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1 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON. DC. 20460
THE ADMINISTRATOR
MEMORANDUM
SUBJECT: EPA Risk Characterization Program
TO: Assistant Administrators
Associate Administrators
Regional Administrators
General Counsel
Inspector General
EPA has achieved significant pollution reduction over the past 20 years, but the challenges
we face now are very different from those of the past. Many more people are aware of
environmental issues today than in the past and their level of sophistication and interest in
understanding these issues continues to increase. We now work with a populace which is not
only interested in knowing what EPA thinks about a particular issue, but also how we come to
our conclusions.
More and more key stakeholders in environmental issues want enough information to
allow them to independently assess and make judgments about the significance of environmental
risks and the reasonableness of our risk reduction actions. If we are to succeed and build our
credibility and stature as a leader in environmental protection for the next century, EPA must be
responsive and resolve to more openly and fully communicate to the public the complexities and
challenges of environmental decisionmaking in the face of scientific uncertainty.
As the issues we face become more complex, people both inside and outside of EPA must
better understand the basis for our decisions, as well as our confidence in the data, the science
policy judgments we have made, and the uncertainty in the information base. In order to achieve
this better understanding, we must improve the way in which we characterize and communicate
environmental risk. We must embrace certain fundamental values
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so that we may begin the process of changing the way in which we interact with each other, the
public, and key stakeholders on environmental risk issues. I need your help to ensure that these
values are embraced and that we change the way we do business.
First, we must adopt as values transparency in our decisionmaking process and clarity in
communication with each other and the public regarding environmental risk and the uncertainties
associated with our assessments of environmental risk. This means that we must fully, openly,
and clearly characterize risks. In doing so, we will disclose the scientific analyses, uncertainties,
assumptions, and science policies which underlie our decisions as they are made throughout the
risk assessment and risk management processes. I want to be sure that key science policy issues
are identified as such during the risk assessment process, that policymakers are fully aware and
engaged in the selection of science policy options, and that their choices and the rationale for
those choices are clearly articulated and visible in our communications about environmental risk.
I understand that some of you may view this as unnecessarily opening ourselves up to
additional challenges and disputes from the outside. I expect that we will see more challenges,
particularly at first. However, I strongly believe that making this change to a more open
decisionmaking process will lead to more meaningful public participation, better information for
decisionmaking, improved decisions, and more public support and respect for EPA positions and
decisions. There is value in sharing with others the complexities and challenges we face in making
decisions in the face of uncertainty. I view making this change as essential to the long term
success of this Agency.
Clarity in communication also means that we will strive to help the public put
environmental risk in the proper perspective when we take risk management actions. Although I
am not suggesting that we compare environmentally-based risks to "familiar" risks, such as the
risk of having an accident while driving a car or being struck by lightning, these types of
comparisons are being used effectively by others to call into question EPA's judgments about the
significance of environmental risks. We must meet this challenge and find legitimate ways to help
the public better comprehend the relative significance of environmental risks.
Second, because transparency in decisionmaking and clarity in communication will likely
lead to more outside questioning of our assumptions and science policies, we must be more
vigilant about ensuring that our core assumptions and science policies are consistent and
comparable across programs, well grounded in science, and that they fall within a "zone of
reasonableness."
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While I believe that the American public expects us to err on the side of protection in the face of
scientific uncertainty, I do not want our assessments to be unrealistically conservative. We cannot
lead the fight for environmental protection into the next century unless we use common sense in
all we do.
These core values of transparency, clarity, consistency, and reasonableness need to guide
each of us in our day-to-day work; from the toxicologist reviewing the individual cancer study, to
the exposure and risk assessors, to the risk manager, and through to the ultimate decisionmaker. I
recognize that issuing this memo will not by itself result in any change. You need to believe in the
importance of this change and convey your beliefs to your managers and staff through your words
and actions in order for the change to occur. You also need to play an integral role in developing
the implementing policies and procedures for your programs.
I am issuing the attached EPA Risk Characterization Policy and Guidance today. I view
these documents as building blocks for the development of your program-specific policies and
procedures. The Science Policy Council (SPC) plans to adopt the same basic approach to
implementation as was used for Peer Review. That is, the Council will form an Advisory Group
that will work with a broad Implementation Team made up of representatives from every Program
Office and Region. Each Program Office and each Region will be asked by the Advisory Group
to develop program and region-specific policies and procedures for risk characterization
consistent with the values of transparency, clarity, consistency, and reasonableness and
consistent with the attached policy and guidance.
I recognize that as you develop your Program-specific policies and procedures you are
likely to need additional tools to fully implement this policy. I want you to identify these needed
tools and work cooperatively with the Science Policy Council in their development. I want your
draft program and region-specific policies, procedures, and implementation plans to be developed
and submitted to the Advisory Group for review by no later than May 30, 1995. You will be
contacted shortly by the SPC Steering Committee to obtain the names of your nominees to the
Implementation Team.
