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

December 2015

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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	3

2.1.4	Substances with Unique Value Selection	4

2.1.5	Substances with Unique Identifiers	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	13

2.5.1	Bioconcentration	13

2.5.2	Octanol/Water Partition Coefficient (Log Kow)	14

2.5.3	Water Solubility	15

2.6	Ecotoxicity Parameters	15

2.6.1	Acute and Chronic Freshwater and Saltwater Criteria - CCC, CMC	15

2.6.2	LC50 - Freshwater, Saltwater	15

2.7	Regulatory Benchmarks	16

2.7.1	National Ambient Air Quality Standards (NAAQS)	16

2.7.2	National Emissions Standards for Hazardous Air Pollutants (NESHAPs)	16

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	17

2.7.6	Uranium Mill Tailings Radiation Control Act Standards (UMTRCA)	17

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2.8 Physical Properties	17

2.8.1	Chemical Formula, Boiling Point and Melting Point	17

2.8.2	Molecular Weight	18

2.8.3	Density	19

3.0 CALCULATION OF INTERIM VALUES	20

3.1	RfC to RfDinhai	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	Photolysis Half-Life	21

3.5	Volatilization Half-Life	21

3.5.1	Volatilization Half-Life for Rivers, Oceans, Coastal Tidal Waters and the Great Lakes... 23

3.5.2	Volatilization Half-Life for Lakes	23

3.6	Overall Half-Lives	24

3.6.1	Overall Half-Lives for Non-radionuclides	24

3.6.2	Overall Half-Lives for Radionuclides	24

3.7	Soil Water Distribution Coefficient (Kd); Soil Organic/Carbon Partition Coefficients
(Koc)	25

3.8	Water solubility for metals	26

4.0 SCREENING CONCENTRATION BENCHMARKS	27

4.1	Screening Concentration Benchmarks for the Air Migration Pathway	27

4.1.1	Non-carcinogenic - Air, Inhalation	27

4.1.2	Carcinogenic -Air, Inhalation	27

4.1.3	Carcinogenic - Air, Inhalation - Asbestos	28

4.1.4	Carcinogenic through a Mutagenic Mode of Action - Air, Inhalation	28

4.1.5	Carcinogenic - Air, Inhalation, Radionuclides	31

4.2	Screening Concentration Benchmarks for the Soil Exposure Pathway	31

4.2.1	Non-carcinogenic - Soil, Ingestion	31

4.2.2	Carcinogenic - Soil, Ingestion	32

4.2.3	Carcinogenic through a Mutagenic Mode of Action - Soil, Ingestion	32

4.2.4	Carcinogenic - Soil, Radionuclides	36

4.3	Screening Concentration Benchmarks for Ground Water and Drinking Water	37

4.3.1	Non-carcinogenic - Ground Water and Drinking Water, Ingestion	37

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	38

4.3.4	Carcinogenic - Ground Water and Drinking Water, Radionuclides	41

4.4	Screening Concentration Benchmarks for the Human Food Chain	42

4.4.1	Non-carcinogenic - Human Food Chain, Fish Ingestion	42

4.4.2	Carcinogenic - Human Food Chain, Fish Ingestion	42

4.4.3	Carcinogenic - Human Food Chain, Fish Ingestion, Radionuclides	43

5.0 SCDM DATA REPORTING and WEB QUERY	44

5.1	Data Reporting	44

5.2	SCDM Web Query	44

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APPENDICES

Appendix A Synonyms List

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LIST OF FIGURES

Figure 1. SCDM Web Query Report Heading	44

Figure 2. Toxicity Table	45

Figure 3. Persistence Table	46

Figure 4. Mobility Table	47

Figure 5. Bioaccumulation Table	47

Figure 6. Physical Characteristics Table	48

Figure 7. Other Data Table	48

Figure 8. Class Information Table	48

Figure 9. Ground Water Pathway Factor Values Table	49

Figure 10. Surface Water Pathway Factor Values Table	50

Figure 11. Soil Pathway Factor Values Table	50

Figure 12. Air Pathway Factor Values Table	50

Figure 13. Ground Water Pathway Benchmarks Table	51

Figure 14. Surface Water Pathway Benchmarks Table	51

Figure 15. Soil Exposure Pathway Benchmarks Table	52

Figure 16. Air Pathway Benchmarks Table	52

Figure 17. Radionuclide Benchmarks Table	52

LIST OF TABLES

Table 1. Examples of Human Food Chain Aquatic Organisms	14

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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

HSDB	Hazardous Substance Data Bank

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

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RBA

Relative Bioavailability Adjustment

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

[December 2015]

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 December 2015. 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, PartF: 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 Web Query) describes how SCDM data, HRS
factor values, and screening concentration benchmarks are presented.

Data inputs, factor values and benchmarks are listed, by substance and Chemical Abstract Survey Registry
Number (CASRN), in the SCDM Web Query (http://www.epa.gov/superfund/superfund-chemical-data-matrix-
scdm-querv). Appendix A 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 2.8 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.

The references listed throughout Section 2.2 of this methodology document were last accessed during August -
November 2012, in preparation for a comprehensive update to SCDM, which was published in January 2014. Any
changes or additions since then are noted in the SCDM Change Control and Errata Sheet.

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:

•	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.

•	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.

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

•	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

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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.

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.

•	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 Polycyclic Aromatic Hydrocarbons (EPA/600/R-93/089), July 1993.

•	Polychlorinated dibenzo-dioxins and fiirans - 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 fiirans 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.

•	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.

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 (Kd). 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.

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2.1.4	Substances with Unique Value Selection

•	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 value of 1,000, as stated in the HRS.

•	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.

•	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 2 L/day ingestion.

•	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)].

•	Mercuric chloride - SCDM assigns an RfC for mercuric chloride using the following molecular weight
conversion of the RfC assigned to mercury: RfC (mercuric chloride) = RfC (elemental mercury) x [molecular
weight (mercuric chloride) / molecular weight (elemental mercury)].

