UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
OFFICE OF
SOLID WASTE AND EMERGENCY
.'1f~>T •, , RESPONSE
uo I - J i -;:-jQ
OSWER Directive 9285.7-28 P
MEMORANDUM
SUBJECT: Issuance of Final Guid^jice: Ecological Risk Assessment and Risk Management
PrinciplgJ? for i
FROM:
Office off&rffergency and Remedial Response
TO: Superfund National Policy Managers
Regions 1-10
I. PURPOSE
This guidance is intended to help Superfund risk managers make ecological risk
management decisions that are based on sound science, consistent across Regions, and present a
characterization of site risks that is transparent to the public. It provides risk managers with six
principles to consider when making ecological risk management decisions. The ability to make
sound ecological risk management decisions is dependent upon the quality and extent of
information provided in the ecological risk assessment (ERA). All ERAs should generally be
performed at every site according to the eight-step process described in: Ecological Risk
Assessment Guidance for Superfund: Process for Designing and Conducting Ecological Risk
Assessments (ERAGS, EPA 540-R-97-006, OSWER Directive # 9285.7-25, June 1997). The
principles provided in this guidance supplement the ERAGS guidance and will aid remedial
project managers (RPMs) and on-scene coordinators (OSCs) in planning ERAs of appropriate
scope and complexity and in identifying response alternatives in the feasibility study or
engineering evaluation/cost analysisthat are protective of the environment. (See Text Box 1.)
By incorporating these principles into their decision-making, risk managers will be able to
present a clear rationale for their ecological risk management actions which they can
communicate to the public in the proposed plan and the Record of Decision, or the Action
Memo. Implementation of this guidance should not restrict the ability of natural resource
trustees to investigate injuries to natural resources, assess damages, and/or restore habitats.
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II. BACKGROUND
As the Superfund program has matured,
it has given more and more consideration to the
potential effects of hazardous substances
releases on ecological receptors. This increased
focus on ecological risks has highlighted the
need for more guidance on ecological risk
management.
The National Oil and Hazardous
Substances Pollution Contingency Plan (NCP)
states that: "Alternatives shall be assessed to
determine whether they can adequately protect
human health and the environment, in both the
short- and long-term, from unacceptable risks
posed by hazardous substances, pollutants, or
contaminants present at the site by eliminating,
reducing, or controlling exposures to levels
established during development of remediation
goals consistent with § 300.430(e)(2)(I)."
(40CRF 300.430(e)(9)(iii)(A)). The NCP
establishes a protective risk range for human
health, but provides little guidance regarding
developing remediation goals considered to be
adequate for protecting ecological receptors. The NCP also states that applicable or relevant and
appropriate requirements (ARARs) shall be considered in determining remediation goals. Thus,
ARARs that are set based on risks to ecological receptors, such as water quality criteria/state
standards established under sections 303 and 304 of the Clean Water Act, must be considered in
determining remediation goals that are protective, but other factors also influence this
determination. Although some states may also have promulgated standards for soil or sediment,
there generally are no current federal ARARs for sediment or soil.
Establishing remediation goals for ecological receptors is considerably more difficult than
establishing such goals for the protection of human health due to the paucity of broadly
applicable and quantifiable toxicological data. Further, owing to the large variation in the kinds
and numbers of receptor species present at sites, to their differences in their susceptibility to
contaminants, to their recuperative potential following exposure, and to the tremendous variation
in environmental bioavailability of many contaminants in different media, protective exposure
levels are best established on a site-specific basis.
Text Box 1. Risk Management vs. Risk
Assessment
This document deals with the application
of principles that help to accomplish the
management of ecological risk in a
consistent and appropriate manner. This
includes decisions about whether to
respond and how to select a response
alternative that is protective. The 1997
ERA guidance provides a standardized
approach to identify adverse effects and the
severity of those effects. That guidance
does not suggest that all ecological risk
assessments must be identical, nor does it
suggest that all ecological risk assessments
will require the same level of effort to
allow appropriate risk management
decisions.
