oEPA
United States
Environmental Protection
Agency
EPA/1 OO/R-14/001 April 2014
www.epa.gov/raf
Framework for Human Health Risk Asse:
to Inform Decision Making
Office of the Science Advisor
Risk Assessment Forum
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Framework for Human Health Risk Assessment
to Inform Decision Making
April 5, 2014
U.S. Environmental Protection Agency
Office of the Science Advisor
Risk Assessment Forum
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The Risk Assessment Forum dedicates this Framework to
Ira William Leighton Jr.
Deputy Regional Administrator - Region 1
2000-2013
41 Years of Service to the U.S. Environmental Protection Agency
for his dedication to risk assessment and in response to his 2010 challenge
to the Risk Assessment Forum to produce actionable products that advance
risk assessment and improve real life decision making.
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Table of Contents
Foreword viii
Preface ix
List of Acronyms x
Executive Summary xi
1. Introduction 1
1.1 Background and History 1
1.2 Scope and Purpose 2
1.3 Fit for Purpose 4
1.4 Overview of the Framework 5
2. Initiation of the Risk Assessment Process 10
2.1 Planning and Scoping 10
2.1.1 Context, Purpose and Scope 13
2.1.2 Overarching Considerations 15
2.1.3 Responsibilities, Resources and Timeline 20
2.1.4 Opportunities for Scientific Peer Review or Other Review Steps 21
2.1.5 Public, Stakeholder and Community Involvement 22
2.1.6 Past Experiences and Assessments 24
2.2 Problem Formulation 24
2.2.1 Conceptual Model 25
2.2.2 Analysis Plan 29
3. Public, Stakeholder and Community Involvement 35
3.1 Audiences for the Risk Assessment 36
3.1.1 Stakeholders 36
3.1.2 Community 37
3.2 Communication 38
4. Risk Assessment 39
4.1 Exposure Assessment 39
4.2 Effects Assessment 41
4.2.1 Hazard Identification 41
4.2.2 Dose-Response Assessment 43
4.3 Risk Characterization 43
4.4 Characterizing the Risks for Risk Managers 45
5. Informing Decisions 47
6. Summary 49
References 52
Appendix I. Examples of EPA Program-Specific Resources and Guidance on Risk Assessment Activities62
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List of Text Boxes
Text Box 1-1. Examples of EPA Actions Informed by Risk Assessments 1
Text Box 1-2. Examples of Key EPA Documents Describing Risk Assessment Frameworks 2
Text Box 1 -3. General Principles of the Framework for Human Health Risk Assessment 3
Text Box 1-4. Silver Book Statements on Utility 4
Text Box 2-1. EPA References on Planning and Scoping 10
Text Box 2-2. Examples of Risk Assessment Planning and Scoping at EPA 12
Text Box 2-3. The Silver Book Statements on Risk Assessment and Decision Context 13
Text Box 2-4. Risk Assessment for Economic Benefits Analysis 16
Text Box 2-5. Key EPA Children's Health Guidance Documents 17
Text Box 2-6. Approaches to Cumulative Risk Assessment 19
Text Box 2-7. Resources on Sustainability and Life Cycle Assessment 20
Text Box 2-8. Definitions of "Public," "Stakeholder" and "Community" 22
Text Box 2-9. Examples of Conceptual Models in EPA Risk Assessments 27
Text Box 2-10. EPA Resources on Conceptual Models 27
Text Box 2-11. Data Quality Resources 30
Text Box 2-12. EPA Exposure Assessment Resources for Human Health 31
Text Box 2-13. EPA Resources on Hazard Identification and Dose-Response Assessment 32
Text Box 2-14. Risk Analyses Resources 33
Text Box 2-15. Definitions of Uncertainty and Variability 34
Text Box 3-1. Resources for Public Involvement Efforts, Tools and Policies 37
Text Box 4-1. Key Elements of an Exposure Assessment 41
Text Box 4-2. Example of a Consideration for Effects Characterization: Mode of Action 42
Text Box 4-3. Characterizing Cancer Risk from Early-Life Exposure 45
Text Box 6-1. The Silver Book Recommendations for a Human Health Risk Assessment Framework 49
List of Figures
Figure 1 -1. Framework for Human Health Risk Assessment to Inform Decision Making 7
Figure 2-1. Framework for Human Health Risk Assessment to Inform Decision Making: Key Considerations
for Planning and Scoping 13
Figure 2-2. Framework for Human Health Risk Assessment to Inform Decision Making: Key Questions and
Considerations for Problem Formulation 25
Figure 2-3. Example of a Generalized Conceptual Model With Examples of Possible Dimensions and Linkages
27
Figure 2-4. Example Conceptual Model of Exposure Pathways for Multiple Receptors to Multiple Stressors for
Superfund Site Assessment 28
Figure 3-1. Framework for Human Health Risk Assessment to Inform Decision Making: Key Questions and
Considerations for Public, Stakeholder and Community Involvement 35
Figure 4-1. Framework for Human Health Risk Assessment to Inform Decision Making: Key Questions and
Considerations for Assessment 40
Figure 5-1. Framework for Human Health Risk Assessment to Inform Decision Making: Key Questions and
Considerations for Informing Decisions 48
Figure 6-1. Framework for Human Health Risk Assessment to Inform Decision Making 50
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Risk Assessment Forum Technical Panel
Rita Schoeny (Co-Chair) Office of Research and Development
Kathryn Gallagher (Co-Chair) Office of Water
Julie Fitzpatrick (Science Coordinator) Office of the Science Advisor/Risk Assessment Forum Staff
Kacee Deener Office of Research and Development
Chris Dockins Office of Policy
Michael Firestone Office of Children's Health Protection
William Jordan Office of Chemical Safety and Pollution Prevention
Margaret McDonough Region 1
Deirdre Murphy Office of Air and Radiation
Marian Olsen Region 2
Kathleen Raffaele Office of Solid Waste and Emergency Response
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Disclaimer
This document has been reviewed in accordance with the U.S. Environmental Protection Agency's peer and
administrative review policies and approved for publication. Mention of trade names or commercial products
does not constitute endorsement or recommendation for use.
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Foreword
This document is a direct result of the 2010 EPA Human Health Risk Assessment Colloquium, where
approximately 120 risk assessors and decision makers from across the Agency convened to develop a plan to
advance human health risk assessment at EPA, focusing on the recommendations presented in three National
Academy of Sciences (NAS) National Research Council (NRC) reports: Science and Decisions: Advancing
Risk Assessment; Phthalates and Cumulative Risk Assessment: The Tasks Ahead; and Toxicity Testing in the
21st Century: A Vision and A Strategy (NRC 2007, 2008, 2009).
In Science and Decisions, the NRC recommended that EPA adopt a framework for risk-based decision making
that maximizes the utility of risk assessment. The EPA Risk Assessment Forum Colloquium Planning
Committee assembled a work group that presented a framework for discussion at the 2010 Colloquium. The
framework considered the NRC's recommendations and built upon existing Agency guidance. During the
Human Health Framework Subgroup session at the Colloquium, participants agreed that adopting a human
health risk assessment framework would increase the Agency's ability to maximize the utility of risk
assessment by emphasizing the need to focus the design of risk assessments on the decision-making process.
The Subgroup suggested that the framework should tie together existing human health frameworks and
guidance, as well as be flexible enough to accommodate the range of assessments conducted across the Agency
and changes in the science of risk assessment. They also agreed with the NRC that the framework should
integrate concepts regarding risk assessment processes such as planning and scoping, as well as problem
formulation, which are described in the Framework for Ecological Risk Assessment, Guidelines for Ecological
Risk Assessment, and Guidance on Cumulative Risk Assessment. Part 1. Planning and Scoping (USEPA
1992a, 1997a, 1998a). This document is a product of the Colloquium participants' recommendations and the
subsequent work of the Risk Assessment Forum's Human Health Risk Assessment Framework Technical
Panel.
Capacity building, including Agency-wide outreach and training for both risk assessors and risk managers, is
needed to institutionalize the concepts presented herein into Agency risk assessment practices. It is critical that
this outreach and training occur to make this Framework a living, high-impact document that will enhance the
utility of risk assessments in decision making.
As mentioned above, many people from across the Agency were involved in the 2010 EPA Human Health
Risk Assessment Colloquium and the development of this Framework, as guided by EPA's Risk Assessment
Forum and Science and Technology Policy Council. Special acknowledgment is given to the Human Health
Risk Assessment Framework Technical Panel and the Risk Assessment Forum staff who worked together
diligently to develop this high-quality document in a timely manner.
It is with great pleasure that I present the Framework for Human Health Risk Assessment to Inform Decision
Making.
Glenn Paulson, Ph.D.
EPA Science Advisor
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Preface
This document describes the EPA framework for conducting human health risk assessments that are responsive
to the Agency's decision-making needs. It is intended to provide information on the overarching process for
conducting human health risk assessments to the U.S. Environmental Protection Agency's (EPA or Agency)
staff and managers, external stakeholders, and the public. This Framework is expected to promote and increase
the transparency of the human health risk assessment process at the EPA. It highlights the important roles of
planning and scoping, as well as problem formulation, in designing a risk assessment that will fulfill a specific
need and purpose. Consistent with longstanding EPA policy, it also emphasizes the importance of scientific
peer review and public, stakeholder and community involvement. This document is not intended to supersede
existing EPA guidance; by citing and discussing existing guidance, it is intended instead to foster increased
implementation and utility of such guidance.
The Framework was prepared by a Technical Panel composed of senior risk assessors and risk managers from
across the Agency overseen by the Risk Assessment Forum. The Risk Assessment Forum is a standing
committee of senior EPA scientists that was established to promote Agency-wide consensus on risk assessment
issues and to ensure that this consensus is incorporated into appropriate Agency risk assessment guidance.
In preparing this document, the Technical Panel considered the recommendations presented in three NRC
reports that explored advancing risk assessment, adopting a cumulative approach to risk assessment and
rethinking toxicity testing (NRC 2007, 2008, 2009). One of the key recommendations provided to the Agency
by the NRC in Science and Decisions: Advancing Risk Assessment was to adopt a framework for risk-based
decision making that maximizes the utility of risk assessment. This Framework has been developed with
particular consideration of this NRC recommendation in light of EPA's broad array of decision-making
contexts. The Framework is inherently flexible with regard to the type of and context for risk assessments, and
the potential for Agency methods to evolve in response to changes in the science of risk assessment. Thus, the
Framework is expected to facilitate the development of risk assessments focused on and in support of the
Agency needs of the decision-making process now and in the future.
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List of Acronyms
ADAF Age-Dependent Adjustment Factor
AIEO American Indian Environmental Office
CAA Clean Air Act
CASAC Clean Air Scientific Advisory Committee
CERCLA Comprehensive Environmental Response, Compensation, and Liability Act
CWA Clean Water Act
EJ Environmental Justice
EPA U.S. Environmental Protection Agency
FQPA Food Quality Protection Act
GIS Geographic Information System
HPV High Production Volume
IRIS Integrated Risk Information System
IRP Integrated Review Plan
ISA Integrated Science Assessment
MOA Mode of Action
NAAQS National Ambient Air Quality Standards
NAS National Academy of Sciences
NRC National Research Council
OAQPS Office of Air Quality Planning and Standards
OMB Office of Management and Budget
OPPT Office of Pollution Prevention and Toxics
ORD Office of Research and Development
OSWER Office of Solid Waste and Emergency Response
PCB Polychlorinated biphenyl
PCCRARM Presidential/Congressional Commission on Risk Assessment and Risk Management
PMN Premanufacture Notice
REA Risk and Exposure Assessment
SAB EPA Science Advisory Board
SDWA Safe Drinking Water Act
TCCR Transparency, Clarity, Consistency and Reasonableness
TSCA Toxic Substances Control Act
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Executive Summary
The purpose of this document is to describe a process for conducting human health risk assessments that are
responsive to the decision-making needs of EPA. The Framework for Human Health Risk Assessment to
Inform Decision Making (Framework) is further intended to facilitate implementation of existing and future
EPA guidance for conducting human health risk assessments and improve the utility of risk assessment in the
decision-making process. The Framework addresses recommendations on risk assessment design and utility
described in the National Research Council's (NRC) 2009 report, Science and Decisions: Advancing Risk
Assessment, and those put forth in earlier NRC reports (e.g., NRC 1994). This Framework highlights the
important roles of planning and scoping, as well as problem formulation, in designing a risk assessment that
will serve a specific and documented purpose. In accordance with longstanding Agency policy, it also
emphasizes the importance of scientific peer review, as well as public, stakeholder and community
involvement.
The key elements of the process for developing a risk assessment to inform decision making are as follows:
• Planning and scoping: In this element, the process for conducting the risk assessment and its general
scope are defined. This activity contributes to development of a sound risk assessment that serves its
intended purpose. It also assists those interested in the risk assessment process in understanding the
context of the risk assessment and the intended use of its results. A broad range of technical experts
working as a team may be involved in this stage.
• Problem formulation: This analytical consideration of the issue being assessed identifies the major
factors to be considered in a specific assessment, thus informing the technical approach. An important
outcome of problem formulation is a conceptual model that describes the linkages between stressors
and adverse human health effects, including the stressor(s), exposure pathway(s), exposed lifestage(s)
and population(s), and endpoint(s) that will be addressed in the risk assessment. Based on the
conceptual model, an analysis plan is developed, which describes the approach for conducting the risk
assessment, including its design, methods and key inputs and intended outputs.
• Risk Assessment
• Exposure and effects assessment: Exposure assessment, a core component of a risk assessment,
will reflect the considerations identified in problem formulation. The parallel core component,
effects assessment, includes hazard identification and dose-response assessment. Susceptible or
more highly exposed populations may be identified in these assessments, when relevant
information is available.
• Risk characterization: This step of the risk assessment, in which the exposure and effects
assessments are integrated, provides risk managers with risk estimates and a useful, synthesized
set of conclusions about the risk. It is intended to adhere to four principles: transparency, clarity,
consistency and reasonableness (TCCR).
• Public, stakeholder and community involvement: Input from the public is sought and considered at
various stages throughout the process. Such input is essential to the Agency in fulfilling its mission to
protect human health and the environment.
• Informing decisions: The goal of the risk assessment team is to provide a comprehensive assessment
for a range of possible risk management options. The description of the decision should clarify how
the risk assessment and other factors informed the decision.
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The Framework reflects the NRC's recommendations on assuring that risk assessments are well-tailored to the
problems and decisions at hand so that they can inform the decision-making process in the most meaningful
way (NRC 2009). In describing these recommendations, the NRC uses the term "utility of risk assessment,"
among others (NRC 2009). The term "fit for purpose" used in this document is an established quality
assurance principle aimed at assuring that the product is suitable for its intended purpose. The NRC's four-step
risk assessment paradigm (NRC 1983) is maintained in the current Framework, but there is increased emphasis
on assuring the utility of each risk assessment. The utility of risk assessment is not something that is evaluated
as a separate step in the process or as a final check that occurs once the risk assessment is completed. Instead,
an emphasis on the utility of the risk assessment for informing risk management decisions begins with
planning and scoping and continues throughout the process.
Overall, the Framework stresses the practical nature of risk assessment; it highlights the need for analysis in
support of decision making and additionally recognizes areas of overarching Agency interest, including
children's environmental health and environmental justice (EJ). The Framework encourages the consideration
of innovative technology and concepts in the still-developing area of sustainability in environmental decision
making. The Framework supports enhanced dialogue between risk assessors and risk managers while
recognizing the differences in their distinct roles.
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1. Introduction
1.1 Background and History
Since EPA's inception, risk assessment has informed decisions made to protect human health and the
environment from a range of threats. Overtime, the scientific approaches and methods employed for
these risk assessments have evolved. Risk assessments performed by the Agency inform a broad range of
regulatory decisions. See Text Box 1-1. Thus, the design, objectives and specific outputs of risk
assessments vary depending on the purpose and governing statute. EPA economic analyses also may
assess risk to estimate the value of health benefits associated with regulatory options and actions.
The Framework for Human Health Risk
Assessment to Inform Decision Making
(Framework), presented in this document, draws
on Agency experience and addresses the
recommendations on risk assessment process
from the National Research Council's (NRC)
2009 report, Science and Decisions: Advancing
Risk Assessment (NRC 2009), also known as the
Silver Book. In particular, this Framework seeks
to address Silver Book recommendations on the
design of risk assessments and opportunities for . . . . . ... . , ,
0 . , . .,. ^ _, *^ , , • Ambient air quality standards.
improving their utility. The Framework draws on
a considerable body of additional expert advice,
beginning with the NRC's 1983 report, Risk
Assessment in the Federal Government: , ,
,, . ^ n , , r i . • Ambient Water Quality Criteria for surface
Managing the Process (commonly referred to as
the Red Book), followed by the NRC's 1994 waters.
Text Box 1-1. Examples of EPA Actions
Informed by Risk Assessments
• Pesticide usage restrictions.
• Hazardous waste site remediation goals and
approaches.
• Regulation of hazardous materials usage,
storage and disposal.
• Emissions standards for hazardous air
pollutants.
report, Science and Judgment in Risk Assessment (commonly referred to as the Blue Book), as well as
incorporates principles from the Agency's extensive human health risk assessment guidance. Following
publication of the Red Book, the Agency issued Risk Assessment and Management: Framework for
Decision Making (USEPA 1984), which first articulated EPA's risk assessment framework. In 1984, the
Agency established what is now called the Risk Assessment Forum, and in 1986, EPA formed the Risk
Assessment Council, which was replaced in 1993 by the Science Policy Council (now named the Science
and Technology Policy Council). Shortly after publication of the Red Book, EPA began issuing a series of
guidelines for conducting risk assessments in a number of areas (e.g., cancer, chemical mixtures.
developmental toxicity. exposure assessment, mutagenicity. neurotoxicity. reproductive toxicity) (USEPA
1986a, 1987, 2005b, 1986c, 2000e, 1991b, 1992b, 1986b, 1998b and 1996). Many of these original
Agency-wide risk assessment guidelines include frameworks that have been updated over time.
In its emphasis on the planning aspects of conducting risk assessments, this Framework builds on
principles of EPA's 1997 Guidance on Cumulative Risk Assessment. Part 1. Planning and Scoping, which
described an approach for integrated risk assessment and management (USEPA 1997a). The 1997
guidance was designed to help risk managers and assessors plan and document the scope of risk
assessments, as well as consider appropriate (e.g., technical, advisory, stakeholder) participants and
information sources to enrich the risk assessment. Additionally, the 1997 guidance augmented the
Agency's 1995 Guidance for Risk Characterization (USEPA 1995a) by emphasizing the need for
providing a transparent, clear, consistent and reasonable basis for any assessment, as well as strongly
encouraging the undertaking of a formal problem formulation exercise for all risk assessments.
