0. % DELAY BEFORE BACKGROUND EXP (HOUR)

BCK TIME OFF = 613200 % TIME OF BACKGROUND EXP STOP (HOUR)

TIMELIMIT = 58692. % half a year (July 1976 until January 1977) past 6.2 years
MSTOTBCKGR = 3.7E-4 % ORAL BACKGROUND EXPOSURE DOSE (UG/KG)

% oral dose oral dose oral dose

MSTOT = 232.4 % Seveso, ORAL DAILY EXPOSURE DOSE (NG/KG)

DOSEIV = 0 % 40 %50 %5 %0.5 %0.3 %0.2 %0.1%0.05%0.3 %NG/KG
% oral dose oral dose oral dose

MEANLIPID = 731 % 711 %664 %778 %468 %671 %730 %662 %592%615%730%
PAS_INDUC= 1 % NON INDUCTION (0) CONTROLE DE L'INDUCTION

%human variable parameter
MALE = 1.

FEMALE = 0.

Y0 = 0.	% 0 years old at the beginning of the simulation

D.2.2. Input File for Exposure from Pulse to the End of the Critical Window 3.8 Years
After the Seveso Pulse Dose

CINT = 1. %

EXP TIME ON = 54312. % Delay before begin exposure (HOUR) 6.2 years
EXP TIME OFF = 54335. %324120 % HOUR/YEAR !TIME EXPOSURE STOP
(HOUR) 6.2 years + 23 hours
DAY CYCLE = 24. % TIME

This document is a draft for review purposes only and does not constitute Agency policy.

D-2	DRAFT—DO NOT CITE OR QUOTE


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BCKTIMEON = 0. % DELAY BEFORE BACKGROUND EXP (HOUR)
BCKTIMEOFF = 613200. % TIME OF BACKGROUND EXP STOP (HOUR)
TIMELIMIT = 87600. % 10 years

MSTOTBCKGR = 3.7e-4 % ORAL BACKGROUND EXPOSURE DOSE (UG/KG)
% oral dose oral dose oral dose

MSTOT = 232.5 % Serveso, ORAL DAILY EXPOSURE DOSE (NG/KG)

DOSEIV = 0 % 40 %50 %5 %0.5 %0.3 %0.2 %0.1%0.05%0.3 %NG/KG
% oral dose oral dose oral dose

MEANLIPID = 730 % 711 %664 %778 %468 %671 %730 %662 %592%615%730%
PAS_INDUC= 1 % NON INDUCTION (0) CONTROLE DE L'INDUCTION

%human variable parameter
MALE = 1.

FEMALE = 0.

Y0 = 0.	% 0 years old at the beginning of the simulation

D.2.3. Input File for Continuous Exposure for 10 Years

CINT = 1. %

EXP TIME ON =0. % Delay before begin exposure (HOUR)

EXP TIME OFF = 87600. % HOUR/YEAR !TIME EXPOSURE STOP (HOUR)

DAY CYCLE = 24. % TIME

BCK TIME ON = 0. %324120 % DELAY BEFORE BACKGROUND EXP (HOUR)
BCKTIMEOFF = 613200 %324120 % TIME OF BACKGROUND EXP STOP (HOUR)
TIMELIMIT = 87600. % 10 years

MSTOTBCKGR = 0. %3.35E-4 % ORAL BACKGROUND EXPOSURE DOSE (UG/KG)
% oral dose oral dose oral dose

MSTOT = 3.903 % Seveso, ORAL DAILY EXPOSURE DOSE (NG/KG)

DOSEIV = 0 % 40 %50 %5 %0.5 %0.3 %0.2 %0.1%0.05%0.3 %NG/KG
% oral dose oral dose oral dose

MEANLIPID = 730 % 711 %664 %778 %468 %671 %730 %662 %592%615%730%
PAS_INDUC= 1 % NON INDUCTION (0) CONTROLE DE L'INDUCTION

%human variable parameter
MALE = 1.

FEMALE = 0.

Y0 = 0.	% 0 years old at the beginning of the simulation

This document is a draft for review purposes only and does not constitute Agency policy.

D-3	DRAFT—DO NOT CITE OR QUOTE


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D.2.4. Tables of Results for Mocarelli et al. (2008)

Table D-3. Matching critical window average after pulse to critical window
average for continuous intake run

Person modeled,
beginning at age 0

Lipid adjusted
serum (1976) ng/kg
from Figure 3E

Pulse dose, 0.5
year lag time
(ng/kg)

Average lipid
adjusted serum
3.8 years after
incident (ng/kg)

Continuous intake
for 10 years
(ng/kg-day)

Boy, lstquartile

68

8.135

57.72

0.008024

Boy, 4th quartile

733

232.5

580.5

0.2128

Table D-4. Matching critical window peak after pulse to peak critical
window concentration for continuous intake run

Person modeled,
beginning at age 0

Lipid adjusted
serum (1976) ng/kg
from Figure 3E

Pulse dose, 0.5
year lag time
(ng/kg)

Peak lipid
adjusted serum
after incident
(ng/kg)

Continuous intake
for 10 years
(ng/kg-day)

Boy, lstquartile

68

8.135

248.0

0.03194

Boy, 4th quartile

733

232.5

6674

3.904

D.3. ALALUUSUA ET AL. (2004) MODELING

D.3.1. Input File for Exposure for Pulse to Measurement 0.5 Years After the Seveso Pulse
Dose

CINT = 1. %

EXPTIMEON =21900. % Delay before begin exposure (HOUR) 2.5 years
EXPTIMEOFF = 21923. % 21900+23 % HOUR/YEAR ! TIME EXPOSURE STOP
(HOUR) 2.5 years and 23 hours
DAY CYCLE = 24. % TIME

BCK TIME ON = 0. % DELAY BEFORE BACKGROUND EXP (HOUR)

BCK TIME OFF = 613200. % TIME OF BACKGROUND EXP STOP (HOUR)

TIMELIMIT = 26280. % half a year (July 1976 until January 1977) past 2.5 years
MSTOTBCKGR = 3.7e-4 % ORAL BACKGROUND EXPOSURE DOSE (UG/KG)

% oral dose oral dose oral dose

MSTOT = 24.22 % Seveso, ORAL DAILY EXPOSURE DOSE (NG/KG)

DOSEIV = 0 % 40 %50 %5 %0.5 %0.3 %0.2 %0.1%0.05%0.3 %NG/KG
% oral dose oral dose oral dose

This document is a draft for review purposes only and does not constitute Agency policy.

D-4	DRAFT—DO NOT CITE OR QUOTE


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MEANLIPID = 730 % 711 %664 %778 %468 %671 %730 %662 %592%615%730%
PAS_INDUC= 1 % NON INDUCTION (0) CONTROLE DE L'INDUCTION

%human variable parameter
MALE = 1.

FEMALE = 0.

Y0 = 0.	% 0 years old at the beginning of the simulation

D.3.2. Input File for Exposure from Pulse to the End of the Critical Window 2.5 Years
After the Seveso Pulse Dose

CINT = 1. %

EXPTIMEON =21900. % Delay before begin exposure (HOUR) 2.5 years
EXPTIMEOFF = 21923. % 324120 % HOUR/YEAR ! TIME EXPOSURE STOP
(HOUR) 2.5 years and 23 hours
DAY CYCLE = 24. % TIME

BCK TIME ON = 0. % 324120 % DELAY BEFORE BACKGROUND EXP (HOUR)
BCKTIMEOFF = 613200. % 324120 % TIME OF BACKGROUND EXP STOP (HOUR)
TIMELIMIT =43800. % 5 years

MSTOTBCKGR = 3.7e-4 % ORAL BACKGROUND EXPOSURE DOSE (UG/KG)

% oral dose oral dose oral dose

MSTOT = 24.22 % Seveso, ORAL DAILY EXPOSURE DOSE (NG/KG)

DOSEIV = 0 % 40 %50 %5 %0.5 %0.3 %0.2 %0.1%0.05%0.3 %NG/KG
% oral dose oral dose oral dose

MEANLIPID = 730 % 711 %664 %778 %468 %671 %730 %662 %592%615%730%
PAS_INDUC= 1 % NON INDUCTION (0) CONTROLE DE L'INDUCTION

%human variable parameter
MALE = 1.

FEMALE = 0.

Y0 = 0.	% 0 years old at the beginning of the simulation

D.3.3. Input File for Continuous Exposure for 5 Years

CINT = 1. %

EXP TIME ON =0. % Delay before begin exposure (HOUR)

EXP TIME OFF = 43800. % 324120 % HOUR/YEAR !TIME EXPOSURE STOP (HOUR)
DAY CYCLE = 24. % TIME

BCK TIME ON = 0. % 324120 % DELAY BEFORE BACKGROUND EXP (HOUR)
BCK TIME OFF = 613200. % 324120 % TIME OF BACKGROUND EXP STOP (HOUR)
TIMELIMIT =43800. % End of critical window (5 years)

MSTOTBCKGR = 0. % ORAL BACKGROUND EXPOSURE DOSE (UG/KG)

% oral dose oral dose oral dose

MSTOT = 0.03486 % Seveso, ORAL DAILY EXPOSURE DOSE (NG/KG)

This document is a draft for review purposes only and does not constitute Agency policy.

D-5	DRAFT—DO NOT CITE OR QUOTE


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DOSEIV = 0 % 40 %50 %5 %0.5 %0.3 %0.2 %0.1%0.05%0.3 %NG/KG
% oral dose oral dose oral dose

MEANLIPID = 730 % 711 %664 %778 %468 %671 %730 %662 %592%615%730%
PAS_INDUC= 1 % NON INDUCTION (0) CONTROLE DE L'INDUCTION

%human variable parameter
MALE = 1.

FEMALE = 0.

Y0 = 0.	% 0 years old at the beginning of the simulation

D.3.4. Tables of Results for Alaluusua et al. (2004)

Table D-5. Matching critical window average after pulse to critical window
average for continuous intake run

Person modeled,
beginning at age 0

Lipid adjusted
serum (1976) ng/kg
estimated from
tertile bins3

Pulse dose,
0.5 year lag
time (ng/kg)

Average lipid
adjusted serum 2.5
years after
incident (ng/kg)

Continuous
intake for 5
years (ng/kg-
day)

Boy, 1st tertile

130

24.22

110.8

0.03486

Boy, 2nd tertile

383

108.9

322.7

0.1578

Boy, 3rd tertile

1830

1041

1538

1.511

Girl, 1st tertile

130

23.03

110.8

0.03211

Girl, 2nd tertile

383

105.3

324.4

0.1481

Girl, 3rd tertile

1830

1015

1546

1.427

Boy and girl, averaged,
1st tertile

130

-

-

0.03349

Boy and girl, averaged,
2nd tertile

383

-

-

0.1530

Boy and girl, averaged,
3rd tertile

1830

-

-

1.469

aMean of tertile bin assuming a lognormal distribution of serum concentrations.

This document is a draft for review purposes only and does not constitute Agency policy.

D-6	DRAFT—DO NOT CITE OR QUOTE


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Table D-6. Matching critical window peak after pulse to peak critical
window concentration for continuous intake run

Person modeled,
beginning at age 0

Lipid adjusted
serum (1976) ng/kg
estimated from
tertile bins

Pulse dose,
0.5 year lag
time (ng/kg)

Peak lipid
adjusted serum
after incident
(ng/kg)

Continuous
intake for 5
years (ng/kg-
day)

Boy, 1st tertile

130

24.22

618.8

0.2113

Boy, 2nd tertile

383

108.9

2700

1.783

Boy, 3rd tertile

1830

1041

24706

31.35

Girl, 1st tertile

130

23.02

588.0

0.1882

Girl, 2nd tertile

383

105.3

2610

1.642

Girl, 3rd tertile

1830

1015

24113

29.52

Boy and girl, averaged,
1st tertile

130

-

-

0.1998

Boy and girl, averaged,
2nd tertile

383

-

-

1.713

Boy and girl, averaged,
3rd tertile

1830

-

-

30.44

aMean of tertile bin assuming a lognormal distribution of serum concentrations.

D.4. ESKANAZI ET AL. (2002) MODELING

D.4.1. Input File for Exposure for Pulse to Measurement 0.5 Years After the Seveso Pulse
Dose

CINT = 1. %

EXPTIMEON = 58692. % Delay before begin exposure (HOUR) 6.7 years
EXPTIMEOFF = 58715. % HOUR/YEAR !TIME EXPOSURE STOP (HOUR) 6.7 years +
23 hours

DAY CYCLE = 24. % TIME

BCK TIME ON = 0. %324120 % DELAY BEFORE BACKGROUND EXP (HOUR)
BCK TIME OFF = 613200. %324120 % TIME OF BACKGROUND EXP STOP (HOUR)
TIMELIMIT = 63072. % half a year (July 1976 until January 1977) past 6.7 years
MSTOTBCKGR = 3.7e-4 % ORAL BACKGROUND EXPOSURE DOSE (UG/KG)

% oral dose oral dose oral dose

MSTOT = 7193 % Seveso, ORAL DAILY EXPOSURE DOSE (NG/KG)

DOSEIV = 0 % 40 %50 %5 %0.5 %0.3 %0.2 %0.1%0.05%0.3 %NG/KG
% oral dose oral dose oral dose

MEANLIPID = 730 % 711 %664 %778 %468 %671 %730 %662 %592%615%730%

This document is a draft for review purposes only and does not constitute Agency policy.

D-7	DRAFT—DO NOT CITE OR QUOTE


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PAS_INDUC= 1 % NON INDUCTION (0) CONTROLE DE L'INDUCTION

%human variable parameter
MALE = 0.

FEMALE = 1.

Y0 = 0.	% 0 years old at the beginning of the simulation

D.4.2. Input File for Exposure from Pulse to the End of the Critical Window 6.7 Years
After the Seveso Pulse Dose

CINT = 1. %

EXPTIMEON = 58692. % Delay before begin exposure (HOUR) 6.7 years
EXPTIMEOFF = 58715. %324120 % HOUR/YEAR !TIME EXPOSURE STOP
(HOUR) 6.7 years + 23 hours
DAY CYCLE = 24. % TIME

BCKTIMEON = 0. %324120 % DELAY BEFORE BACKGROUND EXP (HOUR)
BCKTIMEOFF = 613200 %324120 % TIME OF BACKGROUND EXP STOP (HOUR)
TIMELIMIT = 113880. % 13 years

MSTOTBCKGR = 3.7e-4 % ORAL BACKGROUND EXPOSURE DOSE (UG/KG)

% oral dose oral dose oral dose

MSTOT =7193 % Seveso, ORAL DAILY EXPOSURE DOSE (NG/KG)

DOSEIV = 0 % 40 %50 %5 %0.5 %0.3 %0.2 %0.1%0.05%0.3 %NG/KG
% oral dose oral dose oral dose

MEANLIPID = 730 % 711 %664 %778 %468 %671 %730 %662 %592%615%730%
PAS_INDUC= 1 % NON INDUCTION (0) CONTROLE DE L'INDUCTION

%human variable parameter
MALE = 0.

FEMALE = 1.

Y0 = 0.	% 0 years old at the beginning of the simulation

D.4.3. Input File for Continuous Exposure for 13 Years

CINT = 1. %

EXP TIME ON =0. % Delay before begin exposure (HOUR)

EXP TIME OFF = 113880. %324120 % HOUR/YEAR !TIME EXPOSURE STOP

(HOUR) 13 years

DAY CYCLE = 24. % TIME

BCK TIME ON = 0. %324120 % DELAY BEFORE BACKGROUND EXP (HOUR)
BCK TIME OFF = 613200. %324120 % TIME OF BACKGROUND EXP STOP (HOUR)
TIMELIMIT = 113880. % 13 years

MSTOTBCKGR = 0. %3.35E-4 % ORAL BACKGROUND EXPOSURE DOSE (UG/KG)
% oral dose oral dose oral dose

MSTOT = 166 % Seveso, ORAL DAILY EXPOSURE DOSE (NG/KG)

This document is a draft for review purposes only and does not constitute Agency policy.

D-8	DRAFT—DO NOT CITE OR QUOTE


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DOSEIV = 0 % 40 %50 %5 %0.5 %0.3 %0.2 %0.1%0.05%0.3 %NG/KG
% oral dose oral dose oral dose

MEANLIPID = 730 % 711 %664 %778 %468 %671 %730 %662 %592%615%730%
PAS_INDUC= 1 % NON INDUCTION (0) CONTROLE DE L'INDUCTION

%human variable parameter
MALE = 0.

FEMALE = 1.

Y0 = 0.	% 0 years old at the beginning of the simulation

D.4.4. Tables of Results for Eskanazi et al. (2002)

Table D-7. Matching critical window average after pulse to critical window
average for continuous intake run

Person modeled,
beginning at age 0

Lipid adjusted serum
(adjusted to 1976-
1977 levels) ng/kg
from Figure 1A

Pulse dose,
0.5 year lag
time (ng/kg)

Average lipid
adjusted serum 6.7
years after incident
(ng/kg)

Continuous
intake for 13
years (ng/kg-day)

Girl, estrous cycle
28.5 days

166

28.40

114.0

0.01660

Girl, estrous cycle
29 days

693

215.5

455.1

0.1224

Girl, estrous cycle
29.5 days

2020

1008

1295

0.5693

Girl, estrous cycle
30 days

8450

7193

5179

4.054

Table D-8. Matching critical window peak after pulse to peak critical
window concentration for continuous intake run

Person modeled,
beginning at age 0

Lipid adjusted serum
(adjusted to 1976-
1977 levels) ng/kg
from Figure 1A

Pulse dose,
0.5 year lag
time (ng/kg)

Peak lipid
adjusted serum
after incident
(ng/kg)

Continuous intake
for 13 years
(ng/kg-day)

Girl, estrous cycle
28.5 days

166

28.40

838.2

0.1800

Girl, estrous cycle
29 days

693

215.5

6183

3.148

Girl, estrous cycle
29.5 days

2020

1008

28316

20.86

Girl, estrous cycle
30 days

8450

7193

198240

166.6

This document is a draft for review purposes only and does not constitute Agency policy.

D-9	DRAFT—DO NOT CITE OR QUOTE


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1

2	D.5. REFERENCES

3	Alaluusua, S; Calderara, P; Gerthoux, PM; et al. (2004) Developmental dental aberrations after the dioxin accident

4	inSeveso. Environ Health Perspect 112(13): 1313-1318.

5	Baccarelli, A; Giacomini, SM; Corbetta, C; et al. (2008) Neonatal thyroid function in Seveso 25 years after maternal

6	exposure to dioxin. PLoS Med 5(7):el61.

7	Eskenazi, B; Mocarelli, P; Warner, M; et al. (2002). Serum dioxin concentrations and endometriosis: a cohort study

8	in Seveso, Italy. Environ Health Perspect 110(7): 629-634.

9	Mocarelli, P; Gerthoux, PM; Patterson, DG, Jr.; et al. (2008) Dioxin exposure, from infancy through puberty,

10	produces endocrine disruption and affects human semen quality. Environ Health Perspect 116(l):70-77.

11

This document is a draft for review purposes only and does not constitute Agency policy.

D-10 DRAFT—DO NOT CITE OR QUOTE


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DRAFT

DO NOT CITE OR QUOTE

May 2010
External Review Draft

APPENDIX E
Noncancer Benchmark Dose Modeling

NOTICE

THIS DOCUMENT IS AN EXTERNAL REVIEW DRAFT. It has not been formally released
by the U.S. Environmental Protection Agency and should not at this stage be construed to
represent Agency policy. It is being circulated for comment on its technical accuracy and policy
implications.

National Center for Environmental Assessment
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, OH


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CONTENTS—APPENDIX E: Noncancer Benchmark Dose Modeling

APPENDIX E. NONCANCER BENCHMARK DOSE MODELING	E-1

E.l. BMDS INPUT TABLES	E-l

E.l.l. Amin et al. (2000)	E-l

E.l.2. Bell et al. (2007)	E-l

E.l.3. Cantoni et al. (1981)	E-2

E.l.4. Crofton et al. (2005)	E-2

E.l.5. DeCaprio et al. (1986)	E-3

E.l.6. Franc et al. (2001)	E-4

E.l.7. Hojoetal. (2002)	E-4

E.l.8. Kattainen et al. (2001)	E-5

E. 1.9. Keller et al. (2007, 2008a, b)	E-5

E.l.10. Kocibaetal. (1978)	E-6

E. 1.11. Latchoumycandane and Mathur (2002)	E-6

E.l. 12. Li etal. (1997)	E-7

E.l.13. Li et al. (2006)	E-7

E.l. 14. Markowski et al. (2001)	E-8

E.l.15. Miettinen et al. (2006)	E-8

E.l. 16. National Toxicology Program (1982)	E-9

E.l. 17. National Toxicology Program (2006)	E-10

E.l.18. Ohsako etal. (2001)	E-ll

E.l. 19. Shi et al. (2007)	E-ll

E.l.20. Smialowicz et al. (2008)	E-12

E.l.21. Toth etal. (1979)	E-12

E.l.22. Van Birgelen et al. (1995)	I>13

E.l.23. White etal. (1986)	I>13

E.2. ALTERNATE DOSE: WHOLE BLOOD BMDS RESULTS	11-14

E.2.1. Amin et al., 2000: 0.25% Saccharin Consumed, Female	E-14

E.2.1.1. Summary Table of BMDS Modeling Results	E-14

E.2.1.2. Output for Selected Model: Linear	E-14

E.2.1.3. Figure for Selected Model: Linear	E-17

E.2.1.4. Output for Additional Model Presented: Power, Unrestricted....E-l7

E.2.1.5. Figure for Additional Model Presented: Power, Unrestricted	E-20

E.2.2. Amin et al., 2000: 0.25% Saccharin Preference Ratio, Female	E-20

E.2.2.1. Summary Table of BMDS Modeling Results	E-20

E.2.2.2. Output for Selected Model: Linear	E-21

E.2.2.3. Figure for Selected Model: Linear	E-23

E.2.3. Amin et al., 2000: 0.50% Saccharin Consumed, Female	E-24

E.2.3.1. Summary Table of BMDS Modeling Results	E-24

E.2.3.2. Output for Selected Model: Linear	E-24

E.2.3.3. Figure for Selected Model: Linear	E-27

E.2.3.4. Output for Additional Model Presented: Power, Unrestricted ....E-27
E.2.3.5. Figure for Additional Model Presented: Power, Unrestricted	E-30

This document is a draft for review purposes only and does not constitute Agency policy.

E-ii DRAFT—DO NOT CITE OR QUOTE


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CONTENTS (continued)

E.2.4. Amin et al., 2000: 0.50% Saccharin Preference Ratio, Female	E-31

E.2.4.1. Summary Table of BMDS Modeling Results	E-31

E.2.4.2. Output for Selected Model: Linear	E-31

E.2.4.3. Figure for Selected Model: Linear	E-34

E.2.4.4. Output for Additional Model Presented: Power, Unrestricted ....E-34

E.2.4.5. Figure for Additional Model Presented: Power, Unrestricted	E-37

E.2.5. Bell et al., 2007a: Balano-Preputial Separation, Postnatal Day 49	E-38

E.2.5.1. Summary Table of BMDS Modeling Results	E-38

E.2.5.2. Output for Selected Model: Log-Logistic	E-38

E.2.5.3. Figure for Selected Model: Log-Logistic	E-40

E. 2.5.4. Output for Additi onal Model Pre sented: Log-Logi sti c,

Unrestricted	E-41

E.2.5.5. Figure for Additional Model Presented: Log-Logistic,

Unrestricted	E-43

E.2.6. Cantoni et al., 1981: Urinary Coproporhyrins, 3 Months	E-44

E.2.6.1. Summary Table of BMDS Modeling Results	E-44

E.2.6.2. Output for Selected Model: Exponential (M4)	E-44

E.2.6.3. Figure for Selected Model: Exponential (M4)	E-47

E.2.6.4. Output for Additional Model Presented: Power, Unrestricted ....E-47

E.2.6.5. Figure for Additional Model Presented: Power, Unrestricted	E-50

E.2.7. Cantoni et al., 1981: Urinary Porphyrins	E-51

E.2.7.1. Summary Table of BMDS Modeling Results	E-51

E.2.7.2. Output for Selected Model: Exponential (M2)	E-51

E.2.7.3. Figure for Selected Model: Exponential (M2)	E-54

E.2.8. Crofton et al., 2005: Serum, T4	E-55

E.2.8.1. Summary Table of BMDS Modeling Results	E-55

E.2.8.2. Output for Selected Model: Exponential (M4)	E-55

E.2.8.3. Figure for Selected Model: Exponential (M4)	E-58

E.2.9. Franc et al., 2001: S-D Rats, Relative Liver Weight	E-59

E.2.9.1. Summary Table of BMDS Modeling Results	E-59

E.2.9.2. Output for Selected Model: Power	E-59

E.2.9.3. Figure for Selected Model: Power	E-62

E.2.10. Franc et al., 2001: L-E Rats, Relative Liver Weight	E-63

E.2.10.1. Summary Table of BMDS Modeling Results	E-63

E.2.10.2. Output for Selected Model: Hill	E-63

E.2.10.3. Figure for Selected Model: Hill	E-66

E.2.10.4. Output for Additional Model Presented: Hill, Unrestricted	E-66

E.2.10.5. Figure for Additional Model Presented: Hill, Unrestricted	E-69

E.2.11. Franc et al., 2001: S-D Rats, Relative Thymus Weight	E-70

E.2.11.1. Summary Table of BMDS Modeling Results	E-70

E.2.11.2. Output for Selected Model: Exponential (M4)	E-70

E.2.11.3. Figure for Selected Model: Exponential (M4)	E-73

E.2.11.4. Output for Additional Model Presented: Polynomial, 3-degree..E-73

This document is a draft for review purposes only and does not constitute Agency policy.

E-iii DRAFT—DO NOT CITE OR QUOTE


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CONTENTS (continued)

E.2.11.5. Figure for Additional Model Presented: Polynomial, 3-degree ..E-76

E.2.12. Franc et al., 2001: L-E Rats, Relative Thymus Weight	E-77

E.2.12.1. Summary Table of BMDS Modeling Results	E-77

E.2.12.2. Output for Selected Model: Exponential (M4)	E-77

E.2.12.3. Figure for Selected Model: Exponential (M4)	E-80

E.2.13. Franc et al., 2001: Ft/W Rats, Relative Thymus Weight	E-81

E.2.13.1. Summary Table of BMDS Modeling Results	E-81

E.2.13.2. Output for Selected Model: Exponential (M2)	E-81

E.2.13.3. Figure for Selected Model: Exponential (M2)	E-84

E.2.14. Hojo et al., 2002: DRL Reinforce Per Minute	E-85

E.2.14.1. Summary Table of BMDS Modeling Results	E-85

E.2.14.2. Output for Selected Model: Exponential (M4)	E-85

E.2.14.3. Figure for Selected Model: Exponential (M4)	E-88

E.2.15. Hojo et al., 2002: DRL Response Per Minute	E-89

E.2.15.1. Summary Table of BMDS Modeling Results	E-89

E.2.15.2. Output for Selected Model: Exponential (M4)	E-89

E.2.15.3. Figure for Selected Model: Exponential (M4)	E-92

E.2.16. Kattainen et al., 2001: 3rd Molar Eruption, Female	E-93

E.2.16.1. Summary Table of BMDS Modeling Results	E-93

E.2.16.2. Output for Selected Model: Log-Logistic	E-93

E.2.16.3. Figure for Selected Model: Log-Logistic	E-95

E.2.16.4. Output for Additional Model Presented: Log-Logistic,

Unrestricted	E-95

E.2.16.5. Figure for Additional Model Presented: Log-Logistic,

Unrestricted	E-97

E.2.17. Kattainen et al., 2001: 3rd Molar Length, Female	E-98

E.2.17.1. Summary Table of BMDS Modeling Results	E-98

E.2.17.2. Output for Selected Model: Hill	E-98

E.2.17.3. Figure for Selected Model: Hill	E-101

E.2.17.4. Output for Additional Model Presented: Hill, Unrestricted	E-101

E.2.17.5. Figure for Additional Model Presented: Hill, Unrestricted	E-104

E.2.18. Keller etal., 2007: Missing Mandibular Molars, CBA J	E-105

E.2.18.1. Summary Table of BMDS Modeling Results	E-105

E.2.18.2. Output for Selected Model: Multistage, 1-Degree	E-105

E.2.18.3. Figure for Selected Model: Multistage, 1-Degree	E-107

E.2.19. Kociba et al., 1978: Urinary Coproporphyrin, Females	E-108

E.2.19.1. Summary Table of BMDS Modeling Results	E-108

E.2.19.2. Output for Selected Model: Exponential (M4)	E-108

E.2.19.3. Figure for Selected Model: Exponential (M4)	E-l 11

E.2.20. Kociba et al., 1978: Uroporphyrin per Creatinine, Female	E-l 12

E.2.20.1. Summary Table of BMDS Modeling Results	E-l 12

E.2.20.2. Output for Selected Model: Linear	E-l 12

E.2.20.3. Figure for Selected Model: Linear	E-l 15

This document is a draft for review purposes only and does not constitute Agency policy.

E-iv DRAFT—DO NOT CITE OR QUOTE


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CONTENTS (continued)

E.2.21. Latchoumycandane and Mathur, 2002: Sperm Production	E-l 16

E.2.21.1. Summary Table of BMDS Modeling Results	E-l 16

E.2.21.2. Output for Selected Model: Hill	E-l 16

E.2.21.3. Figure for Selected Model: Hill	E-l 19

E.2.21.4. Output for Additional Model Presented: Hill, Unrestricted	E-l 19

E.2.21.5. Figure for Additional Model Presented: Hill, Unrestricted	E-122

E.2.22. Li et aL 1997: FSH	E-123

E.2.22.1. Summary Table of BMDS Modeling Results	E-123

E.2.22.2. Output for Selected Model: Power	E-123

E.2.22.3. Figure for Selected Model: Power	E-126

E.2.22.4. Output for Additional Model Presented: Power, Unrestricted ..E-126
E.2.22.5. Figure for Additional Model Presented: Power, Unrestricted...E-l29

E.2.23. Li et al., 2006: Estradiol, 3-Day	E-130

E.2.23.1. Summary Table of BMDS Modeling Results	E-130

E.2.23.2. Output for Selected Model: Linear	E-130

E.2.23.3. Figure for Selected Model: Linear	E-133

E.2.24. Li et al., 2006: Progesterone, 3-Day	E-134

E.2.24.1. Summary Table of BMDS Modeling Results	E-134

E.2.24.2. Output for Selected Model: Hill	E-134

E.2.24.3. Figure for Selected Model: Hill	E-137

E.2.25. Markowski et al., 2001: FR10 Run Opportunities	E-138

E.2.25.1. Summary Table of BMDS Modeling Results	E-138

E.2.25.2. Output for Selected Model: Exponential (M2)	E-138

E.2.25.3. Figure for Selected Model: Exponential (M2)	E-141

E.2.26. Markowski et al., 2001: FR2 Revolutions	E-142

E.2.26.1. Summary Table of BMDS Modeling Results	E-142

E.2.26.2. Output for Selected Model: Hill	E-142

E.2.26.3. Figure for Selected Model: Hill	E-145

E.2.26.4. Output for Additional Model Presented: Power, Unrestricted ..E-145
E.2.26.5. Figure for Additional Model Presented: Power, Unrestricted...E-l48

E.2.27. Markowski et al., 2001: FR5 Run Opportunities	E-149

E.2.27.1. Summary Table of BMDS Modeling Results	E-149

E.2.27.2. Output for Selected Model: Hill	E-149

E.2.27.3. Figure for Selected Model: Hill	E-152

E.2.27.4. Output for Additional Model Presented: Power, Unrestricted ..E-152
E.2.27.5. Figure for Additional Model Presented: Power, Unrestricted...E-155

E.2.28. Miettinen et al., 2006: Cariogenic Lesions, Pups	E-156

E.2.28.1. Summary Table of BMDS Modeling Results	E-156

E.2.28.2. Output for Selected Model: Log-Logistic	E-156

E.2.28.3. Figure for Selected Model: Log-Logistic	E-158

E.2.28.4. Output for Additional Model Presented: Log-Logistic,

Unrestricted	E-158

This document is a draft for review purposes only and does not constitute Agency policy.

E-v DRAFT—DO NOT CITE OR QUOTE


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CONTENTS (continued)

E.2.28.5. Figure for Additional Model Presented: Log-Logistic,

Unrestricted	E-160

E.2.29. Murray et al., 1979: Fertility in F2 Generation	E-161

E.2.29.1. Summary Table of BMDS Modeling Results	E-161

E.2.29.2. Output for Selected Model: Multistage, 2-Degree	E-161

E.2.29.3. Figure for Selected Model: Multistage, 2-Degree	E-163

E.2.30. National Toxicology Program, 1982: Toxic Hepatitis, Male Mice	E-164

E.2.30.1. Summary Table of BMDS Modeling Results	E-164

E.2.30.2. Output for Selected Model: Multistage, 3-Degree	E-164

E.2.30.3. Figure for Selected Model: Multistage, 3-Degree	E-166

E.2.31. National Toxicology Program, 2006: Alveolar Metaplasia	E-167

E.2.31.1. Summary Table of BMDS Modeling Results	E-167

E.2.31.2. Output for Selected Model: Log-Logistic	E-167

E.2.31.3. Figure for Selected Model: Log-Logistic	E-169

E.2.32. National Toxicology Program, 2006: Eosinophilic Focus, Liver	E-170

E.2.32.1. Summary Table of BMDS Modeling Results	E-170

E.2.32.2. Output for Selected Model: Probit	E-170

E.2.32.3. Figure for Selected Model: Probit	E-172

E.2.33. National Toxicology Program, 2006: Fatty Change Diffuse, Liver	E-173

E.2.33.1. Summary Table of BMDS Modeling Results	E-173

E.2.33.2. Output for Selected Model: Weibull	E-173

E.2.33.3. Figure for Selected Model: Weibull	E-175

E.2.34. National Toxicology Program, 2006: Gingival Hyperplasia, Squamous, 2

Years	E-176

E.2.34.1. Summary Table of BMDS Modeling Results	E-176

E.2.34.2. Output for Selected Model: Log-Logistic	E-176

E.2.34.3. Figure for Selected Model: Log-Logistic	E-178

E.2.34.4. Output for Additional Model Presented: Log-Logistic,

Unrestricted	E-178

E.2.34.5. Figure for Additional Model Presented: Log-Logistic,

Unrestricted	E-180

E.2.35. National Toxicology Program, 2006: Hepatocyte Hypertrophy,

2 Years	11-181

E.2.35.1. Summary Table of BMDS Modeling Results	E-181

E.2.35.2. Output for Selected Model: Multistage, 5-Degree	E-181

E.2.35.3. Figure for Selected Model: Multistage, 5-Degree	E-183

E.2.36. National Toxicology Program, 2006: Necrosis, Liver	E-184

E.2.36.1. Summary Table of BMDS Modeling Results	E-184

E.2.36.2. Output for Selected Model: Log-Probit, Unrestricted	E-184

E.2.36.3. Figure for Selected Model: Log-Probit, Unrestricted	E-186

E.2.37. National Toxicology Program, 2006: Oval Cell Hyperplasia	E-187

E.2.37.1. Summary Table of BMDS Modeling Results	E-187

E.2.37.2. Output for Selected Model: Probit	E-187

This document is a draft for review purposes only and does not constitute Agency policy.

E-vi DRAFT—DO NOT CITE OR QUOTE


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CONTENTS (continued)

E.2.37.3. Figure for Selected Model: Probit	E-189

E.2.37.4. Output for Additional Model Presented: Weibull	E-189

E.2.37.5. Figure for Additional Model Presented: Weibull	E-191

E.2.38. National Toxicology Program, 2006: Pigmentation, Liver	E-192

E.2.38.1. Summary Table of BMDS Modeling Results	E-192

E.2.38.2. Output for Selected Model: Log-Probit	E-192

E.2.38.3. Figure for Selected Model: Log-Probit	E-194

E.2.39. National Toxicology Program, 2006: Toxic Hepatopathy	E-195

E.2.39.1. Summary Table of BMDS Modeling Results	E-195

E.2.39.2. Output for Selected Model: Multistage, 5-Degree	E-195

E.2.39.3. Figure for Selected Model: Multistage, 5-Degree	E-197

E.2.40. Ohsako et al., 2001: Ano-Genital Length, PND 120	E-198

E.2.40.1. Summary Table of BMDS Modeling Results	E-198

E.2.40.2. Output for Selected Model: Hill	E-198

E.2.40.3. Figure for Selected Model: Hill	E-201

E.2.40.4. Output for Additional Model Presented: Hill, Unrestricted	E-201

E.2.40.5. Figure for Additional Model Presented: Hill, Unrestricted	E-204

11.2.41.	Sewall et al., 1995: T4 In Serum	11-205

E.2.41.1. Summary Table of BMDS Modeling Results	E-205

E.2.41.2. Output for Selected Model: Hill	E-205

E.2.41.3. Figure for Selected Model: Hill	E-208

E.2.41.4. Output for Additional Model Presented: Hill, Unrestricted	E-208

E.2.41.5. Figure for Additional Model Presented: Hill, Unrestricted	E-211

11.2.42.	Shi et al., 2007: Estradiol 17B, PE9	11-212

E.2.42.1. Summary Table of BMDS Modeling Results	E-212

E.2.42.2. Output for Selected Model: Exponential (M4)	E-212

E.2.42.3. Figure for Selected Model: Exponential (M4)	E-215

11.2.43.	Smialowicz et al., 2008: PFC per 10 6 Cells	11-216

E.2.43.1. Summary Table of BMDS Modeling Results	E-216

E.2.43.2. Output for Selected Model: Power, Unrestricted	E-216

E.2.43.3. Figure for Selected Model: Power, Unrestricted	E-219

E.2.44. Smialowicz et al., 2008: PFC per Spleen	E-220

E.2.44.1. Summary Table of BMDS Modeling Results	E-220

E.2.44.2. Output for Selected Model: Power, Unrestricted	E-220

E.2.44.3. Figure for Selected Model: Power, Unrestricted	E-223

E.2.45. Toth et al., 1979: Amyloidosis	E-224

E.2.45.1. Summary Table of BMDS Modeling Results	E-224

E.2.45.2. Output for Selected Model: Log-Logistic	E-224

E.2.45.3. Figure for Selected Model: Log-Logistic	E-226

E.2.45.4. Output for Additional Model Presented: Log-Logistic,

Unrestricted	E-226

E.2.45.5. Figure for Additional Model Presented: Log-Logistic,

Unrestricted	E-228

This document is a draft for review purposes only and does not constitute Agency policy.

E-vii DRAFT—DO NOT CITE OR QUOTE


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CONTENTS (continued)

E.2.46. Toth et al., 1979: Skin Lesions	E-229

E.2.46.1. Summary Table of BMDS Modeling Results	E-229

E.2.46.2. Output for Selected Model: Log-Logistic	E-229

E.2.46.3. Figure for Selected Model: Log-Logistic	E-231

E.2.46.4. Output for Additional Model Presented: Log-Logistic,

Unrestricted	E-231

E.2.46.5. Figure for Additional Model Presented: Log-Logistic,

Unrestricted	E-23 3

E.2.47. Van Birgelen et al., 1995a: Hepatic Retinol	E-234

E.2.47.1. Summary Table of BMDS Modeling Results	E-234

E.2.47.2. Output for Selected Model: Exponential (M4)	E-234

E.2.47.3. Figure for Selected Model: Exponential (M4)	E-237

E.2.47.4. Output for Additional Model Presented: Power, Unrestricted ..E-237
E.2.47.5. Figure for Additional Model Presented: Power, Unrestricted...E-240

E.2.48. Van Birgelen et al., 1995a: Hepatic Retinol Palmitate	E-241

E.2.48.1. Summary Table of BMDS Modeling Results	E-241

E.2.48.2. Output for Selected Model: Exponential (M4)	E-241

E.2.48.3. Figure for Selected Model: Exponential (M4)	E-244

E.2.48.4. Output for Additional Model Presented: Power, Unrestricted ..E-244
E.2.48.5. Figure for Additional Model Presented: Power, Unrestricted...E-247

E.2.49. White et al., 1986: CH50	1>248

E.2.49.1. Summary Table of BMDS Modeling Results	E-248

E.2.49.2. Output for Selected Model: Hill	E-248

E.2.49.3. Figure for Selected Model: Hill	E-251

E.2.49.4. Output for Additional Model Presented: Hill, Unrestricted	E-251

E.2.49.5. Figure for Additional Model Presented: Hill, Unrestricted	E-254

E.3. ADMINISTERED DOSE BMDS RESULTS	E-255

E.3.1. Amin et al., 2000: 0.25% Saccharin Consumed, Female	E-255

E.3.1.1. Summary Table of BMDS Modeling Results	E-255

E.3.1.2. Output for Selected Model: Linear	E-255

E.3.1.3. Figure for Selected Model: Linear	E-258

E.3.1.4. Output for Additional Model Presented: Power, Unrestricted..E-258
E.3.1.5. Figure for Additional Model Presented: Power, Unrestricted...E-261

E.3.2. Amin et al., 2000: 0.25% Saccharin Preference Ratio, Female	E-262

E.3.2.1. Summary Table of BMDS Modeling Results	E-262

E.3.2.2. Output for Selected Model: Linear	E-262

E.3.2.3. Figure for Selected Model: Linear	E-265

E.3.3. Amin et al., 2000: 0.50% Saccharin Consumed, Female	E-266

E.3.3.1. Summary Table of BMDS Modeling Results	E-266

E.3.3.2. Output for Selected Model: Linear	E-266

E.3.3.3. Figure for Selected Model: Linear	E-269

E.3.3.4. Output for Additional Model Presented: Power, Unrestricted..E-269
E.3.3.5. Figure for Additional Model Presented: Power, Unrestricted...E-272

This document is a draft for review purposes only and does not constitute Agency policy.

E-viii DRAFT—DO NOT CITE OR QUOTE


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CONTENTS (continued)

E.3.4. Amin et al., 2000: 0.50% Saccharin Preference Ratio, Female	E-273

E.3.4.1. Summary Table of BMDS Modeling Results	E-273

E.3.4.2. Output for Selected Model: Linear	E-273

E.3.4.3. Figure for Selected Model: Linear	E-276

E.3.4.4. Output for Additional Model Presented: Power, Unrestricted..E-276
E.3.4.5. Figure for Additional Model Presented: Power, Unrestricted...E-279

E.3.5. Bell et al., 2007a: Balano-Preputial Separation, Postnatal Day 49	E-280

E.3.5.1. Summary Table of BMDS Modeling Results	E-280

E.3.5.2. E-280

E.3.5.3. Output for Selected Model: Log-Logistic	E-280

E.3.5.4. Figure for Selected Model: Log-Logistic	E-282

E. 3.5.5. Output for Additi onal Model Pre sented: Log-Logi sti c,

Unrestricted	E-283

E.3.5.6. Figure for Additional Model Presented: Log-Logistic,

Unrestricted	E-285

E.3.6. Cantoni et al., 1981: Urinary Coproporhyrins, 3 Months	E-286

E.3.6.1. Summary Table of BMDS Modeling Results	E-286

E.3.6.2. Output for Selected Model: Exponential (M4)	E-286

E.3.6.3. Figure for Selected Model: Exponential (M4)	E-289

E.3.6.4. Output for Additional Model Presented: Power, Unrestricted..E-289
E.3.6.5. Figure for Additional Model Presented: Power, Unrestricted...E-292

E.3.7. Cantoni et al., 1981: Urinary Porphyrins	E-293

E.3.7.1. Summary Table of BMDS Modeling Results	E-293

E.3.7.2. Output for Selected Model: Exponential (M2)	E-293

E.3.7.3. Figure for Selected Model: Exponential (M2)	E-296

E.3.8. Crofton et al., 2005: Serum, T4	E-297

E.3.8.1. Summary Table of BMDS Modeling Results	E-297

E.3.8.2. Output for Selected Model: Exponential (M4)	E-297

E.3.8.3. Figure for Selected Model: Exponential (M4)	E-300

E.3.9. Franc et al., 2001: S-D Rats, Relative Liver Weight	E-301

E.3.9.1. Summary Table of BMDS Modeling Results	E-301

E.3.9.2. Output for Selected Model: Power	E-301

E.3.9.3. Figure for Selected Model: Power	E-304

E.3.9.4. Output for Additional Model Presented: Power, Unrestricted..E-304
E.3.9.5. Figure for Additional Model Presented: Power, Unrestricted...E-307

E.3.10. Franc et al., 2001: L-E Rats, Relative Liver Weight	E-308

E.3.10.1. Summary Table of BMDS Modeling Results	E-308

E.3.10.2. Output for Selected Model: Hill	E-308

E.3.10.3. Figure for Selected Model: Hill	E-311

E.3.10.4. Output for Additional Model Presented: Hill, Unrestricted	E-311

E.3.10.5. Figure for Additional Model Presented: Hill, Unrestricted	E-314

E.3.11. Franc et al., 2001: S-D Rats, Relative Thymus Weight	E-315

E.3.11.1. Summary Table of BMDS Modeling Results	E-315

This document is a draft for review purposes only and does not constitute Agency policy.

E-ix DRAFT—DO NOT CITE OR QUOTE


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CONTENTS (continued)

E.3.11.2. Output for Selected Model: Exponential (M4)	E-315

E.3.11.3. Figure for Selected Model: Exponential (M4)	E-318

E.3.11.4. Output for Additional Model Presented: Polynomial,

3-Degree	E-318

E.3.11.5. Figure for Additional Model Presented: Polynomial,

3-Degree	E-321

E.3.12. Franc et al., 2001: L-E Rats, Relative Thymus Weight	E-322

E.3.12.1. Summary Table of BMDS Modeling Results	E-322

E.3.12.2. Output for Selected Model: Exponential (M4)	E-322

E.3.12.3. Figure for Selected Model: Exponential (M4)	E-325

E.3.13. Franc et al., 2001: Ft/W Rats, Relative Thymus Weight	E-326

E.3.13.1. Summary Table of BMDS Modeling Results	E-326

E.3.13.2. Output for Selected Model: Exponential (M2)	E-326

E.3.13.3. Figure for Selected Model: Exponential (M2)	E-329

E.3.13.4. Output for Additional Model Presented: Exponential (M4)	E-329

E.3.13.5. Figure for Additional Model Presented: Exponential (M4)	E-332

E.3.14. Hojo et al., 2002: DRL Reinforce Per Minute	E-333

E.3.14.1. Summary Table of BMDS Modeling Results	E-333

E.3.14.2. Output for Selected Model: Linear	E-333

E.3.14.3. Figure for Selected Model: Linear	E-336

E.3.14.4. Output for Additional Model Presented: Exponential (M4)	E-336

E.3.14.5. Figure for Additional Model Presented: Exponential (M4)	E-339

E.3.15. Hojo et al., 2002: DRL Response Per Minute	E-340

E.3.15.1. Summary Table of BMDS Modeling Results	E-340

E.3.15.2. Output for Selected Model: Exponential (M4)	E-340

E.3.15.3. Figure for Selected Model: Exponential (M4)	E-343

E.3.16. Kattainen et al., 2001: 3rd Molar Eruption, Female	E-344

E.3.16.1. Summary Table of BMDS Modeling Results	E-344

E.3.16.2. Output for Selected Model: Log-Logistic	E-344

E.3.16.3. Figure for Selected Model: Log-Logistic	E-346

E.3.16.4. Output for Additional Model Presented: Log-Logistic,

Unrestricted	E-346

E.3.16.5. Figure for Additional Model Presented: Log-Logistic,

Unrestricted	E-348

E.3.17. Kattainen et al., 2001: 3rd Molar Length, Female	E-349

E.3.17.1. Summary Table of BMDS Modeling Results	E-349

E.3.17.2. Output for Selected Model: Hill	E-349

E.3.17.3. Figure for Selected Model: Hill	E-352

E.3.17.4. Output for Additional Model Presented: Hill, Unrestricted	E-352

E.3.17.5. Figure for Additional Model Presented: Hill, Unrestricted	E-355

E.3.18. Keller etal., 2007: Missing Mandibular Molars, CBA J	E-356

E.3.18.1. Summary Table of BMDS Modeling Results	E-356

E.3.18.2. Output for Selected Model: Multistage, 1-Degree	E-356

This document is a draft for review purposes only and does not constitute Agency policy.

E-x DRAFT—DO NOT CITE OR QUOTE


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CONTENTS (continued)

E.3.18.3. Figure for Selected Model: Multistage, 1-Degree	E-358

E.3.19. Kociba et al., 1978: Urinary Coproporphyrin, Females	E-359

E.3.19.1. Summary Table of BMDS Modeling Results	E-359

E.3.19.2. Output for Selected Model: Exponential (M4)	E-359

E.3.19.3. Figure for Selected Model: Exponential (M4)	E-362

E.3.20. Kociba et al., 1978: Uroporphyrin per Creatinine, Female	E-363

E.3.20.1. Summary Table of BMDS Modeling Results	E-363

E.3.20.2. Output for Selected Model: Linear	E-363

E.3.20.3. Figure for Selected Model: Linear	E-366

E.3.21. Latchoumycandane and Mathur, 2002: Sperm Production	E-367

E.3.21.1. Summary Table of BMDS Modeling Results	E-367

E.3.21.2. Output for Selected Model: Hill	E-367

E.3.21.3. Figure for Selected Model: Hill	E-370

E.3.21.4. Output for Additional Model Presented: Hill, Unrestricted	E-370

E.3.21.5. Figure for Additional Model Presented: Hill, Unrestricted	E-373

E.3.22. Li et al., 1997: FSH	E-374

E.3.22.1. Summary Table of BMDS Modeling Results	E-374

E.3.22.2. Output for Selected Model: Power	E-374

E.3.22.3. Figure for Selected Model: Power	E-377

E.3.22.4. Output for Additional Model Presented: Power, Unrestricted ..E-377
E.3.22.5. Figure for Additional Model Presented: Power, Unrestricted...E-380

E.3.23. Li et al., 2006: Estradiol, 3-Day	E-381

E.3.23.1. Summary Table of BMDS Modeling Results	E-381

E.3.23.2. Output for Selected Model: Linear	E-381

E.3.23.3. Figure for Selected Model: Linear	E-384

E.3.24. Li et al., 2006: Progesterone, 3-Day	E-385

E.3.24.1. Summary Table of BMDS Modeling Results	E-385

E.3.24.2. Output for Selected Model: Exponential (M4)	E-385

E.3.24.3. Figure for Selected Model: Exponential (M4)	E-388

E.3.24.4. Output for Additional Model Presented: Hill, Unrestricted	E-388

E.3.24.5. Figure for Additional Model Presented: Hill, Unrestricted	E-391

E.3.25. Markowski et al., 2001: FR10 Run Opportunities	E-392

E.3.25.1. Summary Table of BMDS Modeling Results	E-392

E.3.25.2. Output for Selected Model: Exponential (M2)	E-392

E.3.25.3. Figure for Selected Model: Exponential (M2)	E-395

E.3.26. Markowski et al., 2001: FR2 Revolutions	E-396

E.3.26.1. Summary Table of BMDS Modeling Results	E-396

E.3.26.2. Output for Selected Model: Hill	E-396

E.3.26.3. Figure for Selected Model: Hill	E-399

E.3.26.4. Output for Additional Model Presented: Power, Unrestricted ..E-399
E.3.26.5. Figure for Additional Model Presented: Power, Unrestricted...E-402

E.3.27. Markowski et al., 2001: FR5 Run Opportunities	E-403

E.3.27.1. Summary Table of BMDS Modeling Results	E-403

This document is a draft for review purposes only and does not constitute Agency policy.

E-xi DRAFT—DO NOT CITE OR QUOTE


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CONTENTS (continued)

E.3.27.2. Output for Selected Model: Hill	E-403

E.3.27.3. Figure for Selected Model: Hill	E-406

E.3.27.4. Output for Additional Model Presented: Power, Unrestricted ..E-407
E.3.27.5. Figure for Additional Model Presented: Power, Unrestricted...E-409

E.3.28. Miettinen et al., 2006: Cariogenic Lesions, Pups	E-410

E.3.28.1. Summary Table of BMDS Modeling Results	E-410

E.3.28.2. Output for Selected Model: Log-Logistic	E-410

E.3.28.3. Figure for Selected Model: Log-Logistic	E-412

E.3.28.4. Output for Additional Model Presented: Log-Logistic,

Unrestricted	E-412

E.3.28.5. Figure for Additional Model Presented: Log-Logistic,

Unrestricted	E-414

E.3.29. Murray et al., 1979: Fertility in F2 Generation	E-415

E.3.29.1. Summary Table of BMDS Modeling Results	E-415

E.3.29.2. Output for Selected Model: Multistage, 2-Degree	E-415

E.3.29.3. Figure for Selected Model: Multistage, 2-Degree	E-417

E.3.30. National Toxicology Program, 1982: Toxic Hepatitis, Male Mice	E-418

E.3.30.1. Summary Table of BMDS Modeling Results	E-418

E.3.30.2. Output for Selected Model: Multistage, 3-Degree	E-418

E.3.30.3. Figure for Selected Model: Multistage, 3-Degree	E-420

E.3.31. National Toxicology Program, 2006: Alveolar Metaplasia	E-421

E.3.31.1. Summary Table of BMDS Modeling Results	E-421

E.3.31.2. Output for Selected Model: Log-Logistic	E-421

E.3.31.3. Figure for Selected Model: Log-Logistic	E-423

E. 3.31.4. Output for Additi onal Model Pre sented: Log-Logi sti c,

Unrestricted	E-423

E.3.31.5. Figure for Additional Model Presented: Log-Logistic,

Unrestricted	E-425

E.3.32. National Toxicology Program, 2006: Eosinophilic Focus, Liver	E-426

E.3.32.1. Summary Table of BMDS Modeling Results	E-426

E.3.32.2. Output for Selected Model: Probit	E-426

E.3.32.3. Figure for Selected Model: Probit	E-428

E.3.33. National Toxicology Program, 2006: Fatty Change Diffuse, Liver	E-429

E.3.33.1. Summary Table of BMDS Modeling Results	E-429

E.3.33.2. Output for Selected Model: Weibull	E-429

E.3.33.3. Figure for Selected Model: Weibull	E-431

E.3.34. National Toxicology Program, 2006: Gingival Hyperplasia, Squamous, 2

Years	E-432

E.3.34.1. Summary Table of BMDS Modeling Results	E-432

E.3.34.2. Output for Selected Model: Log-Logistic	E-432

E.3.34.3. Figure for Selected Model: Log-Logistic	E-434

E.3.34.4. Output for Additional Model Presented: Log-Logistic,

Unrestricted	E-434

This document is a draft for review purposes only and does not constitute Agency policy.

E-xii DRAFT—DO NOT CITE OR QUOTE


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CONTENTS (continued)

E.3.34.5. Figure for Additional Model Presented: Log-Logistic,

Unrestricted	E-436

E.3.35. National Toxicology Program, 2006: Hepatocyte Hypertrophy,

2 Years	E-437

E.3.35.1. Summary Table of BMDS Modeling Results	E-437

E.3.35.2. Output for Selected Model: Multistage, 5-Degree	E-437

E.3.35.3. Figure for Selected Model: Multistage, 5-Degree	E-439

E.3.36. National Toxicology Program, 2006: Necrosis, Liver	E-440

E.3.36.1. Summary Table of BMDS Modeling Results	E-440

E.3.36.2. Output for Selected Model: Log-Probit, Unrestricted	E-440

E.3.36.3. Figure for Selected Model: Log-Probit, Unrestricted	E-442

E.3.37. National Toxicology Program, 2006: Oval Cell Hyperplasia	E-443

E.3.37.1. Summary Table of BMDS Modeling Results	E-443

E.3.37.2. Output for Selected Model: Probit	E-443

E.3.37.3. Figure for Selected Model: Probit	E-445

E.3.37.4. Output for Additional Model Presented: Weibull	E-445

E.3.37.5. Figure for Additional Model Presented: Weibull	E-447

E.3.38. National Toxicology Program, 2006: Pigmentation, Liver	E-448

E.3.38.1. Summary Table of BMDS Modeling Results	E-448

E.3.38.2. Output for Selected Model: Log-Probit	E-448

E.3.38.3. Figure for Selected Model: Log-Probit	E-450

E.3.39. National Toxicology Program, 2006: Toxic Hepatopathy	E-451

E.3.39.1. Summary Table of BMDS Modeling Results	E-451

E.3.39.2. Output for Selected Model: Multistage, 5-Degree	E-451

E.3.39.3. Figure for Selected Model: Multistage, 5-Degree	E-453

E.3.40. Ohsako et al., 2001: Ano-Genital Length, PND 120	E-454

E.3.40.1. Summary Table of BMDS Modeling Results	E-454

E.3.40.2. Output for Selected Model: Hill	E-454

E.3.40.3. Figure for Selected Model: Hill	E-457

E.3.40.4. Output for Additional Model Presented: Hill, Unrestricted	E-457

E.3.40.5. Figure for Additional Model Presented: Hill, Unrestricted	E-460

11.3.41.	Sewall et al., 1995: T4 In Serum	11-461

E.3.41.1. Summary Table of BMDS Modeling Results	E-461

E.3.41.2. Output for Selected Model: Hill	E-461

E.3.41.3. Figure for Selected Model: Hill	E-464

E.3.41.4. Output for Additional Model Presented: Hill, Unrestricted	E-464

E.3.41.5. Figure for Additional Model Presented: Hill, Unrestricted	E-467

11.3.42.	Shi et al., 2007: Estradiol 17B, PE9	11-468

E.3.42.1. Summary Table of BMDS Modeling Results	E-468

E.3.42.2. Output for Selected Model: Exponential (M4)	E-468

E.3.42.3. Figure for Selected Model: Exponential (M4)	E-471

11.3.43.	Smialowicz et al., 2008: PFC per 10 6 Cells	11-472

E.3.43.1. Summary Table of BMDS Modeling Results	E-472

This document is a draft for review purposes only and does not constitute Agency policy.

E-xiii DRAFT—DO NOT CITE OR QUOTE


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CONTENTS (continued)

E.3.43.2. Output for Selected Model: Power, Unrestricted	E-472

E.3.43.3. Figure for Selected Model: Power, Unrestricted	E-475

E.3.43.4. Output for Additional Model Presented: Power	E-475

E.3.43.5. Figure for Additional Model Presented: Power	E-478

E.3.44. Smialowicz et al., 2008: PFC per Spleen	E-479

E.3.44.1. Summary Table of BMDS Modeling Results	E-479

E.3.44.2. Output for Selected Model: Power, Unrestricted	E-479

E.3.44.3. Figure for Selected Model: Power, Unrestricted	E-482

E.3.44.4. Output for Additional Model Presented: Power	E-482

E.3.44.5. Figure for Additional Model Presented: Power	E-485

E.3.45. Toth et al., 1979: Amyloidosis	E-486

E.3.45.1. Summary Table of BMDS Modeling Results	E-486

E.3.45.2. Output for Selected Model: Log-Logistic	E-486

E.3.45.3. Figure for Selected Model: Log-Logistic	E-488

E.3.45.4. Output for Additional Model Presented: Log-Logistic,

Unrestricted	E-488

E.3.45.5. Figure for Additional Model Presented: Log-Logistic,

Unrestricted	E-490

E.3.46. Toth et al., 1979: Skin Lesions	E-491

E.3.46.1. Summary Table of BMDS Modeling Results	E-491

E.3.46.2. Output for Selected Model: Logistic	E-491

E.3.46.3. Figure for Selected Model: Logistic	E-493

E.3.46.4. Output for Additional Model Presented: Log-Logistic,

Unrestricted	E-493

E.3.46.5. Figure for Additional Model Presented: Log-Logistic,

Unrestricted	E-495

E.3.47. Van Birgelen et al., 1995a: Hepatic Retinol	E-496

E.3.47.1. Summary Table of BMDS Modeling Results	E-496

E.3.47.2. Output for Selected Model: Exponential (M4)	E-496

E.3.47.3. Figure for Selected Model: Exponential (M4)	E-499

E.3.47.4. Output for Additional Model Presented: Power, Unrestricted ..E-499
E.3.47.5. Figure for Additional Model Presented: Power, Unrestricted...E-502

E.3.48. Van Birgelen et al., 1995a: Hepatic Retinol Palmitate	E-503

E.3.48.1. Summary Table of BMDS Modeling Results	E-503

E.3.48.2. Output for Selected Model: Linear	E-503

E.3.48.3. Figure for Selected Model: Linear	E-506

E.3.48.4. Output for Additional Model Presented: Power, Unrestricted ..E-506
E.3.48.5. Figure for Additional Model Presented: Power, Unrestricted...E-509

E.3.49. White et al., 1986: CH50	E-510

E.3.49.1. Summary Table of BMDS Modeling Results	E-510

E.3.49.2. Output for Selected Model: Hill	E-510

E.3.49.3. Figure for Selected Model: Hill	E-513

E.3.49.4. Output for Additional Model Presented: Hill, Unrestricted	E-513

This document is a draft for review purposes only and does not constitute Agency policy.

E-xiv DRAFT—DO NOT CITE OR QUOTE


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CONTENTS (continued)

E.3.49.5. Figure for Additional Model Presented: Hill, Unrestricted	E-516

E.4. REFERENCES	E-517

E-xv DRAFT—DO NOT CITE OR QUOTE

This document is a draft for review purposes only and does not constitute Agency policy.


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1	APPENDIX E. NONCANCER BENCHMARK DOSE MODELING

2

3

4	E.l. BMDS INPUT TABLES

5	E.l.l. Amin et al. (2000)

Endpointc

Administered Dose (ng/kg-day)

0

25 a

100

Internal Dose (ng/kg blood) b

0

3.38

10.57

(n = 10)

(n = 10)

(n = 10)

Saccharin consumed, female rats (0.25%)
(ml saccharin solution/100 g body weight)0

31.67 ±6.53

24.60 ±3.79

10.70 ± 1.68

Saccharin consumed, female rats (0.50%)
(ml saccharin solution/100 g body weight)0

22.40 ±5.05

11.38 ±2.42

4.54 ± 1.05

Saccharin preference ratio, female rats (0.25%) (ratio
of saccharin solution consumed to total fluid
consumed) d

82.14 ±4.22

58.12 ± 10.71

54.87 ±6.17

Saccharin preference ratio, female rats (0.50%) (ratio
of saccharin solution consumed to total fluid
consumed) d

72.73 ± 7.79

44.48 ± 10.39

33.77 ±7.79

aLOAEL identified.

bFrom the Emond PBPK model described in 3.3.

0 Values are the mean ± SE. Data obtained from Figure 2 in Amin et al. 2000.
d Values are the ratio ± SE. Data obtained from Figure 3 in Amin et al. 2000.

6

7

8	E.1.2. Bell et al. (2007)



Administered Dose (ng/kg-day)



0

2.4 a

8

46



Internal Dose (ng/kg blood) b



0

2.20

5.14

18.41

Endpoint

(n = 30)

(n = 30)

(n = 30)

(n = 30)

Proportion of male rat pups that had not
undergone balano-preputial separation on
PND 49 0

1/30 (3%)

5/30 (17%)

6/30 (20%)

15/30 (50%)

aLOAEL identified.

b From the Emond PBPK model described in 3.3.
0 Data obtained from Figure 2 in Bell et al. 2007.

This document is a draft for review purposes only and does not constitute Agency policy.

E-l	DRAFT—DO NOT CITE OR QUOTE


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l E.1.3. Cantoni et al. (1981)

Endpoint

Administered Dose (ng/kg-day)

0

1.43 a

14.3

143

Internal Dose (ng/kg blood) b

0

1.85

8.84

50.05

(n = 4)

(n = 4)

(n = 3)

(n = 3)

Urinary coproporphyria in female
rats (|ig coproporphyrin methyl
ester/24 hr) at 3 months0

0.74 ±0.17

1.81 ± 0.42 d

2.73 ± 0.75 e

3.00 ± 1.30 e

Urinary porphyrins in rats
(nmol/24 hr) after 45 weeks 0

2.27 ±0.49

5.55 ± 0.85 d

7.62 ± 1.79 d

196.89 ± 63.14 e

aLOAEL identifed.

bFrom the Emond PBPK model described in 3.3.

0 Values are the mean ± SE. Data for urinary coproporphyria and urinary porphyrins obtained from Figure 1 and
Table 1, respectively, in Cantoni et al. 1981.
d Statistically significant as compared to control (p < 0.05).
e Statistically significant as compared to control (p < 0.01).

2

3

4	E.1.4. Crofton et al. (2005)



Administered Dose (ng/kg-day)



0

0.1

3

10

30 a

100"

300

1,000

3,000

10,000



Internal Dose (ng/kg blood) c



0

0.02

0.49

1.38

3.46

9.26

23.07

65.65

180.90

583.48

Endpoint

(n = 14)

(n = 6)

(n = 12)

(n = 6)

(n = 6)

(n = 6)

(n = 6)

(n = 6)

(n = 6)

(n = 4)

Serum T4 in female
rats

(% control) d

100.00 ±

96.27 ±

98.57 ±

99.76 ±

93.32 ±

70.94 ±

62.52 ±

52.68 ±

54.66 ±

49.15 ±

15.44

14.98

18.11

19.04

12.11

12.74

14.75

22.73

19.71

11.15

aNOAEL identifed.
bLOAEL identifed.

0 From the Emond PBPK model described in 3.3.

d Values are the mean ± SD. Data were obtained from a Crofton et al. supplemental file, available at
http://ehp.niehs.nih.gov/docs/2005/8195/supplemental.pdf.

This document is a draft for review purposes only and does not constitute Agency policy.

E-2	DRAFT—DO NOT CITE OR QUOTE


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l E.1.5. DeCaprio et al. (1986)

Endpoint

Administered Dose (ng/kg-day)

0

0.12

0.61 a

4.9 b

26

Internal Dose (ng/kg blood)c

n/a

n/a

n/a

n/a

n/a

(n = 10)

(n = 10)

(n = 11)

(n = 10)

(n = 4)

Absolute kidney weight (g),
males d

5.49 ±0.17

5.14 ± 0.12

4.71 ±0.12

4.3 ± 0.15 f

-

Absolute thymus weight (g),
males d

0.56 ±0.050

0.45 ±0.022

0.44 ±0.034

0.35 ± 0.167 g

-

Body weight (g), males e

713 ± 15

682 ± 16

651 ± 19

603 ± 20 f

433 ± 38 h

Relative brain weight, males d

0.54 ±0.015

0.56 ±0.016

0.6 ±0.016

0.65 ± 0.016 f

-

Relative liver weight,
males d

4.54 ±0.23

4.1 ±0.14

5.36 ±0.61

5.63±0.29 f

-

Relative thymus weight, males d

0.078 ±
0.006

0.066 ± 0.003

0.068 ± 0.004

0.06±0.003 f

-

Endpoint

Administered Dose (ng/kg-day)

0

0.12

0.68

4.86

31

Internal Dose (ng/kg blood)c

0

n/a

n/a

n/a

n/a

(n = 8)

(n = 10)

(n = 9)

(n = 10)

(n = 4)

Body weight (g), females e

602 ± 12

583 ± 22

570 ± 22

531± 14f

351± 49 h

Relative liver weight, females d

4.3 ±0.26

4.49 ±0.35

4.27 ±0.16

5.54 ±0.43 f

-

aNOAEL identified.
bLOAEL identified.

0 Internal dose not calculated using the Emond PBPK (guinea pigs).

dOrgan weight data in guinea pigs obtained from Table 2 of DeCaprio et al. 1986. Values are the mean ± SE.

Relative organs weights were calculated as organ weight (g) / body weight (g) X 100.

eBody weight data in guinea pigs obtained from Table 1 of DeCaprio et al. 1986. Values are the mean ± SE.

Statistically significant as compared to control (p < 0.05).

8 Statistically significant as compared to control (p < 0.01).

h Statistically significant as compared to control (p < 0.001).

This document is a draft for review purposes only and does not constitute Agency policy.

E-3	DRAFT—DO NOT CITE OR QUOTE


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l E.1.6. Franc et al. (2001)

Endpoint

Administered Dose (ng/kg-day)

0

10 a

30 b

100

Internal Dose (ng/kg blood)c

0

6.59

14.48

36.43

(n = 8)

(n = 8)

(n = 8)

(n = 8)

S-D rats, relative liver weightd

100.0 ±5.0

108.1 ± 6.0 e

116.8 ± 9.2 e

155.3 ± 10.9 e

L-E rats, relative liver weightd

100.0 ±3.5

106.3 ±6.3

116.8 ± 3.2 e

122.2 ± 7.0 e

S-D rats, relative thymus weightd

100.2 ±29.4

91.2 ± 17.0

51.4 ± 15.4 e

22.8 ± 10.6 e

L-E rats, relative thymus weightd

103.4 ± 19.3

95.4 ±24.9

38.7 ± 17.0 e

35.0 ± 27.6 e

HAV rats, relative thymus weightd

101.2 ± 12.7

97.5 ± 11.7.0

71.0 ± 8.5 e

49.3 ± 15.4 e

aNOAEL identified.
bLOAEL identified.

0 From the Emond PBPK model described in 3.3.

d Values are the mean ± SE. Data obtained from Figure 5 in Franc et al. 2001.
e Statistically significant as compared to control (p < 0.05).

2

3

4	E.1.7. Hojo et al. (2002)

Endpoint

Administered Dose (ng/kg-day)

0

20 a

60

180

Internal Dose (ng/kg blood) b

0

1.62

4.17

10.70

(n = 5)

(n = 5)

(n = 6)

(n = 5)

DRL reinforcements/min, rat litters0

-0.814 ±0.45

-0.364 ± 0.82

0.374 ±0.54

-0.163 ±0.44

DRL responses/min, rat litters 0

18.44 ±7.99

-0.99 ± 10.96

-4.52 ±7.19

-0.41 ± 15.23

aLOAEL identified.

bFrom the Emond PBPK model described in 3.3.

0 DRL = differential reinforcement of low rate. Values are the mean ± SD. Data obtained from Table 5 in Hojo et
al. 2002.

5

This document is a draft for review purposes only and does not constitute Agency policy.

E-4	DRAFT—DO NOT CITE OR QUOTE


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l E.1.8. Kattainen et al. (2001)

Endpoint

Administered Dose (ng/kg-day)

0

30 a

100

300

1,000

Internal Dose (ng/kg blood) b

0

2.23

6.25

16.08

46.86

(n = 16)

(n = 17)

(n = 15)

(n = 12)

(n = 19)

3rd molar mesio-distal
length in female rat
offspring (molar
development) (mm)0

1.86 ±0.017

1.58 ± 0.045 e

1.6 ± 0.069 e

1.5 ± 0.064 e

1.35 ± 0.118 e

Proportion of female rat
offspring without 3rd molar
eruption on PND 35 d

1/16 (10%)

3/17 (20%)

4/15 (30%)

6/12 (50%)e

13/19 (70%)e

aLOAEL identified.

bFrom the Emond PBPK model described in 3.3.

0 Values are the mean ± SE. Data were obtained from Figure 3 in Kattainen et al. 2001.
d Data were obtained from Figure 2 in Kattainen et al. 2001.
e Statistically significant as compared to control (p < 0.05).

2

3

4	E.1.9. Keller et al. (2007, 2008a, b)

Endpoint

Administered Dose (ng/kg-day)

0

10 a

100

1,000

Internal Dose (ng/kg blood) b

0

0.54

4.29

34.06

Frequency of missing 3rd mandibular molars in CBA J
mice 0

0/29 (0%)

2/23 (10%)

6/29 (20%)

30/30 (100%)

aLOAEL identified.

bFrom the Emond PBPK model described in 3.3.
0 Data obtained from Table 1 in Keller et al. 2007.

This document is a draft for review purposes only and does not constitute Agency policy.

E-5	DRAFT—DO NOT CITE OR QUOTE


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l E.1.10. Kociba et al. (1978)

Endpoint

Administered Dose (ng/kg-day)

0

la

10 b

100

Internal Dose (ng/kg blood)c

0

1.55

7.15

38.56

(n = 5)

(n = 5)

(n = 5)

(n = 5)

Urinary coproporphyrin
(Hg/48 h), female rats d

9.8 ± 1.3

8.6 ±2

16.4 ± 4.7 e

17.4 ± 4e

|ig uroporphyrin per mg creatinine,
female rats d

0.157 ±0.05

0.143 ±0.037

0.181 ±0.053

0.296 ± 0.074e

aNOAEL identified.
bLOAEL identified.

0 From the Emond PBPK model described in 3.3.

d Values are the mean ± SD. Data obtained from Table 2 in Kociba et al. 1978.
e Statistically significant as compared to control (p < 0.05).

2

3

4	E.l.ll. Latchoumycandane and Mathur (2002)



Administered Dose (ng/kg-day)



0

la

10

100



Internal Dose (ng/kg blood) b



0

0.78

4.65

27.27

Endpoint

(n = 6)

(n = 6)

(n = 6)

(n = 6)

Daily sperm production (/106) in adult
male rats (mg)0

22.19 ±2.67

15.67 ±2.65 d

13.65 ± 2.19 d

13.1 ± 3.16 d

aLOAEL identified.

bFrom the Emond PBPK model described in 3.3.

0 Values are the mean ± SD. Data obtained from Table 1 in Latchoumycandane and Mathur 2002.
d Statistically significant as compared to control (p < 0.05).

5

6

This document is a draft for review purposes only and does not constitute Agency policy.

E-6	DRAFT—DO NOT CITE OR QUOTE


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l E.1.12. Li et al. (1997)

Endpoint

Administered Dose (ng/kg-day)

0

3a

10 b

30

100

300

1,000

3,000

10,000

30,000

Internal Dose (ng/kg blood) c

0

0.27

0.80

2.1

5.87

15

43.33

119.94

385.96

1171.90

(n = 10)

(n =10)

(n = 10)

(n = 10)

(n = 10)

(n = 10)

(n = 10)

(n = 10)

(n = 10)

(n = 10)

Serum FSH (ng/ml)
in female rats d

23.86
±
9.38

22.16
±
15.34

85.23
±
29.83

73.30 ±
15.34

126.14 ±
50.28

132.10 ±
36.65

116.76 ±
16.19

304.26 ±
48.58

346.88 ±
47.73

455.11 ±
90.34

aNOAEL identified.
bLOAEL identified.

0 From the Emond PBPK model described in 3.3.

d Values are the mean ± SE. Data obtained from Figure 3 in Li et al. 1997.

2

3

4	E.1.13. Li et al. (2006)

Endpoint

Administered Dose (ng/kg-day)

0

2a

50

100

Internal Dose (ng/kg blood) b

0

0.16

2.84

5.12

(n = 10)

(n = 10)

(n = 10)

(n = 10)

Serum estradiol/(pg-ml)_1 in female

mice

(l~3d)c

10.17 ±3.85

19.91 ±6.31

24.72 ± 4.60

18.09 ±5.57

Serum progesterone (ng-ml)"1 in
female mice
(l~3d)c

61.74 ±3.51

30.56 ±
12.80 d

16.93 ± 10.53

11.36 ± 13.83

aLOAEL identified.

bFrom the Emond PBPK model described in 3.3.

0 Values are the mean ± SE. Data obtained from Figures 3 (estradiol) and 4 (progesterone) in Li et al. 2006.
d Statistically significant as compared to control (p < 0.01).

This document is a draft for review purposes only and does not constitute Agency policy.

E-7	DRAFT—DO NOT CITE OR QUOTE


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l E.1.14. Markowski et al. (2001)

Endpoint

Administered Dose (ng/kg-day)

0

20 a

60

180

Internal Dose (ng/kg blood) b

0

1.56

4.03

10.32

(n = 7)

(n = 4)

(n = 6)

(n = 7)

FR10 earned run opportunities, adult
female offspring0

13.29 ±8.65

11.25 ±5.56

5.75 ±3.53

7 ±6.01

FR2 total revolutions, adult female
offspring0

119.29 ±69.9

108.5 ±61

56.5 ±31.21

68.14 ±33.23

FR5 earned run opportunities, adult
female offspring0

26.14 ± 12.28

23.5 ±7.04

12.8 ±6.17

13.14 ± 7.14

aLOAEL identified.

bFrom the Emond PBPK model described in 3.3.

0 Values are the mean ± SD. Data obtained from Table 3 in Markowski et al. 2001.

2

3

4	E.1.15. Miettinen et al. (2006)

Endpoint

Administered Dose (ng/kg-day)

0

30 a

100

300

1,000

Internal Dose (ng/kg blood) b

0

2.22

6.23

16.01

46.64

(n = 42)

II

(n = 15)

(n = 24)

II

Cariogenic lesions in rat pups 0

25/42 (60%)

23/29 (79%) d

19/25 (76%)

20/24
(83%) d

29/32
(91%) d

aLOAEL identified.

bFrom the Emond PBPK model described in 3.3.

0 Data obtained from Table 2 in Miettinen et al. 2006.
d Statistically significant as compared to control (p < 0.05).

5

6

This document is a draft for review purposes only and does not constitute Agency policy.

E-8	DRAFT—DO NOT CITE OR QUOTE


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l E.1.16. National Toxicology Program (1982)



Administered Dose (ng/kg-day)



0

1.43 a

7.14

71.4



Internal Dose (ng/kg blood) b



0

0.77

2.27

11.24

Endpoint

r-
II

3,

(n = 49)

(n = 49)

(n = 50)

Numbers of male mice with toxic
hepatitis 0

1/73 (1.4%)

5/49 (10%)

3/49 (6.1%)

44/50 (88%)

aLOAEL identified.

bFrom the Emond PBPK model described in 3.3.
0 Data obtained from Table 11 inNTP 1982.

This document is a draft for review purposes only and does not constitute Agency policy.

E-9	DRAFT—DO NOT CITE OR QUOTE


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l E.1.17. National Toxicology Program (2006)

Endpointe

Administered Dose (ng/kg-day)

0

2.14 a

7.14

15.7

32.9

71.4

Internal Dose (ng/kg blood) b

0

2.56

5.69

9.79

16.57

29.70

(n = 10)

(n = 10)

(n = 10)

(n = 10)

(n = 10)

(n = 10)

Gingival squamous hyperplasia

1/53 (2%)

7/54
(13%)d

14/53
(26%)°

13/53
(25%)°

15/53
(28%)°

16/53
(30%)°

Liver, hepatocyte hypertrophy

0/53
(0%)

19/54
(40%)°'

19/53
(40%)°

42/53
(80%)°

41/53
(80%)°

52/53
(100%)°

Heart, cardiomyopathy

10/53
(19%)

12/54
(22%)

22/53°
(42%)

25/52°
(48%)

32/53°
(60%)

36/52°
(69%)

Liver, eosinophilic focus, multiple

3/53
(6%)

8/54
(15%)

14/53
(26%)

17/53
(32%)

22/53
(42%)

42/53
(79%)

Liver, fatty change, diffuse

0/53
(0%)

2/54
(4%)

12/53°
(23%)

17/53°
(32%)

30/53°
(57%)

48/53°
(91%)

Liver, necrosis

1/53
(2%)

4/54
(7%)

4/53
(8%)

8/5 3 d
(15%)

10/53°
(19%)

17/53°
(32%)

Liver, pigmentation

4/53
(8%)

9/54
(17%)

34/53°
(64%)

48/53°
(91%)

52/53°
(98%)

53/53°
(100%)

Liver, toxic hepatopathy

0/53
(0%)

2/54
(4%)

8/53
(15%)

30/53
(57%)

45/50
(85%)

53/53
(100%)

Oval cell hyperplasia

0/53
(0%)

4/54
(10%)d

3/53
(10%)

20/53
(40%)°

38/53
(70%)d

53/53
(100%)°

Lung, alveolar to bronchiolar
epithelial metaplasia (Alveolar
epithelium, metaplasia, bronchiolar)

2/53
(4%)

19/54 c
(35%)

33/53°
(62%)

35/52°
(67%)

45/53°
(85%)

46/52°
(89%)

aLOAEL identified.

bFrom the Emond PBPK model described in 3.3.

0 Statistically significant as compared to control (p < 0.01).
d Statistically significant as compared to control (p < 0.05).

e Data are for female rats in 2-year gavage study. Data for all endpoints obtained from Table A5b in NTP 2006.

This document is a draft for review purposes only and does not constitute Agency policy.

E-10	DRAFT—DO NOT CITE OR QUOTE


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l E.1.18. Ohsako et al. (2001)

Endpoint

Administered Dose (ng/kg-day)

0

12.5 a

50 b

200

800

Internal Dose (ng/kg blood)c

0

1.04

3.47

11.36

38.42

(n = 12)

(n = 10)

(n = 10)

(n = 10)

(n = 12)

Anogenital distance (mm) in male
rat offspring, PND120 d

28.91 ±0.90

27.94 ±0.79

25.17 ± 1.02 e

26.01 ±0.90 f

23.80 ±0.45 e

aNOAEL for selected endpoint.
bLOAEL for selected endpoint.

0 From the Emond PBPK model described in 3.3.

d Values are the mean ± SE. Data obtained from Figure 7 in Ohsako et al. 2001.
e Statistically significant as compared to control (p < 0.01).

Statistically significant as compared to control (p < 0.05).

2

3

4	E.1.19. Shi et al. (2007)

Endpoint

Administered Dose (ng/kg-day)

0

0.143 a

0.714 b

7.14

28.6

Internal Dose (ng/kg blood)c

0

0.34

1.07

5.23

13.91

(n = 10)

(n = 10)

(n = 10)

(n = 10)

(n = 10)

Serum estradiol - 17(3 at proestrus
9 in female rats at 9 mo.of age
(pg/ml) d

102.86 ± 13.10

86.19 ±6.19

63.33 ± 9.29 e

48.1 ± 5.95 e

38.57 ± 7.14 e

aNOAEL identified.
bLOAEL identified.

0 From the Emond PBPK model described in 3.3.

d Values are the mean ± SE. Data obtained from Figure 4 in Shi et al. 2007.
e Statistically significant as compared to control (p < 0.05).

This document is a draft for review purposes only and does not constitute Agency policy.

E-l 1	DRAFT—DO NOT CITE OR QUOTE


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l E.1.20. Smialowicz et al. (2008)

Endpoint

Administered Dose (ng/kg-day)

0

1.07 a

10.7

107

321

Internal Dose (ng/kg blood) b

0

0.44

2.46

13.40

31.65

(n = 15)

(n = 14)

(n = 15)

(n = 15)

(n = 8)

PFC per 106 cells in female
mice 0

1491 ±716

1129±171d

945±516d

677 ± 465 d

161± 117d

PFC x 104 per spleen in female
mice 0

27.8 ± 13.4

21 ± 13.6 d

17.6 ± 9.4 d

12.6 ± 8.7 d

3.0 ±3.1 d

aLOAEL identified.

bFrom the Emond PBPK model described in 3.3.

0 Values are the mean ± SD. Data obtained from Table 4 in Smialowicz et al. 2008.
d Statistically significant as compared to control (p < 0.05).

2

3

4	E.1.21. Toth et al. (1979)

Endpoint

Administered Dose (ng/kg-day)

0

la

100

1,000

Internal Dose (ng/kg blood) b

0

0.57

14.21

91.21

(n =38)

(n = 44)

(n = 44)

(n = 43)

Number with amyloidosis plus skin
lesions in mice 0

0/38 (0%)

5/44(11%)

10/44 (23%)

17/43 (40%)

Number with skin lesions in mice 0

0/38 (0%)

5/44(11%)

13/44 (30%)

25/43 (58%)

aLOAEL identified.

bFrom the Emond PBPK model described in 3.3.
0 Data obtained from Table 2 in Toth et al. 1979.

5

6

This document is a draft for review purposes only and does not constitute Agency policy.

E-12	DRAFT—DO NOT CITE OR QUOTE


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l E.1.22. Van Birgelen et al. (1995)

Endpoint

Administered Dose (ng/kg-day)

0

14

26

47

320

1,024

Internal Dose (ng/kg blood) b

0

7.20

11.76

18.09

86.41

250.16

n = 8

n = 8

n = 8

n = 8

n = 8

n = 8

Hepatic retinol (mg/g liver) in
female rats0

14.9 ±3.1

8.4 ± 1.2 d

8.2 ± 0.8 d

5.1 ± 0.3 d

2.2 ± 0.3 d

0.6 ± 0.2 d

Hepatic retinol palmitate
(mg/g liver) in female rats 0

472 ± 96

94 ± 24 d

107 ± 27 d

74 ± 14 d

22 ± 8 d

3 ± 1d

Plasma FT4 (pmol/liter) in
female rats0

23.4 ± 1.1

24.5 ±2.0

22.4 ± 1.0

19.3 ±3.3

16.3 ± 1.5 d

10.3 ± 1.7 d

Plasma TT4 (nmol/liter) in
female rats0

40.9 ±2.4

41.4 ± 1.9

41.4 ±2.3

32.3 ± 2.6 d

33.6 ± 2.2 d

25.5 ± 2.7 d

aLOAEL identified.

bFrom the Emond PBPK model described in 3.3.

0 Values are the mean ± SE. Data obtained from Table 3 in Van Birgelen et al. 1995.
d Statistically significant as compared to control (p < 0.05).

2

3

4	E.1.23. White et al. (1986)

Endpoint

Administered Dose (ng/kg-day)

0

10 a

50

100

500

1,000

2,000

Internal Dose (ng/kg blood) b

0

1.09

4.08

7.14

26.81

48.72

90.56

(n = 8)

(n = 8)

(n = 8)

(n = 8)

(n = 8)

(n = 8)

(n = 8)

CH50 (U/ml) in
female mice 0

91 ± 5

54 ± 3 d

63 ± 4d

56 ± 9 d

41 ± 6 d

32 ±6 d

17 ± 6 d

aLOAEL identified.

bFrom the Emond PBPK model described in 3.3.

0 Values are the mean ± SE. Data obtained from Table 1 in White et al. 1986.
d Statistically significant as compared to control (p < 0.05).

This document is a draft for review purposes only and does not constitute Agency policy.

E-13	DRAFT—DO NOT CITE OR QUOTE


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1

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3

4

5

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7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

E.2. ALTERNATE DOSE: WHOLE BLOOD BMDS RESULTS
E.2.1. Amin et al., 2000: 0.25% Saccharin Consumed, Female
E.2.1.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

xV

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

linear b

1

0.551

179.214

9.147E+00

6.094E+00



polynomial, 2-
degree

1

0.551

179.214

9.147E+00

6.094E+00



power

1

0.551

179.214

9.147E+00

6.094E+00

power bound hit (power =1)

power,
unrestricted0

0

N/A

180.858

8.367E+00

3.419E+00

unrestricted (power = 0.736)

a Non-constant variance model selected (p = 0.0005)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.2.1.2. Output for Selected Model: Linear

Amin et al., 2000: 0.25% Saccharin Consumed, Female

Polynomial Model. (Version: 2.13; Date: 04/08/2008)

Input Data File: C:\l\Blood\l_Amin_2000_25_SC_Linear_l.(d)

Gnuplot Plotting File: C:\l\Blood\l_Amin_2 000_25_SC_Linear_l.plt

Mon Feb 08 10:44:22 2010

The form of the response function is:

Y[dose] = beta_0 + beta_l*dose + beta_2*dose/N2 + ...

Dependent variable = Mean
Independent variable = Dose

Signs of the polynomial coefficients are not restricted

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)
Total number of dose groups = 3

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial
lalpha =
rho =
beta_0 =
beta 1 =

Parameter Values
5.29482
0

31. 5112
-1.97726

This document is a draft for review purposes only and does not constitute Agency policy.

E-14	DRAFT—DO NOT CITE OR QUOTE


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9

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13

14

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16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

55

56

57

58

59

60

61

62

63

64

65

66

67

68

69

70

Asymptotic Correlation Matrix of Parameter Estimates

lalpha
rho
beta_0
beta 1

lalpha
1

-0. 99
-0.029
0. 044

rho

-0. 99
1

0. 026
-0. 04

beta_0

-0.029
0. 026
1

-0. 94

beta_l

0. 044
-0. 04
-0. 94
1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
lalpha
rho
beta_0
beta 1

Estimate

-2.54215
2 .40985
31.2644
-1.9414

Std. Err.

1.65048
0.541771
4 .1929
0. 436071

Lower Conf. Limit
-5.77702
1.34799
23.0464
-2.79609

Upper Conf. Limit

0.692726
3. 4717
39.4823
-1. 08672

Table of Data and Estimated Values of Interest

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0 10
3.378 10
10.57 10

31. 7

24 . 6
10.7

31. 3

24 . 7
10.8

20.6
12
5.33

17 . 8
13. 4
4 . 91

0.0727
-0.0264
-0.0362

Model Descriptions for likelihoods calculated

Model A1:	Yij

Var{e(ij ) }

Model A2:	Yij

Var{e(ij ) }

Mu(i) + e(ij ;
Sigma/N2

Mu(i) + e(ij ;

Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi

Var{e(i)}

Mu + e(i)
Sigma/N2

Likelihoods of Interest

Model
A1

A2
A3

fitted
R

Log(likelihood)
-92.841935
-85.255316
-85.429148
-85.606998
-98.136607

Param's

4
6

5
4
2

AIC

193.683870
182.510632
180.858295
179.213995

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

This document is a draft for review purposes only and does not constitute Agency policy.

E-15	DRAFT—DO NOT CITE OR QUOTE


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23

24

25

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30

31

32

33

34

35

36

37

38

39

40

Test 3: Are variances adequately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.)

Tests of Interest

Test -2*log(Likelihood Ratio) Test df

p-value

Test 1

Test 2
Test 3
Test 4

25.7626
15.1732
0.347663
0.3557

4
2
1
1

<.0001
0.0005072

0.5554
0.5509

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adequately describe the data

Benchmark Dose Computation

Specified effect

1

Risk Type

Estimated standard deviations from the control mean

Confidence level

0. 95

BMD

9.14709

BMDL

6.09414

This document is a draft for review purposes only and does not constitute Agency policy.

E-16	DRAFT—DO NOT CITE OR QUOTE


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28

E.2.1.3. Figure for Selected Model: Linear

Linear Model with 0.95 Confidence Level

dose

10:44 02/08 2010

E.2.1.4. Output for Additional Model Presented: Power, Unrestricted
Amin et al., 2000: 0.25% Saccharin Consumed, Female

Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\l\Blood\l_Amin_2000_25_SC_Pwr_U_l.(d)

Gnuplot Plotting File: C:\l\Blood\l_Amin_2 000_25_SC_Pwr_U_l.plt

Mon Feb 08 10:44:22 2010

The form of the response function is:
Y[dose] = control + slope * doseApower

Dependent variable = Mean
Independent variable = Dose
The power is not restricted

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-l 7	DRAFT—DO NOT CITE OR QUOTE


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Total number of dose groups = 3

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
lalpha =	5.29482

rho =	0

control =	31.6727

slope =	-2.2195

power =	0.952715

Asymptotic Correlation Matrix of Parameter Estimates

lalpha	rho	control	slope	power

lalpha 1	-0.99	0.34	-0.17	-0.061

rho -0.99	1	-0.42	0.19	0.068

control 0.34	-0.42	1	-0.72	-0.56

slope -0.17	0.19	-0.72	1	0.97

power -0.061	0.068	-0.56	0.97	1

Parameter Estimates

Variable
lalpha
rho
control
slope
power

Estimate
-2 .48291
2 . 38455
32 . 99
-3.91099
0 .735877

Std. Err.

2 . 08669
0. 692047
5. 40754
3.83883
0.350669

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

-6.57274
1.02817
22 .3914
-11.435
0.0485775

1. 60693
3.74094
43.5886
3. 61299
1.42318

Table of Data and Estimated Values of Interest
Dose	N Obs Mean	Est Mean Obs Std Dev Est Std Dev Scaled Res.

0 10 31.7 33	20.6 18.7 -0.223

3.378 10 24.6 23.4	12 12.4 0.302

10.57 10 10.7 10.8	5.33 4.94 -0.08

Warning: Likelihood for fitted model	larger than the Likelihood for model A3.

Model Descriptions for likelihoods calculated

Model A1:	Yij	= Mu(i) + e(iji

Var{e(ij)} = Sigma/'2

Model A2:	Yij	= Mu(i) + e(ij|

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

This document is a draft for review purposes only and does not constitute Agency policy.

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Model R:	Yi = Mu + e(i

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model	Log(likelihood) # Param's	AIC

A1	-92.841935	4	193.683870

A2	-85.255316	6	182.510632

A3	-85.429148	5	180.858295

fitted	-85.429148	5	180.858295

R	-98.136607	2	200.273213

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Test

2

Test

3

Test

4

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	25.7626	4	<.0001

Test 2	15.1732	2	0.0005072

Test 3	0.347663	1	0.5554

Test 4	-8.2423e-013	0	NA

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

NA - Degrees of freedom for Test 4 are less than or egual to 0. The Chi-Sguare
test for fit is not valid

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD = 8.3667 8

BMDL = 3.41906

This document is a draft for review purposes only and does not constitute Agency policy.

E-19	DRAFT—DO NOT CITE OR QUOTE


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l E.2.1.5. Figure for Additional Model Presented: Power, Unrestricted

Power Model with 0.95 Confidence Level

dose

2	10:44 02/08 2010

3

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5	E.2.2. Amin et al., 2000: 0.25% Saccharin Preference Ratio, Female

6	E.2.2.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

xV

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

linear b

1

0.002

227.807

1.162E+01

5.572E+00



polynomial, 2-
degree

1

0.002

227.807

1.162E+01

5.572E+00



power

1

0.002

227.807

1.162E+01

5.572E+00

power bound liit (power = 1)

a Non-constant variance model selected (p = 0.0135)
b Best-fitting model, BMDS output presented in this appendix

7

8

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.2.2.2. Output for Selected Model: Linear

Amin et al., 2000: 0.25% Saccharin Preference Ratio, Female

Polynomial Model. (Version: 2.13; Date: 04/08/2008)

Input Data File: C:\l\Blood\2_Amin_2000_25_SP_Linear_l.(d)

Gnuplot Plotting File: C:\l\Blood\2_Amin_2 000_25_SP_Linear_l.plt

Mon Feb 08 10:44:49 2010

The form of the response function is:

Y[dose] = beta 0 + beta l^dose + beta 2*dose/N2 + ...

Dependent variable = Mean
Independent variable = Dose

Signs of the polynomial coefficients are not restricted

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)
Total number of dose groups = 3

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
lalpha =	6.34368

rho =	0

beta_0 =	7 5.4888

beta~l =	-2.24733

Asymptotic Correlation Matrix of Parameter	Estimates

lalpha rho beta 0	beta 1

lalpha 1 -1 0.22	-0.31

rho -1 1 -0.22	0.31

beta_0 0.22 -0.22 1	-0.77

beta_l -0.31 0.31 -0.77	1

Parameter Estimates

95.0% Wald Confidence Interval

Variable Estimate Std. Err.	Lower Conf. Limit	Upper Conf. Limit

lalpha 3.00523 9.2122	-15.0503	21.0608

rho 0.797764 2.21138	-3.53646	5.13199

beta_0 75.1087 6.74312	61.8924	88.3249

beta_l -2.16469 1.00825	-4.14082	-0.188553

Table of Data and Estimated Values of Interest
Dose	N Obs Mean	Est Mean Obs Std Dev Est Std Dev Scaled Res.

This document is a draft for review purposes only and does not constitute Agency policy.

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0 10	82.1

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10.57 10	54.9

75.1	13.3
67.8 33.9

52.2	19.5

25.2	0.884

24.2	-1.27

21.8	0.383

Model Descriptions for likelihoods calculated

Model A1:	Yij	= Mu(i) + e(ij

Var{e(ij)}	= Sigma^2

Model A2:	Yij	= Mu(i) + e(ij

Var{e(ij)}	= Sigma(i)^2

Model A3:	Yij = Mu(i) + e(1j)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1 -108.574798	4	225.149597

A2 -104.269377	6	220.538754

A3 -105.147952	5	220.295903

fitted -109.903705	4	227.807410

R -112.382522	2	228.765045

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1
Test 2
Test 3
Test 4

16.2263
8.61084
1.75715
9.51151

0.00273
0.0135
0.185
0.002042

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is less than .1. You may want to try a different
model

Benchmark Dose Computation
Specified effect =	1

This document is a draft for review purposes only and does not constitute Agency policy.

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Risk Type	=

Confidence level =
BMD =

Estimated standard deviations from the control mean
0. 95
11.6241

BMDL =	5.57215

E.2.2.3. Figure for Selected Model: Linear

Linear Model with 0.95 Confidence Level

dose

10:44 02/08 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-23	DRAFT—DO NOT CITE OR QUOTE


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E.2.3. Amin et al., 2000: 0.50% Saccharin Consumed, Female
E.2.3.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

X2 P-
Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

linear b

1

0.060

158.591

1.016E+01

6.567E+00



polynomial, 2-
degree

1

0.060

158.591

1.016E+01

6.567E+00



power

1

0.060

158.591

1.016E+01

6.567E+00

power bound hit (power =1)

power,
unrestricted0

0

N/A

157.060

6.567E+00

1.155E+00

unrestricted (power = 0.396)

a Non-constant variance model selected (p = <0.0001)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.2.3.2. Output for Selected Model: Linear

Amin et al., 2000: 0.50% Saccharin Consumed, Female

Polynomial Model. (Version: 2.13; Date: 04/08/2008)

Input Data File: C:\l\Blood\3_Amin_2000_50_SC_Linear_l.(d)

Gnuplot Plotting File: C:\l\Blood\3_Amin_2 000_50_SC_Linear_l.plt

Mon Feb 08 10:45:20 2010

The form of the response function is:

Y[dose] = beta_0 + beta_l*dose + beta_2*dose/N2 + ...

Dependent variable = Mean
Independent variable = Dose

Signs of the polynomial coefficients are not restricted

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)
Total number of dose groups = 3

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial
lalpha =
rho =
beta_0 =
beta 1 =

Parameter Values

4 . 68512
0

20.0631
-1.57142

Asymptotic Correlation Matrix of Parameter Estimates

This document is a draft for review purposes only and does not constitute Agency policy.

E-24	DRAFT—DO NOT CITE OR QUOTE


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lalpha
rho
beta_0
beta 1

lalpha
1

-0. 96
0. 019
-0.0016

rho

-0. 96
1

-0.031
0. 015

beta_0

0. 019
-0.031
1

-0. 96

beta_l

-0.0016
0. 015
-0. 96
1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
lalpha
rho
beta_0
beta 1

Estimate

-0.982115
2.11808
18.6171
-1.33226

Std. Err.

0.982262
0.401166
3.1782
0.322037

Lower Conf. Limit

-2.90731
1. 33181
12.3879
-1.96344

Upper Conf. Limit

0.943084
2.90435
24.8462
-0.70108

Table of Data and Estimated Values of Interest

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0 10
3.378 10
10.57 10

22 . 4
11. 4
4 . 54

18 . 6
14 .1
4 . 54

16

7 . 66
3.33

13.5

10.1
3. 04

0. 873
-0.856
-0.00339

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1 -83.696404	4	175.392808

A2 -73.511830	6	159.023660

A3 -73.530233	5	157.060467

fitted -75.295363	4	158.590726

R -90.294746	2	184.589492

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

Test 3: Are variances adequately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

This document is a draft for review purposes only and does not constitute Agency policy.

E-25	DRAFT—DO NOT CITE OR QUOTE


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Tests of Interest

Test -2*log(Likelihood Ratio) Test df

p-value

Test 1

Test 2
Test 3
Test 4

0. 0368066

33.5658
20.3691

3.53026

4
2
1
1

0.06026

<.0001
<.0001
0.8479

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is less than .1. You may want to try a different
model

Benchmark Dose Computation

Specified effect

1

Risk Type

Estimated standard deviations from the control mean

Confidence level

0. 95

BMD

10.1633

BMDL

6.56742

This document is a draft for review purposes only and does not constitute Agency policy.

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E.2.3.3. Figure for Selected Model: Linear

Linear Model with 0.95 Confidence Level

dose

10:45 02/08 2010

E.2.3.4. Output for Additional Model Presented: Power, Unrestricted
Amin et al., 2000: 0.50% Saccharin Consumed, Female

Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\l\Blood\3_Amin_2000_50_SC_Pwr_U_l.(d)

Gnuplot Plotting File: C:\l\Blood\3_Amin_2 000_50_SC_Pwr_U_l.plt

Mon Feb 08 10:45:20 2010

The form of the response function is:
Y[dose] = control + slope * doseApower

Dependent variable = Mean
Independent variable = Dose
The power is not restricted

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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Total number of dose groups = 3

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

lalpha =	4.68512

rho =	0

control =	22.3564

slope =	-6.53901

power =	0.425213

Asymptotic Correlation Matrix of Parameter Estimates

lalpha	rho	control	slope	power

lalpha 1	-0.96	0.34	-0.31	-0.15

rho -0.96	1	-0.47	0.36	0.15

control 0.34	-0.47	1	-0.81	-0.52

slope -0.31	0.36	-0.81	1	0.92

power -0.15	0.15	-0.52	0.92	1

Parameter Estimates

Variable
lalpha
rho
control
slope
power

Estimate
-0.708629
1.96142
22.6293
-7.10123
0.395571

Std. Err.
1.298
0.529653
4.48416
4.04394
0.168677

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

-3.25267

0.923323
13.8405
-15.0272
0.0649698

1.83541

2.99953
31.4181
0. 824743
0.726173

Table of Data and Estimated Values of Interest
Dose	N Obs Mean	Est Mean Obs Std Dev Est Std Dev Scaled Res.

0 10
3.378 10
10.57 10

22 . 4
11. 4
4 . 54

22 . 6
11.1
4 . 58

16

7 . 66
3.33

15
7.46
3.12

-0.0577
0.105
-0.0475

Degrees of freedom for Test A3 vs fitted

0

Model Descriptions for likelihoods calculated

Model A1:	Yij	= Mu(i) + e(iji

Var{e(ij)} = Sigma/'2

Model A2:	Yij	= Mu(i) + e(ij|

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

This document is a draft for review purposes only and does not constitute Agency policy.

E-28	DRAFT—DO NOT CITE OR QUOTE


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Model R:	Yi = Mu + e(i

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model	Log(likelihood) # Param's	AIC

A1	-83.696404	4	175.392808

A2	-73.511830	6	159.023660

A3	-73.530233	5	157.060467

fitted	-73.530233	5	157.060467

R	-90.294746	2	184.589492

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Test

2

Test

3

Test

4

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	33.5658	4	<.0001

Test 2	20.3691	2	<.0001

Test 3	0.0368066	1	0.8479

Test 4	0	0	NA

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

NA - Degrees of freedom for Test 4 are less than or egual to 0. The Chi-Sguare
test for fit is not valid

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD = 6.56719

BMDL = 1.154 7 6

This document is a draft for review purposes only and does not constitute Agency policy.

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E.2.3.5. Figure for Additional Model Presented: Power, Unrestricted

Power Model with 0.95 Confidence Level

dose

10:45 02/08 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-30	DRAFT—DO NOT CITE OR QUOTE


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E.2.4. Amin et al., 2000: 0.50% Saccharin Preference Ratio, Female
E.2.4.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

X2 P-
Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

linear b

1

0.135

234.250

8.144E+00

5.105E+00



polynomial, 2-
degree

1

0.135

234.250

8.144E+00

5.105E+00



power

1

0.135

234.250

8.144E+00

5.105E+00

power bound hit (power =1)

power,
unrestricted0

0

N/A

234.020

2.598E+00

1.057E-14

unrestricted (power = 0.282)

a Constant variance model selected (p = 0.5593)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.2.4.2. Output for Selected Model: Linear

Amin et al., 2000: 0.50% Saccharin Preference Ratio, Female

Polynomial Model. (Version: 2.13; Date: 04/08/2008)

Input Data File: C:\l\Blood\4_Amin_2000_50_SP_LinearCV_l.(d)

Gnuplot Plotting File: C:\l\Blood\4_Amin_2 000_50_SP_LinearCV_l.plt

Mon Feb 08 10:45:50 2010

The form of the response function is:

Y[dose] = beta_0 + beta_l*dose + beta_2*dose/N2 + ...

Dependent variable = Mean
Independent variable = Dose
rho is set to 0

Signs of the polynomial coefficients are not restricted
A constant variance model is fit

Total number of dose groups = 3

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial P.

alpha =
rho =
beta_0 =
beta 1 =

rameter Values
764.602

0 Specified
65.8627
-3.34297

This document is a draft for review purposes only and does not constitute Agency policy.

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Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -rho

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha	beta 0	beta 1

alpha 1	2.6e-008	2.1e-009

beta_0 2.6e-008	1	-0.73

beta 1 2. le-009	-0.73	1

Parameter Estimates

Variable
alpha
beta_0
beta 1

Estimate

741.255
65.8627
-3.34297

95.0% Wald Confidence Interval
Std. Err.	Lower Conf. Limit Upper Conf. Limit

191.391	366.135	1116.38

7.22524	51.7015	80.0239

1.12815	-5.55412	-1.13183

Table of Data and Estimated Values of Interest

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0 10
3.378 10
10.57 10

12. 7
44.5
33. 8

65. 9

54 . 6
30.5

24 . 6
32 . 9
24 . 6

27 . 2
27 . 2
27 . 2

0.191
-1 . 17
0.375

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi

Var{e(i)}

Mu + e(i)
Sigma/N2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1	-113.009921	4	234.019841

A2	-112.428886	6	236.857773

A3	-113.009921	4	234.019841

fitted	-114.125184	3	234.250368

R	-117.976057	2	239.952114

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

This document is a draft for review purposes only and does not constitute Agency policy.

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Test 3: Are variances adequately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.)

Tests of Interest

Test -2*log(Likelihood Ratio) Test df

p-value

Test 1

Test 2
Test 3
Test 4

11.0943
1.16207
1.16207
2.23053

4
2
2
1

0.02552
0.5593
0.5593
0.1353

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than .1. A homogeneous variance
model appears to be appropriate here

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adequately describe the data

Benchmark Dose Computation

Specified effect

1

Risk Type

Estimated standard deviations from the control mean

Confidence level

0. 95

BMD

8 .14425

BMDL

5.10523

This document is a draft for review purposes only and does not constitute Agency policy.

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E.2.4.3. Figure for Selected Model: Linear

Linear Model with 0.95 Confidence Level

dose

10:45 02/08 2010

E.2.4.4. Output for Additional Model Presented: Power, Unrestricted
Amin et al., 2000: 0.50% Saccharin Preference Ratio, Female

Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\l\Blood\4_Amin_2000_50_SP_PwrCV_U_l.(d)

Gnuplot Plotting File: C:\l\Blood\4_Amin_2 000_50_SP_PwrCV_U_l.plt

Mon Feb 08 10:45:50 2010

The form of the response function is:
Y[dose] = control + slope * doseApower

Dependent variable = Mean
Independent variable = Dose
rho is set to 0
The power is not restricted
A constant variance model is fit

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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Total number of dose groups = 3

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

alpha
rho
control
slope
power

764.602

0

72.7273
-20.0402
0.281985

Specified

Asymptotic Correlation Matrix of Parameter Estimates

alpha
control

The model parameter(s) -rho

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha
1

-1. 2e-009

control
-1. 2e-009
1

slope
-1.2e-009
-0.51

power
-2 . 2e-010
-0.22

slope -1.2e-009	-0.51	1	0.92

power -2.2e-010	-0.22	0.92	1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
alpha
control
slope
power

Estimate
688.142
72.7273
-20.0402
0.281985

Std. Err.

177.677
8.29543
15.0576
0.325861

Lower Conf. Limit

339. 9
56.4686
-49.5526
-0.35669

Upper Conf. Limit
1036.38
88 . 986
9. 47219
0. 920661

Table of Data and Estimated Values of Interest
Dose	N Obs Mean	Est Mean Obs Std Dev Est Std Dev Scaled Res.

0 10 72.7	72.7	24.6	26.2	4.67e-009

3.378 10 44.5	44.5	32.9	26.2	1.52e-008

10.57 10 33.8	33.8	24.6	26.2	1.77e-008

Warning: Likelihood for	fitted model	larger than	the Likelihood	for model A3.

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

This document is a draft for review purposes only and does not constitute Agency policy.

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Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1	-113.009921	4	234.019841

A2	-112.428886	6	236.857773

A3	-113.009921	4	234.019841

fitted	-113.009921	4	234.019841

R	-117.976057	2	239.952114

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Test

2

Test

3

Test

4

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	11.0943	4	0.02552

Test 2	1.16207	2	0.5593

Test 3	1.16207	2	0.5593

Test 4	-2.84217e-014	0	NA

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than .1. A homogeneous variance
model appears to be appropriate here

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

NA - Degrees of freedom for Test 4 are less than or egual to 0. The Chi-Sguare
test for fit is not valid

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD = 2.59831

BMDL = 1.05661e-014

This document is a draft for review purposes only and does not constitute Agency policy.

E-36	DRAFT—DO NOT CITE OR QUOTE


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E.2.4.5. Figure for Additional Model Presented: Power, Unrestricted

Power Model with 0.95 Confidence Level

dose

10:45 02/08 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-3 7	DRAFT—DO NOT CITE OR QUOTE


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E.2.5. Bell et al., 2007a: Balano-Preputial Separation, Postnatal Day 49
E.2.5.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

gamma

2

0.684

112.136

2.867E+00

1.943E+00

power bound hit (power = 1)

logistic

2

0.342

113.915

6.159E+00

4.746E+00

negative intercept (intercept =
-2.246)

log-logistica

2

0.777

111.908

2.246E+00

1.394E+00

slope bound hit (slope = 1)

log-probit

2

0.269

114.254

5.322E+00

3.512E+00

slope bound hit (slope =1)

multistage, 3-
degree

2

0.684

112.136

2.867E+00

1.943E+00

final B = 0

probit

2

0.367

113.713

5.715E+00

4.422E+00



Weibull

2

0.684

112.136

2.867E+00

1.943E+00

power bound hit (power = 1)

gamma,
unrestricted

1

0.566

113.746

1.862E+00

1.829E-01

unrestricted (power = 0.741)

log-logistic,
unrestricted b

1

0.501

113.871

1.998E+00

2.795E-01

unrestricted (slope = 0.93)

log-probit,
unrestricted

1

0.456

113.977

2.038E+00

3.250E-01

unrestricted (slope = 0.54)

Weibull,
unrestricted

1

0.551

113.771

1.914E+00

2.346E-01

unrestricted (power = 0.795)

a Best-fitting model, BMDS output presented in this appendix
b Alternate model, BMDS output also presented in this appendix

E.2.5.2. Output for Selected Model: Log-Logistic

Bell et al., 2007a: Balano-Preputial Separation, Postnatal Day 49

Logistic Model. (Version: 2.12; Date: 05/16/2008)

Input Data File: C:\l\Blood\5_Bell_2007_BPS_LogLogistic_l.(d)

Gnuplot Plotting File: C:\l\Blood\5_Bell_2007_BPS_LogLogistic_l.plt

Mon Feb 08 10:46:18 2010

0

The form of the probability function is:

P[response] = background+(1-background)/[1+EXP(-intercept-slope*Log(dose))]

Dependent variable = DichEff
Independent variable = Dose

This document is a draft for review purposes only and does not constitute Agency policy.

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Slope parameter is restricted as slope >= 1

Total number of observations = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

User has chosen the log transformed model

Default Initial Parameter Values

background = 0.0333333
intercept =	-2.99896

slope =	1

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -slope

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

background intercept

background	1	-0.49

intercept	-0.49	1

Parameter Estimates

95.0% Wald Confidence Interval

Variable Estimate Std. Err.	Lower Conf.	Limit Upper Conf. Limit

background 0.038005 *	*	*

intercept -3.00658 *	*	*

slope 1 *	*	*

Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-53.7077	4

Fitted model -53.954 2	0.492596 2	0.7817

Reduced model -63.9797 1	20.544 3	0.0001309

AIC:	111.908

Goodness of Fit

Scaled

Dose Est. Prob. Expected Observed	Size	Residual

0.0000 0.0380 1.140 1.000	30	-0.134

2.2040 0.1326 3.977 5.000	30	0.551

5.1378 0.2329 6.988 6.000	30	-0.427

18.4110 0.4965 14.895 15.000	30	0.038

Chi/N2 = 0.50	d.f. = 2	P-value = 0.7769

Benchmark Dose Computation
Specified effect =	0.1

This document is a draft for review purposes only and does not constitute Agency policy.

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Risk Type	=

Confidence level =
BMD =

Extra risk
0. 95
2 .24647

BMDL =	1.39385

E.2.5.3. Figure for Selected Model: Log-Logistic

Log-Logistic Model with 0.95 Confidence Level

dose

10:46 02/08 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-40	DRAFT—DO NOT CITE OR QUOTE


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E.2.5.4. Output for Additional Model Presented: Log-Logistic, Unrestricted
Bell et al., 2007a: Balano-Preputial Separation, Postnatal Day 49

Logistic Model. (Version: 2.12; Date: 05/16/2008)

Input Data File: C:\l\Blood\5_Bell_2007_BPS_LogLogistic_U_l.(d)

Gnuplot Plotting File: C:\l\Blood\5_Bell_2007_BPS_LogLogistic_U_l.plt

Mon Feb 08 10:46:18 2010

The form of the probability function is:

P[response] = background+(1-background)/[1+EXP(-intercept-slope*Log(dose)

Dependent variable = DichEff
Independent variable = Dose
Slope parameter is not restricted

Total number of observations = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

User has chosen the log transformed model

Default Initial Parameter Values

background = 0.0333333
intercept =	-2.68464

slope =	0.858398

Asymptotic Correlation Matrix of Parameter Estimates
background intercept	slope

background	1	-0.48	0.35

intercept	-0.48	1	-0.94

slope	0.35	-0.94	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

background	0.0353402	*	*	*

intercept	-2.84051	*	*	*

slope	0.929645	*	*	*

* - Indicates that this value is not calculated.

Analysis of Deviance Table

Model	Log(likelihood) # Param's Deviance Test d.f. P-value

Full model	-53.7077	4

This document is a draft for review purposes only and does not constitute Agency policy.

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Fitted model	-53.9354	3	0.455534	1	0.4997

Reduced model	-63.9797	1	20.544	3	0.0001309

AIC:	113.871

Goodness of Fit

Scaled

Dose	Est. Prob. Expected Observed	Size	Residual

0.0000

0.0353

1. 060

1. 000

30

-0.060

2.2040

0.1400

4 .201

5. 000

30

0.420

5.1378

0.2389

7 .166

6. 000

30

-0.499

18.4110

0.4858

14.573

15.000

30

0.156

Chi^2 = 0.45	d.f. = 1	P-value = 0.5005

Benchmark Dose Computation
Specified effect =	0.1

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	1.99765

BMDL =	0.27 9534

This document is a draft for review purposes only and does not constitute Agency policy.

