United States
Environmental Protection
Agency
Office of Solid Waste and
Emergency Response
Washington, D.C. 20460
9285.7-01/FS
April 1990
&EPA
Risk Assessment Guidance
for Superfund: Volume I
Human Health Evaluation Manual
(Part A)
Office of Emergency and Remedial Response
Hazardous Site Evaluation Division, OS-230
Quick Reference Fact Sheet
The overarching mandate of the Superfund program is to protect human health and the environment from current and
potential threats posed by uncontrolled releases of hazardous substances. To help meet this mandate, the U.S.
Environmental Protection Agency's (EPA's) Office of Emergency and Remedial Response (OERR) has developed a human
health evaluation process as part of its remedial response program. EPA's Human Health Evaluation Manual describes the
process of gathering information and assessing the risk to human health, and together with the Environmental Evaluation
Manual comprise a two-volume set (Volumes I and II, respectively) called Risk Assessment Guidance for Superfund (RAGS).
RAGS replaces two previous EPA guidance documents: the Superfund Public Health Evaluation Manual (SPHEM; 1986) and
the Draft Endangerment Assessment Handbook (1985).
The Human Health Evaluation Manual has three main parts: baseline risk assessment (Part A), refinement of preliminary
remediation goals (Part B), and risk evaluation of remedial alternatives (Part C). Part A of this manual is being distributed as
an Interim Final document. Remedial project managers (RPMs) should ensure that the procedures in this guidance be used
for all new human health risk assessments conducted as part of the remedial investigation/feasibility study (RI/FS) process.
Copies of Part A can be obtained by calling EPA's Center for Environmental Research Information at 513-569-7562 (FTS
684-7562). Parts B and C are targeted for completion in 1990.
This fact sheet is designed to alert RPMs and other personnel to (1) new aspects of the Human Health Evaluation Manual
(Part A), (2) the purpose and steps of the baseline risk assessment, and (3) where additional help can be obtained.
PURPOSE OF THE HUMAN HEALTH
EVALUATION
The human health evaluation is used in the Superfund
program to:
help identify which sites warrant remedial action;
provide a consistent process for evaluating and
documenting human health risk;
ensure pro'tectiveness by the refinement of
risk-based, site-specific remediation goals;
provide focus for the FS;
help to measure the effectiveness of remedial
alternatives; and
aid in priority setting for remedial design/
remedial .action,
HUMAN HEALTH EVALUATION IN THE
RI/FS PROCESS
The RI/FS is the methodology that the Superfund program
has established for characterizing the nature and extent of
risks posed by uncontrolled hazardous waste sites and for
developing and evaluating remedial options. The
Superfund Amendments and Reauthorization Act of 1986
reemphasized the original statutory mandate that remedies
meet the threshold requirement to protect human health
and the environment. Because the RI/FS is an analytical
process designed to support risk management
decision-making, the assessment of health and
environmental risk plays an essential role in the RI/FS.
Highlight 1 shows the stages of the RI/FS, relating health
risk evaluation activities to each stage. Although the RI/FS
process and related risk evaluation activities are presented
in a fashion that makes the steps appear sequential and
distinct, in practice the steps are usually highly interactive.
HUMAN HEALTH EVALUATION AND
ENDANGERMENT FINDINGS
One of EPA's goals in the Superfund program is to use
more CERCLA section 106 (i.e., imminent and substantial.
endangerment) orders to compel potentially responsible
parties to design arid conduct the remedial actions. In order
for EPA to issue and enforce a section 106 order, the
baseline risk assessment must be sufficient to support the
finding that there may be an imminent arid substantial
endangerment to public health or welfare or the
environment because of an actual or threatened release of
a hazardous substance. By requiring careful adherence to
the Human Health Evaluation Manual (together with the
Environmental Evaluation Manual), the resulting baseline
risk assessment should be adequate to support an
. endangerment finding and thus a CERCLA section 106
order.
