United States
Environmental Protection
Agency
EPA/690/R-17/012
FINAL
09-28-2017
Provisional Peer-Reviewed Toxicity Values for
Superfund Health Risk Technical Support Center
National Center for Environmental Assessment
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, OH 45268
/>-Toluic Acid
(CASRN 99-94-5)
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AUTHORS, CONTRIBUTORS, AND REVIEWERS
CHEMICAL MANAGER
Jon Reid, PhD, DABT
National Center for Environmental Assessment, Cincinnati, OH
DRAFT DOCUMENT PREPARED BY
SRC, Inc.
7502 Round Pond Road
North Syracuse, NY 13212
PRIMARY INTERNAL REVIEWERS
Dan Petersen, PhD, DABT
National Center for Environmental Assessment, Cincinnati, OH
Suryanarayana V. Vulimiri, PhD
National Center for Environmental Assessment, Research Triangle Park, NC
This document was externally peer reviewed under contract to:
Eastern Research Group, Inc.
110 Hartwell Avenue
Lexington, MA 02421-3136
Questions regarding the content of this PPRTV assessment should be directed to the EPA Office
of Research and Development's National Center for Environmental Assessment, Superfund
Health Risk Technical Support Center (513-569-7300).
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TABLE OF CONTENTS
COMMONLY USED ABBREVIATIONS AND ACRONYMS iv
BACKGROUND 1
DISCLAIMERS 1
QUESTIONS REGARDING PPRTVs 1
INTRODUCTION 2
REVIEW OF POTENTIALLY RELEVANT DATA (NONCANCER AND CANCER) 5
HUMAN STUDIES 9
Oral Exposures 9
Inhalation Exposures 9
ANIMAL STUDIES 9
Oral Exposures 9
Inhalation Exposures 12
OTHER DATA (SHORT-TERM TESTS, OTHER EXAMINATIONS) 12
Acute and Short-Term Tests (Oral and Dermal) 12
Genotoxicity 13
Metabolism/Toxicokinetic Studies 13
DERIVATION 01 PROVISIONAL VALUES 15
DERIVATION OF ORAL REFERENCE DOSES 15
Derivation of a Subchronic Provisional Reference Dose 15
Derivation of a Chronic Provisional Reference Dose 23
DERIVATION OF INHALATION REFERENCE CONCENTRATIONS 25
CANCER WEIGHT-OF-EVIDENCE DESCRIPTOR 25
DERIVATION OF PROVISIONAL CANCER POTENCY VALUES 26
APPENDIX A. SCREENING PROVISIONAL VALUES 27
APPENDIX B. DATA TABLES 28
APPENDIX C. BENCHMARK DOSE MODELING RESULTS 34
APPENDIX D. REFERENCES 70
in
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COMMONLY USED ABBREVIATIONS AND ACRONYMS1
a2u-g
alpha 2u-globulin
MN
micronuclei
ACGIH
American Conference of Governmental
MNPCE
micronucleated polychromatic
Industrial Hygienists
erythrocyte
AIC
Akaike's information criterion
MOA
mode of action
ALD
approximate lethal dosage
MTD
maximum tolerated dose
ALT
alanine aminotransferase
NAG
7V-acetyl-P-D-glucosaminidase
AR
androgen receptor
NCEA
National Center for Environmental
AST
aspartate aminotransferase
Assessment
atm
atmosphere
NCI
National Cancer Institute
ATSDR
Agency for Toxic Substances and
NOAEL
no-observed-adverse-effect level
Disease Registry
NTP
National Toxicology Program
BMD
benchmark dose
NZW
New Zealand White (rabbit breed)
BMDL
benchmark dose lower confidence limit
OCT
ornithine carbamoyl transferase
BMDS
Benchmark Dose Software
ORD
Office of Research and Development
BMR
benchmark response
PBPK
physiologically based pharmacokinetic
BUN
blood urea nitrogen
PCNA
proliferating cell nuclear antigen
BW
body weight
PND
postnatal day
CA
chromosomal aberration
POD
point of departure
CAS
Chemical Abstracts Service
PODadj
duration-adjusted POD
CASRN
Chemical Abstracts Service registry
QSAR
quantitative structure-activity
number
relationship
CBI
covalent binding index
RBC
red blood cell
CHO
Chinese hamster ovary (cell line cells)
RDS
replicative DNA synthesis
CL
confidence limit
RfC
inhalation reference concentration
CNS
central nervous system
RfD
oral reference dose
CPN
chronic progressive nephropathy
RGDR
regional gas dose ratio
CYP450
cytochrome P450
RNA
ribonucleic acid
DAF
dosimetric adjustment factor
SAR
structure activity relationship
DEN
diethylnitrosamine
SCE
sister chromatid exchange
DMSO
dimethylsulfoxide
SD
standard deviation
DNA
deoxyribonucleic acid
SDH
sorbitol dehydrogenase
EPA
Environmental Protection Agency
SE
standard error
ER
estrogen receptor
SGOT
serum glutamic oxaloacetic
FDA
Food and Drug Administration
transaminase, also known as AST
FEVi
forced expiratory volume of 1 second
SGPT
serum glutamic pyruvic transaminase,
GD
gestation day
also known as ALT
GDH
glutamate dehydrogenase
SSD
systemic scleroderma
GGT
y-glutamyl transferase
TCA
trichloroacetic acid
GSH
glutathione
TCE
trichloroethylene
GST
glutathione-S-transferase
TWA
time-weighted average
Hb/g-A
animal blood-gas partition coefficient
UF
uncertainty factor
Hb/g-H
human blood-gas partition coefficient
UFa
interspecies uncertainty factor
HEC
human equivalent concentration
UFc
composite uncertainty factor
HED
human equivalent dose
UFd
database uncertainty factor
i.p.
intraperitoneal
UFh
intraspecies uncertainty factor
IRIS
Integrated Risk Information System
UFl
LOAEL-to-NOAEL uncertainty factor
IVF
in vitro fertilization
UFS
subchronic-to-chronic uncertainty factor
LC50
median lethal concentration
U.S.
United States of America
LD50
median lethal dose
WBC
white blood cell
LOAEL
lowest-observed-adverse-effect level
Abbreviations and acronyms not listed on this page are defined upon first use in the PPRTV document.
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PROVISIONAL PEER-REVIEWED TOXICITY VALUES FOR
/7-TOLUIC ACID (CASRN 99-94-5)
BACKGROUND
A Provisional Peer-Reviewed Toxicity Value (PPRTV) is defined as a toxicity value
derived for use in the Superfund Program. PPRTVs are derived after a review of the relevant
scientific literature using established Agency guidance on human health toxicity value
derivations. All PPRTV assessments receive internal review by at least two National Center for
Environment Assessment (NCEA) scientists and an independent external peer review by at least
three scientific experts.
The purpose of this document is to provide support for the hazard and dose-response
assessment pertaining to chronic and subchronic exposures to substances of concern, to present
the major conclusions reached in the hazard identification and derivation of the PPRTVs, and to
characterize the overall confidence in these conclusions and toxicity values. It is not intended to
be a comprehensive treatise on the chemical or toxicological nature of this substance.
PPRTV assessments are eligible to be updated on a 5-year cycle to incorporate new data
or methodologies that might impact the toxicity values or characterization of potential for
adverse human-health effects and are revised as appropriate. Questions regarding nomination of
chemicals for update can be sent to the appropriate U.S. Environmental Protection Agency
(EPA) Superfund and Technology Liaison (https://www.epa.gov/research/fact-sheets-regional-
science).
DISCLAIMERS
The PPRTV document provides toxicity values and information about the adverse effects
of the chemical and the evidence on which the value is based, including the strengths and
limitations of the data. All users are advised to review the information provided in this
document to ensure that the PPRTV used is appropriate for the types of exposures and
circumstances at the site in question and the risk management decision that would be supported
by the risk assessment.
Other U.S. EPA programs or external parties who may choose to use PPRTVs are
advised that Superfund resources will not generally be used to respond to challenges, if any, of
PPRTVs used in a context outside of the Superfund program.
This document has been reviewed in accordance with U.S. EPA policy and approved for
publication. Mention of trade names or commercial products does not constitute endorsement or
recommendation for use.
QUESTIONS REGARDING PPRTVs
Questions regarding the content of this PPRTV assessment should be directed to the EPA
Office of Research and Development's (ORD's) NCEA, Superfund Health Risk Technical
Support Center (513-569-7300).
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INTRODUCTION
/>-Toluic acid, CASRN 99-94-5, is also known as crithminic acid, 4-methylbenzoic acid,
/>carboxytoluene, /;-methylbenzoic acid, /Moluylic acid, /Molylcarboxylic acid, and 4-toluic
acid. This compound belongs to the class of compounds known as carboxylic acids. It is used as
an intermediate for antibiotic pharmaceuticals, photosensitive pigments, fluorescent dyes, and
colorants (Maki and Takeda. 2012; 01X I). 2008a). />-Toluic acid is listed on the U.S. EPA's
Toxic Substances Control Act's public inventory (U.S. EPA. 2015). and was assessed under the
joint U.S. EPA high production volume (HPV) chemical and Organisation for Economic
Co-operation and Development Screening Information Data Set (OECD SIDS) programme
(01 XT). 2008a). It is not registered with Europe's Registration, Evaluation, Authorisation and
Restriction of Chemicals (REACH) programme (I X'H A. 2017).
Commercial production of /Moluic acid occurs primarily by the vapor-phase or nitric acid
oxidation of /^-xylene in the presence of a catalyst, such as cobalt naphthenate. It may also be
isolated as a byproduct during the manufacture of terephthalic acid from /^-xylene (Maki and
Takeda. 2012; OI XT). 2008a).
The empirical formula for/Moluic acid is C8H8O2 (see Figure 1). Table 1 summarizes
the physicochemical properties of /Moluic acid. />Toluic acid is a white to yellow-brown
crystalline solid at room temperature (OECD. 2008a). The acid dissociation constant (pKa) of
/Moluic acid is 4.22, indicating that it will exist predominantly as an anion in the environment.
/>Toluic acid's low vapor pressure indicates that it will exist in both the vapor and particulate
phases in the atmosphere. The estimated half-life of vapor-phase /Moluic acid in air by reaction
with photochemically produced hydroxyl radicals is 4.2 days. p-Toluic acid's low vapor
pressure indicates that it is not likely to volatilize from dry soil surfaces. Volatilization is not
expected from moist soil or water because this compound exists as an anion. The moderate
water solubility and low soil adsorption coefficient for /Moluic acid indicate that it may leach to
groundwater or undergo runoff after a rain event. />Toluic acid may also undergo ready
biodegradation in the environment, based on screening tests (OECD. 2008a).
o
H ,C
O H
Figure l./>-Toluic Acid Structure
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Table 1. Physicochemical Properties of/>-Toluic Acid (CASRN 99-94-5)
Property (unit)
Value
Physical state
Solid
Boiling point (°C)
273.9a
Melting point (°C)
179.6b
Density (g/cm3 at 20°C)
1.23°
Vapor pressure (mm Hg at 25 °C)
5.08 x 10 5 (extrapolated)13
pH (unitless)
3.6a
pKa (unitless)
4.22a
Solubility in water (mg/L at 25 °C)
340b
Octanol-water partition coefficient (log Kow)
2.27b
Henry's law constant (atm-m3/mol at 25°C)
1.2 x 10 (estimated)13
Soil adsorption coefficient Koc (L/kg)
27 (estimated)13
Atmospheric OH rate constant (cm3/molecule-sec at 25°C)
2.5 x 10 12 (estimated)13
Atmospheric half-life (d)
4.2 (estimated)13
Relative vapor density (air = 1)
NA
Molecular weight (g/mol)
136b
Flash point (°C)
181°
"OECD (2008a).
bU.S. EPA (2012c).
°Maki and Takeda (2012).
NA = not applicable.
No toxicity values for /?-toluic acid from EPA or other agencies/organizations were
located (see Table 2).
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Table 2. Summary of Available Toxicity Values for />-Toluic Acid (CASRN 99-94-5)
Source3
Value
Notes
Reference
Noncancer
IRIS
NV
NA
U.S. EPA (2017)
HEAST
NV
NA
U.S. EPA (201 la)
DWSHA
NV
NA
U.S. EPA (2012a)
ATSDR
NV
NA
ATSDR (2017)
IPCS
NV
NA
IPCS (2017); WHO (2017)
Cal/EPA
NV
NA
Cal/EPA (2014): Cal/EPA (2017a): Cal/EPA (2017b)
OSHA
NV
NA
OSHA (2006): OSHA (2011)
NIOSH
NV
NA
NIOSH (2016)
ACGIH
NV
NA
ACGIH (2016)
Cancer
IRIS
NV
NA
U.S. EPA (2017)
HEAST
NV
NA
U.S. EPA (2011a)
DWSHA
NV
NA
U.S. EPA (2012a)
NTP
NV
NA
NTP (2014)
IARC
NV
NA
IARC (2017)
Cal/EPA
NV
NA
Cal/EPA (2011): Cal/EPA (2017a): Cal/EPA (2017b)
ACGIH
NV
NA
ACGIH (2016)
aSources: ACGIH = American Conference of Governmental Industrial Hygienists; ATSDR = Agency for Toxic
Substances and Disease Registry; Cal/EPA = California Environmental Protection Agency; DWSHA = Drinking
Water Standards and Health Advisories; HEAST = Health Effects Assessment Summary Tables;
IARC = International Agency for Research on Cancer; IPCS = International Programme on Chemical Safety;
IRIS = Integrated Risk Information System; NIOSH = National Institute for Occupational Safety and Health;
NTP = National Toxicology Program; OSHA = Occupational Safety and Health Administration.
NA = not applicable; NV = not available.
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Non-date-limited literature searches were conducted in December 2015 and updated in
August 2017 for studies relevant to the derivation of provisional toxicity values for /Moluic acid
(CASRN 99-94-5). Searches were conducted using U.S. EPA's Health and Environmental
Research Online (HERO) database of scientific literature. HERO searches the following
databases: PubMed, ToxLine (including TSCATS1), and Web of Science. The following
databases were searched outside of HERO for health-related data: American Conference of
Governmental Industrial Hygienists (ACGIH), Agency for Toxic Substances and Disease
Registry (ATSDR), California Environmental Protection Agency (Cal/EPA), European Centre
for Ecotoxicology and Toxicology of Chemicals (ECETOC), European Chemicals Agency
(ECHA), U.S. EPA Health Effects Assessment Summary Tables (HEAST), U.S. EPA HPV,
U.S. EPA Integrated Risk Information System (IRIS), U.S. EPA Office of Water (OW),
U.S. EPA TSCATS2, U.S. EPA TSCATS4/8d/8e/FYI, International Agency for Research on
Cancer (IARC), Japan Existing Chemical Data Base (JECDB), National Institute for
Occupational Safety and Health (NIOSH), National Toxicology Program (NTP), OECD HPV,
OECD International Uniform Chemical Information Database (IUCLID), OECD SIDS,
Occupational Safety and Health Administration (OSHA), and World Health Organization
(WHO).