CarcrM. Browner
Attachments
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FINAL DRAFT (2/10/95)
POLICY FOR RISK CHARACTERIZATION
at the U.S. Environmental Protection Agency
Introduction
Many EPA policy decisions are based in part on the results of risk assessment,
an analysis of scientific information on existing and projected risks to human health
and the environment. As practiced at EPA, risk assessment makes use of many
different kinds of scientific concepts and data (e.g., exposure, toxicity, epidemiology,
ecology), all of which are used to "characterize" the expected risk associated with a
particular agent or action in a particular environmental context. Informed use of
reliable scientific information from many different sources is a central feature of the
risk assessment process.
Reliable information may or may not be available for many aspects of a risk
assessment. Scientific uncertainty is a fact of life for the risk assessment process, and
agency managers almost always must make decisions using assessments that are not
as definitive in all important areas as would be desirable. They therefore need to
understand the strengths and the limitations of each assessment, and to
communicate this information to ail participants and the public.
This policy reaffirms the principles and guidance found in the Agency's 1992
policy (Guidance on Risk Characterization for Risk Managers and Risk Assessors,
February 26, 1992). That guidance was based on EPA's risk assessment guidelines,
which are products of peer review and public comment. The 1994 National
Research Council (NRC) report, "Science and Judgment in Risk Assessment,"
addressed the Agency's approach to risk assessment, including the 1992 risk
characterization policy. The NRC statement accompanying the report stated,"
"... EPA's overall approach to assessing risks is fundamentally sound despite often-
heard criticisms, but the Agency must more clearly establish the scientific and policy
basis for risk estimates and better describe the uncertainties in its estimates of risk."
This policy statement and associated guidance for risk characterization is
designed to ensure that critical information from each stage of a risk assessment is
used in forming conclusions about risk and that this information is communicated
from risk assessors to risk managers (policy makers), from middle to upper manage-
ment, and from the Agency to the public. Additionally, the policy will provide a
basis for greater clarity, transparency, reasonableness, and consistency in risk
assessments across Agency programs. While most of the discussion and examples
in this policy are drawn from health risk assessment, these values also apply to
ecological risk assessment. A parallel effort by the Risk Assessment Forum to
develop EPA ecological risk assessment guidelines will include guidance specific to
ecological risk characterization.
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Policy Statement
Each risk assessment prepared in support of decision-making at EPA should
include a risk characterization that follows the principles and reflects the values
outlined in this policy. A risk characterization should be prepared in a manner that
is clear, transparent, reasonable and consistent with other risk characterizations of
similar scope prepared across programs in the Agency. Further, discussion of risk in
all EPA reports, presentations, decision packages, and other documents should be
substantively consistent with the risk characterization. The nature of the risk
characterization will depend upon the information available, the regulatory
application of the risk information, and the resources (including time) available. In
all cases, however, the assessment should identify and discuss all the major issues
associated with determining the nature and extent of the risk and provide
commentarv on any constraints limiting fuller exposition.
Key Aspects of Risk Characterization
Bridging risk assessment and risk management. As the interface between risk
assessment and risk management, risk characterizations should be clearly presented,
and separate from any risk management considerations. Risk management options
should be developed using the risk characterization and should be based on
consideration of all relevant factors, scientific and nonscientific.
Discussing confidence and uncertainties. Key scientific concepts, data and
methods (e.g., use of animal or human data for extrapolating from high to low
doses, use of pharmacokinetics data, exposure pathways, sampling methods,
availability of chemical-specific information, quality of data) should be discussed.
To ensure transparency, risk characterizations should include a statement of -
confidence in the assessment that identifies all major uncertainties along with
comment on their influence on the assessment, consistent with the Guidance on
Risk Characterization (attached).
Presenting several types of risk information. Information should be
presented on the range of exposures derived from exposure scenarios and on the use
of multiple risk descriptors (e.g., central tendency, high end of individual risk,
population risk, important subgroups, if known) consistent with terminology in the
Guidance on Risk Characterization, Agency risk assessment guidelines, and
program-specific guidance. In decision-making, risk managers should use risk
information appropriate to their program legislation.
EPA conducts many types of risk assessments, including screening-level
assessments of new chemicals, in-depth assessments of pollutants such as dioxin
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and environmental tobacco smoke, and site-specific assessments for hazardous
waste sites. An iterative approach to risk assessment, beginning with screening
techniques, may be used to determine if a more comprehensive assessment is
necessary. Tne degree to which confidence and uncertainty are addressed in a risk
characterization depends largely on the scope of the assessment. In general, the
scope of the risk characterization should reflect the information presented in the
risk assessment and program-specific guidance. When special circumstances (e.g.,
lack of data, extremely complex situations, resource limitations, statutory deadlines)
preclude a full assessment, such circumstances should be explained and their impact
on the risk assessment discussed.
Risk Characterization in Context
Risk assessment is based on a series of questions that the assessor asks about
scientific information that is relevant to human and/or environmental risk. Each
question calls for analysis and interpretation of the available studies, selection of the
concepts and data that are most scientifically reliable and most relevant to the
problem at hand, and scientific conclusions regarding the question presented. For
example, health risk assessments involve the following questions:
Hazard Identification -- What is known about the capacity of an environmental
agent for causing cancer or other adverse health effects in humans, laboratory
animals, or wildlife species? What are the related uncertainties and science
policy choices?
