Superfund Exposure Assessment Manual Draft


                                             OSWER Directivp  9285.5-1
                    DRAFT

    SUPERFUND EXPOSURE ASSESSMENT MANUAL
               Prepared for:
 Office of Emergency and Remedial Response
Office of Solid W&ste arid Emergency Response
    U.S. Environmental Protection Agency
          Washington, D.C.    20460
              January  14,  19P6



              En'-':troi"'"'  ''  •   ---;-o,j Agency

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          Chicago, ii:; ,,..,: c   -.jj.

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                             rstsetion Agency

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                                           OSWER Directive 9285.5-1
                             DRAFT
             Superfund Exposure Assessment Manual
    EPA Contract Nos.:  68-01-6271, Task No.:  59
                        68-03-3149, Work Assignment No. 23-2
                        68-01-7090, Work Assignment No. A-02
                              by:

H. Lee Schultz, Walter A. Palmer, Gina H. Dixon, Alan F. Gleit

                     Versar Inc
                  6850 Versar Center
            Springfield, Virginia   22151
                         Submitted  to:

               Dr.  Craig  Zamuda,  Project  Officer
          Office of  Emergency  and  Remedial  Response
             U.S.  Environmental Protection Agency
                   Washington, D.C.   20460
                                          U.S. Environmental  Protection Agency
                                          Region V, Library
                       i       u  mot   23° South Dearborn Street
                       January 14, 1986   Chjc?qa ,„

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U.S.- £nv:!'Ort.t'"iM1:--1'  P;-ctacl!on Agency

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                                                 OSWER Directive 9285.5-1
                                Disclaimer
    This document is a draft.  It has not been released formally by the
Office of Emergency and Remedial  Response, U.S. Environmental  Protection
Agency, and should not at this stage be construed to represent Agency
policy.  It is being circulated for comments on its technical  merit and
policy implications.
                                 11 i

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                                                 OSWER Directive 9285.5-1


                             Table  of Contents

                                                                Page No.

1.0    INTRODUCTION	   1-1

       1.1   Background	   1-1
       1.2   Purpose and Scope	   1-5
       1.3   Organization of the Manual	   1-6

2.0    STRUCTURE AND APPLICATION OF THE EXPOSURE ASSESSMENT
       PROCESS	  2-1

       2.1   Methodological Framework	  2-1
       2.2   Timeframe of Analysis	  2-3
       2.3   Exposure and Dose	  2-3
       2.4   Exposure Assessment Flexibility and Complexity	  2-3
       2.5   Exposure Assessment Output and Report Format	  2-6
       2.6   Application of the Exposure Assessment Process	  2-6

3.0    CONTAMINANT RELEASE ANALYSIS	   3-1

       3.1   Introduction	   3-1
       3.2   Contaminant Release Screening	   3-2
            3'.2.1  Contaminant Release Screening:  Contaminants
                   in Soil	   3-2
            3.2.2  Contaminant Release Screening':  Contaminants
                   Above Ground	   3-7
       3.3   Quantitative Contaminant Release Analysis	   3-8
       3.4   Atmospheric Contamination	   3-10
            3.4.1  Fugitive Dust Emission Analysis	   3-10
            3.4.2  Volati lization Emission Analysis	   3-19
            3.4.3  Long-term and Short-term Release Calculation.   3-32
       3.5   Surface Water Contamination Analysis	   3-34
            3.5.1  Simplified Procedures	;	   3-34
            3.5.2  In-depth Analysis	'	   3-44
            3.5.3  Long-Term and Short-Term Release Calculation.   3-44
       3.6   Ground-Water Contamination Analysis	   3-47
            3.6.1  Simplified Procedures	   3-47
            3.6.2  In-depth Analysis	   3-49
            3.6.3  Long-term and Short-term Release Calculation.   3-49
       3.7   Soil Contamination	   3-49
            3.7.1  Simplified Procedures	   3-49
            3.7.2  In-depth Analysis	   3-50
            3.7.3  Long-term and Short-term Release Calculation.   3-50
                                 IV

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                                                 OSNER Directive  9285.5-1


                       Table of Contents (continued)

                                                                  Page  No.