•	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)].

•	Vanadium - SCDM assigns an RfD for vanadium using the following molecular weight conversion of the
RfD available for vanadium pentoxide: RfD (vanadium) = RfD (vanadium pentoxide) x [molecular weight
(vanadium) / molecular weight (vanadium pentoxide)].

2.1.5	Substances with Unique Identifiers

There is no CASRN specific to uranium 238 (+D) (radionuclide). Therefore, the EPA identification number of
E1734789 is used in its place. Information regarding EPA identification numbers may be found from the EPA
Substance Registry Service (SRS, accessible online at

http: //ofmpub.epa.gov/sor internet/registrv/substreg/home/overvie w/home.do).

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, LD50 and LC50) and carcinogenic data (IUR, SF and ED10) 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://cpa-prgs.ornl.gov/radionuclides/download.html.

• U.S. EPA. Health Effects Assessment Summary Tables {HEAST). Office of Research and Development/Office
of Emergency and Remedial Response, Washington, DC. http://www.epa.gov/sites/production/files/2Q15-
02/documents/heast2 table 4-d2 0401.pdf.

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.

• 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.

• 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)

• 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.

• PPRTV Appendix Screening Toxicity Values, http ://hhpprtv.ornl.gov/quickview/pprtv papers.php.

• 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/.

ATSDR provides MRLs for acute (1 - 14 days), intermediate (>14 - 364 days), and chronic (365 days and longer)
exposure durations. SCDM does not use MRLs that are based on acute exposure. Similarly, PPRTV, PPRTV
Appendix, and HEAST provide RfD and RfC values (or PPRTV Appendix screening levels) for chronic and
subchronic exposure durations. During SCDM data collection, preference is given to values that are based on
chronic exposure. SCDM may use intermediate MRLs or subchronic RfDs or RfCs only if no chronic value is
available from any reference in the above hierarchy.

Where intermediate MRLs are used in SCDM, the reference provided in the SCDM Web Query report is
"ATSDR-Int." Where subchronic RfDs or RfCs from PPRTV or HEAST, or subchronic PPRTV Appendix
screening levels, are used in SCDM, the reference provided in the SCDM Web Query report is "PPRTV-Sub,"
"HEAST-Sub" or "PPRTV_APP-Sub."

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

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

• 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.

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

• 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/.

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/tlv-
bei-guidelines/policies-procedures-presentations/overview.

• 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. Values that are included in EPA ED10 are provided as potency factors; the
reciprocal of these potency factors are used as ED10 values 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.srcinc.com/what-
we-do/environmental/scientific-databases .html.

• 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/tsca-screening-tools/epi-suitetm-estimation-program-interface.

• 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.srcinc.com/what-
we-do/environmental/scientific-databases .html.

• 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.srcinc.com/what-
we-do/environmental/scientific-databases .html.

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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/tsca-
screening-tools/epi-suitetm-estimation-program-interface.

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.srcinc.com/what-
we-do/environmental/scientific-databases .html.

• 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. srcinc. com/what-we -do/environmental/scientific-databases .html.

• 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/tsca-screening-tools/epi-suitetm-estimation-program-interface.

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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:

• 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. srcinc. com/what-we -do/environmental/scientific-databases .html.

• 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 3.8 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
hazardous substances that are available to migrate from sources at the site to ground water are evaluated for

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ground water mobility.

For organic substances, SCDM calculates the Kd according to HRS Section 3.2.1.2 (Mobility) and the
relationship of Kd = Koc x fs (see Section 3.7 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/tsca-screening-
tools/epi-suitetm-estimation-program-interface.

• 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/soil-screening-guidance.

• 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/soil-screening-guidance.

• Estimated as described in Section 3.7 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 3.7 (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/soil-screening-guidance.

• 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 3.7 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:

• 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.

• Hazardous Substances Data Bank (HSDB). U.S. National Library of Medicine. Bethesda, MD.
http: //toxnet .nlm .nih. gov/ne wtoxnet/hsdb .htm.

• EPI Suite™ (estimated values, HYDROWIN hydrolysis half-life estimates and BioHCwin biodegradation
half-life estimates; does not apply to photolysis 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/tsca-screening-tools/epi-suitetm-estimation-program-interface.

For collection of hydrolysis and biodegradation half-lives, SCDM uses aqueous half-life values. Only aerobic
biodegradation half-lives are collected. If values are obtained from HEDR, SCDM uses only values listed as
"first-order." If multiple values are provided from a given reference, the highest value is used.

For photolysis half-life values collected from HEDR and HSDB, both direct photolysis and indirect photolysis (or
photooxidation) half-lives are collected, if available. If only a direct or indirect photolysis value is available, that
value is used as the SCDM final photolysis half-life. If both direct and indirect photolysis values are available
from a given reference, a final photolysis half-life is calculated as described in Section 3.4 of this methodology
document. For photolysis half-lives collected from HSDB, if the photolysis mechanism (direct or indirect) is
unspecified, the value is used to determine a final photolysis half-life only if no direct and/or indirect photolysis
half-life is available.

If the reference from which half-lives are collected contains half-lives that apply specifically and separately to
rivers and lakes, the values are used for the specified water body in SCDM. If different values for each water body
type are not available, the half-life value collected is applied to both rivers and lakes.

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 3.5 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:

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• U.S. EPA. Health Effects Assessment Summary Tables (HEAST). Office of Research and Development/Office
of Emergency and Remedial Response, Washington, DC. http://www .epa.gov/sitcs/production/filcs/2015-
02/documents/heast2 table 4-d2 0401.pdf.

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

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 CFR Part 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
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/chemical-research/ecotoxicologv-database.

• Versar, Inc. 1990. Issue Paper: Bioaccumulation Potential Based on Ambient Water Quality Criteria
Documents (VER BCF). 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 or data reported as approximations are considered non definitive and are not used in
SCDM. SCDM uses BCF values derived from wet weight data. Values derived from dry weight data are not
selected. When BCF values are reported as a range, the upper limit of the range is selected.