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E.2.5.5. Figure for Additional Model Presented: Log-Logistic, Unrestricted

Log-Logistic Model with 0.95 Confidence Level

dose

10:46 02/08 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.2.6. Cantoni et al., 1981: Urinary Coproporhyrins, 3 Months
E.2.6.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

X2 P-
Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential (M2)

2

0.003

32.882

3.209E+01

1.567E+01



exponential (M3)

2

0.003

32.882

3.209E+01

1.567E+01

power hit bound (d = 1)

exponential
(M4)b

1

0.486

23.459

5.339E-01

1.803E-01



exponential (M5)

1

0.486

23.459

5.339E-01

1.803E-01

power hit bound (d = 1)

Hill

1

0.788

23.047

4.333E-01

error

n lower bound hit (n = 1)

linear

2

0.005

31.595

1.464E+01

2.753E+00



polynomial, 3-
degree

2

0.005

31.595

1.464E+01

2.753E+00



power

2

0.005

31.595

1.464E+01

2.753E+00

power bound hit (power =1)

power,
unrestricted0

1

0.610

23.235

2.766E-02

2.031E-05

unrestricted (power = 0.304)

Hill, unrestricted

0

N/A

24.974

2.602E-01

error

unrestricted (n = 0.739)

a Non-constant variance model selected (p = 0.0039)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.2.6.2. Output for Selected Model: Exponential (M4)

Cantoni et al., 1981: Urinary Coproporhyrins, 3 Months

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\l\Blood\6_Cantoni_l981_UriCopro_Exp_l.(d)

Gnuplot Plotting File:

Mon Feb 08 10:46:46 2010

Figurel-UrinaryCoproporphyrin 3months

The form of the response function by Model:

Model 2
Model 3
Model 4
Model 5

Y[dose]
Y[dose]
Y[dose]
Y[dose]

exp{sign *	b * dose}

exp{sign *	(b * dosej^d}

[c-(c-l) *	exp{-b * dose}]

[c-(c-l) *	exp{-(b * dosej^d}

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;

This document is a draft for review purposes only and does not constitute Agency policy.

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sign = -1 for decreasing trend.

Model 2 is nested within Models 3 and 4.
Model 3 is nested within Model 5.

Model 4 is nested within Model 5.

Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)
Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values
Variable	Model 4

lnalpha	-1.50063

rho	2.6097 9

a	0.704303

b	0.0604961

c	4.47268

d	1

Parameter Estimates
Variable	Model 4

lnalpha	-1.75302

rho	2.6322

a	0.761218

b	0.241561

c	4.15597

d	1

Table of Stats From Input Data
Dose	N	Obs Mean	Obs Std Dev

0	4	0.7414	0.3475

1.847	4	1.807	0.8341

8.839	4	2.734	1.506

50.05	4	3	2.6

Estimated Values of Interest
Dose	Est Mean	Est Std	Scaled Residual

0	0.7612	0.2907	-0.1366

1.847	1.626	0.7892	0.4588

8.839	2.88	1.674	-0.1743

50.05	3.164	1.895	-0.1725

Other models for which likelihoods are calculated:

This document is a draft for review purposes only and does not constitute Agency policy.

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Model A1:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma^2

Model A2 :	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma(i)^2

Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= exp(lalpha + log(mean(i) ) 'k rho)

Model R:	Yij	= Mu + e(i)

Var{e(ij)}	= Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	DF	AIC

A1	-12.90166	5	35.80333

A2	-6.203643	8	28.40729

A3	-6.487204	6	24.97441

R	-15.73713	2	35.47427

4	-6.729737	5	23.45947

Additive constant for all log-likelihoods =	-14.7. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Test

1:

Does response

and/or variances differ among Dose levels? (A2 vs. R)

Test

2 :

Are Variances

Homogeneous? (A2 vs. A1)

Test

3:

Are variances

adequately modeled? (A2 vs. A3)

Test 6a: Does Model 4 fit the data? (A3 vs 4)

Test

Test 1
Test 2
Test 3
Test 6a

Tests of Interest

-2*log(Likelihood Ratio)

19. 07
13. 4
0.5671
0.4851

D. F.

p-value

0.004052
0.003854
0.7531
0.4861

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose
levels, it seems appropriate to model the data.

The p-value for Test 2 is less than .1. A non-homogeneous
variance model appears to be appropriate.

The p-value for Test 3 is greater than .1. The modeled
variance appears to be appropriate here.

The p-value for Test 6a is greater than .1. Model 4 seems
to adeguately describe the data.

Benchmark Dose Computations:

Specified Effect = 1.000000

Risk Type = Estimated standard deviations from control
Confidence Level = 0.950000

This document is a draft for review purposes only and does not constitute Agency policy.

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EMD =

0.533855

E'.MDL =	0.18 02 93

E.2.6.3. Figure for Selected Model: Exponential (M4)

Exponential Model 4 with 0.95 Confidence Level

dose

10:46 02/08 2010

E.2.6.4. Output for Additional Model Presented: Power, Unrestricted
Cantoni et al., 1981: Urinary Coproporhyrins, 3 Months

Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\l\Blood\6_Cantoni_l981_UriCopro_Pwr_U_l.(d)

Gnuplot Plotting File: C:\l\Blood\6_Cantoni_1981_UriCopro_Pwr_U_l.plt

Mon Feb 08 10:46:47 2010

Figurel-UrinaryCoproporphyrin_3months

The form of the response function is:
Y[dose] = control + slope * doseApower

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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Dependent variable = Mean

Independent variable = Dose

The power is not restricted

The variance is to be modeled as Var(i)

exp(lalpha + log(mean(i))

rho)

Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

lalpha =	0.90039

rho =	0

control =	0.741372

slope =	0.93685

power =	0.224 904

Asymptotic Correlation Matrix of Parameter Estimates

lalpha
rho
control
slope
power

lalpha
1

-0. 62
-0.53
-0.036
0. 024

rho

-0. 62
1

0.43
-0.2
-0.16

control

-0.53
0.43
1

-0.28
0. 086

slope
-0.036
-0.2

-0.28
1

-0.77

power

0. 024
-0.16
0. 086
-0.77
1

Parameter Estimates

Variable
lalpha
rho
control
slope
power

Estimate
-1.78125
2.64332
0.75678
0. 845767
0.304211

Std. Err.

0. 617807
0.744946
0.139979
0.324854
0.135053

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

-2.99213
1.18325
0. 482426
0.209065
0. 0395119

-0.570373
4 .10338
1. 03113
1.48247
0.568909

Table of Data and Estimated Values of Interest

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0	4	0.741	0.757	0.348	0.284	-0.109

1.847	4	1.81	1.78	0.834	0.877	0.0705

8.839	4	2.73	2.4	1.51	1.3	0.515

50.05	4	3	3.54	2.6	2.18	-0.493

Model Descriptions for likelihoods calculated

Model A1:	Yij	= Mu(i) + e(iji

Var{e(ij)} = Sigma/'2

Model A2:	Yij	= Mu(i) + e(ij|

Var{e(ij)} = Sigma(i)^2

This document is a draft for review purposes only and does not constitute Agency policy.

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Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1	-12.901663	5	35.803325

A2	-6.203643	8	28.407287

A3	-6.487204	6	24.974409

fitted	-6.617347	5	23.234694

R	-15.737135	2	35.474269

Explanation of Tests

Test 1:

Test

2

Test

3

Test

4

Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	19.067	6	0.004052

Test 2	13.396	3	0.003854

Test 3	0.567122	2	0.7531

Test 4	0.260285	1	0.6099

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adeguately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD = 0.0276599

BMDL = 2.03143e-005

This document is a draft for review purposes only and does not constitute Agency policy.

E-49	DRAFT—DO NOT CITE OR QUOTE


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E.2.6.5. Figure for Additional Model Presented: Power, Unrestricted

Power Model with 0.95 Confidence Level

dose

10:46 02/08 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-50	DRAFT—DO NOT CITE OR QUOTE


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E.2.7. Cantoni et al., 1981: Urinary Porphyrins
E.2.7.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential (M2)b

2

<0.001

55.465

3.760E+00

2.762E+00



exponential (M3)

2

<0.001

55.465

3.760E+00

2.762E+00

power hit bound (d = 1)

exponential (M4)

1

<0.0001

59.187

2.484E-01

1.448E-01



exponential (M5)

0

N/A

61.084

2.878E-01

1.461E-01



Hill

0

N/A

62.199

6.233E+00

3.341E+00



linear

2

<0.001

57.187

2.484E-01

1.448E-01



polynomial, 3-
degree

1

<0.0001

10.000

error

error



power

1

<0.0001

59.084

2.878E-01

1.461E-01



a Non-constant variance model selected (p = <0.0001)
b Best-fitting model, BMDS output presented in this appendix

E.2.7.2. Output for Selected Model: Exponential (M2)

Cantoni et al., 1981: Urinary Porphyrins

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\l\Blood\7_Cantoni_l981_UriPor_Exp_l.(d)

Gnuplot Plotting File:

Mon Feb 08 10:47:24 2010

Table 1, dose converted to ng per kg per day

The form of the response function by Model:

Model 2
Model 3
Model 4
Model 5

Y[dose]
Y[dose]
Y[dose]
Y[dose]

exp{sign *	b * dose}

exp{sign *	(b * dosej^d}

[c-(c-l) *	exp{-b * dose}]

[c-(c-l) *	exp{-(b * dosej^d}

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;
sign = -1 for decreasing trend.

Model 2 is nested within Models 3 and 4.
Model 3 is nested within Model 5.

Model 4 is nested within Model 5.

Dependent variable = Mean

This document is a draft for review purposes only and does not constitute Agency policy.

E-51	DRAFT—DO NOT CITE OR QUOTE


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Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)
Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values
Variable	Model 2

lnalpha	-3.57509

rho	2.23456

a	3.36453

b	0.0819801

c	0

d	1

Parameter Estimates
Variable	Model 2

lnalpha	-1.85879

rho	1.82273

a	3.57896

b	0.0803347

c	0

d	1



Table of

Stats From Input

Data

Dose

N

Obs Mean

Obs Std

0

4

2 . 27

0.49

1.847

4

5.55

o

CO
CJ1

8 . 839

3

7 . 62

1.79

en
o

o
CJ1

3

196. 9

63.14

Estimated Values of Interest
Dose	Est Mean	Est Std	Scaled Residual

0	3.579	1.262	-2.074

1.847	4.152	1.445	1.936

8.839	7.28	2.41	0.2441

50.05	199.5	49.25	-0.09069

Other models for which likelihoods are calculated:

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + log(mean(i)) * rho)

This document is a draft for review purposes only and does not constitute Agency policy.

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Model R:	Yij = Mu + e(i

Var{e(ij)} = Sigma^2

Likelihoods of Interest
Model	Log(likelihood)	DF	AIC

A1	-51.42175	5	112.8435

A2	-15.31211	8	46.62422

A3	-15.66963	6	43.33925

R	-68.75058	2	141.5012

2	-23.73254	4	55.46509

Additive constant for all log-likelihoods =	-12.87. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Does response and/or variances differ among Dose levels? (A2

Are Variances Homogeneous? (A2 vs. A1)

Are variances adeguately modeled? (A2 vs. A3)

Does Model 2 fit the data? (A3 vs. 2)

Tests of Interest
Test	-2*log(Likelihood Ratio)	D. F.	p-value

Test 1	106.9	6	< 0.0001

Test 2	72.22	3	< 0.0001

Test 3	0.715	2	0.6994

Test 4	16.13	2	0.000315

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose
levels, it seems appropriate to model the data.

The p-value for Test 2 is less than .1. A non-homogeneous
variance model appears to be appropriate.

The p-value for Test 3 is greater than .1. The modeled
variance appears to be appropriate here.

The p-value for Test 4 is less than .1. Model 2 may not adeguately
describe the data; you may want to consider another model.

Benchmark Dose Computations:

Specified Effect = 1.000000

Risk Type = Estimated standard deviations from control
Confidence Level = 0.950000

BMD =	3.75968

BMDL =	2.76247

This document is a draft for review purposes only and does not constitute Agency policy.

E-53	DRAFT—DO NOT CITE OR QUOTE


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l E.2.7.3. Figure for Selected Model: Exponential (M2)

Exponential Model 2 with 0.95 Confidence Level

dose

2	10:47 02/08 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.2.8. Crofton et al., 2005: Serum, T4

E.2.8.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

r p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential (M2)

8

<0.0001

516.356

1.144E+02

6.239E+01



exponential (M3)

8

<0.0001

516.356

1.144E+02

6.239E+01

power hit bound (d = 1)

exponential
(M4)b

7

0.942

476.449

5.190E+00

3.029E+00



exponential (M5)

6

0.912

478.234

5.757E+00

3.094E+00



Hill

6

0.972

477.450

5.724E+00

3.024E+00



linear

8

<0.0001

522.460

2.406E+02

1.761E+02



polynomial, 8-
degree

8

<0.0001

522.460

2.406E+02

1.761E+02



power

8

<0.0001

522.460

2.406E+02

1.761E+02

power bound hit (power =1)

power,
unrestricted

7

0.018

491.101

2.449E+00

3.307E-01

unrestricted (power = 0.243)

a Constant variance model selected (p = 0.7647)
b Best-fitting model, BMDS output presented in this appendix

E.2.8.2. Output for Selected Model: Exponential (M4)

Crofton et al., 2005: Serum, T4

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\l\Blood\8_Crofton_2005_T4_ExpCV_l.(d)

Gnuplot Plotting File:

Mon Feb 08 10:48:04 2010

0

The form of the response function by Model:

Model 2
Model 3
Model 4
Model 5

Y[dose]
Y[dose]
Y[dose]
Y[dose]

exp{sign *	b * dose}

exp{sign *	(b * dosej^d}

[c-(c-l) *	exp{-b * dose}]

[c-(c-l) *	exp{-(b * dosej^d}

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;
sign = -1 for decreasing trend.

Model 2 is nested within Models 3 and 4.
Model 3 is nested within Model 5.

Model 4 is nested within Model 5.

This document is a draft for review purposes only and does not constitute Agency policy.

E-55	DRAFT—DO NOT CITE OR QUOTE


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Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))
rho is set to 0.

A constant variance model is fit.

Total number of dose groups = 10

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values

Variable

Model 4

lnalpha

rho(S)

5.47437

0

104.999
0.00641895
0.445764

1

(S)

Specified

Parameter Estimates

Variable

lnalpha
rho

Model 4

5.50623

0

100.332
0. 076678
0.523626

1

Table of Stats From Input Data

Dose

0

0.0202

0.4882

1.	384
3. 455
9.257
23. 07
65. 65
180. 9
583.5

N
14

6
12

Obs Mean

100
96.27
98 . 57
99.76
93.32
70. 94
62 . 52
52 . 68
54 . 66
49.15

Obs Std Dev

15. 44
14 . 98
18 .11
19. 04
12 .11

12.74

14.75
22 .73
19.71
11.15

Estimated Values of Interest

Dose

0

0.0202
0.4882
1. 384
3. 455

Est Mean

100.3
100.3
98 . 58
95.52
89.21

Est Std

15. 69
15. 69
15. 69
15. 69
15. 69

Scaled Residual

-0.07952
-0.6231
-0.000744
0.6614
0.6422

This document is a draft for review purposes only and does not constitute Agency policy.

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9.257	76.04	15.69	-0.7962

23.07	60.69	15.69	0.2854

65.65	52.85	15.69	-0.02621

180.9	52.54	15.69	0.3319

583.5	52.54	15.69	-0.4323

Other models for which	likelihoods are calculated:

Model A1:	Yij	=	Mu(i) + e(1j)

Var{e(ij)}	=	Sigma^2

Model A2:	Yij	=	Mu(i) + e(1j)

Var{e(ij)}	=	Sigma(i)^2

Model A3:	Yij	=	Mu(i) + e(1j)

Var{e(ij)}	=	exp(lalpha + log(mean(i) ) 'k rho)

Model R:	Yij	=	Mu + e(1)

Var{e(ij)}	=	Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	DF	AIC

A1	-233.0774	11	488.1549

A2	-230.2028	20	500.4056

A3	-233.0774	11	488.1549

R	-268.4038	2	540.8076

4	-234.2243	4	476.4486

Additive constant for all log-likelihoods =	-66.16. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Test 1: Does response and/or variances differ among Dose levels? (A2 vs. R)

Test 2: Are Variances Homogeneous? (A2 vs. A1)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 6a: Does Model 4 fit the data? (A3 vs 4)

Test

Test 1
Test 2
Test 3
Test 6a

Tests of Interest

-2*log(Likelihood Ratio)

76.4
5.749
5.749
2.294

D. F.

18
9
9
7

p-value

< 0.0001
0.7647
0.7647
0.9418

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose
levels, it seems appropriate to model the data.

The p-value for Test 2 is greater than .1. A homogeneous
variance model appears to be appropriate here.

The p-value for Test 3 is greater than .1. The modeled
variance appears to be appropriate here.

The p-value for Test 6a is greater than .1. Model 4 seems
to adeguately describe the data.

This document is a draft for review purposes only and does not constitute Agency policy.

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Benchmark Dose Computations:

Specified Effect = 1.000000

Risk Type = Estimated standard deviations from control
Confidence Level = 0.950000

BMD =	5.18983

BMDL =	3.02894

E.2.8.3. Figure for Selected Model: Exponential (M4)

Exponential Model 4 with 0.95 Confidence Level

dose

10:48 02/08 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.2.9. Franc et al., 2001: S-D Rats, Relative Liver Weight
E.2.9.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

z2 p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential (M2)

2

0.968

234.369

7.800E+00

6.040E+00



exponential (M3)

1

0.880

236.327

9.201E+00

6.051E+00



exponential (M4)

1

0.580

236.610

6.365E+00

4.512E+00



exponential (M5)

0

N/A

238.346

9.474E+00

4.425E+00



Hill

0

N/A

238.346

9.479E+00

3.004E+00



linear

2

0.858

234.610

6.365E+00

4.512E+00



polynomial, 3-
degree

1

0.935

236.311

8.946E+00

4.598E+00



power b

1

0.839

236.346

9.474E+00

4.587E+00



a Constant variance model selected (p = 0.107)
b Best-fitting model, BMDS output presented in this appendix

E.2.9.2. Output for Selected Model: Power
Franc et al., 2001: S-D Rats, Relative Liver Weight

Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\l\Blood\88_Franc_2001_SD_RelLivWt_PowerCV_l.(d)

Gnuplot Plotting File: C:\l\Blood\88_Franc_2001_SD_RelLivWt_PowerCV_l.plt

Thu Apr 15 11:46:32 2010

Figure 5, SD rats, relative liver weight

The form of the response function is:

Y[dose] = control + slope * doseApower

Dependent variable = Mean
Independent variable = Dose
rho is set to 0

The power is restricted to be greater than or egual to 1
A constant variance model is fit

Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

This document is a draft for review purposes only and does not constitute Agency policy.

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Default Initial Parameter Values

alpha
rho
control
slope
power

527 .447

0

100
0.947018
1.13144

Specified

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -rho

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha	control	slope	power

alpha	1 -6.3e-009	5.4e-009 -4.7e-009

control -6.3e-009	1	-0.74	0.71

slope	5.4e-009	-0.74	1	-1

power -4.7e-009	0.71	-1	1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
alpha
control
slope
power

Estimate

462.113
100.494
0.593276
1. 25841

Std. Err.
115.528
7.31114
1.31535
0.597816

Lower Conf. Limit

235.682
86.1645
-1. 98476
0.086712

Upper Conf. Limit

688.544
114 . 824
3.17131
2.43011

Table of Data and Estimated Values of Interest

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0	8	100	100	14	21.5	-0.065

6.587	8	108	107	16.9	21.5	0.158

14.48	8	117	118	25.9	21.5	-0.109

36.43	8	155	155	30.9	21.5	0.0157

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

This document is a draft for review purposes only and does not constitute Agency policy.

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Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1	-114.152281	5	238.304562

A2	-111.103649	8	238.207299

A3	-114.152281	5	238.304562

fitted	-114.172940	4	236.345880

R	-125.052064	2	254.104127

Test

1

Test

2

Test

3

Test

4

(Note:

Explanation of Tests

Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adequately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1

Test 2
Test 3
Test 4

27 .8968
6. 09726
6.09726
0. 0413179

<.0001
0.107
0.107
0. 8389

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than .1. A homogeneous variance
model appears to be appropriate here

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adequately describe the data

Benchmark Dose Computation
Specified effect =	0.1

Risk Type	=	Relative risk

Confidence level =	0.95

BMD = 9.47 4 08

BMDL = 4.587 3

This document is a draft for review purposes only and does not constitute Agency policy.

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l E.2.9.3. Figure for Selected Model: Power

Power Model with 0.95 Confidence Level

dose

2	11:46 04/15 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.2.10. Franc et al., 2001: L-E Rats, Relative Liver Weight
E.2.10.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

z2 p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential (M2)

2

0.441

208.974

1.708E+01

1.098E+01



exponential (M3)

2

0.441

208.974

1.708E+01

1.098E+01

power hit bound (d = 1)

exponential (M4)

1

0.785

209.408

7.997E+00

2.601E+00



exponential (M5)

1

0.785

209.408

7.997E+00

2.601E+00

power hit bound (d = 1)

Hill b

1

0.829

209.381

7.725E+00

1.225E+00

n lower bound hit (n = 1)

linear

2

0.499

208.725

1.570E+01

9.619E+00



polynomial, 3-
degree

1

<0.0001

10.000

8.604E+00

error



power

2

0.499

208.725

1.570E+01

9.619E+00

power bound hit (power =1)

Hill, unrestricted

C

0

N/A

211.337

7.217E+00

1.147E+00

unrestricted (n = 0.545)

power,
unrestricted

1

0.965

209.336

7.193E+00

error

unrestricted (power = 0.524)

a Non-constant variance model selected (p = 0.0632)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.2.10.2. Output for Selected Model: Hill

Franc et al., 2001: L-E Rats, Relative Liver Weight

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\l\Blood\89_Franc_2001_LE_RelLivWt_Hill_l.(d)

Gnuplot Plotting File: C:\l\Blood\8 9_Franc_2001_LE_RelLivWt_Hill_l.plt

Thu Apr 15 11:48:14 2010

Figure 5, L-E rats, relative liver weight

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = Mean
Independent variable = Dose

Power parameter restricted to be greater than 1

This document is a draft for review purposes only and does not constitute Agency policy.

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The variance is to be modeled as Var(i) = exp(lalpha + rho * ln(mean(i)))
Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

lalpha
rho

intercept

5. 41581

0

100
22 . 225
0. 443155
18.746

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -n

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

lalpha
rho

intercept

lalpha
1
-1

-0.21
0.33
0.18

rho
-1

1

0.21
-0.33
-0.18

intercept

-0.21
0.21
1

0. 028
0.35

v

0.33
-0.33
0. 028
1

0. 91

k

0.18
-0.18
0.35
0. 91
1

Parameter Estimates

Variable
lalpha
rho

intercept

k

Estimate

-17.2754
4 .77884
99.5348
36.3963
1

20.5223

Std. Err.

17 . 3066
3. 67625
3.61286
24 .1862
NA

28 . 2566

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

-51.1957
-2 .42648
92.4538
-11.0079

-34.8596

16.6449

11.9842
106.616
83.8004

75.9042

NA - Indicates that this parameter has hit a bound
implied by some ineguality constraint and thus
has no standard error.

Table of Data and Estimated Values of Interest

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0	8	100	99.5	10	10.5	0.125

6.584	8	106	108	17.9	12.9	-0.455

14.47	8	117	115	8.97	14.8	0.426

36.41	8	122	123	19.9	17.4	-0.0954

Model Descriptions for likelihoods calculated

This document is a draft for review purposes only and does not constitute Agency policy.

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Model A1:	Yij	= Mu(i) + e(ij

Var{e(ij)}	= Sigma^2

Model A2 :	Yij	= Mu(i) + e(ij

Var{e(ij)}	= Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model
A1
A2
A3

fitted
R

Log(likelihood)
-100.516456
-96.870820
-99.666984
-99.690373
-105.717087

Param1s
5

AIC
211.032912
209.741641
211.333969
209.380746
215.434174

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.)

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1
Test 2
Test 3
Test 4

17.6925
7.29127
5.59233
0.0467774

0.007048
0.06317
0.06104
0.8288

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is less than .1. You may want to consider a
different variance model

The p-value for Test 4 is greater than .1. The model chosen seems
to adeguately describe the data

Benchmark Dose Computation
Specified effect =	0.1

Risk Type	=	Relative risk

Confidence level =	0.95

BMD =	7.724 92

BMDL =	1.22451

This document is a draft for review purposes only and does not constitute Agency policy.

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E.2.10.3. Figure for Selected Model: Hill

Hill Model with 0.95 Confidence Level

a>

CO
c
o

Q.

CO
CD

a:

c
m

CD

140

130

120

110

100

90

Hill



BMDL

BMD

10

15

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25

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35

dose

11:48 04/15 2010

E.2.10.4. Output for Additional Model Presented: Hill, Unrestricted
Franc et al., 2001: L-E Rats, Relative Liver Weight

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\l\Blood\89_Franc_2001_LE_RelLivWt_Hill_U_l.(d)

Gnuplot Plotting File: C:\l\Blood\8 9_Franc_2001_LE_RelLivWt_Hill_U_l.plt

Thu Apr 15 11:48:50 2010

Figure 5, L-E rats, relative liver weight

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = Mean
Independent variable = Dose
Power parameter is not restricted
The variance is to be modeled as Var(i)

Total number of dose groups = 4

exp(lalpha + rho

In(mean(i)

This document is a draft for review purposes only and does not constitute Agency policy.

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Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

lalpha =	5.41581

rho =	0

intercept =	100

v =	22.225

n =	0.443155

k =	18.746

Asymptotic Correlation Matrix of Parameter Estimates

lalpha rho	intercept v n k

lalpha 1 -1	-0.22 -0.14 0.24 -0.15

rho -1 1	0.22 0.14 -0.24 0.15

intercept -0.22 0.22	1 0.022 0.11 0.013

v -0.14 0.14	0.022 1 -0.9 1

n 0.24 -0.24	0.11 -0.9 1 -0.92

k -0.15 0.15	0.013 1 -0.92 1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
lalpha
rho

intercept

Estimate
-19.2405
5.19575
99.5348
440.285
0.544741
7266.27

Std. Err.

18 . 21
3. 86861
3.51796
13708.5
0.730981
485402

Lower Conf. Limit

-54.9315
-2 . 38657
92 . 6398
-26427.9
-0.887956
-944104

Upper Conf. Limit

16.4505
12 .7781
106.43
27308.5
1.97744
958637

Table of Data and Estimated Values

Dose	N Obs Mean	Est Mean

0	8	100	99.5

6.584	8	106	109

14.47	8	117	114

36.41	8	122	123

of Interest

Scaled Res.

0.128

-0.589
0.558
-0.0957

Obs Std Dev Est Std Dev

10

17 . 9
8 . 97
19. 9

10.3
13
14 . 6
17 . 8

Degrees of freedom for Test A3 vs fitted <= 0

Model Descriptions for likelihoods calculated

Model A1:	Yij	= Mu(i) + e(iji

Var{e(ij)} = Sigma/'2

Model A2:	Yij	= Mu(i) + e(ij|

Var{e(ij)} = Sigma(i)^2

This document is a draft for review purposes only and does not constitute Agency policy.

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Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1	-100.516456	5	211.032912

A2 -96.870820	8	209.741641

A3 -99.666984	6	211.333969

fitted -99.668321	6	211.336641

R	-105.717087	2	215.434174

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1
Test 2
Test 3
Test 4

17.6925
7.29127
5.59233
0.00267242

0.007048
0.06317
0.06104
NA

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is less than .1. You may want to consider a
different variance model

NA - Degrees of freedom for Test 4 are less than or egual to 0. The Chi-Sguare
test for fit is not valid

Benchmark Dose Computation
Specified effect =	0.1

Risk Type	=	Relative risk

Confidence level =	0.95

BMD =	7.21718

BMDL =	1.147 42

This document is a draft for review purposes only and does not constitute Agency policy.

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E.2.10.5. Figure for Additional Model Presented: Hill, Unrestricted

Hill Model with 0.95 Confidence Level

dose

11:48 04/15 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.2.11. Franc et al., 2001: S-D Rats, Relative Thymus Weight
E.2.11.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

z2 p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential (M2)

2

0.814

285.107

2.478E+00

1.535E+00



exponential (M3)

1

0.016

292.452

3.173E+01

1.007E+00



exponential
(M4)b

1

0.720

286.825

1.878E+00

9.221E-01



exponential (M5)

0

N/A

288.696

3.296E+00

9.365E-01



Hill

0

N/A

288.696

3.625E+00

6.199E-01



linear

2

0.404

286.508

4.783E+00

3.893E+00



polynomial, 3-
degree0

2

0.404

286.508

4.783E+00

3.893E+00



power

2

0.404

286.508

4.783E+00

3.893E+00

power bound hit (power = 1)

power,
unrestricted

1

0.483

287.189

6.795E-01

3.271E-03

unrestricted (power = 0.515)

a Non-constant variance model selected (p = 0.0320)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.2.11.2. Output for Selected Model: Exponential (M4)

Franc et al., 2001: S-D Rats, Relative Thymus Weight

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\l\Blood\91_Franc_2001_SD_RelThyWt_Exp_l.(d)

Gnuplot Plotting File:

Thu Apr 15 11:51:19 2010

Figure 5, SD rats, relative thymus weight

The form of the response function by Model:

Model 2
Model 3
Model 4
Model 5

Y[dose]
Y[dose]
Y[dose]
Y[dose]

exp{sign *	b * dose}

exp{sign *	(b * dosej^d}

[c-(c-l) *	exp{-b * dose}]

[c-(c-l) *	exp{-(b * dosej^d}

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;
sign = -1 for decreasing trend.

Model 2 is nested within Models 3 and 4.

This document is a draft for review purposes only and does not constitute Agency policy.

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Model 3 is nested within Model 5.
Model 4 is nested within Model 5.

Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)
Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values
Variable	Model 4

lnalpha	3.35464

rho	1.08199

a	105

b	0.0569979

c	0.108531

d	1

Parameter Estimates
Variable	Model 4

lnalpha	2.4312

rho	1.28672

a	110.959

b	0.0663498

c	0.146486

d	1

Table of Stats From Input Data

Dose	N	Obs Mean	Obs Std Dev

0	8	100	83.2

6.587	8	91.17	47.97

14.48	8	51.41	43.48

36.43	8	22.79	29.98

Estimated Values of Interest
Dose	Est Mean	Est Std	Scaled Residual

0	111	69.78	-0.4442

6.587	77.43	55.36	0.7019

14.48	52.49	43.11	-0.0709

36.43	24.7	26.54	-0.2031

Other models for which likelihoods are calculated:

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

This document is a draft for review purposes only and does not constitute Agency policy.

E-71	DRAFT—DO NOT CITE OR QUOTE


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Model A2 :	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma(i)^2

Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= exp(lalpha + log(mean(i) ) 'k rho)

Model R:	Yij	= Mu + e(i)

Var{e(ij)}	= Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	DF	AIC

A1	-141.9834	5	293.9669

A2	-137.5818	8	291.1637

A3	-138.3482	6	288.6964

R	-146.9973	2	297.9946

4	-138.4123	5	286.8245

Additive constant for all log-likelihoods =	-29.41. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Test 1: Does response and/or variances differ among Dose levels? (A2 vs. R)

Test 2: Are Variances Homogeneous? (A2 vs. A1)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 6a: Does Model 4 fit the data? (A3 vs 4)

Test

Test 1
Test 2
Test 3
Test 6a

Tests of Interest

-2*log(Likelihood Ratio)

18 . 83
8 .803
1. 533
0.1282

p-value

0.004459
0.03203
0.4647
0.7203

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose
levels, it seems appropriate to model the data.

The p-value for Test 2 is less than .1. A non-homogeneous
variance model appears to be appropriate.

The p-value for Test 3 is greater than .1. The modeled
variance appears to be appropriate here.

The p-value for Test 6a is greater than .1. Model 4 seems
to adeguately describe the data.

Benchmark Dose Computations:

Specified Effect = 0.100000

Risk Type = Relative deviation
Confidence Level = 0.950000

BMD =	1.87814

BMDL =	0.922136

This document is a draft for review purposes only and does not constitute Agency policy.

E-72	DRAFT—DO NOT CITE OR QUOTE


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E.2.11.3. Figure for Selected Model: Exponential (M4)

Exponential_beta Model 4 with 0.95 Confidence Level

150


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Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

lalpha	=	8.007 5

rho	=	0

beta_0	=	100

beta_l	=	0

beta~2	=	-0.475283

beta 3	=	0

Asymptotic Correlation Matrix of Parameter Estimates

lalpha
rho
beta_0
beta 1

The model parameter(s) -beta 2 -beta 3

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

lalpha
1

-0. 99
0. 018
0.0095

rho

-0. 99
1

-0.022
-0.0024

beta_0

0. 018
-0.022
1

-0. 87

beta_l

0.0095
-0.0024
-0. 87
1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
lalpha
rho

beta_0
beta_l
beta_2
beta 3

Estimate

2 . 8315
1.19884
94.5944
-1.97776
0
0

Std. Err.
1.71297
0. 416889
14.6685
0.509904
NA
NA

Lower Conf. Limit
-0.525852
0.381756
65.8446
-2 . 97715

Upper Conf. Limit
6.18885
2.01593
123.344
-0.978362

NA - Indicates that this parameter has hit a bound
implied by some ineguality constraint and thus
has no standard error.

Table of Data and Estimated Values of Interest

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0	8	100	94.6	83.2	63	0.243

6.587	8	91.2	81.6	48	57.6	0.471

14.48	8	51.4	66	43.5	50.7	-0.811

36.43	8	22.8	22.5	30	26.7	0.0269

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(iji

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij|

This document is a draft for review purposes only and does not constitute Agency policy.

E-74	DRAFT—DO NOT CITE OR QUOTE


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Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1	-141.983433	5	293.966865

A2	-137.581833	8	291.163667

A3	-138.348184	6	288.696368

fitted	-139.254163	4	286.508326

R	-146.997301	2	297.994602

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1
Test 2
Test 3
Test 4

18.8309
8.8032
1.5327
1.81196

0.004459
0.03203
0.4647
0.4041

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adeguately describe the data

Benchmark Dose Computation
Specified effect =	0.1

Risk Type	=	Relative risk

Confidence level =	0.95

BMD =	4.78292

BMDL =	3.8 932

This document is a draft for review purposes only and does not constitute Agency policy.

E-75	DRAFT—DO NOT CITE OR QUOTE


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l E.2.11.5. Figure for Additional Model Presented: Polynomial, 3-degree

Polynomial Model with 0.95 Confidence Level

dose

2	11:51 04/15 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-76	DRAFT—DO NOT CITE OR QUOTE


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E.2.12. Franc et al., 2001: L-E Rats, Relative Thymus Weight
E.2.12.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

z2 p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential (M2)

2

0.440

301.449

2.726E+00

1.212E+00



exponential (M3)

2

0.440

301.449

2.726E+00

1.212E+00

power hit bound (d = 1)

exponential
(M4)b

1

0.227

303.266

2.084E+00

5.926E-01



exponential (M5)

0

N/A

303.805

7.859E+00

9.801E-01



Hill

0

N/A

303.805

7.480E+00

7.512E-01



linear

2

0.304

302.186

5.045E+00

3.349E+00



polynomial, 3-
degree

2

0.304

302.186

5.045E+00

3.349E+00



power

2

0.304

302.186

5.045E+00

3.349E+00

power bound hit (power = 1)

power,
unrestricted

1

0.168

303.710

1.374E+00

9.032E-09

unrestricted (power = 0.601)

a Constant variance model selected (p = 0.5063)
b Best-fitting model, BMDS output presented in this appendix

E.2.12.2. Output for Selected Model: Exponential (M4)

Franc et al., 2001: L-E Rats, Relative Thymus Weight

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\l\Blood\92_Franc_2001_LE_RelThyWt_ExpCV_l.(d)

Gnuplot Plotting File:

Thu Apr 15 11:53:37 2010

Figure 5, L-E rats, relative thymus weight

The form of the response function by Model:

Model 2
Model 3
Model 4
Model 5

Y[dose]
Y[dose]
Y[dose]
Y[dose]

exp{sign *	b * dose}

exp{sign *	(b * dosej^d}

[c-(c-l) *	exp{-b * dose}]

[c-(c-l) *	exp{-(b * dosej^d}

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;
sign = -1 for decreasing trend.

Model 2 is nested within Models 3 and 4.
Model 3 is nested within Model 5.

Model 4 is nested within Model 5.

This document is a draft for review purposes only and does not constitute Agency policy.

E-77	DRAFT—DO NOT CITE OR QUOTE


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Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))
rho is set to 0.

A constant variance model is fit.

Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values
Variable	Model 4

Specified

lnalpha	8.1814

rho(S)	0

a	105

b	0.0506168

c	0.166582

d	1

Parameter Estimates
Variable	Model 4

lnalpha	8.22706

rho	0

a	105.977

b	0.0660042

c	0.221786

d	1

Table of Stats From Input Data

Dose	N	Obs Mean	Obs Std Dev

0	8	100	54.72

6.584	8	95.41	70.46

14.47	8	38.69	47.97

36.41	8	34.98	77.96

Estimated Values of Interest
Dose	Est Mean	Est Std	Scaled Residual

0	106	61.16	-0.2764

6.584	76.91	61.16	0.8555

14.47	55.24	61.16	-0.765

36.41	30.96	61.16	0.186

Other models for which

Model A1:	Yij

Var{e(ij)}

likelihoods are calculated:

= Mu(i) + e(ij)

= Sigma/N2

This document is a draft for review purposes only and does not constitute Agency policy.

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Model A2 :	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma(i)^2

Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= exp(lalpha + log(mean(i) ) 'k rho)

Model R:	Yij	= Mu + e(i)

Var{e(ij)}	= Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	DF	AIC

A1	-146.9024	5	303.8049

A2	-145.7361	8	307.4723

A3	-146.9024	5	303.8049

R	-150.6049	2	305.2098

4	-147.6329	4	303.2658

Additive constant for all log-likelihoods =	-29.41. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Test 1: Does response and/or variances differ among Dose levels? (A2 vs. R)

Test 2: Are Variances Homogeneous? (A2 vs. A1)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 6a: Does Model 4 fit the data? (A3 vs 4)

Test

Test 1
Test 2
Test 3
Test 6a

Tests of Interest

-2*log(Likelihood Ratio)

9.738
2 . 333
2 . 333
1. 461

p-value

0.1362
0.5063
0.5063
0.2268

The p-value for Test 1 is greater than .05. There may not be a
diffence between responses and/or variances among the dose levels
Modelling the data with a dose/response curve may not be appropriate.

The p-value for Test 2 is greater than .1. A homogeneous
variance model appears to be appropriate here.

The p-value for Test 3 is greater than .1. The modeled
variance appears to be appropriate here.

The p-value for Test 6a is greater than .1. Model 4 seems
to adeguately describe the data.

Benchmark Dose Computations:

Specified Effect = 0.100000

Risk Type = Relative deviation
Confidence Level = 0.950000

BMD =	2.0837 9

BMDL =	0.592601

This document is a draft for review purposes only and does not constitute Agency policy.

E-79	DRAFT—DO NOT CITE OR QUOTE


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l E.2.12.3. Figure for Selected Model: Exponential (M4)

Exponential_beta Model 4 with 0.95 Confidence Level

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2	11:53 04/15 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.2.13. Franc et al., 2001: HAV Rats, Relative Thymus Weight
E.2.13.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

z2 p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential
(M2)b

2

0.698

261.646

5.094E+00

3.132E+00



exponential (M3)

1

0.407

263.616

5.944E+00

3.140E+00



exponential (M4)

1

0.396

263.646

5.063E+00

1.864E+00



exponential (M5)

0

N/A

264.927

9.945E+00

2.127E+00



Hill

0

N/A

264.927

9.638E+00

1.853E+00



linear

2

0.645

261.804

6.874E+00

5.006E+00



polynomial, 3-
degree

2

0.645

261.804

6.874E+00

5.006E+00



power

2

0.645

261.804

6.874E+00

5.006E+00

power bound hit (power = 1)

power,
unrestricted

1

0.363

263.755

5.487E+00

2.573E-01

unrestricted (power = 0.881)

a Constant variance model selected (p = 0.4331)
b Best-fitting model, BMDS output presented in this appendix

E.2.13.2. Output for Selected Model: Exponential (M2)

Franc et al., 2001: HAV Rats, Relative Thymus Weight

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\l\Blood\93_Franc_2001_HW_RelThyWt_ExpCV_l.(d)

Gnuplot Plotting File:

Thu Apr 15 11:55:55 2010

Figure 5, H/W rats, relative thymus weight

The form of the response function by Model:

Model 2
Model 3
Model 4
Model 5

Y[dose]
Y[dose]
Y[dose]
Y[dose]

exp{sign *	b * dose}

exp{sign *	(b * dosej^d}

[c-(c-l) *	exp{-b * dose}]

[c-(c-l) *	exp{-(b * dosej^d}

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;
sign = -1 for decreasing trend.

Model 2 is nested within Models 3 and 4.
Model 3 is nested within Model 5.

Model 4 is nested within Model 5.

This document is a draft for review purposes only and does not constitute Agency policy.

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Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))
rho is set to 0.

A constant variance model is fit.

Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values
Variable	Model 2

Specified

lnalpha	6.96647

rho(S)	0

a	56.9433

b	0.0204806

c	0

d	1

Parameter Estimates
Variable	Model 2

lnalpha	6.98 8 95

rho	0

a	103.047

b	0.0206828

c	0

d	1

Table of Stats From Input Data
Dose	N	Obs Mean	Obs Std Dev

0	8	100	35.98

6.588	8	97.53	32.98

14.48	8	71.02	23.99

36.44	8	49.29	43.48

Estimated Values of Interest
Dose	Est Mean	Est Std	Scaled Residual

0	103	32.93	-0.2617

6.588	89.92	32.93	0.6532

14.48	76.38	32.93	-0.4596

36.44	48.49	32.93	0.06871

Other models for which

Model A1:	Yij

Var{e(ij)}

likelihoods are calculated:

= Mu(i) + e(ij)

= Sigma/N2

This document is a draft for review purposes only and does not constitute Agency policy.

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Model A2 :	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma(i)^2

Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= exp(lalpha + log(mean(i) ) 'k rho)

Model R:	Yij	= Mu + e(i)

Var{e(ij)}	= Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	DF	AIC

A1	-127.4636	5	264.9271

A2	-126.0925	8	268.185

A3	-127.4636	5	264.9271

R	-132.935	2	269.87

2	-127.8231	3	261.6463

Additive constant for all log-likelihoods =	-29.41. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Test

1:

Test

2 :

Test

3:

Test

4 :

Does response and/or variances differ among Dose levels:
Are Variances Homogeneous? (A2 vs. A1)

Are variances adeguately modeled? (A2 vs. A3)

Does Model 2 fit the data? (A3 vs. 2)

(A2 vs. R)

Test

Test 1
Test 2
Test 3
Test 4

Tests of Interest

-2*log(Likelihood Ratio)

13. 69
2.742
2.742
0.7192

p-value

0.03336
0.4331
0.4331
0. 698

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose
levels, it seems appropriate to model the data.

The p-value for Test 2 is greater than .1. A homogeneous
variance model appears to be appropriate here.

The p-value for Test 3 is greater than .1. The modeled
variance appears to be appropriate here.

The p-value for Test 4 is greater than .1. Model 2 seems
to adeguately describe the data.

Benchmark Dose Computations:

Specified Effect = 0.100000

Risk Type = Relative deviation
Confidence Level = 0.950000

BMD =	5.09411

BMDL =	3.13214

This document is a draft for review purposes only and does not constitute Agency policy.

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l E.2.13.3. Figure for Selected Model: Exponential (M2)

Exponential_beta Model 2 with 0.95 Confidence Level

dose

2	11:55 04/15 2010

3

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This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.2.14. Hojo et al., 2002: DRL Reinforce Per Minute
E.2.14.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

X2 P-
Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

Hill

1

0.101

4.465

1.667E+00

6.209E-08

n upper bound hit (n = 18)

linear

2

0.009

9.124

1.352E+01

6.020E+00



polynomial, 3-
degree

2

0.009

9.124

1.352E+01

6.020E+00



power

2

0.009

9.124

1.352E+01

6.020E+00

power bound hit (power =1)

power,
unrestricted

1

0.025

6.780

2.428E-01

1.070E-14

unrestricted (power = 0.103)

exponential (M2)

2

0.007

9.612

1.623E+01

8.673E+00



exponential (M3)

2

0.007

9.612

1.623E+01

8.673E+00

power hit bound (d = 1)

exponential
(M4)b

1

0.054

5.488

1.316E+00

2.367E-03



exponential (M5)

0

N/A

6.465

1.728E+00

9.452E-03



a Constant variance model selected (p = 0.4321)
b Best-fitting model, BMDS output presented in this appendix

E.2.14.2. Output for Selected Model: Exponential (M4)

Hojo et al., 2002: DRL Reinforce Per Minute

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\l\Blood\21_Hojo_2002_DRLrein_ExpCV_l.(d)

Gnuplot Plotting File:

Mon Feb 08 10:49:08 2010

Table 5, values adjusted by a constant to allow exponential model

The form of the response function by Model:

Model 2:	Y[dose] = a * exp{sign * b * dose}

Model 3:	Y[dose] = a * exp{sign * (b * dosej^d}

Model 4:	Y[dose] = a * [c-(c-l) * exp{-b * dose}]

Model 5:	Y[dose] = a * [c-(c-l) * exp{-(b * dosej^d}]

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;
sign = -1 for decreasing trend.

Model 2 is nested within Models 3 and 4.

Model 3 is nested within Model 5.

Model 4 is nested within Model 5.

This document is a draft for review purposes only and does not constitute Agency policy.

E-85	DRAFT—DO NOT CITE OR QUOTE


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Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))
rho is set to 0.

A constant variance model is fit.

Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values
Variable	Model 4

Specified

lnalpha	-1.29672

rho(S)	0

a	0.0817

b	0.15642

c	16.3733

d	1

Parameter Estimates
Variable	Model 4

lnalpha	-1.11961

rho	0

a	0.0547452

b	0.708154

c	18.214

d	1

Table of Stats From Input Data

Dose	N	Obs Mean	Obs Std Dev

0	5	0.086	0.448

1.625	5	0.536	0.821

4.169	6	1.274	0.54

10.7	5	0.737	0.443

Estimated Values of Interest
Dose	Est Mean	Est Std	Scaled Residual

0	0.05475	0.5713	0.1223

1.625	0.6989	0.5713	-0.6375

4.169	0.9479	0.5713	1.398

10.7	0.9966	0.5713	-1.016

Other models for which likelihoods are calculated:

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

This document is a draft for review purposes only and does not constitute Agency policy.

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Model A2 :	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma(i)^2

Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= exp(lalpha + log(mean(i) ) 'k rho)

Model R:	Yij	= Mu + e(i)

Var{e(ij)}	= Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	DF	AIC

A1	3.11555	5	3.7689

A2	4.489557	8	7.020886

A3	3.11555	5	3.7689

R	-2.435087	2	8.870174

4	1.255891	4	5.488219

Additive constant for all log-likelihoods =	-19.3. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Test 1: Does response and/or variances differ among Dose levels? (A2 vs. R)

Test 2: Are Variances Homogeneous? (A2 vs. A1)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 6a: Does Model 4 fit the data? (A3 vs 4)

Test

Test 1
Test 2
Test 3
Test 6a

Tests of Interest

-2*log(Likelihood Ratio)

13. 85
2.748
2.748
3.719

p-value

0.03137
0.4321
0.4321
0.05379

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose
levels, it seems appropriate to model the data.

The p-value for Test 2 is greater than .1. A homogeneous
variance model appears to be appropriate here.

The p-value for Test 3 is greater than .1. The modeled
variance appears to be appropriate here.

The p-value for Test 6a is less than .1. Model 4 may not adeguately
describe the data; you may want to consider another model.

Benchmark Dose Computations:

Specified Effect = 1.000000

Risk Type = Estimated standard deviations from control
Confidence Level = 0.950000

BMD =	1.31616

This document is a draft for review purposes only and does not constitute Agency policy.

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1	E'.MDL = 0.00236664

2

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4	E.2.14.3. Figure for Selected Model: Exponential (M4)

Exponential Model 4 with 0.95 Confidence Level

dose

5	10:49 02/08 2010

6

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-88	DRAFT—DO NOT CITE OR QUOTE


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E.2.15. Hojo et al., 2002: DRL Response Per Minute

E.2.15.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

r p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

Hill

0

N/A

126.353

1.373E+00

1.070E-14



linear

2

0.006

132.243

1.064E+01

5.340E+00



polynomial, 3-
degree

2

0.006

132.243

1.064E+01

5.340E+00



power

2

0.006

132.243

1.064E+01

5.340E+00

power bound hit (power = 1)

power,
unrestricted

2

0.741

122.455

1.070E+03

error

unrestricted (power = 0)

exponential (M2)

2

0.570

122.980

5.027E-01

error



exponential (M3)

2

0.570

122.980

5.027E-01

error

power hit bound (d = 1)

exponential
(M4)b

1

0.477

124.360

3.813E-01

1.553E-02



exponential (M5)

0

N/A

126.353

8.430E-01

2.221E-02



a Constant variance model selected (p = 0.3004)
b Best-fitting model, BMDS output presented in this appendix

E.2.15.2. Output for Selected Model: Exponential (M4)

Hojo et al., 2002: DRL Response Per Minute

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\l\Blood\23_Hojo_2002_DRLresp_ExpCV_l.(d)

Gnuplot Plotting File:

Mon Feb 08 10:50:10 2010

Table 5, values adjusted by a constant to allow exponential model

The form of the response function by Model:

Model 2
Model 3
Model 4
Model 5

Y[dose]
Y[dose]
Y[dose]
Y[dose]

exp{sign *	b * dose}

exp{sign *	(b * dosej^d}

[c-(c-l) *	exp{-b * dose}]

[c-(c-l) *	exp{-(b * dosej^d}

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;
sign = -1 for decreasing trend.

Model 2 is nested within Models 3 and 4.
Model 3 is nested within Model 5.

Model 4 is nested within Model 5.

This document is a draft for review purposes only and does not constitute Agency policy.

E-89	DRAFT—DO NOT CITE OR QUOTE


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Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))
rho is set to 0.

A constant variance model is fit.

Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values
Variable	Model 4

Specified

lnalpha	4.51689

rho(S)	0

a	24.6362

b	0.379327

c	0.0184785

d	1

Parameter Estimates
Variable	Model 4

lnalpha	4.54096

rho	0

a	23.4674

b	1.61185

c	0.101317

d	1

Table of Stats From Input Data

Dose	N	Obs Mean	Obs Std Dev

0	5	23.46	7.986

1.625	5	4.013	10.96

4.169	6	0.478	7.194

10.7	5	4.594	15.23

Estimated Values of Interest
Dose	Est Mean	Est Std	Scaled Residual

0	23.47	9.684	-0.001008

1.625	3.915	9.684	0.02265

4.169	2.403	9.684	-0.4869

10.7	2.378	9.684	0.5118

Other models for which likelihoods are calculated:

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

This document is a draft for review purposes only and does not constitute Agency policy.

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Model A2 :	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma(i)^2

Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= exp(lalpha + log(mean(i) ) 'k rho)

Model R:	Yij	= Mu + e(i)

Var{e(ij)}	= Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	DF	AIC

A1	-57.92733	5	125.8547

A2	-56.09669	8	128.1934

A3	-57.92733	5	125.8547

R	-64.49611	2	132.9922

4	-58.1801	4	124.3602

Additive constant for all log-likelihoods =	-19.3. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Test 1: Does response and/or variances differ among Dose levels? (A2 vs. R)

Test 2: Are Variances Homogeneous? (A2 vs. A1)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 6a: Does Model 4 fit the data? (A3 vs 4)

Test

Test 1
Test 2
Test 3
Test 6a

Tests of Interest

-2*log(Likelihood Ratio)

16.8
3. 661
3. 661
0.5056

p-value

0.01005
0.3004
0.3004
0.4771

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose
levels, it seems appropriate to model the data.

The p-value for Test 2 is greater than .1. A homogeneous
variance model appears to be appropriate here.

The p-value for Test 3 is greater than .1. The modeled
variance appears to be appropriate here.

The p-value for Test 6a is greater than .1. Model 4 seems
to adeguately describe the data.

Benchmark Dose Computations:

Specified Effect = 1.000000

Risk Type = Estimated standard deviations from control
Confidence Level = 0.950000

BMD =	0.381347

This document is a draft for review purposes only and does not constitute Agency policy.

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1	E'.MDL = 0.0155267

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4	E.2.15.3. Figure for Selected Model: Exponential (M4)

Exponential Model 4 with 0.95 Confidence Level

dose

5	10:50 02/08 2010

6

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-92	DRAFT—DO NOT CITE OR QUOTE


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E.2.16. Kattainen et al., 2001: 3rd Molar Eruption, Female
E.2.16.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

logistic

3

0.360

88.508

9.223E+00

6.671E+00

negative intercept (intercept =
-1.586)

log-logistica

3

0.982

85.227

2.399E+00

1.328E+00

slope bound hit (slope = 1)

log-probit

3

0.522

87.424

7.346E+00

4.561E+00

slope bound hit (slope =1)

probit

3

0.379

88.352

8.802E+00

6.549E+00

negative intercept (intercept =
-0.975)

multistage, 4-
degree

3

0.781

86.155

4.042E+00

2.626E+00

final B = 0

log-logistic,
unrestricted b

2

0.949

87.162

1.931E+00

1.840E-01

unrestricted (slope = 0.91)

log-probit,
unrestricted

2

0.941

87.181

2.075E+00

2.395E-01

unrestricted (slope = 0.549)

a Best-fitting model, BMDS output presented in this appendix
b Alternate model, BMDS output also presented in this appendix

E.2.16.2. Output for Selected Model: Log-Logistic

Kattainen et al., 2001: 3rd Molar Eruption, Female

Logistic Model. (Version: 2.12; Date: 05/16/2008)

Input Data File: C:\l\Blood\24_Katt_2001_Erup_LogLogistic_BMRl.(d)

Gnuplot Plotting File: C:\l\Blood\24_Katt_2001_Erup_LogLogistic_BMRl.plt

Mon Feb 08 10:50:39 2010

Figure 2

The form of the probability function is:

P[response] = background+(1-background)/[1+EXP(-intercept-slope*Log(dose))]

Dependent variable = DichEff
Independent variable = Dose

Slope parameter is restricted as slope >= 1
Total number of observations = 5

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

User has chosen the log transformed model

This document is a draft for review purposes only and does not constitute Agency policy.

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Default Initial Parameter Values
background =	0.0625

intercept =	-3.07535

slope =	1

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -slope

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

background intercept

background	1	-0.53

intercept	-0.53	1

Parameter Estimates

Variable
background
intercept
slope

Estimate

0.0699339
-3.07219
1

Std. Err.

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

Indicates that this value is not calculated.







Analysis

of

Deviance Table







Model

Log(likelihooc

) #

Param's Deviance Test

d

f. P-value

Full

model



-40.5286



5







Fitted

model



-40.6137



2 0.170195

3

0.9823

Reduced

model



-50.7341



1 20

411

4

0.0004142



AIC:



85.2274



















Goodness of Fit























Scaled

Dose

Est

. Prob

Expected

Observed

Size



Residual

0.0000

0.

0 6 9 9

1.

119

1. 000

16



-0.117

2 2297

0.

1570

2 .

6 6 9

3. 000

17



0.221

6.2523

0.

2788

4 .

182

4 . 000

15



-0.105

16.0824

0.

4670

5.

604

6. 000

12



0.229

46.8576

0.

7066

13.

426

13.000

19



-0.215

Chi ^2 = 0

. 17

d. f.

= 3

P

-value = 0.9820







Benchmark Dose Computation
Specified effect =	0.1

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	2.3987 9

BMDL =	1.32815

This document is a draft for review purposes only and does not constitute Agency policy.

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E.2.16.3. Figure for Selected Model: Log-Logistic

Log-Logistic Model with 0.95 Confidence Level

0.8

"O


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Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-006
Parameter Convergence has been set to: le-008

User has chosen the log transformed model

Default Initial Parameter Values
background =	0.0625

intercept =	-2.7659

slope =	0.901885

Asymptotic Correlation Matrix of Parameter Estimates
background intercept	slope

background	1	-0.52	0.38

intercept	-0.52	1	-0.94

slope	0.38	-0.94	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

background	0.0630045	*	*	*

intercept	-2.79616	*	*	*

slope	0.910333	*	*	*

* - Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-40.5286	5

Fitted model -40.5811 3	0.105049 2	0.9488

Reduced model -50.7341 1	20.411 4	0.0004142

AIC:	87.1622

Goodness of Fit

Scaled

Dose	Est. Prob. Expected Observed	Size	Residual

0.0000

0

0630

1. 008

1

000

16

-0

008

2.2297

0

1683

2 .862

3

000

17

0

090

6.2523

0

2922

4 . 383

4

000

15

-0

217

16.0824

0

4692

5. 631

6

000

12

0

214

46.8576

0

6903

13.116

13

000

19

-0

058

Chi/N2 = 0.10	d.f. = 2	P-value = 0.94 91

Benchmark Dose Computation
Specified effect =	0.1

Risk Type	=	Extra risk

Confidence level =	0.95

This document is a draft for review purposes only and does not constitute Agency policy.

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BMD =	1.9307 9

BMDL =	0.184 03

E.2.16.5. Figure for Additional Model Presented: Log-Logistic, Unrestricted

Log-Logistic Model with 0.95 Confidence Level

"O

(D

-t—<

o

CD
!t=
<
c
o
¦+-'
o
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0.6

0.4

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0 :
BMDL

10:50 02/08 2010

dose

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-97	DRAFT—DO NOT CITE OR QUOTE


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E.2.17. Kattainen et al., 2001: 3rd Molar Length, Female
E.2.17.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential (M2)

3

<0.0001

124.866

1.669E+01

9.933E+00



exponential (M3)

3

<0.0001

124.866

1.669E+01

9.933E+00

power hit bound (d = 1)

exponential (M4)

2

0.002

147.120

4.237E-01

2.530E-01



exponential (M5)

2

0.002

147.120

4.237E-01

2.530E-01

power hit bound (d = 1)

Hill b

2

0.022

152.239

3.132E-01

1.679E-01

n lower bound hit (n = 1)

linear

3

<0.0001

124.024

1.982E+01

1.277E+01



polynomial, 4-
degree

3

<0.0001

124.024

1.982E+01

1.277E+01



power

3

<0.0001

124.024

1.982E+01

1.277E+01

power bound hit (power =1)

Hill, unrestricted0

1

<0.0001

130.856

1.215E-02

error

unrestricted (n = 13.042)

power,
unrestricted

2

0.263

157.201

1.964E-03

8.002E-06

unrestricted (power = 0.195)

a Non-constant variance model selected (p = <0.0001)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.2.17.2. Output for Selected Model: Hill

Kattainen et al., 2001: 3rd Molar Length, Female

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\l\Blood\25_Katt_2001_Length_Hill_l.(d)

Gnuplot Plotting File: C:\l\Blood\25_Katt_2001_Length_Hill_l.plt

Mon Feb 08 10:51:09 2010

Figure 3 female only

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = Mean
Independent variable = Dose

Power parameter restricted to be greater than 1

This document is a draft for review purposes only and does not constitute Agency policy.

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The variance is to be modeled as Var(i) = exp(lalpha + rho * ln(mean(i)))

Total number of dose groups = 5

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

lalpha
rho

intercept

-2 . 37155

0

1. 85591
-0.507874
0. 845932
2 . 03129

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -n

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

lalpha
rho

intercept

lalpha
1

-0. 98
-0.16
0.84
-0.38

rho

-0. 98
1

0.2
-0.79
0.4

intercept

-0.16
0.2
1

-0.3
-0.11

v

0.84
-0.79
-0.3
1

-0.52

k

-0.38
0.4
-0.11
-0.52
1

Parameter Estimates

Variable
lalpha
rho

intercept

k

Estimate
3.31084
-14.2657
1. 85483
-0.453667
1

1. 91219

Std. Err.
1.404
2.62739
0.0159477
0.0620227
NA

0.624785

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

0.559057
-19.4153
1.82357
-0.575229

0. 687636

6. 06262
-9.11612

1.88609
-0.332105

3.13675

NA - Indicates that this parameter has hit a bound
implied by some ineguality constraint and thus
has no standard error.

Table of Data and Estimated Values of Interest

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0

16

i—1

CO
G\

i—1

CO
CJ1

0.0661

0. 0639

0.0674

2 . 23

17

1 . 58

1 . 61

0.185

0.175

-0.789

6.252

15

1 . 6

1 . 51

0.265

0.28

1. 22

i—1

G\

O
CO

12

1 . 5

1 .45

0.221

0.371

o
en

i—1

46.86

19

1. 35

1 .42

0.515

0. 431

-0.716

Model

Descriptions for

likelihoods

calculated





This document is a draft for review purposes only and does not constitute Agency policy.

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Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2 :	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model
A1

A2
A3

fitted
R

Log(likelihood)
56.758717
85.856450
84.934314
81.119648
45.373551

10

7
5
2

AIC
-101.517434
-151.712901
-155.868628
-152.239295
-86.747101

Test

1

Test

2

Test

3

Test

4

(Note:

Explanation of Tests

Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1

Test 2
Test 3
Test 4

80.9658
58 .1955
1.84427
7 . 62933

<.0001
<.0001
0.6053
0.02205

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is less than .1. You may want to try a different
model

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	0.313211

BMDL =	0.167922

This document is a draft for review purposes only and does not constitute Agency policy.

E-100 DRAFT—DO NOT CITE OR QUOTE


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E.2.17.3. Figure for Selected Model: Hill

Hill Model with 0.95 Confidence Level

1.9

1.8

1.7


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Total number of dose groups = 5

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

lalpha =	-2.37155

rho =	0

intercept =	1.85591

v =	-0.507874

n =	0.845932

k =	2 . 03129

Asymptotic Correlation Matrix of Parameter Estimates

lalpha	rho	intercept	v	n	k

lalpha 1	-0.98	-0.16	0.84	1.4e-016	3.3e-017

rho -0.98	1	0.22	-0.77	-2.2e-016	-5.1e-017

intercept -0.16	0.22	1	-0.35	6e-017	1.4e-017

v 0.84	-0.77	-0.35	1	-2.6e-016	-6.2e-017

n 1.4e-016	-2.2e-016	6e-017	-2.6e-016	1	1

k 3.3e-017	-5.1e-017	1.4e-017	-6.2e-017	1	1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
lalpha
rho

intercept

Estimate

4 . 25154
-15.7639
1. 85591
-0.357293
13.0417
0.0136512

Std. Err.
1.5913
2.90127
0.0160104
0.0463784
4.64308e+013
2.57737e+011

Lower Conf. Limit

1.13265
-21.4503
1. 82453
-0.448193
-9.10027e+013
-5.05155e+011

Upper Conf. Limit

7.37044
-10.0776
1.88729
-0.266393
9.10027e+013
5. 05155e + 011

Table of Data and Estimated Values of Interest

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0

2 . 23
6.252
16. 08
46.86

16

17
15
12
19

1.86
1. 58
1. 6
1. 5
1. 35

1.86
1. 5
1. 5
1. 5
1. 5

0.0661

0.185
0.265
0.221
0.515

0. 064
0.345
0.345
0.345
0.345

2.09e-009
0. 937
1.09
0.0534
-1. 9

Model Descriptions for likelihoods calculated

Model A1:	Yij =	Mu(i) + e(ij)

Var{e(ij)} =	Sigma/'2

Model A2:	Yij =	Mu(i) + e(ij)

Var{e(ij)} =	Sigma(i)^2

This document is a draft for review purposes only and does not constitute Agency policy.

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Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1	56.758717	6	-101.517434

A2	85.856450	10	-151.712901

A3	84.934314	7	-155.868628

fitted	71.427978	6	-130.855955

R	45.373551	2	-86.747101

Explanation of Tests

Test 1:

Test

2

Test

3

Test

4

Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	80.9658	8	<.0001

Test 2	58.1955	4	<.0001

Test 3	1.84427	3	0.6053

Test 4	27.0127	1	<.0001

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is less than .1. You may want to try a different
model

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	0.012148

BMDL computation failed.

This document is a draft for review purposes only and does not constitute Agency policy.

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l E.2.17.5. Figure for Additional Model Presented: Hill, Unrestricted

Hill Model

CD
CO
c
o

Q.

CO
CD

a:

c
m

CD

19 r _

1.7

1.6

1.5

1.4

1.3

1.2

1.1

dose

10:51 02/08 2010

This document is a draft for review purposes only and does not constitute Agency policy.

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E.2.18. Keller et al., 2007: Missing Mandibular Molars, CBA J
E.2.18.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

r p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

gamma

1

0.105

52.510

3.342E+00

8.986E-01



logistic

2

0.335

49.984

3.069E+00

2.212E+00

negative intercept (intercept =
-3.414)

log-logistic

1

0.105

52.524

4.009E+00

2.411E+00



log-probit

1

0.105

52.524

3.845E+00

2.421E+00



multistage, 1-
degreea

3

0.255

50.425

1.091E+00

7.624E-01



multistage, 2-
degree

1

0.122

51.391

1.916E+00

9.654E-01



multistage, 3-
degree

1

0.150

50.853

1.713E+00

9.584E-01



probit

2

0.342

49.904

2.927E+00

2.053E+00

negative intercept (intercept =
-1.873)

Weibull

1

0.108

52.219

2.744E+00

9.350E-01



a Best-fitting model, BMDS output presented in this appendix

E.2.18.2. Output for Selected Model: Multistage, 1-Degree

Keller et al., 2007: Missing Mandibular Molars, CBA J

Multistage Model. (Version: 3.0; Date: 05/16/2008)

Input Data File: C:\l\Blood\26_Keller_2007_Molars_Multil_l.(d)

Gnuplot Plotting File: C:\l\Blood\26_Keller_2007_Molars_Multil_l.plt

Mon Feb 08 10:51:47 2010

Table 1 using mandibular molars only

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = DichEff
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0

This document is a draft for review purposes only and does not constitute Agency policy.

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Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
Background =	0

Beta(1) = 3.03988e+018

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -Background

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Beta(1)

Beta(1)	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0	*	*	*

Beta(1)	0.096571	*	*	*

Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-21.5798	4

Fitted model -24.2126 1	5.26564 3	0.1533

Reduced model -71.326 1	99.4926 3	<.0001

AIC:	50.4251

Goodness of Fit

Scaled

Dose	Est. Prob. Expected Observed	Size	Residual

0.0000

0.0000

0. 000

0. 000

29

0. 000

0.5374

0.0506

1.163

2 . 000

23

0.796

4.2881

0.3391

9. 833

6. 000

29

-1.504

34.0560

0.9627

28.881

30.000

30

1. 078

Chi/N2 = 4.06	d.f. = 3	P-value = 0.2554

Benchmark Dose Computation
Specified effect =	0.1

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	1.09102

BMDL =	0.762404

This document is a draft for review purposes only and does not constitute Agency policy.

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1

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3

4	Taken together, (0.762404, 1.56496) is a 90	% two-sided confidence

5	interval for the EMD

6

7

8	E.2.18.3. Figure for Selected Model: Multistage, 1-Degree

Multistage Model with 0.95 Confidence Level

dose

9	10:51 02/08 2010

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E.2.19. Kociba et al., 1978: Urinary Coproporphyrin, Females
E.2.19.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential (M2)

2

<0.0001

82.975

2.378E+01

1.340E+01



exponential (M3)

2

<0.0001

82.975

2.378E+01

1.340E+01

power hit bound (d = 1)

exponential
(M4)b

1

0.006

73.823

1.566E+00

7.180E-01



exponential (M5)

0

N/A

69.047

6.225E+00

1.586E+00



Hill

0

N/A

69.047

5.473E+00

error



linear

2

<0.001

82.233

1.790E+01

3.862E+00



polynomial, 3-
degree

2

<0.001

82.233

1.790E+01

3.862E+00



power

2

<0.001

82.233

1.790E+01

3.862E+00

power bound hit (power =1)

power,
unrestricted

1

<0.001

78.691

1.148E+00

8.984E-09

unrestricted (power = 0.416)

a Non-constant variance model selected (p = 0.0298)
b Best-fitting model, BMDS output presented in this appendix

E.2.19.2. Output for Selected Model: Exponential (M4)

Kociba et al., 1978: Urinary Coproporphyrin, Females

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\l\Blood\29_Kociba_l978_Copro_Exp_l.(d)

Gnuplot Plotting File:

Mon Feb 08 10:52:47 2010

Table2-UrinaryCoproporphyrin

The form of the response function by Model:

Model 2
Model 3
Model 4
Model 5

Y[dose]
Y[dose]
Y[dose]
Y[dose]

exp{sign *	b * dose}

exp{sign *	(b * dosej^d}

[c-(c-l) *	exp{-b * dose}]

[c-(c-l) *	exp{-(b * dosej^d}

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;
sign = -1 for decreasing trend.

Model 2 is nested within Models 3 and 4.
Model 3 is nested within Model 5.

Model 4 is nested within Model 5.

This document is a draft for review purposes only and does not constitute Agency policy.

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Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)
Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values
Variable	Model 4

lnalpha	-5.58269

rho	2.98472

a	8.17

b	0.0692478

c	2.23623

d	1

Parameter Estimates
Variable	Model 4

lnalpha	-4.90852

rho	2.80743

a	8.91071

b	0.15304

c	1.97526

d	1

Table of Stats From Input Data

Dose	N	Obs Mean	Obs Std Dev

0	5	9.8	1.3

1.547	5	8.6	2

7.155	5	16.4	4.7

38.56	5	17.4	4

Estimated Values of Interest
Dose	Est Mean	Est Std	Scaled Residual

0	8.911	1.852	1.074

1.547	10.74	2.407	-1.991

7.155	14.69	3.736	1.021

38.56	17.58	4.805	-0.08246

Other models for which likelihoods are calculated:

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

This document is a draft for review purposes only and does not constitute Agency policy.

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Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= exp(lalpha + log(mean(i) ) 'k rho)

Model R:	Yij	= Mu + e(i)

Var{e(ij)}	= Sigma^2

Likelihoods of Interest
Model	Log(likelihood)	DF	AIC

A1

-31.69739

5

73

39478

A2

-27 . 21541

8

70

43081

A3

-28.16434

6

68

32868

R

-41. 73188

2

87

46376

4

-31.91136

5

73

82272

Additive constant for all log-likelihoods =	-18.38. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Test

1:

Does response

and/or variances differ among Dose levels? (A2 vs. R)

Test

2 :

Are Variances

Homogeneous? (A2 vs. A1)

Test

3:

Are variances

adequately modeled? (A2 vs. A3)

Test 6a: Does Model 4 fit the data? (A3 vs 4)

Test

Test 1
Test 2
Test 3
Test 6a

Tests of Interest

-2*log(Likelihood Ratio)

29. 03
8 . 964
1.898
7 . 494

p-value

C 0.0001
0.02977
0.3872
0.00619

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose
levels, it seems appropriate to model the data.

The p-value for Test 2 is less than .1. A non-homogeneous
variance model appears to be appropriate.

The p-value for Test 3 is greater than .1. The modeled
variance appears to be appropriate here.

The p-value for Test 6a is less than .1. Model 4 may not adeguately
describe the data; you may want to consider another model.

Benchmark Dose Computations:

Specified Effect = 1.000000

Risk Type = Estimated standard deviations from control
Confidence Level = 0.950000

BMD =	1.56562

BMDL =	0.718033

This document is a draft for review purposes only and does not constitute Agency policy.

E-l 10 DRAFT—DO NOT CITE OR QUOTE


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l E.2.19.3. Figure for Selected Model: Exponential (M4)

Exponential Model 4 with 0.95 Confidence Level

dose

2	10:52 02/08 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.2.20. Kociba et al., 1978: Uroporphyrin per Creatinine, Female
E.2.20.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

r p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential (M2)

2

0.755

-93.828

1.641E+01

1.259E+01



exponential (M3)

2

0.755

-93.828

1.641E+01

1.259E+01

power hit bound (d = 1)

exponential (M4)

1

0.499

-91.935

1.216E+01

3.958E+00



exponential (M5)

0

N/A

-90.190

7.542E+00

4.128E+00



Hill

0

N/A

-90.190

7.607E+00

3.966E+00



linear b

2

0.793

-93.928

1.306E+01

9.287E+00



polynomial, 3-
degree

2

0.793

-93.928

1.306E+01

9.287E+00



power

1

0.497

-91.928

1.326E+01

9.287E+00



a Constant variance model selected (p = 0.4919)
b Best-fitting model, BMDS output presented in this appendix

E.2.20.2. Output for Selected Model: Linear

Kociba et al., 1978: Uroporphyrin per Creatinine, Female

Polynomial Model. (Version: 2.13; Date: 04/08/2008)

Input Data File: C:\l\Blood\28_Kociba_l978_Uropor_LinearCV_l.(d)

Gnuplot Plotting File: C:\l\Blood\28_Kociba_197 8_Uropor_LinearCV_l.plt

Mon Feb 08 10:52:17 2010

Table 2

The form of the response function is:

Y[dose] = beta_0 + beta_l*dose + beta_2*dose/N2 + ...

Dependent variable = Mean
Independent variable = Dose
rho is set to 0

Signs of the polynomial coefficients are not restricted
A constant variance model is fit

Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

This document is a draft for review purposes only and does not constitute Agency policy.

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Default Initial Parameter Values
alpha = 0.0030385

rho =	0 Specified

beta_0 =	0.149139

beta 1 = 0.00381789

Asymptotic Correlation Matrix of Parameter Estimates

The model parameter(s) -rho

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha
beta_0
beta 1

alpha
1

1. 9e-009
-2.6e-009

beta_0

1.9e-009
1

-0.6

beta_l
-2 . 6e-009
-0.6
1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
alpha
beta_0
beta 1

Estimate

0. 00248773
0.149139
0.00381789

Std. Err.

0. 000786688
0.0139684
0.000711776

Lower Conf. Limit

0.000945846
0.121761
0.00242284

Upper Conf. Limit

0. 00402961
0.176517
0.00521295

Table of Data and Estimated Values of Interest

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0	5

1.547	5

7.155	5

38.56	5

0.157

0.143
0.181
0.296

0.149

0.155
0.176
0.296

0. 05
0. 037
0. 053
0. 074

0. 0499

0. 0499
0. 0499
0. 0499

0.352
-0.54
0.204
-0.0161

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model
A1

Log(likelihood)
50.195349

Param's
5

AIC
-90.390697

This document is a draft for review purposes only and does not constitute Agency policy.

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A2	51.400051	8	-86.800103

A3	50.195349	5	-90.390697

fitted	49.963863	3	-93.927727

R	41.049755	2	-78.099510

Explanation of Tests

Test 1:

Test

2

Test

3

Test

4

Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	20.7006	6	0.002076

Test 2	2.40941	3	0.4919

Test 3	2.40941	3	0.4919

Test 4	0.46297	2	0.7934

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than .1. A homogeneous variance
model appears to be appropriate here

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adeguately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	13.064

BMDL =	9.2 8715

This document is a draft for review purposes only and does not constitute Agency policy.

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E.2.20.3. Figure for Selected Model: Linear

Linear Model with 0.95 Confidence Level

dose

10:52 02/08 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.2.21. Latchoumycandane and Mathur, 2002: Sperm Production
E.2.21.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

X2 P-
Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential (M2)

2

<0.0001

93.831

1.739E+01

9.432E+00



exponential (M3)

2

<0.0001

93.831

1.739E+01

9.432E+00

power hit bound (d = 1)

exponential (M4)

1

0.700

75.261

1.912E-01

7.976E-02



exponential (M5)

0

N/A

77.263

2.925E-01

7.970E-02



Hill b

1

0.962

75.115

1.171E-01

1.324E-02

n lower bound hit (n = 1)

linear

2

<0.0001

94.250

1.995E+01

1.212E+01



polynomial, 3-
degree

2

<0.0001

94.250

1.995E+01

1.212E+01



power

2

<0.0001

94.250

1.995E+01

1.212E+01

power bound hit (power = 1)

Hill, unrestricted0

0

N/A

77.113

9.955E-02

1.228E-09

unrestricted (n = 0.916)

power,
unrestricted

1

0.501

75.566

6.921E-06

6.921E-06

unrestricted (power = 0.087)

a Constant variance model selected (p = 0.8506)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.2.21.2. Output for Selected Model: Hill

Latchoumycandane and Mathur, 2002: Sperm Production

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\l\Blood\30_Latch_2002_Sperm_HillCV_l.(d)

Gnuplot Plotting File: C:\l\Blood\30_Latch_2002_Sperm_HillCV_l.plt

Mon Feb 08 10:53:26 2010

(xlO^) Table 1 without Vitamin E

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = Mean
Independent variable = Dose
rho is set to 0

This document is a draft for review purposes only and does not constitute Agency policy.

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Power parameter restricted to be greater than 1
A constant variance model is fit

Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

alpha
rho

intercept

7 . 23328

0

22.19
-9.09
1. 93059
0.546864

Specified

Asymptotic Correlation Matrix of Parameter Estimates

alpha
intercept

The model parameter(s) -rho -n

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha
1

-2 . 2e-009
-3.7e-008
-5.9e-009

intercept
-2 . 2e-009
1

-0.76
-0.23

v

-3.7e-008
-0.76
1

-0.24

k

-5.9e-009
-0.23
-0.24
1

Parameter Estimates

Variable
alpha
intercept

k

Estimate

6.0283
22.1894
-9.16715
1

0.320198

Std. Err.
1.74022
1.00236
1.30966
NA

0.220443

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

2.61753
20.2248
-11.734

-0.111862

9. 43907
24 .154
-6.60026

0.752259

NA - Indicates that this parameter has hit a bound
implied by some ineguality constraint and thus
has no standard error.

Table of Data and Estimated Values of Interest

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0	6	22.2	22.2	2.67	2.46	0.000631

0.7845 6	15.7 15.7	2.65 2.46	-0.00931

4.651	6	13.7	13.6	2.19	2.46	0.0372

27.27	6	13.1	13.1	3.16	2.46	-0.0285

Model Descriptions for likelihoods calculated
Model A1:	Yij = Mu(i) + e(ij)

This document is a draft for review purposes only and does not constitute Agency policy.

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Var{e(ij)} = Sigma^2

Model A2 :	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma^2
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model

Log(likelihood)

# Param's

AIC

A1

-33.556444

5

77 . 112888

A2

-33.158811

8

82.317623

A3

-33.556444

5

77 . 112888

fitted

-33.557588

4

75.115176

R

-47 . 392394

2

98 .784788

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1
Test 2
Test 3
Test 4

28.4672
0.795266
0.795266
0.00228746

<.0001
0.8506
0.8506
0.9619

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than .1. A homogeneous variance
model appears to be appropriate here

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adeguately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	0.117131

BMDL =	0.0132353

This document is a draft for review purposes only and does not constitute Agency policy.

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E.2.21.3. Figure for Selected Model: Hill

Hill Model with 0.95 Confidence Level

dose

10:53 02/08 2010

E.2.21.4. Output for Additional Model Presented: Hill, Unrestricted
Latchoumycandane and Mathur, 2002: Sperm Production

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\l\Blood\30_Latch_2002_Sperm_HillCV_U_l.(d)

Gnuplot Plotting File: C:\l\Blood\30_Latch_2002_Sperm_HillCV_U_l.plt

Mon Feb 08 10:53:26 2010

(xl0^6) Table 1 without Vitamin E

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = Mean
Independent variable = Dose
rho is set to 0

Power parameter is not restricted
A constant variance model is fit

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

alpha =	7.23328

rho =	0 Specified

intercept =	22.19

v =	-9.09

n =	1.93059

k =	0.546864

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -rho

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha
intercept

alpha
1

-9.8e-009
1.6e-007
1.6e-007
1.2e-007

intercept
-9.8e-009
1

-0.5

-0.015
-0.13

v

1.6e-007
-0.5

1

0.76
0.56

n

1.6e-007
-0.015
0.76
1

0.86

k

1. 2e-007
-0.13
0.56
0.86
1

Parameter Estimates

Variable
alpha
intercept

Estimate

6.02773
22.19
-9.23667
0. 916265
0.301742

Std

Err.
1.74006
1.00231
2.03204
1.66287
0.440535

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

2.61728
20.2255
-13.2194
-2 . 34291
-0.561692

9. 43818
24 .1545
-5.25394
4 .17544
1.16518

Table of Data and Estimated Values of Interest

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0	6 22.2 22.2 2.67	2.46	3.4e-008

0.7845	6 15.7 15.7 2.65 2.46	-1.51e-007

4.651	6 13.7 13.6 2.19	2.46	2.62e-007

27.27	6 13.1 13.1 3.16	2.46	-5.45e-007

Degrees	of freedom for Test A3 vs fitted <= 0

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

This document is a draft for review purposes only and does not constitute Agency policy.

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Model A2 :	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma^2
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model

Log(likelihood)

# Param's

AIC

A1

-33.556444

5

77 . 112888

A2

-33.158811

8

82.317623

A3

-33.556444

5

77 . 112888

fitted

-33.556444

5

77 . 112888

R

-47 . 392394

2

98 .784788

Explanation of Tests

Test 1:

Test 2
Test 3
Test 4
(Note:

Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1
Test 2
Test 3
Test 4

28.4672
0.795266
0.795266
>.96332e-013

<.0001
0.8506
0.8506
NA

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than
model appears to be appropriate here

.1. A homogeneous variance

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

NA - Degrees of freedom for Test 4 are less than or egual to 0. The Chi-Sguare
test for fit is not valid

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	0.0995543

BMDL = 1.22818e-009

This document is a draft for review purposes only and does not constitute Agency policy.

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E.2.21.5. Figure for Additional Model Presented: Hill, Unrestricted

Hill Model with 0.95 Confidence Level

dose

10:53 02/08 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.2.22. Li et al., 1997: FSH

E.2.22.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential (M2)

8

<0.0001

1095.292

5.222E+02

4.121E+02



exponential (M3)

8

<0.0001

1095.292

5.222E+02

4.121E+02

power hit bound (d = 1)

exponential (M4)

7

<0.0001

1059.480

3.432E+01

9.930E+00



exponential (M5)

6

<0.0001

1066.195

1.019E+02

8.583E-01



Hill

7

<0.0001

1056.459

5.423E+00

error

n lower bound hit (n = 1)

linear

8

<0.0001

1077.695

2.003E+02

1.357E+02



polynomial, 8-
degree

9

<0.0001

1155.670

error

1.916E+02



power b

8

<0.0001

1077.695

2.003E+02

1.357E+02

power bound hit (power =

1)

Hill, unrestricted

6

0.001

1039.481

2.204E-01

error

unrestricted (n = 0.32)

power,
unrestricted0

7

0.002

1037.474

1.963E-01

2.484E-02

unrestricted (power = 0.305)

a Non-constant variance model selected (p = <0.0001)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.2.22.2. Output for Selected Model: Power

Li et al., 1997: FSH

Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\l\Blood\72_Li_l997_FSH_Pwr_l.(d)

Gnuplot Plotting File: C:\l\Blood\72_Li_1997_FSH_Pwr_l.plt

Mon Feb 08~13:36:35 2010

Figure 3: FSH in female S-D rats 24hr after dosing, 22 day old rats

The form of the response function is:

Y[dose] = control + slope * doseApower

Dependent variable = Mean
Independent variable = Dose

The power is restricted to be greater than or egual to 1

This document is a draft for review purposes only and does not constitute Agency policy.

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The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)

Total number of dose groups = 10

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

lalpha
rho
control
slope
power

9.8191

0

22.1591
52 .284
0.294106

Asymptotic Correlation Matrix of Parameter Estimates

lalpha
rho
control
slope

The model parameter(s) -power

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

lalpha
1

-0. 99
-0.29
-0.033

rho

-0. 99
1

0.2
0. 033

control

-0.29
0.2
1

-0.36

slope

-0.033
0. 033
-0.36
1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
lalpha
rho
control
slope
power

Estimate
3.50054
1. 27087
87 .4348
0. 492306
1

Std. Err.

1. 225
0.241869
12.9347
0.0919718
NA

Lower Conf. Limit
1.09958
0.796814
62.0833
0.312044

Upper Conf. Limit

5.9015
1.74492
112 .786
0. 672567

NA - Indicates that this parameter has hit a bound
implied by some ineguality constraint and thus
has no standard error.

Table of Data and Estimated Values of Interest

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0

10

23. 9

CO
-j

29.6

CO
cxi

-2 . 04

0.266

10

22 . 2

87 . 6

48.5

98 . 7

-2 .1

0.7988

10

85.2

87 . 8

94 . 3

98 . 9

-0.0832

2 .097

10

73.3

CO
CO

CJ1

48.5

99.4

-0.483

5. 867

10

126

90.3

159

101

1.12

15

10

132

CO
cxi

116

104

1.14

43.33

10

117

109

51. 2

113

0.223

119. 9

10

304

146

154

137

3. 65

386

10

347

277

151

205

1. 07

1172

10

455

664

286

358

i—1

CO
CJ1

This document is a draft for review purposes only and does not constitute Agency policy.

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Model Descriptions for likelihoods calculated

Model A1:	Yij	= Mu(i) + e(iji

Var{e(ij)} = Sigma/'2

Model A2 :	Yij	= Mu(i) + e(ij|

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model
A1

A2
A3

fitted
R

Log(likelihood)

-535.687163
-496.367061
-502.709623
-534.847518
-574.835246

Param's

11

20

12
4
2

AIC
1093.374327
1032.734122
1029.419246
1077.695035
1153.670492

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

Test 3: Are variances adequately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.)

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1

Test 2
Test 3
Test 4

156.936

78 . 6402
12 . 6851
64 . 2758

18
9

<.0001
<.0001
0.1232
<.0001

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is less than .1. You may want to try a different
model

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD = 200.314

This document is a draft for review purposes only and does not constitute Agency policy.

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E'.MDL = 135.673

E.2.22.3. Figure for Selected Model: Power

Power Model with 0.95 Confidence Level

0	200	400	600	800	1000	1200

dose

13:36 02/08 2010

E.2.22.4. Output for Additional Model Presented: Power, Unrestricted
Li et al., 1997: FSH

Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\l\Blood\72_Li_l997_FSH_Pwr_U_l.(d)

Gnuplot Plotting File: C:\l\Blood\72_Li_1997_FSH_Pwr_U_l.plt

Mon Feb 08 13:36:46 2010

Figure 3: FSH in female S-D rats 24hr after dosing, 22 day old rats

The form of the response function is:
Y[dose] = control + slope * doseApower

Dependent variable = Mean

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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Independent variable = Dose
The power is not restricted

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)

Total number of dose groups = 10

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

lalpha
rho
control
slope
power

9.8191

0

22.1591
52 .284
0.294106

Asymptotic Correlation Matrix of Parameter Estimates

lalpha
rho
control
slope
power

lalpha
1

-0. 99
-0.69
-0. 06
0.26

rho

-0. 99
1

0. 65
0. 0089
-0.23

control

-0.69
0. 65
1

-0.23
0. 029

slope

-0. 06
0. 0089
-0.23
1

-0. 85

power

0.26
-0.23
0. 029
-0. 85
1

Parameter Estimates

Variable
lalpha
rho
control
slope
power

Estimate

3.67487
1.17882
15.8201
52.528
0.304867

Std. Err.

1.12134
0.221526
6. 87715
9. 46821
0.0336805

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

1.47708
0.744632
2.34113
33.9706
0.238855

5. 87265
1. 613

29.299
71. 0853
0.37088

Table of Data and Estimated Values of Interest

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0

0.266
0.7988
2 .097
5. 867
15
43.33
119. 9
386
1172

10
10

10
10
10
10
10
10
10
10

23. 9

22 . 2

85.2
73.3
126
132
117
304
347
455

15. 8

50. 9

64 . 9
81. 7
106
136
182
242
339
469

29.6
48.5

94 . 3
48.5
159
116
51. 2
154
151
286

32
63.7

73.5
84 .1
98 .1
114
135
160
195
236

0.795
-1.43
0. 876
-0.314
0. 652
-0.102
-1. 52
1.24
0.134
-0.182

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(iji

This document is a draft for review purposes only and does not constitute Agency policy.

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Var{e(ij)} = Sigma^2

Model A2 :	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model	Log(likelihood) # Param's	AIC

A1	-535.687163	11	1093.374327

A2	-496.367061	20	1032.734122

A3	-502.709623	12	1029.419246

fitted	-513.737215	5	1037.474431

R	-574.835246	2	1153.670492

Test

1

Test

2

Test

3

Test

4

Explanation of Tests

(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.)

Tests of Interest

Test -2*log(Likelihood Ratio) Test df	p-value

Test 1	156.936	18	<.0001

Test 2	78.6402	9	<.0001

Test 3	12.6851	8	0.1232

Test 4	22.0552	7	0.002485

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is less than .1. You may want to try a different
model

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD = 0.196278

BMDL = 0.0248364

This document is a draft for review purposes only and does not constitute Agency policy.

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E.2.22.5. Figure for Additional Model Presented: Power, Unrestricted

Power Model with 0.95 Confidence Level

dose

13:36 02/08 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.2.23. Li et al., 2006: Estradiol, 3-Day

E.2.23.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

X2 P-
Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential (M2)

2

0.156

269.027

1.416E+01

5.544E+00



exponential (M3)

2

0.156

269.027

1.416E+01

5.544E+00

power hit bound (d = 1)

exponential (M4)

1

0.341

268.212

error

error



exponential (M5)

0

N/A

270.212

error

error



Hill

0

N/A

270.212

error

error



linear b

2

0.162

268.952

1.606E+01

5.379E+00



polynomial, 3-
degree

2

0.162

268.952

1.606E+01

5.379E+00



power

2

0.162

268.952

1.606E+01

5.379E+00

power bound hit (power =1)

Hill, unrestricted

0

N/A

270.265

9.273E+12

9.273E+12

unrestricted (n = 0.03)

power,
unrestricted

1

0.328

268.265

9.455E+10

error

unrestricted (power = 0.015)

a Constant variance model selected (p = 0.4372)
b Best-fitting model, BMDS output presented in this appendix

E.2.23.2. Output for Selected Model: Linear

Li et al., 2006: Estradiol, 3-Day

Polynomial Model. (Version: 2.13; Date: 04/08/2008)

Input Data File: C:\l\Blood\31_Li_2006_Estra_LinearCV_l.(d)

Gnuplot Plotting File: C:\l\Blood\31_Li_2006_Estra_LinearCV_l.plt

Mon Feb 08 10:54:00 2010

Figure 3, 3-day estradiol

The form of the response function is:

Y[dose] = beta_0 + beta_l*dose + beta_2*dose/'2 + ...

Dependent variable = Mean
Independent variable = Dose
rho is set to 0

Signs of the polynomial coefficients are not restricted
A constant variance model is fit

This document is a draft for review purposes only and does not constitute Agency policy.

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Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
alpha =	267 . 211

rho =	0 Specified

beta_0 =	16.1705

beta 1 =	1.0106

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -rho

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha	beta 0	beta 1

alpha 1	2.le-012	5e-014

beta_0 2.le-012	1	-0.69

beta 1 5e-014	-0.69	1

Parameter Estimates

Variable
alpha
beta_0
beta 1

Estimate
263.435
16.1705
1.0106

95.0% Wald Confidence Interval
Std. Err.	Lower Conf. Limit Upper Conf. Limit

58.9057	147.981	378.888

3.55949	9.19407	23.147

1.2148	-1.37037	3.39156

Table of Data and Estimated Values of Interest

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0	10	10.2	16.2	12.2	16.2	-1.17

0.1588 10 19.9	16.3 20 16.2	0.697

2.839	10	24.7	19	14.6	16.2	1.11

5.124	10	18.1	21.3	17.6	16.2	-0.635

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

This document is a draft for review purposes only and does not constitute Agency policy.

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Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1	-129.653527	5	269.307054

A2	-128.294657	8	272.589314

A3	-129.653527	5	269.307054

fitted	-131.476097	3	268.952193

R	-131.819169	2	267.638338

Explanation of Tests

Test

1

Test

2

Test

3

Test

4

Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adequately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.

Test

Tests of Interest
-2*log(Likelihood Ratio) Test df

p-value

Test 1

Test 2
Test 3
Test 4

7.04902
2 .71774
2 .71774
3.64514

0.3163

0.4372
0.4372
0.1616

The p-value for Test 1 is greater than .05. There may not be a
diffence between responses and/or variances among the dose levels
Modelling the data with a dose/response curve may not be appropriate

The p-value for Test 2 is greater than .1.
model appears to be appropriate here

A homogeneous variance

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adequately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	16.0605

BMDL =	5.37 8 95

This document is a draft for review purposes only and does not constitute Agency policy.

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E.2.23.3. Figure for Selected Model: Linear

Linear Model with 0.95 Confidence Level

dose

10:54 02/08 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.2.24. Li et al., 2006: Progesterone, 3-Day
E.2.24.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential (M2)

2

<0.001

329.928

2.619E+00

error



exponential (M3)

2

0.001

328.101

1.340E-01

error

power hit bound (d = 1)

exponential (M4)

1

0.384

315.734

1.074E-02

6.633E-03



exponential (M5)

0

N/A

317.734

4.301E-02

4.272E-03



Hill b

1

0.386

315.728

9.461E-04

8.006E-11

n lower bound hit (n = 1)

linear

2

<0.001

330.729

3.891E+00

2.626E+00



polynomial, 3-
degree

2

<0.001

330.729

3.891E+00

2.626E+00



power

2

<0.001

330.729

3.891E+00

2.626E+00

power bound hit (power =1)

power,
unrestricted

1

0.404

315.673

2.812E-59

2.812E-59

unrestricted (power = 0.01)

a Non-constant variance model selected (p = 0.0013)
b Best-fitting model, BMDS output presented in this appendix

E.2.24.2. Output for Selected Model: Hill

Li et al., 2006: Progesterone, 3-Day

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\l\Blood\32_Li_2006_Progest_Hill_l.(d)

Gnuplot Plotting File: C:\l\Blood\32_Li_2006_Progest_Hill_l.plt

Wed Feb 10~10:57:14 2 010

Figure 4, 3-day progesterone

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = Mean
Independent variable = Dose

Power parameter restricted to be greater than 1

The variance is to be modeled as Var(i) = exp(lalpha + rho * ln(mean(i)))

Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

This document is a draft for review purposes only and does not constitute Agency policy.

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Relative Function
Parameter

has been set to: le-008
has been set to: le-008

Default Initial Parameter Values

lalpha
rho

intercept

7 . 08699

0

61. 7404
-50.3835
1.47286
0.128302

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -n

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

lalpha
rho

intercept

lalpha
1

-0. 99
-0.093
0. 82
0.22

rho

-0. 99
1

0.12
-0.79
-0.2

intercept

-0.093
0.12
1

-0.43
0. 014

v

0. 82
-0.79
-0.43
1

0. 035

k

0.22
-0.2

0. 014
0. 035
1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
lalpha
rho

intercept

k

Estimate

14.0902
-2 . 27438
61. 7488
-42 .1007
1

0. 00282851

Std. Err.
3.36095
0.861553
3.3373
7 .70852
NA

0.020619

Lower Conf. Limit

7.50284
-3.963
55.2078
-57.2091

-0.037584

Upper Conf. Limit

20.6775
-0.585772
68.2898
-26.9922

0.0432411

NA - Indicates that this parameter has hit a bound
implied by some inequality constraint and thus
has no standard error.

Table of Data and Estimated Values of Interest

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0	10	61.7	61.7	11.1	10.6	-0.00251

0.1588 10	30.6 20.4	40.5 37.2	0.865

2.839	10	16.9	19.7	33.3	38.7	-0.225

5.124	10	11.4	19.7	43.7	38.8	-0.678

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(iji

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij|

This document is a draft for review purposes only and does not constitute Agency policy.

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Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1 -159.632675	5	329.265349

A2 -151.812765	8	319.625529

A3 -152.488175	6	316.976349

fitted -152.863841	5	315.727683

R -165.698875	2	335.397750

Explanation of Tests

Test 1:

Test

2

Test

3

Test

4

Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	27.7722	6	0.0001037

Test 2	15.6398	3	0.001344

Test 3	1.35082	2	0.5089

Test 4	0.751333	1	0.3861

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adeguately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD = 0.000946102
BMDL = 8.00639e-011

This document is a draft for review purposes only and does not constitute Agency policy.

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l E.2.24.3. Figure for Selected Model: Hill

Hill Model with 0.95 Confidence Level

Hill

60

CD
CO
c
o

Q.

CO
CD

a:

c
m

CD

40

20

-20

iVIDL

BMD

10:57 02/10 2010

dose

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.2.25. Markowski et al., 2001: FRIO Run Opportunities
E.2.25.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

r p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential
(M2)b

2

0.304

117.150

8.570E+00

2.887E+00



exponential (M3)

2

0.304

117.150

8.570E+00

2.887E+00

power hit bound (d = 1)

exponential (M4)

1

0.371

117.570

3.452E+00

1.299E-02



exponential (M5)

0

N/A

118.918

2.315E+00

1.391E-02



Hill

0

N/A

118.918

1.801E+00

1.274E-09



linear

2

0.226

117.744

1.106E+01

5.741E+00



polynomial, 3-
degree

2

0.226

117.744

1.106E+01

5.741E+00



power

2

0.226

117.744

1.106E+01

5.741E+00

power bound hit (power = 1)

power,
unrestricted

1

0.239

118.158

5.768E+00

1.032E-14

unrestricted (power = 0.276)

a Constant variance model selected (p = 0,1719)
b Best-fitting model, BMDS output presented in this appendix

E.2.25.2. Output for Selected Model: Exponential (M2)

Markowski et al., 2001: FR10 Run Opportunities

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\l\Blood\33_Mark_2001_FR10opp_ExpCV_l.(d)

Gnuplot Plotting File:

Mon Feb 08 10:55:13 2010

Table 3

The form of the response function by Model:

Model 2
Model 3
Model 4
Model 5

Y[dose]
Y[dose]
Y[dose]
Y[dose]

exp{sign *	b * dose}

exp{sign *	(b * dosej^d}

[c-(c-l) *	exp{-b * dose}]

[c-(c-l) *	exp{-(b * dosej^d}

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;
sign = -1 for decreasing trend.

Model 2 is nested within Models 3 and 4.
Model 3 is nested within Model 5.

Model 4 is nested within Model 5.

This document is a draft for review purposes only and does not constitute Agency policy.

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Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))
rho is set to 0.

A constant variance model is fit.

Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values
Variable	Model 2

Specified

lnalpha	3.5321

rho(S)	0

a	6.77975

b	0.0581937

c	0

d	1

Parameter Estimates
Variable	Model 2

lnalpha	3.63127

rho	0

a	12.2901

b	0.0808832

c	0

d	1

Table of Stats From Input Data

Dose	N	Obs Mean	Obs Std Dev

0	7	13.29	8.65

1.557	4	11.25	5.56

4.03	6	5.75	3.53

10.32	7	7	6.01

Estimated Values of Interest
Dose	Est Mean	Est Std	Scaled Residual

0	12.29	6.145	0.4305

1.557	10.84	6.145	0.1347

4.03	8.871	6.145	-1.244

10.32	5.335	6.145	0.717

Other models for which likelihoods are calculated:

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

This document is a draft for review purposes only and does not constitute Agency policy.

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Model A2 :	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma(i)^2

Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= exp(lalpha + log(mean(i) ) 'k rho)

Model R:	Yij	= Mu + e(i)

Var{e(ij)}	= Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	DF	AIC

A1	-54.38526	5	118.7705

A2	-51.88568	8	119.7714

A3	-54.38526	5	118.7705

R	-57.45429	2	118.9086

2	-55.57522	3	117.1504

Additive constant for all log-likelihoods =	-22.05. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Test

1:

Test

2 :

Test

3:

Test

4 :

Does response and/or variances differ among Dose levels:
Are Variances Homogeneous? (A2 vs. A1)

Are variances adeguately modeled? (A2 vs. A3)

Does Model 2 fit the data? (A3 vs. 2)

(A2 vs. R)

Test

Test 1
Test 2
Test 3
Test 4

Tests of Interest
-2*log(Likelihood Ratio)

11.14

4.999
4.999
2 . 38

p-value

0.08423
0.1719
0.1719
0.3042

The p-value for Test 1 is greater than .05. There may not be a
diffence between responses and/or variances among the dose levels
Modelling the data with a dose/response curve may not be appropriate.

The p-value for Test 2 is greater than .1. A homogeneous
variance model appears to be appropriate here.

The p-value for Test 3 is greater than .1. The modeled
variance appears to be appropriate here.

The p-value for Test 4 is greater than .1. Model 2 seems
to adeguately describe the data.

Benchmark Dose Computations:

Specified Effect = 1.000000

Risk Type = Estimated standard deviations from control
Confidence Level = 0.950000

BMD =	8.56961

BMDL =	2.887 08

This document is a draft for review purposes only and does not constitute Agency policy.

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l E.2.25.3. Figure for Selected Model: Exponential (M2)

Exponential Model 2 with 0.95 Confidence Level

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This document is a draft for review purposes only and does not constitute Agency policy.

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E.2.26. Markowski et al., 2001: FR2 Revolutions

E.2.26.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

r p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential (M2)

2

0.236

217.219

8.486E+00

3.232E+00



exponential (M3)

2

0.236

217.219

8.486E+00

3.232E+00

power hit bound (d = 1)

exponential (M4)

1

0.263

217.583

3.413E+00

1.766E-02



exponential (M5)

0

N/A

218.532

2.415E+00

9.313E-01



Hill b

1

0.654

216.532

1.840E+00

5.992E-01

n upper bound hit (n = 18)

linear

2

0.180

217.764

1.058E+01

5.602E+00



polynomial, 3-
degree

2

0.180

217.764

1.058E+01

5.602E+00



power

2

0.180

217.764

1.058E+01

5.602E+00

power bound hit (power =1)

power,
unrestricted0

1

0.161

218.294

5.739E+00

1.032E-14

unrestricted (power = 0.318)

a Constant variance model selected (p = 0.1092)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.2.26.2. Output for Selected Model: Hill

Markowski et al., 2001: FR2 Revolutions

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\l\Blood\34_Mark_2001_FR2rev_HillCV_l.(d)

Gnuplot Plotting File: C:\l\Blood\34_Mark_2001_FR2rev_HillCV_l.plt

Mon Feb 08 10:55:47 2010

Table 3

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = Mean
Independent variable = Dose
rho is set to 0

Power parameter restricted to be greater than 1
A constant variance model is fit

This document is a draft for review purposes only and does not constitute Agency policy.

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Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

alpha =	2598 . 74

rho =	0 Specified

intercept =	119.29

v =	-62.79

n =	2 .13752

k =	2.53662

Asymptotic Correlation Matrix of Parameter Estimates

alpha
intercept

The model parameter(s) -rho -n

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha
1

1. 2e-008
le-009
3 . 5e-008

intercept
1. 2e-008
1

-0. 81
-0.52

v

le-009
-0. 81
1

0.37

k

3 . 5e-008
-0.52
0.37
1

Parameter Estimates

Variable
alpha
intercept

k

Estimate
2183.85
119.29
-56.5223
18

1.68653

Std. Err.
630.425
17 . 6629
21.9082
NA

0.295154

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

948.245
84 . 6713
-99.4615

1.10804

3419.46

153.909
-13.5831

2 .26502

NA - Indicates that this parameter has hit a bound
implied by some ineguality constraint and thus
has no standard error.

Table of Data and Estimated Values of Interest

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0

1. 557
4 . 03
10.32

119

109
56.5
68 .1

119

108
62 . 8
62 . 8

6 9.9
61
31. 2
33.2

46.7
46.7
46.7
46.7

-2 . 41e-007
2 . 29e-007
-0.329
0.304

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(iji

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij|

This document is a draft for review purposes only and does not constitute Agency policy.

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Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma^2
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1 -104.165520	5	218.331040

A2 -101.140174	8	218.280349

A3 -104.165520	5	218.331040

fitted -104.266162	4	216.532324

R -107.599268	2	219.198536

Explanation of Tests

Test

1

Test

2

Test

3

Test

4

Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

Test 1
Test 2
Test 3
Test 4

-2*log(Likelihood Ratio)

12.9182
6.05069
6.05069
0.201284

Test df

p-value

0.04435
0.1092
0.1092
0.6537

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than .1.
model appears to be appropriate here

A homogeneous variance

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adeguately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	1.83952

BMDL =	0.599228

This document is a draft for review purposes only and does not constitute Agency policy.

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E.2.26.3. Figure for Selected Model: Hill

Hill Model with 0.95 Confidence Level

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E.2.26.4. Output for Additional Model Presented: Power, Unrestricted
Markowski et al., 2001: FR2 Revolutions

Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\l\Blood\34_Mark_2001_FR2rev_PowerCV_U_l.(d)

Gnuplot Plotting File: C:\l\Blood\34_Mark_2001_FR2rev_PowerCV_U_l.plt

Mon Feb 08 10:55:49 2010

Table 3

The form of the response function is:
Y[dose] = control + slope * doseApower

Dependent variable = Mean
Independent variable = Dose
rho is set to 0
The power is not restricted
A constant variance model is fit

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial
alpha =
rho =
control =
slope =
power =

Parameter Values

2598.74

0 Specified
119.29
-10.3599
0. 824761

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -rho

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha	control	slope	power

alpha 1	-3e-010	6.9e-010	9.9e-010

control -3e-010	1	-0.63	-0.28

slope 6.9e-010	-0.63	1	0.87

power 9.9e-010	-0.28	0.87	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

alpha	2350.22	678.449	1020.48	3679.95

control	120.082	18.0782	84.6491	155.514

slope	-27.8164	24.2447	-75.3352	19.7023

power	0.317923	0.350841	-0.369713	1.00556

Table of Data and Estimated Values of Interest
Dose	N Obs Mean	Est Mean Obs Std Dev Est Std Dev Scaled Res.

0	7	119	120	69.9	48.5	-0.0432

1.557	4	109	88.1	61	48.5	0.843

4.03	6	56.5	76.8	31.2	48.5	-1.02

10.32	7	68.1	61.7	33.2	48.5	0.353

Model Descriptions for likelihoods calculated

Model A1:

Yij

Var{e ( ij ;

Mu(i) + e(ij ;
Sigma/N2

Model A2:

Yij

Var{e ( ij ;

Mu(i) + e(ij ;

Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2
Model A3 uses any fixed variance parameters that

This document is a draft for review purposes only and does not constitute Agency policy.

E-146 DRAFT—DO NOT CITE OR QUOTE


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were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1 -104.165520	5	218.331040

A2 -101.140174	8	218.280349

A3 -104.165520	5	218.331040

fitted -105.147159	4	218.294317

R -107.599268	2	219.198536

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Test

2

Test

3

Test

4

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	12.9182	6	0.04435

Test 2	6.05069	3	0.1092

Test 3	6.05069	3	0.1092

Test 4	1.96328	1	0.1612

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than .1. A homogeneous variance
model appears to be appropriate here

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adeguately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD = 5.73906

BMDL = 1.03181e-014

This document is a draft for review purposes only and does not constitute Agency policy.

E-147 DRAFT—DO NOT CITE OR QUOTE


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E.2.26.5. Figure for Additional Model Presented: Power, Unrestricted

Power Model with 0.95 Confidence Level

dose

10:55 02/08 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.2.27. Markowski et al., 2001: FR5 Run Opportunities
E.2.27.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

r p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential (M2)

2

0.205

133.193

5.078E+00

2.439E+00



exponential (M3)

2

0.205

133.193

5.078E+00

2.439E+00

power hit bound (d = 1)

exponential (M4)

1

0.254

133.328

2.160E+00

6.854E-01



exponential (M5)

0

N/A

134.032

2.124E+00

9.667E-01



Hill b

1

0.939

132.032

1.723E+00

9.085E-01

n upper bound hit (n = 18)

linear

2

0.122

134.229

7.234E+00

4.430E+00



polynomial, 3-
degree

2

0.122

134.229

7.234E+00

4.430E+00



power

2

0.122

134.229

7.234E+00

4.430E+00

power bound hit (power =1)

power,
unrestricted0

1

0.134

134.268

2.666E+00

1.032E-14

unrestricted (power = 0.392)

a Constant variance model selected (p = 0.2262)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.2.27.2. Output for Selected Model: Hill

Markowski et al., 2001: FR5 Run Opportunities

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\l\Blood\35_Mark_2001_FR5opp_HillCV_l.(d)

Gnuplot Plotting File: C:\l\Blood\35_Mark_2001_FR5opp_HillCV_l.plt

Mon Feb 08 10:56:24 2010

Table 3

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = Mean
Independent variable = Dose
rho is set to 0

Power parameter restricted to be greater than 1
A constant variance model is fit

This document is a draft for review purposes only and does not constitute Agency policy.

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Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

alpha =	77.4849

rho =	0 Specified

intercept =	26.14

v =	-13.34

n =	2.77257

k =	2 .48811

Asymptotic Correlation Matrix of Parameter Estimates

alpha
intercept

The model parameter(s) -rho -n

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha
1

-3.2e-009
1. 9e-008
6 . 2e-008

intercept
-3.2e-009
1

-0. 81
-0.51

v

1.9e-008
-0. 81
1

0.36

k

. 2e-008
-0.51
0.36
1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
alpha
intercept

k

Estimate

64 . 5863
26.14
-13.1569
18

1.68073

Std. Err.

18 . 6445
3.03753
3.7676
NA

0.208677

Lower Conf. Limit

28.0438
20.1865
-20.5413

1. 27173

Upper Conf. Limit

101.129
32 .0935
-5.77257

2 . 08973

NA - Indicates that this parameter has hit a bound
implied by some ineguality constraint and thus
has no standard error.

Table of Data and Estimated Values of Interest

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0	7	26.1	26.1	12.3	8.04	-1.9e-008

1.557	4	23.5	23.5	7.04	8.04	-1.94e-007

4.03	6	12.8	13	6.17	8.04	-0.0558

10.32	7	13.1	13	7.14	8.04	0.0517

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(iji

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij|

This document is a draft for review purposes only and does not constitute Agency policy.

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Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma^2
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1 -62.013133	5	134.026266

A2 -59.839035	8	135.678070

A3 -62.013133	5	134.026266

fitted -62.016025	4	132.032049

R -67.530040	2	139.060081

Explanation of Tests

Test

1

Test

2

Test

3

Test

4

Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio)

Test df

p-value

Test 1
Test 2
Test 3
Test 4

15.382
4.3482
4.3482
0.00578335

0.01748
0.2262
0.2262
0.9394

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than .1.
model appears to be appropriate here

A homogeneous variance

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adeguately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	1.72335

BMDL =	0.9084 91

This document is a draft for review purposes only and does not constitute Agency policy.

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E.2.27.4. Output for Additional Model Presented: Power, Unrestricted
Markowski et al., 2001: FR5 Run Opportunities

Hill Model with 0.95 Confidence Level

1 1 1—'—'—I—'—'—'—'—'—1 1 1 1 I	

0

2010

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Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\l\Blood\35_Mark_2001_FR5opp_PwrCV_U_l.(d)

Gnuplot Plotting File: C:\l\Blood\35_Mark_2 001_FR5opp_PwrCV_U_l.plt

Mon Feb 08 10:56:24 2010

Table 3

The form of the response function is:
Y[dose] = control + slope * doseApower

Dependent variable = Mean
Independent variable = Dose
rho is set to 0
The power is not restricted
A constant variance model is fit

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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61

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63

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70

Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

alpha
rho
control
slope
power

77.4849

0 Specified
26.14
-2.3827
0.844532

Asymptotic Correlation Matrix of Parameter Estimates

alpha
control

The model parameter(s) -rho

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha
1

-9.3e-009

control
-9.3e-009
1

slope
1. 4e-008
-0. 64

power
9.3e-009
-0.34

slope	1.4e-008	-0.64	1	0.9

power	9.3e-009	-0.34	0.9	1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
alpha
control
slope
power

Estimate

70.8926
26.3582
-5.73309
0.391903

Std. Err.

20.4649
3.12902
4.02937
0.281862

Lower Conf. Limit
30.7821
20.2254
-13.6305
-0.160536

Upper Conf. Limit

111.003
32.4909
2.16433
0.944342

Table of Data and Estimated Values of Interest

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0	7	26.1	26.4	12.3	8.42	-0.0686

1.557	4	23.5	19.5	7.04	8.42	0.941

4.03	6	12.8	16.5	6.17	8.42	-1.06

10.32	7	13.1	12	7.14	8.42	0.343

Model Descriptions for likelihoods calculated

Model A1:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma/'2

Model A2:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma(i)^2

Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma/'2
Model A3 uses any fixed variance parameters that

This document is a draft for review purposes only and does not constitute Agency policy.

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were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1 -62.013133	5	134.026266

A2 -59.839035	8	135.678070

A3 -62.013133	5	134.026266

fitted -63.134001	4	134.268002

R -67.530040	2	139.060081

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Test

2

Test

3

Test

4

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	15.382	6	0.01748

Test 2	4.3482	3	0.2262

Test 3	4.3482	3	0.2262

Test 4	2.24174	1	0.1343

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than .1. A homogeneous variance
model appears to be appropriate here

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adeguately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD = 2.66625

BMDL = 1.03181e-014

This document is a draft for review purposes only and does not constitute Agency policy.

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E.2.27.5. Figure for Additional Model Presented: Power, Unrestricted

Power Model with 0.95 Confidence Level

dose

10:56 02/08 2010

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E.2.28. Miettinen et al., 2006: Cariogenic Lesions, Pups
E.2.28.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

gamma

3

0.410

162.280

3.401E+00

1.889E+00

power bound hit (power = 1)

logistic

3

0.371

162.518

4.108E+00

2.450E+00



log-logistica

3

0.602

161.292

1.428E+00

5.175E-01

slope bound hit (slope = 1)

log-probit

3

0.300

163.040

6.321E+00

3.127E+00

slope bound hit (slope =1)

multistage, 4-
degree

3

0.410

162.280

3.401E+00

1.889E+00

final B = 0

probit

3

0.350

162.656

4.548E+00

2.889E+00



Weibull

3

0.410

162.280

3.401E+00

1.889E+00

power bound hit (power = 1)

gamma,
unrestricted

2

0.798

161.801

3.374E-03

8.884E-
242

unrestricted (power = 0.215)

log-logistic,
unrestricted b

2

0.728

161.983

4.942E-02

error

unrestricted (slope = 0.465)

log-probit,
unrestricted

2

0.732

161.972

6.495E-02

error

unrestricted (slope = 0.289)

Weibull,
unrestricted

2

0.766

161.884

1.792E-02

error

unrestricted (power = 0.324)

a Best-fitting model, BMDS output presented in this appendix
b Alternate model, BMDS output also presented in this appendix

E.2.28.2. Output for Selected Model: Log-Logistic

Miettinen et al., 2006: Cariogenic Lesions, Pups

Logistic Model. (Version: 2.12; Date: 05/16/2008)

Input Data File: C:\l\Blood\36_Miet_2006_Cariogenic_LogLogistic_l.(d)

Gnuplot Plotting File: C:\l\Blood\36_Miet_2006_Cariogenic_LogLogistic_l.plt

Mon Feb 08 10:56:59 2010

Table 2 converting the percentage into the number of animals, and control is Control II from the
study. Dose is in ng per kg and is from Table 1

The form of the probability function is:

P[response] = background+(1-background)/[1+EXP(-intercept-slope*Log(dose))]

Dependent variable = DichEff

This document is a draft for review purposes only and does not constitute Agency policy.

