Superfund Chemical Data Matrix (SCDM) Methodology


SUPERFUND CHEMICAL DATA MATRIX (SCDM)
METHODOLOGY

Prepared for:

U.S. Environmental Protection Agency
Office of Superfund Remediation and Technology Innovation
1200 Pennsylvania Avenue, NW (5204P)
Washington, DC 20460

June 20, 2014

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TABLE OF CONTENTS

LIST OF FIGURES	iv

LIST OF TABLES	iv

ACRONYMS and ABBREVIATIONS	v

1.0 INTRODUCTION	1

2.0 DATA SELECTION METHODOLOGY	2

2.1	General Protocols for SCDM Data Collection	2

2.1.1	Generic Values	2

2.1.2	Use of Compound Classes to Assign Values for Individual Substances	3

2.1.3	Substitution Classes	4

2.1.4	Substances with Unique Value Selection	4

2.2	Data Used to Determine Human Toxicity Factor Values and Screening Concentration
Benchmarks	4

2.2.1	SF, IUR, RfD and RfC Data Collection	5

2.2.2	Weight of Evidence (WOE)	6

2.2.3	LD50 - Oral, Dermal; LC50- Inhalation	6

2.2.4	EDI0 and Weight-of-Evidence - Oral, Inhalation	7

2.3	Mobility Information	7

2.3.1	Vapor Pressure	7

2.3.2	Henry's Law Constant	8

2.3.3	Water Solubility	9

2.3.4	Soil/Water Distribution Coefficient (Kd); Soil Organic/Carbon Partition

Coefficients (Koc and Log Kow)	10

2.4	Persistence Information	12

2.4.1	Hydrolysis, Bi ode gradation and Photolysis Half-Lives	12

2.4.2	Volatilization Half-Lives	12

2.4.3	Radioactive Half-Lives	12

2.5	Bioaccumulation Potential Information	12

2.5.1	Bioconcentration	13

2.5.2	Octanol/Water Partition Coefficient (Log Kow)	14

2.5.3	Water Solubility	14

2.6	Ecotoxicity Parameters	14

2.6.1	Acute and Chronic Freshwater and Saltwater Criteria - CCC, CMC	14

2.6.2	LC50 - Freshwater, Saltwater	15

2.7	Regulatory Benchmarks	15

2.7.1	National Ambient Air Quality Standards (NAAQS)	15

2.7.2	National Emissions Standards for Hazardous Air Pollutants (NESHAPs)	15

2.7.3	Maximum Contaminant Levels (MCLs) and Maximum Contaminant Level

Goals (MCLGs)	16

2.7.4	FDA Action Levels (FDAALs)	16

2.7.5	Ecological Based Benchmarks	16

2.7.6	Uranium Mill Tailings Radiation Control Act Standards (UMTRCA)	16

2.8	Physical Properties	16

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2.8.1	Chemical Formula, Boiling Point and Melting Point	17

2.8.2	Molecular Weight	18

2.8.3	Density	18

3.0 CALCULATION OF INTERIM VALUES	20

3.1	RfC to RfDinhal	20

3.2	IUR to Inhalation Slope Factor	20

3.3	Using ED10 to estimate a Slope Factor for either oral or inhalation pathways	21

3.4	Volatilization Half-Life	21

3.4.1	Volatilization Half-Life for Rivers, Oceans, Coastal Tidal Waters and the

Great Lakes	23

3.4.2	Volatilization Half-Life for Lakes	23

3.5	Overall Half-Lives	23

3.5.1 Overall Half-Lives for Non-radionuclides	23

3.5.1 Overall Half-Lives for Radionuclides	24

3.6	Soil Water Distribution Coefficient (Kj); Soil Organic/Carbon Partition Coefficients
(Koc)	24

3.7	Water solubility for metals	25

4.0 SCREENING CONCENTRATION BENCHMARKS	26

4.1	Screening Concentration Benchmarks for the Air Migration Pathway	26

4.1.1	Non-carcinogenic - Air, Inhalation	26

4.1.2	Carcinogenic - Air, Inhalation	26

4.1.3	Carcinogenic - Air, Inhalation - Asbestos	27

4.1.4	Carcinogenic through a Mutagenic Mode of Action - Air, Inhalation	27

4.1.5	Carcinogenic - Air, Inhalation, Radionuclides	30

4.2	Screening Concentration Benchmarks for the Soil Exposure Pathway	30

4.2.1	Non-carcinogenic - Soil, Ingestion	30

4.2.2	Carcinogenic - Soil, Ingestion	31

4.2.3	Carcinogenic through a Mutagenic Mode of Action - Soil, Ingestion	31

4.2.4	Carcinogenic - Soil, Radionuclides	35

4.3	Screening Concentration Benchmarks for the Ground Water and Drinking Water
Pathways	36

4.3.1	Non-carcinogenic - Ground Water and Drinking Water, Ingestion	36

4.3.2	Carcinogenic - Ground Water and Drinking Water, Ingestion	37

4.3.3	Carcinogenic through a Mutagenic Mode of Action - Ground Water and

Drinking Water, Ingestion	37

4.3.4	Carcinogenic - Ground Water and Drinking Water, Radionuclides	40

4.4	Screening Concentration Benchmarks for the Human Food Chain Pathway	41

4.4.1	Non-carcinogenic - Human Food Chain, Fish Ingestion	41

4.4.2	Carcinogenic - Human Food Chain, Fish Ingestion	41

4.4.3	Carcinogenic - Human Food Chain, Fish Ingestion, Radionuclides	42

5.0 SCDM DATA REPORTING and APPENDICES	43

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APPENDICES

Appendix A
Appendix B-I
Appendix B-II
Appendix C

Chemical Data, Factor Values, and Benchmarks
Hazardous Substances Factor Values

Hazardous Substances Screening Concentration Benchmarks
Synonyms List

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LIST OF FIGURES

Figure 1. Page Heading	43

Figure 2. Toxicity Section	44

Figure 3. Persistence Section	45

Figure 4. Physical Characteristics Section	45

Figure 5. Mobility Section	46

Figure 6. Bioaccumulation Section	46

Figure 7. Other Data	46

Figure 8. Class Information Sections	47

Figure 9. Assigned Factor Values Section	48

Figure 10. Benchmarks Section	49

LIST OF TABLES

Table 1. Examples of Human Food Chain Aquatic Organisms	13

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ACRONYMS and ABBREVIATIONS

AALAC	Ambient Aquatic Life Advisory Concentrations

ACGIH	American Conference of Governmental Industrial Hygienists

ATSDR	Agency for Toxic Substances and Disease Registry

AWQC	Ambient Water Quality Criteria

BCF	Bioconcentration Factor

CAS RN	Chemical Abstracts Survey Registration Number

CCC	Criteria Continuous Concentration

CERCLA	Comprehensive Environmental Response, Compensation, and Liability Act

CFR	Code of Federal Regulations

CMC	Criteria Maximum Concentration

ED	Effective Dose

EPA	United States Environmental Protection Agency

EPI	Estimation Programs Interface

FDAAL	Food and Drug Administration Action Levels

fs	Sorbent Content (fraction of clays plus organic carbon)

HEAST	Health Effects Assessment Summary Tables

HEDR	Handbook of Environmental Degradation Rates

HLC	Henry's Law Constant

HRS	Hazard Ranking System

HTF	Human Toxicity Factor

ICRP	International Commission on Radiological Protection

Int	Intermediate

IRIS	Integrated Risk Information System

IUR	Inhalation Unit Risk

Kd	Soil/Water Distribution Coefficient

Koc	Soil Organic/Carbon Partition Coefficient

LC	Lethal Concentration

LD	Lethal Dose

Log Kow	Logarithm of the n-Octanol-Water Partition Coefficient

MCI	Molecular Connectivity Index

MCLs	Maximum Contaminant Levels

MCLGs	Maximum Contaminant Level Goals

MRL	Minimal Risk Level

MW	Molecular Weight

NAAQS	National Ambient Air Quality Standards

NESHAPs	National Emission Standards for Hazardous Air Pollutants

NHL	Non-Hodgkin's Lymphoma

NIOSH	National Institute for Occupational Safety and Health

NJDEP	New Jersey Department of Environmental Protection

NPL	National Priorities List

OEHHA	California Environmental Protection Agency Office of Environmental Health Hazard
Assessment

OSRTI	Office of Superfund Remediation and Technology Innovation

PAH	Polyaromatic Hydrocarbons

PCB	Polychlorinated Biphenyls

PPRTV	Provisional Peer Reviewed Toxicity Values

PRG	Preliminary Remediation Goals

RBA	Relative Bioavailability Adjustment

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REL

Reference Exposure Level

RfC

Reference Concentration

RfD

Reference Dose

RME

Reasonable Maximum Exposure

RTECS

Registry of Toxic Effects of Chemical Substances

RTI

Research Triangle Institute

SC

Screening Concentration

SCDM

Superfund Chemical Data Matrix

SF

Slope Factor (Cancer)

SPHEM

Superfund Public Health Evaluation Manual

SRC

Syracuse Research Corporation

STSC

Superfund Health Risk Technical Support Center

TCDD

2,3,7,8 -T etrachlorodibenzo-p -dioxin

TCE

trichloroethylene

TEF

Toxicity Equivalence Factor

UMTRCA

Uranium Mill Tailings Radiation Control Act

WOE

Weight-of-Evidence

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SUPERFUND CHEMICAL DATA MATRIX (SCDM)

METHODOLOGY

[June 2014]

1.0 INTRODUCTION

The Superfund Chemical Data Matrix (SCDM) contains factor values and screening concentration
benchmarks that can be used when applying the Hazard Ranking System (HRS; 40 CFR Part 300
Appendix A, 55 FR 51583) to evaluate potential National Priorities List (NPL) sites. The HRS assigns
factor values for toxicity, gas migration potential, gas and ground water mobility, surface water
persistence, and bioaccumulation potential. These assignments are based on the physical, chemical,
ecological, toxicological, and radiological properties of hazardous substances present at a site. Hazardous
substances, as defined for HRS purposes, include both hazardous substances referenced in the
Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) section 101(14),
which are substances specifically listed under other federal laws and are known as "CERCLA hazardous
substances," and "pollutants or contaminants" as defined in CERCLA itself in section 101(33).

SCDM contains HRS factor values and benchmarks for those hazardous substances frequently found at
sites that are evaluated using the HRS. SCDM also contains the physical, chemical, toxicological, and
radiological input data used to calculate the factors and benchmarks. The input data presented in SCDM
are taken directly from peer reviewed, generally accepted literature sources and databases and/or U.S.
Environmental Protection Agency (EPA) developed literature sources and databases; or are calculated
using procedures set forth by the EPA and in the HRS. Further HRS procedures are then applied to the
input data to determine factor values and benchmarks, which include both risk-based screening
concentrations and concentrations specified in regulatory limits for the hazardous substances.

This document explains the procedures used to provide chemical and physical properties, factor values
and screening concentration benchmarks for substances listed in SCDM. The factor values and
benchmarks supersede any previous values provided by SCDM, beginning January 2014. These new
values and benchmarks reflect the EPA's methodology for determining risk, as described in the EPA's
Risk Assessment Guidance for Superfund (RAGS) Volume 1: Human Health Evaluation Manual, Part F:
Supplemental Guidance for Inhalation Risk Assessment and Part B: Development of Risk-based
Preliminary Remediation Goals (EPA-540-R-070-002/OSWER 9285.7-82) and Soil Screening Guidance:
Technical Background Document (EPA/540/R95/128).

Section 2.0 (Data Selection Methodology) of this document explains how data are selected and prioritized
for use in assigning SCDM values. Section 3.0 (Calculation of Interim Values) describes how some
values (e.g., half-lives, distribution coefficients, slope factors and water solubility for metals) are
calculated using data and methodologies from published literature or regulatory guidance documents.
Section 4.0 (Screening Concentration Benchmarks) describes how screening concentration benchmarks
are calculated for air, water, soil and human food chain exposures. Section 5.0 (SCDM Data Reporting
and Appendices) describes how SCDM data, HRS factor values, and screening concentration benchmarks
are presented in the SCDM Appendices.

Data inputs, factor values and benchmarks are listed, by substance, in SCDM Appendix A. Appendices BI
and BII contain tables presenting HRS factor values and benchmarks, organized by pathway. Appendix C
contains a cross-reference index of substance name synonyms.

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2.0 DATA SELECTION METHODOLOGY

This section describes the methodology used for collecting and selecting data to determine factor values and
screening concentration benchmarks for the substances listed in SCDM. It also specifies data source reference
hierarchies and how the hierarchies are applied for each data type.

Section 2.1 describes hazardous substance identification protocols and how they relate to special cases. Sections
2.2 through 2.9 specify the references used to obtain data and the methodologies used to extract the data and
assign values. The criteria described in these sections were developed based on the type and quality of data
available in the current SCDM references; they are not intended to apply to all data in general.

2.1	General Protocols for SCDM Data Collection

Compiling data for SCDM requires a determination of which data reasonably apply to each hazardous
substance. In most cases, data are collected for each substance from the specific references identified in Sections

2.2	through 2.8. In some cases, however, data in the references cited are available only for a class or mixture of
hazardous substances and not for the individual substances that are included in the class or that make up the
mixture. In general, if any of these classes or mixtures is present at a hazardous waste site, it is assumed that the
most toxic, most persistent, or most bioaccumulative component of the class or mixture is present. For these
mixtures or classes, SCDM collects and uses those data resulting in the greatest HRS factor values as specified
by the HRS (e.g., lowest Reference Dose [RfD], highest cancer slope factor [SF], longest half-life and greatest
bioaccumulation factor) from the data provided in the references used. In other cases, data that are specific to
individual substances are used or substituted as representative for a class of substances. These special cases are
described in Sections 2.1.1 through 2.1.4 below.

2.1.1 Generic Values

SCDM contains generic values for the following classes of compounds:

•	Chromium (III and VI oxidation states) - SCDM contains values for chromium III, chromium VI, and a
"generic" total chromium value to be used only when the specific oxidation state is not known. SCDM
assigns the oral RfD and reference concentration (RfC) from chromium VI to total chromium.

•	Mercury (elemental and inorganic compounds) - SCDM contains data for elemental and inorganic
species of mercury, and applies the data to a single listing of "mercury." The oral RfD is for mercuric
chloride, and the inhalation RfD is for elemental mercury vapor. The vapor pressure, Henry's Law
Constant and distribution coefficient are for elemental mercury. A geometric mean water solubility is
based on the lowest solubility (mercurous chloride) and highest solubility (mercury perchlorate) found
in the reference sources.

•	Polychlorinated biphenyls (PCBs) - PCBs are represented as a single class of compounds, regardless of
the PCB mixture or mixtures that may be identified at a site. For PCBs, toxicity in SCDM is based on
Arochlor 1254, which results in the most environmentally conservative screening concentration
benchmarks and bioaccumulation/human food chain-based factor values for this group of compounds.
EPA's most recent reference on PCB risk assessment is "EPA's PCB Risk Assessment Review Guidance
Document, Interim Draft," 2000a.