REVIEW OF POTENTIALLY RELEVANT DATA
(NONCANCER AND CANCER)
Tables 3 A and 3B provide overviews of the relevant noncancer and cancer databases,
respectively, for /Moluic acid and include all potentially relevant repeated short-term-,
subchronic-, and chronic-duration studies, as well as reproductive and developmental toxicity
studies. Principal studies are identified in bold. The phrase "statistical significance," used
throughout the document, indicates ap-walue of < 0.05, unless otherwise specified.
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Table 3A. Summary of Potentially Relevant Noncancer Data for />-Toluic Acid (CASRN 99-94-5)
Number of Male/Female, Strain,
Species, Study Type, Study Duration,
Reference
Category"
Reported Doses
Dosimetryb
Critical Effects
NOAELb
LOAELb
(comments)
Notes0
Human
1. Oral (mg/kg-d)
ND
2. Inhalation (mg/m3)
ND
Animal
1. Oral (mg/kg-d)
Short term
5 M/5 F, S-D Cij:CD(SD) rat, gavage in
0, 100, 300, 1,000
Increased AST; decreased RBC counts, Hb,
300
1,000
Shirota et al.
PR
sodium carboxymethyl-cellulose, 7 d/wk,
and Hct (end of recovery period)
(2008)
28 d; 0, 100, 300, 1,000 mg/kg-d
R/I)
13 M/13 F, S-D Crj:CD(SD) rat,
ADD: 0,100,300,
Parental males: Decreased absolute and
300
1,000
Shirota et al.
PR, PS
gavage in sodium
1,000
relative epididymis weights; increased
(2008)
carboxymethyl-cellulose, ~6 wk (2 wk
incidence of animals with fewer numbers
premating and during mating in both
of spermatozoa
sexes, and continuing thereafter for a
total of 42 d in males and throughout
Parental females: Decreased gestational
100
300
gestation and until LD 4 in females); 0,
body-weight gain
100,300,1,000 mg/kg-d
R/D: Decreased implantation index;
100
300
decreased number of pups born; decreased
number of live pups on LD 0 and 4
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Table 3A. Summary of Potentially Relevant Noncancer Data for />-Toluic Acid (CASRN 99-94-5)
Category"
Number of Male/Female, Strain,
Species, Study Type, Study Duration,
Reported Doses
Dosimetryb
Critical Effects
NOAELb
LOAELb
Reference
(comments)
Notes0
2. Inhalation (mg/m3)
ND
'Duration categories are defined as follows: Acute = exposure for <24 hours; short term = repeated exposure for 24 hours to <30 days; long term (subchronic) = repeated
exposure for >30 days <10% lifespan for humans (>30 days up to approximately 90 days in typically used laboratory animals); and chronic = repeated exposure for
>10% lifespan for humans (more than approximately 90 days to 2 years in typically used laboratory animal species) (U.S. EPA. 20021.
bDosimetry: Doses are presented as an ADD (mg/kg-day) for oral noncancer effects.
°Notes: PR = peer reviewed; PS = principal study.
ADD = adjusted daily dose; AST = aspartate aminotransferase; F = female(s); Hb = hemoglobin; Hct = hematocrit; LD = lactation day;
LOAEL = lowest-observed-adverse-effect level; M = male(s); ND = no data; NDr = not determined; NOAEL = no-observed-adverse-effect level; RBC = red blood cell;
R/D = reproductive/developmental; S-D = Sprague-Dawley.
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Table 3B. Summary of Potentially Relevant Cancer Data for />-Toluic Acid (CASRN 99-94-5)
Category
Number of Male/Female, Strain, Species,
Study Type, Study Duration, Reported Doses
Dosimetry
Critical Effects
NOAEL
LOAEL
Reference
(comments)
Notes
Human
1. Oral (mg/kg-d)
ND
2. Inhalation (mg/m3)
ND
Animal
1. Oral (mg/kg-d)
ND
2. Inhalation (mg/m3)
ND
LOAEL = lowest-observed-adverse-effect level; ND = no data; NOAEL = no-observed-adverse-effect level.
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HUMAN STUDIES
Oral Exposures
No studies have been identified.
Inhalation Exposures
No studies have been identified.
ANIMAL STUDIES
Oral Exposures
Short-Term-Duration Studies
Shirota et al. (2008)
In a 28-day study, />-toluic acid (purity 98.95%) was administered to Sprague-Dawley
(S-D) Cij:CD(SD) rats (five/sex/group), daily by gavage (sodium carboxymethyl-cellulose was
used as a vehicle) at doses of 0, 100, 300, or 1,000 mg/kg-day. Rats were 5 weeks old at the start
of dosing. The control group received the vehicle only. Additional animals (five/sex/group)
were included in the control and high-dose groups for assessment of recovery during a 14-day
post-treatment observation period. Animals were observed for mortality and clinical signs daily,
and detailed clinical observations were recorded weekly. Body weights were measured
three times during Week 1 and twice weekly thereafter. Food consumption was determined
weekly. A four-item neurobehavioral auditory and visual function assessment (parameters not
reported) was performed during Week 4. Urine was collected in a metabolic cage during the
final week of the treatment and recovery periods, and evaluated for color, turbidity, sediments,
pH, occult blood, protein ketone bodies, urobilinogen, bilirubin, volume, weight, and specific
gravity. On the last day of treatment, the animals were fasted for 18-24 hours. Blood was
collected for hematological and clinical chemistry measurements on the day following the last
day of treatment or recovery. All surviving animals were sacrificed and subjected to a complete
gross necropsy. Hematological parameters included red blood cell (RBC) count, hemoglobin
(Hb) concentration, hematocrit (Hct), mean corpuscular volume (MCV), mean corpuscular
hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), platelet count,
prothrombin time (PT), activated partial thromboplastin time (APTT), leukocyte count, and
differential leukocyte (neutrophils, eosinophils, basophils, monocytes, and lymphocytes) counts.
Clinical chemistry parameters included total protein (TP), albumin, albumin:globulin (A:G)
ratio, blood urea nitrogen (BUN), creatinine, glucose, total cholesterol, triglycerides, total
bilirubin, inorganic phosphorus, calcium, sodium, potassium, chloride, alkaline phosphatase
(ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and gtmma-glutamyl
transpeptidase (y-GTP). Organ weights were determined for the brain, thymus, heart, liver,
kidneys, spleen, adrenals, testes, and epididymides of all animals, and relative organ weights
were calculated. All weighed organs, as well as the following organs and tissues, were examined
microscopically for histopathological abnormalities: spinal cord, lungs, bronchi, stomach, ileum,
colon, seminal vesicles, ovaries, uterus, vagina, urinary bladder, thyroid gland, femoral marrow,
mesenteric lymph nodes, mandibular lymph nodes, and ischiadic nerves. Statistical analyses
included the Fisher's direct probability test, Mann-Whitney U test, x2-square test, Student's
Mest, Aspin-Welch's /-test, analysis of variance (ANOVA), Kruskal-Wallis rank test, Bartlett's
test, and Dunnett's test.
No deaths were reported. Slight, statistically significant increases in mean food
consumption were observed in high-dose females on Days 7-8. Clinical signs during exposure
were confined to temporary, postdosing salivation, a common finding in gavage studies, in a few
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high-dose animals (incidence was not reported). No treatment-related effects on body-weight
gain, absolute and relative organ weights, gross necropsy, or histopathology were observed (data
not shown). Hematological changes were restricted to high-dose males and included a
statistically significant decrease in the differential eosinophil count at the end of treatment on
Day 42 (1% at 0 mg/kg-day and 0% at 1,000 mg/kg-day as percent of leukocytes), and slight, yet
statistically significant, decreases relative to controls (-4%) in RBC count, Hb, and Hct at the
end of the recovery period (see Table B-l). Changes in blood chemistry parameters included a
statistically significant decrease (-11%) in TP concentration and an increase (36%) in AST
concentration in high-dose females at the end of treatment (see Table B-l). Changes in
urinalysis parameters were observed in mid- and high-dose males and females and included
statistically significant decreases in specific gravity (-1% at 300 and 1,000 mg/kg-day) and
increases in urinary volume (34% and 53% for males and 11% and 89% for females) at the end
of treatment (see Table B-l). At Day 9 of the recovery period, urine volumes were not
statistically significant but were increased (33% for males and 38% for females) (see Table B-l).
The increase in urine volume was preceded by an increase in water consumption.
A lowest-observed-adverse-effect level (LOAEL) of 1,000 mg/kg-day and a
no-observed-adverse-effect level (NOAEL) of 300 mg/kg-day are identified for increased AST
levels in female rats.
Reproductive/Developmental Studies
Shiroto et al. (2008)
In a reproductive/developmental (R/D) toxicity screening study, groups of 26 S-D
Cij:CD(SD) rats (13/sex/group) at 10 weeks of age received daily doses of />-toluic acid
(purity 98.95%)) at 0, 100, 300, or 1,000 mg/kg-day via gavage in sodium
carboxymethyl-cellulose for 2 weeks prior to mating. Females continued exposure throughout
mating, gestation, and lactation, until Lactation Day (LD) 4; males continued to receive daily
gavage exposures throughout mating and postmating, for a total of 42 consecutive days of
exposure. Rats were observed daily for survival and clinical signs. Male body weights and food
consumption were recorded weekly. Female body weights were recorded weekly until mating
and then on Gestation Days (GDs) 0, 7, 14, and 20 and LDs 0 and 4. Food consumption was
measured weekly in females until mating and then on GDs 0-1, 7-8, 14-15, and 20-21 and
LDs 3-4. The estrous cycle was monitored daily until copulation. Reproductive endpoints
evaluated included pairing days until copulation (precoital interval), estrus cycles until
copulation; birth, and F1 viability indices; number of corpora lutea, implantation sites, pups
born, and live and dead pups; gestation length; sex ratio; and F1 body weight. Live F1 animals
were examined daily during the postnatal period for external morphology and general condition.
On LD 4, all surviving dams and offspring were weighed and sacrificed. F0 animals were
subjected to a complete gross necropsy, and organ weights including testes and epididymides for
males were recorded at terminal sacrifice. Histopathology of the reproductive organs was
performed at terminal sacrifice of F0 animals and included the testes, epididymides, prostate,
seminal vesicles, coagulating glands, ovaries, uterus, and vagina. Pups were examined for
external and visceral abnormalities at terminal sacrifice on LD 4. Statistical analyses included
the Fisher's direct probability test, Mann-Whitney U test, Student's f-test, Aspin-Welch's /-test,
F-test, ANOVA, Kruskal-Wallis rank test, Bartlett's test, and Dunnett's test. It is not evident
whether the data were analyzed on a litter/dam basis. While the study was conducted according
to a standard guideline (OECD Test Guideline 421) (PLC IX 1995). the version of the test
guideline followed in this study did not require that analyses be performed using litter/dam as the
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experimental unit of analysis, which is a requirement of the revised version (01XI). 2016) of the
test guideline.
No deaths were reported. Food consumption in the females was statistically significantly
increased in the 1,000 mg/kg-day group during GDs 14-15, but was significantly decreased
during Days 3-4 of lactation (data not shown). In male rats, however, there were no measurable
effects on feed intake or body-weight changes. Postdosing salivation was temporarily observed
in high-dose animals (incidence not reported), but this is a common finding in gavage studies. It
is noted that data from this study used body weights which were split into weekly changes. No
effects on body weight or body-weight gain were observed in males. In females, no effects on
body weight were observed during the premating or gestation periods (see Table B-2). However,
female mean body weights were statistically significantly increased on LD 0 at the mid- and
high-dose levels relative to controls (13% for both groups, estimated from Figure 5 A of the study
report; see Table B-2). On LD 4, no significant treatment-related effects on female mean body
weights were observed. Female mean body-weight gains were not significantly different
compared to controls during the premating period, but were statistically significantly decreased
during GDs 14-20 at the mid- and high doses (-17 and -25%, respectively; estimated from
Figure 5B of the study report; see Table B-2) and during LDs 0-4 at the high dose (—73%;
estimated from Figure 5B of the study report; see Table B-2). A decrease in female mean
body-weight gain relative to controls (—43%) was also observed in mid-dose females during
LDs 0-4, but the decrease was not statistically significant.
Reproductive parameters are shown in Table B-3. No treatment-related effects were
observed on estrous cyclicity, ovulation, mating, gestation length, or delivery index. Although
all females that had copulated in the control and low-dose groups became pregnant (i.e., 13/13
for both groups), one and four such females in the mid- and high-dose groups (i.e., 1/13 and
4/13, respectively) did not become pregnant. A statistically significant decrease in the fertility
index (pregnant females/copulated pairs) was observed at the high dose relative to controls
(-31%). There was no effect on the number of corpora lutea, but the number of implantation
sites was decreased insignificantly at the mid and high doses (-13 and -24%, respectively),
leading to statistically significant decreases in implantation index (number of implantation
sites/number of corpora lutea) at the mid and high doses relative to controls (-13 and -23%,
respectively). Related findings were statistically significant decreases in the number of pups
born in the mid- and high-dose groups relative to controls (-18 and -33%, respectively) and
decreases in the number of pups alive on LD 0 (-14 and —30%, respectively) and LD 4 (-14 and
-32%, respectively) (statistically significant only in the high-dose group). Examination of pup
morphology, behavior, and body weight during the postnatal period showed no treatment-related
effects. Temporary cyanosis at birth and dilatation of the renal pelvis at necropsy were observed
in one high-dose pup. No other effects on mating, fertility, pregnancy, or pup parameters were
observed.
Adult male reproductive organ weights and histopathology are shown in Tables B-4 and
B-5. Absolute and relative epididymis weights were statistically significantly decreased (-12
and -13%), respectively) in high-dose animals (see Table B-4). The decreases in absolute and
relative epididymis weights in high-dose males were accompanied by an increased incidence
(0/13 at 0, 100, and 300 mg/kg-day; 13/13 at 1,000 mg/kg-day) of animals with fewer numbers
of spermatozoa in the cauda epididymis (see Tables B-4 and B-5). This effect (graded as very
slight or slight; see Table B-5) was localized to the cauda epididymis and was not present in the
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caput epididymis of any animal. The incidence of animals with cell debris in the cauda
epididymal lumen was increased, but not significantly, at the highest dose relative to the control
group (graded as very slight; 5/13 vs. 1/13, respectively; see Tables B-4 and B-5). The uterus of
the mid-dose female that failed to become pregnant showed ballooning and accumulation of
cloudy fluid, and histopathology revealed lumen dilatation and cellular infiltration of neutrophils
in the epithelium and endometrial stroma, with edema present in the endometrial stroma. A
moderate increase in atretic follicles was observed in one high-dose female. No other
abnormalities in male or female reproductive organs were reported.
Parental male NOAEL and LOAEL values of 300 and 1,000 mg/kg-day, respectively, are
identified, based on statistically significant decreases in absolute and relative epididymis
weights, and a significant increase in the incidence of animals with reduced numbers of
spermatozoa. Parental female NOAEL and LOAEL values of 100 and 300 mg/kg-day,
respectively, were identified, based on a significant decrease in gestational body-weight gain.