Dose-Response Assessment — What is known about the biological mechanisms
and dose-response relationships underlying any effects observed in the laboratory
or epidemiology studies providing data for the assessment? What are the
related uncertainties and science policy choices?
Exposure Assessment — What is known about the principal paths, patterns, and
magnitudes of human or wildlife exposure and numbers of persons or wildlife
species likely to be exposed? What are the related uncertainties and science
policy choices?
Corresponding principles and questions for ecological risk assessment are being
discussed as part of the effort to develop ecological risk guidelines.
Risk characterization is the summarizing step of risk assessment. The risk
characterization integrates information from the preceding components of the risk
assessment and synthesizes an overall conclusion about risk that is complete,
informative and useful for decisionmakers.
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Risk characterizations should clearly highlight both the confidence and the
uncertainty associated with the risk assessment. For example, numerical risk
estimates should always be accompanied by descriptive information carefully
selected to ensure an objective and balanced characterization.of risk in risk
assessment reports and regulatory documents. In essence, a risk characterization
conveys the assessor's judgment as to the nature and existence of (or lack of) human
health or ecological risks. Even though a risk characterization describes limitations
in an assessment, a balanced discussion of reasonable conclusions and related
uncertainties enhances, rather than detracts, from the overall credibility of each
assessment.
"Risk characterization" is not synonymous with "risk communication." This
risk characterization policy addresses the interface between risk assessment and risk
management. Risk communication, in contrast, emphasizes the process of
exchanging information and opinion with :he public - including individuals,
groups, and other institutions. The development of a risk assessment may involve
risk communication. For example, in the case of site-specific assessments for
hazardous waste sites, discussions with the public may influence the exposure
pathways included in the risk assessment. While the final risk assessment
document (including the risk characterization) is available to the public, the risk
communication process may be better served by separate risk information
documents designed for particular audiences.
Promoting Clarity, Comparability and Consistency
There are several reasons that the Agency should strive for greater clarity,
consistency and comparability in risk assessments. One reason is to minimize
confusion. For example, many people have not understood that a risk estimate of
one in a million for an "average" individual is not comparable to another one in a
million risk estimate for the "most exposed individual." Use of such apparently
similar estimates without further explanation leads to misunderstandings about the
relative significance of risks and the protectiveness of risk reduction actions.
EPA's Exposure Assessment Guidelines provide standard descriptors of
exposure and risk. Use of these terms in all Agency risk assessments will promote
consistency and comparability.' Use of several descriptors, rather than a single
descriptor, will enable EPA to present a fuller picture of risk that corresponds to the
range of different exposure conditions encountered by various individuals and
populations exposed to most environmental chemicals.
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Legal Effect
This policy statement and associated guidance on risk characterization do not
establish or affect legal rights or'obligations. Rather, they confirm the importance of
risk characterization as a component of risk assessment, outline relevant principles,
and identify factors Agency staff should consider in implementing the policy.
Tne policy and associated guidance do not stand alone; nor do they establish a
binding norm that is finally determinative of the issues addressed. Except where
otherwise provided by-law, the Agency's decision on conducting a risk assessment in
any particular case is within the Agency's discretion. Variations in the application
of the policy and associated guidance, therefore, are not a legitimate basis for
delaying or complicating action on Agency decisions.
Applicability
Except where otherwise provided by law and subject to the limitations on the
policy's legal effect discussed above, this policy applies to risk assessments prepared
by EPA and to risk assessments prepared by others that are used in support of EPA
decisions.
EPA will consider the principles in this policy in evaluating assessments
submitted to EPA to complement or challenge Agency assessments. Adherence to
this Agency-wide policy will improve understanding of Agency risk assessments,
lead to more informed decisions, and heighten the credibility of both assessments
and decisions.
Implementation
Assistant Administrators and Regional Administrators are responsible for
implementation of this policy within their organizational units. The Science Policy
Council (SPC) is organizing Agency-wide implementation activities. Its
responsibilities include promoting consistent interpretation, assessing Agency-wide
progress, working with external groups on risk characterization issues and methods,
and developing recommendations for revisions of the policy and guidance, as
necessary.
Each Program, and Regional office will develop office-specific policies and
procedures for risk characterization that are consistent with this policy and the
associated guidance. Each Program and Regional office will designate a risk
manager or risk assessor as the office representative to the Agency-wide Implementa-
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tion Team, which will coordinate development of office-specific policies and
procedures and other implementation activities. The SPC will also designate a
small cross-Agency Advisory Group that will serve as the liaison between the SPC
and the Implementation Team.
In ensuring coordination and consistency among EPA offices, the
Implementation Team will take into account statutory ajid court deadlines, resource
implications, and existing Agency and program-specific guidance on risk
assessment. The group will work closely with staff throughout Headquarters and
Regional offices to promote development of risk characterizations that present a full
and complete picture, of risk that meets the needs of the risk managers.
APPROVED:
Carol M. Brown«r, Administrator
DATE:
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