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Prior to the Guidance on Cumulative Risk Assessment. Part 1. Planning and Scoping (USEPA 1997a), the
Agency published the Framework for Ecological Risk Assessment (USEPA 1992a) and subsequently
released the Guidelines for Ecological Risk Assessment (USEPA 1998a), which incorporated planning
and scoping into the ecological risk assessment process. In 2003, the Framework for Cumulative Risk
Assessment (USEPA 2003b) further built on these documents in formulating a flexible structure for
conducting a risk assessment to evaluate cumulative human health or ecological risk. In 2006, the Agency
published A Framework for Assessing Health Risk of Environmental Exposures to Children, which
applied this general structure (including problem formulation, analysis and risk characterization) in
describing risk assessments focused on evaluating potential risks arising as a result of early life exposure
(USEPA 2006b). In addition to these more general Agency documents, individual programs and offices
have implemented risk assessment frameworks specific to their missions. Examples of documents with
risk assessment frameworks are provided in Text Box 1-2. Finally, EPA has developed a Risk Assessment
Portal (USEPA 2014) for the EPA website that provides basic information about environmental risk
assessments and offers a comprehensive set of links to key Agency tools, policies, guidance and
guidelines.
The document discusses aspects
of the interaction of risk
assessment and management,
focusing on the utility of a risk
assessment to aid in making
choices among risk management
options. In this context, we refer
to a well-conducted, useful risk
assessment, one that specifically
fits its intended purpose. A risk
assessment that does not support
informed choices will be less
useful than one that does. In
addition, the risk management
context (e.g., regulatory decision
making) will affect the risk
assessment in many ways.
Statutory or regulatory
requirements and restrictions,
including those established by
states and tribal nations, may
place boundaries on risk
management options. Court
decisions also can affect how the
U.S. Environmental Protection
Agency (EPA) considers
assessments of risk.
Text Box 1-2. Examples of Key EPA Documents Describing Risk
Assessment Frameworks
• Risk Assessment Guidance for Superfund (RAGS) Part A (USEPA
1989).
• Framework for Ecological Risk Assessment (USEPA 1992a).
• Guidance on Cumulative Risk Assessment. Part 1. Planning
and Scoping (USEPA 1997a).
• Guidelines for Ecological Risk Assessment (USEPA 1998a).
• Risk Characterization: Science Policy Handbook (USEPA
2000d).
• Framework for Cumulative Risk Assessment (USEPA 2003b).
• "Human Health Risk Assessment: Inhalation" In Air Toxics Risk
Assessment Library. Vol. 1. Technical Resource Manual (USEPA
2004c, 5-3).
• A Framework for Assessing Health Risk of Environmental
Exposures to Children (USEPA 2006b).
• Office of Pollution Prevention and Toxics' (OPPT)
Requirements for Submitting Electronic Pre-manufacture
Notices (PMNs) (USEPA 2010d).
1.2 Scope and Purpose
The purpose of this document is to describe a process for conducting human health risk assessments that
are responsive to EPA's decision-making needs. It provides an organizing structure for implementing
existing and future EPA guidance on human health risk assessment. Rather than establishing new
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guidance, this Framework compiles existing Agency policy, guidance and guidelines into a single
coherent document. This document is intended to serve as a useful resource. Toward that end, text boxes
throughout the document cite relevant Agency materials to which risk assessors may refer based on the
needs of a particular assessment.
This Framework highlights the important role of planning and scoping in designing a risk assessment so
that it serves its intended purpose, as well as the importance of scientific review and public, stakeholder
and community involvement. The Framework also moves the Agency forward in the harmonization of
human health and ecological risk assessment methodology. This Framework is expected to promote and
increase the transparency of the human health risk assessment process at the Agency. It is consistent with
EPA's Scientific Integrity Policy (USEPA 2012s) and follows the general principles presented in Text
Box 1-3.
Text Box 1-3. General Principles of the Framework for Human Health Risk Assessment
• A risk assessment should be fit for its intended purpose.
• A risk assessment should state its purpose, context and scope clearly.
• Risk assessments should be based on exposure scenarios that are consistent with the purpose and
context. As appropriate, they should include consideration of susceptible population groups and
life stages.
• Risk assessments should follow an acceptable, overtly logical path, employing common sense and
sound judgment in applying relevant guidance.
• All steps, key assumptions, limitations and decisions, as well as associated rationales, should be
presented clearly.
• The role of scientific peer review should be considered.
• Public involvement should be considered.
• Risk assessments should be presented in a readily understandable and useful form for the
intended audiences.
In summary, this Framework describes approaches for organizing and conducting human health risk
assessments; it complements but does not replace any existing guidance or guidelines. Building on the
Agency's experience and NRC recommendations, the Framework is intended to identify the critical
aspects of the risk assessment process within a formal but flexible structure. The Framework is not
intended to be an exhaustive reference on all relevant guidance; instead, the Framework is intended to
describe the overall process clearly, giving attention to critical aspects of each component, focusing on
the less technical (more process-associated) components of the process and identifying relevant references
for the more technical components. It describes and discusses a series of steps and considerations
important to formulating and performing a risk assessment to inform decisions. A major objective of the
Framework is to improve the consistency and transparency of risk assessments while enhancing
harmonization of approaches across the Agency. The Framework aims to maximize the utility of the risk
assessment for informing risk management decisions, as well as ensure the most efficient use of resources
by aligning the nature and/or scope of the risk assessment with the decision to be made.
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1.3 Fit for Purpose
Risk assessments at EPA are performed to inform risk management decisions. Accordingly throughout
the process of planning and performing the analyses, it is important to confirm that the assessment will
address the information needs of the decision makers. Periodic confirmations may be part of the review
steps described above or may be done as they otherwise fit within the process of the assessment. In the
Silver Book (NRC 2009), the NRC recommended the use of a framework that "maximizes the utility of
risk assessment," with a focus on assuring that risk assessments are well-tailored to the problems and
decisions at hand so that they can inform the decision-making process most meaningfully. In describing
this concept, the 2009 NRC report recommends development of a framework to improve the utility of risk
assessment. See Text Box 1-4. With this framework document, EPA introduces the concept of "fit for
purpose" to characterize risk assessments that are designed to maximize the utility of risk assessments for
their intended purpose in Agency decision making. Consistent with its usage as a key principle in quality
assurance programs, "fit for purpose" in this Framework refers to the development of risk assessments
and associated products that are suitable and useful for their intended purpose(s), particularly for
informing risk management decisions.
In EPA's Framework described here, the utility of
risk assessment is not evaluated as a separate step
in the process or in a final check that occurs once
the risk assessment is completed. Instead,
consistent with the NRC's emphasis on
consideration of risk management needs early in
the process, the Agency's Framework emphasizes
attention to utility throughout the process,
beginning with planning and scoping, and
including a specific focus on the applicability of
the risk assessment for informing risk
management decisions. Attention is given to this
concept through focused planning and problem
formulation, as well as confirmation during the
process, to ensure that the informational needs for
the assessment are being met by the information
being generated by the assessment. The
overarching questions in addressing "fit for
purpose" are the following:
Text Box 1-4. Silver Book Statements on Utility
• "Risk assessment in EPA is not an end in itself
but a means to develop policies that make
the best use of resources to protect the
health of the public and of ecosystems" (NRC
2009, 240).
• "By focusing on early and careful problem
formulation and on the options for managing
the problem, implementation of the
framework can do much to improve the
utility of risk assessment. Indeed, without
such a framework, risk assessments may be
addressing the wrong questions and yielding
results that fail to address the needs of risk
managers" (NRC 2009, 244).
• Does the assessment inform choices among risk management options?
• Will the risk assessment need to be changed or expanded to discriminate between risk
management options?
Questions to consider in evaluating the usefulness of the risk assessment design and its implementation
include those listed below:
• Does the risk assessment design meet the objectives and does it have the attributes identified in
the problem formulation step?
• Does the assessment, as implemented, meet the initial objectives, and is it consistent with the
attributes identified in problem formulation? Or, if the initially identified objectives or attributes
have been modified, does the assessment incorporate the modifications?
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• If the assessment requires peer review, has this been done appropriately, and have the issues
raised during the peer review been addressed adequately?
• How will the results of the risk assessment be communicated to the risk managers and
stakeholders?
Depending on the answers to these and other questions, additional or revised analyses may be considered
in the assessment that may reflect the specific risk management decision being addressed. Rather than a
separate step or final check in the process once the risk assessment is completed, this emphasis on the
utility of the risk assessments occurs throughout the process with the team continually mindful of the end
use of the assessment.
The utility of the risk assessment is defined by the degree to which the assessment informs choices among
risk management options. Related to this, it is critical that there be transparent dialogue between risk
assessors and risk managers throughout the assessment process, beginning with the planning stage. It is
important to note, however, that EPA maintains the conceptual distinction between risk assessment and
risk management, as described in the Red Book (NRC 1983); the Framework does not allow for the
manipulation of the risk assessment to support predetermined policy or management choices. As
articulated by the NRC in the Silver Book. "[T]he conduct of risk assessments used to evaluate the risk-
management options [is] in no way to be influenced by the preferences of risk managers" (NRC 2009,
244). For more information on the conduct of risk assessment from the Silver Book, see Section 2.1.
It is important to note that the uses of any risk assessment will vary with the environmental problem being
assessed; statutory mandates; and limitations of data, methods, time and resources. Further as recognized
in Section 5, risk assessments often are just one of a variety of factors that are considered in making a
decision.
1.4 Overview of the Framework
The Framework for Human Health Risk Assessment to Inform Decision Making in its most basic form is
illustrated in Figure 1-1. This figure reflects the main elements of the Framework and their roles in the
risk assessment process in a form that encompasses the broad range of EPA risk assessment contexts. The
figure conveys a path from planning and scoping to informing decisions and illustrates that the process
provides opportunities for feedback along this path, which may vary among applications.
In building on the basic components identified in the Red Book (NRC 1983) and on processes currently
employed across the Agency, this Framework takes into account key recommendations from the Silver
Book (NRC 2009) that called for more interaction among risk assessors and risk managers during the
course of a risk assessment while recognizing and keeping separate their distinctly different roles (NRC
2009). Thus, this Framework emphasizes the importance of early identification of risk management
options so that risk assessment can inform choices most efficiently among such options. Risk
management decisions are beyond the scope of the risk assessment proper; a risk assessment is one of the
sources of information that informs the particular decision at hand. As discussed in Section 5 of this
document, the risk assessment should not "make" the decision; it should characterize the estimated risk.
The Framework emphasizes planning to maximize the utility of the risk assessment for informing risk
management decisions.
The Framework reflects the often iterative nature of risk assessment; for example, as some scientific
questions are answered, new ones may emerge that require the generation of additional data and/or
analyses that better define the distribution of risk and/or address uncertainty. Throughout the process,
additional knowledge may result in further refinement of the conceptual model and analysis plan.
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Finally, this document recognizes a role for areas of overarching Agency interest, such as EPA's Policy
on Evaluating Health Risks to Children (USEPA 1995b), assessment of cumulative risk (USEPA 2003b),
consideration of environmental justice (EJ) (USEPA 201 Ob, Interim Guidance on Considering
Environmental Justice During the Development of an Action}, and the concept of sustainability in risk
management decision making. Executive orders that apply to these areas are Executive Order 13045
(Clinton 1997, Protection of Children From Environmental Health Risks and Safety Risks) and Executive
Order 12898 (Clinton 1994, Federal Actions To Address Environmental Justice in Minority Populations
and Low-Income Populations).
The main elements of the Framework are discussed in the subsequent sections of this document. The
concept of "fit for purpose," described in Section 1.3, is discussed throughout the document in keeping
with the need for its consideration from planning through execution to ensure that assessments inform the
decision-making process most meaningfully. Sections focused on the other elements are described below:
• Planning and scoping and problem formulation are detailed in Section 2 (Initiation of the Risk
Assessment Process).
• Public, stakeholder and community involvement are addressed in Section 3 (Public, Stakeholder
and Community Involvement).
• Exposure and effects assessment and risk characterization are discussed in Section 4 (Risk
Assessment).
• Informing decisions is discussed in Section 5 (Informing Decisions).
As described in the Silver Book (NRC 2009), the process begins with a decision to conduct a risk
assessment based on what is described as a "signal" of potential harm. Generally, this assessment would
involve a set of existing or potential environmental conditions and the context may vary broadly (e.g.,
from consideration of a contaminated waste site to review of ambient air standards to a proposal for new
chemicals to be introduced into commerce). The process outlined in the Framework initiates activities on
the assessment of the risk potential of the environmental conditions.
The initial stage in conducting any EPA risk assessment focuses on carefully characterizing the task to be
completed; it includes planning and scoping and problem formulation components. The planning and
scoping phase involves consideration of the specific environmental issue to be addressed; the legal
framework under which any action will be taken; the risk management options; and the public-,
stakeholder- or community-specific issues. Specific regulatory or programmatic requirements are
considered throughout the planning process. An essential question in this phase is what level of
complexity is required (e.g., screening, deterministic or probabilistic risk assessment) to inform the
necessary decision(s). Planning and scoping also include the identification of resources available to
complete the assessment and the formation of a risk assessment team that will be capable of performing
the technical analyses that may be needed. The team members may include a project manager, risk
assessor and other staff with the appropriate expertise necessary to address the specific question. Based on
the information developed during planning and scoping, the problem formulation then is conducted to
develop a conceptual model and incorporate the information into an analysis plan. The analysis plan
outlines how the exposure assessment, effects assessment (hazard and dose-response) and risk
characterization components of the risk assessment will be conducted, with consideration of data quality;
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Figure 1-1. Framework for Human Health Risk Assessment to Inform Decision Making
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uncertainty and variability; and public, stakeholder and community involvement for each component, as
appropriate. The risk assessment then is conducted based on the analysis plan developed during problem
formulation. The risk assessment phase includes developing the exposure and effects characterizations
and integrating those results for presentation as part of the risk characterization. A key aspect of this
Framework is an emphasis on the concept of "fit for purpose" by evaluating the applicability of the risk
assessment to informing risk management decisions; these evaluations may take place at several points of
the iterative risk assessment process. Focus is maintained on the information needs for the risk
management decisions by asking whether the assessment is achieving its objective to inform decisions. If
the answer is 'no', then the risk assessment team can make adjustments, revisit steps or develop additional
information as needed.
The risk assessment or its components may be evaluated via independent peer review consistent with the
Peer Review Handbook (EPA 2006e). Input may also be solicited from public, stakeholder and/or
affected communities, recognizing that approaches for addressing these different audiences will vary
among assessments (USEPA 2012m). Independent peer review helps to ensure the integrity and quality of
the scientific and technical aspects of the risk assessment. This review may involve internal and/or
external technical reviewers. Input from the public, internal and external stakeholders, and the affected
community(ies) can provide insights that otherwise may not be available to risk managers, but these
inputs should not compromise the integrity or quality of the scientific and technical aspects of the risk
assessment.
In the decision making process, information in the risk assessment report is considered to evaluate the risk
management options. This evaluation is undertaken in light of all appropriate factors and under applicable
authorities. During this "Informing Decisions" phase (noted in Figure 1-1), additional analysis needs may
be identified, which may lead to iteration of previous steps. This phase also generally includes
development of a strategy for communicating conclusions with the public, internal and external
stakeholders, and affected community(ies). In addition, plans may be made to evaluate the outcome of
any actions taken.
The following example describes the current process for conducting reviews of the National Ambient Air
Quality Standards (NAAQS) (USEPA 20121, Process of Reviewing the National Ambient Air Quality
Standards}. This process includes explicit phases for planning (that includes planning and scoping and
problem formulation), assessment of currently available scientific evidence (including that on hazard and
dose-response relationships), risk and/or exposure assessment, and policy assessment and rulemaking.
With each phase, there is consideration of the need for external peer review and/or public comment.
Although each component or step in this example may not rely on precisely the same terms as those used
in this Framework document, the example illustrates one manner by which EPA implements the key
aspects of this Framework for a program in which risk assessment plays a role in informing regulatory
decisions.
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Example: Review of National Ambient Air Quality Standards
(Phases of the Framework are bolded)
EPA's current process for reviewing NAAQS has four major phases: (1) planning, (2) science assessment, (3)
risk/exposure assessment, and (4) policy assessment and rulemaking. The planning phase of the NAAQS review
process begins with a science policy workshop to identify issues and questions to frame the review. A draft
Integrated Review Plan (IRP) is prepared jointly by EPA's National Center for Environmental Assessment and EPA's
Office of Air Quality Planning and Standards (OAQPS). The draft IRP is made available for consultation with the Clean
Air Scientific Advisory Committee (CASAC) and public comment. The final IRP is prepared in consideration of CASAC
and public comments. It presents the current plan and specifies the schedule for the entire review, the process for
conducting the review and the key policy-relevant science issues that will guide the review.
The second phase of the review, science assessment, involves the preparation of an Integrated Science Assessment
(ISA), which provides a review, synthesis and evaluation of the most policy-relevant science, including key science
judgments that are important to the design and scope of exposure and risk assessments. The ISA provides a
comprehensive assessment of the current scientific literature pertaining to known and anticipated effects on public
health and welfare associated with the presence of the pollutant in the ambient air, emphasizing information that
has become available since the last air quality criteria review to reflect the current state of knowledge. The ISA forms
the scientific foundation for the NAAQS review and is intended to provide information useful in forming judgments
about the elements of the standard: air quality indicator(s), form(s), averaging time(s) and level(s).
In the third phase, risk/exposure assessment, EPA staff members prepare planning documents that consider the
extent to which newly available scientific evidence, tools and/or methodologies warrant conducting quantitative risk
and exposure assessments. If warranted, these documents outline a general plan, including scope and methods, for
conducting the assessments. When an assessment is performed, one or more drafts of each risk and exposure
assessment (REA) document undergoes CASAC and public review prior to completion of final REA(s). The REA
provides concise presentations of methods, key results, observations and related uncertainties.