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•	Endosulfans - SCDM contains data for endosulfan mixture and two endosulfan isomers (endosulfan I
and endosulfan II). The RfD and distribution coefficient data are collected for endosulfan and applied to
endosulfan mixture and its isomers. SCDM contains a vapor pressure and Henry's Law constant for
each isomer.

•	Chlordane (alpha and gamma) - SCDM contains some data for the alpha and gamma isomers of
chlordane, but most values represent a mixture of the two. When a reference does not specify whether
chlordane data were derived from a specific isomer or isomer concentration, SCDM uses the generic
values.

2.1.2 Use of Compound Classes to Assign Values for Individual Substances

SCDM assigns substance class data to the substances listed below. If no data can be found in the specified
references for an individual substance, but data are available for the generic class to which the substance
belongs, SCDM assigns the generic value to that substance. These substance classes contain relatively small sets
of isomers, which are likely to occur as mixtures, and are well defined, in that the generic class typically refers
to a mixture of all members of the class (e.g., o-, m-, p-xylenes). Members of these classes are also expected to
have similar chemical behavior.

•	Polychlorinated dibenzo-dioxins and furans - SCDM contains cancer slope factor, inhalation unit risk (IUR)
and RfD values for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). When a slope factor, IUR and/or RfD are
not available for similar dioxins and furans listed in SCDM, SCDM applies toxicity equivalence factors
(TEFs) to determine the values for these substances. Substance-specific TEFs are obtained from EPA's

Recommended Toxicity Equivalence Factors (TEFs) for Human Health Risk Assessments of 2,3,7,8-
Tetrachlorodibenzo-p-dioxin and Dioxin-Like Compounds (EPA/100/R 10/005), December 2010. All
members of this class are assigned the weight of evidence (WOE) assigned to TCDD, which is currently B2.

•	Polyaromatic hydrocarbons (PAHs) - SCDM contains cancer slope factor and IUR values for
benzo(a)pyrene. When a slope factor and/or IUR are not available for similar PAHs listed in SCDM, SCDM
applies TEFs to determine values for these substances. PAH-specific TEFs are obtained from EPA's
Provisional Guidance for Quantitative Risk Assessment of Poly cyclic Aromatic Hydrocarbons (EPA/600/R-
93/089), July 1993.

•	Xylenes - Values are provided for o-xylene, m-xylene and p-xylene. If no data can be found in the specified
references for the individual substances, but data are available for the generic class of xylenes, SCDM
assigns the generic value to the individual substances. The class of xylenes is a relatively small set of
isomers that are likely to occur as mixtures. The class also is well defined in that the generic class (e.g.,
xylenes) almost always refers to a mixture of all members of the class (o-, m-, and p-xylene). The expected
similarity in chemical behavior for members of each class, as well as the likelihood that they will occur as
mixtures, makes using data from mixtures reasonable.

•	Dibutyltin compounds - SCDM assigns an RfD for dibutyltin dichloride using the following molecular
weight conversion of the RfD assigned to dibutyltin: RfD (dibutyltin dichloride) = RfD (dibutyltin) x
[molecular weight (dibutyltin dichloride) / molecular weight (dibutyltin)].

•	Tributyltin compounds - SCDM assigns an RfD for tributyltin chloride using the following molecular
weight conversion of the RfD assigned to tributyltin: RfD (tributyltin chloride) = RfD (tributyltin) x
[molecular weight (tributyltin chloride) / molecular weight (tributyltin)].

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2.1.3 Substitution Classes

In some cases, SCDM uses data from a parent substance class, for particular substances of that class. SCDM
contains three major classes of data for which data substitution may be applied: (1) toxicity, (2) ground water
mobility and (3) other. All toxicity data used to determine human- or eco-toxicity factor values can be
substituted. Ground water mobility data substitutions include water solubility, geometric mean water solubility
and soil/water distribution coefficient (K^). Parent class data also may be used for hydrolysis, biodegradation,
photolysis and volatilization half-lives, as well as bioconcentration factor (BCF) and logarithm of the n-octanol-
water partition coefficient (Log Kow).

Currently in SCDM, two groups of substances inherit data from a parent substance: metals and radioactive
substances. Generally, metal-containing substances inherit data for ground water mobility values with the
elemental metal as the class parent. Radioactive isotopes may inherit data from the primary radioactive element.
Substitute data are not applied to radioactive isotope decay chains.

2.1.4 Substances with Unique Value Selection

• Cadmium - For cadmium, the Integrated Risk Information System (IRIS) contains two RfD values: one for
drinking water and one for dietary exposure. Because SCDM calculates RfD-based, non-cancer screening
concentration benchmarks for both drinking water and dietary exposures, the more conservative value is
used; therefore, SCDM uses the drinking water RfD for cadmium.

• Asbestos and Lead - The HRS specifies that a human toxicity factor of 10,000 be assigned to asbestos, lead
and lead compounds. Asbestos also receives a Kd value of 1,000, as stated in the HRS.

• Copper - SCDM uses a HEAST water quality standard of 1.3 mg/L to determine an RfD for copper, based
on drinking water exposure assumptions of 70 kg body mass, 30 years exposure, and lL/day ingestion.

• Vanadium - SCDM assigns an RfD that has been identified for vanadium pentoxide as the RfD for
vanadium.

2.2 Data Used to Determine Human Toxicity Factor Values and Screening Concentration
Benchmarks

Section 2.2 details how data are obtained for determining human toxicity factor (HTF) values and screening
concentration benchmarks. RfD, RfC, SF, IUR, lethal dose with 50% mortality (LD50), lethal concentration with
50% mortality (LC50) and effective dose (ED10) values are identified and used to determine the HTF value for
each substance according to HRS Section 2.4.1.1. The RfD, RfC, SF, IUR values are also used to determine
screening concentration benchmarks (see Section 4.0 of this document).

Non-carcinogenic data (RfD, RfC, LD50and LC50) and carcinogenic data (IUR, SF and EDi0) are selected for
each substance according to a hierarchy of references. Of the values selected, the most conservative (i.e., most
protective of human health) is used to determine the HTF, regardless of exposure route or whether the value
represents a non-cancer or cancer effect.

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2.2.1 SF, IUR, RfD and RfC Data Collection

SCDM does not assign RfD or RfC data to radionuclides. SF values (inhalation, oral and external exposure) are
obtained for radionuclides from the following references, listed in order of preference:

• U.S. EPA Preliminary Remediation Goals (PRGs) for Radionuclides. Office of Superfund Remediation and
Technology Innovation (OSRTI). http://epa-prgs.ornl.gov/radionuclides/download.html. Accessed October
2012.

• U.S. EPA. Health Effects Assessment Summary Tables {HEAST). Office of Research and
Development/Office of Emergency and Remedial Response, Washington, DC. http://epa-heast.ornl.gov/.
Accessed September 2012.

For all other substances, RfD and RfC values are obtained from the following references, listed in order of
preference:

• U.S. EPA. Integrated Risk Information System (IRIS). Office of Research and Development, Cincinnati,
OH. http://www.epa.gov/iris. Accessed October 2012.

• Provisional Peer Reviewed Toxicity Values for Superfund (PPRTVs) derived by the EPA's Superfund Health
Risk Technical Support Center (STSC) for the EPA Superfund program, http://hhpprtv .ornl.gov. Accessed
September 2012.

• The Agency for Toxic Substances and Disease Registry (ATSDR) minimal risk levels (MRLs).
http://www.atsdr.cdc.gov/mrls/mrllist.asp (non-cancer data only) Accessed September 2012.

• The California Environmental Protection Agency (CALEPA) Office of Environmental Health Hazard
Assessment's (OEHHA) Chronic Reference Exposure Levels (RELS) and Cancer Potency Values. Main
database. http://oehha.ca.gov/risk/chemicalDB/index.asp. Accessed September 2012.

• PPRTV Appendix, http://hhpprtv.ornl.gov/quickview/pprtv compare.php. Accessed September 2012.

• U.S. EPA. Health Effects Assessment Summary Tables (HEAST). Office of Research and
Development/Office of Emergency and Remedial Response, Washington, DC. http://epa-heast.ornl.gov/.
Accessed September 2012.

ATSDR provides MRLs for acute (1 - 14 days), intermediate (>14 - 364 days), and chronic (365 days and
longer) exposure durations. During SCDM data collection, preference is given to ATSDR values that are based
on chronic exposure. Where chronic exposure values are not available, SCDM uses values based on
intermediate exposure. Where intermediate MRLs are used in SCDM, the reference provided in the SCDM
Appendices is "ATSDR-Int." SCDM does not use MRLs that are based on acute exposure.

For non-radionuclide substances, SF and IUR values are obtained from the following references, listed in order
of preference:

• U.S. EPA. Integrated Risk Information System (IRIS). Office of Research and Development, Cincinnati,
OH. http://www.epa.gov/iris. Accessed October 2012.

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• The California Environmental Protection Agency (CALEPA) Office of Environmental Health Hazard
Assessment's (OEHHA) Chronic Reference Exposure Levels (RELS) and Cancer Potency Values. Main
database, http://oehha.ca.gov/risk/chcmicalDB/index.asp. Accessed September 2012.

• PPRTV Appendix, http://hhpprtv.ornl.gov/quickview/pprtv compare.php. Accessed September 2012.

An oral cancer slope factor was not available for chromium VI, from the first three references listed (IRIS,
PPRTV, ATSDR); an oral cancer slope factor from the New Jersey Department of Environmental Protection
(NJDEP Division of Science, Research and Technology, Derivation of Ingestion-Based Soil Remediation
Criterion for Cr+6 Based on the NTP Chronic Bioassay Data for Sodium Dichromate Dihydrate, April 2009.
http://www.state.ni.us/dep/dsr/chromium/soil-cleanup-derivation.pdf) includes consideration of mutagenicity,
and was preferred over the slope factor provided in CALEPA OEHHA.

2.2.2 Weight of Evidence (WOE)

When available, a carcinogenic risk WOE classification is collected from the same reference that provided the
corresponding cancer risk value (e.g., IUR or SF). If only an oral WOE classification is provided for a substance
that is identified as carcinogenic via inhalation, the oral WOE is recorded for the inhalation cancer risk value. In
some instances, two or more WOE assessments are provided in a single reference. In these cases, the WOE
assessment associated with the selected risk value is used; typically, this is the most recent WOE assessment.

2.2.3 LD50 — Oral, Dermal; LC50 - Inhalation

When no RfD, RfC, cancer SF with WOE or IUR with WOE are available, SCDM uses an LD50 (oral, dermal)
or LC50 (dust and gas inhalation) to assign HTF values. The lowest value is used to determine the HTF. LD50
and LC50 values are not used to calculate screening concentration benchmarks.

SCDM does not assign LD50 and LC50 values to radionuclides. The references used to collect these data for other
substances are listed below, in order of preference:

• American Conference of Governmental Industrial Hygienists (ACGIH). 2012. Threshold Limit Values and
Biological Exposure Indices, ACGIH, Cincinnati, OH.ISBN: 978-1-607260-48-6.
http://www.acgih.org/store/ProductDetail.cfm?id=2190.

• National Institute for Occupational Safety and Health (NIOSH). 2012. Registry of Toxic Effects of Chemical
Substances (RTECS). http://www.cdc.gov/niosh/rtecs/.

SCDM contains the lowest LD50 or LC50 value for any mammalian species by the oral and dermal exposures, in
controlled dose studies, with durations of less than 24 hours. LD50 and LC50 data that are reported in the
references as less than or greater than a particular value are considered non definitive and are not used in
SCDM.

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2.2.4 ED 10 and Weight-of-Evidence — Oral, Inhalation

When a cancer SF with WOE is not available, SCDM uses ED10 oral and inhalation values to calculate cancer
SF (see Section 3.3 of this methodology document). SCDM does not assign EDi0 values to radionuclides. For all
other substances, SCDM uses data from the following references, listed in order of preference for oral and
inhalation ED10 and associated WOEs:

• U.S. EPA. 1989. Methodology for Evaluating Potential Carcinogenicity in Support of Reportable Quantity
Adjustments Pursuant to CERCLA Section 102 (EPA_ED10), Office of Health and Environmental
Assessment, Washington DC (EPA/600/8-89/053).

• U.S. EPA. 1986. SuperfundPublic Health Evaluation Manual (SPHEM), Office of Emergency and
Remedial Response, Washington DC (EPA/540/1-86/060) (OSWER Directive 9285, 4-1).

EDio data that are reported in the references as less than or greater than a particular value are considered non
definitive and are not used in SCDM.

2.3 Mobility Information

Vapor pressures and Henry's Law Constants are used to determine the gas migration potential and gas mobility

potential for each substance. Water solubility and soil/water distribution coefficients are used to determine

ground water mobility factor values. Henry's Law Constants are also used to determine volatilization half life.

2.3.1 Vapor Pressure

SCDM uses data from the following references to obtain vapor pressures for organic compounds, listed in order

of preference:

• PHYSPROP Database. Syracuse Research Corporation (SRC). Syracuse, NY. http://www.svrres.com/what-
we-do/databaseforms.aspx?id=386. Accessed September 2012.

• The Estimation Programs Interface (EPI) Suite™ (experimental values). Developed by the U.S.
Environmental Protection Agency's Office of Pollution Prevention and Toxics and Syracuse Research
Corporation (SRC), http://www.epa.gov/opptintr/exposure/pubs/episuite.htm. Accessed September 2012.

• Perry's Chemical Engineers' Handbook, 8th Edition. 2008. Perry, Roberts H., Green, Don W., McGraw-Hill,
ISBN: 978-0-07-142294-9.

• CRC Handbook of Chemistry and Physics, 93rd Edition. 2012 - 2013. W.M. Haynes, National Institute of
Standards and Technology, CRC Press, Boulder, Colorado. ISBN-10: 1439855110/ISBN-13: 978-
1439855119.

• O'Neil, M., and A. Smith (Eds). 2012. The Merck Index, 14thEdition. Merck & Co., Inc., Rahway, NJ.

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SCDM uses data from the following references to obtain vapor pressures for non-organic compounds, listed in
order of preference:

• PHYSPROP Database. Syracuse Research Corporation (SRC). Syracuse, NY. http://www.svrres.com/what-
we-do/databaseforms.aspx?id=386. Accessed September 2012.

• Lange's Handbook of Chemistry. 16th Edition. 2004. Speight, James G., McGraw-Hill, ISBN-
10:0071432205 / ISBN-13: 978-0071432207.

• Perry's Chemical Engineers' Handbook, 8th Edition. 2008. Perry, Roberts H., Green, Don W., McGraw-Hill,
ISBN: 978-0-07-142294-9.

