United States Region 10 Alaska
Environmental Protection 1200 Sixth Avenue Idaho
Agency Seattle WA 98101 Oregon
• Washington
&EPA
Reply tcr August 23, 1991
Attn. of: ES-098
MEMORANDUM
Subject: Supplemental Guidance for Superfund Risk Assessments in
Region 10
From: /^.Patricia A. CironeTChief 6^
^ Health & Environmental Assessment Section
Carol Rushin, Deputy Chief
Superfund Branch
U.S.Environmental Protection Agency, Region 10, Superfund
program, has been developing supplemental guidance for conducting
Human Health Risk Assessments at Superfund Sites. An interim
final product is attached. This document was prepared as a joint
effort between Region 10 remedial project managers and the risk
assessment staff.
This regional guidance is not meant as a replacement or in
lieu of national guidance. Rather, it should be treated as an
extension or more detailed explanation of the National
Contingency Plan and Part A of the Risk Assessment Guidance for
Superfund, Volume 1, Human Health Evaluation Manual.
We suggest that you use this document whenever you are
working on risk assessments documents that will be submitted to
EPA Region 10. Such work includes preparing or reviewing scoping
documents; preparing and reviewing risk assessment and RI/FS work
plans; and preparing and reviewing draft and final risk
assessments and interim deliverables. As one of the goals of
this guidance has been to address issues that frequently come up
during the planning of risk assessments, it provides general
policy direction on a number of issues.
We are calling this document an interim final, since we
believe risk assessment is always evolving and we wish to allow
for changes which may be necessary in the future. When changes
become necessary we will either issue them as addenda to the
original document or provide a major revision. Any changes or
additions will be dated and appropriate references for
incorporation into this document will be provided.
i
You will notice that the sections on ecological evaluation
are not completed. We will add sections on ecological evaluation
as national and regional guidance is developed.
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We appreciate the effort many of you made to provide us with
your concerns during the workshops and discussions we conducted
daring the development of this guidance. We have tried to
respond to these concerns in this interim final version.
Additional questions or comments on the document should be
to Carol Sweeney (telephone number (206) 553-6699) of
risk assessment staff.
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EPA Region 10
Supplemental Risk Assessment Guidance for Superfund
August 16,1991
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EPA Region 10
Supplemental Risk Assessment Guidance for Superfund
Table of Contents
1.0 Introduction. 1
1.1 Scheduling of Dellverables. „ 1
1.2 Focus of Risk Assessment 3
2.0 RI/FS Project Planning. 5
2.1 Scheduling of RI/FS Project Planning Interim Dellverables 5
2.2 .Conceptual Site Model 5
2.3 Preliminary Remediation Goals 6
2.3.1 List Expected Contaminants
2.3.2 Identify Potential ARARS
2.3.3 Assemble Tcndcity Information
2.3.4 Calculate 'Risk at ARAB' and 'Risk Based Concentration''
2.3.5 Present PRG Information In a Table
2.4 Exposure Scenarios and Pathways 12
2.5 Consideration of Risk Assessment Data Needs in the Work Plan. 13
2.5.1 Use of Sampling Data in the Risk Assessment
2.5.2 Analytes and Detection Limits
3.0 Preliminary Data Analysis 15
3.1 Scheduling of Risk Assessment Dellverables During Preliminary Data Analysis. 15
3.2 Ewaluation of Lab Contaminants and Natural Background 16
3.2.1 Lab Contaminants
3.2.2 Natural Background
3.3 Risk-based Screening of Contaminants: Human Health 17
3.3.1 Risk-Based Screening: Suggested Approach
3.3.2 Chemical-Specific Screening Criteria
3.4 Risk-based Screening of Contaminants: Ecological
("reserved")
3.5 Revised Conceptual Site Model/Exposure Pathways 19
4.0 Baseline Human Health Risk Assessment 20
4.1 Scheduling of the Baseline Risk Assessment 20
4.2 Exposure Assessment 20
4.2.1 Selection of Exposure Scenarios
4.2.2 Select Exposure Pathways
4.2.2.1 Pathways of Exposure to Son
4.2.2.2 Pathways of Exposure to Groundwater
4.2.2.3 Pathways of Exposure to Surface Water and Sediment
4.2.3 Calculating Exposure Point Concentration from Sampling Data
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EPA Region 10
August, 1991
4.2.3.1 Calculating the "RME" Concentration
4.2.3.2 Grouping Samples
4.2.3.3 Background
4.2.3.4 Non-Detects
4.2.4 Predicting Exposure Point Concentration Using Modeling/Estimates
4.2.5 Contact Rate, Exposure Frequency and Duration
4.2.5.1 Use of Standard Default Exposure Factors
4.2.5.2 Region 10 Default Exposure Factors
4.3 Toxicity Assessment 28
4.3.1 Toxtetty Reference Values
4.3.2 Toxlcity Profiles
4.4 Risk Characterization and Uncertainty Analysis. 29
4.4.1 Risk Characteriation Using RfCs and Units Risks
4.4.2 Summary Tables
4.4.3 Uncertainty Analysis
4.4.3.1 Qualitative Uncertainty Analysis
4.4.3.2 Quantitative Uncertainty Analysis
4.4.4 Summary and Conclusions
5.0 Baseline Ecological Risk Assessment
("reserved")
6.0 Risk Evaluation of Remedial Alternatives 32
6.1 Scheduling of Risk Assessment Deliverables for the FS 32
7.0 References 33
8.0 Where to Obtain Documents 35
APPENDICES
Appendix I. Calculation of Human Health Risk-Based Concentrations
Appendix II. Human Health Risk-Based 'Preliminary Remediation Goals* for Water and Sol
Table 11-1 Water Cheat Sheet: MCL's and Risk-based Concentrations
Table II-2 Soil Cheat Sheet: Risk-based Concentrations
Appendix III. Summary Tables of Exposure Factors
Table III-1 a. Residential RME and Average Exposure Factors for Superfund Human
Health Risk Assessment
Table 111-1 b. Industrial RME Exposure Factors for Superund Human Health Risk Assessment
Table III-2. Exposure Factors Used for Risk Assessment at Hazardous Waste Sites:
DetaPs of Differences Among Programs
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EPA Region 10
August, 1991
1.0 Introduction
The methodology to be used in developing the baseline risk assessment Is described In the Risk Assessment
Guidance For Superfund, Volume I: Human Health Evaluation Manual, Part A, (EPA 1983d) (RAGS HHEM)
and Volume II, Environmental Evaluation Manual (EPA 1969C). Parts B (EPA 1991e) and C (EPA 199!f) of
the Human Health Evaluation Manual, which are now being written by EPA, will provide guidance on the use
of risk assessment In the Feasibility Study. This Region 10 guidance summarizes important concepts from
the national guidance, highlights steps of the Remedial Investigation / Feasibility Study (RI/FS) process
where risk assessors need to be Involved, and Identifies specific dellverables that should be submitted to
Region 10 during development of the baseline risk assessment The anticipated users of the regional
guidance are project managers, who need to identify stages of the remedial process where a risk assessor
should -be involved, as well as technical staff who write or review risk assessments.
This document supersedes the January, 1990 Region 10 Statement of Work for Human Health Risk
Assessment New or substantially revised guidance Is provided on some Important Issues.
Highlights of Revised Region 10 Guidance:
- Calculation of Preliminary Remediation Goals
(Section 2.2 and Appendices I and II)
- Risk-Based Screening of Contaminants
(Section 3.1 and Appendices I and II)
- Use of Standard Default Exposure Parameters (for Human
Health Evaluation) (Section 4.1 and Appendix III)
1.1 Scheduling of Dsllverablaa
The organization of this regional risk assessment guidance consistent with the "Region 10 Policy, Conduct
of Remedial Investigations and Feasibility Studies' (EPA 1990e). This regional risk assesement guidance
identifies certain items as risk assessment interim deliverables, which should be submitted in advance of the
baseline risk assessment Risk assessment interim deliverables can be Included as parts of the Site
Characterization. Work Plan, and Preliminary Data Analysis documents (see figure 1 -1), or may be submitted
as separate technical memos, according to the needs of the particular project The EPA Remedial Project
Manager (RPM) will determine the specific schedule of deliverables for a site. The information from Interim
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EPA Region 10
August. 1991
Phase I. Scoping Report(s) and Work Plan
Site Characterization and/or Scoping Document
Conceptual Site Model (2.2)
Preliminary Remediation Goals (2.3)
RI/FS Work Plan
Exposure Scenarios and Pathways (2.4)
Phase II. Preliminary Data Analysis / Site Characterization Summary
Evaluation of Lab Contaminants
and Natural Background (3.2)
Risk-Based Screening of Contaminants (3.3)
Revised Conceptual Site Model/
Exposure Pathways (as needed) (3.5)
Phase III. Remedial Investigation and Feasibility Study Reports
Remedial Investigation Report
Baseline Risk Assessment (4.0 and 5.0)
Feasibility Study
Risk Evaluation of Remedial Alternatives (6.0)
Rgure 1-1. Integration of Risk Assessment Deliverables in RI/FS Process.
Items in bold are risk assessment deliverables. References in parentheses
are to relevant sections of Region 10 Supplemental Risk Assessment
Guidance.
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EPA Region 10
August, 1991
deliverables will ultimately be Incorporated in the baseline risk assessment, or elsewhere In the RI/FS, or as
appendices to these documents. The Intent of requesting early submlttal of Interim deliverables for review
is to facilitate the progress of the risk assessment, to encourage discussion, and to clarify reasoning in
decisions affecting risk assessment and ultimately risk management DeHverables are discussed here in
the sequence in which they will be submitted, as outlined in figure 1-1. Further discussion of scheduling of
risk assessment deliverables is provided in sections 2.1, 3.1, 4.1 and 6.1. Recent headquarters guidance
(EPA 1991Q also addresses scheduling of deliverables for sites at which a potentially responsible party (PRP)
wil conduct the RI/FS but the EPA will conduct the risk assessment
1.2 Focum of Risk Assessment
Quite a oft of detailed EPA guidance is available on the subject of risk assessment in general as well as
Superfund risk assessment in particular. (See section 7.0, References.) We hope that this regional guidance
wll be useful In pointing out relevant guidance for specific issues. However, guidance does not serve as
a 'cookbook* or establish an invariable pattern, but is subject to interpretation. National Priority Ust (NPL)
sites In Region 10 vary in size from a few acres to square mOes, vary in number and type of sources of
contamination, and vary in presence of ecological receptors or in potential for exposure to human
populations. The risk assessment process and the report produced as an end product will not be exactly
the same for any two sites. The process will be modified as appropriate to each project The professional
judgement of the project manager, risk assessor, and reviewers will always be involved in determining what
level of effort wll be devoted to risk assessment and to specific aspects of the risk assessment See RAGS
HHEM (EPA 1989d), chapter 3, for additional discussion regarding goals and focus of the risk assessment
Ideally, the risk assessment process will be iterative, with results of early steps (scoping meeting, calculation
of preliminary remediation goals, and •screening" risk assessment) used to focus subsequent work on
information needed by decision-makers and on important chemicals, pathways, and issues. For example,
the RPM and risk assessor may find that not as much precision is needed in the baseline risk assessment
for a site where remedial action is clearly triggered, based on criteria in the National Contingency Plan (NCP)
(EPA I990d) and 'Role of the Baseline Risk Assessment..1 memo (EPA 1991h), although detailed analysis
might go into setting remediation goals for such a site. For a site where preliminary calculations show risks
near the upper boundary of the risk range, more effort and precise Information for the baseline risk
assessment might be needed to support risk management decisions.
Some NPL sites will be managed as multiple operable units, or as projects of several phases, including early
or interim actions, rather than a single RI/FS. Appropriate modifications of the risk assessment process to
meet the needs of decision-makers will be important for these sites. Instead of a single 'baseline' risk
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EPA Region 10
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assessment, the risk assessment deliverables might include one or more focused risk assessments,
addressing a single source area or medium. The focused risk assessment would be used to justify a specific
action. This Is consistent with RAGS HHEM, section 3.3. This type of approach Is also discussed In the
guidance for CERCLA Municipal Landfills (EPA 1991 a), on pages 3-39 and 3-40:
"it may be possible to streamline or limit the scope of the baseline risk assessment In order to initiate
remedial action on the most obvious landfill problems... Ultimately, It will be necessary to
demonstrate that the final remedy, once implemented, wOl address all pathways and contaminants
of concern, not just those that triggered the need for remedial action.'
Sites where early action or operable unit actions had been taken based on focused risk assessment or
other criteria would later require a comprehensive risk assessment, considering all sources, pathways, and
contaminants, to justify final actions or 'no further action* decisions. At a partially remediated site, the risk
assessment would evaluate the site in its present physical condition. The RPM and risks assessor would
decide how to factor ongoing actions into the risk assessment
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EPA Region 10
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2.0 RI/FS Project Planning
2.1 Scheduling of RI/FS Prelect Planning Interim D*llv«rabU«
Risk Assessment Interim Deliverables During RI/FS Project Planning
- Conceptual Site Model (2.2)
- Preliminary Remediation Goals (2.3)
- Exposure Scenarios and Pathways (2.4)
The risk assessment information considered in the RI/FS project planning Is often included In primary
documents, such as a scoping document and work plans. The Items described In section 2 as 'Interim
deliverables' can either be submitted for review in advance of the larger documents, or the information can
be incorporated In the larger documents and reviewed at the same time. The specific schedule is up to the
discretion of the RPM. For sites where the potentially responsible party (PRP) will be conducting the RI/FS
whle an EPA contractor will be doing the risk assessment, it wll probably be necessary to have separate
risk assessment deliverables submitted. The risk assessor wil need the conceptual site model and list of
expected contaminants, submitted by the PRP, In order to prepare preliminary remediation goals (PRGs) and
exposure pathways. In turn, the exposure pathways wll have to be presented in time for the PRP to
consider risk assessment data needs In preparing the RI/FS work plan. (See also the recent directive on
risk assessment for PRP sites (EPA 19911)).
2.2 Conceptual Site Model
The 'Site Characterization Document,' or another document used at the scoping stage, should present and
discuss a conceptual site model for both current and potential future site use. This should be a flow chart
showing site characteristics, including contaminant sources, release mechanisms, transport routes,
receptors, and other information as appropriate. Iterations of this model will be carried through the workplan
and baseline risk assessment report As stated on page 2-9 of the Guidance for Conducting Remedial
Investigations and Feasibility Studies (EPA 1988b) (RI/FS guidance):
The conceptual site model should include known and suspected sources of contamination, types
of contaminants and affected media, known and potential routes of migration, and known or
potential human and environmental receptors. This effort, in addition to assisting in Identifying
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EPA Region 10
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locations where sampling is necessary, will also assist in the identification of potential remedial
technologies.'
A generic conceptual site model diagram taken from the RI/FS guidance Is presented as figure 2-1. This
may be used as a starting point, although other effective formats, pictorial or graphic, are possible, for
example figure 2-2 and 2-3 here. The generic model should be modified to include as much site specific
Information as possible. Text accompanying the diagram should be sufficient to address specific sources
and receptors at the site.
2.3 Preliminary Remediation Goals
Part B of the RAGS HHEM, 'Development of Risk-Based Remediation Goals,' (EPA 1991e) will address the
need for early consideration of risk-based dean-up numbers. It will present simplified equations for
calculating these Preliminary Remediation Goals (PRGs). The Regional Policy on Conduct of RI/FS (EPA
1990s) also emphasizes that preliminary remedial action objectives be developed at the Initial scoping group
meeting.
The risk assessor should calculate and present a table of 'risk-based concentrations' and 'risk at ARARs,'
for use in discussion of PRGs at the scoping meeting. The primary function of the completed PRG table will
be to anticipate the range of risk-based concentrations that may become goals for site dean up action.
Early consideration of these numbers allows planning and evaluation of remedial alternatives to begin before
the remedial investigation report and baseline risk assessment are complete. It is expected that the PRG
table will also be referred to by managers and technical personnel at various stages of the RI/FS process,
for various purposes. An important use is evaluation of adequacy of analytical methods to provide data for
risk assessment: method detection/quantitation limits can be compared to risk-based concentrations. (See
section 2.5.2.) Also, as Rl data becomes available, actual concentrations of contaminants in site media can
be compared to risk-based concentrations to identify contaminants of concern for sampling In subsequent
phases. The risk-based concentrations will also be used in screening contaminants for the baseline risk
assessment.