R/D NOAEL and LOAEL values of 100 and 300 mg/kg-day, respectively, were identified based
on statistically significant decreases in implantation index and number of pups born. Reduced
fertility in females could be related to effects on the male reproductive system at this dose
(e.g., decreased epididymal weight and number of luminal sperm) and/or other treatment-related
reproductive effects in both sexes. Reduced fertility in females is also among the potential
causes for increased preimplantation loss (i.e., decreased implantation index) observed in this
study at the high and mid doses. The decreases in the number of pups born and the number of
pups alive on LDs 0 and 4 appear to be sequelae of preimplantation loss. The decrease in
maternal body-weight gain at the mid and high doses during the latter part of gestation
(i.e., GDs 14-20) is attributed to the small litter size, resulting from the reduced number of
implantations, rather than to a direct, test substance-related effect on maternal body weight. This
was also the conclusion of the study authors.
Inhalation Exposures
No studies examining the effects of /Moluic acid in animals exposed via inhalation have
been identified.
OTHER DATA (SHORT-TERM TESTS, OTHER EXAMINATIONS)
Acute and Short-Term Tests (Oral and Dermal)
Oral median lethal dose (LD50) values for /Moluic acid in rodents were
1,130-3,113 mg/kg (rats) and 2,340-2,484 mg/kg (mice) (01X I). 2008a; Ha/.elton Lab. 1986.
1984). Clinical signs observed following immediately or by Day 2 of oral exposure in the acute
toxicity studies in rats and mice included respiratory arrest, tremors, sedation, ataxia, decreased
locomotor activity, absent pain reflex, decreased grasping reflex, limb weakness, impaired use of
front limbs, loss of righting reflex, abasia, prostration, ptosis, bradypnea, loss of reflexes,
subnormal temperature, and temporary reductions in body-weight gain. Hemorrhages in the
stomach mucosa and small intestine and petechial hemorrhages in the thymus were observed in
animals that died during the study (OECD, 2008a). Reduced locomotor activity was observed at
two daily doses of 500 mg/kg-day and higher, while prone position was observed at two daily
doses of 2,000 mg/kg-day.
/>Toluic acid induced strong dermal reactions upon initial challenge in adult human
volunteers and was a potent dermal sensitizer (Emmett and Suskind. 1973). Simultaneous and
repeated application of /Moluic acid (50% in polystyrene) and o-toluic acid to different sites on
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the upper back produced severe dermal reactions in 4/10 subjects. Challenge application induced
sensitization reactions in 5/10 subjects. The five subjects that displayed sensitization reactions
also showed cross-sensitization to/>-, o-, and m-toluic acids (Kmmett and Suskind. 1973).
Genotoxicity
/>-Toluic acid has been tested in in vitro (positive and negative results) and in vivo
(negative results) studies (see Table 4). Although English-language peer-reviewed study reports
are not available, these studies were summarized in the OECD (2008a) dossier for /Moluic acid.
In a bacterial mutation test, /Moluic acid was negative (both with and without exogenous
metabolic activation) for reverse mutations in Salmonella typhimurium strains TA98, TA100,
TA1535, and TA 1537 and in Escherichia coli strain WP2 uvrA/pKM 101 (OECD, 2008a).
Doses were 313, 625, 1,250, 2,500, and 5,000 |ig/plate without activation and 156, 313, 625,
1,250, 2,500, and 5,000 |ig/plate with activation. In clastogenicity tests, /Moluic acid induced
chromosomal aberrations (CAs) in Chinese hamster lung (CHL) cells in the absence and
presence of S9 metabolic activation (OECD, 2008a), but was negative for induction of
micronuclei (MN) in vivo in male CD-1 mice following two daily gavage exposures (OECD,
2008a).
Metabolism/Toxicokinetic Studies
Evidence of toxic effects from animal studies indicates that /Moluic acid can be absorbed
through the gastrointestinal (GI) tract (Shirota et aL 2008), but no data are available regarding
the rate or extent of absorption. An in vitro dermal absorption study demonstrated that /Moluic
acid penetrated skin samples from pigs and rodents (Dver and Aziza. 1989). The study authors
reported a partition coefficient (Km) of 0.47-0.51 for penetration of /Moluic acid from aqueous
solution to pig or rodent skin, and a self-diffusion permeation rate coefficient (D) of
0.57-1.3 x 10~10 nr/sec for diffusion of /Moluic acid through pig or rodent skin (Dver and
Aziza. 1989).
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Table 4. Summary of />-Toluic Acid Genotoxicity
Endpoint
Test System
Dose/Concentration
Results without
Activation3
Results with
Activation3
Comments
References
Genotoxicity studies in prokaryotic organisms
Mutation
Salmonella
typhimurium strain
TA98, TA100,
TA1535, TA1537;
Escherichia coli strain
WP2 uvrA/pKM 101
0,313,625, 1,250, 2,500,
5,000 ng/plate in DMSO
(-S9);
0, 156,313,625, 1,250, 2,500,
5,000 |ig/platc in DMSO (+S9)
Toxicity was observed in all strains at
5,000 ng/plate with S9 mix.
OECD (2008a):
Mori etal. (1980)
Genotoxicity studies in mammalian cells—in vitro
CAs
CHL cells; DNA
damage assessed at 6
or 24 hr after
treatment
0, 500, 1,000, 1,250, 1,400,
1,500, 1,600, 1,800, 2,000,
2,500, 5,000 (6 hr, -S9);
0, 250, 500, 1,000, 1,250,
1,500, 2,000, 2,500, 3,000,
5,000 (24 hr, -S9);
0, 250, 500, 1,000, 1,200,
1,250, 1,400, 1,500, 2,500,
5,000 (6 hr, +S9)
+
+
In the presence of metabolic activation,
the number of cells with structural CAs
was increased at concentrations of
>1,000 iig/mL in the absence of metabolic
activation and at >1,200 |ig/mL in the
presence of metabolic activation. Toxicity
was observed at concentrations
>1,500 |ig/mL in the absence of metabolic
activation and at >3,000 |ig/mL in the
presence of metabolic activation.
OECD (2008a)
Genotoxicity studies—in vivo
Micronucleus test
Male CD-I mice
(five/group); gavage
in sodium
carboxymethyl-cellul
ose; twice with 24-hr
interval; DNA
damage assessed
24 hr after the second
dose
0, 500, 1,000, 2,000 mg/kg-d
(24 hr)
NA
No significant increase in the frequency of
micronucleated polychromatic
erythrocytes. There was no indication of
cytotoxicity, as evidenced by no increase
in the frequency of polychromatic
eiythrocytes in total eiythrocytes. No
deaths occurred. Clinical signs included
reduced locomotor activity at
500 mg/kg-d and prone position at
2,000 mg/kg-d.
Tanineher et al.
(1993)
a+ = positive; - = negative
CA = chromosomal aberration; CHL = Chinese hamster lung; DMSO = dimethyl sulfoxide; DNA = deoxyribonucleic acid; NA = not applicable.
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DERIVATION OF PROVISIONAL VALUES
Tables 5 and 6 present summaries of noncancer and cancer reference values, respectively.
Table 5. Summary of Noncancer Reference Values for />-Toluic Acid (CASRN 99-94-5)
Toxicity Type
(units)
Species/Sex
Critical Effect
p-Reference
Value
POD
Method
POD
(HED)
UFc
Principal
Study
Subchronic p-RfD
(mg/kg-d)
Rat/F
Decreased implantation
index
5 x 1(T2
BMDLi sd
13.5
300
Shirota et al.
(2008)
Chronic p-RfD
(mg/kg-d)
Rat/F
Decreased implantation
index
5 x 1CT3
BMDLi sd
13.5
3,000
Shirota et al.
(2008)
Subchronic p-RfC
(mg/m3)
NDr
Chronic p-RfC
(mg/m3)
NDr
BMDL = benchmark dose lower confidence limit; F = female(s); HED = human equivalent dose; M = male(s);
NDr = not determined; POD = point of departure; p-RfC = provisional reference concentration;
p-RfD = provisional reference dose; SD = standard deviation; UFC = composite uncertainty factor.
Table 6. Summary of Cancer Reference Values for /j-Toluic Acid (CASRN 99-94-5)
Toxicity Type (units)
Species/Sex
Tumor Type
Cancer Value
Principal Study
p-OSF (mg/kg-d) 1
NDr
p-IUR (mg/m3)-1
NDr
NDr = not determined; p-IUR = provisional inhalation unit risk; p-OSF = provisional oral slope factor.
DERIVATION OF ORAL REFERENCE DOSES
Derivation of a Subchronic Provisional Reference Dose
No data were located on the effects of oral exposure to /Moluic acid in humans. There is
only one 28-day study in rats (Shirota et aL 2008) and one reproductive developmental toxicity
screening test in rats [also reported in Shi rota et al. (2008)1 available for consideration for
derivation of a subchronic provisional reference dose. The R/D toxicity study (Shirota et al..
2008) is selected as the principal study and decreased implantation index is identified as the
critical effect; the rationale for selecting the principal study and critical effect are discussed
below.
Justification for the Principal Study
The 28-day study in rats exposed to /Moluic acid by gavage (Shirota et al.. 2008) is
considered to be of acceptable quality. Effects observed in this study include significantly
increased urine volume in males (>300 mg/kg-day) and females (1,000 mg/kg-day). Urine
specific gravity was statistically significantly reduced for males at >300 mg/kg-day. Total
protein was significantly decreased and the levels of AST were significantly increased in the
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blood of female rats, both at 1,000 mg/kg-day. Eosinophils were decreased in males at
1,000 mg/kg-day. Levels of RBCs, Hb, and Hct were all significantly decreased in males at
1,000 mg/kg-day at the end of the recovery period. The biological relevance of these effects is
questionable and therefore were not considered for subchronic p-RfD derivation. Furthermore,
except for decreased urine volume in males, these effects occurred at higher doses than the
reproductive effects observed in the R/D toxicity study conducted by Shirota et al. (2008).
Therefore, the 28-day study in rats was not selected as the principal study for the subchronic
p-RfD derivation.
The R/D toxicity study by Shirota et al. (2008) is also of acceptable quality and was
designed and performed according to standard protocols in rodents, included in OECD
Guidelines for the Testing of Chemicals, Section 4, "Test No. 421: Reproduction/Developmental
Toxicity Screening Test" adopted 29 July 2016, and "Test No. 407: Repeated Dose 28-day Oral
Toxicity Study in Rodents" adopted on 3 October 2008 (OECD, 2016. 2008b). All potential
/Moluic acid-induced effects observed in the R/D toxicity study conducted by Shirota et al.
(2008) were evaluated to determine the most sensitive response. The most sensitive endpoints
(i.e., those at the LOAEL of 300 mg/kg-day) included decreased maternal body-weight gain
(gestational), decreased implantation index, and decreased number of pups born. Data sets for
sensitive R/D endpoints in Shirota et al. (2008) were considered to derive potential points of
departure (PODs) via benchmark dose (BMD) modeling (see Table 7 and Appendix B). Other
reproductive endpoints (e.g., decreased number of live pups on LDs 0 and 4, decreased fertility
index [nonpregnant females/copulated pairs], and decreased absolute and relative epididymis
weights) observed at >300 mg/kg-day were significant at the high dose only. These effects were
suggestive of a dose response and were, therefore, also modeled.
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Table 7. R/D Endpoints in S-D Crj:CD(SD) Rats Exposed via Gavage to/>-Toluic Acid
during Premating, Mating, Gestation, and Lactation Considered for Benchmark Dose
Modeling3'b
Endpoint
Dose, mg/kg-d
0
100
300
1,000
Number of pregnant animals
13
13
11
9
Fertility index (number of nonpregnant
females/copulated pairs)
0
0
1
4*. t
Implantation index (%)
99.1 ±2.2
98.2 ±3.5
86.5 ± 12.6**
75.9 ±32.6*
Number of pups born
15.2 ± 1.4
14.1 ± 1.8
12.5 ±2.1**
10.2 ±5.1**
Number of live pups on LD 0
14.3 ± 1.7
14.1 ± 1.8
12.3 ±2.2
10.0 ±5.0*
Number of live pups on LD 4
14.3 ± 1.7
13.9 ± 1.8
12.3 ±2.2
9.7 ±5.3*
Absolute epididymis weight (g)b
1.28 ±0.08
1.27 ±0.08
(-0.8%)
1.24 ±0.07
(-3%)
1.13 ±0.09*
(-12%)
Relative epididymis weight
(g/ioo g)b
0.24 ±0.03
0.23 ± 0.02
(-4%)
0.23 ±0.01
(-4%)
0.21 ±0.02*
(-13%)
Few number of sperm, lumen,
bilateral
0/13 (0%)
0/13 (0%)
0/13 (0%)
13/13* (100%)
aSfairota et al. (2008).
bValues expressed as mean ± SD.
* Significantly different from controls (p < 0.05) as presented by study authors.
**Significantly different from controls (p < 0.01) as presented by study authors.
The data for the fertility index were presented by the study authors as number of pregnant females/copulated pairs
with a negative dose-response. Because BMDS cannot model negative quantal data, the data were converted to
number of nonpregnant females/copulated pairs with a positive dose-response.
BMDS = Benchmark Dose Software; LD = lactation day; R/D = reproductive/developmental;
S-D = Sprague-Dawley; SD = standard deviation.
Dosimetric Adjustments
No dosimetric adjustments for duration are made because continual dosing occurred
during the exposure portion of the R/D toxicity study. In Recommended Use of Body Weight4
as the Default Method in Derivation of the Oral Reference Dose (U.S. EPA, 201 lb), the Agency
endorses a hierarchy of approaches to derive human equivalent oral exposures from data on
laboratory animal species, with the preferred approach being physiologically based toxicokinetic
modeling. Other approaches may include using some chemical-specific information, without a
complete physiologically based toxicokinetic model. In the absence of chemical-specific models
or data to inform the derivation of human equivalent oral exposures, the EPA endorses
body-weight scaling to the 3/4 power (i.e., BW3/4) as a default to extrapolate toxicologically
equivalent doses of orally administered agents from all laboratory animals to humans for the
purpose of deriving an oral reference dose (RfD) under certain exposure conditions. More
specifically, the use of BW3 4 scaling for deriving an RfD is recommended when the observed
effects are associated with the parent compound or a stable metabolite but not for portal-of-entry
effects.
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A validated human physiologically based toxicokinetic model for />toluic acid is not
available for use in dose extrapolation from animals to humans. Furthermore, the R/D endpoints
are not portal-of-entry effects. Therefore, scaling by BW3/4 is relevant for deriving human
equivalent doses (HEDs) for this effect.
Doses provided in the study in mg/kg-day were converted to HEDs according to U.S.
EPA (2011b) guidance.
DAF = (BWa1/4 - BWh1/4)
where
DAF = dosimetric adjustment factor
BWa = animal body weight
BWh = human body weight; 70 kg
Table 8 shows animal doses converted to HEDs.
Table 8. Time-Adjusted Body Weights (DAF and HED)a
Dose Level from Principal Study
(mg/kg-d)
Time-Weighted Body Weight (F)
(kg)
DAF (F/M)b
HED (F/M)
(mg/kg-d)
0
0.2925
0.25/0.25
0/0
100
0.2950
0.25/0.25
25.0/25.0
300
0.2998
0.26/0.25
78.0/75.0
1,000
0.2986
0.26/0.25
260.0/250.0
aSfairota et al. (2008).