• O'Neil, M., and A. Smith (Eds). 2012. The Merck Index, 14thEdition. Merck & Co., Inc., Rahway, NJ.

If a recommended vapor pressure is not provided in the references, SCDM uses a value measured at 25°C. If
more than one vapor pressure measured at 25°C is available, SCDM uses the highest value. If no value is
available at 25°C, the value determined at a temperature closest to 25°C is selected. If no temperature is
specified for all vapor pressure measurements for a substance, SCDM uses the highest value.

If no vapor pressure values are available in any of the references listed or if the referenced value is suspect, a
value may be either selected from a data source outside the hierarchy or estimated. For any given substance,
suspect values are identified by comparison with other vapor pressure values in SCDM data sources or other
sources of chemical property data. The procedures described in Lyman et al. (1990) are used to estimate vapor
pressure. RTI (1996) describes the use of these procedures for specific hazardous substances.

• Estimation procedures set forth by Lyman et al. 1990. Handbook of Chemical Property Estimation Methods.
American Chemical Society, Washington, DC, as described in Research Triangle Institute (RTI). 1996.
Chemical Properties for SCDM Development, Prepared for U.S. EPA Office of Emergency and Remedial
Response.

For organic substances, if a vapor pressure is not available, a normal boiling point is obtained from the reference
hierarchy listed in Section 2.8.1. If the boiling point at 1 atmosphere (atm) is <25 °C, a default vapor pressure of
760 Torr is used with the assumption that the substance is a gas at 25°C.

If no vapor pressure is available for a substance and the normal boiling point is >25 °C, SCDM assumes that the
substance is in a particulate form, rather than a gaseous form, and no vapor pressure is assigned. This
assumption is made because the absence of a vapor pressure value often reflects an extremely low and difficult
to measure (under standard conditions) value for nongaseous substances.

2.3.2 Henry's Law Constant

SCDM uses data from the following references to obtain Henry's Law Constants (HLC) for organic compounds,
listed in order of preference:

• PHYSPROP Database. Syracuse Research Corporation (SRC). Syracuse, NY. http://www.svrres.com/what-
we-do/databaseforms.aspx?id=386. Accessed September 2012.

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• EPI Suite™ (experimental values). Developed by the US Environmental Protection Agency's Office of
Pollution Prevention and Toxics and Syracuse Research Corporation (SRC).
http://www.epa.gov/opptintr/exposure/pubs/episuite.htm. Accessed September 2012.

• CHEMFATE Database. Syracuse Research Corporation (SRC). Syracuse, NY http://www.srcinc.com/what-
we-do/databaseforms.aspx?id=381. Accessed December 2012.

SCDM uses data from the following references to obtain HLC's for inorganic compounds, listed in order of
preference:

• PHYSPROP Database. Syracuse Research Corporation (SRC). Syracuse, NY. http://www.svrres.com/what-
we-do/databaseforms.aspx?id=386. Accessed September 2012.

• CRC Handbook of Chemistry and Physics. 93rd Edition. 2012 - 2013. W.M. Haynes, National Institute of
Standards and Technology, CRC Press, Boulder, Colorado. ISBN-10: 1439855110/ISBN-13: 978-
1439855119.

• Lange's Handbook of Chemistry. 16th Edition. 2004. Speight, James G., McGraw-Hill, ISBN-
10:0071432205 / ISBN-13: 978-0071432207.

• Perry's Chemical Engineers' Handbook, 8th Edition. 2008. Perry, Roberts H., Green, Don W., McGraw-Hill,
ISBN: 978-0-07-142294-9.

• O'Neil, M., and A. Smith (Eds). 2012. The Merck Index, 14thEdition. Merck & Co., Inc., Rahway, NJ.

If a recommended value is not available, SCDM uses a value measured at 25°C. If more than one value
measured at 25°C is available, SCDM uses the highest one. If no value is available at 25°C, the value
determined at a temperature closest to 25°C is selected. If more than one value measured at the same
temperature is available and none is recommended, SCDM uses the highest value. If no temperature is specified
for all Henry's Law Constants for a substance, SCDM uses the highest value.

2.3.3 Water Solubility

Water solubility is used, along with values, to calculate the ground water mobility of hazardous substances
that do not meet observed release criteria. All hazardous substances that are available to migrate from sources at
a site to the ground water are evaluated for ground water mobility. Water solubility values are also used to
assign BCF values for hazardous substances when BCF or Log Kow data are not available.

2.3.3.1 Water Solubility - Organic Substances

SCDM obtains water solubility values for organic substances from the following references, listed in

order of preference:

• PHYSPROP Database. Syracuse Research Corporation (SRC). Syracuse, NY.

http://www.svrres.com/what-we-do/databaseforms.aspx?id=386. Accessed September 2012.

• EPI Suite™ (experimental values) developed by the US Environmental Protection Agency's Office
of Pollution Prevention and Toxics and Syracuse Research Corporation (SRC).
http://www.epa.gov/opptintr/exposure/pubs/episuite.htm. Accessed April - November 2012.

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• CRC Handbook of Chemistry and Physics. 93rd Edition. 2012 - 2013. W.M. Haynes, National
Institute of Standards and Technology, CRC Press, Boulder, Colorado. ISBN-10:

1439855110/ISBN-13: 978-1439855119.

• Perry's Chemical Engineers' Handbook, 8th Edition. 2008. Perry, Roberts H., Green, Don W.,
McGraw-Hill, ISBN: 978-0-07-142294-9.

• Lange's Handbook of Chemistry. 16th Edition. 2004. Speight, James G., McGraw-Hill, ISBN-
10:0071432205 / ISBN-13: 978-0071432207.

• Estimation procedures set forth by Lyman et al. 1990. Handbook of Chemical Property Estimation
Methods. American Chemical Society, Washington, DC, as described in Research Triangle Institute
(RTI). 1996. Chemical Properties for SCDM Development, Prepared for U.S. EPA Office of
Emergency and Remedial Response.

If a recommended value is not available, SCDM uses a value measured at 25°C. If more than one value
measured at 25°C is available, SCDM uses the highest one. If no value is available at 25°C, the value
determined at a temperature closest to 25°C is selected. If more than one value measured at the same
temperature is available and none is recommended, SCDM uses the highest value. If no temperature is
specified for all water solubility measurements for a substance, SCDM uses the highest value.

2.3.3.2 Water Solubility - Metals, Metalloids and Radionuclides

SCDM obtains water solubility values for metals and metalloid compounds from the following
references, listed in order of preference:

• PHYSPROP Database. Syracuse Research Corporation (SRC). Syracuse, NY.

http://www.svrres.com/what-we-do/databaseforms.aspx?id=386. Accessed September 2012.

• CRC Handbook of Chemistry and Physics. 93rd Edition. 2012 - 2013. W.M. Haynes, National
Institute of Standards and Technology, CRC Press, Boulder, Colorado. ISBN-10:

1439855110/ISBN-13: 978-1439855119.

• Lange's Handbook of Chemistry. 16th Edition. 2004. Speight, James G., McGraw-Hill, ISBN-
10:0071432205 / ISBN-13: 978-0071432207.

• Perry's Chemical Engineers' Handbook, 8th Edition. 2008. Perry, Roberts H., Green, Don W.,
McGraw-Hill, ISBN: 978-0-07-142294-9.

For a metal or metalloid substance, SCDM determines and assigns water solubility as the geometric
mean of the highest and lowest water solubility values available for compounds containing the metal or
metalloid, as defined in the HRS (see HRS Section 3.2.1.2, Mobility) and described in Section 3.7 of
this document.

2.3.4 Soil/Water Distribution Coefficient (Kd); Soil Organic/Carbon Partition Coefficients (Koc
and Log Kow)

Kd values are used to calculate ground water mobility for hazardous substances that do not meet observed
release criteria. If values are not available, associated Koc and Log Kow values are used to calculate K^. All

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hazardous substances that are available to migrate from sources at the site to ground water are evaluated for
ground water mobility.

For organic substances, SCDM calculates the according to HRS Section 3.2.1.2 (Mobility) and the
relationship of = Koc x fs (see Section 3.6 of this methodology document), where fs is the sorbent content
(fraction of clays plus organic carbon) and Koc is obtained from the following references, listed in order of
preference:

• EPI Suite™ (estimated values) developed by the U.S. Environmental Protection Agency's Office of
Pollution Prevention and Toxics and Syracuse Research Corporation (SRC).
http://www.epa.gov/opptintr/exposure/pubs/episuite.htm. Accessed April - November 2012.

• U.S. EPA. 2002. Supplemental Guidance for Developing Soil Screening Levels for Superfund Sites (Peer
Review Draft), OSWER 9355.4-24. http://www.epa.gov/superfund/health/conmedia/soil/pdfs/ssg main.pdf.
Accessed August 2012.

• EPI Suite™ (experimental values) developed by the U.S. Environmental Protection Agency's Office of
Pollution Prevention and Toxics and Syracuse Research Corporation (SRC).
http://www.epa.gov/opptintr/exposure/pubs/episuite.htm. April - November 2012

• Estimated as described in Section 3.6 of this methodology document

When using values from EPI Suite™, SCDM prefers Koc values that are estimated using the Molecular
Connectivity Index (MCI) method over Koc values that are estimated by the Log Kow method. When a Koc is
not available using the MCI method, SCDM uses the EPI Suite™ Koc values estimated using the Log Kow
method. Information regarding collection of Log Kow values is provided in Section 2.5.2 of this methodology
document. Section 3.6 (Soil Water Distribution Coefficient [K^]; Soil Organic/Carbon Partition Coefficients
[Koc]) of this document provides additional information regarding SCDM calculations of and Koc values.

SCDM obtains values for inorganic substances from the following references, listed in order of preference:

• U.S. EPA. 2002. Supplemental Guidance for Developing Soil Screening Levels for Superfund Sites (Peer
Review Draft), Office of Solid Waste and Emergency Response. 9355.4-24.
http://www.epa.gov/superfund/health/conmedia/soil/pdfs/ssg main.pdf. Accessed August 2012.

• U.S. EPA. 1996. Soil Screening Guidance: Technical Background Document. EPA/540/R95/128. Office of
Emergency and Remedial Response, Washington, DC. NTIS PB96-963502.
http://www.epa.gov/superfund/health/conmedia/soil/index.htm. Accessed August 2012.

• Baes, C.F. Ill, R.D. Sharp, and A.L. Sjoreen, and R.W. Shor. 1984. A Review and Analysis of Parameters
for Assessing Transportation of Environmentally Released Radionuclides through Agriculture. Oak Ridge
National Laboratory, TN. ORNL-5786.

• HRS Section 3.2.1.2 (See Section 3.6 of this methodology document).

SCDM contains values corresponding to typical subsurface pH (e.g., 6.8).

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2.4 Persistence Information

The evaluation of persistence is based primarily on the half-life of hazardous substances in surface water and
(for non-radionuclides) secondarily on the sorption of the hazardous substances to sediments. Persistence
information is used to determine the surface water persistence factor value.

2.4.1 Hydrolysis, Biodegradation and Photolysis Half-Lives

SCDM does not assign hydrolysis, biodegradation or photolysis half lives to radionuclides. SCDM obtains
hydrolysis, biodegradation and photolysis half-lives for all other substances from the following references, listed
in order of preference:

• CHEMFATE Database. SRC. Syracuse Research Corporation (SRC). Syracuse, NY.
http://www.srcinc.com/what-we-do/databaseforms.aspx?id=381. Accessed December 2012.

• Handbook of Environmental Degradation Rates (HEDR). 1991. Howard, Phillip H., W.F. Jarvis, W.M.
Meylan and E.M. Michalenko, Lewis Publishers, Inc. Chelsea, Michigan.

SCDM only uses values that have been measured in water from the CHEMFATE database. SCDM uses a value
measured at 25°C. If more than one value measured at 25°C is available, SCDM uses the highest value. If no
value is available at 25 °C, a value determined at a temperature closest to 25 °C is selected. If no temperature is
specified for all half-life values for a substance, SCDM uses the highest value. If values are obtained from
HEDR, SCDM uses only values listed as "first-order." If multiple values are provided, the highest value is used.

2.4.2 Volatilization Half-Lives

SCDM estimates volatilization half-lives for organic substances in both rivers and lakes, using the equations and
procedures described in Section 3.4 of this methodology document. Volatilization half-lives are not collected or
estimated for inorganic substances.

2.4.3 Radioactive Half-Lives

SCDM obtains radioactive half-lives for radioactive substances from the following references, listed in order of
preference:

• U.S. EPA. October 2000. Soil Screening Guidance for Radionuclides: User's Guide. EPA/540-R-00-007
PB2000 963307. http://www.epa.gov/superfund/health/contaminants/radiation/radssg.htm. Accessed August
2012.

2.5 Bioaccumulation Potential Information

BCF values for freshwater and saltwater (one set each for the human food chain and environmental threats) are
used to determine bioaccumulation potential factor values (40 CFRPart 300, Appendix A, Section 4.1.3.2.1.3).
BCF values are selected based on edible species to determine bioaccumulation potential factor values for the
human food chain threat. If BCF data are not available for organic substances, the Log Kow is used to determine

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bioaccumulation potential factor values. Water solubility data are used if the Log Kow exceeds 6.0, the
substance is inorganic or there is no Log Kow.

2.5.1 Bioconcentration

Bioaccumulation factor values in SCDM are preferentially based on actual measurements of bioconcentration in
aquatic organisms. SCDM used BCF values from the following sources, listed in order of preference:

• U.S. EPA. ECOTOX Database. Environmental Research Laboratory, Duluth, MN.
http://www.epa.gov/ecotox. Accessed September 2012.

• Versar, Inc. 1990. Issue Paper: Bioaccumulation Potential Based on Ambient Water Quality Criteria
Documents (VERBCF). Prepared for U.S. EPA Office of Emergency and Remedial Response,

Washington, DC. Contract No. 68-W8-0098.

SCDM uses the highest measured value from ECOTOX. Measured values are preferred over calculated or
estimated values. The Versar reference is a report of literature survey BCF values developed to obtain
preliminary values for use when the initial HRS was being developed. When using data from this reference,
SCDM also prefers the highest measured value to an estimated value. BCF data reported in the references as less
than or greater than a particular value are considered non definitive and are not used in SCDM.

Environmental Threat: For the environmental threat, the highest value from any aquatic organism, regardless of
whether it is consumed by humans, in each reference is used to establish environmental threat BCF values.

Human Food Chain Threat: The highest measured BCF for aquatic organisms typically known to be consumed
by humans is used to obtain the human food chain threat BCF values. Table 1 includes a list of some of the
organisms for which these BCF values may be taken. This list is intended to serve only as a guide to the SCDM
data collector and hence, not all human food chain aquatic organisms are listed. Values from organisms not in
this list may be used provided they are known to be consumed by humans.