Sections 2.3.1 through 2.3.5 below are a summary of the procedure for calculating and presenting risk-
based concentrations based on human health. Equations for these calculations can be found in Appendix
I. PRGs for ecological effects can also be developed, according to site-specific criteria. Although applicable
or relevant and appropriate requirements (ARARs) are not part of the baseline risk assessment, risk
associated with chemicals at concentrations specified in potential ARARs is information that may be
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EXAMPLE CONCEPTUAL SITE MODEL
RECEPTOR
PRIMARY
SOURCES
Drums
and
Tanks
Lagoon
Structures.
Drums. Tanks.
Lagoon
f
F
1
>
\
\
\
^
/
,
>RIMARY
RELEASE
MECHANISM
Spills
IniUlratlorv
Percolation
Overtopping
Dike
I
1
]
/
!
IECONDARY
SOURCES
Soil
SECONDARY
RELEASE
MECHANISM
Dust and/or
_^. Volatile
_ Emissions
iniU)T81IOfV
M.
otofm-
Runoll
+•
PATHWAY
Wind
Ground Water
ounoct
lA/atnr anrl
Sediments
i
*
_^
EXPOSURE
ROUTE
IngctUon
Inhclilton
Dermal
conlacl
Ingtidon
conlacl |
IngciUon
Muladon
Owmal
oonlacl
IngMUon
Inhclatton
Owmil
Uwmal I
contact 1
HUM
ATM
BMWwiU
•
I«
•
•
•
•
•
IAN
Slto
VWtofi
•
%
•
•
f)
•
BIO
T*rr«sM*l
•
•
•
•
•
TA
AquOc
•
•
-------
Ingestlon.
Dermal Contact.
Bloconcentratton
00
Sediment! —\r—,,
Ingestion,
Inhalation,
Du«t. »"™\
VblatllUatlon. Contact.
landfill Ga» D""ct,
Contact
lng*stk>n,
Dermal
Contact,
— Inhalation
Surface
Runoff
LEGEND
LandfUl Cont*nti
Eipoiur* taut*
Figure a 2
SCHEMATIC OF CONCEPTUAL LANDFILL SITE
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RECEPTORS AND
SOURCE RECEIVING MEDIA MIGRATION PATHWAY EXPOSURE MEDIA ROUTES OF EXPOSURE
PLATING
RESIDUAL PESTK
EXPOSURE PATHWAYS POTENTIALLY COMPLETE UNDER EXISTING CONDITIONS
SITE VISITORS
• Dermal contact
• InoesBonvla
hand-to-mouth contact
SITE WORKERS. SITE
RESIDENTS
• Inhaladon
1
SUBSURFACE SOILS BY PRECIPITATION ,
VIA SEPTIC SYSTEM INFILTRATING THE GROUND
LEACH BED
MIGRATION OF LIQUID
RESIDENTIAL AND
GROUNDWATER
• tagestion as drlnMng water
TO GROUNDWATER
-mr~ .- SURFACE ~OIL= » unur » "UnfACC SOILS » SITE WORKERS AND SITE
• Donnal contact
• IngesVon via hand-to-mouth
contact
mm,^o - SITE VISITORS. AND
NEARBY RESIDENTS '
• Inhalalon
FIGURE 2-3
ZR7050
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EPA Region 10
August, 1991
important in risk management decisions. It is convenient to have the risk assessor calculate and present
these numbers together with the risk-based concentrations.
Steps In Development of Preliminary Remediation Goals:
- List Expected Contaminants
- Identify Potential ARARs
- Assemble Toxicity Information
- Calculate 'Risk at ARAR'
- Calculate "Risk-based Concentrations'
- Present Information in a Table
Risk-based concentrations and risk at MCLs/MCLGs for chemicals on the Target Compound List and Target
Analyte List (TCL/TAL) can be found on tables in Appendix II. These were calculated according to standard
default exposure factors and the procedure below. If all •expected contaminants* at a site are Included on
the TCL and TAL, the values in Appendix II can be used for PRG discussion at the scoping stage. Data in
Appendix II is believed to be correct as of August, 1991, but 100% accuracy is not guaranteed. (Please
inform Region 10 risk assessment staff If you find any errors.) To insure that calculations are correct and
toxicity values and MCLs are current, an independent check for accuracy should be made, using the original
sources for toxlctty reference values, for expected contaminants for each site. Time invested In checking
toxicity information will not be wasted, because current toxicity information from the original sources wBI be
needed for the baseline risk assessment
Project managers and other staff should be aware that the risk-based concentrations presented at this stage
are preliminary. Changes may occur if new or revised toxicity information is obtained, and/or If site-specific
modifications in exposure assumptions are appropriate. Consideration of cumulative exposures to multiple
pathways and contaminants may affect risk-based numbers. Risk-based concentrations for soi are
particularly susceptible to change, because assumptions about human exposure to contaminants in soil
depend on several site-specific factors. SoO characteristics, geological and meteorological conditions at the
site, as well as chemical and physical properties of contaminants affect their fate and transport These
factors, along with site use, determine the relative importance of various routes of release and exposure
pathways (release to air, migration to groundwater, incidental ingestion, dermal contact) in determining
risk-based goals for sol. Results of the ecological risk assessment may affect risk-based goals.
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EPA Region 10
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2.3.1 Ust Expected Contaminants
The first step In developing PRGs Is to assemble a list of potential site-related contaminants. Based on
Information about the site use history, and on analytical results from Site Investigation, Preliminary
Assessment, or other sampling efforts prior to the HI, a list of chemicals expected or known to be present
can be compiled. Resource materials identifying contaminants expected to be associated with specific
Industries or sources can be consulted. (Resources include Appendix II of the Data Useabllity Guidance
(EPA 1990D) and guidance for specific categories of sources.) A written discussion of site Information used
In compilng the list of expected contaminants should be provided somewhere; the discussion may be part
of the scoping document or conceptual site model, or may accompany the table of PRGs. The list of
expected contaminants may be lengthy for sites with complex sources. Chemicals may be added to or
deleted from the list as more information becomes available during the Rl.
2.3.2 Identify Potential ARARS
Chemical-specific standards for soil, water, and air, as specified in federal or state regulations that may
become ARARs, can then be identified for each expected contaminant (ARARs guidance is provided In EPA
1988a). In the interest of limiting effort during scoping, the RPM may determine that identification of the
obvious federal standards, Maximum Contaminant Levels and Maximum Contaminants Level Goals (MCLs
and MCLGs) for water and Ambient Water Quality Criteria (AWQC) for surface water, is sufficient at this
stage. Note that ARARs under the Washington State Model Toxics Control Act (MTCA) (Wash. Dept of
Ecology. 1991) include some concentrations defined in the regulation, and some concentrations calculated
using toxteity information.
2.3.3 Assemble Toxlcfty Information
Toxlcity reference values for human health risks will be needed to calculate PRGs. Reference doses (RfDs),
inhalation reference concentrations (RfCs), carcinogen potency factors ("slope factors'), and Inhalation unit
risks wfll then be compiled for all contaminants identified in the first step. Toxteity values can be sought
using the Integrated Risk Information System (IRIS; EPA 1991C) and Health Effects Assessment Summary
Tables (HEAST; EPA 1991b). and the heirarchy of sources discussed in section 4.3.1 of this Region 10
guidance. The risk assessor should Identify expected contaminants for which toxteity data Is not readily
available, and should submit a list of these to EPA Region 10 risk assessment staff, who will contact EPA
Environmental Criteria Assessment Office, Superfund Technical Support Center (ECAO) to request additional
information. These requests should be made as early in the process as possible to allow adequate time for
toxicity values to be developed for the baseline risk assessment
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EPA Region 10
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2.3.4 Calculate "Risk at ARAB* and "Risk Based Concentration-
Human health risk at ARARs Is calculated by treating ARAR concentrations as exposure point concentrations
in risk equations, using standard default exposure factors. Risk-based concentrations for each contaminant
are calculated using rearrangements of the same equations. For this step, the concentration corresponding
to a target risk of 10"* and KT* for carcinogens, and hazard quotient of 1 for non-cancer effects, Is
calculated. See Appendix I for specific equations.
2.3.5 Present PRG Information in a Table
Results of the development of PRGs should be summarized in a tabular format Separate tables for each
medium (sol, groundwater, surface water, and sediment) are suggested. (Information pertaining to human
health and ecological risk can be incorporated in the same presentations, If appropriate.) Sources of data
must be cited. See Appendix II for an example format
2.4 Exposure Scenarios and Pathways
The development of the conceptual site model will provide a basis for preliminary identification of exposure
scenarios to be evaluated in the baseline risk assessment RAGS HHEM (EPA 1989d), chapter 6 and
Standard Default Exposure Factors (SDEF; EPA 1991g) provide guidance on exposure scenarios and
pathways. Also, see section 4.2 of this regional guidance for discussion of selection of exposure scenarios
and pathways.
A written presentation of exposure scenarios and pathways that will be evaluated in the risk assessment
should be prepared during RI/FS planning. The exposure scenarios and pathways will be used in
developing the work plans so that risk assessment data needs are addressed. This presentation can take
the form of a table or chart with accompanying notes or text presenting reasoning for Including and
excluding various pathways. Discussion of exposure scenarios should be accompanied by site maps
showing locations of sources and receptors, or can refer to maps in the scoping report or work plan.
Identification of exposure scenarios and pathways at this stage In the process may be detailed, or may be
more general, depending on the amount of information about the site available from the scoping process.
Scenarios and pathways may be modified as more information is collected during the Rl. The final version
the exposure scenarios and pathways presentation will appear again in the exposure assessment section
of the baseline risk assessment
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EPA Region 10
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2-5 Consideration of Risk Asseaamant Data Neada In tha Work Plan
Sampling and analysis activities undertaken during the remedial .Investigation should provide adequate data
to evaluate all appropriate exposure pathways for the risk assessment The sampling plan should be
designed with all data uses, including risk assessment, In mind.
2.5.1 UM of Sampling Data for the Risk Assessment
The work plan should show that the data needed to evaluate each exposure pathway Identified for the site
will be collected. In the section of the work plan that the discusses the risk assessment, the association of
each pathway with specific samples should be spelled out. The information that should be provided would
answer the following types of questions: Will groundwater concentrations be averaged over time for risk
assessment? If so, how many rounds of data will be collected? Will sol samples be averaged or
composited to describe an area? Will exposures to soil be considered using samples taken at the surface,
at depth, or both? Were locations for soil samples selected using a random, systematic, or purposive
design? »
For pathways that will be evaluated using estimates of potential release and/or models of fate and transport,
specific models that have been selected for use at the site should be identified In the work plan. (Superfund
Exposure Assessment Manual (SEAM) (EPA 1988e), Air/Superfund National Technical Guidance (EPA 1990a),
and other EPA documents provide guidance on selection of models.) Physical data needed for model(s),
such as meteorological data or characteristics of soils, should be identified, and appropriate data collection
activities Included in the sampling plan.
2.5.2 Analytes and Detection Limits
Selection of analytical methods involves consideration of many site-specific factors, including site use history
and expected contaminants. Judgement of the RPM, chemist and risk assessor will be used to evaluate
advantages and disadvantages of available methods. Appendix III of the "Data Useabillty Guidance1 (EPA
1990b) compiles information on various analytical methods and associated detection limits, listed by
chemical. Information developed during the scoping process, particularly PRGs for expected site
contaminants, wfll be consulted when choosing methods. For samples that will be used to establish
exposure point concentrations for risk assessment, results are more useful if detection limits meet risk-
based concentrations. The adequacy of detection iimits should be evaluated in the work plan by presenting
a table listing expected contaminants and comparing the method detection or quantttation limit for each.
compound with the appropriate risk-based goal for that chemical in that medium. This does not mean that
every sample must be analyzed with the method achieving the lowest possible detection limits. Issues of
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EPA Region 10
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cost and other data uses will affect choice of methods. At locations where concentrations are known or
expected to be high, the most sensitive method may not be necessary.
i
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EPA Region 10
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3.0 Preliminary Data Analysis
Extensive discussion on evaluation of data for use In risk assessment Is provided In chapter 5 of RAGS
HHEM (EPA I989d) and in the Data UseabUity Guidance (EPA 19905). Judgement regarding the needs of
a particular project should be used In interpreting this guidance. The discussion below highlights some
Important Issues.
For many Superfund sites, the number of chemicals detected In site media is large. It will usually be useful
to focus the baseline risk assessment on important chemicals. Elimination from the baseline risk assessment
of common laboratory contaminants, natural background elements, and chemicals presenting little risk
should be conducted in a systematic manner, as presented in 3.2 and 3.3 below, or using other acceptable
rationale approved by EPA Region 10. It is suggested that this step be carried out in advance of the
baseline risk assessment
3.1 Scheduling of Risk Assessment Deliverable* Purina Preliminary Data Analysis
Risk Assessment Deliverables During Preliminary Data Analysis
- Evaluation of Laboratory Contaminants and Natural Background (3.2)
- Risk-based Screening of Contaminants (3.3)
- Revised Conceptual Site Model/Exposure Pathways (3.5)
Section 3 describes the content of deliverables that will be submitted after Rl sampling results are available
but before the RI/FS and baseline risk assessment are submitted. All of the information called for in section
3 can be compiled and submitted to the RPM in one package, along with other data reports, if convenient
The timing and length of these deliverables will vary depending on the needs of the site. If additional
sampling events will be planned based on results of early rounds, timely reporting of risk-based screening
and revised exposure scenarios will be important. These should be submitted as soon as possible after data
are available. Risk-based screening can also be used to identify unusually high risks, where the RPM might
want to consider early action. Documentation of the logic used In reducing the number of contaminants to
be carried through the baseline risk assessment must be included in the final risk assessment. This can be
accomplished by including a copy of the risk-based screening and other deliverables from the preliminary
data analysis as an appendix to the baseline risk assessment.
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EPA Region 10
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For some projects the preliminary data analysis deliverabies may be omitted entirely. This may occur when
previously agreed-upon schedules do not allow for additional rounds of document review. Also, some of
the interim deliverabies called for below may not be necessary if no additional sampling Is anticipated, and
if the conceptual site model and Identification of exposure scenarios and pathways In the work plan are
acceptable and do not require revision. In these cases, the information called for in section 3 below will be
submitted as part of the baseline risk assessment The Region 10 risk assessment staff does not
recommend skipping the 'Risk-based Screening* and 'Revised Conceptual Site Model/Exposure Pathways'
interim steps. The potential problem is that if risk-based screening and specific exposure and toxtelty
Information Is not submitted and approved, errors or gaps In these will be carried through the baseline risk
assessment In that case, time spent in preparation of the baseline risk assessment may be wasted, and
delays could be encountered in revisions of the baseline.
For PRP-lead sites, again the specifics of the schedule may be different. Rl sampling results wfll need to
be provided as a deliverable to the risk assessor before he or she can proceed with the risk assessment data
analysis tasks.
3.2 Evaluation of Lab Contaminants and Natural Background
3.2.1 Lab Contaminants
Contaminants introduced into samples during laboratory analysis should not be considered among site risks.
As discussed in RAGS HHEM section 5.5, common laboratory contaminants include acetone, 2-butanone,
methylene chloride, toluene, and phthalate esters. These may be eliminated from the risk assessment as
indicated in RAGS HHEM page 5-16:
'if the blank contains detectable levels of common laboratory contaminants, then the sample results
should be considered as positive results only if the concentrations in the sample exceed ten times
the maximum amount detected in any blank.'
3.2.2 Natural Background
RAGS HHEM page 5-19 states:
'If inorganic chemicals are present at the site at naturally occurring levels, they may be eliminated
from the quantitative risk assessment-comparison with naturally ocurring levels is applicable only
to inorganic chemicals...'
Determining whether detected concentrations of inorganics represent natural background In a medium Is
a site-specific Issue. Appropriate number and locations of background samples are determined by the RPM
and geologists. Interpretating site data compared to background data should be discussed among project
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EPA Region 10
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\
managers and scientists and addressed In the Rl report. If It Is unclear at the time the preliminary data
analysis is conducted whether inorganics are natural or anthropogenic In origin, they should be carried
through the baseline risk assessment, with further consideration of the issue of background In the FS.
Although In general natural background elements may be excluded from the baseline risk assessment, at
some sites the risk from natural background elements may be included in the baseline risk assessment,
presented separately from the site-related risks, at the option of the RPM.