The review process ends with a policy assessment and rulemaking phase. The Policy Assessment is a document that
provides a transparent analysis and conclusions prepared by OAQPS staff on the adequacy of the current standards
and potential alternatives that are appropriate to consider prior to the issuance of proposed and final rules. The
Policy Assessment integrates and interprets the information from the ISA and REA(s) to frame policy options for
consideration by the EPA Administrator. Such an evaluation of policy implications is intended to help "bridge the
gap" between the Agency's scientific assessments, presented in the ISA and REA(s), and the judgments required of
the Administrator in determining whether it is appropriate to retain or revise NAAQS. The Policy Assessment also is
intended to facilitate the CASAC's advice to the Agency and recommendations to the Administrator on the adequacy
of the existing standards or revisions that may be appropriate to consider, as provided for in the Clean Air Act (CAA).
In evaluating the adequacy of the current standards and (as appropriate) a range of alternative standards, the Policy
Assessment considers the available scientific evidence and, as available, quantitative risk-based analyses, together
with related limitations and uncertainties. The Policy Assessment focuses on the information that is most pertinent
to evaluating the basic elements of NAAQS: indicator, averaging time, form and level. One or more drafts of a Policy
Assessment are released for CASAC review and public comment prior to completion of the final Policy Assessment.
Following issuance of the final Policy Assessment and consideration of conclusions presented therein, the Agency
develops and publishes a notice of proposed rulemaking that communicates the Administrator's proposed decisions
regarding the standards review. A draft notice undergoes interagency review involving other federal agencies prior
to publication. Materials on which this decision is based, including the documents described above, are made
available to the public in the regulatory docket for the review. A public comment period, during which public
hearings generally are held, follows publication of the notice of proposed rulemaking. Taking into account comments
received on the proposed rule, EPA develops a final rule that undergoes interagency review prior to publication to
complete the rulemaking process (USEPA 2012i, National Ambient Air Quality Standards [NAAQSD.
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2. Initiation of the Risk Assessment Process
The initiation of the risk assessment process occurs within a larger decision-making process. It is
important that planning for the risk assessment includes consideration of the decisions that the assessment
is being conducted to inform. There are multiple challenges and requirements that may arise in
conducting a risk assessment. For example, an assessment conducted as part of a regulatory action may
have various legal considerations, including the statute under which it is being conducted (e.g., Clean Air
Act [CAA],1 Clean Water Act [CWA]2) and the regulatory program of which it is a part (e.g., 6-Year
Review of Drinking Water Contaminants under the Safe Drinking Water Act [SDWA],3 Pesticide
Registration Review, Risk and Technology Review program). Such legal considerations may result in the
selection of specific aspects of the assessment.
There also may be technical challenges in conducting an assessment. An assessor also may be faced with
a lack of toxicity data for specific chemicals or routes of exposure. Information on sensitive populations
may be unavailable. Information on the likelihood or timing of combined exposures to multiple chemicals
may be difficult to obtain or estimate. Other challenges or considerations may be related to resources,
such as the need for access to specific expertise (e.g., modeling). Time constraints associated with
decision making and funding—or lack thereof—also may be an issue and should be noted in the analysis
plan.
2.1 Planning and Scoping
Planning and scoping is an important first step to ensure that each risk assessment has a clear purpose and
well-defined vision. It is critical to producing a sound risk assessment that serves its intended purpose.
Decisions made at this stage of the process will have significant implications for later stages (NRC 2009;
PCCRARM 1997a, 1997b; USEPA 1997a, 1998a, 2000d, 2002d, 2003b, 2006c). Planning and scoping is
also an element of EPA's data quality objectives process. For example, EPA's guidance related to the
2001 Data Quality Act (Section 515 of the Consolidated Appropriations Act4) emphasizes the important
role of systematic planning and attention to data quality objectives (USEPA 2006c). Text Box 2-1
provides a list of EPA references on planning and scoping. This phase may involve a team of technical
Text Box 2-1. EPA References on Planning and Scoping
• Guidance on Cumulative Risk Assessment. Part 1. Planning and Scoping (USEPA 1997a)
• Guidelines for Ecological Risk Assessment (USEPA 1998a)
• Risk Characterization: Science Policy Council Handbook (USEPA 2000d)
• Lessons Learned on Planning and Scoping for Environmental Risk Assessments (USEPA 2002a)
• Framework for Cumulative Risk Assessment (USEPA 2003b)
• Human Health Risk Assessment: Inhalation (USEPA 2004c)
• Guidance on Systematic Planning Using the Data Quality Objectives Process (USEPA 2006c)
1 Clean Air Act of 1963, 42 U.S.C. § 7401 et seq.
2 Clean Water Act of 1972, 33 U.S.C. § 1251 et seq.
3 Safe Drinking Water Act, 42 U.S.C. § 300f et seq.
4 Consolidated Appropriations Act, Pub. L. No. 106-554, 114 Stat. 2763 (2001).
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experts, such as toxicologists, environmental chemists, economists and engineers, as well as risk assessors
and risk managers. In some cases, other subject matter experts may include attorneys and community
outreach specialists. It also may be informed by external scientific or stakeholder input. Questions
addressed in the planning and scoping step (derived from USEPA 1997a), are as follows:
• What are the overall purposes and general scope of the risk assessment? Are there legal
limitations or other legal considerations? If so, what are they?
• What risk assessment products (quantitative and qualitative) are needed by management for
informed decision making? What is needed for other analyses (e.g., economic analysis)?
• What resources are required, available or pending? Resources could include data or models,
funding, personnel, expertise and/or coordination with other organizations.
• Who will be involved in conducting the risk assessment, and what are their roles?
• What schedule will be followed? This will include provision for timely input to the decision-
making process, as well as, timely and adequate internal and independent external peer review,
where appropriate.
In general, planning and scoping provides the opportunity for the risk manager(s), risk assessor(s) and
others interested in the process to consider the context in which the risk assessment is being conducted
and the purpose(s) for which the results will be used. The risk assessment team, in collaboration with the
risk managers, also defines what is expected to be covered, considering limitations or constraints
(e.g., tools, resources, timing). In this stage, risk assessors and risk managers discuss the risk management
options to be considered along with any aspects of the risk assessment design for which there are policy
implications.
Planning and scoping results in a common understanding of the boundaries for the risk assessment and
the process for how it will be conducted. This step also recognizes the potential for the analysis plan to
involve qualitative, as well as quantitative aspects. Selected examples of planning and scoping
information are summarized in Text Box 2-2.
EPA and external advisors have repeatedly recognized that an important part of ensuring the usefulness of
each risk assessment is the dialogue between the risk manager and the risk assessment team on the nature
of the decision to be informed by the risk assessment (NRC 2009; PCCRARM 1997a and b; USEPA
1997a, 1998a, 2000d, 2002d, 2003b). This dialogue may include discussion of many topics, for example:
• Basis for the risk assessment (e.g., legal and regulatory requirements, public concern, scientific
findings).
• How the information will be used (e.g., risk communication, economic analysis)
• Risk management options.
• Applicable EPA policies and Presidential Executive Orders.
• Overarching considerations (e.g., EJ, children's environmental health, cumulative risk
assessment, sustainability).
• Current knowledge.
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• Level of effort (e.g., resources).
• Plans for communication to risk managers, stakeholders and others.
Text Box 2-2. Examples of Risk Assessment Planning and Scoping at EPA
• In EPA's review of pesticide registrations, planning and scoping occurs for a series of risk assessments
that are designed to address a common overarching regulatory purpose, although focused on different
pesticides (USEPA 2004d, Registration Review Update).
• In the planning phase for reviews of National Ambient Air Quality Standards, an Integrated Review Plan
is developed that describes all phases of the review, including the risk/exposure assessment.
Additionally, a Risk and Exposure Assessment planning document is developed as the first step in the
REA phase (e.g., planning documents for the particulate matter NAAQS review [USEPA 2011k,
Particulate Matter Standards—Documents From Current Review—Planning Documents]).
• In EPA's residual risk review of National Emissions Standards for Hazardous Air Pollutants, the planning
and scoping step encompasses a set of emissions source categories for which risk assessments are of
generally similar scope and basic design, while differing in specific aspects of the sources and the
chemicals emitted. A general project and methodology is described at the Risk and Technology Review
program Web page (USEPA 2011o).
• Planning and scoping are key components of human health risk assessments conducted under the
Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA, also known
as Superfund; 42 U.S.C. §9601 et seq.), and are discussed in the following guidance documents:
> Guidance for Conducting Remedial Investigations and Feasibility Studies Under CERCLA (USEPA
1988).
> Human Health: Planning and Scoping (USEPA 2011h).
> Ecological: Planning and Scoping (USEPA 2011c).
Figure 2-1 provides detail on the key elements of planning and scoping in the Framework, each of which
is discussed in further detail in subsequent sections. Text Box 2-3 provides context on risk assessment
from the Silver Book (NRC 2009). The next six subsections address the key aspects of the planning and
scoping phase:
• Section 2.1.1 focuses on the need to consider the purpose and context for the risk assessment,
noting that different processes may be employed depending on this context and purpose.
• Section 2.1.2 describes important overarching considerations that may affect risk management
options.
• Section 2.1.3 discusses consideration of responsibilities, resources and timelines.
• Section 2.1.4 addresses planning for scientific or other reviews.
• Section 2.1.5 details public, stakeholder and community involvement.
• Section 2.1.6 discusses consideration of previous assessments.
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Key Considerations
for Planning and Scoping
What decision is to be informed by risk assessment, when
is the decision anticipated, and what are the risk
management options?
What legal/statutory requirements affect risk management
options and level/type of analysis?
What other considerations (e.g., environmental justice, life
stage, cumulative risk, sustainability) or countervailing
risks may influence risk management options and
analyses?
What assessments (e.g., risk, economic) are needed to
address decision-making needs?
What expertise, resources and timelines are available to
conduct the assessments(s)?
Figure 2-1. Framework for Human Health Risk Assessment to Inform Decision Making: Key
Considerations for Planning and Scoping
Text Box 2-3. The Silver Book Statements on Risk Assessment and Decision Context
• "Risk assessments should not be conducted unless it is clear that they are designed to answer
specific questions, and that the level of technical detail and uncertainty and variability analysis is
appropriate to the decision context" (NRC 2009, 247).
• "The technical framework for risk assessment presented in the Red Book should remain intact but
should be embedded in a broader framework in which risk assessment is used principally to help to
discriminate among risk-management options" (NRC 2009, 256).
2.1.1 Context, Purpose and Scope
Each human health risk assessment is conducted within a particular context specific to regulatory or
programmatic needs and responsive to environmental events or public health concerns. Many EPA risk
assessments are performed to inform specific decisions that guide the development of regulatory actions.
For example, risk assessments commonly inform federal regulatory actions concerning ambient air
quality standards; the provision of public drinking water; and the registration of pesticides for U.S.
distribution, sale and use. In other cases, such as a response to a newly identified environmental concern,
careful consideration of the purpose and associated objectives, including decisions being informed is
essential to the development of a risk assessment that provides information needed. It is important that
planning for the risk assessment clearly states the decision to be informed and the boundaries for the
assessment, detailing what will not be addressed in the risk assessment.
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For risk assessments performed within a specific regulatory context, statutory language or legislative
history may impose requirements or restrictions that will need to be considered in scoping the risk
assessment; for example, the Food Quality Protection Act (FQPA)5 includes directives on assessing risk
that apply to pesticides in foods and water. In some regulatory contexts, a risk assessment (or some
quantitative aspect of it) may be a key input into benefit-cost analyses of alternative regulatory options;
these analyses may impose different or additional requirements than is the case in other regulatory
contexts, where costs and quantified benefits are not considered.
As emphasized earlier, risk assessments are most useful when they are designed to answer specific
questions, with a level of technical evaluation that is appropriate for the decision context ("fit for
purpose"). In situations that are perceived to be particularly complex, clear articulation of the overall
purpose or end use of an assessment may involve extensive interaction among the assessment team and
the range of stakeholders to establish a common understanding. Such consideration recognizes that the
utility of a risk assessment is a function of how well it informs the decision for which it is designed.
The planning and scoping phase includes explicit consideration of the nature of the assessment question
or the hypothesis that the assessment seeks to address, with the goal of developing or clarifying the broad
dimensions and elements of the assessment. In this step, the assessment and management objectives and
purpose are defined clearly.
The particular purpose for which an assessment will be used and its scale (e.g., site-specific vs. regional
or national) often will have significant implications for the scope, level of detail and approach of an
assessment. A complete risk assessment may not be necessary when an exposure assessment or effects
estimation is all that is required to inform a decision. The risk assessment scope can be defined, in a
general sense, by the scale of the environmental problem being considered (e.g., local scale vs. national
scale) and the regulatory context. One example is a risk assessment intended to investigate the health risks
associated with a hazardous waste site that falls under the Comprehensive Environmental Response,
Compensation, and Liability Act (CERCLA).6 The scope for this type of risk assessment may be site-
specific, considering multiple receptors, multiple chemicals and multiple pathways of exposure for on-
and off-site receptors (depending on the nature of the site). This will differ from the scope for a risk
assessment on uses or exposure to a particular chemical, which is conducted to inform a national
regulation (such as a National Primary Drinking Water Rule).
Scoping provides a foundation for the problem formulation step. Scope, in this context, refers to the
proposed boundaries of the assessment (e.g., what chemicalfs] and exposure pathwayfs] will be
addressed). The scope is considered with other factors (e.g., context, purpose, participants, timeline,
resources) in developing the detailed plan for the assessment. At this step, most EPA assessment projects
focus on identifying and considering information available in these areas:
• Sources of contaminants.
• Stressors, associated effects, susceptible populations and life stages.
• Exposure routes and pathways.
5 Food Quality Protection Act of 1996, Pub. L. No. 104-170, 110 Stat. 1489 (1996).
6 Comprehensive Environmental Response, Compensation, and Liability Act of 1980, 42 U.S.C. §9601 et seq.
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• Stakeholder concerns.
• Any spatial or temporal aspects of exposure (USEPA 1997a, 200 Ic).
Consideration of these elements during planning and scoping helps to identify missing information and
potential assessment endpoints for the analysis plan. It also provides the basis for an early
conceptualization of the problem being assessed and the approaches for assessment. The scoping
discussion also should include regulatory context and any additional management or programmatic needs
or limitations. Information considered and decisions made during the scoping step also shape the
development of the conceptual model and the analysis plan (as described in Section 2.2).
At this stage, consideration of the needs of related, quantitative analyses (e.g., benefit-cost analysis or
environmental impacts of associated policy decisions) can contribute to improved efficiency. Text Box
2-4 provides examples of important considerations for an economic benefits analysis. A consideration of
related analyses at this stage also will help to ensure the compatibility of quantitative analyses considered
in the decision-making step described in Section 5.
In the planning and scoping phase, it also is important to identify separate processes by which
components of the risk assessment may be completed (e.g., development of dose-response assessment
within Integrated Risk Information System [IRIS]), as well as larger processes (e.g., rulemaking that
occurs within the Agency's Action Development Process) (USEPA 201 Ib). Furthermore, individual
regulatory programs (e.g., Superfund) have a formalized process detailing the risk assessment process.
These processes may have specific information requirements and timelines, and these may impose
additional requirements on the risk assessment process. Depending on the nature of the risk assessment
and the importance of the decisions, it may be essential to identify how the risk assessment team will
interact with other program offices affected by the ultimate decision. For example, regulatory risk
assessments focused on important multimedia pollutants with multiple sources for human exposure (e.g.,
lead) generally will involve multiple programs, particularly in cases where EPA may address the pollutant
under multiple regulatory programs. In some cases, there also may be interactions with other government
agencies, as well as coordination with state and tribal nations.
2.1.2 Overarching Considerations
The purpose and scope of the assessment also should be considered in the context of broad EPA priorities.
The extent to which these affect the design or methods for any given risk assessment will depend on many
factors, including the risk assessment purpose, scope and regulatory context. These overarching
considerations, such as those described in the following subsections, may not affect all analyses; early
consideration and discussion of these issues, however, can enhance the utility of the risk assessment.
Thus, the potential for inclusion of analyses involving these topics is an important consideration in the
planning stage for an assessment, as is the consideration of corresponding methodology. Analyses
focused on such considerations may benefit from involvement of specific experts and the EPA offices that
focus on them.
Overarching considerations also are often the focus for policy considerations. Accordingly, they
alternatively or additionally may receive particular attention in the risk management arena, depending on
the decision context. Such attention may be independent of a risk assessment. Several current examples of
EPA priorities that may be important overarching considerations in human health risk assessments are
described in the following subsections.
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Text Box 2-4. Risk Assessment for Economic Benefits Analysis
Although risk assessment and economic analysis often are considered very separate exercises, estimates
from or inputs to risk assessment sometimes may serve as inputs into the models that economists use
for the benefits side of a benefit-cost analysis. Therefore, when benefit-cost analysis is needed to inform
decisions, early communication between the risk assessment and benefits analysis teams, including
consideration of the needs of both analyses, can contribute to efficiencies in the assessment designs.
Listed below are some important considerations for benefits analyses that depending on the context for
the health risk assessment may or may not otherwise be relevant.
• Economically meaningful human health endpoints: These are endpoints that can be linked to human
well-being and for which the risks can be monetized using economic valuation methods. This may
include additional outcomes or different outcomes than otherwise would be modeled in a health risk
assessment. For example, benefits analysis incorporates changes in all health effects across the
relevant range of exposure, not just the most sensitive. The endpoints are characterized using metrics
for which there are economic valuation methods.
• Changes in the probabilities of human health outcomes: Although this may be part of some health
risk assessments, many health risk assessments alternatively utilize measures, such as reference doses
and reference concentrations, which do not inform estimates of health outcome probabilities (as
noted in Chapter 5 of the Silver Book [NRC 2009]).
• Expected or central estimates of risk for a given population: Depending on the context for the risk
assessment, it may rely instead on more conservative or upper-bound estimates of risk. The Science
Advisory Board's (SAB) Advisory on EPA's Superfund Benefits Analysis highlights the issue of using
conservative risk assessments in benefits analysis (Morgan and Freeman 2006), recognizing that
conservative estimates of risk might differ significantly from central tendency and might lead to biased
estimates of benefits.
• A "cessation lag" to account for any time lag between reductions in exposure and health benefits:
The benefits analysis must consider the time profile of changes in exposures and resulting changes in
risks. This concept is more fully described in the Arsenic Rule Benefits Analysis: An SAB Review (USEPA
2001a).
• A full probabilistic distribution of risk estimates: Not only does this possibly contribute to a better
understanding of potential outcomes, but also it enables economists to incorporate risk assessment
uncertainty into a broader analysis of uncertainty. Formal probabilistic assessment of uncertainty in
benefits and costs is required by the Office of Management and Budget (OMB) for some regulations.