4.0    ENVIRONMENTAL FATE ANALYSIS	    4-1

       4.1  Introduction	    4-1
       4.2  Environmental  Fate Screening	    4-1
            4.2.1  Contaminant Environmental Fate Screening:
                   Atmospheric Fate	    4-2
            4.2.2  Contaminant Environmental Fate Screening:
                   Surface Water Fate	    4-4
            4.2.3  Contaminant Environmental Fate Screening:
                   Soi 1 and Ground-Water Fate	    4-7
            4.2.4  Contaminant Environmental Fate Screening:
                   Biotic Fate	    4-9
       4.3  Quantitative-Environmental   Fate Analysi s..'.	    4-11
            4.3.1  Atmospheric Fate	    4-13
            4.3.2  Surface Water Fate Analysis	    4-30
            4.3.3  Ground-Water Fate Analysis	    4-44
            4.3.4  Biotic Pathways	    4-70

5.0    QUANTITATIVE ANALYSIS OF EXPOSED POPULATIONS	    5-1

       5.1  Introduction....'	'....    5-1
       5.2  Exposed Populations Screening	    5-1
       5.3  Quantitative Exposed Populations Analysis	".    5-4
       5.4  Identification and Enumeration of  Exposed Human
            Populations	    5-4
            5.4.1  Populations Exposed  via Air	    5-8
            5.4.2  Populations Exposed  via Surface  Water or
                   Ground Water	    5-9
            5.4.3  Populations Exposed  via Food	    5-9
            5.4.4  Populations Exposed  via Soil	    5-11
       5.5  Population Characterization	    5-11
       5.6  Activity Analysis	'   5-12

6.0    EXPOSURE CALCULATION AND INTEGRATION	    6-1

       6.1  Inhalation Exposures	    6-2
       6.2  Dermal Exposure	    £=£->
       6.3  Ingestion Exposure	  i  6-£\J
            6.3.1  Food	  vi=8
            6.3.2  Water	    6-9
       6.4  Exposure Integration	    6-9

7.0    REFERENCES	    7-1

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                                                 OSNER Directive 9285.5-1
                       Table  of  Contents  (continued)



                                                                 Page No.



APPENDIX A  Index to Variable Terms	   A-l



APPENDIX B  Suggested Outline for Exposure Assessment	   B-l



APPENDIX C  Data Management Forms	   C-l

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                                                 OSWER Directive 9285.5-1


                              List of Tables


                                                                Page No.

Table 2-1   Possible Data Requirements for Estimation of
            Contaminant Release and Transport and Exposed
            Populations	   2-9

Table 3-1   Potential Contaminant Release Mechanisms	   3-3

Table 3-2   Environmental Variables and Model Parameters for the
            Wind Erosion Equation	   3-13

Table 3-3   Diffusion Coefficients of Selected Organic Compounds   3-24

Table 3-4   Runoff Curve Numbers	'	   3-36

Table 3-5   "C" Values for Permanent Pasture, Rangeland, and
            Idle Land	   3-41

Table 3-6   "C" Values for Woodland	   3-42

Table 3-7   Critical Compound and Site Characteristics	   3-48

Table 4-1   Assumptions for Calculation of Short-term Maximum
            Concentrations in Air	    4-17

Table 4-2   Resource Requirements, and Information Sources:
            Atmospheric Fate Models	    4-24

Table 4-3   Features of Atmospheric Fate Models	    4-27

Table 4-4   Data Requirements for Atmospheric Models	    4-28

Table 4-5   Resource Requirements, and Information Sources:
            Surface Water Fate Model s	    4-37

Table 4-6   Features of Surface Water Fate Models	   4-42

Table 4-7   Data Requirements for Surface Water Models	   4-43

Table 4-8   Suggested Value for Cet Relating Evaporation from
            a US Clas^ A Pan to Evapotranspiration from 8-15-cm
            Tal 1,  Wei 1-watered Grass  Turf	   4-47

Table 4-9   Crop Coefficients for Estimating Evapotranspiration    4-48
                                  VI 1

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                                                 OSHER Directive 9285.5-1


                        List of Tables (continued)


                                                                Page No.

Table 4-10  Representative Values of Hydraulic Parameters
            (Standard Deviation in Parentheses)	   4-50

Table 4-11  Representative Values of Saturated Hydraulic
            Conductivity	   4-51

Table 4-12  Saturated Hydraulic Conductivity Ranges for
            Selected Rock and Soil Types	  4-52

Table 4-13  Representative Values for Saturated Moisture
            Contents and Field Capacities of Various Soil Types..  4-53

Table 4-14  Resource Requirements, and Information
            Sources:  Unsaturated Zone and Ground-water Fate
            Model s	  4-63

Table 4-15  Features of Unsaturated Zone 'and Ground-Water Fate
            Model s	   4-67

Table 4-16  Data Requirements for Unsaturated Zone and
            Ground-Water Fate Model s	 4-68

Table 5-1   Regional Census Bureau Offices	   5-7

Table 5-2   U.S. Home Fruit and Vegetable Garden Use, 1977
            (USEPA  1980b)	   5-10

Table 6-1   Summary of Human Inhalation Rates for Men, Women
            and Children by Activity Level (m^/hour)	    6-4
                                  vi n

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                                                  OSWER  Directive  9285.5-1


                              List of Figures


                                                                  Page  No.