! Contaminar
The number of contaminants considered In the baseline risk assessment may be further reduced using a
conservative risk-based screening. For risk assessments submitted to Region 10, a screening process
comparing concentrations to risk-based concentrations as outlined below Is suggested (instead of
•concentratlonAoxIdty screen' as In RAGS HHEM section 5.9.5). Site-specific screening criteria different
from below may be used If approval of the RPM and risk assessment reviewer are obtained.
3.3.1 Risk-Based Screening: Suggested Approach
Risk-based Screening of Contaminants
- List maximum concentration of each chemical in each medium.
- Compare to risk-based concentration
- Eliminate chemicals if:
maximum detection for water <. 10"* cancer risk screening value
.< 0.1 hazard quotient screening value.
maximum detection for sol <. 10~7 cancer risk screening value
.<.0.1 hazard quotient screening value.
- Carry remaining chemicals through baseline risk assessment.
The screening of contaminants should compare the maximum concentration of each contaminant detected
at the site to a risk-based concentration calculated using a conservative target risk, calculated based on
standard default exposure factors. The target risks specified here were chosen based on lower end of the
10~* to 10"* "risk range" specified in the NCP (EPA 1990d). The assumption used Is that if no single sample
exceeds a concentration representing a human health risk concern, total exposure to the contaminant from
the site wll not be of concern. The 'screening risk" deliverable should include tables clearly showing
comparisons used, with columns showing risk-based screening concentration and maximum concentration
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EPA Region 10
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on site in each medium for each contaminant eliminated from the risk assessment The risk assessor may
also want to list toxic endpoints for each contaminant eliminated, to Insure that cumulative hazard Is not
overlooked.
For water, the default screening level at which carcinogenic contaminants can be eliminated Is 10"* risk,
calculated as in Appendix I. For son, contaminants should be included In the baseline risk assessment If
the maximum concentration exceeds 10~7 based on the sol ingestton pathway. This lower target risk
number is used in screening for soil because additional pathways that are not accounted for by the
calculations in Appendix I, dermal or inhalation, could result In significantly higher exposures for some
chemicals. For non-carcinogens, because multiple pathways and multiple contaminants may result hi
cumulative effects, the screening concentration should be 0.1 hazard quotient Chemicals exceeding these
screening concentrations should be carried through the baseline human health risk assessment Note that
the risk-based screening criteria for carcinogens in water would be the same risk-based concentrations
shown In Appendix II. The more conservative screening criteria, 10~7 risk for soil ingestton and 0.1 hazard
quotient for non-carcinogens, differ from numbers presented in Appendix II by a factor of 10, In other words
moving the decimal point one place to the left
If contaminants are detected that were not part of the list compiled at the project planning stage, toxicity
data will have to be sought and risk-based concentrations calculated as In 2.2.3 and 2.2.4 above, and
Appendix I. For chemicals that are detected in site samples for which no toxicity values are available, and
therefore no risk-based concentrations can be calculated, Region 10 and ECAO should be contacted If this
has not already been done.
3.3.2 Chemical-Specific Screening Criteria
If chromium, cadmium, elemental mercury, or carcinogenic forms of nickel are present as contaminants In
soH, they should not be eliminated based on the soH ingestton screening criteria. This Is due to the special
issue of their inhalation toxicity being more of concern than ingestton, according to current EPA toxicity
assessment The same concept would apply to other contaminants having disproportionately high Inhalation
or dermal toxicity.
Six inorganic constituents which are often analyzed for but which are not associated with toxicity to humans
under normal circumstances are aluminum, calcium, magnesium, potassium, iron and sodium. No
quantitative toxicity information is available for these elements from EPA sources. These six elements can
generally be eliminated from the human health risk assessment at the screening stage based on qualitative
judgement
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EPA Region 10
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3.4 Risk-based Screening of Contaminants: Ecological
("reserved")
3.5 R«vi«ad Conceptual Stt« Model/ExDO«urePithway«
The conceptual site model and exposure scenarios and pathways planned for the risk assessment should
be revisited at this stage. Depending on the amount of Information previously available and new Information
obtained from sampling data, a revised conceptual site model and presentation of exposure scenarios may
be needed. If only general Ideas were presented at the scoping stage, more specifics should be presented.
If new information causes significant changes, revisions should be submitted. If additional phases of
sampling are planned, revised information on exposure should be considered In the new work plans.
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EPA Region 10
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4.0 Baseline Human Health Risk Assessment
4.1 Scheduling of the Baseline Risk Assessment
The baseline human health and ecological risk assessments (section 4 and 5) may be submitted as part of
the Rl report, or as separate documents.
4.2 Exposure Assessment
The degree of "protecttveness" or "conservatism" that will be used in exposure assessment for Superfund
risk assessments has been the subject of considerable discussion. In order to have consistency in risk
assessments nationwide, Superfund program guidance descibes in some detail the approach that will be
used. RAGS HHEM Part A (EPA 1983d), Chapter 6, provides guidance on development of reasonable
maximum exposure (RME) scenarios, and the Standard Default Exposure Factors (SDEF) (EPA 1991g) gives
specific exposure factors, for example drinking water ingestion rate, that should be used as defaults for all
sites. These factors wUI seldom be subject to modification. However, certain aspects of the exposure
assessment, particularly quantification of absorption of chemicals from soil and estimation of exposure point
concentrations using modeling or other predictive approaches, have not been 'standardized' and will require
site-specific data and judgement. The use of simplified, conservative (protective) assumptions is a tool of
an Iterative risk assessment approach. Where this or other EPA guidance proposes simplified or screening
calculations to evaluate a particular pathway of release or exposure, these are often subject to refinement
in the next iteration, if necessary. For example, if conservative "worst-case' assumptions about release of
contaminants from sofl to air are used in human exposure calculations, and results show that risks are well
below risk-based goals and levels of regulatory concern, more complex or detailed models would not be
necessary. If results of the same calculations show risks of concern, additional effort and collection of site-
specific data may be justified.
4.2.1 Selection of Exposure Scenarios
The conceptual site model and the exposure scenarios and pathways should be presented as early in the
RI/FS process as possible, to insure that appropriate data collection is planned. Exposure scenarios are
revised as necessary as more information becomes available. Issues affecting selection of exposure
scenarios and pathways are discussed below.
The baseline risk assessment will consider risks under both current and future land uses. The land use
scenarios most commonly evaluated in Superfund risk assessments are residential or industrial land use.
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However, scenarios in addition to residential and Industrial use can be developed In consideration of the
location, size, and current and potential uses of the affected area. Scenarios may include fishing, agriculture,
or recreational or other occasional activities, as appropriate. Evaluation of multiple scenarios (including
residential, Industrial, and recreational land use) will be appropriate for many sites.
Region 10 recommends that a residential land use scenario should be evaluated as a potential future use
in the baseline risk assessment for most Superfund sites. The reasons for making the general
recommendation that residential land use should be evaluated Include the following:
1) Predicting the likelihood of future changes in land use can be uncertain. For example, anticipating
which miltary bases may face closure in the future Is beyond the scope of a Superfund risk
assessment; the residential scenario should be evaluated as a "what IT question.
2) For sites where institutional controls or access restrictions wHI be implemented to prevent future
residential land use, evaluation of the residential scenario in the baseline risk assessment provides
justification for this type of action.
3) The residential scenario usually provides the most conservative estimate of exposures at a site, In
other words the highest estimate of risk. If results were low risks, this would provide the most
comfortable basis for a no-action decision, and confidence that Superfund could "walk away" from
the site.
Including residential land use in the risk assessment does not dictate that the site will be cleaned up for
residential use. Presentation of results of quantitative evaluation for more than one scenario In the baseline
risk assessment for a site gives decision-makers more information when considering various risk
management options. During the FS process, managers will determine which land use assumptions wll be
the basis for deciding whether remedial action is warranted, and the basis for selection of final remediation
goals.
However, at some sites or operable units the RPM may determine that it Is not appropriate to evaluate
residential land use in the risk assessment For specific sites where the RPM believes that future residential
use is highly unlikely, this scenario may be given less effort in the risk assessment, or may be eliminated.
If evaluation of a residential scenario for such a site would necessitate additional sample collection, the
benefits of the information should be weighed against the costs of collecting It before proceeding. The level
of effort devoted to evaluating residential land use may be limited through the use of pre-existing sample
data, standard exposure assumptions, and 'screening* pathways.
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4.2.2 Select Exposure Pathways
Within each exposure scenario, specific pathways that will be evaluated will be selected based on slte-
spedfic characteristics and on general considerations outlined below and in table 4-1. Soil and water
Ingestion pathways are the minimum that should be considered. After comparing contaminant
concentrations to screening concentrations based on these pathways, as discussed in section 3 above,
multiple pathway exposures should be evaluated, as outlined in table 4-1, for each 'contaminant of concern'
remaining to be carried through the baseline risk assessment
4.2.2.1 Pathways of Exposure to Soil
For contaminated soB, incidental ingestion of soil should always be evaluated. Assessment of exposure
through dermal contact with soil requires chemical-specific absorption Information. Absorption data for
organtes should be sought in the Guidance for Dermal Exposure Assessment (EPA 1991 d). If no absorption
data for contaminants of concern (or analogous compounds) Is available, dermal exposure should be
addressed qualitatively. Quantitative information on dermal absorption of inorganics from sol Is not
available. Dermal contact with contaminants that have toxic effects at the skin surface, for example certain
metals, can be evaluated quantitatively if information can be obtained. Inhalation of volatile and paniculate
contaminants released from soil to air should be evaluated, again usually limiting the evaluation to
contaminants of concern identified at the screening stage. Evaluation of air pathways can be particularly
important for sites where waste or contaminated soil is left In place, with direct contact prevented through
access restrictions. Other pathways of exposure to contaminants in soil, such as uptake into plant or animal
food products, will be evaluated less frequently. Site charactisttes which would make consideration of food
chain pathways important would be:
- current residential site use
- large areas of contaminated soil located in agricultural area
- contaminants known to be taken up into plants or animals at potentially significant levels, for
example cadmium and PCBs.
Decisions to include food chain pathways in should be made in consultation with the RPM and the Region
10 risk assessment contact
4.2.2.2 Pathways of Exposure to Grouhdwater
If contaminated potable water is present, or contaminants may potentially affect potable water, exposure
through Ingestion of water, and through inhalation of voiatHes released from household water use, should
be evaluated. Dermal contact during bathing should be evaluated for organic contaminants of concern using
permeability coefficient data available in the Dermal Exposure Guidlines (EPA 1991d).
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Table 4-1. General Approach for Selection of Exposure Pathways
Contaminated
MocHurn
Ground Water
Surface Water
andSedbnant
Exposure
Scenario
Residential use
as potable water.
Industrial use
as potable water.
Residential or
Industrial use
as potable water.
Recreational or
subsistence
flshing.
Recreational or
trespasser.
Potential
Exposure
Pathway
Ingestton of water
Inhalation of
volatUes
Dermal contact
with water
Ingestton of water
Inhalation of
volatUes
Dermal contact
with water
Same as for
ground water
Consumption of
fish/seafood
Ingestion of water
Evaluate
In Risk
Screening?
Yea
Yes, if volatiles
present
•
A
*
*
decision.
•
Evaluate
in Baseline
Risk?
Yes
Yes, If volatttes
present
Yes, for organic
contaminants of
concern.
Yes
Slte-spedflc
decision.
Site-specffic
dociBJon.
Ste-speclflc
decision.
•
Dermal contact *
with water
Ingestton of *
sediment
Dermal contact with *
sediment
Sol Residential Son Ingestton Yes
Dermal contact *
with soil
Inhalation of paniculate/ *
volatiles from son
Residential or Consumption of *
agricultural produce, meat milk.
Industrial Sol Ingestton.
Dermal contact *
with soil.
Inhalation of paniculate/ *
volatiles from sol.
Yes
Yes, for
contaminants
of concern.
Yes, tor
contaminants
of concern.
Site-specific
decision.
Yes
Yet, for organic
contaminants
of concern.
Yes, tor
contaminants
of concern.
may be considered if srte-specrfic screening criteria are developed.
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EPA Region 10
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4.2.2.3 Pathways of Exposure to Surface Water and Sediment
For contaminated surface water and sediment, potential for human exposure varies greatly depending on
the size and location of the water bodies. For sites that have small water bodies or that are in remote
locations, exposure pathways can be limited to incidental ingestton for a child playing or a trespasser.' If
these exposures appear to be of concern, however, or for some sites with potential for recreational use,
dermal contact should also be included. Fish or seafood consumption pathways will be an Important
consideration at sites where large water bodies are affected by contamination.
4.2.3 Calculating Exposure Point Concentration from Sampling Data
4.2.3.1 Calculating the "RME" Concentration
HHEM Section 6.4.1 states that where results from several samples will be combined to estimate exposure
point concentration, the appropriate calculation is the ninety-five percent upper confidence limit (95% UCL)
on the arithmetic average (except when the 95% UCL exceeds the maximum) of concentrations that would
be contacted by the *RME* individual. Averaging and statistical treatment of data is correct only for samples
that were collected with an appropriate random or systematic sampling design. Further guidance on
developing the TIME" exposure concentration is under development by EPA and should be available within
6-9 months.
4.2.3.2 Grouping Samples
Combining data to evaluate exposures must take into account spatial distribution of contaminants, human
activity patterns, and potential fate and transport. A Section of RAGS HHEM which summarizes some
exposure pathways issues is 6.5.1, which includes the following guidance:
"...The manner in which the data are summarized depends upon the site characteristics and the
pathways being evaluated. It may be necessary to divide chemical data from a particular medium
into subgroups based on the location of sample points and the potential exposure pathways. In
other instances, as when the sampling point Is an exposure point (e.g., when the sample is from an
existing drinking water well) It may not be appropriate to group samples at all, but may be most
appropriate to treat the sample data separately when estimating intakes."
If more than one source exists at a site, it may be appropriate to evaluate exposures for a separate 'RME*
individual for each source area, because the sou or water at one source area may present distinct exposures
and risks that are not present elsewhere on site. However, for a site with multiple source areas It is also
possible that release of contaminants to air or water from various sources will affect the same down-wind
or down-gradient receptor, so the cumulative exposure should also be evaluated. It is useful to Identify the
location of contaminant concentrations of each contaminant in sol and water on a map to evaluate whether
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EPA Region 10
August, 1991
!*
maximum risks from each do or do not coincide In location. Needs of decision-makers will be a factor In
determining whether to evaluate source areas together or separately.
Groundwater samples from a single well location over time should generally be used to represent the 95%
UCL average concentration that would be contacted by the RME individual at that location. Future exposure
point concentrations estimated by modeling may be used In the risk assessment If the RPM and technical
staff determine that modeling te appropriate.
Surface soi.sample data should be used to represent the 95% UCL average concentration for an area the
size of a yard for residential use scenarios. The risk assessment should Identify whether the concentrations
used for calculations are typical of large areas of the site, or represent a "hot spot' If contaminant
concentrations vary significantly over the site area, it may be appropriate to calculate several different
exposure point concentrations, using a subset of samples for each. For sites where future construction of
residences is possible, the exposure assessment should consider concentration at the current surface, and
also that construction activities could result In excavation of son, and distribution of this soil at the surface.
Exposure calculations would use the 95% UCL average of samples to an appropriate depth for this case.
4.2.3.3 Background
The RPM may request that exposures and risks from on-site sources be summed separately from natural
and anthropogenic background in the risk assessment Treatment of "background" in the risk assessment
wil depend on ability to distinguish site-related contaminants from other chemicals detected, and on risk
management issues.
4.2.3.4 Non-Detects
Where a specific contaminant has been detected at some locations on a site, but not others, or has been
detected In past sampling events but not in current samples, the contaminant should be assumed to be
present In the 'non-detecf sample at one-half the sample detection limit This approach Is specified in
section 5.3.3 of HHEM. However, judgement should also be used in evaluating of non-detects; if high
detection limits for certain samples would result in bias using the "half detection limit" assumption, other
interpretation may be appropriate, for example the following:
- Calculate RME concentration using one-half the detection limit for non-detects
- Compare the result with the maximum detected concentration. Use the lower of the two values
as the exposure point concentration for the risk assessment
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EPA Region 10
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4.2.4 Predicting Exposure Point Concentration Using Modeling/Estimates
Appropriate publications (SEAM (EPA 1988e), NTGS (EPA I990a), etc.) should be consulted for guidance
on use of fate and transport modeling for risk assessment The Standard Default Exposure Factors directive
(EPA 1991g) does not comprehensively review methods of evaluating contaminant fate and transport or
uptake into the food chain. Although some examples of approaches or models for development of predicted
exposure point concentrations are mentioned in the directive, their use is not being mandated. In addition
to the cited references, continue to consult national guidance and the published literature for the most
appropriate methods for predicting contaminant concentrations in air, in agricultural products, and in fish.