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III. ECOLOGICAL RISK ASSESSMENT/ MANAGEMENT PRINCIPLES
A goal of the Superfund program is to select remedies that are protective of human health
and the environment, both in the short-term and long-term. Since ecological receptors at sites
exist within a larger ecosystem context, remedies selected for protection of these receptors
should also assure protection of the ecosystem components upon which they depend or which
they support. Except at a few very large sites, Superfund ERAs typically do not address effects
on entire ecosystems, but rather normally gather effects data on individuals in order to predict or
postulate potential effects on local wildlife, fish, invertebrate, and plant populations and
communities that occur or that could occur in specific habitats at sites (e.g., wetland, floodplain,
stream, estuary, grassland, etc.). Ecological risk assessments incorporate a wide range of tests
and studies to either directly estimate community effects (e.g., benthic species diversity) or
indirectly predict local population-level effects (e.g., toxicity tests on individual species), both of
which can contribute to estimating.ecological risk. Superfund remedial actions generally should
not be designed to protect organisms on an individual basis (the exception being designated
protected status resources, such as listed or candidate threatened and endangered species or
treaty-protected species that could be exposed to site releases), but to protect local populations
and communities of biota. Levels that are expected to protect local populations and communities
can be estimated by extrapolating from effects on individuals and groups of individuals using a
lines-of-evidence approach. The performance of multi-year field studies at Superfund sites to try
to quantify or predict long-term changes in local populations is not necessary for appropriate risk
management decisions to be made. Data from discrete field and laboratory studies, if properly
planned and appropriately interpreted, can be used to estimate local population or community-
level effects.
Risk managers should generally adhere to the six principles listed below when scoping
ecological risk assessments and when making ecological risk management decisions.
Principle No. 1 -Superfund's goal is to reduce ecological risks to levels that will result in the
recovery and maintenance of healthy local populations and communities of biota. The goal
of the Superfund program is to select a response action that will result in the recovery and/or
maintenance of healthy local populations/communities of ecological receptors that are or should
be present at or near the site. Superfund risk managers and risk assessors should select
assessment endpoints and measures (as defined in the 1997 ERAGS) that: 1) are ecologically
relevant to the site; i.e., important to sustaining the ecological structure and function of the local
populations, communities and habitats present at or near the site, and 2) include species that are
exposed to and sensitive to site-related contaminants. In addition, if individual threatened or
endangered species or critical habitats for such species are present at a site, the federal
Endangered Species Act or a state endangered species act may be an ARAR.
Principle No. 2 - Coordinate witH Federal, Tribal, and State Natural Resource Trustees. It
is Superfund's goal that our response actions will not only achieve levels that are protective, but
will also minimize the residual ecological risks at sites. Due to factors such as technical
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implementability and response costs at some sites, however, EPA recognizes that its response
action may not lead to complete recovery of the ecosystem and that additional restoration
activities by the natural resource trustees may be needed to bring natural resources back to their
baseline condition within an acceptable time frame. It is important, however, that EPA and the
Trustees coordinate both the EPA investigations of risk and the trustee investigations of resource
injuries in order to most efficiently use federal and state monies and to not duplicate efforts.
Principle No. 3 - Use site-specific ecological risk data to support cleanup decisions. Site
specific data should be collected and used, wherever practicable, to determine whether or not site
releases present unacceptable risks and to develop quantitative cleanup levels that are protective.
Site-specific information can include, but is not limited to, plant and animal tissue residue data,
toxicity test data, bioavailability factors, and population- or community-level effects studies.
Data collection efforts should be coordinated with other efforts to collect data for a human health
assessment or for a natural resource injury assessment by trustees. As in all risk assessments, its
scope should be tailored to the nature and complexity of the site problems being addressed and
the response alternatives being considered, including their costs and implementability.
Principle No. 4 - Characterize site risks. When evaluating ecological risks and the potential
for response alternatives to achieve acceptable levels of protection, Superfund risk managers
should characterize site risks in terms of: 1) magnitude; i.e., the degree of the observed or
predicted responses of receptors to the range of contaminant levels, 2) severity; i.e., how many
and to what extent the receptors may be affected), 3) distribution; i.e., areal extent and duration
over which the effects may occur, and 4) the potential for recovery of the affected receptors. It is
important to recognize, however, that a small area of effect is not necessarily associated with low
risk; the ecological function of that area may be more important than its size.