Figure  1-1. Relationship Between  Public  Health  Evaluation  and
            Exposure Assessment Guidance  for  Superfund  Sites	   1-4

Figure  2-1  Overview of the  Integrated Exposure Assessment
            Process	   2-2

Figure  3-1  Contaminant Release Decision  Network:  Contaminants
            in Soil	    3-4

Figure  3-2  Contaminant Release Decision  Network:  Contaminants
            above Ground	    3-5

Figure  3-3  Mean Number of Days per Year  with ^0.01  Inches of
            Precipitation (i.e.,  "wet days")	    3-17

Figure  3-4  Slope Effect Chart Applicable  to Areas A-1  in
            Washington, Oregon, and Idaho, and All of A-3	    3-38

Figure  3-5  Slope Effect Chart for Areas  Where  Figure 3-5  Is
            Not Applicable	'.	    3-39

Figure  3-6  Soil Moisture-Soil Temperature Regimes of the
            Western United States	    3-40

Figure  4-1  Environmental Fate Screening  Assessment  Decision
            Network:  Atmosphere	    4-3

Figure  4-2  Environmental Fate Screening  Assessment  Decision
            Network:  Surface Water	    4-5

Figure  4-3  Environemntal Fate Screening  Assessment  Decision
            Network:  Soils  and Ground Water	    4-8

Figure  4-4  Environmental Fate Screening  Assessment  Decision
            Network:  Food Chain	    4-10

Figure  4-5  Horizontal Dispersion Coefficient as  a Function of
            Downwind Distance from the Source	    4-15
                                    »

Figure  4-6  Vertical Dispersion Coefficient as a  Function  of
            Downwi nd Di stance from the Source	    4-16

Figure  4-7  Area within Isopleths for a Ground-Level Source	    4-20

.Figure  5-1  Exposed Populations Decision  Network	    5-2

Figure  5-2  Quantitative Exposed Populations Analysis	    5-5
                                  IX

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                                                 OSWER Directive 9285.5-1
1.0      INTRODUCTION

1.1      Background

    The Comprehensive Environmental Response, Compensation, and Liability
Act of 1980 (CERCLA) was enacted to provide the Federal Government with
the authority to respond to releases or substantial threats of releases
of hazardous substances, pollutants, or contaminants into the
environment.  Pursuant to the mandates of CERCLA, procedures for the
funding and execution of such responses have been developed.

    In response to Section 105 of the Act, the U.S. Environmental
Protection Agency was charged with the responsibility for reviewing and
revising the National Oil and Hazardous Substances Contingency Plan
(NCP).  Among the provisions that Section 105 of the Act directed to be
incorporated into the NCP during this revision effort were:
(1) procedures for the identification and investigation of facilities
that are releasing or may potentially release hazardous substances,
pollutants, or contaminants to the environment; (2) methods for
evaluating such existing or potential releases if they pose substantial
danger to human health or the environment; and (3) methods for evaluating
and selecting cost-effective control measures.  In meeting this
responsibility, EPA published the revised NCP as a final rule on
November 20, 1985.

    As set forth in the revised NCP (see 40 CFR Part 300), uncontrolled
hazardous waste sites are to be reviewed and ranked according to their
potential for release of hazardous substances.  This ranking is conducted
according to procedures provided in the Hazard Ranking System (HRS).
Those sites that receive high HRS scores are then lifted on the National
Priorities List (NPL) as designated Superfund sites.   For sites listed
on  the NPL, a Remedial Investigation (RI) and a Feasibility Study (FS)
are major components in the remedial response process.   The U.S.
Environmental  Protection Agency has developed guidance for Remedial
Investigations (USEPA 1985a) and Feasibility Studies (USEPA 1985b).  A
goal  of the Remedial Investigation is the acquisition of field data
needed to  determine the extent of existing contamination at the site (in
the absence of any control  measures).  In the Feasibility Study, these
data are used to evaluate site-related exposure.   The Feasibility Study
also evaluates the public health impacts from exposure attributable to
*
 A cut-off score has been established by EPA to differentiate those
sites that score "high," and therefore require listing on the NPL, from
those sites that rank "low" in this relative ranking procedure.

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                                                 OSWER Directive 9285.5-1
the uncontrolled site,  and identifies and evaluates the overall
effectiveness of potential remedial  alternatives.   The ultimate  goal of
the Feasibility Study is to select a cost-effective remedial  alternative
that provides adequate  public health and environmental protection.