Examples of approaches to predicting uptake of chemicals Into agricultural products and fish can be found
in recent documents from EPA Office of Research and Development (EPA 1988C, EPA 1989a, EPA 1990c).
An acceptable default approach for estimation of indoor inhalation exposure to vdatDes released from
contaminated water is to:
- Include as "volatiles* all organic contaminants with Henry's constant (unitiess) > KT* and molecular
weight <200.
- Estimate indoor air concentrations by assuming that they will be related to concentration in the
water supply according to a coefficient of 0.5 l/m1 (EPA 199le).
4.2.5 Contact Rate, Exposure Frequency and Duration
Sources of Exposure Factors for Superfund Risk Assessment
Exposure Pathway
Ingestion of Water
Indoor Inhalation of Volatiles
Dermal Contact with Water
Sol Ingestion
Dermal Contact with Soil
Inhalation of Partlculate/Vdatiles from
Consumption of Produce, Meat, Milk
Consumption of Fish/Seafood
Exposure Factors
RME Average
SDEF Region 10
SDEF Region 10
Region 10 Region 10
SDEF Region 10
Region 10 Region 10
SoU SDEF Region 10
Site-Specific
Site-Specific
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EPA Region 10
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The Standard Default Exposure Factors, (EPA I99lg) compiled by the Superfund program, Is the source
for RME exposure factors for Superfund risk assessments. For 'average' exposure factors, and for pathways
not addressed In the SDEF guidance, Region 10 has provided recommended values, mostly selected from
the Exposure Factors Handbook (EPA 1989b) or Dermal Exposure Guidelines (EPA 1991d). For convenient
reference, exposure factors from both SDEF and Region 10 are presented together In Appendix III.
4.2.5.1 UM of Standard Default Exposure Factors
The supplemental guidance document entitled 'Standard Default Exposure Factors,' (EPA 1991g) provides
specific exposure factors which are to be used for Superfund Human Health Risk Assessments. The
standard default exposure factors (SDEF) are summarized on page 15 of the directive and in Appendix III,
table III-2, here. The values in the directive supersede the RME values presented In the January, 1990,
Region 10 'Statement of Work RI/FS Risk Assessment'
As stated on page one of the SDEF supplemental guidance,
the exposure factors presented in this document are generally considered most appropriate and
should be used in baseline risk assessments unless alternate or site-specific values can be clearly
justified by supporting data.'
Drinking water ingestion, soil ingestion, and inhalation defaults will apply to virtually all sites. The need to
evaluate consumption of homegrown produce, meat and milk, and consumption of locally caught fish will
be determined according to characteristics of each site. For these food chain pathways, it is also expected
that site-specific exposure values wUI usually be preferable to defaults. Assessment of dermal exposures
is not discussed hi the directive. The 'Guidance on Dermal Exposure Assessment* being developed by
ORD Exposure Assessment Group will address this pathway.
Questions regarding which exposure factors to use for risk assessments already in progress using the
January, 1990 Region 10 'Statement of Work* should be directed to the RPM and regional risk assessment
contact person. To compare impact of using one set of exposure factors versus another, see 'Summary
Intake Factors' In table III-2.
4.2.5.2 Region 10 Default Exposure Factors
Exposure factors for the dermal pathway, which is not addressed In the SDEF, for the RME, and for all
pathways for average exposures, are presented In Appendix III, table 111-1. Although regulatory decisions
for Superfund sites wfll be based on risks at RME exposures, average exposure factors are presented here
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EPA Region 10
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for two purposes. Average exposure factors will be used for comparison In uncertainty analysis. Also,
average exposures wil be included in some RME scenarios, as stated In RAGS HHEM on page 6-47:
To calculate an exposure that Is a reasonable maximum across pathways, It may be necessary to
combine the RME for one pathway with an estimate of more typical exposure for another pathway.'
When subchronic or acute exposures are evaluated, age-specific intake factors and body weights for
children should be used. Age-specific factors are presented In the Exposure Factors Handbook (EPA
1989b). RME exposure factors for the dermal pathway presented in Appendix III are recommended by
Region 10 based on the Dermal Exposure Guidelines (EPA I99ld).
4.3 Toxicfty Assessment
Toxictty assessment should be conducted as described in chapter 7 of RAGS HHEM.
4.3.1 Toxictty Reference Values
The heirarchy of sources for toxicity information is as follows:
1) Integrated Risk Information System (IRIS; EPA 1991C). On-line database. IRIS Is the preferred EPA
source for toxicity information. It provides RfD's and carcinogen slope factors that have been
reviewed and verified by agency-wide work groups. Supporting discussion and references also
appear in each chemical file. IRIS User Support (513-569-7254) can provide information about how
to access IRIS. IRIS is also available on PC-compatible diskettes from NTIS.
2) Health Effects Assessment Summary Tables (HEAST; EPA 1991b). (OSWER Directive No. 9200.6-
303. NTIS No. P890-921100.) Prepared by the Environmental Criteria and Assessment Office for
the Office of Emergency and Remedial Response. The HEAST tables provide a summary of all
currently available toxicity factors developed by ECAO, and a bibliography of Health Effects
Assessments and related documents. These documents contain supporting information for toxicity
values developed by EPA ECAO. Additional chemicals that do not appear in IRIS are included in
HEAST. The HEAST tables are revised quarterly. Effective In the second quarter, 1991 edition,
toxicity factors that appear in IRIS will no longer appear In HEAST.
3) Toxicity reference values developed by, or in consultation with, the EPA Superfund Technical
Support Center at the Environmental Criteria and Assessment Office (ECAO) In Cincinnati!,
(513)569-7300. Region 10 risk assessment staff should usually be contacted before calling ECAO.
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EPA Region 10
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4) ATSDR minimal risk levels (MRLs). These values are developed using an approach that Is consistent
with reference dose methodology. These are available for acute, Intermediate, and chronic
exposure durations and so are potentially useful for situations of short-term exposure, for which
verified RfDs seldom available. These numbers can be found in the ATSDR Toxlclty Profile
documents, in the Health Effects Summary section, in the text and/or on the •thermometer" chart
Concurrence with use of MRLs for a specific situation should be sought from Region 10 and ECAO.
4.3.2 ToxicKy Profiles
The baseline risk assessment (or an appendix) should Include a short toxlctty profile for each contaminant
of concern Identified In screening. See RAGS HHEM section 7.7 regarding the type of discussion of toxlclty
information for each chemical. These profiles should provide two types of information.
1) General toxlclty information, intended for the non-specialist reader. This discussion should be
concise and "non-technical,' or at least not too technical. ATSDR Toxicity Profiles are good sources
of general toxlclty information for many hazardous waste chemicals, and the Introductory sections
are good models of informative yet readable discussions of toxicity.
2) Summary of information used in developing slope factor or RfD (critical effect or target organ,
uncertainty factors, etc.) This can be very brief, referring the reader to IRIS or other original source
for details.
In some situations, more detailed toxicity profiles will be needed. At sites where potential exposures
resulting hi hazard quotients around one is an issue, additional discussion of the database supporting the
RfDs wfll be Important In addition to sources listed In 4.2.1 above, the published literature can of course
also be consulted and referenced for information for toxicity profiles.
4.4 Risk Characterization and Uncertainty Analysis
Combining exposure and toxicity data to characterize risks Is described in RAGS HHEM chapter 8.
Uncertainty analysis is discussed in RAGS HHEM sections 6.8. 7.6, and 8.4.1. Some frequently occurring
questions/issues are addressed below.
4.4.1 Risk Characteriatlon Using RfCs and Units Risks
For inhalation pathways, toxicity reference values are now being verified in units of concentration in air,
(mg/m3 or /ug/m3, Instead of mg/kg-day) so the RfC or unit risk will not fit into the equations on page 8-
6 and 8-11 of RAGS. For Superfund risk assessments, the approach that Is currently being recommended
by headquarters is to convert RfCs and Unit Risks to Inhalation RfDs and slope factors using 20m3/day
breathing rate and 70 kg body weight This mathematical conversion, and adjustment for Intermittent
29
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EPA Region 10
August, 1991
exposure patterns, Is not the Intended use of chronic RfCs. However, the magnitude of the adjustment for
the exposure frequency and duration in 'standard default* scenarios, 350 day/year for residential and 250
day/year for industrial, Is not great More detailed analysis of applicability of RfCs/Unlt Risks to site-specific
sources and exposure patterns can be presented If necessary for a specific chemical at a site.
4.4.2 Summary Tables
Summary tables of results should be prepared in which each risk or HI number is associated with a specific
scenario, exposure pathway and chemical. One or a few numbers do not characterize a site; multiple
scenarios are presented. See exhibits 8-2 and 8-3 in RAGS for sample format Although additional decimal
places should be carried through calculations, when final risk and HI estimates are presented they should
be rounded to one significant figure.
4.4.3 UncertalntyAnalysis
4.4.3.1 Qualitative Uncertainty Analysis
Qualitative discussion of uncertainties is expected for all risk assessments submitted to Region 10.
Uncertainties in the quantitative risk assessment process should be recognized, as discussed in the agency
guidelines. The RfD Background Document (EPA 1988d) provides perspective on Interpreting reference
doses, including the following:
the RfD is an estimate (with uncertainty spanning perhaps an order-of-magnitude) of a daily
exposure to the human population (including sensitive subgroups) that is likely to be without an
appreciable risk of deleterious effects during a lifetime...However, It should not be categorically
concluded that all doses below the RfD are 'acceptable' (or will be risk-free) and that all doses In
excess of the RfD are 'unacceptable' (or will result in adverse effects)' (EPA 1988d).
Slope factors for carcinogens are derived by the EPA, usually using the linearized multistage procedure.'
The Guidelines for Carcinogen Risk Assessment (EPA 1986) acknowledge that:
"the linearized multistage procedure leads to a plausible upper limit to the risk that is consistent with
some proposed mechanisms of carcinogenesis... The true value of the risk is unknown, and may
be as low as zero.'
However, because the risk assessment for a Superfund site is intended to support decision making within
a defined regulatory context, the risk assessor should clearly distinguish uncertainties Inherent in the risk
assessment process (i.e. toxicity values based on low-dose extrapolation from high-dose experiments), or
common to Superfund risk assessments (i.e. assumptions in standard default exposure parameters, lack of
data on dermal absorption from soil) from uncertainties specific to the particular project Discussion should
focus on site-specific uncertainties. These might include data gaps in site sampling, uncertainy In modeling
for fate and transport, uncertainty in assumptions about future land use, and data gaps for toxicity or
absorption information. After risks at RME are calculated for each pathway, It is possible to identify which
30
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EPA Region 10
August, 1991
chemicals, scenarios and exposure routes present risks of larger magnitude. Discussion of uncertainty
should focus on the more significant pathways and chemicals.
4.4.3.2 Quantitative Uncertainty Analysis
Semi-quantitative analysis of uncertainty in exposure assessment should be presented. The format
suggested by Region 10 Is evaluation of impact of average compared to RME values for exposure factors
and exposure point concentrations for pathways contributing most of the risk. If modeling has been used
to develop exposure point concentrations, sensitivity analysis for model input assumptions Is also
appropriate. Because decisions at Superfund sites are based on risks to the reasonably maximally exposed
Individual, as specified In the NCP (EPA I990d) and as defined by the associated guidance (RAGS HHEM,
SDEF), more sophisticated approaches to quantitative uncertainty analysis will usually not be used.
4.4.4 Summary and Conclusion*
The risk assessor and reviewer should devote some care to providing an effective and concise summary of
site risks, because this section will 'stand alone* for some persons Interested in the site who may read the
summary but not the rest of the risk assessment
Risk assessments containing unqualified statements such as:
•Risk from chemical XYZ in drinking water are unacceptable. Risks from exposure to sol are
insignificant..'
have sometimes been submitted to Region 10. Writers of Superfund risk assessments should avoid the use
of terms such as 'significant,' 'unacceptable,' or 'not of concern' In interpreting results, particularly If the
criteria for significance or concern are not dearly defined in the report- These terms imply conclusions
about whether remediation will be undertaken at the site; risk management should be discussed in the
Feasibility Study, not In the baseline risk assessment Preferred language would be something like:
•Risk from chemical XYZ in drinking water was calculated to be 9 x 10"4. For sod, total risk from all
contaminants was less than 10"'."
The risk assessment may cite the NCP (EPA I990d; see page 8848) or 'Role of the Baseline Risk* memo
(EPA 1991 h), and quote the language on the 'risk range' used in Superfund, if this is acceptable to the RPM.
31
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EPA Region 10
August, 1991
5.0 Baseline Ecological Risk Assessment
("reserved")
6.0 Risk Evaluation of Remedial Alternatives
Parts B and C of the Risk Assessment Guidance for Superfund, HHEM will provide guidance on calculation
of risk-based remediation goals and risk evaluation of remedial alternatives. However, because these
processes involve the integration of risk assessment with management and feasabBity concerns, specific
dellverables and level of effort will be determined according to needs of each site.
6.1 Scheduling of Risk Assessment Dellverables for the FS
Risk assessment tasks for the FS must be integrated in the FS process. The risk assessor will need to
provide risk-based concentrations, as developed during scoping or modified based on the baseline risk
assessment to engineers working on remedial alternatives. Engineers wPI need to provide estimates of time
to complete remediation, of expected treatment residuals, and of potential for releases during remedial
activities to the risk assessor, for evaluations of long-term and short-term risks. These pieces of Information
may be called for as separate dellverables at the discretion of the RPM. This would probably be necessary
for PRP-iead sites.
32
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EPA Region 10
August, 1991
7.0 References
Environmental Protection Agency (EPA). 1986. Risk Assessment Guidelines of 1986. Office of Health and
Environmental Assessment. EPA/600/8-87-045. (Also published in the Federal Register, September 24,
1986, 55 PR 33992-34054.)
Environmental Protection Agency (EPA), 1988a. CERCLA Compliance with Other Laws Manual. Interim
Final. Volumes. I and II. Office of Emergency and Remedy Response. OSWER Directive No. 9234.1-01
and 9234.1-02. EPA/540/6-89-009.
Environmental Protection Agency (EPA). 1988b. Guidance for Conducting Remedial Investigations and
Feasibility Studies Under CERCLA Office of Emergency and Remedial Response. OSWER Directive No.
9355.3-01.
Environmental Protection Agency (EPA). 1988c. Estimating Exposures to 2.3.7.8-TCDD. Office of Health
and Environmental Assessment. EPA 600/6-88/005A.
Environmental Protection Agency (EPA). 1988d. RfD Description and Use In Health Risk Assessments.
Background Document 1A in Integrated Risk Information System (IRIS), on-Jine database.
Environmental Protection Agency (EPA). I988e. Suoerfund Exposure Assessment Manual. Office of
Remedial Response. EPA 540/1 -88/001.
Environmental Protection Agency (EPA). I989a. Development of a Risk Assessment Methodology for
Land Application and Distribution and Marketing of Municipal Sludge. EPA 600/6-89/001.
Environmental Protection Agency (EPA). 1989b. Exposure Factors Handbook. Office of Health and
Environmental Assessment. EPA 600/8-89/043.
Environmental Protection Agency (EPA). 1989c. Risk Assessment Guidance for Suoerfund. Volume I.
Environmental Evaluation Manual. Office of Solid Waste and Emergency Response. EPA 540/1-
89/001 A.
Environmental Protection Agency (EPA). I989d. Risk Assessment Guidance for Suoerfund. Volume I.
Human Health Evaluation Manual. Part A. Baseline Risk Assessment. Office of Solid Waste and
Emergency Response. OSWER Directive No. 9285.7-01 A. EPA 540/1-89/002.
Environmental Protection Agency (EPA). 1990a. Air Pathway Analysis Procedures for Superfund
Applications. Office of Air Quality Planning and Standards. EPA/450/1-89/001,002,003,004.
Environmental Protection Agency (EPA). 1990b. Guidance for Data Useabllitv In Risk Assessment.
Office of Emergency and Remedial Response. EPA/540/G-90/008.
Environmental Protection Agency (EPA). 1990c. Methodology for Assessing Health Risks Associated
with Indirect Exnosure to Combustor Emissions. EPA 600/6-90/003.