Table 1. Examples of Human Food Chain Aquatic Organisms

American or Virginia

Carp

Kiyi

Red abalone

oyster

Chinook salmon

Lake trout (siscowet)

Red swamp crayfish

Asiatic clam

Channel catfish

Lake whitefish

River salmon

Atlantic dogwinkle

Clam

Largemouth bass

Rock bass

Atlantic salmon

Cockle

Limpet

Rough periwinkle

Atlantic silverside

Coho salmon

Lobster

Sauger

Bay scallop

Common bay mussel

Mangrove snapper

Scallop

Bent-nosed clam

Common mirror colored

Marsh snail

Shrimp

Bivalve/clam/mussel

Carp

Mussel

Sole

Black abolone

Common shrimp

Netted dog whelk

Spot

Black bullhead

Crab

Northern anchovy

Striped bass

Black crappie

Crayfish

Northern krill

Striped mullet

Black mussel

Dungeness or edible crab

Northern pike

Swan mussel

Blue crab

Eel

Oyster

Taiwan abalone

Bluegill

Filefish

Pilchard sardine

Tong sole

Bony fishes

Flounder

Pinfish

Topmouth gudgeon (golden shiner)

Brook silverside

Giant gourami

Pink salmon

White mullet

Brook trout

Green sunfish

Porgy

White sand mussel

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Brown trout

Golden shiner

Prawn

Whiting

Brown shrimp

Gudgeon

Rainbow trout

Winkle, common edible

Bull frog

Gulf toadfish

2.5.2 Octanol/W'iter Partition Coefficient (Log Kow)

Log Kow values are used to determine the bioaccumulation potential factor value for a hazardous substance for
which BCF data are not available. SCDM may also use the log Kow to estimate a log Koc when a Koc is not
available (see Sections 2.3.4 and 3.2 of this methodology document). SCDM obtains n-octanol/water (log Kow,
also referred to as Log P) values from the following sources, listed in order of preference:

• EPI Suite™ (organic substances, experimental values) developed by the U.S. Environmental Protection
Agency's Office of Pollution Prevention and Toxics and Syracuse Research Corporation (SRC).
http://www.epa.gov/opptintr/exposure/pubs/episuite.htm. Accessed April - November 2012.

• PHYSPROP Database. Syracuse Research Corporation (SRC). Syracuse, NY. http://www.svrres.com/what-
we-do/databaseforms.aspx?id=386. Accessed September 2012.

• CHEMFATE Database. Syracuse Research Corporation (SRC). Syracuse, NY. http://www.srcinc.com/what-
we-do/databaseforms.aspx?id=381. Accessed December 2012.

• Research Triangle Institute (RTI). 1996. Chemical Properties for SCDM Development. Prepared for the
U.S. EPA Office of Emergency and Remedial Response, Washington, DC.

SCDM uses experimental values; estimated or calculated values are not used. If values are obtained from
CHEMFATE, the recommended values are used.

2.5.3 Water Solubility

Water solubility values are used to assign a bioaccumulation potential factor value for hazardous substances
when BCF or log Kow data are not available. See Sections 2.3.3.1 (Water Solubility - Organic Substances) and
2.3.3.2 (Water Solubility - Metals, Metalloids and Radionuclides) of this methodology document for the data
collection protocol and guidance on water solubility values.

2.6 Ecotoxicity Parameters

Ecotoxicity data are used in the HRS scoring system to determine the Ecotoxicity Factor values (HRS; 40 CFR
Part 300, Appendix A, Section 4.1.4.2.1.1). SCDM uses acute and chronic freshwater and saltwater criteria, and
only uses those values specifically stated as criteria. If criteria are not available, then LC50 data are used.

2.6.1 Acute and Chronic Freshwater and Saltwater Criteria - CCC, CMC

The HRS (Section 4.1.4.2.1.1, Ecosystem Toxicity) uses the EPA Ambient Water Quality Criteria (AWQC) and
Ambient Aquatic Life Advisory Concentrations (AALAC) for assigning ecosystem toxicity factor values. The

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acute and chronic AWQC have been replaced by a new set of criteria, and the AALAC values no longer exist.
The new criteria replacing the AWQC for both freshwater and saltwater are labeled as (1) Criteria Maximum
Concentration (CMC), to be used in place of what was previously acute AWQC, and (2) Criteria Continuous
Concentration (CCC), to be used in place of what was previously chronic AWQC. These new values closely
correspond to the old acute and chronic AWQC values, respectively; however, some values have been re-
derived using different methodology. Therefore, the resulting values must be used as directed by the EPA. Many
of the CMC and CCC values have associated endnotes regarding how the value was derived and how it should
be used. Some CMC and CCC values are baseline values that must be adjusted using the information specified
in the endnotes. The CMC and CCC values are taken from:

• U.S. EPA. National Recommended Water Quality Criteria. Office of Water. Washington, DC.
http://water.epa.gOv/scitech/swguidance/standards/current/index.cfm#altable. Accessed October 2012.

2.6.2 LCso - Freshwater, Saltwater

SCDM obtains LC50 data from the ECOTOX database for both freshwater and saltwater.

• U.S. EPA. 2012. ECOTOX Database. Environmental Research Laboratory, Duluth, MN.
http://www.epa.gov/ecotox. Accessed September 2012.

SCDM uses the lowest acute LC50 value found for any aquatic organism in the specified environment with an
acute exposure duration of >1 day and < 4 days. When no duration or environment is given, LC50 values are not
entered into SCDM.

2.7 Regulatory Benchmarks

The HRS assigns extra weight to targets with exposure to hazardous substances at levels that are at or above
regulatory benchmark values. This section describes the sources for regulatory limits that the HRS uses as
health-based or ecological-based benchmarks.

2.7.1 National Ambient Air Quality Standards (NAAQS)

National Ambient Air Quality Standards (NAAQS) are used to establish Level I concentrations. Targets exposed
to concentrations at or above the NAAQS are scored as Level I targets. SCDM uses data from the following
source to obtain NAAQS:

• 40 CFR Part 50. National Ambient Air Quality Standards, http://www.epa.gov/air/criteria.html. Accessed
October 2012.

2.7.2 National Emissions Standards for Hazardous Air Pollutants (NESHAPs)

National Emission Standards for Hazardous Air Pollutants (NESHAPs) are used to establish Level I
concentrations. Targets exposed to concentrations at or above NESHAPs are scored as Level I targets. SCDM
uses data from the following source to obtain NESHAPs and uses only those values that are reported in ambient
concentration units ((.ig/nr1):

• 40 CFR Part 61 and Part 63. National Emission Standards for Hazardous Air Pollutants.

http://www.epa.gov/compliance/monitoring/programs/caa/neshaps.html. Accessed October 2012.

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2.7.3 Maximum Contaminant Levels (MCLs) and Maximum Contaminant Level Goals (MCLGs)

Maximum Contaminant Levels (MCLs) and Maximum Contaminant Level Goals (MCLGs) are used to establish
Level I concentrations. Targets exposed to concentrations at or above MCLs and MCLGs are scored as Level I
targets. SCDM uses data from the following sources for MCLs and MCLGs:

• U.S. EPA. 2009. National Primary Drinking Water Standards. Accessed through List of Drinking Water
Contaminants and MCLs. Office of Water, Washington, DC.
http://water.epa.gov/drink/contaminants/index.cfm. Accessed October 2012.

• U.S. EPA. October 2000. Soil Screening Guidance for Radionuclides: User's Guide (EPA/540-R-00-007,
PB2000 963307). http://www.epa.gov/superfund/health/contaminants/radiation/radssg.htm. Accessed
August 2012.

SCDM uses only MCLs that are reported in units of concentration (mg/L, |ig/L or pCi/L) and only non-zero
MCLGs that are reported in units of concentration (mg/L or |i/L). For substances where multiple values are
listed, SCDM uses the lowest value. For substances where both MCLs and MCLGs are provided but are
different, SCDM selects the lower of the two values.

2.7.4 FDA Action Levels (FDAALs)

Food and Drug Administration Action Levels (FDAAL) are used to establish Level I concentrations. Targets
exposed to concentrations at or above FDAALs are scored as Level I targets. SCDM contains FDAALs for fish
and shellfish only, and obtains the FDAAL values from the following reference:

• U.S. Food and Drug Administration. 2000. Action Levels for Poisonous or Deleterious Substances in
Human and Animal Feed. Center for Food Safety and Applied Nutrition, Washington, D.C.
http://www.fda.gov/Food/GuidanceComplianceRegulatorvInformation/GuidanceDocuments/ChemicalConta
minantsandPesticides/ucm077969.htm. Accessed October 2012.

2.7.5 Ecological Based Benchmarks

See Section 2.6.1 of this document for information regarding acute CMC and chronic CCC for freshwater and
saltwater.

2.7.6 Uranium Mill Tailings Radiation Control Act Standards (UMTRCA)

Uranium Mill Tailings Radiation Control Act (UMTRCA) standards are used to establish Level I
concentrations. Targets exposed to concentrations at or above UMTRCA standards are scored as Level I targets.
SCDM extracts UMTRCA data directly from 40 CFR Part 192 (Uranium Mill Tailings Radiation Control Act
Standards), http://www.wise-uranium.org/ulus.html. Accessed October 2012.

2.8 Physical Properties

SCDM contains hazardous substance physical property data including, but not limited to, chemical formula,
molecular weight, density, boiling point and melting point. SCDM applies yes/no flags to classify physical
property data into the four substance categories defined below.

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Organic Substances ("Organic"): "Y" indicates that the substance is organic, and "N" indicates an inorganic
substance. This flag is used to determine factor values for ground water mobility and bioaccumulation potential.
Volatile and semivolatile organics are indicated. These flags influence the SCDM calculation of Kd values.

Metal-Containing Substances ("Metal Contain"): "Y" indicates that the substance is a metal or metalloid or
an inorganic compound that contains a metal or metalloid. "N" indicates that the substance is not, or does not
contain, a metal or metalloid. This flag is used to determine factor values for ground water mobility and surface
water persistence.

Radioactive Isotope ("Radionuclide"): "Y" indicates that the substance is a specific radioactive isotope, and
"N" indicates that it is not. In SCDM, a substance cannot be both a radioactive element and a specific
radioactive isotope. This flag is used to determine factor values for human toxicity, ecosystem toxicity and
surface water persistence.

Radioactive Element ("Rad. Element"): "Y" indicates that the substance is a radioactive element, and "N"
indicates that it is not. In SCDM, a substance cannot be both a radioactive element and a specific radioactive
isotope. This flag determines whether or not the HRS factors and benchmarks are printed in Appendix A.

2.8.1 Chemical Formula, Boiling Point and Melting Point

Chemical formula, boiling point and melting point data are extracted for inorganic substances, from the
following sources in order of preference:

• PHYSPROP Database. Syracuse Research Corporation (SRC). Syracuse, NY. http://www.svrres.com/what-
we-do/databaseforms.aspx?id=386. Accessed September 2012.

• Perry's Chemical Engineers' Handbook, 8th Edition. 2008. Perry, Roberts H., Green, Don W., McGraw-Hill,
ISBN: 978-0-07-142294-9.

• Lange's Handbook of Chemistry. 16th Edition. 2004. Speight, James G., McGraw-Hill, ISBN-
10:0071432205 / ISBN-13: 978-0071432207.

• O'Neil, M., and A. Smith (Eds). 2012. The Merck Index, 14thEdition. Merck & Co., Inc., Rahway, NJ.

Chemical formula, boiling point and melting point data are extracted for all other substances, from the following
sources in order of preference:

• PHYSPROP Database. Syracuse Research Corporation (SRC). Syracuse, NY. http://www.svrres.com/what-
we-do/databaseforms.aspx?id=386. Accessed September 2012.

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•	EPI Suite™ (experimental values) developed by the U.S. Environmental Protection Agency's Office of
Pollution Prevention and Toxics and Syracuse Research Corporation (SRC).
http://www.epa.gov/opptintr/exposure/pubs/episuite.htm. Accessed April - November 2012.

•	Perry's Chemical Engineers' Handbook, 8th Edition. 2008. Perry, Roberts H., Green, Don W., McGraw-Hill,
ISBN: 978-0-07-142294-9.

2.8.2	Molecular Weight

Molecular weight data are collected for inorganic substances, from the following sources in order of preference:

•	CRC Handbook of Chemistry and Physics. 93rd Edition. 2012 - 2013. W.M. Haynes, National Institute of
Standards and Technology, CRC Press, Boulder, Colorado. ISBN-10: 1439855110/ISBN-13: 978-
1439855119.

•	PHYSPROP Database. Syracuse Research Corporation (SRC). Syracuse, NY. http://www.svrres.com/what-
we-do/databaseforms.aspx?id=386. Accessed September 2012.

•	Lange's Handbook of Chemistry. 16th Edition. 2004. Speight, James G., McGraw-Hill, ISBN-
10:0071432205 / ISBN-13: 978-0071432207.

•	Perry's Chemical Engineers' Handbook, 8th Edition. 2008. Perry, Roberts H., Green, Don W., McGraw-Hill,
ISBN: 978-0-07-142294-9.

•	O'Neil, M., and A. Smith (Eds). 2012. The Merck Index, 14thEdition. Merck & Co., Inc., Rahway, NJ.

Molecular weight data are collected for all other substances, from the following sources in order of preference:

•	EPI Suite™ (experimental values) developed by the U.S. Environmental Protection Agency's Office of
Pollution Prevention and Toxics and Syracuse Research Corporation (SRC).
http://www.epa.gov/opptintr/exposure/pubs/episuite.htm. Accessed April - November 2012.

•	CRC Handbook of Chemistry and Physics. 93rd Edition. 2012 - 2013. W.M. Haynes, National Institute of
Standards and Technology, CRC Press, Boulder, Colorado. ISBN-10: 1439855110/ISBN-13: 978-
1439855119.

•	Perry's Chemical Engineers' Handbook, 8th Edition. 2008. Perry, Roberts H., Green, Don W., McGraw-Hill,
ISBN: 978-0-07-142294-9.

•	Lange's Handbook of Chemistry. 16th Edition. 2004. Speight, James G., McGraw-Hill, ISBN-
10:0071432205 / ISBN-13: 978-0071432207.

2.8.3	Density

Density data are collected for inorganic substances, from the following sources in order of preference:

•	CRC Handbook of Chemistry and Physics. 93rd Edition. 2012 - 2013. W.M. Haynes, National Institute of
Standards and Technology, CRC Press, Boulder, Colorado. ISBN-10: 1439855110/ISBN-13: 978-
1439855119.

18

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June 2014

•	PHYSPROP Database. Syracuse Research Corporation (SRC). Syracuse, NY. http://www.svrres. com/what-
we-do/databaseforms.aspx?id=386. Accessed September 2012.

•	Lange's Handbook of Chemistry. 16th Edition. 2004. Speight, James G., McGraw-Hill, ISBN-
10:0071432205 / ISBN-13: 978-0071432207.