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.

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Table 1. Examples of Human Food Chain Aquatic Organisms

American or Virginia

Common carp

Green sunfish

Oyster

oyster

Common limpet, flither

Gudgeon

Pacific oyster

Atlantic salmon

Common mud crab

Japanese eel

Pinfish

Bay scallop

Common or edible winkle

Japanese littleneck clam

Pink salmon

Pink shrimp, common

prawn

Porcelain crab

Bay shrimp, sand shrimp

Common rangia or clam

Japanese whiting

Bent-nosed clam

Common shrimp, sand shrimp

Lake trout, siscowet

Bivalve

Crab

Lake whitefish

Porgy

Bivalve/clam/mussel class

Crayfish

Lamp mussel

Rainbow trout

Black abalone

Daggerblade grass shrimp

Largemouth bass

Red abalone

Black bullhead

Dog whelk, Atlantic

Leopard frog

Red sea bream

Blue crab

dogwinkle

Limpet

Red swamp crayfish

Bluegill

Dungeness or edible crab

Longnose killifish

River limpet

Bony fishes

Eastern lamp mussel

Mangrove oyster

Rough periwinkle
Scallop

Short-necked clam

Brook silverside

Edible or rock crab

Marine bivalve

Brook trout

European lobster

Marsh grass shrimp

Slipper limpet

Brown shrimp

Filefish

Marsh snail

Snail

Bullfrog

Flat, native European oyster

Mediterranean mussel

Sole order

Carp

Freshwater crab

Minnow, carp family

Spot

Catfish

Freshwater mussel

Mud crab

Starry flounder

Channel catfish

Fresh-water mussel

Mummichog

Striped mullet

Chinook salmon

Gizzard shad

Mussel

Swan mussel
Taiwan abalone
Two spot goby
Unionid clam

Clam

Golden shiner

Mussel family

Cockle

Grass shrimp, freshwater

Mussel, eastern elliptio

Coho salmon, silver

prawn

Netted dog whelk

Wedge clam

salmon

Great scallop

Northern kiill

White mullet

Common bay mussel, blue

Green mussel

Northern pink shrimp

Whitefish

mussel

Green or European shore crab

Opossum shrimp

Zebra mussel

2.5.2 Octanol/W'iter Partition Coefficient (Log K0w)

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/tsca-screening-tools/epi-suitetm-estimation-program-interface.

• PHYSPROP Database. Syracuse Research Corporation (SRC). Syracuse, NY. http://www.srcinc.com/what-
we-do/environmental/scientific-databases .html.

• Research Triangle Institute (RTI). 1996. Chemical Properties for SCDM Development. Prepared for the U.S.

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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
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.cfin#altable.

2.6.2 LC50- 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/chemical-research/ecotoxicology-database.

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. SCDM does not use ecological LC50 results that are qualified as labile, dissolved, or
unionized. Data that are reported in the references as less than or greater than a particular value or data reported as
approximations are considered non definitive and are not used in SCDM. When LC50 values are presented as a
range, the lowest value is collected.

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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 ://www3.epa.gov/ttn/naaqs/criteria.html.

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/enforcement/air-enforcement.

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 (NPDWS). Accessed through List of Drinking
Water Contaminants and MCLs. Office of Water, Washington, DC.
http://water.epa.gov/drink/contaminants/index.cfm.

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

(Although NPDWS is the primary source of MCLs, MCLs for beta-emitting radionuclides are collected from the
Soil Screening Guidance document where the NPDWS values in units of millirem/year are converted to pCi/L.)

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 jx/L). Where available, both MCLs and MCLGs are
collected for non-radionuclide substances; only MCL values are collected for radionuclide substances.

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

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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/guidanceregulation/ucm077969.htm.

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 CFRPart 192 (Uranium Mill Tailings Radiation Control Act Standards).
http: //www. ecfr. gov/cgi-bin/text-

idx?SID=2315f900f6e83727c94c050ced329934&mc=true&node=Pt40.25.192&rgn=div5#se40.25.192 102.
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.

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.
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 which HRS factor values and benchmarks will be included in the SCDM Web
Query.

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:

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December 2015

•	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.srcinc.com/what-
we-do/environmental/scientific-databases .html.

•	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.

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.srcinc.com/what-
we-do/environmental/scientific-databases .html.

•	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.

•	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.cpa.gov/tsca-
screening-tools/epi-suitetm-estimation-program-interface.

•	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.srcinc.com/what-
we-do/environmental/scientific-databases .html.

•	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.

18

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December 2015

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/tsca-
screening-tools/epi-suitetm-estimation-program-interface.

•	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.

•	PHYSPROP Database. Syracuse Research Corporation (SRC). Syracuse, NY. http://www.srcinc.com/what-
we-do/environmental/scientific-databases .html.

•	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:

•	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.

19

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December 2015

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 ,u for use in these
determinations. RfC values are converted from concentrations into inhalation dosages (RfDmhal) values for
determining HTF values using the following equation:

RFC,IR,AR
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
SFmhal before assigning HTF values, using the following equation:

_ IUR xBMxCF	^

inhal	Tr, . „	^ '

IRx 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).