P'inted on Recycled Paper
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Hlghllght 1
Human Health Risk Evaluation Activities in the RI/FS Process
RI/FS
STAGES
HUMAN
HEALTH
RISK
EVALUATION
ACTIVITIES
Project
Scoping
RI/FS:
Site
Characterization
Establishment of
Remedial Action
Objective* (FS)
Development &
Screening of
Alternative! (FS)
Detailed
Analysis of
Alternatives (FS)
Review data
collected In sit*
Inspection
Review sampling/
data collection
plans
Formulate prelimi-
nary remediation
goals (RQs)
Determine level of
effort for baseline
risk assessment
Evaluate risk
of remedial
alternative*
PART A OF THE MANUAL:
BASELINE RISK ASSESSMENT
The baseline risk assessment process described in Part A of
the manual consists of four main steps as shown in
Highlight 2. Relevant information identified through data
collection and evaluation (Step 1) is used to develop
exposure and toxicity assessments (Steps 2 and 3). Risk
characterization (Step 4) summarizes and integrates both
the toxicity and exposure steps into quantitative and
qualitative expressions of risk.
WHAT'S NEW IN THE MANUAL
The Human Health Evaluation Manual revises and builds
upon the health evaluation process established in SPHEM.
Provided are new information and techniques gleaned from
several years of program experience conducting risk
assessments at hazardous waste sites. Policies established
and evolved over the years including those resulting
from the revised National Oil and Hazardous Substances
Pollution Contingency Plan (NCP) have been updated
and clarified. In addition, the link between the human
health evaluation, the environmental evaluation, and the
RI/FS has been strengthened.
HIGHLIGHTS OF THE REVISION
;
Introduction. Emphasizes shift in NCP and RI/FS
philosophy toward efficiency, effectiveness, and a bias for
action.
Data Collection (new chapter). Encourages assessors' early
involvement in RI/FS planning and effective
communication with RPMs. Describes procedures for
acquiring reliable chemical release and exposure data for
quantitative assessment. The topics discussed in the Data
Collection chapter are shown in Highlight 3.
Data Evaluation (new chapter). Provides nine steps to
organize data and to identify a set of chemicals and
concentrations that are of acceptable quality for use in the
quantitative risk assessment. The nine data evaluation
steps are shown in Highlight 4.
Highlight 2
Part A: Baseline Risk Assessment
Exposure Assessment
Analyze contaminant release*
Identify exposed population*
Identify potential exposure pathways
Estlmats exposure concentration*
for pathway*
Estimate contaminant Makes for
pathways
Data Collection and Evaluation
Gather and analyze relevant site data
Identify potential chemical* of concern
Risk Characterization
Characterize potential for adverse
health effects to occur
Estimate cancer risks
Estimate noncancer hazard
quotient* and Indlcee
Evaluate uncertainty
Summarize risk Information
Toxicity Assessment
Colect qualtattv* and quantitative
toxlctty Information
Determine appropriate toxlctty value*
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Highlight 3
Topics Discussed in
Data Collection Chapter
Available site Information
Modeling parameter needs
Background sampling needs
Preliminary Identification of human ex-
posure
Overall strategy for sample collection
Need for Special Analytical Services
Activities during workplan development
and data collection
Exposure Assessment. Gives specific equations and
parameter values for common Superfund site exposure
pathways. Defines the revised NCP's reasonable maximum
exposure (RME) concept under both current and future
land-use conditions. Highlight 5 defines the RME and
describes the specific terms in the general exposure
equation used to generate the RME.
Toxicity Assessment. Discusses EPA guidances, toxicity
data bases, and Superfund technical assistance groups.
Provides updated discussion of EPA's toxicity assessment
methods. Defines hierarchy of toxicity data sources, as
shown in Highlight 6.
Risk Characterization. Provides guidance for summarizing
risk information for use in decision-making. Presents
Highlight 4
Data Evaluation Steps
Step.t:
Step 2:
Step 3:
Step 4:
Step 5:
Step 6:
Step 7:
Step 8:
Step 9:
Gather all data available from the site
Investigation and sort by medium.