Early communication between the teams, with consideration of their needs and objectives, can help to
improve the analyses performed for both purposes. For example, risk assessment estimates may be
informative for benefit-cost analysis and also can contribute information and insights on how behavioral
changes may affect exposure, and thus, change the risk. Additional information on economic analysis can
be found in Guidelines for Preparing Economic Analyses (USEPA 2010a).
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2.1.2.1 Children's Environmental Health Protection
Protecting children's health from environmental pollutants long has been part of EPA's mission. Children
may have greater exposures to some environmental contaminants than adults; for example through
increased consumption per body weight of certain foods. Furthermore, their behavior patterns, such as
playing close to the ground and hand-to-mouth activity, also may increase their exposure to contaminants.
In addition, they may be more vulnerable to environmental hazards because their organ systems still are
developing and undergoing processes that are specifically sensitive to certain chemicals, leading to
potential windows of susceptibility. Children also may differ from adults in their metabolism,
detoxification and excretion of some chemicals. Accordingly, EPA's risk assessments routinely consider
the potential susceptibility of children to ensure that decisions will provide protection of children's health.
EPA's Policy on Evaluating Health Risks to Children is intended to ensure that environmental health
risks to children are considered explicitly and consistently as part of risk assessments generated during the
Agency's decision-making process, including the setting of standards to protect public health and the
environment (USEPA 1995b). The 1995 policy was reaffirmed by Administrator McCarthy in October
2013 (USEPA 2013c) Presidential Executive Order 13045. Protection of Children from Environmental
Health Risks and Safety Risks, also requires all federal agencies to assign a high priority to addressing
health and safety risks to children, coordinate research priorities on children's environmental health, and
ensure that their standards take into account special risks to children (Clinton 1997).
Additionally, some public health statutes provide for the protection of sensitive populations, population
groups or subpopulations. For example, the 1996 SDWA amendments use the term "subpopulation" to
describe groups with unique attributes, including those defined by age or life stage. EPA recognizes that
these terms, as used in such statutes, describe groups of people with common attributes, including life
stage, which may make them more sensitive or susceptible to the stressor(s) being assessed. EPA
emphasizes the importance of recognizing that childhood encompasses a sequence of life stages through
which all members of a population pass. A life-stage approach to risk assessment considers the relevant
periods of exposure in developmental life stages and subsequent outcomes that may not be expressed until
later life stages (USEPA 2005b). Accordingly, using a variety of approaches, EPA's risk assessments
consider and take into account the potential for differences across life stages that may affect risk. See the
"life stages" entry included in USEPA 2012g. Where a statute might use the term "subpopulation," EPA
recognizes this as including consideration of age groups or life stages. Text Box 2-5 highlights several
guidance documents available to assist in considering children's environmental health.
Text Box 2-5. Key EPA Children's Health Guidance Documents
• Policy on Evaluating Health Risks to Children (USEPA 1995b and 2013c).
• Supplemental Guidance for Assessing Susceptibility from Early-Life Exposure to Carcinogens
(USEPA 2005e).
• Guidance on Selecting Age Groups for Monitoring and Assessing Childhood Exposures to
Environmental Contaminants (USEPA 2005a).
• A Framework for Assessing Health Risk of Environmental Exposures to Children (USEPA 2006b).
• Guide to Considering Children's Health When Developing EPA Actions: Implementing Executive
Order 13045 and EPA's Policy on Evaluating Health Risks to Children (USEPA 2006d).
• Exposure Factors Handbook (USEPA 2011f; includes specific sections with child-specific factors).
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2.1.2.2 Cumulative Risk Assessment
In EPA's 2003 Framework for Cumulative Risk Assessment (USEPA 2003b), cumulative risk is defined
as "the combined risks from aggregate exposures to multiple agents or stressors". Several key points are
made with this definition. First, cumulative risk explicitly involves multiple agents or stressors. Second,
the "agents or stressors" are not limited to chemicals; in some cases, stressors also may include biological
or physical agents. In addition, stressors may include activities that directly or indirectly alter or cause the
loss of a necessity or those that adversely affect health or increase susceptibility to other stressors. Third,
this definition specifies that the risks from multiple agents or stressors are combined. This does not
necessarily mean that the risks are added; "combining" may mean that some analysis is conducted to
determine how the risks from the various agents or stressors interact. Cumulative risk assessment includes
qualitative evaluation and possible quantification of the combined risks to health or the environment from
multiple agents or stressors.
The specific characteristics of a given cumulative risk assessment will vary depending on scientific and
regulatory needs. The Office of Pesticide Programs' cumulative assessments under the FQPA and those
used by the Office of Water for pesticides are conducted pursuant to the Guidance on Cumulative Risk
Assessment of Pesticide Chemicals That Have a Common Mechanism ofToxicity, which applies only to
chemicals that share a common mechanism of action (USEPA 2002c). Other environmental statutes, such
as the National Environmental Policy Act7 and CAA (e.g., hazardous air pollutant aspects), also include
various requirements for cumulative and multiple pollutant analyses. Text Box 2-6 lists resources that
describe approaches to cumulative risk assessment.
2.1.2.3 Environmental Justice
EPA defines environmental justice as "the fair treatment and meaningful involvement of all people
regardless of race, color, national origin or income with respect to the development, implementation and
enforcement of environmental laws, regulations and policies" (USEPA 2012b). As described in
Presidential Executive Order 12898:
To the greatest extent practicable and permitted by law, and consistent with the principles
set forth in the report on the National Performance Review, each Federal agency shall
make achieving environmental justice part of its mission by identifying and addressing,
as appropriate, disproportionately high and adverse human health or environmental
effects of its programs, policies, and activities on minority populations and low-income
populations in the United States and its territories and possessions, the District of
Columbia, the Commonwealth of Puerto Rico, and the Commonwealth of the Mariana
Islands (Clinton 1994).
Incorporating environmental justice considerations into EPA process for developing rules and regulations
is a priority (USEPA 201 Ob). In the risk assessment process, the potential for disproportionate
environmental and public health impacts to minority or low-income populations (e.g., inequities in
environmental health and conditions) is an important consideration during the problem formulations and
planning and scooping stages. EPA's Plan EJ 2014, the Agency outlines a strategy to understand and
solve environmental and health inequalities among overburdened populations and communities that uses
integrated, transdisciplinary and community-based participatory research approaches to address
cumulative impacts and equity in environmental health and environmental conditions (USEPA 2011m).
7 National Environmental Policy Act, 42 U.S.C. § 4321 et seq.
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As part of EPA's Plan EJ 2014, Technical Guidance for Assessing Environmental Justice in Regulatory
Analysis is being developed (EPA 2013b). Furthermore, cumulative risk assessment may have a role in
EJ analyses.
Text Box 2-6. Approaches to Cumulative Risk Assessment
Cumulative risk assessments may differ in design and associated results. Examples of cumulative risk
assessment at EPA include:
• The Office of Pesticide Programs' evaluation of cumulative risk according to the FQPA (USEPA
2012d).
• Guidance for Performing Aggregate Exposure and Risk Assessments (USEPA 1999a).
• General Principles for Performing Aggregate Exposure and Risk Assessments (USEPA 2001c).
• Guidance on Cumulative Risk Assessment of Pesticide Chemicals That Have a Common Mechanism of
Toxicitv (USEPA 2002c).
• The Office of Air and Radiation's assessment of hazardous air pollutant risks remaining after
implementation of technology-based emissions standards (USEPA 2011o, Risk and Technology
Review).
• The Office of Environmental Justice's Ensuring Risk Reduction in Communities With Multiple
Stressors: Environmental Justice and Cumulative Risks/Impacts (USEPA 2004a).
• Region 3's Multi-criteria Integrated Resource Assessment (MIRA) (USEPA 2011J).
Additionally, two NRC publications, Science and Decisions: Advancing Risk Assessment (NRC 2009)
and Phthalates and Cumulative Risk Assessment: The Tasks Ahead (NRC 2008), describe
approaches to consider in the practice of cumulative risk assessment. For example, Phthalates and
Cumulative Risk Assessment discusses the advantages of focusing on physiologic consequences
rather than structural or mechanistic similarity in conducting cumulative risk assessment. This
approach is more directly relevant to relating chemical exposures to human diseases and
disorders. Science and Decisions discusses the importance of considering nonchemical stressors
and background processes in cumulative risk assessment.
Information on approaches for consideration of EJ in Agency actions is available at EPA's EJ Policy &
Guidance Web page (USEPA 2012J) and in the Interim Guidance on Considering Environmental Justice
During the Development of an Action (USEPA 201 Ob). For example, EPA priorities in this area include
development of technical guidance and implementation plans. EPA has established the American Indian
Environmental Office (AIEO) to coordinate the Agency-wide effort to strengthen public health and
environmental protection in tribal lands, with a special emphasis on helping tribes administer their own
environmental programs. Information on the AIEO and related activities is available at the American
Indian Environmental Office Portal website (USEPA 2012a).
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2.1.2.4 Sustainability
Sustainability is defined in Executive Order 13514s as a process "to create and maintain conditions, under
which humans and nature can exist in productive harmony, that permit fulfilling the social, economic, and
other requirements of present and future generations." Sustainability is based on the simple principle that
everything humans need for survival and well-being depends, either directly or indirectly, on the natural
environment. The concept entails consideration of how we meet society's needs of today while ensuring
future generations can do the same. Sustainability is important to ensure that humans have—and will
continue to have—the water, materials and resources to protect human health and the environment. EPA's
efforts in the area of Sustainability practices include approaches such as labeling green products,
promoting green chemistry and engineering, and managing materials rather than creating waste. Text Box
2-7 includes references related to Sustainability.
Text Box 2-7. Resources on Sustainability and Life Cycle Assessment
• Office of Research and Development's (ORD) Sustainabilitv program (USEPA 2011t).
• National Risk Management Research Laboratory's (ORD) Life Cycle Assessment Web page (USEPA
Sustainabilitv and the U.S. EPA (NRC 2011).
If the planning and scoping phase identifies this as important to decision making, analyses accompanying
the risk assessment may provide the risk manager with information relevant to the Sustainability of
proposed risk management options. Such analyses may consider the full life cycle impacts of the agent,
stressor or remedy under review, as well as the potential unintended consequences of decisions.
Sustainabilitv and the U.S. EPA (NRC 2011) contains a detailed discussion of how a framework for
Sustainability relates to risk assessment and risk management.
2.1.3 Responsibilities, Resources and Timeline
A team approach to planning risk assessments is essential (NRC 2009, USEPA 2002d). The planning and
scoping process includes the initial allocation of responsibilities for members of the assessment team as
well as clarification of the interactions of the risk assessment team with the risk managers and
stakeholders. Transparency in planning and scoping can improve the understanding of the public and
regulated community with regard to the basis for the risk assessment design, including options,
limitations and approaches considered but not selected for the assessment. For some risk assessments
there are precedents, templates, or guidance documents that can be used to facilitate the planning and
scoping process as well as the communication of the plan (e.g., Process for Conducting Probabilistic Risk
Assessment in the Risk Assessment Guidance for Superfund [USEPA 2001d]).
The composition of the risk assessment team is dependent on the nature of the problem. At a minimum,
the team comprises individuals with the necessary scientific expertise. Depending on the level of
complexity of a risk assessment and the context for its conduct, a multidisciplinary approach is often
necessary. Some disciplines that may be pertinent include: toxicology; epidemiology; exposure science;
hydrogeology; fate and transport modeling (e.g., indoor and outdoor air, surface and drinking water);
computer science (including geographic information systems [GIS], data management); chemistry;
' Exec. Order 13514, 74 Fed. Reg. 52126 (October 8, 2009).
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biology; various engineering fields (e.g., chemical, environmental, mechanical, industrial, civil);
economics; sociology; statistics and communications. Lawyers and policy makers also may be called on
to contribute to risk assessment planning and scoping. Depending on the context and process in which the
risk assessment is conducted, specific expertise may be needed to develop particular tools, data or
analyses. Coordination with other federal, tribal and state agencies and with other stakeholders also may
be appropriate, depending on the type of assessment being conducted.
Different members of the assessment team will provide expertise for specific elements of the planning
and scoping discussion. For example, the risk manager may identify the regulatory needs of the
assessment, timeframes and quantity of funds available for the assessment. The site assessment team
would focus on evaluation of the current and future concentrations of the contaminants in various media.
An exposure assessor may help the team consider the nature, fate and transport of the contaminants;
sources, routes, timing and pathways; the extent of contamination; and the availability of data, either at
the national or local level. Other specialists may provide information on topics such as funding levels and
sources, contractor requirements and relevant interagency agreements.
It also is important to describe or establish the resources in terms of staffing, budget and time for the
assessment as part of the planning and scoping phase. These aspects need to be considered in the
development of the analysis plan, as they can affect the scope and approach for the assessment. The
timeline for the assessment is developed, taking into account critical legal and management timeframes,
as well as any need to meet external deadlines or coordinate with the schedules of other organizations
(including critical stakeholders or external review bodies). When there is extensive stakeholder
involvement, it is especially important that this be reflected in the budget and schedule and understood by
all participants (USEPA 2003d). Data collection activities involving human data must adhere to EPA's
regulations and policies on the protection of human subjects. See EPA's Office of the Science Advisor
Web page on Ethics, Regulations, and Policies (USEPA 2012f).
2.1.4 Opportunities for Scientific Peer Review or Other Review Steps
The need for and timing of scientific peer review or other reviews is a consideration in planning and
scoping activities. Various stages in the assessment process can provide opportunities for scientific
review and stakeholder involvement. For example, completion of a draft conceptual model and analysis
plan or an iteration of the risk assessment may be useful points for focused discussion between the risk
assessor and risk manager and/or for scientific review and public, stakeholder and community
involvement. Additionally, internal review and checks for quality of the assessment are important. Other
types of review also may be necessary, depending on the scope and purpose of the assessment. For
example, an independent external peer review may be an important element. Also some assessments (e.g.,
those developed for NAAQS, pesticide registration decisions or through the IRIS program) include a
public review step that often is coincident with the scientific review step.
Scientific peer review is a process used to provide a critical evaluation of a specific EPA scientific and/or
technical work product. EPA has published a Peer Review Handbook that describes the types and extent
of reviews as well as the documentation needed to fulfill EPA requirements (USEPA 2006e). It should be
noted that a new edition of the Peer Review Handbook is expected to be released by the Agency in 2014.
The Peer Review Handbook incorporates the guidance provided in the Office of Management and
Budget's (OMB) Final Information Quality Bulletin for Peer Review (OMB 2004). The Peer Review
Handbook makes distinctions among peer involvement, peer consultation and peer review.
Peer review is a documented process conducted to ensure that activities are technically supportable,
competently performed, properly documented and consistent with established quality criteria. Peer review
may be internal or external to the Agency consistent with the classification or use of the document. It is
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conducted by qualified individuals or organizations that are independent of those who performed the work
and who are collectively equivalent in technical expertise (i.e., peers). Peer review usually involves a one-
time or limited number of interactions by the independent peer reviewers with the authors of the work
product. An assessment also may benefit from other types of input (such as peer involvement and public
comment) that differ from peer review (USEPA 2006e). Planning and scoping for the assessment includes
discussion of whether and what types of reviews will be included in light of the context and constraints
for the assessment, including schedule and resources.
As part of planning and scoping, risk assessors and/or risk managers should consider the need for and
timing of peer review (USEPA 2006e).The team will need to determine whether any of the analyses or
products of the assessment may need peer review and if so, what level of peer review may be required and
at what stage in the process. Evaluating peer review needs early will help ensure that adequate resources
are allocated. In addition, peer review considerations are an integral part of setting assessment milestones
and schedules. EPA's Peer Review Handbook (USEPA 2006e) provides detailed guidance for
determining when peer review is required and how to plan and implement a peer review. The principle
underlying the Agency's peer review policy is that "all influential scientific and technical work products
used in decision making will be peer reviewed" (USEPA 2006e, 30). The Peer Review Handbook stresses
transparency in all parts of the peer review process, and EPA supports systems (e.g., the EPA Science
Inventory, USEPA 2012e) for documentation and disclosure of peer review plans and products.
2.1.5 Public, Stakeholder and Community Involvement
The planning and scoping phase also includes
consideration of opportunities for
involvement and/or review by the public and
specific stakeholders. EPA's public
involvement policy (USEPA 2003d), a
framework for implementing it (USEPA
2003c), and other references are available at
EPA's Public Involvement Policy and Related
Documents Web page (USEPA 2012m);
public, stakeholder and community
involvement are described at greater length in
Section 3 of this Framework document.
Depending on the context for the risk
assessment and overarching process
governing its conduct, risk assessment
products also may be made available for
public comment, as required or practical
under specific regulatory programs. Public, ' Extemal Stakeholders include the public,
Text Box 2-8. Definitions of "Public,"
"Stakeholder" and "Community"
Public Involvement refers to the full range of
activities that EPA uses to engage the American
people in the Agency's decision-making process
(USEPA 2011a).
Stakeholders are individuals or representatives
from organizations or interest groups that have
a strong interest in the Agency's work and
policies (USEPA 2011a).
• Internal Stakeholders include EPA program
offices or regions (USEPA 2007a).
affected industries, public health or
environmental organizations and other
government agencies (USEPA 2007a).
Community Involvement is the process of
engaging in dialogue and collaboration with
community members (USEPA 2011q).
by
be
stakeholder and community involvement may
initiated through a formal notice of
availability of the risk assessment and
opportunity for public comment, and/or there
may be a formal period for public comment
associated with the regulatory decision that
was informed by the risk assessment. Public
commenters generally include a wide range of
interested parties, both experts and non-experts, but they are not expected to provide the kind of
independent, expert information and in-depth analyses obtained from the peer review process (USEPA
2006e). The involvement of the public, stakeholders and communities (defined in Text Box 2-8) can help
EPA RISK ASSESSMENT FORUM
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ensure that the assessment process is transparent and that risk-informed decision making proceeds
effectively, efficiently and credibly (NRC 2009). Such involvement also may facilitate development of
sustainable solutions (NRC 2011). EPA activities may need involvement of the state and tribal
environmental agencies. In Agency activities with international implications, there may be involvement of
other governments or international government organizations.
The roles for stakeholders are considered during the planning and scoping phase. Deciding how and when
to involve stakeholders will depend on the context for and nature of an assessment. Depending on the
project, a list of critical points for stakeholder input—such as discussions of purpose, scope and
approach— may be defined (USEPA 2003a).
Stakeholders may be from programs within EPA; other federal agencies; state, local and tribal
governments; regulated industries; the regulated community; community members affected by an
environmental release; and members of the general public. The Presidential/Congressional Commission
on Risk Assessment and Risk Management (PCCRARM) reports (PCCRARM 1997a and b) suggest
using the following questions to identify potential stakeholders:
• Who might be affected by the assessment?