' Male default weight 0.267 kg for S-D male rats following subchronic-duration exposure (U.S. EPA. 19881. female
weight is time weighted.
DAF = dosimetric adjustment factor; F = female(s); HED = human equivalent dose; M = male(s);
S-D = Sprague-Dawley.
Approach for Deriving the Subchronic p-RfD
All available continuous-variable models in the Benchmark Dose Software (BMDS,
Version 2.5) were fit to the four R/D endpoints from Shirota et al. (2008) that were amenable to
BMD modeling. Dichotomous models were fit to the decreased fertility index data. Reduced
fertility in females could be related to effects on the male reproductive system (e.g., decreased
epididymal weight and number of luminal sperm) and/or other treatment-related reproductive
effects in both sexes, therefore, these data were modeled using dosimetry for both male and
female rats. Appendix C presents the modeling results, with benchmark dose lower confidence
limits (BMDLs), for the five BMD modeled data sets: (1) decreased implantation index
(see Table C-l), (2) decreased number of pups born (see Table C-2), (3) decreased number of
live pups on LDs 0 and 4 (see Tables C-3 and C-4, respectively), (4) reduced fertility index for
female and male rats (see Tables C-5 and C-6, respectively), and (5) decreased absolute and
relative epididymis weights in male rats (see Tables C-l and C-8, respectively). BMDs (HEDs)
and BMDLs (HEDs) from the best fitting models are presented in Table 9.
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Table 9. BMD and BMDL Values from Best Fitting Models for Selected R/D Endpoints in
Rats Exposed to />-Toluic Acid via Gavage during Premating, Mating, Gestation,
and Lactation3'b
Endpoint
Best Fitting Model
BMDisd (HED)
mg/kg-dc
BMDLisd (HED)
mg/kg-dc
Implantation index
Linear"1
BMDisd = 22.3
BMDLisd = 13.5
Number of pups born
Exponential (models 2 and 3)
BMDisd = 49.7
BMDLisd = 29.9
Number of live pups on LD 0
Exponential (model 2)
BMDisd = 73.6
BMDLisd = 42.7
Number of live pups on LD 4
Exponential (model 2)
BMDisd = 69.4
BMDLisd = 40.6
Fertility Index
Male and female: LogProbit
Male: BMDio = 105
Female: BMDio = 109
Male: BMDLio = 65.3
Female: BMDLio = 67.8
Decreased absolute epididymis
weight
Linear
BMDisd = 127
BMDLisd = 94.6
'Data sets from Shirota et al. (2008).
bModeling results are described in more detail in Appendix C.
°HEDs were calculated using the species-specific DAF based on the animal:human BW1/4 ratio recommended by
U.S. EPA (20lib).
dBest fitting model for this endpoint is for a reduced data set with the high-dose group dropped.
BMD = benchmark dose; BMDLio = 10% benchmark dose lower confidence limit; BMDLisd = benchmark dose
95th lower confidence limit based on 1 SD from the mean of the data; B W = body weight; DAF = dosimetric
adjustment factor; HED = human equivalent dose; LD = lactation day; R/D = reproductive/developmental;
SD = standard deviation.
Among the available candidate endpoints (see Table 10), decreased implantation index
represents the most sensitive (i.e., lowest) candidate POD for deriving a subchronic p-RfD.
Therefore, the BMDLisd (HED) for decreased implantation index in female rats exposed to
/Moluic acid during premating, mating, gestation, and lactation (13.5 mg/kg-day) is selected as
the POD for derivation of the subchronic p-RfD.
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Table 10. Candidate PODs for Derivation of the Subchronic p-RfDa'b
Endpoint
Male
Female
Comments
NOAEL
(HED)
mg/kg-d
LOAEL
(HED)
mg/kg-d
BMDL
(HED)
mg/kg-de
POD
NOAEL
(HED)
mg/kg-d
LOAEL
(HED)
mg/kg-d
BMDL
(HED)
mg/kg-de
POD
Fertility Index
75.0
250.0
65.3
BMDLio
(HED)
78.0
260.0
67.8
BMDLio (HED)
NA
Implantation index
NDr
NDr
NDr
NDr
25.0
78.0
13.5f
BMDLisd (HED)
Most sensitive
endpoint
Number of pups born0
NDr
NDr
NDr
NDr
25.0
78.0
29.9
BMDLisd (HED)
NA
Number of live pups on LD 0°
NDr
NDr
NDr
NDr
78.0
260.0
42.7
BMDLisd (HED)
NA
Number of live pups on LD 4°
NDr
NDr
NDr
NDr
78.0
260.0
40.6
BMDLisd (HED)
NA
Decreased gestational
body-weight gain0
NDr
NDr
NDr
NDr
25.0
78.0
DUB
NOAEL (HED)
BMD modeling
was not possible
because variances
were not reported
Decreased absolute epididymis
weightd
75.0
250.0
94.6
BMDLi sd
(HED)
NDr
NDr
NDr
NDr
NA
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Table 10. Candidate PODs for Derivation of the Subchronic p-RfDa'b
Endpoint
Male
Female
Comments
NOAEL
(HED)
mg/kg-d
LOAEL
(HED)
mg/kg-d
BMDL
(HED)
mg/kg-de
POD
NOAEL
(HED)
mg/kg-d
LOAEL
(HED)
mg/kg-d
BMDL
(HED)
mg/kg-de
POD
Decreased relative epididymis
weightd
75.0
250.0
DUB
NOAEL
(HED)
NDr
NDr
NDr
NDr
BMD modeling
failed
Increased incidence of animals
with fewer numbers of
spermatozoad
75.0
250.0
DUB
NOAEL
(HED)
NDr
NDr
NDr
NDr
BMD modeling
was not attempted
due to the lack of
dose-response
aSfairota et al. (2008).
' Following U.S. EPA (2011b) guidance, animal doses from candidate principal studies were converted to HEDs through the application of a DAF. DAFs for each dose
are calculated as follows: DAF = (BW,14 BWh1/4), where BWa = animal body weight and BWh = human body weight. For all DAF calculations, a reference human
body weight (BWh) of 70 kg (U.S. EPA. 1988) was used.
°DAFs were calculated using study-specific time-weighted body weights (BW.,) data for female rats during pre mating and gestation from Shirota et al. (2008).
•'DAFs were calculated using reference body weights (BW„) for S-D male rats following subchronic-duration exposure (U.S. EPA. 1988).
eAll modeling was conducted using U.S. EPA BMDS (Version 2.5). BMD analysis details are available in Appendix C.
fAn adequate fit was achieved when the high-dose group was dropped.
BMD = benchmark dose; BMDL = benchmark dose lower confidence limit; BMDS = Benchmark Dose Software; BW = body weight; DAF = dosimetric adjustment
factor; DUB = data unamenable to BMDS; HED = human equivalent dose; LD = lactation day; LOAEL = lowest-observed-adverse-effect level; NA = not applicable;
NDr = not determined; NOAEL = no-observed-adverse-effect level; POD = point of departure; p-RfD = provisional reference dose; S-D = Sprague-Dawley;
SD = standard deviation.
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The subchronic p-RfD for/Moluic acid, based on a BMDLisd (HED) of 13.5 mg/kg-day
(see Table 9 and 10) for decreased implantation index in female rats and composite uncertainty
factor (UFc), is derived as follows:
Subchronic p-RfD = BMDLisd (HED) ^ UFc
= 13.5 mg/kg-day -^300
= 5 x 10"2 mg/kg-day
Table 11 summarizes the uncertainty factors for the subchronic p-RfD for /Moluic acid.
Table 11. Uncertainty Factors for the Subchronic p-RfD for />-Toluic Acid
UF
Value
Justification
UFa
3
A UFa of 3 (10°5) is applied to account for uncertainty in characterizing the toxicokinetic or
toxicodynamic differences between rats and humans following oral /Holuic exposure. The
toxicokinetic uncertainty has been accounted for by calculating a HED through application of a
DAF as outlined in the EPA's Recommended Use of Body WeightB/4 as the Default Method in
Derivation of the Oral Reference Dose (TJ.S. EPA. 20 lib).
UFd
10
A UFd of 10 is applied to account for deficiencies and uncertainties in the database. The database
is limited to a 28-d reoeated-dose studv and a R/D toxicity screening studv in rats (Shirota et al..
2008). The R/D screening studv indicates that R/D endooints are sensitive targets of o-toluic acid
following oral exposure, but was not a definitive study of reproductive or developmental effects.
The database is lacking subchronic-duration, two-generation reproduction, and comprehensive
developmental toxicity studies.
UFh
10
A UFh of 10 is applied to account for human variability in susceptibility, in the absence of
information to assess toxicokinetic and toxicodynamic variability of /Holuic acid in humans.
UFl
1
A UFl of 1 is applied because the POD is a BMDL.
UFS
1
A UFS of 1 is applied because the POD is based on a R/D toxicity study wherein parental rats were
exposed for 6 wk.
UFC
300
Composite UF = UFA x UFD x UFH x UFL x UFS.
BMDL = benchmark dose lower confidence limit; HED = human equivalent dose; POD = point of departure;
p-RfD = provisional reference dose; R/D = reproductive/developmental; UF = uncertainty factor;
UFa = interspecies uncertainty factor; UFC = composite uncertainty factor; UFD = database uncertainty factor;
UFh = intraspecies variability uncertainty factor; UFL = LOAEL-to-NOAEL uncertainty factor;
UFS = subchronic-to-chronic uncertainty factor.
The confidence in the subchronic p-RfD for /Moluic acid is low, as described in Table 12.
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Table 12. Confidence Descriptors for the Subchronic p-RfD for />-Toluic Acid
Confidence Categories
Designation
Discussion
Confidence in study
M
Confidence in the orincroal studv (Shirota et al.. 2008) is medium. The
principal study is a peer-reviewed, R/D toxicity screening study. The
study was conducted according to OECD guidelines (OECD Test
Guideline 421), with an adequate number of dose groups and dose
spacing, group sizes, and quantitation of results to describe
dose-response relationships for effects. The study identified sensitive
R/D effects and identified NOAEL and LOAEL values. Confidence is
not considered high because some details were not provided in the report
(i.e., variances for maternal body-weight gain; whether analyses were
conducted using litters/dams as the experimental unit).
Confidence in database
L
Confidence in the database is low. The database is limited to a 28-d
repeated-dose study that found no clear evidence of treatment-related
effects and a R/D toxicity screening studv (Shirota et al.. 2008) that
identified R/D effects. No subchronic-duration, two-generation
reproductive, or comprehensive developmental toxicity studies are
available.
Confidence in
subchronic p-RfDa
L
The overall confidence in the subchronic p-RfD is low.
aThe overall confidence cannot be greater than the lowest entry in the table (low).
L = low; LOAEL = lowest-observed-adverse-effect level; M = medium; NOAEL = no-observed-adverse-effect
level; OECD = Organisation for Economic Co-operation and Development; p-RfD = provisional reference dose;
R/D = reproductive/developmental.
Derivation of a Chronic Provisional Reference Dose
There are no chronic-duration studies of humans or animals orally exposed to /Moluic
acid. In the absence of additional data, the subchronic p-RfD based on decreased implantation
index in female rats exposed to/Moluic acid in a R/D toxicity study (Shirota et aL 2008) is used
as the basis for deriving a chronic p-RfD.
The chronic p-RfD for /Moluic acid, based on a BMDLisd (HED) of 13.5 mg/kg-day
(see Table 9 and 10) for decreased implantation index in female rats and UFc is derived as
follows:
Chronic p-RfD = BMDLisd (HED) UFc
= 13.5 mg/kg-day ^ 3,000
= 5 x 10"3 mg/kg-day
Table 13 summarizes the uncertainty factors for the chronic p-RfD for /Moluic acid.
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Table 13. Uncertainty Factors for the Chronic p-RfD for />-Toluic Acid
UF
Value
Justification
UFa
3
A UFa of 3 (10°5) is applied to account for uncertainty in characterizing the toxicokinetic or
toxicodynamic differences between rats and humans following oral /Holuic exposure. The
toxicokinetic uncertainty has been accounted for by calculating a HED through application of a
DAF as outlined in the EPA's Recommended Use of Body WeightB/4 as the Default Method in
Derivation of the Oral Reference Dose ('U.S. EPA. 20 lib).
UFd
10
A UFd of 10 is applied to account for deficiencies and uncertainties in the database. The database
is limited to a 28-d reoeated-dose studv and a R/D toxicity screening studv in rats fShirota et al..
2008). The R/D studv indicates that R/D endooints are sensitive tareets of o-toluic acid following
oral exposure, but was not a definitive study of reproductive or developmental effects. The
database is lacking chronic-duration, two-generation reproductive, and comprehensive
developmental toxicity studies.
UFh
10
A UFh of 10 is applied to account for human variability in susceptibility, in the absence of
information to assess toxicokinetic and toxicodynamic variability of /Holuic acid in humans.
UFl
1
A UFl of 1 is applied because the POD is a BMDL.
UFS
10
A UFS of 10 is applied to account for exposure for less than a complete reproductive cycle of a
single generation in the R/D toxicity screening study used to identify the POD. Furthermore, the
critical effect (i.e., decreased implantation index) was observed in female rats that were treated for
6 wk, which is less than chronic duration.
UFC
3,000
Composite UF = UFA x UFD x UFH x UFL x UFS.
BMDL = benchmark dose lower confidence limit; HED = human equivalent dose; POD = point of departure;
p-RfD = provisional reference dose; R/D = reproductive/developmental; UF = uncertainty factor;
UFa = interspecies uncertainty factor; UFC = composite uncertainty factor; UFD = database uncertainty factor;
UFh = intraspecies variability uncertainty factor; UFL = LOAEL-to-NOAEL uncertainty factor;
UFS = subchronic-to-chronic uncertainty factor.
The confidence in the chronic p-RfD for /Moluic acid is low, as described in Table 14.
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Table 14. Confidence Descriptors for the Chronic p-RfD for />-Toluic Acid
Confidence Categories
Designation
Discussion
Confidence in study
M
Confidence in the Drincioal study (Shirota et al.. 2008) is medium. The
principal study is a peer-reviewed, R/D toxicity study. The study was
conducted according to OECD guidelines (OECD Test Guideline 421),
with an adequate number of dose groups and dose spacing, group sizes,
and quantitation of results to describe dose-response relationships for
critical effects. The study identified sensitive R/D effects and identified
NOAEL and LOAEL values. Confidence is not considered high because
some details were not provided in the report (i.e., variances for maternal
body-weight gain, whether analyses were conducted using litters/dams
as the experimental unit).
Confidence in database
L
Confidence in the database is low. No chronic-duration, two-generation
reproductive, or comprehensive developmental toxicity studies are
available. The R/D toxicity screening study included exposure for less
than a complete reproductive cycle of a single generation.
Confidence in the
chronic p-RfDa
L
The overall confidence in the chronic p-RfD is low.
aThe overall confidence cannot be greater than the lowest entry in the table (low).
L = low; LOAEL = lowest-observed-adverse-effect level; M = medium; NOAEL = no-observed-adverse-effect
level; OECD = Organisation for Economic Co-operation and Development; p-RfD = provisional reference dose;
R/D = reproductive/developmental.