Evaluate the analytical methods used.
Evaluate the quality of data with respect to
sample quantitatlon limits.
Evaluate the quality of data with respect to
qualifiers and codes.
Evaluate the quality of data with respect to
blanks.
Evaluate tentatively Identified compounds.
Compare potential site-related contamination
with background.
Develop a set of data for use in the risk
assessment
If appropriate, further limit the number of
chemicals to be carried through the risk
assessment
expanded discussion of uncertainty. Includes examples of
helpful visual presentations of risk assessment as shown in
Highlights 7 and 8.
Documentation, Review, and Management Tools (new
chapter). Presents new tools for the RPM, risk assessor,
and risk assessment reviewer. These new tools are
described in Highlight 9. They include an RPM
involvement checklist (see Highlight 10), recommended
format for a baseline risk assessment report, and a risk
assessment reviewer's checklist.
Highlight 5
Reasonable Maximum Exposure (RME)
The reasonable maximum exposure (RME) is de-
fined as the highest exposure that could reasonably
be expected to occur at a site. RME is calculated
using the following general equation,
I = C x CR x EFD x J_
BW AT
where:
I
= Intake; the amount of chemical at the
exchange boundary (mg/kg body
weight- dy).
C = Concentration; the average chemical
concentration contacted over the
exposure period (e.g., mg/l).
CR = Contact Rate; the amount of
contaminated medium (e.g., soil, air,
water) contacted per unit time or event
(e.g., l/dy).
EFD = Exposure Frequency and Duration; how
often and how long exposure occurs
(e.g., dy/yr, yr).
BW = Body Weight; the average body weigh
over the exposure period (kg).
AT = Averaging Time; the time period over
which exposure is averaged (dy).
Use a 95th upper confidence limit on the arithmetic mean
concentration contacted over the exposure period, rather than
the mean itself. Rationale: uncertainty in the measurements
or modeling will be quantitatively considered.
Use the 95th percentile intake rate. Rationale: this will be
protective of most of the population.
Use the 95th percentile estimate if available, or best profes-
sional judgment to estimate a conservative value. Rationale:
statistical data on these terms are rarely available; a conserva-
tive estimate is suggested rather than a best or average esti-
mate in order to be protective.
Use the arithmetic average body weight over the exposure
period. Rationale: body weight is not always independent of
intake; by using the average, error from this dependence is
minimized; using the average rather than the 5th percentile
body weight will also reduce the number of upper-bound
values that are multiplied together.
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Hlghllght 6
Hierarchy of Toxicity Data Sources
Integrated Risk Information System (IRIS)
Provides verified reference doses
(RfDs) and slope factors
Updated monthly
EPA's preferred source of toxicity
information
Health Effects Assessment Summary Tables
(HEAST)
Provides interim as well as
verified RfDs and slope factors
Should be used only for
chemicals not addressed in IRIS
Other EPA References
Do not necessarily provide verified
RfDs and slope factors
Should be used only for chemicals
not found or referenced in IRIS or
HEAST
EPA's Environmental Criteria and
Assessment Office must be contacted
first (513-569-7300; FTS 684-7300)
Highlight 8
Example of Presentation of Relative
Contribution of Individual
Chemicals to Exposure Pathway
and Total Hazard Index Estimates
Nearby Resident Population
Chronic Hazard Index = 0.6
1.2
1.1
1.0
0.9
0.8
Hazard °'7
Index3 °-6
0.5
0.4
0.3
0.2
0.1
0.0
k'V'l Phenol
B^| Nitrobenzene
Well Water
Contaminated
Fish
Exposure Pathway
1 The hazard Index Is equal to the sum of the hazard quotients (I.e.. exposure
level/RfD) for each chemical. It Is not a probability; a hazard Index or quotient of
£1.0 Indicates that It Is unlikely for even sensitive human populations to
experience adveise health effects.
Radiation Risk Assessment Guidance (new chapter).
Provides basic principles and concepts of radiation
protection and supplemental baseline risk assessment
guidance for use at sites contaminated with radioactive
spbstances.