Principle No. 5 - Communicate risks to the public. Superfund risk managers, in collaboration
with ecological risk assessors, should clearly communicate to the public the scientific basis and
ecological relevance of the assessment endpoints used in site risk assessments and the
relationship between the effect or exposure measures used to determine if there are any adverse
effects to any of the assessment endpoints. For example, earthworms are not normally perceived
by the public as important to ecosystem functioning but are very important in many habitats as
they are the main food source for many birds and small mammals and they play a critical role in
recycling soil nutrients and in improving the soil quality for other plants and invertebrates.
Principle No. 6 - Remediate unacceptable eco risks. Working within the framework of the
NCP, Superfund's goal is to eliminate unacceptable ecological risks due to any release or
threatened release. Contaminated media that are expected to constrain the ability of local
populations and/or communities of plants and animals to recover and maintain themselves in a
healthy state at or near the site (e.g., contamination that significantly reduces diversity, increases
mortality, or diminishes reproductive capacity) should be remediated to acceptable levels. (See
the following discussion under question #3 for additional guidance).
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IV. QUESTIONS RISK MANAGERS AND RISK ASSESSORS SHOULD ADDRESS
Although all site cleanup decisions are ultimately the responsibility of EPA's Regional
Administrator or the appropriate designee, no ecological risk management decisions should be
made without coordinating with the regional ecological risk assessor, usually the Regional
Biological Technical Assistance Group (BTAG) Coordinator, and the representative(s) from the
appropriate natural resource trustee agency(s). The BTAG Coordinators are listed at the end of
this document. Frequent coordination among the risk manager, risk assessor, and trustees is
critical in selecting remedies that provide acceptable levels of protection. The eight-step ERAGS
process with its five key risk assessor/risk manager decision points (Scientific/Management
Decisions Points) should always be used in conjunction with this guidance. Addressing the
following four questions, which highlight fundamental ecological risk assessment and risk
management issues, should facilitate reaching sound decisions at these five points in the process.
1. What ecological receptors should be protected?
ERAGS provides information on identifying and selecting assessment endpoints for
evaluating the ecological risk to biotic receptors at sites. An assessment endpoint is defined as:
"an explicit expression of the environmental value that is to be protected." Superfund risk
assessments should use site-specific assessment endpoints that address chemical specific
potential adverse effects to local populations and communities of plants and animals (e.g.,
reductions in populations of fish-eating birds, or reductions in survival, reproduction or species
diversity of indigenous benthic communities). The number and breadth of the assessment
endpoints depends on the number and type of contaminated habitats at the site. Risk assessment
measures (i.e., measures of effect, measures of exposure, measures of ecosystem and receptor
characteristics) should then be selected based on site-specific conditions and used to infer effects
on the local population or community of concern. Examples might include: toxicity test results,
tissue concentrations, and physio-chemical measurements related to fate and transport of the
contaminants.
2. Is there an unacceptable ecological risk at the site?
Unless the ecological impacts are apparent (e.g., no vegetation will grow on the
contaminated portion of the site or no benthic organisms exist in the sediment downstream from
the release), site specific biological data should be developed in order to determine if there are
unacceptable risks. The baseline risk assessment may include site-specific toxicity tests with test
organisms that address the assessment endpoints selected for the site. These readily available
test organisms are considered surrogates for the actual species exposed. The Regional BTAG
coordinator can identify the tests and species most appropriate for the site. Other techniques to
estimate the magnitude and severity of risks may include modeling to predict food-chain transfer
and secondary toxicity of bioaccumulative chemicals to upper trophic level receptors, the
measurement of tissue concentrations, the performance of species diversity studies (e.g., Rapid
Bioassessment Protocols), and in-situ bioassays (e.g., caged fish/bivalves). Through the use of
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field studies and/or toxicity tests, several types of data may be developed to provide supporting
information for a lines-of-evidence approach to characterizing site risks. This approach is far
superior to using single studies or tests or measurements to determine whether or not the
observed or predicted risk is unacceptable.