DERIVATION OF INHALATION REFERENCE CONCENTRATIONS
No studies have been identified regarding toxicity of /Moluic acid to humans or animals
by inhalation; therefore, subchronic and chronic provisional reference concentrations (p-RfCs)
are not derived.
CANCER WEIGHT-OF-EVIDENCE DESCRIPTOR
No relevant data are available. Under the U.S. EPA Cancer Guidelines (U.S. EPA.
2005). there is "Inadequate Information to Assess Carcinogenic Potential" of /Moluic acid
(see Table 15).
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Table 15. Cancer WOE Descriptor for />-Toluic Acid
Possible WOE Descriptor
Designation
Route of Entry (oral,
inhalation, or both)
Comments
"Carcinogenic to Humans "
NS
NA
There are no human data to support this.
"Likely to Be Carcinogenic to
Humans "
NS
NA
There are no suitable animal studies to
support this.
"Suggestive Evidence of
Carcinogenic Potential"
NS
NA
There are no suitable animal studies to
support this.
"Inadequate Information to
Assess Carcinogenic Potential"
Selected
Both
This descriptor is selected due to the
lack of any information on the
carcinogenicity of /Moluic acid.
"Not Likely to Be Carcinogenic to
Humans "
NS
NA
There are no suitable animal studies to
support this.
NA = not applicable; NS = not selected; WOE = weight of evidence.
DERIVATION OF PROVISIONAL CANCER POTENCY VALUES
The lack of data on the carcinogenicity of /Moluic acid precludes deriving quantitative
estimates for either oral (provisional oral slope factor [p-OSF]) or inhalation (provisional
inhalation unit risk [p-IUR]) exposure.
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APPENDIX A. SCREENING PROVISIONAL VALUES
No screening provisional values for /Moluic acid are derived.
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APPENDIX B. DATA TABLES
Table B-l. Hematology, Clinical Chemistry, and Urinalysis Data for Rats Treated Orally with />-Toluic Acid in a
Repeated-Dose 28-Day Oral Toxicity Study"
Effect
Males
Females
Males
(end of recovery)
Females
(end of recovery)
Dose (mg/kg)
0
100
300
1,000
0
100
300
1,000
0
1,000
0
1,000
RBC (x 104/(iL)
755 ±53
780 ± 15
770 ± 27
755 ± 18
742 ± 19
771 ±26
750 ± 25
751 ±30
797 ± 13
766 ± 22**
749 ± 25
766 ± 24
Hb (g/dL)
14.9 ±0.6
15.2 ±0.2
15.2 ±0.3
15.0 ±0.2
14.8 ±0.3
15.1 ± 0.5
14.9 ±0.3
14.7 ±0.5
15.2 ±0.1
14.6 ±0.3**
14.5 ±0.4
14.4 ±0.7
Hct (%)
44.8 ±2.9
46.0 ±0.7
45.5 ± 1.1
45.2 ±0.4
44.2 ± 1.0
44.9 ± 1.3
44.4 ±0.7
43.6 ± 1.9
45.3 ±0.8
43.5 ± 1.0**
42.6 ± 1.3
42.7 ± 1.9
Total protein (g/dL)
5.0 ±0.2
5.2 ±0.2
5.1 ± 0.1
5.0 ±0.0
5.4 ±0.3
5.3 ±0.3
5.2 ±0.3
4.8 ±0.3**
5.6 ±0.4
5.4 ±0.1
5.5 ±0.1
5.70 ±0.3
AST (U/L)
72 ± 10
66 ± 11
67 ±7
88 ±24
69 ±3
66 ±5
69 ±8
94 ± 16*
83 ± 14
66 ±2
62 ±3
66 ±5
Eosinophil
1 ±0
1 ±0
1 ±0
0±0*
1 ±0
1 ± 1
1±0
1 ±0
1±0
1 ± 1
2 ± 1
1 ± 1
Urine volume on
D 23 of treatment
or D 9 of recovery
(mL/24 hr)
15.6 ±2.2
15.6 ±2.1
20.9 ±4.7*
23.8 ±4.7**
11.7 ± 3.5
11.9 ± 3.4
13.0 ±4.3
22.1 ±7.5**
18.3 ±4.7
24.3 ±4.6
13.3 ±2.8
18.3 ±5.6
Specific Gravity
1.058
± 0.0008
1.051
± 0.0007
1.043
±0.011**
1.045
± 0.006**
1.045
±0.012
1.046
± 0.008
1.043
± 0.007
1.038
± 0.009
1.056
± 0.009
1.038
± 0.0006**
1.041
±0.010
1.044
±0.011
aShirota et al. (2008).
* Significantly different from controls (p < 0.05) as presented by study authors.
**Significantly different from controls (p < 0.01) as presented by study authors.
AST = aspartate transaminase (also known as SGOT); Hb = hemoglobin; Hct = hematocrit; RBC = red blood cell; SGOT = glutamic oxaloacetic transaminase.
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Table B-2. Body Weights and Body-Weight Gains in Female S-D Crj:CD(SD) Rats Exposed
to /7-Toluic Acid via Gavage during Premating, Mating, Gestation, and Lactation3'b
Endpoint
Exposure Group, mg/kg-d
0
100
300
1,000
Body weight, gc
Premating
D 1
236.2
244.7 (+4%)
242.4 (+3%)
242.4 (+3%)
D 7
246.8
250.6 (+2%)
249.1 (+1%)
248.3 (+1%)
D 14
258.1
260.4 (+1%)
264.3 (+2%)
264.3 (+2%)
Gestation
DO
267.9
267.9 (0%)
275.6 (+3%)
277.2 (+3%)
D 7
304.2
304.9 (0%)
313.4 (+3%)
311.9 (+3%)
D 14
339.7
339.7 (0%)
350.5 (+3%)
350.5 (+3%)
D 20
416.8
413.7 (-1%)
415.3 (0%)
413.7 (-1%)
Lactation
DO
297.2
304.9 (+2%)
336.6* (+13%)
337.3* (+13%)
D 4
326.5
335.8 (+3%)
349.7 (+7%)
341.2 (+5%)
Body weight gain, gc
Premating
D 1-7
10.6
8.7 (-18%)
8.8 (-17%)
13.2 (+25%)
D 7-14
10.7
11.4 (+7%)
15.5 (+45%)
16.6 (+55%)
Gestation
D 0-7
35.2
35.0 (-1%)
40.5 (+15%)
36.1 (+3%)
D 7-14
34.6
36.3 (+5%)
36.8 (+6%)
38.5 (+11%)
D 14-20
74.1
70.1 (-5%)
61.4* (-17%)
55.7** (-25%)
Lactation
D 0-4
29.4
31.5 (+7%)
16.7 (-43%)
8.0** (-73%)
aSfairota et al. (2008).
bMeanbody weight and relative body-weight values were estimated from Figure 5 of the study report with digitizing
software (Softonic Grab It! XP2 software) because numerical values were not available. Variances were not
provided.
°Mean body weight; value in parentheses is % change relative to control = ([treatment mean - control
mean] + control mean) x 100.
* Significantly different from controls (p < 0.05), as reported by the study authors.
**Significantly different from controls (p < 0.01), as reported by the study authors.
S-D = Sprague-Dawley.
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Table B-3. Selected Reproductive Parameters in S-D Crj:CD(SD) Rats Exposed to
/j-Toluic Acid via Gavage during Premating, Mating, Gestation, and Lactation3
Endpoint
Exposure Group, mg/kg-d
0
100
300
1,000
Mating performance
Copulated pairs/cohoused pairsb
13/13 (100%)
13/13 (100%)
12/13 (92%)
13/13 (100%)
Pregnant females/copulated pairsb
13/13 (100%)
13/13 (100%)
11/12 (92%)
9/13* (69%)
Pairing days until copulation0
3.0 ±3.4
2.4 ± 1.3 (-20%)
2.4 ± 1.3 (-20%)
3.2 ±3.3 (+7%)
Estrus cycles until copulation0
1.0 ±0.0
1.0 ±0.0(0%)
1.0 ± 0.0 (0%)
1.1 ±0.3 (+10%)
Pregnancy data
Pregnant females with live pupsb
13/13 (100%)
13/13 (100%)
11/11 (100%)
9/9 (100%)
Gestation length in d°
22.3 ±0.5
22.5 ±0.5 (+1)
22.3 ± 0.5 (0%)
22.8 ± 0.4 (+2%)
Number of corpora lutea0
16.2 ± 1.3
15.7 ± 1.3 (-3%)
16.2 ± 1.5 (0%)
15.9 ± 1.3 (-2%)
Number of implantation sites0
16.0 ± 1.3
15.4 ± 1.0 (-4%)
14.0 ± 2.4 (-13%)
12.1 ±5.3 (-24%)
Implantation index (%)°-d
99.1 ±2.2
98.2 ±3.5
(-1%)
86.5 ± 12.6**
(-13%)
75.9 ±32.6*
(-23%)
LDO
Number of pups born0
15.2 ± 1.4
14.1 ± 1.8
("7%)
12.5 ±2.1**
(-18%)
10.2 ±5.1**
(-33%)
Delivery index (%)°-e
94.7 ±5.2
91.4 ±8.5 (-3%)
90.1 ±8.4 (-5%)
82.9 ± 19.5 (-12)
Number of live pups0
14.3 ± 1.7
14.1 ± 1.8 (-1%)
12.3 ± 2.2 (-14%)
10.0 ± 5.0* (-30%)
Birth index (%)°f
89.7 ± 10.4
91.4 ±8.5 (+2%)
88.0 ±9.1 (-2%)
81.5 ± 19.8 (-9%)
Live birth index (%)°-g
94.8 ± 10.5
100.0 ± 0 (+5%)
97.6 ± 4.2 (+3%)
98.2 ±3.7 (+4%)
Sex ratio, M:F (%)°
54.1 ± 14.3
51.9 ± 12.8
(-4%)
46.6 ± 13.8
(-14%)
59.8 ± 17.7
(+11%)
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Table B-3. Selected Reproductive Parameters in S-D Crj:CD(SD) Rats Exposed to
/j-Toluic Acid via Gavage during Premating, Mating, Gestation, and Lactation3
Endpoint
Exposure Group, mg/kg-d
0
100
300
1,000
Pregnancy data, continued
LD4
Number of live pups0
14.3 ± 1.7
13.9 ± 1.8 (-3%)
12.3 ± 2.2 (-14%)
9.7 ±5.3* (-32%)
Viability index (%)c h
100.0 ±0
99.0 ±3.7 (-1%)
100 ± 0 (0%)
88.1 ±33.1
(-12%)J
Sex ratio (%)c-1
54.1 ± 14.3
52.3 ± 12.3
(-3%)
46.6 ± 13.8 (-14%)
54.4 ± 9.5 (+1%)
aShirota et al. (2008).
bNumber of animals/total in group; value in parentheses expressed as % of animals.
°Mean ± SD. Percent change relative to control = ([treatment mean - control mean] control mean) x 100.
dDefined as (number of implantation sites ^ number of corpora lutea) x 100.
"Defined as (number of pups born number of implantation sites) x 100.
fDefined as (number of live pups on LD 0 number of implantation sites) x 100.
gDefined as (number of live pups on LD 0 number of pups born) x 100.
hNot defined by the study authors; interpreted by the reviewer as: (number of live pups on LD 4 number of live
pups onLD 0) x 100.
'Defined as (number of live male pups ^ number of live pups) x 100.
JValue (88.1%) as reported by the study authors appears to be an error. The calculated value was 97%.
* Significantly different from controls (p < 0.05), as reported by study authors.
**Significantly different from controls (p < 0.01), as reported by study authors.
F = female(s); LD = lactation day; M = male(s); S-D = Sprague-Dawley; SD = standard deviation.
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Table B-4. Selected Effects on Reproductive Organ Weights and Histopathology in Male
S-D Crj:CD(SD) Rats Exposed to/>-Toluic Acid via Gavage for 42 Days3
Endpoint
Exposure Group, mg/kg-d
0
100
300
1,000
Animal data
Number of animals
13
13
13
13
Terminal body weight (g)b
527.0 ±37.8
549.9 ± 42.8 (+4%)
541.6 ±26.6 (+3%)
542.4 ± 30.7 (+3%)
Organ weights
Absolute testes weight (g)b
3.37 ±0.24
3.29 ±0.19 (-2%)
3.29 ± 0.22 (-2%)
3.31 ±0.17 (-2%)
Relative testes weight (g/100 g)b
0.64 ±0.07
0.60 ± 0.06 (-6%)
0.61 ± 0.04 (-5%)
0.61 ± 0.05 (-5%)
Absolute epididymis weight (g)b
1.28 ±0.08
1.27 ±0.08 (-1%)
1.24 ±0.07 (-3%)
1.13 ±0.09* (-12%)
Relative epididymis weight
(g/ioo g)b
0.24 ±0.03
0.23 ± 0.02 (-4%)
0.23 ± 0.01 (-4%)
0.21 ±0.02* (-13%)
Histopathology
Testis, seminiferous tubule
Atrophy, focal, bilateral0
1/13 (8%)
1/13 (8%)
0/13 (0%)
0/13 (0%)
Multinucleated giant cell0
0/13 (0%)
0/13 (0%)
0/13 (0%)
1/13 (8%)
Epididymis, cauda
Few sperm, lumen, bilateral0
0/13 (0%)
0/13 (0%)
0/13 (0%)
13/13* (100%)
Cell debris, lumen, bilateral0
1/13 (8%)
0/13 (0%)
0/13 (0%)
5/13 (38%)
Spermatid granuloma,
unilateral0
0/13 (0%)
0/13 (0%)
1/13 (8%)
0/13 (0%)
"Shirota et al. (2008).
bMean± SD. Percent change relative to control = ([treatment mean - control mean] control mean) x 100.
°Number of animals ^ total in group with lesion; value in parentheses expressed as % of animals.
* Significantly different from controls (p < 0.01), as reported by study authors.
S-D = Sprague-Dawley; SD = standard deviation.
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Table B-5. Selected Non-neoplastic Lesions in Male S-D Crj:CD(SD) Rats Exposed to
/j-Toluic Acid via Gavage for 42 Days3
Endpoint
Exposure Group, mg/kg-d
0
100
300
1,000
Epididymidis, caudab
Few number of sperm, lumen, bilateral
0/13 (0%)
0/13 (0%)
0/13 (0%)
13/13* (100%)
Normal (-)
13/13 (100%)
13/13 (100%)
13/13 (100%)
0/13 (0%)
Very slight (±)
0/13 (0%)
0/13 (0%)
0/13 (0%)
11/13 (85%)
Slight (+)
0/13 (0%)
0/13 (0%)
0/13 (0%)
2/13 (15%)
Moderate (++)
0/13 (0%)
0/13 (0%)
0/13 (0%)
0/13 (0%)
Severe (+++)
0/13 (0%)
0/13 (0%)
0/13 (0%)
0/13 (0%)
Cell debris, lumen, bilateral
1/13 (8%)
0/13 (0%)
0/13 (0%)
5/13 (38%)
Normal (-)
12/13 (92%)
13/13 (100%)
13/13 (100%)
8/13 (62%)
Very slight (±)
1/13 (8%)
0/13 (0%)
0/13 (0%)
5/13 (38%)
Slight (+)
0/13 (0%)
0/13 (0%)
0/13 (0%)
0/13 (0%)
Moderate (++)
0/13 (0%)
0/13 (0%)
0/13 (0%)
0/13 (0%)
Severe (+++)
0/13 (0%)
0/13 (0%)
0/13 (0%)
0/13 (0%)
Spermatid granuloma, unilateral
0/13 (0%)
0/13 (0%)
1/13 (8%)
0/13 (0%)
Normal (-)
13/13 (100%)
13/13 (100%)
12/13 (92%)
13/13 (100%)
Very slight (±)
0/13 (0%)
0/13 (0%)
0/13 (0%)
0/13 (0%)
Slight (+)
0/13 (0%)
0/13 (0%)
1/13 (8%)
0/13 (0%)
Moderate (++)
0/13 (0%)
0/13 (0%)
0/13 (0%)
0/13 (0%)
Severe (+++)
0/13 (0%)
0/13 (0%)
0/13 (0%)
0/13 (0%)
aShirota et al. (2008).
bNumber of animals group with lesion; value in parentheses expressed as % of animals.