Environmental Protection Agency (EPA). 1990d. National Oil and Hazardous Substances Pollution
Contingency Plan: Final Rule. Federal Register, Vol. 55. No. 46, pages 8665-8865.
Environmental Protection Agency (EPA). 1990e. Region 10 Policy. Conduct of Remedial Investigations
and Feasibility Studies. Region 10 Hazardous Waste Division.
33
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EPA Region 10
August, 1991
Environmental Protection Agency (EPA). 1991 a. Conducting Remedial Investigations/Feasibility Studies
for CERCLA Municipal Landfill Sites. Office of Emergency and Remedial Response. OSWER Directive
No. 9355.3-11.
Environmental Protection Agency (EPA). 1991b. Health Effects Assessment Summary Tables (HEAST).
Office of Solid Waste and Emergency Response, Office of Emergency and Remedial Response 9200.6-
303. NTISNo. PB91-921100.
Environmental Protection Agency (EPA). 1991 c. Integrated Risk Information System (IRIS). On-line
database.
Environmental Protection Agency (EPA). 1991d. Interim Guidance for Dermal Exposure Assessment.-
Office of Research and Development, Office of Health and Environmental Assessment OHEA-E-367.
Environmental Protection Agency (EPA). 1991e. Risk Assessment Guidance for Superfund. Volume I.
Human Health Evaluation Manual. Part B. Development of Risk-based Remediation Goals. Office of Solid
Waste and Emergency Response. OSWER Directive No. 9285.7-01 B. (Not available yet.)
Environmental Protection Agency (EPA). I99lf. Risk Assessment Guidance for Superfund. Volume I.
Human Health Evaluation Manual. Part C. Risk Evaluation of Remedial Alternatives. Office of Solid Waste
and Emergency Response. OSWER Directive No. 9285.7-01 C. (Not available yet)
Environmental Protection Agency (EPA). 1991g. Risk Assessment Guidance for Suoerfund. Human
Health Evaluation Manual. Supplemental Guidance: Standard Default Exposure Factors. Office of
Emergency and Remedial Response, Office of Solid Waste and Emergency Response, Directive No.
9285.603.
Environmental Protection Agency (EPA). 1991h. Role of the Baseline Risk Assessment In Superfund
Remedy Selection Decisions. Office of Solid Waste and Emergency Response. OSWER Directive No.
9355.0-30.
Environmental Protection Agency (EPA). 19911. Supplemental Guidance on Performing Risk
Assessments In Remedial Investigations/Feasibility Studies (RI/FSs) Conducted by Potentially
Responsible Parties (PRPs). Office of Solid Waste and Emergency Response. OSWER Directive No.
9835.15a.
Washington State Department of Ecology. 1991. Model Toxics Control Act Cleanup Regulation. Chapter
173-340 WAC.
34
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EPA Region 10
August, 1991
8.0 Wh«r« to Obtain Doeumanta
IRIS User Support (513-569-7254) can provide Information about how to access IRIS on-line through
vendors. IRIS Is also available on PC-compatible diskettes from NTIS.
National Technical Information Service, Springfield, VA (703-487-4650). NTIS distributes many government
publications including EPA documents.
Center for Environmental Research Information (CERI), Cincinnati, Ohio (513-569-7562). Depending on
avaiabilty, CERI can provide free single copies of guidance documents, HEA's, HEED's, HEEP's, HAD's,
AAQD's, and some other documents identified with 'EPA /*."
Superfund Docket (202-382-3046). Source for guidance identified as 'OSWER Directive #.'
Region 10 Library (206-553-1289) will loan EPA publications (and ATSDR Toxicity Profiles) to the public.
35
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EPA Region 10
Supplemental Risk Assessment Guidance for Superfund
August, 1991
APPENDICES
Appendix I. Calculation of Human Health Risk-Based Concentrations
Appendix II. Human Health Risk-Based "Preliminary Remediation Goals' for Water and Soil
Appendix III. Summary Tables Exposure Factors
-------
Appendix I. Calculation of Human Health Risk-based Concentrations
Exposure assessment and risk characterization equations for Superfund risk assessments use site-specific
contaminant concentration data, factors describing exposure, and toxlcity dose-response values (reference
£!?
-------
Drinking Water
Plugging in Standard Default Exposure Factors for water ingestion, the equation for risk from drinking water
ingestion for carcinogens becomes:
Risk = C(ug/l) x 0.001 mg/ug x ( 2 l/dav x 350 dav/vr x 30 vr) x SF0 (5)
70 kg x 70 yr x 365 day/yr
This can be rearranged to solve for risk-based concentration, for example with target risk of 10"":
C(ug/l) = 10~8 x 1000 ug/mg / [( 2 l/dav x 350 dav/vr x 30 vr) x SF0] (6)
70 kg x 70 yr x 365 day/yr
An equation to calculate total risk from ingestion and inhalation pathways for voiatiles in drinking water can
be developed. Using a factor of 0.5 l/m (EPA I991e) to estimate the air concentration that would result
from domestic use of water, and Standard Default Exposure Factors, the resulting equation is:
Risk = C(ug/l) x 0.001 mg/ug x
[((2 l/dav x 350 dav/vr x 30 vr) x SF0) + ((0.5 l/m3 x 15 mVdav x 350 dav/vr x 30 vr) x SF)]
70 kg x 70 yr x 365 day/yr 70 kg x 70 yr x 365 day/yr
(7)
can bd rearranged to:
C(ug/l) = 10~8 x 1000 ug/mg /
[(( 2 l/dav x 350 dav/vr x 30 vr) x SF0) + (( 0.5 l/m3 x 15 mVdav x 350 dav/vr x 30 vr) x SF,)]
70 kg x 70 yr x 365 day/yr 70 kg x 70 yr x 365 day/yr
(8)
For non-carcinogens, the equation for HQ for drinking water ingestion is:
HQ = C (ug/l) x 0.001 mg/ug x ( 2 l/dav x 350 dav/vr x 30 vr) / RfD0 (9)
70 kg x 30 yr x 365 day/yr
-------
The equation for concentration representing hazard quotient of 1 from Ingestion Is:
C(ug/I) = 1 x 1000 ug/mg / [(2 l/dav x 350 dav/vr x 30 yr) / RfDJ (10)
70 kg x 30 yr x 365 day/yr
For non-carcinogens, the equation for HQ for drinking water ingestion and volatile inhalation is:
HQ = C (ug/l) x 0.001 mg/ug x
[((2 l/dav x 350 dav/vr x 30 vr) / RfD0) + ((0.5 l/m3 x 15 mVdav x 350 dav/vr x 30 vr) / RfD,)]
70 kg * 30 yrx 365 day/yr 70 kg x 30 yr x 365 day/yr
(11)
For non-carcinogens, the equation for concentration representing hazard quotient of 1 for vdatiles is:
C(ug/l) = 1 x 1000 ug/mg /
[((2 l/dav x 350 dav/vr x 30 vr) / RfD0) + ((0.5 l/m3 x 15 mVdav x 350 dav/vr x 30 vr) / RfD,)]
70 kg x 30 yr x 365 day/yr 70 kg x 30 yr x 365 day/yr
(12)
-------
Soil Ingest Ion
The equation for calculating carcinogenic risk from soil ingestion, using Standard Default Exposure Factors
and combining child and adult exposure, is as follows:
Risk = C(mg/kg) x 0.000001 kg/mg x
[(200 ma/day x 350 day/yr x 6 yr) + (100 mg/dav x 350 dav/vr x 24 yr)] / 70 yr x SF0
15 kg x 365 day/yr 70 kg x 365 day/yr
(13)
This can be'rearranged to solve for concentration at a target risk of 10"*:
C(mg/kg) = 10~8 x 1000000 kg/mg /
[((200 mo/dav x 350 dav/vr x 6 yr) + (100 mo/day x 350 dav/vr x 24 yr)) / 70 yr x SF0]
15 kg x 365 day/yr 70 kg x 365 day/yr
(14)
For noncarcinogens in soil, HQ is calculated:
HQ = C(mg/kg) x 0.000001 kg/mg x
[(( 200 ma/dav x 350 dav/vr x 6 yr) + (100 mg/dav x 350 dav/vr x 24 yr)) / 30 yr] / RfD0
15 kg x 365 day/yr 70 kg x 365 day/yr
(15)
For noncarcinogens, a concentration representing hazard quotient of 1 is calculated by:
C(mg/kg) = 1 x 1000000 mg/kg /
[(((200 ma/dav x 350 dav/vr x 6 yr) + (100 ma/dav x 350 dav/vr x 24 yr)) / 30 yr) / RfD0]
15 kg x 365 day/yr 70 kg x 365 day/yr
(16)
-------
EPA Region 10
October, 1992
Appendix II. Human Health Risk-based "Preliminary Remediation Goals" for Water and Soil
Table 11-1 Water Cheat Sheet: MCLs and Risk-Based Concentrations
Table II-2 Soil Cheat Sheet: Risk-Based Concentrations
REVISED VERSION
OCTOBER, 1992
-------
EPA Region 1O, 1O/30/92
Table 11-1. Water Cheat Sheet: MCLs and Risk-based Concentrations
CHEMICAL
Organics
Acenaphthene
Acenapthylene
Acetone
Aldrin
Anthracene
Benzene
Benz(a)anthracene
Benzo(b)fluoranthene
Benzo(g,h,i)perylene
Benzo(k)fluoranthene
Benzo[a]pyrene (BaP)
Benzoic acid
Benzyl alcohol
Bis(2-chloroethoxy)methane
Bis(2-chloroisopropyl) ether
Bis(2-ethylhexyl)phthalate (BEHP)
Bis(chloroethyl)ether (BCEE)
Bromodichloromethane
Bromoform
Bromomethane
Bromophenyl-phenyl ether
2-Butanone (methyl ethyl ketone)
Butyl benzyl phthalate
Carbon disulfide
Carbon tetrachloride
Chlordane
p-Chloroaniline
Chlorobenzene
Chloroethane (ethyl chloride)
Chloroform
Chloromethane
4-Chloro-3-methyl phenol
2-Chloronaphthalene
2-Chlorophenol
EPA REGULATED LIMITS
FINAL MCLs Carcinogen
Weight
Ma MCLG of
(ug/l) (ug/l) Evidence
D
D
B2
D
5 (a) 0 (a) A
B2
B2
D
B2
0.2 (b) 0 (b) B2
D
D
C
6 (b) 0 (b) B2
B2
100(a)THM B2
1 00 (a)THM B2
D
D
C
.5 (a) 0 (a) B2
2 (a) 0 (a) B2
100 (a) 100 (a) D
1 00 (a)THM B2
C
RISK-BASED CONCENTRATIONS
Risk
at
Ma
NA
NA
NA
NA
NA
8.0E-6
NA
NA
NA
NA
2.0E-5
NA
•NA
NA
NA
1.0E-6
NA
2.0E-4
9.0E-6
NA
NA
NA
NA
NA
2.0E-5
3.0E-5
NA
NA
NA
4.0E-4
NA
NA
NA
NA
H3
at
Ma
NA
NA
NA
NA
NA
(e) NA
NA
NA
NA
NA
(d) NA
NA
NA
NA
NA
(d) 0.008 (f)
NA
(d) 0.1 (f)
(d) 0.1 (f)
NA
NA
NA
NA
NA
(e) 0.2 (f)
(d) 0.9 (f)
NA
2
NA
(e) 0.3 (a)
NA
NA
NA
NA
Based on
Risk =10-6
(ug/l)
NA
NA
NA
0.005 (i)
NA
O.S (i)
0.01 (n)
0.01 (n)
NA
0.01 (n)
O.Ot (i)
NA
NA
NA
0.5 (i)
6 (i)
0.02 (i)
0.6 (i)
10 (i)
NA
NA
NA
NA
NA
0.3 (j)
0.06 (i)
NA
NA
NA
0.4 (D
3 (I)
NA
NA
NA
Ingestion, Residential
Risk =10-4 Hl = 1
. (ug/l) (ug/l)
NA
NA
NA
' 0,5 (i)
NA
80 (j)
1 (")
1 (n)
NA
1 (n)
1 (0
NA
NA
NA
50 (i)
600 ' (i)
2 (i)
60 (i)
1000 (i)
NA
NA
NA
NA
NA
30 (i)
6 (i)
NA
NA
I NA
i 40 (i)
B300 (i)
NA
NA
NA
2000
NA
4000
J
10000
NA
NA
NA
NA
NA
NA
1 00000
10000
NA
1000
700
NA
700
700
10
NA
1000
7OOO
30
30
2
100
50
30000
400
NA
NA
3000
200
(k)
(k)
(k)
(k)
(k)
(k)
(k)
(k)
(k)
(D
(D
(k)
(1)
(k)
(k)
(k)
(I)
(m)
(D
(k)
(k)
Cheat sheet, water 10/30
-------
EPA Region 10, 10/30/92
Table 11-1. Water Cheat Sheet: MCLs and Risk-based Concentrations
EPA REGULATED LIMITS
RISK-BASED CONCENTRATIONS
FINAL MCLs Carcinogen
CHEMICAL
4-Chlorophenyl-phenyl ether
Chrysene
Di-n-butylphthalate
Di-n-octylphthalate
Dibenz(a,h)anthracene
Dibenzofuran
Dibromochloromethane
1 ,2-Dichlorobenzene
1 ,3-Dichlorobenzene
1 ,4-Dichlorobenzene
3,3-dichlorobenzidine
p,p'-Dichlorodiphenyl dichloroethane (ODD)
p,p'-Dichlorodiphenyldichloroethylene (DDE)
p,p'-Dichlorodiphenyltrichloroethane (DDT)
1 ,1 -Dichloroethane
1 ,2-Dichloroethane
1,1-Dichloroethylene
cis-1 ,2-Dichloroethylene
trans-1 ,2-Dichloroethylene
Dichloromethane (methylene chloride)
2,4-Dichlorophenol
1 ,2-Dichloropropane
1 ,3-Dichloropropene
Dieldrin
Diethyl phthalate
2,4-Dimethylphenol
Dimethyl phthalate
4,6-Dinitro-2-methylphenol
2,4-Dinitrophenol
2,4-Dinitrotoluene
2,6-Dinitrotoluene
Endosulfan
Endosulfan sulfate
Endrin
Endrin ketone
Weight Risk
MCL MCLG of at
(ug/l) (ug/l) Evidence MCL
B2
B2
D
C
600 (a) 600 (a) D
D
75 (a) 75 (a) C
B2
B2
B2
B2
C
6 (a) 0 (a) B2
7 (a) 7 (a) C
70 (a) 70 (a) D
100 (a) 100 (a)
5 (b) 0 (b) B2
B (a) 0 (a) B2
B2
B2
D
D
B2
B2
2 (b) 2 (b) D
NA
NA
NA
NA
NA
NA
NA
NA
NA
2.0E-5
NA
NA
NA
NA
NA
3.0E-5
1.0E-4
NA
NA
8.0E-7
NA
4.0E-6
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
H3
at
Ma
NA
NA
NA
NA
NA
NA
NA
1 (9)
NA
(d) 0.04 (h)
NA
NA
NA
NA
NA
(e) NA
(e) 0.02 (f)
0.2 (f)
0.1
(e) 0.003 (g)
NA
(d) 0.04 (h)
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
0.2 (f)
NA
Based on Ingestion, Residential
Risk =10-6 Risk =10-4 HI = 1
(ug/l) (ug/l) (ug/l)
NA
0,01
NA
NA
0.01
NA
1
NA
NA
3
0.2
0.3
0.2
0.2
NA
0.3
0,08
NA
NA
7
NA
1
0.2
O.OOS
NA
NA
NA
NA
NA
0,1
0.1
NA
NA
NA
NA
(n)
(n)
(0
(i)
(i)
(i)
(i)
(i)
(i)
(i)
(i)
(i)
(i)
(i)
(i)
(i)
NA
1
NA
NA
1
NA
100
NA
NA
300
20
30
20
20
NA
30
•;.:::B
NA
NA
700
NA
100
20
0.5
NA
NA
NA
NA
NA
10
10
NA
NA
NA
NA
(n)
(n)
(i)
„,<'),.