• Who has information and expertise that might be helpful?
• Who has been involved in similar risk situations before?
• Who has expressed interest in being involved in similar decisions before?
• Who might reasonably think that they should be included?
Assessments that require short-term, low-budget efforts or preliminary screening assessments may not
have the scope, time or resources for extensive public, stakeholder and community involvement.
Community involvement, however, is important to many community-based or site-specific assessments;
for a highly controversial, location-specific assessment, early and extensive public, stakeholder and/or
community involvement can be essential to the quality and usefulness of the risk assessment and the
applicability of the risk management options informed by the assessment.
The Framework for Implementing EPA 's Public Involvement Policy (USEPA 2003c) provides general
guidance for scoping a public involvement process and identifies the following seven basic steps for
conducting effective public involvement:
1. Plan and budget for public involvement activities.
2. Identify the interested and affected public.
3. Consider providing technical or financial assistance to the public to facilitate involvement.
4. Provide information and outreach to the public.
5. Conduct public consultation and involvement activities.
6. Review and use input, and provide feedback to the public.
7. Evaluate public involvement activities.
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2.1.6 Past Experiences and Assessments
Review of past experiences and assessments is an important part of planning and scoping because it can
contribute to the development of a more robust analysis plan, as well as improve the usefulness and focus
of the assessment. For example, in the review of existing national standards, consideration of previous
assessments, as well as the aspects of those assessments that might cause risk estimates to change because
of newly available information or tools, can inform the planning and scoping stage for a new risk
assessment and predictions of what new insights the assessment might be able to provide. Furthermore,
such explicit consideration of the potential value added of a new assessment may improve the efficiency
of associated risk-based decision making. Valuable lessons also can be learned and information can be
obtained from assessments performed for conceptually similar situations (e.g., previous analyses for a
similar industry, analog or chemical).
Assessments by other agencies (federal, state, tribal and international) also may be useful to study.
Understanding past risk assessment decisions and associated risk assumptions within a specific regulatory
program is important to assuring the usefulness of a given risk assessment in the decision-making
process. Furthermore, notable differences between the current assessment and previous assessments
(e.g., new health effects evidence or technical approaches) may be important to describe in the analysis
plan for the current assessment, as well as in the risk characterization.
2.2 Problem Formulation
Problem formulation is the part of the Framework that systematically identifies the major factors to be
considered in the assessment. It draws from the regulatory, decision-making and policy context of the
assessment and informs the assessment's technical approach. EPA's Guidelines on Ecological Risk
Assessment defines problem formulation as the analytical phase of the assessment in which "the purpose
for the assessment is articulated, the problem is defined, and a plan for analyzing and characterizing risk
is determined" (USEPA 1998a, 2). Problem formulation also should define clearly the dimensions of the
risk assessment, including the basis (or necessity) of the risk assessment.
Problem formulation has been detailed clearly in ecological risk assessment (USEPA 1998a), and
described in Agency references that also address human health risk assessment (US USEPA 1997a, EPA
2002d, and USEPA 2003b). The formalization of problem formulation in both categories of risk
assessment is a significant step in harmonizing human health and ecological risk assessment processes
across the Agency's programs and key in ensuring that risk assessments are "fit for purpose" by
addressing the decision-making needs of the Agency.
An important outcome of the problem formulation step is a conceptual model. Through the use of a
written description and visual representation, it identifies the stressor(s), the exposed population(s) and
the endpoint(s) that will be addressed in the risk assessment, as well as the relationships among them.
Assessment endpoints, as well as the exposed populations, are more limited in variety in human health
risk assessment than is the case in ecological risk assessment (USEPA 1998a). Many Agency regulatory
programs have established specific human health risk assessment endpoints that often are linked to
statutory requirements. For example, risk assessments for the Superfund and Hazardous Air Pollutant
programs, among others, may include the assessment endpoint of estimating the lifetime individual cancer
risk associated with the particular sources or sites assessed (Clay 1991; USEPA 1999b). Alternatively,
risk assessments performed for reviews of NAAQS often focus on population risk metrics particular to
the health effects evidence for the air pollutant being assessed. The analysis plan, which describes the
approach for the risk assessment and how it will address the Agency's needs, is developed in light of the
conceptual model, any programmatically established assessment endpoints and other planning
considerations (described in Section 2.1). Additional detailed information on the conceptual model and
EPA RISK ASSESSMENT FORUM
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analysis plan are provided in the following sections, including some of the key issues that should be
considered as they are developed. Figure 2-2 highlights the problem formulation steps within the
Framework.
Key Considerations for Problem Formulation
Conceptual Model
What are the human health risk pathways for this
problem, including the elements for each dimension
(e.g., populations and/or life stages at risk)?
What factors and endpoints need to be analyzed?
Analysis Plan
What approaches, methods and metrics will be used to
assess exposures, effects and risk, including the
associated uncertainty and variability?
What is the strategy for developing new or using existing
data? Are existing approaches adequate or are new
approaches needed?
Figure 2-2. Framework for Human Health Risk Assessment to Inform Decision Making: Key Questions
and Considerations for Problem Formulation
2.2.1 Conceptual Model
A conceptual model includes a written description and a visual representation of actual or predicted
relationships between humans (populations or population segments) and the chemicals or other stressors
to which they may be exposed. The conceptual model is a scientific or technical work product that can
include the following:
• The rationale for selecting the sources, stressors, exposure pathways, receptors, exposed
populations, endpoints or risk metrics, including effects.
• The basis for the model development.
• The scientific implications of additional data gathering.
The complexity of the conceptual model depends on the complexity of the problem. This may be related
to the number of stressors, exposure pathways or assessment endpoints; the nature of effects; and/or the
characteristics of the exposed populations or life stages. Generally, the conceptual model identifies factors
and endpoints that will be analyzed in the risk assessment. It also addresses those aspects that might not
be analyzed in the risk assessment, the recognition of which sometimes is important in the overall
decision-making process. For example, although a risk assessment for a particular stressor may focus on
exposure pathways or media relevant to the regulatory decision being faced (e.g., ingestion of drinking
EPA RISK ASSESSMENT FORUM
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water), the conceptual model also will describe the role of other pathways (e.g., consumption offish),
thus ensuring appropriate characterization of and context for the assessment results.
A conceptual model can provide documentation of decisions for future reference during risk assessment
and can be useful in characterizing and communicating the risk management decision. The conceptual
model is valuable as a risk communication tool within EPA and in the Agency's interactions with the
public.
A general conceptual model (visually represented in Figure 2-3) defines the key elements for the problem
to be assessed and shows pathways and routes of exposure between the stressors and effects (endpoints)
for human receptors. The visual representation of the conceptual model is a diagram that may include the
following types of elements:
• Source(s) of stressors of interest in the environment (e.g., releases from a leaking storage tank,
waste material poured on the ground).
• Types of stressor(s), including physical, chemical and biological stressors.
• Exposure pathways, including fate and transport processes by which stressors move from the
original point of release through the environment (e.g., a chemical in soil might penetrate down
into groundwater or might volatilize into air) and the interaction(s) through which populations or
individuals are exposed (e.g., ingestion of contaminated water, inhalation of chemicals in air,
dermal contact with contaminated soil).
• Receptors, which may be groups of individuals or populations identified by common
characteristics (e.g., the general population, local residents near the site of concern, adult workers,
recreational visitors, particular populations with unique exposures and/or susceptibilities to
stressors), including life stages (e.g., infants or women of childbearing age).
• Types of endpoints to be considered (e.g., cancer, asthma, IQ decrement, developmental effects).
• Risk metrics (e.g., cases of disease or disease incidence, hazard quotient, magnitude of effect,
margin of exposure).
Conceptual models are used to plan the risk assessment and associated data collection activities, and they
may be periodically revised as data become available. Conceptual models consist of two principal
components: (1) a set of risk hypotheses that describe predicted relationships among stressor, exposure
and health endpoints and/or responses, along with the rationale for their selection; and (2) a diagram that
illustrates the relationships presented in the risk hypotheses. Examples of conceptual models from various
EPA risk assessments are provided in Text Box 2-9 and Text Box 2-10 identifies EPA resources with
more information about conceptual models.
Figure 2-4 presents a diagram illustrating a detailed conceptual model of multiple exposure pathways and
receptors potentially affected by multiple sources of chemical stressors; this model was designed by EPA
Region 8 for the analysis of Superfund sites contaminated with polychlorinated biphenyls (PCBs)
(USEPA2012p).
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Sources
Activities that
generate/release
stressors or types
of stressor releases
Stressors
Chemical, physical
or biological
agents that cause
an effect
Exposure
Pathways/Routes
Physical processes
or interactions by
which a stressor is
brought into contact
with receptor
Receptors
Populations and/or
life stages exposed
to the stressor
Endpoints
Measure of stressor
effects or biological
systems affected
(cancer, asthma,
IQ decrement)
Risk Metrics
Measure by which
risk is quantified
(cases of disease
or disease
incidence, hazard
quotient, magnitude
of effect, margin of
exposure)
Figure 2-3. Example of a Generalized Conceptual Model With Examples of Possible Dimensions and
Linkages
Source: Adapted from USEPA 2002d, 2003b.
Text Box 2-9. Examples of Conceptual Models in EPA Risk Assessments
• Conceptual model to inform lead NAAQS risk assessment (USEPA 2007b, 2-1 to 2-19).
• Case study on concentrated animal feeding operations (USEPA 2002a, Appendix B).
• Re-registration of pentachlorophenol (USEPA 2002e, Appendix C).
Text Box 2-10. EPA Resources on Conceptual Models
• Ecological Risk Assessment Guidelines (USEPA 1998a, 40-41).
• Lessons Learned on Planning and Scoping for Environmental Risk Assessments (USEPA 2002a, 5-6).
• Risk Characterization: Science Policy Council Handbook (USEPA 2000d, 29-30, B-21, B-23).
• Framework for Cumulative Risk Assessment (USEPA 2003b, 25-27).
• A Framework for Assessing Health Risks of Environmental Exposures to Children (USEPA 2006b, 3-5
to 3-9).
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2.2.2 Analysis Plan
The analysis plan is the final stage of problem formulation (USEPA 1989, 2000e, 2002d, 2003b). It is
developed with attention to the conceptual model and the Agency's needs for the risk assessment. The
analysis plan describes intentions for the assessment, which may have been developed during the
planning and scoping process and it provides details on technical aspects of the risk assessment. In some
cases, it will specify a phased or tiered risk assessment approach to facilitate management needs;
scientific review (such as external peer review); and/or public, stakeholder and community involvement.
During analysis planning, hypotheses about the relationships described in the conceptual model are
evaluated to determine how they will be assessed using available and new data. Although the conceptual
model may identify a larger set of pathways and relationships, the analysis plan focuses on the pathways
and relationships that will be pursued in the risk assessment analyses. The rationale for selecting or
omitting pathways and relationships is incorporated into the plan, as is acknowledgement of data gaps and
uncertainties. The analysis plan also may include a consideration of how the level of confidence (or
precision) needed for the management decision compares with that expected from available analytical
approaches; this comparison determines data needs and evaluates which analytic approach is best. When
new data are needed, the feasibility of obtaining them is evaluated. The analysis plan is most useful when
it contains explicit statements of how measures were selected, what the measures were intended to
evaluate and which analyses they support.
The analysis plan may include these components:
• The assessment design and rationale for selecting specific pathways to include in the risk
assessment.
• A description of the data, information, methods and models to be used in the analyses (including
uncertainty analyses), as well as intended outputs (e.g., risk metrics).
• The associated data gaps and limitations.
Also described is the extent or aspects of the assessment that are qualitative rather than quantitative.
Analysis plans may be briefer extensive, depending on the assessment and its level of complexity. For
assessments that are performed for some purposes (e.g., EPA's new chemical assessments [USEPA
2013a] under the Toxic Substances Control Act [TSCA]9), a standard analysis plan is established for the
set of assessments to be conducted for the same purpose and regulatory context. The type or design of
analyses to be conducted is influenced by statutory requirements or programmatic objectives, data
availability, risk management options, available resources, and the purpose and scope of assessment.
Thus, risk assessment designs will vary, and variations will be reflected in the development of the plan.
For example, EPA performs risk assessments that range from deterministic, scenario-based assessments to
more complex, probabilistic, population-modeling analyses. Assessments may be screening-level or more
robust, depending on various factors, including the resources available for the assessment. Furthermore,
the organization of the analysis plan may vary with the purpose and context for the assessment.
In all cases, the analysis plan addresses the quality of data to be used; assessments of exposure, hazard
and dose-response; and risk analyses, including analyses of uncertainty and variability. These areas are
described in the subsections below.
9 Toxic Substances Control Act of 1976, 15 U.S.C. § 2601-2692.
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2.2.2.1 Data Quality Planning
In developing and implementing the analysis plan, several aspects of the data and information to be used
in the assessment are evaluated, including the following (USEPA 2003b):
• Soundness. The extent to which the scientific and technical procedures, measures, methods or
models employed to generate the information are reasonable and consistent with the intended
application.
• Applicability and utility. The extent to which the information is relevant for the intended use.
• Clarity and completeness. The degree of clarity and completeness with which the data,
assumptions, methods, quality assurance, sponsoring organizations and analyses employed to
generate the information are documented.
• Uncertainty and variability. The extent to which the variability and uncertainty (quantitative
and qualitative) in the information or in the procedures, measures, methods or models are
evaluated and characterized.
• Evaluation and review. The extent of independent verification, validation and peer review of the
information, procedures, measures, methods or models.
Evaluation of data quality requires context. Depending on how and for what purpose the data will be
used, the same data may be acceptable in one situation and unacceptable in another. EPA's Quality
System for Environmental Data and Technology (USEPA 201 le) ensures that environmental programs
and decisions are supported by data of the type and quality needed and expected for their intended use. A
critical aspect of this system involves the use of data quality objectives for the development of new data
and evaluation of existing data. Aspects of a risk assessment for which data quality may be important to
consider in the analysis plan include:
• The collection, evaluation and use of environmental data, including the distributions of
contaminants, as well as sources of variability, tolerance for potential decision errors and/or
precision requirements (USEPA 201 le).
• Development, evaluation and use of computer or mathematical models, including evaluation of
uncertainty and variability (USEPA 2009a).
• Use of secondary data collected for purposes other than the planned assessment.
Analysis plans also consider data quality guidance specific to the program for which the assessment is
being conducted. Information disseminated by the Agency also follows EPA's information quality
guidelines (USEPA 2002b). Some key data quality resources are given in Text Box 2-11.
Text Box 2-9. Data Quality Resources
• EPA Requirements for Quality Assurance Project Plans (USEPA 2001b).
• EPA's Quality System for Environmental Data and Technology (USEPA 2011e).
• Superfund Quality Assurance/Quality Control (USEPA 2011s).
• Resources for Planning New Data Collections (USEPA 2011n).
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Text Box 2-10. EPA Exposure Assessment
Resources for Human Health
• Guidelines for Exposure Assessment (USEPA
1992b).
• Guidance on Selecting Age Groups for
Monitoring and Assessing Childhood
Exposures to Environmental Contaminants
(USEPA 2005a).
• A Framework for Assessing Health Risk of
Environmental Exposures to Children (USEPA
2006b).
• Highlights of the Exposure Factors Handbook
(USEPA 2011g).
• Exposure Factors Handbook (USEPA 2011f).
2.2.2.2 Exposure Assessment Planning
The analysis plan describes the approach
(quantitative or qualitative) to be employed for
characterizing exposure in the risk assessment. See
Text Box 2-12 for EPA resources on how to
conduct exposure assessments. The exposure
assessment component of the analysis plan is
developed by drawing on the information,
considerations and decisions represented by the
conceptual model for human health (as described in
Section 2.2.1). Accordingly, the analysis plan
describes the exposure assessment elements
specified in the conceptual model, including the
relevant routes and pathways, frequency and
duration of exposures, populations and life stages,
and assessment metrics. The analysis plan also
defines the methods, models and information or
data that will be used, as well as the environmental
conditions or scenarios (e.g., conditions associated
with alternative standards or cleanup levels for
environmental contaminants or different uses for a pesticide). Key limitations, assumptions and
uncertainties associated with the tools and approaches are recognized in the analysis plan.
The analysis plan also identifies the approach for describing exposure variability. For example, the
approach might specify a deterministic, scenario-based assessment to provide point estimates for a
particular population (e.g., long-term residents or high-end consumers of a particular food such as fish) or
life stage (e.g., very young children). In contrast, a more complex, probabilistic population modeling
assessment might provide a distribution of estimates for the specific population assessed; an example
would be children living in three specific urban areas under environmental conditions associated with a
current standard or food consumption pattern (e.g., for specific age groups based on dietary survey
information). The rationale for the selected approach is described in the analysis plan, as well as the
extent to which estimates will be developed for the central and upper percentiles of the population being
assessed. Furthermore, the analysis plan generally delineates the approaches for assessing uncertainty and
variability in the exposure estimates.
2.2.2.3 Effects Assessment Planning: Hazard Identification and Dose-Response Analysis
The effects assessment is composed of hazard identification and dose-response analysis. The analysis plan
specifies the strategy for characterizing hazard and dose-response relationships for the stressors being
assessed. For example, the strategy may include use of publicly available hazard identification and dose-
response assessments that already have been prepared (in accordance with Agency guidance and
methods), such as those in EPA's IRIS database. Alternatively, the strategy may specify a different
approach for characterizing the hazard of the identified stressors and describing the dose- or
concentration-response relationship that will be used in the risk assessment. A range of factors that stem
from the chemical-specific information available, as well as from logistical considerations for the
assessment, may influence the extent to which the effects assessment may include qualitative aspects and
quantitative analyses.
EPA has established a variety of guidance documents for the hazard identification and dose-response
components of risk assessment (Text Box 2-13). These documents address the evaluation of particular
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Text Box 2-11. EPA Resources on Hazard Identification and Dose-Response Assessment
• Guidelines for the Health Risk Assessment of Chemical Mixtures and Supplementary Guidance for
Conducting Health Risk Assessment of Chemical Mixtures (USEPA 1986a, 2000e).
• Guidelines for Developmental Toxicity Risk Assessment (USEPA 1991b).
• Methods for Derivation of Inhalation Reference Concentrations (RfCs) and Application of Inhalation
Dosimetry (USEPA 1994).
• Guidelines for Reproductive Toxicity Risk Assessment (USEPA 1996).