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Independent variable = Dose

Slope parameter is restricted as slope >= 1
Total number of observations = 5

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

User has chosen the log transformed model

Default Initial Parameter Values

background =	0.595238

intercept =	-2.494

slope =	1

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -slope

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

background intercept

background	1	-0.66

intercept	-0.66	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

background	0.644165	*	*	*

intercept	-2.55354	*	*	*

slope	1	*	*	*

Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-77.6769	5

Fitted model -78.646 2	1.93832 3	0.5853

Reduced model -83.2067 1	11.0597 4	0.0259

AIC:	161.292

Goodness of Fit

Scaled

Dose	Est. Prob. Expected Observed	Size	Residual

0.0000

0

6442

27.055

25.000

42

-0

662

2.2195

0

6 9 6 6

20.200

23.000

29

1

131

6.2259

0

7603

19.007

19.000

25

-0

003

16.0142

0

8416

20.198

20.000

24

-0

111

46.6355

0

9231

29.540

29.000

32

-0

358

H-

K>

II

1—1

CO



d.f.

= 3 P

-value = 0.6024







Benchmark Dose Computation

This document is a draft for review purposes only and does not constitute Agency policy.

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Specified effect =
Risk Type	=

Confidence level =

0.1
Extra risk
0. 95

BMD =	1. 42805

BMDL =	0.517 4 95

E.2.28.3. Figure for Selected Model: Log-Logistic

Log-Logistic Model with 0.95 Confidence Level

dose

10:56 02/08 2010

E.2.28.4. Output for Additional Model Presented: Log-Logistic, Unrestricted
Miettinen et al., 2006: Cariogenic Lesions, Pups

Logistic Model. (Version: 2.12; Date: 05/16/2008)

Input Data File: C:\l\Blood\36_Miet_2006_Cariogenic_LogLogistic_U_l.(d)

Gnuplot Plotting File: C:\l\Blood\36_Miet_2006_Cariogenic_LogLogistic_U_l.plt

Mon Feb 08 10:56:59 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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Table 2 converting the percentage into the number of animals, and control is Control II from the
study. Dose is in ng per kg and is from Table 1

The form of the probability function is:

P[response] = background+(1-background)/[1+EXP(-intercept-slope*Log(dose))]

Dependent variable = DichEff
Independent variable = Dose
Slope parameter is not restricted

Total number of observations = 5

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

User has chosen the log transformed model

Default Initial Parameter Values

background =	0.595238

intercept = -0.739403
slope =	0.442847

Asymptotic Correlation Matrix of Parameter Estimates
background intercept	slope

background	1	-0.51	0.24

intercept	-0.51	1	-0.89

slope	0.24	-0.89	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

background	0.597745	*	*	*

intercept	-0.798024	*	*	*

slope	0.465259	*	*	*

Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-77.6769	5

Fitted model -77.9915 3	0.629204 2	0.7301

Reduced model -83.2067 1	11.0597 4	0.0259

AIC:	161.983

Goodness of Fit

Scaled

Dose	Est. Prob. Expected Observed	Size	Residual

0.0000	0.5977	25.105 25.000	42	-0.033

2.2195	0.7566	21.940 23.000	29	0.458

This document is a draft for review purposes only and does not constitute Agency policy.

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6.2259	0.8042

16.0142	0.8474

4 6.6355	0.8 910

20.105 19.000
20.338 20.000
28.512 29.000

Chi' '2 = 0.63

d . f . = 2

P-value = 0.7281

25
24
32

-0.557
-0.192
0.277

E'.enchmark Dose Computation
Specified effect =	0 .1

Risk Typ'e	=	E::tra risk

Cc'nfidence level =	0.95

BMD =	0.04 94 22

E'.enchmark duse cO'mp'UtatiO'ri failed. Lower limit includes :eru.

E.2.28.5. Figure for Additional Model Presented: Log-Logistic, Unrestricted

Log-Logistic Model

"O

(D

-t—<

o

CD
!t=
<

0.9

0.7

0.6

0.5

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10:57 02/08 2010

10

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dose

40

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E.2.29. Murray et al., 1979: Fertility in F2 Generation
E.2.29.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

X2 P-
Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

gamma

0

N/A

61.729

4.481E+00

1.590E+00



logistic

1

0.051

61.318

2.420E+00

1.722E+00

negative intercept (intercept =
-2.567)

log-logistic

0

N/A

61.729

4.971E+00

1.565E+00



multistage, 1-
degree

1

0.031

63.154

1.598E+00

8.747E-01



multistage, 2-
degreea

1

0.079

60.464

2.733E+00

1.366E+00



probit

1

0.048

61.544

2.250E+00

1.590E+00

negative intercept (intercept =
-1.459)

Weibull

0

N/A

61.729

5.042E+00

1.604E+00



log-probit,
unrestricted

0

N/A

61.729

4.244E+00

1.506E+00

unrestricted (slope = 3.182)

a Best-fitting model, BMDS output presented in this appendix

E.2.29.2. Output for Selected Model: Multistage, 2-Degree

Murray et al., 1979: Fertility in F2 Generation

Multistage Model. (Version: 3.0; Date: 05/16/2008)

Input Data File: C:\l\Blood\Murray_l979_fert_index_f2_Multi2_l.(d)

Gnuplot Plotting File: C:\l\Blood\Murray_197 9_fert_index_f2_Multi2_l.plt

Wed_Feb 10 16:06:28 2010~

Table 1 but expressed as number of dams who do not produce offspring

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal*dose/Nl-beta2*dose/N2 ) ]

The parameter betas are restricted to be positive

Dependent variable = DichEff
Independent variable = Dose

Total number of observations = 3

Total number of records with missing values = 0
Total number of parameters in model = 3
Total number of specified parameters = 0
Degree of polynomial = 2

This document is a draft for review purposes only and does not constitute Agency policy.

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Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background = 0.0567204
Beta(1) =	0

Beta(2) = 0.0155037

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -Beta(l)

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Background
Beta(2)

Background
1

-0.45

Beta(2)

-0.45
1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0.0780188	*	*	*

Beta(1)	0	*	*	*

Beta(2)	0.0141051	*	*	*

* - Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-25.8194	3

Fitted model -28.2318 2	4.82474 1	0.02805

Reduced model -34.0009 1	16.363 2	0.0002798

AIC:	60.4 636

Goodness of Fit

Scaled

Est. Prob. Expected Observed	Size	Residual

0.0000

0.0780

2.497

4 . 000

32

0. 991

1.1242

0.0943

1.886

0. 000

20

-1.443

5.8831

0.4341

8 . 683

9. 000

20

0.143

Chi ^2 = 3.08	d.f. = 1	P-value = 0.0790

Benchmark Dose Computation
Specified effect =	0.1

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	2.73307

This document is a draft for review purposes only and does not constitute Agency policy.

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E'.MDL =

1.36619

E'.MDU =	4.10938

Taken together, (1.36619, 4.10938) is a 90	% two-sided confidence

interval for the EMD

E.2.29.3. Figure for Selected Model: Multistage, 2-Degree

Multistage Model with 0.95 Confidence Level

dose

16:06 02/10 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.2.30. National Toxicology Program, 1982: Toxic Hepatitis, Male Mice
E.2.30.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

gamma

1

0.027

113.103

3.823E+00

2.005E+00



logistic

2

0.092

110.352

3.108E+00

2.465E+00

negative intercept (intercept =
-3.388)

log-logistic

1

0.026

113.089

3.797E+00

2.141E+00



log-probit

1

0.027

113.111

3.565E+00

2.294E+00



multistage, 3-
degreea

1

0.036

112.045

2.782E+00

1.343E+00



probit

2

0.082

110.512

2.763E+00

2.241E+00

negative intercept (intercept =
-1.894)

Weibull

1

0.025

113.044

3.967E+00

1.704E+00



a Best-fitting model, BMDS output presented in this appendix

E.2.30.2. Output for Selected Model: Multistage, 3-Degree

National Toxicology Program, 1982: Toxic Hepatitis, Male Mice

pit
2010

0

Multistage Model. (Version: 3.0; Date: 05/16/2008)

Input Data File: C:\l\Blood\37_NTP_1982_ToxHep_Multi3_l.(d)

Gnuplot Plotting File: C:\l\Blood\37_NTP_1982_ToxHep_Multi3_l.

Mon Feb 08 10:57:32

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(

-betal*dose/Nl-beta2*dose/N2-beta3*dose/N3) ]

The parameter betas are restricted to be positive

Dependent variable = DichEff
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 4
Total number of specified parameters = 0
Degree of polynomial = 3

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008

This document is a draft for review purposes only and does not constitute Agency policy.

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Parameter

has been set to: le-008

Default Initial
Background =
Beta(1) =
Beta(2) =
Beta(3) =

Parameter Values

0.0471757
0.00749116
0

0.00139828

Asymptotic Correlation Matrix of Parameter Estimates

Background
Beta (1)
Beta(3)

The model parameter(s) -Beta(2)

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Background
1

-0.77
0.69

Beta(1)

-0.77
1

-0. 95

Beta(3)

0.69
-0. 95
1

Parameter Estimates

Variable
Background
Beta(1)
Beta(2)
Beta(3)

Estimate

0. 0267933
0. 0283198
0

0.0012342

Std. Err.

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

Indicates that this value is not calculated.

Analysis of Deviance Table

Model
Full model
Fitted model
Reduced model

Log(likelihood)

-51.0633
-53.0224
-121.743

Param's

4
3
1

Deviance Test d.f.

3.91812
141.358

P-value

0.04777
<.0001

AIC:

112 . 045

Dose

Goodness of Fit

Est. Prob.

Expected

Observed

Scaled
Residual

0.0000
0.7665
2.2711
11.2437

0268
0482
1005
8775

1. 956

2 . 363
4 . 925
43.877

1. 000
5. 000
3. 000
44.000

73

49

49

50

-0.693
1.759
-0.915
0. 053

Chi ^2

4 .41

d.f.

P-value

0.0357

Benchmark Dose Computation
Specified effect =	0.1

Risk Type	=	Extra risk

Confidence level =	0.95

This document is a draft for review purposes only and does not constitute Agency policy.

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BMD =

2 .78201

EMDL =	1.34 308

BMDLJ =	4.5214

Taken together, (1.34308,	4.5214 )
interval for the EMD

is a 90	% two'-sided confidenoe

E.2.30.3. Figure for Selected Model: Multistage, 3-Degree

Multistage Model with 0.95 Confidence Level

dose

10:57 02/08 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-166 DRAFT—DO NOT CITE OR QUOTE


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E.2.31. National Toxicology Program, 2006: Alveolar Metaplasia
E.2.31.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

r p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

gamma

4

0.010

320.093

9.886E-01

8.393E-01

power bound hit (power =1)

logistic

4

<0.001

343.283

2.389E+00

2.052E+00

negative intercept (intercept =
-1.059)

log-logistica

3

0.723

312.558

6.497E-01

3.751E-01



log-probit

4

0.024

318.680

1.566E+00

1.318E+00

slope bound hit (slope =1)

multistage, 5-
degree

4

0.010

320.093

9.886E-01

8.393E-01

final B = 0

probit

4

<0.001

347.071

2.542E+00

2.219E+00

negative intercept (intercept =
-0.599)

Weibull

4

0.010

320.093

9.886E-01

8.393E-01

power bound hit (power =1)

gamma,
unrestricted

3

0.426

314.011

1.642E-01

1.874E-02

unrestricted (power = 0.503)

log-probit,
unrestricted

3

0.696

312.677

6.818E-01

2.740E-01

unrestricted (slope = 0.677)

Weibull,
unrestricted

3

0.522

313.492

2.644E-01

6.947E-02

unrestricted (power = 0.661)

a Best-fitting model, BMDS output presented in this appendix

E.2.31.2. Output for Selected Model: Log-Logistic

National Toxicology Program, 2006: Alveolar Metaplasia

Logistic Model. (Version: 2.12; Date: 05/16/2008)

Input Data File: C:\l\Blood\40_NTP_2006_AlvMeta_LogLogistic_l.(d)

Gnuplot Plotting File: C:\l\Blood\4 0_NTP_2006_AlvMeta_LogLogistic_l.plt

Mon Feb 08 10:58:58 2010

The form of the probability function is:

P[response] = background+(1-background)/[1+EXP(-intercept-slope*Log(dose))]

Dependent variable = DichEff
Independent variable = Dose

Slope parameter is restricted as slope >= 1
Total number of observations = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

This document is a draft for review purposes only and does not constitute Agency policy.

E-167 DRAFT—DO NOT CITE OR QUOTE


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Relative Function Convergence has been set to: le-006
Parameter Convergence has been set to: le-008

User has chosen the log transformed model

Default Initial Parameter Values

background = 0.0377358
intercept =	-1.69494

slope =	1.12282

Asymptotic Correlation Matrix of Parameter Estimates
background intercept	slope

background	1	-0.21	0.1

intercept	-0.21	1	-0.93

slope	0.1	-0.93	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

background	0.0373462	*	*	*

intercept	-1.70923	*	*	*

slope	1.13164	*	*	*

* - Indicates that this value is not calculated.

Analysis of Deviance Table

Model	Log(likelihood)	# Param's	Deviance	Test d.f.	P-value

Full model	-152.615	6

Fitted model	-153.279	3	1.32728	3	0.7227

Reduced model	-216.802	1	128.374	5	<.0001

AIC:	312.558

Goodness of Fit

Scaled

Dose

Est

. Prob.

Expected

Observed

Size

Residual

0.0000

0.

0373

1. 979

2 . 000

53

0

015

2.5565

0.

3682

19.881

19.000

54

-0

249

5.6937

0.

5807

30.776

33.000

53

0

619

9.7882

0.

7162

37 .243

35.000

52

-0

690

16.5688

0.

8197

43.446

45.000

53

0

555

29.6953

0.

8976

46.674

46.000

52

-0

308

Chi ^2

1. 33

d.f.

P-value

0.7232

Benchmark Dose Computation
Specified effect =	0.1

Risk Type	=	Extra risk

Confidence level =	0.95

This document is a draft for review purposes only and does not constitute Agency policy.

E-168 DRAFT—DO NOT CITE OR QUOTE


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BMD =	0.64971

BMDL =	0.375051

E.2.31.3. Figure for Selected Model: Log-Logistic

Log-Logistic Model with 0.95 Confidence Level

"O

(D

-t—<

o

CD
!t=
<
c
o
¦+-'
o
m

0.6

0.4

0.2

0 -

10:58 02/08 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-169 DRAFT—DO NOT CITE OR QUOTE


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E.2.32. National Toxicology Program, 2006: Eosinophilic Focus, Liver
E.2.32.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

gamma

3

0.293

331.902

3.573E+00

2.225E+00



logistic

4

0.405

330.400

5.949E+00

5.137E+00

negative intercept (intercept =
-2.043)

log-logistic

3

0.152

333.515

4.139E+00

2.077E+00



log-probit

4

0.192

332.312

4.889E+00

3.980E+00

slope bound hit (slope =1)

multistage, 5-
degree

3

0.752

329.328

3.393E+00

2.466E+00



probita

4

0.459

329.945

5.583E+00

4.864E+00

negative intercept (intercept
= -1.235)

Weibull

3

0.324

331.628

3.770E+00

2.249E+00



log-probit,
unrestricted

3

0.116

334.150

4.146E+00

2.152E+00

unrestricted (slope = 0.895)

a Best-fitting model, BMDS output presented in this appendix

E.2.32.2. Output for Selected Model: Probit

National Toxicology Program, 2006: Eosinophilic Focus, Liver

Probit Model. (Version: 3.1; Date: 05/16/2008)

Input Data File: C:\l\Blood\45_NTP_2006_LivEosFoc_Probit_l.(d)

Gnuplot Plotting File: C:\l\Blood\45_NTP_2006_LivEosFoc_Probit_l.plt

Mon Feb 08 11:00:54 2010

The form of the probability function is:

P[response] = CumNorm(Intercept + Slope* Dose),

where CumNorm(.) is the cumulative normal distribution function

Dependent variable = DichEff
Independent variable = Dose
Slope parameter is not restricted

Total number of observations = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

This document is a draft for review purposes only and does not constitute Agency policy.

E-170 DRAFT—DO NOT CITE OR QUOTE


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Default Initial	(and Specified) Parameter Values

background =	0 Specified

intercept =	-1.28017

slope =	0.0712441

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -background

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

intercept	slope

intercept	1	-0.77

slope	-0.77	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

intercept	-1.23453	0.125132	-1.47979	-0.989279

slope	0.0688678	0.00823346	0.0527305	0.085005

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-161.07	6

Fitted model -162.972 2	3.80461 4	0.4331

Reduced model -202.816 1	83.4925 5	<.0001

AIC:	329.945

Goodness of Fit

Scaled

Dose	Est. Prob. Expected Observed	Size	Residual

0.0000

0

1085

5.751

3

000

53

-1

215

2.5565

0

1449

7 . 826

8

000

54

0

067

5.6937

0

1998

10.588

14

000

53

1

172

9.7882

0

2876

15.242

17

000

53

0

533

16.5688

0

4628

24.526

22

000

53

-0

6 9 6

29.6953

0

7912

41.932

42

000

53

0

023

Chi/N2 = 3.62	d.f. = 4	P-value = 0.4593

Benchmark Dose Computation
Specified effect =	0.1

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	5.5830 9

BMDL =	4 . 86394

This document is a draft for review purposes only and does not constitute Agency policy.

E-171 DRAFT—DO NOT CITE OR QUOTE


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l E.2.32.3. Figure for Selected Model: Probit

Probit Model with 0.95 Confidence Level

dose

2	11:00 02/08 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-l 72 DRAFT—DO NOT CITE OR QUOTE


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E.2.33. National Toxicology Program, 2006: Fatty Change Diffuse, Liver
E.2.33.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

gamma

4

0.659

252.348

4.028E+00

2.923E+00



logistic

4

0.056

262.132

5.890E+00

5.042E+00

negative intercept (intercept =
-2.825)

log-logistic

4

0.359

254.413

4.254E+00

3.228E+00



log-probit

4

0.367

254.428

4.204E+00

3.277E+00



multistage, 5-
degree

3

0.581

254.045

3.524E+00

2.234E+00



probit

4

0.075

260.915

5.567E+00

4.784E+00

negative intercept (intercept =
-1.665)

Weibull3

4

0.724

251.989

3.917E+00

2.856E+00



a Best-fitting model, BMDS output presented in this appendix

E.2.33.2. Output for Selected Model: Weibull

National Toxicology Program, 2006: Fatty Change Diffuse, Liver

Weibull Model using Weibull Model (Version: 2.12; Date: 05/16/2008)
Input Data File: C:\l\Blood\47_NTP_2006_LivFatDiff_Weibull_l.(d)

Gnuplot Plotting File: C:\l\Blood\47_NTP_2006_LivFatDiff_Weibull_l.plt

Mon Feb 08 11:01:56 2010

NTP liver fatty change diffuse

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(-slope*doseApower)]

Dependent variable = DichEff
Independent variable = Dose

Power parameter is restricted as power >=1
Total number of observations = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial (and Specified) Parameter Values

Background = 0.00925926
Slope = 0.00721355

This document is a draft for review purposes only and does not constitute Agency policy.

E-173 DRAFT—DO NOT CITE OR QUOTE


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Power =

1.69678

Asymptotic Correlation Matrix of Parameter Estimates

Slope
Power

The model parameter(s) -Background

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Slope
1

-0. 98

Power

-0. 98
1

Parameter Estimates

Variable
Background
Slope
Power

Estimate

0

0.0135075
1. 50444

Std. Err.

NA

0. 00640459
0.168981

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

0.00095478
1.17324

0.0260603
1. 83564

NA - Indicates that this parameter has hit a bound
implied by some inequality constraint and thus
has no standard error.

Analysis of Deviance Table

Model

Log(likelihood) #

Param's Deviance

Test

d

f. P-value

Full

model



- . 992

6







Fitted

model



-123.995

2 2.00444



4

0.7349

Reduced

model



-204.846

1 163.708



5

<.0001



AIC:



251.989















Goodness of Fit





















Scaled

Dose

Est

. Prob

Expected

Observed Si

ze



Residual

0.0000

0.

0000

0. 000

0. 000

53



0. 000

2.5565

0.

0539

2 . 912

2 . 000

54



-0.550

5.6937

0.

1688

8. 949

12.000

53



1.119

9.7882

0.

3415

18 .102

17.000

53



-0.319

16.5688

0.

6024

31.929

30.000

53



-0.542

29.6953

0.

8913

47 . 238

48 . 000

53



0.336

Chi ^2 = 2

. 06

d. f.

= 4 P

-value = 0.7243







Benchmark Dose

Computation









Specified

effect

=

0.1









Risk Type



=

Extra risk









Confidence

level

=

0. 95











BMD

=

3.91723











BMDL



2 . 85566









This document is a draft for review purposes only and does not constitute Agency policy.

E-174 DRAFT—DO NOT CITE OR QUOTE


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l E.2.33.3. Figure for Selected Model: Weibull

Weibull Model with 0.95 Confidence Level

dose

2	11:01 02/08 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-l 75 DRAFT—DO NOT CITE OR QUOTE


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E.2.34. National Toxicology Program, 2006: Gingival Hyperplasia, Squamous, 2 Years
E.2.34.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

gamma

4

0.036

314.985

7.743E+00

5.166E+00

power bound hit (power = 1)

logistic

4

0.016

318.602

1.392E+01

1.056E+01

negative intercept (intercept =
-1.859)

log-logistica

4

0.055

313.351

5.850E+00

3.730E+00

slope bound hit (slope = 1)

log-probit

4

0.005

321.426

1.535E+01

1.038E+01

slope bound hit (slope =1)

multistage, 5-
degree

4

0.036

314.985

7.743E+00

5.166E+00

final B = 0

probit

4

0.018

318.240

1.318E+01

9.924E+00

negative intercept (intercept =
-1.123)

Weibull

4

0.036

314.985

7.743E+00

5.166E+00

power bound hit (power = 1)

gamma,
unrestricted

3

0.633

307.618

5.309E-01

9.859E-07

unrestricted (power = 0.282)

log-logistic,
unrestricted b

3

0.655

307.507

7.049E-01

1.260E-05

unrestricted (slope = 0.374)

log-probit,
unrestricted

3

0.668

307.444

8.357E-01

4.796E-05

unrestricted (slope = 0.22)

Weibull,
unrestricted

3

0.644

307.562

6.143E-01

3.872E-06

unrestricted (power = 0.325)

a Best-fitting model, BMDS output presented in this appendix
b Alternate model, BMDS output also presented in this appendix

E.2.34.2. Output for Selected Model: Log-Logistic

National Toxicology Program, 2006: Gingival Hyperplasia, Squamous, 2 Years

Logistic Model. (Version: 2.12; Date: 05/16/2008)

Input Data File: C:\l\Blood\42_NTP_2006_GingHypSq_LogLogistic_l.(d)

Gnuplot Plotting File: C:\l\Blood\42_NTP_2006_GingHypSq_LogLogistic_l.plt

Mon Feb 08 10:59:57 2010

[insert study notes]

The form of the probability function is:

P[response] = background+(1-background)/[1+EXP(-intercept-slope*Log(dose))]

Dependent variable = DichEff
Independent variable = Dose

This document is a draft for review purposes only and does not constitute Agency policy.

E-176 DRAFT—DO NOT CITE OR QUOTE


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Slope parameter is restricted as slope >= 1
Total number of observations = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

User has chosen the log transformed model

Default Initial Parameter Values

background = 0.0188679
intercept =	-3.75308

slope =	1

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -slope

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

background intercept

background	1	-0.79

intercept	-0.79	1

Parameter Estimates

95.0% Wald Confidence Interval

Variable Estimate Std. Err.	Lower Conf.	Limit Upper Conf. Limit

background 0.0671812 *	*	*

intercept -3.96371 *	*	*

slope 1 *	*	*

Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-149.95	6

Fitted model -154.675 2	9.45085 4	0.05077

Reduced model -162.631 1	25.3627 5	0.0001186

AIC:	313.351

Goodness of Fit

Scaled

Dose	Est. Prob. Expected Observed	Size	Residual

0.0000

0.0672

3.561

1.

000

53

-1. 405

2.5565

0.1104

5. 960

7 .

000

54

0. 452

5.6937

0.1582

8 . 385

14 .

000

53

2 .113

9.7882

0.2134

11.311

13.

000

53

0.566

16.5688

0.2905

15.394

15.

000

53

-0.119

29.6953

0.4036

21.389

16.

000

53

-1.509

i^2 = 9.26

d.f.

= 4 P

-value

= 0.0550





Benchmark Dose Computation

This document is a draft for review purposes only and does not constitute Agency policy.

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Specified effect =	0.1

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	5.85026

BMDL =	3.7 2 96

E.2.34.3. Figure for Selected Model: Log-Logistic

Log-Logistic Model with 0.95 Confidence Level

0	5	10	15	20	25	30

dose

10:59 02/08 2010

E.2.34.4. Output for Additional Model Presented: Log-Logistic, Unrestricted
National Toxicology Program, 2006: Gingival Hyperplasia, Squamous, 2 Years

t i i i i i i i i r

Log-Logistic

BMDL

BMD

Logistic Model. (Version: 2.12; Date: 05/16/2008)

Input Data File: C:\l\Blood\42_NTP_2006_GingHypSq_LogLogistic_U_l.(d)

Gnuplot Plotting File: C:\l\Blood\42_NTP_2006_GingHypSq_LogLogistic_U_l.plt

Mon Feb 08 10:59:57 2010

[insert study notes]

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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The form of the probability function is:

P[response] = background+(1-background)/[1+EXP(-intercept-slope*Log(dose))]

Dependent variable = DichEff
Independent variable = Dose
Slope parameter is not restricted

Total number of observations = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

User has chosen the log transformed model

Default Initial Parameter Values

background = 0.0188679
intercept =	-2.2

slope =	0.424326

Asymptotic Correlation Matrix of	Parameter Estimates

background intercept	slope

background	1	-0.27	0.11

intercept	-0.27	1	-0.93

slope	0.11	-0.93	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

background	0.0185138	*	*	*

intercept	-2.06653	*	*	*

slope	0.373721	*	*	*

Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-149.95	6

Fitted model -150.753 3	1.60697 3	0.657e

Reduced model -162.631 1	25.3627 5	0.000118^

AIC:	307.507

Goodness of Fit

Scaled

Dose Est. Prob. Expected Observed	Size	Residual

0.0000 0.0185 0.981 1.000	53 0.019

2.5565 0.1681 9.078 7.000	54	-0.756

5.6937 0.2101 11.136 14.000	53 0.966

9.7882 0.2433 12.893 13.000	53 0.034

This document is a draft for review purposes only and does not constitute Agency policy.

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16.5688	0.27 92	14.7 95 15.000

29.6953	0.3230	17.117 16.000

53
53

0. 0 63
-0.328

Chi''2 = 1.62	d.f. = 3	P-value = 0.6554

E'.enchmark Dose Computation
Specified effect =	0 .1

Risk Typ'e	=	E::tra risk

Cc'nfidence level =	0.95

BMD =	0.7 04 8 98

EMDL = 1. 2 6 0 3 4 e - 0 0 5

E.2.34.5. Figure for Additional Model Presented: Log-Logistic, Unrestricted

Log-Logistic Model with 0.95 Confidence Level

BMD

15
dose

10:59 02/08 2010

"i i 1 1 1 1 1 1 1 1 i 1 1 1 1 1 1 1 1 1 r

Log-Logistic

777/5 document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.2.35. National Toxicology Program, 2006: Hepatocyte Hypertrophy, 2 Years
E.2.35.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

r p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

gamma

5

0.034

273.875

9.091E-01

7.868E-01

power bound hit (power =1)

logistic

4

<0.001

297.895

2.475E+00

2.122E+00

negative intercept (intercept =
-1.685)

log-logistic

4

0.006

279.210

1.137E+00

6.491E-01



log-probit

5

0.006

277.800

1.530E+00

1.321E+00



multistage, 5-
degreea

4

0.018

275.693

9.272E-01

7.906E-01



probit

4

<0.001

299.731

2.453E+00

2.137E+00

negative intercept (intercept =
-0.985)

Weibull

5

0.034

273.875

9.091E-01

7.868E-01

power bound hit (power =1)

gamma,
unrestricted

4

0.027

275.270

error

error

unrestricted (power = 0.844)

log-probit,
unrestricted

4

0.008

278.360

1.191E+00

7.038E-01

unrestricted (slope = 0.864)

Weibull,
unrestricted

4

0.024

275.439

7.345E-01

3.588E-01

unrestricted (power = 0.92)

a Best-fitting model, BMDS output presented in this appendix

E.2.35.2. Output for Selected Model: Multistage, 5-Degree

National Toxicology Program, 2006: Hepatocyte Hypertrophy, 2 Years

Multistage Model. (Version: 3.0; Date: 05/16/2008)

Input Data File: C:\l\Blood\43_NTP_2006_HepHyper_Multi5_l.(d)

Gnuplot Plotting File: C:\l\Blood\43_NTP_2006_HepHyper_Multi5_l.plt

Mon Feb 08 11:00:25 2010

[insert study notes]

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(

-betal*dose/Nl-beta2*dose/N2-beta3*dose/N3-beta4*dose/N4-beta5*dose/N5) ]

The parameter betas are restricted to be positive

Dependent variable = DichEff
Independent variable = Dose

Total number of observations = 6

This document is a draft for review purposes only and does not constitute Agency policy.

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Total number of records with missing values = 0
Total number of parameters in model = 6
Total number of specified parameters = 0
Degree of polynomial = 5

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background
Beta(1)
Beta(2)
Beta(3)
Beta ( 4 )
Beta(5)

0.112745

0.0950808
0
0
0

4.39515e-008

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -Background -Beta(2)	-Beta(3)	-Beta(4)

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Beta(1)	Beta(5)

Beta(1)	1	-0.5

Beta(5)	-0.5	1

Parameter Estimates

Variable
Background
Beta(1)
Beta(2)
Beta(3)
Beta(4)
Beta(5)

Std. Err.

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

Indicates that this value is not calculated.

Analysis of Deviance Table

Model
Full model
Fitted model
Reduced model

Log(likelihood)

-129.986
-135.847
-219.97

Param's Deviance Test d.f.

P-value

11.7216
179.968

0. 01955
<.0001

AIC:

275.693

Est. Prob.

Goodness of Fit
Expected Observed

Scaled
Residual

0.0000

0

0000

0. 000

0. 000

53

0

000

2.5565

0

2521

13.614

19.000

54

1

688

5.6937

0

4764

25.251

19.000

53

-1

719

9.7882

0

6717

35.599

42.000

53

1

872

16.5688

0

8510

45.106

41.000

53

-1

584

29.6953

0

9769

51. 778

52.000

53

0

203

This document is a draft for review purposes only and does not constitute Agency policy.

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Chi' 2 = 11.86	d.f. = 4	P-value = 0.0184

E'.enchmark Dose Computation

Specified effect	=	0 .1

Risk Typ'e	=	E::tra risk

Cc'nfidence level	=	0.95

BMD	=	0.92721

EMDL	=	0.7 90637

BMDLJ	=	1.14523

Taken together, (0.7 90637, 1.14523) is a 90	% two-sided confidence

interval for the EMD

E.2.35.3. Figure for Selected Model: Multistage, 5-Degree

Multistage Model with 0.95 Confidence Level

dose

11:00 02/08 2010

This document is a draft for review purposes only and does not constitute Agency policy.

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E.2.36. National Toxicology Program, 2006: Necrosis, Liver
E.2.36.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

r p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

gamma

4

0.939

234.400

8.655E+00

6.340E+00

power bound hit (power =1)

logistic

4

0.601

236.742

1.484E+01

1.240E+01

negative intercept (intercept
= -2.818)

log-logistic

4

0.943

234.382

7.928E+00

5.605E+00

slope bound hit (slope =1)

log-probit

4

0.572

236.863

1.333E+01

1.024E+01

slope bound hit (slope =1)

multistage, 5-
degree

4

0.939

234.400

8.655E+00

6.340E+00

final B = 0

probit

4

0.666

236.293

1.393E+01

1.154E+01

negative intercept (intercept
= -1.626)

Weibull

4

0.939

234.400

8.655E+00

6.340E+00

power bound hit (power =1)

gamma,
unrestricted

3

0.883

236.290

7.726E+00

3.453E+00

unrestricted (power = 0.87)

log-logistic,
unrestricted

3

0.860

236.377

7.733E+00

3.536E+00

unrestricted (slope = 0.974)

log-probit,
unrestricteda

3

0.805

236.598

7.501E+00

3.504E+00

unrestricted (slope = 0.517)

Weibull,
unrestricted

3

0.879

236.302

7.763E+00

3.508E+00

unrestricted (power = 0.895)

a Best-fitting model, BMDS output presented in this appendix

E.2.36.2. Output for Selected Model: Log-Probit, Unrestricted

National Toxicology Program, 2006: Necrosis, Liver

Probit Model. (Version: 3.1; Date: 05/16/2008)

Input Data File: C:\l\Blood\50_NTP_2006_LivNec_LogProbit_U_l.(d)

Gnuplot Plotting File: C:\l\Blood\50_NTP_2006_LivNec_LogProbit_U_l.plt

Mon Feb 08 11:29:30 2010

NTP liver necrosis

The form of the probability function is:

P[response] = Background

+ (1-Background) * CumNorm(Intercept + Slope^Log(Dose) ) ,

where CumNorm(.) is the cumulative normal distribution function

Dependent variable = DichEff

This document is a draft for review purposes only and does not constitute Agency policy.

E-l 84 DRAFT—DO NOT CITE OR QUOTE


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Independent variable = Dose
Slope parameter is not restricted

Total number of observations = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

User has chosen the log transformed model

Default Initial	(and Specified) Parameter Values

background =	0.0188679

intercept =	-2.16223

slope =	0.457376

Asymptotic Correlation Matrix of	Parameter Estimates

background intercept	slope
background 1 -0.65 0.55

intercept	-0.65	1	-0.97

slope	0.55	-0.97	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

background	0.0221151	0.0221351	-0.0212689	0.065499

intercept	-2.32352	0.556343	-3.41393	-1.23311

slope	0.517104	0.185064	0.154385	0.879823

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-114.813	6

Fitted model -115.299 3	0.972184 3	0.808

Reduced model -127.98 1	26.3331 5	<.0001

AIC:	236.598

Goodness of Fit

Scaled

Dose	Est. Prob. Expected Observed	Size	Residual

0.0000

0

0221

1.172

1.

000

53

-0.161

2.5565

0

0544

2 . 938

4 .

000

54

0. 637

5.6937

0

0976

5.174

4 .

000

53

-0.543

9.7882

0

1457

7 .720

8 .

000

53

0.109

16.5688

0

2096

11.106

10.

000

53

-0.373

29.6953

0

3002

15.908

17 .

000

53

0.327

i-2 =0.99



d.f.

= 3 P

-value

= 0.8048





Benchmark Dose Computation
Specified effect =	0.1

This document is a draft for review purposes only and does not constitute Agency policy.

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Risk Type
Confidence level
BMD
BMDL

Extra risk
0. 95
7.50077
3.5039

E.2.36.3. Figure for Selected Model: Log-Probit, Unrestricted

LogProbit Model with 0.95 Confidence Level

0.5 —~—

0.4

"O

CD

-t—'

O
CD
!t=
<

0.3

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20

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11:29 02/08 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.2.37. National Toxicology Program, 2006: Oval Cell Hyperplasia
E.2.37.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

gamma

3

0.074

199.468

6.739E+00

5.074E+00



logistic

4

0.171

196.803

6.064E+00

5.145E+00

negative intercept (intercept =
-3.834)

log-logistic

3

0.042

201.659

6.936E+00

5.604E+00



log-probit

3

0.072

200.121

7.090E+00

5.931E+00



multistage, 5-
degree

3

0.207

195.962

4.785E+00

3.105E+00



probita

4

0.227

195.448

5.673E+00

4.793E+00

negative intercept (intercept
= -2.19)

Weibullb

3

0.077

198.375

5.718E+00

4.088E+00



a Best-fitting model, BMDS output presented in this appendix
b Alternate model, BMDS output also presented in this appendix

E.2.37.2. Output for Selected Model: Probit

National Toxicology Program, 2006: Oval Cell Hyperplasia

Probit Model. (Version: 3.1; Date: 05/16/2008)

Input Data File: C:\l\Blood\53_NTP_2006_OvalHyper_Probit_l.(d)

Gnuplot Plotting File: C:\l\Blood\53_NTP_2006_OvalHyper_Probit_l.plt

Mon_Feb 08 13725:23 2010

The form of the probability function is:

P[response] = CumNorm(Intercept + Slope* Dose),

where CumNorm(.) is the cumulative normal distribution function

Dependent variable = DichEff
Independent variable = Dose
Slope parameter is not restricted

Total number of observations = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

This document is a draft for review purposes only and does not constitute Agency policy.

E-l 87 DRAFT—DO NOT CITE OR QUOTE


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Default Initial	(and Specified) Parameter Values

background =	0 Specified

intercept =	-2.29925

slope =	0.169545

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -background

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

intercept
slope

intercept
1

-0. 87

slope

-0. 87
1

Parameter Estimates

Variable
intercept
slope

Estimate
-2 .18988
0.172453

95.0% Wald Confidence Interval
Std. Err.	Lower Conf. Limit Upper Conf. Limit

0.208021	-2.5976	-1.78217

0.0182446	0.136694	0.208211

Model
Full model
Fitted model
Reduced model

Analysis of Deviance Table

Param's Deviance Test d.f.

Log(likelihood)
-92.4898
-95.7242
-210.191

195.448

6.46873
235.402

P-value

0.1668
C.0001

Goodness of Fit

Scaled

Dose

Est

. Prob.

Expected

Observed

Size

Residual

0.0000

0.

0143

0.756

0

000

53

-0

876

2.5565

0.

0401

2 .168

4

000

54

1

270

5.6937

0.

1135

6. 017

3

000

53

-1

306

9.7882

0.

3079

16.317

20

000

53

1

096

16.5688

0.

7478

39.631

38

000

53

-0

516

29.6953

0.

9983

52 911

53

000

53

0

299

Chi ^2

5. 64

d.f.

P-value

0.2274

Benchmark Dose Computation

Specified effect
Risk Type
Confidence level
BMD
BMDL

0.1
Extra risk

0. 95
5.67298
4.79341

This document is a draft for review purposes only and does not constitute Agency policy.

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E.2.37.3. Figure for Selected Model: Probit

Probit Model with 0.95 Confidence Level

dose

13:25 02/08 2010

E.2.37.4. Output for Additional Model Presented: Weibull
National Toxicology Program, 2006: Oval Cell Hyperplasia

Weibull Model using Weibull Model (Version: 2.12; Date: 05/16/2008)
Input Data File: C:\l\Blood\53_NTP_2006_OvalHyper_Weibull_l.(d)

Gnuplot Plotting File: C:\l\Blood\53_NTP_2 006_OvalHyper_Weibull_l.plt

Mon Feb 08 13:25:23 2010

0

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(-slope*doseApower)]

Dependent variable = DichEff

Independent variable = Dose

Power parameter is restricted as power >=1

Total number of observations = 6

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial	(and Specified) Parameter Values

Background =	0.00925926

Slope =	0.00296825

Power =	2.17092

Asymptotic Correlation Matrix of	Parameter Estimates

Background Slope	Power

Background 1 -0.72	0.7

Slope -0.72 1	-0.99

Power 0.7 -0.99	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0.0164137	0.0221488	-0.0269971	0.0598245

Slope	0.00162074	0.00202897	-0.00235596	0.00559745

Power	2.39427	0.455116	1.50226	3.28628

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-92.4898	6

Fitted model -96.1875 3	7.3953 3	0.06031

Reduced model -210.191 1	235.402 5	<.0001

AIC:	198.375

Goodness of Fit

Scaled

Dose	Est. Prob. Expected Observed	Size	Residual

0.0000

0.0164

0. 870

0

000

53

-0

940

2.5565

0.0314

1.695

4

000

54

1

799

5.6937

0.1138

6. 034

3

000

53

-1

312

9.7882

0.3285

17.411

20

000

53

0

757

16.5688

0.7440

39.431

38

000

53

-0

450

29.6953

0.9957

52 . 774

53

000

53

0

476

Chi/N2 = 6.85	d.f. = 3	P-value = 0.0770

Benchmark Dose Computation
Specified effect =	0.1

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	5.71754

BMDL =	4.08 823

This document is a draft for review purposes only and does not constitute Agency policy.

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l E.2.37.5. Figure for Additional Model Presented: Weibull

Weibull Model with 0.95 Confidence Level

dose

2	13:25 02/08 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.2.38. National Toxicology Program, 2006: Pigmentation, Liver
E.2.38.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

gamma

3

0.552

196.971

2.172E+00

1.493E+00



logistic

4

0.247

197.066

1.853E+00

1.521E+00

negative intercept (intercept =
-2.51)

log-logistic

3

0.984

195.530

2.566E+00

1.937E+00



log-probita

3

0.962

195.526

2.463E+00

1.890E+00



multistage, 5-
degree

3

0.058

199.955

1.822E+00

9.916E-01

final B = 0

probit

4

0.004

200.504

1.710E+00

1.430E+00

negative intercept (intercept =
-1.392)

Weibull

3

0.219

199.007

1.756E+00

1.190E+00



a Best-fitting model, BMDS output presented in this appendix

E.2.38.2. Output for Selected Model: Log-Probit

National Toxicology Program, 2006: Pigmentation, Liver

Probit Model. (Version: 3.1; Date: 05/16/2008)

Input Data File: C:\l\Blood\54_NTP_2006_Pigment_LogProbit_l.(d)

Gnuplot Plotting File: C:\l\Blood\54_NTP_2006_Pigment_LogProbit_l.plt

Mon Feb 08 13:25:55 2010

0

The form of the probability function is:

P[response] = Background

+ (1-Background) * CumNorm(Intercept + Slope^Log(Dose) ) ,

where CumNorm(.) is the cumulative normal distribution function

Dependent variable = DichEff
Independent variable = Dose

Slope parameter is restricted as slope >= 1
Total number of observations = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

This document is a draft for review purposes only and does not constitute Agency policy.

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User has chosen the log transformed model

Default Initial	(and Specified) Parameter Values

background =	0.0754717

intercept =	-2.48683

slope =	1.53221

Asymptotic Correlation Matrix of Parameter Estimates

background
intercept
slope

background
1

-0.42
0.33

intercept

-0.42
1

-0. 96

slope

0.33
-0. 96
1

Parameter Estimates

Variable
background
intercept
slope

Estimate

0.0725473
-2.93268
1. 83184

Std. Err.

0.0338856
0. 487158
0.246868

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

0.00613263
-3.8875
1.34798

0.138962
-1 . 97787
2 . 31569

Model
Full model
Fitted model
Reduced model

Analysis of Deviance Table

Param's Deviance Test d.f.

Log(likelihood)

-94.6177
-94.7632
-210.717

0.291072
232.198

P-value

0.9617
C.0001

195.526

Goodness of Fit

Est. Prob.

Expected

Observed

Scaled
Residual

0.0000 0.

0725

. :

4 .

000

53

0. 082

2.5565 0.

1769

9.553

9.

000

54

-0.197

5.6937 0.

6291

33.342

34 .

000

53

0.187

9.7882 0.

9013

47 .771

48 .

000

53

0.105

16.5688 0.

9874

52.334

52 .

000

53

-0.412

29.6953 0.

9 9 95

52.974

53.

000

53

0.160

Chi ^2 = 0.29

d.f.

= 3 P-

-value

= 0.9624





Benchmark Dose

Computation









Specified effect

=

0.1









Risk Type

=

Extra risk









Confidence level

=

0. 95









BMD

=

2.46293









BMDL



1.88981









This document is a draft for review purposes only and does not constitute Agency policy.

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l E.2.38.3. Figure for Selected Model: Log-Probit

LogProbit Model with 0.95 Confidence Level

dose

2	13:25 02/08 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-194 DRAFT—DO NOT CITE OR QUOTE


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E.2.39. National Toxicology Program, 2006: Toxic Hepatopathy
E.2.39.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

gamma

4

0.754

185.763

4.302E+00

3.463E+00



logistic

4

0.159

191.136

4.833E+00

4.068E+00

negative intercept (intercept =
-3.756)

log-logistic

3

0.391

189.577

4.697E+00

3.818E+00



log-probit

3

0.394

189.580

4.972E+00

3.780E+00



multistage, 5-
degreea

4

0.693

185.924

3.980E+00

3.059E+00

final 15 = 0

probit

4

0.231

189.820

4.621E+00

3.860E+00

negative intercept (intercept =
-2.172)

Weibull

4

0.716

185.785

4.089E+00

3.215E+00



a Best-fitting model, BMDS output presented in this appendix

E.2.39.2. Output for Selected Model: Multistage, 5-Degree

National Toxicology Program, 2006: Toxic Hepatopathy

Multistage Model. (Version: 3.0; Date: 05/16/2008)

Input Data File: C:\l\Blood\55_NTP_2006_ToxHepa_Multi5_l.(d)

Gnuplot Plotting File: C:\l\Blood\55_NTP_2006_ToxHepa_Multi5_l.plt

Mon_Feb 08 13:26:28 2010

0

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(

-betal*dose/Nl-beta2*dose/N2-beta3*dose/N3-beta4*dose/N4-beta5*dose/N5) ]

The parameter betas are restricted to be positive

Dependent variable = DichEff
Independent variable = Dose

Total number of observations = 6

Total number of records with missing values = 0
Total number of parameters in model = 6
Total number of specified parameters = 0
Degree of polynomial = 5

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008

This document is a draft for review purposes only and does not constitute Agency policy.

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Parameter

has been set to: le-008

Default Initial Parameter Values
Background =	0

Beta(1) =	0

Beta(2) =	0

Beta(3) =	0

Beta(4) =	0

Beta(5) = 4.36963e+012

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -Background -Beta(l)	-Beta(4)	-Beta(5)

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Beta(2)	Beta(3)

Beta(2)	1	-0.95

Beta(3)	-0.95	1

Parameter Estimates

Variable
Background
Beta(1)
Beta(2)
Beta(3)
Beta(4)
Beta(5)

Estimate

0
0

0. 00639021
5.5404e-005
0
0

Std. Err.

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

Indicates that this value is not calculated.

Analysis of Deviance Table

Model
Full model
Fitted model
Reduced model

Log(likelihood)

-89.8076
-90.9619
-218.207

Param's Deviance Test d.f.

2.30853
256.799

P-value

0.6792
C.0001

AIC:

185.924

Goodness of Fit

Scaled

Dose

Est

. Prob.

Expected

Observed

Size

Residual

0.0000

0.

0000

0. 000

0

000

53

0

000

2.5565

0.

0420

2 .265

2

000

54

-0

180

5.6937

0.

1969

10.434

8

000

53

-0

841

9.7882

0.

4 901

25.976

30

000

53

1

106

16.5688

0.

8715

46.189

45

000

53

-0

488

29.6953

0.

9994

52 966

53

000

53

0

185

Chi ^2

2 . 23

d.f.

P-value

0.6928

Benchmark Dose Computation
Specified effect =	0.1

This document is a draft for review purposes only and does not constitute Agency policy.

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Risk Type

Extra risk

Confidence level =	0.95

BMD =	3.98025

BMDL =	3.05855

BMDU =	4.897 35

Taken together, (3.05855,	4.89735) is a 90	% two-sided confidence

interval for the BMD

E.2.39.3. Figure for Selected Model: Multistage, 5-Degree

Multistage Model with 0.95 Confidence Level

dose

13:26 02/08 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.2.40. Ohsako et al., 2001: Ano-Genital Length, PND 120
E.2.40.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

r p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential (M2)

3

0.027

171.073

2.592E+01

1.750E+01



exponential (M3)

3

0.027

171.073

2.592E+01

1.750E+01

power hit bound (d = 1)

exponential (M4)

2

0.106

168.392

2.248E+00

8.445E-01



exponential (M5)

1

0.049

169.789

2.193E+00

9.382E-01



Hill b

2

0.154

167.647

2.879E+00

8.028E-01

n lower bound hit (n = 1)

linear

3

0.025

171.258

2.700E+01

1.881E+01



polynomial, 4-
degree

3

0.025

171.258

2.700E+01

1.881E+01



power

3

0.025

171.258

2.700E+01

1.881E+01

power bound hit (power =1)

Hill, unrestricted0

1

0.056

169.555

3.494E+00

3.046E-01

unrestricted (n = 0.591)

power,
unrestricted

2

0.153

167.654

4.151E+00

2.395E-01

unrestricted (power = 0.291)

a Constant variance model selected (p = 0.165)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.2.40.2. Output for Selected Model: Hill

Ohsako et al., 2001: Ano-Genital Length, PND 120

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\l\Blood\56_Ohsako_2001_Anogen_HillCV_l.(d)

Gnuplot Plotting File: C:\l\Blood\56_Ohsako_2001_Anogen_HillCV_l.plt

Mon Feb 08 13727:02 2010

Figure 7

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = Mean
Independent variable = Dose
rho is set to 0

This document is a draft for review purposes only and does not constitute Agency policy.

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Power parameter restricted to be greater than 1
A constant variance model is fit

Total number of dose groups = 5

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

alpha
rho

intercept

7 . 27386

0

28.905
-5.1065
1.57046
2.4317

Specified

Asymptotic Correlation Matrix of Parameter Estimates

alpha
intercept

The model parameter(s) -rho -n

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha
1

4 . 4e-008
-9.8e-008
7.2e-008

intercept
4.4e-008
1

-0.57
-0.52

v

-9.8e-008
-0.57
1

-0.23

k

7 . 2e-008
-0.52
-0.23
1

Parameter Estimates

Variable
alpha
intercept

k

Estimate

7.07394
28.9732
-5.02686
1

2 . 56203

Std

Err.

1. 36138
0.74996
1.05086
NA

2 .11462

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

4.40568

27 . 5034
-7 . 08651

-1. 58255

9.7422
30.4431
-2.9672

6.70661

NA - Indicates that this parameter has hit a bound
implied by some ineguality constraint and thus
has no standard error.

Table of Data and Estimated Values of Interest

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0	12	28.9	29	3.13	2.66	-0.0889

1.04	10	27.9	27.5	2.5	2.66	0.495

3.471	10	25.2	26.1	3.21	2.66	-1.09

11.36	10	26	24.9	2.85	2.66	1.35

38.42	12	23.8	24.3	1.56	2.66	-0.602

Model Descriptions for likelihoods calculated

This document is a draft for review purposes only and does not constitute Agency policy.

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Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2 :	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model
A1

A2
A3

fitted
R

Log(likelihood)

-77 . 952340
-74.703868
-77 . 952340
-7 9.823277
-89.824703

Param's

10

AIC

167.904680
169.407736
167.904680
167.646555
183.649405

Explanation of Tests

Test 1:

Test 2
Test 3
Test 4
(Note:

Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1

Test 2
Test 3
Test 4

30.2417

6 . 4 9 6 9 4
6 . 4 9 6 9 4
3.74187

0. 0001916
0.165
0.165
0.154

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than
model appears to be appropriate here

.1. A homogeneous variance

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adeguately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	2.87863

BMDL =	0.802782

This document is a draft for review purposes only and does not constitute Agency policy.

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E.2.40.3. Figure for Selected Model: Hill

Hill Model with 0.95 Confidence Level

dose

13:27 02/08 2010

E.2.40.4. Output for Additional Model Presented: Hill, Unrestricted
Ohsako et al., 2001: Ano-Genital Length, PND 120

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\l\Blood\56_Ohsako_2001_Anogen_HillCV_U_l.(d)

Gnuplot Plotting File: C:\l\Blood\56_Ohsako_2 001_Anogen_HillCV_U_l.plt

Mon Feb 08 13:27:04 2010

Figure 7

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = Mean
Independent variable = Dose
rho is set to 0

Power parameter is not restricted
A constant variance model is fit

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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Total number of dose groups = 5

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

alpha =	7.27386

rho =	0 Specified

intercept =	28.905

v =	-5.1065

n =	1. 57046

k =	2 .4317

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -rho

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha
intercept

alpha
1

-3.le-008
7.5e-009
1. 7e-008
-8 . 8e-009

intercept
-3.le-008
1

0. 001
0.0016
-0.13

v

7.5e-009
0. 001
1

0. 98
-0. 99

n

1. 7e-008
0. 0016
0. 98
1

-0. 97

k

. 8e-009
-0.13
-0. 99
-0. 97
1

Parameter Estimates

Variable
alpha
intercept

Estimate

7 . 06192
28 . 9618
-6.82284
0.591421
7 .47064

Std. Err.

I.	35907
0.754441

II.1104
1. 04

48.002

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

4.3982
27.4831
-28.5989
-1.44695
-86.6115

9.72564

30.4404
14.9532
2.62979
101.553

Table of Data and Estimated Values of Interest
5	N Obs Mean	Est Mean Obs Std Dev Est Std Dev Scaled Res.

0	12	28.9	29	3.13	2.66	-0.074

1.04	10	27.9	27.3	2.5	2.66	0.71

3.471	10	25.2	26.3	3.21	2.66	-1.36

11.36	10	26	25.1	2.85	2.66	1.04

38.42	12	23.8	24	1.56	2.66	-0.284

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(iji

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij|

This document is a draft for review purposes only and does not constitute Agency policy.

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Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma^2
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1 -77.952340	6	167.904680

A2 -74.703868	10	169.407736

A3 -77.952340	6	167.904680

fitted -79.777354	5	169.554709

R -89.824703	2	183.649405

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1
Test 2
Test 3
Test 4

30.2417
6.4 9 6 9 4
6.4 9 6 9 4
3.65003

0.0001916
0.165
0.165
0.05607

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than .1. A homogeneous variance
model appears to be appropriate here

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is less than .1. You may want to try a different
model

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	3.49389

BMDL =	0.304602

This document is a draft for review purposes only and does not constitute Agency policy.

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E.2.40.5. Figure for Additional Model Presented: Hill, Unrestricted

Hill Model with 0.95 Confidence Level

dose

13:27 02/08 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.2.41. Sewall et al., 1995: T4 In Serum
E.2.41.1. Summary Table of BMDS Modeling Results

Model3

Degrees of
Freedom

x2 p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential (M2)

3

0.722

204.495

1.869E+01

1.243E+01



exponential (M3)

3

0.722

204.495

1.869E+01

1.243E+01

power hit bound (d = 1)

exponential (M4)

2

0.854

205.483

1.106E+01

4.650E+00



exponential (M5)

2

0.854

205.483

1.106E+01

4.650E+00

power hit bound (d = 1)

Hillb

2

0.898

205.382

1.031E+01

3.603E+00

n lower bound hit (n = 1)

linear

3

0.576

205.150

2.238E+01

1.619E+01



polynomial, 4-
degree

3

0.576

205.150

2.238E+01

1.619E+01



power

3

0.576

205.150

2.238E+01

1.619E+01

power bound hit (power =1)

Hill, unrestricted0

1

0.864

207.196

9.706E+00

1.973E+00

unrestricted (n = 0.569)

power, unrestricted

2

0.985

205.197

9.726E+00

1.914E+00

unrestricted (power = 0.538)

a Constant variance model selected (p = 0.4078)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.2.41.2. Output for Selected Model: Hill

Sewall et al., 1995: T4 In Serum

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\l\Blood\58_Sewall_l995_T4_HillCV_l.(d)

Gnuplot Plotting File: C:\l\Blood\58_Sewall_1995_T4_HillCV_l.plt

Mon Feb 08 13:28:15 2010

Figure 1, Saline noninitiated

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = Mean
Independent variable = Dose
rho is set to 0

Power parameter restricted to be greater than 1

This document is a draft for review purposes only and does not constitute Agency policy.

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A constant variance model is fit

Total number of dose groups = 5

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

alpha
rho

intercept

33.0913

0

30.6979
-12 .2937
0.950815
12 . 5808

Specified

Asymptotic Correlation Matrix of Parameter Estimates

alpha
intercept

The model parameter(s) -rho -n

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha
1

-1. 2e-009
-1. 8e-008
1. 5e-008

intercept
-1.2e-009
1

0.3
-0. 65

v

-1.8e-008
0.3
1

-0.89

k

1. 5e-008
-0. 65
-0.89
1

Parameter Estimates

Variable
alpha
intercept

k

Estimate
29.5556
30.3957
-18.2488
1

24.2883

Std. Err.
6.23087
1.68747
7.72836
NA
26.743

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

17.3433

27 . 0883
-33.3961

-28 .127

41.7679
33.7031
-3.10154

76.7035

NA - Indicates that this parameter has hit a bound
implied by some ineguality constraint and thus
has no standard error.

Table of Data and Estimated Values of Interest

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0

9

30

7

o

CO

4

6 6

5.44

0.167

3.291

9

27

9

28 . 2

7

17

5.44

-0.188

7 .107

9

25

9

26.3

6

81

5.44

-0.204

16. 63

9

23

6

23

5

38

5.44

0.319

44.66

9

18

4

18 . 6

4

12

5.44

-0.0942

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(iji

This document is a draft for review purposes only and does not constitute Agency policy.

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Var{e(ij)} = Sigma^2

Model A2 :	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma^2
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model
A1
A2
A3

fitted
R

Log(likelihood)
-98.583448
-96.590204
-98.583448
-98.691143
-109.013252

Param1s

10

AIC
209.166896
213.180407
209.166896
205.382286
222.026503

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1
Test 2
Test 3
Test 4

24.8461
3.98649
3.98649
0.21539

0.001651
0.4078
0.4078
0. 897 9

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than .1. A homogeneous variance
model appears to be appropriate here

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adeguately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	10.306

BMDL =	3.60269

This document is a draft for review purposes only and does not constitute Agency policy.

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E.2.41.3. Figure for Selected Model: Hill

Hill Model with 0.95 Confidence Level

dose

13:28 02/08 2010

E.2.41.4. Output for Additional Model Presented: Hill, Unrestricted
Sewall et al., 1995: T4 In Serum

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\l\Blood\58_Sewall_l995_T4_HillCV_U_l.(d)

Gnuplot Plotting File: C:\l\Blood\58_Sewall_1995_T4_HillCV_U_l.plt

Mon Feb 08 13:28:15 2010

Figure 1, Saline noninitiated

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = Mean
Independent variable = Dose
rho is set to 0

Power parameter is not restricted
A constant variance model is fit

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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Total number of dose groups = 5

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

alpha
rho

intercept

33.0913

0

30.6979
-12 .2937
0.950815
12 . 5808

Specified

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -rho

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha
intercept

alpha
1

-3.9e-005
0.00022
0.00021
-0.00022

intercept
-3.9e-005
1

-0.17
-0.31
0.18

v

0.00022
-0.17
1

0. 97
-1

n

0.00021
-0.31
0. 97
1

-0. 98

k

-0.00022
0.18
-1

-0. 98
1

Parameter Estimates

Variable
alpha
intercept

Estimate

29.4337
30.7096
-143.244
0.569063
2856.29

Std. Err.
6.20518
1.79801
3972.28
0.947248
171186

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

17 . 2718

27 .1855
-7928.78
-1.28751
-332662

41. 5957

34 . 2336
7642.29
2 .42564
338374

Table of Data and Estimated Values of Interest

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0

9

30

7

30

7

4

6 6

5.43

-0.00646

291

9

27

9

27

7

7

17

5.43

0.0842

107

9

25

9

26

1

6

81

5.43

-0.134

. 63

9

23

6

23

4

5

38

5.43

0.0657

. 6 6

9

18

4

18

4

4

12

5.43

-0.00948

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij)

This document is a draft for review purposes only and does not constitute Agency policy.

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Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma^2
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model
A1
A2
A3

fitted
R

Log(likelihood)
-98.583448
-96.590204
-98.583448
-98.598183
-109.013252

10

AIC
209.166896
213.180407
209.166896
207.196367
222.026503

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1
Test 2
Test 3
Test 4

24.8461
3.98649
3.98649
0.0294713

0.001651
0.4078
0.4078
0.8637

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than .1. A homogeneous variance
model appears to be appropriate here

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adeguately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	9.70574

BMDL =	1.97319

This document is a draft for review purposes only and does not constitute Agency policy.

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l E.2.41.5. Figure for Additional Model Presented: Hill, Unrestricted

Hill Model with 0.95 Confidence Level

dose

2	13:28 02/08 2010

3

4

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E.2.42. Shi et al., 2007: Estradiol 17B, PE9
E.2.42.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

r p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential (M2)

3

0.010

391.638

6.976E+00

3.761E+00



exponential (M3)

3

0.010

391.638

6.976E+00

3.761E+00

power hit bound (d = 1)

exponential
(M4)b

2

0.690

382.969

8.068E-01

3.544E-01



exponential (M5)

2

0.690

382.969

8.068E-01

3.544E-01

power hit bound (d = 1)

Hill

2

0.975

382.278

7.239E-01

error

n lower bound hit (n = 1)

linear

3

0.003

394.308

9.841E+00

6.687E+00



polynomial, 4-
degree

3

0.003

394.308

9.841E+00

6.687E+00



power

3

0.003

394.308

9.841E+00

6.687E+00

power bound hit (power = 1)

Hill, unrestricted

1

0.897

384.243

7.086E-01

error

unrestricted (n = 0.875)

power,
unrestricted

2

0.506

383.590

6.280E-01

3.304E-02

unrestricted (power = 0.222)

a Non-constant variance model selected (p = 0.0521)
b Best-fitting model, BMDS output presented in this appendix

E.2.42.2. Output for Selected Model: Exponential (M4)

Shi et al., 2007: Estradiol 17B, PE9

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\l\Blood\59_Shi_2007_Estradiol_Exp_l.(d)

Gnuplot Plotting File:

Mon Feb 08 13:28:52 2010

Figure 4 PE9 only

The form of the response function by Model:

Model 2
Model 3
Model 4
Model 5

Y[dose]
Y[dose]
Y[dose]
Y[dose]

exp{sign *	b * dose}

exp{sign *	(b * dosej^d}

[c-(c-l) *	exp{-b * dose}]

[c-(c-l) *	exp{-(b * dosej^d}

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;
sign = -1 for decreasing trend.

This document is a draft for review purposes only and does not constitute Agency policy.

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Model 2 is nested within Models 3 and 4.
Model 3 is nested within Model 5.

Model 4 is nested within Model 5.

Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)
Total number of dose groups = 5

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values
Variable	Model 4

lnalpha	2.65881

rho	0.913414

a	108

b	0.277637

c	0.340136

d	1

Parameter Estimates
Variable	Model 4

lnalpha	1.66773

rho	1.15314

a	103.146

b	1.00685

c	0.418742

d	1

Table of Stats From Input Data
Dose	N	Obs Mean	Obs Std Dev

0	10	102.9	41.41

0.3418	10 86.19	19.58

1.075	10	63.33	29.36

5.23	10 48.1	18.82

13.91	10	38.57	22.59

Estimated Values of Interest
Dose	Est Mean	Est Std	Scaled Residual

0	103.1	33.35	-0.02738

0.3418	85.69	29.96	0.05296

1.075	63.51	25.21	-0.02238

5.23	43.5	20.27	0.7167

13.91	43.19	20.19	-0.7237

Other models for which likelihoods are calculated:

This document is a draft for review purposes only and does not constitute Agency policy.

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Model A1:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma^2

Model A2 :	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma(i)^2

Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= exp(lalpha + log(mean(i) ) 'k rho)

Model R:	Yij	= Mu + e(i)

Var{e(ij)}	= Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	DF	AIC

A1	-188.3615	6	388.7231

A2	-183.667	10	387.3339

A3	-186.1132	7	386.2263

R	-203.3606	2	410.7211

4	-186.4844	5	382.9687

Additive constant for all log-likelihoods =	-45.95. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Test

1:

Does response

and/or variances differ among Dose levels? (A2 vs. R)

Test

2 :

Are Variances

Homogeneous? (A2 vs. A1)

Test

3:

Are variances

adequately modeled? (A2 vs. A3)

Test 6a: Does Model 4 fit the data? (A3 vs 4)

Test

Test 1
Test 2
Test 3
Test 6a

Tests of Interest

-2*log(Likelihood Ratio)

39.39
9.389
4 . 892
0.7424

D. F.

p-value

< 0.0001
0.05208
0.1798
0.6899

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose
levels, it seems appropriate to model the data.

The p-value for Test 2 is less than .1. A non-homogeneous
variance model appears to be appropriate.

The p-value for Test 3 is greater than .1. The modeled
variance appears to be appropriate here.

The p-value for Test 6a is greater than .1. Model 4 seems
to adeguately describe the data.

Benchmark Dose Computations:

Specified Effect = 1.000000

Risk Type = Estimated standard deviations from control
Confidence Level = 0.950000

This document is a draft for review purposes only and does not constitute Agency policy.

E-214 DRAFT—DO NOT CITE OR QUOTE


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BMD =	0.806817

BMDL =	0.354366

E.2.42.3. Figure for Selected Model: Exponential (M4)

Exponential Model 4 with 0.95 Confidence Level

a>

CO
c
o

Q.

CO
CD

a:

c
m

CD

140

120

100

80

60

40

20

Exponential

10

12

14

dose

13:28 02/08 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.2.43. Smialowicz et al., 2008: PFC per 10A6 Cells
E.2.43.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential (M2)

3

0.101

901.897

8.343E+00

5.064E+00



exponential (M3)

3

0.101

901.897

8.343E+00

5.064E+00

power hit bound (d = 1)

exponential (M4)

2

0.044

903.897

8.325E+00

1.465E+00



exponential (M5)

2

0.044

903.897

8.325E+00

1.465E+00

power hit bound (d = 1)

Hill

2

0.063

903.192

3.669E+00

6.970E-01

n lower bound hit (n = 1)

linear

3

0.048

903.585

1.373E+01

1.053E+01



polynomial, 4-
degree

3

0.048

903.585

1.374E+01

1.053E+01



power

3

0.048

903.585

1.373E+01

1.053E+01

power bound hit (power =1)

Hill, unrestricted

1

0.213

901.219

1.928E+00

2.208E-01

unrestricted (n = 0.35)

power,
unrestricted b

2

0.481

899.130

1.902E+00

2.158E-01

unrestricted (power = 0.333)

a Constant variance model selected (p = <0.0001)
b Best-fitting model, BMDS output presented in this appendix

E.2.43.2. Output for Selected Model: Power, Unrestricted

Smialowicz et al., 2008: PFC per 10A6 Cells

Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\l\Blood\60_Smial_2008_PFCcells_PwrCV_U_l.(d)

Gnuplot Plotting File: C:\l\Blood\60_Smial_2008_PFCcells_PwrCV_U_l.plt

Mon Feb 08 13:29:38 2010

Anti Response to SRBCs, PFC per 10to6 cells, Table 4

The form of the response function is:

Y[dose] = control + slope * doseApower

Dependent variable = Mean
Independent variable = Dose
rho is set to 0
The power is not restricted
A constant variance model is fit

This document is a draft for review purposes only and does not constitute Agency policy.

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Total number of dose groups = 5

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

alpha
rho
control
slope
power

232385

0

1491
-491.716
0.288021

Specified

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -rho

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha	control	slope	power

alpha	1 -3.4e-009	1.8e-009 -1.2e-010

control -3.4e-009	1	-0.82	-0.65

slope	1.8e-009	-0.82	1	0.94

power -1.2e-010	-0.65	0.94	1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
alpha
control
slope
power

Estimate

219793
1470.48
-378.406
0.333124

Std. Err.
37974.5
123.73
157.002
0.113501

Lower Conf. Limit

145365
1227.98
-686.125
0.110666

Upper Conf. Limit

294222
1712.99
-70.6872
0.555581

Table of Data and Estimated Values of Interest
Dose	N Obs Mean	Est Mean Obs Std Dev Est Std Dev Scaled Res.

0

0. 438
2.464
13. 4
31. 65

15

1. 4 9e + 003

1. 47e + 003

716

469

0.169

14

1.13e + 003

1.18e + 003

171

469

-0.431

15

945

959

516

469

-0.12

15

677

572

465

469

0. 867

8

161

274

117

469

-0.684

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

This document is a draft for review purposes only and does not constitute Agency policy.

E-217 DRAFT—DO NOT CITE OR QUOTE


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Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1 -444.832859	6	901.665718

A2 -425.402825	10	870.805651

A3 -444.832859	6	901.665718

fitted -445.564823	4	899.129647

R -463.753685	2	931.507371

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Test

2

Test

3

Test

4

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	76.7017	8	<.0001

Test 2	38.8601	4	<.0001

Test 3	38.8601	4	<.0001

Test 4	1.46393	2	0.481

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. Consider running a
non-homogeneous variance model

The p-value for Test 3 is less than .1. You may want to consider a
different variance model

The p-value for Test 4 is greater than .1. The model chosen seems
to adeguately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD = 1.9024 9

BMDL = 0.215843

This document is a draft for review purposes only and does not constitute Agency policy.

E-218 DRAFT—DO NOT CITE OR QUOTE


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E.2.43.3. Figure for Selected Model: Power, Unrestricted

Power Model with 0.95 Confidence Level

dose

13:29 02/08 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-219 DRAFT—DO NOT CITE OR QUOTE


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E.2.44. Smialowicz et al., 2008: PFC per Spleen

E.2.44.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

r p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential (M2)

3

0.124

377.565

1.334E+01

8.593E+00



exponential (M3)

2

0.069

379.138

1.536E+01

8.895E+00



exponential (M4)

3

0.124

377.565

1.334E+01

8.593E+00



exponential (M5)

1

0.021

381.138

1.536E+01

8.895E+00



Hill

2

0.116

378.108

1.568E+01

error

n lower bound hit (n = 1)

linear

3

0.126

377.522

2.055E+01

1.624E+01



polynomial, 4-
degree

3

0.126

377.522

2.055E+01

1.624E+01



power

3

0.126

377.522

2.055E+01

1.624E+01

power bound hit (power =1)

Hill, unrestricted

1

0.103

378.463

1.202E+01

error

unrestricted (n = 0.544)

power,
unrestricted b

2

0.270

376.420

1.187E+01

3.762E+00

unrestricted (power = 0.531)

a Non-constant variance model selected (p = 0.0011)
b Best-fitting model, BMDS output presented in this appendix

E.2.44.2. Output for Selected Model: Power, Unrestricted

Smialowicz et al., 2008: PFC per Spleen

Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\l\Blood\61_Smial_2008_PFCspleen_Pwr_U_l.(d)

Gnuplot Plotting File: C:\l\Blood\61_Smial_2008_PFCspleen_Pwr_U_l.plt

Mon Feb 0 8 13:3 0:16~2 010

Anti Response to SRBCs - PFC x 10 to the 4 per spleen, Table 4

The form of the response function is:

Y[dose] = control + slope * doseApower

Dependent variable = Mean
Independent variable = Dose
The power is not restricted

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)

This document is a draft for review purposes only and does not constitute Agency policy.

E-220 DRAFT—DO NOT CITE OR QUOTE


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Total number of dose groups = 5

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
lalpha =	4.76607

rho =	0

control =	27.8

slope =	-9.21898

power =	0.286443

Asymptotic Correlation Matrix of Parameter Estimates

lalpha
rho
control
slope
power

lalpha
1

-0. 98
0.25
-0.28
-0.22

rho

-0. 98
1

-0.3

0.28
0.22

control
0.25
-0.3

1

-0. 83
-0.74

slope

-0.28
0.28
-0. 83
1

0. 99

power

-0.22
0.22
-0.74
0. 99
1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
lalpha
rho
control
slope
power

Estimate
0.746922
1. 36826
25.3816
-3.5662
0.531216

Std. Err.

1.02058
0.355827
2.96691
2.52558
0.175728

Lower Conf. Limit

-1.25337
0. 67085
19.5666
-8 . 51626
0.186796

Upper Conf. Limit
2 .74721
2.06567
31.1967
1. 38385
0. 875637

Table of Data and Estimated Values of Interest

0

0. 438
2.464
13. 4
31. 65

N

Obs Mean

Est Mean

Obs Std Dev

Est Std Dev

Scaled Res

15

27 . 8

25. 4

13

4

13.3

0.706

14

21

23.1

13

6

12 . 4

-0.626

15

17 . 6

19.6

9

4

11.1

-0.704

15

12 . 6

11 2

8

7

7 . 6

0.702

8

3

CO

o

CO

3

1

3.1

-0.0313

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

This document is a draft for review purposes only and does not constitute Agency policy.

E-221 DRAFT—DO NOT CITE OR QUOTE


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Model R:	Yi = Mu + e(i

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model	Log(likelihood) # Param's	AIC

A1 -190.565019	6	393.130038

A2 -181.476284	10	382.952569

A3 -181.900030	7	377.800059

fitted -183.210137	5	376.420274

R -204.636496	2	413.272993

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Test

2

Test

3

Test

4

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	46.3204	8	<.0001

Test 2	18.1775	4	0.001139

Test 3	0.84749	3	0.8381

Test 4	2.62021	2	0.2698

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adeguately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD = 11.8748

BMDL = 3.76161

This document is a draft for review purposes only and does not constitute Agency policy.

E-222 DRAFT—DO NOT CITE OR QUOTE


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E.2.44.3. Figure for Selected Model: Power, Unrestricted

Power Model with 0.95 Confidence Level

dose

13:30 02/08 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-223 DRAFT—DO NOT CITE OR QUOTE


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E.2.45. Toth et al., 1979: Amyloidosis

E.2.45.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

gamma

2

0.040

149.120

1.965E+01

1.283E+01

power bound hit (power = 1)

logistic

2

0.019

151.340

3.701E+01

2.858E+01

negative intercept (intercept =
-2.16)

log-logistica

2

0.053

148.269

1.503E+01

8.747E+00

slope bound hit (slope = 1)

log-probit

2

0.009

152.855

3.782E+01

2.502E+01

slope bound hit (slope =1)

multistage, 3-
degree

2

0.040

149.120

1.965E+01

1.283E+01

final B = 0

probit

2

0.021

151.115

3.467E+01

2.657E+01

negative intercept (intercept =
-1.276)

Weibull

2

0.040

149.120

1.965E+01

1.283E+01

power bound hit (power = 1)

gamma,
unrestricted

2

0.959

140.119

4.349E-01

2.891E-03

unrestricted (power = 0.254)

log-logistic,
unrestricted b

2

0.903

140.240

4.843E-01

5.312E-03

unrestricted (slope = 0.326)

log-probit,
unrestricted

2

0.870

140.315

4.960E-01

7.292E-03

unrestricted (slope = 0.186)

Weibull,
unrestricted

2

0.933

140.174

4.641E-01

4.069E-03

unrestricted (power = 0.289)

a Best-fitting model, BMDS output presented in this appendix
b Alternate model, BMDS output also presented in this appendix

E.2.45.2. Output for Selected Model: Log-Logistic

Toth et al., 1979: Amyloidosis

Logistic Model. (Version: 2.12; Date: 05/16/2008)

Input Data File: C:\l\Blood\62_Toth_l979_Amylyr_LogLogistic_l.(d)

Gnuplot Plotting File: C:\l\Blood\62_Toth_197 9_Amylyr_LogLogistic_l.plt

Mon Feb 08 13:30:54 2010

Table 2

The form of the probability function is:

P[response] = background+(1-background)/[1+EXP(-intercept-slope*Log(dose))]

Dependent variable = DichEff
Independent variable = Dose

This document is a draft for review purposes only and does not constitute Agency policy.

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Slope parameter is restricted as slope >= 1

Total number of observations = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

User has chosen the log transformed model

Default Initial Parameter Values
background =	0

intercept =	-4.54593

slope =	1

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -slope

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

background intercept

background	1	-0.49

intercept	-0.49	1

Parameter Estimates

95.0% Wald Confidence Interval

Variable Estimate Std. Err.	Lower Conf.	Limit Upper Conf. Limit

background 0.0699918 *	*	*

intercept -4.90704 *	*	*

slope 1 *	*	*

Indicates that this value is not calculated.

Analysis of Deviance Table

Model	Log(likelihood)	# Param's	Deviance	Test d.f.	P-value

Full model	-68.017	4

Fitted model	-72.1346	2	8.23525	2	0.0162e

Reduced model	-82.0119	1	27.99	3	<.0001

AIC:	148.269

Goodness of Fit

Scaled

Dose Est. Prob. Expected Observed	Size	Residual

0.0000 0.0700 2.660 0.000	38	-1.691

0.5732 0.0739 3.252 5.000	44	1.007

14.2123 0.1584 6.971 10.000	44	1.251

91.2070 0.4446 19.117 17.000	43	-0.650

Chi/N2 = 5.86	d.f. = 2	P-value = 0.0534

Benchmark Dose Computation
Specified effect =	0.1

This document is a draft for review purposes only and does not constitute Agency policy.

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Risk Type	=

Confidence level =

Extra risk
0. 95

BMD =	15.0264

BMDL =	8.7 4 665

E.2.45.3. Figure for Selected Model: Log-Logistic

Log-Logistic Model with 0.95 Confidence Level

dose

13:30 02/08 2010

E.2.45.4. Output for Additional Model Presented: Log-Logistic, Unrestricted
Toth et al., 1979: Amyloidosis

Logistic Model. (Version: 2.12; Date: 05/16/2008)

Input Data File: C:\l\Blood\62_Toth_l979_Amylyr_LogLogistic_U_l.(d)

Gnuplot Plotting File: C:\l\Blood\62_Toth_197 9_Amylyr_LogLogistic_U_l.plt

Mon Feb 08 13:30:54 2010

Table 2

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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The form of the probability function is:

P[response] = background+(1-background)/[1+EXP(-intercept-slope*Log(dose))]

Dependent variable = DichEff
Independent variable = Dose
Slope parameter is not restricted

Total number of observations = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

User has chosen the log transformed model

Default Initial Parameter Values
background =	0

intercept =	-1.92722

slope =	0.314472

Asymptotic Correlation Matrix of Parameter Estimates

The model parameter(s) -background

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

intercept	slope

intercept	1	-0.84

slope	-0.84	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

background	0	*	*	*

intercept	-1.96073	*	*	*

slope	0.326156	*	*	*

Indicates that this value is not calculated.

Analysis of Deviance Table

Model	Log(likelihood)	# Param's	Deviance	Test d.f.	P-value

Full model	-68.017	4

Fitted model	-68.1201	2	0.206341	2	0.902

Reduced model	-82.0119	1	27.99	3	<.0001

AIC:	140.24

Goodness of Fit

Scaled

Dose Est. Prob. Expected Observed	Size	Residual

0.0000 0.0000 0.000 0.000	38	0.000

0.5732 0.1051 4.623 5.000	44	0.186

14.2123 0.2507 11.029 10.000	44	-0.358

91.2070 0.3802 16.348 17.000	43	0.205

This document is a draft for review purposes only and does not constitute Agency policy.

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Chi' 2 = 0.20	d.f. = 2

P-value = 0.9028

E'.enchmark Dose Computation
Specified effect =	0 .1

Risk Typ'e	=	E::tra risk

Cc'nfidence level =	0.95

BMD =	0.4 84272

EMDL =	0.00531211

E.2.45.5. Figure for Additional Model Presented: Log-Logistic, Unrestricted

Log-Logistic Model with 0.95 Confidence Level

"O

(D

-t—<

o

(U
!t=
<

20

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80

dose

13:30 02/08 2010

This document is a draft for review purposes only and does not constitute Agency policy.

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E.2.46. Toth et al., 1979: Skin Lesions

E.2.46.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

gamma

2

0.032

156.346

1.037E+01

7.470E+00

power bound hit (power = 1)

logistic

2

0.005

161.421

2.487E+01

1.982E+01

negative intercept (intercept =
-1.999)

log-logistica

2

0.078

153.963

6.413E+00

4.025E+00

slope bound hit (slope = 1)

log-probit

2

0.003

161.788

1.887E+01

1.280E+01

slope bound hit (slope =1)

multistage, 3-
degree

2

0.032

156.346

1.037E+01

7.470E+00

final B = 0

probit

2

0.006

160.991

2.309E+01

1.858E+01

negative intercept (intercept =
-1.198)

Weibull

2

0.032

156.346

1.037E+01

7.470E+00

power bound hit (power = 1)

gamma,
unrestricted

2

0.945

147.148

error

error

unrestricted (power = 0.341)

log-logistic,
unrestricted b

2

0.744

147.631

5.969E-01

6.773E-02

unrestricted (slope = 0.48)

log-probit,
unrestricted

2

0.670

147.844

5.939E-01

8.147E-02

unrestricted (slope = 0.279)

Weibull,
unrestricted

2

0.866

147.324

5.539E-01

5.181E-02

unrestricted (power = 0.405)

a Best-fitting model, BMDS output presented in this appendix
b Alternate model, BMDS output also presented in this appendix

E.2.46.2. Output for Selected Model: Log-Logistic

Toth et al., 1979: Skin Lesions

Logistic Model. (Version: 2.12; Date: 05/16/2008)

Input Data File: C:\l\Blood\63_Toth_l979_SkinLes_LogLogistic_l.(d)

Gnuplot Plotting File: C:\l\Blood\63_Toth_197 9_SkinLes_LogLogistic_l.plt

~~Wed Feb 10 14:47:53 2 010~

Table 2

The form of the probability function is:

P[response] = background+(1-background)/[1+EXP(-intercept-slope*Log(dose))]

Dependent variable = DichEff
Independent variable = Dose

This document is a draft for review purposes only and does not constitute Agency policy.

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Slope parameter is restricted as slope >= 1

Total number of observations = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

User has chosen the log transformed model

Default Initial Parameter Values
background =	0

intercept =	-3.94312

slope =	1

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -slope

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

background intercept

background	1	-0.43

intercept	-0.43	1

Parameter Estimates

95.0% Wald Confidence Interval

Variable Estimate Std. Err.	Lower Conf.	Limit Upper Conf. Limit

background 0.0564562 *	*	*

intercept -4.05558 *	*	*

slope 1 *	*	*

Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-71.5177	4

Fitted model -74.9813 2	6.92722 2	0.03132

Reduced model -95.8498 1	48.6642 3	<.0001

AIC:	153.963

Goodness of Fit

Scaled

Dose Est. Prob. Expected Observed	Size	Residual

0.0000 0.0565 2.145 0.000	38	-1.508

0.5732 0.0657 2.892 5.000	44	1.282

14.2123 0.2429 10.687 13.000	44	0.813

91.2070 0.6343 27.275 25.000	43	-0.720

Chi ^2 = 5.10	d.f. = 2	P-value = 0.0782

Benchmark Dose Computation
Specified effect =	0.1

This document is a draft for review purposes only and does not constitute Agency policy.

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Risk Type	=

Confidence level =

Extra risk
0. 95

BMD =	6.4132

BMDL =	4.02 4 9

E.2.46.3. Figure for Selected Model: Log-Logistic

Log-Logistic Model with 0.95 Confidence Level

dose

14:47 02/10 2010

E.2.46.4. Output for Additional Model Presented: Log-Logistic, Unrestricted
Toth et al., 1979: Skin Lesions

Logistic Model. (Version: 2.12; Date: 05/16/2008)

Input Data File: C:\l\Blood\63_Toth_l979_SkinLes_LogLogistic_U_l.(d)

Gnuplot Plotting File: C:\l\Blood\63_Toth_197 9_SkinLes_LogLogistic_U_l.plt

Wed Feb 10 14:47:54 2010

Table 2

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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The form of the probability function is:

P[response] = background+(1-background)/[1+EXP(-intercept-slope*Log(dose))]

Dependent variable = DichEff
Independent variable = Dose
Slope parameter is not restricted

Total number of observations = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

User has chosen the log transformed model

Default Initial Parameter Values
background =	0

intercept =	-1.87608

slope =	0.458888

Asymptotic Correlation Matrix of Parameter Estimates

The model parameter(s) -background

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

intercept	slope

intercept	1	-0.86

slope	-0.86	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

background	0	*	*	*

intercept	-1.94946	*	*	*

slope	0.4802	*	*	*

Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-71.5177	4

Fitted model -71.8153 2	0.59526 2	0.742£

Reduced model -95.8498 1	48.6642 3	<.0001

AIC:	147.631

Goodness of Fit

Scaled

Dose Est. Prob. Expected Observed	Size	Residual

0.0000 0.0000 0.000 0.000	38 0.000

0.5732 0.0983 4.323 5.000	44 0.343

14.2123 0.3374 14.845 13.000	44	-0.588

91.2070 0.5542 23.832 25.000	43 0.358

This document is a draft for review purposes only and does not constitute Agency policy.

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Chi' 2 = 0.59	d.f. = 2

E'-value =

0.7438

E'.enchmark Dose Computation
Specified effect =	0 .1

Risk Typ'e	=	E::tra risk

Cc'nfidence level =	0.95

BMD =	0.596932

BMDL =	0.06773

E.2.46.5. Figure for Additional Model Presented: Log-Logistic, Unrestricted

Log-Logistic Model with 0.95 Confidence Level

20	40	60	80

dose

14:47 02/10 2010

T 1 '' ' • • • ' ' I • • • ' ' • • • • I ' ' • • • ' ' • • I 1 1 ' ' • • • ' ' I ' • • • ' ^

Log-Logistic 	

T

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.2.47. Van Birgelen et al., 1995a: Hepatic Retinol
E.2.47.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential (M2)

4

<0.0001

159.735

7.790E+00

4.150E+00



exponential (M3)

4

<0.0001

3222.700

5.542E+01

error

power hit bound (d = 1)

exponential
(M4)b

3

<0.001

141.454

2.488E+01

3.363E+00



exponential (M5)

3

<0.001

141.454

2.488E+01

3.363E+00

power hit bound (d = 1)

Hill

3

0.239

124.865

5.316E+00

error

n lower bound hit (n = 1)

linear

4

<0.0001

176.828

1.877E+02

1.437E+02



polynomial, 5-
degree

4

<0.0001

176.828

1.877E+02

1.437E+02



power

4

<0.0001

176.828

1.877E+02

1.437E+02

power bound hit (power =1)

Hill, unrestricted

2

0.241

125.495

3.595E+00

error

unrestricted (n = 0.763)

power,
unrestricted0

3

0.011

131.771

3.802E-01

1.393E-02

unrestricted (power = 0.14)

a Non-constant variance model selected (p = <0.0001)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.2.47.2. Output for Selected Model: Exponential (M4)

Van Birgelen et al., 1995a: Hepatic Retinol

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\l\Blood\65_VanB_l995a_HepRet_Exp_l.(d)

Gnuplot Plotting File:

Mon Feb 08 13:32:00 2010

Tbl3, hepatic retinol

The form of the response function by Model:

Model 2
Model 3
Model 4
Model 5

Y[dose]
Y[dose]
Y[dose]
Y[dose]

exp{sign *	b * dose}

exp{sign *	(b * dosej^d}

[c-(c-l) *	exp{-b * dose}]

[c-(c-l) *	exp{-(b * dosej^d}

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;

This document is a draft for review purposes only and does not constitute Agency policy.

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sign = -1 for decreasing trend.

Model 2 is nested within Models 3 and 4.
Model 3 is nested within Model 5.

Model 4 is nested within Model 5.

Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)
Total number of dose groups = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values
Variable	Model 4

lnalpha	-1.16065

rho	1.53688

a	15.645

b	0.0254351

c	0.0365247

d	1

Parameter Estimates
Variable	Model 4

lnalpha	-0.92683

rho	1.77262

a	11.5049

b	0.0286598

c	0.0653043

d	1

Table of Stats From Input Data

Dose	N	Obs Mean	Obs Std Dev

0	8	14.9	8.768

7.204	8	8.4	3.394

11.76	8	8.2	2.263

18.09	8	5.1	0.8485

86.41	8	2.2	0.8485

250.2	8	0.6	0.5657

Estimated Values of Interest
Dose	Est Mean	Est Std	Scaled Residual

0	11.5	5.483	1.751

7.204	9.499	4.627	-0.6719

11.76	8.428	4.161	-0.1552

18.09	7.154	3.599	-1.615

86.41	1.655	0.9832	1.568

250.2	0.7596	0.4931	-0.9155

This document is a draft for review purposes only and does not constitute Agency policy.

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Other models for which	likelihoods are calculated:

Model A1:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma/'2

Model A2 :	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma(i)^2

Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= exp(lalpha + log(mean(i)) * rho)

Model R:	Yij	= Mu + e(i)

Var{e(ij)}	= Sigma/'2

Likelihoods of Interest

Model	Log(likelihood)	DF	AIC

A1	-87.1567	7	188.3134

A2	-47.28742	12	118.5748

A3	-55.32422	8	126.6484

R	-109.967	2	223.934

4	-65.72714	5	141.4543

Additive constant for all log-likelihoods =	-44.11. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Test

1:

Does response

and/or variances differ among Dose levels? (A2 vs. R)

Test

2 :

Are Variances

Homogeneous? (A2 vs. A1)

Test

3:

Are variances

adeguately modeled? (A2 vs. A3)

Test 6a: Does Model 4 fit the data? (A3 vs 4)

Test

Test 1
Test 2
Test 3
Test 6a

Tests of Interest

-2*log(Likelihood Ratio)

125. 4
79.74
16. 07
20. 81

10
5
4
3

p-value

<	0.0001

<	0.0001
0. 002922

0.0001155

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose
levels, it seems appropriate to model the data.

The p-value for Test 2 is less than .1. A non-homogeneous
variance model appears to be appropriate.

The p-value for Test 3 is less than .1. You may want to
consider a different variance model.

The p-value for Test 6a is less than .1. Model 4 may not adeguately
describe the data; you may want to consider another model.

Benchmark Dose Computations:

Specified Effect = 1.000000

This document is a draft for review purposes only and does not constitute Agency policy.

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Risk Type = Estimated standard deviations from control
Confidence Level = 0.950000

BMD =	24.8811

BMDL =	3.36281

E.2.47.3. Figure for Selected Model: Exponential (M4)

Exponential Model 4 with 0.95 Confidence Level

dose

13:32 02/08 2010

E.2.47.4. Output for Additional Model Presented: Power, Unrestricted
Van Birgelen et al., 1995a: Hepatic Retinol

Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\l\Blood\65_VanB_l995a_HepRet_Pwr_U_l.(d)

Gnuplot Plotting File: C:\l\Blood\65_VanB_1995a_HepRet_Pwr_U_l.plt

Mon Feb 08 13:32:03 2010

Tbl3, hepatic retinol

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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The form of the response function is:
Y[dose] = control + slope * doseApower

Dependent variable = Mean

Independent variable = Dose

The power is not restricted

The variance is to be modeled as Var(i)

exp(lalpha + log(mean(i))

rho)

Total number of dose groups = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
lalpha =	2.76506

rho =	0

control =	14.9

slope =	-3.98831

power =	0.231232

Asymptotic Correlation Matrix of Parameter Estimates

lalpha
rho
control
slope
power

lalpha
1

-0.8

-0.042
0. 038
0. 063

rho
-0.8

1

-0.089
0.0044
-0.1

control

-0.042
-0.089
1

-0. 95
-0. 81

slope

0. 038
0.0044
-0. 95
1

0. 95

power
0. 063
-0.1

-0. 81
0. 95
1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
lalpha
rho
control
slope
power

Estimate

-0.986251
1.67858
16.9266
-7.51118
0.139871

Std. Err.
0.394722
0.202896
2.23237
2.04379
0.0269576

Lower Conf. Limit
-1.75989
1.28091
12 . 5513
-11. 5169
0. 0870351

Upper Conf. Limit
-0.212609
2.07625
21.302
-3.50543
0.192707

Table of Data and Estimated Values of Interest

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0

7 .204
11.76
18.09
86.41
250.2

14 . 9

8 . 4
8 . 2
5.1
2 . 2
0.6

16. 9

7 . 03
6.32
5. 67
2 . 91
0.666

8 .77

3.39
2 .26
0.849
0.849
0.566

6.56

3.14
2 . 87
2 . 62
1. 5
0. 434

-0.874
1.24
1. 85
-0.611
-1. 34
-0.427

Model Descriptions for likelihoods calculated

This document is a draft for review purposes only and does not constitute Agency policy.

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Model A1:	Yij	= Mu(i) + e(iji

Var{e(ij)} = Sigma/'2

Model A2 :	Yij	= Mu(i) + e(ij|

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model
A1

A2
A3

fitted
R

Log(likelihood)

-87 .156698
-47.287416
-55.324218
-60.885746
-109.967018

Param's

7
12

8
5
2

AIC

188.313395
118.574833
126.648436
131.771493
223.934036

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

Test 3: Are variances adequately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.)

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1

Test 2
Test 3
Test 4

125.359
79.7386
16.0736
11.1231

10
5
4
3

<.0001
<.0001
0.002922
0.01108

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is less than .1. You may want to consider a
different variance model

The p-value for Test 4 is less than .1. You may want to try a different
model

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD = 0.380208

BMDL = 0.013927

This document is a draft for review purposes only and does not constitute Agency policy.

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E.2.47.5. Figure for Additional Model Presented: Power, Unrestricted

Power Model with 0.95 Confidence Level

dose

13:32 02/08 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.2.48. Van Birgelen et al., 1995a: Hepatic Retinol Palmitate
E.2.48.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

r p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential (M2)

4

<0.0001

460.282

error

error



exponential (M3)

4

<0.0001

460.282

error

error

power hit bound (d = 1)

exponential
(M4)b

3

<0.0001

446.995

1.415E+02

3.647E+01



exponential (M5)

3

<0.0001

446.995

1.415E+02

3.647E+01

power hit bound (d = 1)

Hill

3

0.009

416.233

3.657E+00

error

n lower bound hit (n = 1)

linear

4

<0.0001

486.375

3.487E+02

2.412E+02



polynomial, 5-
degree

0

N/A

584.170

error

5.617E+02



power

4

<0.0001

486.375

3.487E+02

2.412E+02

power bound hit (power = 1)

Hill, unrestricted

3

<0.0001

527.310

6.875E-14

6.875E-14

unrestricted (n = 0.613)

power,
unrestricted0

3

0.239

408.982

5.262E-02

5.889E-05

unrestricted (power = 0.064)

a Non-constant variance model selected (p = <0.0001)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.2.48.2. Output for Selected Model: Exponential (M4)

Van Birgelen et al., 1995a: Hepatic Retinol Palmitate

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\l\Blood\66_VanB_l995a_HepRetPalm_Exp_l.(d)

Gnuplot Plotting File:

Mon Feb 08 13:32:41 2010

Tbl3, hepatic retinol palmitate

The form of the response function by Model:

Model 2:	Y[dose] = a * exp{sign * b * dose}

Model 3:	Y[dose] = a * exp{sign * (b * dosej^d}

Model 4:	Y[dose] = a * [c-(c-l) * exp{-b * dose}]

Model 5:	Y[dose] = a * [c-(c-l) * exp{-(b * dosej^d}]

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;

This document is a draft for review purposes only and does not constitute Agency policy.

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sign = -1 for decreasing trend.

Model 2 is nested within Models 3 and 4.
Model 3 is nested within Model 5.

Model 4 is nested within Model 5.

Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)
Total number of dose groups = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values
Variable	Model 4

lnalpha	0.284674

rho	1.77158

a	4 95.6

b	0.0337826

c	0.00576502

d	1

Parameter Estimates
Variable	Model 4

No Convergence

lnalpha	-0.241601

rho	2.03456

a	223.848

b	0.0300737

c	0.0129253

d	1

Table of Stats From Input Data

Dose	N	Obs Mean	Obs Std Dev

0	8	472	271.5

7.204	8	94	67.88

11.76	8	107	76.37

18.09	8	74	39.6

86.41	8	22	22.63

250.2	8	3	2.828

Estimated Values of Interest
Dose	Est Mean	Est Std	Scaled Residual

0	223.8	217.8	3.222

7.204	180.8	175.3	-1.401

11.76	158	152.9	-0.9443

18.09	131.1	126.4	-1.278

86.41	19.33	18.03	0.4197

This document is a draft for review purposes only and does not constitute Agency policy.

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250.2

3. 013

2 .721

-0.01317

Other models for which	likelihoods are calculated:

Model A1:	Yij	=	Mu(i) + e(1j)

Var{e(ij)}	=	Sigma^2

Model A2:	Yij	=	Mu(i) + e(1j)

Var{e(ij)}	=	Sigma(i)^2

Model A3:	Yij	=	Mu(i) + e(1j)

Var{e(ij)}	=	exp(lalpha + log(mean(i) ) 'k rho)

Model R:	Yij	=	Mu + e(1)

Var{e(ij)}	=	Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	DF	AIC

A1	-250.5548	7	515.1096

A2	-196.7557	12	417.5115

A3	-197.3832	8	410.7663

R	-276.7896	2	557.5793

4	-218.4977	5	446.9954

Additive constant for all log-likelihoods =	-44.11. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Test 1: Does response and/or variances differ among Dose levels? (A2 vs. R)

Test 2: Are Variances Homogeneous? (A2 vs. A1)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 6a: Does Model 4 fit the data? (A3 vs 4)

Test

Test 1
Test 2
Test 3
Test 6a

Tests of Interest

-2*log(Likelihood Ratio)

160.1
107 . 6
1. 255
42 . 23

10
5
4
3

p-value

<	0.0001

<	0.0001

0.869

<	0.0001

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose
levels, it seems appropriate to model the data.

The p-value for Test 2 is less than .1. A non-homogeneous
variance model appears to be appropriate.

The p-value for Test 3 is greater than .1. The modeled
variance appears to be appropriate here.

The p-value for Test 6a is less than .1. Model 4 may not adeguately
describe the data; you may want to consider another model.

Benchmark Dose Computations:

This document is a draft for review purposes only and does not constitute Agency policy.

E-243 DRAFT—DO NOT CITE OR QUOTE


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Specified Effect	=	1.000000

Risk Type	=	Estimated standard deviations from contrui

Confidence Level	=	0.950000

EMD	=	141.528

E'.MDL	=	36.4 7 21

E.2.48.3. Figure for Selected Model: Exponential (M4)

Exponential Model 4 with 0.95 Confidence Level

dose

13:32 02/08 2010

E.2.48.4. Output for Additional Model Presented: Power, Unrestricted
Van Birgelen et al., 1995a: Hepatic Retinol Palmitate

Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\l\Blood\66_VanB_l995a_HepRetPalm_Pwr_U_l.(d)

Gnuplot Plotting File: C:\l\Blood\66_VanB_19 95a_HepRetPalm_Pwr_U_l.plt

Mon Feb 08 13:32:47 2010

Tbl3, hepatic retinol palmitate

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-244 DRAFT—DO NOT CITE OR QUOTE


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The form of the response function is:
Y[dose] = control + slope * doseApower

Dependent variable = Mean
Independent variable = Dose
The power is not restricted

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)

Total number of dose groups = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
lalpha =	9.57332

rho =	0

control =	472

slope =	-320.514

power = 0.0711173

Asymptotic Correlation Matrix of Parameter Estimates

lalpha	rho	control	slope	power

lalpha 1	-0.95	0.3	-0.31	-0.3

rho -0.95	1	-0.41	0.39	0.29

control 0.3	-0.41	1	-0.98	-0.82

slope -0.31	0.39	-0.98	1	0.9

power -0.3	0.29	-0.82	0.9	1

Parameter Estimates

Variable
lalpha
rho
control
slope
power

Estimate

0. 0640168
1. 81132
464.29
-324.216
0. 0639088

Std. Err.

0. 859472
0.197468
87 . 5705
83.3327
0. 0139778

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

-1.62052
1.42429
292.655
-487.545
0.0365129

1.74855
2 .19835
635.925
-160.887
0.0913048

Table of Data and Estimated Values of Interest

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0

7 .204
11.76
18.09
86.41
250.2

472

464

272

269

0.0812

94

96.5

67 . 9

64 . 7

-0.108

107

CO
CO

76.4

57 . 6

1.09

74

74.2

39.6

51

-0.00941

22

33.2

22 . 6

24 . 6

-1.28

3

2 .86

2 . 83

2 . 68

0.145

This document is a draft for review purposes only and does not constitute Agency policy.

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Model Descriptions for likelihoods calculated

Model A1:	Yij	= Mu(i) + e(iji

Var{e(ij)} = Sigma/'2

Model A2 :	Yij	= Mu(i) + e(ij|

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model
A1

A2
A3

fitted
R

Log(likelihood)
-250.554817
-196.755746
-197.383174
-199.490808
-276.789644

Param's

7
12

8
5
2

AIC
515.109634
417.511491
410.766347
408.981615
557.579287

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

Test 3: Are variances adequately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1

Test 2
Test 3
Test 4

160.068
107.598
1. 25486
4 . 21527

10
5
4
3

<.0001
<.0001
0.869
0.2391

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adequately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD = 0.0526247

This document is a draft for review purposes only and does not constitute Agency policy.

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BMDL = 5.8 8 8 83e-005

E.2.48.5. Figure for Additional Model Presented: Power, Unrestricted

Power Model with 0.95 Confidence Level

a>

CO
c
o

Q.

CO
CD

a:

c
m

CD

700

600

500

400

300

200

100

Power

S/IDLBMD

13:32 02/08 2010

50

100

150

200

250

dose

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.2.49. White et al., 1986: CH50

E.2.49.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential (M2)

5

0.002

389.664

1.957E+01

1.261E+01



exponential (M3)

5

0.002

389.664

1.957E+01

1.261E+01

power hit bound (d = 1)

exponential (M4)

4

0.001

390.632

1.411E+01

5.177E+00



exponential (M5)

4

0.001

390.632

1.411E+01

5.177E+00

power hit bound (d = 1)

Hill b

4

0.002

389.601

8.632E+00

1.498E+00

n lower bound hit (n = 1)

linear

5

<0.001

394.446

3.497E+01

2.568E+01



polynomial, 6-
degree

5

<0.001

394.446

3.497E+01

2.568E+01



power

5

<0.001

394.446

3.497E+01

2.568E+01

power bound hit (power = 1)

Hill, unrestricted0

3

0.071

381.520

1.481E-01

4.351E-03

unrestricted (n = 0.246)

power,
unrestricted

4

0.148

379.265

1.211E-01

1.225E-03

unrestricted (power = 0.227)

a Non-constant variance model selected (p = 0.0871)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.2.49.2. Output for Selected Model: Hill

White etal., 1986: CH50

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\l\Blood\71_White_198 6_CH50_Hill_l
Gnuplot Plotting File: C:\l\Blood\71_White_198 6_CH50

Mon Feb 08

[insert study notes]

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = Mean
Independent variable = Dose

Power parameter restricted to be greater than 1

This document is a draft for review purposes only and does not constitute Agency policy.

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_Hill_l.pit
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The variance is to be modeled as Var(i) = exp(lalpha + rho * ln(mean(i)))
Total number of dose groups = 7

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

lalpha
rho

intercept

5.60999
0
91
-74
0.118036
1.094

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -n

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

lalpha
rho

intercept

lalpha
1

-0. 99
0.27
0.23
-0.32

rho

-0. 99
1

-0.28
-0.24
0.33

intercept

0.27
-0.28
1

0.39
-0.78

v

0.23
-0.24
0.39
1

-0. 85

k

-0.32
0.33
-0.78
-0. 85
1

Parameter Estimates

Variable
lalpha
rho

intercept

k

Estimate

4 . 581
0.31293
74 . 6365
-66.2096
1

20.8286

Std. Err.

1.66273
0. 431616
6.33673
14.7876
NA

21.3237

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

1.32211
-0.533022
62.2167
-95.1928

-20.965

7 . 83989
1.15888
87.0562
-37.2264

62.6223

NA - Indicates that this parameter has hit a bound
implied by some ineguality constraint and thus
has no standard error.

Table of Data and Estimated Values of Interest

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0 8

91

74.6

14 .1

19

4

2 .39

1.094 8

54

71 . 3

8.49

19

3

-2 . 54

4.085 8

63

63. 8

11. 3

18

9

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-0.263

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0.589

48.72 8

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0. 636

90.56 8

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20.8

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-0.678

This document is a draft for review purposes only and does not constitute Agency policy.

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Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2 :	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model
A1

A2
A3

fitted
R

Log(likelihood)
-181.340979
-175.820265
-181. 238690
-189.800288
-212 . 367055

14

9
5
2

AIC

378 . 681959
379.640529
380.477380
389.600575
428.734109

Explanation of Tests

Test

1

Test

2

Test

3

Test

4

(Note:

Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1

Test 2
Test 3
Test 4

73.0936
11. 0414
10.8369
17 .1232

12

<.0001
0.0871
0.05471
0.001829

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is less than .1. You may want to consider a
different variance model

The p-value for Test 4 is less than .1. You may want to try a different
model

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	8.63239

This document is a draft for review purposes only and does not constitute Agency policy.

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E'.MDL =

1.49823

E.2.49.3. Figure for Selected Model: Hill

Hill Model with 0.95 Confidence Level

dose

13:35 02/08 2010

E.2.49.4. Output for Additional Model Presented: Hill, Unrestricted
White etal., 1986: CH50

pit
2010

[insert study notes]

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = Mean

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\l\Blood\7l_White_l986_CH50_Hill_U_l.(d)

Gnuplot Plotting File: C:\l\Blood\71_White_1986_CH50_Hill_U_l.

Mon Feb 08 13:35:57

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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Independent variable = Dose

Power parameter is not restricted

The variance is to be modeled as Var(i)

exp(lalpha + rho * ln(mean(i)

Total number of dose groups = 7

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

lalpha
rho

intercept

5.60999
0
91
-74
0.118036
1.094

Asymptotic Correlation Matrix of Parameter Estimates

lalpha
rho

intercept

lalpha
1
-1
0.16
0.19
-0.4
-0.014

rho
-1

1

-0.16
-0.19
0.4
0. 011

intercept

0.16
-0.16
1

0.15
-0.58
0. 015

v

0.19
-0.19
0.15
1

-0. 02
-0. 93

n

-0.4

0.4
-0.58
-0. 02
1

-0.35

k

-0.014
0. 011
0. 015
-0. 93
-0.35
1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
lalpha
rho

intercept

Estimate
6.54093
-0.245847
89.6302
-628.486
0.246409
493877

Std. Err.
2.08879
0.541645
5.59428
727.973
0. 058636
2 . 74838e + 006

Lower Conf. Limit
2 .44698
-1.30745
78 . 6656
-2055.29
0.131484
-4.89284e+006

Upper Conf. Limit

10.6349
0. 815757
100.595
798.315
0.361333
5. 88059e + 006

Table of Data and Estimated Values of Interest

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0

1.094
4 . 085
7 .14
26. 81
48.72
90.56

91

54
63
56
41
32
17

89.6

65.2

56.3
51. 7
38 . 3
30. 9
22 . 3

14 .1
8.49
11. 3
25.5
17
17
17

15.1

15. 8
16

16.2
16.8
17 . 3

18

0.256
-2 . 01
1.17
0.746
0. 453
0.175
-0.831

Model Descriptions for likelihoods calculated

This document is a draft for review purposes only and does not constitute Agency policy.

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Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2 :	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(1)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model
A1

A2
A3

fitted
R

Log(likelihood)
-181.340979
-175.820265
-181. 238690
-184.759769
-212 . 367055

Param's

14
9

AIC

378 . 681959
379.640529
380.477380
381.519538
428.734109

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

Test 3: Are variances adequately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1

Test 2
Test 3
Test 4

73.0936
11. 0414
10.8369
7 . 04216

12

<.0001
0.0871
0.05471
0.07057

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is less than .1. You may want to consider a
different variance model

The p-value for Test 4 is less than .1. You may want to try a different
model

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	0.148074

BMDL = 0.00435112

This document is a draft for review purposes only and does not constitute Agency policy.

E-253 DRAFT—DO NOT CITE OR QUOTE


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E.2.49.5. Figure for Additional Model Presented: Hill, Unrestricted

Hill Model with 0.95 Confidence Level

dose

13:35 02/08 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-254 DRAFT—DO NOT CITE OR QUOTE


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E.3. ADMINISTERED DOSE BMDS RESULTS

E.3.1. Amin et al., 2000: 0.25% Saccharin Consumed, Female

E.3.1.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

xV

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

linear b

1

0.358

179.702

8.816E+01

5.890E+01



polynomial, 2-
degree

1

0.358

179.702

8.816E+01

5.890E+01



power

1

0.358

179.702

8.816E+01

5.890E+01

power bound hit (power =1)

power,
unrestricted0

0

N/A

180.858

7.530E+01

2.537E+01

unrestricted (power = 0.605)

a Non-constant variance model selected (p = 0.0005)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.3.1.2. Output for Selected Model: Linear

Amin et al., 2000: 0.25% Saccharin Consumed, Female

Polynomial Model. (Version: 2.13; Date: 04/08/2008)

Input Data File: C:\1\l_Amin_2000_25_SC_Linear_l.(d)

Gnuplot Plotting File: C:\l\l_Amin_2 000_25_SC_Linear_l.plt

Tue_Feb 16~17:22:16 2010

The form of the response function is:

Y[dose] = beta_0 + beta_l*dose + beta_2*dose/N2 + ...

Dependent variable = Mean
Independent variable = Dose

Signs of the polynomial coefficients are not restricted

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)
Total number of dose groups = 3

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
lalpha =	5.29482

rho =	0

beta_0 =	30.8266

beta~l = -0.204134

This document is a draft for review purposes only and does not constitute Agency policy.

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Asymptotic Correlation Matrix of Parameter Estimates

lalpha
rho
beta_0
beta 1

lalpha
1

-0. 99
-0.016
0. 03

rho

-0. 99
1

0. 013
-0.026

beta_0

-0.016
0. 013
1

-0. 94

beta_l

0. 03
-0.026
-0. 94
1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
lalpha
rho
beta_0
beta 1

Estimate

-2.55843
2 .42056
30.3968
-0.196699

Std. Err.

1.66185
0.545617
4 . 03582
0.0443352

Lower Conf. Limit

-5.8156
1.35117
22.4868
-0.283594

Upper Conf. Limit

0.698746
3. 48995
38 . 3069
-0.109803

Table of Data and Estimated Values of Interest

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0 10
25 10
100 10

31. 7

24 . 6
10.7

30. 4
25.5
10.7

20.6
12
5.33

17 . 3
14
4 . 92

0.233
-0.2

-0.0204

Model Descriptions for likelihoods calculated

Model A1:	Yij

Var{e(ij ) }

Model A2:	Yij

Var{e(ij ) }

Mu(i) + e(ij ;
Sigma/N2

Mu(i) + e(ij ;

Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi

Var{e(i)}

Mu + e(i)
Sigma/N2

Likelihoods of Interest

Model
A1

A2
A3

fitted
R

Log(likelihood)
-92.841935
-85.255316
-85.429148
-85.851107
-98.136607

Param's

4
6

5
4
2

AIC

193.683870
182.510632
180.858295
179.702213

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

This document is a draft for review purposes only and does not constitute Agency policy.

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Test 3: Are variances adequately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.)

Tests of Interest

Test -2*log(Likelihood Ratio) Test df

p-value

Test 1

Test 2
Test 3
Test 4

25.7626
15.1732
0.347663
0. 843918

4
2
1
1

<.0001
0.0005072

0.5554
0.3583

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adequately describe the data

Benchmark Dose Computation

Specified effect

1

Risk Type

Estimated standard deviations from the control mean

Confidence level

0. 95

BMD

88 .1623

BMDL

58.9029

This document is a draft for review purposes only and does not constitute Agency policy.

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E.3.1.3. Figure for Selected Model: Linear

Linear Model with 0.95 Confidence Level

dose

17:22 02/16 2010

E.3.1.4. Output for Additional Model Presented: Power, Unrestricted
Amin et al., 2000: 0.25% Saccharin Consumed, Female

Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\1\l_Amin_2000_25_SC_Pwr_U_l.(d)

Gnuplot Plotting File: C:\l\l_Amin_2 000_25_SC_Pwr_U_l.plt

Tue Feb 16 17:22:17 2010

The form of the response function is:
Y[dose] = control + slope * doseApower

Dependent variable = Mean
Independent variable = Dose
The power is not restricted

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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Total number of dose groups = 3

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

lalpha
rho
control
slope
power

5.29482

0

31.6727
-0.567889
0.783745

Asymptotic Correlation Matrix of Parameter Estimates

lalpha
rho
control
slope
power

lalpha
1

-0. 99
0.34
-0.14
-0.061

rho

-0. 99
1

-0.42
0.15
0. 068

control

0.34
-0.42
1

-0. 67
-0.56

slope

-0.14
0.15
-0. 67
1

0. 99

power

-0.061
0. 068
-0.56
0. 99
1

Parameter Estimates

Variable
lalpha
rho
control
slope
power

Estimate
-2 .48291
2 . 38455
32 . 99
-1.36469
0.605364

Std. Err.

2.08669
0.692047
5.40754
2.01258
0.288476

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

-6.57274

1. 02817
22 .3914
-5.30927
0.0399625

1.60693
3.74094
43.5886
2.5799
1 . 17077

Table of Data and Estimated Values of Interest
Dose	N Obs Mean	Est Mean Obs Std Dev Est Std Dev Scaled Res.

0 10
25 10
100 10

31. 7

24 . 6
10.7

33

23. 4
10.8

20.6
12
5.33

18 . 7
12 . 4
4 . 94

-0.223
0.302
-0. 08

Warning: Likelihood for fitted model larger than the Likelihood for model A3.

Model Descriptions for likelihoods calculated

Model A1:	Yij

Var{e(ij ) }

Model A2:	Yij

Var{e(ij ) }

Mu(i) + e(ij ;
Sigma/N2

Mu(i) + e(ij ;

Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that

This document is a draft for review purposes only and does not constitute Agency policy.

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were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1 -92.841935	4	193.683870

A2 -85.255316	6	182.510632

A3 -85.429148	5	180.858295

fitted -85.429148	5	180.858295

R -98.136607	2	200.273213

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Test

2

Test

3

Test

4

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	25.7626	4	<.0001

Test 2	15.1732	2	0.0005072

Test 3	0.347663	1	0.5554

Test 4	-8.2423e-013	0	NA

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

NA - Degrees of freedom for Test 4 are less than or egual to 0. The Chi-Sguare
test for fit is not valid

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD = 7 5.2994

BMDL = 25.3717

This document is a draft for review purposes only and does not constitute Agency policy.

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E.3.1.5. Figure for Additional Model Presented: Power, Unrestricted

Power Model with 0.95 Confidence Level

dose

17:22 02/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.3.2. Amin et al., 2000: 0.25% Saccharin Preference Ratio, Female
E.3.2.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

linear b

1

0.002

228.094

1.264E+02

6.128E+01



polynomial, 2-
degree

1

0.002

228.094

1.264E+02

6.128E+01



power

1

0.002

228.094

1.264E+02

6.128E+01

power bound hit (power = 1)

a Non-constant variance model selected (p = 0.0135)
b Best-fitting model, BMDS output presented in this appendix

E.3.2.2. Output for Selected Model: Linear

Amin et al., 2000: 0.25% Saccharin Preference Ratio, Female

Polynomial Model. (Version: 2.13; Date: 04/08/2008)

Input Data File: C:\1\2_Amin_2000_25_SP_Linear_l.(d)

Gnuplot Plotting File: C:\l\2_Amin_2 000_25_SP_Linear_l.plt

Tue_Feb 16~17:22:44 2010

The form of the response function is:

Y[dose] = beta_0 + beta_l*dose + beta_2*dose/N2 + ...

Dependent variable = Mean
Independent variable = Dose

Signs of the polynomial coefficients are not restricted

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)
Total number of dose groups = 3

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
lalpha =	6.34368

rho =	0

beta_0 =	74.2008

beta 1 = -0.219781

Asymptotic Correlation Matrix of Parameter Estimates
lalpha	rho	beta 0	beta 1

lalpha	1	-1	0.2	-0.28

This document is a draft for review purposes only and does not constitute Agency policy.