    The public health evaluation component of the  Feasibility Study
defines the type and extent of hazards to public health presented by a
site in the absence of  remedial  action.   It is based in large part on an
exposure assessment that evaluates:  the  type and extent of contaminant
release from a site to  environmental media; the environmental transport
and transformation of contaminants following release; and the magnitude
of contact with human populations.  The  results of the exposure
assessment may aid the  public health evaluation in one of two ways.
Measured or estimated environmental  contaminant concentrations can be
compared with public health standards or criteria  that identify
acceptable concentrations of contaminants in specific environmental media
to directly assess the  potential public  health impact.  Alternatively, in
the absence of such standards/criteria,  the public health evaluation
process evaluates exposure estimates in  light of relevant toxicological
data to determine the magnitude of the health hazard posed by the
uncontrolled site.

    In addition, the exposure/public health assessment is a major
component of a site Endangerment Assessment (refer to USEPA 1985c for a
detailed discussion of the content and application of Endangerment
Assessments).  The Endangerment Assessment provides the documentation of
environmental and human population risk  that is required before  EPA can
initiate an enforcement action pursuant  to Section 106 of CERCLA.

    This Superfund Exposure Assessment Manual is designed to complement
the Superfund Public Health Evaluation Manual (USEPA 1985d),  which
details the information requirements and analytical procedures necessary
to conduct a public health evaluation during a Feasibility Study.  It
also provides an analytical approach and methods useful in addressing
other analyses conducted during the RI/FS.  For example, many of the
analytical procedures provided in this manual for  the determination of
contaminant release and mobility  in the  environment are equally well
suited for the analysis of natural resource damages as required  by
Section 301(c) of CERCLA.  Similarly, many of these procedures may also
aid in the identification of potentially useful remediation technologies.

    In conducting a Superfund evaluation of exposure and public  health
impact, the analyst initially applies the indicator chemical  selection
                                    1-2

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                                                 OSWER Directive 9285.5-1
process  as outlined in the Superfund Public Health Evaluation Manual.
Once those chemicals upon which site analyses will focus have been
selected, the framework for exposure assessment provided in this manual
is applied.  When exposure has been evaluated, the analyst returns to the
Superfund Public Health Evaluation Manual for guidance in determining the
degree of public health impact for each receptor population.  This
process is illustrated in Figure 1-1.

    The procedures provided in the Superfund Public Health Evaluation and
Superfund Exposure Assessment Manuals provide direct input to the
evaluation of threats posed by the uncontrolled site (no-action
alternative), and the development and evaluation of alternative remedial
actions.  Procedures and approaches for developing and evaluating these
alternatives will be presented in several guidances currently under
development, including guidance documents for soils and ground water
remedial actions and criteria for selecting alternative technologies.
Those guidances will refer the reader to the Superfund Exposure
Assessment Manual for specific analytical procedures.

    Many methods exist which could conceivably be applied to component
portions of the analytical process outlined in following chapters;
however, all possible approaches could not be addressed here.   In
developing this manual the authors have attempted to compile those
analytical methods most appropriate for assessing human exposure to
chemicals migrating from uncontrolled hazardous waste  facilities.  It
should be noted, however, that during the review process certain
potentially pertinent methods in addition to those currently addressed
have been identified for consideration and possible future incorporation
into this manual.  Examples are the Vertical and Horizontal Spread (VHS)
model for screening groundwater contamination potential, and the
EP-Toxicity procedure for evaluating the leachate generation potential of
certain waste constituents.  Following evaluation of these procedures,
their utility in conducting Superfund exposure assessments will  be
identified and detailed in the next revision of this manual.

    EPA is developing other more detailed information  to support the
effective and consistent application of the RI/FS process.   For example,
Health Effects Assessments for contaminants likely to  be found at
uncontrolled hazardous waste facilities are being compiled.  These
provide information on the physical and chemical  properties and
*Selection of indicator chemicals will  be required only at those Sites
where the number of contaminants present is too large to individually
evaluate exposure to each.
                                    1-3

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OSWER Directive 9285.5-1
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OSWER Directive 9285.5-1
toxicological characteristics of such substances. Copies of the Health
Effects Assessments are available through the National Technical
Information Service. Field sampling Data Quality Objectives (DQOs) are
being developed in two parts. The first part (DQO 1) will establish a
phased sampling strategy designed to guide the efficient acquisition of
field data for site-specific exposure and public health assessments. The
second part (DQO 2) will provide sampling plan guidance addressing the
location of sampling points. Field Operating Procedures for obtaining
and handling samples are also being developed. Similarly, a Soil
Contamination Evaluation Methodology (SOCEM) is being developed that will
provide the user with a simplified procedure for determining the risk
that contaminated soils pose to ground water, and for evaluating the
degree of reduction in such risk attainable through implementation of
various remedial alternatives. Finally, guidance for evaluating and
selecting ground-water remedial actions is under development.