20

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December 2015

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 Photolysis Half-Life

In instances where both direct and indirect photolysis half-lives are available, SCDM combines the two to
calculate a final photolysis half-life for lakes (Equation 5) or rivers (Equation 6) as follows:

1

PHALFL_FINAL =	jj	

PHALFL_D + PHALFLJ

Where:

PHALFL FINAL = Final photolysis half-life in lakes
PHALFL D = Direct photolysis half-life in lakes
PHALFL I = Indirect photolysis half-life in lakes

1

PHALFR_FINAL =	jj	

PHALFR_D + PHALFRJ

Where:

PHALFR FINAL = Final photolysis half-life in rivers
PHALFR D = Direct photolysis half-life in rivers
PHALFR I = Indirect photolysis half-life in rivers

3.5 Volatilization Half-Life

SCDM estimates the volatilization half-life in surface water for organic substances using Equation 7 (presented as
Equation 15-12 in the "Handbook of Chemical Property and Estimation Methods," Lyman, et al.1 In this method,
the volatilization half-life (Ti/2) can be expressed as follows:

T1/2 (hr) =

Z x In 2
~~Kl

(7)

Where:

Z = Mean water body depth (cm)

Kl = Overall liquid-phase mass transfer coefficient

In 2 = Natural logarithm of 2 (-0.693147)

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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December 2015

The following expression gives the overall liquid-phase mass transfer coefficient:

KL(cm/hr	(8)

(H/RT)kg + ki

Where:

3

H = Henry's Law constant (atmm /mol)

-5	3

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

T = Temperature (K; °C + 273)
kg = Gas-phase exchange coefficient
k1 = 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 (cm/hr) = 3,000 x (18 / MW)	(9)

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

1/2

kg (cm/hr)= 1137.5 x (Vwmd + Vcurr)(18 / MW)	(10)

Where:

Vwmd = Wind velocity (m/s)

Vcurr = Current velocity (m/s)

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

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

1/2

K (cm/hr)= 20 x (44 / MW)	(11)

•	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:

k/m/s) = 23.51 x (Vc°ur9r69 /(Z x lm / 100cm)° 673) x(32/AWf2	(12)

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

k/m/s) = 23.51 x(Vc°Jr69 /(Zxlm/lOOcm)0673) x (32/MWf2e™(Kind~X9) (13)
No liquid-phase exchange coefficient equation is provided in Thomas (1990) for wind velocities >5 m/sec.

22

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December 2015

Combining Equations (7), (8), (9), and (10) into a single equation for estimating volatilization half-life (T1/2) for
compounds with MW <65 g/mol gives the following equation:

T1/2 (days) = (1 day /24/ir) x (Z x In2) x {[(1 /20) x (MW/44)1/2] + [RT l(H x 3000) x (MW /18)1/2 ]} (14)

The following equation, combining Equations (7), (8), (9), 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:

T1/2 (days) = (\day / 24 hr) x Z x In 2 x {[(Z x \m /100 cmf613 /(23.51 x Vc°Jr69) x (MW !3lf2 ]

+ [RT/((H x 1,137.5) x (Vwmd +VCUJ) x (MW /18)12]}	(15)

The following equation, combining Equations (7), (8), (9), and (12), 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:

Ti/2 (days) = (\day /2Ahr) x Z x In2 x {[(Z x Im/lOOcm)0613 /(23.51 x Vc°ff) x (MW/32)1/2] e°-526^9-v^>

+ [RT/((H x 1,137.5) x (Vwmd +VCUJ) x (MW/18)12]}	(16)

-7	3

If H is <10 atm-m /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.

3.5.1	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 (14) and (15) reduce to the following:

•	IfMW <65 g/mol:

Ti/2 (days) = 2.89 x {[0.05 x (MW/44)1/2] + [(8.1 x 10 6 /H) x (MWUS)112}}	(17)

•	IfMW >65 g/mol:

T1/2 (days) = 2.89 x {[0.0425 x (MW 122)m] + [(1.4 x 10~5 / H) x (MW I \%f2]}	(18)

Where:

H = Henry's Law Constant (atm m3/mol)

MW = Molecular Weight (g/mol)

3.5.2	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
(14) and (15) reduce to the following:

23

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December 2015

•	If MW <65 g/mol:

Ti/2 (days) = 2.89 x {[0.05 x (MW/44)m]+ [(8.1 x 10~6 /H) x (MW/18)12]}	(19)

•	IfMW >65 g/mol:

T1/2(days) = 2.89 x {[0.775 x (MW/32)m] + [(3.9 x 10~5 /H) x (MW/18)12]}	(20)

Where:

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

MW = Molecular Weight (g/mol)

3.6 Overall Half-Lives

3.6.1 Overall Half-Lives for Nott-radionuclides

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

1

HALF LAK =

1 | 1 | 1 | 1	(21)

HHALFL 1 BHALFL 1 PHALFL 1 VHALFL

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 = —	1 ! ^	| !	(22)

HHALFR 1 BHALFR 1 PHALFR 1 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

3.6.2 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^

RHALFL + VHALFL

24

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December 2015

Where:

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

1

HALF_R_RIV =	jj	

RHALFR + VHALFR

Where:

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

3.7 Soil Water Distribution Coefficient (Kd); Soil Organic/Carbon Partition Coefficients (K0c)

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:

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 (K^).... 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 range for the hazardous substance using the following equation:

Kd = (Koc)(fs)	(25)

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 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:

25

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December 2015

Log Koc = 0.00028 + (0.983 Log Kow)

(26)

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):

[Note: SCDM applied the following criteria to define a substance as volatile: 1) vapor pressure greater than 1 mm
Hg or 2) Henry's Law constant greater than 0.00001 atm-m3/mole. These criteria are based on EPA Office of
Solid Waste and Emergency Response's (OSWER) "OSWER Technical Guide for Assessing and Mitigating the
Vapor Intrusion Pathway from Subsurface Vapor Sources to Indoor Air," Publication 9200.2-154, June 2015.]

3.8 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 (high water solubility)	(28)

Log Koc = 0.0784 + (0.7919 Log Kow)

(27)

26

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December 2015

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

(1000 fig^

THQ x (AT x ED) x

SC.

mg

EF x ED x ET x

^ 1 day ^

24 hours
\	J

1

(29)

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 (29) can be simplified as:

= 1042.857 x RfC

(30)

4.1.2 Carcinogenic — A ir, Inhalation

TRx(ATxLT)

SC.