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rho
beta_0
beta 1

-1

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-0.28

1

-0.19
0.28

-0.19
1

-0.76

0.28
-0.76
1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
lalpha
rho
beta_0
beta 1

Estimate
0.338774
1.43998
73.6633
-0.207175

Std. Err.
9.23768
2 . 21674
6.6623
0.101074

Lower Conf. Limit
-17.7667
-2.90476
60.6054
-0.405276

Upper Conf. Limit
18.4443
5.78472
86.7211
-0.00907442

Table of Data and Estimated Values of Interest

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0 10
25 10
100 10

82 .1
58 .1
54 . 9

73 . 7
68 . 5
52 . 9

13.3

33. 9
19.5

26.2

24 . 8
20.6

1. 02
-1. 32
0.295

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1	-108.574798	4	225.149597

A2	-104.269377	6	220.538754

A3	-105.147952	5	220.295903

fitted	-110.046917	4	228.093834

R	-112.382522	2	228.765045

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

Test 3: Are variances adequately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

This document is a draft for review purposes only and does not constitute Agency policy.

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Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1

Test 2
Test 3
Test 4

16.2263

1.75715
9.79793

8.61084

4
2
1
1

0.00273
0.0135
0.185
0.001747

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is less than .1. You may want to try a different
model

Benchmark Dose Computation

Specified effect

1

Risk Type

Estimated standard deviations from the control mean

Confidence level

0. 95

BMD

126.365

BMDL

61.2812

This document is a draft for review purposes only and does not constitute Agency policy.

E-264 DRAFT—DO NOT CITE OR QUOTE


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E.3.2.3. Figure for Selected Model: Linear

Linear Model with 0.95 Confidence Level

dose

17:22 02/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-265 DRAFT—DO NOT CITE OR QUOTE


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E.3.3. Amin et al., 2000: 0.50% Saccharin Consumed, Female
E.3.3.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

X2 P-
Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

linear b

1

0.031

159.737

9.874E+01

6.417E+01



polynomial, 2-
degree

1

0.031

159.737

9.874E+01

6.417E+01



power

1

0.031

159.737

9.874E+01

6.417E+01

power bound hit (power =1)

power,
unrestricted0

0

N/A

157.060

5.610E+01

6.781E+00

unrestricted (power = 0.325)

a Non-constant variance model selected (p = <0.0001)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.3.3.2. Output for Selected Model: Linear

Amin et al., 2000: 0.50% Saccharin Consumed, Female

Polynomial Model. (Version: 2.13; Date: 04/08/2008)

Input Data File: C:\1\3_Amin_2000_50_SC_Linear_l.(d)

Gnuplot Plotting File: C:\l\3_Amin_2 000_50_SC_Linear_l.plt

Tue_Feb 16~17:23:14 2010

The form of the response function is:

Y[dose] = beta_0 + beta_l*dose + beta_2*dose/N2 + ...

Dependent variable = Mean
Independent variable = Dose

Signs of the polynomial coefficients are not restricted

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)
Total number of dose groups = 3

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

lalpha =	4.68512

rho =	0

beta_0 =	19.3484

beta 1 = -0.158141

Asymptotic Correlation Matrix of Parameter Estimates

This document is a draft for review purposes only and does not constitute Agency policy.

E-266 DRAFT—DO NOT CITE OR QUOTE


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lalpha
rho
beta_0
beta 1

lalpha
1

-0. 97
0. 018
-0.0021

rho

-0. 97
1

-0.027
0. 014

beta_0

0. 018
-0.027
1

-0. 95

beta_l

-0.0021
0. 014
-0. 95
1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
lalpha
rho
beta_0
beta 1

Estimate

-0.997428
2 .13634
18 .1144
-0.135736

Std. Err.

0.992786
0. 404 989
3.10302
0.0331501

Lower Conf. Limit

-2.94325
1.34257
12.0326
-0.200709

Upper Conf. Limit

0. 948397
2.9301
24.1962
-0.0707631

Table of Data and Estimated Values of Interest

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0 10
25 10
100 10

22 . 4
11. 4
4 . 54

18 .1
14 . 7
4 . 54

16

7 . 66
3.33

13. 4

10.7
3. 06

1

-0.983
-0.00393

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1 -83.696404	4	175.392808

A2 -73.511830	6	159.023660

A3 -73.530233	5	157.060467

fitted -75.868688	4	159.737377

R -90.294746	2	184.589492

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

Test 3: Are variances adequately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

This document is a draft for review purposes only and does not constitute Agency policy.

E-267 DRAFT—DO NOT CITE OR QUOTE


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(Note:

When rho=0 the results of Test 3 and Test 2 will be the same.)

Tests of Interest

Test -2*log(Likelihood Ratio) Test df

p-value

Test 1

Test 2
Test 3
Test 4

0. 0368066

33.5658
20.3691

4.67691

4
2
1
1

<.0001
<.0001
0.8479
0.03057

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is less than .1. You may want to try a different
model

Benchmark Dose Computation

Specified effect

1

Risk Type

Estimated standard deviations from the control mean

Confidence level

0. 95

BMD

98.7409

BMDL

64.169

This document is a draft for review purposes only and does not constitute Agency policy.

E-268 DRAFT—DO NOT CITE OR QUOTE


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E.3.3.3. Figure for Selected Model: Linear

Linear Model with 0.95 Confidence Level

dose

17:23 02/16 2010

E.3.3.4. Output for Additional Model Presented: Power, Unrestricted
Amin et al., 2000: 0.50% Saccharin Consumed, Female

Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\1\3_Amin_2000_50_SC_Pwr_U_l.(d)

Gnuplot Plotting File: C:\l\3_Amin_2 000_50_SC_Pwr_U_l.plt

Tue Feb 16 17:23:15 2010

The form of the response function is:
Y[dose] = control + slope * doseApower

Dependent variable = Mean
Independent variable = Dose
The power is not restricted

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-269 DRAFT—DO NOT CITE OR QUOTE


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Total number of dose groups = 3

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

lalpha =	4.68512

rho =	0

control =	22.3564

slope =	-3.5587 4

power =	0.34 97 99

Asymptotic Correlation Matrix of Parameter Estimates

lalpha	rho	control	slope	power

lalpha 1	-0.96	0.34	-0.26	-0.15

rho -0.96	1	-0.47	0.3	0.15

control 0.34	-0.47	1	-0.73	-0.52

slope -0.26	0.3	-0.73	1	0.96

power -0.15	0.15	-0.52	0.96	1

Parameter Estimates

Variable
lalpha
rho
control
slope
power

Estimate
-0.708629
1.96142
22.6293
-4.03215
0.325414

Std. Err.
1.298
0.529653
4.48416
3.21302
0.138761

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

-3.25267

0.923323
13.8405
-10.3296
0.053447

1.83541

2.99953
31.4181
2 .26526
0.597381

Table of Data and Estimated Values of Interest
Dose	N Obs Mean	Est Mean Obs Std Dev Est Std Dev Scaled Res.

0 10	22.4	22.6	16	15	-0.0577

25 10	11.4	11.1	7.66	7.46	0.105

100 10	4.54	4.58	3.33	3.12	-0.0475

Warning: Likelihood for fitted model larger than the Likelihood for model A3.

Model Descriptions for likelihoods calculated

Model A1:	Yij	= Mu(i) + e(iji

Var{e(ij)} = Sigma/'2

Model A2:	Yij	= Mu(i) + e(ij|

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

This document is a draft for review purposes only and does not constitute Agency policy.

E-270 DRAFT—DO NOT CITE OR QUOTE


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Model R:	Yi = Mu + e(i

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model	Log(likelihood) # Param's	AIC

A1	-83.696404	4	175.392808

A2	-73.511830	6	159.023660

A3	-73.530233	5	157.060467

fitted	-73.530233	5	157.060467

R	-90.294746	2	184.589492

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Test

2

Test

3

Test

4

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	33.5658	4	<.0001

Test 2	20.3691	2	<.0001

Test 3	0.0368066	1	0.8479

Test 4	-2.84217e-014	0	NA

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

NA - Degrees of freedom for Test 4 are less than or egual to 0. The Chi-Sguare
test for fit is not valid

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD = 56.0 967

BMDL = 6.7 8112

This document is a draft for review purposes only and does not constitute Agency policy.

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E.3.3.5. Figure for Additional Model Presented: Power, Unrestricted

Power Model with 0.95 Confidence Level

dose

17:23 02/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-272 DRAFT—DO NOT CITE OR QUOTE


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E.3.4. Amin et al., 2000: 0.50% Saccharin Preference Ratio, Female
E.3.4.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

X2 P-
Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

linear b

1

0.088

234.936

8.278E+01

5.100E+01



polynomial, 2-
degree

1

0.088

234.936

8.278E+01

5.100E+01



power

1

0.088

234.936

8.278E+01

5.100E+01

power bound hit (power =1)

power,
unrestricted0

0

N/A

234.020

1.817E+01

1.000E-13

unrestricted (power = 0.232)

a Constant variance model selected (p = 0.5593)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.3.4.2. Output for Selected Model: Linear

Amin et al., 2000: 0.50% Saccharin Preference Ratio, Female

Polynomial Model. (Version: 2.13; Date: 04/08/2008)

Input Data File: C:\1\4_Amin_2000_50_SP_LinearCV_l.(d)

Gnuplot Plotting File: C:\l\4_Amin_2 000_50_SP_LinearCV_l.plt

Tue_Feb 16 17:23:43 2010

The form of the response function is:

Y[dose] = beta_0 + beta_l*dose + beta_2*dose/N2 + ...

Dependent variable = Mean
Independent variable = Dose
rho is set to 0

Signs of the polynomial coefficients are not restricted
A constant variance model is fit

Total number of dose groups = 3

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
alpha =	764.602

rho =	0 Specified

beta_0 =	64.1858

beta~l = -0.332668

This document is a draft for review purposes only and does not constitute Agency policy.

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Asymptotic Correlation Matrix of Parameter Estimates

alpha
beta_0
beta 1

The model parameter(s) -rho

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha
1

2e-008
1. 4e-009

beta_0

2e-008
1

-0.7

beta_l
1. 4e-009
-0.7
1

Parameter Estimates

Variable
alpha
beta_0
beta 1

Estimate
758.396
64 .1858
-0.332668

95.0% Wald Confidence Interval
Std. Err.	Lower Conf. Limit Upper Conf. Limit

195.817	374.602	1142.19

7.04184	50.3841	77.9876

0.118327	-0.564584	-0.100752

Table of Data and Estimated Values of Interest

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0 10
25 10
100 10

12. 7
44.5
33. 8

64 . 2
55. 9
30. 9

24 . 6
32 . 9
24 . 6

27 . 5
27 . 5
27 . 5

0. 981
-1. 31
0.327

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi

Var{e(i)}

Mu + e(i)
Sigma/N2

Likelihoods of Interest

Model
A1

A2
A3

fitted
R

Log(likelihood)

-113.009921
-112 .428886
-113.009921
-114.468091
-117.976057

Param's

4
6
4
3
2

AIC

234.019841
236.857773
234.019841
234.936183
239.952114

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

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Test 3: Are variances adequately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.)

Tests of Interest

Test -2*log(Likelihood Ratio) Test df

p-value

Test 1

Test 2
Test 3
Test 4

11.0943
1.16207
1.16207
2.91634

4
2
2
1

0.02552
0.5593
0.5593

0.08769

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than .1. A homogeneous variance
model appears to be appropriate here

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is less than .1. You may want to try a different
model

Benchmark Dose Computation

Specified effect

1

Risk Type

Estimated standard deviations from the control mean

Confidence level

0. 95

BMD

82 .7823

BMDL

50.9971

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E.3.4.3. Figure for Selected Model: Linear

Linear Model with 0.95 Confidence Level

dose

17:23 02/16 2010

E.3.4.4. Output for Additional Model Presented: Power, Unrestricted
Amin et al., 2000: 0.50% Saccharin Preference Ratio, Female

Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\1\4_Amin_2000_50_SP_PwrCV_U_l.(d)

Gnuplot Plotting File: C:\l\4_Amin_2 000_50_SP_PwrCV_U_l.plt

Tue Feb 16 17:23:44 2010

The form of the response function is:
Y[dose] = control + slope * doseApower

Dependent variable = Mean
Independent variable = Dose
rho is set to 0
The power is not restricted
A constant variance model is fit

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Total number of dose groups = 3

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

alpha
rho
control
slope
power

764.602

0

72.7273
-13.387
0.231973

Specified

Asymptotic Correlation Matrix of Parameter Estimates

alpha
control

The model parameter(s) -rho

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha
1

-1. 3e-008

control
-1.3e-008
1

slope
5.9e-009
-0.4

power
2.5e-009
-0.22

slope	5.9e-009	-0.4	1	0.97

power	2.5e-009	-0.22	0.97	1

Parameter Estimates

Variable
alpha
control
slope
power

Estimate
688.142
72.7273
-13.387
0.231973

Std. Err.

177.677
8.29543
15.9957
0.268067

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

339. 9

56.4686
-44.738
-0.293429

1036.38

88 . 986
17 . 9639
0.757376

Table of Data and Estimated Values of Interest
Dose	N Obs Mean	Est Mean Obs Std Dev Est Std Dev Scaled Res.

0	10 72.7	72.7	24.6	26.2	5.16e-008

25	10 44.5	44.5	32.9	26.2	-1.27e-008

100	10 33.8	33.8	24.6	26.2	-2e-008

Degrees	of freedom for	Test A3 vs fitted	<= 0

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

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Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1	-113.009921	4	234.019841

A2	-112.428886	6	236.857773

A3	-113.009921	4	234.019841

fitted	-113.009921	4	234.019841

R	-117.976057	2	239.952114

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Test

2

Test

3

Test

4

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	11.0943	4	0.02552

Test 2	1.16207	2	0.5593

Test 3	1.16207	2	0.5593

Test 4	0	0	NA

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than .1. A homogeneous variance
model appears to be appropriate here

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

NA - Degrees of freedom for Test 4 are less than or egual to 0. The Chi-Sguare
test for fit is not valid

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD = 18.1732

BMDL = le-013

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E.3.4.5. Figure for Additional Model Presented: Power, Unrestricted

Power Model with 0.95 Confidence Level

dose

17:23 02/16 2010

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E.3.5. Bell et al., 2007a: Balano-Preputial Separation, Postnatal Day 49
E.3.5.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

gamma

2

0.369

113.514

7.332E+00

4.687E+00

power bound hit (power = 1)

logistic

2

0.237

114.853

1.501E+01

1.137E+01

negative intercept (intercept =
-2.07)

log-logistica

2

0.456

112.952

5.209E+00

2.870E+00

slope bound hit (slope = 1)

log-probit

2

0.178

115.488

1.428E+01

9.138E+00

slope bound hit (slope =1)

multistage, 3-
degree

2

0.369

113.514

7.332E+00

4.687E+00

final B = 0

probit

2

0.248

114.723

1.399E+01

1.061E+01

negative intercept (intercept =
-1.23)

Weibull

2

0.369

113.514

7.332E+00

4.687E+00

power bound hit (power = 1)

gamma,
unrestricted

1

0.566

113.746

1.894E+00

7.609E-02

unrestricted (power = 0.506)

log-logistic,
unrestricted b

1

0.484

113.908

2.127E+00

1.363E-01

unrestricted (slope = 0.67)

log-probit,
unrestricted

1

0.439

114.021

2.179E+00

1.671E-01

unrestricted (slope = 0.389)

Weibull,
unrestricted

1

0.534

113.802

2.007E+00

1.075E-01

unrestricted (power = 0.574)

a Best-fitting model, BMDS output presented in this appendix
b Alternate model, BMDS output also presented in this appendix
E.3.5.2.

E.3.5.3. Output for Selected Model: Log-Logistic

Bell et al., 2007a: Balano-Preputial Separation, Postnatal Day 49

Logistic Model. (Version: 2.12; Date: 05/16/2008)

Input Data File: C:\1\5_Bell_2007_BPS_LogLogistic_l.(d)

Gnuplot Plotting File: C:\l\5_Bell_2007_BPS_LogLogistic_l.plt

Tue Feb 16 17724:10 2010

The form of the probability function is:

P[response] = background+(1-background)/[1+EXP(-intercept-slope*Log(dose))]

Dependent variable = DichEff
Independent variable = Dose

Slope parameter is restricted as slope >= 1

This document is a draft for review purposes only and does not constitute Agency policy.

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Total number of observations = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

User has chosen the log transformed model

Default Initial Parameter Values

background = 0.0333333
intercept =	-3.75371

slope =	1

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -slope

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

background intercept

background	1	-0.58

intercept	-0.58	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

background	0.0635251	*	*	*

intercept	-3.84765	*	*	*

slope	1	*	*	*

Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-53.7077	4

Fitted model -54.476 2	1.53661 2	0.4638

Reduced model -63.9797 1	20.544 3	0.0001309

AIC:	112.952

Goodness of Fit

Scaled

Dose	Est. Prob. Expected Observed	Size	Residual

0.0000
2.4000
8.0000
46.0000

0.0635
0.1091
0.2000
0.5273

1

15

906
3.274
6. 001
19

1. 000

5.	000

6.	000
15.000

30
30
30
30

-0.678
1. 011

-0.000
-0.300

Chi ^2

1. 57

d.f.

P-value

0.4559

Benchmark Dose Computation
Specified effect =	0.1

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Risk Type =	Extra risk

Confidence level =	0.95

BMD =	5.20918

BMDL =	2.86991

E.3.5.4. Figure for Selected Model: Log-Logistic

Log-Logistic Model with 0.95 Confidence Level

dose

17:24 02/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.3.5.5. Output for Additional Model Presented: Log-Logistic, Unrestricted
Bell et al., 2007a: Balano-Preputial Separation, Postnatal Day 49

Logistic Model. (Version: 2.12; Date: 05/16/2008)

Input Data File: C:\1\5_Bell_2007_BPS_LogLogistic_U_l.(d)

Gnuplot Plotting File: C:\l\5_Bell_2007_BPS_LogLogistic_U_l.plt

Tue Feb 16 17721:10 2010

The form of the probability function is:

P[response] = background+(1-background)/[1+EXP(-intercept-slope*Log(dose)

Dependent variable = DichEff
Independent variable = Dose
Slope parameter is not restricted

Total number of observations = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

User has chosen the log transformed model

Default Initial	Parameter Values

background =	0.0333333

intercept =	-2.54947

slope =	0.615936

Asymptotic Correlation Matrix of Parameter Estimates
background intercept	slope

background	1	-0.49	0.35

intercept	-0.49	1	-0.93

slope	0.35	-0.93	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

background	0.0354714	*	*	*

intercept	-2.70296	*	*	*

slope	0.670238	*	*	*

* - Indicates that this value is not calculated.

Analysis of Deviance Table

Model	Log(likelihood) # Param's Deviance Test d.f. P-value

Full model	-53.7077	4

This document is a draft for review purposes only and does not constitute Agency policy.

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Fitted model	-53.9541	3	0.492844	1	0.4827

Reduced model	-63.9797	1	20.544	3	0.0001309

AIC:	113.908

Goodness of Fit

Scaled

Dose	Est. Prob. Expected Observed	Size	Residual

0.0000

0.0355

1. 064

1. 000

30

-0.063

2.4000

0.1392

4.176

5. 000

30

0. 435

8.0000

0.2405

7 . 216

6. 000

30

-0.520

46.0000

0.4848

14.544

15.000

30

0.167

Chi^2 = 0.49	d.f. = 1	P-value = 0.4836

Benchmark Dose Computation
Specified effect =	0.1

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	2.12667

BMDL =	0.13633

This document is a draft for review purposes only and does not constitute Agency policy.

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l E.3.5.6. Figure for Additional Model Presented: Log-Logistic, Unrestricted

Log-Logistic Model with 0.95 Confidence Level

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.3.6. Cantoni et al., 1981: Urinary Coproporhyrins, 3 Months
E.3.6.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

X2 P-
Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

exponential (M2)

2

0.002

33.792

1.101E+02

5.318E+01



exponential (M3)

2

0.002

33.792

1.101E+02

5.318E+01

power hit bound (d = 1)

exponential
(M4)b

1

0.341

23.881

3.741E-01

1.253E-01



exponential (M5)

1

0.341

23.881

3.741E-01

1.253E-01

power hit bound (d = 1)

Hill

1

0.535

23.359

3.273E-01

error

n lower bound hit (n = 1)

linear

2

0.002

33.301

7.734E+01

1.975E+01



polynomial, 3-
degree

2

0.002

33.301

7.734E+01

1.975E+01



power

2

0.002

33.301

7.734E+01

1.975E+01

power bound hit (power =1)

power,
unrestricted0

1

0.665

23.162

4.637E-03

8.796E-08

unrestricted (power = 0.22)

Hill, unrestricted

0

N/A

24.974

7.264E-02

1.656E-04

unrestricted (n = 0.48)

a Non-constant variance model selected (p = 0.0039)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.3.6.2. Output for Selected Model: Exponential (M4)

Cantoni et al., 1981: Urinary Coproporhyrins, 3 Months

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\1\6_Cantoni_l981_UriCopro_Exp_l.(d)

Gnuplot Plotting File:

Tue Feb 16 17:24:39 2010

Figurel-UrinaryCoproporphyrin 3months

The form of the response function by Model:

Model 2
Model 3
Model 4
Model 5

Y[dose]
Y[dose]
Y[dose]
Y[dose]

exp{sign *	b * dose}

exp{sign *	(b * dosej^d}

[c-(c-l) *	exp{-b * dose}]

[c-(c-l) *	exp{-(b * dosej^d}

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;

This document is a draft for review purposes only and does not constitute Agency policy.

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sign = -1 for decreasing trend.

Model 2 is nested within Models 3 and 4.
Model 3 is nested within Model 5.

Model 4 is nested within Model 5.

Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)
Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values
Variable	Model 4

lnalpha	-1.50063

rho	2.6097 9

a	0.704303

b	0.0205927

c	4.47268

d	1

Parameter Estimates
Variable	Model 4

lnalpha	-1.74154

rho	2.66803

a	0.755982

b	0.3715

c	3.93845

d	1

Table of Stats From Input Data
Dose	N	Obs Mean	Obs Std Dev

0	4	0.7414	0.3475

1.43	4	1.807	0.8341

14.3	4	2.734	1.506

143	4	3	2.6

Estimated Values of Interest
Dose	Est Mean	Est Std	Scaled Residual

0	0.756	0.2882	-0.1014

1.43	1.671	0.8307	0.3265

14.3	2.966	1.786	-0.2607

143	2.977	1.794	0.02532

Other models for which likelihoods are calculated:

This document is a draft for review purposes only and does not constitute Agency policy.

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Model A1:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma^2

Model A2 :	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma(i)^2

Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= exp(lalpha + log(mean(i) ) 'k rho)

Model R:	Yij	= Mu + e(i)

Var{e(ij)}	= Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	DF	AIC

A1	-12.90166	5	35.80333

A2	-6.203643	8	28.40729

A3	-6.487204	6	24.97441

R	-15.73713	2	35.47427

4	-6.940389	5	23.88078

Additive constant for all log-likelihoods =	-14.7. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Test

1:

Does response

and/or variances differ among Dose levels? (A2 vs. R)

Test

2 :

Are Variances

Homogeneous? (A2 vs. A1)

Test

3:

Are variances

adequately modeled? (A2 vs. A3)

Test 6a: Does Model 4 fit the data? (A3 vs 4)

Test

Test 1
Test 2
Test 3
Test 6a

Tests of Interest

-2*log(Likelihood Ratio)

19. 07
13. 4
0.5671
0.9064

D. F.

p-value

0.004052
0.003854
0.7531
0.3411

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose
levels, it seems appropriate to model the data.

The p-value for Test 2 is less than .1. A non-homogeneous
variance model appears to be appropriate.

The p-value for Test 3 is greater than .1. The modeled
variance appears to be appropriate here.

The p-value for Test 6a is greater than .1. Model 4 seems
to adeguately describe the data.

Benchmark Dose Computations:

Specified Effect = 1.000000

Risk Type = Estimated standard deviations from control
Confidence Level = 0.950000

This document is a draft for review purposes only and does not constitute Agency policy.

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EMD =
E'.MDL =

0.374114
0.125287

E.3.6.3. Figure for Selected Model: Exponential (M4)

Exponential_beta Model 4 with 0.95 Confidence Level

a>

CO
c
o

Q.

CO
CD

a:

c
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5
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1

0
-1

Exponential

BplDLBMD

20

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dose

17:24 02/16 2010

E.3.6.4. Output for Additional Model Presented: Power, Unrestricted
Cantoni et al., 1981: Urinary Coproporhyrins, 3 Months

Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\1\6_Cantoni_l981_UriCopro_Pwr_U_l.(d)

Gnuplot Plotting File: C:\l\6_Cantoni_1981_UriCopro_Pwr_U_l.plt

Tue Feb 16 17:24:41 2010

Figurel-UrinaryCoproporphyrin_3months

The form of the response function is:
Y[dose] = control + slope * doseApower

140

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Dependent variable = Mean

Independent variable = Dose

The power is not restricted

The variance is to be modeled as Var(i)

exp(lalpha + log(mean(i))

rho)

Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

lalpha =	0.90039

rho =	0

control =	0.741372

slope =	1.00533

power =	0.163111

Asymptotic Correlation Matrix of Parameter Estimates

lalpha
rho
control
slope
power

lalpha
1

-0. 62
-0.53
-0.038
0. 027

rho

-0. 62
1

0.43
-0.24
-0.16

control

-0.53
0.43
1

-0.3

0.09

slope
-0.038
-0.24
-0.3
1

-0.72

power

0. 027
-0.16
0.09
-0.72
1

Parameter Estimates

Variable
lalpha
rho
control
slope
power

Estimate
-1.78404
2 . 6428
0.757242
0.927009
0.220276

Std. Err.

0. 61698
0.74449
0.139966
0.325923
0 . 0964599

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

-2.9933
1.18363
0. 482915
0.288212
0. 031218

-0.57478
4 .10197
1.03157
1. 56581
0.409334

Table of Data and Estimated Values of Interest

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0	4

1.43	4

14.3	4

143	4

0.741
1. 81

2 .73
3

0.757
1.76
2 .42
3.52

0.348
0. 834
1. 51
2 . 6

0.284
0. 865
1. 32
2 .16

-0.112
0.108
0.471
-0.483

Model Descriptions for likelihoods calculated

Model A1:	Yij	= Mu(i) + e(iji

Var{e(ij)} = Sigma/'2

Model A2:	Yij	= Mu(i) + e(ij|

Var{e(ij)} = Sigma(i)^2

This document is a draft for review purposes only and does not constitute Agency policy.

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Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1	-12.901663	5	35.803325

A2	-6.203643	8	28.407287

A3	-6.487204	6	24.974409

fitted	-6.580755	5	23.161510

R	-15.737135	2	35.474269

Explanation of Tests

Test 1:

Test

2

Test

3

Test

4

Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	19.067	6	0.004052

Test 2	13.396	3	0.003854

Test 3	0.567122	2	0.7531

Test 4	0.187101	1	0.6653

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adeguately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD = 0.00463746

BMDL = 8.7 9634e-008

This document is a draft for review purposes only and does not constitute Agency policy.

E-291 DRAFT—DO NOT CITE OR QUOTE


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E.3.6.5. Figure for Additional Model Presented: Power, Unrestricted

Power Model with 0.95 Confidence Level

dose

17:24 02/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.3.7. Cantoni et al., 1981: Urinary Porphyrins
E.3.7.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

exponential
(M2)b

2

<0.0001

58.753

1.223E+01

9.037E+00



exponential (M3)

2

<0.0001

58.753

1.223E+01

9.037E+00

power hit bound (d = 1)

exponential (M4)

1

<0.0001

63.138

2.227E-01

1.137E-01



exponential (M5)

1

<0.0001

63.138

2.227E-01

1.137E-01

power hit bound (d = 1)

Hill

0

N/A

62.356

9.363E+00

4.664E+00



linear

2

<0.0001

62.487

7.732E-01

2.816E-01



polynomial, 3-
degree

1

<0.0001

10.000

error

error



power

2

<0.0001

62.487

7.732E-01

2.816E-01

power bound hit (power =1)

power,
unrestricted

1

<0.0001

59.914

1.025E-01

2.389E-02

unrestricted (power = 0.746)

a Non-constant variance model selected (p = <0.0001)
b Best-fitting model, BMDS output presented in this appendix

E.3.7.2. Output for Selected Model: Exponential (M2)

Cantoni et al., 1981: Urinary Porphyrins

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\1\7_Cantoni_l981_UriPor_Exp_l.(d)

Gnuplot Plotting File:

Tue Feb 16 17:25:14 2010

Table 1, dose converted to ng per kg per day

The form of the response function by Model:

Model 2
Model 3
Model 4
Model 5

Y[dose]
Y[dose]
Y[dose]
Y[dose]

exp{sign *	b * dose}

exp{sign *	(b * dosej^d}

[c-(c-l) *	exp{-b * dose}]

[c-(c-l) *	exp{-(b * dosej^d}

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;
sign = -1 for decreasing trend.

Model 2 is nested within Models 3 and 4.
Model 3 is nested within Model 5.

Model 4 is nested within Model 5.

This document is a draft for review purposes only and does not constitute Agency policy.

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Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)
Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values
Variable	Model 2

lnalpha	-3.57509

rho	2.23456

a	3.83141

b	0.0277822

c	0

d	1

Parameter Estimates
Variable	Model 2

lnalpha	-1.55886

rho	1.77962

a	4.17268

b	0.0270415

c	0

d	1

Table of Stats From Input	Data

Dose	N	Obs Mean	Obs Std Dev

0	4	2.27	0.49

1.43	4	5.55	0.85

14.3	3	7.62	1.79

143	3	196.9	63.14

Estimated Values of	Interest
Dose Est Mean Est Std Scaled Residual

0	4.173	1.635	-2.327

1.43	4.337	1.692	1.433

14.3	6.143	2.307	1.109

143	199.4	51.04	-0.08645

Other models for which likelihoods are calculated:

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

This document is a draft for review purposes only and does not constitute Agency policy.

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Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= exp(lalpha + log(mean(i) ) 'k rho)

Model R:	Yij	= Mu + e(i)

Var{e(ij)}	= Sigma^2

Likelihoods of Interest
Model	Log(likelihood)	DF	AIC

A1	-51.42175	5	112.8435

A2	-15.31211	8	46.62422

A3	-15.66963	6	43.33925

R	-68.75058	2	141.5012

2	-25.37651	4	58.75302

Additive constant for all log-likelihoods =	-12.87. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Test

1:

Test

2 :

Test

3:

Test

4 :

Does response and/or variances differ among Dose levels? (A2 vs. R)

Are Variances Homogeneous? (A2 vs. A1)

Are variances adeguately modeled? (A2 vs. A3)

Does Model 2 fit the data? (A3 vs. 2)

Test 1
Test 2
Test 3
Test 4

Tests of Interest

-2*log(Likelihood Ratio)

106. 9
12. 22
0.715
19.41

p-value

0.0001
0.0001
0.6 9 9 4
0.0001

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose
levels, it seems appropriate to model the data.

The p-value for Test 2 is less than .1. A non-homogeneous
variance model appears to be appropriate.

The p-value for Test 3 is greater than .1. The modeled
variance appears to be appropriate here.

The p-value for Test 4 is less than .1. Model 2 may not adeguately
describe the data; you may want to consider another model.

Benchmark Dose Computations:

Specified Effect = 1.000000

Risk Type = Estimated standard deviations from control
Confidence Level = 0.950000

BMD =	12.227 2

BMDL =	9.03732

This document is a draft for review purposes only and does not constitute Agency policy.

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l E.3.7.3. Figure for Selected Model: Exponential (M2)

Exponential_beta Model 2 with 0.95 Confidence Level

dose

2	17:25 02/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.3.8. Crofton et al., 2005: Serum, T4

E.3.8.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

r p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

exponential (M2)

8

<0.0001

518.241

2.136E+03

1.157E+03



exponential (M3)

8

<0.0001

518.241

2.136E+03

1.157E+03

power hit bound (d = 1)

exponential
(M4)b

7

0.957

476.204

5.633E+01

3.006E+01



exponential (M5)

7

0.957

476.204

5.633E+01

3.006E+01

power hit bound (d = 1)

Hill

6

0.973

477.434

5.564E+01

2.590E+01



linear

8

<0.0001

523.518

4.246E+03

3.086E+03



polynomial, 8-
degree

8

<0.0001

523.518

4.246E+03

3.086E+03



power

8

<0.0001

523.518

4.246E+03

3.086E+03

power bound hit (power =1)

power,
unrestricted

7

0.030

489.670

2.179E+01

2.271E+00

unrestricted (power = 0.217)

a Constant variance model selected (p = 0.7647)
b Best-fitting model, BMDS output presented in this appendix

E.3.8.2. Output for Selected Model: Exponential (M4)

Crofton et al., 2005: Serum, T4

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\1\8_Crofton_2005_T4_ExpCV_l.(d)

Gnuplot Plotting File:

Tue Feb 16 17:26:01 2010

The form of the response function by Model:

Model 2
Model 3
Model 4
Model 5

Y[dose]
Y[dose]
Y[dose]
Y[dose]

exp{sign *	b * dose}

exp{sign *	(b * dosej^d}

[c-(c-l) *	exp{-b * dose}]

[c-(c-l) *	exp{-(b * dosej^d}

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;
sign = -1 for decreasing trend.

Model 2 is nested within Models 3 and 4.
Model 3 is nested within Model 5.

Model 4 is nested within Model 5.

This document is a draft for review purposes only and does not constitute Agency policy.

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Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))
rho is set to 0.

A constant variance model is fit.

Total number of dose groups = 10

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values

Variable

Model 4

lnalpha

rho(S)

5.47437

0

104.999
0.000371694
0.445764

1

(S)

Specified

Parameter Estimates

Variable

lnalpha
rho

Model 4

5.50283

0

99.776
0.00728387
0.533516

1

Table of Stats From Input Data

Dose	N	Obs Mean	Obs Std Dev

0	14	100	15.44

0.1 6	96.27	14.98

3	12	98.57	18.11

10 6	99.76	19.04

30 6	93.32	12.11

100 6	70.94	12.74

300 6	62.52	14.75

1000 6	52.68	22.73

3000 6	54.66	19.71

le+004 4	49.15	11.15

Estimated Values of Interest

Dose Est	Mean	Est Std	Scaled Residual

0

99

78

15. 66

0.05325

0.1

99

74

15. 66

-0.5434

3

98

77

15. 66

-0. 04357

10

96

51

15. 66

0.5085

30

90

64

15. 66

0.4195

This document is a draft for review purposes only and does not constitute Agency policy.

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100	75.7	15.66	-0.744

300	58.47	15.66	0.6334

1000	53.26	15.66	-0.09133

3000	53.23	15.66	0.2237

le+004	53.23	15.66	-0.5218

Other models for which	likelihoods are calculated:

Model A1:	Yij	=	Mu(i) + e(1j)

Var{e(ij)}	=	Sigma^2

Model A2:	Yij	=	Mu(i) + e(1j)

Var{e(ij)}	=	Sigma(i)^2

Model A3:	Yij	=	Mu(i) + e(1j)

Var{e(ij)}	=	exp(lalpha + log(mean(i) ) 'k rho)

Model R:	Yij	=	Mu + e(1)

Var{e(ij)}	=	Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	DF	AIC

A1	-233.0774	11	488.1549

A2	-230.2028	20	500.4056

A3	-233.0774	11	488.1549

R	-268.4038	2	540.8076

4	-234.1019	4	476.2038

Additive constant for all log-likelihoods =	-66.16. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Test 1: Does response and/or variances differ among Dose levels? (A2 vs. R)

Test 2: Are Variances Homogeneous? (A2 vs. A1)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 6a: Does Model 4 fit the data? (A3 vs 4)

Test

Test 1
Test 2
Test 3
Test 6a

Tests of Interest

-2*log(Likelihood Ratio)

76.4
5.749
5.749
2.049

D. F.

18
9
9
7

p-value

< 0.0001
0.7647
0.7647
0.9571

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose
levels, it seems appropriate to model the data.

The p-value for Test 2 is greater than .1. A homogeneous
variance model appears to be appropriate here.

The p-value for Test 3 is greater than .1. The modeled
variance appears to be appropriate here.

The p-value for Test 6a is greater than .1. Model 4 seems
to adeguately describe the data.

This document is a draft for review purposes only and does not constitute Agency policy.

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Benchmark Dose Computations:

Specified Effect = 1.000000

Risk Type = Estimated standard deviations from control
Confidence Level = 0.950000

BMD =	56.3321

BMDL =	30.0635

E.3.8.3. Figure for Selected Model: Exponential (M4)

Exponential_beta Model 4 with 0.95 Confidence Level

a>

CO
c
o

Q.

CO
CD

a:

c
m

CD

120

100

80

60

40

20

Exponential

BMDLBMD

2000

4000

6000

8000

10000

dose

17:26 02/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.3.9. Franc et al., 2001: S-D Rats, Relative Liver Weight
E.3.9.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

X2 P-
Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Hill

1

0.797

236.371

1.826E+01

5.463E+00

n lower bound hit (n = 1)

exponential (M2)

2

0.935

234.440

2.262E+01

1.757E+01



exponential (M3)

2

0.935

234.440

2.262E+01

1.757E+01

power hit bound (d = 1)

exponential (M4)

1

0.797

236.371

1.827E+01

6.112E+00



exponential (M5)

1

0.797

236.371

1.827E+01

6.112E+00

power hit bound (d = 1)

linear

2

0.967

234.372

1.861E+01

1.339E+01



polynomial, 3-
degree

2

0.967

234.372

1.861E+01

1.339E+01



power b

2

0.967

234.372

1.861E+01

1.339E+01

power bound hit (power =1)

Hill, unrestricted

0

N/A

238.366

1.726E+01

2.022E+00

unrestricted (n = 0.965)

power,
unrestricted0

1

0.805

236.365

1.725E+01

2.003E+00

unrestricted (power = 0.962)

a Constant variance model selected (p = 0.107)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.3.9.2. Output for Selected Model: Power
Franc et al., 2001: S-D Rats, Relative Liver Weight

Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\1\88_Franc_2001_SD_RelLivWt_PowerCV_l.(d)

Gnuplot Plotting File: C:\l\88_Franc_2001_SD_RelLivWt_PowerCV_l.plt

Fri Apr 16 16:28:45 2010

Figure 5, SD rats, relative liver weight

The form of the response function is:

Y[dose] = control + slope * doseApower

Dependent variable = Mean
Independent variable = Dose
rho is set to 0

This document is a draft for review purposes only and does not constitute Agency policy.

E-301 DRAFT—DO NOT CITE OR QUOTE


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The power is restricted to be greater than or equal to 1
A constant variance model is fit

Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial
alpha =
rho =
control =
slope =
power =

Parameter Values

527 .447

0 Specified
100
1.15946
0. 839423

Asymptotic Correlation Matrix of Parameter Estimates

alpha
control
slope

The model parameter(s) -rho -power

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha
1

1. 3e-012
-6.2e-013

control
1.3e-012
1

-0. 67

slope
). 2e-013
-0. 67
1

Parameter Estimates

Variable
alpha
control
slope
power

Estimate

462.485
101.047
0.542984
1

Std. Err.

115.621
5.10511
0. 0973507
NA

NA - Indicates that this parameter has hit a bound
implied by some inequality constraint and thus
has no standard error.

Table of Data and Estimated Values of Interest

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

235.872
91. 0415
0.352181

68 9.0 9 9
111.053
0.733788

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0
10
30
100

100
108
117
155

101
106
117
155

14

16. 9
25. 9
30. 9

21. 5

21. 5
21. 5
21. 5

-0.138
0.208
-0.0702
0.000298

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

This document is a draft for review purposes only and does not constitute Agency policy.

E-302 DRAFT—DO NOT CITE OR QUOTE


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Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model
A1

A2
A3

fitted
R

Log(likelihood)
-114 .152281
-111.103649
-114.152281
-114.185827
-125.052064

Param's

5
8
5
3
2

AIC

238.304562
238.207299
238.304562
234.371654
254.104127

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.)

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1

Test 2
Test 3
Test 4

27 .8968

6. 09726
6.09726
0.0670927

C. 0001
0.107
0.107
0. 967

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than .1. A homogeneous variance
model appears to be appropriate here

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adeguately describe the data

Benchmark Dose Computation
Specified effect =	0.1

Risk Type	=	Relative risk

Confidence level =	0.95

BMD = 18.6096

BMDL = 13.387 9

This document is a draft for review purposes only and does not constitute Agency policy.

E-303 DRAFT—DO NOT CITE OR QUOTE


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E.3.9.3. Figure for Selected Model: Power

Power Model with 0.95 Confidence Level

dose

16:28 04/16 2010

E.3.9.4. Output for Additional Model Presented: Power, Unrestricted
Franc et al., 2001: S-D Rats, Relative Liver Weight

Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\1\88_Franc_2001_SD_RelLivWt_PowerCV_U_l.(d)

Gnuplot Plotting File: C:\l\88_Franc_2001_SD_RelLivWt_PowerCV_U_l.plt

Fri Apr 16 16:28:46 2010

Figure 5, SD rats, relative liver weight

The form of the response function is:
Y[dose] = control + slope * doseApower

Dependent variable = Mean
Independent variable = Dose
rho is set to 0
The power is not restricted
A constant variance model is fit

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-304 DRAFT—DO NOT CITE OR QUOTE


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Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

alpha
rho
control
slope
power

527 .447

0

100
1.15946
0. 839423

Specified

Asymptotic Correlation Matrix of Parameter Estimates

alpha
control

The model parameter(s) -rho

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha
1

le-009

control
le-009
1

slope
). 2e-010
-0.74

power
4 . 7e-010
0.71

slope -6.2e-010	-0.74	1	-1

power	4.7e-010	0.71	-1	1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
alpha
control
slope
power

Estimate
462.394
100.636
0. 650456
0.961853

Std. Err.
115.598
7 .29156
1.43713
0. 465182

Lower Conf. Limit

235.825
86.3448
-2 .16627
0. 0501134

Upper Conf. Limit

688.963
114.927
3.46718
1.87359

Table of Data and Estimated Values of Interest

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0	8	100	101	14	21.5	-0.0836

10	8	108	107	16.9	21.5	0.192

30	8	117	118	25.9	21.5	-0.128

100	8	155	155	30.9	21.5	0.0192

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2
Model A3 uses any fixed variance parameters that
were specified by the user

This document is a draft for review purposes only and does not constitute Agency policy.

E-305 DRAFT—DO NOT CITE OR QUOTE


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Model R:	Yi

Var{e(i)}

Mu + e(i
Sigma/N2

Likelihoods of Interest

Model
A1

A2
A3

fitted
R

Log(likelihood)
-114 .152281
-111.103649
-114.152281
-114.182670
-125.052064

Param's

5
8
5
4
2

AIC

238.304562
238.207299
238.304562
236.365340
254.104127

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1

Test 2
Test 3
Test 4

27 .8968

6. 09726
6.09726
0.0607785

<.0001
0.107
0.107
0.8053

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than .1. A homogeneous variance
model appears to be appropriate here

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adeguately describe the data

Benchmark Dose Computation
Specified effect =	0.1

Risk Type	=	Relative risk

Confidence level =	0.95

BMD = 17.24 69

BMDL = 2.00336

This document is a draft for review purposes only and does not constitute Agency policy.

E-306 DRAFT—DO NOT CITE OR QUOTE


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E.3.9.5. Figure for Additional Model Presented: Power, Unrestricted

Power Model with 0.95 Confidence Level

dose

16:28 04/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-307 DRAFT—DO NOT CITE OR QUOTE


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E.3.10. Franc et al., 2001: L-E Rats, Relative Liver Weight
E.3.10.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

X2 P-
Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

exponential (M2)

2

0.245

210.148

5.143E+01

3.188E+01



exponential (M3)

2

0.245

210.148

5.143E+01

3.188E+01

power hit bound (d = 1)

exponential (M4)

1

0.607

209.599

1.476E+01

3.702E+00



exponential (M5)

1

0.607

209.599

1.476E+01

3.702E+00

power hit bound (d = 1)

Hill b

1

0.703

209.480

1.321E+01

1.591E+00

n lower bound hit (n = 1)

linear

2

0.273

209.933

4.753E+01

2.788E+01



polynomial, 3-
degree

1

<0.0001

10.000

1.505E+01

error



power

2

0.273

209.933

4.753E+01

2.788E+01

power bound hit (power =1)

Hill, unrestricted

C

0

N/A

211.341

1.163E+01

9.756E-01

unrestricted (n = 0.418)

power,
unrestricted

1

0.940

209.340

1.155E+01

1.513E-02

unrestricted (power =0.394)

a Non-constant variance model selected (p = 0.0632)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.3.10.2. Output for Selected Model: Hill

Franc et al., 2001: L-E Rats, Relative Liver Weight

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\1\89_Franc_2001_LE_RelLivWt_Hill_l.(d)

Gnuplot Plotting File: C:\l\8 9_Franc_2001_LE_RelLivWt_Hill_l.plt

Fri Apr 16 16:29:20 2010

Figure 5, L-E rats, relative liver weight

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = Mean
Independent variable = Dose

Power parameter restricted to be greater than 1

This document is a draft for review purposes only and does not constitute Agency policy.

E-308 DRAFT—DO NOT CITE OR QUOTE


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The variance is to be modeled as Var(i) = exp(lalpha + rho * ln(mean(i)))
Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

lalpha
rho

intercept

5. 41581

0

100
22 . 225
0.329526
40.8403

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -n

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

lalpha
rho

intercept

lalpha
1
-1

-0.18
0.38
0.2

rho
-1

1

0.17
-0.38
-0.2

intercept

-0.18
0.17
1

-0.13
0.39

v

0.38
-0.38
-0.13
1

0 .77

k

0.2
-0.2

0.39
0 .77
1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
lalpha
rho

intercept

k

Estimate
-15.3958
4.38043
99.5667
28 . 8965
1

25.1273

Std. Err.

17 . 0376
3. 61867
3.7178
12.6477
NA
30.138

Lower Conf. Limit
-48.7889
-2 .71204
92 .28
4 .10739

-33.9421

Upper Conf. Limit

17 . 9973
11.4729
106.853
53.6856

84.1966

NA - Indicates that this parameter has hit a bound
implied by some ineguality constraint and thus
has no standard error.

Table of Data and Estimated Values of Interest

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0	8	100	99.6	10	10.8	0.114

10	8	106	108	17.9	12.8	-0.329

30	8	117	115	8.97	14.9	0.288

100	8	122	123	19.9	17	-0.0723

Model Descriptions for likelihoods calculated

This document is a draft for review purposes only and does not constitute Agency policy.

E-309 DRAFT—DO NOT CITE OR QUOTE


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Model A1:	Yij	= Mu(i) + e(ij

Var{e(ij)}	= Sigma^2

Model A2 :	Yij	= Mu(i) + e(ij

Var{e(ij)}	= Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model
A1
A2
A3

fitted
R

Log(likelihood)
-100.516456
-96.870820
-99.666984
-99.739888
-105.717087

Param1s
5

AIC
211.032912
209.741641
211.333969
209.479776
215.434174

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.)

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1
Test 2
Test 3
Test 4

17.6925
7.29127
5.59233
0.145807

0.007048
0.06317
0.06104
0.7026

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is less than .1. You may want to consider a
different variance model

The p-value for Test 4 is greater than .1. The model chosen seems
to adeguately describe the data

Benchmark Dose Computation
Specified effect =	0.1

Risk Type	=	Relative risk

Confidence level =	0.95

BMD =	13.2 0 94

BMDL =	1.59127

This document is a draft for review purposes only and does not constitute Agency policy.

E-310 DRAFT—DO NOT CITE OR QUOTE


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E.3.10.3. Figure for Selected Model: Hill

Hill Model with 0.95 Confidence Level

dose

16:29 04/16 2010

E.3.10.4. Output for Additional Model Presented: Hill, Unrestricted
Franc et al., 2001: L-E Rats, Relative Liver Weight

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\1\89_Franc_2001_LE_RelLivWt_Hill_U_l.(d)

Gnuplot Plotting File: C:\l\8 9_Franc_2 001_LE_RelLivWt_Hill_U_l.plt

Fri Apr 16 16:29:27 2010

Figure 5, L-E rats, relative liver weight

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = Mean
Independent variable = Dose
Power parameter is not restricted

The variance is to be modeled as Var(i) = exp(lalpha + rho * In(mean(i)))

Total number of dose groups = 4

This document is a draft for review purposes only and does not constitute Agency policy.

E-311 DRAFT—DO NOT CITE OR QUOTE


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Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

lalpha =	5.41581

rho =	0

intercept =	100

v =	22.225

n =	0.329526

k =	40.8403

Asymptotic Correlation Matrix of Parameter Estimates

lalpha rho	intercept v n k

lalpha 1 -1	-0.21 -0.099 0.23 -0.13

rho -1 1	0.21 0.099 -0.23 0.13

intercept -0.21 0.21	1 0.023 0.14 0.011

v -0.099 0.099	0.023 1 -0.84 1

n 0.23 -0.23	0.14 -0.84 1 -0.88

k -0.13 0.13	0.011 1 -0.88 1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
lalpha
rho

intercept

Estimate

-18 . 8355
5.1098
99.526
286.422
0. 418159
32981.9

Std. Err.

18 . 0637
3.83743
3.53402
4487.2
0. 457476
1.52481e+006

Lower Conf. Limit

-54.2397
-2 .41144
92.5994
-8508.33
-0.478477
-2.95559e+006

Upper Conf. Limit
16.5688
12.631
106.453
9081.17
1.31479
3.02155e+006

Table of Data and Estimated Values of Interest

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0
10
30
100

100
106
117
122

99.5

109
114
123

10
17 . 9
8 . 97
19. 9

10.3
13
14 . 6
17 . 7

0.13

-0.563
0.529
-0.0942

Degrees of freedom for Test A3 vs fitted

0

Model Descriptions for likelihoods calculated

Model A1:	Yij	= Mu(i) + e(iji

Var{e(ij)} = Sigma/'2

Model A2:	Yij	= Mu(i) + e(ij|

Var{e(ij)} = Sigma(i)^2

This document is a draft for review purposes only and does not constitute Agency policy.

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Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1	-100.516456	5	211.032912

A2 -96.870820	8	209.741641

A3 -99.666984	6	211.333969

fitted -99.670736	6	211.341472

R	-105.717087	2	215.434174

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1
Test 2
Test 3
Test 4

17.6925
7.29127
5.59233
0.00750301

0.007048
0.06317
0.06104
NA

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is less than .1. You may want to consider a
different variance model

NA - Degrees of freedom for Test 4 are less than or egual to 0. The Chi-Sguare
test for fit is not valid

Benchmark Dose Computation
Specified effect =	0.1

Risk Type	=	Relative risk

Confidence level =	0.95

BMD =	11.6342

BMDL =	0.975601

This document is a draft for review purposes only and does not constitute Agency policy.

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E.3.10.5. Figure for Additional Model Presented: Hill, Unrestricted

Hill Model with 0.95 Confidence Level

dose

16:29 04/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-314 DRAFT—DO NOT CITE OR QUOTE


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E.3.11. Franc et al., 2001: S-D Rats, Relative Thymus Weight
E.3.11.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

exponential (M2)

2

0.551

285.890

6.730E+00

3.627E+00



exponential (M3)

1

<0.0001

303.995

3.858E+02

6.615E-01



exponential
(M4)b

1

0.972

286.698

3.559E+00

1.714E+00



exponential (M5)

0

N/A

288.696

3.796E+00

1.714E+00



Hill

0

N/A

288.696

4.299E+00

9.311E-01



linear

2

0.252

287.456

1.330E+01

1.062E+01



polynomial, 3-
degree0

2

0.252

287.456

1.330E+01

1.062E+01



power

2

0.252

287.456

1.330E+01

1.062E+01

power bound hit (power =1)

power,
unrestricted

1

0.510

287.131

5.049E-01

4.411E-04

unrestricted (power = 0.388)

a Non-constant variance model selected (p = 0.0320)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.3.11.2. Output for Selected Model: Exponential (M4)

Franc et al., 2001: S-D Rats, Relative Thymus Weight

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\1\91_Franc_2001_SD_RelThyWt_Exp_l.(d)

Gnuplot Plotting File:

Fri Apr 16 16:30:07 2010

Figure 5, SD rats, relative thymus weight

The form of the response function by Model:

Model 2
Model 3
Model 4
Model 5

Y[dose]
Y[dose]
Y[dose]
Y[dose]

exp{sign *	b * dose}

exp{sign *	(b * dosej^d}

[c-(c-l) *	exp{-b * dose}]

[c-(c-l) *	exp{-(b * dosej^d}

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;
sign = -1 for decreasing trend.

Model 2 is nested within Models 3 and 4.

This document is a draft for review purposes only and does not constitute Agency policy.

E-315 DRAFT—DO NOT CITE OR QUOTE


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Model 3 is nested within Model 5.
Model 4 is nested within Model 5.

Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)
Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values
Variable	Model 4

lnalpha	3.35464

rho	1.08199

a	105

b	0.0424361

c	0.206726

d	1

Parameter Estimates
Variable	Model 4

lnalpha	2.54324

rho	1.25901

a	108.904

b	0.0379343

c	0.208146

d	1

Table of Stats From Input	Data

Dose	N	Obs Mean	Obs Std Dev

0	8	100	83.2

10	8	91.17	47.97

30	8	51.41	43.48

100	8	22.79	29.98

Estimated Values of	Interest
Dose Est Mean Est Std Scaled Residual

0	108.9	68.33	-0.3686

10	81.68	57.01	0.4706

30	50.3	42.02	0.0748

100	24.61	26.79	-0.192

Other models for which likelihoods are calculated:

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

This document is a draft for review purposes only and does not constitute Agency policy.

E-316 DRAFT—DO NOT CITE OR QUOTE


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Model A2 :	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma(i)^2

Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= exp(lalpha + log(mean(i) ) 'k rho)

Model R:	Yij	= Mu + e(i)

Var{e(ij)}	= Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	DF	AIC

A1	-141.9834	5	293.9669

A2	-137.5818	8	291.1637

A3	-138.3482	6	288.6964

R	-146.9973	2	297.9946

4	-138.3488	5	286.6976

Additive constant for all log-likelihoods =	-29.41. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Test 1: Does response and/or variances differ among Dose levels? (A2 vs. R)

Test 2: Are Variances Homogeneous? (A2 vs. A1)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 6a: Does Model 4 fit the data? (A3 vs 4)

Test

Test 1
Test 2
Test 3
Test 6a

Tests of Interest

-2*log(Likelihood Ratio)

18 . 83
8 .803
1. 533
0.001216

p-value

0.004459
0.03203
0.4647
0.9722

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose
levels, it seems appropriate to model the data.

The p-value for Test 2 is less than .1. A non-homogeneous
variance model appears to be appropriate.

The p-value for Test 3 is greater than .1. The modeled
variance appears to be appropriate here.

The p-value for Test 6a is greater than .1. Model 4 seems
to adeguately describe the data.

Benchmark Dose Computations:

Specified Effect = 0.100000

Risk Type = Relative deviation
Confidence Level = 0.950000

BMD =	3.55883

BMDL =	1.71399

This document is a draft for review purposes only and does not constitute Agency policy.

E-317 DRAFT—DO NOT CITE OR QUOTE


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E.3.11.3. Figure for Selected Model: Exponential (M4)

Exponential_beta Model 4 with 0.95 Confidence Level

150


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Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial	Parameter Values

lalpha	=	8.007 5

rho	=	0

beta_0	=	100

beta~l	=	-0.352259

beta_2	=	-0.0585481

beta 3	=	0

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -beta 2 -beta 3

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

lalpha	rho	beta 0	beta 1

lalpha 1	-0.99	0.031	-0.016

rho -0.99	1	-0.034	0.022

beta_0 0.031	-0.034	1	-0.84

beta 1 -0.016	0.022	-0.84	1

Parameter Estimates

Variable
lalpha
rho

beta_0
beta_l
beta_2
beta 3

Estimate

2.92328
1.18295
89.841
-0.675682
0
0

Std. Err.
1.7394
0. 423359
13.7418
0.175538
NA
NA

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

-0.485884
0.353177
62.9076
-1.01973

6.33243
2.01271
116.774
-0.331634

NA - Indicates that this parameter has hit a bound
implied by some ineguality constraint and thus
has no standard error.

Table of Data and Estimated Values of Interest

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0	8	100	89.8	83.2	61.7	0.466

10	8	91.2	83.1	48	58.9	0.388

30	8	51.4	69.6	43.5	53	-0.968

100	8	22.8	22.3	30	27	0.0543

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(iji

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij|

This document is a draft for review purposes only and does not constitute Agency policy.

E-319 DRAFT—DO NOT CITE OR QUOTE


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Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1	-141.983433	5	293.966865

A2	-137.581833	8	291.163667

A3	-138.348184	6	288.696368

fitted	-139.728204	4	287.456407

R	-146.997301	2	297.994602

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1
Test 2
Test 3
Test 4

18.8309
8.8032
1.5327
2.76004

0.004459
0.03203
0.4647
0.2516

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adeguately describe the data

Benchmark Dose Computation
Specified effect =	0.1

Risk Type	=	Relative risk

Confidence level =	0.95

BMD =	13.2963

BMDL =	10.6163

This document is a draft for review purposes only and does not constitute Agency policy.

E-320 DRAFT—DO NOT CITE OR QUOTE


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l E.3.11.5. Figure for Additional Model Presented: Polynomial, 3-Degree

Polynomial Model with 0.95 Confidence Level

dose

2	16:30 04/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-321 DRAFT—DO NOT CITE OR QUOTE


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E.3.12. Franc et al., 2001: L-E Rats, Relative Thymus Weight
E.3.12.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

r p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

exponential (M2)

2

0.394

301.666

6.406E+00

2.122E+00



exponential (M3)

2

0.394

301.666

6.406E+00

2.122E+00

power hit bound (d = 1)

exponential
(M4)b

1

0.317

302.808

3.520E+00

1.067E+00



exponential (M5)

0

N/A

303.805

1.280E+01

1.450E+00



Hill

0

N/A

303.805

1.195E+01

9.965E-01



linear

2

0.236

302.690

1.429E+01

9.087E+00



polynomial, 3-
degree

2

0.236

302.690

1.429E+01

9.087E+00



power

2

0.236

302.690

1.429E+01

9.087E+00

power bound hit (power = 1)

power,
unrestricted

1

0.175

303.643

1.297E+00

2.703E-08

unrestricted (power = 0.454)

a Constant variance model selected (p = 0.5063)
b Best-fitting model, BMDS output presented in this appendix

E.3.12.2. Output for Selected Model: Exponential (M4)

Franc et al., 2001: L-E Rats, Relative Thymus Weight

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\1\92_Franc_2001_LE_RelThyWt_ExpCV_l.(d)

Gnuplot Plotting File:

Fri Apr 16 16:30:58 2010

Figure 5, L-E rats, relative thymus weight

The form of the response function by Model:

Model 2
Model 3
Model 4
Model 5

Y[dose]
Y[dose]
Y[dose]
Y[dose]

exp{sign *	b * dose}

exp{sign *	(b * dosej^d}

[c-(c-l) *	exp{-b * dose}]

[c-(c-l) *	exp{-(b * dosej^d}

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;
sign = -1 for decreasing trend.

Model 2 is nested within Models 3 and 4.
Model 3 is nested within Model 5.

Model 4 is nested within Model 5.

This document is a draft for review purposes only and does not constitute Agency policy.

E-322 DRAFT—DO NOT CITE OR QUOTE


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Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))
rho is set to 0.

A constant variance model is fit.

Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values
Variable	Model 4

Specified

lnalpha	8.1814

rho(S)	0

a	105

b	0.0413945

c	0.3173

d	1

Parameter Estimates
Variable	Model 4

lnalpha	8.21275

rho	0

a	106.57

b	0.0425967

c	0.28189

d	1

Table of Stats From Input Data

Dose	N	Obs Mean	Obs Std Dev

0	8	100	54.72

10	8	95.41	70.46

30	8	38.69	47.97

100	8	34.98	77.96

Estimated Values of Interest
Dose	Est Mean	Est Std	Scaled Residual

0	106.6	60.73	-0.306

10	80.03	60.73	0.7164

30	51.36	60.73	-0.5902

100	31.12	60.73	0.1798

Other models for which likelihoods are calculated:

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

This document is a draft for review purposes only and does not constitute Agency policy.

E-323 DRAFT—DO NOT CITE OR QUOTE


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Model A2 :	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma(i)^2

Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= exp(lalpha + log(mean(i) ) 'k rho)

Model R:	Yij	= Mu + e(i)

Var{e(ij)}	= Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	DF	AIC

A1	-146.9024	5	303.8049

A2	-145.7361	8	307.4723

A3	-146.9024	5	303.8049

R	-150.6049	2	305.2098

4	-147.404	4	302.8079

Additive constant for all log-likelihoods =	-29.41. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Test 1: Does response and/or variances differ among Dose levels? (A2 vs. R)

Test 2: Are Variances Homogeneous? (A2 vs. A1)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 6a: Does Model 4 fit the data? (A3 vs 4)

Test

Test 1
Test 2
Test 3
Test 6a

Tests of Interest

-2*log(Likelihood Ratio)

9.738
2 . 333
2 . 333
1. 003

p-value

0.1362
0.5063
0.5063
0.3166

The p-value for Test 1 is greater than .05. There may not be a
diffence between responses and/or variances among the dose levels
Modelling the data with a dose/response curve may not be appropriate.

The p-value for Test 2 is greater than .1. A homogeneous
variance model appears to be appropriate here.

The p-value for Test 3 is greater than .1. The modeled
variance appears to be appropriate here.

The p-value for Test 6a is greater than .1. Model 4 seems
to adeguately describe the data.

Benchmark Dose Computations:

Specified Effect = 0.100000

Risk Type = Relative deviation
Confidence Level = 0.950000

BMD =	3.52038

This document is a draft for review purposes only and does not constitute Agency policy.

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1	E'.MDL =	1.06729

2	E.3.12.3. Figure for Selected Model: Exponential (M4)

Exponential_beta Model 4 with 0.95 Confidence Level

dose

16:30 04/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.3.13. Franc et al., 2001: HAV Rats, Relative Thymus Weight
E.3.13.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

r p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

exponential (M2)

C

2

0.682

261.694

1.366E+01

8.014E+00



exponential (M3)

2

0.682

261.694

1.366E+01

8.014E+00

power hit bound (d = 1)

exponential
(M4)b

1

0.512

263.358

8.820E+00

3.219E+00



exponential (M5)

0

N/A

264.927

1.776E+01

3.500E+00



Hill

0

N/A

264.927

1.701E+01

2.729E+00



linear

2

0.543

262.148

1.919E+01

1.373E+01



polynomial, 3-
degree

2

0.543

262.148

1.919E+01

1.373E+01



power

2

0.543

262.148

1.919E+01

1.373E+01

power bound hit (power = 1)

power,
unrestricted

1

0.381

263.694

8.127E+00

1.406E-01

unrestricted (power = 0.665)

a Constant variance model selected (p = 0.4331)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.3.13.2. Output for Selected Model: Exponential (M2)

Franc et al., 2001: HAV Rats, Relative Thymus Weight

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\1\93_Franc_2001_HW_RelThyWt_ExpCV_l.(d)

Gnuplot Plotting File:

Fri Apr 16 16:31:40 2010

Figure 5, H/W rats, relative thymus weight

The form of the response function by Model:

Model 2
Model 3
Model 4
Model 5

Y[dose]
Y[dose]
Y[dose]
Y[dose]

exp{sign *	b * dose}

exp{sign *	(b * dosej^d}

[c-(c-l) *	exp{-b * dose}]

[c-(c-l) *	exp{-(b * dosej^d}

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;
sign = -1 for decreasing trend.

Model 2 is nested within Models 3 and 4.

This document is a draft for review purposes only and does not constitute Agency policy.

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Model 3 is nested within Model 5.
Model 4 is nested within Model 5.

Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))
rho is set to 0.

A constant variance model is fit.

Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values
Variable	Model 2

Specified

lnalpha	6.96647

rho(S)	0

a	59.5084

b	0.00715458

c	0

d	1

Parameter Estimates
Variable	Model 2

lnalpha	6.99043

rho	0

a	99.7761

b	0.00771341

c	0

d	1

Table of Stats From Input Data
Dose	N	Obs Mean	Obs Std Dev

0	8	100	35.98

10	8	97.53	32.98

30	8	71.02	23.99

100	8	49.29	43.48

Estimated Values of Interest
Est Mean	Est Std	Scaled Residual

0	99.78	32.96	0.01921

10	92.37	32.96	0.4426

30	79.16	32.96	-0.6986

100	46.14	32.96	0.271

Other models for which likelihoods are calculated:

This document is a draft for review purposes only and does not constitute Agency policy.

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Model A1:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma^2

Model A2 :	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma(i)^2

Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= exp(lalpha + log(mean(i) ) 'k rho)

Model R:	Yij	= Mu + e(i)

Var{e(ij)}	= Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	DF	AIC

A1	-127.4636	5	264.9271

A2	-126.0925	8	268.185

A3	-127.4636	5	264.9271

R	-132.935	2	269.87

2	-127.8469	3	261.6939

Additive constant for all log-likelihoods =	-29.41. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Test

1:

Test

2 :

Test

3:

Test

4 :

Does response and/or variances differ among Dose levels? (A2 vs. R)

Are Variances Homogeneous? (A2 vs. A1)

Are variances adeguately modeled? (A2 vs. A3)

Does Model 2 fit the data? (A3 vs. 2)

Test

Test 1
Test 2
Test 3
Test 4

Tests of Interest

-2*log(Likelihood Ratio)

13. 69
2.742
2.742
0.7668

D. F.

p-value

0.03336
0.4331
0.4331
0.6815

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose
levels, it seems appropriate to model the data.

The p-value for Test 2 is greater than .1. A homogeneous
variance model appears to be appropriate here.

The p-value for Test 3 is greater than .1. The modeled
variance appears to be appropriate here.

The p-value for Test 4 is greater than .1. Model 2 seems
to adeguately describe the data.

Benchmark Dose Computations:

Specified Effect = 0.100000

Risk Type = Relative deviation
Confidence Level = 0.950000

BMD =	13.6594

This document is a draft for review purposes only and does not constitute Agency policy.

E-328 DRAFT—DO NOT CITE OR QUOTE


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E'.MDL =	8.0137 3

E.3.13.3. Figure for Selected Model: Exponential (M2)

Exponential_beta Model 2 with 0.95 Confidence Level

a>

CO
c
o

Q.

CO
CD

a:

c
m

CD

140

120

100

80

60

40

20

Exponential

BMD

20

40

60

80

100

dose

16:31 04/16 2010

E.3.13.4. Output for Additional Model Presented: Exponential (M4)
Franc et al., 2001: H/W Rats, Relative Thymus Weight

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\1\93_Franc_2001_HW_RelThyWt_ExpCV_l.(d)

Gnuplot Plotting File:

Fri Apr 16 16:31:40 2010

Figure 5, H/W rats, relative thymus weight

The form of the response function by Model:

Model 2
Model 3
Model 4
Model 5

Y[dose]
Y[dose]
Y[dose]
Y[dose]

exp{sign
exp{sign
[c—(c—1)
[c—(c—1)

b * dose}
(b * dose)^d}
exp{-b * dose}]
exp{-(b * dose)^d}

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;
sign = -1 for decreasing trend.

This document is a draft for review purposes only and does not constitute Agency policy.

E-329 DRAFT—DO NOT CITE OR QUOTE


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Model 2 is nested within Models 3 and 4.
Model 3 is nested within Model 5.

Model 4 is nested within Model 5.

Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))
rho is set to 0.

A constant variance model is fit.

Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values
Variable	Model 4

Specified

lnalpha	6.96647

rho(S)	0

a	105

b	0.03169

c	0.447105

d	1

Parameter Estimates
Variable	Model 4

lnalpha	6.97993

rho	0

a	103.091

b	0.02048

c	0.394904

d	1

Table of Stats From Input	Data

use	N	Obs Mean	Obs Std Dev

0	8	100	35.98

10	8	97.53	32.98

30	8	71.02	23.99

100	8	49.29	43.48

Estimated Values of	Interest
Dose Est Mean Est Std Scaled Residual

0	103.1	32.78	-0.2667

10	91.54	32.78	0.5166

30	74.46	32.78	-0.2961

100	48.76	32.78	0.04621

This document is a draft for review purposes only and does not constitute Agency policy.

E-330 DRAFT—DO NOT CITE OR QUOTE


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Other models for which	likelihoods are calculated:

Model A1:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma/'2

Model A2 :	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma(i)^2

Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= exp(lalpha + log(mean(i)) * rho)

Model R:	Yij	= Mu + e(i)

Var{e(ij)}	= Sigma/'2

Likelihoods of Interest

Model	Log(likelihood)	DF	AIC

A1	-127.4636	5	264.9271

A2	-126.0925	8	268.185

A3	-127.4636	5	264.9271

R	-132.935	2	269.87

4	-127.6789	4	263.3577

Additive constant for all log-likelihoods =	-29.41. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Test 1: Does response and/or variances differ among Dose levels? (A2 vs. R)

Test 2: Are Variances Homogeneous? (A2 vs. A1)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 6a: Does Model 4 fit the data? (A3 vs 4)

Test

Test 1
Test 2
Test 3
Test 6a

Tests of Interest

-2*log(Likelihood Ratio)

13. 69
2.742
2.742
0.4306

D. F.

p-value

0.03336
0.4331
0.4331
0.5117

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose
levels, it seems appropriate to model the data.

The p-value for Test 2 is greater than .1. A homogeneous
variance model appears to be appropriate here.

The p-value for Test 3 is greater than .1. The modeled
variance appears to be appropriate here.

The p-value for Test 6a is greater than .1. Model 4 seems
to adeguately describe the data.

Benchmark Dose Computations:

Specified Effect = 0.100000

Risk Type = Relative deviation

This document is a draft for review purposes only and does not constitute Agency policy.

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Confidence Level = 0.950000

BMD =	8.82023

BMDL =	3.21928

E.3.13.5. Figure for Additional Model Presented: Exponential (M4)

Exponential_beta Model 4 with 0.95 Confidence Level

dose

16:31 04/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-332 DRAFT—DO NOT CITE OR QUOTE


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E.3.14. Hojo et al., 2002: DRL Reinforce Per Minute
E.3.14.1. Summary Table of BMDS Modeling Results

Model3

Degrees of
Freedom

X2 P-
Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Hill

0

N/A

6.465

2.060E+01

1.713E-05



linear b

2

0.008

9.552

2.677E+02

1.100E+02



polynomial, 3-
degree

2

0.008

9.552

2.677E+02

1.100E+02



power

2

0.008

9.552

2.677E+02

1.100E+02

power bound hit (power =1)

power, unrestricted

1

0.025

6.780

2.187E+00

4.612E-08

unrestricted (power = 0.089)

exponential (M2)

2

0.006

9.894

3.043E+02

1.505E+02



exponential (M3)

2

0.006

9.894

3.043E+02

1.505E+02

power hit bound (d = 1)

exponential (M4)0

1

0.062

5.241

1.734E+01

3.827E-02



exponential (M5)

0

N/A

6.465

2.140E+01

1.240E-05



a Constant variance model selected (p = 0.4321)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.3.14.2. Output for Selected Model: Linear

Hojo et al., 2002: DRL Reinforce Per Minute

Polynomial Model. (Version: 2.13; Date: 04/08/2008)

Input Data File: C:\1\20_Hojo_2002_DRLrein_LinearCV_l.(d)

Gnuplot Plotting File: C:\l\20_Hojo_2002_DRLrein_LinearCV_l.plt

Tue Feb 16 17:29:42 2010

Table 5

The form of the response function is:

Y[dose] = beta_0 + beta_l*dose + beta_2*dose/'2 + ...

Dependent variable = Mean
Independent variable = Dose
rho is set to 0

Signs of the polynomial coefficients are not restricted
A constant variance model is fit

Total number of dose groups = 4

This document is a draft for review purposes only and does not constitute Agency policy.

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Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
alpha =	0.337763

rho =	0 Specified

beta_0 =	-0.4 04

beta~l = 0.00249615

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -rho

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha	beta 0	beta 1

alpha 1	-1.4e-008	2.2e-008

beta_0 -1.4e-008	1	-0.69

beta 1 2.2e-008	-0.69	1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
alpha
beta_0
beta 1

Estimate

0. 435671
-0.372098
0.00246548

Std. Err.
0.134451
0.198702
0. 00211361

Lower Conf. Limit
0.172152
-0.761547
-0.00167711

Upper Conf. Limit

0 . 6 9 919
0. 017352
0. 00660807

Table of Data and Estimated Values of Interest

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0	5	-0.814	-0.372	0.448	0.66	-1.5

20	5	-0.364	-0.323	0.821	0.66	-0.14

60	6	0.374	-0.224	0.54	0.66	2.22

180	5	-0.163	0.0717	0.443	0.66	-0.795

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

This document is a draft for review purposes only and does not constitute Agency policy.

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Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1	3.115550	5	3.768900

A2	4.489557	8	7.020886

A3	3.115550	5	3.768900

fitted	-1.775882	3	9.551763

R	-2.435087	2	8.870174

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adequately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Test

2

Test

3

Test

4

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	13.8493	6	0.03137

Test 2	2.74801	3	0.4321

Test 3	2.74801	3	0.4321

Test 4	9.78286	2	0.007511

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than .1. A homogeneous variance
model appears to be appropriate here

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is less than .1. You may want to try a different
model

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	267.718

BMDL =	110.032

This document is a draft for review purposes only and does not constitute Agency policy.

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E.3.14.3. Figure for Selected Model: Linear

Linear Model with 0.95 Confidence Level

dose

17:29 02/16 2010

E.3.14.4. Output for Additional Model Presented: Exponential (M4)
Hojo et al., 2002: DRL Reinforce Per Minute

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\1\21_Hojo_2002_DRLrein_ExpCV_l.(d)

Gnuplot Plotting File:

Tue Feb 16 17:30:21 2010

Table 5, values adjusted by a constant to allow exponential model

The form of the response function by Model:

Model 2
Model 3
Model 4
Model 5

Y[dose]
Y[dose]
Y[dose]
Y[dose]

exp{sign * b * dose}
exp{sign * (b * dose)^d}
[c-(c-l) * exp{-b * dose}]
[c-(c-l) * exp{-(b * dose)^d}

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;
sign = -1 for decreasing trend.

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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Model 2 is nested within Models 3 and 4.
Model 3 is nested within Model 5.

Model 4 is nested within Model 5.

Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))
rho is set to 0.

A constant variance model is fit.

Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values
Variable	Model 4

Specified

lnalpha	-1.29672

rho(S)	0

a	0.0817

b	0.00880867

c	16.3733

d	1

Parameter Estimates
Variable	Model 4

lnalpha	-1.13136

rho	0

a	0.0542868

b	0.0525016

c	18.5072

d	1

Table of Stats From Input Data
Dose	N	Obs Mean	Obs Std Dev

0	5	0.086	0.448

20	5	0.536	0.821

60	6	1.274	0.54

180	5	0.737	0.443

Estimated Values of Interest
Est Mean	Est Std	Scaled Residual

0	0.05429	0.568	0.1249

20	0.6721	0.568	-0.5359

60	0.964	0.568	1.337

180	1.005	0.568	-1.054

Other models for which likelihoods are calculated:

This document is a draft for review purposes only and does not constitute Agency policy.

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Model A1:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma^2

Model A2 :	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma(i)^2

Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= exp(lalpha + log(mean(i) ) 'k rho)

Model R:	Yij	= Mu + e(i)

Var{e(ij)}	= Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	DF	AIC

A1	3.11555	5	3.7689

A2	4.489557	8	7.020886

A3	3.11555	5	3.7689

R	-2.435087	2	8.870174

4	1.379312	4	5.241376

Additive constant for all log-likelihoods =	-19.3. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Test 1: Does response and/or variances differ among Dose levels? (A2 vs. R)

Test 2: Are Variances Homogeneous? (A2 vs. A1)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 6a: Does Model 4 fit the data? (A3 vs 4)

Test

Test 1
Test 2
Test 3
Test 6a

Tests of Interest

-2*log(Likelihood Ratio)

13. 85
2.748
2.748
3.472

D. F.

p-value

0.03137
0.4321
0.4321
0.0624

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose
levels, it seems appropriate to model the data.

The p-value for Test 2 is greater than .1. A homogeneous
variance model appears to be appropriate here.

The p-value for Test 3 is greater than .1. The modeled
variance appears to be appropriate here.

The p-value for Test 6a is less than .1. Model 4 may not adeguately
describe the data; you may want to consider another model.

Benchmark Dose Computations:

Specified Effect = 1.000000

Risk Type = Estimated standard deviations from control
Confidence Level = 0.950000

This document is a draft for review purposes only and does not constitute Agency policy.

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BMD =	17.3391

BMDL = 0.0382689

E.3.14.5. Figure for Additional Model Presented: Exponential (M4)

(D
CO
c
o
Q.
CO
(D

(Z
c
(0
(D

Exponential_beta Model 4 with 0.95 Confidence Level

i	1	1	1	1—

80 100
dose

120

140

160

180

17:30 02/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-339 DRAFT—DO NOT CITE OR QUOTE


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E.3.15. Hojo et al., 2002: DRL Response Per Minute

E.3.15.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

X2 P-
Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Hill

0

N/A

126.353

1.646E+01

1.800E-13



linear

2

0.004

132.825

2.067E+02

9.757E+01



polynomial, 3-
degree

2

0.004

132.825

2.067E+02

9.757E+01



power

2

0.004

132.825

2.067E+02

9.757E+01

power bound hit (power = 1)

power,
unrestricted

2

0.741

122.455

1.800E+04

error

unrestricted (power = 0)

exponential (M2)

2

0.568

122.985

6.184E+00

error



exponential (M3)

2

0.568

122.985

6.184E+00

error

power hit bound (d = 1)

exponential
(M4)b

1

0.479

124.356

4.775E+00

2.704E-01



exponential (M5)

0

N/A

126.353

1.118E+01

2.127E-01



a Constant variance model selected (p = 0.3004)
b Best-fitting model, BMDS output presented in this appendix

E.3.15.2. Output for Selected Model: Exponential (M4)

Hojo et al., 2002: DRL Response Per Minute

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\1\23_Hojo_2002_DRLresp_ExpCV_l.(d)

Gnuplot Plotting File:

Tue Feb 16 17:31:24 2010

Table 5, values adjusted by a constant to allow exponential model

The form of the response function by Model:

Model 2
Model 3
Model 4
Model 5

Y[dose]
Y[dose]
Y[dose]
Y[dose]

exp{sign *	b * dose}

exp{sign *	(b * dosej^d}

[c-(c-l) *	exp{-b * dose}]

[c-(c-l) *	exp{-(b * dosej^d}

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;
sign = -1 for decreasing trend.

Model 2 is nested within Models 3 and 4.
Model 3 is nested within Model 5.

Model 4 is nested within Model 5.

This document is a draft for review purposes only and does not constitute Agency policy.

E-340 DRAFT—DO NOT CITE OR QUOTE


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Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))
rho is set to 0.

A constant variance model is fit.

Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values
Variable	Model 4

Specified

lnalpha	4.51689

rho(S)	0

a	24.6362

b	0.0212679

c	0.0184785

d	1

Parameter Estimates
Variable	Model 4

lnalpha	4.54075

rho	0

a	23.465

b	0.12859

c	0.100615

d	1

Table of Stats From Input Data

Dose	N	Obs Mean	Obs Std Dev

0	5	23.46	7.986

20	5	4.013	10.96

60	6	0.478	7.194

180	5	4.594	15.23

Estimated Values of Interest
Dose	Est Mean	Est Std	Scaled Residual

0	23.47	9.683	-0.0004677

20	3.973	9.683	0.009182

60	2.37	9.683	-0.4787

180	2.361	9.683	0.5157

Other models for which likelihoods are calculated:

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

This document is a draft for review purposes only and does not constitute Agency policy.

E-341 DRAFT—DO NOT CITE OR QUOTE


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Model A2 :	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma(i)^2

Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= exp(lalpha + log(mean(i) ) 'k rho)

Model R:	Yij	= Mu + e(i)

Var{e(ij)}	= Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	DF	AIC

A1	-57.92733	5	125.8547

A2	-56.09669	8	128.1934

A3	-57.92733	5	125.8547

R	-64.49611	2	132.9922

4	-58.17787	4	124.3557

Additive constant for all log-likelihoods =	-19.3. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Test 1: Does response and/or variances differ among Dose levels? (A2 vs. R)

Test 2: Are Variances Homogeneous? (A2 vs. A1)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 6a: Does Model 4 fit the data? (A3 vs 4)

Test

Test 1
Test 2
Test 3
Test 6a

Tests of Interest

-2*log(Likelihood Ratio)

16.8
3. 661
3. 661
0.5011

p-value

0.01005
0.3004
0.3004
0.479

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose
levels, it seems appropriate to model the data.

The p-value for Test 2 is greater than .1. A homogeneous
variance model appears to be appropriate here.

The p-value for Test 3 is greater than .1. The modeled
variance appears to be appropriate here.

The p-value for Test 6a is greater than .1. Model 4 seems
to adeguately describe the data.

Benchmark Dose Computations:

Specified Effect = 1.000000

Risk Type = Estimated standard deviations from control
Confidence Level = 0.950000

BMD =	4.77493

This document is a draft for review purposes only and does not constitute Agency policy.

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1	E'.MDL =	0.27 04 4 7

2

3

4	E.3.15.3. Figure for Selected Model: Exponential (M4)

Exponential_beta Model 4 with 0.95 Confidence Level

dose

5	17:31 02/16 2010

6

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.3.16. Kattainen et al., 2001: 3rd Molar Eruption, Female
E.3.16.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

logistic

3

0.292

89.060

1.941E+02

1.390E+02

negative intercept (intercept =
-1.508)

log-logistica

3

0.923

85.535

4.763E+01

2.481E+01

slope bound hit (slope = 1)

log-probit

3

0.390

88.231

1.574E+02

9.512E+01

slope bound hit (slope =1)

probit

3

0.306

88.919

1.858E+02

1.370E+02

negative intercept (intercept =
-0.927)

multistage, 4-
degree

3

0.641

86.798

8.677E+01

5.520E+01

final B = 0

log-logistic,
unrestricted b

2

0.952

87.157

2.599E+01

1.730E+00

unrestricted (slope = 0.794)

log-probit,
unrestricted

2

0.941

87.179

2.813E+01

2.334E+00

unrestricted (slope = 0.478)

a Best-fitting model, BMDS output presented in this appendix
b Alternate model, BMDS output also presented in this appendix

E.3.16.2. Output for Selected Model: Log-Logistic

Kattainen et al., 2001: 3rd Molar Eruption, Female

Logistic Model. (Version: 2.12; Date: 05/16/2008)

Input Data File: C:\1\24_Katt_2001_Erup_LogLogistic_BMRl.(d)

Gnuplot Plotting File: C:\l\24_Katt_2001_Erup_LogLogistic_BMRl.plt

Tue_Feb 16 17:31:52 2010

Figure 2

The form of the probability function is:

P[response] = background+(1-background)/[1+EXP(-intercept-slope*Log(dose))]

Dependent variable = DichEff
Independent variable = Dose

Slope parameter is restricted as slope >= 1
Total number of observations = 5

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

User has chosen the log transformed model

This document is a draft for review purposes only and does not constitute Agency policy.

E-344 DRAFT—DO NOT CITE OR QUOTE


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Default Initial Parameter Values
background =	0.0625

intercept =	-6.063

slope =	1

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -slope

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

background intercept

background	1	-0.56

intercept	-0.56	1

Parameter Estimates

95.0% Wald Confidence Interval

Variable Estimate Std. Err.	Lower Conf. Limit Upper Conf. Limit

background 0.0846785 *	*	*

intercept -6.06063 *	*	*

slope 1 *	*	*

Indicates that this value is not calculated.

Model
Full model
Fitted model

Analysis of Deviance Table

Deviance

Log(likelihood
-40.5286
-40.7674

Param's

5
2

Test d.f.

0. 477533

P-value

0.9238

Reduced

model

50.7341

1



20.411

4 0.0004142



AIC:

85.5347













Goodness

of

Fit















Scaled

Dose

Est. Prob.

Expected

Observed

Size

Residual

0.0000

0.0847

1. 355

1.

000

16

-0.319

30.0000

0.1445

2 .457

3.

000

17

0.374

100.0000

0.2578

3. 867

4 .

000

15

0. 078

300.0000

0. 4615

5.538

6 .

000

12

0.267

1000.0000

0.7254

13.782

13.

000

19

-0.402

Chi ^2

0. 4E

d. f.

3

P-value

0.9231

Benchmark Dose Computation
Specified effect =	0.1

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	47.6274

BMDL =	24.8121

This document is a draft for review purposes only and does not constitute Agency policy.

E-345 DRAFT—DO NOT CITE OR QUOTE


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E.3.16.3. Figure for Selected Model: Log-Logistic

Log-Logistic Model with 0.95 Confidence Level

"O

(D

-t—<

o

CD
!t=
<

0.6

0.4

0.2

200

400	600

dose

800

1000

17:31 02/16 2010

E.3.16.4. Output for Additional Model Presented: Log-Logistic, Unrestricted
Kattainen et al., 2001: 3rd Molar Eruption, Female

Logistic Model. (Version: 2.12; Date: 05/16/2008)

Input Data File: C:\1\24_Katt_2001_Erup_LogLogistic_U_BMRl.(d)

Gnuplot Plotting File: C:\l\24_Katt_2001_Erup_LogLogistic_U_BMRl.plt

Tue Feb 16 17:31:53 2010

Figure 2

The form of the probability function is:

P[response] = background+(1-background)/[1+EXP(-intercept-slope*Log(dose)

Dependent variable = DichEff
Independent variable = Dose
Slope parameter is not restricted

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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Total number of observations = 5

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

User has chosen the log transformed model

Default Initial Parameter Values
background =	0.0625

intercept =	-4.71231

slope =	0.782659

Asymptotic Correlation Matrix of Parameter Estimates
background intercept	slope

background	1	-0.48	0.39

intercept	-0.48	1	-0.98

slope	0.39	-0.98	1

Parameter Estimates

Variable
background
intercept
slope

Estimate

0.0633217
-4.78282
0.793723

Std. Err.

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

Indicates that this value is not calculated.

Analysis of Deviance Table

Model
Full model
Fitted model
Reduced model

Log(likelihood)
-40.5286
-40.5783
-50.7341

Param's

5
3
1

Deviance Test d.f.

0.0994416
20.411

P-value

0. 9515
0.0004142

AIC:

87 .1566

Est. Prob.

Goodness of Fit
Expected Observed

Scaled
Residual

0.0000

0.0633

1. 013

1.

000

16

-0.013

30.0000

0.1670

2.840

3.

000

17

0.104

100.0000

0.2924

4 . 387

4 .

000

15

-0.219

300.0000

0. 4721

5.666

6 .

000

12

0.193

1000.0000

0.6892

13.095

13.

000

19

-0.047

Chi ^2 = 0.10

d.f.

= 2 P

-value

= 0.9518





Benchmark Dose Computation
Specified effect =	0.1

Risk Type	=	Extra risk

This document is a draft for review purposes only and does not constitute Agency policy.

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Confidence level =	0.95

BMD =	25.986

BMDL =	1.73001

E.3.16.5. Figure for Additional Model Presented: Log-Logistic, Unrestricted

Log-Logistic Model with 0.95 Confidence Level

dose

17:31 02/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.3.17. Kattainen et al., 2001: 3rd Molar Length, Female
E.3.17.1. Summary Table of BMDS Modeling Results

Model3

Degrees of
Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

exponential (M2)

3

<0.0001

-122.954

4.027E+02

2.366E+02



exponential (M3)

3

<0.0001

-122.954

4.027E+02

2.366E+02

power hit bound (d = 1)

exponential (M4)

2

<0.0001

-80.747

error

error



exponential (M5)

1

<0.0001

-78.747

error

error



Hillb

2

0.013

-151.152

4.052E+00

2.144E+00

n lower bound hit (n = 1)

linear

3

<0.0001

-122.325

4.659E+02

2.963E+02



polynomial, 4-
degree

3

<0.0001

-122.325

4.659E+02

2.963E+02



power

3

<0.0001

-122.325

4.659E+02

2.963E+02

power bound hit (power =1)

Hill, unrestricted0

1

0.087

-154.939

1.913E-02

1.928E-04

unrestricted (n = 0.197)

power, unrestricted

2

0.250

-157.093

9.098E-03

9.097E-03

unrestricted (power = 0.169)

a Non-constant variance model selected (p = <0.0001)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.3.17.2. Output for Selected Model: Hill

Kattainen et al., 2001: 3rd Molar Length, Female

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\1\25_Katt_2001_Length_Hill_l.(d)

Gnuplot Plotting File: C:\l\25_Katt_2001_Length_Hill_l.plt

Tue Feb 16~17:32:21 2010

Figure 3 female only

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = Mean
Independent variable = Dose

Power parameter restricted to be greater than 1

The variance is to be modeled as Var(i) = exp(lalpha + rho * ln(mean(i)))

This document is a draft for review purposes only and does not constitute Agency policy.

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Total number of dose groups = 5

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

lalpha
rho

intercept

-2 . 37155

0

1. 85591
-0.507874
0. 826204
27 . 3305

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -n

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

lalpha
rho

intercept

lalpha
1

-0. 98
-0.16
0.84
-0.37

rho

-0. 98
1

0.2
-0.79
0.39

intercept

-0.16
0.2
1

-0.31
-0.11

v

0.84
-0.79
-0.31
1

-0.48

k

-0.37
0.39
-0.11
-0.48
1

Parameter Estimates

Variable
lalpha
rho

intercept

k

Estimate
3.34561
-14.3325
1. 8548
-0.441166
1

24.0343

Std. Err.
1.40443
2 . 62129
0.0159017
0.058852
NA

7.84495

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

0.592981

-19.4701
1.82364
-0.556513

8.65852

6.09824
-9.19484
1.88597
-0.325818

39.4101

NA - Indicates that this parameter has hit a bound
implied by some ineguality constraint and thus
has no standard error.

Table of Data and Estimated Values of Interest

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0	16	1.86	1.85	0.0661	0.0637	0.0692

30	17	1.58	1.61	0.185	0.176	-0.768

100	15	1.6	1.5	0.265	0.293	1.28

300	12	1.5	1.45	0.221	0.378	0.527

1000	19	1.35	1.42	0.515	0.423	-0.783

Model Descriptions for likelihoods calculated

This document is a draft for review purposes only and does not constitute Agency policy.

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Model A1:	Yij	= Mu(i) + e(iji

Var{e(ij)} = Sigma/'2

Model A2 :	Yij	= Mu(i) + e(ij|

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model
A1

A2
A3

fitted
R

Log(likelihood)
56.758717
85.856450
84.934314
80.575940
45.373551

10

7
5
2

AIC
-101.517434
-151.712901
-155.868628
-151.151880
-86.747101

Test

1

Test

2

Test

3

Test

4

(Note:

Explanation of Tests

Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1

Test 2
Test 3
Test 4

80.9658
58 .1955
1.84427
8 .71675

<.0001
<.0001
0.6053
0.0128

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is less than .1. You may want to try a different
model

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	4 . 05231

BMDL =	2.14357

This document is a draft for review purposes only and does not constitute Agency policy.

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E.3.17.3. Figure for Selected Model: Hill

Hill Model with 0.95 Confidence Level

1.9

1.8

1.7


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Total number of dose groups = 5

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

lalpha
rho

intercept

-2 . 37155

0

1. 85591
-0.507874
0. 826204
27 . 3305

Asymptotic Correlation Matrix of Parameter Estimates

lalpha
rho

intercept

lalpha
1

-0. 98
-0.18
0.18
-0.28
-0.011

rho

-0. 98
1

0.22
-0.18
0.29
0. 011

intercept

-0.18
0.22
1

-0.025
-0.059
0.0019

v

0.18
-0.18
-0.025
1

0.51
-0. 96

n

-0.28
0.29
-0.059
0.51
1

-0.71

k

-0.011
0. 011
0.0019
-0. 96
-0.71
1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
lalpha
rho

intercept

Estimate
3.21882
-14.0862
1. 85564
-2 .48572
0.196925
1. 92 967e + 006

Std. Err.
1.4221
2.68292
0.0160224
2 .89658
0.0499318
1.60869e+007

Lower Conf. Limit

0. 431563
-19.3446
1.82424
-8.16291
0.0990606
-2.96e+007

Upper Conf. Limit

6.00607

82777
88704
19148
2947 9

3.34593e+007

Table of Data and Estimated Values of Interest

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0
30
100
300
1000

16

17
15
12
19

1.86
1. 58
1. 6
1. 5
1. 35

1.86
1. 6
1. 54
1.48
1. 4

0.0661

0.185
0.265
0.221
0.515

0.0643
0.18
0.234
0.316
0.471

0.0164

-0.598
0. 857
0.259
-0.466

Model Descriptions for likelihoods calculated

Model A1:	Yij	= Mu(i) + e(iji

Var{e(ij)} = Sigma/'2

Model A2:	Yij	= Mu(i) + e(ij|

Var{e(ij)} = Sigma(i)^2

This document is a draft for review purposes only and does not constitute Agency policy.

E-353 DRAFT—DO NOT CITE OR QUOTE


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Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1	56.758717	6	-101.517434

A2	85.856450	10	-151.712901

A3	84.934314	7	-155.868628

fitted	83.469680	6	-154.939361

R	45.373551	2	-86.747101

Explanation of Tests

Test 1:

Test

2

Test

3

Test

4

Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	80.9658	8	<.0001

Test 2	58.1955	4	<.0001

Test 3	1.84427	3	0.6053

Test 4	2.92927	1	0.08699

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is less than .1. You may want to try a different
model

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	0.0191282

BMDL =	0.0001928

This document is a draft for review purposes only and does not constitute Agency policy.

E-3 54 DRAFT—DO NOT CITE OR QUOTE


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E.3.17.5. Figure for Additional Model Presented: Hill, Unrestricted

Hill Model with 0.95 Confidence Level

dose

17:32 02/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-355 DRAFT—DO NOT CITE OR QUOTE


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E.3.18. Keller et al., 2007: Missing Mandibular Molars, CBA J
E.3.18.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

gamma

1

0.105

52.490

7.293E+01

2.027E+01



logistic

2

0.320

50.095

7.168E+01

5.142E+01

negative intercept (intercept =
-3.372)

log-logistic

1

0.105

52.524

9.278E+01

5.273E+01



log-probit

1

0.105

52.524

8.849E+01

5.297E+01



multistage, 1-
degreea

3

0.276

49.409

2.778E+01

1.884E+01



multistage, 2-
degree

1

0.126

51.515

4.619E+01

2.214E+01



multistage, 3-
degree

1

0.141

51.222

4.253E+01

2.212E+01



probit

2

0.325

50.032

6.848E+01

4.775E+01

negative intercept (intercept =
-1.851)

Weibull

1

0.108

52.216

6.079E+01

2.078E+01



a Best-fitting model, BMDS output presented in this appendix

E.3.18.2. Output for Selected Model: Multistage, 1-Degree

Keller et al., 2007: Missing Mandibular Molars, CBA J

Multistage Model. (Version: 3.0; Date: 05/16/2008)

Input Data File: C:\1\26_Keller_2007_Molars_Multil_l.(d)

Gnuplot Plotting File: C:\l\26_Keller_2007_Molars_Multil_l.plt

Tue Feb_16 17:32:56 2010

Table 1 using mandibular molars only

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = DichEff
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0

This document is a draft for review purposes only and does not constitute Agency policy.

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Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
Background =	0

Beta(1) = 1.02909e+017

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -Background

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Beta(1)

Beta(1)	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0	*	*	*

Beta(1)	0.00379264	*	*	*

Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-21.5798	4

Fitted model -23.7044 1	4.24924 3	0.2358

Reduced model -71.326 1	99.4926 3	<.0001

AIC:	49.4088

Goodness of Fit

Scaled

Dose	Est. Prob. Expected Observed	Size	Residual

0.0000

0.0000

0. 000

0. 000

29

0. 000

10.0000

0.0372

0. 856

2 . 000

23

1.260

100.0000

0.3156

9.153

6. 000

29

-1.260

1000.0000

0.9775

29.324

30.000

30

0. 832

Chi ^2 = 3.87	d.f. = 3	P-value = 0.2762

Benchmark Dose Computation
Specified effect =	0.1

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	27.7803

BMDL =	18.84 47

This document is a draft for review purposes only and does not constitute Agency policy.

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E'.MDU =

41.7256

Taken together, (18.8447, 41.7256) is a 90	% two-sided confidence

interval for the EMD

E.3.18.3. Figure for Selected Model: Multistage, 1-Degree

Multistage Model with 0.95 Confidence Level

-i—i—		—i—i—¦ | '

Multista

1

"O

(D

-t—<

o

CD
!t=
<
c
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0.6

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400	600

dose

17:32 02/16 2010

This document is a draft for review purposes only and does not constitute Agency policy.

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E.3.19. Kociba et al., 1978: Urinary Coproporphyrin, Females
E.3.19.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

exponential (M2)

2

<0.0001

84.006

7.054E+01

4.341E+01



exponential (M3)

2

<0.0001

84.006

7.054E+01

4.341E+01

power hit bound (d = 1)

exponential
(M4)b

1

0.040

70.556

1.625E+00

7.300E-01



exponential (M5)

0

N/A

69.092

3.128E+00

1.024E+00



Hill

0

N/A

69.047

6.677E+00

error



linear

2

<0.0001

83.713

6.195E+01

3.112E+01



polynomial, 3-
degree

2

<0.0001

83.713

6.195E+01

3.112E+01



power

2

<0.0001

83.713

6.195E+01

3.112E+01

power bound hit (power =1)

power,
unrestricted

1

0.001

78.260

7.808E-01

1.693E-08

unrestricted (power = 0.306)

a Non-constant variance model selected (p = 0.0298)
b Best-fitting model, BMDS output presented in this appendix

E.3.19.2. Output for Selected Model: Exponential (M4)

Kociba et al., 1978: Urinary Coproporphyrin, Females

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\1\29_Kociba_l978_Copro_Exp_l.(d)

Gnuplot Plotting File:

Tue Feb 16 17:34:45 2010

Table2-UrinaryCoproporphyrin

The form of the response function by Model:

Model 2
Model 3
Model 4
Model 5

Y[dose]
Y[dose]
Y[dose]
Y[dose]

exp{sign *	b * dose}

exp{sign *	(b * dosej^d}

[c-(c-l) *	exp{-b * dose}]

[c-(c-l) *	exp{-(b * dosej^d}

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;
sign = -1 for decreasing trend.

Model 2 is nested within Models 3 and 4.
Model 3 is nested within Model 5.

Model 4 is nested within Model 5.

This document is a draft for review purposes only and does not constitute Agency policy.

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Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)
Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values
Variable	Model 4

lnalpha	-5.58269

rho	2.98472

a	8.17

b	0.0259469

c	2.23623

d	1

Parameter Estimates
Variable	Model 4

lnalpha	-4.94473

rho	2.76088

a	8.93039

b	0.136554

c	1.9753

d	1

Table of Stats From Input	Data

use N Obs Mean	Obs Std Dev

0 5 9.8	1.3

15 8.6	2

10 5 16.4	4.7

100 5 17.4	4

Estimated Values of	Interest

Dose Est Mean Est Std	Scaled Residual

0	8.93	1.733	1.122

1	10.04	2.038	-1.582
10	15.42	3.683	0.5967

100	17.64	4.436	-0.1211

Other models for which likelihoods are calculated:

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

This document is a draft for review purposes only and does not constitute Agency policy.

E-360 DRAFT—DO NOT CITE OR QUOTE


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Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= exp(lalpha + log(mean(i) ) 'k rho)

Model R:	Yij	= Mu + e(i)

Var{e(ij)}	= Sigma^2

Likelihoods of Interest
Model	Log(likelihood)	DF	AIC

A1

-31.69739

5

73

39478

A2

-27 . 21541

8

70

43081

A3

-28.16434

6

68

32868

R

-41. 73188

2

87

46376

4

-30.27804

5

70

55608

Additive constant for all log-likelihoods =	-18.38. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Test

1:

Does response

and/or variances differ among Dose levels? (A2 vs. R)

Test

2 :

Are Variances

Homogeneous? (A2 vs. A1)

Test

3:

Are variances

adequately modeled? (A2 vs. A3)

Test 6a: Does Model 4 fit the data? (A3 vs 4)

Test

Test 1
Test 2
Test 3
Test 6a

Tests of Interest

-2*log(Likelihood Ratio)

29. 03
8 . 964
1.898
4 . 227

p-value

C 0.0001
0.02977
0.3872
0.03978

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose
levels, it seems appropriate to model the data.

The p-value for Test 2 is less than .1. A non-homogeneous
variance model appears to be appropriate.

The p-value for Test 3 is greater than .1. The modeled
variance appears to be appropriate here.

The p-value for Test 6a is less than .1. Model 4 may not adeguately
describe the data; you may want to consider another model.

Benchmark Dose Computations:

Specified Effect = 1.000000

Risk Type = Estimated standard deviations from control
Confidence Level = 0.950000

BMD =	1.62505

BMDL =	0.729987

This document is a draft for review purposes only and does not constitute Agency policy.

E-361 DRAFT—DO NOT CITE OR QUOTE


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l E.3.19.3. Figure for Selected Model: Exponential (M4)

Exponential_beta Model 4 with 0.95 Confidence Level

dose

2	17:34 02/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-362 DRAFT—DO NOT CITE OR QUOTE


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E.3.20. Kociba et al., 1978: Uroporphyrin per Creatinine, Female
E.3.20.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

r p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

exponential (M2)

2

0.661

-93.561

4.357E+01

3.328E+01



exponential (M3)

2

0.661

-93.561

4.357E+01

3.328E+01

power hit bound (d = 1)

exponential (M4)

1

0.576

-92.078

1.719E+01

5.516E+00



exponential (M5)

0

N/A

-90.190

1.080E+01

5.613E+00



Hill

0

N/A

-90.190

1.099E+01

5.088E+00



linear b

2

0.720

-93.735

3.522E+01

2.500E+01



polynomial, 3-
degree

2

0.720

-93.735

3.522E+01

2.500E+01



power

2

0.720

-93.735

3.522E+01

2.500E+01

power bound hit (power =1)

power,
unrestricted

1

0.515

-91.967

2.274E+01

3.334E+00

unrestricted (power = 0.731)

a Constant variance model selected (p = 0.4919)
b Best-fitting model, BMDS output presented in this appendix

E.3.20.2. Output for Selected Model: Linear

Kociba et al., 1978: Uroporphyrin per Creatinine, Female

Polynomial Model. (Version: 2.13; Date: 04/08/2008)

Input Data File: C:\1\28_Kociba_l978_Uropor_LinearCV_l.(d)

Gnuplot Plotting File: C:\l\28_Kociba_197 8_Uropor_LinearCV_l.plt

Tue Feb_16 17:347l2 2010

Table 2

The form of the response function is:

Y[dose] = beta_0 + beta_l*dose + beta_2*dose/'2 + ...

Dependent variable = Mean
Independent variable = Dose
rho is set to 0

Signs of the polynomial coefficients are not restricted
A constant variance model is fit

Total number of dose groups = 4

Total number of records with missing values = 0

This document is a draft for review purposes only and does not constitute Agency policy.

E-363 DRAFT—DO NOT CITE OR QUOTE


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Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
alpha = 0.0030385

rho =	0 Specified

beta_0 =	0.154759

beta 1 = 0.0014231

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -rho

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha	beta 0	beta 1

alpha 1	-2.2e-009	3.5e-009

beta_0 -2.2e-009	1	-0.55

beta 1 3.5e-009	-0.55	1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
alpha
beta_0
beta 1

Estimate

0. 00251184
0.154759
0.0014231

Std. Err.

0.000794315
0.0134422
0.000267497

Lower Conf. Limit

0.000955015
0.128413
0. 000898818

Upper Conf. Limit

0. 00406867
0.181105
0. 00194739

Table of Data and Estimated Values of Interest

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0	5	0.157	0.155	0.05	0.0501	0.1

1	5	0.143	0.156	0.037	0.0501	-0.588
10	5	0.181	0.169	0.053	0.0501	0.536

100	5	0.296	0.297	0.074	0.0501	-0.0477

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

This document is a draft for review purposes only and does not constitute Agency policy.

E-364 DRAFT—DO NOT CITE OR QUOTE


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Model	Log(likelihood)	# Param's	AIC

A1	50.195349	5	-90.390697

A2	51.400051	8	-86.800103

A3	50.195349	5	-90.390697

fitted	49.867385	3	-93.734769

R	41.049755	2	-78.099510

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Test

2

Test

3

Test

4

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	20.7006	6	0.002076

Test 2	2.40941	3	0.4919

Test 3	2.40941	3	0.4919

Test 4	0.655928	2	0.7204

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than .1. A homogeneous variance
model appears to be appropriate here

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adeguately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	35.2176

BMDL =	25.0024

This document is a draft for review purposes only and does not constitute Agency policy.

E-365 DRAFT—DO NOT CITE OR QUOTE


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E.3.20.3. Figure for Selected Model: Linear

Linear Model with 0.95 Confidence Level

dose

17:34 02/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-366 DRAFT—DO NOT CITE OR QUOTE


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E.3.21. Latchoumycandane and Mathur, 2002: Sperm Production

E.3.21.1. Summary Table of BMDS Modeling Results

Model3

Degrees of
Freedom

z2 P-
Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

exponential (M2)

2

<0.0001

95.106

7.640E+01

3.992E+01



exponential (M3)

2

<0.0001

95.106

7.640E+01

3.992E+01

power hit bound (d = 1)

exponential (M4)

1

0.699

75.263

2.435E-01

1.016E-01



exponential (M5)

0

N/A

77.263

3.697E-01

1.016E-01



Hillb

1

0.859

75.144

1.450E-01

1.559E-02

n lower bound hit (n = 1)

linear

2

<0.0001

95.308

8.275E+01

4.852E+01



polynomial, 3-
degree

2

<0.0001

95.308

8.275E+01

4.852E+01



power

2

<0.0001

95.308

8.275E+01

4.852E+01

power bound hit (power =1)

Hill, unrestricted0

0

N/A

77.113

6.943E-02

2.060E-06

unrestricted (n = 0.709)

power, unrestricted

1

0.499

75.570

2.706E-07

2.706E-07

unrestricted (power = 0.067)

a Constant variance model selected (p = 0.8506)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.3.21.2. Output for Selected Model: Hill

Latchoumycandane and Mathur, 2002: Sperm Production

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\1\30_Latch_2002_Sperm_HillCV_l.(d)

Gnuplot Plotting File: C:\l\30_Latch_2002_Sperm_HillCV_l.plt

_Tue Feb 16 18:13:20 2010

(xlO^) Table 1 without Vitamin E

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = Mean
Independent variable = Dose
rho is set to 0

Power parameter restricted to be greater than 1

This document is a draft for review purposes only and does not constitute Agency policy.

E-367 DRAFT—DO NOT CITE OR QUOTE


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A constant variance model is fit

Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

alpha
rho

intercept

7 . 23328

0

22.19
-9.09
1.80484
0. 697086

Specified

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -rho -n

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha
intercept

alpha
1

. 3e-010
3e-008
. 3e-009

intercept
6.3e-010
1

-0.78
-0.23

v

3e-008
-0.78
1

-0.17

k

. 3e-009
-0.23
-0.17
1

Parameter Estimates

Variable
alpha
intercept

k

Estimate

6.03567
22.1885
-9.00869
1

0.386669

Std. Err.
1.74235
1.00316
1.26801
NA

0.265663

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

9.45061
24 .1547
-6.52343

-0.134021

0.907359

NA - Indicates that this parameter has hit a bound
implied by some ineguality constraint and thus
has no standard error.

Table of Data and Estimated Values of Interest

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0

1
10

100

22 . 2
15.7
13.7
13.1

22 . 2
15.7
13.5
13.2

2 . 67
2 . 65
2.19
3.16

2.46
2.46
2.46
2.46

0.00151
-0.0218
0.134
-0.114

Model Descriptions for likelihoods calculated

Model A1:	Yij

Var{e(ij ) }

Mu(i) + e(ij ;
Sigma/N2

This document is a draft for review purposes only and does not constitute Agency policy.

E-368 DRAFT—DO NOT CITE OR QUOTE


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Model A2 :	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma^2
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model

Log(likelihood)

# Param's

AIC

A1

-33.556444

5

77 . 112888

A2

-33.158811

8

82.317623

A3

-33.556444

5

77 . 112888

fitted

-33.572245

4

75.144490

R

-47 . 392394

2

98 .784788

Explanation of Tests

Test 1:

Test 2
Test 3
Test 4
(Note:

Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1
Test 2
Test 3
Test 4

28.4672
0.795266
0.795266
0.031602

<.0001
0.8506
0.8506
0.8589

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than
model appears to be appropriate here

. 1.

homogeneous variance

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adeguately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	0.144988

BMDL =	0.0155926

This document is a draft for review purposes only and does not constitute Agency policy.

E-369 DRAFT—DO NOT CITE OR QUOTE


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E.3.21.3. Figure for Selected Model: Hill

Hill Model with 0.95 Confidence Level

dose

18:13 02/16 2010

E.3.21.4. Output for Additional Model Presented: Hill, Unrestricted
Latchoumycandane and Mathur, 2002: Sperm Production

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\1\30_Latch_2002_Sperm_HillCV_U_l.(d)

Gnuplot Plotting File: C:\l\30_Latch_2002_Sperm_HillCV_U_l.plt

Tue Feb 16 18:13:21 2010

(xl0^6) Table 1 without Vitamin E

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = Mean
Independent variable = Dose
rho is set to 0

Power parameter is not restricted
A constant variance model is fit

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-3 70 DRAFT—DO NOT CITE OR QUOTE


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Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

alpha =	7.23328

rho =	0 Specified

intercept =	22.19

v =	-9.09

n =	1.80484

k =	0.697086

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -rho

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha
intercept

alpha
1

-7 . 6e-009
8e-008
5e-008
1. 9e-008

intercept
-7.6e-009
1

-0.5

-0.015
-0.13

v

8e-008
-0.5

1

0.75
0.55

n

5e-008
-0.015
0.75
1

0.86

k

1.9e-008
-0.13
0.55
0.86
1

Parameter Estimates

Variable
alpha
intercept

Estimate

6.02773
22.19
-9.23433
0.709305
0.290697

Std.
1.
1.

Err.

74006
00231

2.02073
1.28329

0.548737

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

2.61728
20.2255
-13.1949
-1.8059
-0.784807

9. 43818
24 .1545
-5.27378
3.22451
1. 3662

Table of Data and Estimated Values of Interest

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0	6	22.2	22.2	2.67	2.46	2.62e-008

1	6	15.7	15.7	2.65	2.46	-1.5e-008
10	6 13.7	13.7	2.19	2.46	-4.56e-008

100	6 13.1	13.1	3.16	2.46	-3.52e-007

Degrees	of freedom for Test A3 vs fitted <= 0

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

This document is a draft for review purposes only and does not constitute Agency policy.

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Model A2 :	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma^2
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model

Log(likelihood)

# Param's

AIC

A1

-33.556444

5

77 . 112888

A2

-33.158811

8

82.317623

A3

-33.556444

5

77 . 112888

fitted

-33.556444

5

77 . 112888

R

-47 . 392394

2

98 .784788

Explanation of Tests

Test 1:

Test 2
Test 3
Test 4
(Note:

Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1
Test 2
Test 3
Test 4

28.4672
0.795266
0.795266
2.84217e-014

<.0001
0.8506
0.8506
NA

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than
model appears to be appropriate here

.1. A homogeneous variance

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

NA - Degrees of freedom for Test 4 are less than or egual to 0. The Chi-Sguare
test for fit is not valid

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	0.0694325

BMDL = 2.06007e-006

This document is a draft for review purposes only and does not constitute Agency policy.

E-372 DRAFT—DO NOT CITE OR QUOTE


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E.3.21.5. Figure for Additional Model Presented: Hill, Unrestricted

Hill Model with 0.95 Confidence Level

dose

18:13 02/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-3 73 DRAFT—DO NOT CITE OR QUOTE


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E.3.22. Li et al., 1997: FSH

E.3.22.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

exponential (M2)

8

<0.0001

1095.240

1.340E+04

1.060E+04



exponential (M3)

8

<0.0001

1095.240

1.340E+04

1.060E+04

power hit bound (d = 1)

exponential (M4)

7

<0.0001

1061.243

1.031E+03

4.015E+02



exponential (M5)

7

<0.0001

1061.243

1.031E+03

4.015E+02

power hit bound (d = 1)

Hill

7

<0.0001

1059.547

6.645E+02

error

n lower bound hit (n = 1)

linear

8

<0.0001

1078.221

5.287E+03

3.602E+03



polynomial, 8-
degree

9

<0.0001

1155.670

error

error



power b

8

<0.0001

1078.221

5.287E+03

3.602E+03

power bound hit (power = 1)

Hill, unrestricted

6

0.001

1039.902

2.809E+00

6.602E-01

unrestricted (n = 0.291)

power,
unrestricted0

7

0.002

1037.821

2.508E+00

2.525E-01

unrestricted (power = 0.279)

a Non-constant variance model selected (p = <0.0001)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.3.22.2. Output for Selected Model: Power

Li et al., 1997: FSH

Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\1\72_Li_l997_FSH_Pwr_l.(d)

Gnuplot Plotting File: C:\l\72_Li_1997_FSH_Pwr_l.plt

Tue Feb 16 20:07:31 2010

Figure 3: FSH in female S-D rats 24hr after dosing, 22 day old rats

The form of the response function is:

Y[dose] = control + slope * doseApower

Dependent variable = Mean
Independent variable = Dose

The power is restricted to be greater than or egual to 1

This document is a draft for review purposes only and does not constitute Agency policy.

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The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)

Total number of dose groups = 10

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

lalpha
rho
control
slope
power

9.8191

0

22.1591
26.1213
0.264963

Asymptotic Correlation Matrix of Parameter Estimates

lalpha
rho
control
slope

The model parameter(s) -power

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

lalpha
1

-0. 99
-0.29
-0.023

rho

-0. 99
1

0.2
0. 023

control

-0.29
0.2
1

-0.35

slope

-0.023
0. 023
-0.35
1

Parameter Estimates

Variable
lalpha
rho
control
slope
power

Estimate
3.5473
1.26137
88.9479
0. 0188972
1

Std. Err.

1. 23656
0.244246
12 . 9114
0. 00351723
NA

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

1.12369
0.782659
63.6419
0.0120035

5. 9709
1.74009
114.254
0. 0257908

NA - Indicates that this parameter has hit a bound
implied by some ineguality constraint and thus
has no standard error.

Table of Data and Estimated Values of Interest

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0

10

23. 9

cxi

CO
CO

29.6

9 9.9

-2 . 06

3

10

22 . 2

89

48.5

9 9.9

-2 .12

10

10

85.2

89.1

94 . 3

100

-0.124

30

10

73.3

89.5

48.5

100

-0.511

100

10

126

90. 8

159

101

1.1

300

10

132

94 . 6

116

104

1.14

1000

10

117

108

51. 2

113

0.25

3000

10

304

146

154

136

3. 68

le+004

10

347

278

151

205

1. 06

3e+004

10

455

656

286

352

-1. 8

This document is a draft for review purposes only and does not constitute Agency policy.