* Significantly different from controls (p < 0.01) for incidence and severity, respectively, as reported by study
authors.
S-D = Sprague-Dawley.
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APPENDIX C. BENCHMARK DOSE MODELING RESULTS
MODELING PROCEDURE FOR CONTINUOUS DATA
Benchmark dose (BMD) modeling of continuous data is conducted with EPA's
Benchmark Dose Software (BMDS, Version 2.5). All continuous models available within the
software are fit using a default benchmark response (BMR) of 1 standard deviation (SD) relative
risk unless a biologically determined BMR is available (e.g., BMR 10% relative deviation for
body weight based on a biologically significant weight loss of 10%), as outlined in the
Benchmark Dose Technical Guidance (U.S. EPA. 2012b). An adequate fit is judged based on
the x2 goodness-of-fit p-value (p > 0.1), magnitude of the scaled residuals in the vicinity of the
BMR, and visual inspection of the model fit. In addition to these three criteria forjudging
adequacy of model fit, a determination is made as to whether the variance across dose groups is
homogeneous. If a homogeneous variance model is deemed appropriate based on the statistical
test provided by BMDS (i.e., Test 2), the final BMD results are estimated from a homogeneous
variance model. If the test for homogeneity of variance is rejected (p< 0.1), the model is run
again while modeling the variance as a power function of the mean to account for this
nonhomogeneous variance. If this nonhomogeneous variance model does not adequately fit the
data (i.e., Test 3;p<0. 1), the data set is considered unsuitable for BMD modeling. Among all
models providing adequate fit, the lowest benchmark dose lower confidence limit/benchmark
concentration lower confidence limit (BMDL/BMCL) is selected if the BMDL/BMCL estimates
from different models vary >threefold; otherwise, the BMDL/BMCL from the model with the
lowest Akaike's information criterion (AIC) is selected as a potential point of departure (POD)
from which to derive the reference dose/reference concentration (RfD/RfC).
In addition, in the absence of a mechanistic understanding of the biological response to a
toxic agent, data from exposures much higher than the study lowest-observed-adverse-effect
level (LOAEL) do not provide reliable information regarding the shape of the response at low
doses. Such exposures, however, can have a strong effect on the shape of the fitted model in the
low-dose region of the dose-response curve. Thus, if lack of fit is due to characteristics of the
dose-response data for high doses, then thq Benchmark Dose Technical Guidance document
allows for data to be adjusted by eliminating the high-dose group (U.S. EPA. 2012b). Because
the focus of BMD analysis is on the low-dose regions of the response curve, elimination of the
high-dose group is deemed reasonable.
MODELING PROCEDURE FOR DICHOTOMOUS DATA
The BMD modeling of dichotomous data was conducted with the EPA's BMDS
(Version 2.2.2). For these data, all of the dichotomous models (i.e., Gamma, Multistage,
Logistic, LogLogistic, Probit, LogProbit, and Weibull models) available within the software
were fit using a default BMR of 10% extra risk based on the EPA's Benchmark Dose Technical
Guidance Document (U.S. EPA. 2012b). Adequacy of model fit was judged based on the
goodness-of-fit p-v alue (p> 0.1), magnitude of scaled residuals in the vicinity of the BMR, and
visual inspection of the model fit. Among all models providing adequate fit, the lowest BMDL
was selected if the BMDLs estimated from different models varied greater than threefold;
otherwise, the BMDL from the model with the lowest AIC was selected as a potential POD from
which to derive a p-RfD.
34
/?-Toluic Acid
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BMD MODELING TO IDENTIFY POTENTIAL PODs FOR DERIVING A
PROVISIONAL REFERENCE DOSE
The data sets for sensitive reproductive/developmental (R/D) endpoints observed in the
principal study of rats exposed orally to /Moluic acid during premating, mating, gestation, and
lactation (Shirota et al.. 2008) were selected to determine potential PODs for the provisional
reference dose (p-RfD), using BMD analysis. Table 7 shows the data that were modeled.
Summaries of modeling approaches and results (see Tables C-l to C-8 and Figures C-l to C-8)
for each data set follow.
Decreased Implantation Index in Female Rats Exposed to /J-Toluic Acid via Gavage during
Premating, Mating, Gestation, and Lactation
The procedure outlined above was applied to the data for decreased implantation index in
the R/D toxicity study in rats (Shirota et al.. 2008) (see Table 7). Table C-l summarizes the
BMD modeling results. The constant variance model did not provide adequate fit to the variance
data. Variance was modeled adequately using the power model in the BMDS, but none of the
available models fit the means with the variance model applied. The high-dose group was
dropped in an effort to model the data. Using the reduced data set, the constant variance model
did not provide adequate fit to the variance data, but the nonconstant variance model did. With
the nonconstant variance model applied, the only models that provided adequate fit were the
Exponential models 2 and 4 and the linear model. BMDLs for models providing adequate fit
were considered to be sufficiently close (i.e., differed by
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09-28-2017
Table C-l. Modeling Results for Implantation Index Data in Female Rats Exposed to
/j-Toluic Acid via Gavage during Premating, Mating, Gestation, and Lactation11
Model
Variance
/>-Valucb
/7-Value
for Fitb
Scaled Residual
for Dose Group0
AIC
BMDisd
BMDLisd
Exponential (model 2)'L e
0.1912
0.1259
1.138
154.7342
22.2487
13.116
Exponential (model 3 )'L e
0.1912
NA
0.4058
154.0213
33.314
18.2503
Exponential (model 4)'L e
0.1912
0.1259
1.138
154.7342
22.2487
12.8216
Lineard'e'f
0.2474
0.1102
1.15
154.572929
22.2766
13.4576
Polynomial (2-degree)4 e
0.2474
NA
0.406
154.021294
33.7566
17.8553
Polynomial (3-degree)4 e
0.2474
NA
0.406
156.021294
35.6382
17.6413
Power4 e
0.1912
NA
0.406
154.021294
33.4727
18.1475
aSfairota et al. (2008).
bValues <0.10 fail to meet conventional goodness-of-fit criteria.
°Scaled residuals at doses immediately below and above the BMD; also the largest residual at any dose.
Coefficients restricted to be negative.
Tower restricted to >1.
Selected model.
AIC = Akaike's information criterion; BMD = maximum likelihood estimate of the exposure concentration
associated with the selected BMR; BMDL = 95% lower confidence limit on the BMD; BMR = benchmark
response; NA = not applicable (BMDL computation failed or the BMD was higher than the highest dose tested);
SD = standard deviation.
36
/>-Toluic Acid
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Linear Model, with BMR of 1 Std. Dev. for the BMD and 0.95 Lower Confidence Limit for the BMDL
Linear
100
95
90
85
80
BMDL
BMD
0
10
20
30
40
50
60
70
80
dose
16:08 05/11 2017
Figure C-l. Linear Model for Implantation Index Data (Reduced Data Set) in Female Rats
Exposed to »-Toluic Acid via Gavage during Premating, Mating, Gestation, and Lactation
(Shirota et al.. 2008)
Text Output for Figure C-l:
Polynomial Model. (Version: 2.17; Date: 01/28/2013)
Input Data File:
C:/Users/JKaiser/Desktop/BMDS24 0/Data/1in_Implantation_pta_nohd_Lin-ModelVariance-BMRl
Std.(d)
Gnuplot Plotting File:
C:/Users/JKaiser/Desktop/BMDS24 0/Data/1in_Implantation_pta_nohd_Lin-ModelVariance-BMRl
Std.pit
Tue May 16 10:56:35 2017
BMDS Model Run
The form of the response function is:
Y[dose] = beta_0 + beta_l*dose + beta_2*dose/s2 + ...
Dependent variable = Mean
Independent variable = Dose
The polynomial coefficients are restricted to be negative
The variance is to be modeled as Var(i) = exp(lalpha + log(mean(i)) * rho)
Total number of dose groups = 3
37
/>-Toluic Acid
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09-28-2017
Total number of records with missing values = 0
Maximum number of iterations = 5 00
Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008
Default Initial Parameter Values
lalpha = 3.96511
rho = 0
beta_0 = 100.463
beta 1 = -0.170771
Asymptotic Correlation Matrix of Parameter Estimates
lalpha rho beta_0 beta_l
lalpha 1 -1 -0.18 0.35
rho -1 1 0.18 -0.35
beta_0 -0.18 0.18 1 -0.52
beta 1 0.35 -0.35 -0.52 1
Parameter Estimates
Interval
Variable
Limit
lalpha
293.983
rho
7.86667
beta_0
100.501
beta_l
0.0429776
Estimate
223.555
-48 .2942
-63.7126
99.3548
-0.093378
-0.177613
Std. Err.
35.9332
-32.8758
0.58484
-0.0091435
95.0% Wald Confidence
Lower Conf. Limit Upper Conf.
153.127
98.2086
Table of Data and Estimated Values of Interest
Dose N Obs Mean Est Mean Obs Std Dev Est Std Dev Scaled Res.
0 13 99.1 99.4 2.2 2.08 -0.442
25 13 98.2 97 3.5 3.69 1.15
78 11 86.5 92.1 12.6 13.1 -1.41
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
38
/?-Toluic Acid
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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
A1
A2
A3
fitted
R
Log(likelihood)
-90.290158
-71.341768
-72.010647
-73.286465
-99.435945
# Param's
4
6
5
4
AIC
188.580316
154.683536
154.021294
154.572929
202.871890
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 56.1884 4 <.0001
Test 2 37.8968 2 <.0001
Test 3 1.33776 1 0.2474
Test 4 2.55164 1 0.1102
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 = 22.2766
BMDL = 13.4576
39 /?-Toluic Acid
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09-28-2017
Decreased Number of Pups Born for Female Rats Exposed to /J-Toluic Acid via Gavage
during Premating, Mating, Gestation, and Lactation
The procedure outlined above was applied to the data for decreased number of pups born
in the R/D toxicity study in rats (Shirota et al.. 2008) (see Table 7). Table C-2 summarizes the
BMD modeling results. The constant variance model did not provide adequate fit to the variance
data, but the nonconstant variance model did. With the nonconstant variance model applied, all
models provided adequate fit to the means. BMDLs for models providing adequate fit were
considered to be sufficiently close (differed by >two- to threefold, but
-------
FINAL
09-28-2017
Table C-2. Modeling Results for Number of Pups Born Data for Female Rats Exposed to />-Toluic Acid via Gavage during
Premating, Mating, Gestation, and Lactation"
Model
Variance />-Valucb
/j-Valuc for Fitb
Scaled Residual for Dose Group0
AIC
BMDisd
BMDLisd
Exponential (model 2)d e f
0.7989
0.576
-0.3771
121.0425
49.7412
29.8647
Exponential (model 3)d e f
0.7989
0.6834
-0.3771
121.0425
49.7412
29.8647
Exponential (model 4)'L e
0.7989
0.6834
-0.1834
122.1053
36.3464
18.5538
Exponential (model 5)'L e
0.7989
0.7306
-0.1834
122.1053
36.3464
18.5538
Hill4 e
0.7989
0.3263
-0.129
122.057565
35.0056
17.7975
Linear4 e
0.7989
0.3263
-0.881
122.179185
63.2159
39.8283
Polynomial (2-degree)4 e
0.7989
0.3263
-0.881
122.179185
63.2159
39.8283
Polynomial (3-degree)4 e
0.7989
0.3263
-0.881
122.179185
63.2159
39.8283
Power4 e
0.7989
0.3263
-0.881
122.179185
63.2159
39.8283
aSfairota et al. (2008).
bValues <0.10 fail to meet conventional goodness-of-fit criteria.
°Scaled residuals at doses immediately below and above the BMD; also the largest residual at any dose.
Coefficients restricted to be negative.
Tower restricted to >1.
Selected model.
AIC = Akaike's information criterion; BMD = maximum likelihood estimate of the exposure concentration associated with the selected BMR; BMDL = 95% lower
confidence limit on the BMD; BMR = benchmark response; SD = standard deviation.
41
/>-Toluic Acid
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09-28-2017
Exponential Model 2, with BMR of 1 Std. Dev. for the BMD and 0.95 Lower Confidence Level for BMD
0
QL
c
ro
0
16 - -r
14
12
10
Exponential
BMDL
09:12 05/15 2017
100 150
dose
Figure C-2. Exponential Model 2 for Number of Pups Born Data for Female Rats Exposed
to /7-Toluic Acid via Gavage during Premating, Mating, Gestation, and Lactation
(Shirota et al., 2008)
Text Output for Figure C-2:
Exponential Model. (Version: 1.9; Date: 01/29/2013)
Input Data File:
C:/Users/JKaiser/Desktop/BMDS24 0/Data/exp_pupsborn_pta_Exp-ModelVariance-BMRlStd-Down.
(d)
Gnuplot Plotting File:
Tue May 16 11:50:26 2017
BMDS Model Run
The form of the response function by Model:
Model 2
Model 3
Model 4
Model 5
Y[dose] = a * exp{sign * b * dose}
Y[dose] = a * exp{sign * (b * dosej^d}
Y[dose] = a * [c-(c-l) * exp{-b * dose}]
Y[dose] = a * [c-(c-l) * exp{-(b * dose)Ad}]
Note: Y[dose] is the median response for exposure
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.
dose;
42
/>-Toluic Acid
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09-28-2017
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 = 5 00
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 17.7989
rho -6.32411
a 11.7294
b 0.00147751
c 0
d 1
Parameter Estimates
Variable
lnalpha
rho
a
b
c
d
Model 2
13.5612
-4 .73947
15.009
0. 00202169
0
1
Table of Stats From Input Data
Dose N Obs Mean Obs Std Dev
0 13 15.2 1.4
25 13 14.1 1.8
78 11 12.5 2.1
260 9 10.2 5.1
Estimated Values of Interest
Dose Est Mean Est Std Scaled Residual
0 15.01 1.436 0.4796
25 14.27 1.619 -0.3771
78 12.82 2.087 -0.5077
260 8.873 4.99 0.7978
Other models for which likelihoods are calculated:
43
/?-Toluic Acid
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09-28-2017
Model A1:
Model A2:
Model A3:
Model R:
Yij
= Mu(i) + e(i j )
Var{e(ij)}
= Sigma^2
Yij
= Mu(i) + e(i j )
Var{e(ij)}
= Sigma(i)^2
Yij
= Mu(i) + e(i j)
Var{e(ij)}
= exp(lalpha + log(mean(i)) * rho)
Yij
= Mu + e(i)
Var{e(ij)}
= Sigma^2
Model
A1
A2
A3
R
2
Likelihoods of Interest
Log (likelihood) DF
-67.21973 5
-55.74506 8
-55.96952 6
-76.12408 2
-56.52125 4
AIC
144.4395
127.4901
123.939
156.2482
121.0425
Additive constant for all log-likelihoods = -42.27. 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
Are Variances Homogeneous? (A2 vs. Al)
Are variances adeguately modeled? (A2 vs. A3)
Does Model 2 fit the data? (A3 vs. 2)
R)
Test
Test 1
Test 2
Test 3
Test 4
Tests of Interest
-2*log(Likelihood Ratio)
40.76
22.95
0.4489
1.103
D. F.
6
3
2
2
p-value
< 0.0001
< 0.0001
0.7989
0.576
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. Model 2 seems
to adeguately describe the data.