(i)
(i)
(')
(i)
(i)
(i) -
(i)
(i)
(i)
(i)
(i)
(i)
NA
NA
4000 (k)
700 ... (k)
NA
40 (k)
700 (k)
500 (I)
NA
2000 (m)
NA
NA
NA
20 (k)
1000 (I)
NA
300 (k)
400 (k)
700 (k)
2000 (I)
100 (k)
100 (m)
9 (I)
2 (k)
30000 (k)
700 (k)
400000 (k)
NA
70 (k)
70 (k)
40 (k)
2 (k)
NA
10 (k)
NA
Cheat sheet, water 10/30
-------
EPA Region 10, 10/30/92
Table 11-1. Water Cheat Sheet: MCLs and Risk-based Concentrations
EPA REGULATED LIMITS
FINAL MCLs Carcinogen
CHEMICAL
Ma
Weight
MCLG of
(ug/l) Evidence
Risk
at
Ma
H3
at
Ma
RISK-BASED CONCENTRATIONS
Based on
Risk =10-6
(ug/l)
Ingestion, Residential
Risk =10-4 HI = 1
(ug/l) (ug/l)
Ethylbenzene 700 (a)
Fluoranthene
Fluorene
Heptachlor 0.4 (a)
Heptachlor epoxide 0.2 (a)
Hexachlorobenzene 1 (b)
Hexachlorobutadiene
alpha-Hexachlorocyclohexane (alpha-HCH)
beta-Hexachlorocyclohexane (beta-HCH)
delta-Hexachlorocyclohexane (delta-HCH)
epsilon-Hexachlorocyclohexane (epsilon-HC)
gamma-Hexachlorocyclohexane (lindane)(gamma-l 0.2 (a)
technical Hexachlorocyclohexane (t-HCH)
Hexachlorocyclopentadiene (HCCPD) 50 (b)
Hexachloroethane
Hexanone
lndeno(1 ,2,3-cd)pyrene
Isophorone
Methoxychlor 40 (a)
Methyl-2-pentanone
2-Methylnaphthalene
2-Methylphenol (o-cresol)
4-Methylphenol (p-cresol)
Naphthalene ,
2-Nitroaniline
3-Nitroaniline
4-Nitroaniline
Nitrobenzene
2-Nitrophenol
4-Nitrophenol
N-Nitrosodi-N-propylamine
N-Nitrosodiphenylamine
Pentachlorophenol 1 (a)
Phenanthrene
Phenol
700 (a) D
D
D
0 (a) B2
0 (a) B2
0 (b) B2
C
B2
C
D
D
0.2 (a) B2-C
B2
50 (b) D
C
B2
C
40 (a) D
C
C
D
D
B2
B2
0 (a) B2
D
D
NA
NA
NA
2.0E-5
2.0E-5
2.0E-5
NA
NA
NA
NA
NA
3.0E-6
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
1.0E-6
NA
NA
0.4 (g)
NA
NA
(d) 0.02 (f)
(d) 0.4 (f)
(d) 0.03 (f)
NA
NA
NA
NA
NA
(d) 0.02 (f)
NA
0.2 (f)
NA
NA
NA
NA
0.2 (f)
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
(d) 9E-04 (f)
NA
NA
NA .
NA
NA
0.02 (i)
0.009 (i)
0,05 (i)
1 (i)
0,01 (i)
0.05 (j)
NA
NA
0.06 (i)
0,05 (i)
NA
6 (i)
NA'
0.01
90 (i)
NA
NA
NA
NA
NA,
NA
NA
NA
NA
NA
NA
NA
0.01 (i)
20 (i)
0.7 (i)
NA
NA
NA
NA
NA
2 (i)
0,9 d)
• 5 (i)
100 • (i)
1 (i)
5 (i)
NA
NA
6 (i)
5 (i)
NA
600 (i)
NA
1 '
9000 (i)
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
1 (0
2000 (i)
70 (i)
NA
NA
?000
1000
1000
20
0,5
30
70
NA
NA
NA
NA
10
NA
300
40
NA
NA
7000
2OO
NA
NA
5000
2000
tooo
2
NA
NA
20
NA
NA
NA
NA
1000
NA
20000
(I)
(k)
(k)
(k)
W
(k)
(k)
(k)
(k)
(k)
(k)
(k)
(k)
(k)
(k)
(k)
(k)
(k)
(k)
Cheat sheet, water 10/30
-------
EPA Region 1O, 10/3O/92
Table 11-1. Water Cheat Sheet: MCLs and Risk-based Concentrations
EPA REGULATED LIMITS
FINAL MCLs Carcinogen
CHEMICAL
Polychlorinated biphenyls (PCBs)
Pyrene
Styrene
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD)
1 ,1 ,2,2-Tetrachloroethane
Tetrachloroethylene
Toluene
Toxaphene
1 ,2,4-Trichlorobenzene
1 ,1 ,1 -Trichloroethane
1 ,1 ,2-Trichloroethane
Trichloroethylene
2,4,5-Trichlorophenol
2,4,6-Trichlorophenol
Vinyl acetate
Vinyl chloride
Xylenes
MCL
(ug/l)
0.5 (a)
100 (a)
0.00003 (b)
5 (a)
1000 (a)
3 (a)
TQ.(b)
200 (a)
5 (b)
5 (a)
2 (a)
10000 (a)
MCLG
(ug/l)
0 (a)
100 (a)
0 (b)
0 (a)
1000 (a)
0 (a)
70 (b)
200 (a)
3 (b)
0 (a)
0 (a)
10000 (a)
Weight
of
Evidence
B2
D
B2 (c)
B2
C
B2 (c)
D
B2
D
D
C
B2 (c)
B2
A
D
Risk
at
MCL
5.0E-5
NA
4.0E-5
5.0E-5
NA
3.0E-6
NA
4.0E-5
NA
NA
2.0E-5
2.0E-6
NA
NA
NA
7.0E-5
NA
(d)
(e)
(d)
(«)
(d)
(e)
(e)
(e)
H3
at
MCL
NA
NA
0.01 (f)
NA
NA
0.01 (f)
1 (g)
NA
3 (g)
0.1 (g)
0.03 (f)
0.02 (f)
NA
NA
NA
NA
10 (g)
RISK-BASED CONCENTRATIONS
Based
Risk =10-6
(ug/l)
0.01
NA
2
0.0000006
0.1
2
NA
0,08
NA
NA
0.4
3
NA
2
NA
0.03
NA
on
C)
(i)
(i)
(i)
(i)
(')
(i)
(i)
(i)
(i)
Ingestion, Residential
Risk =10-4 HI = 1
(ug/l) (ug/l)
1
NA
200
0.00006
10
200
NA
8
NA
NA
40
300
NA
200
NA
3
NA
(i)
(i)
(i)
(i)
(i)
(')
(j)
(i)
(i)
(i)
NA
1000 (k)
7000 Ik}
NA
1000 (k)
400 (k)
1000 (I)
NA
20 (I)
2000 (I)
100 (k)
200 (k)
4000 (k)
NA
40000 (k)
NA
800 (I)
Cheat sheet, water 10/30
-------
EPA Region 10, 10/30/92
Table 11-1. Water Cheat Sheet: MCLs and Risk-based Concentrations
EPA REGULATED LIMITS
FINAL MCLs
CHEMICAL
Inorganics
Antimony
Arsenic, inorganic
Barium
Beryllium
Cadmium
Chromium(lll)
Chromium(VI)
Copper
Cyanide, free
Lead and compounds (inorganic)
Manganese
Mercury (Inorganic)
Nickel, soluble salts
Selenium
Silver
Thallium (soluble salts)
Vanadium
Zinc
Ma
(ug/l)
6
SO
2000
4
5
100
100
200
2
100
50
2
(b)
(a)
(a)
(b)
(a)
(a)totC
(a) totC
(b)
(a)
(b)
(a)
(b)
MCLG
(ug/l)
6 (b)
2000 (a)
4 (b)
5 (a)
1 00 (a)
1 00 (a)
1300 (a)
200 (b)
0 (a)
2 (a)
1 00 (b)
50 (a)
0.5 (b)
Carcinogen
Weight Risk
of at
Evidence MCL
A
B2
B1
A
D
B2
D
D
no data
D
D
D
NA
1.0E-3
NA
2.0E-4
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
K3
at
MCL
0.4
(d) 5
0.8
(d) 0.02
0.3
0.003
0.5
NA
0.3
NA
NA
0.2
0.1
0.3
NA
0.8
NA
NA
RISK-BASED CONCENTRATIONS
Based on Ingestion, Residential
Risk =10-6 Risk =10-4 HI = 1
(ug/l) (ug/l) (ug/l)
(f)
(0
(f)
(0
(«)
(f)
111
(f)
ill
III
111
ill
(f)
NA
0,05
NA
0.02
NA
NA
NA
NA
NA .
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
(i) 6
NA
(i) , 2
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
to
(0 10
3000
(i) 200
20
40000
200
1000
700
NA
iQoo
10
700
200
200
3
300
1000O
(k)
(k>
lk)
(k)
(k>
(k)
("I
-------
Table 11-1. Footnotes
NA = Toxicrty value and/or MCL not available, so risk-based concentration and/or risk at MCL can not be calculated.
(a) 40CFR141,subpartsA,B, F, G, and I.
(b) 57 FR 31777. July 17, 1992.
(c) Weight-of-Evidence classifications for carcinogenicity for trichloroethylene, tetrachloroethylene, and styrene are under review to
determine status as "C" or "B2". Carcinogenicity characterizations have been withdrawn from IRIS and HEAST pending resolution of the
issue. Until the new characterizations are available, Superfund risk assessments should use the quantitative evaluations for TCE and PCE
presented in the 1991 HEAST.
(d) Risk at MCL was calculated considering residential exposure through ingestion of water, using equation (5) from Appendix I. Appendix I is
consistent with Risk Assessment Guidance for Superfund, Part B (EPA/540/R-92/003). Exposure factors were taken from "Standard
Default Exposure Factors", OSWER Directive No. 9285.6-03. Cancer potency (slope) factors for each chemical were taken from EPA's
Integrated Risk Information System (IRIS) or Health Effects Assessment Summary Tables (HEAST). Specific reference for toxicrty
information for each chemical is provided in Table II-2, Sources of Toxicrty Data.
(e) Risk at MCL was calculated considering residential exposure through ingestion of water and inhalation of volatiles from household use of
water. The equation used was:
RISK = Cone, (ug/l) x ((.001 mg/ug x 2l/dav x 350 day/yr x 30 yr x SFo) + (0.5 l/m3 x 30 vr x 15 m3/dav x 350 dav/vr xUnit Risk (inhal.)(ug/m3)-i))
70 kg x 70 yr x 365 day/yr 70 yr x 20 rrhVday x 365 day/yr
This is identical in practice to equation (7) from Appendix I, except that is uses the unit risk term directly rather than back-calculating an
inhalation slope factor (avoiding potential rounding error). Sources of exposure factors and cancer potency (slope) factors are as in
footnote (d) above.
(f) HQ at MCL was calculated considering residential exposure through ingestion of water, using equation (9) from Appendix I. Sources of
exposure factors and reference doses are as in footnote (d) above.
(g) HQ at MCL was calculated considering residential exposure through ingestion of water and inhalation of volatiles from household use of
water. The equation used was:
HQ = Cone, (ug/l) x .001 mg/ug x ((2l/dav x 350 dav/vr /RfDo) + (0.5 Vm* x 15 m3/dav x 350 day/yr /RfC (mg/m3)))
70 kg x 365 day/yr 20 m3/day x 365 day/yr
-------
This is identical in practice to equation (11) from Appendix I, except that is uses the reference concentration directly rather than back-
calculating an inhalation reference dose (avoiding potential rounding error). Sources of exposure factors, reference doses and reference
concentrations are as in footnote (d) above.
(h) For volatile chemicals that have an RfC but no RfD, HQ at MCL was calculated using the right half of the equation in (g) above.
(i) Risk-based concentration was calculated using equation (6) from Appendix I, considering ingestion of drinking water. Exposure factors
and sources of toxicity data are the same as in footnote (d) above.
(D Risk-based concentration was calculated using the equation in footnote (e) above, rearranged. Exposure pathways considered were
ingestion of drinking water and inhalation of volatiles. Exposure factors and toxicity data sources are the same as in footnote (d) above.
(k) HQ = 1 concentration was calculated using equation (10) from Appendix I, considering ingestion of drinking water. Exposure factors and
sources of toxicity data are the same as in footnote (d) above.
(0 HQ = 1 concentration was calculated using the equation in footnote (g) above, rearranged. Exposure pathways considered were
ingestion of drinking water and inhalation of volatiles. Exposure factors and toxicity data sources are the same as in footnote (d) above.
(m) For volatile chemicals that have an RfC but no RfD, HQ =1 concentration was calculated using the right half of the equatbn in (g) above.
(n) For the purposes of this table and preliminary remediation goals, risk-based concentrations for all carcinogenic (B2) PAHs were calculated
using the BaP potency factor. Toxic equivalency factor (TEF) approaches are being reviewed for applicability in Superfund risk
assessments. This issue has not been resolved.
(o) The manganese RfD is based on exposure in the diet. For drinking water, absorption is expected to be greater, so an absorption factor of
3 is included in calculation of HQ.
-------
EPA Region 10, 10/30/92
Table H-2. Soil Cheat Sheet
RISK-BASED CONCENTRATIONS
CHEMICAL
Organics
Acenaphthene
Acenapthylene
Acetone
Aldrin
Anthracene
Benzene
Benz(a)anthracene
Benzo(b)fluoranthene
Benzo(g,h,i)perylene
Benzo(k)(luoranthene
Benzo[a]pyrene (BaP)
Benzole acid
Benzyl alcohol
Bis(2-chloroethoxy)methane
Bis(2-chloroisopropyl) ether
Bis(2-ethylhexyl)phthalate (BEHP)
Bis(chloroethyl)ether (BCEE)
Bromodichloromethane
Bromoform
Bromomethane
Bromophenyl-phenyl ether
2-Butanone (methyl ethyl ketone)
Butyl benzyl phthalate
Carbon disulflde
Carbon tetrachloride
Chlordane
p-Chloroaniline
Chlorobenzene
Chloroethane (ethyl chloride)
Chloroform
Chloromethane
4-Chloro-3-methyl phenol
2-Chloronaphthalene
2-Chlorophenol
4-Chlorophenyl-phenyl ether
Chrysene
Di-n-butylphthalate
Di-n-octylphthalate
Dibenzfa, h )anth racene
Dibenzofuran
Dibromochloromethane
1 ,2-Oichlorobenzene
1 ,3-Oichlorobenzene
1,4-Dichlorobenzene
3,3-dichlorobenzidine
p.p'-DichlorodiDhenvl dichloroethane
p,p'-Dichlorodiphenvldichloroethylem
p,p'-Dichlorodiphenvltrichloroethane
1,1 -Dichloroethane
1,2-Dichloroethane
Based on Soil Ingestion
Risk - 10-6
(mg/kg) (a)
NA
_ NA
NA
0.04
MA
SO
Q.Q9
o.oa
NA
o.oa
0,09
NA '
NA
NA
$
$0
0,5
5
80
NA
MA
NA
NA
NA
£
Q.5
NA
NA
NA
100
50
NA
NA
NA
NA
CKQ»
NA
NA
O.0»
NA
8
NA
NA
30
t
3
2
2
NA
7
Risk - 10-4
(mg/kg)
NA
NA
NA
4
NA
200$ -
9
9
NA
9
3
NA
NA
NA
900
$000
60
50$
8000
NA
NA
NA
NA
NA
500
50
NA
NA
NA
10000
5000
NA
NA
NA
NA
9
NA
NA
9
NA
800
NA
NA
3000
100
300
200
200
NA
700
Residential
HQ-1
(a) (mg/kg) (b)
20000
NA
30000
8
80000
NA
NA
NA
NA
NA
NA
fOOOOOO
80000
MA
10000
5000
NA
5000
5030
400
NA
10000
50000
30000
200
20
tooo
5000
NA
3000
MA
NA
20000
tooo
NA
NA
30000
SOOO
NA
300
5000
20000
NA
NA
NA
NA
NA
100
30000
NA
SOURCES OF TOXICITY DATA
Reference Dose
Data Source
Oral Inhal.