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Model Descriptions for likelihoods calculated

Model A1:	Yij	= Mu(i) + e(iji

Var{e(ij)} = Sigma/'2

Model A2 :	Yij	= Mu(i) + e(ij|

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model
A1

A2
A3

fitted
R

Log(likelihood)

-535.687163
-496.367061
-502.709623
-535.110448
-574.835246

Param's

11

20

12
4
2

AIC
1093.374327
1032.734122
1029.419246
1078.220896
1153.670492

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

Test 3: Are variances adequately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1

Test 2
Test 3
Test 4

156.936

78 . 6402
12 . 6851
64 .8016

18
9

<.0001
<.0001
0.1232
<.0001

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is less than .1. You may want to try a different
model

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD = 5286.67

This document is a draft for review purposes only and does not constitute Agency policy.

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E'.MDL = 3 6 01.91

E.3.22.3. Figure for Selected Model: Power

Power Model with 0.95 Confidence Level

0	5000	10000	15000	20000	25000	30000

dose

20:07 02/16 2010

E.3.22.4. Output for Additional Model Presented: Power, Unrestricted
Li et al„ 1997: FSH

Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\1\72_Li_l997_FSH_Pwr_U_l.(d)

Gnuplot Plotting File: C:\l\72_Li_1997_FSH_Pwr_U_l.plt

Tue Feb 16 20:07:33 2010

Figure 3: FSH in female S-D rats 24hr after dosing, 22 day old rats

The form of the response function is:
Y[dose] = control + slope * doseApower

Dependent variable = Mean

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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Independent variable = Dose
The power is not restricted

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)

Total number of dose groups = 10

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

lalpha
rho
control
slope
power

9.8191

0

22.1591
26.1213
0.264963

Asymptotic Correlation Matrix of Parameter Estimates

lalpha
rho
control
slope
power

lalpha
1

-0. 99
-0.69
-0.15
0.28

rho

-0. 99
1

0. 65
0.11
-0.26

control

-0.69
0. 65
1

-0.17
0. 024

slope

-0.15
0.11
-0.17
1

-0. 93

power

0.28
-0.26
0. 024
-0. 93
1

Parameter Estimates

Variable
lalpha
rho
control
slope
power

Estimate
3.72156
1.17032
15.7412
24.963
0.278637

Std. Err.

1.13117
0.223249
6.97367
6. 42976
0. 0312355

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

1. 5045
0.732758
2 . 07307
12.3609
0.217417

5.93861

1. 60788
29.4094
37 . 5651
0.339857

Table of Data and Estimated Values of Interest

Table ¦

Dose



0

10

3

10

10

10

30

10

100

10

300

10

1000

10

3000

10

le+004
3e+004

10
10

Obs Mean

23. 9

22 . 2

85.2

73.3
126
132
117
304

347
455

Est Mean Obs Std Dev Est Std Dev Scaled Res.

15.7

49.6
63.2
80.1
106
138
187
248
341
457

29.6
48.5
94 . 3
48.5
159
116
51. 2
154
151
286

32 . 3

63.2
72 . 7
83. 6
98 . 4
115
137
162
195
232

0.796
-1. 38
0. 96
-0.259
0. 654
-0.164
-1. 62
1.1
0 . 0 9 9 9
-0.0271

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(iji

This document is a draft for review purposes only and does not constitute Agency policy.

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Var{e(ij)} = Sigma/N2

Model A2 :	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model
A1

A2
A3

fitted
R

Log(likelihood)

-535.687163
-496.367061
-502.709623
-513.910636
-574.835246

Param's

11

20

12
5
2

AIC
1093.374327
1032.734122
1029.419246
1037.821272
1153.670492

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1

Test 2
Test 3
Test 4

156.936

78 . 6402
12 . 6851
22.402

18
9

<.0001
<.0001
0.1232
0.002165

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is less than .1. You may want to try a different
model

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD = 2.5083 9

BMDL = 0.252541

This document is a draft for review purposes only and does not constitute Agency policy.

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E.3.22.5. Figure for Additional Model Presented: Power, Unrestricted

Power Model with 0.95 Confidence Level

dose

20:07 02/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.3.23. Li et al., 2006: Estradiol, 3-Day

E.3.23.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

X2 P-
Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

exponential (M2)

2

0.147

269.146

3.044E+02

1.108E+02



exponential (M3)

2

0.147

269.146

3.044E+02

1.108E+02

power hit bound (d = 1)

exponential (M4)

1

0.341

268.212

error

error



exponential (M5)

0

N/A

270.212

error

error



Hill

0

N/A

270.212

error

error



linear b

2

0.151

269.084

3.471E+02

1.082E+02



polynomial, 3-
degree

2

0.151

269.084

3.471E+02

1.082E+02



power

2

0.151

269.084

3.471E+02

1.082E+02

power bound hit (power =1)

Hill, unrestricted

0

N/A

270.266

1.059E+17

1.059E+17

unrestricted (n = 0.025)

power,
unrestricted

1

0.327

268.266

3.727E+14

error

unrestricted (power = 0.012)

a Constant variance model selected (p = 0.4372)
b Best-fitting model, BMDS output presented in this appendix

E.3.23.2. Output for Selected Model: Linear

Li et al., 2006: Estradiol, 3-Day

Polynomial Model. (Version: 2.13; Date: 04/08/2008)

Input Data File: C:\1\31_Li_2006_Estra_LinearCV_l.(d)

Gnuplot Plotting File: C:\l\31_Li_2006_Estra_LinearCV_l.plt

Tue Feb 16 18:13:56 2010

Figure 3, 3-day estradiol

The form of the response function is:

Y[dose] = beta_0 + beta_l*dose + beta_2*dose/'2 + ...

Dependent variable = Mean
Independent variable = Dose
rho is set to 0

Signs of the polynomial coefficients are not restricted
A constant variance model is fit

This document is a draft for review purposes only and does not constitute Agency policy.

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Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
alpha =	267 . 211

rho =	0 Specified

beta_0 =	16.4428

beta 1 = 0.0468351

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -rho

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha	beta 0	beta 1

alpha 1	-2.6e-013	-4.5e-015

beta_0 -2.6e-013	1	-0.68

beta 1 -4.5e-015	-0.68	1

Parameter Estimates

Variable
alpha
beta_0
beta 1

Estimate

264.303
16.4428
0.0468351

95.0% Wald Confidence Interval
Std. Err.	Lower Conf. Limit Upper Conf. Limit

59.1	148.469	380.137

3.50431	9.57445	23.3111

0.062677	-0.0760095	0.16968

Table of Data and Estimated Values of Interest

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0	10

2	10

50	10

100	10

10.2
19. 9
24 . 7
18 .1

16.4

16.5
18 . 8
21.1

12 . 2
20
14 . 6
17 . 6

16.3
16.3
16.3
16.3

-1. 22
0. 656
1.16
-0.591

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

This document is a draft for review purposes only and does not constitute Agency policy.

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Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1	-129.653527	5	269.307054

A2	-128.294657	8	272.589314

A3	-129.653527	5	269.307054

fitted	-131.541911	3	269.083823

R	-131.819169	2	267.638338

Explanation of Tests

Test 1:

Test

2

Test

3

Test

4

Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adequately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.'

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	7.04902	6	0.3163

Test 2	2.71774	3	0.4372

Test 3	2.71774	3	0.4372

Test 4	3.77677	2	0.1513

The p-value for Test 1 is greater than .05. There may not be a
diffence between responses and/or variances among the dose levels
Modelling the data with a dose/response curve may not be appropriate

The p-value for Test 2 is greater than .1. A homogeneous variance
model appears to be appropriate here

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adequately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	34 7.12

BMDL =	108.17 3

This document is a draft for review purposes only and does not constitute Agency policy.

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l E.3.23.3. Figure for Selected Model: Linear

Linear Model with 0.95 Confidence Level

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.3.24. Li et al., 2006: Progesterone, 3-Day
E.3.24.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

exponential (M2)

2

<0.001

330.234

5.252E+01

error



exponential (M3)

2

<0.001

330.234

5.252E+01

error

power hit bound (d = 1)

exponential (M4)

b

1

0.384

315.734

1.353E-01

8.351E-02



exponential (M5)

0

N/A

317.734

5.225E-01

7.503E-02



Hill

1

0.386

315.729

1.135E-02

1.161E-05

n lower bound hit (n = 1)

linear

2

<0.001

331.121

7.765E+01

5.264E+01



polynomial, 3-
degree

2

<0.001

331.121

7.765E+01

5.264E+01



power

2

<0.001

331.121

7.765E+01

5.264E+01

power bound hit (power =1)

power,
unrestricted

1

0.405

315.670

1.066E-63

1.066E-63

unrestricted (power = 0.009)

a Non-constant variance model selected (p = 0.0013)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.3.24.2. Output for Selected Model: Exponential (M4)

Li et al., 2006: Progesterone, 3-Day

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\1\32_Li_2006_Progest_Exp_l.(d)

Gnuplot Plotting File:

Tue Feb 16 18:14:31 2010

Figure 4, 3-day progesterone

The form of the response function by Model:

Model 2
Model 3
Model 4
Model 5

Y[dose]
Y[dose]
Y[dose]
Y[dose]

exp{sign *	b * dose}

exp{sign *	(b * dosej^d}

[c-(c-l) *	exp{-b * dose}]

[c-(c-l) *	exp{-(b * dosej^d}

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;
sign = -1 for decreasing trend.

Model 2 is nested within Models 3 and 4.

This document is a draft for review purposes only and does not constitute Agency policy.

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Model 3 is nested within Model 5.
Model 4 is nested within Model 5.

Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)
Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values
Variable	Model 4

lnalpha	11.3313

rho	-1.44835

a	64.8274

b	0.0456906

c	0.166844

d	1

Parameter Estimates
Variable	Model 4

lnalpha	14.074

rho	-2.27065

a	61.7474

b	2.13327

c	0.318566

d	1

Table of Stats From Input	Data

Dose	N	Obs Mean	Obs Std Dev

0	10	61.74	11.1

2	10	30.56	40.48

50	10	16.93	33.3

100	10	11.36	43.75

Estimated Values of	Interest
Dose Est Mean Est Std Scaled Residual

0	61.75	10.55	-0.002085

2	20.26	37.38	0.8713

50	19.67	38.66	-0.224

100	19.67	38.66	-0.6801

Other models for which likelihoods are calculated:

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

This document is a draft for review purposes only and does not constitute Agency policy.

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Model A2 :	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma(i)^2

Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= exp(lalpha + log(mean(i) ) 'k rho)

Model R:

Yij = Mu + e(i)
Var{e(ij)} = Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	DF	AIC

A1	-159.6327	5	329.2653

A2	-151.8128	8	319.6255

A3	-152.4882	6	316.9763

R	-165.6989	2	335.3978

4	-152.8668	5	315.7335

Additive constant for all log-likelihoods =	-36.76. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Test

1:

Test

2 :

Test

3:

Does response and/or variances differ among Dose levels:

Are Variances Homogeneous? (A2 vs. A1)

Are variances adeguately modeled? (A2 vs. A3)

(A2 vs. R)

Test

Does Model 4 fit the data? (A3 vs 4)

Tests of Interest
Test	-2*log(Likelihood Ratio)	D. F.	p-value

Test 1	27.77	6	0.0001037

Test 2	15.64	3	0.001344

Test 3	1.351	2	0.5089

Test 6a	0.7572	1	0.3842

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose
levels, it seems appropriate to model the data.

The p-value for Test 2 is less than .1. A non-homogeneous
variance model appears to be appropriate.

The p-value for Test 3 is greater than .1. The modeled
variance appears to be appropriate here.

The p-value for Test 6a is greater than .1. Model 4 seems
to adeguately describe the data.

Benchmark Dose Computations:

Specified Effect = 1.000000

Risk Type = Estimated standard deviations from control
Confidence Level = 0.950000

BMD =	0.135296

BMDL = 0.0835054

This document is a draft for review purposes only and does not constitute Agency policy.

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E.3.24.3. Figure for Selected Model: Exponential (M4)

Exponential_beta Model 4 with 0.95 Confidence Level

60

40

20

-20

Exponential

VIDL

BMD

20

40

60

80

100

dose

18:14 02/16 2010

E.3.24.4. Output for Additional Model Presented: Hill, Unrestricted

Li et al., 2006: Progesterone, 3-Day

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\1\32_Li_2006_Progest_Hill_U_l.(d)

Gnuplot Plotting File: C:\l\32_Li_2 006_Progest_Hill_U_l.plt

Tue Feb 16 18:14:41 2010

Figure 4, 3-day progesterone

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = Mean
Independent variable = Dose
Power parameter is not restricted

The variance is to be modeled as Var(i) = exp(lalpha + rho * In(mean(i)))

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

lalpha =	7.08699

rho =	0

intercept =	61.7404

v =	-50.3835

n =	1.43997

k =	1.6159

Asymptotic Correlation Matrix of Parameter Estimates

lalpha
rho

intercept

The model parameter(s) -k

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

lalpha
1

-0. 99
-0.097
0.84

NA

rho

-0. 99
1

0.13
-0. 81
NA

intercept

-0.097
0.13
1

-0.43
NA

v

0.84
-0. 81
-0.43
1

NA

NA

NA
NA
NA

NA - This parameter's variance has been estimated as zero or less.
THE MODEL HAS PROBABLY NOT CONVERGED!!!

Parameter Estimates

95.0% Wald Confidence Interval

Variable
lalpha
rho

intercept

k

Estimate

13.9863
-2 . 25026
61. 7404
-42 .1239
2.02774
le-013

Std.

Err.

NA
NA
NA
NA
NA
NA

Lower Conf.

Limit

NA
NA
NA
NA
NA

Upper Conf.

Limit

NA
NA
NA
NA
NA

At least some variance estimates are negative.
THIS USUALLY MEANS THE MODEL HAS NOT CONVERGED!
Try again from another starting point.

Table of Data and Estimated Values of Interest

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0
2
50
100

10
10
10
10

61. 7

30. 6
16. 9
11. 4

61. 7

19.6
19.6
19.6

11.1
40.5
33.3
43.7

10.5

38 . 3
38 . 3
38 . 3

9 . 7 4e-008

0. 905
-0.222
-0.683

This document is a draft for review purposes only and does not constitute Agency policy.

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Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2 :	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model
A1

A2
A3

fitted
R

Log(likelihood)

-159.632675
-151.812765
-152.488175
-152.873643
-165.698875

Param's
5

AIC
329.265349
319.625529
316.976349
315.747285
335.397750

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

Test 3: Are variances adequately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1

Test 2
Test 3
Test 4

0.0001037
0.001344
0.5089
0.3799

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adequately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD = 5.817 03e-014

This document is a draft for review purposes only and does not constitute Agency policy.

E-390 DRAFT—DO NOT CITE OR QUOTE


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BMDL = 5.817 03e-014

5 E.3.24.5. Figure for Additional Model Presented: Hill, Unrestricted

Hill Model with 0.95 Confidence Level

a>

CO
c
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Q.
CO
(D

(Z
c
(0
(D

18:14 02/16 2010

This document is a draft for review purposes only and does not constitute Agency policy.

E-391 DRAFT—DO NOT CITE OR QUOTE


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E.3.25. Markowski et al., 2001: FRIO Run Opportunities
E.3.25.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

r p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

exponential
(M2)b

2

0.248

117.557

1.653E+02

5.025E+01



exponential (M3)

2

0.248

117.557

1.653E+02

5.025E+01

power hit bound (d = 1)

exponential (M4)

1

0.412

117.445

4.742E+01

1.729E-01



exponential (M5)

0

N/A

118.918

3.178E+01

3.967E-05



Hill

0

N/A

118.918

2.348E+01

6.728E-06



linear

2

0.190

118.089

2.081E+02

1.051E+02



polynomial, 3-
degree

2

0.190

118.089

2.081E+02

1.051E+02



power

2

0.190

118.089

2.081E+02

1.051E+02

power bound hit (power = 1)

power,
unrestricted

1

0.238

118.164

9.153E+01

5.911E-07

unrestricted (power = 0.237)

a Constant variance model selected (p = 0,1719)
b Best-fitting model, BMDS output presented in this appendix

E.3.25.2. Output for Selected Model: Exponential (M2)

Markowski et al., 2001: FR10 Run Opportunities

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\1\33_Mark_2001_FR10opp_ExpCV_l.(d)

Gnuplot Plotting File:

Tue Feb 16 18:15:26 2010

Table 3

The form of the response function by Model:

Model 2
Model 3
Model 4
Model 5

Y[dose]
Y[dose]
Y[dose]
Y[dose]

exp{sign *	b * dose}

exp{sign *	(b * dosej^d}

[c-(c-l) *	exp{-b * dose}]

[c-(c-l) *	exp{-(b * dosej^d}

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;
sign = -1 for decreasing trend.

Model 2 is nested within Models 3 and 4.
Model 3 is nested within Model 5.

Model 4 is nested within Model 5.

This document is a draft for review purposes only and does not constitute Agency policy.

E-392 DRAFT—DO NOT CITE OR QUOTE


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Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))
rho is set to 0.

A constant variance model is fit.

Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values
Variable	Model 2

Specified

lnalpha	3.5321

rho(S)	0

a	6.98169

b	0.00309891

c	0

d	1

Parameter Estimates
Variable	Model 2

lnalpha	3.64 823

rho	0

a	11.9443

b	0.0044262

c	0

d	1

Table of Stats From Input Data

Dose	N	Obs Mean	Obs Std Dev

0	7	13.29	8.65

20	4	11.25	5.56

60	6	5.75	3.53

180	7	7	6.01

Estimated Values of Interest
Dose	Est Mean	Est Std	Scaled Residual

0	11.94	6.197	0.5745

20	10.93	6.197	0.1025

60	9.158	6.197	-1.347

180	5.385	6.197	0.6897

Other models for which likelihoods are calculated:

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

This document is a draft for review purposes only and does not constitute Agency policy.

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Model A2 :	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma(i)^2

Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= exp(lalpha + log(mean(i) ) 'k rho)

Model R:	Yij	= Mu + e(i)

Var{e(ij)}	= Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	DF	AIC

A1	-54.38526	5	118.7705

A2	-51.88568	8	119.7714

A3	-54.38526	5	118.7705

R	-57.45429	2	118.9086

2	-55.77871	3	117.5574

Additive constant for all log-likelihoods =	-22.05. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Test

1:

Test

2 :

Test

3:

Test

4 :

Does response and/or variances differ among Dose levels:
Are Variances Homogeneous? (A2 vs. A1)

Are variances adeguately modeled? (A2 vs. A3)

Does Model 2 fit the data? (A3 vs. 2)

(A2 vs. R)

Test

Test 1
Test 2
Test 3
Test 4

Tests of Interest
-2*log(Likelihood Ratio)

11.14

4.999
4.999
2.787

p-value

0.08423
0.1719
0.1719
0.2482

The p-value for Test 1 is greater than .05. There may not be a
diffence between responses and/or variances among the dose levels
Modelling the data with a dose/response curve may not be appropriate.

The p-value for Test 2 is greater than .1. A homogeneous
variance model appears to be appropriate here.

The p-value for Test 3 is greater than .1. The modeled
variance appears to be appropriate here.

The p-value for Test 4 is greater than .1. Model 2 seems
to adeguately describe the data.

Benchmark Dose Computations:

Specified Effect = 1.000000

Risk Type = Estimated standard deviations from control
Confidence Level = 0.950000

BMD =	165.284

BMDL =	5 0.24 88

This document is a draft for review purposes only and does not constitute Agency policy.

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E.3.25.3. Figure for Selected Model: Exponential (M2)

Exponential_beta Model 2 with 0.95 Confidence Level

dose

18:15 02/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.3.26. Markowski et al., 2001: FR2 Revolutions

E.3.26.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

exponential (M2)

2

0.192

217.636

1.627E+02

5.807E+01



exponential (M3)

2

0.192

217.636

1.627E+02

5.807E+01

power hit bound (d = 1)

exponential (M4)

1

0.298

217.415

4.668E+01

1.965E-01



exponential (M5)

0

N/A

218.532

3.308E+01

1.193E+01



Hill b

0

N/A

218.532

2.364E+01

7.336E+00

n upper bound hit (n = 18)

linear

2

0.150

218.129

1.989E+02

1.025E+02



polynomial, 3-
degree

2

0.150

218.129

1.989E+02

1.025E+02



power

2

0.150

218.129

1.989E+02

1.025E+02

power bound hit (power =1)

power,
unrestricted0

1

0.160

218.302

9.101E+01

1.800E-13

unrestricted (power = 0.272)

a Constant variance model selected (p = 0.1092)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.3.26.2. Output for Selected Model: Hill

Markowski et al., 2001: FR2 Revolutions

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\1\34_Mark_2001_FR2rev_HillCV_l.(d)

Gnuplot Plotting File: C:\l\34_Mark_2001_FR2rev_HillCV_l.plt

Tue Feb 16 18:16:03 2010

Table 3

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = Mean
Independent variable = Dose
rho is set to 0

Power parameter restricted to be greater than 1
A constant variance model is fit

This document is a draft for review purposes only and does not constitute Agency policy.

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Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

alpha =	2598 . 74

rho =	0 Specified

intercept =	119.29

v =	-62.79

n =	1.80602

k =	35.85

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -rho

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha
intercept

alpha
1

-8 . le-009
4 . 5e-008
-3e-005
3e-005

intercept
-8 . le-009
1

-0. 81
-0.00013
-0.0022

v

4 . 5e-008
-0. 81
1

0.0002
0.0014

n

-3e-005
-0. 00013
0.0002
1
-1

k

3e-005
-0.0022
0.0014
-1
1

Parameter Estimates

Variable
alpha
intercept

Estimate
2183.85
119.29
-56.5223
18

21.6708

Std. Err.
630.425
17 . 6629
21.9082
8854.08
855.263

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

948.245
84.6713
-99.4615
-17335.7
-1654.61

3419.46

153.909
-13.5831
17371.7
1697.95

Table of Data and Estimated Values of Interest
5	N Obs Mean	Est Mean Obs Std Dev Est Std Dev Scaled Res.

0	7 119	119 69.9	46.7	2.74e-008

20	4 109	108 61	46.7	8.42e-010

60	6 56.5	62.8 31.2	46.7	-0.329

180	7 68.1	62.8 33.2	46.7	0.304

Degrees	of freedom for Test A3 vs fitted <= 0

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij)

This document is a draft for review purposes only and does not constitute Agency policy.

E-397 DRAFT—DO NOT CITE OR QUOTE


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Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma^2
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1 -104.165520	5	218.331040

A2 -101.140174	8	218.280349

A3 -104.165520	5	218.331040

fitted -104.266162	5	218.532324

R -107.599268	2	219.198536

Explanation of Tests

Test

1

Test

2

Test

3

Test

4

Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

Test 1
Test 2
Test 3
Test 4

-2*log(Likelihood Ratio)

12.9182
6.05069
6.05069
0.201283

Test df

p-value

0.04435
0.1092
0.1092
NA

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than .1.
model appears to be appropriate here

A homogeneous variance

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

NA - Degrees of freedom for Test 4 are less than or egual to 0. The Chi-Sguare
test for fit is not valid

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	23.6366

BMDL =	7.33648

This document is a draft for review purposes only and does not constitute Agency policy.

E-398 DRAFT—DO NOT CITE OR QUOTE


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E.3.26.3. Figure for Selected Model: Hill

Hill Model with 0.95 Confidence Level

200

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80 100
dose

120

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180

18:16 02/16 2010

E.3.26.4. Output for Additional Model Presented: Power, Unrestricted
Markowski et al., 2001: FR2 Revolutions

Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\1\34_Mark_2001_FR2rev_PowerCV_U_l.(d)

Gnuplot Plotting File: C:\l\34_Mark_2001_FR2rev_PowerCV_U_l.plt

Tue Feb 16 18:16:04 2010

Table 3

The form of the response function is:
Y[dose] = control + slope * doseApower

Dependent variable = Mean
Independent variable = Dose
rho is set to 0
The power is not restricted
A constant variance model is fit

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-399 DRAFT—DO NOT CITE OR QUOTE


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Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

alpha
rho
control
slope
power

2598.74

0 Specified
119.29
-1.79436
0.708231

Asymptotic Correlation Matrix of Parameter Estimates

alpha
control

The model parameter(s) -rho

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha
1

9 . 7e-009

control
9 . 7e-009
1

slope
-1. 9e-008
-0.49

power
-1. 6e-008
-0.28

slope -1.9e-008	-0.49	1	0.96

power -1.6e-008	-0.28	0.96	1

Parameter Estimates

Variable
alpha
control
slope
power

Estimate

2351
120.074
-14.1965
0.27229

Std. Err.

678.674
18 . 0837
22 .2073
0.301344

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

1020.82
84.6305
-57.722
-0.318334

3681.17
155.517
29.329
0. 862913

Table of Data and Estimated Values of Interest

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0	7	119	120	69.9	48.5	-0.0428

20	4	109	88	61	48.5	0.846

60	6	56.5	76.8	31.2	48.5	-1.02

180	7	68.1	61.7	33.2	48.5	0.352

Model Descriptions for likelihoods calculated

Model A1:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma/'2

Model A2:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma(i)^2

Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma/'2
Model A3 uses any fixed variance parameters that

This document is a draft for review purposes only and does not constitute Agency policy.

E-400 DRAFT—DO NOT CITE OR QUOTE


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were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1 -104.165520	5	218.331040

A2 -101.140174	8	218.280349

A3 -104.165520	5	218.331040

fitted -105.151136	4	218.302271

R -107.599268	2	219.198536

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Test

2

Test

3

Test

4

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	12.9182	6	0.04435

Test 2	6.05069	3	0.1092

Test 3	6.05069	3	0.1092

Test 4	1.97123	1	0.1603

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than .1. A homogeneous variance
model appears to be appropriate here

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adeguately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD = 91.0145

BMDL = 1.8e-013

This document is a draft for review purposes only and does not constitute Agency policy.

E-401 DRAFT—DO NOT CITE OR QUOTE


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E.3.26.5. Figure for Additional Model Presented: Power, Unrestricted

Power Model with 0.95 Confidence Level

dose

18:16 02/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-402 DRAFT—DO NOT CITE OR QUOTE


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E.3.27. Markowski et al., 2001: FR5 Run Opportunities
E.3.27.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

exponential (M2)

2

0.149

133.830

9.491E+01

4.324E+01



exponential (M3)

2

0.149

133.830

9.491E+01

4.324E+01

power hit bound (d = 1)

exponential (M4)

1

0.303

133.087

2.961E+01

9.356E+00



exponential (M5)

0

N/A

134.032

2.871E+01

1.226E+01



Hill b

1

0.939

132.032

2.214E+01

1.117E+01

n upper bound hit (n = 18)

linear

2

0.091

134.825

1.349E+02

8.118E+01



polynomial, 3-
degree

2

0.091

134.825

1.349E+02

8.118E+01



power

2

0.091

134.825

1.349E+02

8.118E+01

power bound hit (power =1)

power,
unrestricted0

1

0.133

134.281

3.721E+01

1.439E-07

unrestricted (power = 0.336)

a Constant variance model selected (p = 0.2262)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.3.27.2. Output for Selected Model: Hill

Markowski et al., 2001: FR5 Run Opportunities

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\1\35_Mark_2001_FR5opp_HillCV_l.(d)

Gnuplot Plotting File: C:\l\35_Mark_2001_FR5opp_HillCV_l.plt

Tue Feb 16 18:16:39 2010

Table 3

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = Mean
Independent variable = Dose
rho is set to 0

Power parameter restricted to be greater than 1
A constant variance model is fit

This document is a draft for review purposes only and does not constitute Agency policy.

E-403 DRAFT—DO NOT CITE OR QUOTE


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Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

alpha =	77.4849

rho =	0 Specified

intercept =	26.14

v =	-13.34

n =	2.36002

k =	35.0654

Asymptotic Correlation Matrix of Parameter Estimates

alpha
intercept

The model parameter(s) -rho -n

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha
1

-3.6e-009
9 . 8e-009
3. 6e-008

intercept
-3.6e-009
1

-0. 81
-0.51

v

9 . 8e-009
-0. 81
1

0.36

k

3. 6e-008
-0.51
0.36
1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
alpha
intercept

k

Estimate

64 . 5863
26.14
-13.1569
18

21.5963

Std. Err.

18 . 6445
3. 03753
3.7676
NA

2 . 68136

Lower Conf. Limit

28.0438
20.1865
-20.5413

16.3409

Upper Conf. Limit

101.129
32 .0935
-5.77257

26.8517

NA - Indicates that this parameter has hit a bound
implied by some ineguality constraint and thus
has no standard error.

Table of Data and Estimated Values of Interest

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0	7	26.1	26.1	12.3	8.04	1.02e-008

20	4	23.5	23.5	7.04	8.04	-1.39e-007

60	6	12.8	13	6.17	8.04	-0.0558

180	7	13.1	13	7.14	8.04	0.0517

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(iji

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij|

This document is a draft for review purposes only and does not constitute Agency policy.

E-404 DRAFT—DO NOT CITE OR QUOTE


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Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma^2
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1 -62.013133	5	134.026266

A2 -59.839035	8	135.678070

A3 -62.013133	5	134.026266

fitted -62.016024	4	132.032049

R -67.530040	2	139.060081

Explanation of Tests

Test

1

Test

2

Test

3

Test

4

Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio)

Test df

p-value

Test 1
Test 2
Test 3
Test 4

15.382
4.3482
4.3482
0.0057833

0.01748
0.2262
0.2262
0.9394

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than .1.
model appears to be appropriate here

A homogeneous variance

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adeguately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	22.14 4

BMDL =	11.165

This document is a draft for review purposes only and does not constitute Agency policy.

E-405 DRAFT—DO NOT CITE OR QUOTE


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l E.3.27.3. Figure for Selected Model: Hill

Hill Model with 0.95 Confidence Level

a>

CO
c
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Q.

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CD

a:

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15 - -L

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18:16 02/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.3.27.4. Output for Additional Model Presented: Power, Unrestricted
Markowski et al., 2001: FR5 Run Opportunities

Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\1\35_Mark_2001_FR5opp_PwrCV_U_l.(d)

Gnuplot Plotting File: C:\l\35_Mark_2001_FR5opp_PwrCV_U_l.plt

Tue Feb 16 187l6:40 2010

Table 3

The form of the response function is:
Y[dose] = control + slope * doseApower

Dependent variable = Mean
Independent variable = Dose
rho is set to 0
The power is not restricted
A constant variance model is fit

Total number of dose groups = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial
alpha =
rho =
control =
slope =
power =

Parameter Values
77.4849

0 Specified
26.14
-0.39517
0.725538

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -rho

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha
control

alpha
1

7 . 4e-009

control
7 . 4e-009
1

slope
4.3e-008
-0.51

power
4 . 8e-008
-0.34

slope	4.3e-008	-0.51	1	0.97

power	4.8e-008	-0.34	0.97	1

Parameter Estimates

95.0% Wald Confidence Interval

Variable Estimate Std. Err.	Lower Conf. Limit	Upper Conf. Limit

alpha 70.9323 20.4764	30.7993	111.065

control 26.3567 3.13032	20.2213	32.492

slope -2.49841 3.16984	-8.71118	3.71437

power 0.336003 0.242031	-0.138368	0.810375

This document is a draft for review purposes only and does not constitute Agency policy.

E-407 DRAFT—DO NOT CITE OR QUOTE


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Table of Data and Estimated Values of Interest

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0
20
60
180

26.1

23.5
12 . 8
13.1

26.4

19.5
16.5
12 .1

12 . 3
7 . 04
6.17
7 .14

} .42

J .42
J .42
} .42

-0.0681
0. 945
-1. 07
0.341

Model Descriptions for likelihoods calculated

Model A1:	Yij

Var{e(ij ) }

Mu(i) + e(ij ;
Sigma/N2

Model A2:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi

Var{e(i)}

Mu + e(i)
Sigma/N2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1 -62.013133	5	134.026266

A2 -59.839035	8	135.678070

A3 -62.013133	5	134.026266

fitted -63.140714	4	134.281428

R -67.530040	2	139.060081

Explanation of Tests

Test 1:

Test 2
Test 3
Test 4
(Note:

Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1

Test 2
Test 3
Test 4

15.382
4.3482
4.3482
2 . 25516

0.01748
0.2262
0.2262
0.1332

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than
model appears to be appropriate here

.1. A homogeneous variance

The p-value for Test 3 is greater than
to be appropriate here

.1. The modeled variance appears

This document is a draft for review purposes only and does not constitute Agency policy.

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The p-value for Test 4 is greater than .1. The model chosen seems
to adequately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD = 37.2131

BMDL = 1.4 3 92 6e-007

E.3.27.5. Figure for Additional Model Presented: Power, Unrestricted

CD
CO
c
o

Q.

CO
CD

a:

c
m

CD

Power Model with 0.95 Confidence Level

20

40

60

80 100
dose

120

140

160

180

18:16 02/16 2010

This document is a draft for review purposes only and does not constitute Agency policy.

E-409 DRAFT—DO NOT CITE OR QUOTE


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E.3.28. Miettinen et al., 2006: Cariogenic Lesions, Pups
E.3.28.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

gamma

3

0.345

162.699

7.505E+01

4.086E+01

power bound hit (power = 1)

logistic

3

0.315

162.909

8.991E+01

5.250E+01



log-logistica

3

0.506

161.767

3.130E+01

1.054E+01

slope bound hit (slope = 1)

log-probit

3

0.257

163.393

1.390E+02

6.729E+01

slope bound hit (slope =1)

multistage, 4-
degree

3

0.345

162.699

7.505E+01

4.086E+01

final B = 0

probit

3

0.299

163.031

9.941E+01

6.208E+01



Weibull

3

0.345

162.699

7.505E+01

4.086E+01

power bound hit (power = 1)

gamma,
unrestricted

2

0.797

161.805

1.591E-02

1.335E-
240

unrestricted (power = 0.184)

log-logistic,
unrestricted b

2

0.723

161.998

3.713E-01

error

unrestricted (slope = 0.403)

log-probit,
unrestricted

2

0.726

161.987

5.098E-01

error

unrestricted (slope = 0.25)

Weibull,
unrestricted

2

0.761

161.897

1.174E-01

error

unrestricted (power = 0.281)

a Best-fitting model, BMDS output presented in this appendix
b Alternate model, BMDS output also presented in this appendix

E.3.28.2. Output for Selected Model: Log-Logistic

Miettinen et al., 2006: Cariogenic Lesions, Pups

Logistic Model. (Version: 2.12; Date: 05/16/2008)

Input Data File: C:\1\36_Miet_2006_Cariogenic_LogLogistic_l.(d)

Gnuplot Plotting File: C:\l\36_Miet_2006_Cariogenic_LogLogistic_l.plt

Tue Feb 16 18:17:16 2010

Table 2 converting the percentage into the number of animals, and control is Control II from the
study. Dose is in ng per kg and is from Table 1

The form of the probability function is:

P[response] = background+(1-background)/[1+EXP(-intercept-slope*Log(dose))]

Dependent variable = DichEff

This document is a draft for review purposes only and does not constitute Agency policy.

E-410 DRAFT—DO NOT CITE OR QUOTE


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Independent variable = Dose

Slope parameter is restricted as slope >= 1
Total number of observations = 5

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

User has chosen the log transformed model

Default Initial Parameter Values
background =	0.595238

intercept =	-5.52519

slope =	1

Asymptotic Correlation Matrix of Parameter Estimates

The model parameter(s) -slope

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

background intercept
background	1	-0.64

intercept	-0.64	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

background	0.658158	*	*	*

intercept	-5.64068	*	*	*

slope	1	*	*	*

Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-77.6769	5

Fitted model -78.8837 2	2.41374 3 0.4911

Reduced model -83.2067 1	11.0597 4 0.0259

AIC:	161.767

Goodness of Fit

Scaled

Dose	Est. Prob. Expected Observed	Size	Residual

0.0000

0

6582

27 . 643

25.000

42

-0

860

30.0000

0

6911

20.041

23.000

29

1

189

100.0000

0

7477

18.693

19.000

25

0

141

300.0000

0

8345

20.027

20.000

24

-0

015

1000.0000

0

924 9

29.596

29.000

32

-0

400

Chi ^2 = 2.33



d.f.

= 3 P

-value = 0.5062







Benchmark Dose Computation

This document is a draft for review purposes only and does not constitute Agency policy.

E-411 DRAFT—DO NOT CITE OR QUOTE


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Specified effect =
Risk Type	=

Confidence level =

0.1
Extra risk
0. 95

BMD =	31.2951

BMDL =	10.5354

E.3.28.3. Figure for Selected Model: Log-Logistic

Log-Logistic Model with 0.95 Confidence Level

dose

18:17 02/16 2010

E.3.28.4. Output for Additional Model Presented: Log-Logistic, Unrestricted
Miettinen et al., 2006: Cariogenic Lesions, Pups

Logistic Model. (Version: 2.12; Date: 05/16/2008)

Input Data File: C:\1\36_Miet_2006_Cariogenic_LogLogistic_U_l.(d)

Gnuplot Plotting File: C:\l\36_Miet_2006_Cariogenic_LogLogistic_U_l.plt

Tue Feb 16 18:17:18 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-412 DRAFT—DO NOT CITE OR QUOTE


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65

66

67

68

69

70

Table 2 converting the percentage into the number of animals, and control is Control II from the
study. Dose is in ng per kg and is from Table 1

The form of the probability function is:

P[response] = background+(1-background)/[1+EXP(-intercept-slope*Log(dose))]

Dependent variable = DichEff
Independent variable = Dose
Slope parameter is not restricted

Total number of observations = 5

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

User has chosen the log transformed model

Default Initial Parameter Values

background =	0.595238

intercept =	-1.68849

slope =	0.382632

Asymptotic Correlation Matrix of Parameter Estimates
background intercept	slope

background	1	-0.41	0.24

intercept	-0.41	1	-0.96

slope	0.24	-0.96	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

background	0.597778	*	*	*

intercept	-1.79836	*	*	*

slope	0.402606	*	*	*

Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-77.6769	5

Fitted model -77.9988 3	0.643944 2	0.7247

Reduced model -83.2067 1	11.0597 4	0.0259

AIC:	161.998

Goodness of Fit

Scaled

Dose	Est. Prob. Expected Observed	Size	Residual

0.0000	0.5978	25.107 25.000	42	-0.034

30.0000	0.7564	21.936 23.000	29	0.460

This document is a draft for review purposes only and does not constitute Agency policy.

E-413 DRAFT—DO NOT CITE OR QUOTE


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100.0000	0.8045

300.0000	0.8480

1000.0000	0.8905

Chi ^2

0. 65

d. f.

2

20.112 19.000
20.351 20.000
28.495 29.000

P-value = 0.7227

25
24
32

-0.561
-0.200
0.286

Benchmark Dose Computation
Specified effect =	0.1

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	0.371315

Benchmark dose computation failed. Lower limit includes zero.

E.3.28.5. Figure for Additional Model Presented: Log-Logistic, Unrestricted

Log-Logistic Model

"O

(D

-t—<

o

CD
!t=
<

0.9

0.7

0.6

0.5

0.4

18:17 02/16 2010

200

400

600

800

1000

dose

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-414 DRAFT—DO NOT CITE OR QUOTE


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E.3.29. Murray et al., 1979: Fertility in F2 Generation
E.3.29.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

X2 P-
Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

gamma

0

N/A

61.729

7.016E+00

1.698E+00



logistic

1

0.072

60.497

4.007E+00

2.836E+00

negative intercept (intercept = -
2.53)

log-logistic

0

N/A

61.729

7.902E+00

1.584E+00



multistage, 1-
degree

1

0.053

61.644

2.380E+00

1.320E+00



multistage, 2-
degreea

1

0.094

59.935

4.548E+00

1.635E+00



probit

1

0.070

60.613

3.707E+00

2.615E+00

negative intercept (intercept = -
1.446)

Weibull

0

N/A

61.729

8.115E+00

1.698E+00



log-probit,
unrestricted

0

N/A

61.729

6.373E+00

1.503E+00

unrestricted (slope = 2.306)

a Best-fitting model, BMDS output presented in this appendix

E.3.29.2. Output for Selected Model: Multistage, 2-Degree

Murray et al., 1979: Fertility in F2 Generation

Multistage Model. (Version: 3.0; Date: 05/16/2008)

Input Data File: C:\l\Murray_l979_fert_index_f2_Multi2_l.(d)

Gnuplot Plotting File: C:\l\Murray_197 9_fert_index_f2_Multi2_l.plt

Tue Feb 16 20:08:06 2010

Table 1 but expressed as number of dams who do not produce offspring

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal*dose/Nl-beta2*dose/N2 ) ]

The parameter betas are restricted to be positive

Dependent variable = DichEff
Independent variable = Dose

Total number of observations = 3

Total number of records with missing values = 0
Total number of parameters in model = 3
Total number of specified parameters = 0
Degree of polynomial = 2

This document is a draft for review purposes only and does not constitute Agency policy.

E-415 DRAFT—DO NOT CITE OR QUOTE


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65

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68

69

70

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background = 0.0624181
Beta(1) =	0

Beta(2) = 0.00532688

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -Beta(l)

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Background	Beta(2)

Background	1	-0.44

Beta(2)	-0.44	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0.0772201	*	*	*

Beta (1)	0	*	*	*

Beta(2)	0.00509404	*	*	*

* - Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-25.8194	3

Fitted model -27.9673 2	4.29584 1 0.03821

Reduced model -34.0009 1	16.363 2 0.0002798

AIC:	59.9347

Goodness of Fit

Scaled

Est. Prob. Expected Observed	Size	Residual

0.0000

0.0772

2 .471

4 . 000

32

1. 013

1.0000

0.0819

1. 638

0. 000

20

-1. 336

10.0000

0.4455

8 . 911

9. 000

20

0. 040

Chi ^2 = 2.81	d.f. = 1	P-value = 0.0936

Benchmark Dose Computation
Specified effect =	0.1

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	4.54787

This document is a draft for review purposes only and does not constitute Agency policy.

E-416 DRAFT—DO NOT CITE OR QUOTE


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E'.MDL =

1.63487

E'.MDU =	6.7 9105

Taken together, (1.63487, 6.79105) is a 90	% two-sided confidence

interval for the EMD

E.3.29.3. Figure for Selected Model: Multistage, 2-Degree

Multistage Model with 0.95 Confidence Level

dose

20:08 02/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-417 DRAFT—DO NOT CITE OR QUOTE


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E.3.30. National Toxicology Program, 1982: Toxic Hepatitis, Male Mice
E.3.30.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

gamma

1

0.026

113.097

1.552E+01

5.155E+00



logistic

2

0.093

110.712

1.769E+01

1.383E+01

negative intercept (intercept =
-3.087)

log-logistic

1

0.027

113.093

1.499E+01

6.628E+00



log-probit

1

0.027

113.111

1.360E+01

7.237E+00



multistage, 3-
degreea

1

0.028

112.555

1.488E+01

4.676E+00



probit

2

0.088

110.696

1.564E+01

1.261E+01

negative intercept (intercept =
-1.731)

Weibull

1

0.026

113.056

1.619E+01

4.903E+00



a Best-fitting model, BMDS output presented in this appendix

E.3.30.2. Output for Selected Model: Multistage, 3-Degree

National Toxicology Program, 1982: Toxic Hepatitis, Male Mice



Multistage Model.

. (Version: 3.0;

: Date: 05/16/2008)



Input Data File:

C:\l\37 NTP 19E

32 ToxHep Multi3 1.(d)



Gnuplot Plotting

File: C:\l\37

NTP 1982 ToxHep Multi3 l.plt

Tue Feb 16 18:17:51 2010

0

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(

-betal*dose/Nl-beta2*dose/N2-beta3*dose/N3) ]

The parameter betas are restricted to be positive

Dependent variable = DichEff
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 4
Total number of specified parameters = 0
Degree of polynomial = 3

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008

This document is a draft for review purposes only and does not constitute Agency policy.

E-418 DRAFT—DO NOT CITE OR QUOTE


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Parameter

has been set to: le-008

Default Initial Parameter Values

Background = 0.0525767
Beta(1) = 0.00243254
Beta(2) =	0

Beta(3) = 5.29052e-006

Asymptotic Correlation Matrix of Parameter Estimates

Background
Beta(1)
Beta(3)

The model parameter(s) -Beta(2)

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Background
1

-0.69
0. 66

Beta(1)

-0.69
1

-0. 98

Beta(3)

0. 66
-0. 98
1

Parameter Estimates

Variable
Background
Beta(1)
Beta(2)
Beta(3)

Estimate

0.0383474
0.00605732
0

.60855e-006

Std. Err.

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

Indicates that this value is not calculated.

Analysis of Deviance Table

Model
Full model
Fitted model
Reduced model

Log(likelihood)

-51.0633
-53.2776
-121.743

Param's

4
3
1

Deviance Test d.f.

4.42854
141.358

P-value

0.03534
<.0001

AIC:

112.555

Dose

Goodness of Fit

Est. Prob.

Expected

Observed

Scaled
Residual

0.0000
1.4000
7.1000
71.0000

0.0383
0.0465
0.0803
0.8798

2.799

2.278
3. 937
43.990

1. 000
5. 000
3. 000
44.000

73

49

49

50

-1.097

1.847
-0.492
0. 004

Chi ^2

4 .86

d.f.

P-value

0. 0275

Benchmark Dose Computation
Specified effect =	0.1

Risk Type	=	Extra risk

Confidence level =	0.95

This document is a draft for review purposes only and does not constitute Agency policy.

E-419 DRAFT—DO NOT CITE OR QUOTE


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BMD =

14.8848

E'.MDL =	4.67636

BMDLJ =	28.8293

Taken together, (4.67636,	28.8293) is a 90
interval for the EMD

two'-sided oorifidenoe

E.3.30.3. Figure for Selected Model: Multistage, 3-Degree

Multistage Model with 0.95 Confidence Level

"O

(D

-t—<

o

(U
!t=
<

0.6

0.4

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0 -

18:17 02/16 2010

This document is a draft for review purposes only and does not constitute Agency policy.

E-420 DRAFT—DO NOT CITE OR QUOTE


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E.3.31. National Toxicology Program, 2006: Alveolar Metaplasia
E.3.31.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

r p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

gamma

4

<0.001

340.127

2.240E+00

1.791E+00

power bound hit (power =1)

logistic

4

<0.001

358.346

4.997E+00

4.149E+00

negative intercept (intercept =
-0.687)

log-logistica

4

0.409

312.970

6.644E-01

5.041E-01

slope bound hit (slope = 1)

log-probit

4

<0.001

340.296

3.291E+00

2.517E+00

slope bound hit (slope =1)

multistage, 5-
degree

4

<0.001

340.127

2.240E+00

1.791E+00

final B = 0

probit

4

<0.001

362.181

5.656E+00

4.810E+00

negative intercept (intercept =
-0.381)

Weibull

4

<0.001

340.127

2.240E+00

1.791E+00

power bound hit (power =1)

gamma,
unrestricted

3

0.407

314.135

2.211E-02

8.081E-04

unrestricted (power = 0.297)

log-logistic,
unrestricted b

3

0.739

312.487

3.062E-01

7.972E-02

unrestricted (slope = 0.785)

log-probit,
unrestricted

3

0.727

312.543

3.316E-01

8.968E-02

unrestricted (slope = 0.471)

Weibull,
unrestricted

3

0.586

313.176

9.000E-02

1.341E-02

unrestricted (power = 0.465)

a Best-fitting model, BMDS output presented in this appendix
b Alternate model, BMDS output also presented in this appendix

E.3.31.2. Output for Selected Model: Log-Logistic

National Toxicology Program, 2006: Alveolar Metaplasia

Logistic Model. (Version: 2.12; Date: 05/16/2008)

Input Data File: C:\1\40_NTP_2006_AlvMeta_LogLogistic_l.(d)

Gnuplot Plotting File: C:\l\4 0_NTP_2006_AlvMeta_LogLogistic_l.plt

Tue Feb 16 18:19:30 2010

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The form of the probability function is:

P[response] = background+(1-background)/[1+EXP(-intercept-slope*Log(dose))]

Dependent variable = DichEff
Independent variable = Dose

This document is a draft for review purposes only and does not constitute Agency policy.

E-421 DRAFT—DO NOT CITE OR QUOTE


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Slope parameter is restricted as slope >= 1
Total number of observations = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

User has chosen the log transformed model

Default Initial Parameter Values

background = 0.0377358
intercept =	-2.03745

slope =	1

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -slope

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

background intercept
background	1	-0.4

intercept	-0.4	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

background	0.0448753	*	*	*

intercept	-1.78837	*	*	*

slope	1	*	*	*

Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-152.615	6

Fitted model -154.485 2	3.7393 4	0.4424

Reduced model -216.802 1	128.374 5	<.0001

AIC:	312.97

Goodness of Fit

Scaled

Dose	Est. Prob. Expected Observed	Size	Residual

0.0000

0

044 9

2.318

2 . 000

53

-0

251

2.1400

0

2966

16.017

19.000

54

0

889

7.1400

0

5647

29.928

33.000

53

0

851

15.7000

0

7366

38.301

35.000

52

-1

039

32.9000

0

8531

45.214

45.000

53

-0

083

71.4000

0

9262

48.162

46.000

52

-1

147

Chi/N2 = 3.98	d.f. = 4	P-value = 0.4088

Benchmark Dose Computation

This document is a draft for review purposes only and does not constitute Agency policy.

E-422 DRAFT—DO NOT CITE OR QUOTE


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Specified effect
Risk Type
Confidence level
BMD
BMDL

0.1
Extra risk
0. 95
0.664411
0.504109

E.3.31.3. Figure for Selected Model: Log-Logistic

Log-Logistic Model with 0.95 Confidence Level

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E.3.31.4. Output for Additional Model Presented: Log-Logistic, Unrestricted
National Toxicology Program, 2006: Alveolar Metaplasia

Logistic Model. (Version: 2.12; Date: 05/16/2008)

Input Data File: C:\1\40_NTP_2006_AlvMeta_LogLogistic_U_l.(d)

Gnuplot Plotting File: C:\l\4 0_NTP_2006_AlvMeta_LogLogistic_U_l.plt

Tue Feb 16 18:19:31 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-423 DRAFT—DO NOT CITE OR QUOTE


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The form of the probability function is:

P[response] = background+(1-background)/[1+EXP(-intercept-slope*Log(dose))]

Dependent variable = DichEff
Independent variable = Dose
Slope parameter is not restricted

Total number of observations = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

User has chosen the log transformed model

Default Initial	Parameter Values

background =	0.0377358

intercept =	-1.26694

slope =	0.784484

Asymptotic Correlation Matrix of Parameter Estimates
background intercept	slope

background	1	-0.24	0.11

intercept	-0.24	1	-0.9

slope	0.11	-0.9	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

background	0.0375286	*	*	*

intercept	-1.26811	*	*	*

slope	0.785033	*	*	*

Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-152.615	6

Fitted model -153.244 3	1.2566 3	0.7395

Reduced model -216.802 1	128.374 5	<.0001

AIC:	312.487

Goodness of Fit

Scaled

Dose Est. Prob. Expected Observed	Size	Residual

0.0000 0.0375 1.989 2.000	53	0.008

2.1400 0.3631 19.609 19.000	54	-0.172

7.1400 0.5845 30.980 33.000	53	0.563

15.7000 0.7205 37.468 35.000	52	-0.763

This document is a draft for review purposes only and does not constitute Agency policy.

E-424 DRAFT—DO NOT CITE OR QUOTE


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32.9000	0.8207	43.4 98 45.000

71.4000	0.8934	46.455 46.000

53
52

0.538
-0.204

Chi' '2 = 1.26 d.f.	= 3 P-value = 0.738

E'.enchmark Dose Computation

Specified effect =	0 .1

Risk Typ'e =	E::tra risk

Cc'nfidence level =	0.95

BMD =	0.306194

EMDL =	0.07 97 223

E.3.31.5. Figure for Additional Model Presented: Log-Logistic, Unrestricted

Log-Logistic Model with 0.95 Confidence Level

dose

18:19 02/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-425 DRAFT—DO NOT CITE OR QUOTE


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E.3.32. National Toxicology Program, 2006: Eosinophilic Focus, Liver
E.3.32.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

gamma

4

0.367

330.457

5.676E+00

4.532E+00

power bound hit (power = 1)

logistic

4

0.167

333.343

1.258E+01

1.071E+01

negative intercept (intercept =
-1.747)

log-logistic

3

0.117

334.148

4.727E+00

2.867E+00



log-probit

4

0.084

334.683

1.078E+01

8.514E+00



multistage, 5-
degree

3

0.313

331.771

6.568E+00

4.666E+00



probita

4

0.187

332.962

1.196E+01

1.031E+01

negative intercept (intercept
= -1.061)

Weibull

4

0.367

330.457

5.675E+00

4.532E+00

power bound hit (power = 1)

log-probit,
unrestricted

3

0.087

334.849

4.750E+00

1.757E+00

unrestricted (slope = 0.643)

a Best-fitting model, BMDS output presented in this appendix

E.3.32.2. Output for Selected Model: Probit

National Toxicology Program, 2006: Eosinophilic Focus, Liver

pit

56 2010
0

Probit Model. (Version: 3.1; Date: 05/16/2008)

Input Data File: C:\1\45_NTP_2006_LivEosFoc_Probit_l.(d)

Gnuplot Plotting File: C:\l\45_NTP_2006_LivEosFoc_Probit_l.

Tue Feb 16 18:25:

The form of the probability function is:

P[response] = CumNorm(Intercept + Slope* Dose),

where CumNorm(.) is the cumulative normal distribution function

Dependent variable = DichEff
Independent variable = Dose
Slope parameter is not restricted

Total number of observations = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

This document is a draft for review purposes only and does not constitute Agency policy.

E-426 DRAFT—DO NOT CITE OR QUOTE


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Default Initial	(and Specified) Parameter Values

background =	0 Specified

intercept =	-1.11935

slope =	0.0279665

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -background

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

intercept	slope

intercept	1	-0.69

slope	-0.69	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

intercept	-1.06148	0.109177	-1.27546	-0.847497

slope	0.0269279	0.00327788	0.0205034	0.0333525

Analysis of Deviance Table

Model
Full model
Fitted model
Reduced model

Log(likelihood)
-161.07
-164.481
-202.816

Param's Deviance Test d.f.

6.8221
83.4925

P-value

0.1456
C. 0001

332.962

Est. Prob.

Goodness of Fit
Expected Observed

Scaled
Residual

0.0000

0

1442

7 . 645

3

000

53

-1

816

2.1400

0

1577

8 . 517

8

000

54

-0

193

7.1400

0

1924

10.195

14

000

53

1

326

15.7000

0

2615

13.860

17

000

53

0

982

32.9000

0

4303

22 .807

22

000

53

-0

224

71.4000

0

8054

42.688

42

000

53

-0

239

Chi ^2 = 6.16	d.f. = 4	P-value = 0.1873

Benchmark Dose Computation
Specified effect =	0.1

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	11.9584

BMDL =	10.3075

This document is a draft for review purposes only and does not constitute Agency policy.

E-427 DRAFT—DO NOT CITE OR QUOTE


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l E.3.32.3. Figure for Selected Model: Probit

Probit Model with 0.95 Confidence Level

dose

2	18:25 02/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-428 DRAFT—DO NOT CITE OR QUOTE


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E.3.33. National Toxicology Program, 2006: Fatty Change Diffuse, Liver
E.3.33.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

gamma

4

0.668

252.294

4.224E+00

3.166E+00



logistic

4

0.005

269.825

1.092E+01

9.292E+00

negative intercept (intercept =
-2.298)

log-logistic

4

0.292

255.082

4.697E+00

3.153E+00



log-probit

4

0.118

257.548

6.236E+00

5.204E+00

slope bound hit (slope =1)

multistage, 5-
degree

4

0.808

251.545

4.021E+00

3.250E+00



probit

4

0.005

269.430

1.052E+01

9.068E+00

negative intercept (intercept =
-1.36)

Weibull3

4

0.679

252.218

4.252E+00

3.174E+00



log-probit,
unrestricted

4

0.282

255.258

4.581E+00

3.193E+00

unrestricted (slope = 0.824)

a Best-fitting model, BMDS output presented in this appendix

E.3.33.2. Output for Selected Model: Weibull

National Toxicology Program, 2006: Fatty Change Diffuse, Liver

Weibull Model using Weibull Model (Version: 2.12; Date: 05/16/2008)
Input Data File: C:\1\47_NTP_2006_LivFatDiff_Weibull_l.(d)

Gnuplot Plotting File: C:\l\47_NTP_2006_LivFatDiff_Weibull_l.plt

Tue Feb 16 18:26757 2010

NTP liver fatty change diffuse

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(-slope*doseApower)]

Dependent variable = DichEff
Independent variable = Dose

Power parameter is restricted as power >=1
Total number of observations = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

This document is a draft for review purposes only and does not constitute Agency policy.

E-429 DRAFT—DO NOT CITE OR QUOTE


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Default Initial	(and Specified) Parameter Values

Background =	0.00925926

Slope =	0.00962604

Power =	1.28042

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -Background

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Slope	Power

Slope	1	-0.97

Power	-0.97	1

Parameter Estimates

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

0.0037073	0.0409874

0.831952	1.31071

NA - Indicates that this parameter has hit a bound
implied by some ineguality constraint and thus
has no standard error.

Variable
Background
Slope
Power

Estimate

0

0.0223474
1.07133

Std. Err.

NA

0.00951041
0.122134

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-122.992	6

Fitted model -124.109 2	2.23388 4	0.692e

Reduced model -204.846 1	163.708 5	<.0001

AIC:	252.218

Goodness of Fit

Scaled

Dose	Est. Prob. Expected Observed	Size	Residual

0.0000

0

0000

0. 000

0

000

53

0

000

2.1400

0

04 92

2 . 659

2

000

54

-0

414

7.1400

0

1677

8.889

12

000

53

1

144

15.7000

0

3475

18.420

17

000

53

-0

409

32.9000

0

6107

32.365

30

000

53

-0

6 6 6

71.4000

0

8851

4 6.909

48

000

53

0

470

Chi ^2 = 2.31	d.f. = 4	P-value = 0.6785

Benchmark Dose Computation
Specified effect =	0.1

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	4.25219

BMDL =	3.17375

This document is a draft for review purposes only and does not constitute Agency policy.

E-430 DRAFT—DO NOT CITE OR QUOTE


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1

2	E.3.33.3. Figure for Selected Model: Weibull

Weibull Model with 0.95 Confidence Level

dose

3	18:26 02/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-431 DRAFT—DO NOT CITE OR QUOTE


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E.3.34. National Toxicology Program, 2006: Gingival Hyperplasia, Squamous, 2 Years
E.3.34.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

gamma

4

0.012

318.867

2.295E+01

1.417E+01

power bound hit (power = 1)

logistic

4

0.008

320.908

3.594E+01

2.564E+01

negative intercept (intercept =
-1.711)

log-logistica

4

0.015

317.969

1.838E+01

1.044E+01

slope bound hit (slope = 1)

log-probit

4

0.003

323.633

4.313E+01

2.794E+01

slope bound hit (slope =1)

multistage, 5-
degree

4

0.012

318.867

2.295E+01

1.417E+01

final B = 0

probit

4

0.008

320.687

3.436E+01

2.425E+01

negative intercept (intercept =
-1.034)

Weibull

4

0.012

318.867

2.295E+01

1.417E+01

power bound hit (power = 1)

gamma,
unrestricted

3

0.651

307.529

2.480E-01

5.096E-09

unrestricted (power = 0.199)

log-logistic,
unrestricted b

3

0.675

307.416

3.710E-01

1.505E-07

unrestricted (slope = 0.265)

log-probit,
unrestricted

3

0.688

307.354

4.688E-01

8.851E-07

unrestricted (slope = 0.156)

Weibull,
unrestricted

3

0.663

307.471

3.076E-01

3.210E-08

unrestricted (power = 0.23)

a Best-fitting model, BMDS output presented in this appendix
b Alternate model, BMDS output also presented in this appendix

E.3.34.2. Output for Selected Model: Log-Logistic

National Toxicology Program, 2006: Gingival Hyperplasia, Squamous, 2 Years

Logistic Model. (Version: 2.12; Date: 05/16/2008)

Input Data File: C:\1\42_NTP_2006_GingHypSq_LogLogistic_l.(d)

Gnuplot Plotting File: C:\l\42_NTP_2006_GingHypSq_LogLogistic_l.plt

Tue Feb~16 18:20:29~2010

[insert study notes]

The form of the probability function is:

P[response] = background+(1-background)/[1+EXP(-intercept-slope*Log(dose))]

Dependent variable = DichEff
Independent variable = Dose

This document is a draft for review purposes only and does not constitute Agency policy.

E-432 DRAFT—DO NOT CITE OR QUOTE


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Slope parameter is restricted as slope >= 1

Total number of observations = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

User has chosen the log transformed model

Default Initial Parameter Values
background = 0.0188679
intercept =	-4.5509

slope =	1

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -slope

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

background intercept

background	1	-0.71

intercept	-0.71	1

Parameter Estimates

95.0% Wald Confidence Interval

Variable Estimate Std. Err.	Lower Conf.	Limit Upper Conf. Limit

background 0.117717 *	*	*

intercept -5.10866 *	*	*

slope 1 *	*	*

Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-149.95	6

Fitted model -156.985 2	14.0696 4	0.00707^

Reduced model -162.631 1	25.3627 5	0.000118^

AIC:	317.969

Goodness of Fit

Scaled

Dose	Est. Prob. Expected Observed	Size	Residual

0.0000

0.1177

6.239

1

000

53

-2 . 233

2.1400

0.1290

6. 965

7

000

54

0. 014

7.1400

0.1542

8.174

14

000

53

2 . 216

15.7000

0.1942

10.292

13

000

53

0. 940

32.9000

0.2641

13.995

15

000

53

0.313

71.4000

0.3837

20.335

16

000

53

-1. 225

Chi ^2 = 12.38	d.f. = 4	P-value = 0.0147

Benchmark Dose Computation

This document is a draft for review purposes only and does not constitute Agency policy.

E-433 DRAFT—DO NOT CITE OR QUOTE


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Specified effect =	0.1

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	18.3832

BMDL =	10.4 35 9

E.3.34.3. Figure for Selected Model: Log-Logistic

Log-Logistic Model with 0.95 Confidence Level

dose

18:20 02/16 2010

E.3.34.4. Output for Additional Model Presented: Log-Logistic, Unrestricted
National Toxicology Program, 2006: Gingival Hyperplasia, Squamous, 2 Years

Logistic Model. (Version: 2.12; Date: 05/16/2008)

Input Data File: C:\1\42_NTP_2006_GingHypSq_LogLogistic_U_l.(d)

Gnuplot Plotting File: C:\l\42_NTP_2006_GingHypSq_LogLogistic_U_l.plt

Tue Feb 16 18:20:29 2010

[insert study notes]

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-434 DRAFT—DO NOT CITE OR QUOTE


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The form of the probability function is:

P[response] = background+(1-background)/[1+EXP(-intercept-slope*Log(dose))]

Dependent variable = DichEff
Independent variable = Dose
Slope parameter is not restricted

Total number of observations = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

User has chosen the log transformed model

Default Initial	Parameter Values

background =	0.0188679

intercept =	-2.04571

slope =	0.299277

Asymptotic Correlation Matrix of Parameter Estimates
background intercept	slope

background	1	-0.3	0.12

intercept	-0.3	1	-0.91

slope	0.12	-0.91	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

background	0.0185126	*	*	*

intercept	-1.93464	*	*	*

slope	0.264795	*	*	*

Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-149.95	6

Fitted model -150.708 3	1.5163 3	0.6785

Reduced model -162.631 1	25.3627 5	0.0001186

AIC:	307.416

Goodness of Fit

Scaled

Dose Est. Prob. Expected Observed	Size	Residual

0.0000 0.0185 0.981 1.000	53 0.019

2.1400 0.1659 8.959 7.000	54	-0.717

7.1400 0.2105 11.155 14.000	53 0.959

15.7000 0.2447 12.972 13.000	53 0.009

This document is a draft for review purposes only and does not constitute Agency policy.

E-43 5 DRAFT—DO NOT CITE OR QUOTE


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32.9000	0.2806

71.4000	0.3219

14 . 873
17.059

15.000
16.000

53
53

0. 03 9
-0.311

Chi' '2

1. 53

d. f.

E'-value

0.6750

E'.enchmark Dose Computation
Specified effect =	0 .1

Risk Typ'e	=	E::tra risk

Cc'nfidence level =	0.95

BMD =	0.37 0 95 8

BMDL = 1. 5 0 4 9 4 e - 0 0 7

E.3.34.5. Figure for Additional Model Presented: Log-Logistic, Unrestricted

Log-Logistic Model with 0.95 Confidence Level

dose

18:20 02/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-436 DRAFT—DO NOT CITE OR QUOTE


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E.3.35. National Toxicology Program, 2006: Hepatocyte Hypertrophy, 2 Years
E.3.35.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

gamma

4

<0.001

290.365

1.647E+00

1.340E+00

power bound hit (power = 1)

logistic

4

<0.001

310.492

4.315E+00

3.650E+00

negative intercept (intercept =
-1.237)

log-logistic

5

0.010

278.082

6.978E-01

5.454E-01

slope bound hit (slope =1)

log-probit

4

<0.001

297.168

2.930E+00

2.267E+00

slope bound hit (slope =1)

multistage, 5-
degreea

4

<0.001

290.365

1.647E+00

1.340E+00

final 15 = 0

probit

4

<0.001

313.841

4.564E+00

3.923E+00

negative intercept (intercept =
-0.714)

Weibull

4

<0.001

290.365

1.647E+00

1.340E+00

power bound hit (power = 1)

gamma,
unrestricted

4

0.029

275.042

error

error

unrestricted (power = 0.478)

log-logistic,
unrestricted

4

0.005

280.068

6.672E-01

2.939E-01

unrestricted (slope = 0.984)

log-probit,
unrestricted

4

0.006

279.204

7.167E-01

3.322E-01

unrestricted (slope = 0.594)

Weibull,
unrestricted

4

0.019

275.967

3.709E-01

1.315E-01

unrestricted (power = 0.64)

a Best-fitting model, BMDS output presented in this appendix

E.3.35.2. Output for Selected Model: Multistage, 5-Degree

National Toxicology Program, 2006: Hepatocyte Hypertrophy, 2 Years

Multistage Model. (Version: 3.0; Date: 05/16/2008)

Input Data File: C:\1\43_NTP_2006_HepHyper_Multi5_l.(d)

Gnuplot Plotting File: C:\l\43_NTP_2006_HepHyper_Multi5_l.plt

Tue Feb 16 18721:00 2010

[insert study notes]

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(

-betal*dose/Nl-beta2*dose/N2-beta3*dose/N3-beta4*dose/N4-beta5*dose/N5) ]

The parameter betas are restricted to be positive

Dependent variable = DichEff

This document is a draft for review purposes only and does not constitute Agency policy.

E-437 DRAFT—DO NOT CITE OR QUOTE


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Independent variable = Dose
Total number of observations = 6

Total number of records with missing values = 0
Total number of parameters in model = 6
Total number of specified parameters = 0
Degree of polynomial = 5

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background =	0.232262

Beta(1) =	0.045074

Beta(2) =	0

Beta(3) =	0

Beta(4) =	0

Beta(5) = 2.59945e-010

Asymptotic Correlation Matrix of Parameter Estimates

(	The model parameter(s) -Beta(2)	-Beta(3)	-Beta(4)	-Beta(5)

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Background	Beta(1)

Background	1	-0.64

Beta(1)	-0.64	1

Parameter Estimates

Variable
Background
Beta(1)
Beta(2)
Beta(3)
Beta(4)
Beta(5)

Estimate

0.0541647
0.0639585
0
0
0
0

Std. Err.

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

Indicates that this value is not calculated.

Analysis of Deviance Table

Model
Full model
Fitted model
Reduced model

Log(likelihood)

-129.986
-143.183
-219.97

Param's Deviance Test d.f.

26.3932
179.968

P-value

2.63 61629e-0 05
<.0001

AIC:

290.365

Dose

Est. Prob.

Goodness of Fit
Expected Observed

Scaled
Residual

0.0000
2.1400
7.1400

0.0542
0.1752
0.4009

2 . 871
9. 458
21.248

0. 000
19.000
19.000

53

54
53

-1.742

3.416
-0.630

This document is a draft for review purposes only and does not constitute Agency policy.

E-43 8 DRAFT—DO NOT CITE OR QUOTE


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15.7000	0.6535	34.635 42.000	53	2.126

32.9000	0.8847	46.887 41.000	53	-2.532

71.4000	0.9902	52.479 52.000	53	-0.667

Chi' '2 = 26.48 d.f.	= 4	P-value = 0.0000

E'.enchmark Dose Computation

Specified effect =	0 .1

Risk Typ'e =	E::tra risk

Cc'nfidence level =	0.95

BMD =	1.64733

EMDL =	1.34 007

BMDLJ =	2.05 81

Taken together, (1.34 007, 2.0581 ) is a 90	% two-sided confidence

interval for the EMD

E.3.35.3. Figure for Selected Model: Multistage, 5-Degree

Multistage Model with 0.95 Confidence Level

10	20	30	40	50	60	70

dose

18:21 02/16 2010

Multistage

This document is a draft for review purposes only and does not constitute Agency policy.

E-439 DRAFT—DO NOT CITE OR QUOTE


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E.3.36. National Toxicology Program, 2006: Necrosis, Liver
E.3.36.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

r p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

logistic

4

0.397

238.314

3.484E+01

2.842E+01

negative intercept (intercept =
-2.601)

log-logistic

4

0.810

235.265

1.791E+01

1.194E+01

slope bound hit (slope =1)

log-probit

4

0.290

239.107

3.205E+01

2.382E+01

slope bound hit (slope =1)

multistage, 5-
degree

4

0.763

235.581

2.019E+01

1.419E+01

final B = 0

probit

4

0.445

237.888

3.266E+01

2.637E+01

negative intercept (intercept =
-1.508)

Weibull

4

0.763

235.581

2.019E+01

1.419E+01

power bound hit (power =1)

gamma,
unrestricted

3

0.869

236.344

1.114E+01

3.487E+00

unrestricted (power = 0.599)

log-logistic,
unrestricted

3

0.833

236.483

1.112E+01

3.581E+00

unrestricted (slope = 0.695)

log-probit,
unrestricteda

3

0.768

236.742

1.061E+01

3.498E+00

unrestricted (slope = 0.367)

Weibull,
unrestricted

3

0.856

236.393

1.117E+01

3.554E+00

unrestricted (power = 0.64)

a Best-fitting model, BMDS output presented in this appendix

E.3.36.2. Output for Selected Model: Log-Probit, Unrestricted

National Toxicology Program, 2006: Necrosis, Liver

Probit Model. (Version: 3.1; Date: 05/16/2008)

Input Data File: C:\1\50_NTP_2006_LivNec_LogProbit_U_l.(d)

Gnuplot Plotting File: C:\l\50_NTP_2006_LivNec_LogProbit_U_l.plt

Tue Feb 16 18:34731 2010

NTP liver necrosis

The form of the probability function is:

P[response] = Background

+ (1-Background) * CumNorm(Intercept + Slope^Log(Dose) ) ,

where CumNorm(.) is the cumulative normal distribution function

Dependent variable = DichEff
Independent variable = Dose
Slope parameter is not restricted

This document is a draft for review purposes only and does not constitute Agency policy.

E-440 DRAFT—DO NOT CITE OR QUOTE


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Total number of observations = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

User has chosen the log transformed model

Default Initial	(and Specified) Parameter Values

background =	0.0188679

intercept =	-1.98094

slope =	0.316942

Asymptotic Correlation Matrix of Parameter Estimates
background intercept	slope

background	1	-0.69	0.59

intercept	-0.69	1	-0.97

slope	0.59	-0.97	1

Parameter Estimates

Variable
background
intercept
slope

Estimate

0.0228339
-2 .14844
0.367034

95.0% Wald Confidence Interval
Std. Err.	Lower Conf. Limit Upper Conf. Limit

0.0230818	-0.0224057	0.0680734

0.527256	-3.18184	-1.11503

0.139055	0.0944904	0.639577

Analysis of Deviance Table

Model
Full model
Fitted model
Reduced model

Log(likelihood)
-114 . 813
-115.371
-127.98

Param's Deviance Test d.f.

1.1157
26.3331

P-value

0.7733
C. 0001

236.742

Goodness of Fit

Scaled

Dose

Est

. Prob.

Expected

Observed

Size

Residual

0.0000

0.

0228

1 210

1

000

53

-0

193

2.1400

0.

0529

2 858

4

000

54

0

694

7.1400

0.

0979

5.187

4

000

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-0

549

15.7000

0.

1475

7.819

8

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070

32.9000

0.

2116

11 215

10

000

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-0

409

71.4000

0.

2968

15.729

17

000

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0

382

Chi ^2

1.14

d.f.

P-value

0.7678

Benchmark Dose Computation
Specified effect =	0.1

Risk Type	=	Extra risk

Confidence level =	0.95

This document is a draft for review purposes only and does not constitute Agency policy.

E-441 DRAFT—DO NOT CITE OR QUOTE


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BMD =	10.6107

BMDL =	3.4 97 91

E.3.36.3. Figure for Selected Model: Log-Probit, Unrestricted

LogProbit Model with 0.95 Confidence Level

0.5 	

0.4

"O

CD

-t—'

O
CD
!t=
<
c
o

o
m

0.3

0.2

0.1

0 -

dose

18:34 02/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-442 DRAFT—DO NOT CITE OR QUOTE


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E.3.37. National Toxicology Program, 2006: Oval Cell Hyperplasia
E.3.37.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

gamma

3

0.072

199.446

8.970E+00

5.499E+00



logistic

4

0.069

199.875

9.792E+00

8.245E+00

negative intercept (intercept =
-3.116)

log-logistic

3

0.039

202.012

9.708E+00

7.247E+00



log-probit

3

0.068

200.421

9.968E+00

7.758E+00



multistage, 5-
degree

2

0.066

198.641

5.424E+00

3.514E+00



probita

4

0.112

198.166

9.103E+00

7.701E+00

negative intercept (intercept
= -1.821)

Weibullb

3

0.075

198.690

7.712E+00

4.692E+00



a Best-fitting model, BMDS output presented in this appendix
b Alternate model, BMDS output also presented in this appendix

E.3.37.2. Output for Selected Model: Probit

National Toxicology Program, 2006: Oval Cell Hyperplasia

pit

52 2010

0

Probit Model. (Version: 3.1; Date: 05/16/2008)

Input Data File: C:\1\53_NTP_2006_OvalHyper_Probit_l.(d)

Gnuplot Plotting File: C:\l\53_NTP_2006_OvalHyper_Probit_l.

Tue Feb 16 19:51:

The form of the probability function is:

P[response] = CumNorm(Intercept + Slope* Dose),

where CumNorm(.) is the cumulative normal distribution function

Dependent variable = DichEff
Independent variable = Dose
Slope parameter is not restricted

Total number of observations = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

This document is a draft for review purposes only and does not constitute Agency policy.

E-443 DRAFT—DO NOT CITE OR QUOTE


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Default Initial	(and Specified) Parameter Values

background =	0 Specified

intercept =	-1.92612

slope =	0.0670004

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -background

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

intercept	slope

intercept	1	-0.8

slope	-0.8	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

intercept	-1.82129	0.16954	-2.15359	-1.489

slope	0.0767832	0.00835175	0.060414	0.0931523

Analysis of Deviance Table

Model
Full model
Fitted model
Reduced model

Log(likelihood)
-92.4898
-97.0832
-210.191

Param's Deviance Test d.f.

9.18683
235.402

P-value

0.0566
C.0001

198.166

Dose

Est. Prob.

Goodness of Fit
Expected Observed

Scaled
Residual

0.0000

0

0343

1. 817

0

000

53

-1

372

2.1400

0

0488

2 . 633

4

000

54

0

864

7.1400

0

1015

5.379

3

000

53

-1

082

15.7000

0

2690

14 . 258

20

000

53

1

77 9

32.9000

0

7596

40.256

38

000

53

-0

725

71.4000

0

9 9 9 9

52.993

53

000

53

0

082

Chi ^2 = 7.50	d.f. = 4	P-value = 0.1119

Benchmark Dose Computation
Specified effect =	0.1

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	9.1026

BMDL =	7.7011

This document is a draft for review purposes only and does not constitute Agency policy.

E-444 DRAFT—DO NOT CITE OR QUOTE


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E.3.37.3. Figure for Selected Model: Probit

Probit Model with 0.95 Confidence Level

dose

19:51 02/16 2010

E.3.37.4. Output for Additional Model Presented: Weibull
National Toxicology Program, 2006: Oval Cell Hyperplasia

Weibull Model using Weibull Model (Version: 2.12; Date: 05/16/2008)
Input Data File: C:\1\53_NTP_2006_OvalHyper_Weibull_l.(d)

Gnuplot Plotting File: C:\l\53_NTP_2006_OvalHyper_Weibull_l.plt

Tue Feb 16 19:51:53 2010

0

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(-slope*doseApower)]

Dependent variable = DichEff

Independent variable = Dose

Power parameter is restricted as power >=1

Total number of observations = 6

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-445 DRAFT—DO NOT CITE OR QUOTE


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Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial	(and Specified) Parameter Values

Background =	0.00925926

Slope =	0.00444 52

Power =	1.63009

Asymptotic Correlation Matrix of Parameter Estimates
Background	Slope	Power

Background	1	-0.63	0.61

Slope	-0.63	1	-0.99

Power	0.61	-0.99	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0.021258	0.0198428	-0.0176332	0.0601492

Slope	0.0028715	0.00303327	-0.0030736	0.0088166

Power	1.76359	0.309457	1.15706	2.37011

Analysis of Deviance Table

Model	Log(likelihood)	# Param's	Deviance	Test d.f.	P-value

Full model	-92.4898	6

Fitted model	-96.3448	3	7.70998	3	0.0524

Reduced model	-210.191	1	235.402	5	<.0001

AIC:	198.69

Goodness of Fit

Scaled

Dose	Est. Prob. Expected Observed	Size	Residual

0.0000

0.0213

1.127

0

000

53

-1.073

2.1400

0.0320

1.725

4

000

54

1.760

7.1400

0.1073

5. 685

3

000

53

-1.192

15.7000

0.3234

17 .138

20

000

53

0.840

32.9000

0.7490

39.698

38

000

53

-0.538

71.4000

0.9953

52.750

53

000

53

0.501

Chi/N2 = 6.92	d.f. = 3	P-value = 0.0746

Benchmark Dose Computation
Specified effect =	0.1

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	7.71171

BMDL =	4 . 69152

This document is a draft for review purposes only and does not constitute Agency policy.

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1

2	E.3.37.5. Figure for Additional Model Presented: Weibull

Weibull Model with 0.95 Confidence Level

dose

3	19:51 02/16 2010

4

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-447 DRAFT—DO NOT CITE OR QUOTE


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E.3.38. National Toxicology Program, 2006: Pigmentation, Liver
E.3.38.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

gamma

3

0.385

197.655

1.547E+00

8.055E-01



logistic

4

<0.001

203.517

2.259E+00

1.872E+00

negative intercept (intercept =
-1.925)

log-logistic

3

0.978

195.600

2.212E+00

1.452E+00



log-probita

3

0.980

195.450

2.072E+00

1.399E+00



multistage, 5-
degree

3

0.210

199.850

9.396E-01

7.079E-01

final B = 0

probit

4

<0.001

210.309

2.259E+00

1.916E+00

negative intercept (intercept =
-1.057)

Weibull

3

0.290

198.489

1.280E+00

7.518E-01



a Best-fitting model, BMDS output presented in this appendix

E.3.38.2. Output for Selected Model: Log-Probit

National Toxicology Program, 2006: Pigmentation, Liver

Probit Model. (Version: 3.1; Date: 05/16/2008)

Input Data File: C:\1\54_NTP_2006_Pigment_LogProbit_l.(d)

Gnuplot Plotting File: C:\l\54_NTP_2006_Pigment_LogProbit_l.plt

Tue Feb 16 19:52:19 2 010

The form of the probability function is:

P[response] = Background

+ (1-Background) * CumNorm(Intercept + Slope^Log(Dose) ) ,

where CumNorm(.) is the cumulative normal distribution function

Dependent variable = DichEff
Independent variable = Dose

Slope parameter is restricted as slope >= 1
Total number of observations = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

This document is a draft for review purposes only and does not constitute Agency policy.

E-448 DRAFT—DO NOT CITE OR QUOTE


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User has chosen the log transformed model

Default Initial	(and Specified) Parameter Values

background =	0.0754717

intercept =	-1.91144

slope =	1.07 385

Asymptotic Correlation Matrix of Parameter Estimates

background
intercept
slope

background
1

-0.45
0.35

intercept

-0.45
1

-0. 94

slope

0.35
-0. 94
1

Parameter Estimates

Variable
background
intercept
slope

Estimate

0.0735956
-2 .19294
1. 25068

Std. Err.

0.0343284
0. 400053
0.169731

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

0. 00631316
-2 . 97703
0.918012

0.140878
-1.40885
1.58335

Model
Full model
Fitted model
Reduced model

Analysis of Deviance Table

Param's Deviance Test d.f.

Log(likelihood)

-94.6177
-94.7248
-210.717

195.45

0.214232
232.198

P-value

0. 9753
C.0001

Goodness of Fit

Est. Prob.

Expected

Observed

Scaled
Residual

0.0000

0

0736

3. 901

4

000

53

0

052

2.1400

0

1729

9.338

9

000

54

-0

122

7.1400

0

6338

33.591

34

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0

117

15.7000

0

9023

47.822

48

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53

0

082

32.9000

0

9863

52 . 275

52

000

53

-0

325

71.4000

0

9992

52.959

53

000

53

0

202

Chi ^2

0.18

d.f.

P-value

0.9801

Benchmark Dose Computation

Specified effect
Risk Type
Confidence level
BMD
BMDL

0.1
Extra risk

0. 95
2.07241
1.39932

This document is a draft for review purposes only and does not constitute Agency policy.

E-449 DRAFT—DO NOT CITE OR QUOTE


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l E.3.38.3. Figure for Selected Model: Log-Probit

LogProbit Model with 0.95 Confidence Level

dose

2	19:52 02/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-450 DRAFT—DO NOT CITE OR QUOTE


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E.3.39. National Toxicology Program, 2006: Toxic Hepatopathy
E.3.39.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

gamma

4

0.772

185.634

4.668E+00

3.317E+00



logistic

4

0.012

198.445

7.070E+00

5.925E+00

negative intercept (intercept =
-2.925)

log-logistic

3

0.362

190.061

5.676E+00

4.040E+00



log-probit

3

0.378

189.858

6.061E+00

4.079E+00



multistage, 5-
degreea

4

0.577

186.521

4.163E+00

2.701E+00

final 15 = 0

probit

4

0.019

197.159

6.784E+00

5.712E+00

negative intercept (intercept =
-1.724)

Weibull

4

0.745

185.657

4.454E+00

3.159E+00



a Best-fitting model, BMDS output presented in this appendix

E.3.39.2. Output for Selected Model: Multistage, 5-Degree

National Toxicology Program, 2006: Toxic Hepatopathy

Multistage Model. (Version: 3.0; Date: 05/16/2008)

Input Data File: C:\1\55_NTP_2006_ToxHepa_Multi5_l.(d)

Gnuplot Plotting File: C:\l\55_NTP_2006_ToxHepa_Multi5_l.plt

Tue Feb 16 19:52:49 2010

0

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(

-betal*dose/Nl-beta2*dose/N2-beta3*dose/N3-beta4*dose/N4-beta5*dose/N5) ]

The parameter betas are restricted to be positive

Dependent variable = DichEff
Independent variable = Dose

Total number of observations = 6

Total number of records with missing values = 0
Total number of parameters in model = 6
Total number of specified parameters = 0
Degree of polynomial = 5

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008

This document is a draft for review purposes only and does not constitute Agency policy.

E-451 DRAFT—DO NOT CITE OR QUOTE


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Parameter

has been set to: le-008

Default Initial Parameter Values
Background =	0

Beta(1) =	0

Beta(2) =	0

Beta(3) =	0

Beta(4) =	0

Beta(5) = 5.40983e+010

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -Background -Beta(3)	-Beta(4)	-Beta(5)

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Beta(1)	Beta(2)

Beta(1)	1	-0.91

Beta(2)	-0.91	1

Parameter Estimates

Variable
Background
Beta(1)
Beta(2)
Beta(3)
Beta(4)
Beta(5)

Estimate

0

0. 019656
0. 00135796
0
0
0

Std. Err.

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

Indicates that this value is not calculated.

Analysis of Deviance Table

Model
Full model
Fitted model
Reduced model

Log(likelihood)

-89.8076
-91.2606
-218.207

Param's Deviance Test d.f.

2.90597
256.799

P-value

0.5737
C.0001

AIC:

186.521

Goodness of Fit

Scaled

Dose

Est

. Prob.

Expected

Observed

Size

Residual

0.0000

0.

0000

0. 000

0

000

53

0

000

2.1400

0.

0471

2 545

2

000

54

-0

350

7.1400

0.

1891

10.021

8

000

53

-0

709

15.7000

0.

4745

25.146

30

000

53

1

335

32.9000

0.

87 96

46.616

45

000

53

-0

682

71.4000

0.

9998

52 987

53

000

53

0

113

Chi ^2

2.89

d.f.

P-value

0.5771

Benchmark Dose Computation
Specified effect =	0.1

This document is a draft for review purposes only and does not constitute Agency policy.

E-452 DRAFT—DO NOT CITE OR QUOTE


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Risk Type =	Extra risk

Confidence level =	0.95

BMD =	4.16294

BMDL =	2.70063

BMDU =	6.0018 6

Taken together, (2.70063, 6.00186) is a 90	% two-sided confidence

interval for the BMD

E.3.39.3. Figure for Selected Model: Multistage, 5-Degree

Multistage Model with 0.95 Confidence Level

dose

19:52 02/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-453 DRAFT—DO NOT CITE OR QUOTE


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E.3.40. Ohsako et al., 2001: Ano-Genital Length, PND 120
E.3.40.1. Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

exponential (M2)

3

0.019

171.804

5.650E+02

3.785E+02



exponential (M3)

3

0.019

171.804

5.650E+02

3.785E+02

power hit bound (d = 1)

exponential (M4)

2

0.117

168.204

2.854E+01

1.054E+01



exponential (M5)

1

0.049

169.789

2.948E+01

1.135E+01



Hill b

2

0.148

167.727

3.722E+01

9.752E+00

n lower bound hit (n = 1)

linear

3

0.018

171.954

5.852E+02

4.047E+02



polynomial, 4-
degree

3

0.018

171.954

5.852E+02

4.047E+02



power

3

0.018

171.954

5.852E+02

4.047E+02

power bound hit (power =1)

Hill, unrestricted0

1

0.055

169.600

5.101E+01

3.066E+00

unrestricted (n = 0.502)

power,
unrestricted

2

0.151

167.689

6.200E+01

2.291E+00

unrestricted (power = 0.252)

a Constant variance model selected (p = 0.165)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.3.40.2. Output for Selected Model: Hill

Ohsako et al., 2001: Ano-Genital Length, PND 120

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\1\56_Ohsako_2001_Anogen_HillCV_l.(d)

Gnuplot Plotting File: C:\l\56_Ohsako_2001_Anogen_HillCV_l.plt

Tue Feb_16 19:53:25 2010

Figure 7

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = Mean
Independent variable = Dose
rho is set to 0

This document is a draft for review purposes only and does not constitute Agency policy.

E-454 DRAFT—DO NOT CITE OR QUOTE


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Power parameter restricted to be greater than 1
A constant variance model is fit

Total number of dose groups = 5

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

alpha
rho

intercept

7 . 27386

0

28.905
-5.1065
1.40226
33.9669

Specified

Asymptotic Correlation Matrix of Parameter Estimates

alpha
intercept

The model parameter(s) -rho -n

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha
1

-2 . 2e-009
-2 . 4e-008
-7 . 2e-009

intercept
-2.2e-009
1

-0. 66
-0.5

v

-2.4e-008
-0. 66
1

-0.11

k

-7 . 2e-009
-0.5
-0.11
1

Parameter Estimates

Variable
alpha
intercept

k

Estimate

7.08444
28 . 9809
-4.79692
1

29.8628

Std. Err.

1.3634
0.745637
0.983318
NA

24 . 4463

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

4 .41223

27 . 5195
-6.72418

-18.0511

9.75666

30.4423
-2.86965

77 .7767

NA - Indicates that this parameter has hit a bound
implied by some ineguality constraint and thus
has no standard error.

Table of Data and Estimated Values of Interest

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0	12	28.9	29	3.13	2.66	-0.0988

12.5	10	27.9	27.6	2.5	2.66	0.442

50	10	25.2	26	3.21	2.66	-0.963

200	10	26	24.8	2.85	2.66	1.42

800	12	23.8	24.4	1.56	2.66	-0.726

Model Descriptions for likelihoods calculated

This document is a draft for review purposes only and does not constitute Agency policy.

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Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2 :	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model
A1

A2
A3

fitted
R

Log(likelihood)

-77 . 952340
-74.703868
-77 . 952340
-79.863340
-89.824703

Param's

10

AIC

167.904680
169.407736
167.904680
167.726680
183.649405

Explanation of Tests

Test 1:

Test 2
Test 3
Test 4
(Note:

Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1

Test 2
Test 3
Test 4

30.2417

6 . 4 9 6 9 4
6 . 4 9 6 9 4
3. 822

0.0001916
0.165
0.165
0.1479

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than
model appears to be appropriate here

.1. A homogeneous variance

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adeguately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	37.224 9

BMDL =	9.75249

This document is a draft for review purposes only and does not constitute Agency policy.

E-456 DRAFT—DO NOT CITE OR QUOTE


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E.3.40.3. Figure for Selected Model: Hill

Hill Model with 0.95 Confidence Level

dose

19:53 02/16 2010

E.3.40.4. Output for Additional Model Presented: Hill, Unrestricted
Ohsako et al., 2001: Ano-Genital Length, PND 120

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\1\56_Ohsako_2001_Anogen_HillCV_U_l.(d)

Gnuplot Plotting File: C:\l\56_Ohsako_2 001_Anogen_HillCV_U_l.plt

Tue Feb 16 19:53:26 2010

Figure 7

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = Mean
Independent variable = Dose
rho is set to 0

Power parameter is not restricted
A constant variance model is fit

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-457 DRAFT—DO NOT CITE OR QUOTE


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Total number of dose groups = 5

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

alpha =	7.27386

rho =	0 Specified

intercept =	28.905

v =	-5.1065

n =	1.40226

k =	33.9669

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -rho

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha
intercept

alpha
1

2 . le-009
-1. 8e-008
-1. 7e-008
1. 6e-008

intercept
2 . le-009
1

0. 012
0.0075
-0.13

v

-1.8e-008
0. 012
1

0. 98
-0. 99

n

-1. 7e-008
0. 0075
0. 98
1

-0. 97

k

1. 6e-008
-0.13
-0. 99
-0. 97
1

Parameter Estimates

Variable
alpha
intercept

Estimate

7 . 06785
28 . 9608
-6.94236
0.501942
131.957

Std. Err.

1.36021
0.755363
12 . 2514
0.915162
1071.9

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

4 .40189

27.4803
-30.9547
-1.29174
-1968.92

9.73381

30.4413
17 . 07
2.29563
2232.84

Table of Data and Estimated Values of Interest
5	N Obs Mean	Est Mean Obs Std Dev Est Std Dev Scaled Res.

0	12	28.9	29	3.13	2.66	-0.0727

12.5	10	27.9	27.3	2.5	2.66	0.72

50	10	25.2	26.3	3.21	2.66	-1.37

200	10	26	25.1	2.85	2.66	1.04

800	12	23.8	24	1.56	2.66	-0.287

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(iji

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij|

This document is a draft for review purposes only and does not constitute Agency policy.

E-458 DRAFT—DO NOT CITE OR QUOTE


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Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma^2
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1 -77.952340	6	167.904680

A2 -74.703868	10	169.407736

A3 -77.952340	6	167.904680

fitted -79.800035	5	169.600070

R -89.824703	2	183.649405

Explanation of Tests

Test 1:

Test

2

Test

3

Test

4

Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	30.2417	8	0.0001916

Test 2	6.49694	4	0.165

Test 3	6.49694	4	0.165

Test 4	3.69539	1	0.05456

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than .1. A homogeneous variance
model appears to be appropriate here

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is less than .1. You may want to try a different
model

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	51.0107

BMDL =	3.06631

This document is a draft for review purposes only and does not constitute Agency policy.

E-459 DRAFT—DO NOT CITE OR QUOTE


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E.3.40.5. Figure for Additional Model Presented: Hill, Unrestricted

Hill Model with 0.95 Confidence Level

dose

19:53 02/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-460 DRAFT—DO NOT CITE OR QUOTE


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E.3.41. Sewall et al., 1995: T4 In Serum
E.3.41.1. Summary Table of BMDS Modeling Results

Model3

Degrees of
Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

exponential (M2)

3

0.424

205.966

5.762E+01

3.783E+01



exponential (M3)

3

0.424

205.966

5.762E+01

3.783E+01

power hit bound (d = 1)

exponential (M5)

2

0.611

206.152

2.523E+01

8.442E+00

power hit bound (d = 1)

Hillb

2

0.702

205.875

2.071E+01

5.164E+00

n lower bound hit (n = 1)

linear

3

0.332

206.584

6.788E+01

4.858E+01



polynomial, 4-
degree

3

0.332

206.584

6.788E+01

4.858E+01



power

3

0.332

206.584

6.788E+01

4.858E+01

power bound hit (power =1)

Hill, unrestricted0

1

0.844

207.205

1.657E+01

1.903E+00

unrestricted (n = 0.427)

power, unrestricted

2

0.983

205.200

1.658E+01

1.820E+00

unrestricted (power = 0.403)

a Constant variance model selected (p = 0.4078)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.3.41.2. Output for Selected Model: Hill

Sewall et al., 1995: T4 In Serum

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\1\58_Sewall_l995_T4_HillCV_l.(d)

Gnuplot Plotting File: C:\l\58_Sewall_1995_T4_HillCV_l.plt

Tue_Feb 16~19:54:30 2010

Figure 1, Saline noninitiated

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = Mean
Independent variable = Dose
rho is set to 0

Power parameter restricted to be greater than 1
A constant variance model is fit

Total number of dose groups = 5

Total number of records with missing values = 0

This document is a draft for review purposes only and does not constitute Agency policy.

E-461 DRAFT—DO NOT CITE OR QUOTE


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Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

alpha
rho

intercept

33.0913

0

30.6979
-12 .2937
0.695384
24 . 6674

Specified

Asymptotic Correlation Matrix of Parameter Estimates

alpha
intercept

The model parameter(s) -rho -n

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha
1

1. 2e-008
4 . le-008
-2 . 4e-008

intercept
1. 2e-008
1

0.14
-0. 66

v

4 . le-008
0.14
1

-0.76

k

-2 . 4e-008
-0. 66
-0.76
1

Parameter Estimates

Variable
alpha
intercept

k

Estimate

29.8807
2 9.9609
-14.2338
1

33.2198

Std. Err.
6.29941
1.64749
4 . 35645
NA

37.0852

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

17.5341
26.7319
-22 .7723

-39.4658

42 . 2274
33.1899
-5.69537

105.905

NA - Indicates that this parameter has hit a bound
implied by some ineguality constraint and thus
has no standard error.

Table of Data and Estimated Values of Interest

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0

9

30

7

30

4

6 6

5.47

0

404

3.5

9

27

9

28 . 6

7

17

5.47

-0

399

10.7

9

25

9

26.5

6

81

5.47

-0

328

35

9

23

6

22 . 7

5

38

5.47

0

493

125

9

18

4

i—1

CO

-j

4

12

5.47

-0

171

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

This document is a draft for review purposes only and does not constitute Agency policy.

E-462 DRAFT—DO NOT CITE OR QUOTE


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Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma^2
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1 -98.583448	6	209.166896

A2 -96.590204	10	213.180407

A3 -98.583448	6	209.166896

fitted -98.937315	4	205.874631

R -109.013252	2	222.026503

Explanation of Tests

Test 1:

Test

2

Test

3

Test

4

Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	24.8461	8	0.001651

Test 2	3.98649	4	0.4078

Test 3	3.98649	4	0.4078

Test 4	0.707735	2	0.702

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than .1. A homogeneous variance
model appears to be appropriate here

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adeguately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	2 0.7117

BMDL =	5.16405

This document is a draft for review purposes only and does not constitute Agency policy.

E-463 DRAFT—DO NOT CITE OR QUOTE


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E.3.41.3. Figure for Selected Model: Hill

Hill Model with 0.95 Confidence Level

dose

19:54 02/16 2010

E.3.41.4. Output for Additional Model Presented: Hill, Unrestricted
Sewall et al., 1995: T4 In Serum

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\1\58_Sewall_l995_T4_HillCV_U_l.(d)

Gnuplot Plotting File: C:\l\58_Sewall_1995_T4_HillCV_U_l.plt

Tue Feb 16 19:54:31 2010

Figure 1, Saline noninitiated

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = Mean
Independent variable = Dose
rho is set to 0

Power parameter is not restricted
A constant variance model is fit

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-464 DRAFT—DO NOT CITE OR QUOTE


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Total number of dose groups = 5

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

alpha
rho

intercept

33.0913

0

30.6979
-12 .2937
0.695384
24 . 6674

Specified

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -rho

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha
intercept

alpha
1

-0.0004
0.0059
0.0048
-0.0059

intercept

-0.0004
1

-0.026
-0.44
0. 07

v

0. 0059
-0.026
1

0 .77
-1

n

0.0048
-0.44
0 .77
1

-0. 82

k

-0.0059
0. 07
-1
-0. 82
1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
alpha
intercept

Estimate

29.4396
30.6757
-141.324
0.426599
31487

Std. Err.
6.20653
1.77521
1202.4
0.262207
770429

Lower Conf. Limit

17 . 2751
27 .1963
-2497.98
-0.0873175
-1. 47853e + 006

Upper Conf. Limit

41.6042
34.155
2215.33
0.940515
1.5415e+006

Table of Data and Estimated Values of Interest

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0

9

30

7

30.7

4

6 6

5.43

0.0123

3.5

9

27

9

27 . 8

7

17

5.43

0.0279

10.7

9

25

9

26.1

6

81

5.43

-0.137

35

9

23

6

23.3

5

38

5.43

0.132

125

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4

18 . 5

4

12

5.43

-0.0354

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij)

This document is a draft for review purposes only and does not constitute Agency policy.

E-465 DRAFT—DO NOT CITE OR QUOTE


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Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma^2
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model
A1
A2
A3

fitted
R

Log(likelihood)
-98.583448
-96.590204
-98.583448
-98.602701
-109.013252

10

AIC
209.166896
213.180407
209.166896
207.205403
222.026503

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1
Test 2
Test 3
Test 4

24.8461
3.98649
3.98649
0.0385071

0.001651
0.4078
0.4078
0.8444

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than .1. A homogeneous variance
model appears to be appropriate here

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adeguately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	16.568 9

BMDL =	1.90347

This document is a draft for review purposes only and does not constitute Agency policy.

E-466 DRAFT—DO NOT CITE OR QUOTE


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E.3.41.5. Figure for Additional Model Presented: Hill, Unrestricted

Hill Model with 0.95 Confidence Level

dose

19:54 02/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-467 DRAFT—DO NOT CITE OR QUOTE


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E.3.42. Shi et al., 2007: Estradiol 17B, PE9
E.3.42.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

exponential (M2)

3

0.001

395.701

1.729E+01

8.956E+00



exponential (M3)

3

0.001

395.701

1.729E+01

8.956E+00

power hit bound (d = 1)

exponential (M4)b

2

0.494

383.635

5.559E-01

2.236E-01



exponential (M5)

2

0.494

383.635

5.559E-01

2.236E-01

power hit bound (d = 1)

Hill

2

0.773

382.743

4.434E-01

error

n lower bound hit (n = 1)

linear

3

0.001

397.484

2.243E+01

1.523E+01



polynomial, 4-
degree

3

0.001

397.484

2.243E+01

1.523E+01



power

3

0.001

397.484

2.243E+01

1.523E+01

power bound hit (power = 1)

Hill, unrestricted

1

0.874

384.251

3.998E-01

error

unrestricted (n = 0.616)

power, unrestricted

2

0.506

383.589

3.409E-01

5.002E-03

unrestricted (power = 0.155)

a Non-constant variance model selected (p = 0.0521)
b Best-fitting model, BMDS output presented in this appendix

E.3.42.2. Output for Selected Model: Exponential (M4)

Shi et al., 2007: Estradiol 17B, PE9

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\1\59_Shi_2007_Estradiol_Exp_l.(d)

Gnuplot Plotting File:

Tue Feb 16 19:55:06 2010

Figure 4 PE9 only

The form of the response function by Model:

Model 2
Model 3
Model 4
Model 5

Y[dose]
Y[dose]
Y[dose]
Y[dose]

exp{sign *	b * dose}

exp{sign *	(b * dosej^d}

[c-(c-l) *	exp{-b * dose}]

[c-(c-l) *	exp{-(b * dosej^d}

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;
sign = -1 for decreasing trend.

Model 2 is nested within Models 3 and 4.

This document is a draft for review purposes only and does not constitute Agency policy.

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Model 3 is nested within Model 5.
Model 4 is nested within Model 5.

Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)
Total number of dose groups = 5

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values
Variable	Model 4

lnalpha	2.65881

rho	0.913414

a	108

b	0.136287

c	0.340136

d	1

Parameter Estimates
Variable	Model 4

lnalpha	1.81331

rho	1.12126

a	100.526

b	1.53823

c	0.431796

d	1

Table of Stats From Input	Data

Dose	N	Obs Mean	Obs Std Dev

0	10	102.9	41.41

0.143	10	86.19	19.58

0.714	10	63.33	29.36

7.14	10	48.1	18.82

28.6	10	38.57	22.59

Estimated Values of Interest
Dose	Est Mean	Est Std	Scaled Residual

0	100.5	32.83	0.2245

0.143	89.25	30.71	-0.3147

0.714	62.45	25.14	0.1108

7.14	43.41	20.5	0.723

28.6	43.41	20.5	-0.7458

Other models for which likelihoods are calculated:

Model A1:	Yij = Mu(i) + e(ij)

This document is a draft for review purposes only and does not constitute Agency policy.

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Var{e(ij)}	= Sigma^2

Model A2 :	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma(i)^2

Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= exp(lalpha + log(mean(i) ) 'k rho)

Model R:	Yij	= Mu + e(i)

Var{e(ij)}	= Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	DF	AIC

A1	-188.3615	6	388.7231

A2	-183.667	10	387.3339

A3	-186.1132	7	386.2263

R	-203.3606	2	410.7211

4	-186.8176	5	383.6352

Additive constant for all log-likelihoods =	-45.95. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Test

1:

Does response

and/or variances differ among Dose levels? (A2 vs. R)

Test

2 :

Are Variances

Homogeneous? (A2 vs. A1)

Test

3:

Are variances

adequately modeled? (A2 vs. A3)

Test 6a: Does Model 4 fit the data? (A3 vs 4)

Test

Test 1
Test 2
Test 3
Test 6a

Tests of Interest

-2*log(Likelihood Ratio)

39.39
9.389
4 . 892
1.409

D. F.

p-value

< 0.0001
0.05208
0.1798
0.4944

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose
levels, it seems appropriate to model the data.

The p-value for Test 2 is less than .1. A non-homogeneous
variance model appears to be appropriate.

The p-value for Test 3 is greater than .1. The modeled
variance appears to be appropriate here.

The p-value for Test 6a is greater than .1. Model 4 seems
to adeguately describe the data.

Benchmark Dose Computations:

Specified Effect = 1.000000

Risk Type = Estimated standard deviations from control
Confidence Level = 0.950000

BMD =	0.555948

This document is a draft for review purposes only and does not constitute Agency policy.

E-470 DRAFT—DO NOT CITE OR QUOTE


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0.223612

5 E.3.42.3. Figure for Selected Model: Exponential (M4)

Exponential_beta Model 4 with 0.95 Confidence Level

a>

CO
c
o

Q.

CO
CD

a:

c
m

CD

140

120

100

80

60

40

20

E:MDL

BMD

19:55 02/16 2010

Exponential

10

15
dose

20

25

30

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.3.43. Smialowicz et al., 2008: PFC per 10A6 Cells
E.3.43.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

exponential (M2)

3

0.048

903.586

8.234E+01

4.833E+01



exponential (M3)

3

0.048

903.586

8.234E+01

4.833E+01

power hit bound (d = 1)

exponential (M4)

2

0.019

905.578

8.032E+01

6.220E+00



exponential (M5)

2

0.019

905.578

8.032E+01

6.220E+00

power hit bound (d = 1)

Hill

2

0.026

904.975

1.617E+01

2.214E+00

n lower bound hit (n = 1)

linear

3

0.016

905.992

1.450E+02

1.102E+02



polynomial, 4-
degree

2

<0.0001

1198.471

1.375E+03

3.331E+01



power0

3

0.016

905.992

1.450E+02

1.102E+02

power bound hit (power =1)

Hill, unrestricted

1

0.183

901.442

8.297E+00

4.172E-01

unrestricted (n = 0.266)

power,
unrestricted b

2

0.446

899.282

7.676E+00

4.087E-01

unrestricted (power = 0.249)

a Constant variance model selected (p = <0.0001)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.3.43.2. Output for Selected Model: Power, Unrestricted

Smialowicz et al., 2008: PFC per 10A6 Cells

Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\1\60_Smial_2008_PFCcells_PwrCV_U_l.(d)

Gnuplot Plotting File: C:\l\60_Smial_2008_PFCcells_PwrCV_U_l.plt

_Tue Feb 16 19:55753 2010

Anti Response to SRBCs, PFC per 10to6 cells, Table 4

The form of the response function is:

Y[dose] = control + slope * doseApower

Dependent variable = Mean
Independent variable = Dose
rho is set to 0

This document is a draft for review purposes only and does not constitute Agency policy.

E-472 DRAFT—DO NOT CITE OR QUOTE


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The power is not restricted
A constant variance model is fit

Total number of dose groups = 5

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

alpha
rho
control
slope
power

232385

0

1491
-384.362
0.215085

Specified

Asymptotic Correlation Matrix of Parameter Estimates

alpha
control

The model parameter(s) -rho

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha
1

-1. 5e-009

control
-1.5e-009
1

slope
J. 2e-009
-0.79

power
-1. le-008
-0. 65

slope -8.2e-009	-0.79	1	0.96

power -1.le-008	-0.65	0.96	1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
alpha
control
slope
power

Estimate

220294
1470.38
-282.777
0.248621

Std. Err.

38061.1
124.07
145.113
0.0856348

Lower Conf. Limit

145696
1227.21
-567.193
0.0807799

Upper Conf. Limit

294893
1713.55
1. 64025
0. 416462

Table of Data and Estimated Values of Interest
Dose	N Obs Mean	Est Mean Obs Std Dev Est Std Dev Scaled Res.

0

15

1. 4 9e + 003

1. 47e + 003

716

469

0.17

1 . 07

14

1.13e + 003

1.18e + 003

171

469

-0.429

10.7

15

945

961

516

469

-0.129

107

15

677

567

465

469

0. 91

321

8

161

283

117

469

-0.735

Model Descriptions for likelihoods calculated

Model A1:	Yij	= Mu(i) + e(iji

Var{e(ij)} = Sigma/'2

Model A2:	Yij	= Mu(i) + e(ij|

Var{e(ij)} = Sigma(i)^2

This document is a draft for review purposes only and does not constitute Agency policy.

E-473 DRAFT—DO NOT CITE OR QUOTE


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Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma^2
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model	Log(likelihood) # Param's	AIC

A1 -444.832859	6	901.665718

A2 -425.402825	10	870.805651

A3 -444.832859	6	901.665718

fitted -445.641102	4	899.282205

R -463.753685	2	931.507371

Explanation of Tests

Test 1:

Test

2

Test

3

Test

4

Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	76.7017	8	<.0001

Test 2	38.8601	4	<.0001

Test 3	38.8601	4	<.0001

Test 4	1.61649	2	0.4456

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. Consider running a
non-homogeneous variance model

The p-value for Test 3 is less than .1. You may want to consider a
different variance model

The p-value for Test 4 is greater than .1. The model chosen seems
to adeguately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD = 7.67 564

BMDL = 0.408661

This document is a draft for review purposes only and does not constitute Agency policy.

E-474 DRAFT—DO NOT CITE OR QUOTE


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E.3.43.3. Figure for Selected Model: Power, Unrestricted

Power Model with 0.95 Confidence Level

dose

19:55 02/16 2010

E.3.43.4. Output for Additional Model Presented: Power
Smialowicz et al., 2008: PFC per 10A6 Cells

Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\1\60_Smial_2008_PFCcells_PwrCV_l.(d)

Gnuplot Plotting File: C:\l\60_Smial_2008_PFCcells_PwrCV_l.plt

Tue Feb 16 19:55:53 2010

Anti Response to SRBCs, PFC per 10to6 cells, Table 4

The form of the response function is:
Y[dose] = control + slope * doseApower

Dependent variable = Mean
Independent variable = Dose
rho is set to 0

The power is restricted to be greater than or egual to 1
A constant variance model is fit

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-475 DRAFT—DO NOT CITE OR QUOTE


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69

70

Total number of dose groups = 5

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

alpha =	232385

rho =	0 Specified

control =	1491

slope =	-2925.99

power = -0.136613

Asymptotic Correlation Matrix of Parameter Estimates

alpha
control
slope

The model parameter(s) -rho -power

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha
1

3.6e-0 0 9
-1.2e-008

control

3.6e-0 0 9
1

-0.53

slope
-1.2e-008
-0.53
1

Parameter Estimates

Variable
alpha
control
slope
power

Estimate

250878
1176.24
-3.45384
1

Std. Err.
43345.1
72 .2586
0.592114
NA

NA - Indicates that this parameter has hit a bound
implied by some inequality constraint and thus
has no standard error.

Table of Data and Estimated Values of Interest

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

165923
1034.61
-4.61436

335833
1317.86
-2 .29332

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0

15

1. 4 9e + 003

1.18e + 003

716

501

2 .43

1 . 07

14

1.13e + 003

1.17e + 003

171

501

-0.325

10.7

15

945

1.14e + 003

516

501

-1. 5

107

15

677

807

465

501

-1

321

8

161

67 . 6

117

501

0.528

Model Descriptions for likelihoods calculated

Model A1:

Yij

Var{e ( ij ;

Mu(i) + e(ij ;
Sigma/N2

Model A2:

Yij

Var{e ( ij ;

Mu(i) + e(ij ;

Sigma(i)^2

This document is a draft for review purposes only and does not constitute Agency policy.

E-476 DRAFT—DO NOT CITE OR QUOTE


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Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma^2
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model	Log(likelihood) # Param's	AIC

A1 -444.832859	6	901.665718

A2 -425.402825	10	870.805651

A3 -444.832859	6	901.665718

fitted -449.996183	3	905.992366

R -463.753685	2	931.507371

Explanation of Tests

Test 1:

Test

2

Test

3

Test

4

Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	76.7017	8	<.0001

Test 2	38.8601	4	<.0001

Test 3	38.8601	4	<.0001

Test 4	10.3266	3	0.01598

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. Consider running a
non-homogeneous variance model

The p-value for Test 3 is less than .1. You may want to consider a
different variance model

The p-value for Test 4 is less than .1. You may want to try a different
model

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD = 145.02

BMDL = 110.161

This document is a draft for review purposes only and does not constitute Agency policy.

E-477 DRAFT—DO NOT CITE OR QUOTE


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E.3.43.5. Figure for Additional Model Presented: Power

Power Model with 0.95 Confidence Level

dose

19:55 02/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-478 DRAFT—DO NOT CITE OR QUOTE


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E.3.44. Smialowicz et al., 2008: PFC per Spleen

E.3.44.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

exponential (M2)

3

0.133

377.395

1.320E+02

8.431E+01



exponential (M3)

3

0.133

377.395

1.320E+02

8.431E+01

power hit bound (d = 1)

exponential (M4)

3

0.133

377.395

1.320E+02

8.184E+01



exponential (M5)

2

0.061

379.395

1.320E+02

8.184E+01

power hit bound (d = 1)

Hill

2

0.069

379.150

1.401E+02

error

n lower bound hit (n = 1)

linear

3

0.044

379.895

2.151E+02

1.704E+02



polynomial, 4-
degree

3

0.044

379.895

2.151E+02

1.704E+02



power0

3

0.044

379.895

2.151E+02

1.704E+02

power bound hit (power =1)

Hill, unrestricted

2

<0.0001

441.885

7.545E-23

error

unrestricted (n = 0.038)

power,
unrestricted b

2

0.230

376.738

9.374E+01

2.088E+01

unrestricted (power = 0.418)

a Non-constant variance model selected (p = 0.0011)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.3.44.2. Output for Selected Model: Power, Unrestricted

Smialowicz et al., 2008: PFC per Spleen

Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\1\61_Smial_2008_PFCspleen_Pwr_U_l.(d)

Gnuplot Plotting File: C:\l\61_Smial_2008_PFCspleen_Pwr_U_l.plt

_Tue Feb 16 19756:26 2010

Anti Response to SRBCs - PFC x 10 to the 4 per spleen, Table 4

The form of the response function is:

Y[dose] = control + slope * doseApower

Dependent variable = Mean
Independent variable = Dose
The power is not restricted

This document is a draft for review purposes only and does not constitute Agency policy.

E-479 DRAFT—DO NOT CITE OR QUOTE


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The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)
Total number of dose groups = 5

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
lalpha =	4.76607

rho =	0

control =	27.8

slope =	-7.21601

power =	0.213905

Asymptotic Correlation Matrix of Parameter Estimates

lalpha	rho	control	slope	power

lalpha 1	-0.98	0.25	-0.27	-0.23

rho -0.98	1	-0.31	0.28	0.23

control 0.25	-0.31	1	-0.81	-0.74

slope -0.27	0.28	-0.81	1	0.99

power -0.23	0.23	-0.74	0.99	1

Parameter Estimates

Variable
lalpha
rho
control
slope
power

Estimate
0.747155
1. 36972
25.1733
-1.98465
0. 417867

Std. Err.

1. 0244
0.357098
2.93169
1. 82113
0.141932

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

-1.26063

0.66982
19.4273
-5.554
0.139686

2.75494

2.06962
30.9193
1.5847
0.696048

Table of Data and Estimated Values of Interest

Dose

N

Obs Mean

Est Mean

Obs Std Dev

Est Std Dev

Scaled Res

0

15

27 . 8

25.2

13

4

13.2

0.769

1. 07

14

21

23.1

13

6

12 . 5

-0.639

10.7

15

17 . 6

19.8

9

4

11. 2

-0.768

107

15

12 . 6

11 2

8

7

7 .59

0.721

321

8

3

3. 04

3

1

3.11

-0.0353

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))

This document is a draft for review purposes only and does not constitute Agency policy.