Where:

EF x ED xET x

1 day
24 hours

\

(31)

xIUR

SCc-air = Air Inhalation Screening Concentration, Carcinogenic (|_ig/m )

27

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December 2015

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 (31) can be simplified as:

2.433 xlO"6

SCa-alr = 		(32)

IUR

4.1.3 Carcinogenic — A ir, Inhalation — Asbestos

(fibers/mL) = TR (IUR x TWF)	(33)

Where:

S(	= Air Inhalation Screening Concentration, Carcinogenic, Asbestos (fibers/mL)

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

IUR	= Inhalation Unit Risk (fibers/mL)"1

TWF	= Time Weighting Factor = 350/365 = 0.96

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

=			 TR,(AT,LD		(34)

' 1 day '

EF x ET x

24 hours

\

v, [(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)

EDq-2	= Exposure duration (2 years)

££>2-6	= Exposure duration (4 years)

ED6.l6	= 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 (34) can be simplified as:

28

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December 2015

9.605x10 7

SC =		(35)

mu—air	^ '

1UK

4.1.4.1 Vinyl Chloride - Air, Inhalation

scm. „„ = —	TR

IUR

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

(36)

Where:

SCmu_vc = 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 (36) can be simplified as:

7.090 xl0~7

i^r-	<37)

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.

77? x (AT x LT)

gQ =	!	i	

" EF X ET X (1 day/24 hours) x [(ED 0_2 x IURkldney x 10) + (ED2_6 x IURkldmy x 3)

+ (ED6-w x !URkldney X 3) + (ED16_30 X IURkldney 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)

EDq-2 = Exposure duration (2 years)

ED2-6 = Exposure duration (4 years)

ED6_16 = Exposure duration (10 years)

ED mo = Exposure duration (14 years)

EF = Exposure frequency (350 days/year)

ET = Exposure time (24 hours/day)

IURkidney = Inhalation unit risk, kidney (|_ig/m3)_1

29

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December 2015

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

SCm-air = 9.61 X 10 /IURkidney	(39)

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(ATxLT)	

EFxEDxETx(l day/24 hours)xIURNHLandLlver

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 1^ anjj nver

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

Using the exposure assumptions listed above, Equation (40) can be simplified as:

SCc_air = 2.44 x 10"6 / IURNHLandllver	(41)

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.

1

mu—c—tce {	\ f	\	(42)

r i

\



r i

\

sc_



sc_

V m—air J

V c—air J

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

gQ	— 		(An)

IflU	C	tCC	s*. A	1 /-\6 T T TT-\	A 1 y~\	1 s~\ 5 TT TT^l	^	'

1.04x10 707^+4.10x10 IURNHLandLiver

30

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December 2015

4.1.5 Carcinogenic —Air, Inhalation, Radionuclides

TR

c-air-rad

ETx (im)x EFx ED x SFiX IFA^dj	(44)

Where:

(IRA x EDC +IRAr_a x EDrJ

IFAr-adj =	"	W)	

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 (44) can be simplified as:

SCc_air_rad = 5.29 x 10"12 / SFj	(45)

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

= THQ xATx EDc X BMC

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

1 ' :/RSc

EF x EDC

RfD

mg

Where:

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

31

-------
December 2015

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 (46) can be simplified as:

SC

res-sol-nc-ing

= 78214.29 xR/D

(47)

4.2.2 Carcinogenic — Soil, Ingestion

SC

TRxATxLT

res-sol-ca-ing

SF x EF x IFS x

lO^kg
mg

(48)

Where:

SC res_soi_c

IFS

SF

TR

AT

LT

EF

EDC

EDr

IRSa

IRSC

BMa

BMr

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

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

(

EDc x IRS

	c

BM „



(EDr — EDC ) x IRSa
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 (48) can be simplified as:

SC

res-sol-ca-ing

0.64

~~sF

(49)

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

(50)

32

-------
December 2015

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:

f

EDn

IRS„ x 10

A

BM

f

ED„

IRS

i'\ (

BM

EDK

IRS„



BM„

(

EDl6_30xIRSa
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)

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)

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 (50) can be simplified as:

0.149

sc

res-sol-mu-ing

SF

(51)

4.2.3.1 Vinyl Chloride - Soil, Ingestion

SC

TR

res-sol-ca-vc- ing

f 10 6 kg ^
SF x EF x IFS x	^

mg

ATxLT

SF x IRS c x

BMr

10 6 kg
mg

(52)

Where:

SC,

res-sol-ca-vc-ing

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

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

SF

TR

AT

LT

EF

EDC

EDr

IRSa
IRSn

(

EDc x IRSc
BM „

(EPr — EDc) x IRSa
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 - child (= 6 years)

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

33

-------
December 2015

BMa = Body mass - adult (=70 kg)

BMC = Body mass - child (=15 kg)

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

SC ,	= 0 067	(53)

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.

=	TRxAT xLT	

sol-mu-tce-ing	1 n~6 1

SFkidney x EF x IFSM x	*

mg

Where:

SC_soi_mu_tce4ng = Soil Screening Concentration, Mutagenic (mg/kg)

IFSM= Mutagenic soil ingestion rate-resident, age adjusted [=(489.5 mg-year)/(kg-day)], calculated as:
(ED0_2 x IRS\ x 10^ (ED,_k x IRS\ x 3] (EDK_1K x IRS„ x 3} (ED„_,n x IRS„ x l}

BM„

BM„

'6-16

BM „

BM „

SFkidney	= Chronic oral 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)

ED0-2	= Exposure duration - resident ages 0-2 (= 2 years)

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

ED6_16	= Exposure duration - resident ages 6-16 (=10 years)

ED16_30	= 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 (54) can be simplified as:

_ 0.149

soil-mu—tce-ing 0 77

(55)

kidney

34

-------
December 2015

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

(56)

Where:

SC_soi_ca_tce4ng = Soil Screening Concentration, Carcinogenic (mg/kg)

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

( EDr — EDC ) x IRS a

f EDc x IRS.