• Guidelines for Neurotoxicity Risk Assessment (USEPA 1998b).
• A Review of the Reference Dose and Reference Concentration Processes (USEPA 2002f).
• Guidelines for Carcinogen Risk Assessment (USEPA 2005b).
• Supplemental Guidance for Assessing Susceptibility from Early-Life Exposure to Carcinogens
(USEPA 2005e).
• A Framework for Assessing Health Risk of Environmental Exposures to Children (USEPA 2006b).
types of toxicity, dose-response assessment and endpoint selection; the consideration of information on
mode of action (MOA) or pathways of toxicity; the role of toxicokinetic information; and factors
influencing sensitivity and susceptibility (e.g., nutrition, life stage, exposure characteristics, disease state).
Rather than describing in detail the steps in effects assessment, the analysis plan may instead reference
these guidance documents or other relevant published sources
2.2.2.4 Risk Characterization Planning
The analysis plan identifies and describes the strategy or approach for combining exposure information
with hazard and dose-response information to generate risk estimates or other measures for characterizing
health risk. The approaches may vary widely depending on considerations described above for the
planning and scoping phase, such as the following: the purpose and context for the assessment, available
information, available resources, and timeline. Risk analyses might range from deterministic, scenario-
based assessment to a probabilistic, population-modeling assessment. These approaches may yield
estimates for general population risk or for specific, defined groups within the general population. For
estimates of individual risk, calculations can consider central tendency and/or the upper end of the risk
distribution. The upper end of the distribution used for risk characterization may vary depending on the
needs of the assessment (e.g., the 90th, 95th or 99th percentiles) (USEPA 1992b).
As stated above, assessments may be screening-level or more robust, depending on the purpose and
availability of data. Decisions on the type or design of the assessment are influenced by statutory
requirements or programmatic objectives, data or resource availability and limitations, and the purpose
and/or scope of the assessment. Types of metrics that might be considered for the assessment include:
• Incidence of specific health outcomes.
• Risk of specific health outcomes.
• Occurrences of exposures above health-based benchmarks or comparison points.
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• Potential for occurrence of exposure above health-based benchmarks.
• Margins of exposure between a point of departure for an effect and a measured or estimated
environmental level.
• Hazard quotients (i.e., measured or estimated exposure levels divided by a reference value) for
specific exposure scenarios.
In defining the analyses to be performed the plan also describes the associated limitations, assumptions
and plans for the assessment of uncertainty and variability. EPA resources for risk analysis are described
in Text Box 2-14.
Text Box 2-12. Risk Analyses Resources
• Risk assessment guidance for EPA's Superfund Program (Clay 1991; USEPA 1989, 1991a, 1991c,
2001d, 2001e, 2004f, 2009b).
• Risk Characterization: Science Policy Council Handbook (USEPA 2000d).
• Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health
(USEPA 2000b).
• Framework for Cumulative Risk Assessment (USEPA 2003b).
• Air Toxics Risk Assessment Reference Library (USEPA 2004b, 2004g, 2006a, 2007c).
2.2.2.5 Uncertainty and Variability Planning
Drawing from EPA guidance and experience, the analysis plan describes how uncertainty and variability
will be characterized in the risk assessment. The complexity of the approaches will be influenced by
considerations identified earlier in the planning phase, including the purpose and context for the
assessment, as well as the timeline and resources. Planning for this stage of the assessment also will
consider how elements of an uncertainty/variability evaluation can inform different parts of the
assessment approach, improving the overall plan as well as the utility of the final product. The analysis
plan may consider the value of obtaining additional data or information to reduce areas of uncertainty.
More information about uncertainty and variability can be found in Text Box 2-15.
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Text Box 2-13. Definitions of Uncertainty and Variability
Uncertainty refers to imperfect knowledge or lack of precise knowledge of the real world, either for
specific values of interest or in the description of the system. Although numerous schemes for classifying
uncertainty have been proposed, most focus on two broad categories: parameter uncertainty and model
uncertainty. Descriptions of both areas are found in Risk Assessment Principles and Practices (USEPA
2004e).
Variability refers to inherent natural variation, diversity and heterogeneity across time and/or space or
among individuals within a population. Although we can describe and understand variability in the world
or a particular system better than uncertainty, it is unavoidable and cannot be reduced (USEPA 2010e).
Resources for Characterizing Uncertainty/Variability
• Guiding Principles for Monte Carlo Analysis (USEPA 1997b).
• Risk Characterization: Science Policy Council Handbook (USEPA 2000d).
• Process for Conducting Probabilistic Risk Assessment. Part A of Vol. 3 of Risk Assessment Guidance for
Superfund (USEPA 2001d).
• Risk Assessment Principles and Practices (USEPA 2004e).
• A Framework for Assessing Health Risk of Environmental Exposures to Children (USEPA 2006b).
• Guidance Document on Characterizing and Communicating Uncertainty in Exposure Assessment (WHO
2008).
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3. Public, Stakeholder and Community Involvement
As discussed in Section 2.1 Planning and Scoping, public, stakeholder and community involvement are
key elements of the Framework. The level of public, stakeholder and community involvement varies
depending on the activity and program requirements. Figure 3-1 highlights key questions and
considerations for stakeholder involvement. As indicated in the figure, public, stakeholder and
community involvement are considered early and may be considered often in the risk assessment and
decision-making process. Although the single term "public" could be used to include the full range of
external stakeholders, including community members, all three terms are specifically included in
recognition of the differences in what each term may convey to different readers and in recognition of the
unique roles played by internal stakeholders. See Section 2.1.5.
Key Considerations for Public, Stakeholder
and Community Involvement
What are the opportunities for public involvement?
Who are the stakeholders or community groups?
What communication products are needed?
What mechanisms for community and public involvement
will be most effective in actually involving the public and
community?
Figure 3-1. Framework for Human Health Risk Assessment to Inform Decision Making: Key Questions
and Considerations for Public, Stakeholder and Community Involvement
Public participation is an essential aspect of EPA's process for making decisions to achieve the Agency's
mission of protecting human health and the environment. It provides EPA with the opportunity to obtain
and consider a range of views on the issue being assessed, as well as on management options. Effective
public involvement (including key stakeholders and/or communities) can enhance the deliberative process
and improve the content of the Agency's decisions (USEPA 2003d); it is consistent with sustainability
principles. A critical feature of the Framework is the involvement of the public, stakeholders and
communities at key points in the process. The timing, frequency and level of community involvement will
depend on a number of factors, including regulatory requirements, the nature of the decision and
community interest.
As discussed in Section 2.1.5, public involvement may begin when individuals and organizations seek
information from EPA about a topic or issue or when the public receives information from EPA because
the Agency identifies them as a potentially affected party. EPA's outreach activities serve and engage
these individuals and organizations (USEPA 2003d).
Each decision or action by the Agency may call for a different level of public involvement, and certain
members of the public, stakeholders or communities may need to be involved at different steps in the risk
assessment process. EPA's Public Involvement Policy (USEPA 2003d, 1) states that "EPA staff and
managers should seek input reflecting all points of view and should carefully consider this input when
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making decisions." In addition, the policy states that "EPA should not accept any recommendation or
proposal without careful, critical examination" (USEPA 2003d, 1).
The overall goal of public involvement is to provide opportunities for people to contribute at every point
along the progression of the decision-making process. Individuals and groups decide for themselves
whether, when and how to participate. It is recognized that not everyone who is interested in the situation
being assessed chooses to be an active participant in providing input (e.g., facts, data, opinions) to policy
or regulatory decisions of the Agency. The information provided through the public involvement process
is considered by the Agency's officials in the decision-making process.
3.1 Audiences for the Risk Assessment
If properly planned and executed, the technical risk characterization itself will be consistent with the level
of detail and complexity of the assessment conducted. The information presented, however, may vary by
regulatory and audience needs. Co-regulators such as states and tribal nations also are audiences for the
risk assessments; these groups may prefer a high level of technical detail in communication of an
assessment. Several statutes and executive orders affect the development of regulatory rules and other
EPA decisions and may define specific activities for public, stakeholder and community involvement. In
addition, several programs have developed specific guidance on public involvement—variously termed
public, stakeholder and community involvement (Dalton and Harter 2009). These guidance documents are
listed in Text Box 3-1.
3.1.1 Stakeholders
The appropriate stakeholder involvement process will depend on the specifics of the situation.
Stakeholder involvement processes are highly adaptive and can be modified to take changing
circumstances into account. Additional details are found in Better Decisions Through Consultation and
Collaboration (Dalton and Harter 2009).
Staff and management of EPA offices are important internal stakeholders in the process of drafting rules,
policies, permits or plans. The planning process considers inclusion of internal stakeholders in
establishing the project. Three key considerations are to include stakeholders early, obtain "buy-in" along
the way and keep stakeholders engaged.
Communication with stakeholders outside the Agency may vary depending on regulatory requirements.
For example, regulatory and non-regulatory activities in the Office of Chemical Safety and Pollution
Prevention provide mechanisms to interact with stakeholders while EPA is developing the assessments.
During the review of pre-manufacture notices (PMNs) for new substances, the EPA Program Manager or
other Agency personnel may contact the submitter for additional information if EPA identifies concerns
or needs clarification of the technical information provided in the PMN. Rules issued under TSCA
Section 5 (i.e., Significant New Use Rules) and Section 6 (e.g., formaldehyde) provide a notice and
comment period in the Federal Register that allows public involvement in the Office of Pollution
Prevention and Toxics' (OPPT) rulemaking actions (e.g., Proposed Significant New Use Rule for Multi-
walled Carbon Nanotubes [USEPA 2010c] and Formaldehyde Emissions From Pressed Wood Products
[USEPA 2008]). Public meetings are scheduled in different parts of the United States to increase public
involvement in the rulemaking process. Under the High Production Volume (HPV) Challenge Program,
OPPT posts notice of and links to data summaries and test plans for HPV chemicals (USEPA 2012o) and
provides a 120-day public comment period. The Office of Pesticide Programs provides multiple
opportunities for public comment and involvement in its registration review program, including at the
opening of the process for a chemical on the Preliminary Work Plan, on the draft risk assessment and on
the proposed regulatory actions.
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Text Box 3-1. Resources for Public Involvement Efforts, Tools and Policies
Public Involvement
• The Model Plan for Public Participation (USEPA 2000c).
• EPA Public Involvement website (USEPA 2011d).
• Pesticide Program Dialogue Committee. This Committee provides a forum for a diverse group of
stakeholders to provide feedback to the pesticide program on various pesticide regulatory, policy
and program implementation issues (USEPA 20111).
Community Involvement
• Superfund Community Involvement Plans (USEPA 2002g).
« EPA's Superfund Community Involvement Handbook (USEPA 2005d).
• Superfund Community Involvement Publications Web page (USEPA 2011r).
Risk Communication
• Seven Cardinal Rules of Risk Communication (Covello and Allen 1988; USEPA 1988).
• Risk Communication. Vol. 4 of Guidance for Assessing Chemical Contaminant Data for Use in Fish
Advisories (USEPA 1995c).
• Lessons Learned About Designing, Developing, and Disseminating Environmental Information
Products (USEPA 2000a).
• Risk Communication in Action: The Risk Communication Workbook (USEPA 2007d).
• Risk Communication in Action: The Tools of Message Mapping (USEPA 2007e).
Sustainability
• Sustainabilitv and the U.S. EPA (NRC 2011).
Another example of stakeholder involvement is the IRIS process (USEPA 2012k), which provides
multiple opportunities for stakeholder participation. The process includes a call for nominations that
allows stakeholders to suggest chemicals for assessment through the IRIS Program. Nominations include
a description of why the chemical(s) should be considered for assessment. Multiple opportunities for
review and comment occur during the development of health hazard assessments. For example, the IRIS
process includes a step that provides for review by other offices within EPA (Agency review) and two
opportunities for interagency science consultation and discussion, enabling other federal agencies to
comment on the assessment. Finally, during the period of public review and comment, any interested
member of the public may comment on the assessment; there also is a public listening session in which
any stakeholder or member of the public has the opportunity to speak about the assessment.
3.1.2 Community
Community involvement may be a component of the stakeholder involvement process, particularly in
cases in which the issue assessed relates to a specific location (e.g., decisions regarding contaminated
waste sites or facilities with environmental releases). Community involvement is the process of engaging
in dialogue and collaboration with community members who may be affected directly by the risk
assessment. For example, in the Superfund Program, the goal of community involvement is to advocate
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and strengthen early and meaningful community participation during the investigation, while conducting
the risk assessment and during the decision-making process. For additional information see the EPA
Public Involvement website. USEPA 20 lid and USEPA 2011q.
3.2 Communication
Successful communication begins early in the risk assessment process—during planning and scoping and
problem formulation - see Section 2.1.5 — and has a pivotal role throughout the process. As the Silver
Book (NRC 2009, 250) points out, "[Communication among those involved in the policy and technical
evaluations are [sic] difficult to achieve, but they are necessary for success." Communication of risk may
be challenging as a result of the complexity of the information being conveyed, the inherent uncertainty in
risk estimates and the varying needs of the audiences (e.g., scientists, risk managers, various stakeholders,
the media, and the general public). The Silver Book (NRC 2009, 66) recognized this issue, stating that "...
the critical final process in risk assessment is ultimately communication."
Risk communication begins with understanding the risk characterization portion of the risk assessment.
Risk characterization is an integral part of a risk assessment and summarizes the key findings, as well
as the strengths and weaknesses of the assessment, for risk managers and others. Although it provides
information that may be useful for communicating with the public, risk characterization is not
synonymous with risk communication.
Risk communication includes the process of providing information to the public—including
individuals, groups and other institutions—about levels of health or environmental risk. Risk
communication is used for such things as information and education, behavior change and protective
action, disaster warnings and emergency information, and joint problem solving. Although the final
risk assessment documentation (including the risk characterization) can be used to communicate with
the public, the risk communication process often is better served by a separate set of documents
designed for particular audiences.
Risk communication tools are written, verbal or visual statements containing information about risk.
These tools put a particular risk in context, possibly adding comparisons with other risks, and often
include advice about risk reduction behavior. Risk communications also can encourage a dialogue
between the sender and receiver of the message (USEPA 2007d). In general, the communication tools
should be concise and provide adequate information for the user, although not at the level of detail
provided in the risk characterization. In addition, care is required to assure that the risk information is
consistent with the data provided in the risk characterization and includes risk assessment results, the
strengths and limitations of the analysis, and how they will be used by risk managers.
Risk communication documents should be designed to consider the intended audience for the information.
For example, risk managers generally prefer not to receive the depth of detail found in the technical risk
characterization. The usual products prepared for risk managers from the risk characterization provide a
summary and can take various forms depending on specific needs (e.g., executive summary, bulleted list
of key issues and conclusions, briefing packages) (USEPA 2000d). Risk characterization products
prepared for the public, stakeholders and communities can come in many forms. Generally, these
communication pieces carry forward the key issues and describe conclusions in a lay person's context
rather than a technical one (e.g., that of a scientific presentation or paper); this can include plain language
definitions, translations into appropriate languages, use of graphics as appropriate to convey information,
and so on. Communication products are developed to meet the needs of the intended audience and may
include products such as fact sheets for interested members of the public, press releases, slide shows,
public relations notices, decision documents, and speeches and talks (USEPA 2000d). Text Box 3-1
identifies resources helpful in developing a risk communication plan for various audiences.
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4. Risk Assessment
Risk assessments conducted for EPA range from relatively simple to complex, depending on factors that
include the needs of the risk management decision being made and the availability of relevant data.
Consistent with Agency policies and guidance, the analyses that contribute to a risk assessment may range
from those based on default assumptions to more refined analyses that include site-specific information
and quantitative uncertainty assessment (USEPA 1992b, 2005b, 201 If). Planning and scoping identifies
the level of assessment appropriate for the needs of the risk manager and the role that risk information
plays in the decision. Information gathered during planning and scoping is used during problem
formulation to develop a conceptual model and analysis plan. The assessment step builds on the
conceptual model and implements the analysis plan. As information is developed and preliminary
conclusions are drawn, it is not uncommon to revisit data needs or revise the conceptual model and
analysis plan.
EPA has issued guidance on all four steps of the risk assessment paradigm (i.e., exposure assessment,
effects characterization, which includes hazard identification and dose-response assessment, and risk
characterization); these publications are highlighted in Section 2. The steps in risk assessment often are
performed together, in an integrative fashion, rather than as a linear, sequential process. This Framework
document focuses on the context, utility and planning for the risk assessment itself; therefore, it does not
provide detail on the conduct of the steps.
EPA risk assessments may focus on individual risk metrics or may include population-level and/or life
stage-specific assessments to inform characterization of risk. Different categories of assessments may be
conducted by the Agency depending on the specific types of regulatory or programmatic decisions the
assessment is intended to inform. The Agency's Risk Assessment Portal (USEPA 2012n) provides basic
information about environmental risk assessments and offers a comprehensive set of links to key EPA
tools, guidance and guidelines.
Figure 4-1 highlights the assessment phase in the Framework, detailing several cross-cutting areas for
consideration in exposure or effects characterization. The risk assessor might consider available data on
metabolism; modeling; MOA; toxicity; cumulative risk (exposure and/or effects); the susceptibility of
individuals based on factors such as life stage, genetics and gender; specific population groups, including
socio-economic considerations; uncertainty and variability; and other factors relevant to the
characterization of risk. The landscape of risk assessment is changing, with new advances in molecular
biology, computational toxicology and risk assessment methodology. The areas of consideration noted in
Figure 4-1 are meant to be illustrative of today's practices rather than definitive or comprehensive, and
they are likely to change as the science of risk assessment advances.
4.1 Exposure Assessment
Exposure assessment is one of the primary components of risk assessment; it describes how humans come
into contact with hazards. The approaches employed for this component may vary across risk assessments
to reflect considerations described in the conceptual model and analysis plan, as well as regulatory needs.
The Guidelines for Exposure Assessment provides principles, concepts and methods used by EPA in
evaluating exposures (USEPA 1992b). The use of exposure science has been instrumental in forecasting,
preventing and mitigating exposures that lead to adverse human health outcomes. It addresses the
intensity and duration of human contact with different types of stressors (e.g., chemical, physical,
biological) and their fate in living systems, including vulnerable populations and susceptible life stages
(NRC2012).
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Exposure Assessment
How and to what range of concentrations/doses are
populations/life stages of interest exposed?
How do risk management options affect existing/resulting
conditions of exposure?
Effects Assessment
Hazard ID: What adverse endpoints are associated with
agents or stressors of concern? Are there data to identify
susceptible populations or support a MOA for the agent or
stressor?