E-480 DRAFT—DO NOT CITE OR QUOTE


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Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1 -190.565019	6	393.130038

A2 -181.476284	10	382.952569

A3 -181.900030	7	377.800059

fitted -183.369059	5	376.738118

R -204.636496	2	413.272993

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Test

2

Test

3

Test

4

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	46.3204	8	<.0001

Test 2	18.1775	4	0.001139

Test 3	0.84749	3	0.8381

Test 4	2.93806	2	0.2301

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adeguately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD = 93.7416

BMDL = 20.8758

This document is a draft for review purposes only and does not constitute Agency policy.

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E.3.44.3. Figure for Selected Model: Power, Unrestricted

Power Model with 0.95 Confidence Level

35

30

25

CD
CO
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0	50	100	150	200	250	300

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19:56 02/16 2010

E.3.44.4. Output for Additional Model Presented: Power
Smialowicz et al., 2008: PFC per Spleen

Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\1\61_Smial_2008_PFCspleen_Pwr_l.(d)

Gnuplot Plotting File: C:\l\61_Smial_2008_PFCspleen_Pwr_l.plt

Tue Feb 16 19:56:25 2010

Anti Response to SRBCs - PFC x 10 to the 4 per spleen, Table 4

The form of the response function is:
Y[dose] = control + slope * doseApower

Dependent variable = Mean
Independent variable = Dose

The power is restricted to be greater than or egual to 1

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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Total number of dose groups = 5

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
lalpha =	4.76607

rho =	0

control =	27.8

slope =	-54.5244

power = -0.136501

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -power

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

lalpha	rho	control	slope

lalpha	1	-0.98	0.16	-0.48

rho	-0.98	1	-0.25	0.54

control
slope

o.ie

-0. 4E

-0.25
0.54

-0. I

-OA

Parameter Estimates

95.0% Wald Confidence Interval

Variable
lalpha
rho
control
slope
power

Estimate

0. 474614
1.48709
21.3571
-0.0574184
1

Std. Err.
1.09569
0.385029
1.69233
0. 00632057
NA

Lower Conf. Limit

-1.6729
0.732449
18.0402
-0.0698064

Upper Conf. Limit

2.62213
2 .24173
24.674
-0.0450303

NA - Indicates that this parameter has hit a bound
implied by some inequality constraint and thus
has no standard error.

Table of Data and Estimated Values of Interest

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0

15

27 . 8

21. 4

13

4

12 . 3

2 . 02

1 . 07

14

21

21. 3

13

6

12 . 3

-0.0898

10.7

15

17 . 6

20.7

9

4

12 .1

-1. 01

107

15

12 . 6

15.2

8

7

9.6

-1. 05

321

8

3

2 . 93

3

1

2 . 82

0.0745

Model

Descriptions for

likelihoods

calculated







Model

A1:

Yij =

Mu(i) + e(ij

)









Var {e

ij ) } =

Sigma/N2









Model A2:	Yij = Mu(i) + e(ij)

This document is a draft for review purposes only and does not constitute Agency policy.

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Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1 -190.565019	6	393.130038

A2 -181.476284	10	382.952569

A3 -181.900030	7	377.800059

fitted -185.947278	4	379.894555

R -204.636496	2	413.272993

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1
Test 2
Test 3
Test 4

46.3204
18.1775
0.84749
8.0945

<.0001
0.001139
0.8381
0.0441

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is less than .1. You may want to try a different
model

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD = 215.073

BMDL = 17 0.412

This document is a draft for review purposes only and does not constitute Agency policy.

E-484 DRAFT—DO NOT CITE OR QUOTE


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E.3.44.5. Figure for Additional Model Presented: Power

Power Model with 0.95 Confidence Level

dose

19:56 02/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-485 DRAFT—DO NOT CITE OR QUOTE


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E.3.45. Toth et al., 1979: Amyloidosis

E.3.45.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

gamma

2

0.022

150.666

2.296E+02

1.460E+02

power bound hit (power =1)

logistic

2

0.013

152.187

4.088E+02

3.125E+02

negative intercept (intercept = -
2.098)

log-logistica

2

0.028

149.984

1.759E+02

9.729E+01

slope bound hit (slope = 1)

log-probit

2

0.007

153.479

4.402E+02

2.965E+02

slope bound hit (slope =1)

multistage, 3-
degree

2

0.022

150.666

2.296E+02

1.460E+02

final B = 0

probit

2

0.014

152.040

3.846E+02

2.911E+02

negative intercept (intercept = -
1.238)

Weibull

2

0.022

150.666

2.296E+02

1.460E+02

power bound hit (power =1)

gamma,
unrestricted

2

0.917

140.208

7.687E-01

7.637E-04

unrestricted (power =0.187)

log-logistic,
unrestricted b

2

0.847

140.370

8.465E-01

1.565E-03

unrestricted (slope = 0.238)

log-probit,
unrestricted

2

0.811

140.458

8.545E-01

2.334E-03

unrestricted (slope = 0.135)

Weibull,
unrestricted

2

0.882

140.287

8.179E-01

1.140E-03

unrestricted (power = 0.212)

a Best-fitting model, BMDS output presented in this appendix
b Alternate model, BMDS output also presented in this appendix

E.3.45.2. Output for Selected Model: Log-Logistic

Toth et al., 1979: Amyloidosis

Logistic Model. (Version: 2.12; Date: 05/16/2008)

Input Data File: C:\1\62_Toth_l979_Amylyr_LogLogistic_l.(d)

Gnuplot Plotting File: C:\l\62_Toth_197 9_Amylyr_LogLogistic_l.plt

Tue Feb 16 19:56:59 2010

Table 2

The form of the probability function is:

P[response] = background+(1-background)/[1+EXP(-intercept-slope*Log(dose))]

Dependent variable = DichEff
Independent variable = Dose

This document is a draft for review purposes only and does not constitute Agency policy.

E-486 DRAFT—DO NOT CITE OR QUOTE


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Slope parameter is restricted as slope >= 1

Total number of observations = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

User has chosen the log transformed model

Default Initial Parameter Values
background =	0

intercept =	-6.90711

slope =	1

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -slope

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

background intercept

background	1	-0.47

intercept	-0.47	1

Parameter Estimates

95.0% Wald Confidence Interval

Variable Estimate Std. Err.	Lower Conf. Limit Upper Conf. Limit

background 0.0848984 *	*	*

intercept -7.36716 *	*	*

slope 1 *	*	*

Indicates that this value is not calculated.

Analysis of Deviance Table

Model	Log(likelihood)	# Param's	Deviance	Test d.f.	P-value

Full model	-68.017	4

Fitted model	-72.9918	2	9.9496	2	0.00691

Reduced model	-82.0119	1	27.99	3	<.0001

AIC:	149.984

Goodness of Fit

Scaled

Dose Est. Prob. Expected Observed	Size	Residual

0.0000 0.0849 3.226 0.000	38	-1.878

1.0000 0.0855 3.761 5.000	44	0.668

100.0000 0.1393 6.128 10.000	44	1.686

1000.0000 0.4392 18.884 17.000	43	-0.579

Chi ^2 = 7.15	d.f. = 2	P-value = 0.0280

Benchmark Dose Computation
Specified effect =	0.1

This document is a draft for review purposes only and does not constitute Agency policy.

E-487 DRAFT—DO NOT CITE OR QUOTE


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Risk Type
Confidence level
BMD
BMDL

Extra risk
0. 95
175.903
97.2899

E.3.45.3. Figure for Selected Model: Log-Logistic

Log-Logistic Model with 0.95 Confidence Level

"O

(D

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o

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!t=
<

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0.5

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19:56 02/16 2010

E.3.45.4. Output for Additional Model Presented: Log-Logistic, Unrestricted
Toth et al., 1979: Amyloidosis

Logistic Model. (Version: 2.12; Date: 05/16/2008)

Input Data File: C:\1\62_Toth_l979_Amylyr_LogLogistic_U_l.(d)

Gnuplot Plotting File: C:\l\62_Toth_197 9_Amylyr_LogLogistic_U_l.plt

Tue Feb 16 19:57:00 2010

Table 2

This document is a draft for review purposes only and does not constitute Agency policy.

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The form of the probability function is:

P[response] = background+(1-background)/[1+EXP(-intercept-slope*Log(dose))]

Dependent variable = DichEff
Independent variable = Dose
Slope parameter is not restricted

Total number of observations = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

User has chosen the log transformed model

Default Initial Parameter Values
background =	0

intercept =	-2.10894

slope =	0.227921

Asymptotic Correlation Matrix of Parameter Estimates

The model parameter(s) -background

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

intercept	slope

intercept	1	-0.89

slope	-0.89	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

background	0	*	*	*

intercept	-2.15753	*	*	*

slope	0.238304	*	*	*

Indicates that this value is not calculated.

Analysis of Deviance Table

Model	Log(likelihood)	# Param's	Deviance	Test d.f.	P-value

Full model	-68.017	4

Fitted model	-68.1848	2	0.33571	2	0.8455

Reduced model	-82.0119	1	27.99	3	<.0001

AIC:	140.37

Goodness of Fit

Scaled

Dose Est. Prob. Expected Observed	Size	Residual

0.0000 0.0000 0.000 0.000	38 0.000

1.0000 0.1036 4.560 5.000	44 0.218

100.0000 0.2573 11.321 10.000	44	-0.456

1000.0000 0.3749 16.119 17.000	43 0.277

This document is a draft for review purposes only and does not constitute Agency policy.

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Chi' 2 = 0.33	d.f. = 2

E'-value =

0.8471

E'.enchmark Dose Computation
Specified effect =	0 .1

Risk Typ'e	=	E::tra risk

Cc'nfidence level =	0.95

BMD =	0.846547

BMDL =	0.0 015 653 4

E.3.45.5. Figure for Additional Model Presented: Log-Logistic, Unrestricted

Log-Logistic Model with 0.95 Confidence Level

"O

(D

-t—<

o

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!t=
<

200

400	600

dose

800

1000

19:57 02/16 2010

This document is a draft for review purposes only and does not constitute Agency policy.

E-490 DRAFT—DO NOT CITE OR QUOTE


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E.3.46. Toth et al., 1979: Skin Lesions

E.3.46.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

gamma

2

0.009

159.223

1.181E+02

8.308E+01

power bound hit (power =1)

logistica

2

0.002

162.974

2.709E+02

2.147E+02

negative intercept (intercept =
-2.098)

log-logistic

2

0.029

156.567

6.750E+01

4.057E+01

slope bound hit (slope =1)

log-probit

2

0.001

164.598

2.446E+02

1.626E+02

slope bound hit (slope =1)

multistage, 3-
degree

2

0.009

159.223

1.181E+02

8.308E+01

final B = 0

probit

2

0.003

162.684

2.522E+02

2.015E+02

negative intercept (intercept = -
1.238)

Weibull

2

0.009

159.223

1.181E+02

8.308E+01

power bound hit (power =1)

gamma,
unrestricted

2

0.882

147.287

error

error

unrestricted (power = 0.251)

log-logistic,
unrestricted b

2

0.630

147.969

1.137E+00

5.477E-02

unrestricted (slope = 0.351)

log-probit,
unrestricted

2

0.558

148.218

1.096E+00

6.847E-02

unrestricted (slope = 0.202)

Weibull,
unrestricted

2

0.762

147.581

1.077E+00

4.080E-02

unrestricted (power = 0.3)

a Best-fitting model, BMDS output presented in this appendix
b Alternate model, BMDS output also presented in this appendix

E.3.46.2. Output for Selected Model: Logistic

Toth et al., 1979: Skin Lesions

Logistic Model. (Version: 2.12; Date: 05/16/2008)

Input Data File: C:\1\63_Toth_l979_SkinLes_Logistic_l.(d)

Gnuplot Plotting File: C:\l\63_Toth_197 9_SkinLes_Logistic_l.plt

Tue Feb 16 19:57:29 2010

Table 2

The form of the probability function is:

P[response] = 1/[1+EXP(-intercept-slope^dose)]

Dependent variable = DichEff
Independent variable = Dose

This document is a draft for review purposes only and does not constitute Agency policy.

E-491 DRAFT—DO NOT CITE OR QUOTE


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Slope parameter is not restricted
Total number of observations = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

background =	0 Specified

intercept =	-2.53484

slope = 0.00299511

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -background

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

intercept	slope

intercept	1	-0.67

slope	-0.67	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

intercept	-1.91768	0.26892	-2.44475	-1.39061

slope	0.00230499	0.000419329	0.00148312	0.00312686

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-71.5177	4

Fitted model -79.487 2	15.9387 2	0.0003459

Reduced model -95.8498 1	48.6642 3	<.0001

AIC:	162.974

Goodness of Fit

Scaled

Dose	Est. Prob. Expected Observed	Size	Residual

0.0000

0.1281

4 .869

0. 000

38

-2.363

1.0000

0.1284

5. 649

5. 000

44

-0.292

100.0000

0.1561

6. 870

13.000

44

2.546

1000.0000

0.5956

25.612

25.000

43

-0.190

Chi ^2 = 12.19	d.f. = 2	P-value = 0.0023

Benchmark Dose Computation
Specified effect =	0.1

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	270.917

This document is a draft for review purposes only and does not constitute Agency policy.

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E'.MDL =

214.66

E.3.46.3. Figure for Selected Model: Logistic

Logistic Model with 0.95 Confidence Level

200	400	600	800	1000

dose

19:57 02/16 2010

E.3.46.4. Output for Additional Model Presented: Log-Logistic, Unrestricted
Toth et al., 1979: Skin Lesions

			 1 ¦ i ¦ ¦ ¦ 1 1 ¦ ¦ ¦ ¦ i ¦ 1 			 1 			 1 			 1 1 1 r

Logistic 	

BMDL

j	i	i	L

BMD

Logistic Model. (Version: 2.12; Date: 05/16/2008)

Input Data File: C:\1\63_Toth_l979_SkinLes_LogLogistic_U_l.(d)

Gnuplot Plotting File: C:\l\63_Toth_197 9_SkinLes_LogLogistic_U_l.plt

Tue Feb 16 20:01:56 2010

Table 2

The form of the probability function is:

P[response] = background+(1-background)/[1+EXP(-intercept-slope*Log(dose))]

Dependent variable = DichEff

This document is a draft for review purposes only and does not constitute Agency policy.

E-493 DRAFT—DO NOT CITE OR QUOTE


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Independent variable = Dose
Slope parameter is not restricted

Total number of observations = 4

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

User has chosen the log transformed model

Default Initial Parameter Values
background =	0

intercept =	-2.14055

slope =	0.332 4 0 9

Asymptotic Correlation Matrix of Parameter Estimates

The model parameter(s) -background

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

intercept	slope

intercept	1	-0.9

slope	-0.9	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

background	0	*	*	*

intercept	-2.24241	*	*	*

slope	0.350932	*	*	*

Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-71.5177	4

Fitted model -71.9844 2	0.93345 2	0.6271

Reduced model -95.8498 1	48.6642 3	<.0001

AIC:	147.969

Goodness of Fit

Scaled

Dose	Est. Prob. Expected Observed	Size	Residual

0.0000
1.0000
100.0000
1000.0000

0.0000
0.0960
0.3483
0.5453

0. 000
4 . 224
15.327
23.448

0. 000
5. 000
13.000
25.000

38
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0. 000
0.397
-0.736
0.475

Chi ^2

0. 93

d.f.

P-value

0.6295

Benchmark Dose Computation

This document is a draft for review purposes only and does not constitute Agency policy.

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Specified effect =	0.1

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	1.137 4

BMDL =	0.0547689

E.3.46.5. Figure for Additional Model Presented: Log-Logistic, Unrestricted

Log-Logistic Model with 0.95 Confidence Level

200	400	600	800	1000

dose

20:01 02/16 2010

			 1 1 i 1 1 1 1 1 1 1 1 1 i 1 1 			 1 			 1 			 1 1 1 r

Log-Logistic 	

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.3.47. Van Birgelen et al., 1995a: Hepatic Retinol
E.3.47.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

exponential (M2)

4

<0.0001

164.340

2.912E+02

error



exponential (M3)

4

<0.0001

164.340

2.912E+02

error

power hit bound (d = 1)

exponential (M4)b

3

<0.0001

148.052

1.151E+02

7.098E+01



exponential (M5)

3

<0.0001

148.052

1.151E+02

7.098E+01

power hit bound (d = 1)

Hill

3

0.044

128.757

1.314E+01

error

n lower bound hit (n = 1)

linear

4

<0.0001

178.734

7.815E+02

5.997E+02



polynomial, 5-degree

0

N/A

283.606

2.481E+03

error



power

4

<0.0001

178.734

7.815E+02

5.997E+02

power bound hit (power =1)

Hill, unrestricted

2

0.269

125.273

5.561E+00

error

unrestricted (n = 0.571)

power, unrestricted0

3

0.025

129.990

4.205E-01

8.504E-03

unrestricted (power = 0.118)

a Non-constant variance model selected (p = <0.0001)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.3.47.2. Output for Selected Model: Exponential (M4)

Van Birgelen et al., 1995a: Hepatic Retinol

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\1\65_VanB_l995a_HepRet_Exp_l.(d)

Gnuplot Plotting File:

Tue Feb 16 20:03:05 2010

Tbl3, hepatic retinol

The form of the response function by Model:

Model 2
Model 3
Model 4
Model 5

Y[dose]
Y[dose]
Y[dose]
Y[dose]

exp{sign *	b * dose}

exp{sign *	(b * dosej^d}

[c-(c-l) *	exp{-b * dose}]

[c-(c-l) *	exp{-(b * dosej^d}

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;

This document is a draft for review purposes only and does not constitute Agency policy.

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sign = -1 for decreasing trend.

Model 2 is nested within Models 3 and 4.
Model 3 is nested within Model 5.

Model 4 is nested within Model 5.

Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)
Total number of dose groups = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values
Variable	Model 4

lnalpha	-1.16065

rho	1.53688

a	15.645

b	0.00625117

c	0.0365247

d	1

Parameter Estimates
Variable	Model 4

lnalpha	-0.882225

rho	1.82707

a	10.5294

b	0.00720346

c	0.0688661

d	1

Table of Stats From Input Data
Dose	N	Obs Mean	Obs Std Dev

0	8	14.9	8.768

14	8	8.4	3.394

26	8	8.2	2.263

47	8	5.1	0.8485

320	8	2.2	0.8485

1024	8	0.6	0.5657

Estimated Values of Interest
Dose	Est Mean	Est Std	Scaled Residual

0	10.53	5.526	2.237

14	9.589	5.073	-0.6628

26	8.855	4.717	-0.3926

47	7.714	4.159	-1.778

320	1.703	1.046	1.343

1024	0.7313	0.4833	-0.7681

This document is a draft for review purposes only and does not constitute Agency policy.

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Other models for which	likelihoods are calculated:

Model A1:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma/'2

Model A2 :	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma(i)^2

Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= exp(lalpha + log(mean(i)) * rho)

Model R:	Yij	= Mu + e(i)

Var{e(ij)}	= Sigma/'2

Likelihoods of Interest

Model	Log(likelihood)	DF	AIC

A1	-87.1567	7	188.3134

A2	-47.28742	12	118.5748

A3	-55.32422	8	126.6484

R	-109.967	2	223.934

4	-69.02619	5	148.0524

Additive constant for all log-likelihoods =	-44.11. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Test

1:

Does response

and/or variances differ among Dose levels? (A2 vs. R)

Test

2 :

Are Variances

Homogeneous? (A2 vs. A1)

Test

3:

Are variances

adeguately modeled? (A2 vs. A3)

Test 6a: Does Model 4 fit the data? (A3 vs 4)

Test

Test 1
Test 2
Test 3
Test 6a

Tests of Interest

-2*log(Likelihood Ratio)

125. 4
79.74
16. 07
27 . 4

10
5
4
3

p-value

<	0.0001

<	0.0001
0. 002922

<	0.0001

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose
levels, it seems appropriate to model the data.

The p-value for Test 2 is less than .1. A non-homogeneous
variance model appears to be appropriate.

The p-value for Test 3 is less than .1. You may want to
consider a different variance model.

The p-value for Test 6a is less than .1. Model 4 may not adeguately
describe the data; you may want to consider another model.

Benchmark Dose Computations:

Specified Effect = 1.000000

This document is a draft for review purposes only and does not constitute Agency policy.

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Risk Type = Estimated standard deviations from control
Confidence Level = 0.950000

BMD =	115.128

BMDL =	70.981

E.3.47.3. Figure for Selected Model: Exponential (M4)

Exponential_beta Model 4 with 0.95 Confidence Level

dose

20:03 02/16 2010

E.3.47.4. Output for Additional Model Presented: Power, Unrestricted
Van Birgelen et al., 1995a: Hepatic Retinol

Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\1\65_VanB_l995a_HepRet_Pwr_U_l.(d)

Gnuplot Plotting File: C:\l\65_VanB_19 95a_HepRet_Pwr_U_l.plt

Tue Feb 16 20:03:11 2010

Tbl3, hepatic retinol

The form of the response function is:

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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Y[dose]

control + slope * doseApower

Dependent variable = Mean

Independent variable = Dose

The power is not restricted

The variance is to be modeled as Var(i)

exp(lalpha + log(mean(i))

rho)

Total number of dose groups = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
lalpha =	2.76506

rho =	0

control =	14.9

slope =	-3.78637

power =	0.191713

Asymptotic Correlation Matrix of Parameter Estimates

lalpha
rho
control
slope
power

lalpha
1

-0.8

-0.047
0. 042
0. 065

rho
-0.8

1

-0.085
-0.0029
-0.11

control

-0.047
-0.085
1

-0. 95
-0. 81

slope

0. 042
-0.0029
-0. 95
1

0. 96

power

0. 065
-0.11
-0. 81
0. 96
1

Parameter Estimates

Variable
lalpha
rho
control
slope
power

Estimate

-1.02622
1. 68421
16.9577
-7 .19097
0.117935

Std. Err.
0.389164
0.199212
2.21133
1.99708
0.0225396

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

-1.78897

1. 29376
12.6235
-11.1052
0.0737578

-0.263475

2 . 07466
21.2918
-3.27676
0.162111

Table of Data and Estimated Values of Interest

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0	8	14.9	17	8.77	6.4 9	-0.896

14	8	8.4	7.14	3.39	3.13	1.14

26	8	8.2	6.4	2.26	2.86	1.78

47	8	5.1	5.63	0.849	2.57	-0.588

320	8	2.2	2.76	0.849	1.41	-1.12

1024	8	0.6	0.672	0.566	0.428	-0.475

Model Descriptions for likelihoods calculated

This document is a draft for review purposes only and does not constitute Agency policy.

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Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2 :	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model
A1

A2
A3

fitted
R

Log(likelihood)

-87 .156698
-47.287416
-55.324218
-59.994980
-109.967018

Param's

7
12

8
5
2

AIC

188.313395
118.574833
126.648436
129.989960
223.934036

Test

1

Test

2

Test

3

Test

4

(Note:

Explanation of Tests

Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1

Test 2
Test 3
Test 4

125.359
79.7386
16.0736
9.34152

10
5
4
3

<.0001

<.0001
0.002922
0.02508

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is less than .1. You may want to consider a
different variance model

The p-value for Test 4 is less than .1. You may want to try a different
model

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD = 0.420475

BMDL = 0.00850422

This document is a draft for review purposes only and does not constitute Agency policy.

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E.3.47.5. Figure for Additional Model Presented: Power, Unrestricted

Power Model with 0.95 Confidence Level

dose

20:03 02/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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E.3.48. Van Birgelen et al., 1995a: Hepatic Retinol Palmitate
E.3.48.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

r p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

exponential (M2)

4

<0.0001

467.446

error

error



exponential (M3)

4

<0.0001

467.446

error

error

power hit bound (d = 1)

exponential (M4)

3

<0.0001

454.087

error

error



exponential (M5)

3

<0.0001

454.087

error

error

power hit bound (d = 1)

Hill

3

<0.0001

563.579

error

error



linear b

4

<0.0001

488.446

1.420E+03

9.889E+02



polynomial, 5-
degree

0

N/A

573.977

error

error



power

4

<0.0001

488.446

1.420E+03

9.889E+02

power bound hit (power =1)

Hill, unrestricted

3

<0.0001

522.322

2.418E-12

2.418E-12

unrestricted (n = 0.452)

power,
unrestricted0

3

0.348

408.062

3.765E-02

1.208E-05

unrestricted (power = 0.054)

a Non-constant variance model selected (p = <0.0001)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.3.48.2. Output for Selected Model: Linear

Van Birgelen et al., 1995a: Hepatic Retinol Palmitate

Polynomial Model. (Version: 2.13; Date: 04/08/2008)

Input Data File: C:\1\66_VanB_l995a_HepRetPalm_Linear_l.(d)

Gnuplot Plotting File: C:\l\66_VanB_1995a_HepRetPalm_Linear_l.plt

_Tue Feb 16~20:03:l6 2010

Tbl3, hepatic retinol palmitate

The form of the response function is:

Y[dose] = beta_0 + beta_l*dose + beta_2*dose/N2 + ...

Dependent variable = Mean
Independent variable = Dose

Signs of the polynomial coefficients are not restricted

This document is a draft for review purposes only and does not constitute Agency policy.

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The variance is to be modeled as Var(i)

exp(lalpha + log(mean(i))

rho)

Total number of dose groups = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
lalpha =	9.57332

rho =	0

beta_0 =	177 . 506

beta 1 = -0.204775

Asymptotic Correlation Matrix of Parameter	Estimates

lalpha rho beta 0	beta 1

lalpha 1 -0.95 -0.017	0.022

rho -0.95 1 0.00019	-0.0048

beta_0 -0.017 0.00019 1	-1

beta_l 0.022 -0.0048 -1	1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
lalpha
rho
beta_0
beta 1

Estimate
-0.723216
2 .26615
150.535
-0.143931

Std. Err.

0.638291
0.140196
31.5457
0.0308317

Lower Conf. Limit

-1.97424
1.99137
88.7064
-0.20436

Upper Conf. Limit
0.527811
2 . 54093
212.363
-0.0835018

Table of Data and Estimated Values of Interest

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0
14
26
47
320
1024

472

94
107
74
22
3

151

149
147
144
104
3.15

272

67 . 9
76.4
39.6
22 . 6
2 . 83

204
201
199
194
135
2 . 56

4 .45

-0.766
-0.567
-1. 02
-1.73
-0.166

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

This document is a draft for review purposes only and does not constitute Agency policy.

E-504 DRAFT—DO NOT CITE OR QUOTE


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Model R:	Yi = Mu + e(i

Var{e(i)) = Sigma^2

Likelihoods of Interest

Model	Log(likelihood) # Param's	AIC

A1 -250.554817	7	515.109634

A2 -196.755746	12	417.511491

A3 -197.383174	8	410.766347

fitted -240.223107	4	488.446215

R -276.789644	2	557.579287

Explanation of Tests

Test 1:

Test

2

Test

3

Test

4

Do responses and/or variances differ among Dose levels?
(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	160.068	10	<.0001

Test 2	107.598	5	<.0001

Test 3	1.25486	4	0.869

Test 4	85.6799	4	<.0001

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is less than .1. You may want to try a different
model

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	1419.81

BMDL =	988.945

This document is a draft for review purposes only and does not constitute Agency policy.

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E.3.48.3. Figure for Selected Model: Linear

Linear Model with 0.95 Confidence Level

dose

20:03 02/16 2010

E.3.48.4. Output for Additional Model Presented: Power, Unrestricted
Van Birgelen et al., 1995a: Hepatic Retinol Palmitate

Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\1\66_VanB_l995a_HepRetPalm_Pwr_U_l.(d)

Gnuplot Plotting File: C:\l\66_VanB_1995a_HepRetPalm_Pwr_U_l.plt

Tue Feb 16 20:03:50 2010

Tbl3, hepatic retinol palmitate

The form of the response function is:
Y[dose] = control + slope * doseApower

Dependent variable = Mean
Independent variable = Dose
The power is not restricted

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-506 DRAFT—DO NOT CITE OR QUOTE


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Total number of dose groups = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

lalpha
rho
control
slope
power

9.57332

0

472
-315.054
0.0586881

Asymptotic Correlation Matrix of Parameter Estimates

lalpha
rho
control
slope
power

lalpha
1

-0. 95
0.29
-0.31
-0.3

rho

-0. 95
1

-0.4

0.39
0.29

control
0.29
-0.4

1

-0. 98
-0. 82

slope

-0.31
0.39
-0. 98
1

0. 91

power
-0.3

0.29
-0. 82
0. 91
1

Parameter Estimates

Variable
lalpha
rho
control
slope
power

Estimate

0.0734958
1.80632
465.497
-318.06
0. 0540573

Std. Err.

0. 849559
0.194602
86.914
82.4127
0.0117709

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

-1.59161
1.42491
295.149
-479.586
0.0309869

1.7386
2 .18774
635.845
-156.534
0. 0771278

Table of Data and Estimated Values of Interest

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0
14
26
47
320
1024

472

94
107
74
22
3

465

98 . 7
86.2
73.8
31.1
2 .86

272

67 . 9
76.4
39.6
22 . 6
2 . 83

266
65. 6
58 .1
50.5
23.1
2 . 68

0. 069
-0.201
1. 01
0.0086
-1.11
0.145

Model Descriptions for likelihoods calculated

Model A1:	Yij

Var{e(ij ) }

Model A2:	Yij

Var{e(ij ) }

Mu(i) + e(ij ;
Sigma/N2

Mu(i) + e(ij ;

Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that

This document is a draft for review purposes only and does not constitute Agency policy.

E-507 DRAFT—DO NOT CITE OR QUOTE


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were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model	Log(likelihood) # Param's	AIC

A1 -250.554817	7	515.109634

A2 -196.755746	12	417.511491

A3 -197.383174	8	410.766347

fitted -199.031154	5	408.062307

R -276.789644	2	557.579287

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Test

2

Test

3

Test

4

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	160.068	10	<.0001

Test 2	107.598	5	<.0001

Test 3	1.25486	4	0.869

Test 4	3.29596	3	0.3482

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adeguately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD = 0.0376489

BMDL = 1.207 69e-005

This document is a draft for review purposes only and does not constitute Agency policy.

E-508 DRAFT—DO NOT CITE OR QUOTE


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E.3.48.5. Figure for Additional Model Presented: Power, Unrestricted

Power Model with 0.95 Confidence Level

dose

20:03 02/16 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-509 DRAFT—DO NOT CITE OR QUOTE


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E.3.49. White et al., 1986: CH50

E.3.49.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

exponential (M2)

5

0.001

391.472

4.480E+02

2.844E+02



exponential (M3)

5

0.001

391.472

4.480E+02

2.844E+02

power hit bound (d = 1)

exponential (M4)

4

0.001

392.128

3.126E+02

1.140E+02



exponential (M5)

4

0.001

392.128

3.126E+02

1.140E+02

power hit bound (d = 1)

Hillb

4

0.001

391.223

2.042E+02

3.585E+01

n lower bound hit (n = 1)

linear

5

<0.0001

396.430

8.065E+02

5.899E+02



polynomial, 6-
degree

3

<0.0001

643.059

9.600E+02

error



power

5

<0.0001

396.430

8.065E+02

5.899E+02

power bound hit (power =1)

Hill, unrestricted0

3

0.058

381.943

9.677E-01

1.900E-01

unrestricted (n = 0.211)

power,
unrestricted

4

0.131

379.574

7.186E-01

1.157E-02

unrestricted (power = 0.188)

a Non-constant variance model selected (p = 0.0871)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

E.3.49.2. Output for Selected Model: Hill

White etal., 1986: CH50

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\1\7l_White_l986_CH50_Hill_l.(d)

Gnuplot Plotting File: C:\l\71_White_1986_CH50_Hill_l.plt

_Tue Feb 16 20:06:45 2010

[insert study notes]

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = Mean
Independent variable = Dose

Power parameter restricted to be greater than 1

This document is a draft for review purposes only and does not constitute Agency policy.

E-510 DRAFT—DO NOT CITE OR QUOTE


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The variance is to be modeled as Var(i) = exp(lalpha + rho * ln(mean(i)))
Total number of dose groups = 7

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

lalpha
rho

intercept

5.60999

0
91
-74

0.0969998
10

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -n

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

lalpha
rho

intercept

lalpha
1

-0. 99
0.19
0.13
-0.22

rho

-0. 99
1

-0.2

-0.14
0.23

intercept
0.19
-0.2

1

0.33
-0.7

v

0.13
-0.14
0.33
1

-0.86

k

-0.22
0.23
-0.7

-0.86
1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
lalpha
rho

intercept

k

Estimate

4 . 34761
0.381496
71.6585
-62.7464
1

441.016

Std. Err.
1.59601
0. 413764
5.38454
14 . 9646
NA

460.151

Lower Conf. Limit
1.21948
-0.429467
61.105
-92.0765

-460.864

Upper Conf. Limit
7 .47574
1.19246
82 . 212
-33.4163

1342.9

NA - Indicates that this parameter has hit a bound
implied by some ineguality constraint and thus
has no standard error.

Table of Data and Estimated Values of Interest

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

CO

o

91

71.

. 7

14 .1

19.

. 9

2 .75

10 8

54

70.

. 3

8.49

19.

. 8

-2 . 33

50 8

63

65.

. 3

11. 3

19.

. 5

-0.329

100 8

56

60.

. 1

25.5

19.

. 2

-0.598

500 8

41

38 .

. 3

17

17 .

, 6

0.43

1000 8

32

28 .

. 1

17

16.

, 6

0. 661

2000 8

17

20.

. 2

17

15.

. 6

-0.589

This document is a draft for review purposes only and does not constitute Agency policy.

E-511 DRAFT—DO NOT CITE OR QUOTE


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Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2 :	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model
A1

A2
A3

fitted
R

Log(likelihood)
-181.340979
-175.820265
-181. 238690
-190.611743
-212 . 367055

14

9
5
2

AIC

378 . 681959
379.640529
380.477380
391.223485
428.734109

Explanation of Tests

Test

1

Test

2

Test

3

Test

4

(Note:

Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1

Test 2
Test 3
Test 4

73.0936
11. 0414
10.8369
18 . 7461

12

<.0001
0.0871
0.05471
0.0008815

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is less than .1. You may want to consider a
different variance model

The p-value for Test 4 is less than .1. You may want to try a different
model

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	2 04.214

This document is a draft for review purposes only and does not constitute Agency policy.

E-512 DRAFT—DO NOT CITE OR QUOTE


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E'.MDL =

35.8504

E.3.49.3. Figure for Selected Model: Hill

Hill Model with 0.95 Confidence Level

dose

20:06 02/16 2010

E.3.49.4. Output for Additional Model Presented: Hill, Unrestricted
White etal., 1986: CH50

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\1\7l_White_l986_CH50_Hill_U_l.(d)

Gnuplot Plotting File: C:\l\71_White_1986_CH50_Hill_U_l.plt

Tue Feb 16 20:06:46 2010

[insert study notes]

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = Mean

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-513 DRAFT—DO NOT CITE OR QUOTE


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Independent variable = Dose

Power parameter is not restricted

The variance is to be modeled as Var(i)

exp(lalpha + rho * ln(mean(i)

Total number of dose groups = 7

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

lalpha
rho

intercept

5.60999

0
91
-74

0.0969998
10

Asymptotic Correlation Matrix of Parameter Estimates

lalpha
rho

intercept

lalpha
1
-1

0.17
0.22
-0.42
-0.022

rho
-1

1

-0.17
-0.22
0.42
0. 019

intercept

0.17
-0.17
1

0.16
-0.58
0. 0069

v

0.22
-0.22
0.16
1

-0.048
-0. 91

n

-0.42
0.42
-0.58
-0.048
1

-0.35

k

-0.022
0. 019
0.0069
-0. 91
-0.35
1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
lalpha
rho

intercept

Estimate

6. 62767
-0.266376
89.579
-458.615
0.210614
9. 00638e + 006

Std. Err.
2 .14235
0.555274
5.61106
402.837
0.0503369
. 61231e + 007

Lower Conf. Limit
2 .42875
-1.35469
78 . 5815
-1248.16
0.111956
-8 .13933e + 007

Upper Conf. Limit

10.8266
0. 821941
100.576
330.93
0.309273
9.94 061e + 007

Table of Data and Estimated Values of Interest

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0
10
50
100
500
1000
2000

91

54
63
56
41
32
17

89.6

65. 4
56.3
51. 5
37
30
22

9

9

14 .1
8.49
11. 3
25.5
17
17
17

15.1

15.	8
16.1
16.3

16.	9

17	. 4

18	.1

0.266
-2 . 04
1.18
0 .777
0.516
0.191
-0.927

Model Descriptions for likelihoods calculated

This document is a draft for review purposes only and does not constitute Agency policy.

E-514 DRAFT—DO NOT CITE OR QUOTE


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Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2 :	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(1)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model
A1

A2
A3

fitted
R

Log(likelihood)
-181.340979
-175.820265
-181. 238690
-184.971691
-212 . 367055

Param's

14
9

AIC

378 . 681959
379.640529
380.477380
. 943382
.734109

381.
428 .

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

Test 3: Are variances adequately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1

Test 2
Test 3
Test 4

73.0936
11. 0414
10.8369
7.466

12

<.0001
0.0871
0.05471
0.05844

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is less than .1. You may want to consider a
different variance model

The p-value for Test 4 is less than .1. You may want to try a different
model

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	0.967 68 9

BMDL =	0.18 9992

This document is a draft for review purposes only and does not constitute Agency policy.

E-515 DRAFT—DO NOT CITE OR QUOTE


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l E.3.49.5. Figure for Additional Model Presented: Hill, Unrestricted

Hill Model with 0.95 Confidence Level

dose

2	20:06 02/16 2010

3

4

5

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

E-516 DRAFT—DO NOT CITE OR QUOTE


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1	E.4. REFERENCES

2	Amin, S; Moore, RW; Peterson, RE; et al. (2000) Gestational and lactational exposure to TCDD or coplanar PCBs

3	alters adult expression of saccharin preference behavior in female rats. Neurotoxicol Teratol 22(5):675-682.

4	Bell, DR; Clode, S; Fan, MQ; et al. (2007a) Toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin in the developing male

5	Wistar(Han) rat. II: Chronic dosing causes developmental delay. Toxicol Sci 99(l):224-233.

6	Bell, DR; Clode, S; Fan, MQ; et al. (2007b) Relationships between tissue levels of 2,3,7,8-tetrachlorodibenzo-

7	p-dioxin (TCDD), mRNAs, and toxicity in the developing male Wistar (Han) rat. Toxicol Sci 99(2):591-604.

8	Cantoni, L; Salmona, M; Rizzardini, M. (1981) Porphyrogenic effect of chronic treatment with

9	2,3,7,8-tetrachlorodibenzo-p-dioxin in female rates. Dose-effect relationship following urinary excretion of

10	porphyrins. Toxicol Appl Pharmacol 57:156-157.

11	Crofton, KM; Craft, ES; Hedge, JM; et al. (2005) Thyroid-hormone-disrupting chemicals: evidence for dose-

12	dependent additivity or synergism. Environ Health Perspect 113(11): 1549-1554.

13	DeCaprio, AP; McMartin, DN; O'Keefe, PE; et al. (1986) Subchronic oral toxicity of 2,3,7,8-tetrachlorodibenzo-

14	p-dioxin in the guinea pig: comparisons with a PCB-containing transformer fluid pyrolysate. Fund Appl Toxicol

15	6:454-463.

16	Franc, MA; Pohjanvirta, R; Tuomisto, J; et al. (2001) Persistent, low-dose 2,3,7,8-tetrachlorodibenzo-p-dioxin

17	exposure: effect on aryl hydrocarbon receptor expression in a dioxin-resistance model. Toxicol Appl Pharmacol

18	175:43-53.

19	Hojo, R; Stern, S; Zareba, G; et al. (2002) Sexually dimorphic behavioral responses to prenatal dioxin exposure.

20	Environ Health Perspect 110(3):247-254.

21	Kattainen, H; Tuukanan, J; Simanainen, U; et al. (2001) In utero/lactational 2,3,7,8-tetrachlorodibenzo-p-dioxin

22	exposure impairs molar tooth development in rats. Toxicol Appl Pharmacol 17:216-224.

23	Keller, JM; Huet-Hudson, YM; Leamy, LJ. (2007) Qualitative effects of dioxin on molars vary among inbred mouse

24	strains. Arch Oral Biol 52:450-454.

25	Keller, JM; Zelditch, ML; Huet, YM; et al. (2008a) Genetic differences in sensitivity to alterations of mandible

26	structure caused by the teratogen 2.3.7.8-tctrachlorodibenzo-/?-dio.\in. Toxicol Pathol 36:1006-1013.

27	Keller, JM; Huet-Hudson, Y; Leamy, LJ. (2008b) Effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin on molar

28	development among non-resistant inbred strains of mice: a geometric morphometric analysis. Growth Devel Aging

29	71:3-16.

30	Kociba, RJ; Keyes, DG; Beyer, JE; et al. (1978) Results of a two-year chronic toxicity and oncogenicity study of

31	2,3,7,8-tetrachlorodibenzo-p-dioxin in rats. Toxicol Appl Pharmacol 46(2):279-303.

32	Latchoumycandane, C; Mathur, PP. (2002) Effects of vitamin E on reactive oxygen species-mediated

33	2,3,7,8-tetrachlorodi-benzo-p-dioxin toxicity in rat testis. J Appl Toxicol 22(5):345-351.

34	Li, B; Liu, H-Y; Dai, L-J; et al. (2006) The early embryo loss caused by 2,3,7,8-tetrachlorodibenzo-p-dioxin may be

35	related to the accumulation of this compound in the uterus. Reprod Toxicol 21:301-306.

36	Markowski, VP; Zareba, G; Stern, S; et al. (2001) Altered operant responding for motor reinforcement and the

37	determination of benchmark doses following perinatal exposure to low-level 2,3,7,8-tetrachlorodibenzo-p-dioxin.

38	Environ Health Perspect 109(6):621-627.

This document is a draft for review purposes only and does not constitute Agency policy.

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1	Miettinen, HM; Sorvari, R; Alaluusua, S; et al. (2006) The Effect of perinatal TCDD exposure on caries

2	susceptibility in rats. Toxicol Sci 91(2):568-575.

3	NTP (National Toxicology Program). (1982) NTP Technical Report on carcinogenesis bioassay of

4	2,3,7,8-tetrachlorodibenzo-p-dioxin in Osborne-Mendel rats and B6C3F1 mice (gavage study). Public Health

5	Service, U.S. Department of Health and Human Services; NTP TR 209. Available from the National Institute of

6	Environmental Health Sciences, Research Triangle Park, NC.

7	NTP (National Toxicology Program). (2006) NTP technical report on the toxicology and carcinogenesis studies of

8	2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) (CAS No. 1746-01-6) in female Harlan Sprague-Dawley rats (Gavage

9	Studies). Natl Toxicol ProgramTech Rep 521. Public Health Service, National Institute of Health, U.S. Department

10	of Health and Human Services, Research Triangle Park, NC.

11	Ohsako, S; Miyabara, Y; Nishimura, N; et al. (2001) Maternal exposure to a low dose of

12	2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) suppressed the development of reproductive organs of male rats: dose-

13	dependent increase of mRNA levels of 5a-reductase type 2 in contrast to decrease of androgren receptor in the

14	pubertal ventral prostate. Toxicol Sci 60:132-143.

15	Shi, Z; Valdez, KE; Ying, AY; et al. (2007) Ovarian endocrine disruption underlies premature reproduction

16	senescence following environmentally relevant chronic exposure to aryl hydrocarbon receptor agonist

17	2,3,7,8-tetrachlorodibenzo-p-dioxin. Biol Reprod 30(4):293-342.

18	Smialowicz, RJ; DeVito, MJ; Williams, WC; et al. (2008) Relative potency based on hepatic enzyme induction

19	predicts immunosuppressive effects of a mixture of PCDDS/PCDFS and PCBS. Toxicol Appl Pharmacol

20	227:477-484.

21	Toth, KJ; Sugar, S; Somfai-Relle, S; et al. (1978) Carcinogenic bioassay of the herbicide 2,4,5-trichlorphenoxy

22	ethanol (TCPE) with Swiss mice. Prog BiochemPharmacol 14:82-93.

23	Toth, L; Somfai-Relle, S; Sugar, J; et al. (1979) Carcinogenicity testing of herbicide 2,4,5-trichlorophenoxyethanol

24	containing dioxin and of pure dioxin in Swiss mice. Nature 278:548-549.

25	Van Birgelen, AP; Van der Kolk, J; Fase, KM; et al. (1995) Subchronic dose-response study of

26	2,3,7,8-tetrachlorodibenzo-p-dioxin in female Sprague-Dawley rats. Toxicol Appl Pharmacol 132:1-13.

27	White, KL, Jr; Lysy, HH; McCay, JA; et al. (1986) Modulation of serum complement levels following exposure to

28	polychlorinated dibenzo-p-dioxins. Toxicol Appl Pharmacol 84:209-219.

This document is a draft for review purposes only and does not constitute Agency policy.

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DRAFT

DO NOT CITE OR QUOTE

May 2010
External Review Draft

APPENDIX F
Cancer Benchmark Dose Modeling

NOTICE

THIS DOCUMENT IS AN EXTERNAL REVIEW DRAFT. It has not been formally released
by the U.S. Environmental Protection Agency and should not at this stage be construed to
represent Agency policy. It is being circulated for comment on its technical accuracy and policy
implications.

National Center for Environmental Assessment
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, OH


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CONTENTS—APPENDIX F: Cancer Benchmark Dose Modeling

APPENDIX F. CANCER BENCHMARK DOSE MODELING	F-l

F.l. BLOOD BMDS RESULTS	F-l

F.l.l. Kociba et al., 1978: Stratified squamous cell carcinoma of hard

palate or nasal turbinates	F-l

F.l. 1.1. Summary Table of BMDS Modeling Results	F-l

F.l. 1.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-l

F.l.1.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-3

F.1.2. Kociba et al., 1978: Stratified squamous cell carcinoma of tongue	F-4

F.l.2.1. Summary Table of BMDS Modeling Results	F-4

F. 1.2.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-4

F. 1.2.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-6

F.1.3. Kociba et al., 1978: Adenoma of adrenal cortex	F-7

F.1.3.1. Summary Table of BMDS Modeling Results	F-7

F. 1.3.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-7

F.1.3.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-9

F.1.4. Kociba et al., 1978: Hepatocellular adenoma(s) or carcinoma(s)	F-10

F.l.4.1. Summary Table of BMDS Modeling Results	F-10

F. 1.4.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-10

F. 1.4.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-12

F.1.5. Kociba et al., 1978: Stratified squamous cell carcinoma of hard

palate or nasal turbinates	F-l3

F.l.5.1. Summary Table of BMDS Modeling Results	F-13

F.1.5.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-13

F.1.5.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-15

F.1.6. Kociba et al., 1978: Keratinizing squamous cell carcinoma of lung	F-16

F.l.6.1. Summary Table of BMDS Modeling Results	F-16

F. 1.6.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-16

F. 1.6.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-18

F.1.7. National Toxicology Program, 1982: Subcutaneous Tissue:

Fibrosarcoma	F-19

F.l.7.1. Summary Table of BMDS Modeling Results	F-19

F. 1.7.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-19

F. 1.7.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-21

F.1.8. National Toxicology Program, 1982: Liver: Neoplastic Nodule or

Hepatocellular Carcinoma	F-22

F.l.8.1. Summary Table of BMDS Modeling Results	F-22

F.1.8.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-22

F.1.8.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-24

F.1.9. National Toxicology Program, 1982: Adrenal: Cortical Adenoma, or

Carcinoma or Adenoma, NOS	F-25

F.l.9.1. Summary Table of BMDS Modeling Results	F-25

F. 1.9.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-25

F. 1.9.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-27

This document is a draft for review purposes only and does not constitute Agency policy.

F-ii	DRAFT—DO NOT CITE OR QUOTE


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CONTENTS (continued)

F.1.10. National Toxicology Program, 1982: Thyroid: Follicular-Cell

Adenoma	F-28

F. 1.10.1. Summary Table ofBMDS Modeling Results	F-28

F.1.10.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-28

F.1.10.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-30

F. 1.11. National Toxicology Program, 1982: Liver: Neoplastic Nodule or

Hepatocellular Carcinoma	F-31

F. 1.11.1. Summary Table ofBMDS Modeling Results	F-31

F. 1.11.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-31

F.1.11.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-33

F.1.12. National Toxicology Program, 1982: Thyroid: Follicular-Cell

Adenoma or Carcinoma	F-34

F. 1.12.1. Summary Table ofBMDS Modeling Results	F-34

F.1.12.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-34

F.1.12.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-36

F.1.13. National Toxicology Program, 1982: Adrenal cortex: Adenoma	F-37

F.1.13.1. Summary Table ofBMDS Modeling Results	F-37

F.1.13.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-37

F.1.13.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-39

F.1.14. National Toxicology Program, 1982: Subcutaneous Tissue:

Fibrosarcoma	F-40

F. 1.14.1. Summary Table ofBMDS Modeling Results	F-40

F.1.14.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-40

F.1.14.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-42

F.1.15. National Toxicology Program, 1982: Hematopoietio System:

Lymphoma or Leukemia	F-43

F.1.15.1. Summary Table ofBMDS Modeling Results	F-43

F.1.15.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-43

F.1.15.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-45

F.1.16. National Toxicology Program, 1982: Liver: Hepatooellular

Adenoma or Carcinoma	F-46

F. 1.16.1. Summary Table ofBMDS Modeling Results	F-46

F.1.16.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-46

F.1.16.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-48

F.1.17. National Toxicology Program, 1982: Subcutaneous Tissue:

Fibrosarcoma	F-49

F. 1.17.1. Summary Table ofBMDS Modeling Results	F-49

F.1.17.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-49

F.1.17.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-51

F.1.18. National Toxicology Program, 1982: Lung: Alveolar/Bronchiolar

Adenoma or Carcinoma	F-52

F.1.18.1. Summary Table ofBMDS Modeling Results	F-52

F.1.18.2. Output for Selected Model: Multistage Cancer, 2-Degree	F-52

This document is a draft for review purposes only and does not constitute Agency policy.

F-iii	DRAFT—DO NOT CITE OR QUOTE


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CONTENTS (continued)

F. 1.18.3. Figure for Selected Model: Multistage Cancer, 2-Degree	F-54

F.1.19. National Toxicology Program, 1982: Liver: Hepatocellular Adenoma

or Carcinoma	F-55

F. 1.19.1. Summary Table ofBMDS Modeling Results	F-55

F.1.19.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-55

F.1.19.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-57

F.1.20. National Toxicology Program, 2006: Liver: Cholangiocarcinoma	F-58

F. 1.20.1. Summary Table ofBMDS Modeling Results	F-58

F.1.20.2. Output for Selected Model: Multistage Cancer, 3-Degree	F-58

F. 1.20.3. Figure for Selected Model: Multistage Cancer, 3-Degree	F-60

F. 1.21. National Toxicology Program, 2006: Liver: Hepatocellular adenoma	F-61

F. 1.21.1. Summary Table ofBMDS Modeling Results	F-61

F. 1.21.2. Output For Selected Model: Multistage Cancer, 3-Degree	F-61

F.1.21.3. Figure For Selected Model: Multistage Cancer, 3-Degree	F-63

F.1.22. National Toxicology Program, 2006: Oral mucosa: squamous cell

carcinoma	F-64

F. 1.22.1. Summary Table ofBMDS Modeling Results	F-64

F. 1.22.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-64

F. 1.22.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-66

F.1.23. National Toxicology Program, 2006: Pancreas: adenoma or

carcinoma	F-67

F.1.23.1. Summary Table ofBMDS Modeling Results	F-67

F. 1.23.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-67

F.1.23.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-69

F.1.24. National Toxicology Program, 2006: Lung: Cystic keratinizing

epithelioma	F-70

F. 1.24.1. Summary Table ofBMDS Modeling Results	F-70

F. 1.24.2. Output for Selected Model: Multistage Cancer, 2-Degree	F-70

F. 1.24.3. Figure for Selected Model: Multistage Cancer, 2-Degree	F-72

F.1.25. Tothetal., 1979: Liver: Tumors	F-73

F. 1.25.1. Summary Table ofBMDS Modeling Results	F-73

F. 1.25.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-73

F.1.25.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-75

F.1.26. DellaPorta et al., 1987: Table 4, B6C3 mice, male, hepatocellular

carcinoma	F-76

F. 1.26.1. Summary Table ofBMDS Modeling Results	F-76

F. 1.26.2. Output for Selected Model: Multistage Cancer, 2-Degree	F-76

F. 1.26.3. Figure for Selected Model: Multistage Cancer, 2-Degree	F-78

F.1.27. DellaPorta et al., 1987: Table 4, B6C3 mice, female, hepatocellular

adenoma	F-79

F. 1.27.1. Summary Table ofBMDS Modeling Results	F-79

F. 1.27.2. Output for Selected Model: Multistage Cancer, 2-Degree	F-79

F. 1.27.3. Figure for Selected Model: Multistage Cancer, 2-Degree	F-81

This document is a draft for review purposes only and does not constitute Agency policy.

F-iv	DRAFT—DO NOT CITE OR QUOTE


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CONTENTS (continued)

F.1.28. DellaPorta et al., 1987: Table 4, B6C3 mice, female, hepatocellular

carcinoma	F-82

F. 1.28.1. Summary Table ofBMDS Modeling Results	F-82

F.1.28.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-82

F.1.28.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-84

F.2. ADMINISTERED DOSE BMDS RESULTS	1-85

F.2.1. Kociba et al., 1978: Stratified squamous cell carcinoma of hard

palate or nasal turbinates	F-85

F.2.1.1. Summary Table ofBMDS Modeling Results	F-85

F.2.1.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-85

F.2.1.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-87

F.2.2. Kociba et al., 1978: Stratified squamous cell carcinoma of tongue	F-88

F.2.2.1. Summary Table ofBMDS Modeling Results	F-88

F.2.2.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-88

F.2.2.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-90

F.2.3. Kociba et al., 1978: Adenoma of adrenal cortex	F-91

F.2.3.1. Summary Table ofBMDS Modeling Results	F-91

F.2.3.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-91

F.2.3.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-93

F.2.4. Kociba et al., 1978: Hepatocellular adenoma(s) or carcinoma(s)	F-94

F.2.4.1. Summary Table ofBMDS Modeling Results	F-94

F.2.4.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-94

F.2.4.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-96

F.2.5. Kociba et al., 1978: Stratified squamous cell carcinoma of hard

palate or nasal turbinates	F-97

F.2.5.1. Summary Table ofBMDS Modeling Results	F-97

F.2.5.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-97

F.2.5.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-99

F.2.6. Kociba et al., 1978: Keratinizing squamous cell carcinoma of lung	F-100

F.2.6.1. Summary Table ofBMDS Modeling Results	F-100

F.2.6.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-100

F.2.6.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-102

F.2.7. National Toxicology Program, 1982: Subcutaneous Tissue:

Fibrosarcoma	F-103

F.2.7.1. Summary Table ofBMDS Modeling Results	F-103

F.2.7.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-103

F.2.7.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-105

F.2.8. National Toxicology Program, 1982: Liver: Neoplastic Nodule or

Hepatocellular Carcinoma	F-106

F.2.8.1. Summary Table ofBMDS Modeling Results	F-106

F.2.8.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-106

F.2.8.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-108

This document is a draft for review purposes only and does not constitute Agency policy.

F-v	DRAFT—DO NOT CITE OR QUOTE


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CONTENTS (continued)

F.2.9. National Toxicology Program, 1982: Adrenal: Cortical Adenoma, or

Carcinoma or Adenoma, NOS	F-109

F.2.9.1. Summary Table ofBMDS Modeling Results	F-109

F.2.9.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-109

F.2.9.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-l 11

F.2.10. National Toxicology Program, 1982: Thyroid: Follicular-Cell

Adenoma	F-l 12

F.2.10.1. Summary Table ofBMDS Modeling Results	F-l 12

F.2.10.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-l 12

F.2.10.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-l 14

F.2.11. National Toxicology Program, 1982: Liver: Neoplastic Nodule or

Hepatocellular Carcinoma	F-l 15

F.2.11.1. Summary Table ofBMDS Modeling Results	F-l 15

F.2.11.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-l 15

F.2.11.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-l 17

F.2.12. National Toxicology Program, 1982: Thyroid: Follicular-Cell

Adenoma or Carcinoma	F-l 18

F.2.12.1. Summary Table ofBMDS Modeling Results	F-118

F.2.12.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-118

F.2.12.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-120

F.2.13. National Toxicology Program, 1982: Adrenal cortex: Adenoma	F-121

F.2.13.1. Summary Table ofBMDS Modeling Results	F-121

F.2.13.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-121

F.2.13.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-123

F.2.14. National Toxicology Program, 1982: Subcutaneous Tissue:

Fibrosarcoma	F-124

F.2.14.1. Summary Table ofBMDS Modeling Results	F-124

F.2.14.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-124

F.2.14.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-126

F.2.15. National Toxicology Program, 1982: Hematopoietio System:

Lymphoma or Leukemia	F-127

F.2.15.1. Summary Table ofBMDS Modeling Results	F-127

F.2.15.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-127

F.2.15.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-129

F.2.16. National Toxicology Program, 1982: Liver: Hepatooellular

Adenoma or Carcinoma	F-130

F.2.16.1. Summary Table ofBMDS Modeling Results	F-130

F.2.16.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-130

F.2.16.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-132

F.2.17. National Toxicology Program, 1982: Subcutaneous Tissue:

Fibrosarcoma	F-133

F.2.17.1. Summary Table ofBMDS Modeling Results	F-133

F.2.17.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-133

This document is a draft for review purposes only and does not constitute Agency policy.

F-vi	DRAFT—DO NOT CITE OR QUOTE


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CONTENTS (continued)

F.2.17.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-135

F.2.18. National Toxicology Program, 1982: Lung: Alveolar/Bronchiolar

Adenoma or Carcinoma	F-136

F.2.18.1. Summary Table ofBMDS Modeling Results	F-136

F.2.18.2. Output for Selected Model: Multistage Cancer, 2-Degree	F-136

F.2.18.3. Figure for Selected Model: Multistage Cancer, 2-Degree	F-138

F.2.19. National Toxicology Program, 1982: Liver: Hepatocellular Adenoma

or Carcinoma	F-139

F.2.19.1. Summary Table ofBMDS Modeling Results	F-139

F.2.19.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-139

F.2.19.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-141

F.2.20. National Toxicology Program, 2006: Liver: Cholangiocarcinoma	F-142

F.2.20.1. Summary Table ofBMDS Modeling Results	F-142

F.2.20.2. Output for Selected Model: Multistage Cancer, 3-Degree	F-142

F.2.20.3. Figure for Selected Model: Multistage Cancer, 3-Degree	F-144

F.2.21. National Toxicology Program, 2006: Liver: Hepatocellular adenoma	F-145

F.2.21.1. Summary Table ofBMDS Modeling Results	F-145

F.2.21.2. Output for Selected Model: Multistage Cancer, 3-Degree	F-145

F.2.21.3. Figure for Selected Model: Multistage Cancer, 3-Degree	F-147

F.2.22. National Toxicology Program, 2006: Oral mucosa: squamous cell

carcinoma	F-148

F.2.22.1. Summary Table ofBMDS Modeling Results	F-148

F.2.22.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-148

F.2.22.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-150

F.2.23. National Toxicology Program, 2006: Pancreas: adenoma or

carcinoma	F-151

F.2.23.1. Summary Table ofBMDS Modeling Results	F-151

F.2.23.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-151

F.2.23.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-153

F.2.24. National Toxicology Program, 2006: Lung: Cystic keratinizing

epithelioma	F-154

F.2.24.1. Summary Table ofBMDS Modeling Results	F-154

F.2.24.2. Output for Selected Model: Multistage Cancer, 2-Degree	F-154

F.2.24.3. Figure for Selected Model: Multistage Cancer, 2-Degree	F-156

F.2.25. Tothetal., 1979: Liver: Tumors	F-157

F.2.25.1. Summary Table ofBMDS Modeling Results	F-157

F.2.25.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-157

F.2.25.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-159

F.2.26. Delia Porta et al., 1987: Table 4, B6C3 mice, male, hepatocellular

carcinoma	F-160

F.2.26.1. Summary Table ofBMDS Modeling Results	F-160

F.2.26.2. Output for Selected Model: Multistage Cancer, 2-Degree	F-160

F.2.26.3. Figure for Selected Model: Multistage Cancer, 2-Degree	F-162

This document is a draft for review purposes only and does not constitute Agency policy.

F-vii	DRAFT—DO NOT CITE OR QUOTE


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CONTENTS (continued)

F.2.27. Delia Porta et al., 1987: Table 4, B6C3 mice, female, hepatocellular

adenoma	F-163

F.2.27.1. Summary Table ofBMDS Modeling Results	F-163

F.2.27.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-163

F.2.27.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-165

F.2.28. Delia Porta et al., 1987: Table 4, B6C3 mice, female, hepatocellular

carcinoma	F-166

F.2.28.1. Summary Table ofBMDS Modeling Results	F-166

F.2.28.2. Output for Selected Model: Multistage Cancer, 1-Degree	F-166

F.2.28.3. Figure for Selected Model: Multistage Cancer, 1-Degree	F-168

F.3. REFERENCES	F-169

This document is a draft for review purposes only and does not constitute Agency policy.

F-viii DRAFT—DO NOT CITE OR QUOTE


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APPENDIX F.

CANCER BENCHMARK DOSE MODELING

F.l. BLOOD BMDS RESULTS

F.l.l. Kociba et al., 1978: Stratified squamous cell carcinoma of hard palate or nasal
turbinates

F. 1.1.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

3

0.815

31.564

5.763E+00

2.795E+00



Multistage Cancer,
2-Degree

3

0.985

30.170

1.369E+01

3.416E+00



Multistage Cancer,
3-Degree

3

0.999

29.930

1.917E+01

3.578E+00



a Best-fitting model, BMDS output presented in this appendix

F. 1.1.2. Output for Selected Model: Multistage Cancer, 1 -Degree

Kociba et al., 1978: Stratified squamous cell carcinoma of hard palate or nasal turbinates

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\4\Blood\l mscl IPerc palate nasal.(d)

Gnuplot Plotting File: C:\4\Blood\l mscl IPerc palate nasal.pit

Thu Apr 01 15:56:03 2010

Source - Table 4

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(

-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

This document is a draft for review purposes only and does not constitute Agency policy.

F-l	DRAFT—DO NOT CITE OR QUOTE


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Default Initial Parameter Values
Background =	0

Beta(1) = 0.00226154

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -Background

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Beta(1)

Beta(1)	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0	*	*	*

Beta(1)	0.0017438	*	*	*

Indicates that this value is not calculated.

Analysis of Deviance Table

Model	Log(likelihood)	# Param's	Deviance	Test d.f.	P-value

Full model	-13.9385	4

Fitted model	-14.7819	1	1.68696	3	0.6398

Reduced model	-20.2589	1	12.6409	3	0.005481

AIC:	31.5639

Goodness of Fit

Scaled

Dose Est. Prob. Expected Observed	Size	Residual

0.0000 0.0000 0.000 0.000	85	0.000

1.5617 0.0027 0.136 0.000	50	-0.369

7.1600 0.0124 0.620 0.000	50	-0.793

38.7212 0.0653 3.265 4.000	50	0.421

Chi/N2 = 0.94	d.f. = 3	P-value = 0.8153

Benchmark Dose Computation

Specified effect	=	0.01

Risk Type	=	Extra risk

Confidence level	=	0.95

BMD	=	5.7 6347

BMDL	=	2.7 94 85

BMDU	=	14 . 9396

Taken together, (2.79485, 14.9396) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor =	0.003578

This document is a draft for review purposes only and does not constitute Agency policy.

F-2	DRAFT—DO NOT CITE OR QUOTE


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1 F.l.1.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	14:56 04/01 2010

3

4	Kociba et al., 1978: Stratified squamous cell carcinoma of hard palate or nasal turbinates

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-3	DRAFT—DO NOT CITE OR QUOTE


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F.1.2. Kociba et al., 1978: Stratified squamous cell carcinoma of tongue
F. 1.2.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

Up-
value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degree a

2

0.472

47.933

6.091E+00

2.600E+00



Multistage Cancer,
2-Degree

2

0.472

47.933

6.091E+00

2.600E+00

final B=0

Multistage Cancer,
3-Degree

2

0.472

47.933

6.091E+00

2.600E+00

final B=0

a Best-fitting model, BMDS output presented in this appendix

F. 1.2.2. Output for Selected Model: Multistage Cancer, 1-Degree
Kociba et al., 1978: Stratified squamous cell carcinoma of tongue

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\4\Blood\2_mscl_lPerc_tongue.(d)

Gnuplot Plotting File: C:\4\Blood\2_mscl_lPerc_tongue.plt

Thu Apr 01 15:56:35 2010

Source - Table 4

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background = 0.0092514
Beta (1) = 0.00137224

This document is a draft for review purposes only and does not constitute Agency policy.

F-4	DRAFT—DO NOT CITE OR QUOTE


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Asymptotic Correlation Matrix of Parameter Estimates
Background	Beta(1)

Background	1	-0.58

Beta(1)	-0.58	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0.00510501	*	*	*

Beta (1)	0.00165011	*	*	*

* - Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-21.1523	4

Fitted model -21.9667 2	1.62881 2	0.4429

Reduced model -24.1972 1	6.08976 3	0.1073

AIC:	47.9334

Goodness of Fit

Scaled

Dose Est. Prob. Expected Observed	Size	Residual

0.0000 0.0051 0.434 0.000	85	-0.660

1.5617 0.0077 0.383 1.000	50	1.000

7.1600 0.0168 0.840 1.000	50	0.177

38.7212 0.0667 3.334 3.000	50	-0.189

Chi ^2 = 1.50	d.f. = 2	P-value = 0.4716

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	6.0907

BMDL =	2.6004 9

BMDU =	519124

Taken together, (2.60049, 519124 ) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00384542

This document is a draft for review purposes only and does not constitute Agency policy.

F-5	DRAFT—DO NOT CITE OR QUOTE


-------
1 F. 1.2.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	14:56 04/01 2010

3

4	Kociba et al., 1978: Stratified squamous cell carcinoma of tongue

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-6	DRAFT—DO NOT CITE OR QUOTE


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F.1.3. Kociba et al., 1978: Adenoma of adrenal cortex
F. 1.3.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

xV

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

3

0.779

52.488

3.254E+00

1.852E+00



Multistage Cancer,
2-Degree

3

0.779

52.488

3.254E+00

1.852E+00

final fi=0

Multistage Cancer,
3-Degree

3

0.779

52.488

3.254E+00

1.852E+00

final fi=0

a Best-fitting model, BMDS output presented in this appendix

F. 1.3.2. Output for Selected Model: Multistage Cancer, 1-Degree
Kociba et al., 1978: Adenoma of adrenal cortex

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\4\Blood\3 mscl IPerc adre adenoma.(d)

Gnuplot Plotting File: C:\4\Blood\3 mscl IPerc adre adenoma.pit

Thu Apr 01 15:57:07 2010

Source - Table 5

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background = 0.00493756
Beta(1) = 0.0026639

This document is a draft for review purposes only and does not constitute Agency policy.

F-7	DRAFT—DO NOT CITE OR QUOTE


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65

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -Background

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Beta(1)

Beta(1)	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0	*	*	*

Beta(1)	0.00308883	*	*	*

- Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-24.6514	4

Fitted model -25.2438 1	1.18487 3	0.756£

Reduced model -31.4904 1	13.6781 3	0.00337e

AIC:	52.4876

Goodness of Fit

Scaled

Est. Prob. Expected Observed	Size	Residual

0.0000
1.5617
7.1600
38.7212

0.0000
0.0048
0.0219
0.1127

0. 000
0.241
1.094
5. 636

0. 000
0. 000
2 . 000
5. 000

85

50
50
50

0. 000
-0.492
0. 876
-0.285

Chi ^2

1.09

d.f.

P-value

0.77 93

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	3.25376

BMDL =	1.85162

BMDU =	6.585 95

Taken together, (1.85162, 6.58595) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00540067

This document is a draft for review purposes only and does not constitute Agency policy.

F-8	DRAFT—DO NOT CITE OR QUOTE


-------
1 F. 1.3.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	14:57 04/01 2010

3

4	Kociba et al., 1978: Adenoma of adrenal cortex

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-9	DRAFT—DO NOT CITE OR QUOTE


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F.1.4. Kociba et al., 1978: Hepatocellular adenoma(s) or carcinoma(s)
F.l.4.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

r p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

2

0.245

143.261

7.010E-01

5.013E-01



Multistage Cancer,
2-Degree

2

0.245

143.261

7.010E-01

5.013E-01

final fi=0

Multistage Cancer,
3-Degree

2

0.245

143.261

7.010E-01

5.013E-01

final fi=0

a Best-fitting model, BMDS output presented in this appendix

F.l.4.2. Output for Selected Model: Multistage Cancer, 1-Degree
Kociba et al., 1978: Hepatocellular adenoma(s) or carcinoma(s)

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\4\Blood\4 mscl IPerc liver ad carc.(d)

Gnuplot Plotting File: C:\4\Blood\4 mscl IPerc liver ad carc.pit

Thu Apr 01_15T57:41 2010

Source - Table 1 in Goodman and Sauer 1992

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background = 0.0400263
Beta(1) = 0.0124752

This document is a draft for review purposes only and does not constitute Agency policy.

F-10	DRAFT—DO NOT CITE OR QUOTE


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Asymptotic Correlation Matrix of Parameter Estimates
Background	Beta(1)

Background
Beta(1)

1

-0.51

-0.51
1

Variable
Background
Beta(1)

Parameter Estimates

Estimate

0. 0221468
0.0143372

Std. Err.

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

Indicates that this value is not calculated.

Analysis of Deviance Table

Model
Full model
Fitted model
Reduced model

Log(likelihood)	# Param'

-68.2561	4

-69.6304	2

-89.1983	1

Deviance Test d.f.

P-value

2.74857
41.8843

0.253
0001

143.261

Dose

Est. Prob.

Goodness of Fit
Expected Observed

Scaled
Residual

0.0000
1.5473
7 .1546
38 . 5608

0.0221
0.0436
0.1175
0.4374

1. 905

2 .180
5. 874
19.685

2 . 000
1. 000
9. 000
18 . 000

86
50
50
45

0.	070
-0.817

1.	373
-0.506

Chi ^2

2 . 81

d.f.

P-value

0.2449

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	0.700996

BMDL =	0.501345

BMDU =	1.04839

Taken together, (0.501345, 1.04839) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor =	0.0199463

This document is a draft for review purposes only and does not constitute Agency policy.

F-l 1	DRAFT—DO NOT CITE OR QUOTE


-------
1 F.l.4.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	14:57 04/01 2010

3

4	Kociba et al., 1978: Hepatocellular adenoma(s) or carcinoma(s)

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-12	DRAFT—DO NOT CITE OR QUOTE


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F.1.5. Kociba et al., 1978: Stratified squamous cell carcinoma of hard palate or nasal
turbinates

F.l.5.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

3

0.815

31.564

5.763E+00

2.795E+00



Multistage Cancer,
2-Degree

3

0.985

30.170

1.369E+01

3.416E+00



Multistage Cancer,
3-Degree

3

0.999

29.930

1.917E+01

3.578E+00



a Best-fitting model, BMDS output presented in this appendix

F.l.5.2. Output for Selected Model: Multistage Cancer, 1-Degree

Kociba et al., 1978: Stratified squamous cell carcinoma of hard palate or nasal turbinates

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\4\Blood\5_mscl_lPerc_nasal.(d)

Gnuplot Plotting File: C:\4\Blood\5_mscl_lPerc_nasal.plt

Thu Apr 01 15:58:14 2010

Source - Table 5

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background = 7.10818e-005
Beta (1) = 0.00222324

This document is a draft for review purposes only and does not constitute Agency policy.

F-13	DRAFT—DO NOT CITE OR QUOTE


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67

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -Background

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Beta(1)

Beta(1)	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0	*	*	*

Beta(1)	0.0022294	*	*	*

- Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-18.7562	4

Fitted model -18.9547 1	0.397012 3	0.9409

Reduced model -24.1972 1	10.882 3	0.01238

AIC:	39.9093

Goodness of Fit

Scaled

Est. Prob. Expected Observed	Size	Residual

0.0000
1.5473
7 .1546
38 . 5608

0.0000
0.0034
0.0158
0.0824

0. 000
0.172
0.791
4 . 036

0. 000

0.	000

1.	000
4 . 000

50
50
49

0. 000
-0.416
0.237
-0.019

Chi ^2

0.23

d.f.

P-value

0.97 2 E

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	4.50809

BMDL =	2.34012

BMDU =	10.4588

Taken together, (2.34012, 10.4588) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00427329

This document is a draft for review purposes only and does not constitute Agency policy.

F-14	DRAFT—DO NOT CITE OR QUOTE


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F.l.5.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

14:58 04/01 2010

Kociba et al., 1978: Stratified squamous cell carcinoma of hard palate or nasal turbinates

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-l 5	DRAFT—DO NOT CITE OR QUOTE


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F.1.6. Kociba et al., 1978: Keratinizing squamous cell carcinoma of lung
F.l.6.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

xV

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

3

0.626

45.298

3.140E+00

1.786E+00



Multistage Cancer,
2-Degree

3

0.964

42.736

1.004E+01

2.707E+00



Multistage Cancer,
3-Degree

3

0.997

42.291

1.556E+01

3.135E+00



a Best-fitting model, BMDS output presented in this appendix

F.l.6.2. Output for Selected Model: Multistage Cancer, 1-Degree
Kociba et al., 1978: Keratinizing squamous cell carcinoma of lung

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\4\Blood\6 mscl IPerc kera carc.(d)

Gnuplot Plotting File: C:\4\Blood\6 mscl IPerc kera carc.pit

Thu Apr 01 15:58:49 2010

Source - Table 5

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
Background =	0

Beta(1) = 0.00419802

This document is a draft for review purposes only and does not constitute Agency policy.

F-16	DRAFT—DO NOT CITE OR QUOTE


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Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -Background

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Beta(1)

Beta(1)	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0	*	*	*

Beta(1)	0.00320098	*	*	*

- Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-20.0957	4

Fitted model -21.6489 1	3.10639 3	0.3755

Reduced model -31.4904 1	22.7894 3	<.0001

AIC:	45.2978

Goodness of Fit

Scaled

Est. Prob. Expected Observed	Size	Residual

0.0000
1.5473
7 .1546
38 . 5608

0.0000
0.0049
0.0226
0.1161

0. 000
0.247
1.132
90

5

0. 000
0. 000
0. 000
7 . 000

50
50
49

0. 000
-0.498
-1.076
0.584

Chi ^2

1.75

d.f.

P-value

0.6263

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	3.13977

BMDL =	1.78648

BMDU =	6.28288

Taken together, (1.78648, 6.28288) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor =	0.0055976

This document is a draft for review purposes only and does not constitute Agency policy.

F-17	DRAFT—DO NOT CITE OR QUOTE


-------
1 F.l.6.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	14:58 04/01 2010

3

4	Kociba et al., 1978: Keratinizing squamous cell carcinoma of lung

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-l 8	DRAFT—DO NOT CITE OR QUOTE


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F.1.7. National Toxicology Program, 1982: Subcutaneous Tissue: Fibrosarcoma
F.l.7.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage Cancer,
1-Degreea

2

0.179

75.385

3.127E+00

1.380E+00



Multistage Cancer,
2-Degree

2

0.179

75.385

3.127E+00

1.380E+00

final fi=0

Multistage Cancer,
3-Degree

2

0.179

75.385

3.127E+00

1.380E+00

final fi=0

a Best-fitting model, BMDS output presented in this appendix

F.l.7.2. Output for Selected Model: Multistage Cancer, 1-Degree
National Toxicology Program, 1982: Subcutaneous Tissue: Fibrosarcoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\4\Blood\7_mscl_lPerc_sub_fibro.(d)

Gnuplot Plotting File: C:\4\Blood\7_mscl_lPerc_sub_fibro.plt

Thu Apr 01 15:59:25 2010

Source - Table 10

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background = 0.0268183
Beta (1) = 0.00211524

This document is a draft for review purposes only and does not constitute Agency policy.

F-19	DRAFT—DO NOT CITE OR QUOTE


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64

Asymptotic Correlation Matrix of Parameter Estimates
Background	Beta(1)

Background	1	-0.63

Beta(1)	-0.63	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0.0149841	*	*	*

Beta(1)	0.00321423	*	*	*

* - Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-33.5998	4

Fitted model -35.6923 2	4.18508 2	0.1234

Reduced model -37.7465 1	8.29346 3	0.04032

AIC:	75.3847

Goodness of Fit

Scaled

Est. Prob. Expected Observed	Size	Residual

0.0000
1.9574
5.6942
29.7519

0.0150

0.0212
0.0328
0.1048

1.124

058
642

5.136

0. 000
2 . 000
3. 000
4 . 000

75

50
50
49

-1.068

0.	926

1.	077
-0.530

Chi ^2

3.44

d.f.

P-value

0.1792

Benchmark Dose Computation
Specified effect =	0.01

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	3.12 683

BMDL =	1.38 04 7

BMDU = 2 .18232e + 006

Taken together, (1.38047, 2.18232e+006) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00724391

This document is a draft for review purposes only and does not constitute Agency policy.

F-20	DRAFT—DO NOT CITE OR QUOTE


-------
1 F.l.7.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	14:59 04/01 2010

3

4	National Toxicology Program, 1982: Subcutaneous Tissue: Fibrosarcoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-21	DRAFT—DO NOT CITE OR QUOTE


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F.1.8. National Toxicology Program, 1982: Liver: Neoplastic Nodule or Hepatocellular
Carcinoma

F.l.8.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

xV

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

2

0.218

135.190

1.169E+00

7.375E-01



Multistage Cancer,
2-Degree

2

0.491

133.447

5.578E+00

8.771E-01



Multistage Cancer,
3-Degree

1

0.239

135.435

7.204E+00

8.786E-01



a Best-fitting model, BMDS output presented in this appendix

F.l.8.2. Output for Selected Model: Multistage Cancer, 1-Degree

National Toxicology Program, 1982: Liver: Neoplastic Nodule or Hepatocellular Carcinoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\4\Blood\8_mscl_lPerc_liver_nod.(d)

Gnuplot Plotting File: C:\4\Blood\8 mscl IPerc liver nod.pit

Thu Apr 01_16:00:00 2010

Source - Table 10

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background = 0.0261097
Beta (1) = 0.0102165

This document is a draft for review purposes only and does not constitute Agency policy.

F-22	DRAFT—DO NOT CITE OR QUOTE


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65

Asymptotic Correlation Matrix of Parameter Estimates
Background	Beta(1)

Background	1	-0.52

Beta(1)	-0.52	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0.0424738	*	*	*

Beta (1)	0.00859382	*	*	*

* - Indicates that this value is not calculated.

Analysis of Deviance Table

Model	Log(likelihood)	# Param's	Deviance	Test d.f.	P-value

Full model	-63.9149	4

Fitted model	-65.5949	2	3.36005	2	0.1864

Reduced model	-74.0195	1	20.2092	3	0.0001536

AIC:	135.19

Goodness of Fit

Scaled

Est. Prob. Expected Observed	Size	Residual

0.0000
1.9574
5.6942
29.7519

0.0425
0.0584
0.0882
0.2585

3.1

2 . 8

4 .
12 .

864
410
667

5. 000
1. 000
3. 000
14.000

75

49

50
49

1. 039
-1.135
-0.703
0. 435

Chi ^2

3. 05

d.f.

P-value

0.2175

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	1.1694 8

BMDL =	0.737535

BMDU =	2.17 906

Taken together, (0.737535, 2.17906) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor =	0.0135587

This document is a draft for review purposes only and does not constitute Agency policy.

F-23	DRAFT—DO NOT CITE OR QUOTE


-------
F.l.8.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

15:00 04/01 2010

National Toxicology Program, 1982: Liver: Neoplastic Nodule or Hepatocellular Carcinoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-24	DRAFT—DO NOT CITE OR QUOTE


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F.1.9. National Toxicology Program, 1982: Adrenal: Cortical Adenoma, or Carcinoma or
Adenoma, NOS

F.l.9.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

xV

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

2

0.337

203.824

1.611E+00

8.140E-01



Multistage Cancer,
2-Degree

2

0.470

203.033

6.652E+00

8.904E-01



Multistage Cancer,
3-Degree

2

0.505

202.868

1.091E+01

9.100E-01



a Best-fitting model, BMDS output presented in this appendix

F.l.9.2. Output for Selected Model: Multistage Cancer, 1-Degree

National Toxicology Program, 1982: Adrenal: Cortical Adenoma, or Carcinoma or Adenoma,
NOS

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\4\Blood\9 mscl IPerc adre cort ad carc.(d)

Gnuplot Plotting File: C:\4\Blood\9 mscl IPerc adre cort ad carc.pit

Thu Apr 01 16:06:15 2010

Source - Table 10

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

This document is a draft for review purposes only and does not constitute Agency policy.

F-25	DRAFT—DO NOT CITE OR QUOTE


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Background =
Beta(1) =

0.134165
0.0069662

Asymptotic Correlation Matrix of Parameter Estimates
Background	Beta(1)

Background	1	-0.54

Beta(1)	-0.54	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0.139854	*	*	*

Beta (1)	0.00623778	*	*	*

* - Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-98.7282	4

Fitted model -99.912 2	2.36764 2	0.3061

Reduced model -102.201 1	6.94636 3	0.07363

AIC:	203.824

Goodness of Fit

Scaled

Dose Est. Prob. Expected Observed	Size	Residual

0.0000 0.1399 10.209 11.000	73	0.267

1.9574 0.1503 7.364 9.000	49	0.654

5.6942 0.1699 8.324 5.000	49	-1.264

29.7519 0.2855 13.135 14.000	46	0.282

Chi ^2 = 2.18	d.f. = 2	P-value = 0.3367

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	1.6112

BMDL =	0.814 04

BMDU =	370555

Taken together, (0.81404, 370555 ) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor =	0.0122844

This document is a draft for review purposes only and does not constitute Agency policy.

F-26	DRAFT—DO NOT CITE OR QUOTE


-------
1 F.l.9.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	15:06 04/01 2010

3

4	National Toxicology Program, 1982: Adrenal: Cortical Adenoma, or Carcinoma or Adenoma,

5	NOS

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-27	DRAFT—DO NOT CITE OR QUOTE


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F.1.10. National Toxicology Program, 1982: Thyroid: Follicular-Cell Adenoma
F. 1.10.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage Cancer,
1-Degreea

2

0.568

92.411

3.376E+00

1.553E+00



Multistage Cancer,
2-Degree

2

0.735

91.749

9.526E+00

1.690E+00



Multistage Cancer,
3-Degree

2

0.773

91.626

1.385E+01

1.720E+00



a Best-fitting model, BMDS output presented in this appendix

F. 1.10.2. Output for Selected Model: Multistage Cancer, 1 -Degree
National Toxicology Program, 1982: Thyroid: Follicular-Cell Adenoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\4\Blood\10_mscl_lPerc_thy_ad.(d)

Gnuplot Plotting File: C:\4\Blood\10_mscl_lPerc_thy_ad.plt

~Thu Apr 01 16:06:53 2010

Source - Table 10

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background = 0.0283212
Beta (1) = 0.00346762

This document is a draft for review purposes only and does not constitute Agency policy.

F-28	DRAFT—DO NOT CITE OR QUOTE


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Asymptotic Correlation Matrix of Parameter Estimates
Background	Beta(1)

Background	1	-0.54

Beta(1)	-0.54	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0.0332432	*	*	*

Beta (1)	0.00297726	*	*	*

* - Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-43.5264	4

Fitted model -44.2053 2	1.35778 2	0.5072

Reduced model -46.2299 1	5.40699 3	0.1443

AIC:	92.4106

Goodness of Fit

Scaled

Dose Est. Prob. Expected Observed	Size	Residual

0.0000 0.0332 2.427 3.000	73	0.374

1.9574 0.0389 1.749 2.000	45	0.194

5.6942 0.0495 2.425 1.000	49	-0.939

29.7519 0.1152 5.414 6.000	47	0.268

Chi ^2 = 1.13	d.f. = 2	P-value = 0.5682

Benchmark Dose Computation

Specified effect	=	0.01

Risk Type	=	Extra risk

Confidence level	=	0.95

BMD	=	3.3757

BMDL	=	1.55287

BMDU	=	306341

Taken together, (1.55287, 306341 ) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00643967

This document is a draft for review purposes only and does not constitute Agency policy.

F-29	DRAFT—DO NOT CITE OR QUOTE


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1 F. 1.10.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	15:06 04/01 2010

3

4	National Toxicology Program, 1982: Thyroid: Follicular-Cell Adenoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-30	DRAFT—DO NOT CITE OR QUOTE


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F.l.ll. National Toxicology Program, 1982: Liver: Neoplastic Nodule or Hepatocellular
Carcinoma

F. 1.11.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

xV

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage Cancer,
1-Degreea

2

0.218

135.190

1.169E+00

7.375E-01



Multistage Cancer,
2-Degree

2

0.491

133.447

5.578E+00

8.771E-01



Multistage Cancer,
3-Degree

1

0.239

135.435

7.204E+00

8.786E-01



a Best-fitting model, BMDS output presented in this appendix

F. 1.11.2. Output for Selected Model: Multistage Cancer, 1 -Degree

National Toxicology Program, 1982: Liver: Neoplastic Nodule or Hepatocellular Carcinoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\4\Blood\ll_mscl_lPerc_liver_nod.(d)

Gnuplot Plotting File: C:\4\Blood\ll mscl IPerc liver nod.pit

~Thu Apr 01 16:07:28 2010

Source - Table 9

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
Background =	0

Beta(1) = 0.00219894

This document is a draft for review purposes only and does not constitute Agency policy.

F-31	DRAFT—DO NOT CITE OR QUOTE


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Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -Background

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Beta(1)

Beta(1)	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0	*	*	*

Beta(1)	0.00163808	*	*	*

- Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-11.3484	4

Fitted model -12.0522 1	1.40767 3	0.7037

Reduced model -15.9189 1	9.14109 3	0.02747

AIC:	26.1044

Goodness of Fit

Scaled

Est. Prob. Expected Observed	Size	Residual

0.0000
1.9569
5.7027
29.8723

0.0000
0.0032
0.0093
0.0478

0. 000
0.160
0. 465
2 . 388

0. 000
0. 000
0. 000
3. 000

74

50
50
50

0. 000
-0.401
-0.685
0. 406

Chi ^2

0.79

d.f.

P-value

0. 8507

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	6.13543

BMDL =	2.70101

BMDU =	18 . 9354

Taken together, (2.70101, 18.9354) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00370232

This document is a draft for review purposes only and does not constitute Agency policy.

F-32	DRAFT—DO NOT CITE OR QUOTE


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F. 1.11.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

15:07 04/01 2010

National Toxicology Program, 1982: Liver: Neoplastic Nodule or Hepatocellular Carcinoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-33	DRAFT—DO NOT CITE OR QUOTE


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F.1.12. National Toxicology Program, 1982: Thyroid: Follicular-Cell Adenoma or
Carcinoma

F.l.12.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

xV

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

2

0.057

149.263

1.208E+00

6.984E-01



Multistage Cancer,
2-Degree

2

0.057

149.263

1.208E+00

6.984E-01

final fi=0

Multistage Cancer,
3-Degree

2

0.057

149.263

1.208E+00

6.984E-01

final fi=0

a Best-fitting model, BMDS output presented in this appendix

F.l.12.2. Output for Selected Model: Multistage Cancer, 1-Degree

National Toxicology Program, 1982: Thyroid: Follicular-Cell Adenoma or Carcinoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\4\Blood\12_mscl_lPerc_thyroid.(d)

Gnuplot Plotting File: C:\4\Blood\12_mscl_lPerc_thyroid.plt

~Thu Apr 01 16:08:03 2010

Source - Table 9

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background = 0.0768555
Beta (1) = 0.00606248

This document is a draft for review purposes only and does not constitute Agency policy.

F-34	DRAFT—DO NOT CITE OR QUOTE


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Asymptotic Correlation Matrix of Parameter Estimates
Background	Beta(1)

Background	1	-0.62

Beta(1)	-0.62	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0.0529006	*	*	*

Beta(1)	0.00831706	*	*	*

* - Indicates that this value is not calculated.

Analysis of Deviance Table

Model	Log(likelihood)	# Param's	Deviance	Test d.f.	P-value

Full model	-69.5946	4

Fitted model	-72.6315	2	6.07383	2	0.04798

Reduced model	-77.5267	1	15.8643	3	0.001209

AIC:	149.263

Goodness of Fit

Scaled

Est. Prob. Expected Observed	Size	Residual

0.0000
1.9569
5.7027
29.8723

0.0529
0.0682
0.0968
0.2613

3. 650

3.273
4 . 839
13.063

1

11

000
5. 000
8 . 000
000

69

48
50
50

-1.425

0.	989

1.	512
-0.664

Chi ^2

5.74

d.f.

P-value

0. 056

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	1.2084

BMDL =	0.698436

BMDU =	2 . 8 910 9

Taken together, (0.698436, 2.89109) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor =	0.0143177

This document is a draft for review purposes only and does not constitute Agency policy.

F-3 5	DRAFT—DO NOT CITE OR QUOTE


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F.l.12.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

15:08 04/01 2010

National Toxicology Program, 1982: Thyroid: Follicular-Cell Adenoma or Carcinoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-36	DRAFT—DO NOT CITE OR QUOTE


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F.1.13. National Toxicology Program, 1982: Adrenal cortex: Adenoma
F.l.13.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

2

0.062

199.309

3.977E+00

1.223E+00



Multistage Cancer,
2-Degree

2

0.062

199.309

3.977E+00

1.223E+00

final fi=0

Multistage Cancer,
3-Degree

2

0.062

199.309

3.977E+00

1.223E+00

final fi=0

a Best-fitting model, BMDS output presented in this appendix

F.l.13.2. Output for Selected Model: Multistage Cancer, 1-Degree
National Toxicology Program, 1982: Adrenal cortex: Adenoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\l\Blood\13_mscl_lPerc_adre_cort.(d)

Gnuplot Plotting File: C:\l\Blood\13 mscl IPerc adre cort.plt

Fri Apr 02 10:53:16 2010

Source - Table 9

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background =	0.163685

Beta (1) = 0.00144687

This document is a draft for review purposes only and does not constitute Agency policy.

F-37	DRAFT—DO NOT CITE OR QUOTE


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Asymptotic Correlation Matrix of Parameter Estimates
Background	Beta(1)

Background	1	-0.6

Beta(1)	-0.6	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0.146079	*	*	*

Beta(1)	0.00252696	*	*	*

- Indicates that this value is not calculated.

Analysis of Deviance Table

Model	Log(likelihood)	# Param's	Deviance	Test d.f.	P-value

Full model	-94.8672	4

Fitted model	-97.6546	2	5.57468	2	0.06158

Reduced model	-98.0432	1	6.35197	3	0.09569

AIC:	199.309

Goodness of Fit

Scaled

Dose	Est. Prob. Expected Observed	Size	Residual

0.0000

0.1461

10.518

6. 000

72

-1.507

1.9569

0.1503

7 . 515

9. 000

50

0.588

5.7027

0.1583

7 .756

12.000

49

1. 661

29.8723

0.2082

10.200

9. 000

49

-0.422

Chi/N2 = 5.55	d.f. = 2	P-value = 0.0622

Benchmark Dose Computation
Specified effect =	0.01

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	3.97724

BMDL =	1.222 8 6

BMDU did not converge for BMR = 0.010000
BMDU calculation failed
BMDU = Inf

This document is a draft for review purposes only and does not constitute Agency policy.

F-3 8	DRAFT—DO NOT CITE OR QUOTE


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1 F.l.13.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	09:53 04/02 2010

3

4	National Toxicology Program, 1982: Adrenal cortex: Adenoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-39	DRAFT—DO NOT CITE OR QUOTE


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F.1.14. National Toxicology Program, 1982: Subcutaneous Tissue: Fibrosarcoma
F. 1.14.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage Cancer,
1-Degreea

2

0.179

75.385

3.127E+00

1.380E+00



Multistage Cancer,
2-Degree

2

0.179

75.385

3.127E+00

1.380E+00

final fi=0

Multistage Cancer,
3-Degree

2

0.179

75.385

3.127E+00

1.380E+00

final fi=0

a Best-fitting model, BMDS output presented in this appendix

F. 1.14.2. Output for Selected Model: Multistage Cancer, 1 -Degree
National Toxicology Program, 1982: Subcutaneous Tissue: Fibrosarcoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\l\Blood\14_mscl_lPerc_subcu_fibro.(d)

Gnuplot Plotting File: C:\l\Blood\14 mscl IPerc subcu fibro.plt

Fri Apr 02 10:59:38 2010

0

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background =	0.010477

Beta(1) = 0.00314237

This document is a draft for review purposes only and does not constitute Agency policy.

F-40	DRAFT—DO NOT CITE OR QUOTE


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Asymptotic Correlation Matrix of Parameter Estimates
Background	Beta(1)

Background	1	-0.55

Beta(1)	-0.55	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0.0124357	*	*	*

Beta (1)	0.0029518	*	*	*

* - Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-30.9876	4

Fitted model -31.0692 2	0.163345 2	0.9216

Reduced model -34.3291 1	6.68308 3	0.08272

AIC:	66.1385

Goodness of Fit

Scaled

Dose Est. Prob. Expected Observed	Size	Residual

0.0000 0.0124 0.920 1.000	74	0.084

1.9460 0.0181 0.905 1.000	50	0.101

5.8440 0.0293 1.408 1.000	48	-0.349

32.0560 0.1016 4.775 5.000	47	0.109

Chi ^2 = 0.15	d.f. = 2	P-value = 0.9274

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	3.4 04 81

BMDL =	1 . 68615

BMDU =	11.3501

Taken together, (1.68615, 11.3501) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00593067

This document is a draft for review purposes only and does not constitute Agency policy.

F-41	DRAFT—DO NOT CITE OR QUOTE


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F. 1.14.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

09:59 04/02 2010

National Toxicology Program, 1982: Subcutaneous Tissue: Fibrosarcoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-42	DRAFT—DO NOT CITE OR QUOTE


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F.1.15. National Toxicology Program, 1982: Hematopoietio System: Lymphoma or
Leukemia

F. 1.15.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

xV

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

2

0.977

261.445

1.145E+00

6.091E-01



Multistage Cancer,
2-Degree

1

0.869

263.426

1.704E+00

6.102E-01



Multistage Cancer,
3-Degree

1

0.869

263.426

1.704E+00

6.102E-01

final fi=0

a Best-fitting model, BMDS output presented in this appendix

F. 1.15.2. Output for Selected Model: Multistage Cancer, 1 -Degree

National Toxicology Program, 1982: Hematopoietio System: Lymphoma or Leukemia

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\l\Blood\15 mscl IPerc mice f lymphoma.(d)

Gnuplot Plotting File: C:\l\Blood\15 mscl IPerc mice f lymphoma.pit

Fri Apr 02 11:00:07 2010

Table 15 page 64 Hematopoietic System Lymphoma or Leukemia

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background =	0.23423

Beta(1) = 0.00892991

This document is a draft for review purposes only and does not constitute Agency policy.

F-43	DRAFT—DO NOT CITE OR QUOTE


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Asymptotic Correlation Matrix of Parameter Estimates
Background	Beta(1)

Background
Beta(1)

1

-0.54

-0.54
1

Variable
Background
Beta(1)

Parameter Estimates

Estimate
0.236159
0. 00877894

Std. Err.

Indicates that this value is not calculated.

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

Model
Full model
Fitted model
Reduced model

Analysis of Deviance Table

Log(likelihood)
-128.699
-128.723
-131.412

Param's

4
2
1

Deviance Test d.f.

P-value

0.0465401
5. 42487

0 . 977
0.1432

AIC:

261.445

Dose

Est. Prob.

Goodness of Fit
Expected Observed

Scaled
Residual

0.0000
1.9460
5.8440
32.0560

0.2362
0.2491
0.2744
0.4235

17.476
12.455
13.169
19.905

18.000

12.000
13.000
20.000

74

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48
47

0.143

-0.149
-0.055
0. 028

Chi ^2

0. 05

d.f.

P-value

0. 9770

Benchmark Dose Computation
Specified effect =	0.01

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	1.14 4 82

BMDL =	0.609084

BMDU =	4 .29581

Taken together, (0.609084, 4.29581) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor =	0.0164181

This document is a draft for review purposes only and does not constitute Agency policy.

F-44	DRAFT—DO NOT CITE OR QUOTE


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F. 1.15.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

10:00 04/02 2010

National Toxicology Program, 1982: Hematopoietio System: Lymphoma or Leukemia

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-45	DRAFT—DO NOT CITE OR QUOTE


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F.1.16. National Toxicology Program, 1982: Liver: Hepatocellular Adenoma or Carcinoma
F. 1.16.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

2

0.340

155.213

1.488E+00

8.265E-01



Multistage Cancer,
2-Degree

2

0.340

155.213

1.488E+00

8.265E-01

final fi=0

Multistage Cancer,
3-Degree

2

0.340

155.213

1.488E+00

8.265E-01

final fi=0

a Best-fitting model, BMDS output presented in this appendix

F. 1.16.2. Output for Selected Model: Multistage Cancer, 1 -Degree

National Toxicology Program, 1982: Liver: Hepatocellular Adenoma or Carcinoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\l\Blood\16_mscl_lPerc_mf_LivAdenCarc.(d)

Gnuplot Plotting File: C:\l\Blood\16_mscl_lPerc_mf_LivAdenCarc.plt

~Fri Apr 02 11:04:11 2010

0

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background =	0.080941

Beta (1) = 0.00583089

This document is a draft for review purposes only and does not constitute Agency policy.

F-46	DRAFT—DO NOT CITE OR QUOTE


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Asymptotic Correlation Matrix of Parameter Estimates
Background	Beta(1)

Background	1	-0.57

Beta(1)	-0.57	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0.0692161	*	*	*

Beta (1)	0.00675636	*	*	*

* - Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-74.5177	4

Fitted model -75.6063 2	2.17736 2	0.3367

Reduced model -79.6703 1	10.3053 3	0.01614

AIC:	155.213

Goodness of Fit

Scaled

Dose Est. Prob. Expected Observed	Size	Residual

0.0000 0.0692 5.053 3.000	73	-0.947

1.9460 0.0814 4.069 6.000	50	0.999

5.8440 0.1053 5.052 6.000	48	0.446

32.0560 0.2505 11.772 11.000	47	-0.260

Chi ^2 = 2.16	d.f. = 2	P-value = 0.3395

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	1.487 54

BMDL =	0.826482

BMDU =	3.9863

Taken together, (0.826482, 3.9863 ) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor =	0.0120995

This document is a draft for review purposes only and does not constitute Agency policy.

F-47	DRAFT—DO NOT CITE OR QUOTE


-------
1 F. 1.16.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	10:04 04/02 2010

3

4	National Toxicology Program, 1982: Liver: Hepatocellular Adenoma or Carcinoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-48	DRAFT—DO NOT CITE OR QUOTE


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F.1.17. National Toxicology Program, 1982: Subcutaneous Tissue: Fibrosarcoma
F. 1.17.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage Cancer,
1-Degreea

2

0.179

75.385

3.127E+00

1.380E+00



Multistage Cancer,
2-Degree

2

0.179

75.385

3.127E+00

1.380E+00

final fi=0

Multistage Cancer,
3-Degree

2

0.179

75.385

3.127E+00

1.380E+00

final fi=0

a Best-fitting model, BMDS output presented in this appendix

F. 1.17.2. Output for Selected Model: Multistage Cancer, 1 -Degree
National Toxicology Program, 1982: Subcutaneous Tissue: Fibrosarcoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\l\Blood\17 mscl IPerc mice f thyroid aden.(d)

Gnuplot Plotting File: C:\l\Blood\17 mscl IPerc mice f thyroid aden.pit

Fri Apr 02 11:04:39 2010

0

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background = 0.0202346
Beta (1) = 0.00292833

This document is a draft for review purposes only and does not constitute Agency policy.

F-49	DRAFT—DO NOT CITE OR QUOTE


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Asymptotic Correlation Matrix of Parameter Estimates
Background	Beta(1)

Background	1	-0.58

Beta(1)	-0.58	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0.0153082	*	*	*

Beta (1)	0.00329742	*	*	*

* - Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-32.0017	4

Fitted model -34.3904 2	4.77738 2	0.09175

Reduced model -37.2405 1	10.4776 3	0.01491

AIC:	72.7807

Goodness of Fit

Scaled

Est. Prob. Expected Observed	Size	Residual

0.0000
1.9460
5.8440
32.0560

0.0153
0.0216
0.0341
1141

056

080
603

0

5.24E

0.	000
3. 000

1.	000
5. 000

69

50
47
46

-1.036
1.867
-0.484
-0.115

Chi ^2

d.f.

P-value

0.0904

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	3.04794

BMDL =	1.43569

BMDU =	138 87 6

Taken together, (1.43569, 138876 ) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00696528

This document is a draft for review purposes only and does not constitute Agency policy.

F-50	DRAFT—DO NOT CITE OR QUOTE


-------
F. 1.17.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

10:04 04/02 2010

National Toxicology Program, 1982: Subcutaneous Tissue: Fibrosarcoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-51	DRAFT—DO NOT CITE OR QUOTE


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F.1.18. National Toxicology Program, 1982: Lung: Alveolar/Bronchiolar Adenoma or
Carcinoma

F. 1.18.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

xV

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage Cancer,
1-Degree

2

0.088

168.342

6.499E-01

3.512E-01



Multistage
Cancer, 2-Degreea

2

0.167

166.946

2.528E+00

4.135E-01



Multistage Cancer,
3-Degree

2

0.182

166.799

4.147E+00

4.230E-01



a Best-fitting model, BMDS output presented in this appendix

F. 1.18.2. Output for Selected Model: Multistage Cancer, 2-Degree

National Toxicology Program, 1982: Lung: Alveolar/Bronchiolar Adenoma or Carcinoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\l\Blood\18 msc2 IPerc lung aden carc.(d)

Gnuplot Plotting File: C:\l\Blood\18 msc2 IPerc lung aden carc.pit

Fri Apr 02 11:05:09 2010

0

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal*dose/Nl-beta2*dose/N2 ) ]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 3
Total number of specified parameters = 0
Degree of polynomial = 2

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background = 0.0868577
Beta(1) =	0

This document is a draft for review purposes only and does not constitute Agency policy.

F-52	DRAFT—DO NOT CITE OR QUOTE


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Beta(2) = 0.00165722

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -Beta(l)

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Background	Beta(2)

Background	1	-0.46

Beta(2)	-0.46	1

Parameter Estimates

95.0% Wald Confidence Interval

Variable Estimate Std. Err.	Lower Conf.	Limit Upper Conf. Limit

Background 0.0942466 *	*	*

Beta(1) 0 *	*	*

Beta(2) 0.00157255 *	*	*

Indicates that this value is not calculated.

Analysis of Deviance Table

Model	Log(likelihood)	# Param's	Deviance	Test d.f.	P-value

Full model	-79.5959	4

Fitted model	-81.4729	2	3.754	2	0.153

Reduced model	-85.3351	1	11.4782	3	0.009402

AIC:	166.946

Goodness of Fit

Scaled

Dose	Est. Prob. Expected Observed	Size	Residual

0.0000	0.0942	6.692	10.000	71	1.344

0.7665	0.0951	4.564	2.000	48	-1.262

2.2711	0.1016	4.875	4.000	48	-0.418

11.2437	0.2575	12.877	13.000	50	0.040

Chi ^2 = 3.57	d.f. = 2	P-value = 0.1674

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	2.52806

BMDL =	0.413504

BMDU =	4 .19905

Taken together, (0.413504, 4.19905) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor =	0.0241835

This document is a draft for review purposes only and does not constitute Agency policy.

F-53	DRAFT—DO NOT CITE OR QUOTE


-------
F. 1.18.3. Figure for Selected Model: Multistage Cancer, 2-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

10:05 04/02 2010

National Toxicology Program, 1982: Lung: Alveolar/Bronchiolar Adenoma or Carcinoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-54	DRAFT—DO NOT CITE OR QUOTE


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F.1.19. National Toxicology Program, 1982: Liver: Hepatocellular Adenoma or Carcinoma
F. 1.19.1. Summary Table of BMDS Modeling Results

Degrees ,	BMD BMDL

Model	of 7 ;	AIC , „ ,, (ng/kg-	Notes

„ , Value	(ng/kg-d)

Freedom	** &	d)

Multistage	2	0.928 258.548 2.110E-01 1.378E-

Cancer, 1-Degree	01

a

Multistage	1	0.779 260.475 3.072E-01 1.385E-

Cancer, 2-Degree	01

Multistage	1	0.790 260.468 2.934E-01 1.385E-

Cancer, 3-Degree	01

a Best-fitting model, BMDS output presented in this appendix

F. 1.19.2. Output for Selected Model: Multistage Cancer, 1 -Degree

National Toxicology Program, 1982: Liver: Hepatocellular Adenoma or Carcinoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\l\Blood\19 mscl IPerc mice m liver aden carc.(d)

Gnuplot Plotting File: C:\l\Blood\19 mscl IPerc mice m liver aden carc.pit

Fri Apr 02 11:05:36 2010

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background =	0.201679

Beta (1) = 0.04864 92

Asymptotic Correlation Matrix of Parameter Estimates

This document is a draft for review purposes only and does not constitute Agency policy.

F-55	DRAFT—DO NOT CITE OR QUOTE


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Background
Beta(1)

Background
1

-0.53

Beta(1)

-0.53
1

Parameter Estimates

Variable
Background
Beta(1)

Estimate
0.204258
0. 0476385

Std. Err.

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

Indicates that this value is not calculated.

Analysis of Deviance Table

Model
Full model
Fitted model
Reduced model

Log(likelihood)	# Param'

-127.199	4

-127.274	2

-135.589	1

Deviance Test d.f.

0.149955
16.7801

P-value

0.9278
0.0007843

AIC:

258.548

Dose

Est. Prob.

Goodness of Fit

Expected

Observed

Scaled
Residual

0.0000
0.7665
2.2711
11.2437

0.2043
0.2328
0.2859
0.5343

14.911

11.407
14.007
26.713

15.000

12.000
13.000
27.000

73

49

49

50

0. 026
0.201
-0.318
0. 081

Chi ^2

0.15

d.f.

P-value

0.9283

Benchmark Dose Computation
Specified effect =	0.01

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	0.210971

BMDL =	0.137771

BMDU =	0.383981

Taken together, (0.137771, 0.383981) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor =	0.0725843

This document is a draft for review purposes only and does not constitute Agency policy.

F-56	DRAFT—DO NOT CITE OR QUOTE


-------
1 F. 1.19.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	10:05 04/02 2010

3

4	National Toxicology Program, 1982: Liver: Hepatocellular Adenoma or Carcinoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-57	DRAFT—DO NOT CITE OR QUOTE


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F.1.20. National Toxicology Program, 2006: Liver: Cholangiocarcinoma
F. 1.20.1. Summary Table of BMDS Modeling Results

Model

Multistage
Cancer, 1-Degree

Multistage
Cancer, 2-Degree

Multistage
Cancer, 3-
Degreea	

Degrees
of

Freedom

5

5
5

i: p-

Value

0.001

0.405
0.993

BMD BMDL

(ng/kg-d) (ng/kg-d)

AIC

138.456	9.481E-01	7.114E-01

119.374	4.263E+00	2.959E+00

113.508	7.574E+00	4.133E+00

Notes

a Best-fitting model, BMDS output presented in this appendix

F. 1.20.2. Output for Selected Model: Multistage Cancer, 3-Degree
National Toxicology Program, 2006: Liver: Cholangiocarcinoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\l\Blood\20_msc3_lPerc_liv_cho-carc.(d)

Gnuplot Plotting File: C:\l\Blood\2 0 msc3 IPerc liv cho-carc.plt

Fri Apr 02 11:06:03 2010

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(

-betal*dose/Nl-beta2*dose/N2-beta3*dose/N3)

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 6

Total number of records with missing values = 0
Total number of parameters in model = 4
Total number of specified parameters = 0
Degree of polynomial = 3

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
Background =	0

Beta(1) =	0

Beta(2) =	0

Beta(3) = 2.44727e-005

This document is a draft for review purposes only and does not constitute Agency policy.

F-58	DRAFT—DO NOT CITE OR QUOTE


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Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -Background -Beta(l)	-Beta(2)

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Beta(3)

Beta(3)	1

Parameter Estimates

Variable
Background
Beta(1)
Beta(2)
Beta(3)

Estimate

0
0
0

2 . 31301e-005

Std. Err.

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

Indicates that this value is not calculated.

Analysis of Deviance Table

Model
Full model
Fitted model
Reduced model

Log(likelihood)

-55.408
-55.7538
-96.9934

Param's Deviance Test d.f.

0.691671
83.1708

P-value

0.9834
C.0001

AIC:

113.508

Est. Prob.

Goodness of Fit
Expected Observed

Scaled
Residual

0.0000

0

0000

0

000

0

000

49

0

000

2.5565

0

0004

0

019

0

000

48

-0

136

5.6937

0

0043

0

196

0

000

46

-0

444

9.7882

0

0215

1

073

1

000

50

-0

071

16.5688

0

0 9 9 9

4

893

4

000

49

-0

426

29.6953

0

4543

24

078

25

000

53

0

254

Chi/N2 = 0.47	d.f. = 5	P-value = 0.9933

Benchmark Dose Computation
Specified effect =	0.01

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	7.57416

BMDL =	4 . 13304

BMDU =	8 . 42557

Taken together, (4.13304, 8.42557) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00241953

This document is a draft for review purposes only and does not constitute Agency policy.

F-59	DRAFT—DO NOT CITE OR QUOTE


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1 F. 1.20.3. Figure for Selected Model: Multistage Cancer, 3-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	10:06 04/02 2010

3

4	National Toxicology Program, 2006: Liver: Cholangiocarcinoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-60	DRAFT—DO NOT CITE OR QUOTE


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F.1.21. National Toxicology Program, 2006: Liver: Hepatocellular adenoma
F. 1.21.1. Summary Table of BMDS Modeling Results

Model

Degrees of x p-

AIC

Freedom
5

Value
0.026

BMD
(ng/kg-d)

BMDL
(ng/kg-d)

0.509

Multistage Cancer,

1-Degree

Multistage Cancer,

2-Degree

Multistage Cancer,

3-Degreea

a Best-fitting model, BMDS output presented in this appendix

Notes

87.024 2.192E+00 1.455E+00

76.982 6.602E+00 4.342E+00

0.933 72.782 1.022E+01 6.527E+00

F. 1.21.2. Output For Selected Model: Multistage Cancer, 3-Degree
National Toxicology Program, 2006: Liver: Hepatocellular adenoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\l\Blood\21_msc3_lPerc_liv_hepat_ad.(d)

Gnuplot Plotting File: C:\l\Blood\21_msc3_lPerc_liv_hepat_ad.plt

~Fri Apr 02 11:06:32 2010

0

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(

-betal*dose/Nl-beta2*dose/N2-beta3*dose/N3) ]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 6

Total number of records with missing values = 0
Total number of parameters in model = 4
Total number of specified parameters = 0
Degree of polynomial = 3

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
Background =	0

Beta(1) =	0

Beta(2) =	0

Beta(3) = 1.08896e-005

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -Background -Beta(l)	-Beta(2)

This document is a draft for review purposes only and does not constitute Agency policy.

F-61	DRAFT—DO NOT CITE OR QUOTE


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have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Beta(3)

Beta(3)	1

Parameter Estimates

Variable
Background
Beta(1)
Beta(2)
Beta(3)

Estimate

0
0
0

9. 41228e-006

Std. Err.

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

Indicates that this value is not calculated.

Analysis of Deviance Table

Model
Full model
Fitted model
Reduced model

Log(likelihood)
-34.4075
-35.3907
-56.3333

Param's Deviance Test d.f.

1.96648
43.8515

P-value

0.8538
C.0001

72.7815

Goodness of Fit

Scaled

Dose

Est

. Prob.

Expected

Observed

Size

Residual

0.0000

0.

0000

0

000

0

000

49

0

000

2.5565

0.

0002

0

008

0

000

48

-0

087

5.6937

0.

0017

0

080

0

000

46

-0

283

9.7882

0.

0088

0

439

0

000

50

-0

6 6 6

16.5688

0.

0419

2

054

1

000

49

-0

751

29.6953

0.

2184

11

577

13

000

53

0

473

Chi ^2

1. 32

d.f.

P-value

0.9330

Benchmark Dose Computation
Specified effect =	0.01

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	10.221

BMDL =	6.52683

BMDU =	11.9754

Taken together, (6.52683, 11.9754) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00153214

This document is a draft for review purposes only and does not constitute Agency policy.

F-62	DRAFT—DO NOT CITE OR QUOTE


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1 F. 1.21.3. Figure For Selected Model: Multistage Cancer, 3-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	10:06 04/02 2010

3

4	National Toxicology Program, 2006: Liver: Hepatocellular adenoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-63	DRAFT—DO NOT CITE OR QUOTE


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F.1.22. National Toxicology Program, 2006: Oral mucosa: squamous cell carcinoma
F. 1.22.1. Summary Table of BMDS Modeling Results

Model

Multistage
Cancer, 1-
Degreea
Multistage
Cancer, 2-Degree

Multistage
Cancer, 3-Degree

Degrees
of

Freedom

x2 p-

Value

AIC

BMD BMDL

(ng/kg-d) (ng/kg-d)

Notes

0.270 126.963 2.204E+00 1.389E+00

0.538 123.896 7.108E+00 2.158E+00
0.565 123.295 1.103E+01 2.298E+00

a Best-fitting model, BMDS output presented in this appendix

F. 1.22.2. Output for Selected Model: Multistage Cancer, 1-Degree
National Toxicology Program, 2006: Oral mucosa: squamous cell carcinoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\l\Blood\22_mscl_lPerc_oral_carc.(d)

Gnuplot Plotting File: C:\l\Blood\22_mscl_lPerc_oral_carc.plt

Fri Apr 02 11:07:00 2010

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 6

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-006
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
Background =	0

Beta(1) = 0.00629243

Asymptotic Correlation Matrix of Parameter Estimates

This document is a draft for review purposes only and does not constitute Agency policy.

F-64	DRAFT—DO NOT CITE OR QUOTE


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Background	Beta(1)

Background	1	-0.67

Beta(1)	-0.67	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0.0139169	*	*	*

Beta(1)	0.00456055	*	*	*

Indicates that this value is not calculated.

Analysis of Deviance Table

Model	Log(likelihood)	# Param's	Deviance	Test d.f.	P-value

Full model	-57.5353	6

Fitted model	-61.4815	2	7.89233	4	0.0956

Reduced model	-67.7782	1	20.4858	5	0.001013

AIC:	126.963

Goodness of Fit

Scaled

Dose	Est. Prob. Expected Observed	Size	Residual

0.0000

0

0139

0

682

1

000

49

0.388

2.5565

0

0253

1

217

2

000

48

0.719

5.6937

0

0392

1

803

1

000

46

-0.610

9.7882

0

0570

2

848

0

000

50

-1.738

16.5688

0

0857

4

198

4

000

49

-0.101

29.6953

0

1388

7

357

10

000

53

1. 050

Chi ^2 = 5.17	d.f. = 4	P-value = 0.2700

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	2.20376

BMDL =	1.38901

BMDU =	4 . 3103

Taken together, (1.38901, 4.3103 ) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00719939

This document is a draft for review purposes only and does not constitute Agency policy.