BM

BM

SF}

TR

AT

IT

EF

EDC

EDr

IRSa

IRSC

BMa

BMC

NHL and liver

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

= Target risk (=1x10 )

= 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)
= Body mass - adult (=70 kg)

= Body mass - child (=15 kg)

Using the exposure assumptions listed above, Equation (56) can be simplified as:

0.64

SC

soil-ca-tce—ing

SF}

(57)

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

soll-ca-mu-tce-ing

(58)

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:

SC

1

soil - ca- mu-tce-ing

\.56SFnhl

and Liver

6.71 SFMdney

(59)

35

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December 2015

4.2.4 Carcinogenic — Soil, Radionuclides
1) Oral

„r			TRx I , x /.	

soll-ca-rad f	/	\ \	(60)

(1-e lt')xSFs xIFSr_adj xEFr x EDr x

r-adj

g	

mrT J J

lOOOmg

Where:

(IRScxEDc IRSaxEDr_J

'''^r-adj	JiJ)

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 (60) can be simplified as:

SCc_sol_rad = 2.38 x 10"11 x 1/[(1 - e"3) x SEext xACI-'xx	x /¦:/) x [ETr-0 + (ETr.,x GSFt)]

(62)

Where:

SCext-rad	= Screening concentration benchmark - radiochemical, external (pCi/g)

SFext	= Slope factor - external exposure - substance specific) (pCi)"1

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

tr	= Time (30 years)

X	= Lamba - substance specific

e	= Euler's number (= 2.718281828)

ACF	= Area correction factor - substance specific

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)

36

-------
December 2015

ETr_0	= Exposure time - resident outdoor (0.073 hr/hr)

ET,_	= Exposure time - resident indoor (0.684 hr/hr)

GSF,	= Gamma shielding factor - indoor (0.4), unitless

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

Using the exposure assumptions listed above, Equation (62) can be simplified as:

= 3.01x10 6 xX

ext-rad	j ^	x/)

4.3 Screening Concentration Benchmarks for Ground Water and Drinking Water

The following equations are used to determine water ingestion screening concentration benchmarks. 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 4.3.1 (non-carcinogenic benchmarks) and Section 4.3.2 (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 4.3.3; 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 4.3.4.

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

THQ xATx EDC x BMC x 1000 fig/mg

water-nc-ing	^	^	—	(64)

EF x EDC x

RfD

xlRWc

Where:

SCwater_nc4ng = Ground Water/Drinking Water Screening Concentration, Non-Carcinogenic (j^ig/L)

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

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

BMC = Body mass - child (=15 kg)

EDC = Exposure duration - child (= 6 years)

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

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

THQ = Target hazard quotient (=1)

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

SCwatmg = 15642.86 xRp	(65)

4.3.2 Carcinogenic — Ground Water and Drinking Water, Ingestion

TRxATxLTxlOOO jug/mg

water-ca-ino, / ,» - ,. , -

(66)

SF x EF x IFW

Where:

37

-------
December 2015

water-

1FW

SF

TR

AT

LT

EF

EDC

EDr

IRWa

IRWC

BMa

BMC

ca-ing = Ground Water/Drinking Water Screening Concentration, Carcinogenic (j^ig/L)

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

(EDC x IRWc
BM,

jEDr - EDC ) x IRWa
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 (66) can be simplified as:

0.0672

SC

water-ca-ing

SF

(67)

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

SC

water-mu-ing

TRxATxLTxlOOO jug/mg
SF x EF x IFWM

(68)

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:

f ED0_2 xIRWcx 10^

(ED, , xIRW x 3^

	2-6	c	

BM„

(ED, xIRW x3^

	6-16	a	

(ED„ xIRW xl^

	16-30	a	

= 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)
ED mo = 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)

SF
TR
AT
LT

EF
EDo-2
ED2-6
EDg_16

38

-------
December 2015

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

0.0215

sc

water-mu-ing

SF

(69)

4.3.3.1 Vinyl Chloride - Ground Water and Drinking Water, Ingestion

TR

SC

res-water-ca-vc-ing

f

SFxEFx IFW x

mg
1000 jug



ATxLT

f

SF x IRWC x

mg
1000 jug



BMr

(70)

Where:

SC,

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
BM,,

(EDr - EDC ) x IRWa
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)

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

= Body mass - child (=15 kg)

SF

TR

AT

LT

EF

ED,

ED,

BMC
BM;

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

0.0123

SC

res-water-ca-vc-ing

SF

(71)

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
equation provided below.

_	= TRxATxLTxlOOO

W,ater-mu-tce-rng SFkldney X EF X IFWM

39

-------
December 2015

Where:

sa

water-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:

SFkidney

TR
AT
LT

EF
EDo_2

ED2-6

EDg.jg

ed16_30

IRWa
IRWC
BMa
BMr

(

EDn

:IRWx 10

A

BM „

(

ED„

IRW x 3

A

BM „

(

EDK

IRW..



BM „

(

ED,

IRW.. xl

A

BM„

= Chronic oral cancer 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)
= 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 (72) can be simplified as:

SCwater-mu-tce-ing 0.0215/ SFkidney

(73)

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

TR x AT x LT x 1000 ng/mg

SC

water-ca-tce-ing

SFNHLandLlverxEFxIFW

(74)

Where:

KC

^ water-ca-tce-i ng

IFW

and liver

TR

AT

LT

EF

EDC

EDr

IRWa

1RWC

BMa

BMC

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

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

^ {EDr - EDc ) x IRWa

f EDC x IRW.

BM.