RfD RfC
IRIS
IRIS
IRIS
IRIS
IRIS
HEAST 92
IRIS
IRIS
IRIS
IRIS
IRIS IRIS
HEAST 92 IRIS
IRIS
IRIS HEAST 92
IRIS
IRIS
IRIS
IRIS HEAST 92
IRIS
IRIS
memo 5/90
IRIS
IRIS IRIS
HEAST 92
IRIS
memo 5/91
IRIS
IRIS HEAST 92
IRIS
HEAST 92
IRIS
HEAST 92 HEAST 92
Carcinogen
Weight
of
Evidence
D
D
B2
D
A
B2
82
D
B2
B2
D
D
C
B2
B2
B2
B2
D
D
C
B2
B2
D
B2
C
B2
B2
D
C
D
D
C
B2
B2
B2
B2
C
B2
Slope Factor
Data Source
Oral Inhal.
SF Unt Risk
IRIS
IRIS
IRIS IRIS
IRIS
IRIS IRIS
IRIS
IRIS
IRIS
IRIS
IRIS HEAST 92
IRIS
IRIS
HEAST 92 HEAST 92
IRIS
IRIS IRIS
IRIS
IRIS IRIS
IRIS
IRIS
IRIS
IRIS IRIS
IRIS IRIS
IRIS
IRIS IRIS
HEAST 92 HEAST 92
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
HEAST 92
IRIS
IRIS
IRIS
IRIS IRIS
IRIS
IRIS IRIS
Cheat sheet, soil 10/30
-------
EPA Region 10, 10/30/92
Table II-2. Soil Cheat Sheet
RISK-BASED CONCENTRATIONS
CHEMICAL
Based on
Soil Ingestion,
Risk = 10-6 Risk = 10-4
(nig/kg) (a) (mg/kg)
1 ,1 -Dichloroethylene
cis-1 ,2-Dichloroethylene
trans-1 ,2-Dichloroethylene
Dichloromethane (methylene chlorii
2,4-Dichlorophenol
1 ,2-Dichloropropane
1 ,3-Dichloropropene
Dieldrin
Diethyl phthalate
2,4-Dimethylphenol
Dimethyl phthalate
4,6-Dinitro-2-methylphenol
2,4-Dinitrophenol
2,4-Dinitrotoluene
2,6-Dinitrotoluene
Endosulfan
Endosulfan sulfate
Endrin
Endrin ketone
Ethylbenzene
Fluoranthene
Fluorene
Meptachlor
Heptachlor epoxide
Hexachlorobenzene
Hexachlorobutadiene
alpha-Hexachlorocyclohexane (alpha
beta-Hexachlorocyclohexane (beta-i-
delta-Hexachlorocyclohexane (delta-
epsilon-Hexachlorocyclohexane (ep:
gamma-Hexachlorocyclohexane (line
technical Mexachlorocyclohexane (t-
Hexachlorocyclopentadiene (HCCPC
Hexachloroethane
Hexanone
lndeno(1,2,3-cd)pyrene .
Isophorone
Methoxychlor
Methyl-2-pentanone
2-Methylnaphthalene
2-Methylphenol (o-cresol)
4-Methylphenol (p-cresol)
Naphthalene
2-Nitroaniline
3-Nitroaniline
4-Nitroaniline
Nitrobenzene
2-Nitrophenol
4-Nitrophenol
N-Nitrosodi-N-propy lamina
N-Nitrosodiphenylamine
t
NA
NA
9O
NA
9.
4
O.04
NA
NA
NA
NA
NA
9,9
0.9
NA
NA
NA
NA
NA
NA
NA
0.1
O.07
0.4
8
0.1
0*4
NA
NA
0.5
0,4
NA
SO
NA
0.09
700
NA
NA
NA
NA
: NA
: NA
NA
NA
NA
NA
NA
NA
o.os
too
100
NA
NA
9000
NA
900
400
4
NA
NA
NA
NA
NA
90
90
NA
NA
NA
NA
NA
NA
NA
10
7
40
800
10
40
NA
NA
50
40
NA
5000
NA
9
70000
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
9
100OO
Residential
HQ = 1
(a) (mg/kg) -(b)
2000
3000
5000
20000
800
NA
80
10
200000
5QOO
3000OOO
NA
500
500
300
10 .
NA
80
NA
30000
10000
10000
10O
4
200
500
NA
NA
NA
NA
80
NA
2000
300
NA
NA
50000
tooo
NA
NA
10000
10000
10000
20
NA
NA
100
NA
NA
NA
NA
SOURCES OF TOXICITY DATA
Reference Dose
Data Source
Oral Inhal.
RfD RfC
IRIS
HEAST 92
IRIS
IRIS HEAST 92
IRIS
IRIS
IRIS IRIS
IRIS
IRIS
IRIS
HEAST 92
IRIS
IRIS IRIS
memo 11/91
IRIS
IRIS
IRIS IRIS
IRIS
IRIS
IRIS
IRIS
IRIS IRIS
IRIS
IRIS HEAST 92
IRIS
IRIS
IRIS IRIS
IRIS IRIS
HEAST 92 IRIS
HEAST 92
HEAST 92 HEAST 92
IRIS HEAST 92
IRIS
IRIS
IRIS
Carcinogen
Weight
of
Evidence
C
D
B2
B2
B2
B2
D
D
B2
82
D
D
D
D
B2
B2
B2
C
B2
C
D
D.
B2-C
B2
D
C
B2
C
D
C
C
D
D
B2
B2
Slope Factor
Data Source
Oral
SF
IRIS
IRIS
IRIS
HEAST 92
HEAST 92
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
HEAST 92
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
Inhal.
Unit Risk
IRIS
IRIS
HEAST 92
HEAST 92
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
Cheat sheet, soil 10/30
-------
EPA Region 10, 10/30/92
Table II-2. Soil Cheat Sheet
RISK-BASED CONCENTRATIONS
CHEMICAL
Pantachlorophenol
Phenan threne
Phenol
Polychlorinated biphenyls (PCBs)
Pyrena .
Styrene
2,3,7,8-Tetrachlorodibenzo-p-dioxii
1 ,1 ,2,2-Tetrachloroethane
Tetrachloroethylene
Toluene
Toxaphena
1 ,2,4-Trichlorobanzana
1,1,1 -Trichloroathana
1 , 1 ,2-Trichloroe thane
Trichloroethylene
2,4,5-Trichlorophenol
2,4,6-Trichlorophenol
Vinyl acatata
Vinyl chloride
Xylenas
Inorganics
Antimony
Arsenic, inorganic
Barium
Beryllium
Cadmium
Chromium(lll)
Chromium(VI)
Copper
Cyanide, free
Lead and compounds (inorganic)
Manganese
Mercury (Inorganic)
Nicker, soluble salts
Selenium
Silver
Thallium (soluble salts)
Vanadium
Zinc
Based on Soil Ingestion,
Risk - 10-6
(mg/kg) (a)
1 5
NA .
MA.
0,0*
NA
2Q
4E-06
a
10
NA
, o,«
NA
MA
10
*0
NA
60
NA
0,3
NA
NA
0*4
NA
04
NA,
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Risk -10-4
(mg/kg)
. 500
NA
NA
a
NA
2000
0,0004
300
1000
NA
60
NA -
NA
1000
6000
NA
0000
NA
30
NA
NA
40
NA
10
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Residential
HQ-1
(a) (mg/kg) (b)
8000
NA
200000
NA
8000
50000
NA
$000
3000
50000
NA
3000
20000
1000
2000
30000
J*A
300000
NA
500OOO
1OO
60
20000
tooo
100
sooo
tooo
1000
20 ,
2000
60000
SOURCES OF TOXICITY DATA
Reference Dose
Data Source
Oral Inhal.
RfD RfC
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS IRIS
IRIS HEAST 92
HEAST92 HEAST 92
IRIS
memo 4/92
IRIS
HEAST 92 IRIS
IRIS HEAST 91
IRIS
IRIS
IRIS HEAST92
IRIS
IRIS
IRIS HEAST 91
IRIS HEAST 91
HEAST 92
IRIS
IRIS IRIS
HEAST 92 HEAST 92
IRIS
IRIS
IRIS
HEAST 91
HEAST 92
IRIS
Carcinogen
Weight
of
Evidence
B2
D
D
B2
Slope
Data
Oral
SF
IRIS
IRIS
IRIS
IRIS
-Factor
Source
Inhal.
Unit Risk
D memo 5/90
B2
B2
C
B2
D
B2
D
D
C
B2
B2
A
D
A
B2
B1
A
D
B2
D
D
no data
D
D
D
HEAST 90
HEAST 91
IRIS
HEAST 89
IRIS
IRIS
IRIS
IRIS
IRIS
HEAST 89
IRIS
HEAST 92
IRIS
HEAST 90
IRIS
IRIS
IRIS
IRIS
'IRIS
IRIS
IRIS
IRIS
HEAST 91
HEAST 91
IRIS
HEAST 91
IRIS
IRIS
HEAST 91
IRIS
HEAST 02
IRIS
IRIS
IRIS
IRIS
Cheat sheet, soil 10/30
-------
Table 11-2. Footnotes
NA = Toxicity value not available, so risk-based concentration can not be calculated.
(a) Risk-based concentration was calculated using equation (14) from Appendix I. This calculation
assumes residential exposure through soil ingestion. Appendix I is consistent with Risk
Assessment Guidance for Superfund, Part B (EPA/540/R-92/003). Exposure factors were taken
from "Standard Default Exposure Factors", OSWER Directive No. 9285.6-03. Cancer potency
(slope) factors for each chemical were taken from EPA's Integrated Risk Information System (IRIS)
or Health Effects Assessment Summary Tables (HEAST). Specific reference for toxicrty
information for each chemical is provided in at right under Sources of Toxicity Data.
(b) HQ = 1 concentration was calculated using equation (16) from Appendix I. This calculation
assumes residential exposure through soil ingestion. Appendix I is consistent with Risk
Assessment Guidance for Superfund, Part B (EPA/540/R-92/003). Exposure factors were taken
from "Standard Default Exposure Factors', OSWER Directive No. 9285.6-03. Reference Doses
(RfDs) for each chemical were taken from EPA's Integrated Risk Information System (IRIS) or
Health Effects Assessment Summary Tables (HEAST). Specific reference for toxicity information
for each chemical is provided in at right under Sources of Toxicity Data
(c) Risk-based concentrations calculated based on the soil ingestion pathway may not be appropriate
for chromiu, cadmium, elemental mercury, or carcinogenic forms of nickel. This is due to the issue
of their inhalation toxicity being potentially of more concern than ingestion.
-------
EPA Region 10
August. 1991
Appendix III. Summary Tables of Exposure Factors
Table 111-1 a. Residential RME and Average Exposure Factors for Superfund Human
Health Risk Assessment
Table 111-1 b. Industrial RME Exposure Factors for Superund Human Health Risk Assessment
Table III-2. Exposure Factors Used for Risk Assessment at Hazardous Waste Sites:
Details of Differences Among Programs
-------
EPA Region 10 8/2/91
Table 111-1 a. Residential RME and Average Exposure Factors
for Superfund Human Health Risk Assessment
RME
Exposure Factors
Residential Scenarios
Water Ingestion
Intake Rate
Exposure Frequency
Exposure Duration
Body Weight
Averaging Time '
Summary Intake Factor
Soil & Dust Ingestion
Intake Rate
Exposure Frequency
Exposure Duration
Body Weight
Averaging Time
Summary Intake Factor
Inhalation
Intake Rate ':<'•'
Exposure Frequency
Exposure Duration
Body Weight
Averaging Time
Summary Intake Factor
Non-Carcinogens
2 I/day
• •',">_— 4
350 day/year
30 year
70kg
30 year
2.7x10-2
IH2O
(kg BW x day)
200 mg/day (child)
100 mg/day (adult)
350 day/year
6 year (child)
24 year (adult)
15 kg (child)
70 kg (adult)
30 year
3.7 x 10-6
kg soil
(kg BW x day)
20, m3/day
(15 m3/day indoor)
350 day/year
30 year
70kg
30 year
0.27
m3 air
(kg x day)
(foot
Carcinogens note)
2 I/day ' ^ (1)
- *?5
350 day/year ||;: (3)
30 year :*.;; (5)
70kg ' || (7)
70 year ;.:;';:; (8)
•^•;'t?*'-^:V::/M(V»Ky*mM^
1 .2 x 1 0-2 (9)
I H2O
(kg BW x day)
200 mg/day (child) (10)
100 mg/day (adult)
350 day/year (3)
6 year (child) • (9)
24 year (adult)
15 kg (child) : (9)
70 kg (adult) :.;;..;
70 year V'.;.! (8)
1.6x10-6 (9)
kg soil
(kg BW x day)
20 m3/day (12)
( 1 5 m3/day indoor) :';'.( 13)
350 day/year •'''"'" (3)
30 year (5)
70 kg (7)
70 year (8)
0.12
m3 air > (9)
(kg x day)
AVERAGE
Exposure Factors
Non-Carcinogens
1.4 I/day
275 day '/year
9 year
70kg
9 year
1.5x 10-2
I H2O
(kg BW x day)
1 00 mg/day
275 day/year
9 year
70kg
9 year
1.1 X 10-6
kg soil .
(kg BW x day)
20 m3/day
275 day/year
9 year
70kg
9 year
0.2
m3 air
(kg x day)
Carcinogens
1,4 I/day
275 day/year
9 year'
70kg
70 year
1.9x10-3
I H2O
(kg BW x day)
1 00 mg/day
275 day/year
9 year
70kg
70 year
1 .4 x 1 0-7
kg soil
(kg BW x day)
20 m3/day
275 day/year
9 year
70kg
70 year
0.026
m3 air
(kg x day)
(foot
note)
(2)
(4)
(6)
(7)
(8)
(9)
(M)
K)
(6)
(7)
(8)
(9)
(12)
' W
(6)
(7)
(8)
(9)
Factors inside shaded boxes are those specified in "Standard Default Exposure Factors."
-------
EPA Region 10 8/2/91
Table ill-1 a. Residential RME and Average Exposure Factors
for Superfund Human Health Risk Assessment
RME
Exposure Factors
Dermal Contact with Soil
Contact Rate
Exposure Frequency
Skin Surface Area
Exposed
Exposure Duration
Body Weight
Averaging Time
Absorption
Summary Intake Factor
Non-Carcinogens
1 .0 mg/cm2
350 day/year
(foot
Carcinogens note)
1.0 mg/cm2
350 day/year
3900 cm2 (child) 3900 cm2 (child)
5000 cm2 (adult, sumrtSOOO cm2 (adult, summer)
1900 cm2 (adult, winte 1900 cm2 (adult, winter)
6 year (child)
24 year (adult)
15 kg (child)
70 kg (adult)
30 year
6 year (child)
24 year (adult) ::
15 kg (child) : ;,
70 kg (adult) ;I:;V
70 year '..
Chemical-specific
7.9 x 10-5xabs
kg soil
3.4x 10-5 xabs
Kg soil
(14)
(3)
(16)
(5)
(7)
(8)
(17)
(9)
AVERAGE
Exposure Factors
Non-Carcinogens
0.6 mg/cm2
275 day/year
1900 cm 2
9 year
70kg
9 year
Chemical
1.2x 10-5 xabs
kg soil
Carcinogens
0.6 mg/cm2
275 day/year
1900 cm 2
9 year
70kg
70 year
-specific
1 .6 x 1 0-6 x abS
kg soil
(foot
note)
(15)
(4)
(16)
(6)
(7)
(8)
(17)
(9)
(kg BW x day)
(kg BW x day)
(kg BW x day)
(kg BW x day)
Dermal Contact with Water
Contact Rate 0. 1 7 hr (bathing) 0.17 hr (bathing)
2.6 hr (swimming) 2.6 hr (swimming)
Exposure Frequency 350 day/year (bathing) 350 day/year (bathing)
7 day/yr (swimming) 7 day/yr (swimming)
Skin Surface Area 20,000 cm2 20.000 cm 2
Exposed
Exposure Duration 30 year 30 year
Body Weight 70 kg 70 kg
Averaging Time 30 year 70 year
Permeability Coefficient Chemical-specific
Summary Intake Factor 4.7 x 1 0-2 x Kp 2.0x1 0-2 x Kp
bathing I H2O I H2O
kg BW x day kg BW x day
Summary Intake Factor 1 .4 x 10-2 x Kp 6.1 x 10-3 x Kp
swimming I H2O I H2O
(14) 0.12 hr (bathing) 0.12 hr (bathing) (14)
2.6 hr (swimming) 2.6 hr (swimming)
(3) 275 day/year (bathing) 275 day/year (battling) (4)
(14) 7 day/yr (swimming) 7 day/yr (swimming) (14)
(14) 20.000 cm2 20.000 cm2 (14)
(5) 9 year 9 year (6)
(7) 70kg 70kg (?)