F-65	DRAFT—DO NOT CITE OR QUOTE


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F. 1.22.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

10:07 04/02 2010

National Toxicology Program, 2006: Oral mucosa: squamous cell carcinoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-66	DRAFT—DO NOT CITE OR QUOTE


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F.1.23. National Toxicology Program, 2006: Pancreas: adenoma or carcinoma
F. 1.23.1. Summary Table of BMDS Modeling Results

Model

Multistage
Cancer, 1-
Degreea
Multistage
Cancer, 2-Degree

Multistage
Cancer, 3-Degree

Degrees
of

Freedom

x2 p-

Value
0.640

0.929
0.986

AIC

BMD BMDL

(ng/kg-d) (ng/kg-d)

Notes

29.373 1.052E+01 4.630E+00

27.061 1.458E+01 7.227E+00
25.972 1.739E+01 9.373E+00

a Best-fitting model, BMDS output presented in this appendix

F. 1.23.2. Output for Selected Model: Multistage Cancer, 1-Degree
National Toxicology Program, 2006: Pancreas: adenoma or carcinoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\l\Blood\23 mscl IPerc pane ad carc.(d)

Gnuplot Plotting File: C:\l\Blood\23 mscl IPerc pane ad carc.pit

Fri Apr 02 11:07:29 2010

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 6

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-006
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
Background =	0

Beta(1) = 0.00191132

Asymptotic Correlation Matrix of Parameter Estimates

This document is a draft for review purposes only and does not constitute Agency policy.

F-67	DRAFT—DO NOT CITE OR QUOTE


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( *** The model parameter(s) -Background

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Beta(1)

Beta(1)

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0	*	*	*

Beta (1)	0.000955662	*	*	*

- Indicates that this value is not calculated.

Analysis of Deviance Table

Model	Log(likelihood)	# Param's	Deviance	Test d.f.	P-value

Full model	-11.4096	6

Fitted model	-13.6865	1	4.55375	5	0.4727

Reduced model	-16.7086	1	10.598	5	0.05996

AIC:	29.373

Goodness of Fit

Scaled

Dose	Est. Prob. Expected Observed	Size	Residual

0.0000

0

0000

0

000

0

000

48

-0

007

2.5565

0

0024

0

117

0

000

48

-0

343

5.6937

0

0054

0

250

0

000

46

-0

501

9.7882

0

0093

0

466

0

000

50

-0

686

16.5688

0

0157

0

754

0

000

48

-0

875

29.6953

0

0280

1

427

3

000

51

1

336

Chi/N2 = 3.39	d.f. = 5	P-value = 0.6403

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	10.5166

BMDL =	4 . 62967

BMDU =	32.8573

Taken together, (4.62967, 32.8573) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00215998

This document is a draft for review purposes only and does not constitute Agency policy.

F-68	DRAFT—DO NOT CITE OR QUOTE


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F. 1.23.3. Figure for Selected Model: Multistage Cancer, 1-Degree

7D

aj
o

0.15

0.1

0.05

0

Multistage Cancer Model with 0.95 Confidence Level

Multistage Cancer
Linear extrapolation

BMDL

BMD

0	5	10	15	20

dose

10:07 04/02 2010

National Toxicology Program, 2006: Pancreas: adenoma or carcinoma

25

30

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-69	DRAFT—DO NOT CITE OR QUOTE


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F.1.24. National Toxicology Program, 2006: Lung: Cystic keratinizing epithelioma

F. 1.24.1. Summary Table of BMDS Modeling Results

Model

Multistage
Cancer, 1-Degree
Multistage
Cancer, 2-Degree

a

Multistage
Cancer, 3-Degree

Degrees
of

Freedom

i: p-

Value

0.062

0.507

0.845

BMD BMDL

(ng/kg-d) (ng/kg-d)

AIC

64.034 3.445E+00 2.084E+00

56.943 8.304E+00 5.245E+00

53.558 1.193E+01 7.765E+00

Notes

a Best-fitting model, BMDS output presented in this appendix

F. 1.24.2. Output for Selected Model: Multistage Cancer, 2-Degree
National Toxicology Program, 2006: Lung: Cystic keratinizing epithelioma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\l\Blood\24_msc2_lPerc_lung_epith.(d)

Gnuplot Plotting File: C:\l\Blood\2 4_msc2_lPerc_lung_epith.plt

Fri Apr 02 11:07:57 2010

The form of the probability function is:

background + (1-background)*[1-EXP(
-betal*dose/Nl-beta2*dose/N2 ) ]

P[response]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 6

Total number of records with missing values = 0
Total number of parameters in model = 3
Total number of specified parameters = 0
Degree of polynomial = 2

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-006
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
Background =	0

Beta(1) =	0

Beta(2) = 0.000216412

This document is a draft for review purposes only and does not constitute Agency policy.

F-70	DRAFT—DO NOT CITE OR QUOTE


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66

67

68

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -Background -Beta(l)

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Beta(2)

Beta(2)	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0	*	*	*

Beta(1)	0	*	*	*

Beta(2)	0.000145744	*	*	*

* - Indicates that this value is not calculated.

Analysis of Deviance Table

Model
Full model
Fitted model
Reduced model

Log(likelihood)

-23.958
-27 .4714
-40.2069

Param's Deviance Test d.f.

P-value

7.02662
32.4976

0.2187
C.0001

AIC:

56.9427

Est. Prob.

Goodness of Fit
Expected Observed

Scaled
Residual

0.0000

0

0000

0

000

0

000

49

0

000

2.5565

0

0010

0

046

0

000

48

-0

214

5.6937

0

0047

0

217

0

000

46

-0

467

9.7882

0

0139

0

679

0

000

49

-0

830

16.5688

0

0392

1

922

0

000

49

-1

414

29.6953

0

1206

6

271

9

000

52

1

162

Chi/N2 = 4.30	d.f. = 5	P-value = 0.5067

Benchmark Dose Computation
Specified effect =	0.01

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =

BMDL =
BMDU =

8.30415
5.24499
11. 2298

Taken together, (5.24499, 11.2298) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00190658

This document is a draft for review purposes only and does not constitute Agency policy.

F-71	DRAFT—DO NOT CITE OR QUOTE


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1 F. 1.24.3. Figure for Selected Model: Multistage Cancer, 2-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	10:07 04/02 2010

3

4	National Toxicology Program, 2006: Lung: Cystic keratinizing epithelioma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-72	DRAFT—DO NOT CITE OR QUOTE


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F.1.25. Toth et al., 1979: Liver: Tumors

F. 1.25.1. Summary Table of BMDS Modeling Results

Model

Degrees
of

Freedom

r p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

1

0.293

155.740

3.684E-01

2.096E-01



Multistage Cancer,
2-Degree

1

0.293

155.740

3.684E-01

2.096E-01

final fi=0

a Best-fitting model, BMDS output presented in this appendix

F. 1.25.2. Output for Selected Model: Multistage Cancer, 1-Degree
Toth et al., 1979: Liver: Tumors

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\l\Blood\25 mscl IPerc adr cor lyr.(d)

Gnuplot Plotting File: C:\l\Blood\25 mscl IPerc adr cor lyr.pit

Fri Apr 02 11:08:26 2010

Table 1

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 1
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background =	0.234952

Beta (1) = 0.0269892

Asymptotic Correlation Matrix of Parameter Estimates
Background	Beta(1)

This document is a draft for review purposes only and does not constitute Agency policy.

F-73	DRAFT—DO NOT CITE OR QUOTE


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Background
Beta(1)

1	-0.55

-0.55	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0.235297	*	*	*

Beta(1)	0.0272796	*	*	*

Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-75.3127	3

Fitted model -75.8702 2	1.11506 1	0.291

Reduced model -79.4897 1	8.35401 2	0.01534

AIC:	155.74

Goodness of Fit

Scaled

Dose Est. Prob. Expected Observed	Size	Residual

0.0000 0.2353 8.941 7.000	38	-0.742

0.5732 0.2472 10.875 13.000	44	0.743

14.2123 0.4811 21.167 21.000	44	-0.050

Chi ^2 = 1.11	d.f. = 1	P-value = 0.2931

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	0.368419

BMDL =	0.209642

BMDU =	1.01064

Taken together, (0.209642, 1.01064) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor =	0.0477004

This document is a draft for review purposes only and does not constitute Agency policy.

F-74	DRAFT—DO NOT CITE OR QUOTE


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1 F. 1.25.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	10:08 04/02 2010

3

4	Toth et al., 1979: Liver: Tumors

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-75	DRAFT—DO NOT CITE OR QUOTE


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F.1.26. Delia Porta et al., 1987: Table 4, B6C3 mice, male, hepatocellular carcinoma
F. 1.26.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

xV

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage Cancer,
1-Degree

1

0.036

165.333

9.239E-01

6.933E-01



Multistage
Cancer, 2-Degreea

1

0.525

161.217

7.143E+00

1.170E+00



a Best-fitting model, BMDS output presented in this appendix

F. 1.26.2. Output for Selected Model: Multistage Cancer, 2-Degree
Delia Porta et al., 1987: Table 4, B6C3 mice, male, hepatocellular carcinoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\l\Blood\94_DPorta_l987_Male_Hep_Carc_MultiCanc2_l.(d)

Gnuplot Plotting File: C:\l\Blood\94_DPorta_1987_Male_Hep_Carc_MultiCanc2_l.plt

Fri Apr 02 13:52:21 2010

Table 4, B6C3 mice, Male, Hepatocellular carcinoma

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal*dose/Nl-beta2*dose/N2 ) ]

The parameter betas are restricted to be positive

Dependent variable = DichEff
Independent variable = Dose

Total number of observations = 3

Total number of records with missing values = 0
Total number of parameters in model = 3
Total number of specified parameters = 0
Degree of polynomial = 2

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background = 0.0865895
Beta(1) =	0

Beta ( 2) = 0.000211877

Asymptotic Correlation Matrix of Parameter Estimates

This document is a draft for review purposes only and does not constitute Agency policy.

F-76	DRAFT—DO NOT CITE OR QUOTE


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( *** The model parameter(s) -Beta(l)

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Background	Beta(2)

Background	1	-0.64

Beta(2)	-0.64	1

Parameter Estimates

95.0% Wald Confidence Interval

Variable Estimate Std. Err.	Lower Conf.	Limit Upper Conf. Limit

Background 0.107218 *	*	*

Beta (1) 0 *	*	*

Beta(2) 0.00019698 *	*	*

- Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-78.4036	3

Fitted model -78.6083 2	0.409345 1	0.5223

Reduced model -94.7394 1	32.6717 2	<.0001

AIC:	161.217

Goodness of Fit

Scaled

Dose Est. Prob. Expected Observed	Size	Residual

0.0000 0.1072 4.610 5.000	43	0.192

37.9990 0.3282 16.740 15.000	51	-0.519

67.7695 0.6387 31.936 33.000	50	0.313

Chi/N2 = 0.40	d.f. = 1	P-value = 0.5249

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	7.142 98

BMDL =	1.16991

BMDU =	8.58118

Taken together, (1.16991, 8.58118) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor =	0.0085477

This document is a draft for review purposes only and does not constitute Agency policy.

F-77	DRAFT—DO NOT CITE OR QUOTE


-------
1 F. 1.26.3. Figure for Selected Model: Multistage Cancer, 2-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	12:52 04/02 2010

3

4	Delia Porta et al., 1987: Table 4, B6C3 mice, male, hepatocellular carcinoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-78	DRAFT—DO NOT CITE OR QUOTE


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F.1.27. Delia Porta et al., 1987: Table 4, B6C3 mice, female, hepatocellular adenoma
F. 1.27.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

xV

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage Cancer,
1-Degree

1

0.380

99.614

3.599E+00

2.186E+00



Multistage
Cancer, 2-Degreea

1

0.863

98.833

1.449E+01

2.342E+00



a Best-fitting model, BMDS output presented in this appendix

F. 1.27.2. Output for Selected Model: Multistage Cancer, 2-Degree
Delia Porta et al., 1987: Table 4, B6C3 mice, female, hepatocellular adenoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\l\Blood\95_DPorta_l987_Female_Hep_Aden_MultiCanc2_l.(d)

Gnuplot Plotting File: C:\l\Blood\95_DPorta_1987_Female_Hep_Aden_MultiCanc2_l.plt

Fri Apr 02 13:52:51 2010

Table 4, B6C3 mice, Female, Hepatocellular adenoma

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal*dose/Nl-beta2*dose/N2 ) ]

The parameter betas are restricted to be positive

Dependent variable = DichEff
Independent variable = Dose

Total number of observations = 3

Total number of records with missing values = 0
Total number of parameters in model = 3
Total number of specified parameters = 0
Degree of polynomial = 2

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background = 0.0364319
Beta(1) =	0

Beta(2) = 4.92861e-005

Asymptotic Correlation Matrix of Parameter Estimates

This document is a draft for review purposes only and does not constitute Agency policy.

F-79	DRAFT—DO NOT CITE OR QUOTE


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( *** The model parameter(s) -Beta(l)

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Background	Beta(2)

Background	1	-0.69

Beta(2)	-0.69	1

Parameter Estimates

95.0% Wald Confidence Interval

Variable Estimate Std. Err.	Lower Conf.	Limit Upper Conf. Limit

Background 0.0392633 *	*	*

Beta(1) 0 *	*	*

Beta(2) 4.78928e-005 *	*	*

Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-47.4015	3

Fitted model -47.4165 2	0.0299957 1	0.8625

Reduced model -51.6367 1	8.47042 2	0.01448

AIC:	98.8329

Goodness of Fit

Scaled

Dose Est. Prob. Expected Observed	Size	Residual

0.0000 0.0393 1.924 2.000	49	0.056

37.5865 0.1021 4.289 4.000	42	-0.147

66.9741 0.2250 10.800 11.000	48	0.069

Chi/N2 = 0.03	d.f. = 1	P-value = 0.8634

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	14.4862

BMDL =	2.34 21

BMDU =	22.1663

Taken together, (2.3421	, 22.1663) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope	Factor = 0.00426967

This document is a draft for review purposes only and does not constitute Agency policy.

F-80	DRAFT—DO NOT CITE OR QUOTE


-------
1 F. 1.27.3. Figure for Selected Model: Multistage Cancer, 2-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	12:52 04/02 2010

3

4	Delia Porta et al., 1987: Table 4, B6C3 mice, female, hepatocellular adenoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-81	DRAFT—DO NOT CITE OR QUOTE


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F.1.28. Delia Porta et al., 1987: Table 4, B6C3 mice, female, hepatocellular carcinoma
F. 1.28.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

xV

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

1

0.019

115.539

2.302E+00

1.545E+00



Multistage Cancer,
2-Degree

1

0.019

115.539

2.302E+00

1.545E+00

final fi=0

a Best-fitting model, BMDS output presented in this appendix

F. 1.28.2. Output for Selected Model: Multistage Cancer, 1-Degree
Delia Porta et al., 1987: Table 4, B6C3 mice, female, hepatocellular carcinoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\l\Blood\96_DPorta_l987_Female_Hep_Carc_MultiCancl_l.(d)

Gnuplot Plotting File: C:\l\Blood\96_DPorta_1987_Female_Hep_Carc_MultiCancl_l.plt

Fri Apr 02 13:53:20 2010

Table 4, B6C3 mice, Female, Hepatocellular carcinoma

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = DichEff
Independent variable = Dose

Total number of observations = 3

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background = 0.0787329
Beta(1) = 0.00304814

Asymptotic Correlation Matrix of Parameter Estimates
Background	Beta(1)

This document is a draft for review purposes only and does not constitute Agency policy.

F-82	DRAFT—DO NOT CITE OR QUOTE


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Background
Beta(1)

1	-0.8

-0.8	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0.0268873	*	*	*

Beta(1)	0.00436529	*	*	*

Indicates that this value is not calculated.

Analysis of Deviance Table

Model	Log(likelihood)	# Param's	Deviance	Test d.f.	P-value

Full model	-53.1726	3

Fitted model	-55.7697	2	5.19425	1	0.02266

Reduced model	-60.7146	1	15.084	2	0.0005303

AIC:	115.539

Goodness of Fit

Scaled

Dose Est. Prob. Expected Observed	Size	Residual

0.0000 0.0269 1.317 1.000	49	-0.280

37.5865 0.1741 7.314 12.000	42	1.907

66.9741 0.2736 13.131 9.000	48	-1.338

Chi/N2 = 5.50	d.f. = 1	P-value = 0.0190

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	2.30233

BMDL =	1.54 47 9

BMDU =	4.37768

Taken together, (1.54479, 4.37768) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00647339

This document is a draft for review purposes only and does not constitute Agency policy.

F-83	DRAFT—DO NOT CITE OR QUOTE


-------
1 F. 1.28.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	12:53 04/02 2010

3

4	Delia Porta et al., 1987: Table 4, B6C3 mice, female, hepatocellular carcinoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-84	DRAFT—DO NOT CITE OR QUOTE


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F.2. ADMINISTERED DOSE BMDS RESULTS

F.2.1. Kociba et al., 1978: Stratified squamous cell carcinoma of hard palate or nasal
turbinates

F.2.1.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

3

0.928

30.745

1.344E+01

6.515E+00



Multistage Cancer,
2-Degree

3

0.998

29.961

3.490E+01

7.216E+00



Multistage Cancer,
3-Degree

3

1.000

29.885

4.941E+01

7.297E+00



a Best-fitting model, BMDS output presented in this appendix

F.2.1.2. Output for Selected Model: Multistage Cancer, 1-Degree

Kociba et al., 1978: Stratified squamous cell carcinoma of hard palate or nasal turbinates

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\Canc\l mscl IPerc palate nasal.(d)

Gnuplot Plotting File: C:\Canc\l mscl IPerc palate nasal.pit

Thu Apr 01 12:47:40 2010

Source - Table 4

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

This document is a draft for review purposes only and does not constitute Agency policy.

F-85	DRAFT—DO NOT CITE OR QUOTE


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Background =	0

Beta(1) = 0.000858074

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -Background

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Beta(1)

Beta(1)	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0	*	*	*

Beta(1)	0.00074801	*	*	*

Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-13.9385	4

Fitted model -14.3726 1	0.868297 3	0.8331

Reduced model -20.2589 1	12.6409 3	0.005481

AIC:	30.7452

Goodness of Fit

Scaled

Dose Est. Prob. Expected Observed	Size	Residual

0.0000 0.0000 0.000 0.000	85	0.000

1.0000 0.0007 0.037 0.000	50	-0.193

10.0000 0.0075 0.373 0.000	50	-0.613

100.0000 0.0721 3.604 4.000	50	0.217

Chi/N2 = 0.46	d.f. = 3	P-value = 0.9276

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	13.4361

BMDL =	6.51522

BMDU =	34.82 9

Taken together, (6.51522, 34.829 ) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00153487

This document is a draft for review purposes only and does not constitute Agency policy.

F-86	DRAFT—DO NOT CITE OR QUOTE


-------
F.2.1.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

11:47 04/01 2010

Kociba et al., 1978: Stratified squamous cell carcinoma of hard palate or nasal turbinates

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-87	DRAFT—DO NOT CITE OR QUOTE


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F.2.2. Kociba et al., 1978: Stratified squamous cell carcinoma of tongue
F.2.2.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

xV

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

2

0.451

48.368

1.742E+01

7.146E+00



Multistage Cancer,
2-Degree

2

0.451

48.368

1.742E+01

7.146E+00

final fi=0

Multistage Cancer,
3-Degree

2

0.451

48.368

1.742E+01

7.146E+00

final fi=0

a Best-fitting model, BMDS output presented in this appendix

F.2.2.2. Output for Selected Model: Multistage Cancer, 1-Degree
Kociba et al., 1978: Stratified squamous cell carcinoma of tongue

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\Canc\2 mscl IPerc tongue.(d)

Gnuplot Plotting File: C:\Canc\2 mscl IPerc tongue.pit

Thu Apr 01 12:48:16 2010

Source - Table 4

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background = 0.0113883
Beta(1) = 0.000508703

This document is a draft for review purposes only and does not constitute Agency policy.

F-88	DRAFT—DO NOT CITE OR QUOTE


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Asymptotic Correlation Matrix of Parameter Estimates
Background	Beta(1)

Background	1	-0.52

Beta(1)	-0.52	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0.00809154	*	*	*

Beta (1)	0.000576915	*	*	*

* - Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-21.1523	4

Fitted model -22.1838 2	2.06309 2	0.3565

Reduced model -24.1972 1	6.08976 3	0.1073

AIC:	48.3677

Goodness of Fit

Scaled

Dose Est. Prob. Expected Observed	Size	Residual

0.0000 0.0081 0.688 0.000	85	-0.833

1.0000 0.0087 0.433 1.000	50	0.865

10.0000 0.0138 0.690 1.000	50	0.376

100.0000 0.0637 3.185 3.000	50	-0.107

Chi/N2 = 1.59	d.f. = 2	P-value = 0.4506

Benchmark Dose Computation
Specified effect =	0.01

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	17.4208

BMDL =	7 .14637

BMDU = 3.20359e+006

Taken together, (7.14637, 3.20359e+006) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00139931

This document is a draft for review purposes only and does not constitute Agency policy.

F-89	DRAFT—DO NOT CITE OR QUOTE


-------
1 F.2.2.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	11:48 04/01 2010

3

4	Kociba et al., 1978: Stratified squamous cell carcinoma of tongue

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-90	DRAFT—DO NOT CITE OR QUOTE


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F.2.3. Kociba et al., 1978: Adenoma of adrenal cortex
F.2.3.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

xV

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

3

0.376

53.518

7.587E+00

4.317E+00



Multistage Cancer,
2-Degree

3

0.376

53.518

7.587E+00

4.317E+00

final fi=0

Multistage Cancer,
3-Degree

3

0.376

53.518

7.587E+00

4.317E+00

final fi=0

a Best-fitting model, BMDS output presented in this appendix

F.2.3.2. Output for Selected Model: Multistage Cancer, 1-Degree
Kociba et al., 1978: Adenoma of adrenal cortex

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\Canc\3 mscl IPerc adre adenoma.(d)

Gnuplot Plotting File: C:\Canc\3 mscl IPerc adre adenoma.pit

Thu Apr 01 12:48:52 2010

Source - Table 5

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background = 0.00927818
Beta(1) = 0.00098105

This document is a draft for review purposes only and does not constitute Agency policy.

F-91	DRAFT—DO NOT CITE OR QUOTE


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Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -Background

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Beta(1)

Beta(1)	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0	*	*	*

Beta(1)	0.00132464	*	*	*

- Indicates that this value is not calculated.

Analysis of Deviance Table

Model	Log(likelihood)	# Param's	Deviance	Test d.f.	P-value

Full model	-24.6514	4

Fitted model	-25.759	1	2.2152	3	0.529

Reduced model	-31.4904	1	13.6781	3	0.003378

AIC:	53.5179

Goodness of Fit

Scaled

Est. Prob. Expected Observed	Size	Residual

0.0000
1.0000
10.0000
100.0000

0.0000
0.0013
0.0132
0.1241

0. 000
0. 066
0. 658
6.203

0. 000
0. 000
2 . 000
5. 000

85

50
50
50

0.	000
-0.257

1.	666
-0.516

Chi ^2

3.11

d.f.

P-value

0.3755

Benchmark Dose Computation

Specified effect	=	0.01

Risk Type	=	Extra risk

Confidence level	=	0.95

BMD	=	7.587 22

BMDL	=	4 . 31737

BMDU	=	17.638

Taken together, (4.31737, 17.638 ) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00231623

This document is a draft for review purposes only and does not constitute Agency policy.

F-92	DRAFT—DO NOT CITE OR QUOTE


-------
1 F.2.3.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	11:48 04/01 2010

3

4	Kociba et al., 1978: Adenoma of adrenal cortex

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-93	DRAFT—DO NOT CITE OR QUOTE


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F.2.4. Kociba et al., 1978: Hepatocellular adenoma(s) or carcinoma(s)
F.2.4.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

xV

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

2

0.034

146.199

1.769E+00

1.225E+00



Multistage Cancer,
2-Degree

2

0.034

146.199

1.768E+00

1.225E+00

final fi=0

Multistage Cancer,
3-Degree

2

0.034

146.199

1.768E+00

1.225E+00

final fi=0

a Best-fitting model, BMDS output presented in this appendix

F.2.4.2. Output for Selected Model: Multistage Cancer, 1-Degree
Kociba et al., 1978: Hepatocellular adenoma(s) or carcinoma(s)

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\Canc\4 mscl IPerc liver ad carc.(d)

Gnuplot Plotting File: C:\Canc\4 mscl IPerc liver ad carc.pit

Thu Apr~01~12:49:25 2010

Source - Table 1 in Goodman and Sauer 1992

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background = 0.0591902
Beta(1) = 0.00458516

This document is a draft for review purposes only and does not constitute Agency policy.

F-94	DRAFT—DO NOT CITE OR QUOTE


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Asymptotic Correlation Matrix of Parameter Estimates
Background	Beta(1)

Background	1	-0.47

Beta(1)	-0.47	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0.0328755	*	*	*

Beta(1)	0.00568299	*	*	*

* - Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-68.2561	4

Fitted model -71.0993 2	5.68634 2	0.05824

Reduced model -89.1983 1	41.8843 3	<.0001

AIC:	146.199

Goodness of Fit

Scaled

Dose Est. Prob. Expected Observed	Size	Residual

0.0000 0.0329 2.827 2.000	86	-0.500

1.0000 0.0384 1.918 1.000	50	-0.676

10.0000 0.0863 4.315 9.000	50	2.359

100.0000 0.4521 20.346 18.000	45	-0.703

Chi ^2 = 6.77	d.f. = 2	P-value = 0.0339

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	1.7685

BMDL =	1.22517

BMDU =	2.77641

Taken together, (1.22517, 2.77641) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00816214

This document is a draft for review purposes only and does not constitute Agency policy.

F-95	DRAFT—DO NOT CITE OR QUOTE


-------
1 F.2.4.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	11:49 04/01 2010

3

4	Kociba et al., 1978: Hepatocellular adenoma(s) or carcinoma(s)

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-96	DRAFT—DO NOT CITE OR QUOTE


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F.2.5. Kociba et al., 1978: Stratified squamous cell carcinoma of hard palate or nasal
turbinates

F.2.5.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

3

0.928

30.745

1.344E+01

6.515E+00



Multistage Cancer,
2-Degree

3

0.998

29.961

3.490E+01

7.216E+00



Multistage Cancer,
3-Degree

3

1.000

29.885

4.941E+01

7.297E+00



a Best-fitting model, BMDS output presented in this appendix

F.2.5.2. Output for Selected Model: Multistage Cancer, 1-Degree

Kociba et al., 1978: Stratified squamous cell carcinoma of hard palate or nasal turbinates

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\Canc\5 mscl IPerc nasal.(d)

Gnuplot Plotting File: C:\Canc\5 mscl IPerc nasal.pit

Thu Apr 01 12:49:59 2010

Source - Table 5

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background = 0.00343283
Beta(1) = 0.000825276

This document is a draft for review purposes only and does not constitute Agency policy.

F-97	DRAFT—DO NOT CITE OR QUOTE


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Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -Background

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Beta(1)

Beta(1)	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0	*	*	*

Beta(1)	0.000953868	*	*	*

- Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-18.7562	4

Fitted model -19.0532 1	0.594034 3	0.8978

Reduced model -24.1972 1	10.882 3	0.01238

AIC:	40.1064

Goodness of Fit

Scaled

Est. Prob. Expected Observed	Size	Residual

0.0000
1.0000
10.0000
100.0000

0.0000
0.0010
0.0095
0.0910

0. 000
0. 048
0.475
4 .458

0. 000

0.	000

1.	000
4 . 000

50
50
49

0. 000
-0.218
0.766
-0.227

Chi ^2

0.69

d.f.

P-value

0. 8764

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	10.5364

BMDL =	5.46907

BMDU =	25.8 64

Taken together, (5.46907, 25.864 ) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00182846

This document is a draft for review purposes only and does not constitute Agency policy.

F-98	DRAFT—DO NOT CITE OR QUOTE


-------
F.2.5.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

11:49 04/01 2010

Kociba et al., 1978: Stratified squamous cell carcinoma of hard palate or nasal turbinates

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-99	DRAFT—DO NOT CITE OR QUOTE


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F.2.6. Kociba et al., 1978: Keratinizing squamous cell carcinoma of lung
F.2.6.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

xV

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

3

0.837

43.792

7.311E+00

4.159E+00



Multistage Cancer,
2-Degree

3

0.994

42.346

2.568E+01

4.917E+00



Multistage Cancer,
3-Degree

3

1.000

42.207

4.026E+01

5.022E+00



a Best-fitting model, BMDS output presented in this appendix

F.2.6.2. Output for Selected Model: Multistage Cancer, 1-Degree
Kociba et al., 1978: Keratinizing squamous cell carcinoma of lung

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\Canc\6 mscl IPerc kera carc.(d)

Gnuplot Plotting File: C:\Canc\6 mscl IPerc kera carc.pit

Thu Apr 01 12:50:34 2010

Source - Table 5

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
Background =	0

Beta(1) = 0.00158635

This document is a draft for review purposes only and does not constitute Agency policy.

F-100 DRAFT—DO NOT CITE OR QUOTE


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Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -Background

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Beta(1)

Beta(1)	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0	*	*	*

Beta (1)	0.0013747	*	*	*

- Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-20.0957	4

Fitted model -20.8959 1	1.60041 3	0.6593

Reduced model -31.4904 1	22.7894 3	<.0001

AIC:	43.7918

Goodness of Fit

Scaled

Est. Prob. Expected Observed	Size	Residual

0.0000
1.0000
10.0000
100.0000

0.0000
0.0014
0.0137
0.1284

0. 000
0. 069
0. 683
6.294

0. 000
0. 000
0. 000
7 . 000

50
50
49

0. 000
-0.262
-0.832
0.302

Chi ^2

0. 85

d.f.

P-value

0. 8370

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	7.31091

BMDL =	4 . 15929

BMDU =	14 . 6306

Taken together, (4.15929, 14.6306) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00240426

This document is a draft for review purposes only and does not constitute Agency policy.

F-101 DRAFT—DO NOT CITE OR QUOTE


-------
1 F.2.6.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	11:50 04/01 2010

3

4	Kociba et al., 1978: Keratinizing squamous cell carcinoma of lung

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-102 DRAFT—DO NOT CITE OR QUOTE


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F.2.7. National Toxicology Program, 1982: Subcutaneous Tissue: Fibrosarcoma
F.2.7.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

xV

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

2

0.146

76.377

9.761E+00

3.964E+00



Multistage Cancer,
2-Degree

2

0.146

76.377

9.761E+00

3.964E+00

final fi=0

Multistage Cancer,
3-Degree

2

0.146

76.377

9.761E+00

3.964E+00

final fi=0

a Best-fitting model, BMDS output presented in this appendix

F.2.7.2. Output for Selected Model: Multistage Cancer, 1-Degree
National Toxicology Program, 1982: Subcutaneous Tissue: Fibrosarcoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\Canc\7 mscl IPerc sub fibro.(d)

Gnuplot Plotting File: C:\Canc\7 mscl IPerc sub fibro.pit

Thu Apr 01 12:51:07 2010

Source - Table 10

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background =	0.030595

Beta(1) = 0.000799545

This document is a draft for review purposes only and does not constitute Agency policy.

F-103 DRAFT—DO NOT CITE OR QUOTE


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Asymptotic Correlation Matrix of Parameter Estimates
Background	Beta(1)

Background	1	-0.54

Beta(1)	-0.54	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0.0231556	*	*	*

Beta (1)	0.00102962	*	*	*

* - Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-33.5998	4

Fitted model -36.1883 2	5.17698 2	0.07513

Reduced model -37.7465 1	8.29346 3	0.04032

AIC:	7 6.3766

Goodness of Fit

Scaled

Dose Est. Prob. Expected Observed	Size	Residual

0.0000 0.0232 1.737 0.000	75	-1.333

1.4000 0.0246 1.228 2.000	50	0.705

7.1000 0.0303 1.514 3.000	50	1.227

71.0000 0.0920 4.509 4.000	49	-0.252

Chi ^2 = 3.84	d.f. = 2	P-value = 0.1463

Benchmark Dose Computation
Specified effect =	0.01

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	9.76124

BMDL =	3.96354

BMDU = 1.03301e+006

Taken together, (3.96354, 1.03301e+006) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor =	0.002523

This document is a draft for review purposes only and does not constitute Agency policy.

F-104 DRAFT—DO NOT CITE OR QUOTE


-------
1 F.2.7.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	11:51 04/01 2010

3

4	National Toxicology Program, 1982: Subcutaneous Tissue: Fibrosarcoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-105 DRAFT—DO NOT CITE OR QUOTE


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F.2.8. National Toxicology Program, 1982: Liver: Neoplastic Nodule or Hepatocellular
Carcinoma

F.2.8.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

2

0.398

133.832

2.554E+00

1.600E+00



Multistage Cancer,
2-Degree

2

0.503

133.436

1.334E+01

1.652E+00



Multistage Cancer,
3-Degree

2

0.503

133.436

1.334E+01

1.652E+00

final fi=0

a Best-fitting model, BMDS output presented in this appendix

F.2.8.2. Output for Selected Model: Multistage Cancer, 1-Degree

National Toxicology Program, 1982: Liver: Neoplastic Nodule or Hepatocellular Carcinoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\Canc\8 mscl IPerc liver nod.(d)

Gnuplot Plotting File: C:\Canc\8 mscl IPerc liver nod.pit

Thu Apr~01 12:51:41 2010

Source - Table 10

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background = 0.0383072
Beta(1) = 0.00417257

This document is a draft for review purposes only and does not constitute Agency policy.

F-106 DRAFT—DO NOT CITE OR QUOTE


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Asymptotic Correlation Matrix of Parameter Estimates
Background	Beta(1)

Background	1	-0.47

Beta(1)	-0.47	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0.0451327	*	*	*

Beta(1)	0.00393556	*	*	*

* - Indicates that this value is not calculated.

Analysis of Deviance Table

Model	Log(likelihood)	# Param's	Deviance	Test d.f.	P-value

Full model	-63.9149	4

Fitted model	-64.916	2	2.00214	2	0.3675

Reduced model	-74.0195	1	20.2092	3	0.0001536

AIC:	133.832

Goodness of Fit

Scaled

Est. Prob. Expected Observed	Size	Residual

0.0000
1.4000
7.1000
71.0000

0.0451

0.0504
0.0714
0 . 277 9

3.385
2.469
3.572
13.618

5. 000
1. 000
3. 000
14.000

75

49

50
49

0. 898
-0.959
-0.314
0.122

Chi ^2

1.

d.f.

P-value

0.3984

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	2 . 55373

BMDL =	1.5 9 983

BMDU =	4.74206

Taken together, (1.59983, 4.74206) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00625067

This document is a draft for review purposes only and does not constitute Agency policy.

F-107 DRAFT—DO NOT CITE OR QUOTE


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1 F.2.8.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	11:51 04/01 2010

3

4	National Toxicology Program, 1982: Liver: Neoplastic Nodule or Hepatocellular Carcinoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-108 DRAFT—DO NOT CITE OR QUOTE


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F.2.9. National Toxicology Program, 1982: Adrenal: Cortical Adenoma, or Carcinoma or
Adenoma, NOS

F.2.9.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

2

0.405

203.380

3.672E+00

1.871E+00



Multistage Cancer,
2-Degree

2

0.501

202.885

1.577E+01

1.974E+00



Multistage Cancer,
3-Degree

2

0.513

202.832

2.600E+01

1.986E+00



a Best-fitting model, BMDS output presented in this appendix

F.2.9.2. Output for Selected Model: Multistage Cancer, 1-Degree

National Toxicology Program, 1982: Adrenal: Cortical Adenoma, or Carcinoma or Adenoma,
NOS

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\Canc\9 mscl IPerc adre cort ad carc.(d)

Gnuplot Plotting File: C:\Canc\9 mscl IPerc adre cort ad carc.pit

Thu Apr 01 12:53:57 2010

Source - Table 10

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background =	0.140663

This document is a draft for review purposes only and does not constitute Agency policy.

F-109 DRAFT—DO NOT CITE OR QUOTE


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Beta(1) = 0.00289845

Asymptotic Correlation Matrix of Parameter Estimates
Background	Beta(1)

Background
Beta(1)

1

-0.48

-0.48
1

Parameter Estimates

Variable
Background
Beta(1)

Estimate
0.143284
0.00273674

Std. Err.

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

Indicates that this value is not calculated.

Model
Full model
Fitted model
Reduced model

Analysis of Deviance Table

Log(likelihood)
-98.7282
-99.6898
-102.201

Param's

4
2
1

Deviance Test d.f.

P-value

1.92318
6.94 636

0.3823
0. 07363

AIC:

203.38

Goodness of Fit

Est. Prob.

Expected

Observed

Scaled
Residual

0.

1.
7 .

71.

0000
4000
1000
0000

0.1433
0.1466
0.1598
0.2946

10.460
7 .181
7.829
13.551

11.
9.
5.

14 .

000
000
000
000

73

49
49
46

0.180
0.735
-1.103
0.145

Chi ^2

1. 81

d.f.

P-value

0.4046

Benchmark Dose Computation
Specified effect =	0.01

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	3.67237

BMDL =	1 . 87133

BMDU =	15.4002

Taken together, (1.87133, 15.4002) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00534381

This document is a draft for review purposes only and does not constitute Agency policy.

F-l 10 DRAFT—DO NOT CITE OR QUOTE


-------
1 F.2.9.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	11:53 04/01 2010

3

4	National Toxicology Program, 1982: Adrenal: Cortical Adenoma, or Carcinoma or Adenoma,

5	NOS

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-lll DRAFT—DO NOT CITE OR QUOTE


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F.2.10. National Toxicology Program, 1982: Thyroid: Follicular-Cell Adenoma
F.2.10.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

xV

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

2

0.661

92.020

7.571E+00

3.488E+00



Multistage Cancer,
2-Degree

2

0.769

91.639

2.257E+01

3.656E+00



Multistage Cancer,
3-Degree

2

0.781

91.601

3.302E+01

3.675E+00



a Best-fitting model, BMDS output presented in this appendix

F.2.10.2. Output for Selected Model: Multistage Cancer, 1-Degree
National Toxicology Program, 1982: Thyroid: Follicular-Cell Adenoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\Canc\10_mscl_lPerc_thy_ad.(d)

Gnuplot Plotting File: C:\Canc\10_mscl_lPerc_thy_ad.plt

Thu Apr 01 12:54:31 2010

Source - Table 10

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background =	0.032089

Beta(1) = 0.00143599

This document is a draft for review purposes only and does not constitute Agency policy.

F-l 12 DRAFT—DO NOT CITE OR QUOTE


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Asymptotic Correlation Matrix of Parameter Estimates
Background	Beta(1)

Background	1	-0.5

Beta(1)	-0.5	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0.0345958	*

Beta(1)	0.00132742	*

Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-43.5264	4

Fitted model -44.0098 2	0.966786 2	0.6167

Reduced model -46.2299 1	5.40699 3	0.1443

AIC:	92.0196

Goodness of Fit

Scaled

Dose Est. Prob. Expected Observed	Size	Residual

0.0000 0.0346 2.525 3.000	73	0.304

1.4000 0.0364 1.637 2.000	45	0.289

7.1000 0.0437 2.139 1.000	49	-0.796

71.0000 0.1214 5.707 6.000	47	0.131

Chi ^2 = 0.83	d.f. = 2	P-value = 0.6614

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	7.57131

BMDL =	3.4 8 815

BMDU =	964 541

Taken together, (3.48815, 964541 ) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00286685

This document is a draft for review purposes only and does not constitute Agency policy.

F-113 DRAFT—DO NOT CITE OR QUOTE


-------
1 F.2.10.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	11:54 04/01 2010

3

4	National Toxicology Program, 1982: Thyroid: Follicular-Cell Adenoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-l 14 DRAFT—DO NOT CITE OR QUOTE


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F.2.11. National Toxicology Program, 1982: Liver: Neoplastic Nodule or Hepatocellular
Carcinoma

F.2.11.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

2

0.398

133.832

2.554E+00

1.600E+00



Multistage Cancer,
2-Degree

2

0.503

133.436

1.334E+01

1.652E+00



Multistage Cancer,
3-Degree

2

0.503

133.436

1.334E+01

1.652E+00

final fi=0

a Best-fitting model, BMDS output presented in this appendix

F.2.11.2. Output for Selected Model: Multistage Cancer, 1 -Degree

National Toxicology Program, 1982: Liver: Neoplastic Nodule or Hepatocellular Carcinoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\Canc\ll mscl IPerc liver nod.(d)

Gnuplot Plotting File: C:\Canc\ll mscl IPerc liver nod.pit

Thu Apr 01 12:55:05 2010

Source - Table 9

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
Background =	0

Beta(1) = 0.000900399

This document is a draft for review purposes only and does not constitute Agency policy.

F-l 15 DRAFT—DO NOT CITE OR QUOTE


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Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -Background

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Beta(1)

Beta(1)	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0	*	*	*

Beta(1)	0.000775683	*	*	*

- Indicates that this value is not calculated.

Analysis of Deviance Table

Model	Log(likelihood)	# Param's	Deviance	Test d.f.	P-value

Full model	-11.3484	4

Fitted model	-11.6976	1	0.698469	3	0.8736

Reduced model	-15.9189	1	9.14109	3	0.02747

AIC:	25.3952

Goodness of Fit

Scaled

Est. Prob. Expected Observed	Size	Residual

0.0000
1.4000
7.1000
71.0000

0.0000
0.0011
0.0055
0.0536

0. 000
0. 054
0.275
2.679

0. 000
0. 000
0. 000
3. 000

74

50
50
50

0. 000
-0.233
-0.525
0.201

Chi ^2

0.37

d.f.

P-value

0.9462

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	12.9568

BMDL =	5.70369

BMDU =	3 9.987 8

Taken together, (5.70369, 39.9878) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00175325

This document is a draft for review purposes only and does not constitute Agency policy.

F-l 16 DRAFT—DO NOT CITE OR QUOTE


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F.2.11.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

11:55 04/01 2010

National Toxicology Program, 1982: Liver: Neoplastic Nodule or Hepatocellular Carcinoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-117 DRAFT—DO NOT CITE OR QUOTE


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F.2.12. National Toxicology Program, 1982: Thyroid: Follicular-Cell Adenoma or
Carcinoma

F.2.12.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

2

0.028

151.224

3.521E+00

1.916E+00



Multistage Cancer,
2-Degree

2

0.028

151.224

3.521E+00

1.916E+00

final fi=0

Multistage Cancer,
3-Degree

2

0.028

151.224

3.521E+00

1.916E+00

final fi=0

a Best-fitting model, BMDS output presented in this appendix

F.2.12.2. Output for Selected Model: Multistage Cancer, 1-Degree

National Toxicology Program, 1982: Thyroid: Follicular-Cell Adenoma or Carcinoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\Canc\12_mscl_lPerc_thyroid.(d)

Gnuplot Plotting File: C:\Canc\12 mscl IPerc thyroid.pit

Thu Apr 01 12:55:38 2010

Source - Table 9

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background = 0.0867382
Beta(1) = 0.00232055

This document is a draft for review purposes only and does not constitute Agency policy.

F-l 18 DRAFT—DO NOT CITE OR QUOTE


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Asymptotic Correlation Matrix of Parameter Estimates
Background	Beta(1)

Background	1	-0.53

Beta(1)	-0.53	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0.0704713	*	*	*

Beta (1)	0.00285481	*	*	*

* - Indicates that this value is not calculated.

Analysis of Deviance Table

Model	Log(likelihood)	# Param's	Deviance	Test d.f.	P-value

Full model	-69.5946	4

Fitted model	-73.6119	2	8.03468	2	0.018

Reduced model	-77.5267	1	15.8643	3	0.001209

AIC:	151.224

Goodness of Fit

Scaled

Est. Prob. Expected Observed	Size	Residual

0.0000
1.4000
7.1000
71.0000

0. 0705
0. 0742
0. 0891
0.2410

4 .863
3.561
4 .456
12.051

1. 000
5. 000
8 . 000
11.000

69

48
50
50

-1.817
0.793
1.759
-0.347

Chi ^2

7 .14

d.f.

P-value

0.0281

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	3.5205

BMDL =	1.91558

BMDU =	9.7 6663

Taken together, (1.91558, 9.76663) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00522034

This document is a draft for review purposes only and does not constitute Agency policy.

F-l 19 DRAFT—DO NOT CITE OR QUOTE


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F.2.12.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

11:55 04/01 2010

National Toxicology Program, 1982: Thyroid: Follicular-Cell Adenoma or Carcinoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-120 DRAFT—DO NOT CITE OR QUOTE


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F.2.13. National Toxicology Program, 1982: Adrenal cortex: Adenoma
F.2.13.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

xV

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

2

0.054

199.672

1.400E+01

3.444E+00



Multistage Cancer,
2-Degree

2

0.054

199.672

1.400E+01

3.444E+00

final fi=0

Multistage Cancer,
3-Degree

2

0.054

199.672

1.400E+01

3.444E+00

final fi=0

a Best-fitting model, BMDS output presented in this appendix

F.2.13.2. Output for Selected Model: Multistage Cancer, 1-Degree
National Toxicology Program, 1982: Adrenal cortex: Adenoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\Canc\13 mscl IPerc adre cort.(d)

Gnuplot Plotting File: C:\Canc\13 mscl IPerc adre cort.pit

Thu Apr~01 12:56:10 2010

Source - Table 9

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background =	0.168444

Beta(1) = 0.000395949

This document is a draft for review purposes only and does not constitute Agency policy.

F-121 DRAFT—DO NOT CITE OR QUOTE


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Asymptotic Correlation Matrix of Parameter Estimates
Background	Beta(1)

Background	1	-0.53

Beta(1)	-0.53	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0.153096	*	*	*

Beta (1)	0.000718012	*	*	*

* - Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-94.8672	4

Fitted model -97.8359 2	5.93732 2	0.05137

Reduced model -98.0432 1	6.35197 3	0.09569

AIC:	199.672

Goodness of Fit

Scaled

Dose	Est. Prob. Expected Observed	Size	Residual

0.0000

0.1531

11.023

6. 000

72

-1.644

1.4000

0.1539

7 . 697

9. 000

50

0.510

7.1000

0.1574

7 .713

12.000

49

1. 682

71.0000

0.1952

9.564

9. 000

49

-0.203

Chi/N2 = 5.83	d.f. = 2	P-value = 0.0541

Benchmark Dose Computation
Specified effect =	0.01

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	13.9974

BMDL =	3.4 4 43

BMDU did not converge for BMR = 0.010000
BMDU calculation failed
BMDU = Inf

This document is a draft for review purposes only and does not constitute Agency policy.

F-122 DRAFT—DO NOT CITE OR QUOTE


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F.2.13.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

T3

aj
o

0.4

0.35

0.3

0.25

0.2

0.15

0.1

0.05

0

Multistage Cancer
Linear extrapolation

BMDL

BMD

0	10	20	30	40	50

dose

11:56 04/01 2010

National Toxicology Program, 1982: Adrenal cortex: Adenoma

60

70

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-123 DRAFT—DO NOT CITE OR QUOTE


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F.2.14. National Toxicology Program, 1982: Subcutaneous Tissue: Fibrosarcoma
F.2.14.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

xV

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

2

0.146

76.377

9.761E+00

3.964E+00



Multistage Cancer,
2-Degree

2

0.146

76.377

9.761E+00

3.964E+00

final fi=0

Multistage Cancer,
3-Degree

2

0.146

76.377

9.761E+00

3.964E+00

final fi=0

a Best-fitting model, BMDS output presented in this appendix

F.2.14.2. Output for Selected Model: Multistage Cancer, 1-Degree
National Toxicology Program, 1982: Subcutaneous Tissue: Fibrosarcoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\Canc\14 mscl IPerc subcu fibro.(d)

Gnuplot Plotting File: C:\Canc\14 mscl IPerc subcu fibro.pit

Thu Apr 01 12:56:41 2010

0

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background = 0.0143554
Beta(1) = 0.000341874

This document is a draft for review purposes only and does not constitute Agency policy.

F-124 DRAFT—DO NOT CITE OR QUOTE


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Asymptotic Correlation Matrix of Parameter Estimates
Background	Beta(1)

Background	1	-0.5

Beta(1)	-0.5	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0.0145028	*

Beta(1)	0.000338561	*

Indicates that this value is not calculated.

Analysis of Deviance Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-30.9876	4

Fitted model -31.0199 2	0.0645971 2	0.9682

Reduced model -34.3291 1	6.68308 3	0.08272

AIC:	6 6.0397

Goodness of Fit

Scaled

Dose Est. Prob. Expected Observed	Size	Residual

0.0000 0.0145 1.073 1.000	74	-0.071

5.7000 0.0164 0.820 1.000	50	0.200

28.6000 0.0240 1.152 1.000	48	-0.143

286.0000 0.1055 4.956 5.000	47	0.021

Chi/N2 = 0.07	d.f. = 2	P-value = 0.9675

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	2 9.6855

BMDL =	14.3524

BMDU =	100.382

Taken together, (14.3524, 100.382) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.000696747

This document is a draft for review purposes only and does not constitute Agency policy.

F-125 DRAFT—DO NOT CITE OR QUOTE


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F.2.14.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

11:56 04/01 2010

National Toxicology Program, 1982: Subcutaneous Tissue: Fibrosarcoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-126 DRAFT—DO NOT CITE OR QUOTE


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F.2.15. National Toxicology Program, 1982: Hematopoietio System: Lymphoma or
Leukemia

F.2.15.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

2

0.987

261.425

1.034E+01

5.456E+00



Multistage Cancer,
2-Degree

2

0.987

261.425

1.034E+01

5.456E+00

final fi=0

Multistage Cancer,
3-Degree

2

0.987

261.425

1.034E+01

5.456E+00

final fi=0

a Best-fitting model, BMDS output presented in this appendix

F.2.15.2. Output for Selected Model: Multistage Cancer, 1-Degree

National Toxicology Program, 1982: Hematopoietio System: Lymphoma or Leukemia

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\Canc\15 mscl IPerc mice f lymphoma.(d)

Gnuplot Plotting File: C:\Canc\15 mscl IPerc mice f lymphoma.pit

Thu Apr~01 12:57:14 2010

Table 15 page 64 Hematopoietic System Lymphoma or Leukemia

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background =	0.242959

Beta(1) = 0.000967723

This document is a draft for review purposes only and does not constitute Agency policy.

F-127 DRAFT—DO NOT CITE OR QUOTE


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Asymptotic Correlation Matrix of Parameter Estimates
Background	Beta(1)

Background
Beta(1)

1

-0.48

-0.48
1

Variable
Background
Beta(1)

Parameter Estimates

Estimate
0.242712
0. 000971954

Std. Err.

Indicates that this value is not calculated.

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

Model
Full model
Fitted model
Reduced model

Analysis of Deviance Table

Log(likelihood)
-128.699
-128.712
-131.412

Param's

4
2
1

Deviance Test d.f.

P-value

0. 0264819
5. 42487

0.9868
0.1432

AIC:

261.425

Dose

Est. Prob.

Goodness of Fit
Expected Observed

Scaled
Residual

0.0000
5.7000
28.6000
286.0000

0.2427
0.2469
0.2635
0.4265

17.961

12 . 345
12.647
20.045

18 . 000

12.000
13.000
20.000

74

50
48
47

0. 011
-0.113
0.116
-0.013

Chi ^2

0. 03

d.f.

P-value

0.9868

Benchmark Dose Computation
Specified effect =	0.01

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	10.3403

BMDL =	5.45599

BMDU =	38.9139

Taken together, (5.45599, 38.9139) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00183285

This document is a draft for review purposes only and does not constitute Agency policy.

F-128 DRAFT—DO NOT CITE OR QUOTE


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1 F.2.15.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	11:57 04/01 2010

3

4	National Toxicology Program, 1982: Hematopoietio System: Lymphoma or Leukemia

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-129 DRAFT—DO NOT CITE OR QUOTE


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F.2.16. National Toxicology Program, 1982: Liver: Hepatocellular Adenoma or Carcinoma
F.2.16.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

xV

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

2

0.244

156.001

1.458E+01

7.829E+00



Multistage Cancer,
2-Degree

2

0.244

156.001

1.458E+01

7.829E+00

final fi=0

Multistage Cancer,
3-Degree

2

0.244

156.001

1.458E+01

7.829E+00

final fi=0

a Best-fitting model, BMDS output presented in this appendix

F.2.16.2. Output for Selected Model: Multistage Cancer, 1-Degree

National Toxicology Program, 1982: Liver: Hepatocellular Adenoma or Carcinoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\Canc\16 mscl IPerc mice f liv aden carc.(d)

Gnuplot Plotting File: C:\Canc\16 mscl IPerc mice f liv aden carc.pit

Thu Apr~01 12757:47 2010

0

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background = 0.0888873
Beta (1) = 0.000616931

This document is a draft for review purposes only and does not constitute Agency policy.

F-130 DRAFT—DO NOT CITE OR QUOTE


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Asymptotic Correlation Matrix of Parameter Estimates
Background	Beta(1)

Background	1	-0.5

Beta(1)	-0.5	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0.0788077	*

Beta(1)	0.000689385	*

Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-74.5177	4

Fitted model -76.0006 2	2.96597 2	0.227

Reduced model -79.6703 1	10.3053 3	0.01614

AIC:	156.001

Goodness of Fit

Scaled

Dose Est. Prob. Expected Observed	Size	Residual

0.0000 0.0788 5.753 3.000	73	-1.196

5.7000 0.0824 4.121 6.000	50	0.966

28.6000 0.0968 4.646 6.000	48	0.661

286.0000 0.2436 11.452 11.000	47	-0.153

Chi ^2 = 2.82	d.f. = 2	P-value = 0.2436

Benchmark Dose Computation

Specified effect	=	0.01

Risk Type	=	Extra risk

Confidence level	=	0.95

BMD	=	14.5787

BMDL	=	7 . 82902

BMDU	=	42 . 4536

Taken together, (7.82902, 42.4536) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor =	0.0012773

This document is a draft for review purposes only and does not constitute Agency policy.

F-131 DRAFT—DO NOT CITE OR QUOTE


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1 F.2.16.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	11:57 04/01 2010

3

4	National Toxicology Program, 1982: Liver: Hepatocellular Adenoma or Carcinoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-132 DRAFT—DO NOT CITE OR QUOTE


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F.2.17. National Toxicology Program, 1982: Subcutaneous Tissue: Fibrosarcoma
F.2.17.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

xV

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

2

0.146

76.377

9.761E+00

3.964E+00



Multistage Cancer,
2-Degree

2

0.146

76.377

9.761E+00

3.964E+00

final fi=0

Multistage Cancer,
3-Degree

2

0.146

76.377

9.761E+00

3.964E+00

final fi=0

a Best-fitting model, BMDS output presented in this appendix

F.2.17.2. Output for Selected Model: Multistage Cancer, 1-Degree
National Toxicology Program, 1982: Subcutaneous Tissue: Fibrosarcoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\Canc\17 mscl IPerc mice f thyroid aden.(d)

Gnuplot Plotting File: C:\Canc\17 mscl IPerc mice f thyroid aden.pit

Thu Apr~01 12:58:20 2010

0

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background =	0.02405

Beta(1) = 0.000315564

This document is a draft for review purposes only and does not constitute Agency policy.

F-133 DRAFT—DO NOT CITE OR QUOTE


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Asymptotic Correlation Matrix of Parameter Estimates
Background	Beta(1)

Background	1	-0.51

Beta(1)	-0.51	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0.0207192	*	*	*

Beta (1)	0.000331835	*	*	*

* - Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-32.0017	4

Fitted model -34.6122 2	5.22112 2	0.07349

Reduced model -37.2405 1	10.4776 3	0.01491

AIC:	73.2245

Goodness of Fit

Scaled

Dose Est. Prob. Expected Observed	Size	Residual

0.0000 0.0207 1.430 0.000	69	-1.208

5.7000 0.0226 1.128 3.000	50	1.782

28.6000 0.0300 1.409 1.000	47	-0.350

286.0000 0.1094 5.032 5.000	46	-0.015

Chi ^2 = 4.76	d.f. = 2	P-value = 0.0927

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	30.2871

BMDL =	13.993

BMDU =	130.014

Taken together, (13.993	, 130.014) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope	Factor = 0.000714641

This document is a draft for review purposes only and does not constitute Agency policy.

F-134 DRAFT—DO NOT CITE OR QUOTE


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F.2.17.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

11:58 04/01 2010

National Toxicology Program, 1982: Subcutaneous Tissue: Fibrosarcoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-135 DRAFT—DO NOT CITE OR QUOTE


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F.2.18. National Toxicology Program, 1982: Lung: Alveolar/Bronchiolar Adenoma or
Carcinoma

F.2.18.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

x2 p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage Cancer,
1-Degree

2

0.138

167.341

3.706E+00

2.026E+00



Multistage
Cancer, 2-Degreea

2

0.181

166.805

1.590E+01

2.139E+00



Multistage Cancer,
3-Degree

2

0.185

166.777

2.618E+01

2.145E+00



a Best-fitting model, BMDS output presented in this appendix

F.2.18.2. Output for Selected Model: Multistage Cancer, 2-Degree

National Toxicology Program, 1982: Lung: Alveolar/Bronchiolar Adenoma or Carcinoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\Canc\18 msc2 IPerc lung aden carc.(d)

Gnuplot Plotting File: C:\Canc\18 msc2 IPerc lung aden carc.pit

Thu Apr 01 12:58:55 2010

0

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal*dose/Nl-beta2*dose/N2 ) ]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 3
Total number of specified parameters = 0
Degree of polynomial = 2

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background = 0.0889033
Beta(1) =	0

This document is a draft for review purposes only and does not constitute Agency policy.

F-136 DRAFT—DO NOT CITE OR QUOTE


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Beta(2) = 4.12413e-005

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -Beta(l)

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Background	Beta(2)

Background	1	-0.45

Beta(2)	-0.45	1

Parameter Estimates

Variable
Background
Beta(1)
Beta(2)

Estimate

0.0953987
0

3.97 322e-005

Std. Err.

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

* - Indicates that this value is not calculated.

Analysis of Deviance Table

Model
Full model
Fitted model
Reduced model

Log(likelihood)
-79.5959
-81.4024
-85.3351

Param's

4
2
1

Deviance Test d.f.

3.61287
11.4782

P-value

0.1642
0.009402

166.805

Dose

Est. Prob.

Goodness of Fit
Expected Observed

Scaled
Residual

0.0000	0.0954	6.773 10.000	71	1.304

1.4000	0.0955	4.583 2.000	48	-1.268

7.1000	0.0972	4.666 4.000	48	-0.325

71.0000	0.2596	12.979 13.000	50	0.007

Chi ^2 = 3.41 d.f.	= 2	P-value = 0.1814

Benchmark Dose Computation
Specified effect =	0.01

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =

BMDL =
BMDU =

15.9045

2 .1388
26.2712

Taken together, (2.1388 , 26.2712) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00467551

This document is a draft for review purposes only and does not constitute Agency policy.

F-137 DRAFT—DO NOT CITE OR QUOTE


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F.2.18.3. Figure for Selected Model: Multistage Cancer, 2-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

11:58 04/01 2010

National Toxicology Program, 1982: Lung: Alveolar/Bronchiolar Adenoma or Carcinoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-138 DRAFT—DO NOT CITE OR QUOTE


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F.2.19. National Toxicology Program, 1982: Liver: Hepatocellular Adenoma or Carcinoma
F.2.19.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

xV

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

2

0.916

258.572

1.338E+00

8.620E-01



Multistage Cancer,
2-Degree

2

0.916

258.572

1.338E+00

8.620E-01

final fi=0

Multistage Cancer,
3-Degree

2

0.916

258.572

1.338E+00

8.620E-01

final fi=0

a Best-fitting model, BMDS output presented in this appendix

F.2.19.2. Output for Selected Model: Multistage Cancer, 1-Degree

National Toxicology Program, 1982: Liver: Hepatocellular Adenoma or Carcinoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\Canc\19 mscl IPerc mice m liver aden carc.(d)

Gnuplot Plotting File: C:\Canc\19 mscl IPerc mice m liver aden carc.pit

Thu Apr~01 12:59:28 2010

0

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 4

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background =	0.22264

Beta(1) = 0.0074005

This document is a draft for review purposes only and does not constitute Agency policy.

F-139 DRAFT—DO NOT CITE OR QUOTE


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Asymptotic Correlation Matrix of Parameter Estimates
Background	Beta(1)

Background
Beta(1)

1

-0. Ai

-0. 4t

Variable
Background
Beta(1)

Parameter Estimates

Estimate
0.219315
0.00750879

Std. Err.

Indicates that this value is not calculated.

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

Model
Full model
Fitted model
Reduced model

Analysis of Deviance Table

Log(likelihood)
-127.199
-127.286
-135.589

258.572

Param's

4
2
1

Deviance Test d.f.

0.174343
16.7801

P-value

0. 9165
0.0007843

Dose

Goodness of Fit

Est. Prob.

Expected

Observed

Size

Scaled
Residual

0.0000
1.4000
7.1000
71.0000

Chi ^2

0.17

0.2193
0.2275
0.2598
0.5419

d.f.

16.010
11.146
12.732
27.096

15.000

12.000
13.000
27.000

P-value

0. 9164

73

49

49

50

-0.286

0.291
0. 087
-0.027

Benchmark Dose Computation

Specified effect
Risk Type
Confidence level

BMD
BMDL
BMDU

0. 01
Extra risk

0. 95
1.33848
0. 861975
2 .4671

Taken together, (0.861975, 2.4671 ) is a 90
interval for the BMD

two-sided confidence

Multistage Cancer Slope Factor

0. 0116013

This document is a draft for review purposes only and does not constitute Agency policy.

F-140 DRAFT—DO NOT CITE OR QUOTE


-------
1 F.2.19.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	11:59 04/01 2010

3

4	National Toxicology Program, 1982: Liver: Hepatocellular Adenoma or Carcinoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-141 DRAFT—DO NOT CITE OR QUOTE


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F.2.20. National Toxicology Program, 2006: Liver: Cholangiocarcinoma
F.2.20.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

xV

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage Cancer,
1-Degree

5

0.024

129.070

1.872E+00

1.404E+00



Multistage Cancer,
2-Degree

5

0.947

114.349

9.440E+00

5.290E+00



Multistage
Cancer, 3-Degreea

4

0.995

115.158

1.310E+01

4.468E+00



a Best-fitting model, BMDS output presented in this appendix

F.2.20.2. Output for Selected Model: Multistage Cancer, 3-Degree
National Toxicology Program, 2006: Liver: Cholangiocarcinoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\Canc\20 msc3 IPerc liv cho-carc.(d)

Gnuplot Plotting File: C:\Canc\20 msc3 IPerc liv cho-carc.pit

Thu Apr 01 13:00:03 2010

0

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(

-betal*dose/Nl-beta2*dose/N2-beta3*dose/N3) ]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 6

Total number of records with missing values = 0
Total number of parameters in model = 4
Total number of specified parameters = 0
Degree of polynomial = 3

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
Background =	0

Beta(1) = 0.000561481
Beta(2) = 1.74365e-005
Beta(3) = 1.40248e-006

This document is a draft for review purposes only and does not constitute Agency policy.

F-142 DRAFT—DO NOT CITE OR QUOTE


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Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -Background -Beta(l)

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Beta(2)	Beta(3)

Beta(2)	1	-0.99

Beta(3)	-0.99	1

Parameter Estimates

Variable
Background
Beta(1)
Beta(2)
Beta(3)

Estimate

0
0

4 . 35 92 7e-0 05
1.14186e-006

Std. Err.

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

Indicates that this value is not calculated.

Analysis of Deviance Table

Model
Full model
Fitted model
Reduced model

Log(likelihood)

-55.408
-55.5789
-96.9934

Param's Deviance Test d.f.

0.34181
83.1708

P-value

0. 987
0001

AIC:

115.158

Goodness of Fit

Scaled

Dose

Est

. Prob.

Expected

Observed

Size

Residual

0.0000

0.

0000

0. 000

0

000

49

0

000

2.1400

0.

0002

0. 010

0

000

48

-0

101

7.1400

0.

0026

0.121

0

000

46

-0

349

15.7000

0.

0150

0.752

1

000

50

0

288

32.9000

0.

0841

4 121

4

000

49

-0

062

71.4000

0.

4716

24.994

25

000

53

0

002

Chi ^2

0.22

d.f.

P-value

0.9945

Benchmark Dose Computation
Specified effect =	0.01

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	13.1014

BMDL =	4 . 46755

BMDU =	19.17 83

Taken together, (4.46755, 19.1783) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00223836

This document is a draft for review purposes only and does not constitute Agency policy.

F-143 DRAFT—DO NOT CITE OR QUOTE


-------
1 F.2.20.3. Figure for Selected Model: Multistage Cancer, 3-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	12:00 04/01 2010

3

4	National Toxicology Program, 2006: Liver: Cholangiocarcinoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-144 DRAFT—DO NOT CITE OR QUOTE


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F.2.21. National Toxicology Program, 2006: Liver: Hepatocellular adenoma
F.2.21.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

xV

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage Cancer,
1-Degree

5

0.131

82.310

4.393E+00

2.915E+00



Multistage Cancer,
2-Degree

5

0.857

73.656

1.475E+01

8.618E+00



Multistage
Cancer, 3-Degreea

5

0.999

71.216

2.379E+01

1.153E+01



a Best-fitting model, BMDS output presented in this appendix

F.2.21.2. Output for Selected Model: Multistage Cancer, 3-Degree
National Toxicology Program, 2006: Liver: Hepatocellular adenoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\Canc\21 msc3 IPerc liv hepat ad.(d)

Gnuplot Plotting File: C:\Canc\21 msc3 IPerc liv hepat ad.pit

Thu Apr 01 13:00:36 2010

0

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(

-betal*dose/Nl-beta2*dose/N2-beta3*dose/N3) ]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 6

Total number of records with missing values = 0
Total number of parameters in model = 4
Total number of specified parameters = 0
Degree of polynomial = 3

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
Background =	0

Beta(1) =	0

Beta(2) =	0

Beta(3) = 7.77141e-007

This document is a draft for review purposes only and does not constitute Agency policy.

F-145 DRAFT—DO NOT CITE OR QUOTE


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Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -Background -Beta(l)	-Beta(2)

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Beta(3)

Beta(3)	1

Parameter Estimates

Variable
Background
Beta(1)
Beta(2)
Beta(3)

Estimate

0
0
0

7 . 46408e-007

Std. Err.

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

Indicates that this value is not calculated.

Analysis of Deviance Table

Model
Full model
Fitted model
Reduced model

Log(likelihood)
-34.4075
-34.6078
-56.3333

Param's Deviance Test d.f.

0.40065
43.8515

P-value

0.9953
C.0001

AIC:

71. 2156

Dose

Est. Prob.

Goodness of Fit
Expected Observed

Scaled
Residual

0.0000

0

0000

0

000

0

000

49

0

000

2.1400

0

0000

0

000

0

000

48

-0

019

7.1400

0

0003

0

012

0

000

46

-0

112

15.7000

0

0029

0

144

0

000

50

-0

380

32.9000

0

0262

1

285

1

000

49

-0

255

71.4000

0

2379

12

609

13

000

53

0

126

Chi/N2 = 0.24	d.f. = 5	P-value = 0.9986

Benchmark Dose Computation
Specified effect =	0.01

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	23.7 904

BMDL =	11.5343

BMDU =	27 . 8755

Taken together, (11.5343, 27.8755) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.000866978

This document is a draft for review purposes only and does not constitute Agency policy.

F-146 DRAFT—DO NOT CITE OR QUOTE


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F.2.21.3. Figure for Selected Model: Multistage Cancer, 3-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

12:00 04/01 2010

National Toxicology Program, 2006: Liver: Hepatocellular adenoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-147 DRAFT—DO NOT CITE OR QUOTE


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F.2.22. National Toxicology Program, 2006: Oral mucosa: squamous cell carcinoma
F.2.22.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

xV

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

4

0.386

125.484

4.751E+00

2.956E+00



Multistage Cancer,
2-Degree

4

0.587

123.245

1.635E+01

3.845E+00



Multistage Cancer,
3-Degree

4

0.587

123.245

1.635E+01

3.844E+00

final fi=0

a Best-fitting model, BMDS output presented in this appendix

F.2.22.2. Output for Selected Model: Multistage Cancer, 1-Degree
National Toxicology Program, 2006: Oral mucosa: squamous cell carcinoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\Canc\22 mscl IPerc oral carc.(d)

Gnuplot Plotting File: C:\Canc\22 mscl IPerc oral carc.pit

Thu Apr~01 13:01:11 2010

0

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 6

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background = 0.00607545
Beta(1) = 0.00265195

This document is a draft for review purposes only and does not constitute Agency policy.

F-148 DRAFT—DO NOT CITE OR QUOTE


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Asymptotic Correlation Matrix of Parameter Estimates
Background	Beta(1)

Background
Beta(1)

1

-0. (

-0. (

Parameter Estimates

Variable
Background
Beta(1)

Estimate

0.0171416
0.00211536

Std. Err.

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

Indicates that this value is not calculated.

Analysis of Deviance Table

Model
Full model
Fitted model
Reduced model

Log(likelihood)

-57.5353
-60.7418
-67.7782

Param's Deviance Test d.f.

6.41293
20.4858

P-value

0.1704
0.001013

125.484

Goodness of Fit

Scaled

Dose

Est

. Prob.

Expected

Observed

Size

Residual

0.0000

0.

0171

0

840

1

000

49

0

176

2.1400

0.

0216

1

036

2

000

48

0

958

7.1400

0.

0319

1

466

1

000

46

-0

391

15.7000

0.

04 92

2

462

0

000

50

-1

609

32.9000

0.

0832

4

078

4

000

49

-0

040

71.4000

0.

1549

8

211

10

000

53

0

679

Chi ^2

4 .15

d.f.

P-value

0.3855

Benchmark Dose Computation
Specified effect =	0.01

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	4 .75111

BMDL =	2.9556

BMDU =	9.194 54

Taken together, (2.9556	, 9.19454) is a 90 % two-sided confidence
interval for the BMD

Multistage Cancer Slope	Factor = 0.0033834

This document is a draft for review purposes only and does not constitute Agency policy.

F-149 DRAFT—DO NOT CITE OR QUOTE


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F.2.22.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

12:01 04/01 2010

National Toxicology Program, 2006: Oral mucosa: squamous cell carcinoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-l50 DRAFT—DO NOT CITE OR QUOTE


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F.2.23. National Toxicology Program, 2006: Pancreas: adenoma or carcinoma
F.2.23.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

xV

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

5

0.796

28.316

2.120E+01

9.335E+00



Multistage Cancer,
2-Degree

5

0.977

26.230

3.270E+01

1.389E+01



Multistage Cancer,
3-Degree

5

0.997

25.427

4.057E+01

1.755E+01



a Best-fitting model, BMDS output presented in this appendix

F.2.23.2. Output for Selected Model: Multistage Cancer, 1-Degree
National Toxicology Program, 2006: Pancreas: adenoma or carcinoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\Canc\23 mscl IPerc pane ad carc.(d)

Gnuplot Plotting File: C:\Canc\23 mscl IPerc pane ad carc.pit

Thu Apr~01~13:01:43 2010

0

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 6

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
Background =	0

Beta(1) = 0.000817541

Asymptotic Correlation Matrix of Parameter Estimates

This document is a draft for review purposes only and does not constitute Agency policy.

F-151 DRAFT—DO NOT CITE OR QUOTE


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( *** The model parameter(s) -Background

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Beta(1)

Beta(1)

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0	*	*	*

Beta (1)	0.000474004	*	*	*

- Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-11.4096	6

Fitted model -13.1581 1	3.49702 5	0.6238

Reduced model -16.7086 1	10.598 5	0.05996

AIC:	28.3163

Goodness of Fit

Scaled

Dose	Est. Prob. Expected Observed	Size	Residual

0.0000

0

0000

0

000

0

000

48

0

000

2.1400

0

0010

0

049

0

000

48

-0

221

7.1400

0

0034

0

155

0

000

46

-0

395

15.7000

0

0074

0

371

0

000

50

-0

611

32.9000

0

0155

0

743

0

000

48

-0

869

71.4000

0

0333

1

697

3

000

51

1

017

Chi ^2 = 2.37	d.f. = 5	P-value = 0.7964

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	21.2031

BMDL =	9.33481

BMDU =	65.4351

Taken together, (9.33481, 65.4351) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00107126

This document is a draft for review purposes only and does not constitute Agency policy.

F-152 DRAFT—DO NOT CITE OR QUOTE


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F.2.23.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

12:01 04/01 2010

National Toxicology Program, 2006: Pancreas: adenoma or carcinoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-153 DRAFT—DO NOT CITE OR QUOTE


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F.2.24. National Toxicology Program, 2006: Lung: Cystic keratinizing epithelioma

F.2.24.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

xV

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage Cancer,
1-Degree

5

0.192

60.806

6.922E+00

4.187E+00



Multistage
Cancer, 2-Degreea

5

0.771

54.363

1.858E+01

1.069E+01



Multistage Cancer,
3-Degree

5

0.961

51.847

2.778E+01

1.556E+01



a Best-fitting model, BMDS output presented in this appendix

F.2.24.2. Output for Selected Model: Multistage Cancer, 2-Degree
National Toxicology Program, 2006: Lung: Cystic keratinizing epithelioma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\Canc\24_msc2_lPerc_lung_epith.(d)

Gnuplot Plotting File: C:\Canc\24 msc2 IPerc lung epith.plt

Thu Apr~01 13:02:19 2010

0

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal*dose/Nl-beta2*dose/N2 ) ]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 6

Total number of records with missing values = 0
Total number of parameters in model = 3
Total number of specified parameters = 0
Degree of polynomial = 2

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
Background =	0

Beta(1) =	0

Beta(2) = 3.77591e-005

This document is a draft for review purposes only and does not constitute Agency policy.

F-154 DRAFT—DO NOT CITE OR QUOTE


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Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -Background -Beta(l)

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Beta(2)

Beta(2)	1

Parameter Estimates

Variable
Background
Beta(1)
Beta(2)

Estimate

0
0

2.91011e-005

Std. Err.

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

Indicates that this value is not calculated.

Analysis of Deviance Table

Model
Full model
Fitted model
Reduced model

Log(likelihood)

-23.958
-26.1815
-40.2069

Param's Deviance Test d.f.

4.44693
32.4976

P-value

0. 487
0001

AIC:

54.363

Goodness of Fit

Scaled

Dose

Est

. Prob.

Expected

Observed

Size

Residual

0.0000

0.

0000

0

000

0

000

49

0

000

2.1400

0.

0001

0

006

0

000

48

-0

080

7.1400

0.

0015

0

068

0

000

46

-0

261

15.7000

0.

0071

0

350

0

000

49

-0

594

32.9000

0.

0310

1

519

0

000

49

-1

252

71.4000

0.

1379

7

170

9

000

52

0

736

Chi ^2

2 . 54

d.f.

P-value

0.7708

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	18.5839

BMDL =	10.687 8

BMDU =	25.1324

Taken together, (10.6878, 25.1324) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.000935646

This document is a draft for review purposes only and does not constitute Agency policy.

F-155 DRAFT—DO NOT CITE OR QUOTE


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1 F.2.24.3. Figure for Selected Model: Multistage Cancer, 2-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	12:02 04/01 2010

3

4	National Toxicology Program, 2006: Lung: Cystic keratinizing epithelioma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-l56 DRAFT—DO NOT CITE OR QUOTE


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F.2.25. Toth et al., 1979: Liver: Tumors
F.2.25.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

xV

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

1

0.254

155.946

2.689E+00

1.522E+00



Multistage Cancer,
2-Degree

1

0.254

155.946

2.689E+00

1.522E+00

final fi=0

a Best-fitting model, BMDS output presented in this appendix

F.2.25.2. Output for Selected Model: Multistage Cancer, 1-Degree
Toth et al., 1979: Liver: Tumors

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\Canc\25 mscl IPerc adr cor lyr.(d)

Gnuplot Plotting File: C:\Canc\25 mscl IPerc adr cor lyr.pit

Thu Apr 01_13:10:25 2010

Table 1

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = Mean
Independent variable = Dose

Total number of observations = 3

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background =	0.240176

Beta (1) = 0.00374745

Asymptotic Correlation Matrix of Parameter Estimates
Background	Beta(1)

This document is a draft for review purposes only and does not constitute Agency policy.

F-157 DRAFT—DO NOT CITE OR QUOTE


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Background
Beta(1)

1	-0.53

-0.53	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0.2418	*	*	*

Beta(1)	0.00373791	*	*	*

Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-75.3127	3

Fitted model -75.9728 2	1.3201 1	0.2506

Reduced model -79.4897 1	8.35401 2	0.01534

AIC:	155.946

Goodness of Fit

Scaled

Dose Est. Prob. Expected Observed	Size	Residual

0.0000 0.2418 9.188 7.000	38	-0.829

1.0000 0.2446 10.764 13.000	44	0.784

100.0000 0.4783 21.044 21.000	44	-0.013

Chi ^2 = 1.30	d.f. = 1	P-value = 0.2537

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	2.68876

BMDL =	1.52183

BMDU =	7.54263

Taken together, (1.52183, 7.54263) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00657103

This document is a draft for review purposes only and does not constitute Agency policy.

F-158 DRAFT—DO NOT CITE OR QUOTE


-------
1 F.2.25.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	12:10 04/01 2010

3

4	Toth et al., 1979: Liver: Tumors

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-l59 DRAFT—DO NOT CITE OR QUOTE


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F.2.26. Delia Porta et al., 1987: Table 4, B6C3 mice, male, hepatocellular carcinoma
F.2.26.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

xV

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage Cancer,
1-Degree

1

0.073

164.110

9.255E+00

6.946E+00



Multistage
Cancer, 2-Degreea

1

0.899

160.823

7.359E+01

9.825E+00



a Best-fitting model, BMDS output presented in this appendix

F.2.26.2. Output for Selected Model: Multistage Cancer, 2-Degree
Delia Porta et al., 1987: Table 4, B6C3 mice, male, hepatocellular carcinoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\1\94_DPorta_l987_Male_Hep_Carc_MultiCanc2_l.(d)

Gnuplot Plotting File: C:\l\94_DPorta_1987_Male_Hep_Carc_MultiCanc2_l.plt

Fri Apr 02 13:58:02 2010

Table 4, B6C3 mice, Male, Hepatocellular carcinoma

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal*dose/Nl-beta2*dose/N2 ) ]

The parameter betas are restricted to be positive

Dependent variable = DichEff
Independent variable = Dose

Total number of observations = 3

Total number of records with missing values = 0
Total number of parameters in model = 3
Total number of specified parameters = 0
Degree of polynomial = 2

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background =	0.110507

Beta(1) =	0

Beta(2) = 1.88069e-006

Asymptotic Correlation Matrix of Parameter Estimates

This document is a draft for review purposes only and does not constitute Agency policy.

F-160 DRAFT—DO NOT CITE OR QUOTE


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63

64

( *** The model parameter(s) -Beta(l)

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

Background	Beta(2)

Background	1	-0.62

Beta(2)	-0.62	1

Parameter Estimates

95.0% Wald Confidence Interval

Variable Estimate Std. Err.	Lower Conf.	Limit Upper Conf. Limit

Background 0.114031 *	*	*

Beta(1) 0 *	*	*

Beta(2) 1.8559e-006 *	*	*

Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-78.4036	3

Fitted model -78.4116 2	0.0160146 1	0.8993

Reduced model -94.7394 1	32.6717 2	<.0001

AIC:	160.823

Goodness of Fit

Scaled

Dose Est. Prob. Expected Observed	Size	Residual

0.0000 0.1140 4.903 5.000	43	0.046

357.1429 0.3008 15.340 15.000	51	-0.104

714.2857 0.6563 32.815 33.000	50	0.055

Chi/N2 = 0.02	d.f. = 1	P-value = 0.8994

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	73.5891

BMDL =	9.82517

BMDU =	88.9247

Taken together, (9.82517, 88.9247) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00101779

This document is a draft for review purposes only and does not constitute Agency policy.

F-161 DRAFT—DO NOT CITE OR QUOTE


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1 F.2.26.3. Figure for Selected Model: Multistage Cancer, 2-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	12:58 04/02 2010

3

4	Delia Porta et al., 1987: Table 4, B6C3 mice, male, hepatocellular carcinoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-162 DRAFT—DO NOT CITE OR QUOTE


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F.2.27. Delia Porta et al., 1987: Table 4, B6C3 mice, female, hepatocellular adenoma
F.2.27.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

xV

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

1

0.468

99.355

3.695E+01

2.245E+01



Multistage Cancer,
2-Degree

0

NA

100.803

1.345E+02

2.353E+01



a Best-fitting model, BMDS output presented in this appendix

F.2.27.2. Output for Selected Model: Multistage Cancer, 1-Degree
Delia Porta et al., 1987: Table 4, B6C3 mice, female, hepatocellular adenoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\1\95_DPorta_l987_Female_Hep_Aden_MultiCancl_l.(d)

Gnuplot Plotting File: C:\l\95_DPorta_1987_Female_Hep_Aden_MultiCancl_l.plt

Fri Apr 02 13:58:32 2010

Table 4, B6C3 mice, Female, Hepatocellular adenoma

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = DichEff
Independent variable = Dose

Total number of observations = 3

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background = 0.0244051
Beta(1) = 0.000306055

Asymptotic Correlation Matrix of Parameter Estimates
Background	Beta(1)

This document is a draft for review purposes only and does not constitute Agency policy.

F-163 DRAFT—DO NOT CITE OR QUOTE


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Background
Beta(1)

1	-0.72

-0.72	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0.0369416	*	*	*

Beta(1)	0.000272012	*	*	*

Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-47.4015	3

Fitted model -47.6775 2	0.552146 1	0.4574

Reduced model -51.6367 1	8.47042 2	0.01448

AIC:	9 9.3551

Goodness of Fit

Scaled

Dose Est. Prob. Expected Observed	Size	Residual

0.0000 0.0369 1.810 2.000	49	0.144

357.1429 0.1261 5.296 4.000	42	-0.602

714.2857 0.2070 9.936 11.000	48	0.379

Chi ^2 = 0.53	d.f. = 1	P-value = 0.4677

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	36.94 82

BMDL =	22.4 477

BMDU =	8 6.1826

Taken together, (22.4477, 86.1826) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.000445481

This document is a draft for review purposes only and does not constitute Agency policy.

F-164 DRAFT—DO NOT CITE OR QUOTE


-------
1 F.2.27.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	12:58 04/02 2010

3

4	Delia Porta et al., 1987: Table 4, B6C3 mice, female, hepatocellular adenoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

F-165 DRAFT—DO NOT CITE OR QUOTE


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F.2.28. Delia Porta et al., 1987: Table 4, B6C3 mice, female, hepatocellular carcinoma
F.2.28.1. Summary Table of BMDS Modeling Results

Model

Degrees of
Freedom

xV

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

Multistage
Cancer, 1-Degreea

1

0.010

116.588

2.425E+01

1.605E+01



Multistage Cancer,
2-Degree

1

0.010

116.588

2.425E+01

1.605E+01

final fi=0

a Best-fitting model, BMDS output presented in this appendix

F.2.28.2. Output for Selected Model: Multistage Cancer, 1-Degree
Delia Porta et al., 1987: Table 4, B6C3 mice, female, hepatocellular carcinoma

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\1\96_DPorta_l987_Female_Hep_Carc_MultiCancl_l.(d)

Gnuplot Plotting File: C:\l\96_DPorta_1987_Female_Hep_Carc_MultiCancl_l.plt

Fri Apr 02 13:59:01 2010

Table 4, B6C3 mice, Female, Hepatocellular carcinoma

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(
-betal^dose^l)]

The parameter betas are restricted to be positive

Dependent variable = DichEff
Independent variable = Dose

Total number of observations = 3

Total number of records with missing values = 0
Total number of parameters in model = 2
Total number of specified parameters = 0
Degree of polynomial = 1

Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

Background = 0.0903848
Beta(1) = 0.000261828

Asymptotic Correlation Matrix of Parameter Estimates
Background	Beta(1)

This document is a draft for review purposes only and does not constitute Agency policy.

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Background
Beta(1)

1	-0.8

-0.8	1

Parameter Estimates

95.0% Wald Confidence Interval
Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf. Limit

Background	0.0300271	*	*	*

Beta(1)	0.000414523	*	*	*

Indicates that this value is not calculated.

Analysis of Deviance	Table

Model Log(likelihood) # Param's	Deviance Test d.f. P-value

Full model	-53.1726	3

Fitted model -56.2941 2	6.24292 1	0.01247

Reduced model -60.7146 1	15.084 2	0.0005303

AIC:	116.588

Goodness of Fit

Scaled

Dose Est. Prob. Expected Observed	Size	Residual

0.0000 0.0300 1.471 1.000	49	-0.395

357.1429 0.1635 6.867 12.000	42	2.142

714.2857 0.2786 13.373 9.000	48	-1.408

Chi/N2 = 6.72	d.f. = 1	P-value = 0.0095

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	24.2455

BMDL =	16.0512

BMDU =	4 9.7176

Taken together, (16.0512, 49.7176) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.000623007

This document is a draft for review purposes only and does not constitute Agency policy.

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1 F.2.28.3. Figure for Selected Model: Multistage Cancer, 1-Degree

Multistage Cancer Model with 0.95 Confidence Level

dose

2	12:59 04/02 2010

3

4	Delia Porta et al., 1987: Table 4, B6C3 mice, female, hepatocellular carcinoma

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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F.3. REFERENCES

1	Delia Porta G; Dragani TA; Sozzi D; Sozzi G. (1978) Carcinogenic effects of infantile and long-term 2,3,7,8-

2	tetrachlorodibenzo-p-dioxin treatment in the mouse. Tumori 73: 99-107.

3	Goodman, DG; Sauer, RM. (1992) Hepatotoxicity and carcinogenicity in female Sprague-Dawley rats treated with

4	2,3,7,8-tetrachlorordibenzo-p-dioxin (TCDD): a Pathology Working Group reevaluation. Regul Toxicol Pharmacol

5	15:245-252.

6	Kociba, RJ; Keyes, DG; Beyer, JE; et al. (1978) Results of a two-year chronic toxicity and oncogenicity study of

7	2,3,7,8-tetrachlorodibenzo-p-dioxin in rats. Toxicol Appl Pharmacol 46(2):279-303.

8	NTP (National Toxicology Program). (1982) Bioassay of 2,3,7,8-tetrachlorodibenzo-p-dioxin for possible

9	carcinogenicity (gavage study). Tech. Rept. Ser. No. 201. U.S. Department of Health and Human Services, Public

10	Health Service, Research Triangle Park, NC.

11	NTP (National Toxicology Program). (2006) NTP technical report on the toxicology and carcinogenesis studies of

12	2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) (CAS No. 1746-01-6) in female Harlan Sprague-Dawley rats (Gavage

13	Studies). Natl Toxicol ProgramTech Rep 521. Public Health Service, National Institute of Health, U.S. Department

14	of Health and Human Services, Research Triangle Park, NC.

15	Toth, KJ; Sugar, S; Somfai-Relle S; et al. (1978) Carcinogenic bioassay of the herbicide 2,4,5-trichlorphenoxy

16	ethanol (TCPE) with Swiss mice. Prog Biochem Pharmacol 14:82-93.

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DRAFT

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External Review Draft

APPENDIX G

Endpoints Excluded From Reference Dose
Derivation Based on Toxicological Relevance

NOTICE

THIS DOCUMENT IS AN EXTERNAL REVIEW DRAFT. It has not been formally released
by the U.S. Environmental Protection Agency and should not at this stage be construed to
represent Agency policy. It is being circulated for comment on its technical accuracy and policy
implications.

National Center for Environmental Assessment
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, OH


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1	APPENDIX G. ENDPOINTS EXCLUDED FROM REFERENCE DOSE DERIVATION

2	BASED ON TOXICOLOGICAL RELEVANCE

3

4

5	The National Academy of Sciences (NAS) committee commented on the low dose model

6	predictions and the need to discuss the biological significance of the noncancer health effects

7	modeled in the 2003 Reassessment. In selecting point of departure (POD) candidates from the

8	animal bioassays for derivation of the reference dose (RfD), U.S. Environmental Protection

9	Agency (EPA) had to consider the toxicological relevance of the identified endpoint(s) from any

10	given study. Often endpoints/effects may be sensitive, but lack general toxicological

11	significance due to not being clearly adverse (defined in the Integrated Risk Information System

12	(IRIS) glossary as a biochemical change, functional impairment, or pathologic lesion that affects

13	the performance of the whole organism, or reduces an organism's ability to respond to an

14	additional environmental challenge), being an adaptive response, or not being clearly linked to

15	downstream functional or pathological alterations. It is standard EPA RfD derivation policy not

16	to base a reference value on endpoints that are not adverse or not obvious precursors to an

17	adverse effect. For select studies, a rationale for lack of toxicological relevance of particular

18	endpoints reported is listed here. These endpoints were not considered for derivation of the RfD.

19	Kitchin and Woods (1979) administered female Sprague-Dawley rats a single gavage

20	dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and measured cytochrome P450 levels and

21	benzo(a)pyrene hydroxylase (BPH) activity as a marker of hepatic microsomal cytochrome

22	P448-mediated enzyme activity. They found a statistically significant increase in BPH at doses

23	>2 ng/kg and a significant increase in cytochrome P450 levels at doses >600 ng/kg. Aryl

24	hydrocarbon hydrolase and EROD were both significantly increased 3 months after exposure;

25	however the elevation did not maintain statistical significance at 6 months. No other indicators

26	of hepatic effects were analyzed. CYP induction alone is not considered a significant

27	toxicologically adverse effect given that CYPs are induced as a means of hepatic processing of

28	xenobiotic agents. Additionally, the role of CYP induction in hepatotoxicity and carcinogenicity

29	of TCDD is unknown, and CYP induction is not considered a relevant POD without obvious

30	pathological significance.

31	In multiple studies by Hassoun et al. (1998, 2000, 2002, 2003), various indicators of

32	oxidative stress were measured in hepatic and brain tissue of female B6C3F1 mice and Sprague-

This document is a draft for review purposes only and does not constitute Agency policy.

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Dawley rats following 13 or 30 weeks of TCDD gavage dosing (5 days a week). Biomarkers for
oxidative stress included production superoxide anion, lipid peroxidation, and DNA single-strand
breaks. The authors report a statistically significant effect on several oxidative stress markers as
a result of TCDD exposure, the lowest dose producing an effect being 0.32 ng/kg-day (Hassoun
et al., 1998). In this study, all oxidative stress markers were significantly effected, but no other
indicators of brain pathology were assessed. Thus, it is impracticable to link the markers of
oxidative stress to a toxicological outcome in the brain, and this study and its endpoints are not
considered relevant POD candidates.

Burleson et al. (1996) analyzed the effect of a TCDD on viral host resistance following a
single gavage dose of TCDD by measuring mortality mediated by influenza virus challenge in
B6C3F1 female mice. The study authors found that TCDD at >10 ng/kg-day increased
influenza-induced mortality. The experimental design calls for a 30% mortality in untreated
animals (15% was achieved); mortality, itself, is not a direct result of TCDD exposure. None of
the other immunologically-relevant measures were affected by TCDD treatment in this study,
and no other effects were reported. The interpretation of these results with respect to humans is
problematic. Furthermore, the findings were not reproduced by Nohara et al. (2002) using the
same experimental design (see Section 2.4.2). Therefore, this endpoint is not considered relevant
as a POD candidate.

To examine the central nervous system response to TCDD, Kuchiiwa et al (2002)
analyzed the effect of in utero and lactational TCDD exposure on the serotonergic system in the
brainstem of male ddY mice. Female mice were administered TCDD by oral gavage once a
week for 8 weeks prior to pregnancy and, using an immunocytochemical detection method, the
raphe nuclei in the brainstem of male offspring was monitored for serotogergic neurons. TCDD
at 0.7 ng/kg-day caused a 25—50% reduction in the immunostaining of serotonin, however there
were no differences in external morphology, birth or postnatal body weights between
TCDD-exposed and control offspring. The authors suggest that these findings may indicate that
TCDD acts as a neuroteratogen by mediating long-term alterations in neuronal serotonin
synthesis and serotonergic function. However, no other relevant neurotoxicity endpoints were
examined or reported. Thus, reduced serotonin is not an adverse endpoint of toxicological
significance in and of itself, and this study is deemed unsuitable as a POD candidate.

This document is a draft for review purposes only and does not constitute Agency policy.

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Mally and Chipman (2002) evaluated the effect of TCDD on gap junctions,
hypothesizing that as a nongenotoxic carcinogen, TCDD may induce tumor formation by
disturbing tissue homeostasis. Female F344 rats were dosed with TCDD by oral gavage for
either 3 consecutive days or 2 days a week for 28 days. Gap junction connexin (Cx) plaque
expression and hepatocyte proliferation was measured. The study authors report a decrease in
Cx32 plaque number and area in the liver of rats exposed to 0.7 ng/kg-day and higher, however
they did not find an associated increase in hepatocyte proliferation. No clinical signs of toxicity
were observed, and histological examination of the liver revealed no abnormalities. In the
absence of additional indicators of hepatotoxicity, a decrease in Cx32 plaque formation is not
clearly linked to TCDD-mediated hepatotoxicity or hepatocarcinogenicty, nor is it considered an
adverse effect. This endpoint is not considered a toxicologically relevant POD.

Vanden Heuvel et al. (1994) analyzed changes in hepatic mRNA following a single
administration of TCDD to female Sprague-Dawley rats by oral gavage. Four days after
treatment, animals were sacrificed and livers were excised. Using reverse transcriptase-
polymerase chain reaction (RT-PCR) on hepatic RNA, they compared levels of "dioxin
responsive" mRNA's (CYP1A1, UDP-glucuronosyltransferase I, plasminogen activator inhibitor
2, and transforming growth factor a) at various doses of TCDD and at control (baseline) levels.
They determined that CYP1 Al elicited the most sensitive response to TCDD, with a statistically
significant increase (3-fold) in mRNA from rat livers exposed to 1 ng/kg-day TCDD. Induction
of CYP1 Al expression is not considered an adverse effect, as the role of CYP1 Al in
TCDD-mediated carcinogenicity is unsettled. Therefore, in the absence of other indicators of
hepatoxicity, increases in liver CYP1 Al cannot be considered toxicologically relevant for a POD
candidate.

Devito et al. (1994) assessed the activity of CYP1A1 and CYP1A2, the amount of
phosphorylation of phosphotyrosyl proteins (pp32, pp34, and pp38), and the levels of estrogen
receptor in the liver, uterus, lung and skin tissue of female B6C3F1 mice administered TCDD for
5 days a week for 13 weeks. The authors hypothesized that these measurements may be
sensitive biomarkers for exposure to TCDD. Body weights were also recorded weekly.

Induction of CY1A1 and CYP1A2, as well as increased phosphorylated forms of pp32, pp34,
and pp38 were sensitive indicators of TCDD exposure, with statistically significant changes seen

at 1.07 ng/kg-day. EROD activity in the ling, skin, and liver was also observed with significant

This document is a draft for review purposes only and does not constitute Agency policy.

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increases at this dose. However, the authors did not find a change in rat body or terminal organ
weights, nor did they note any pathology in the animals at this dose level. The role of CYPs and
phosphorylated pp32, pp34, and pp38 in TCDD-mediated toxicity is unknown, and changes in
the activity or function of these proteins are not considered adverse. Therefore, these endpoints
are not considered suitable as PODs.

Because TCDD had been detected in the soil of contaminated locations, determining the
bioavailability of TCDD from ingested soil may be important to the calculation of safe exposure
levels. Lucier et al. (1986) fed adult female Sprague-Dawley rats TCDD contaminated soil or
gave them TCDD in corn oil at various doses and compared the effects of TCDD on biochemical
parameters from liver tissue. They found that equivalent doses of TCDD in corn oil and soil
produced similar increases in hepatic aryl hydrocarbon hydroxylase activity (AHH) and UDP
glucuronyltransferase activity. They determined that AHH was statistically induced 1.8-fold at
15 ng/kg in corn oil and 40 ng/kg in soil. Cytochrome P450 was significantly increased at higher
doses. No clinical signs of acute toxicity or changes in body weight were observed. The
association between AHH activity and TCDD-mediated hepatotoxicity is unknown and no
adverse endpoints were measured. Thus, this endpoint is not suitable as a POD candidate.

Sugita-Konishi et al. (2003) investigated the change in host resistance of mice offspring
lactationally exposed to TCDD. Pregnant C57BL/6NCji mice were administered TCDD via
drinking water from parturition to weaning of the offspring (17 days). One group of offspring
was then infected with Listeria monocytogenes and blood and spleen samples were collected
various time points post infection. Uninfected, TCDD exposed offspring were weighed and their
spleens and thymuses removed for assay of cellular content and protein expression. TCDD
exposure caused a statistically-significant decrease in relative spleen weight and a statistically-
significant increase in thymic CD4+ cells in the high-dose group (11.3 ng/kg-day). Offspring
infected with Listeria following TCDD exposure exhibited a statistically significant increase in
serum tumor necrosis factor alpha (TNF-a) 2 days after infection in both sexes in the low-
(1.14 ng/kg-day) and high-dose groups. The authors conclude that exposure to TCDD disrupted
the host resistance of the offspring at the lowest dose tested, despite the primary immune
parameters being unaffected. Without an obvious association between TCDD and immune
function, however, this endpoint is not suitable for identification of a LOAEL. Thus, the

LOAEL for this study is 11.3 ng/kg-day, and the NOAEL is 1.14 ng/kg-day.

This document is a draft for review purposes only and does not constitute Agency policy.

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1	Sewall et al. (1993) investigated alterations in the epidermal growth factor receptor

2	(EGFR) pathway in a two-stage initiation promotion model of TCDD hepatic cancer. EGFR

3	signaling has been implicated in the altered cell growth induction by tumor promoters. Female

4	Sprague-Dawley rats were administered TCDD biweekly by oral gavage for 30 weeks following

5	initiation by a single dose of diethylnitrosamine (DEN). A group also received TCDD without

6	prior DEN initiation. Livers were harvested and fixed from sacrificed animals and sections

7	tested for EGFR binding, autophosphorylation, immunolocalization, and hepatic cell

8	proliferation. The authors report a significant dose-dependent decrease in plasma membrane

9	EGFR maximum binding capacity in TCDD-exposed rats beginning at 3.5 ng/kg-day. However,

10	at this same dose, the authors note a statistically significant decrease in cell proliferation (as

11	measured by DNA replication labeling), with increases in proliferation only occurring at higher

12	doses (125 ng/kg-day). No other indicators of hepatic toxicity or tumorigenicity were assessed.

13	The role of EGFR in TCDD-mediated hepatotoxicity and hepatocarcinogenicity is unknown, and

14	as such, this endpoint cannot be unequivocally linked to TCDD-induced hepatic effects nor

15	labeled as adverse. Thus, it is not suitable as a POD candidate.

16

17	G.l. REFERENCES

18	Burleson, GR; Lebrec, H; Yang, YG; et al. (1996) Effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on

19	influenza virus host resistance in mice. Fund Appl Toxicol 29:40-47.

20	Devito, MJ; Ma, X; Babish, JG; et al. (1994) Dose-response relationships in mice following subchronic exposure to

21	2,3,7,8-tetrachlorodibenzo-p-dioxin: CYP1A1, CYP1A2, estrogen receptor, and protein tyrosine phosphoylation.

22	Toxicol Appl Pharmacol 124:82-90.

23	Hassoun, EA; Wilt, SC; DeVito, MJ; et al. (1998) Induction of oxidative stress in brain tissues of mice after

24	subchronic exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin. Toxicol Sci 42:23-27.

25	Hassoun, EA; Li, F; Abushaban, A; et al. (2000) The relative abilities of TCDD and its congeners to induce

26	oxidative stress in the hepatic and brain tissues of rats after subchronic exposure. Toxicology 145:103-113.

27	Hassoun, EA; Wang, H; Abushaban, A. (2002) Induction of oxidative stress following chronic exposure to TCDD,

28	2,3,4,7,8-pentachlorodibenzofuran, and 2,3 ',4,4',5-pentachlorobiphenyl. J Toxicol Environ Health A 65:825-842.

29	Hassoun, EA; Al-Ghafri, M; Abushaban, A. (2003) The role of antioxidant enzymes in TCDD-induced oxidative

30	stress in various brain regions of rats after subchronic exposure. Free Rad Biol Medicine 35(9): 1028-1036.

31	Kitchin, KT; Woods, JS. (1979) 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) effects on hepatic microsomal

32	cytochrome P-448-mediated enzyme activities. Toxicol Appl Pharmacol 47:537-546.

This document is a draft for review purposes only and does not constitute Agency policy.

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1	Kuchiiwa, S; Cheng, S-B; Nagatomo, I; et al. (2002) In utero and lactational exposure to 2,3,7,8-tetrachlorodibenso-

2	/j-dioxin decreases serotonin-immunoreactive neurons in raphe nuclei of male mouse offspring. Neurosci Lett

3	317:73-76.

4	Lucier, GW; Rumbaugh, RC; McCoy, Z; et al. (1986) Ingestion of soil contaminated with 2,3,7,8-tetrachloro-

5	dibenzo-p-dioxin (TCDD) alters hepatic enzyme activities in rats. Fund Appl Toxicol 6:364-371.

6	Mally, A; Chipman, JK. (2002) Non-genotoxic carcinogens: early effects on gap junctions, cell proliferation and

7	apoptosis in the rat. Toxicology 180:233-248.

8	Nohara, K; Izumi, H; Tamura, S; et al. (2002) Effect of low-dose 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on

9	influenza A virus-induced mortality in mice. Toxicology 170:131-138.

10	Sewall, CH; Lucier, GW; Tritscher, AM; et al. (1993) TCDD-mediated changes in hepatic epidermal growth factor

11	receptor may be a critical event in the hepatocarcinogenic action of TCDD. Carcinogenesis 14:1885-1893.

12	Sugita-Konishi, Y; Kobayashi, K; Naito, H; et al. (2003) Effect of lactational exposure to 2,3,7,8-

13	tetrachlorodibenzo-p-dioxin on the susceptibility to Listeria infection. Biosci Biotechnol Biochem 67(l):89-93.

14	U.S. EPA. (2003) Exposure and human health reassessment of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and

15	related compounds [NAS review draft]. Volumes 1-3. National Center for Environmental Assessment, Washington,

16	DC; EPA/600/P-00/001 Cb. Available at: http://www.epa.gov/nceawwwl/pdfs/dioxin/nas-review/.

17	Vanden Heuvel, JP; Clark, GC; Tritscher, A; et al. (1994) Accumulation of polychlorinated dibenzo-p-dioxins and

18	dibenzofurans in liver of control laboratory rats. Fundam Appl Toxicol 23:465-469.

19

This document is a draft for review purposes only and does not constitute Agency policy.

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DRAFT

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May 2010
External Review Draft

APPENDIX H
Cancer Precursor Benchmark Dose Modeling

NOTICE

THIS DOCUMENT IS AN EXTERNAL REVIEW DRAFT. It has not been formally released
by the U.S. Environmental Protection Agency and should not at this stage be construed to
represent Agency policy. It is being circulated for comment on its technical accuracy and policy
implications.

National Center for Environmental Assessment
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, OH


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CONTENTS—APPENDIX H: Cancer Precursor Benchmark Dose Modeling

APPENDIX H. CANCER PRECURSOR BENCHMARK DOSE MODELING	H-1

II I. BMDS INPUT TABLES	II-l

H. 1.1. Hassoun et al. (2000)	II-l

11.1.2.	Kitchin and Woods (1979)	II-l

H. 1.3. National Toxicology Program (2006), 31 Week Exposure	H-2

H. 1.4. National Toxicology Program (2006), 53 Week Exposure	H-2

H. 1.5. Vanden Heuvel et al. (1994)	H-2

II.2. ALTERNATE DOSE: WHOLE BLOOD BMDS RESULTS	11-3

H.2.1. Hassoun et al., 2000: Cytochrome C Reductase	H-3

H.2.1.1. Summary Table of BMDS Modeling Results	H-3

H.2.1.2. Output for Selected Model: Exponential (M5)	H-3

H.2.1.3. Figure for Selected Model: Exponential (M5)	H-6

H.2.2. Hassoun et al., 2000: DNA Single-Strand Breaks	H-7

H.2.2.1. Summary Table of BMDS Modeling Results	H-7

H.2.2.2. Output for Selected Model: Exponential (M4)	H-7

H.2.2.3. Figure for Selected Model: Exponential (M4)	H-10

H.2.2.4. Output for Additional Model Presented: Power, Unrestricted	H-l 1

H.2.2.5. Figure for Additional Model Presented: Power, Unrestricted	H-l3

11.2.3.	Hassoun et al., 2000: TBARS	11-14

H.2.3.1. Summary Table of BMDS Modeling Results	H-14

H.2.3.2. Output for Selected Model: Hill	H-14

H.2.3.3. Figure for Selected Model: Hill	H-17

H.2.4. Kitchin and Woods, 1979: Bap Hydroxylase Activity	H-18

H.2.4.1. Summary Table of BMDS Modeling Results	H-18

H.2.4.2. Output for Selected Model: Exponential (M5)	H-18

H.2.4.3. Figure for Selected Model: Exponential (M5)	H-21

H.2.5. National Toxicology Program, 2006: Liver EROD 53 Weeks	H-22

H.2.5.1. Summary Table of BMDS Modeling Results	H-22

H.2.5.2. Output for Selected Model: Hill	H-22

H.2.5.3. Figure for Selected Model: Hill	H-25

H.2.6. National Toxicology Program, 2006: Lung Erod 53 Weeks	H-26

H.2.6.1. Summary Table of BMDS Modeling Results	H-26

H.2.6.2. Output for Selected Model: Exponential (M4)	H-26

H.2.6.3. Figure for Selected Model: Exponential (M4)	H-29

H.2.6.4. Output for Additional Model Presented: Power, Unrestricted	H-30

H.2.6.5. Figure for Additional Model Presented: Power, Unrestricted	H-32

H.2.7. National Toxicology Program, 2006: Labeling Index 31 Weeks	H-33

H.2.7.1. Summary Table of BMDS Modeling Results	H-33

H.2.7.2. Output for Selected Model: Polynomial, 5-degree	H-33

H.2.7.3. Figure for Selected Model: Polynomial, 5-degree	H-36

H.2.8. Vanden Heuvel et al., 1994: Hepatic CYP1 Al Mrna Expression	H-37

H.2.8.1. Summary Table of BMDS Modeling Results	H-37

H.2.8.2. Output for Selected Model: Hill	H-37

This document is a draft for review purposes only and does not constitute Agency policy.

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CONTENTS (continued)

H.2.8.3. Figure for Selected Model: Hill	H-40

11.3. ADMINISTERED DOSE BMDS RESULTS	11-41

H.3.1. Hassoun et al., 2000: Cytochrome C Reductase	H-41

H.3.1.1. Summary Table of BMDS Modeling Results	H-41

H.3.1.2. Output for Selected Model: Exponential (M4)	H-41

H.3.1.3. Figure for Selected Model: Exponential (M4)	H-44

H.3.1.4. Output for Additional Model Presented: Power, Unrestricted	H-44

H.3.1.5. Figure for Additional Model Presented: Power, Unrestricted	H-47

H.3.2. Hassoun et al., 2000: DNA Single-Strand Breaks	H-48

H.3.2.1. Summary Table of BMDS Modeling Results	H-48

H.3.2.2. Output for Selected Model: Hill	H-48

H.3.2.3. Figure for Selected Model: Hill	H-51

H.3.2.4. Output for Additional Model Presented: Hill, Unrestricted	H-51

H.3.2.5. Figure for Additional Model Presented: Hill, Unrestricted	H-54

H.3.3. Hassoun et al., 2000: TBARS	11-55

H.3.3.1. Summary Table of BMDS Modeling Results	H-55

H.3.3.2. Output for Selected Model: Exponential (M4)	H-55

H.3.3.3. Figure for Selected Model: Exponential (M4)	H-58

H.3.3.4. Output for Additional Model Presented: Power, Unrestricted	H-58

H.3.3.5. Figure for Additional Model Presented: Power, Unrestricted	H-61

H.3.4. Kitchin and Woods, 1979: Bap Hydroxylase Activity	H-62

H.3.4.1. Summary Table of BMDS Modeling Results	H-62

H.3.4.2. Output for Selected Model: Exponential (M5)	H-62

H.3.4.3. Figure for Selected Model: Exponential (M5)	H-65

H.3.5. National Toxicology Program, 2006: Liver EROD 53 Weeks	H-66

H.3.5.1. Summary Table of BMDS Modeling Results	H-66

H.3.5.2. Output for Selected Model: Hill	H-66

H.3.5.3. Figure for Selected Model: Hill	H-69

H.3.6. National Toxicology Program, 2006: Lung Erod 53 Weeks	H-70

H.3.6.1. Summary Table of BMDS Modeling Results	H-70

H.3.6.2. Output for Selected Model: Exponential (M4)	H-70

H.3.6.3. Figure for Selected Model: Exponential (M4)	H-73

H.3.6.4. Output for Additional Model Presented: Power, Unrestricted	H-73

H.3.6.5. Figure for Additional Model Presented: Power, Unrestricted	H-76

H.3.7. National Toxicology Program, 2006: Labeling Index 31 Weeks	H-77

H.3.7.1. Summary Table of BMDS Modeling Results	H-77

H.3.7.2. Output for Selected Model: Exponential (M2)	H-77

H.3.7.3. Figure for Selected Model: Exponential (M2)	H-80

H.3.8. Vanden Heuvel et al., 1994: Hepatic CYP1A1 Mrna Expression	H-81

H.3.8.1. Summary Table of BMDS Modeling Results	H-81

H.3.8.2. Output for Selected Model: Hill	H-81

H.3.8.3. Figure for Selected Model: Exponential (M5)	H-84

This document is a draft for review purposes only and does not constitute Agency policy.

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1	APPENDIX H. CANCER PRECURSOR BENCHMARK DOSE MODELING

2

3

4	H.l. BMDS INPUT TABLES

5	H.l.l. Hassoun et al. (2000)

Endpoint

Administered Dose (ng/kg-day)

0

3

10

22

46

100

Internal Dose (ng/kg blood) 11

0

1.94

4.61

8.15

14.01

25.34

n = 6

n = 6

n = 6

n = 6

n = 6

n = 6

Cytochrome C reductase d

0.15 ±0.07

0.18 ± 0.05b

0.19 ±0.06

0.27 ± 0.06c

0.39 ± 0.06c

0.44 ± 0.11c

DNA single-strand breaks f

7.41 ± 1.54

10.78 ± 1.25 b-c

13.6 ± 1.69c

15.3 ± 1.71c

20.4 ± 2.25c

23.5 ± 1.37c

TBARs e

1.47 ±0.29

1.55 ± 0.54b

2.15 ± 0.36c

2.28 ± 0.25c

2.62 ± 0.52c

2.29 ± 0.49c

aFrom the Emond PBPK model described in 3.3.
bLOEL for selected endpoint.

Statistically significant as compared to control (p < 0.05).
dValues are the mean ± SD. Data obtained from Table 1 in Hassoun et al. 2000.
"Values are the mean ± SD. Data obtained from Table 2 in Hassoun et al. 2000.
Values are the mean ± SD. Data obtained from Table 3 in Hassoun et al. 2000.

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7

8	H.1.2. Kitchin and Woods (1979)

Endpoint

Administered Dose (ng/kg-day)

0

0.6

2

4

20

60

Internal Dose (ng/kg blood) a

0

0.06

0.20

0.38

1.61

4.15

n = 9

n = 4

n = 4

n = 4

n = 4

n = 4

BaP hydroxylase activity'
(continued on next line)

4.9 ±0.37

4.9 ± 0.59b

6.7 ± 0.70c'd

7.2 ± 0.90 d

8.3 ± 0.13 e

14 ± 2.5e

Endpoint

Administered Dose (ng/kg-day)

200

600

2000

5000

20,000



Internal Dose (ng/kg blood) a

11.59

30.26

90.90

218.02

863.18



n = 4

n = 4

n = 4

n = 4

n = 4



BaP hydroxylase activity'
(continued)

59 ± 3.4e

96 ± 23e

155 ± 8.2e

182 ± 13e

189 ±13e



aFrom the Emond PBPK model described in 3.3.

^NOEL for selected endpoint.

°LOEL for selected endpoint.

Statistically significant as compared to control (p < 0.05).

"Statistically significant as compared to control (p < 0.001).

Values are the mean ± SE. Data obtained from Table 3 in Kitchin and Woods 1979.

This document is a draft for review purposes only and does not constitute Agency policy.

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1 H.1.3. National Toxicology Program (2006), 31 Week Exposure



Administered Dose (ng/kg-day)



0

2.14

7.14

15.7

32.9

71.4



Internal Dose (ng/kg blood) a



0

2.33

5.32

9.21

15.66

28.13

Endpoint

n = 9

n = 10

n = 10

n = 10

n = 10

n = 10

Labeling Index ,week 31 c

0.33 ±0.0.06

0.85 ±0.21 b

0.96 ± 0.23 b

0.79 ± 0.15 b

1.33 ± 0.36b

3.85 ± 0.97b

aFrom the Emond PBPK model described in 3.3.

Statistically significant as compared to control (p < 0.05).

°Values are the mean ± SE. Data obtained from Table 11 in NTP 2006.

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3

4	H.1.4. National Toxicology Program (2006), 53 Week Exposure

Endpoint

Administered Dose (ng/kg-day)

0

2.14

7.14

15.7

32.9

71.4

Internal Dose (ng/kg blood) a

0.00

2.46

5.53

9.54

16.18

29.04

n = 8

n = 8

n = 8

n = 8

n = 8

n = 8

Liver EROD, week 53 c

30.22 ± 1.59

569.38 ±
24.62 b

1280.00 ±
95.30b

1551.16 ±
112.36 b

1726.81 ±
107.58b

1871.47 ±
109.14 b

Lung EROD, week 53 c

3.01 ±0.56

27.15 ± 1.87b

42.85 ± 3.94b

36.57 ±4.59b

43.75 ±6.56b

43.71 ±2.24 b

aFrom the Emond PBPK model described in 3.3.

Statistically significant as compared to control (p < 0.01).

°Values are the mean ± SE. Data obtained from Table 12 in NTP 2006.

5

6	H.1.5. Vanden Heuvel et al. (1994)

Endpoint

Administered Dose (ng/kg-day)

0

0.1

1

10

100

1,000

10,000

Internal Dose (ng/kg blood) a

0.00

0.01

0.11

0.88

6.45

48.32

434.50

n = 13

n = 5

n= 12

n = 7

n = 7

n = 11

n = 5

Hepatic CYP1A1
mRNA Expressionc

5.4 ± 1.0

7.2 ±2.5

14.8±4.3b

12.8 ± 1.7b

536± 121b

18000 ±4590

b

36700 ± 9900

b

aFrom the Emond PBPK model described in 3.3.

Statistically significant as compared to control (p < 0.05).

°Values are the mean ± SE. Data obtained from Table 2 in vanden Heuvel 1994.