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)

= 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)

40

-------
December 2015

Using the exposure assumptions listed above, Equation (74) can be simplified as:

SCwater-ca-tce-ing "

0.067 / SFNHL and liver

(75)

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

1

water-ca-mu-tce-ing

\ f

+

SC

water-ca-ing

SC

water-mu-ing J

(76)

Substituting the simplified equations provided above for obtaining Step 1 and Step 2 results, the following is an
alternative to Equation 76 for calculating Step 3 results:

SC

1

water-ca-mu-tce-ing

14.9 SFNHLand Ljver + 46.5 SFkidney

(77)

4.3.4 Carcinogenic — Ground Water and Drinking Water, Radionuclides

SC	=	—		(78)

c-water-rad ^ ^ ^ ^ XIFWr_ad]

Where:

EDC x IRWC + EDrax IRWa

IFWr ndi =	

r'ad]	EDr

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)

EDC = Exposure duration - resident child (6 years)

EDr_a = Exposure duration - resident adult (24 years)

IFTVr_acij— Age-adjusted water ingestion rate (1.8 L/day)

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

SCC-Water-rad = 5.29 X 1 0"" / .S'/v	(79)

41

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December 2015

4.4 Screening Concentration Benchmarks for the Human Food Chain

The following equations are used to determine screening concentration benchmarks for the human food chain
threat. 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 , \	1 n-6 j

RfD

mg

Where:

SCres-fsh-nc-mg = 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 (80) can be simplified as:

SCres-fsh-nc-ing = 1350 X Rfi	(81)

4.4.2 Carcinogenic — Human Food Chain, Fish Ingestion

TR x AT xLTx BM
SC fh . =	2		(82)

res-fsh-ca-ing	1 f) Ira

EFxED x SF x 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)

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 (82) can be simplified as:

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December 2015

000315

res - fsh—ca-ing	,.. .	(83)

or

4.4.3 Carcinogenic — Human Food Chain, Fish Ingestion, Radionuclides

SCc_fish_rad =				(84)

EF x ED x SFf xIRFx	-	

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 (84) can be simplified as:

SC c-flsh-rad = 1.76 x 10'12/SFf	(85)

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December 2015

5.0 SCDM DATA REPORTING and WEB QUERY

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 the SCDM Web Query.

The following rules are applied for purposes of reporting SCDM data in the SCDM Web Query:

• 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 Web Query

The SCDM Web Query (http://www.epa.gov/superfund/superfund-chemical-data-matrix-scdm-query) contains
selected data, HRS factor values and benchmarks for each hazardous substance in SCDM. Information is provided
in tables for each substance. These tables are divided into three categories of available information: factor values,
benchmarks and data elements.

Figure 1 presents an example of the header that appears on the SCDM Web Query report for each substance. The
header contains the substance name, the substance CASRN, and the date the query is accessed.

Substance: Acenaphthene
[CASRN 000083-32-9]

Query Accessed: 11/22/2015

Figure 1. SCDM Web Query Report Heading

For each substance, the data elements tables contain 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, mobility, bioaccumulation, physical characteristics, other data and class information.

The toxicity table (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 human toxicity and ecotoxicity factor values.

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December 2015

DATA ELEMENTS: TOXICITY
Acenaphthene [CASRN 000083-32-9]

Parameter	Value	Unit	Source

Oral RfD	6.0E-02	mg/kg/day	IRIS

Inhal RfD
RfC

Oral Slope
Oral Wt-of-Evid
IUR

IUR Wt-of-Evid
Inhal Slope
Oral ED10
Oral ED10 Wgt
Inhal ED10
Inhal ED10 Wgt
Oral LD50
Dermal LD50
Gas Inhal LC50
Dust Inhal LC50
Acute, Fresh CMC
Acute, Salt CMC
Chronic, Fresh CCC
Chronic, Salt CCC

Fresh Ecol LC50	5.0E+01 MQ/L	ECOTOX

Salt Ecol LC50	1.4E+02 pg/L	ECOTOX

Figure 2. Toxicity Table

The top half of this table 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 table 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 table (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 Kow or 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).

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DATA ELEMENTS: PERSISTENCE
Acenaphthene [CASRN 000083-32-9]

LAKE- HALFLIVES

Parameter

Hydroiysis

Volatility

Final Photolysis

Direct Photolysis

Indirect Photolysis

Unspecified Photolysis

Biodeg

Radio

Parameter

Hydrolysis

Volatility

Final Photolysis

Direct Photolysis

Indirect Photolysis

Unspecified Photolysis

Biodeg

Radio

Parameter
Log Kow

Value

1.1E+02

2.5E+00

1.0E+02

RIVER- HALFLIVES

Vaiue

1.3E+00
2.5E+00

1.0E+02

OTHER

Vaiue
3.9E+00

Unit

Days
Days
Days
Days
Days
Days

Unit

Days
Days
Days
Days
Days
Days

Unit

Source

THOMAS
HEDR

HEDR

Source

THOMAS
HEDR

HEDR

Source
EPI EXP

Figure 3. Persistence Table

The mobility table (Figure 4) 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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December 2015

Parameter
Vapor Press
Henry's Law
Water Solub
Distrib Coef
Geo Mean Sol

DATA ELEMENTS: MOBILITY

Acenaphthene [CASRN 000083-32-9]

Value

2.1E-03

1.8E-04

3.9E+00

7.6E+02

Unit
Torr

atrrs-m3/mo!

mg/L

mL/g

Source

PHYSPROP

CALC

Figure 4. Mobility Table

The bioaccumulation table (Figure 5) 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.

DATA ELEMENTS: BIOACCUMULATION

Acenaphthene [CASRN 000083-32-9]

FOOD CHAIN

Parameter

Fresh BCF
Salt BCF

Parameter
Fresh BCF
Salt BCF

Parameter
Log Kow
Water Solub
Geo Mean Sol

Value

3.8E+02

Unit

ENVIRONMENTAL

Value Unit

3.8E+02

OTHER

Value Unit

3.9E+00

3.9E+00 mg/L

Figure 5. Bioaccumulation Table

Source

ECOTOX

Source

ECOTOX

Source

EPI_EXP
PHYSPROP

The physical characteristics table (Figure 6) 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
which HRS factors and benchmarks may be included. 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.