Appendices (new). Provide technical information on
absorbed vs. administered dose, and a complete index for
quick reference.
Highlight 7
Example of Presentation of Relative
Contribution of Individual Chemicals
to Exposure Pathway and Total
Cancer Risk Estimates
Nearby Resident Population
Excess Lifetime Cancer Risk 5 3x10"*
10'1-
10'2-
-t _
Public Water Supply
2x10"*(B2)
Rs^sj Benzene
HH Chlordane
Contaminated Rsh
x10"*(B2)
Exposure Pathway
The rt»* o< davatoplno. cancar a ptonad on tog KM* A risk of IQ-'lrxJlcjIaa probability
ol 1 chanc* In 10.000 of an individual davatoptng canc»r Rtik« ol lO^and lo^corraapond to
probablmhai ol 1 cnaric* in 100.000 and 1 chanca in 1.000.000. map#cttv»ty, Valoaa In
pjrtfltne«a nsprweni EPA i w».gni-ol-»vtd«nc» ciaisrticalion of tlw agtnt » potential
human carcinooen: A = human carcinogtn: and B2 = prooaola human carctftogan
NEED MORE HELP?
Superfund Health Risk Assessment Technical Support
Center. This center provides program staff and their
contractors access to the Office of Health and
Environmental Assessment (OHEA) and other Agency
experts in the area of health risk assessment. The center is
coordinated by OHEA's Environmental Criteria and
Assessment Office in Cincinnati (513-569-7300 or FTS
684-7300); it offers technical guidance in all areas of health
risk assessment, including project scoping, sampling
methods, exposure assessment, toxicity assessment, and
risk characterization. ECAO may respond to questions
directly or refer callers to other OHEA or Agency offices.
In addition, callers may be referred initially to regional
Toxics Integration Coordinators for responses to
site-specific requests (see next section).
Highlight 9
New Documentation, Review,
and Management Tools
RPM Involvement Checklist (see Highlight
10). The checklist addresses risk information
needs and includes pointers on planning and
involvement for the RPM. Involvement of
managers in the direction and development of
the risk assessment helps to avoid serious
mistakes or costiy misdirections in focus or level
of effort.
Recommended Format for a Baseline Risk
Assessment Report Consistency of
Superfund risk assessment format encourages
completeness, consistent use of results, and
allows for easier review.
Risk Assessment Reviewer's Checklist The
checklist is intended as a guide to ensure that
critical issues concerning the quality and
adequacy of risk information are not overlooked.
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Highlight 10 ~~
Checklist for RPM Involvement
1. Getting Organized
Ensure that the workplan for the risk assessment
contractor support is In place (If needed).
Identify EPA risk assessment support personnel (to be
used throughout the risk assessment process).
Gather relevant Information, such as appropriate
guidances and site-specific data and reports.
Identify available state, county, and other non-EPA
resources.
Prior to Special Notice, determine whether the PRPs will
be allowed to do the risk assessment
2. Before the Scoping Meeting
Make Initial contact with risk assessor.
Provide risk assessor with available guidances and site
data.
Determine (or review) data collection needs for risk
assessment, considering:
modeling parameter needs;
type and location of background samples;
alternate future land use;
possible exposure scenarios;
locatlon(s) In ground water that will be used to
evaluate future ground-water exposures;
the preliminary identification of environmental
concerns;
strategies (including medium and location) for sample
collection appropriate to site/risk assessment needs;
statistical methods;
QA/QC measures of particular Importance to risk
assessment; and
special analytical services needs.
3. At the Scoping Meeting
Present risk assessment data collection needs.
Ensure that the risk assessment data collection needs
will be considered in development of the sampling and
analysis plan.
Where limited resources require that less-than-optlmal 8.
sampling be conducted, discuss potential Impacts on risk
assessment results.
4. After the Scoping Meeting
Ensure that the risk assessor reviews and approves the
sampling and analysis plan.