Benchmark Dose Computations:
44
/?-Toluic Acid
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FINAL
09-28-2017
Specified Effect = 1.000000
Risk Type = Estimated standard deviations from control
Confidence Level = 0.950000
BMD = 49.7412
BMDL = 29.8647
Decreased Number of Live Pups on LD 0 for Female Rats Exposed to />-Toluic Acid via
Gavage during Premating, Mating, Gestation, and Lactation
The procedure outlined above was applied to the data for decreased number of live pups
on Lactation Day (LD) 0 in the R/D toxicity study in rats (Shirota et al.. 2008) (see Table 7).
Table C-3 summarizes the BMD modeling results. The constant variance model did not provide
adequate fit to the variance data, but the nonconstant variance model did. With the nonconstant
variance model applied, all models (except for the Exponential 5 and Hill models) provided
adequate fit to the data. BMDLs for models providing adequate fit were considered to be
sufficiently close (differed by
-------
FINAL
09-28-2017
Table C-3. Modeling Results for Number of Live Pups on LD 0 Data for Female Rats Exposed to />-Toluic Acid via Gavage during
Premating, Mating, Gestation, and Lactation"
Model
Variance />-Valucb
/j-Valuc for Fitb
Scaled Residual for Dose Group0
AIC
BMDisd
BMDLisd
Exponential (model 2)d e f
0.8357
0.761
-0.6057
126.1103
73.6269
42.7243
Exponential (model 3)'L e
0.8357
0.4722
-0.5284
128.0809
74.0713
42.726
Exponential (model 4)'L e
0.8357
0.761
-0.6057
129.5641
69.7282
33.5638
Exponential (model 5)'L e
0.8357
NA
-0.2643
129.564135
72.7046
35.9164
Hill4 e
0.8357
NA
-0.264
126.34659
72.261
37.6492
Linear4 e
0.8357
0.6762
-0.805
126.34659
84.4452
52.2126
Polynomial (2-degree)4 e
0.8357
0.6762
-0.805
126.34659
84.4452
52.2126
Polynomial (3-degree)4 e
0.8357
0.6762
-0.805
126.34659
84.4453
52.2126
Power4 e
0.8357
0.6762
-0.805
126.34659
84.4452
52.2126
"Shirota et at (2008).
bValues <0.10 fail to meet conventional goodness-of-fit criteria.
°Scaled residuals at doses immediately below and above the BMD; also the largest residual at any dose.
Coefficients restricted to be negative.
Tower restricted to >1.
Selected model.
AIC = Akaike's information criterion; BMD = maximum likelihood estimate of the exposure concentration associated with the selected BMR; BMDL = 95% lower
confidence limit on the BMD; BMR = benchmark response; LD = lactation day; NA = not applicable (BMDL computation failed or the BMD was higher than the
highest dose tested); SD = standard deviation.
46
/>-Toluic Acid
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09-28-2017
Exponential Model 2, with BMR of 1 Std. Dev. for the BMD and 0.95 Lower Confidence Level for BMD
16
Exponential
14
12
10
8
6
BMDL
BMD
0
50
100
150
200
250
dose
10:04 05/15 2017
Figure C-3. Exponential Model 2 for Number of Live Pups on LD 0 Data for Female Rats
Exposed to »-Toluic Acid via Gavage during Premating, Mating, Gestation, and Lactation
(Shirota et al.. 2008)
Text Output for Figure C-3:
Exponential Model. (Version: 1.9; Date: 01/29/2013)
Input Data File: C:/Users/JKaiser/Desktop/BMDS240/Data/exp_live
pupsO_Exp-ModelVariance-BMRlStd-Down.(d)
Gnuplot Plotting File:
Tue May 16 15:59:58 2017
BMDS Model Run
The form of the response function by Model:
Model 2
Model 3
Model 4
Model 5
Y[dose] = a * exp{sign * b * dose}
Y[dose] = a * exp{sign * (b * dose)Ad}
Y[dose] = a * [c-(c-l) * exp{-b * dose}]
Y[dose] = a * [c-(c-l) * exp{-(b * dose)Ad}]
Note: Y[dose] is the median response for exposure
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.
dose;
47
/>-Toluic Acid
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09-28-2017
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 = 5 00
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 16.6717
rho -5.89548
a 11.4991
b 0.00141022
c 0
d 1
Parameter Estimates
Variable Model 2
lnalpha 14.78 65
rho -5.19603
a 14.3854
b 0.00159531
c 0
d 1
Table of Stats From Input Data
Dose N Obs Mean Obs Std Dev
0 13 14.3 1.7
25 13 14.1 1.8
78 11 12.3 2.2
260 9 10 5
Estimated Values of Interest
Dose Est Mean Est Std Scaled Residual
0 14.39 1.594 -0.1931
25 13.82 1.768 0.5649
78 12.7 2.203 -0.6057
260 9.501 4.683 0.3194
Other models for which likelihoods are calculated:
48
/?-Toluic Acid
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09-28-2017
Model A1:
Model A2:
Model A3:
Model R:
Yij
= Mu(i) + e(i j )
Var{e(ij)}
= Sigma^2
Yij
= Mu(i) + e(i j )
Var{e(ij)}
= Sigma(i)^2
Yij
= Mu(i) + e(i j)
Var{e(ij)}
= exp(lalpha + log(mean(i)) * rho)
Yij
= Mu + e(i)
Var{e(ij)}
= Sigma^2
Likelihoods of Interest
Model Log(likelihood) DF AIC
A1 -67.75308 5 145.5062
A2 -58.60258 8 133.2052
A3 -58.78207 6 129.5641
R -75.23743 2 154.4749
2 -59.05514 4 126.1103
Additive constant for all log-likelihoods = -42.27. 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. Al)
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)
33.27
18 .3
0.359
0.5461
D. F.
6
3
2
2
p-value
< 0.0001
0.0003812
0.8357
0.761
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. Model 2 seems
to adeguately describe the data.
Benchmark Dose Computations:
Specified Effect = 1.000000
49
/?-Toluic Acid
-------
FINAL
09-28-2017
Risk Type = Estimated standard deviations from control
Confidence Level = 0.950000
BMD = 73.62 69
BMDL = 42.7243
Decreased Number of Live Pups on LD 4 for Female Rats Exposed to />-Toluic Acid via
Gavage during Premating, Mating, Gestation, and Lactation
The procedure outlined above was applied to the data for decreased number of live pups
on LD 4 in the R/D toxicity study in rats (Shirota et aL 2008) (see Table 7). Table C-4
summarizes the BMD modeling results. The constant variance model did not provide adequate
fit to the variance data, but the nonconstant variance model did. With the nonconstant variance
model applied, all models (except for the Exponential 5 and Hill models) provided adequate fit to
the data. BMDLs for models providing adequate fit were considered to be sufficiently close
(differed by
-------
FINAL
09-28-2017
Table C-4. Modeling Results for Number of Live Pups on LD 4 Data for Female Rats Exposed to />-Toluic Acid via Gavage during
Premating, Mating, Gestation, and Lactation"
Model
Variance />-Valucb
/7-Value for Fitb
Scaled Residual for Dose Group0
AIC
BMDisd
BMDLisd
Exponential (model 2)d'e'f
0.8688
0.9155
-0.4143
126.717
69.4258
40.5548
Exponential (model 3)'L e
0.8688
0.679
-0.4278
128.7098
70.349
40.5614
Exponential (model 4)'L e
0.8688
0.9155
-0.3823
128.7064
67.8377
32.5953
Exponential (model 5)'L e
0.8688
NA
-0.2314
130.5352
70.0084
33.3092
Hill4 e
0.8688
NA
-0.231
130.535192
69.7588
NA
Linear4 e
0.8688
0.8341
-0.618
126.898088
79.9491
49.9065
Polynomial (2-degree)4 e
0.8688
0.8341
-0.618
126.898088
79.9491
49.9065
Polynomial (3-degree)4 e
0.8688
0.8341
-0.618
126.898088
79.9491
49.9065
Power4 e
0.8688
0.8341
-0.618
126.898088
79.9491
49.9065
aSfairota et al. (2008).
bValues <0.10 fail to meet conventional goodness-of-fit criteria.
°Scaled residuals at doses immediately below and above the BMD; also the largest residual at any dose.
Coefficients restricted to be negative.
Tower restricted to >1.
Selected model.
AIC = Akaike's information criterion; BMD = maximum likelihood estimate of the exposure concentration associated with the selected BMR; BMDL = 95% lower
confidence limit on the BMD; BMR = benchmark response; LD = lactation day; NA = not applicable (BMDL computation failed or the BMD was higher than the
highest dose tested); SD = standard deviation.
51
/>-Toluic Acid
-------
FINAL
09-28-2017
Exponential Model 2, with BMR of 1 Std. Dev. for the BMD and 0.95 Lower Confidence Level for BMD
16
Exponential
14
12
10
8
6
BMDL
BMD
0
50
100
150
200
250
dose
10:10 05/15 2017
Figure C-4. Exponential Model 2 for Number of Live Pups on LD 4 Data for Female Rats
Exposed to »-Toluic Acid via Gavage during Premating, Mating, Gestation, and Lactation
(Shirota et al.. 2008)
Text Output for Figure C-4:
Exponential Model. (Version: 1.9; Date: 01/29/2013)
Input Data File: C:/Users/JKaiser/Desktop/BMDS240/Data/exp_live
pups4_Exp-ModelVariance-BMRlStd-Down.(d)
Gnuplot Plotting File:
Wed May 17 08:21:52 2017
BMDS Model Run
The form of the response function by Model:
Model 2
Model 3
Model 4
Model 5
Y[dose] = a * exp{sign * b * dose}
Y[dose] = a * exp{sign * (b * dose)Ad}
Y[dose] = a * [c-(c-l) * exp{-b * dose}]
Y[dose] = a * [c-(c-l) * exp{-(b * dose)Ad}]
Note: Y[dose] is the median response for exposure
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.
dose;
52
/>-Toluic Acid
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FINAL
09-28-2017
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 = 5 00
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 16.6143
rho -5.88729
a 11.2992
b 0.00150862
c 0
d 1
Parameter Estimates
Variable Model 2
lnalpha 14.8352
rho -5.23018
a 14.3345
b 0.00167692
c 0
d 1
Table of Stats From Input Data
Dose N Obs Mean Obs Std Dev
0 13 14.3 1.7
25 13 13.9 1.8
78 11 12.3 2.2
260 9 9.7 5.3
Estimated Values of Interest
Dose Est Mean Est Std Scaled Residual
0 14.33 1.575 -0.07906
25 13.75 1.758 0.3158
78 12.58 2.218 -0.4143
260 9.269 4.927 0.2625
Other models for which likelihoods are calculated:
53
/?-Toluic Acid
-------
FINAL
09-28-2017
Model A1:
Model A2:
Model A3:
Model R:
Yij
= Mu(i) + e(i j )
Var{e(ij)}
= Sigma^2
Yij
= Mu(i) + e(i j )
Var{e(ij)}
= Sigma(i)^2
Yij
= Mu(i) + e(i j)
Var{e(ij)}
= exp(lalpha + log(mean(i)) * rho)
Yij
= Mu + e(i)
Var{e(ij)}
= Sigma^2
Likelihoods of Interest
Model Log(likelihood) DF AIC
A1 -69.4545 5 148.909
A2 -59.127 8 134.254
A3 -59.2676 6 130.5352
R -76.98125 2 157.9625
2 -59.35583 4 126.7117
Additive constant for all log-likelihoods = -42.27. 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. Al)
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)
35.71
20. 65
0.2812
0.1765
D. F.
6
3
2
2
p-value
< 0.0001
0.0001242
0.8688
0.9155
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. Model 2 seems
to adeguately describe the data.
Benchmark Dose Computations:
Specified Effect = 1.000000
54
/?-Toluic Acid
-------
FINAL
09-28-2017
Risk Type = Estimated standard deviations from control
Confidence Level = 0.950000
BMD = 69.4258
BMDL = 40.5548
Decreased Fertility Index in Female Rats Exposed to />-Toluic Acid via Gavage during
Premating, Mating, Gestation, and Lactation
The procedure outlined above was applied to the data for decreased fertility index
(number of nonpregnant females/copulated pairs) in the R/D toxicity study in rats (Shi rota et aL
2008) (see Table 7). Table C-5 summarizes the BMD dichotomous modeling results. All
models provided adequate fit to the data. BMDLs for models providing adequate fit were
considered to be sufficiently close (differed by
-------
FINAL
09-28-2017
Table C-5. Modeling Results for Fertility Index in Female Rats Exposed to />-Toluic Acid during Premating, Mating, and Gestation11
Model
/>-Valueb
Scaled Residuals0; Dose
Scaled Residuals'1; Control
AIC
BMDio
BMDLio
Gamma
0.8833
0.334
0
27.2979
109.371
46.9343
Logistic
0.5674
0.842
-0.416
28.2967
164.134
111.606
LogLogistic
0.8882
0.311
0
27.2938
107.708
41.5267
LogProbit®
0.9563
0.473
0
25.2593
109.22
67.7922
Multistage
0.8464
0.384
0
27.4279
116.131
46.1995
Probit
0.6104
0.792
-0.366
28.1131
152.334
102.293
Weibull
0.8766
0.334
0
27.33
110.677
46.7493
aShirota et al. (2008).
bValues <0.10 fail to meet conventional goodness-of-fit criteria.
°Scaled residuals at doses immediately below and above the BMD; also the largest residual at any dose.
dScaled residuals for control.
"Selected model.
AIC = Akaike's information criterion; BMD = maximum likelihood estimate of the exposure concentration associated with the selected BMR; BMDL = 95% lower
confidence limit on the BMD; BMR = benchmark response.