•	Perry's Chemical Engineers' Handbook, 8th Edition. 2008. Perry, Roberts H., Green, Don W., McGraw-Hill,
ISBN: 978-0-07-142294-9.

•	O'Neil, M., and A. Smith (Eds). 2012. The Merck Index, 14thEdition. Merck & Co., Inc., Rahway, NJ.

Density data are collected for all other substances, from the following sources in order of preference:

•	EPI Suite™ (experimental values) developed by the U.S. Environmental Protection Agency's Office of
Pollution Prevention and Toxics and Syracuse Research Corporation (SRC).
http://www.epa.gov/opptintr/exposure/pubs/episuite.htm. Accessed April - November 2012.

•	CRC Handbook of Chemistry and Physics. 93rd Edition. 2012 - 2013. W.M. Haynes, National Institute of
Standards and Technology, CRC Press, Boulder, Colorado. ISBN-10: 1439855110/ISBN-13: 978-
1439855119.

•	Lange's Handbook of Chemistry. 16th Edition. 2004. Speight, James G., McGraw-Hill, ISBN-
10:0071432205 / ISBN-13: 978-0071432207.

19

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June 2014

3.0 CALCULATION OF INTERIM VALUES

SCDM calculates specific chemical properties for some of the following cases:

•	when all preferred references do not contain a property value for a given chemical

•	the property value or values from a given reference cannot be used because they are suspect or

•	the EPA specifies that a value be calculated

3.1 RfC to RfDinhal

SCDM contains RfD values for oral toxicity and RfC values for inhalation toxicity that are used to determine
HTF values and screening concentration benchmarks. SCDM must convert RfC to RfDmh ,i- for use in these
determinations. RfC values are converted from concentrations into inhalation dosages (RfDmhal) values for
determining HTF values using the following equation:

RFDM=RFCXlRXAR	(!)

,nhal	BM

Where:

RFDinhai = Calculated Reference Dose in Air (mg/kg-day)

RFC = Reference Concentration in Air (mg/m3)

IR = Inhalation Rate (20 m3/day)

AR = Absorption (100% assumed unless otherwise specified)

BM= Adult Body Mass (70 kg)

Equation (1) is used to convert RfCs to inhalation RfDs. The resulting RfDmhai values are used to determine HTF
values (see HRS Section 2.4.1.1, Table 2-4 [40 CFR Part 300]). If the reference source used to provide the RfD
or RfC does not provide a corresponding absorption, it is assumed to be 100.

3.2 IUR to Inhalation Slope Factor

SCDM contains slope factors for oral toxicity and IUR values for inhalation toxicity. IUR values are converted
into inhalation slope factors (SFinhal) for use in determining HTF values. SCDM converts IUR values to
calculated SFinhal before assigning HTF values, using the following equation:

_ IUR xBMxCF	^

mhal ~ IR /AR

Where:

SFinhal= Cancer Slope Factor (mg/kg-day)"1

IUR	= Inhalation Unit Risk ((ig/m3)"1

BM	= Adult Body Mass (70 kg)

CF	= Conversion Factor (1,000 (ig/mg)

IR	= Inhalation Rate (20 m3/day)

AR	= Absorption (100% assumed unless otherwise specified)

Equation (2) is used to convert the IUR value to an inhalation cancer SF, and the resulting inhalation cancer SF
is evaluated with a corresponding WOE (see Section 2.2.2.1 above) to assign an HTF value based on HRS Table
2-4 (40 CFR Part 300).

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June 2014

3.3 Using ED10 to estimate a Slope Factor for either oral or inhalation pathways

SCDM uses slope factors and IUR values to determine human toxicity factor values and screening concentration
benchmarks. In cases where a slope factor and/or IUR is not available for a substance, SCDM uses ED10 values,
when available, to calculate oral and inhalation slope factors (SForai and SFmhai), as follows:

SForal = 1 / (6 * ED10oral)	(3)

SFmhal = 1 / (6 * ED10mhal)	(4)

3.4 Volatilization Half-Life

SCDM estimates the volatilization half-life in surface water for organic substances using Equation 5 (presented
as Equation 15-12 in the "Handbook of Chemical Property and Estimation Methods," Lyman, et al} In this
method, the volatilization half-life (Ti/2) can be expressed as follows:

Tl/2

Z x In 2
Kl hr

(5)

Where:

Z = Mean water body depth (cm)

Kl = Overall liquid-phase mass transfer coefficient

In 2 = Natural logarithm of 2 (-0.693147)

The following expression gives the overall liquid-phase mass transfer coefficient:
(H/RT)kg xki

Kt =

(H/RT)kg + ki

cm/hr

(6)

Where:

3

H = Henry's Law constant (atm-m /mol)

-5	3

R = Universal gas constant (8.2 x 10 atm-m /molK)

T = Temperature (K; °C + 273)
kg = Gas-phase exchange coefficient
kj = Liquid-phase exchange coefficient

The gas-phase exchange coefficient expression depends on the molecular weight (MW) of the
compound.

•	If MW is <65 g/mol, the following equation is used:

1/2

kg = 3,000 x (18 / MW) cm/hr	(7)

•	If MW is >65 g/mol, the following equation is used:

1 Thomas, R.G. 1990. "Volatilization from Water." In Handbook of Chemical Property Estimation Methods. W.J. Lyman,
W.F. Reehl, D.H. Rosenblatt, Eds. American Chemical Society, Washington, DC, 15:9-28. 0-ISBN 8412-1761-0.

21

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June 2014

1/2

k = 1,137.5 x (V +V )(18/MW) cm/hr	(8)

g	wind curr ' v	'

Where:

Vwmd = Wind velocity (m/sec)

Vcurr = Current velocity (m/sec)

The liquid-phase exchange coefficient also depends on the molecular weight of the compound.

•	If MW is <65 g/mol, the following equation is used:

1/2

kj = 20 x (44 / MW) cm/hr	(9)

•	If MW is >65 g/mol, the expression also depends on the wind and current velocities; the following
equation is used when Vwmd is <1.9 m/sec and MW is >65 g/mol:

kj = 23.51 x(Vc°u969/Za673) x (32/MW)1/2 cm/hr	(10)

The following equation is used when Vwmdis >1.9 m/sec and <5 m/sec, and MW is >65 g/mol:

kj = 23.51 x (Vc°u969 /Z0,673) x (32/MW)1/2e0'526(VwW~1,9)cm/hr	(11)

No liquid-phase exchange coefficient equation is provided in Thomas (1990) for wind velocities >5 m/sec.

Combining Equations (5), (6), (7), and (9) into a single equation for estimating volatilization half-life (T1/2) for
compounds with MW <65 g/mol gives the following equation:

T1/2 = Z x In 2 x {[(1 / 20) x (MW / 44 )1/2] + [(RT / H x 3000) x (MW /18)1/2]} hr	(12)

The following equation, combining Equations (5), (6), (8), and (10), can be used to estimate the volatilization
half-life (T1/2) for compounds with MW >65 g/mol if the wind velocity is <1.9 m/sec:

T1/2 = Z x In 2 x {[(Za673 / 23.51 x Vc°ur9r69) x (MW /32)1/2 ]

+ [(RT/Hx 1,137.5)x(Vwind + V„rr)x(MW/18)"2]}hr (13)

The following equation, combining Equations (5), (6), (8), and (11), can be used to estimate the volatilization
half-life (T1/2) for compounds with MW >65 g/mol if the wind velocity is >1.9 m/sec and <5 m/sec:

T1/2= Z x ln2 x {[(Z0,673 / 23.51 x V^969) x (MW/32)1/2] e°'526(1'9~Vwind)

+ [(RT/Hx 1.137.5) x (Vlvind + Vcurr) x (MW/18)"2]} hr (14)

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June 2014

-7	3

If H is <10 atmm /mol, the substance is less volatile than water, and its concentration will increase as the
water evaporates. The substance is considered essentially nonvolatile (Thomas, 1990, p. 15-15), and no
volatilization half-life is estimated for rivers or lakes.

3.4.1	Volatilization Half-Life for Rivers, Oceans, Coastal Tidal Waters and the Great Lakes

To calculate the volatilization half-life for rivers, oceans, coastal tidal waters and the Great Lakes, the mean
water body depth is taken as 100 cm, the temperature as 298 K, the wind velocity as 0.5 m/sec and the current
velocity as 1 m/sec. Using these values, Equations (12) and (14) reduce to the following:

•	If MW <65 g/mol:

Ti/2= 2.89 x {[0.05 x(MW/44)1/2] + [(8.1 x 10~6/H) x (MW/18)1/2]} days	(15)

•	IfMW >65 g/mol:

T1/2= 2.89 x {[0.185 x(MW/32)1/2] + [(3.6 x10"6/H)x(MW/18)1/2]} days	(16)

Where:

H = Henry's Law Constant (atmm3/mol)

MW = Molecular Weight (g/mol)

3.4.2	Volatilization Half-Life for Lakes

To calculate the volatilization half-life for lakes, the mean water body depth is taken as 100 cm, the temperature
as 298 K, the wind velocity as 0.5 m/sec and the current velocity as 0.05 m/sec. Using these values, Equations
(12) and (13) reduce to the following:

•	IfMW <65 g/mol:

Ti/2= 2.89 x {[0.05 x(MW/44)1/2] + [(8.1 x 10"6/H) x (MW/18)1/2]} days	(17)

•	IfMW >65 g/mol:

Ti/2= 2.89 x {[0.185 x (MW/32)1/2] + [(3.9 x 10"6/H) x (MW/18)1/2 ]} days	(18)

Where:

H = Henry's Law Constant (atmm3/mol)

MW = Molecular Weight (g/mol)

3.5 Overall Half-Lives

3.5.1 Overall Half-Lives for Non-radionuclides

Overall half-lives are estimated for non-radioactive substances, in rivers and lakes, as follows:

1

HALF_LAK. —	j	j	j	j		(19)

HHALFL + BHALFL + PHALFL + VHALFL

23

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June 2014

Where:

HHALFL = Hydrolysis half-life in lakes
BHALFL = Biodegradation half-life in lakes
PHALFL = Photolysis half-life in lakes
VHALFL = Volatilization half-life in lakes

HALF RiV = ¦

1111	(20)

HHALFR BHALFR PHALFR VHALFR

Where:

HHALFR = Hydrolysis half-life in rivers
BHALFR = Biodegradation half-life in rivers
PHALFR = Photolysis half-life in rivers
VHALFR = Volatilization half-life in rivers

3.5.2 Overall Half-Lives for Radionuclides

SCDM estimates overall half-lives of radionuclides in rivers and lakes as follows (this calculation is similar to
the equation used for non radioactive substances, but considers only radioactive half life and volatilization half
life):

1

HALF_R_LAK =	jj		(2|)

RHALFL + VHALFL

Where:

RHALFL = Radioactive half-life in lakes
VHALFL = Volatilization half-life in lakes

HALFJIJtIV =	j	j		(22)

RHALFR + VHALFR

Where:

RHALFR = Radioactive half-life in rivers
VHALFR = Volatilization half-life in rivers

3.6 Soil Water Distribution Coefficient (Kd); Soil Organic/Carbon Partition Coefficients
(Koc)

In the evaluation of the ground water migration pathway, a hazardous substance that does not meet the criteria
for an observed release is assigned a mobility factor value from HRS Table 3-8 (Ground Water Mobility Factor
Values) based on its value and its water solubility value. values that are not available in the references
listed in Section 2.3.4 of this methodology document are calculated as detailed below:

HRS Section 3.2.1.2 (Mobility) states:

24

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June 2014

For any hazardous substance that does not meet the criteria for an observed release by
chemical analysis to at least one of the aquifers, assign that hazardous substance a
mobility factor value from Table 3-8 for the aquifer being evaluated, based on its water
solubility and distribution coefficient (Kd).... For any hazardous substance that is organic
and that does not meet the criteria for an observed release by chemical analysis, establish
a distribution coefficient for that hazardous substance as follows:

Estimate Kd range for the hazardous substance using the following equation:

Kd = (Koc)(fs)	(23)

Where:

Koc = Soil-water partition coefficient for organic carbon for the hazardous
substance

fs = Sorbent content (fraction of clays plus organic carbon) in the subsurface

Use fs values of 0.03 and 0.77 in the above equation to establish the upper
and lower values of the range for the hazardous substance.

Calculate the geometric mean of the upper and lower range values. Use
this geometric mean as the distribution coefficient in assigning the hazardous
substance a mobility factor value from [HRS] Table 3-8.

When a Koc is not available to calculate Kd values, SCDM uses the Log P or Log Kow to estimate Koc values.
To perform this calculation, SCDM uses the relationship determined by Di'Toro (1985) for semi-volatile
organic compounds:

Log Koc = 0.00028 + (0.983 Log Kow)	(24)

For volatile organic compounds, chlorinated benzenes, and certain chlorinated pesticides, SCDM uses the
relationship derived in the Soil Screening Guidance Technical Background Document (EPA, 1996):

Log Koc = 0.0784 + (0.7919 Log Kow)	(25)

3.7 Water solubility for metals

If a water solubility value is not available for metal substances, it is calculated as the geometric mean of the
highest water solubility and lowest water solubility of substances containing the metal, using the following
equation:

Geometric Mean Solubility = ^(low water solubility) x (Mgh water solubility)	(26)

25

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June 2014

4.0 SCREENING CONCENTRATION BENCHMARKS

Section 4 details the equations and exposure assumptions that are used to determine screening concentration
benchmarks for the substances contained in SCDM. The sources of data and determination of the substance-
specific values used in these equations are detailed in Sections 2.0 and 3.0 of this methodology document.

4.1 Screening Concentration Benchmarks for the Air Migration Pathway

The following equations are used to determine air inhalation screening concentration benchmarks for the air
migration pathway. The benchmarks use exposure parameters and factors that represent Reasonable Maximum
Exposure (RME) conditions for long-term/chronic exposures and are based on the methodology outlined in the
EPA's Risk Assessment Guidance for Superfund, Part B (1991) and Risk Assessment Guidance for Superfund,
Part F (2009). General equations are provided in Section 4.1.1 (non-carcinogenic benchmarks) and Section
4.1.2 (carcinogenic benchmarks). An equation specific for asbestos is provided in Section 4.1.3. Equations that
are specific for substances that are carcinogenic through a mutagenic mode of action, including vinyl chloride
and trichloroethylene (TCE), are provided in Section 4.1.4; these equations are taken from EPA's Handbook for
Implementing the Supplemental Cancer Guidance at Waste and Cleanup Sites. Equations used for radionuclides
are provided in Section 4.1.5.

4.1.1 Non-carcinogenic - A ir, Inhalation

THQ x (AT x ED) x

SC.