Dose-Response Assessment: What is the relationship
between exposure/dose and the likelihood of each
endpoint at the exposure range of interest? How does
MOA and other relevant information affect choices of
low-dose extrapolation?
Risk Characterization
What is the nature and magnitude of risk for existing
conditions and for options?
What are the sources and magnitude of uncertainty and
variability in all steps of the risk assessment?
Figure 4-1. Framework for Human Health Risk Assessment to Inform Decision Making: Key Questions
and Considerations for Assessment
Exposure is characterized, quantitatively or qualitatively, for relevant routes and pathways, frequency and
duration, and populations and life stages. The specific type of exposure estimation needed and the level of
complexity employed for this component of the assessment will vary depending on the assessment
purpose, legal authority and other factors considered in the planning and scoping step. For example, this
step may involve collection of new data, implementation of simple or complex exposure models or data
analysis. A key aspect of all exposure assessments is the consideration of the potential existence of
susceptible or more highly exposed populations, life stages or groups. Based on considerations and
decisions in the conceptual model, quantitative exposure assessments may include the development of
estimates specific to these populations or life stages. The available toxicokinetic information also may be
characterized and internal doses calculated. EPA's exposure factors handbook provides a compendium of
exposure factors for a number of parameters for adults and children, including such metrics as ingestion
of soil, time spent in residence, surveys offish ingestion, ingestion of homegrown products and inhalation
rates (USEPA 201 If). Some key elements of exposure characterizations are listed in Text Box 4-1.
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Text Box 4-1. Key Elements of an Exposure Assessment
• Assess sources, pathways and routes of exposure and determine approach for consideration of
multiple pathways, as relevant.
• Investigate patterns of exposure (e.g., frequency and duration).
• Assess populations and life stages (e.g., the general population or highly exposed, vulnerable, or
susceptible groups) and determine bases for inclusion.
• Consider the rationale for the analysis approach, including any monitoring or modeling needs.
• Consider variability in exposures and appropriate exposure distributions (e.g., the use of Monte
Carlo or kriging).
• Establish descriptors of exposure, generally including estimates for "average" and "high-end"
exposures, as well as susceptible populations or life stages.
• Determine data and methods used in developing the exposure estimates.
Source: Adapted from EPA's Guidance for Risk Characterization (USEPA 1995a) and Guidelines for
Exposure Assessment (USEPA 1992b).
4.2 Effects Assessment
In human health risk assessment, the characterization of effects includes hazard identification and dose-
response assessment. The approaches employed for these components, including, for example, the level
of detail and complexity of quantitative aspects may vary across different risk assessments and will reflect
considerations described in the conceptual model and analysis plan.
4.2.1 Hazard Identification
Hazard identification is the process of identifying the type of hazard to human health (e.g., cancer, birth
defects) posed by the exposure of interest for a given risk assessment. Hazard identification for most
Agency risk assessments focuses on chemical agents. Chemical agents are a subset of all stressors
(e.g., chemical, biological, social or physical) (USEPA 2003b). In the case of chemical agents, the process
examines the available scientific data for a given chemical (or group of chemicals) and often develops a
characterization of hazard. This step requires identification, evaluation and synthesis of information to
describe the health effects of individual chemicals or chemical mixtures. Studies evaluated may include
human clinical or epidemiological studies, in vivo or in vitro laboratory animal studies, or mechanistic or
kinetic studies in a variety of test systems. In recent years, risk assessors have begun to consider
additional types of data during hazard identification, for example, those from computational toxicology
(quantitative structure-activity relationships, high-throughput assays) and genomic response assays. Other
data types may be identified in the future. Key aspects of hazard identification include consideration of
available information on toxicokinetics (i.e., how the body absorbs, distributes, metabolizes and
eliminates chemicals) and toxicodynamics (i.e., the effects that chemicals have on the body), as well as
potential MOAs (or toxicity pathways) related to the health effects identified. Text Box 4-2 describes
some contexts in which the MOA or the adverse outcome pathway10 is considered.
10 Adverse Outcome Pathway: A description of plausible causal linkages that illustrates how a chemical interaction
with a biological system at the molecular level causes biological effects at the subcellular, cellular, tissue, organ and
whole animal levels of observation (Ankley et al. 2010).
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Text Box 4-2. Example of a Consideration for Effects Characterization: Mode of Action
The Guidelines for Carcinogen Risk Assessment (USEPA 2005b) emphasizes the important contribution
that understanding a chemical's MOAA makes to informed risk assessment decisions. These can
include:
• Relevance of data (e.g., animal, in vitro, in silica) for human health risk assessment.
• Harmonization of risk assessments for various health endpoints.
• Conditions under which an agent is likely to cause cancer (or some other health endpoint).
• Choice of low dose extrapolation (e.g., linear or nonlinear).
• In cancer assessments, applicability of default age-dependent adjustment factors (ADAFs) for early
lifestage exposure.
The carcinogen guidelines and supplemental guidance (USEPA 2005b, 2005e) include a framework for
assessing available data to determine whether a hypothesized MOA is likely to be involved in
induction of a specific tumor type. This framework also is useful for assessment of other health
endpoints. For an example of application of the MOA framework to reproductive effects, see the
Office of Pesticide Program's work on the pesticide cacodylic acid (USEPA 2005c, 2012c).
Although the scientific community historically has focused on understanding how chemicals cause
biological effects, the use of detailed information on MOA in human health risk assessment has been
increasing as methods are refined and more reliable information is generated. Recognizing the critical
role in risk-based decision making of understanding how a chemical causes effects, Toxicity Testing in
the 21st Century (NRC 2007) proposed that the next generation of toxicology studies be designed to
focus on "toxicity pathways."8 These are normal biological pathways that respond to chemicals or
other stressors depending on the magnitude of the insult (dose, timing, duration and frequency of
perturbation). For example, at low exposures, some systems will remain within their homeostatic
limits, while at higher levels of stress, adaptive biologic responses may occur, the adversity of which
may depend on the physiological characteristics of those exposed; that is, groups of sensitive
individuals may respond adversely, whereas others may not. At still greater magnitude of stress, the
adaptive capacity may be overwhelmed for all groups, increasing the likelihood of adverse effects.
These and similar concepts may provide approaches for applying greater scientific understanding of
what a chemical does in causing an effect. This knowledge in turn will support improved human
health risk assessments.
The availability of data for these types of detailed assessments varies widely across chemicals.
Accordingly, EPA and the NRC continue to support the use of default methods and procedures to
complete a risk assessment when data are lacking.
AMOA: The sequence of key events and cellular and biochemical events (measurable parameters), starting with the
interaction of an agent with the target cell or tissue, through functional and anatomical changes, resulting in cancer or other
adverse health effects (Boobis et al. 2008, USEPA 2005b). MOA differs from mechanism in that the latter implies a more
detailed understanding of the molecular basis of the toxic effect (Seed et al. 2005).
BToxicity Pathways: Cellular response pathways that, when sufficiently perturbed, are expected to result in adverse health
effects (NRC 2007).
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In hazard identification, the strengths and limitations of the data and information used to support the
weight of evidence are described, including areas for which data may be unavailable (data gaps). In
situations where a quantitative risk assessment is to be performed, a particular study or group of studies
may be identified for use in dose-response assessment.
Hazard identification may be focused on health risks of exposure to specific individual chemicals or
identification of groups of chemicals with common MOAs (e.g., pesticides). In some cases, the specific
chemicals are identified by statute (e.g., the CAA hazardous air pollutants). Thus, the chemical exposures
to be evaluated in the risk assessment may vary across programs, depending on the legal authorities under
which the assessment is conducted. In all cases, the conceptual model and analysis plan will specify the
extent, content and limits of the hazard identification.
4.2.2 Dose-Response Assessment
In this component of effects characterization, the relationship between the exposure or dose of a
contaminant and the occurrence of particular health effects or outcomes is assessed. Drawing from the
conceptual model and analysis plan, the dose-response assessment (USEPA 2012q) may be developed
using a combination of data, science policy decisions and models. For example, the response assessed
might be incidence of some endpoint or health outcome (e.g., cancer incidence, incidence of a critical
effect, hospital admission for a specific outcome, death) or it might describe the magnitude of a response
(e.g., magnitude of IQ loss). The assessment also may include the derivation of an established metric,
such as EPA's reference doses and reference concentrations (USEPA 2002f).
In documentation of the dose-response assessment, aspects of the full database, particularly the key
studies, are described along with their strengths and weaknesses, including the potential impact of those
weaknesses on the reliability of the overall assessment. Toxicokinetic information also is described; in
data-rich situations, measured or modeled target tissue dose may be used in the dose-response
calculations. In some cases, multiple chemicals may be included in a single dose-response assessment,
with decisions made about the grouping of chemicals, as well as the means by which the chemicals will
be combined (e.g., common MOA, common toxic effect, estimation of cancer potency factors, specific
data for chemical mixtures, likelihood of simultaneous exposure). Decisions on these issues are specific to
the individual risk assessment and may be influenced by the information gathered during problem
formulation. Details of EPA practices and policies related to dose-response assessment can be found in
the various guidance documents noted in Section 2 of this document and at EPA's risk assessment
Guidance & Tools Web page (USEPA 2012h), as well as in documents particular to specific assessment
contexts.
4.3 Risk Characterization
Risk characterization is the final, integrative step of risk assessment. This step integrates exposure
assessment and effects assessment into quantitative and qualitative estimates of risk for the evaluated
population(s) (USEPA 20 lip). EPA has incorporated advice on scope and necessity of appropriate risk
characterization into its guidance; see, for example NRC 1994 and NRC 1996. The Agency's Risk
Characterization: Science Policy Council Handbook (USEPA 2000d) describes risk characterization as
the step that "integrates information from the preceding components of the risk assessment and
synthesizes an overall conclusion about the risk that is complete, informative, and useful for decision
makers" (USEPA 2000d, 10).
A good risk characterization will restate the scope of the assessment, express results clearly, articulate
major assumptions and uncertainties, identify reasonable alternative interpretations, and separate
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scientific conclusions from policy judgments (USEPA 201 Ip). EPA's risk characterization policy calls
for conducting risk characterizations in a manner that is consistent with the following principles:
• Transparency: The characterization should fully and explicitly disclose the risk assessment
methods, default assumptions, logic, rationale, extrapolations, uncertainties, and overall strength
of each step in the assessment.
• Clarity: The products from the risk assessment should be readily understood by readers who
were involved and not involved in the specific risk assessment process. Documents should be
concise, be free of jargon, and use understandable tables, graphs and equations as needed.
• Consistency: The risk assessment should be conducted and presented in a manner that is
consistent with EPA policy, and consistent with other risk characterizations of similar scope
prepared across programs within EPA.
• Reasonableness: The risk assessment should be based on sound judgment, with methods and
assumptions consistent with the current state-of-the-science and conveyed in a manner that is
complete, balanced and informative.
These four principles—Transparency, Clarity, Consistency and Reasonableness—are referred to
collectively as TCCR (USEPA 2012r). To achieve TCCR in a risk characterization, the same principles
need to have been applied in all of the prior steps in the risk assessment that lead up to the risk
characterization.
A risk characterization conveys the nature and presence or absence of risks in quantitative and qualitative
terms. It describes information on how the risks were assessed, where assumptions and uncertainties still
exist, and where policy choices will need to be made. If numerical estimates of effects or exposure are not
available, qualitative estimates may be used to characterize risk.
In describing the nature and magnitude of risk for the assessed environmental condition, the risk
characterization describes the universe of people who may be affected, including sensitive and/or
susceptible life stages or populations. As indicated in EPA's risk characterization policy, EPA risk
assessments generally address or provide descriptions of individual risk (including central tendency and
high end portions of risk distribution), population risk, and important population subgroups, such as
highly exposed or highly susceptible groups (Browner 1995; USEPA 2000d; USEPA, 1995b). Specific
life stages and/or populations (e.g., potentially at-risk groups) are first considered in the planning and
scoping phases and may be evaluated explicitly in the risk assessment. Text Box 4-3 presents details on
characterizing cancer risk from early life exposures. Additionally, in consideration of highly exposed or
susceptible life stages and/or populations, risk characterizations generally present multiple risk descriptors
(e.g., high-end and central-tendency) and may include risk descriptors (e.g., maximum exposed
individual, reasonable maximum exposure, central-tendency) that are specific to underlying legislative
requirements (e.g., CAA, CERCLA, CWA) (USEPA 1995a).
In risk characterization, information about uncertainty and variability (defined in Text Box 2-15) from
each step of the risk assessment (e.g., use of default parameters, choice of models and data used for
quantitative analysis) is integrated into an overall discussion and/or analysis of the impact of the
uncertainty and variability on estimated risks. EPA uses several techniques to ensure that risk is not
underestimated with data are lacking. EPA may characterize uncertainty using a qualitative assessment of
the overall strength and limitations of the data used in the assessment. To estimate the effect of data
uncertainty on modeled pollutant impacts, various modeling tools may be employed. Even the
quantification of uncertainty and variability in probabilistic risk assessments itself includes an element of
additional uncertainty. It is important that the level and type of uncertainty analysis be commensurate
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Text Box 4-3. Characterizing Cancer Risk from Early-Life Exposure
When assessing cancer risk resulting from early-life exposures, the risk assessor considers life-stage
differences in both exposure and dose-response relationships. The Guidelines for Carcinogen Risk
Assessment (USEPA 2005b) and EPA's Supplemental Guidance for Assessing Susceptibility from Early-
Life Exposure to Carcinogens (USEPA 2005e), provide guidance in this regard. The preferred
approach is the calculation of life-stage specific slope factors and use of life-stage specific exposure
information when this is supported by data. In the absence of sufficient data, age-dependent
adjustment factors (ADAFs) in dose-response relationships (i.e., adjustments to slope factors based
on age groups) are combined with age-specific exposure estimates when assessing cancer risks for
chemicals determined to act through a mutagenic MOA. This integrative approach is used to assess
total lifetime risk resulting from lifetime or less-than-lifetime exposure during a specific portion of a
lifetime.
with the decision to be made. In some cases, highly detailed quantitative uncertainty analyses might not
be warranted, whereas they might be useful for others.
Communicating the results of probabilistic risk assessment requires particular attention. Probabilistic risk
assessments provide range and likelihood estimates for one or more aspects of hazard, exposure or risk,
rather than a single point estimate (USEPA 2010e; Zartarian et al. 2005). A goal of probabilistic risk
assessment is the quantitative characterization of the uncertainty and variability in estimates of hazard,
exposure or risk (USEPA 1997b). Risk assessors are responsible for sharing information on probabilistic
results so that risk managers have a clear understanding of quantitative assessments of uncertainty and
variability and how this information will affect the risk management decision. Clear communication
between the risk assessment team and the decision maker is essential in aiding the decision maker's
understanding and use of the results from the probabilistic risk assessment.
Areas of uncertainty that may make an appreciable difference in the assessment results or conclusions are
highlighted in the risk characterization. For example, the risk characterization document includes a
discussion of any issues associated with the data quality (e.g., reliability and availability) that may impact
the calculated risks or other metrics. This may include explicit discussions of the evaluation process and
description of issues that may impact the reliability or utility of the endpoints identified for use. A key
question addressed in the risk characterization is whether the risk assessment outcome would change
significantly if data were interpreted differently or if different models were used. This kind of uncertainty
is difficult or impossible to characterize probabilistically. It is essential, however, to describe uncertainty
and variability so that the impact will not be overlooked or misinterpreted. It may be useful to revisit the
analysis plan if the uncertainty/variability analysis determines that gathering additional information will
have a substantive impact on reducing uncertainty in the assessment.
4.4 Characterizing the Risks for Risk Managers
It is the role of the risk assessor to provide a transparent description of all aspects of the risk assessment
(e.g., default assumptions, data selected, policy choices) to make clear the range of plausible risk
associated with each risk management option. Clear communication between the risk assessors and risk
managers is vital to assuring that risk information is conveyed appropriately.
Whatever approach is used to estimate risk, it is important to be clear in describing the range of possible
risks (including central tendency and high end portions of the risk distribution), as well as important
subgroups such as highly exposed or highly susceptible groups. For example, the extent to which the
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assessment may underestimate or overestimate risk for some populations should be highlighted to inform
the decision making appropriately. As discussed in Section 4.3, these uncertainties may be characterized
quantitatively (e.g., using probabilistic methods) or qualitatively (e.g., describing how the results would
change if the data were interpreted differently). The risk assessment characterizes the nature and
magnitude of risk and who is at risk under different risk management options (including a status quo
option).
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5. Informing Decisions
EPA uses risk assessment as a key source of scientific information for evaluating risks and related
outcomes associated with possible risk management options, and ultimately, informing the process of
making sound decisions about managing risks to human health and the environment. As noted in Section
4.3, risk assessments that are well-planned and focused will be most useful and informative for decision
making.
EPA makes many types of decisions that cover a wide range of environmental issues and pollutants. Each
of these decisions is made in the context of a combination of statutes, precedents and stakeholders. The
statutes establish legal requirements that generally describe the protection that EPA regulations must
achieve, and in so doing, also may specify aspects of the risk assessment. Statutes also may identify other
factors to inform the regulatory decision, such as consideration of best available control technologies, cost
and benefit considerations, and so forth. Accordingly, how risk assessment informs decision making may
be affected by such statutory or regulatory requirements and restrictions.
The informational needs, identified as part of planning and scoping, and are updated and refined
throughout the assessment process to ensure that the risk assessment is fit-for-purpose. Much of this
information will be in the risk characterization and is based on transparency in conducting and explaining
the risk assessment combined with clarity, consistency and reasonableness in the preparation of the risk
description (USEPA 2000d). The science supporting the risk assessment conclusions, as well as
consideration of variability, susceptibilities and uncertainties, informs decisions among the risk
management options presented in the risk assessment.
In addition to consideration of the risk assessment, some statutes also may require consideration of other
assessments, such as benefit-cost analysis, which may draw upon the risk assessment in whole or in part.
Addressing these considerations when scientific assessments are integrated into a comprehensive analysis
requires collaboration among the risk assessors, economists and other analysts.
As recognized above, risk assessment is one of many considerations that inform Agency decisions. Other
considerations may include:
• Laws and Regulatory Requirements: legal mandates, flexibility and constraints.
• Economic Analyses: costs, benefits and impacts of potential actions.
• Sustainability: life cycle, multimedia and long-term impacts.
• Technological Considerations: feasibility, impact and range of risk management options.
• Political Considerations: interactions with different branches and levels of government, as well
as the citizens that they represent.