(8) 9 year 70 year (8)
(17) Chemical-specific (17)
(9) 2.5 x 1 0-2 x Kp 3.3 x 1 0-2 x Kp (9)
I H20 I H2O
kg BW x day kg BW x day
(9) 1.4x10-2xKp 1.8x10-3xKp (9)
I H2O I H2O
kg BW x day
kg BW x day
-------
EPA Region 10 8/2/91
Table HI-1 b. Industrial RME Exposure Factors
for Superfund Human Health Risk Assessment
RME
Exposure Factors
Industrial Scenarios
Water Ingestion
• Intake Rate
. Exposure Frequency
Exposure Duration
Body Weight
Averaging Time
Summary Intake Factor
Soil & Oust Ingestion
Intake Rate
Exposure Frequency
Exposure Duration
Body Weight
Averaging Time
Summary Intake Factor
Inhalation
Intake Rate
Exposure Frequency
Exposure Duration
Body Weight
Averaging Time
Summary Intake Factor
Non-Carcinogens
1 I/day
250 day/year
25 year
70kg
25 year
9.8 X 10-3
I H2O
(kg BW x day)
50 mg/day
250 day/year
25 year
70kg
25 year
4.9 x 10-7
kg soil
(kg BW x day)
20 m3/day
250 day/year
25 year
70kg
25 year
0.2
m3 air
Carcinogens
1 I/day .':;>;
250 day/year s m
25 year ••':?.;: •;
70 kg . ;ff
70 year
3.5x 10-3
I M2O
(kg BW x day)
50 mg/day
250 day/year
25 year . ;
70 kg
70 year
1.7x 10-7
kg soil
(kg BW x day)
- ' .'•': .
20 m3/day
250 day/year
25 year
7.0 kg
70 year •<•:;: ;
0.07
rri3 air
(foot
note)
(18)
(19)
(20)
(7)
(8)
(9)
(18)
(19)
(20)
(7)
(8)
(9)
(20)
(19)
(20)
(7)
<8>
(9)
(kg x day) (kg x day)
Factors inside shaded boxes are those specified in "Standard Default Exposure Factors.'
-------
EPA Region 10 8/2/91
Table 111-1 b. Industrial RME Exposure Factors
for Superfund Human Health Risk Assessment
RME
Exposure Factors
(loot
Non-Carcinogens Carcinogens note)
Dermal Contact with Soil
Contact Rate 1.0mg/cm2 1.0mg/cm2 (14)
Exposure Frequency 250 day/year 250 day/year (19)
Skin Surface Area Site-specific (21)
Exposed
Exposure Duration 25 year 25 year (20)
Body Weight ,:; 70 kg 70 kg (7)
Averaging Time 25 year 70 year (8)
Absorption Chemical-specific (17)
-------
Table 111-1. Footnotes:
(1) Specified in Standard Default Exposure Factors (SDEF)(EPA 1991). Recommended in Exposure Factors Handbook
(EFH) (EPA 1989) , section 2.2, as "reasonable worst case." Drinking water ingestion rate of 2 I/day is also used by
EPA Office of Drinking Water in setting MCLs.
(2) Average consumption rate , as reported in EFH section 2.2.
(3) Specified in SDEF Based on judgement that workers take two weeks of vacation per year.(4) From EFH section
5.3.3, fraction of time spent at home by an average person, 0.75, based on survey data, multiplied by 365 day/yr to
make units consistent with SDEF..
(5) Specified in SDEF. Based on 90th percentile residence time for owner-occupied housing, reported in EFH section
5.3.5.
(6) Fiftieth percentile residence time, EFH section 5.3.5.
(7) Specfied in SDEF. Average body weight for adult men and women combined (rounded to 70 kg), from EFH section
5.2.
(8) Averaging time for noncarcinogens is equal to exposure duration. Averaging time for assessing carcinogenic effects is
a lifetime. Use of 70 years to represent a lifetime is specified in SDEF Units of exposure frequency are in days, so
use 365 day/yr in averaging time.
(9) "Summary Intake Factor" represents the sum lifetime exposure to contaminated soil, water, or air through the pathway.
These unconventional units are presented here as a convenient way to compare the RME with average exposre
assumptions.
The "Summary Intake Factor" represents everything except chemical concentration in the generic intake equation:
I = C x CR x EFD x 1
BW AT
Exposure for a chemical can be calculated using the exposure point concentration in units of mg/l for water, mg/kg for
soil, or mg/m3 in air. The concentration multiplied by the "Summary Intake Factor" gives the intake "I" for that pathway,
so a shortcut risk or HQ calculation is-
Risk = SF x (Cone, x Summary Intake Factor) HI = (Cone, x Summary Intake Factor)
RfD
For dermal exposure pathways, the chemical specific factor for absorption (% absorbed for soil exposure; permeability
coefficient (Kp) for water) must be applied to the intake factor to calculate intake. The intake then represents an
absorbed dose, which means that the toxicity factor (RfD or slope factor) must be adjusted (corrected for oral
absorption in the toxicity experiments) to reflect absorbed dose.
(10) Specified in SDEF Calculation of soil ingestion combines child and adult :
Intake (ma soil =
kg BW day)
((200 ma/dav x 350 dav/vrV(15 ko x 365 dayyr)) x 6 vr + ((100 ma/dav x 350 dav/vr)/(70 kg x 365 dav/vr)) x 24 vr
30 yr
(11) Specified in OSWER directive 9850 4 "Interim Final Guidance for Soil Ingestion," EPA 1989.
(12) Specified in SDEF. Recommended as average in EFH section 3.2.5. Assumes 16 hrs/day "light activity" and 8 hr/day
"resting."
(13) Use with estimated indoor air concentration. Default equation to calculate from water concentration:
Intake from Air (mg/kg-day) = Cwtuo'l) x K(l.'m3) x 15 m3/dav)x 350 dav/vr x 0.001 mg/ug
365 day/yr x 70 kg)x AT(yr)
Cw = concentration of volatile contaminant in water
K = volatilization factor, 0.5 l/m3
AT = averaging time
-------
(13) Recommended as average in EFH section 3.2.5.
(14) Recommended as default in Interim Guidance for Dermal Exposure Assessment, (EPA 1991d).
*15^ AdJ"lersr>ce averaged across soil types, fromDriver, et.al. Soil adherence to human skin. Bull. Environ. Contam. Tox.,
1989, 43:814-820.
(16) Skin surface areas are taken from table 2-3 in the Interim Guidance for Dermal Exposure Assessment, and from
DooeloPment o« Statistical Distributions or Ranges of Standard Factors Used in Exposure Assessment, USEPA
1985(EPA 600/8-85-010)... 1900 cm2 represents the hands and forearms of an adult. 5000 cm2 represents the
hands, arms and lower legs of an adult. 3900 cm2 represents the arms, legs, hands and feet of a child. For the RME
case, calculate the sum exposure of a child for six years plus an adult for 24 years, with the adult having exposure for
1900 cm2 3/4 of each year, 5000 cm2 1/4 of the year. All of this assumes, in order to be consistent with the soil
ingestion pathway in SDEF. that contaminant concentrations and exposure to dust inside the house are equivalent to
soil outside.
(17) Chemical specific absorption information should be used. See Interim Guidance for Dermal Exposure Assessment for
guidance on dermal absorption, and/or consult EPA Health Assessment and ATSDR Toxicity Profile documents for
the chemical for absorption data. Appropriateness of extrapolation of toxicity factors from oral to dermal exposures for
the specific chemical should be considered befor evaluating this pathway. Oral RfD or SF should be corrected for oral
absorption in the toxicity study; again use chemical-specific absorption information from Health Effects Assessment or
Toxicity Profile.
(18) Specified in SDEF. Based on judgement that half of daily exposure may occur at work.
(19) Specified in SDEF. Represents 5 days per week, 50 weeks per year.
(20) Specified in SDEF.
(21) Exposure to contaminated soil at work would vary greatly depending on type of work activities. For current use
scenarios, the exposure scenario should include conservative estimate of area of skin that is being exposed to soil in
ongoing work activities.
-------
EPA Region 10 -4/1B/91
Table : Exposure Factors Used for Risk Assessment at Hazardous Waste Sites:
Details of Differences Among Programs
EPA Supertund
Standard Oetaul
RME Exposure factors
March. 1991 (1)
Residential Scenarios
Water Ingestton
Intake Rale
Exposure Frequency
Exposure Duration
Body Weight
Averaging Time
Summary Intake Factor
Son 4 Oust Ingestlon
Intake Rale
Exposure Frequency
Exposure Duration
Body Weight
Averaging Time
Summary Intake Factor
Inhalation
Intake Rate
Exposure Frequency
Exposure Duration
Body Weight
Averaging Time
Summary Intake Factor
Non-Carcinogens
2 I/day
350 day/year
30 year
70kg
30 year
2.7 X 10-2
IH2O
(kg BW x day)
200 mg/day (child)
100 mg/day (adul!)
350 day/year
6 year (child)
24 year (adult)
15 kg (child)
70 kg (adul)
30 year
3.7x10-6
kg soil
(kg BW x day)
20m3/day
(15 m3/day Indoor)
350 day/year
30 year
70kg
30 year
0.27
m3 air
(kg x day)
Carcinogens
2 I/day
350 day/year
30 year
70 Kg
70 year
1.2x10-2
IH2O
(kg BW x day)
200 mg/day (child)
100 mg/day (adult)
350 day/year
6 year (child)
24 year (adult)
15 kg (child)
70 kg (adult)
70 year
1.6 X 10-6
kg soil
(kg BW x day)
20m3fday
(15 m3/day Indoor)
350 day/year
30 year
70kg
70 year
0.12
m3 air
(kg x day)
EPA Region 10
RME Exposure Factors
lor Supertund
January. 1990 (2) (Superseded)
Non -Carcinogens
age-specllic
100%
75 year
age- specific
75 year
3.1 X 10-2
IH2O
(kg BW x day)
2OO mg/day (child)
100 mg/day (adul)
age-specific
75 year
age- specific
75 year
1.5 X 10-6
kg soil
(kg BW i day)
30m3/day
100%
75 year
age- specif ic
75 year
0.62
m3alr
(kg x day)
Carcinogens
age- specific
100%
75 year
age-specitic
75 year
3.1 X 10-2
IH2O
(kg BW x day)
200 mg/day (child)
100 mg/day (adul)
age-spealic
75 year
age-spealic
75 year
1.5x 10-6
kg soil
(kg BW x day)
30m3/day
100%
75 year
age-spealic
75 year
062
m3 air
(kg » day)
Washington Slate
Model Toxics Control Act
Method B
February. 1991 (3)
Non-Carcinogens
1 I/day
•
•
16kg
•
6.3 X 10-2
IH2O
(kg BW x day)
200 mg/day
1.0
16kg
1.3x10-5
kg soil
(kg BW x day)
10 m3/day
16kg
•
0.63
mSalr
(kg x day)
Carcinogens
2 I/day
•
30 year
70kg
75 year
1.1 X 10-2
IH2O
(kg BW x day)
200 mg/day
1.0
6 year
16kg
75 year
1.0X10-6
kg soil
(kg BW i day)
20m3/day
30 year
70kg
75 year
0.11
m3alr
(kg x day)
Washington Stale
Model Toxics Control Act
Method C
February, 1991 (3)
Non-Carcinogens
2 .I/day
•
•
70kg
•
2.9 X 10-2
IH2O
(kg BW x day)
100 mg/day
0.5
16kg
3.1 X 10-6
kg son
(kg BW x day)
20m3/day
•
70kg
0.29
m3 air
(kg x day)
Carcinogens
2 I/day
•
30 year
70kg
75 year
1.1 x 10-2
IH2O
(kg BW x day)
100 mg/day
0.5
6 year
16kg
75 year
2.5 X 10-7
kg soil
(kg BW x day)
20m3/day
30 yea/
70kg
75 year
0.11
m3air
(kg x day)
EPA RCRA
Corrective Action
July. 1990 (4)
Non-Carcinogens
2 I/day
•
70 year
70kg
70 year
2.9 X 10-2
IH2O
(kg BW x day)
200 mg/day
5 year
16kg
5 year
1.3x10-5
kg soil
(kg BW x day)
20m3/day
70 year
70kg
70 year
0.29
m3 air
(kg x day)
Carcinogens
2 Way
•
70 year
70kg
70 year
2.9 x 10-2
IH2O
(kg BW x day)
100 mg/day
70 year
70kg
70 year
1.4X 10-6
kg soil
(kg BW x day)
20 m3/day
70 year
70kg
70 year
029
mSalr
(kg x day)
-------
Table : Exposure Factors Used for Risk Assessment at Hazardous Waste Sites:
Details of Differences Among Programs
EPA Supertund
Standard Defaul
RME Exposure Factors
March. 1991 (1)
Industrial Scenarios
Walec Inflation
Intake Rat*
Exposure Frequency
Exposure Duration
Body Weight
Averaging Tim*
Summary Intak* Factor
Sol I Oust Ingestion
IntaKeRal*
F->posur* Frequency
Exposure Duration
Body Weight
Averaging Time
Summary Intake Factor
Inhalation
Intake Rale
Exposure Frequency
Exposure Duration
Body Weight
Averaging Tims
Summary Intake Factor
Non-Carcinogens
1 May
250 day/y*ar
26 year
70 Kg
25 year
9.8 X 10-3
IH2O
(kg BW i day)
50mg/day
250 day/year
25 year
70kg
25 year
4.9 X 10-7
kg soil
(kg BW i day)
20m3/day
250 day/year
25 year
70kg
25 year
0.20
rrtiair
Carcinogens
1 1/day
250 day/year
25 year
70kg
70 year
3.5 x 10-3
IH2O
(kgBWxday)
50mg/day
250 day/year
25 year
70kg
70 year
1.7x10-7
kg soil
(kgBWxday)
20m3/day
250 day/year
25 year
70kg
70 year
0.070
m3alr
EPA Region 10 Washington Slate Washington Stale EPA RCRA
RME Exposure Factors Model Toxics Control Act Model Toxics Control Act Corrective Action
lor Superlund Method B Method C
January. 1890 (2) (Superseded) February, 1091 (3) February. 1991 (3) juhi loan ui
Non-Carcinogens
2 I/day
60%
40 year
70kg
40 year
1.7x10-2
IH2O
(kgBWxday)
100 mg/day
36%
40 year
70kg
40 year
5.0x10-7
kg soil
(kgBWxday)
79 m3/day
36%
40 year
70kg
40 year
0.41
m3alr
Carcinogens Non-Carcinogens Carcinogens Non-Carcinogens Carcinogens Non-Carcinogens Carcinogens
2 Way
60%
NA NA NA
40 year
70kg
75 year
9.1 x 10-3
IH20
(kg BW i day)
100 mg/day 50 mg/day 50 mg/day
36% 0.4 0.4
NA NA
40 year • 20 year
70 kg 70 kg 70 kg
75 year * 75 year
3.0 x 10-7 2.9 x 10-7 7.6 x 10-8
kg soil kq soil kg soil
(kgBWxday) (kgBWxday) (kgBWxday)
79 m3/day
36%
NA NA NA
40 year
70kg
75 year
0.22
rrOalr
(kg»day)
(kg x day)
(kg x day)
(kg > day)
-------
EPA Region 10 4/18/91
' Where exposure frequency is not specified, tt is understood lo be 365 day/year. Where exposure duration is not specified, exposure duration is understood to be equal to averaging lime,
so these factors cancel out.
(1) Risk Assessment Guidance for Superlund, Voume 1: Human Health Evaluation Manual, Supplemental Guidance, "Standard Default Exposure Factors" Interim Final. U.S. EPA, Office of
Emergency and Remedial Response. OSWER Directive No. 9285.6-03. March 25,1991.
(2) Statement of Work RI/FS Risk Assessment. EPA Region 10, January 31. 1990. Superseded by (1).
(3) The Model Toxics Control Act Cleanup Regulation. Washington Stale Department of Ecology. Chapter 173-340 WAC, February 28,1991.
(4) Corrective Action lor Solid Waste Management Units at Hazardous Waste Management Facilities, Proposed Rule (40 CFR 264 Subpart S, Apendix D). U.S. EPA. July 27, 1990, 55 FR
30798. (Or: Inlenm Final RCRA Facility Investigation Guidance. Volume I of IV. U.S. EPA. OSWER Directive No. 9502.00-60, May, 1989. (EPA 530/SW-89O31))
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