1000 ng^
v mS ,

EF x ED x ET x

1 day

\

24 hours

\

I

RfC

Where:

SCnc_air = Air Inhalation Screening Concentration, Non-Carcinogenic ((.ig/nr1)

THQ = Target hazard quotient (=1), unitless

AT = Averaging time (365 days/year)

ED = Exposure duration (30 years)

EF = Exposure frequency (350 days/year)

ET = Exposure time (24 hours/day)

RfC = Inhalation reference concentration (mg/m3)

Using the exposure assumptions listed above, Equation (27) can be simplified as:

(27)

SCnc_air = 1042.857 x RfC

(28)

4.1.2 Carcinogenic — A ir, Inhalation

SC„

Where:

TR x (AT x LT)

EFx EDxETx

1 day
24 hours

\

xIUR

SCc_air = Air Inhalation Screening Concentration, Carcinogenic (|_ig/m )

(29)

26

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June 2014

TR	= Target risk (1 x 10"6) (unitless)

AT	= Averaging time (365 days/year)

LT	= Lifetime (70 years)

ED	= Exposure duration (30 years)

EF	= Exposure frequency (350 days/year)

ET	= Exposure time (24 hours/day)

IUR	= Inhalation unit risk (j^ig/m ) 1

Using the exposure assumptions listed above, Equation (29) can be simplified as:

2.433 xlO"6

SCc-air =		(30)

IUR

4.1.3 Carcinogenic — A ir, Inhalation — Asbestos

SC^r^eto, (fibers/mL) = TR (IUR x TWF)	(31)

Where:

SC c-air-asbestos

TR
IUR
TWF

= Air Inhalation Screening Concentration, Carcinogenic, Asbestos (fibers/mL)
= Target risk (1 x 10"6) (unitless)

= Inhalation Unit Risk (fibers/mL)"1
= Time Weighting Factor = 350/365 = 0.96

4.1.4 Carcinogenic through a Mutagenic Mode of Action — Air, Inhalation

		TR x (AT x LT)		^2)

EF x ET x

C 1 day ^

24 hours
V	J

x [(ED0_2 x IUR x 10) + (ED2_6 x IUR x 3)
+ (ED6_16 x IUR x3) + (EDI6_30 x IUR x 1)]

Where:

SCmu_air = Air Inhalation Screening Concentration, Carcinogenic - Mutagenic Mode of Action (|_ig/m3)

TR = Target risk (1 x 10"6) (unitless)

AT = Averaging time (365 days/year)

LT = Lifetime (70 years)

ED0_2 = Exposure duration (2 years)

££>2-6 = Exposure duration (4 years)

££>616 = Exposure duration (10 years)

££16-30 = Exposure duration (14 years)

EF = Exposure frequency (350 days/year)

ET = Exposure time (24 hours/day)

IUR = Inhalation unit risk (j^ig/m ) 1

Using the exposure assumptions listed above, Equation (32) can be simplified as:

27

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June 2014

9.605x10 7

SC =		(33)

mu—air	V /

1UK

4.1.4.1 Vinyl Chloride - Air, Inhalation

SC	= —	TR

IUR

IUR x EF x ED x ET x (1 day / 24 hours)
(AT x LT)

(34)

Where:

S( = Air Inhalation Screening Concentration, Vinyl Chloride ((.ig/nr1)

TR = Target risk (1 x 10"6)

AT = Averaging time (365 days/year)

LT = Lifetime (70 years)

ED = Exposure duration (30 years)

EF = Exposure frequency (350 days/year)

ET = Exposure time (24 hours/day)

IUR = Inhalation unit risk (j^ig/m ) 1

Using the exposure assumptions listed above, Equation (34) can be simplified as:

7.090 xlO"7

sc	~=—<35)

4.1.4.2 Trichloroethylene - Air, Inhalation

The following three steps are used to calculate an air inhalation cancer screening concentration benchmark
for TCE.

Step 1. A mutagenic screening concentration (SC) is calculated using the kidney IUR and the mutagenic
equation provided below.

=	TR x (AT x LT)	

mu-tce	EfxETx (1 day/24 hows) x [(EDo 2 x jUr^ x W) + (ee>2 6 x jUr^ x 3)

+ (ED6-10 X IURHdney X 3) + ('EDJ6_30 X LURkldney X 1 )\

Where:

SCmu_tce = Air Inhalation Screening Concentration, Carcinogenic-Mutagenic Mode of Action (|_ig/m3)

TR = Target risk (1 x 10"6) (unitless)

AT = Averaging time (365 days/year)

LT = Lifetime (70 years)

EDo_2 = Exposure duration (2 years)

ED2-6 = Exposure duration (4 years)

ED6_16 = Exposure duration (10 years)

ED16_30 = Exposure duration (14 years)

EF = Exposure frequency (350 days/year)

ET = Exposure time (24 hours/day)

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June 2014

lURkidney = Inhalation unit risk, kidney ((.ig/ni')_1

Using the exposure assumptions listed above, Equation (36) can be simplified as:

SCm-air = 9.61 X 10-7/IURkld„ey	(37)

Step 2. A cancer SC is calculated using the non-Hodgkin's lymphoma (NHL) and liver cancer IUR and the
cancer equation provided below.

sc =	TRx(AT xLT)	

EF x ED x ET x (1 day/24 hours) x IURNHL andLlver

Where:



KC

Ljy—c-tce

= Air Inhalation Screening Concentration, Carcinogenic (|_ig/m3)

TR

= Target risk (1 x 10"6) (unitless)

AT

= Averaging time (365 days/year)

LT

= Lifetime (70 years)

ED

= Exposure duration (30 years)

EF

= Exposure frequency (350 days/year)

ET

= Exposure time (24 hours/day)

11 7^ OVjj nver

= Inhalation unit risk, NHL and liver (j^ig/m3)1

Using the exposure assumptions listed above, Equation (38) can be simplified as:

SCc_air = 2.44 x 10"6 / IURnhl andllver	(39)

Step 3. A cumulative result of both the mutagenic and cancer screening concentrations calculated in Steps 1
and 2 above is then generated, and the resulting value reflects both the kidney cancer risk (mutagenic risk
estimate) and the NHL and liver cancer risk.

SC..

VC

V m-air 7

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June 2014

4.1.5 Carcinogenic —Air, Inhalation, Radionuclides

s-aw-¥ad '	/ j J™ A	(47 )

ETx 4-4^ x EF x ED x SF;x IFA,^	V '

. 24 hrj

Where:

!IRA, x

F*£)

SCc.air.rad = Air inhalation screening concentration benchmark - radiochemical (pCi/m3)

S F = Slope factor - inhalation, radiochemical - substance specific (pCi)"1

TR = Target risk (1 x 10"6), unitless

ET = Exposure time - resident (24 hours/day)

EF = Exposure frequency - resident (350 days/year)

ED = Exposure duration - resident (30 years)

IRAC = Inhalation rate - resident child (10 m3/day)

EDC = Exposure duration - resident child (6 years)

EDr-a = Exposure duration - resident adult (24 years)

IRAr_a = Inhalation rate - resident adult (20 m3/day)

IFAr_adj =Age-adjusted inhalation factor (18 m3/day)

Using the exposure assumptions listed above, Equation (42) can be simplified as:

SCc_air_rad = 5.29 x 10"12 / SFj	(43)

4.2 Screening Concentration Benchmarks for the Soil Exposure Pathway

The following equations are used to determine soil ingestion screening concentration benchmarks for the soil
exposure pathway. The benchmarks use exposure parameters and factors that represent RME conditions for
long-term/chronic exposures and are based on the methodology outlined in the EPA's Risk Assessment
Guidance for Superfund, Part B (1991). General equations are provided in Section 4.2.1 (non-carcinogenic
benchmarks) and Section 4.2.2 (carcinogenic benchmarks). Equations that are specific for substances that are
carcinogenic through a mutagenic mode of action, including vinyl chloride and TCE, are provided in Section
4.2.3; these equations are taken from EPA's Handbook for Implementing the Supplemental Cancer Guidance at
Waste and Cleanup Sites. Equations used for radionuclides are provided in Section 4.2.4. When determining soil
ingestion screening concentration benchmarks for arsenic, the SF and RfD are multiplied by a relative
bioavailability adjustment (RBA) factor of 0.6 (EPA Guidance for Evaluating the Oral Bioavailability of Metals
in Soils for Use in Human Health Risk Assessment).

4.2.1 Non-carcinogenic — Soil, Ingestion

SC

THQ xATx EDC x BMC

res-sol-nc-ing

EF X EDr

( 1 ^
RfD

IRS,

10 6 kg

mg

(44)

Where:

SCres_soi_nc_ing = Soil Screening Concentration, Non-Carcinogenic (mg/kg)

30

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June 2014

RfD	= Oral reference dose (in mg/kg-day)

AT	= Averaging time - resident (365 days/year)

BMC	= Body mass - child (=15 kg)

EDC	= Exposure duration - resident child (= 6 years)

EF	= Exposure frequency - resident (= 350 days/year)

IRSC	= Resident soil ingestion rate - child (= 200 mg/day)

THQ	= Target hazard quotient (=1)

Using the exposure assumptions listed above, Equation (44) can be simplified as:

SC

res-sol-nc-ing

= 78214.29 xR/D

(45)

4.2.2 Carcinogenic — Soil, Ingestion

SC

TRxATx LT

res-sol-ca-ing

SF x EF x IFS x

lO^kg
mg

(46)

Where:

SC res_soi_c

IFS

SF

TR

AT

LT

EF

EDC

EDr

IRSa

IRSC

BMa

BMC

,-ing = Soil Screening Concentration, Carcinogenic (mg/kg)

= Soil ingestion rate - resident, age adjusted [=(114 mg-year) / (kg-day)], calculated as:

(

EDc x IRSc
BM„

A

(EDr-EDc)xIRSa
BM„

-- Chronic oral cancer slope factor (mg/kg-day)"1
: Target risk (= 1 x 10"6)

: Averaging time - resident (= 365 days/year)
: Lifetime (=70 years)

: Exposure frequency - resident (= 350 days/year)
: Exposure duration - resident child (= 6 years)
: Exposure duration - resident (= 30 years)
: Resident soil ingestion rate - adult (= 100 mg/day)
: Resident soil ingestion rate - child (= 200 mg/day)
: Body mass - adult (=70 kg)

: Body mass - child (=15 kg)

Using the exposure assumptions listed above, Equation (46) can be simplified as:

SC

res-sol-ca-ing

0.64

~sF

(47)

4.2.3 Carcinogenic through a Mutagenic Mode of Action — Soil, Ingestion

SC

TRxATx LT

res-sol-mu-ing

SFxEFx IFSM x

10~6kg

mg

(48)

31

-------
June 2014

Where:

SC res-sol-

IFSM

.mu-ing = Soil Screening Concentration, Carcinogenic - Mutagenic Mode of Action (mg/kg)
= Mutagenic soil ingestion rate - resident, age adjusted [= (489.5 mg-year) / (kg-day)],
calculated as:

(

EDn

: IRS„ x 10

A

BM

f

ED,

: IRS x 3

A

BM

f

ED.

IRS,.

x\

BM „

(

ED,6_30 x IRSa
BM „

SF	= Chronic oral cancer slope factor (mg/kg-day)"1

TR	= Target risk (= 1 x 10"6)

AT	= Averaging time - resident (= 365 days/year)

LT	= Lifetime (=70 years)

EF	= Exposure frequency - resident (= 350 days/year)

EDq-2	= Exposure duration - resident ages 0-2 (= 2 years)

ED2-6	= Exposure duration - resident ages 2-6 (= 4 years)

ED6_i6	= Exposure duration - resident ages 6-16 (= 10 years)

ED mo	= Exposure duration - resident ages 16-30 (= 14 years)

IRSa	= Resident soil ingestion rate - adult (= 100 mg/day)

IRSC	= Resident soil ingestion rate - child (= 200 mg/day)

BMa	= Body mass - adult (=70 kg)

BMC	= Body mass - child (=15 kg)

Using the exposure assumptions listed above, Equation (48) can be simplified as:

0.149

SC

res-sol-mu-ing

SF

(49)

4.2.3.1 Vinyl Chloride - Soil, Ingestion

SC.,

TR

s-sol-c.

7

SFxEFx IFS x
AT x LT

lO^kg
mg

\ f

SF x IRSC x

BMr

i(r6kg

mg

J.

(50)

_v	y

Where:

SCres_soi_ca_vc4ng = Soil Screening Concentration, Vinyl Chloride (mg/kg)

IFS = Soil ingestion rate - resident, age adjusted [=(114 mg-year) / (kg-day)], calculated as:

(

EDc x IRSc
BM „

\

(EPr - EDC) x IRSa
BM „

SF

TR

AT

LT

EF

EDC

EDr

IRSa

IRSC

= Chronic oral cancer slope factor (mg/kg-day)"1
= Target risk (= 1 x 10"6)

= Averaging time - resident (= 365 days/year)
= Lifetime (=70 years)

= Exposure frequency - resident (= 350 days/year)
= Exposure duration - child (= 6 years)

= Exposure duration - resident (= 30 years)
= Resident soil ingestion rate - adult (= 100 mg/day)
= Resident soil ingestion rate - child (= 200 mg/day)

32

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June 2014

BMa = Body mass - adult (=70 kg)

BMC = Body mass - child (=15 kg)

Using the exposure assumptions listed above, Equation (50) can be simplified as:

SC	=^L	(51)

res-sol-ca-vc-ing	SF

4.2.3.2 Trichloroethylene (TCE) - Soil, Ingestion

The following three steps were used to calculate a soil screening concentration benchmark reflecting exposure
only via ingestion.

Step 1. A mutagenic screening concentration (SC) is calculated using the kidney cancer slope factor and the
mutagenic equation provided below.

SC

TRxATxLT

sol-mu-tce-ing

SF^xEFxIFSMx

10 6 kg

mg

(52)

Where:

SC_soi_mu_tce_ing = Soil Screening Concentration, Mutagenic (mg/kg)

IFSM= Mutagenic soil ingestion rate-resident, age adjusted [=(489.5 mg-year)/(kg-day)], calculated as:

ED,

0-2

: IRS„ x 10



BM

ED

2-6

IRS

BM

ED,

6-16

IRS,,

A (

BM,

ED

16-30

IRS,,

BM„

S1')Mikv
TR
AT
LT

EF
EDo-2
ED2-6
ED 6-16
ED 1 g_3o

IRSa

IRSC
BMa
BMC

= Chronic oral slope factor, kidney (mg/kg-day)"1
= Target risk (= 1 x 10"6)

= Averaging time - resident (= 365 days/year)
= Lifetime (=70 years)

= Exposure frequency - resident (= 350 days/year)
= Exposure duration - resident ages 0-2 (= 2 years)
= Exposure duration - resident ages 2-6 (= 4 years)
= Exposure duration - resident ages 6-16 (=10 years)
= Exposure duration - resident ages 16-30 (= 14 years)
= Resident soil ingestion rate - adult (= 100 mg/day)
= Resident soil ingestion rate - child (= 200 mg/day)
= Body mass - adult (=70 kg)

= Body mass - child (=15 kg)

Using the exposure assumptions listed above, Equation (52) can be simplified as:

SC

0.149

soil-mu—tce-ing

SK

(53)

kidney

33

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June 2014

Step 2. A cancer screening concentration (SC) is calculated using the NHL and liver cancer slope factor and
the cancer equation provided below.