If studies or tests performed with site soil, sediment, or water demonstrate or predict
serious adverse effects (e.g., increased mortality, diminished growth, impaired reproduction, etc.)
on the selected assessment endpoints as compared to studies or tests conducted at an appropriate
reference site or using reference media, there is usually sufficient evidence to assume that
unacceptable adverse effects have occurred or may occur at the site. Indigenous species,
however, may be more or less sensitive than test organisms, and although toxicity tests may
demonstrate that contaminants are present in amounts potentially toxic to susceptible organisms,
the actual risks to site organisms may be of limited severity, very short-lived or reversible.
Conversely, the adverse effects may result in the loss of a critical species, which may entirely
change the dominant structure and properties of the community.
Sufficient information should be collected in the ecological risk assessment to allow the
risk assessor to make a reasoned decision about: (1) causality between levels of contamination
and effects, (2) whether the observed or predicted adverse effect on the site's local population or
community is of sufficient magnitude, severity, areal extent, and duration that they will not be
able to recover and/or maintain themselves in a healthy state, and (3) whether these effects
appear to exceed the natural changes in the components typical of similar non-site-impacted
habitats (i.e., reference areas). The information gathered in the ecological risk assessment should
provide a clear and concise estimate of overall risk to the site under review.
3. Will the cleanup cause more ecological harm than the current site contamination?
Whether or not to clean up a site based on ecological risk can be a difficult decision at
some sites. When evaluating remedial alternatives, the NCP highlights the importance of
considering both the short-term and long-term effects of the various alternatives, including the no
action alternative, in determining which ones "adequately protect human health and the
environment." Even though an ecological risk assessment may demonstrate that adverse
ecological effects have occurred or are expected to occur, it may not be in the best interest of the
overall environment to actively remediate the sjte. At some sites, especially those that have rare
or very sensitive habitats, removal or in-situ treatment of the contamination may cause more
long-term ecological harm (often due to wide spread physical destruction of habitat) than leaving
it in place. Conversely, leaving persistent and/or bioaccumulative contaminants in place where
they may serve as a continuing source of substantial exposure, may also not be appropriate.
The likelihood of the response alternatives to achieve success and the time frame for a
biological community to fully recover should be considered in remedy selection. Although most
receptors and habitats can recover from physical disturbances, risk managers should carefully
weigh both the short- and long-term ecological effects of active remediation alternatives and
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passive alternatives when selecting a final
response. This does not imply that there is a
preference for passive remediation; all
reasonable alternatives should be considered.
For example, the resilience and high
productivity of many aquatic communities
allows for aggressive remediation, whereas
the removal of bottomland hardwood forest
communities in an area in which they cannot
be restored due to water management
considerations may argue heavily against
extensive action in all but the most highly
contaminated areas.
The evaluation of ecological effects
resulting from implementing various
alternatives should be discussed in the
Feasibility Study or the Engineering
Evaluation/Cost Analysis and should include
input from the ecological risk assessor and the
federal and/or state trustees responsible for
the resources that may be impacted by the
response. (See Text Box 2.)
4. What cleanup levels are protective?
When a decision is made that a
response action should be taken at a site
based on unacceptable ecological risk, the
risk manager normally then selects chemical-
specific cleanup levels that are acceptable;
i.e., provides adequate protection of the
ecological receptors (as represented by the
selected assessment endpoints) at risk. The risk assessor can use the same toxicity tests,
population or community-level studies, or bioaccumulation models that were used to determine if
there was an unacceptable ecological risk to identify appropriate cleanup levels. Sufficient
testing and interpretation should be performed at various site locations to quantify the
relationship between chemical concentrations and effects. The data can then be used to establish
a concentration and response gradient to define the concentration that represents an acceptable
(i.e., protective) level of risk. At some relatively small sites, however, it may be more cost
effective to remove, treat, or contafn all contamination rather than to generate a concentration
and response gradient.