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December 2015

DATA ELEMENTS: PHYSICAL CHARACTERISTICS
Acenaphthene [CASRN 000083-32-9]

Parameter
Metal Contain
Organic
Gas

Particulate
Radionuclide
Rad. Element
Molecular Weight
Density

Value

Unit

No

Yes

Yes

Yes

No

No

1.2E+00	g/mL @ 20.0 °C

Figure 6. Physical Characteristics Table

1.5E+02
1.2E+00

The table labeled "other data" (Figure 7) contains values for melting points and boiling points (°C). The chemical
formula is also listed here.

The class information table (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.

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.

Parameter
Melting Point
Boiling Point
Formula

DATA ELEMENTS: OTHER DATA

Acenaphthene [CASRN 000083-32-9]

Value

Unit

°C
°C

9.3E+01
2.7E+02
C12H10

Figure 7. Other Data Table

Parameter
Parent Substance

DATA ELEMENTS: CLASS INFORMATION

Acenaphthene [CASRN 000083-32-9]

Value

Figure 8. Class Information Table

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December 2015

The other two categories of SCDM Web Query tables—factor values and benchmarks—contain the factor values
(Figures 9 through 12) and benchmarks (Figures 13 through 17) required by the HRS. SCDM determines factor
values using HRS methodologies from selected data in the data elements tables. The factor values are presented
by HRS pathway: ground water, surface water, soil and air. 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 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. The air pathway gas migration factor value is used to determine
likelihood of release. For radioactive substances, human toxicity, ecosystem toxicity and surface water persistence
factor values are determined as specified in Section 7 of the HRS.

FACTOR VALUES: GROUND WATER PATHWAY

Acenaphthene [CASRN 000083-32-9]

Parameter

Toxicity
Water Solub
Distrib

Geo Mean Sol
Mobility: Liquid, Karst
Mobility: Liquid, Non-Karst
Mobility: Non-Liquid, Karst
Mobility: Non-Liquid, Non-Karst

Value

3.9E+00
7.6E+02

1.0E+00
1.0E-02
2.0E-01
2.0E-03

Figure 9. Ground Water Pathway Factor Values Table

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December 2015

FACTOR VALUES: SURFACE WATER PATHWAY

Acenaphthene [CASRN 000083-32-9]

DRINKING WATER

Parameter
Toxicity

Persistence, River
Persistence, Lake

Parameter
Toxicity

Persistence, River
Persistence, Lake
Bioaccumulation, Fresh
Bioaccumuiation, Salt

Parameter
Toxicity, Fresh
Toxicity, Salt
Persistence, River
Persistence, Lake
Bioaccumuiation, Fresh
Bioaccumulation, Salt

HUMAN FOOD CHAIN

ENVIRONMENTAL

Value

10

Value

10

500
500

Value
10000
1000

500
500

Figure 10. Surface Water Pathway Factor Values Table

FACTOR VALUES: SOIL EXPOSURE PATHWAY
Acenaphthene [CASRN 000083-32-9]

Parameter	Value

Toxicity	10

Figure 11. Soil Pathway Factor Values Table

FACTOR VALUES: AIR PATHWAY
Acenaphthene [CASRN 000083-32-9]

Parameter	Value

Toxicity	10

Gas Mobility	0.2

Gas Migration	11

Figure 12. Air Pathway Factor Values Table

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December 2015

The benchmarks (Figures 13 through 17), like the factor values, are presented by pathway: ground water, surface
water, soil and air, as described in Sections 3 through 6 of the HRS. 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.

BENCHMARKS: GROUND WATER PATHWAY

Acenaphthene [CASRN 000083-32-9]

Parameter	Value	Unit

MCL

MCLG

Cancer Risk

Non-Cancer Risk	9E-01	mg/L

Figure 13. Ground Water Pathway Benchmarks Table

BENCHMARKS: SURFACE WATER PATHWAY

Acenaphthene [CASRN 000083-32-9]

DRINKING WATER

Parameter	Value	Unit

MCL

MCLG

Cancer Risk

Non-Cancer Risk	9C-01	mg/L

HUMAN FOOD CHAIN

Parameter	Value	Unit

FDAAL
Cancer Risk

Non-Cancer Risk	8E+01	mg/kg

ENVIRONMENTAL

Parameter	Value	Unit

Acute, Fresh CMC
Acute, Salt CMC
Chronic, Fresh CCC
Chronic, Salt CCC

Figure 14. Surface Water Pathway Benchmarks Table

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December 2015

BENCHMARKS: SOIL EXPOSURE PATHWAY
Acenaphthene [CASRN 000083-32-9]

Parameter	Vaiue	Unit

Cancer Risk

Non-Cancer Risk	4E+03	mg/kg

Figure 15. Soil Exposure Pathway Benchmarks Table

BENCHMARKS: AIR PATHWAY
Acenaphthene [CASRN 000083-32-9]

Parameter	Value	Unit

NAAQS
NESHAPS
Cancer Risk
Non-Cancer Risk

Figure 16. Air Pathway Benchmarks Table

Parameter
MCL

Cancer Risk

Parameter
Cancer Risk

BENCHMARKS: RADIONUCLIDE

Acenaphthene [CASRN 000083-32-9]

DRINKING WATER

Value

HUMAN FOOD CHAIN

Vaiue

Parameter
UMTRCA

Cancer Risk Soil Ing
Cancer Risk Soil Gam

Parameter
Cancer Risk

SOIL

Vaiue

AIR

Vaiue

Unit

Unit

Unit

Unit

Figure 17. Radionuclide Benchmarks Table

Appendix A contains a cross-reference index of hazardous substance names, synonyms and CAS Numbers for
substances in SCDM.

52

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December 2015

6.0 REFERENCES

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U.S. EPA. 1988 .Methodology for Evaluating Potential Carcinogenicity in Support of Reportable Quantity
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idx?SID=2315f900f6e83727c94c050ced329934&mc=true&node=pt40.25.192&rgn=div5#se40.25.192 102

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