SC

TRxATxLT

sol-ca-tce-ing

SFNHLandLlverxEFxIFSx

10 kg

mg

(54)

Where:

SC.

-sol-ca-tce-ing

= Soil Screening Concentration, Carcinogenic (mg/kg)

Il'S = Soil ingestion rate - resident, age adjusted [= (114 mg-year) / (kg-day)], calculated as:

f

EDc x IRSC
BM „

(EDr-EDc)xIRSa
BM „

SFnhl and uver = Chronic oral cancer slope factor, NHL and liver (mg/kg-day)"1

TR	= Target risk (= 1 x 10"6)

AT	= Averaging time - resident (= 365 days/year)

LT	= Lifetime (=70 years)

EF	= Exposure frequency - resident (= 350 days/year)

EDC	= Exposure duration - child (= 6 years)

EDr	= Exposure duration - resident (= 30 years)

IRSa	= Resident soil ingestion rate - adult (= 100 mg/day)

IRSC	= Resident soil ingestion rate - child (= 200 mg/day)

BMa	= Body mass - adult (=70 kg)

BMC	= Body mass - child (=15 kg)

Using the exposure assumptions listed above, Equation (54) can be simplified as:

SC

0.64

soil-ca-tce—ing

SF,

(55)

NHL and Liver

Step 3. A cumulative result of both the mutagenic and cancer screening concentrations, via oral ingestion,
calculated in Steps 1 and 2 above is then generated and the resulting value reflects both the kidney cancer
risk (mutagenic risk estimate) and the NHL and liver cancer risk.

SC

1

soil - ca- mu-tce-ing

(56)

SC

\ soil-ca-ing J

SC

\ soil-mu-ing J

Substituting the simplified equations provided above for obtaining Step 1 and Step 2 results, the following is an
alternative equation for calculating Step 3 results:

(57)

SC

soil-ca-mu-tce-ing

\.56SFnhl

and Liver

6.71 SFkidney

34

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June 2014

4.2.4 Carcinogenic — Soil, Radionuclides
1) Oral

vr	_	TRx trxX

soll-ca-rad /	s	\\	(58)

(1-e- ' )xSFs xIFSr_adj xEFr x EDr x
V	\1000mgjj

g

Where:

(2RS :y EDs + IRSa x ED, J

ED

SCc_soi_rad	= Soil cancer screening concentration benchmark - radiochemical (pCi/g)

SFs	= Slope factor - soil, radiochemical - substance specific (pCi)"1

IFSr_adj	= Resident soil ingestion factor (mg/ day)

TR	= Target risk (1 x 10"6)

I,	= Time (30 years)

X	= Lamba - substance specific

EF	= Exposure frequency - resident (350 days/year)

ED	= Exposure duration - resident (30 years)

IRSa	= Soil ingestion rate - adult (100 mg/day)

IRSC	= Soil ingestion rate - child (200 mg/day)

EDC	= Exposure duration - resident child (6 years)

EDr_a	= Exposure duration - resident adult (24 years)

Using the exposure assumptions listed above, Equation (58) can be simplified as:

SCc_sol_rad = 2.38 x 10"11 x 1/[(1 - e"3
-------
June 2014

ETro
ETr.j
GSF,
IRSC

Exposure time - resident outdoor (0.073 hr/hr)
Exposure time - resident indoor (0.684 hr/hr)
Gamma shielding factor - indoor (0.4), unitless
Soil ingestion rate - child (200 mg/day)

Using the exposure assumptions listed above, Equation (60) can be simplified as:

SC

3.01x10 6 xX

(61)

ext—rad

[(1— e~3
-------
June 2014

4.3.2 Carcinogenic — Ground Water and Drinking Water, Ingestion

FRxAFxLFxlOOO jug/mg

SC

water-ca-ing

SFxEFxIFW

(64)

Where:

water-ca•

1FW --

SF

TR

AT

LT

EF

EDC

EDr

IRWa

IRWC

BMa

BMn

4ng = Ground Water/Drinking Water Screening Concentration, Carcinogenic (j^ig/L)

= Drinking water ingestion rate - Resident, adjusted [= (1.086 L-year) / (kg-day)], calculated as:

fEDC x IRWC
BM„

cEDr-EDc)xIRWa
BM „

-¦ Chronic oral slope factor (mg/kg-day)"1
: Target risk (= 1 x 10"6)

: Averaging time - resident (= 365 days/year)

: Lifetime (=70 years)

: Exposure frequency - resident (= 350 days/year)
: Exposure duration - child (= 6 years)

: Exposure duration - resident (= 30 years)

: Drinking water ingestion rate - resident adult (= 2 L/day)
: Drinking water ingestion rate - resident child (= 1 L/day)
: Body mass - adult (=70 kg)

: Body mass - child (=15 kg)

Using the exposure assumptions listed above, Equation (64) can be simplified as:

0.0672

SC

water-ca-ing

SF

(65)

4.3.3 Carcinogenic through a Mutagenic Mode of Action — Ground Water and Drinking Water,
Ingestion

SC

water-mu-ing

FRxAFxLFxlOOO jug/mg
SFxEFxIFWM

(66)

Where:
SC

water-mu-ing

= Ground Water/Drinking Water Screening Concentration, Mutagenic (|_ig/L)

IFWM = Mutagenic Drinking Water ingestion rate - resident, age adjusted [= (3.39 L-year) / (kg-day)],
calculated as:

(

ED0_2 xIRWcx 10
BM„



(

ED2_6 x IRWC x 3
BM„



(

ED6_l6 x IRWa x 3

BM „

^ (EDl6_mxIRWaxC
BM„

SF
TR
AT
LT

EF
ED0
ED2-6
ED 6-16

'0-2

= Chronic oral slope factor (mg/kg-day)"1
= Target risk (= 1 x 10"6)

= Averaging time - resident (= 365 days/year)
= Lifetime (=70 years)

= Exposure frequency - resident (= 350 days/year)
= Exposure duration - resident ages 0-2 (= 2 years)
= Exposure duration - resident ages 2-6 (= 4 years)
= Exposure duration - resident ages 6-16 (= 10 years)

37

-------
June 2014

ED16_30 = Exposure duration - resident ages 16-30 (= 14 years)

IRWa = Drinking water ingestion rate - resident adult (= 2 L/day)

IRWC = Drinking water ingestion rate - resident child (= 1 L/day)
BMa = Body mass - adult (=70 kg)

BMC = Body mass - child (=15 kg)

Using the exposure assumptions listed above, Equation (66) can be simplified as:

0.0215

sc

water-mu-ing

SF

(67)

4.3.3.1 Vinyl Chloride - Ground Water and Drinking Water, Ingestion

TR

SC

res-water-ca-vc-ing

y

SFxEFx IFW x

mg



1000 jug

ATxLT

(

SF xIRWc x

mg

1000 jug

BMr

Where:
SC,

(68)

res-water-nc-ing

= Ground Water/Drinking Water Screening Concentration, Vinyl Chloride ((.ig/L)

IFW = Drinking water ingestion rate - Resident, adjusted [= (1.086 L-year) / (kg-day)], calculated as:

EDC x IRWC
RM„

(EDr - EDC )x IRWa
BM „

SF

TR

AT

LT

EF

EDC

EDr

IRWa

IRWC

BMa

BMC

= Chronic oral slope factor (mg/kg-day)"1
= Target risk (= 1 x 10"6)

= Averaging time - resident (= 365 days/year)

= Lifetime (=70 years)

= Exposure frequency - resident (= 350 days/year)
= Exposure duration -child (= 6 years)

= Exposure duration - resident (= 30 years)

= Drinking water ingestion rate - resident adult (= 2 L/day)
= Drinking water ingestion rate - resident child (= 1 L/day)
= Body mass - adult (=70 kg)

= Body mass - child (=15 kg)

Using the exposure assumptions listed above, Equation (68) can be simplified as:

0.0123

SC

res-water-ca-vc-ing

SF

(69)

4.3.3.2 Trichloroethylene (TCE) - Ground Water and Drinking Water, Ingestion

The following three steps were used to calculate a drinking water screening concentration reflecting exposure
only via ingestion.

Step 1. A mutagenic screening concentration (SC) is calculated using the kidney cancer slope factor and the

38

-------
June 2014

equation provided below.

_ TRxAT x LT xlOOO

water-mu-tce-ing	x EF X IFWM

Where:

SCwater_mu_tce_ing = Drinking Water Screening Concentration, Mutagenic Mode of Action (j^ig/L)

IFWM = Mutagenic Drinking Water ingestion rate - resident, age adjusted [= (3.39 L-year) / (kg-day)],
calculated as:

f ED0_2 x IRWC x 10^
BM„

( I7n V 7Z>W ^-3 A ( 17n V 7Z>W ^-3 A

ED2_6 / I RW / 3
BM„

ED6_l6 / I RW.. x 3
BM „

(EDl6_30xIRWax\>
BM „

SFiadney	= Chronic oral cancer slope factor, kidney (mg/kg-day)"1

TR	= Target risk (= 1 x 10"6)

AT	= Averaging time - resident (= 365 days/year)

LT	= Lifetime (=70 years)

EF	= Exposure frequency - resident (= 350 days/year)

EDo_2	= Exposure duration - resident ages 0-2 (= 2 years)

ED2-6	= Exposure duration - resident ages 2-6 (= 4 years)

ED6_i6	= Exposure duration - resident ages 6-16 (= 10 years)

ED16_30 = Exposure duration - resident ages 16-30 (= 14 years)

IRWa	= Drinking water ingestion rate - resident adult (= 2 L/day)

IRWC	= Drinking water ingestion rate - resident child (= 1 L/day)

BMa	= Body mass - adult (=70 kg)

BMC	= Body mass - child (=15 kg)

Using the exposure assumptions listed above, Equation (70) can be simplified as:

SCwater-mu-tce-ing 0.0215/ SFkidney	(71)

Step 2. A cancer SC is calculated using the NHL and liver cancer slope factor and equation provided below.

= TRxATxLTx 1000 ng/mg

water-ca-tce-ing	7^ x TfW

NHL and Liver A Ejir A ir VV

Where:

KC

^ water-ca-tce-i ng

1FW

SIW,,,. and liver

TR
AT
LT
EF

= Drinking Water Screening Concentration, Carcinogenic (|_ig/L)

= Drinking water ingestion rate - Resident, adjusted [= (1.086 L-year) / (kg-day)],
calculated as:

(

EDC x IRWC
BM„

\

(EDr-EDc)xIRWa
BM„

= Chronic oral cancer slope factor, NHL and liver (mg/kg-day)"1
= Target risk (= 1 x 10"6)

= Averaging time - resident (= 365 days/year)

= Lifetime (=70 years)

= Exposure frequency - resident (= 350 days/year)

39

-------
June 2014

EDC	= Exposure duration - child (= 6 years)

EDr	= Exposure duration - resident (30 years)

IRWa	= Drinking water ingestion rate - resident adult (= 2 L/day)

IRWC	= Drinking water ingestion rate - resident child (= 1 L/day)

BMa	= Body mass - adult (=70 kg)

BMC	= Body mass - child (=15 kg)

Using the exposure assumptions listed above, Equation (72) can be simplified as:

SCwater-ca-tce-ing

0.067 / SFnhl and liver

(73)

Step 3. A cumulative result of both the oral mutagenic and oral cancer screening concentrations calculated
in Steps 1 and 2 above is then generated and the resulting value reflects both the kidney cancer risk
(mutagenic risk estimate) and NHL and liver cancer risk.

SC

water-ca-mu-tce-ing

l

\ f

- +

SC

water-ca-ing J

SC

water-mu-ing J

(74)

Substituting the simplified equations provided above for obtaining Step 1 and Step 2 results, the following is an
alternative to Equation 74 for calculating Step 3 results:

^	

water-ca-mu-tce-ing ~ 1 . _ CJ(75)
14 9 SF^ and Liver + 46 5 SFIadney

4.3.4 Carcinogenic — Ground Water and Drinking Water, Radionuclides

SC	=	—		(76)

c-^ter-rad ^ ^ ^ ^ XIFW^

Where:

_ _ _ EDe x/fllC. +

~~Yd,

SCc_water_rad = Drinking water screening concentration benchmark - radiochemical (pCi/L)

SFW = Slope factor - drinking water - substance specific (pCi)"1

TR = Target risk (1 x 10"6), unitless

EF = Exposure frequency - resident (350 days/year)

ED = Exposure duration - resident (30 years)

IRWa = Water ingestion rate - adult (2 L/day)

IRWC = Water ingestion rate - child (1 L/day)

40

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June 2014

EDC = Exposure duration - resident child (6 years)

EDr_a = Exposure duration - resident adult (24 years)

IFW,.^ = Age-adjustcd water ingestion rate (1.8 L/day)

Using the exposure assumptions listed above, Equation (76) can be simplified as:

SCc.water.rad = 5.29 x 10-n/SFw	(77)

4.4 Screening Concentration Benchmarks for the Human Food Chain Pathway

The following equations are used to determine screening concentration benchmarks for the human food chain
exposure pathway. The benchmarks use exposure parameters and factors that represent RME conditions for
long-term/chronic exposures and are based on the methodology outlined in the EPA's Risk Assessment
Guidance for Superfund, Part B (1991). General equations are provided in Section 4.4.1 (non-carcinogenic
benchmarks) and Section 4.4.2 (carcinogenic benchmarks). Equations used for radionuclides are provided in
Section 4.4.3.