1.2 Purpose and Scope

This manual presents an integrated methodology designed to guide the
three major component analyses required to assess human population
exposure to contaminants released from uncontrolled hazardous waste
sites: (1) analysis of toxic contaminant releases from a subject site,
-(2) determination of the environmental fate of such contaminants, and (3)
evaluation of the nature and magnitude of human population exposure to
toxic contaminants. These major analytical components are conducted in
sequence to qualitatively or quantitatively track the migration of
contaminants through environmental media to points of contact with human
populations. In quantitative studies, medium-specific exposure estimates
are initially developed for each chemical being evaluated, and the
analysis culminates in the integration of all exposures to receptor
populations.

This manual is designed for three specific purposes. First, the
overatl analytical process outlined herein provides a framework for the
comprehensive assessment of human exposure associated with uncontrolled
hazardous waste sites. It ensures that all pertinent contaminant
releases and exposure routes are considered, and that an appropriate
level of analytical detail is applied to each component of the evaluation
to support the public health evaluation process.

Second, application of this framework supports the development of
exposure assessments that are consistent from site to site. That is,
application of the same analytical philosophy and overall procedure to
each site will ensure that the results obtained are comparable among
sites, and will provide a means of documenting that each site receives
adequate evaluation.
1-5
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OSWER Directive 9285.5-1
Third, the procedures presented in this manual reflect
state-of-the-art methods for conducting the various component analyses
that make up an exposure assessment. However, it is recognized that
contaminant release estimation, chemical fate and transport
determination, etc., are developing sciences. Therefore, although the
overall conceptual approach for conducting exposure assessments at
Superfund sites will probably remain appropriate over time, alternative
analytical methods may be developed for parts of the assessment. In such
cases, the methods presented in this manual can serve as a benchmark
against which such alternative methods can be compared.

1-3 Organization of the Manual

The following chapters of this manual detail qualitative and
quantitative methods for evaluating human population exposure to
chemicals migrating from Superfund sites. Chapter 2 broadly outlines the
analytical framework. Subsequent chapters describe qualitative and
quantitative analytical methods for use in each portion of the overall
site analysis. Chapter 3 presents methods for evaluating contaminant
release from the site; Chapter 4 addresses environmental fate analysis;
and Chapter 5 details analysis of potentially exposed human
populations. The results of these analyses are combined in Chapter 6,
which addresses the calculation of medium-specific exposure estimates and
integration of all exposures to each hazardous substance. The last
chapter of the manual, Chapter 7 cites references used in developing this
guidance. Appendix A contains an index to the variable terms used in the
equations in Chapters 3 and 4. Appendix B provides a suggested format
for documenting the exposure assessment, while Appendix C presents master
copies of data management forms, designed to facilitate the recording and
organization of the results obtained by applying the analytical
procedures discussed in Chapters 3, 4, 5, and 6. These forms arrange
data in a format useful for public health evaluation (conducted following
and based on the results of the exposure assessment), as well as for
development of an Endangerment Assessment for enforcement purposes.
1-6
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OSWER Directive 9285.5-1

2.0 STRUCTURE AND APPLICATION OF THE EXPOSURE ASSESSMENT PROCESS

2.1 Methodological Framework

The ultimate goal of human exposure assessment at Superfund sites is
the determination of the type and magnitude of potential human population
exposure to contaminants present at and migrating from the site.
Depending on site conditions, this goal may be achieved by application of
either qualitative or quantitative analysis. Many sites may require a
mix of qualitative and either simplified or in-depth quantitative
exposure analysis.

The general framework for conducting an integrated exposure analysis
is broadly illustrated in Figure 2-1. Briefly, analysis of contaminant
release involves identifying each on-site source of release of each
target chemical to specific environmental media. Emissions are
characterized as to types and amount of chemicals involved, and a
determination is made of the level of release (mass loading) of each
chemical to each affected medium. The results of the release analysis
step provide the basis for evaluating the potential for contaminant
transport or transformation and environmental fate. This analysis is
also chemical- and medium-specific.

Environmental fate analysis produces results that describe the .extent
and magnitude of environmental contamination (i.e., contaminant
concentrations in specific environmental media). This output, in turn,
allows the user to predict human population contact with chemicals
emanating from the site. Exposed populations analysis results in the
identification, enumeration, and characterization of those population
segments likely to be exposed.