Consult with the Agency for Toxic Substances and
Disease Registry (ATSDR) if human monitoring Is
planned.
5. During Sampling and Analysis
Ensure that risk assessment needs are being met
during sampling.
Provide risk assessor with any preliminary sampling
results so that he/she can determine If sampling
should be refocused.
Consult with ATSDR to obtain a status report on any
human monitoring that Is being conducted. Provide
any results to risk assessor.
6. During Development of Risk Assessment
Meet with risk assessor to discuss basis for excluding
chemicals from the risk assessment (and developing
the list of chemicals of potential concern). Confirm
appropriateness of excluding chemicals.
Confirm determination of alternate future land use.
Confirm location(s) In ground water that will be used
to evaluate future ground-water exposures.
Understand basis for selection of pathways and
potentially exposed populations.
Facilitate discussions between risk assessor and EPA
risk assessment support personnel on the following
points:
the use of any major exposure, fate, and transport
models (e.g., air or ground-water dispersion
models);
site-specific exposure assumptions;
non-EPA-derlved toxiclty values; and
appropriate level of detail for uncertainty analysis,
and the degree to which uncertainties will be
quantified.
Discuss and approve combination of pathway risks
and hazard Indices.
Ensure that results of risk characterization have been
compared with ATSDR health assessments and any
site-specific human studies that might be available.
7. Reviewing the Risk Assessment
Allow sufficient time for review and Incorporation of
comments.
Ensure that reviewers' comments are addressed.
Communicating the Risk Assessment
Plan a briefing among technical staff to discuss
significant findings and uncertainties.
Discuss development of graphics, tools, and
presentations to assist risk management decisions.
Consult with other groups (e.g., community relations
staff), as appropriate.
Brief upper management
Regional Toxics Integration Coordinators and
Headquarters Contacts. Superfund Toxics Integration
Koordinators are located in each region. Questions
jgarding site-specific Superfund risk assessment issues
should be referred to the appropriate individuals listed in
Highlight 11. The Toxics Integration Branch, OERR, may
be contacted at 202-475-9486 (FTS 475-9486) for
technical information sources, availability of guidances,
and related program directives.
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HlghllghtH
Regional Toxics Integration Coordinators
Region Name and Address Phone Number
I Sarah Levinson FTS 833-1504
Waste Management Division (HSS-CAN-7) 617-223-5504
EPA Region I
John F Kennedy Federal Building
Boston, MA 02203
II Peter Grevatt FTS 264-8775
Program Support Branch 212-264-6323
ERR Division
EPA Region II
26 Federal Plaza
New York, NY 10278
III Richard Brunker FTS 597-0804
Hazardous Waste 215-597-0804
Management Division (3HW15)
EPA Region III
841 Chestnut Street
Philadelphia, PA 19107
IV Elmer Akin FTS 257-1586
Waste Management Division 404-347-1586
EPA Region IV
345 Courtland Street, NE
Atlanta, GA 30365
V Steve Ostrodka FTS 886-3011
Technical Support Unit (5HSM-12) 312-886-3011
EPA Region V
230 South Dearborn Street
Chicago, IL 60604
VI JonRauscher FTS 255-2198
EPA Region VI (6H-SR) 214-655-2198
First Interstate Bank Tower
1445 Ross Avenue
Dallas, TX 75202-2733
VII Superfund Branch FTS 236-7052*
EPA Region VII 913-551 -7052
726 Minnesota Avenue
Kansas City, KS 66101
VIII Chris Weis FTS 330-7655
EPA Region VIII (8HWM-SR) 303-294-7655
999 18th Street, Suite 500
Denver, CO 80202-2405
IX Gerald Hiatt FTS 484-1914
Technical Support Section (H-8-4) 415-744-1914
Superfund Program
EPA Region IX
1235 Mission Street
San Francisco, CA 94103
X PatCirone FTS 399-1597
EPA Region X (ES-098) 206-442-1597
1200 Sixth Avenue
Seattle, WA 98101
Caller must have FTS 2000. If not, use commercial number.
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