4.4.1 Non-carcinogenic — Human Food Chain, Fish Ingestion

THQ x AT x EDr x BMa

res-fsh-nc-ing	f	\	7/1-67

1 ' /SFx^i

RfD

mg

EF x ED
Where:

SCres_fsh_nc_ing = Human Food Chain Screening Concentration, Fish Ingestion, Non-Carcinogenic (mg/kg)

RfD = Oral reference dose (in mg/kg-day)

AT = Averaging time - resident (365 days/year)

BMa = Body mass - adult (=70 kg)

EDr = Exposure duration - resident (= 30 years)

EF = Exposure frequency - resident (= 350 days/year)

IRF = Fish ingestion rate (= 5.4 x 104 mg / day)

THQ = Target hazard quotient (=1)

Using the exposure assumptions listed above, Equation (78) can be simplified as:

SCres_fsh_nc_mg = 1350 x RfD	(79)

4.4.2 Carcinogenic — Human Food Chain, Fish Ingestion

TRxAT xLT xBMa

SCres-fsh-ca-mg ~	... 6 ,	(80)

EF x EDr x SFx IRF x	^

mg

Where:

SCres_fsh_ca4ng = Human Food Chain Screening Concentration, Fish Ingestion, Carcinogenic (mg/kg)
SF = Chronic oral cancer slope factor (mg/kg-day)"1
TR = Target risk (= 1 x 10"6)

41

-------
June 2014

AT = Averaging time - resident (= 365 days/year)

LT = Lifetime (=70 years)

BMa = Body mass - adult (=70 kg)

EF = Exposure frequency - resident (= 350 days/year)

ED = Exposure duration - resident (= 30 years)

IRF = Fish ingestion rate (= 5.4 x 104 mg / day)

Using the exposure assumptions listed above, Equation (80) can be simplified as:

0.00315

res- fsh—ca-ing	^

(81)

4.4.3 Carcinogenic — Human Food Chain, Fish Ingestion, Radionuclides

TR

SCc-fish-rad =	~	(82)

EF x ED x SFf x IRF x	^	

1	1000 mg

Where:

SC c-fish-rad ~ Human Food Chain Screening Concentration, Fish Ingestion - Radiochemical,

Carcinogenic (pCi/g)

SFf= Slope factor - drinking water - substance specific (pCi)"1
TR = Target risk (1 x 10"6), unitless
EF = Exposure frequency - resident (350 days/year)

ED = Exposure duration - resident (30 years)

EDC = Exposure duration - resident child (6 years)

EDr_a = Exposure duration - resident adult (24 years)

IRF= Fish ingestion rate (= 5.4 x 104 mg / day)

Using the exposure assumptions listed above, Equation (82) can be simplified as:

SC c.flsh.rad= 1.76 x 10"12 / SFf	(83)

42

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June 2014

5.0 SCDM DATA REPORTING and APPENDICES

5.1	Data Reporting

Data are collected from the references identified in Section 2 of this document. The data are collected exactly as
provided in the references and compiled into a SCDM data management tool. Once in the tool, converted values
are generated to reflect the SCDM standard units for use in calculations, while the original values remain
unchanged for transparency. Collected data and calculated results are maintained in the tool and are not rounded,
truncated or otherwise adjusted except for purposes of reporting in SCDM Appendices A, BI and BII.

The following rules are applied for purposes of reporting SCDM data in Appendices A, BI and BII:

•	Substance characterization data and data that serve as inputs to benchmark and factor value formulas are
truncated and reported to two significant figures.

•	Screening concentration benchmarks are truncated to the number of significant figures contained in the data
input variable (i.e., RfD, RfC, IUR, or cancer slope factor) used to determine each benchmark. For example,
a screening concentration benchmark determined using a cancer slope factor of 2.81E-8, will be reported to
three significant figures.

•	Factor values will be reported to the number of significant figures needed to support decision making as
described at 40 CFR Part 300 Appendix A and 55 FR 51583.

5.2	SCDM Appendices

Appendix A of SCDM contains selected data, HRS factor values and benchmarks for each hazardous substance
in SCDM (the "SCDM page reports"). Information is provided in a two-page report for each substance. Data
selected for SCDM are on the first page; factor values and benchmarks are on the second page.

Figure 1 presents an example of the header that appears on the Appendix A report. The header contains the date
the report was created, the substance name and synonym, and the Chemical Abstract Survey Registration
Number (CAS Number) for the substance.

SUPERFUND CHEMICAL DATA MATRIX

SCDM Data Version:	Publication Date:

Chemical: Acenapthene CAS Number: 000083-32-9
	Figure 1. Page Heading	

For each substance, the first page contains all of the selected chemical data, the data units, and an acronym
describing the reference source of the information. Data are divided into six functional groups: toxicity,
persistence, physical characteristics, mobility, bioaccumulation and other data. The "SCDM Data Version" date
in the upper left-hand corner indicates the date of data collection; the "Publication Date" indicates the date the
report was generated and posted on the SCDM website at
http://www.epa.gov/superfund/sites/npl/hrsres/tools/scdm.htm.

The toxicity section (Figure 2) contains the acute, chronic, and carcinogenicity data that were compiled using
the methodology described in Sections 2.2 and 2.6, and used to derive toxicity and ecotoxicity factor values.

43

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June 2014

TOXICITY

Parameter

Value Unit

Source

Oral RfD:

6.0E-2 mg/kg/day

IRIS

Tnhal RfD:

mg/kg/day



RfC:

mg/mA3



Oral Slope:

(mg/kg/day )A-1



Oral Wt-of-Evid:





IUR:

(mg/kg/day )A-1



IUR Wt-of-Evid:





Oral ED 10:

mg/kg/day



Oral ED 10 Wgt:





Oral ED 10 Wgt:

mg/kg/day



InhalEDIO Wgt:





Oral LD50:

mg/kg



Dermal LD50:

mg/kg



Gas Inhal LC50:

ppm



Dust Inhal LC50:

mg/L



ACUTE





Fresh CMC:

(ig/L



Salt CMC:

(ig/L



CHRONIC





Fresh CCC:

(ig/L



Salt CCC:

(ig/L



Fresh Ecol LC50:

5.0E+1

ECOTOX

SaltEcolLC50:

1.4E+2

ECOTOX

Figure 2. Toxicity Section

The top half of this section contains the data used to determine the HTF value: reference dose (oral and
inhalation), cancer slope factor (oral and inhalation unit risk [IUR]), ED10 (oral and inhalation), LD50 (oral and
dermal) and LC50 (gas and dust inhalation). The bottom half of this section contains the data used to determine
an ecotoxicity factor value: acute and chronic water quality criteria, CMC and CCC, for fresh and salt water as
well as fresh and salt water LC50 values. Blank entries indicate that no value was found using the procedures and
references specified.

The persistence section (Figure 3) contains the surface water persistence data compiled using the methodology
described in Section 2.4. Surface water persistence factors can also be determined using the logarithm of the n-
octanol/water partition coefficient (Log Kowor Log P, Section 2.3) if, as specified in the HRS, this gives a
higher factor value than the half-lives (or a default, if applicable).

44

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June 2014

PERSISTENCE

Parameter

Value

Unit

Source

LAKE - Halflives







Hydrolysis:



days



Volatility:

1.1E+2

days

THOMAS

Photolysis:

2.5E+0

days

HEDR

Biodeg:

1.0E+2

days

HEDR

Radio:



days



RIVER - Halflives







Hydrolysis:



days



Volatility:

1.3E+0

days

THOMAS

Photolysis:

2.5E+0

days

HEDR

Biodeg:

1.0E+2

days

HEDR

Radio:



days



Log Kow:

3.9E+0



EPI

Figure 3. Persistence Section

The physical characteristics section (Figure 4) contains logical "yes/no" flags that classify the substance. The
"metal contain" flag indicates that the hazardous substance is a metal or metalloid and is used to determine
ground water mobility and surface water persistence factors. The "organic" and "inorganic" flags are used to
determine ground water mobility and bioaccumulation. The "radionuclide" flag is used to determine the HTF,
the ecosystem toxicity factor and the surface water persistence factor. The radioactive element flag ("rad.
element") is used to determine whether or not the HRS factors and benchmarks (second page) are printed. The
gas and particulate flags are used to determine mobility and likelihood of release for the air pathway. MW is
used to determine volatilization half-life.

PHYSICAL CHARACTERISTICS

Parameter

Value



Metal Contain:

No



Organic:

Yes



Gas:

Yes



Particulate:

Yes



Radionuclide:

No



Rad. Element:

No



Molecular Weight:

1.5E+2



Density:

1.2E+0 g/mL @20.00

C

Figure 4. Physical Characteristics Section

The mobility section (Figure 5) contains the air and ground water mobility data compiled using the methodology
described in Section 2.3. Vapor pressure and HLC are used to determine gas migration potential and gas
mobility factors. HLC is also used to calculate the volatilization half-life. Water solubility and the soil/water
distribution coefficient are used to determine the ground water mobility factor. Substance-specific water
solubility is used for nonmetal and non-metalloid substances, whereas for metal-containing substances, the
solubility value is the geometric mean of the available water solubilities for inorganic compounds containing the
hazardous substance.

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MOBILITY

Parameter

Value

Unit

Source

Vapor Press:

2.2E-3

Torr

PHYSPROP

Henry's Law:

1.8E-4

atm-m3/mol

PHYSPROP

Water Solub:

3.9E+0

mg/L

PHYSPROP

Distrib Coef:

7.6E+2

ml/g

CALC

Geo Mean Sol:



mg/L



Figure 5. Mobility Section

The bioaccumulation section (Figure 6) contains the human food chain and environmental bioaccumulation
potential factor data compiled using the methodology described in Section 2.5. BCFs are collected for fresh and
saltwater for the human food chain and environmental threats. Log Kowor water solubility is used to establish
bioaccumulation potential when a BCF is not available.

BIOACCUMULATION

Parameter Value Unit

Source

FOOD CHAIN



Fresh BCF: 3.9E+2

ECOTOX

Salt BCF:



ENVIRONMENTAL



Fresh BCF: 3.9E+2

ECOTOX

Salt BCF:



LogKow: 3.9E+0

EPI

Water Solub: 3.9E+0

PHYSPROP

Geo Mean Sol: mg/L



Figure 6. Bioaccumulation Section

The section labeled "other data" (Figure 7) contains values for melting points and boiling points (°C) along with
the associated vapor pressure (Torr), if applicable. The chemical formula is also listed here.

	OTHER DATA

Melting Point:	9.3E+1 C

Boiling Point:	2.8E+2 C

Formula	C12 H10	

	Figure 7. Other Data

The class information section (Figure 8) lists parent substances for three data substitution classes: toxicity,
ground water mobility and other data. The toxicity class includes all toxicity and benchmark data used to
determine human or ecotoxicity factor values. The ground water mobility class includes water solubility, Kd. and
geometric mean water solubility. The "other" class includes hydrolysis, biodegradation, photolysis and
volatilization half-lives, as well as BCFs and Log KQW. This section may also list other class-parent chemical
substitutions for specific data elements.

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Currently, only two groups of substances inherit data from a parent substance: metals and radioactive
substances. Generally, metal-containing substances inherit data for the ground water mobility class with the
elemental metal as the class parent. Radioactive isotopes may inherit data from their primary radioactive
element for the ground water mobility and "other" classes.

	CLASS INFORMATION

Class	Parent Substance

Figure 8. Class Information Section

The second page for each substance is divided into top and bottom sections that contain factor values (Figure 9)
and benchmarks (Figure 10) required by the HRS. SCDM determines factor values using HRS methodologies
from selected data on the first page of the SCDM page report. The factor values are presented by exposure
pathway: air, ground water, soil and surface water. The surface water pathway is further subdivided by threat:
drinking water, human food chain, and environmental. The toxicity factor value represents human toxicity and is
the same for all pathways. The air pathway gas migration factor value is used to determine likelihood of release.
The surface water environmental toxicity factor values are based on fresh and saltwater ecosystem toxicity data,
and the surface water persistence factor values are based on BCFs for all aquatic species. The surface water
human food chain factor values are based on human toxicity and BCFs for only those aquatic species consumed
by humans. For radioactive substances, human toxicity, ecosystem toxicity and surface water persistence factor
values are determined as specified in Section 7 of the HRS.

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ASSIGNED FACTOR VALUES

AIR PATHWAY

GROUND WATER PATHWAY

SOIL EXPOSURE PATHWAY

Parameter Value

Parameter

Value

Parameter

Value

Toxicity: 10

Toxicity:

10

Toxicity:

10

Gas Mobility: 0.2000

Water Solub:

3.9E+0





Gas Migration: 11

Distrib:

7.6E+2







Geo Mean Sol:









Liquid









Karst:

1.0E+0







Non Karst:

1.0E-2







Non Liq.









Karst:

2.0E-1







Non Karst:

2.0E-3





SURFACE WATER PATHWAY

DRINKING WATER

HUMAN FOOD CHAIN

ENVIRONMENTAL

Parameter Value

Parameter

Value

Parameter

Value

Toxicity: 10

Toxicity:

10

Fresh Tox:

10000







Salt Tox:

1000

Persistence

Persistence



Persistence



River: 0.4000

River:

0.4000

River:

0.4000

Lake: 0.4000

Lake:

0.4000

Lake:

0.4000



Bioaccumulation



Bioaccumulation





Fresh:

500.0

Fresh:

500.0



Salt:

500.0

Salt:

500.0

Figure 9. Assigned Factor Values Section

The benchmarks (Figure 10), like the factor values, are presented by pathway: air, ground water, soil exposure,
and surface water. The surface water pathway is further subdivided by threat: drinking water, human food chain,
and environmental. For HRS scoring, actual sample contaminant concentrations for a particular medium are
compared to these benchmark concentrations to determine if the target will be scored as subject to Level I or
Level II concentrations.

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BENCHMARKS

GROUND WATER SOIL EXPOSURE





AIR PATHWAY PATHWAY PATHWAY

RADIONUCLIDE

Parameter Value Unit Parameter Value Unit Parameter

Value Unit

Parameter

Value Unit

NAAQS/ MCL/







NESHAPS: ng/m3 MCLG: mg/L Cancer Risk

mg/kg

MCL:

pCi/L

Non Cancer







Cancer Risk lig/m3 Cancer Risk mg/L Risk

4.7E+3 mg/kg

UMTRCA:

pCi/kg

Non Cancer Non Cancer



CANCER



Risk lig/m3 Risk 9.4E-1 mg/L



RISK







Air:

pCI/m3





DW:

pCI/L





FC:

pCi/kg





Soil Ing:

pCi/kg





Soil GAM:

pCi/kg

SURFACE WATER PATHWAY

DRINKING WATER HUMAN FOOD CHAIN

ENVIRONMENTAL

Parameter Value Unit Parameter Value Unit

Parameter

Value

Unit

MCL/MCLG: mg/L FDAAL: ppm

ACUTE



mg/kg

Cancer Risk mg/L Cancer Risk mg/kg

Fresh CMC



mg/kg

Non Cancer







Risk 9.4E-1 mg/L Non Cancer Risk 8.1E+1 mg/kg

Salt CMC:







CHRONIC







Fresh CCC



Hg/L



Salt CCC:



Hg/L

Figure 10. Benchmarks Section

Appendix B is divided into two sections, Appendix B-I and B-II. Appendix B-I contains all of the factor values
by exposure pathway. Factor values for non-radionuclide substances are listed first and are followed by a listing
of factor values for radionuclides. Appendix B-II presents all the screening concentration benchmarks by
exposure pathway. Benchmarks are provided for the drinking water/groundwater and surface water exposure
pathways, followed by the air and soil exposure pathways. Benchmarks for non-radionuclide substances are
provided first, followed by benchmarks for the radionuclides. Appendix C contains a cross-reference index of
hazardous substance names, synonyms and CAS Numbers for substances in SCDM.

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