7

This document is a draft for review purposes only and does not constitute Agency policy.

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H.2. ALTERNATE DOSE: WHOLE BLOOD BMDS RESULTS

H.2.1.	Hassoun et al., 2000: Cytochrome C Reductase

I.2.1.1.	Summary Table of BMDS Modeling Results	

Model3

Degrees
of

Freedom

x'/'-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential (M2)

4

0.016

-143.333

9.274E+00

7.737E+00



exponential (M3)

4

0.016

-143.333

9.274E+00

7.737E+00

power hit bound (d = 1)

exponential (M4)

3

0.339

-150.139

3.364E+00

2.170E+00



exponential

(M5)b

2

0.788

-151.027

5.913E+00

3.102E+00



Hill

2

0.743

-150.910

6.208E+00

3.190E+00



linear

4

0.170

-149.086

5.613E+00

4.429E+00



polynomial, 5-
degree

4

0.170

-149.086

5.613E+00

4.429E+00



power

4

0.170

-149.086

5.613E+00

4.429E+00

power bound hit (power =1)

a Constant variance model selected (p = 0.3871)
b Best-fitting model, BMDS output presented in this appendix

H.2.1.2. Output for Selected Model: Exponential (M5)

Hassoun et al., 2000: Cytochrome C reductase

Exponential Model. (Version: 1.61;

Date: 7/24/2009)

Input Data File: C:\5\Blood\17 Has

2000 CytCLiv ExpCV 1.(d)

Gnuplot Plotting File:





Fri Apr 30 14:14:

TBARs, liver only (Table 2)

The form of the response function by Model:

Model 2:	Y[dose] = a * exp{sign * b * dose}

Model 3:	Y[dose] = a * exp{sign * (b * dosej^d}

Model 4:	Y[dose] = a * [c-(c-l) * exp{-b * dose}]

Model 5:	Y[dose] = a * [c-(c-l) * exp{-(b * dosej^d}]

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;
sign = -1 for decreasing trend.

Model 2 is nested within Models 3 and 4.

Model 3 is nested within Model 5.

Model 4 is nested within Model 5.

Dependent variable = Mean

This document is a draft for review purposes only and does not constitute Agency policy.

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Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))
rho is set to 0.

A constant variance model is fit.

Total number of dose groups = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values

Variable

Model 5

lnalpha

rho(S)

-5.48625

0

0.1387
0.0225296
6.40231

1

(S)

Specified

Parameter Estimates

Variable

lnalpha
rho

Model 5

-5.47298
0

0.156024
0. 0891513
2.85355
2 .14235

Table of Stats From Input Data

Obs Mean

Obs Std Dev

0 6

0

146

0.06614

1.938 6

0

177

0.05389

4.614 6

0

191

0.05634

8.147 6

0

271

0.05634

14.01 6

0

388

0.06369

25.34 6

0

444

0.1102

Dose

Estimated Values of Interest
Est Mean	Est Std	Scaled Residual

0

0.156

0

0648

-0.3789

1. 938

0.1627

0

0648

0.5416

4 . 614

0.1961

0

0648

-0.1919

8 .147

0.2705

0

0648

0. 01769

14 . 01

0.3874

0

0648

0.02224

25.34

0.4443

0

0648

-0.0107

Other models for which likelihoods are calculated:

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

This document is a draft for review purposes only and does not constitute Agency policy.

H-4 DRAFT—DO NOT CITE OR QUOTE


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Model A2 :	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma(i)^2

Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= exp(lalpha + log(mean(i)) * rho)

Model R:	Yij	= Mu + e(i)

Var{e(ij)}	= Sigma/'2

Likelihoods of Interest

Model	Log(likelihood)	DF	AIC

A1	80.75258	7	-147.5052

A2	83.37355	12	-142.7471

A3	80.75258	7	-147.5052

R	55.82002	2	-107.64

5	80.51364	5	-151.0273

Additive constant for all log-likelihoods =	-33.08. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Test 1: Does response and/or variances differ among Dose levels? (A2 vs. R)

Test 2: Are Variances Homogeneous? (A2 vs. A1)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 7a: Does Model 5 fit the data? (A3 vs 5)

Test

Test 1
Test 2
Test 3
Test 7a

Tests of Interest

-2*log(Likelihood Ratio)

55.11
5.242
5.242
0.4779

10

5
5
2

p-value

< 0.0001
0.3871
0.3871
0.7875

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose
levels, it seems appropriate to model the data.

The p-value for Test 2 is greater than .1. A homogeneous
variance model appears to be appropriate here.

The p-value for Test 3 is greater than .1. The modeled
variance appears to be appropriate here.

The p-value for Test 7a is greater than .1. Model 5 seems
to adeguately describe the data.

Benchmark Dose Computations:

Specified Effect = 1.000000

Risk Type = Estimated standard deviations from control

Confidence Level = 0.950000

BMD =	5.91298

BMDL =	3.10234

This document is a draft for review purposes only and does not constitute Agency policy.

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1 H.2.1.3. Figure for Selected Model: Exponential (M5)

Exponential Model 5 with 0.95 Confidence Level

dose

2	14:14 04/30 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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H.2.2.	Hassoun et al., 2000: DNA Single-Strand Breaks

I.2.2.1.	Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

x2p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential (M2)

4

<0.0001

111.134

6.551E+00

5.472E+00



exponential (M3)

4

<0.0001

111.134

6.551E+00

5.472E+00

power hit bound (d = 1)

exponential
(M4)b

3

0.231

78.588

1.207E+00

9.165E-01



exponential (M5)

3

0.231

78.588

1.207E+00

9.165E-01

power hit bound (d = 1)

Hill

3

0.230

78.590

1.097E+00

7.966E-01

n lower bound hit (n = 1)

linear

4

<0001

97.616

3.552E+00

2.890E+00



polynomial, 5-
degree

4

<0001

97.616

3.552E+00

2.890E+00



power

4

<0001

97.616

3.552E+00

2.890E+00

power bound hit (power =1)

power,
unrestricted0

3

0.132

79.893

4.522E-01

2.027E-01

unrestricted (power = 0.576)

a Constant variance model selected (p = 0.7521)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

H.2.2.2. Output for Selected Model: Exponential (M4)

Hassoun et al., 2000: DNA single-strand breaks

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\5\Blood\18_Has_20 0 0_SSB_ExpCV_l.(d)

Gnuplot Plotting File:

Fri Apr 30 14:15:16 2010

DNA single-strand breaks, liver only (Table 3)

The form of the response function by Model:

Model 2
Model 3
Model 4
Model 5

Y[dose]
Y[dose]
Y[dose]
Y[dose]

exp{sign *	b * dose}

exp{sign *	(b * dosej^d}

[c-(c-l) *	exp{-b * dose}]

[c-(c-l) *	exp{-(b * dosej^d}

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;
sign = -1 for decreasing trend.

Model 2 is nested within Models 3 and 4.
Model 3 is nested within Model 5.

Model 4 is nested within Model 5.

This document is a draft for review purposes only and does not constitute Agency policy.

H-7 DRAFT—DO NOT CITE OR QUOTE


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Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))
rho is set to 0.

A constant variance model is fit.

Total number of dose groups = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values
Variable	Model 4

Specified

lnalpha	0.841244

rho(S)	0

a	7.0395

b	0.103521

c	3.50522

d	1

Parameter Estimates
Variable	Model 4

lnalpha	0.960789

rho	0

a	7.7528

b	0.075429

c	3.39665

d	1

Table of Stats From Input Data
Dose	N	Obs Mean	Obs Std Dev

0	6	7.41	1.543

1.938	6	10.78	1.249

4.614	6	13.6	1.69

8.147	6	15.3	1.715

14.01	6	20.4	2.254

25.34	6	23.5	1.372

Estimated Values of Interest
Dose	Est Mean	Est Std	Scaled Residual

0	7.753	1.617	-0.5194

1.938	10.28	1.617	0.7575

4.614	13.21	1.617	0.5853

8.147	16.28	1.617	-1.49

14.01	19.87	1.617	0.7958

25.34	23.59	1.617	-0.1293

Other models for which likelihoods are calculated:

Model A1:	Yij = Mu(i) + e(ij)

This document is a draft for review purposes only and does not constitute Agency policy.

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Var{e(ij)} = Sigma/N2

Model A2 :	Yij	= Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + log(mean(i)) * rho)

Model R:	Yij	= Mu + e(i)

Var{e(ij)} = Sigma/'2

Likelihoods of Interest

Model	Log(likelihood)	DF	AIC

A1	-33.14239	7	80.28478

A2	-31.81197	12	87.62394

A3	-33.14239	7	80.28478

R	-80.44209	2	164.8842

4	-35.29421	4	78.58842

Additive constant for all log-likelihoods =	-33.08. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Test 1: Does response and/or variances differ among Dose levels? (A2 vs. R)

Test 2: Are Variances Homogeneous? (A2 vs. A1)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 6a: Does Model 4 fit the data? (A3 vs 4)

Test

Test 1
Test 2
Test 3
Test 6a

Tests of Interest

-2*log(Likelihood Ratio)

97 .26
2 . 661
2 . 661
4 . 304

10
5
5
3

p-value

< 0.0001
0.7521
0.7521
0.2305

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose
levels, it seems appropriate to model the data.

The p-value for Test 2 is greater than .1. A homogeneous
variance model appears to be appropriate here.

The p-value for Test 3 is greater than .1. The modeled
variance appears to be appropriate here.

The p-value for Test 6a is greater than .1. Model 4 seems
to adeguately describe the data.

Benchmark Dose Computations:

Specified Effect = 1.000000

Risk Type = Estimated standard deviations from control
Confidence Level = 0.950000

BMD =	1.20684

BMDL =	0.916526

This document is a draft for review purposes only and does not constitute Agency policy.

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1 H.2.2.3. Figure for Selected Model: Exponential (M4)

Exponential Model 4 with 0.95 Confidence Level

dose

2	14:15 04/30 2010

3

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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H.2.2.4. Output for Additional Model Presented: Power, Unrestricted

Hassoun et al., 2000: DNA single-strand breaks

Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\5\Blood\18_Has_20 0 0_SSB_PwrCV_U_l.(d)

Gnuplot Plotting File: C:\5\Blood\18_Has_2000_SSB_PwrCV_U_l.plt

Fri Apr 30 14:15:20 2010

DNA single-strand breaks, liver only (Table 3)

The form of the response function is:
Y[dose] = control + slope * doseApower

Dependent variable = Mean
Independent variable = Dose
rho is set to 0
The power is not restricted
A constant variance model is fit

Total number of dose groups = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
alpha =	2.7831

rho =	0 Specified

control =	7.41

slope =	2.16848

power =	0.62 004 8

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -rho

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha	control	slope	power

alpha	1	2.5e-009 -4.6e-009	5.7e-009

control	2.5e-009	1	-0.79	0.66

slope -4.6e-009	-0.79	1	-0.97

power	5.7e-009	0.66	-0.97	1

Parameter Estimates

95.0% Wald Confidence Interval

Variable Estimate Std. Err.	Lower Conf. Limit	Upper Conf. Limit

alpha 2.71022 0.638804	1.45818	3.96225

control 7.26415 0.644159	6.00163	8.52668

slope 2.60017 0.530762	1.55989	3.64044

power 0.575946 0.0589669	0.460373	0.691519

Table of Data and Estimated Values of Interest

This document is a draft for review purposes only and does not constitute Agency policy.

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Dose

Obs Mean

Est Mean

Obs Std Dev Est Std Dev Scaled Res.

0	6	7.41	7.26

1.938	6	10.8	11.1

4.614	6	13.6	13.5

8.147	6	15.3	16

14.01	6	20.4	19.2

25.34	6	23.5	24

1.54	1.65	0.217

1.25	1.65	-0.432

1.69	1.65	0.094

1.71	1.65	-0.993

2.25	1.65	1.85

1.37	1.65	-0.735

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1 -33.142389	7	80.284779

A2 -31.811970	12	87.623940

A3 -33.142389	7	80.284779

fitted -35.946504	4	79.893008

R -80.442086	2	164.884172

Explanation of Tests

Test 1:

Test 2
Test 3
Test 4
(Note:

Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1

Test 2
Test 3
Test 4

97 .2602
2.66084
2.66084
5.60823

10
5
5
3

<.0001
0.7521
0.7521
0.1323

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than
model appears to be appropriate here

.1. A homogeneous variance

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems

This document is a draft for review purposes only and does not constitute Agency policy.

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to adequately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD = 0.452221

BMDL = 0.202688

H.2.2.5. Figure for Additional Model Presented: Power, Unrestricted

Power Model with 0.95 Confidence Level

dose

14:15 04/30 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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H.2.3.	Hassoun et al., 2000: TEARS

I.2.3.1.	Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

x2p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential (M2)

4

0.001

-8.517

1.736E+01

1.223E+01



exponential (M3)

4

0.001

-8.517

1.736E+01

1.223E+01

power hit bound (d = 1)

exponential (M4)

3

0.188

-19.755

2.189E+00

1.151E+00



exponential (M5)

2

0.240

-19.681

3.470E+00

1.525E+00



Hill b

2

0.272

-19.935

3.292E+00

1.737E+00



linear

4

0.002

-9.793

1.444E+01

9.622E+00



polynomial, 5-
degree

4

0.002

-9.793

1.444E+01

9.622E+00



power

4

0.002

-9.793

1.444E+01

9.622E+00

power bound hit (power =1)

a Constant variance model selected (p = 0.3348)
b Best-fitting model, BMDS output presented in this appendix

H.2.3.2. Output for Selected Model: Hill

Hassoun et al., 2000: TBARS

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\5\Blood\19_Has_20 0 0_TBARsLiv_HillCV_l.(d)

Gnuplot Plotting File: C:\5\Blood\19_Has_2000_TBARsLiv_HillCV_l.plt

Fri Apr 30 14:16:02 2010

TBARs, liver only (Table 2)

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = Mean
Independent variable = Dose
rho is set to 0

Power parameter restricted to be greater than 1
A constant variance model is fit

Total number of dose groups = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

This document is a draft for review purposes only and does not constitute Agency policy.

H-14 DRAFT—DO NOT CITE OR QUOTE


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Default Initial Parameter Values

alpha
rho

intercept

0.178788

0

1.469
1.15
1.2785
5.08547

Specified

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -rho

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha
intercept

alpha
1

2 . 8e-008
-4 . 4e-008
4 . 9e-008
-1. 5e-008

intercept
2 . 8e-008
1

-0. 82
0.48
0.52

v

-4 . 4e-008
-0. 82
1

-0. 61
-0.22

n

4 . 9e-008
0.48
-0. 61
1

0.29

k

-1. 5e-008
0.52
-0.22
0.29
1

Parameter Estimates

Variable
alpha
intercept

Estimate
0.16017
1.46138
0.963033
3.44642
3.63417

Std. Err.

0.0377523
0.152797
0.20228
2.43468
1.02019

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

0.0861764
1.1619
0.566571
-1. 32547
1. 63464

0.234163
1.76086
1. 3595
8 . 21832
5.6337

Table of Data and Estimated Values of Interest

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0 6

1.47

1.46

0.291

0.4

0.0466

938 6

1. 55

1. 56

0.539

0.4

-0.0 6 9 6

614 6

2 .15

2 .13

0.363

0.4

0.12

147 6

2 .28

2 . 37

0.247

0.4

-0.54

. 01 6

2 . 62

2 .42

0.517

0.4

1. 25

. 34 6

2.29

2 .42

0. 487

0.4

-0.803

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

This document is a draft for review purposes only and does not constitute Agency policy.

H-15 DRAFT—DO NOT CITE OR QUOTE


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Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1	16.269770	7	-18.539539

A2	19.127827	12	-14.255654

A3	16.269770	7	-18.539539

fitted	14.967391	5	-19.934782

R	2.442940	2	-0.885880

Explanation of Tests

Test

1

Test

2

Test

3

Test

4

Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adequately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio)

Test df

p-value

Test

Test
Test
Test

33.3698
5.71611
5.71611
2.60476

10

5
5
2

0.000236
0.3348
0.3348
0.2719

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than .1.
model appears to be appropriate here

A homogeneous variance

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adequately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	3.29185

BMDL =	1.73738

This document is a draft for review purposes only and does not constitute Agency policy.

H-16 DRAFT—DO NOT CITE OR QUOTE


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1 H.2.3.3. Figure for Selected Model: Hill

Hill Model with 0.95 Confidence Level

dose

2	15:22 04/30 2010

3

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

H-17 DRAFT—DO NOT CITE OR QUOTE


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H.2.4.	Kitchin and Woods, 1979: Bap Hydroxylase Activity

I.2.4.1.	Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

r/'-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential (M2)

9

<0.0001

452.100

2.960E+02

1.446E+02



exponential (M3)

9

<0.0001

452.100

2.960E+02

1.446E+02

power hit bound (d = 1)

exponential (M4)

8

0.002

232.110

3.182E-01

2.373E-01



exponential

(M5)b

7

0.015

227.004

9.321E-01

4.900E-01



Hill

8

<0001

479.250

5.340E+00

4.528E+00



linear

9

<0001

291.380

4.552E-01

3.303E-01



polynomial, 8-
degree

6

<0001

468.198

1.012E+03

7.899E-01



power

9

<0001

291.380

4.552E-01

3.303E-01

power bound hit (power =1)

1 Non-constant variance model selected (p = <0.0001)
' Best-fitting model, BMDS output presented in this appendix

H.2.4.2. Output for Selected Model: Exponential (M5)

Kitchin and Woods, 1979: BaP Hydroxylase Activity

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\5\Blood\2 7_Kitchin_l979_Hydrolase_Exp_l.(d)

Gnuplot Plotting File:

Fri Apr 30 14 :17:28 2010

Kitchin 1979, Tbl3, BaP hydrolase activity

The form of the response function by Model:

Model 2
Model 3
Model 4
Model 5

Y[dose]
Y[dose]
Y[dose]
Y[dose]

exp{sign *	b * dose}

exp{sign *	(b * dosej^d}

[c-(c-l) *	exp{-b * dose}]

[c-(c-l) *	exp{-(b * dosej^d}

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;
sign = -1 for decreasing trend.

Model 2 is nested within Models 3 and 4.
Model 3 is nested within Model 5.

Model 4 is nested within Model 5.

Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))

This document is a draft for review purposes only and does not constitute Agency policy.

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The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)
Total number of dose groups = 11

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values
Variable	Model 5

lnalpha	-3.27793

rho	1.92227

a	4.655

b	0.0041206

c	42.6316

d	1

Parameter Estimates
Variable	Model 5

lnalpha	-2.64071

rho	1.94 04 6

a	5.46248

b	0.0382278

c	30.9208

d	1.42906

Table of Stats From Input Data

Dose

N

Obs Mean

Obs St

0

9

4 . 9

1.11

0.0645

4

4 . 9

i—1

i—1

CO

0.2023

4

6.7

1 . 4

0.3839

4

7 . 2

i—1

CO

1. 613

4

CO
CO

0.26

4.146

4

14

5

11.59

4

59

CO

30.26

4

96

46

90. 9

4

155

16.4

218

4

182

26

863.2

4

189

26



Estimated

Values

of

Interest

Dose

Est Mean

Est

Std

Scaled Residi

0

5. 462

1.

387

-1.217

0.0645

5. 493

1.

394

-0.8507

0.2023

5. 619

1.

425

1. 516

0.3839

5. 854

1.

483

1. 815

1. 613

8.483

2 .

126

-0.1723

4.146

i—1

G\

CO

4 .

125

-1.358

11.59

49.32

11

.73

1. 65

30.26

121. 2

28

. 06

-1.796

90. 9

168 . 5

38

. 62

-0.6975

218

168 . 9

38

.72

0.6765

863.2

168 . 9

38

.72

1. 038

This document is a draft for review purposes only and does not constitute Agency policy.

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Other models for which	likelihoods are calculated:

Model A1:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma/'2

Model A2 :	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma(i)^2

Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= exp(lalpha + log(mean(i)) * rho)

Model R:	Yij	= Mu + e(i)

Var{e(ij)}	= Sigma/'2

Likelihoods of Interest

Model	Log(likelihood)	DF	AIC

A1	-158.1306	12	340.2613

A2	-84.80028	22	213.6006

A3	-98.82189	13	223.6438

R	-234.6252	2	473.2504

5	-107.5022	6	227.0044

Additive constant for all log-likelihoods =	-45.03. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Test 1: Does response and/or variances differ among Dose levels? (A2 vs. R)

Test 2: Are Variances Homogeneous? (A2 vs. A1)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 7a: Does Model 5 fit the data? (A3 vs 5)

Test

Test 1
Test 2
Test 3
Test 7a

Tests of Interest
-2*log(Likelihood Ratio)

299.6

146.7
28 . 04
17 . 36

D. F.

20
10
9
7

p-value

<	0.0001

<	0.0001
0.0009381

0.01521

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose
levels, it seems appropriate to model the data.

The p-value for Test 2 is less than .1. A non-homogeneous
variance model appears to be appropriate.

The p-value for Test 3 is less than .1. You may want to
consider a different variance model.

The p-value for Test 7a is less than .1. Model 5 may not adeguately
describe the data; you may want to consider another model.

Benchmark Dose Computations:

Specified Effect = 1.000000

Risk Type = Estimated standard deviations from control
Confidence Level = 0.950000

This document is a draft for review purposes only and does not constitute Agency policy.

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BMD =	0.9321

BMDL =	0.490004

7 H.2.4.3. Figure for Selected Model: Exponential (M5)

CD
CO
c
o

Q.

CO
CD

a:

c
m

CD

250

200

150

100

Exponential Model 5 with 0.95 Confidence Level

Exponential

S/IDLBMD

0	100 200 300

400 500
dose

600 700 800 900

14:17 04/30 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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H.2.5.	National Toxicology Program, 2006: Liver EROD 53 Weeks

I.2.5.1.	Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

x2p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential (M2)

4

<0.0001

648.094

2.011E+01

1.464E+01



exponential (M3)

4

<0.0001

648.094

2.011E+01

1.464E+01

power hit bound (d = 1)

exponential (M4)

3

0.015

521.251

1.430E-02

9.808E-03



exponential (M5)

2

0.354

514.812

7.656E-02

3.202E-02



Hill b

2

0.760

513.286

1.853E-01

9.351E-02



linear

4

<0001

639.841

1.034E+01

6.557E-03



polynomial, 5-
degree

1

<0001

14.000

error

error



power

4

<0001

592.889

2.254E-02

1.527E-02

power bound hit (power = 1)

1 Non-constant variance model selected (p = <.0001)
' Best-fitting model, BMDS output presented in this appendix

H.2.5.2. Output for Selected Model: Hill

National Toxicology Program, 2006: Liver EROD 53 Weeks

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\5\Blood\46_NTP_20 0 6_ERODliv53_Hill_l.(d)

Gnuplot Plotting File: C:\5\Blood\4 6_NTP_2006_ERODliv53_Hill_l.plt

Sun May 02 15:34:21 2010

0

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = Mean
Independent variable = Dose

Power parameter restricted to be greater than 1

The variance is to be modeled as Var(i) = exp(lalpha + rho * ln(mean(i)))
Total number of dose groups = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

This document is a draft for review purposes only and does not constitute Agency policy.

H-22 DRAFT—DO NOT CITE OR QUOTE


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lalpha
rho

intercept

11. 0197

0

30.215
1841.26
7 . 0105
6.95814

Asymptotic Correlation Matrix of Parameter Estimates

lalpha
rho

intercept

lalpha
1

-0. 97
-0.18
0. 065
-0.025
0. 046

rho

-0. 97
1

0.17
-0.093
0. 025
-0.048

intercept

-0.18
0.17
1

-0.022
0. 011
0.00084

v

0. 065
-0.093
-0.022
1

-0.73
0. 87

n

-0.025
0. 025
0. 011
-0.73
1

-0. 83

k

0. 046
-0.048
0. 00084
0. 87
-0. 83
1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
lalpha
rho

intercept

Estimate
-4 .47504
2.12799
30.2685
1813.88
2 . 02516
3.78554

Std. Err.

0. 923978
0.137849
1.41935
100.554
0.29717
0.349266

Lower Conf. Limit

-6.286
1. 85781
27.4866
1616.8
1.44272
3.101

Upper Conf. Limit

-2.66407
2 .39817
33.0504
2010.96
2 . 6076
4 .47009

Table of Data and Estimated Values of Interest
Dose	N Obs Mean	Est Mean Obs Std Dev Est Std Dev Scaled Res.

0

2 .458
5.533
9.543
16.18
29. 04

30.2

569

1. 28e + 003
1. 55e + 003
1. 73e + 003
1. 87e + 003

30.3

564

1. 27e + 003
1. 6e + 003
1. 75e + 003
1. 82e + 003

4 . 5

6 9.6
270
318
304
309

4 . 02
90.3
214
274
302
313

-0.0377
0.17
0.137
-0.529
-0.248
0.507

Model Descriptions for likelihoods calculated

Model A1:	Yij

Var{e(ij ) }

Model A2:	Yij

Var{e(ij ) }

Mu(i) + e(ij ;
Sigma/N2

Mu(i) + e(ij ;

Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi

Var{e(i)}

Mu + e(i)
Sigma/N2

This document is a draft for review purposes only and does not constitute Agency policy.

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Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1	-285.269096	7	584.538193

A2	-249.237836	12	522.475671

A3	-250.368300	8	516.736600

fitted	-250.643212	6	513.286424

R	-338.451300	2	680.902600

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adequately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Test

2

Test

3

Test

4

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	178.427	10	<.0001

Test 2	72.0625	5	<.0001

Test 3	2.26093	4	0.6879

Test 4	0.549824	2	0.7596

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adequately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	0.185269

BMDL =	0.0935065

This document is a draft for review purposes only and does not constitute Agency policy.

H-24 DRAFT—DO NOT CITE OR QUOTE


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1 H.2.5.3. Figure for Selected Model: Hill

Hill Model with 0.95 Confidence Level

This document is a draft for review purposes only and does not constitute Agency policy.

H-25 DRAFT—DO NOT CITE OR QUOTE


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H.2.6.	National Toxicology Program, 2006: Lung Erod 53 Weeks

I.2.6.1.	Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

x2p-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential (M2)

4

<0.0001

314.332

3.281E+01

2.047E+01



exponential (M3)

4

<0.0001

555.061

5.210E+00

8.194E-01

power hit bound (d = 1)

exponential
(M4)b

3

0.302

255.955

9.586E-02

5.907E-02



exponential (M5)

2

0.276

256.882

1.044E+00

6.588E-02



Hill

2

0.275

256.882

1.903E+00

3.469E-01



linear

4

<0001

313.237

2.662E+01

1.251E+01



polynomial, 5-
degree

5

<0001

330.180

error

2.718E+01



power

4

<0001

313.237

2.662E+01

1.251E+01

power bound hit (power =1)

power,
unrestricted0

3

0.032

261.083

1.875E-07

1.875E-07

unrestricted (power =0.18)

a Non-constant variance model selected (p = <0.0001)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

H.2.6.2. Output for Selected Model: Exponential (M4)

National Toxicology Program, 2006: Lung EROD 53 Weeks

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\5\Blood\52_NTP_20 0 6_LungEROD53_Exp_l.(d)

Gnuplot Plotting File:

Fri Apr 30 14:20:27 2010

Tbl 12, Week 53, Lung Microsomes EROD

The form of the response function by Model:

Model 2
Model 3
Model 4
Model 5

Y[dose]
Y[dose]
Y[dose]
Y[dose]

exp{sign *	b * dose}

exp{sign *	(b * dosej^d}

[c-(c-l) *	exp{-b * dose}]

[c-(c-l) *	exp{-(b * dosej^d}

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;
sign = -1 for decreasing trend.

Model 2 is nested within Models 3 and 4.
Model 3 is nested within Model 5.

Model 4 is nested within Model 5.

This document is a draft for review purposes only and does not constitute Agency policy.

H-26 DRAFT—DO NOT CITE OR QUOTE


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Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)
Total number of dose groups = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values

Variable

lnalpha
rho

Model 4

-0.80064
1.47683
2 .86045
0.134268
16.0581
1

Parameter Estimates
Variable	Model 4

lnalpha	-1.14455

rho	1.63458

a	3.06102

b	0.371249

c	14.1551

d	1

Table of Stats From Input Data

Dose	N	Obs Mean	Obs Std Dev

0	8	3.011	1.584

2.458	8	27.15	5.269

5.533	8	42.85	11.15

9.543	8	36.57	12.99

16.18	8	43.75	18.55

29.04	8	43.71	6.322

Estimated Values of Interest
Dose	Est Mean	Est Std	Scaled Residual

0	3.061	1.408	-0.1005

2.458	27.16	8.383	-0.003073

5.533	38.17	11.07	1.196

9.543	42.16	12.01	-1.318

16.18	43.23	12.26	0.1191

29.04	43.33	12.28	0.08864

Other models for which likelihoods are calculated:

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

This document is a draft for review purposes only and does not constitute Agency policy.

H-27 DRAFT—DO NOT CITE OR QUOTE


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Model A2 :	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma(i)^2

Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= exp(lalpha + log(mean(i)) * rho)

Model R:	Yij	= Mu + e(i)

Var{e(ij)}	= Sigma/'2

Likelihoods of Interest

Model	Log(likelihood)	DF	AIC

A1	-135.2677	7	284.5353

A2	-115.6885	12	255.3771

A3	-121.1517	8	258.3034

R	-162.0902	2	328.1805

4	-122.9773	5	255.9546

-44.11. This constant added to the

Additive constant for all log-likelihoods =
above values gives the log-likelihood including the term that does not
depend on the model parameters.

Test

1:

Test

2 :

Test

3:

Test

6a

Explanation of Tests

Does response and/or variances differ among Dose levels? (A2 vs. R)

Are Variances Homogeneous? (A2 vs. A1)

Are variances adeguately modeled? (A2 vs. A3)

Does Model 4 fit the data? (A3 vs 4)

Tests of Interest

Test

-2*log(Likelihood Ratio)

D. F.

p-value

Test 1

92 . 8

10

< 0.0001

Test 2

39.16

5

< 0.0001

Test 3

10. 93

4

0.0274

Test 6a

3. 651

3

0.3017

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose
levels, it seems appropriate to model the data.

The p-value for Test 2 is less than .1. A non-homogeneous
variance model appears to be appropriate.

The p-value for Test 3 is less than .1. You may want to
consider a different variance model.

The p-value for Test 6a is greater than .1. Model 4 seems
to adeguately describe the data.

Benchmark Dose Computations:

Specified Effect = 1.000000

Risk Type = Estimated standard deviations from control

Confidence Level = 0.950000

BMD =	0.09586

BMDL = 0.0590734

This document is a draft for review purposes only and does not constitute Agency policy.

H-28 DRAFT—DO NOT CITE OR QUOTE


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H.2.6.3. Figure for Selected Model: Exponential (M4)

Exponential Model 4 with 0.95 Confidence Level

dose

14:20 04/30 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

H-29 DRAFT—DO NOT CITE OR QUOTE


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H.2.6.4. Output for Additional Model Presented: Power, Unrestricted

National Toxicology Program, 2006: Lung EROD 53 Weeks

Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\5\Blood\52_NTP_20 0 6_LungEROD53_Pwr_U_l.(d)

Gnuplot Plotting File: C:\5\Blood\52_NTP_2006_LungEROD53_Pwr_U_l.plt

Fri_Apr 30 14:20:33 2010

Tbl 12, Week 53, Lung Microsomes EROD

The form of the response function is:
Y[dose] = control + slope * doseApower

Dependent variable = Mean
Independent variable = Dose
The power is not restricted

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)
Total number of dose groups = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
lalpha =	4.76968

rho =	0

control =	3.011

slope =	23.2411

power =	0.187468

Asymptotic Correlation Matrix of Parameter Estimates

lalpha	rho	control	slope	power

lalpha 1	-0.96	-0.49	0.1	-0.045

rho -0.96	1	0.45	-0.13	0.05

control -0.49	0.45	1	-0.14	0.048

slope 0.1	-0.13	-0.14	1	-0.94

power -0.045	0.05	0.048	-0.94	1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
lalpha
rho
control
slope
power

Estimate

-1. 02668
1. 63033
3. 01543
23.8167
0.179731

Std. Err.

0. 818488
0.24056
0.519355
3.70401
0.0639681

Lower Conf. Limit

-2.63088
1.15884
1. 99751
16.5569
0.054356

Upper Conf. Limit
0.577531
2 .10182
4.03335
31.0764
0.305106

Table of Data and Estimated Values of Interest
Dose	N Obs Mean	Est Mean Obs Std Dev Est Std Dev Scaled Res.

This document is a draft for review purposes only and does not constitute Agency policy.

H-30 DRAFT—DO NOT CITE OR QUOTE


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CO

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43.7

46.6

6.32

13.7

-0.605

Model Descriptions for likelihoods calculated

Model A1:	Yij	= Mu(i) + e(iji

Var{e(ij)} = Sigma/'2

Model A2 :	Yij	= Mu(i) + e(ij|

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1	-135.267662	7	284.535325

A2	-115.688533	12	255.377067

A3	-121.151707	8	258.303413

fitted	-125.541690	5	261.083380

R	-162.090242	2	328.180484

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

Test 3: Are variances adequately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.)

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1

Test 2
Test 3
Test 4

92 .8034
39.1583
10.9263
8 . 77 997

10
5
4
3

<.0001
<.0001
0.0274
0.03236

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is less than .1. You may want to consider a
different variance model

The p-value for Test 4 is less than .1. You may want to try a different
model

This document is a draft for review purposes only and does not constitute Agency policy.

H-31 DRAFT—DO NOT CITE OR QUOTE


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Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD = 1.87 4 5e-007

BMDL = 1. 87 4 5e-007

H.2.6.5. Figure for Additional Model Presented: Power, Unrestricted

Power Model with 0.95 Confidence Level

dose

14:20 04/30 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

H-32 DRAFT—DO NOT CITE OR QUOTE


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H.2.7.	National Toxicology Program, 2006: Labeling Index 31 Weeks

I.2.7.1.	Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

r/'-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential (M2)

4

0.000

46.547

8.660E+00

6.926E+00



exponential (M3)

4

0.000

46.547

8.660E+00

6.926E+00

power hit bound (d = 1)

exponential (M4)

3

<0.0001

50.958

3.151E+00

1.865E+00



exponential (M5)

3

<0.0001

50.958

3.151E+00

1.864E+00

power hit bound (d = 1)

Hill

3

<0001

50.963

3.145E+00

error

n lower bound hit (n = 1)

linear

4

0.000

48.958

3.151E+00

1.865E+00



polynomial, 5-
degree b

3

0.000

46.230

7.607E+00

3.125E+00



power

4

0.000

48.958

3.151E+00

1.865E+00

power bound hit (power =1)

1 Non-constant variance model selected (p = <.0001)
' Best-fitting model, BMDS output presented in this appendix

H.2.7.2. Output for Selected Model: Polynomial, 5-degree

National Toxicology Program, 2006: Labeling Index 31 Weeks

Polynomial Model. (Version: 2.13; Date: 04/08/2008)

Input Data File: C:\5\Blood\3 8_NTP_20 0 6_HepIndex_Poly5_l.(d)

Gnuplot Plotting File: C:\5\Blood\38_NTP_2006_HepIndex_Poly5_l.plt

Fri_Apr 30 14:21:16 2010

Tbl 11, 31wk, Hep Cell Proliferation Labeling Index

The form of the response function is:

Y[dose] = beta_0 + beta_l*dose + beta_2*dose/N2 + ...

Dependent variable = Mean
Independent variable = Dose

The polynomial coefficients are restricted to be positive

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)
Total number of dose groups = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

This document is a draft for review purposes only and does not constitute Agency policy.

H-33 DRAFT—DO NOT CITE OR QUOTE


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lalpha =	0.708431

rho =	0

beta_0 =	0.327

beta_l =	0

beta_2 =	0

beta_3 =	0

beta_4 =	0

beta 5 =	0

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -beta 2 -beta 3 -beta 4

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

lalpha
rho
beta_0
beta_l
beta 5

lalpha
1

-0.086
0. 012
-0.032
0. 043

rho

-0.086
1

-0.0027
-0.011
0. 076

beta_0

0. 012
-0.0027
1

-0.6
0.23

beta_l
-0.032
-0.011
-0.6
1

-0.53

beta 5

0. 043
0. 076
0.23
-0.53
1

Parameter Estimates

Variable
lalpha
rho

beta_0
beta_l
beta_2
beta_3
beta_4
beta 5

Estimate
-0.501559
1.90452
0.500197
0.0525247
8.00068e-025
0
0

1.08658e-007

Std. Err.
0.185039
0.272948
0.102837
0.0192967
NA
NA
NA

. 10451e-008

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

-0.864229
1.36955
0.298641
0.0147038

-1. 0987 9e-008

-0.138889
2 .43948
0.701753
0. 0903456

2 . 28305e-007

NA - Indicates that this parameter has hit a bound
implied by some inequality constraint and thus
has no standard error.

Table of Data and Estimated Values of Interest

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0

2 . 331
5.315
9.207
15. 66
28 .13

9
10
10
10
10
10

0.327
0. 852
0. 956
0.792
1. 33
3. 85

0.5

0. 623
0.78
0. 991
1.42
3.89

0.189

0. 651
0 .737
0. 462
1.12
3. 08

0. 402
0. 496
0. 614
0 .772
1.09
2 .84

-1.29

1.46
0. 907
-0.816
-0.266
-0.0523

Model Descriptions for likelihoods calculated

Model A1:	Yij	= Mu(i) + e(iji

Var{e(ij)} = Sigma/'2

Model A2:	Yij	= Mu(i) + e(ij|

Var{e(ij)} = Sigma(i)^2

This document is a draft for review purposes only and does not constitute Agency policy.

H-34 DRAFT—DO NOT CITE OR QUOTE


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Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1	-47.234977	7	108.469953

A2	-8.679256	12	41.358512

A3	-8.980651	8	33.961301

fitted	-18.115050	5	46.230101

R	-63.448285	2	130.896571

Explanation of Tests

Test 1:

Test

2

Test

3

Test

4

Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.'

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	109.538	10	<.0001

Test 2	77.1114	5	<.0001

Test 3	0.60279	4	0.9628

Test 4	18.2688	3	0.0003871

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is less than .1. You may want to try a different
model

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	7.6073

BMDL =	3.12526

This document is a draft for review purposes only and does not constitute Agency policy.

H-3 5 DRAFT—DO NOT CITE OR QUOTE


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H.2.7.3. Figure for Selected Model: Polynomial, 5-degree

Polynomial Model with 0.95 Confidence Level

dose

14:21 04/30 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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H.2.8.	Vanden Heuvel et al., 1994: Hepatic CYP1A1 Mrna Expression

I.2.8.1.	Summary Table of BMDS Modeling Results	

Model3

Degrees
of

Freedom

r/'-

Value

AIC

BMD

(ng/kg)

BMDL

(ng/kg)

Notes

exponential (M2)

5

<0.0001

1147.626

1.769E+01

1.257E+01



exponential (M3)

4

<0.0001

1149.626

1.769E+01

1.257E+01

power hit bound (d = 1)

exponential (M4)

4

<0.0001

666.337

6.104E-02

2.871E-02



exponential (M5)

3

<0.0001

635.591

1.252E+00

9.089E-01



Hillb

3

<0001

664.418

2.429E-01

1.679E-01



linear

5

<0001

673.777

4.546E-02

2.487E-02



polynomial, 6-
degree

6

<0001

1213.329

error

1.301E+03



power

4

<0001

673.418

6.269E-02

3.196E-02



a Non-constant variance model selected (p = <0.0001)
b Best-fitting model, BMDS output presented in this appendix

H.2.8.2. Output for Selected Model: Hill

Vanden Heuvel et al., 1994: Hepatic CYP1 Al mRNA Expression

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\Usepa\BMDS21\Data\hil_Vanden_mRNA_Setting.(d)

Gnuplot Plotting File: C:\Usepa\BMDS21\Data\hil_Vanden_mRNA_Setting.plt

Tue May 18 05:24:48 2010

BMDS Model Run

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = mRNA mean
Independent variable = blood cone
Power parameter is not restricted

The variance is to be modeled as Var(i) = exp(lalpha + rho * ln(mean(i)))
Total number of dose groups = 7

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

User Inputs Initial Parameter Values

This document is a draft for review purposes only and does not constitute Agency policy.

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lalpha
rho

intercept

1

1. 9
6

36000
1

1000

Asymptotic Correlation Matrix of Parameter Estimates

lalpha
rho

intercept

lalpha
1

-0.89
-0.43
0.27
0. 68
-0.18

rho

-0.89
1

0.31
-0.42
-0.72
0.22

intercept

-0.43
0.31
1

-0.093
0.14
-0. 04

v

0.27
-0.42
-0.093
1

0. 075
0.7

n

0. 68
-0.72
0.14
0. 075
1

-0.52

k

-0.18
0.22
-0. 04
0.7
-0.52
1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
lalpha
rho

intercept

Estimate
-0.191631
2.0275
5.416
41657.2
1.29154
97 .8648

Std. Err.
0.711681
0.132551
1.16292
16561.5
0.100513
41.0376

Lower Conf. Limit

-1. 5865
1.76771
3.13672
9197.25
1.09454
17 .4325

Upper Conf. Limit
1.20324
2 .28729
7 .69529
74117.2
1.48854
178 . 297

Table of Data and Estimated Values of Interest

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0

0.0113
0.106
0.8828

6.46
48 . 32
434 . 5

13

c

12

7

7
11
5

5.4

7 . 2
14 . 8
12 . 8
536
1. 8e + 004
3. 67e + 004

5.42

5.76
11. 6
100
1. 21e + 003
1.19e + 004
3.64 e + 0 0 4

3. 61

5.59
14 . 9
4 . 5
320

1.52e+004
2 . 21e + 004

5. 04

5.36
10. 9
97 . 2
1. 22e + 003
1. 24e + 004
3. 82e + 004

-0.0115

0.	602

1.	03
-2 . 38

-1.48
1. 62
0.0199

Model Descriptions for likelihoods calculated

Model A1:	Yij

Var{e(ij ) }

Model A2:	Yij

Var{e(ij ) }

Mu(i) + e(ij ;
Sigma/N2

Mu(i) + e(ij ;

Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi

Var{e(i)}

Mu + e(i)
Sigma/N2

This document is a draft for review purposes only and does not constitute Agency policy.

H-3 8 DRAFT—DO NOT CITE OR QUOTE


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Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1	-572.470944	8	1160.941889

A2	-290.799287	14	609.598575

A3	-293.809342	9	605.618684

fitted	-326.209186	6	664.418372

R	-603.663396	2	1211.326792

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

Test 3: Are variances adequately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.)

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	625.728	12	<.0001

Test 2	563.343	6	<.0001

Test 3	6.02011	5	0.3043

Test 4	64.7997	3	<.0001

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is less than .1. You may want to try a different
model

Benchmark Dose	Computation

Specified effect =	24

Risk Type =	Point risk

Confidence level =	0.95

BMD =	0.24 9203

BMDL =	0.167897

This document is a draft for review purposes only and does not constitute Agency policy.

H-39 DRAFT—DO NOT CITE OR QUOTE


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1 H.2.8.3. Figure for Selected Model: Hill

Hill Model with 0.95 Confidence Level

dose

2	05:24 05/18 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

H-40 DRAFT—DO NOT CITE OR QUOTE


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H.3. ADMINISTERED DOSE BMDS RESULTS
H.3.1. Hassoun et al., 2000: Cytochrome C Reductase

Model3

Degrees
of

Freedom

x'/'-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

exponential (M2)

4

0.002

-139.075

3.939E+01

3.254E+01



exponential (M3)

4

0.002

-139.075

3.939E+01

3.254E+01

power hit bound (d = 1)

exponential
(M4)b

3

0.637

-151.807

9.085E+00

5.886E+00



exponential (M5)

2

0.786

-151.023

1.420E+01

6.537E+00



Hill

2

0.741

-150.905

1.513E+01

6.277E+00



linear

4

0.032

-144.946

2.470E+01

1.933E+01



polynomial, 5-
degree

4

0.032

-144.946

2.470E+01

1.933E+01



power

4

0.032

-144.946

2.470E+01

1.933E+01

power bound hit (power =1)

power,
unrestricted0

3

0.211

-148.989

6.573E+00

1.966E+00

unrestricted (power = 0.574)

a Constant variance model selected (p = 0.3871)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

H.3.1.2. Output for Selected Model: Exponential (M4)

Hassoun et al., 2000: Cytochrome C reductase

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\5\17_Has_20 0 0_CytCLiv_ExpCV_l.(d)

Gnuplot Plotting File:

Fri Apr 30 21:15:20 2010

TBARs, liver only (Table 2)

The form of the response function by Model:

Model 2
Model 3
Model 4
Model 5

Y[dose]
Y[dose]
Y[dose]
Y[dose]

exp{sign *	b * dose}

exp{sign *	(b * dosej^d}

[c-(c-l) *	exp{-b * dose}]

[c-(c-l) *	exp{-(b * dosej^d}

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;
sign = -1 for decreasing trend.

Model 2 is nested within Models 3 and 4.
Model 3 is nested within Model 5.

This document is a draft for review purposes only and does not constitute Agency policy.

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Model 4 is nested within Model 5.

Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))
rho is set to 0.

A constant variance model is fit.

Total number of dose groups = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values
Variable	Model 4

Specified

lnalpha	-5.48625

rho(S)	0

a	0.1387

b	0.027423

c	3.36121

d	1

Parameter Estimates
Variable	Model 4

lnalpha	-5.43908

rho	0

a	0.141259

b	0.0235562

c	3.42165

d	1

Table of Stats From Input Data
Dose	N	Obs Mean	Obs Std Dev

0 6

0

146

0.06614

3 6

0

177

0.05389

10 6

0

191

0.05634

22 6

0

271

0.05634

46 6

0

388

0.06369

100 6

0

444

0.1102

Estimated Values of Interest

Dose	Est Mean	Est Std	Scaled Residual

0

0.1413

0. 06591

0

1762

3

0.1646

0.06591

0

4609

10

0.2131

0. 06591

-0

8196

22

0.2796

0. 06591

-0

3199

46

0.3676

0. 06591

0

7587

100

0. 4509

0. 06591

-0

2564

This document is a draft for review purposes only and does not constitute Agency policy.

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Other models for which	likelihoods are calculated:

Model A1:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma/'2

Model A2 :	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma(i)^2

Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= exp(lalpha + log(mean(i)) * rho)

Model R:	Yij	= Mu + e(i)

Var{e(ij)}	= Sigma/'2

Likelihoods of Interest

Model	Log(likelihood)	DF	AIC

A1	80.75258	7	-147.5052

A2	83.37355	12	-142.7471

A3	80.75258	7	-147.5052

R	55.82002	2	-107.64

4	79.90337	4	-151.8067

Additive constant for all log-likelihoods =	-33.08. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Test 1: Does response and/or variances differ among Dose levels? (A2 vs. R)

Test 2: Are Variances Homogeneous? (A2 vs. A1)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 6a: Does Model 4 fit the data? (A3 vs 4)

Test

Test 1
Test 2
Test 3
Test 6a

Tests of Interest

-2*log(Likelihood Ratio)

55.11
5.242
5.242
1.698

D. F.

10
5
5
3

p-value

< 0.0001
0.3871
0.3871
0.6373

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose
levels, it seems appropriate to model the data.

The p-value for Test 2 is greater than .1. A homogeneous
variance model appears to be appropriate here.

The p-value for Test 3 is greater than .1. The modeled
variance appears to be appropriate here.

The p-value for Test 6a is greater than .1. Model 4 seems
to adeguately describe the data.

Benchmark Dose Computations:

Specified Effect = 1.000000

Risk Type = Estimated standard deviations from control
Confidence Level = 0.950000

This document is a draft for review purposes only and does not constitute Agency policy.

H-43 DRAFT—DO NOT CITE OR QUOTE


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EMD =

9.0851

E'.MDL =	5.88612

H.3.1.3. Figure for Selected Model: Exponential (M4)

Exponential Model 4 with 0.95 Confidence Level

dose

21:15 04/30 2010

H.3.1.4. Output for Additional Model Presented: Power, Unrestricted
Hassoun et al., 2000: Cytochrome C reductase

Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\5\17_Has_2000_CytCLiv_PwrCV_U_l.(d)

Gnuplot Plotting File: C:\5\17_Has_2000_CytCLiv_PwrCV_U_l.plt

Fri Apr 30 21:15:26 2010

TBARs, liver only (Table 2)

The form of the response function is:
Y[dose] = control + slope * doseApower

Dependent variable = Mean
Independent variable = Dose
rho is set to 0
The power is not restricted
A constant variance model is fit

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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Total number of dose groups = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

alpha =	0.004972

rho =	0 Specified

control =	0.146

slope = 0.0109242
power =	0.717 914

Asymptotic Correlation Matrix of Parameter Estimates

alpha
control

The model parameter(s) -rho

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha
1

. 8e-010

control
3. 8e-010
1

slope
-3.8e-009
-0.77

power
4.5e-009
0. 68

slope -3.8e-009	-0.77	1	-0.98

power	4.5e-009	0.68	-0.98	1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
alpha
control
slope
power

Estimate

0. 00469717
0.135495
0.0232652
0.573772

Std. Err.

0.00110713
0.0246289
0.013381
0.119032

Lower Conf. Limit

0. 00252723
0.0872229
-0.00296103
0.340474

Upper Conf. Limit

0.00686711
0.183766
0.0494915
0.80707

Table of Data and Estimated Values of Interest

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0 6

0

146

0.135

0.0661

0

0685

0.375

3 6

0

177

0.179

0.0539

0

0685

-0.0784

10 6

0

191

0.223

0.0563

0

0685

-1.13

22 6

0

271

0.273

0.0563

0

0685

-0.056

46 6

0

388

0.345

0.0637

0

0685

1. 54

100 6

0

444

0. 462

0.11

0

0685

-0.653

Model Descriptions for likelihoods calculated

Model A1:	Yij	=	Mu(i) + e(ij)

Var{e(ij)}	=	Sigma/'2

Model A2:	Yij	=	Mu(i) + e(ij)

Var{e(ij)}	=	Sigma(i)^2

Model A3:	Yij	=	Mu(i) + e(ij)

Var{e(ij)}	=	Sigma/'2

This document is a draft for review purposes only and does not constitute Agency policy.

H-45 DRAFT—DO NOT CITE OR QUOTE


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Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1	80.752584	7	-147.505168

A2	83.373547	12	-142.747094

A3	80.752584	7	-147.505168

fitted	78.494318	4	-148.988637

R	55.820023	2	-107.640047

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Test

2

Test

3

Test

4

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	55.107	10	<.0001

Test 2	5.24193	5	0.3871

Test 3	5.24193	5	0.3871

Test 4	4.51653	3	0.2108

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than .1. A homogeneous variance
model appears to be appropriate here

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adeguately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD = 6.57302

BMDL = 1.96558

This document is a draft for review purposes only and does not constitute Agency policy.

H-46 DRAFT—DO NOT CITE OR QUOTE


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H.3.1.5. Figure for Additional Model Presented: Power, Unrestricted

Power Model with 0.95 Confidence Level

dose

21:15 04/30 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

H-47 DRAFT—DO NOT CITE OR QUOTE


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H.3.2.	Hassoun et al., 2000: DNA Single-Strand Breaks

I.3.2.1.	Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

r/'-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

exponential (M2)

4

<0.0001

120.828

3.006E+01

2.491E+01



exponential (M3)

4

<0.0001

120.828

3.006E+01

2.491E+01

power hit bound (d = 1)

exponential (M4)

3

0.036

82.814

3.734E+00

2.783E+00



exponential (M5)

3

0.036

82.814

3.734E+00

2.783E+00

power hit bound (d = 1)

Hill b

3

0.068

81.407

2.890E+00

2.007E+00

n lower bound hit (n = 1)

linear

4

<0001

111.165

1.807E+01

1.452E+01



polynomial, 5-
degree

4

<0001

111.165

1.807E+01

1.452E+01



power

4

<0001

111.165

1.807E+01

1.452E+01

power bound hit (power =1)

Hill, unrestricted

C

2

0.133

80.318

9.618E-01

2.114E-01

unrestricted (n = 0.613)

a Constant variance model selected (p = 0.7521)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

H.3.2.2. Output for Selected Model: Hill

Hassoun et al., 2000: DNA single-strand breaks

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\5\18_Has_2000_SSB_HillCV_l.(d)

Gnuplot Plotting File: C:\5\18_Has_2000_SSB_HillCV_l.plt

Fri Apr 30 21:16:28 2010

DNA single-strand breaks, liver only (Table 3)

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = Mean
Independent variable = Dose
rho is set to 0

Power parameter restricted to be greater than 1
A constant variance model is fit

Total number of dose groups = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

This document is a draft for review purposes only and does not constitute Agency policy.

H-48 DRAFT—DO NOT CITE OR QUOTE


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Relative Function
Parameter

has been set to: le-008
has been set to: le-008

Default Initial Parameter Values

alpha
rho

intercept

2 .7831

0

7 .41
16.09
0.174831
69.2706

Specified

Asymptotic Correlation Matrix of Parameter Estimates

alpha
intercept

The model parameter(s) -rho -n

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha
1

1. le-007
1.9e-007
1.9e-007

intercept
1.le-007
1

0.099
0. 61

v

1.9e-007
0.099
1

0.79

k

1.9e-007
0. 61
0.79
1

Parameter Estimates

Variable
alpha
intercept

k

Estimate

2 . 82659
8 .16404
20.1253
1

31. 702

Std. Err.

0.666233
0.581043
1.69013
NA

8 . 35815

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

1.5208

7.02522
16.8127

15.3203

4 .13238
9.30286
23.4379

48 . 0836

NA - Indicates that this parameter has hit a bound
implied by some inequality constraint and thus
has no standard error.

Table of Data and Estimated Values of Interest

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0 6

7 .41

CO

i—1

G\

1. 54

1

68

-1.1

3 6

10.8

9. 9

1. 25

1

68

1.28

10 6

13. 6

13

1.69

1

68

0.889

22 6

15.3

16.4

1.71

1

68

-1. 62

46 6

20.4

20.1

2 . 25

1

68

0.469

100 6

23.5

23. 4

1. 37

1

68

0.0802

Model Descriptions for likelihoods calculated

Model A1:	Yij	= Mu(i) + e(iji

Var{e(ij)} = Sigma/'2

Model A2:	Yij	= Mu(i) + e(ij|

Var{e(ij)} = Sigma(i)^2

This document is a draft for review purposes only and does not constitute Agency policy.

H-49 DRAFT—DO NOT CITE OR QUOTE


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Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i)

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model
A1

A2
A3

fitted
R

Log(likelihood)
-33.142389
-31.811970
-33.142389
-36.703273
-80.442086

Param's

7
12
7
4
2

AIC
80.284779
87 . 623940
80.284779
81.406545
164.884172

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio) Test df

p-value

Test 1

Test 2
Test 3
Test 4

97 .2602
2.66084
2.66084
7 . 12177

10
5
5
3

<.0001
0.7521
0.7521
0.06812

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than .1. A homogeneous variance
model appears to be appropriate here

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is less than .1. You may want to try a different
model

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	2 . 88976

BMDL =	2.0066 9

This document is a draft for review purposes only and does not constitute Agency policy.

H-50 DRAFT—DO NOT CITE OR QUOTE


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H.3.2.3. Figure for Selected Model: Hill

Hill Model with 0.95 Confidence Level

dose

21:16 04/30 2010

H.3.2.4. Output for Additional Model Presented: Hill, Unrestricted

Hassoun et al., 2000: DNA single-strand breaks

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\5\18_Has_2000_SSB_HillCV_U_l.(d)

Gnuplot Plotting File: C:\5\18_Has_2 000_SSB_HillCV_U_l.plt

Fri Apr 30 21:16:30 2010

DNA single-strand breaks, liver only (Table 3)

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = Mean
Independent variable = Dose
rho is set to 0

Power parameter is not restricted
A constant variance model is fit

Total number of dose groups = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

H-51 DRAFT—DO NOT CITE OR QUOTE


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Relative Function
Parameter

has been set to: le-008
has been set to: le-008

Default Initial Parameter Values

alpha
rho

intercept

2 .7831

0

7 .41
16.09
0.174831
69.2706

Specified

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -rho

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha
intercept

alpha
1

-2 . 2e-008
-4 . 6e-008
8 . 4e-009
-4 . 3e-008

intercept
-2 . 2e-008
1

-0.33
0.47
-0.29

v

-4 . 6e-008
-0.33
1

-0. 95
1

n

. 4e-009
0.47
-0. 95
1

-0. 96

k

-4 . 3e-008
-0.29
1

-0. 96
1

Parameter Estimates

Variable
alpha
intercept

Estimate
2 .5942
7 . 47627
36.9014
0.612877
148.104

Std. Err.

0. 611459
0. 665055
25.5466
0.190055
303.532

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

1.39576
6.17278
-13.1689
0.240376
-446.809

3.79264

8 . 77 975
86.9718
0.985377
743.016

Table of Data and Estimated Values of Interest

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0	6	7.41	7.48

3	6	10.8	10.6

10	6	13.6	13.4

22	6	15.3	16.2

46	6	20.4	19.6

100	6	23.5	23.7

1.54	1.61	-0.101

1.25	1.61	0.313

1.69	1.61	0.286

1.71	1.61	-1.41

2.25	1.61	1.24

1.37	1.61	-0.33

Model Descriptions for likelihoods calculated

Model A1:	Yij	=	Mu(i) + e(ij)

Var{e(ij)}	=	Sigma/'2

Model A2:	Yij	=	Mu(i) + e(ij)

Var{e(ij)}	=	Sigma(i)^2

Model A3:	Yij	=	Mu(i) + e(ij)

Var{e(ij)}	=	Sigma/'2

This document is a draft for review purposes only and does not constitute Agency policy.

H-52 DRAFT—DO NOT CITE OR QUOTE


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Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi = Mu + e(i

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model	Log(likelihood) # Param's	AIC

A1	-33.142389	7	80.284779

A2	-31.811970	12	87.623940

A3	-33.142389	7	80.284779

fitted	-35.159023	5	80.318046

R	-80.442086	2	164.884172

Explanation of Tests

Test

1

Test

2

Test

3

Test

4

(Note:

Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.

Tests of Interest

Test

-2*log(Likelihood Ratio)

Test df

p-value

Test 1

Test 2
Test 3
Test 4

97 .2602
2.66084
2.66084
4.03327

10

5
5
2

<.0001
0.7521
0.7521
0.1331

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than .1.
model appears to be appropriate here

A homogeneous variance

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adeguately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	0.961789

BMDL =	0.211403

This document is a draft for review purposes only and does not constitute Agency policy.

H-53 DRAFT—DO NOT CITE OR QUOTE


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H.3.2.5. Figure for Additional Model Presented: Hill, Unrestricted

Hill Model with 0.95 Confidence Level

dose

21:16 04/30 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

H-54 DRAFT—DO NOT CITE OR QUOTE


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H.3.3.	Hassoun et al., 2000: TEARS

I.3.3.1.	Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

r/'-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

exponential (M2)

4

0.000

-6.143

7.977E+01

5.344E+01



exponential (M3)

4

0.000

-6.143

7.977E+01

5.344E+01

power hit bound (d = 1)

exponential
(M4)b

3

0.340

-21.181

4.916E+00

2.300E+00



exponential (M5)

2

0.240

-19.681

6.732E+00

2.470E+00



Hill

2

0.272

-19.932

6.261E+00

2.575E+00



linear

4

0.001

-7.019

6.904E+01

4.373E+01



polynomial, 5-
degree

4

0.001

-7.019

6.904E+01

4.373E+01



power

4

0.001

-7.019

6.904E+01

4.373E+01

power bound hit (power =1)

power,
unrestricted0

3

0.023

-14.993

2.902E+00

6.150E-02

unrestricted (power = 0.263)

a Constant variance model selected (p = 0.3348)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

H.3.3.2. Output for Selected Model: Exponential (M4)

Hassoun et al., 2000: TBARS

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\5\19_Has_2000_TBARsLiv_ExpCV_l.(d)

Gnuplot Plotting File:

Fri Apr 30 21:17:17 2010

TBARs, liver only (Table 2)

The form of the response function by Model:

Model 2
Model 3
Model 4
Model 5

Y[dose]
Y[dose]
Y[dose]
Y[dose]

exp{sign *	b * dose}

exp{sign *	(b * dosej^d}

[c-(c-l) *	exp{-b * dose}]

[c-(c-l) *	exp{-(b * dosej^d}

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;
sign = -1 for decreasing trend.

Model 2 is nested within Models 3 and 4.
Model 3 is nested within Model 5.

Model 4 is nested within Model 5.

This document is a draft for review purposes only and does not constitute Agency policy.

H-55 DRAFT—DO NOT CITE OR QUOTE


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Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))
rho is set to 0.

A constant variance model is fit.

Total number of dose groups = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values
Variable	Model 4

Specified

lnalpha	-1.90388

rho(S)	0

a	1.39555

b	0.0194898

c	1.97051

d	1

Parameter Estimates

Variable

lnalpha
rho
a
b
c
d

Model 4

-1. 81059

0

1.40436
0.0996859
1.74329

1

Table of Stats From Input Data

Obs Mean

Obs Std Dev

0 6

1.469

0

2915

3 6

1.549

0

5389

10 6

2 .15

0

3625

22 6

2 .28

0

2474

46 6

2 . 619

0

5168

100 6

2 . 292

0

4874

Estimated Values of Interest

Dose

Est Mean

Est Std

Scaled Residual

0

1.404

0

4044

0.3915

3

1. 674

0

4044

-0.7582

10

2 . 063

0

4044

0.527

22

2 . 332

0

4044

-0.3134

46

2 .438

0

4044

1.099

100

2.448

0

4044

-0.9458

Other models for which likelihoods are calculated:

This document is a draft for review purposes only and does not constitute Agency policy.

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Model A1:	Yij	= Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2 :	Yij	= Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + log(mean(i)) * rho)

Model R:	Yij	= Mu + e(i)

Var{e(ij)} = Sigma/'2

Likelihoods of Interest

Model	Log(likelihood)	DF	AIC

A1	16.26977	7	-18.53954

A2	19.12783	12	-14.25565

A3	16.26977	7	-18.53954

R	2.44294	2	-0.8858799

4	14.5907	4	-21.18141

Additive constant for all log-likelihoods =	-33.08. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Test

1:

Does response

and/or variances differ among Dose levels? (A2 vs. R)

Test

2 :

Are Variances

Homogeneous? (A2 vs. A1)

Test

3:

Are variances

adeguately modeled? (A2 vs. A3)

Test 6a: Does Model 4 fit the data? (A3 vs 4)

Test

Test 1
Test 2
Test 3
Test 6a

Tests of Interest

-2*log(Likelihood Ratio)

33.37
5.716
5.716
3.358

D. F.

10
5
5
3

p-value

0.000236
0.3348
0.3348
0.3396

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose
levels, it seems appropriate to model the data.

The p-value for Test 2 is greater than .1. A homogeneous
variance model appears to be appropriate here.

The p-value for Test 3 is greater than .1. The modeled
variance appears to be appropriate here.

The p-value for Test 6a is greater than .1. Model 4 seems
to adeguately describe the data.

Benchmark Dose Computations:

Specified Effect = 1.000000

Risk Type = Estimated standard deviations from control
Confidence Level = 0.950000

BMD =	4.91639

This document is a draft for review purposes only and does not constitute Agency policy.

H-57 DRAFT—DO NOT CITE OR QUOTE


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E'.MDL =	2.2 9 952

H.3.3.3. Figure for Selected Model: Exponential (M4)

Exponential Model 4 with 0.95 Confidence Level

dose

21:17 04/30 2010

H.3.3.4. Output for Additional Model Presented: Power, Unrestricted
Hassoun et al., 2000: TBARS

Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\5\19_Has_2000_TBARsLiv_PwrCV_U_l.(d)

Gnuplot Plotting File: C:\5\19_Has_2 000_TBARsLiv_PwrCV_U_l.plt

Fri Apr 30 21:17:21 2010

TBARs, liver only (Table 2)

The form of the response function is:
Y[dose] = control + slope * doseApower

Dependent variable = Mean
Independent variable = Dose
rho is set to 0
The power is not restricted
A constant variance model is fit

Total number of dose groups = 6

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
alpha =	0.178788

rho =	0 Specified

control =	1.469

slope = 0.0756538
power =	0.652114

Asymptotic Correlation Matrix of Parameter Estimates

alpha
control

The model parameter(s) -rho

have been estimated at a boundary point, or have been specified by the user,
and do not appear in the correlation matrix )

alpha
1

1. le-008

control
1. le-008
1

slope
-1.le-009
-0.75

power
-1. 5e-008
0.47

slope -1.le-009	-0.75	1	-0.91

power -1.5e-008	0.47	-0.91	1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
alpha
control
slope
power

Estimate
0.194232
1.42104
0.333105
0.262735

Std. Err.

0. 0457809
0.171077
0.166768
0. 0983956

Lower Conf. Limit
0.104503
1.08573
0. 00624603
0. 0698836

Upper Conf. Limit
0.283961
1.75634
0.659963
0. 455587

Table of Data and Estimated Values of Interest

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0
3
10
22
46
100

1.47

1. 55
2 .15
2 .28
2 . 62
2.29

1.42

1. 87
2 . 03
2 .17
2 . 33
2 . 54

0.291

0.539
0.363
0.247
0.517
0. 487

0.441

0.441
0.441
0.441
0.441
0.441

0.267
-1.76
0. 661
0. 603
1. 6
-1. 37

Model Descriptions for likelihoods calculated

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

Model A2:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2
Model A3 uses any fixed variance parameters that
were specified by the user

This document is a draft for review purposes only and does not constitute Agency policy.

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Model R:	Yi = Mu + e(i

Var{e(i) } = Sigma/'2

Likelihoods of Interest

Model	Log(likelihood) # Param's	AIC

A1	16.269770	7	-18.539539

A2	19.127827	12	-14.255654

A3	16.269770	7	-18.539539

fitted	11.496634	4	-14.993268

R	2.442940	2	-0.885880

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adeguately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Test

2

Test

3

Test

4

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	33.3698	10	0.000236

Test 2	5.71611	5	0.3348

Test 3	5.71611	5	0.3348

Test 4	9.54627	3	0.02284

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is greater than .1. A homogeneous variance
model appears to be appropriate here

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is less than .1. You may want to try a different
model

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD = 2.90232

BMDL = 0.0614 971

This document is a draft for review purposes only and does not constitute Agency policy.

H-60 DRAFT—DO NOT CITE OR QUOTE


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H.3.3.5. Figure for Additional Model Presented: Power, Unrestricted

Power Model with 0.95 Confidence Level

dose

21:17 04/30 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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H.3.4.	Kitchin and Woods, 1979: Bap Hydroxylase Activity

I.3.4.1.	Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

r/'-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

exponential (M2)

9

<0.0001

452.693

7.939E+03

3.663E+03



exponential (M3)

9

<0.0001

452.693

7.939E+03

3.663E+03

power hit bound (d = 1)

exponential (M4)

8

0.015

226.600

5.458E+00

4.099E+00



exponential

(M5)b

7

0.019

226.401

1.022E+01

4.807E+00



Hill

8

<0001

504.527

error

error

n upper bound hit (n = 18)

linear

9

<0001

299.732

8.276E+00

5.945E+00



polynomial, 8-
degree

3

<0001

20.000

error

error



power

9

<0001

299.732

8.276E+00

5.945E+00

power bound hit (power =1)

1 Non-constant variance model selected (p = <0.0001)
' Best-fitting model, BMDS output presented in this appendix

H.3.4.2. Output for Selected Model: Exponential (M5)

Kitchin and Woods, 1979: BaP Hydroxylase Activity

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\5\27_Kitchin_l979_Hydrolase_Exp_l.(d)

Gnuplot Plotting File:

Fri Apr 30 21:18:04 2010

Kitchin 1979, Tbl3, BaP hydrolase activity

The form of the response function by Model:

Model 2
Model 3
Model 4
Model 5

Y[dose]
Y[dose]
Y[dose]
Y[dose]

exp{sign *	b * dose}

exp{sign *	(b * dosej^d}

[c-(c-l) *	exp{-b * dose}]

[c-(c-l) *	exp{-(b * dosej^d}

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;
sign = -1 for decreasing trend.

Model 2 is nested within Models 3 and 4.
Model 3 is nested within Model 5.

Model 4 is nested within Model 5.

Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))

This document is a draft for review purposes only and does not constitute Agency policy.

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The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)
Total number of dose groups = 11

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values

Variable

lnalpha
rho

Model 5

-3.27793
1.92227
4 . 655
0.000177432
42 . 6316
1

Parameter Estimates

Variable

lnalpha
rho

Model 5

-2 . 64304
1.93753
5. 43423
0. 00191658
31.2033
1. 21503

Table of Stats From Input Data

Dose

Obs Mean

Obs Std Dev

0

0.6
2
4
20
60
200
600
2000
5000
2e+004

7

9

9
7

2

3
14
59
96

155
182
189

1.11

1.18
1. 4
1. 8
0.26
5

6.8
46
16.4
26
26

Estimated Values of Interest

Dose

Est Mean

Est Std

Scaled Residual

0

5. 434

1.

375

-1.166

0.6

5.478

1.

386

-0.8347

2

5. 624

1.

421

1. 514

4

5. 875

1.

483

1.787

20

8 . 525

2 .

127

-0.2115

60

i—1

G\

CO
-J

4

. 12

-1.394

200

49.41

11

. 67

1. 643

600

119. 4

27

.43

-1.705

2000

168 . 6

38

. 31

-0.7091

5000

169.6

38

. 53

0.6454

2e+004

169.6

38

. 53

1. 009

This document is a draft for review purposes only and does not constitute Agency policy.

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Other models for which	likelihoods are calculated:

Model A1:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma/'2

Model A2 :	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma(i)^2

Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= exp(lalpha + log(mean(i)) * rho)

Model R:	Yij	= Mu + e(i)

Var{e(ij)}	= Sigma/'2

Likelihoods of Interest

Model	Log(likelihood)	DF	AIC

A1	-158.1306	12	340.2613

A2	-84.80028	22	213.6006

A3	-98.82189	13	223.6438

R	-234.6252	2	473.2504

5	-107.2005	6	226.4011

Additive constant for all log-likelihoods =	-45.03. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Test 1: Does response and/or variances differ among Dose levels? (A2 vs. R)

Test 2: Are Variances Homogeneous? (A2 vs. A1)

Test 3: Are variances adeguately modeled? (A2 vs. A3)

Test 7a: Does Model 5 fit the data? (A3 vs 5)

Test

Test 1
Test 2
Test 3
Test 7a

Tests of Interest
-2*log(Likelihood Ratio)

299.6

146.7
28 . 04
16.76

D. F.

20
10
9
7

p-value

<	0.0001

<	0.0001
0.0009381

0.01903

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose
levels, it seems appropriate to model the data.

The p-value for Test 2 is less than .1. A non-homogeneous
variance model appears to be appropriate.

The p-value for Test 3 is less than .1. You may want to
consider a different variance model.

The p-value for Test 7a is less than .1. Model 5 may not adeguately
describe the data; you may want to consider another model.

Benchmark Dose Computations:

Specified Effect = 1.000000

Risk Type = Estimated standard deviations from control
Confidence Level = 0.950000

This document is a draft for review purposes only and does not constitute Agency policy.

H-64 DRAFT—DO NOT CITE OR QUOTE


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BMD =	10.2235

BMDL =	4 . 80673

H.3.4.3. Figure for Selected Model: Exponential (M5)

Exponential Model 5 with 0.95 Confidence Level

a>

CO
c
o

Q.

CO
CD

a:

c
m

CD

250

200

150

100

50

Exponential

S/IDL

BMD

5000

10000
dose

15000

20000

21:18 04/30 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

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H.3.5.	National Toxicology Program, 2006: Liver EROD 53 Weeks

I.3.5.1.	Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

x2p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

exponential (M2)

4

<0.0001

210.749

4.068E+01

2.856E+01



exponential (M3)

4

<0.0001

210.749

4.068E+01

2.856E+01

power hit bound (d = 1)

exponential (M4)

3

0.071

98.835

1.912E-01

1.384E-01



exponential (M5)

2

0.040

100.232

2.394E-01

1.433E-01



Hill b

2

0.219

96.847

3.823E-01

2.336E-01



linear

4

<0001

203.577

2.076E+01

8.128E+00



polynomial, 5-
degree

4

<0001

203.577

2.076E+01

8.128E+00



power

4

<0001

203.577

2.076E+01

8.128E+00

power bound hit (power = 1)

1 Non-constant variance model selected (p = <.0001)
' Best-fitting model, BMDS output presented in this appendix

H.3.5.2. Output for Selected Model: Hill

National Toxicology Program, 2006: Liver EROD 53 Weeks

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\5\46_NTP_2006_ERODliv53_Hill_l.(d)

Gnuplot Plotting File: C:\5\4 6_NTP_2006_ERODliv53_Hill_l.plt

Sun May 02 15:05:02 2010

0

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = Mean
Independent variable = Dose

Power parameter restricted to be greater than 1

The variance is to be modeled as Var(i) = exp(lalpha + rho * ln(mean(i)))
Total number of dose groups = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

This document is a draft for review purposes only and does not constitute Agency policy.

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lalpha
rho

intercept

1.59547

0

3. 614
17 .599
1.38542
8.70663

Asymptotic Correlation Matrix of Parameter Estimates

lalpha
rho

intercept

lalpha
1

-0. 96
-0.16
0. 086
-0.057
0. 041

rho

-0. 96
1

0.14
-0.11
0. 059
-0.045

intercept

-0.16
0.14
1

-0.18
0.13
0. 069

v

0. 086
-0.11
-0.18
1

-0.72
0.84

n

-0.057
0. 059
0.13
-0.72
1

-0.79

k

0. 041
-0.045
0. 069
0.84
-0.79
1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
lalpha
rho

intercept

Estimate
-4 .86522
2.26949
3. 62909
17.9802
1.4314
5.58259

Std. Err.
0.741624
0.287245
0.133823
0.989132
0.162447
0.717084

Lower Conf. Limit
-6.31878
1.7065
3.3668
16.0416
1.11301
4 .17713

Upper Conf. Limit

-3.41167
2 . 83248
3. 89138
19.9189
1.74979
6.98805

Table of Data and Estimated Values of Interest

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0

2 .14
7 .14
15.7
32 . 9
71. 4

3. 61

7 . 27
14 . 8
17 . 3
20.6
21. 2

3. 63

7 . 27
14 . 2
18 . 3
20.3
21. 2

0.486
0.557
1. 61
1.59
3. 05
3. 82

0.379

0. 833
1.78
2 . 37
2 . 67
2 . 8

-0.113

0. 0203
0. 911
-1.19
0.304
0.0606

Model Descriptions for likelihoods calculated

Model A1:	Yij

Var{e(ij ) }

Model A2:	Yij

Var{e(ij ) }

Mu(i) + e(ij ;
Sigma/N2

Mu(i) + e(ij ;

Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi

Var{e(i)}

Mu + e(i)
Sigma/N2

This document is a draft for review purposes only and does not constitute Agency policy.

H-67 DRAFT—DO NOT CITE OR QUOTE


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Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1 -59.086537	7	132.173073

A2 -37.515858	12	99.031716

A3 -40.906180	8	97.812359

fitted -42.423278	6	96.846556

R	-116.710291	2	237.420582

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adequately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.

Test

2

Test

3

Test

4

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	158.389	10	<.0001

Test 2	43.1414	5	<.0001

Test 3	6.78064	4	0.1479

Test 4	3.0342	2	0.2193

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is greater than .1. The model chosen seems
to adequately describe the data

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	0.382287

BMDL =	0.233611

This document is a draft for review purposes only and does not constitute Agency policy.

H-68 DRAFT—DO NOT CITE OR QUOTE


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1 H.3.5.3. Figure for Selected Model: Hill

Hill Model with 0.95 Confidence Level

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

H-69 DRAFT—DO NOT CITE OR QUOTE


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H.3.6.	National Toxicology Program, 2006: Lung Erod 53 Weeks

I.3.6.1.	Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

x2p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

exponential (M2)

4

<0.0001

316.324

8.979E+01

5.757E+01



exponential (M3)

4

<0.0001

316.324

8.979E+01

5.757E+01

power hit bound (d = 1)

exponential
(M4)b

3

0.421

255.120

8.746E-02

5.370E-02



exponential (M5)

2

0.276

256.882

6.769E-01

5.491E-02



Hill

2

0.275

256.882

1.454E+00

1.138E-01



linear

4

<0001

315.961

8.550E+01

4.502E+01



polynomial, 5-
degree

4

<0001

315.961

8.550E+01

4.502E+01



power

4

<0001

315.961

8.550E+01

4.502E+01

power bound hit (power =1)

power,
unrestricted0

3

0.037

260.794

2.688E-10

2.688E-10

unrestricted (power = 0.129)

a Non-constant variance model selected (p = <0.0001)
b Best-fitting model, BMDS output presented in this appendix
0 Alternate model, BMDS output also presented in this appendix

H.3.6.2. Output for Selected Model: Exponential (M4)

National Toxicology Program, 2006: Lung EROD 53 Weeks

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\5\52_NTP_2006_LungEROD53_Exp_l.(d)

Gnuplot Plotting File:

Fri Apr 30 21:22:36 2010

Tbl 12, Week 53, Lung Microsomes EROD

The form of the response function by Model:

Model 2
Model 3
Model 4
Model 5

Y[dose]
Y[dose]
Y[dose]
Y[dose]

exp{sign *	b * dose}

exp{sign *	(b * dosej^d}

[c-(c-l) *	exp{-b * dose}]

[c-(c-l) *	exp{-(b * dosej^d}

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;
sign = -1 for decreasing trend.

Model 2 is nested within Models 3 and 4.
Model 3 is nested within Model 5.

Model 4 is nested within Model 5.

This document is a draft for review purposes only and does not constitute Agency policy.

H-70 DRAFT—DO NOT CITE OR QUOTE


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Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)
Total number of dose groups = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values

Variable

lnalpha
rho

Model 4

-0.80064
1.47683
2 .86045
0.054659
16.0581
1

Parameter Estimates
Variable	Model 4

lnalpha	-1.15021

rho	1.63127

a	3.06838

b	0.414677

c	13.847

d	1

Table of Stats From Input	Data

Dose	N	Obs Mean	Obs Std Dev

0	8	3.011	1.584

2.14	8	27.15	5.269

7.14	8	42.85	11.15

15.7	8	36.57	12.99

32.9	8	43.75	18.55

71.4	8	43.71	6.322

Estimated Values of	Interest
Dose Est Mean Est Std Scaled Residual

0	3.068	1.404	-0.1156

2.14	26.26	8.088	0.3116

7.14	40.45	11.5	0.5901

15.7	42.43	11.96	-1.386

32.9	42.49	11.98	0.2972

71.4	42.49	11.98	0.2894

Other models for which likelihoods are calculated:

Model A1:	Yij = Mu(i) + e(ij)

Var{e(ij)} = Sigma/'2

This document is a draft for review purposes only and does not constitute Agency policy.

H-71 DRAFT—DO NOT CITE OR QUOTE


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Model A2 :	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma(i)^2

Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= exp(lalpha + log(mean(i)) * rho)

Model R:	Yij	= Mu + e(i)

Var{e(ij)}	= Sigma/'2

Likelihoods of Interest

Model	Log(likelihood)	DF	AIC

A1	-135.2677	7	284.5353

A2	-115.6885	12	255.3771

A3	-121.1517	8	258.3034

R	-162.0902	2	328.1805

4	-122.5601	5	255.1202

-44.11. This constant added to the

Additive constant for all log-likelihoods =
above values gives the log-likelihood including the term that does not
depend on the model parameters.

Test

1:

Test

2 :

Test

3:

Test

6a

Explanation of Tests

Does response and/or variances differ among Dose levels? (A2 vs. R)

Are Variances Homogeneous? (A2 vs. A1)

Are variances adeguately modeled? (A2 vs. A3)

Does Model 4 fit the data? (A3 vs 4)

Test

Test 1
Test 2
Test 3
Test 6a

Tests of Interest

-2*log(Likelihood Ratio)

92 . 8
39.16
10. 93
2 . 817

10
5
4
3

p-value

0.0001
0.0001
0.0274
0.4207

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose
levels, it seems appropriate to model the data.

The p-value for Test 2 is less than .1. A non-homogeneous
variance model appears to be appropriate.

The p-value for Test 3 is less than .1. You may want to
consider a different variance model.

The p-value for Test 6a is greater than .1. Model 4 seems
to adeguately describe the data.

Benchmark Dose Computations:

Specified Effect = 1.000000

Risk Type = Estimated standard deviations from control

Confidence Level = 0.950000

BMD = 0.0874595
BMDL = 0.0537035

This document is a draft for review purposes only and does not constitute Agency policy.

H-72 DRAFT—DO NOT CITE OR QUOTE


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H.3.6.3. Figure for Selected Model: Exponential (M4)

Exponential Model 4 with 0.95 Confidence Level

60

Exponential

50

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BVIDLBMD

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21:22 04/30 2010

dose

H.3.6.4. Output for Additional Model Presented: Power, Unrestricted

National Toxicology Program, 2006: Lung EROD 53 Weeks

Power Model. (Version: 2.15; Date: 04/07/2008)

Input Data File: C:\5\52_NTP_2006_LungEROD53_Pwr_U_l.(d)

Gnuplot Plotting File: C:\5\52_NTP_2006_LungEROD53_Pwr_U_l.plt

Fri Apr 30 21:22:40 2010

Tbl 12, Week 53, Lung Microsomes EROD

The form of the response function is:
Y[dose] = control + slope * doseApower

Dependent variable = Mean
Independent variable = Dose
The power is not restricted

The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)
Total number of dose groups = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008

This document is a draft for review purposes only and does not constitute Agency policy.

H-73 DRAFT—DO NOT CITE OR QUOTE


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Parameter

has been set to: le-008

Default Initial Parameter Values

lalpha =	4 .76968

rho =	0

control =	3.011

slope =	24 . 7003

power =	0.132 9 96

Asymptotic Correlation Matrix of Parameter Estimates

lalpha
rho
control
slope
power

lalpha
1

-0. 96
-0.48
0.11
-0.048

rho

-0. 96
1

0.45
-0.15
0. 053

control

-0.48
0.45
1

-0.15
0. 05

slope
0.11
-0.15
-0.15
1

-0. 92

power

-0.048
0. 053
0. 05
-0. 92
1

Parameter Estimates

Variable
lalpha
rho
control
slope
power

Estimate

-1.03242
1.63031
3.01793
25.144
0.128894

Std. Err.

0. 815871
0.239764
0.518146
3.39289
0.0448391

95.0% Wald Confidence Interval
Lower Conf. Limit Upper Conf. Limit

-2 . 6315
1.16038
2.00238
18.494
0.041011

0.566654
2 .10024
4.03348
31.7939
0 . 216777

Table of Data and Estimated Values of Interest

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0

2 .14
7 .14
15.7
32 . 9
71. 4

3. 01

27 .1
42 . 8
3 6.6
43.7
43.7

3. 02
30. 8
35. 4
38 . 9
42 . 5
46.6

I.	58

5.27

II.	2
13

18 . 5
6.32

I.47

9.74
10. 9

II.	8
12 . 7
13.7

-0.0133
-1. 05
1. 92
-0.553
0.286
-0.598

Model Descriptions for likelihoods calculated

Model A1:	Yij

Var{e(ij ) }

Model A2:	Yij

Var{e(ij ) }

Mu(i) + e(ij ;
Sigma/N2

Mu(i) + e(ij ;

Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi

Var{e(i)}

Mu + e(i)
Sigma/N2

This document is a draft for review purposes only and does not constitute Agency policy.

H-74 DRAFT—DO NOT CITE OR QUOTE


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Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1	-135.267662	7	284.535325

A2	-115.688533	12	255.377067

A3	-121.151707	8	258.303413

fitted	-125.397022	5	260.794043

R	-162.090242	2	328.180484

Explanation of Tests

Test 1:

Test

2

Test

3

Test

4

Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Are Variances Homogeneous? (A1 vs A2)

Are variances adequately modeled? (A2 vs. A3)

Does the Model for the Mean Fit? (A3 vs. fitted)

When rho=0 the results of Test 3 and Test 2 will be the same.'

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	92.8034	10	<.0001

Test 2	39.1583	5	<.0001

Test 3	10.9263	4	0.0274

Test 4	8.49063	3	0.03689

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is less than .1. You may want to consider a
different variance model

The p-value for Test 4 is less than .1. You may want to try a different
model

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD = 2 . 68823e-010

BMDL = 2 . 68823e-010

This document is a draft for review purposes only and does not constitute Agency policy.

H-75 DRAFT—DO NOT CITE OR QUOTE


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H.3.6.5. Figure for Additional Model Presented: Power, Unrestricted

Power Model with 0.95 Confidence Level

a>

CO
c
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dose

21:22 04/30 2010

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

H-76 DRAFT—DO NOT CITE OR QUOTE


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H.3.7.	National Toxicology Program, 2006: Labeling Index 31 Weeks

I.3.7.1.	Summary Table of BMDS Modeling Results

Model3

Degrees
of

Freedom

x2p-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

exponential
(M2)b

4

0.000

47.304

2.336E+01

1.867E+01



exponential (M3)

4

0.000

47.304

2.336E+01

1.867E+01

power hit bound (d = 1)

exponential (M4)

3

<0.0001

53.331

1.233E+01

7.562E+00



exponential (M5)

2

<0.0001

51.057

3.279E+01

2.055E+01



Hill

3

0.000

49.057

3.277E+01

error

n upper bound hit (n = 18)

linear

4

<0001

51.331

1.233E+01

7.563E+00



polynomial, 5-
degree

3

0.000

48.698

2.510E+01

1.192E+01



power

3

<0001

49.826

3.238E+01

1.723E+01



1 Non-constant variance model selected (p = <0.0001)
' Best-fitting model, BMDS output presented in this appendix

H.3.7.2. Output for Selected Model: Exponential (M2)

National Toxicology Program, 2006: Labeling Index 31 Weeks

Exponential Model. (Version: 1.61; Date: 7/24/2009)

Input Data File: C:\5\38_NTP_2006_HepIndex_Exp_l.(d)

Gnuplot Plotting File:

Fri Apr 30 21:23:28 2010

Tbl 11, 31wk, Hep Cell Proliferation Labeling Index

The form of the response function by Model:

Model 2
Model 3
Model 4
Model 5

Y[dose]
Y[dose]
Y[dose]
Y[dose]

exp{sign *	b * dose}

exp{sign *	(b * dosej^d}

[c-(c-l) *	exp{-b * dose}]

[c-(c-l) *	exp{-(b * dosej^d}

Note: Y[dose] is the median response for exposure = dose;
sign = +1 for increasing trend in data;
sign = -1 for decreasing trend.

Model 2 is nested within Models 3 and 4.
Model 3 is nested within Model 5.

Model 4 is nested within Model 5.

Dependent variable = Mean
Independent variable = Dose

Data are assumed to be distributed: normally
Variance Model: exp(lnalpha +rho *ln(Y[dose]))

This document is a draft for review purposes only and does not constitute Agency policy.

H-77 DRAFT—DO NOT CITE OR QUOTE


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The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)
Total number of dose groups = 6

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

MLE solution provided: Exact

Initial Parameter Values
Variable	Model 2

lnalpha	-0.674004

rho	2.29189

a	0.576363

b	0.0266174

c	0

d	1

Parameter Estimates

Variable	Model 2

lnalpha	-0.471424

rho	1.902 98

a	0.616539

b	0.0253715

c	0

d	1

Table of Stats From Input Data

Dose N Obs Mean	Obs Std Dev

0	9

2.14	10

7.14	10

15.7	10

32.9	10

71.4	10

Estimated Values of Interest
Dose	Est Mean	Est Std	Scaled Residual

0.327
0. 852
0. 956

0.792

1.	333
3.846

0.189
0.6514
0.7368
0.4617
1.123
3. 08

0	0.6165	0.4986	-1.742

2.14	0.6509	0.5251	1.211

7.14	0.739	0.5924	1.158

15.7	0.9182	0.7284	-0.548

32.9	1.421	1.103	-0.2511

71.4	3.773	2.795	0.08251

Other models for which	likelihoods are calculated:

Model A1:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma/'2

Model A2:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= Sigma(i)^2

Model A3:	Yij	= Mu(i) + e(ij)

Var{e(ij)}	= exp(lalpha + log(mean(i)) * rho)

This document is a draft for review purposes only and does not constitute Agency policy.

H-78 DRAFT—DO NOT CITE OR QUOTE


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Model R:	Yij = Mu + e(i)

Var{e(ij)} = Sigma/'2

Likelihoods of Interest

Model	Log(likelihood)	DF	AIC

A1	-47.23498	7	108.47

A2	-8.679256	12	41.35851

A3	-8.980651	8	33.9613

R	-63.44829	2	130.8966

2	-19.65195	4	47.30389

Additive constant for all log-likelihoods =	-54.22. This constant added to the

above values gives the log-likelihood including the term that does not
depend on the model parameters.

Explanation of Tests

Does response and/or variances differ among Dose levels? (A2

Are Variances Homogeneous? (A2 vs. A1)

Are variances adeguately modeled? (A2 vs. A3)

Does Model 2 fit the data? (A3 vs. 2)

Tests of Interest
Test	-2*log(Likelihood Ratio)	D. F.	p-value

Test 1	109.5	10	< 0.0001

Test 2	77.11	5	< 0.0001

Test 3	0.6028	4	0.9628

Test 4	21.34	4	0.0002708

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose
levels, it seems appropriate to model the data.

The p-value for Test 2 is less than .1. A non-homogeneous
variance model appears to be appropriate.

The p-value for Test 3 is greater than .1. The modeled
variance appears to be appropriate here.

The p-value for Test 4 is less than .1. Model 2 may not adeguately
describe the data; you may want to consider another model.

Benchmark Dose Computations:

Specified Effect = 1.000000

Risk Type = Estimated standard deviations from control

Confidence Level = 0.950000

BMD =	23.3586

BMDL =	18.6683

This document is a draft for review purposes only and does not constitute Agency policy.

H-79 DRAFT—DO NOT CITE OR QUOTE


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1 H.3.7.3. Figure for Selected Model: Exponential (M2)

Exponential Model 2 with 0.95 Confidence Level

0	10	20	30	40	50	60	70

dose

2	21:23 04/30 2010

3

t	i	r

Exponential 	

BMDL

BMD

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

H-80 DRAFT—DO NOT CITE OR QUOTE


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H.3.8.	Vanden Heuvel et al., 1994: Hepatic CYP1A1 Mrna Expression

I.3.8.1.	Summary Table of BMDS Modeling Results	

Model3

Degrees
of

Freedom

r/'-

Value

AIC

BMD

(ng/kg-d)

BMDL

(ng/kg-d)

Notes

exponential (M2)

5

<0.0001

1164.377

4.699E+03

1.729E+03



exponential (M3)

5

<0.0001

1164.377

4.699E+03

1.729E+03

power hit bound (d = 1)

exponential (M4)

4

<0.0001

661.006

4.550E-01

2.643E-01



exponential (M5)

3

<0.0001

635.327

1.516E+01

1.046E+01



Hill b

3

<0001

662.251

8.091E-01

4.844E-01



linear

5

<0001

667.554

4.953E-01

3.093E-01



polynomial, 6-
degree

1

<0001

715.412

5.774E+03

1.204E+01



power

4

<0001

669.441

5.571E-01

3.204E-01



a Non-constant variance model selected (p = <0.0001)
b Best-fitting model, BMDS output presented in this appendix

H.3.8.2. Output for Selected Model: Hill

Vanden Heuvel et al., 1994: Hepatic CYP1 Al mRNA Expression

Hill Model. (Version: 2.14; Date: 06/26/2008)

Input Data File: C:\Usepa\BMDS21\Data\hil_Vanden_mRNA_Setting.(d)

Gnuplot Plotting File: C:\Usepa\BMDS21\Data\hil_Vanden_mRNA_Setting.plt

Wed May 19 14:25:06 2010

BMDS Model Run

The form of the response function is:

Y[dose] = intercept + v*doseAn/(kAn + doseAn)

Dependent variable = mRNA mean

Independent variable = d

Power parameter is not restricted

The variance is to be modeled as Var(i) = exp(lalpha + rho * ln(mean(i)))
Total number of dose groups = 7

Total number of records with missing values = 0
Maximum number of iterations = 250

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values

This document is a draft for review purposes only and does not constitute Agency policy.

H-81 DRAFT—DO NOT CITE OR QUOTE


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lalpha
rho

intercept

18.2064

0

5.4
3 6 6 9 4 . 6
0.720907
18830.3

Asymptotic Correlation Matrix of Parameter Estimates

lalpha
rho

intercept

lalpha
1

-0.89
-0.41
0.37
0.7
-0.2

rho

-0.89
1

0.29
-0.54
-0.75
0.24

intercept

-0.41
0.29
1

-0.11
0.13
-0.034

v

0.37
-0.54
-0.11
1

0.21
0.57

n

0.7
-0.75
0.13
0.21
1

-0.53

k

-0.2

0.24
-0.034
0.57
-0.53
1

Parameter Estimates

95.0% Wald Confidence Interval

Variable
lalpha
rho

intercept

Estimate
-0.28219
2.05171
5.4299
36598.9
1.13992
2012.71

Std. Err.

0.146654
1.14997
13930.2
0.0919476
881.73

Lower Conf. Limit
-1.71928
1.76427
3.17599
9296.23
0. 959705
284 . 554

Upper Conf. Limit
1.1549
2.33915
7.68381
63901.7
1. 32013
3740.87

Table of Data and Estimated Values of Interest

Dose

Obs Mean

Est Mean Obs Std Dev Est Std Dev Scaled Res.

0

0.1

1
10

100
1000
le+004

13

5
12
7
7
11

5.4

7 . 2
14 . 8
12 . 8
536
1. 8e + 004
3. 67e + 004

5.43

5.88
11. 7
91. 8
1.16e + 003
1.14e + 004
3 .15e + 004

3. 61

5.59
14 . 9
4 . 5
320

1.52e+004
2 . 21e + 004

4 . 93

5.35
10.8
89.6
1. 21e + 003
1. 26e + 004
3.58e+004

-0.0219
0.55
0. 991
-2 . 33
-1. 37
1.75
0.323

Model Descriptions for likelihoods calculated

Model A1:	Yij

Var{e(ij ) }

Model A2:	Yij

Var{e(ij ) }

Mu(i) + e(ij ;
Sigma/N2

Mu(i) + e(ij ;

Sigma(i)^2

Model A3:	Yij = Mu(i) + e(ij)

Var{e(ij)} = exp(lalpha + rho*ln(Mu(i)))
Model A3 uses any fixed variance parameters that
were specified by the user

Model R:	Yi

Var{e(i)}

Mu + e(i)
Sigma/N2

This document is a draft for review purposes only and does not constitute Agency policy.

H-82 DRAFT—DO NOT CITE OR QUOTE


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Likelihoods of Interest

Model	Log(likelihood)	# Param's	AIC

A1	-572.470944	8	1160.941889

A2	-290.799287	14	609.598575

A3	-293.809342	9	605.618684

fitted	-325.125462	6	662.250924

R	-603.663396	2	1211.326792

Explanation of Tests

Test 1: Do responses and/or variances differ among Dose levels?

(A2 vs. R)

Test 2: Are Variances Homogeneous? (A1 vs A2)

Test 3: Are variances adequately modeled? (A2 vs. A3)

Test 4: Does the Model for the Mean Fit? (A3 vs. fitted)

(Note: When rho=0 the results of Test 3 and Test 2 will be the same.)

Tests of Interest

Test	-2*log(Likelihood Ratio)	Test df	p-value

Test 1	625.728	12	<.0001

Test 2	563.343	6	<.0001

Test 3	6.02011	5	0.3043

Test 4	62.6322	3	<.0001

The p-value for Test 1 is less than .05. There appears to be a
difference between response and/or variances among the dose levels
It seems appropriate to model the data

The p-value for Test 2 is less than .1. A non-homogeneous variance
model appears to be appropriate

The p-value for Test 3 is greater than .1. The modeled variance appears
to be appropriate here

The p-value for Test 4 is less than .1. You may want to try a different
model

Benchmark Dose Computation
Specified effect =	1

Risk Type	=	Estimated standard deviations from the control mean

Confidence level =	0.95

BMD =	0.809125

BMDL =	0.4 84 455

This document is a draft for review purposes only and does not constitute Agency policy.

H-83 DRAFT—DO NOT CITE OR QUOTE


-------
1 H.3.8.3. Figure for Selected Model: Exponential (M5)

Hill Model with 0.95 Confidence Level

dose

2	14:25 05/19 2010

3

4

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

H-84 DRAFT—DO NOT CITE OR QUOTE


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DRAFT

DO NOT CITE OR QUOTE

May 2010
External Review Draft

APPENDIX I

Effect of Background Exposure on
Benchmark-Dose Modeling

NOTICE

THIS DOCUMENT IS AN EXTERNAL REVIEW DRAFT. It has not been formally released
by the U.S. Environmental Protection Agency and should not at this stage be construed to
represent Agency policy. It is being circulated for comment on its technical accuracy and policy
implications.

National Center for Environmental Assessment
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, OH


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CONTENTS—APPENDIX I: Effect of Background Exposure on Benchmark-Dose

Modeling

LIST OF FIGURES	I-ii

APPENDIX I. EFFECT OF BACKGROUND EXPOSURE ON BENCHMARK-DOSE

MODELING	1-1

1.1.	NTP, 2006 (CHOLANGIOCARCINOMAS): UNADJUSTED BLOOD
CONCENTRATIONS	I-1

1.2.	NTP, 2006 (CHOLANGIOCARCINOMAS): BACKGROUND DOSE =

MEASURED TCDD CONCENTRATION ONLY	1-4

1.3.	NTP, 2006 (CHOLANGIOCARCINOMAS): BACKGROUND DOSE =

MEASURED TEQ CONCENTRATION (TCDD, PECDF, AND PCB-126)	1-7

1.4.	NTP, 2006 (CHOLANGIOCARCINOMAS): BACKGROUND DOSE = 2x
MEASURED TEQ CONCENTRATION (TCDD, PECDF, AND PCB-126)	I-10

1.5.	NTP, 2006 (CHOLANGIOCARCINOMAS): BACKGROUND DOSE = 10x
MEASURED TCDD CONCENTRATION	1-13

1.6.	REFERENCE	1-15

LIST OF FIGURES

1-1. NTP, 2006: Unadjusted blood concentrations (cholangiocarcinomas)	1-3

1-2. NTP, 2006 (cholangiocarcinomas): Background dose = measured TCDD

concentration only	1-6

1-3. NTP, 2006 (cholangiocarcinomas): Background dose = measured TEQ

concentration (TCDD, PeCDF, and PCB-126)	1-9

1-4. NTP, 2006 (cholangiocarcinomas): Background dose = 2x measured TEQ

concentration (TCDD, PeCDF, and PCB-126)	1-12

1-5. NTP, 2006 (cholangiocarcinomas): Background dose = 10x measured TCDD

concentration	1-15

This document is a draft for review purposes only and does not constitute Agency policy.

I-ii DRAFT—DO NOT CITE OR QUOTE


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APPENDIX I. EFFECT OF BACKGROUND EXPOSURE ON BENCHMARK-DOSE

MODELING

1.1. NTP, 2006 (CHOLANGIOCARCINOMAS): UNADJUSTED BLOOD
CONCENTRATIONS

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\Usepa\BMDS21\Data\msc_NTP_2006_carcin_Setting.(d)

Gnuplot Plotting File: C:\Usepa\BMDS21\Data\msc_NTP_2 00 6_carcin_Setting.plt

Wed Apr 14 12:59:57 2010

BMDS Model Run

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(

-betal*dose/sl-beta2*dose/s2-beta3* dose^)]

The parameter betas are restricted to be positive

Dependent variable = cholang
Independent variable = bl_nom

Total number of observations = 6

Total number of records with missing values = 0

Total number of parameters in model = 4

Total number of specified parameters = 0

Degree of polynomial = 3

Maximum number of iterations = 25 0

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
Background =	0

Beta (1) =	0

Beta (2) =	0

Beta (3) = 2.44609e-005

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -Background -Beta(l) -Beta(2)

have been estimated at a boundary point, or have been specified by

the user,

and do not appear in the correlation matrix )

Beta (3)

Beta(3)	1

This document is a draft for review purposes only and does not constitute Agency policy.

1-1 DRAFT—DO NOT CITE OR QUOTE


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Parameter Estimates

95.0% Wald Confidence

Interval

Variable	Estimate	Std. Err.	Lower Conf. Limit Upper Conf.

Limit

Background

0







Beta (1)

0







Beta (2)

0







Beta (3)

2.30992e-005







* - Indicates that this value is not calculated.

Model
Full model
Fitted model
Reduced model

Analysis of Deviance Table
#

Log(likelihood)
-55.408
-55 .7584
-96.9934

Param's
6
1
1

Deviance Test d.f.

0.700706
83.1708

P-value

0.9829
<.0001

AIC:

113.517

Goodness of Fit

Scaled

Dose	Est._Prob. Expected Observed	Size	Residual

0.0000

0.0000

0. 000

0. 000

49

0.000

2.5600

0.0004

0. 019

0. 000

48

-0.136

5.6900

0.0042

0.195

0. 000

46

-0.443

9.7900

0.0214

1. 072

1. 000

50

-0.070

16.6000

0.1003

4.913

4.000

49

-0.434

29.7000

0.4540

24.063

25.000

53

0.259

Chi^2 = 0.48	d.f. = 5	P-value = 0.9930

Benchmark Dose Computation

Specified effect =	0.01

Risk Type =	Extra risk

Confidence level =	0.95

BMD =	7.57754

BMDL =	4.13907

BMDU =	8.42931

Taken together, (4.13907, 8.42931) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor =	0.002416

This document is a draft for review purposes only and does not constitute Agency policy.

1-2 DRAFT—DO NOT CITE OR QUOTE


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Multistage Cancer Model with 0.95 Confidence Level

dose

12:59 04/14 2010

Figure 1-1. NTP, 2006: Unadjusted blood concentrations
(cholangiocarcinomas).

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

1-3	DRAFT—DO NOT CITE OR QUOTE


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1.2. NTP, 2006 (CHOLANGIOCARCINOMAS): BACKGROUND DOSE = MEASURED
TCDD CONCENTRATION ONLY

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\Usepa\BMDS21\Data\msc_NTP_2006_carcin_Setting.(d)

Gnuplot Plotting File: C:\Usepa\BMDS21\Data\msc_NTP_2 00 6_carcin_Setting.plt

Fri Apr 16 15:47:08 2010

BMDS Model Run

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(

-betal*dose/sl-beta2*dose/s2-beta3* doseA3)]

The parameter betas are restricted to be positive

Dependent variable = cholang
Independent variable = bl_TCDDadj

Total number of observations = 6

Total number of records with missing values = 0

Total number of parameters in model = 4

Total number of specified parameters = 0

Degree of polynomial = 3

Maximum number of iterations = 25 0

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
Background =	0

Beta (1) =	0

Beta (2) =	0

Beta (3) = 2.43074e-005

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -Background -Beta(l) -Beta(2)

have been estimated at a boundary point, or have been specified by

the user,

and do not appear in the correlation matrix )

Beta (3)

Beta(3)	1

Parameter Estimates

This document is a draft for review purposes only and does not constitute Agency policy.

1-4 DRAFT—DO NOT CITE OR QUOTE


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95.0% Wald Confidence

Interval

Variable Estimate Std. Err.	Lower Conf. Limit Upper Conf.

Limit

Background 0 *	* *

Beta (1) 0 *	* *

Beta (2) 0 *	* *

Beta (3) 2.29144e-005 *	* *

* - Indicates that this value is not calculated.

Model
Full model
Fitted model
Reduced model

Analysis of Deviance Table
#

Log(likelihood)
-55.408
-55.771
-96.9934

Param's
6
1
1

Deviance Test d.f.

0.726
83.1708

P-value

0.9815
<.0001

AIC:

113.542

Goodness of Fit

Scaled

Dose	Est._Prob. Expected Observed	Size	Residual

0.0640

0.0000

0. 000

0. 000

49

-0.001

2.6240

0.0004

0. 020

0. 000

48

-0.141

5.7540

0.0044

0.200

0. 000

46

-0.449

9.8540

0.0217

1. 084

1. 000

50

-0.082

16.6640

0.1006

4.930

4.000

49

-0.442

29.7640

0.4535

24.035

25.000

53

0.266

Chi^2 = 0.49	d.f. = 5	P-value = 0.9924

Benchmark Dose Computation
Specified effect =	0.01

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	7.59785

BMDL =	4.19355

BMDU =	8.4518 8

Taken together, (4.19355, 8.45188) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00238461

This document is a draft for review purposes only and does not constitute Agency policy.

1-5 DRAFT—DO NOT CITE OR QUOTE


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Multistage Cancer Model with 0.95 Confidence Level

dose

15:47 04/16 2010

Figure 1-2. NTP, 2006 (cholangiocarcinomas): Background dose = measured
TCDD concentration only.

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

1-6 DRAFT—DO NOT CITE OR QUOTE


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1.3. NTP, 2006 (CHOLANGIOCARCINOMAS): BACKGROUND DOSE = MEASURED
TEQ CONCENTRATION (TCDD, PECDF, AND PCB-126)

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\Usepa\BMDS21\Data\msc_NTP_2006_carcin_Setting.(d)

Gnuplot Plotting File: C:\Usepa\BMDS21\Data\msc_NTP_2 00 6_carcin_Setting.plt

Fri Apr 16 15:50:00 2010

BMDS Model Run

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(

-betal*dose/sl-beta2*dose/s2-beta3* doseA3)]

The parameter betas are restricted to be positive

Dependent variable = cholang
Independent variable = bl_TEQadj

Total number of observations = 6

Total number of records with missing values = 0

Total number of parameters in model = 4

Total number of specified parameters = 0

Degree of polynomial = 3

Maximum number of iterations = 25 0

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
Background =	0

Beta (1) =	0

Beta (2) =	0

Beta(3) = 2.40088e-005

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -Background -Beta(l) -Beta(2)

have been estimated at a boundary point, or have been specified by

the user,

and do not appear in the correlation matrix )

Beta (3)

Beta(3)	1

Parameter Estimates

This document is a draft for review purposes only and does not constitute Agency policy.

1-7 DRAFT—DO NOT CITE OR QUOTE


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43

44

45

46

47

48

49

50

51

52

53

54

55

56

57

95.0% Wald Confidence

Interval

Variable Estimate Std. Err.	Lower Conf. Limit Upper Conf.

Limit

Background 0 *	* *

Beta (1) 0 *	* *

Beta (2) 0 *	* *

Beta (3) 2.25556e-005 *	* *

* - Indicates that this value is not calculated.

Model
Full model
Fitted model
Reduced model

Analysis of Deviance Table
#

Log(likelihood)
-55.408
-55.7969
-96.9934

Param's
6
1
1

Deviance Test d.f.

0.777718
83.1708

P-value

0.9784
<.0001

AIC:

113.594

Goodness of Fit

Scaled

Dose	Est._Prob. Expected Observed	Size	Residual

0.1900

0.0000

0. 000

0. 000

49

-0.003

2.7500

0.0005

0. 023

0. 000

48

-0.150

5.8800

0.0046

0.210

0. 000

46

-0.460

9.9800

0.0222

1.109

1. 000

50

-0.104

16.7900

0.1013

4.962

4.000

49

-0.455

29.8900

0.4525

23.981

25.000

53

0.281

Chi^2 = 0.53	d.f. = 5	P-value = 0.9909

Benchmark Dose Computation
Specified effect =	0.01

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	7.63793

BMDL =	4.29872

BMDU =	8.4 964

Taken together, (4.29872, 8.4964 ) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00232627

This document is a draft for review purposes only and does not constitute Agency policy.

1-8 DRAFT—DO NOT CITE OR QUOTE


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Multistage Cancer Model with 0.95 Confidence Level

dose

15:50 04/16 2010

Figure 1-3. NTP, 2006 (cholangiocarcinomas): Background dose = measured
TEQ concentration (TCDD, PeCDF, and PCB-126).

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

1-9 DRAFT—DO NOT CITE OR QUOTE


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1.4. NTP, 2006 (CHOLANGIOCARCINOMAS): BACKGROUND DOSE = 2x
MEASURED TEQ CONCENTRATION (TCDD, PECDF, AND PCB-126)

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\Usepa\BMDS21\Data\msc_NTP_2006_carcin_Setting.(d)

Gnuplot Plotting File: C:\Usepa\BMDS21\Data\msc_NTP_2 00 6_carcin_Setting.plt

Fri Apr 16 15:51:30 2010

BMDS Model Run

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(

-betal*dose/sl-beta2*dose/s2-beta3* doseA3)]

The parameter betas are restricted to be positive

Dependent variable = cholang
Independent variable = bl_TEQ2x

Total number of observations = 6

Total number of records with missing values = 0

Total number of parameters in model = 4

Total number of specified parameters = 0

Degree of polynomial = 3

Maximum number of iterations = 25 0

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
Background =	0

Beta (1) =	0

Beta (2) =	0

Beta(3) = 2.3568e-005

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -Background -Beta(l) -Beta(2)

have been estimated at a boundary point, or have been specified by

the user,

and do not appear in the correlation matrix )

Beta (3)

Beta(3)	1

Parameter Estimates

This document is a draft for review purposes only and does not constitute Agency policy.

I-10 DRAFT—DO NOT CITE OR QUOTE


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95.0% Wald Confidence

Interval

Variable Estimate Std. Err.	Lower Conf. Limit Upper Conf.

Limit

Background 0 *	* *

Beta (1) 0 *	* *

Beta (2) 0 *	* *

Beta (3) 2.20268e-005 *	* *

* - Indicates that this value is not calculated.

Model
Full model
Fitted model
Reduced model

Analysis of Deviance Table
#

Log(likelihood)
-55.408
-55.8382
-96.9934

Param's
6
1
1

Deviance Test d.f.

0.860456
83.1708

P-value

0.973
<.0001

AIC:

113.676

Goodness of Fit

Scaled

Dose	Est._Prob. Expected Observed	Size	Residual

0.3800

0.0000

0. 000

0. 000

49

-0.008

2.9400

0.0006

0. 027

0. 000

48

-0.164

6.0700

0.0049

0.226

0. 000

46

-0.477

10.1700

0.0229

1.145

1. 000

50

-0.137

16.9800

0.1022

5.009

4.000

49

-0.476

30.0800

0.4509

23.898

25.000

53

0.304

Chi^2 = 0.59	d.f. = 5	P-value = 0.9884

Benchmark Dose Computation
Specified effect =	0.01

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	7.6985 6

BMDL =	4.45212

BMDU =	8.5 637 6

Taken together, (4.45212, 8.56376) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor = 0.00224612

This document is a draft for review purposes only and does not constitute Agency policy.

I-11 DRAFT—DO NOT CITE OR QUOTE


-------
Multistage Cancer Model with 0.95 Confidence Level

dose

15:51 04/16 2010

Figure 1-4. NTP, 2006 (cholangiocarcinomas): Background dose = 2x
measured TEQ concentration (TCDD, PeCDF, and PCB-126).

This document is a draft for re\'iew purposes only and does not constitute Agency policy.

1-12 DRAFT—DO NOT CITE OR QUOTE


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1.5. NTP, 2006 (CHOLANGIOCARCINOMAS): BACKGROUND DOSE = 10x
MEASURED TCDD CONCENTRATION

Multistage Cancer Model. (Version: 1.7; Date: 05/16/2008)

Input Data File: C:\Usepa\BMDS21\Data\msc_NTP_2006_carcin_Setting.(d)

Gnuplot Plotting File: C:\Usepa\BMDS21\Data\msc_NTP_2 00 6_carcin_Setting.plt

Fri Apr 16 15:55:37 2010

BMDS Model Run

The form of the probability function is:

P[response] = background + (1-background)*[1-EXP(

-betal*dose/sl-beta2*dose/s2-beta3* doseA3)]

The parameter betas are restricted to be positive

Dependent variable = cholang
Independent variable = bl_TEQmax

Total number of observations = 6

Total number of records with missing values = 0

Total number of parameters in model = 4

Total number of specified parameters = 0

Degree of polynomial = 3

Maximum number of iterations = 25 0

Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008

Default Initial Parameter Values
Background =	0

Beta (1) =	0

Beta (2) =	0

Beta(3) = 2.29823e-005

Asymptotic Correlation Matrix of Parameter Estimates

( *** The model parameter(s) -Background -Beta(l) -Beta(2)

have been estimated at a boundary point, or have been specified by

the user,

and do not appear in the correlation matrix )

Beta (3)

Beta(3)	1

Parameter Estimates

This document is a draft for review purposes only and does not constitute Agency policy.

I-13 DRAFT—DO NOT CITE OR QUOTE


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95.0% Wald Confidence

Interval

Variable Estimate Std. Err.	Lower Conf. Limit Upper Conf.

Limit

Background 0 *	* *

Beta (1) 0 *	* *

Beta (2) 0 *	* *

Beta (3) 2.13264e-005 *	* *

* - Indicates that this value is not calculated.

Model
Full model
Fitted model
Reduced model

Analysis of Deviance Table
#

Log(likelihood)
-55.408
-55.8994
-96.9934

Param's
6
1
1

Deviance Test d.f.

0.982747
83.1708

P-value

0.9639
<.0001

AIC:

113.799

Goodness of Fit

Scaled

Dose	Est._Prob. Expected Observed	Size	Residual

0.6400

0.0000

0. 000

0. 000

49

-0.017

3.2000

0.0007

0. 034

0. 000

48

-0.183

6.3300

0.0054

0.248

0. 000

46

-0.499

10.4300

0.0239

1.195

1. 000

50

-0.181

17.2400

0.1035

5.072

4.000

49

-0.503

30.3400

0.4488

23.785

25.000

53

0.336

Chi^2 = 0.68	d.f. = 5	P-value = 0.9840

Benchmark Dose Computation
Specified effect =	0.01

Risk Type	=	Extra risk

Confidence level =	0.95

BMD =	7.78193

BMDL =	4.65224

BMDU =	8.65 638

Taken together, (4.65224, 8.65638) is a 90	% two-sided confidence

interval for the BMD

Multistage Cancer Slope Factor =	0.0021495

This document is a draft for review purposes only and does not constitute Agency policy.

1-14 DRAFT—DO NOT CITE OR QUOTE


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Multistage Cancer Model with 0.95 Confidence Level

dose

1	15:55 04/16 2010

2

3	Figure 1-5. NTP, 2006 (cholangiocarcinomas): Background dose = 10*

4	measured TCDD concentration.

5	1.6. REFERENCE

6	NTP (National Toxicology Program). (2006a) NTP technical report on the toxicology and carcinogenesis studies of

7	2,3,7,8-tetrachlorodibenzo-/?-dioxin (TCDD) (CAS No. 1746-01-6) in female Harlan Sprague-Dawley rats (Gavage

8	Studies). Natl Toxicol ProgramTech Rep 521. Public Health Service, National Institute of Health, U.S. Department

9	of Health and Human Services, Research Triangle Park, NC.

This document is a draft for review purposes only and does not constitute Agency policy.

1-15 DRAFT—DO NOT CITE OR QUOTE


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