Text Box 2. Deciding Whether to Respond
Before making a response decision, the risk
manager, in consultation with an ecological
risk assessor, should consider in the context
of a nine-criteria evaluation under the NCP at
least the following factors:
• the magnitude of the observed or expected
effects of site releases and the level of
biological organization affected (e.g.,
individual, local population or community),
• the likelihood that these effects will occur
or continue,
• the ecological relationship of the affected
area to the surrounding habitat,
• whether or not the affected area is a highly
sensitive or ecologically unique environment,
• the recovery potential of the affected
ecological receptors and expected persistence
of the chemicals of concern under present site
conditions, and
• short- and long-term effects of the remedial
alternatives on the site habitats and the
surrounding ecosystem.
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The difficulty is in determining the acceptable level of adverse effects for the receptors to
be protected; e.g., what percent reduction in fish survival or in benthic species diversity is no
longer protective? There is no "magic" number that can be used; it is dependent on the
assessment endpoints selected and the risk assessment measures used including chemical and
biological data gathered from the range of contaminated locations and compared to the reference
locations. While it may be desirable to identify a standard numerical level of risk reduction that
is protective, it is impracticable to do this for each possible species that could be exposed. It is
for this reason that surrogate measures or representative species are used to evaluate the
ecological risks to the assessment endpoints at the site. The acceptable level of adverse effects
should be discussed by the risk assessor and risk manager as early as possible in the risk
assessment process and should be coordinated with the trustees. At sites in locations where a
large amount of data exists relating abundances or population/community indices with chemical
concentrations (e.g., Puget Sound, San Francisco Bay, the states of Ohio and Florida, and some
of the Environmental Monitoring and Assessment Program provinces), biotic indices, instead of
chemical concentrations, may also be used to select acceptable levels and to delineate the area
needing remediation.
V. IMPLEMENTATION
These principles should be followed at all sites with a planned or on going baseline
ecological risk assessment. It is the responsibility of the risk manager, in consultation with the
risk assessor, to select and document a response and cleanup levels for the site that are protective
of human health and the environment and meet or waive ARARs. The final selection of the
remedy from among alternatives that satisfy these threshold criteria can be made only after a
thorough consideration of the other seven balancing and modifying NCP criteria. The complex
nature of ecosystems, the many parameters that can affect bioavailability, and the large number
of species potentially affected at a given site may result in a relatively high degree of uncertainty
concerning the levels deemed necessary to provide overall protection of the environment. At
these sites, the risk manager should incorporate a long-term monitoring plan and a review
schedule in the Record of Decision. The data collected should be adequate to determine if
recovery is occurring in an acceptable and ecologically relevant time frame or if any additional
response action is warranted.
The Superfund program may update this guidance as more scientific information
becomes available regarding the nature of adverse effects on ecological resources resulting from
hazardous substance releases and the effectiveness of various response alternatives in alleviating
those effects. For any additional information or questions about this guidance, please contact
Steve Ells (703) 603-8822 or David-Charters (732) 906-6825.
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REGIONAL BTAG COORDINATORS
Region 1 Patti Tyler, Cornell Rosiu
Region 2 Mindy Pensak
Region 3 Jeff Turtle (Acting)
Region 4 Lynn Wellman, Sharon Thorns
Region 5 Brenda Jones, James Chapman
Region 6 Jon Rauscher, Susan Roddy
Region 7 Steve Wharton, Bob Koke
Region 8 Dale Hoff, Gerry Henningsen
Region 9 Clarence Callahan, Ned Black
Region 10 Joe Goulet
NOTICE: This document provides guidance to EPA staff and is designed to communicate
national policy on assessing and managing ecological risks. The document does not, however,
substitute for EPA's statutes or regulations, nor is it a regulation itself. Thus, it does not impose
legally-binding requirements on EPA, states, or the regulated community, and may not apply to a
particular situation based upon the circumstances of the site. EPA may change this guidance in
the future, as appropriate.
cc: Tim Fields, OSWER
Mike Shapiro, OSWER
Barry Breen, OSRE
James Woolford, FFRRO/OSWER
Guy Tomassoni, OSW
Bob Cianciarulo, Superfund-Lead Region Coordinator, Region 1
OERR Records Manager (Offutt), IMC, 5202G
OSWER Congressional Courtesy Copy Manager (Tenusak), 5103
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