56
/>-Toluic Acid
-------
FINAL
09-28-2017
LogProbit Model, with BMR of 10% Extra Risk for the BMD and 0.95 Lower Confidence Limit for the BMDL
LogProbit
0.6
0.5
0.4
o
<
§ 0.3
o
ra
0.2
BMDL
BMD
0
50
100
150
200
250
dose
10:08 08/08 2017
Figure C-5. LogProbit Model for Decreased Fertility Index in Female Rats Exposed to
/j-Toluic Acid via Gavage during Premating, Mating, Gestation, and Lactation
(Shirota et al., 2008)
Text Output for Figure C-5:
Probit Model. (Version: 3.3; Date: 2/28/2013)
Input Data File:
C:/Users/JREID/Desktop/BMDS2601/lnp_PREGNANT_Lnp-BMR10-Restrict.(d)
Gnuplot Plotting File:
C:/Users/JREID/Desktop/BMDS2601/lnp_PREGNANT_Lnp-BMR10-Restrict.pit
Tue Aug 08 10:08:52 2017
BMDS Model Run
The form of the probability function is:
P[response] = Background
+ (1-Background) * CumNorm(Intercept+Slope*Log(Dose)) ,
where CumNormf .) is the cumulative normal distribution function
Dependent variable = Effect
57 />-Toluic Acid
-------
FINAL
09-28-2017
Independent variable = Dose
Slope parameter is restricted as slope >= 1
Total number of observations = 4
Total number of records with missing values = 0
Maximum number of iterations = 5 00
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
intercept = -5.821
slope = 1
Asymptotic Correlation Matrix of Parameter Estimates
( *** The model parameter(s) -background -slope
have been estimated at a boundary point, or have been specified by
the user,
and do not appear in the correlation matrix )
intercept
intercept 1
Parameter Estimates
Interval
Variable
Limit
background
intercept
0.300852
slope
Estimate
0
-5.97491
-6.56457
1
Std. Err.
NA
-5.38525
NA
NA - Indicates that this parameter has hit a bound
implied by some ineguality constraint and thus
has no standard error.
95.0% Wald Confidence
Lower Conf. Limit Upper Conf.
Analysis of Deviance Table
Model
Full model
Fitted model
Reduced model
Log(likelihood)
-11.4662
-11.6296
-16.3584
# Param's
4
1
1
Deviance Test d.f.
0.326916
9.78448
P-value
0.9549
0. 02049
AIC:
25.2593
Goodness of Fit
Scaled
Dose Est._Prob. Expected Observed Size Residual
58
/?-Toluic Acid
-------
FINAL
09-28-2017
0.0000 0.0000 0.000 0.000 13.000 0.000
25.0000 0.0029 0.038 0.000 13.000 -0.195
78.0000 0.0528 0.634 1.000 12.000 0.473
260.0000 0.3394 4.412 4.000 13.000 -0.241
Chi^2 = 0.32 d.f. = 3 P-value = 0.9563
Benchmark Dose Computation
Specified effect = 0.1
Risk Type = Extra risk
Confidence level = 0.95
BMD = 109.22
BMDL = 67.7922
Decreased Fertility Index in Male Rats Exposed to />-Toluic Acid via Gavage during
Premating, Mating, Gestation, and Lactation
The procedure outlined above was applied to the data for decreased fertility index
(number of nonpregnant females/copulated pairs) in the R/D toxicity study in rats (Shi rota et aL
2008) (see Table 7). Table C-6 summarizes the BMD dichotomous modeling results. All
models provided adequate fit to the data. BMDLs for models providing adequate fit were
considered to be sufficiently close (differed by
-------
FINAL
09-28-2017
Table C-6. Modeling Results for Fertility Index in Male Rats Exposed to />-Toluic Acid during Premating, Mating, and Gestation"
Model
/>-Valueb
Scaled Residuals; Dosec
Scaled Residuals; Control0
AIC
BMD io
BMDLio
Gamma
0.8778
0.344
0
27.315
105.607
45.3595
Logistic
0.5656
0.845
-0.415
28.3033
157.895
107.397
LogLogistic
0.8827
0.321
0
27.3112
104.03
40.2255
LogProbitd
0.9552
0.475
0
25.2687
105.145
65.3087
Multistage
0.8406
0.395
0
27.448
112.2
44.6475
Probit
0.6083
0.795
-0.365
28.1207
146.558
98.4465
Weibull
0.871
0.344
0
27.3477
106.895
45.1768
aShirota et al. (2008).
bValues <0.10 fail to meet conventional goodness-of-fit criteria.
°Scaled residuals at doses immediately below and above the BMD; also for control.
dSelected model.
AIC = Akaike's information criterion; BMD = maximum likelihood estimate of the exposure concentration associated with the selected BMR; BMDL = 95% lower
confidence limit on the BMD; BMR = benchmark response.
60
/>-Toluic Acid
-------
FINAL
09-28-2017
LogProbit Model, with BMR of 10% Extra Risk for the BMD and 0.95 Lower Confidence Limit for the BMDL
3=
<
0.6
0.5
0.4
0.3
0.2
0.1
LogProbit
BMDL
BMD
50
100
150
200
250
dose
12:58 08/08 2017
Figure C-6. LogProbit Model for Decreased Fertility Index in Male Rats Exposed to
/j-Toluic Acid via Gavage during Premating, Mating, Gestation, and Lactation
(Shirota et al., 2008)
Text Output for Figure C-6:
Probit Model. (Version: 3.3; Date: 2/28/2013)
Input Data File: C:/Users/JREID/Desktop/BMDS2601/lnp_Male
fertility_Lnp-BMR10-Restrict.(d)
Gnuplot Plotting File: C:/Users/JREID/Desktop/BMDS2601/lnp_Male
fertility_Lnp-BMR10-Restrict.pit
Tue Aug 08 12:58:32 2017
BMDS Model Run
The form of the probability function is:
P[response] = Background
+ (1-Background) * CumNorm(Intercept+Slope*Log(Dose)) ,
where CumNormf .) is the cumulative normal distribution function
Dependent variable = Effect
61
/>-Toluic Acid
-------
FINAL
09-28-2017
Independent variable = Dose
Slope parameter is restricted as slope >= 1
Total number of observations = 4
Total number of records with missing values = 0
Maximum number of iterations = 5 00
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
intercept = -5.78433
slope = 1
Asymptotic Correlation Matrix of Parameter Estimates
( *** The model parameter(s) -background -slope
have been estimated at a boundary point, or have been specified by
the user,
and do not appear in the correlation matrix )
intercept
intercept 1
Parameter Estimates
Interval
Variable
Limit
background
intercept
0.300506
slope
Estimate
0
-5.93689
-6.52587
1
Std. Err.
NA
-5.34791
NA
NA - Indicates that this parameter has hit a bound
implied by some ineguality constraint and thus
has no standard error.
95.0% Wald Confidence
Lower Conf. Limit Upper Conf.
Analysis of Deviance Table
Model
Full model
Fitted model
Reduced model
Log(likelihood)
-11.4662
-11.6345
-16.3584
# Param's Deviance Test d.f. P-value
4
1 0.336559 3 0.953
1 9.78448 3 0.02049
AIC:
25.2689
Goodness of Fit
Scaled
Dose Est._Prob. Expected Observed Size Residual
62
/?-Toluic Acid
-------
FINAL
09-28-2017
0.0000 0.0000 0.000 0.000 13.000 0.000
25.0000 0.0033 0.043 0.000 13.000 -0.207
75.0000 0.0527 0.632 1.000 12.000 0.475
250.0000 0.3389 4.406 4.000 13.000 -0.238
Chi^2 =0.33 d.f. = 3 P-value = 0.9552
Benchmark Dose Computation
Specified effect = 0.1
Risk Type = Extra risk
Confidence level = 0.95
BMD = 105.145
BMDL = 65.3087
Decreased Absolute Epididymis Weight in Male Rats Exposed to /J-Toluic Acid via Gavage
during Premating, Mating, Gestation, and Lactation
The procedure outlined above was applied to the data for decreased absolute epididymal
weights in male rats in Shirota et al. (2008) (see Table 7). Table C-7 summarizes the BMD
modeling results. The constant variance model provided adequate fit to the variance data. All
models except the Exponential 5 and Hill models provided adequate fit to the data. BMDLs for
models providing adequate fit were considered to be sufficiently close (differed by
-------
FINAL
09-28-2017
Table C-7. Modeling Results for Decreased Absolute Epididymis Weight in Male Rats Exposed to /J-Toluic Acid via Gavage during
Premating, Mating, Gestation, and Lactation"
Model
Variance /?-Valueb
/7-Value for Fitb
Scaled Residual for Dose Group0
AIC
BMDisd
BMDLisd
Exponential (model 2)'L e
0.8461
0.9604
0.1715
-208.3524
122.396
89.77
Exponential (model 3)'L e
0.8461
0.9522
-0.02663
-206.4297
135.354
90.121
Exponential (model 4)'L e
0.8461
0.9604
0.1715
-208.3524
122.396
60.493
Exponential (model 5)'L e
0.8461
NA
1.11 x 10-6
-204.4333
131.034
61.182
Hill4 e
0.8461
NA
-1.80 x 10-7
-204.43333
131.39
60.546
Lineard'e'f
0.8461
0.977
0.111
-208.38682
126.584
94.617
Polynomial (2-degree)4 e
0.8461
0.9145
-0.037
-206.42179
137.436
94.772
Polynomial (3-degree)4 e
0.8461
0.9145
-0.037
-206.42179
137.436
94.772
Power4 e
0.8461
0.9415
-0.0332
-206.42795
136.291
94.8
aSfairota et al. (2008).
bValues <0.10 fail to meet conventional goodness-of-fit criteria.
°Scaled residuals at doses immediately below and above the BMD; also the largest residual at any dose.
Coefficients restricted to be negative.
Tower restricted to >1.
Selected model.
AIC = Akaike's information criterion; BMD = maximum likelihood estimate of the exposure concentration associated with the selected BMR; BMDL = 95% lower
confidence limit on the BMD; BMR = benchmark response; LD = lactation day; NA = not applicable (BMDL computation failed or the BMD was higher than the
highest dose tested); SD = standard deviation.
64
/>-Toluic Acid
-------
FINAL
09-28-2017
Linear Model, with BMR of 1 Std. Dev. for the BMD and 0.95 Lower Confidence Limit for the BMDL
1.35
Linear
1.25
Q.
BMDL
BMD
1.05
0
50
100
150
200
250
dose
15:23 09/21 2017
Figure C-7. Linear Model for Decreased Absolute Epididymis Weight for Male Rats
Exposed to »-Toluic Acid via Gavage during Premating, Mating, Gestation, and Lactation
(Shirota et al.. 2008)
Text Output for Figure C-7:
Polynomial Model. (Version: 2.20; Date: 10/22/2014)
Input Data File: C:/Users/JREID/Desktop/BMDS2601/lin_epdid
abs_Lin-ConstantVariance-BMRlStd.(d)
Gnuplot Plotting File: C:/Users/JREID/Desktop/BMDS2601/lin_epdid
abs_Lin-ConstantVariance-BMRlStd.pit
Thu Sep 21 15:23:28 2017
BMDS Model Run
The form of the response function is:
Y[dose] = beta_0 + beta_l*dose + beta_2*dose/s2 + ...
Dependent variable = Mean
Independent variable = Dose
rho is set to 0
65
/>-Toluic Acid
-------
FINAL
09-28-2017
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 = 5 00
Relative Function Convergence has been set to: le-008
Parameter Convergence has been set to: le-008
Default Initial Parameter Values
alpha = 0.00645
rho = 0 Specified
beta_0 = 1.28336
beta 1 = -0.000609836
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_l
alpha 1 6.8e-009 2.1e-010
beta_0 6.8e-009 1 -0.67
beta 1 2.le-010 -0.67 1
Parameter Estimates
Interval
Variable
Limit
alpha
0.00824976
beta_0
1.31154
beta_l
0.000109652
Estimate
0.00595917
1.28336
-0.000609836
-0.00082475
Std. Err.
0. 00116869
0.0143755
-0.000394922
95.0% Wald Confidence
Lower Conf. Limit Upper Conf.
0.00366858
1.25519
Table of Data and Estimated Values of Interest
Dose
Obs Mean
Est Mean Obs Std Dev Est Std Dev Scaled Res.
0
25
75
250
13
13
13
13
1.28
1.27
1.24
1.13
1.28
1.27
1.24
1.13
0.08
0.08
0.07
0.09
0.0772
0.0772
0.0772
0.0772
-0.157
0.0881
0. Ill
-0.0421
Model Descriptions for likelihoods calculated
66
/?-Toluic Acid
-------
FINAL
09-28-2017
Model A1: Yij = Mu(i) + e(ij)
Var{e(ij)} = SigmaA2
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)
107.216664
107.623729
107.216664
107.193408
95.057526
# Param's
5
8
5
3
2
AIC
-204.433329
-199.247457
-204.433329
-208.386817
-186.115053
Explanation of Tests
Test 1:
Test
Test
Test
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.)
Tests of Interest
Test -2*log(Likelihood Ratio) Test df p-value
Test 1 25.1324 6 0.0003227
Test 2 0.814129 3 0.8461
Test 3 0.814129 3 0.8461
Test 4 0.046512 2 0.977
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
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Confidence level
0.95
BMD
126.584
BMDL
94.6168
Decreased Relative Epididymis Weight in Male Rats Exposed to /J-Toluic Acid via Gavage
during Premating, Mating, Gestation, and Lactation
The procedure outlined above was applied to the data for decreased absolute epididymal
weights in male rats in Shirota et al. (2008) (see Table 7). Table C-8 summarizes the BMD
modeling results. Neither constant variance or nonconstant variance models provided adequate
fit to the variance data. Therefore, the decreased relative epididymal data in male rats could not
be modeled.
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Table C-8 Modeling Results for Decreased Relative Epididymis Weight in Male Rats Exposed to />-Toluic Acid via Gavage during
Premating, Mating, Gestation, and Lactation"
Model
Variance />-Valucb
/7-Value for Fitb
Scaled Residual for Dose Group0
AIC
BMDisd
BMDLisd
Exponential (model 2)'L e
0.003362
0.4022
-0.002952
-345.2806
202.695
132.478
Exponential (model 3)'L e
0.003362
0.4022
-0.002953
-345.2806
202.695
132.478
Exponential (model 4)'L e
0.003362
0.3279
1.064
-344.145
149.468
53.5089
Exponential (model 5)'L e
0.003362
0.3279
1.064
-344.145
149.468
53.5089
Hill4 e
0.003362
0.367
1.16
-344.28841
149.705
42.7573
Linear4 e
0.003362
0.3868
-0.00128
-345.20218
205.854
138.049
Polynomial (2-degree)4 e
0.003362
0.3868
-0.00128
-345.20218
205.854
138.049
Polynomial (3-degree)4 e
0.003362
0.3868
-0.00128
-345.20218
205.854
138.049
Power4 e
0.003362
0.3868
-0.00128
-345.20218
205.854
138.049
aSfairota et al. (2008).
bValues <0.10 fail to meet conventional goodness-of-fit criteria.
°Scaled residuals at doses immediately below and above the BMD; also the largest residual at any dose.
Coefficients restricted to be negative.
Tower restricted to >1.
AIC = Akaike's information criterion; BMD = maximum likelihood estimate of the exposure concentration associated with the selected BMR; BMDL = 95% lower
confidence limit on the BMD; BMR = benchmark response; LD = lactation day; NA = not applicable (BMDL computation failed or the BMD was higher than the
highest dose tested); SD = standard deviation.
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