• Public and Social Considerations: susceptible population groups and life stages, nonchemical
stressors and cumulative risk assessment considerations.
Some of these considerations are independent of the risk assessment, though the analysis of some may be
informed by the risk assessment.
Some key questions and considerations for the informing decisions step of the process are shown in
Figure 5-1.
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Key Risk-Based Considerations
for Informing Decisions
What is the health protection level provided by each
option?
What are the key limitations/uncertainties associated
with risk estimates for each option?
Does consideration of other factors (e.g., technologies,
costs, social considerations, environmental justice,
sustainability) vary with each option?
Figure 5-1. Framework for Human Health Risk Assessment to Inform Decision Making: Key Questions
and Considerations for Informing Decisions
In this step of the process, the goal of the risk assessment team ultimately is to paint as complete a picture
as possible regarding risk for a range of possible management options. The description of the risk
management decision should clarify how the risk assessment and other factors informed the decision.
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6. Summary
The Framework for Human Health Risk Assessment to Inform Decision Making lays out a Framework
for conducting human health risk assessments in support of decision making at EPA. It focuses on the
planning and scoping and problem formulation steps, drawing on NRC (2009) and other advisory groups,
and EPA experience. For example, the Framework addresses recommendations in the Silver Book (NRC
2009) on assuring the utility of risk assessment, which the Framework terms as being fit for purpose. See
Text Box 6-1. As indicated in the Framework diagram, Figure 6-1, the NRC's 1983 four-step risk
assessment paradigm is maintained, but there is increased emphasis on interaction between risk assessors
and risk managers in planning the assessment to maximize utility. Emphasis on utility is maintained
throughout the process, beginning with planning and scoping and continuing through the evaluation of the
applicability of the risk assessment in informing decisions.
The Framework highlights the practical nature
of risk assessment. For example, although the
Agency is committed to advancing risk
assessment science, assessments are not
academic exercises. Instead, they are intended
to support decision making for the protection of
human health. Application of the Framework,
with its emphasis on problem formulation and
the utility of the risk assessment, ultimately will
result in better, more transparent choices among
risk management options. This Framework
builds on Agency guidelines, policies and
guidance and is directed at improving risk
assessment products but does not overturn or in
any way change existing science policy
decisions.
EPA programs routinely apply components of
this Framework, as evidenced by the examples
cited in the preceding sections. It is expected,
however, that this document will facilitate the
formal recognition of these components in
Agency risk assessment activities. The
Framework's explicit recognition of the roles for
planning and scoping; public, stakeholder and
community involvement; and consideration of
utility will assist in the development of risk
assessments focused on informing decisions.
Furthermore, "institutionalization" of this
Framework for Human Health Risk Assessment
to Inform Decision Making will contribute
transparency to the Agency's risk assessment
process and a level of consistency across
assessments, media and programs, as well as
between human health and ecological outcomes.
Text Box 6-1. The Silver Book
Recommendations for a Human Health Risk
Assessment Framework
• The technical framework for risk assessment
presented in the Red Book should remain
intact but should be embedded in a broader
framework in which risk assessment is used
principally to help to discriminate among
risk-management options (NRC 2009, 256).
• The framework for risk-based decision
making (Figure 6-1) should have as its core
elements a problem-formulation and scoping
phase in which the available risk-
management options are identified, a
planning and assessment phase in which risk-
assessment tools are used to determine risks
under existing conditions and with proposed
options, and a management phase in which
risk information and other factors are
integrated to inform choices among options
(NRC 2009, 256).
• EPA should phase in the use of the
framework with a series of demonstration
projects that apply the framework and that
determine the degree to which the approach
meets the needs of Agency risk managers,
and how risk-management conclusions differ
as a result of the revised orientation (NRC
2009, 256).
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/]
; I
U
<*
\
\1 >i
\o\tiatioo
Planning & Scoping
Problem Formulation
Conceptual
Model
Analysis
Plan
Risk Assessment
Exposure
Assessment
Effects
Assessment
• Hazard
Identification
• Dose Response
Risk
Characterization
7 i
Figure 6-1. Framework for Human Health Risk Assessment to Inform Decision Making
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The Framework is intended to be flexible. The structure will accommodate advances in the technology
and science. These might include development of life cycle analyses and use of data from high throughput
assays (i.e., those that generate data much more rapidly and for many more chemicals than the standard
toxicological assays of the 20th century). The Framework structure is sufficiently adaptable to encompass
evolving changes in Agency direction, developing needs and new or revised legislative mandates.
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Assessment Forum, http://www.epa.gov/raf/publications/framework-eco-risk-assessment.htm.
USEPA. 1992b. Guidelines for Exposure Assessment. EPA/600/Z-92/001. Washington, B.C.: Risk
Assessment Forum. http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=15263.
USEPA. 1994. Methods for Derivation of Inhalation Reference Concentrations (RfCs) and Application of
Inhalation Dosimetry. EPA/600/8-90/066F. Washington, B.C.: Office of Research and Bevelopment,
Office of Health and Environmental Assessment.
http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=71993.
USEPA. 1995a. Guidance for Risk Characterization. Washington, B.C.: Science Policy Council.
http://www.epa.gov/spc/pdfs/rcguide.pdf
USEPA. 1995b. Policy on Evaluating Health Risks to Children. Washington, B.C.: Office of the Science
Advisor, http://www.epa. gov/spc/2poleval .htm.
USEPA. 1995c. Risk Communication. Vol. 4 of Guidance for Assessing Chemical Contaminant Data for
Use in Fish Advisories. EPA/823/R-95/001. Washington, B.C.: Office of Water.
http://water.epa.gov/scitech/swguidance/fishshellfish/techguidance/upload/1999_ll_03_fish_fishvolume
4.pdf.
USEPA. 1996. Guidelines for Reproductive Toxicity Risk Assessment. EPA/63 O/R-96/009. Washington,
B.C.: Risk Assessment Forum, http://www.epa.gov/raf/publications/guidelines-reproductive-tox-risk-
assessment.htm.
USEPA. 1997a. Guidance on Cumulative Risk Assessment. Part 1. Planning and Scoping. Washington,
B.C.: Science Policy Council, http://www.epa.gov/spc/pdfs/cumrisk2.pdf
USEPA. 1997b. Guiding Principles for Monte Carlo Analysis. EPA/63 O/R-97/001. Washington, B.C.:
Risk Assessment Forum, http://www.epa.gov/raf/publications/guiding-monte-carlo-analysis.htm.
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USEPA. 1998a. Guidelines for Ecological Risk Assessment. EPA/63 0/R-95/002F. Washington, D.C.:
Risk Assessment Forum, http://www.epa.gov/raf/publications/pdfs/ECOTXTBX.PDF.
USEPA. 1998b. Guidelines for Neurotoxicity Risk Assessment. EPA/630/R-95/001F. Washington, D.C.:
Risk Assessment Forum, http://www.epa.gov/raf/publications/pdfs/NEUROTOX.PDF.
USEPA. 1999a. Guidance for Performing Aggregate Exposure and Risk Assessments. Washington, B.C.:
Office of Pesticide Programs, http://www.epa.gov/scipoly/sap/meetings/1999/february/guidance.pdf.
USEPA. 1999b. Residual Risk: Report to Congress. Research Triangle Park, NC: Office of Air Quality
Planning and Standards. EPA/453/R-99/001. http://www.epa.gov/ttn/caaa/t3/reports/risk rep.pdf.
USEPA. 2000a. Lessons Learned About Designing, Developing, and Disseminating Environmental
Information Products. EPA/260/R-00/001. Washington, B.C.: Office of Environmental Information.
http://nepis.epa.gov/Exe/ZyPURL.cgi?Bockev=P1005LPL.txt.
USEPA. 2000b. Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human
Health. EPA/822/B-00/004. Washington, B.C.: Office of Water.
http://water.epa.gov/scitech/swguidance/standards/criteria/health/methodology/index.cfm.
USEPA. 2000c. The Model Plan for Public Participation. EPA/3 00/K-OO/OO1. Washington, B.C.: Office
of Enforcement and Compliance, http://www.epa.gov/compliance/ej/resources/publications/nejac/model-
public-part-plan.pdf.
USEPA. 2000d. Risk Characterization: Science Policy Council Handbook. EPA/100/B-00/002.
Washington, B.C.: Science Policy Council, http://www.epa.gov/spc/pdfs/rchandbk.pdf.
USEPA. 2000e. Supplementary Guidance for Conducting Health Risk Assessment of Chemical Mixtures.
EPA/63O/R-00/002. Washington, B.C.: Risk Assessment Forum.
http://www.epa.gov/raf/publications/pdfs/CHEM MIX 08 2001.PBF.
USEPA. 2001a. Arsenic Rule Benefits Analysis: An SAB Review. EPA/SAB/EC-01/008. Washington,
B.C.: Science Advisory Board. http://www.epa.gov/ogwdwOOO/arsenic/pdfs/ec01008.pdf
USEPA. 200 Ib. EPA Requirements for Quality Assurance Project Plans. EPA/240/B-00/003.
Washington, B.C.: Office of Environmental Information, http://www.epa.gov/quality/qs-docs/r5-
final.pdf.
USEPA. 2001c. General Principles for Performing Aggregate Exposure and Risk Assessments.
Washington, B.C.: Office of Pesticide Programs.
http://www.epa.gov/oppfeadl/trac/science/aggregate.pdf
USEPA. 2001d. Process for Conducting Probabilistic Risk Assessment. Part A of Vol. 3 of Risk
Assessment Guidance for Superfund. EPA/540/R-02/002. Washington, B.C.: Office of Solid Waste and
Emergency Response. http://www.epa.gov/oswer/riskassessment/rags3adt/pdf/rags3adt_complete.pdf
USEPA. 2001e. Standardized Planning, Reporting, and Review of Superfund Risk Assessments. Part B of
Vol. 1 of Risk Assessment Guidance for Superfund. Washington, B.C.: Office of Emergency and
Remedial Response, http://www.epa.gov/oswer/riskassessment/ragsd/index.htm.
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USEPA. 2002a. "Case Study on Concentrated Animal Feeding Operations." In Lessons Learned on
Planning and Scoping for Environmental Risk Assessments, B1-B8. Washington, B.C.: Science Policy
Council, http://www.epa.gov/spc/pdfs/handbook.pdf.
USEPA. 2002b. Guidance for Ensuring and Maximizing the Quality, Objectivity, Utility, and Integrity of
Information Disseminated by the Environmental Protection Agency. EPA/260/R-02-008. Washington,
B.C.: Office of Environmental Information.
http://www.epa.gov/quality/informationguidelines/documents/EPA InfoQualitvGuidelines.pdf.
USEPA. 2002c. Guidance on Cumulative Risk Assessment of Pesticide Chemicals That Have a Common
Mechanism ofToxicity. Washington, B.C.: Office of Pesticide Programs.
http: //www. epa.gov/oppfead 1 /trac/science/cumulative_guidance .pdf.
USEPA. 2002d. Lessons Learned on Planning and Scoping for Environmental Risk Assessments.
Washington, B.C.: Science Policy Council Steering Committee.
http://www.epa.gov/spc/pdfs/handbook.pdf
USEPA. 2002e. "Re-registration of Pentachlorophenol." In Lessons Learned on Planning and Scoping for
Environmental Risk Assessments, C1-C15. Washington, B.C.: Science Policy Council.
http://www.epa.gov/spc/pdfs/handbook.pdf
USEPA. 2002f. A Review of the Reference Dose and Reference Concentration Processes. External
Review Draft. EPA/630/P-02/002F. Washington, B.C.: Risk Assessment Forum.
http: //www. epa. gov/raf/publications/pdfs/rfdrfcextrevdrft.pdf.
USEPA. 2002g. "Superfund Community Involvement Plans." Washington, B.C.: Superfund Community
Involvement Program, http://www.epa.gov/superfund/communitv/pdfs/toolkit/7clplans.pdf
USEPA. 2003a. Considerations in Risk Communication: A Digest of Risk Communication as a Risk
Management Tool. EPA/625/R-02/004. Cincinnati: Office of Research and Bevelopment, National Risk
Management Research Laboratory, http://www.epa.gov/nrmrl/pubs/625r02004.html.
USEPA. 2003b. Framework for Cumulative Risk Assessment. EPA/630/P-02/001F. Washington, B.C.:
Risk Assessment Forum. http://www.epa.gov/raf/publications/pdfs/frmwrk_cum_risk_assmnt.pdf
USEPA. 2003c. Framework for Implementing EPA 's Public Involvement Policy. EPA/233/F-03/001.
Washington, B.C.: Office of Policy, Economics and Innovation.
http://www.epa.gov/publicinvolvement/policy2003/framework.pdf.
USEPA. 2003d. Public Involvement Policy. EPA/233/B-03/002. Washington, B.C.: Office of Policy,
Economics and Innovation, http://www.epa.gov/publicinvolvement/pdf/policy2003.pdf
USEPA. 2004a. Ensuring Risk Reduction in Communities With Multiple Stressors: EnvironmentalJustice
and Cumulative Risks/Impacts. Washington, B.C.: National Environmental Justice Advisory Council,
Cumulative Risks/Impacts Work Group.
http://www.epa.gov/environmentaljustice/resources/publications/nejac/nejac-cum-risk-rpt-122104.pdf.
USEPA. 2004b. Facility-Specific Assessment. Vol. 2 of Air Toxics Risk Assessment Reference Library.
EPA/453/K-04/001B. Research Triangle Park, NC: Office of Air Quality Planning and Standards.
http://www.epa.gov/ttn/fera/risk atra vol2.html.
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USEPA. 2004c. "Part II. Human Health Risk Assessment: Inhalation." In Vol. 1 of Air Toxics Risk
Assessment Library, Chapter 5. Research Triangle Park, NC: Office of Air and Radiation.
http://www.epa.gov/ttn/fera/data/risk/vol_l/chapter_05.pdf
USEPA. 2004d. Registration Review Update. Washington, B.C.: Office of Pesticide Programs, Pesticide
Program Dialogue Committee. http://www.epa.gov/oppfeadl/cb/ppD.C./regisreview/regreview-
update.pdf
USEPA. 2004e. Risk Assessment Principles and Practices. EPA/ 100/B-04/001. Washington, D.C.: Office
of the Science Advisor, Risk Assessment Task Force, http://www.epa.gov/osa/pdfs/ratf-final.pdf
USEPA. 2004f Supplemental Guidance for Dermal Risk Assessment. Part E of Vol. 1 of Risk Assessment
Guidance for Superfund. EPA/540/R/99/005. Washington, D.C.: Office of Solid Waste and Emergency
Response, http://www.epa.gov/oswer/riskassessment/ragse/.
USEPA. 2004g. Technical Resource Manual. Vol. 1 of Air Toxics Risk Assessment Reference Library.
EPA/453/K-04/001A. Research Triangle Park, NC: Office of Air Quality Planning and Standards.
http://www.epa.gov/ttn/fera/risk atravol 1 .html.
USEPA. 2005a. Guidance on Selecting Age Groups for Monitoring and Assessing Childhood Exposures
to Environmental Contaminants. Final. EPA/630/P-03/003F. Washington, D.C.: Risk Assessment Forum.
http://www.epa.gov/raf/publications/guidance-on-selecting-age-groups.htm.
USEPA. 2005b. Guidelines for Carcinogen Risk Assessment. EPA/630/P-03/001B. Washington, D.C.:
Risk Assessment Forum. http://www.epa.gov/raf/publications/pdfs/CANCER_GUIDELINES_FINAL_3-
25-05.pdf.
USEPA. 2QQ5c.Mode of Carcinogenic Action for Cacodylic Acid (Dimethylarsinic Acid, DMAV) and
Recommendations for Dose Response Extrapolation: Science Issue Paper. Washington, D.C.: Office of
Pesticide Programs, Health Effects Division.
http://www.epa.gov/oppsrrdl/reregistration/cacodylic acid/dma moa.pdf
USEPA. 2005d. Superfund Community Involvement Handbook. EPA/540/K-05/003. Washington, D.C.:
Office of Solid Waste and Emergency Response.
http: //www. epa. gov/superfund/community/cag/pdfs/ci_handbook .pdf.
USEPA. 2005e. Supplemental Guidance for Assessing Susceptibility from Early-Life Exposure to
Carcinogens. EPA/630/R-03/003F. Washington, D.C.: Risk Assessment Forum.
http: //www. epa. gov/ttn/atw/childrens_supplement_final .pdf.
USEPA. 2006a. Community-Scale Assessment. Vol. 3 of Air Toxics Risk Assessment Reference Library.
EPA/452/K-06/001C. Research Triangle Park, NC: Office of Air Quality Planning and Standards.
http://www.epa.gov/ttn/fera/risk_atra_vol3.html.
USEPA. 2006b. A Framework for Assessing Health Riskof Environmental Exposures to Children. Final.
EPA/600/R-05/093F. Washington, D.C.: Office of Research and Development, National Center for
Environmental Assessment. http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=158363.
USEPA. 2006c. Guidance on Systematic Planning Using the Data Quality Objectives Process.
EPA/QA/G-4. Washington, D.C.: Office of Environmental Information, http://www.epa.gov/qualitv/qs-
docs/g4-final.pdf
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USEPA. 2006d. Guide to Considering Children's Health When Developing EPA Actions: Implementing
Executive Order 13045 and EPA 's Policy on Evaluating Health Risks to Children. Washington, B.C.:
Office of Policy, Economics and Innovation.
http://vosemite.epa.gov/ochp/ochpweb.nsf/content/ADPguide.htm/SFile/EPA ADP Guide 508.pdf
USEPA. 2006e. Peer Review Handbook. 3rd ed. EPA/100/B-06/002. Washington, D.C.: Science Policy
Council, http://www.epa.gov/peerreview/pdfs/peer_review_handbook_2006.pdf.
USEPA. 2007a. Better Decisions through Consultation and Collaboration. Washington, B.C.: Conflict
Prevention and Resolution Center. http://www.epa.gov/adr/Better Decisions.pdf
USEPA. 2007b. Human Exposure and Health Risk Assessments—Full-Scale. Vol. I. of Lead: Human
Exposure and Health Risk Assessment for Selected Case Studies. EPA/452/R-07/014a. Research Triangle
Park, NC: Office of Air Quality Planning and Standards.
http://www.epa.gov/ttn/naaqs/standards/pb/data/Pb-RA-Vol-l-073007.pdf.
USEPA. 2007c. Risk Assessment and Modeling—Air Toxics Risk Assessment Reference Library. Office of
Air and Radiation. Last modified 2007 May 22. http://www.epa.gov/ttn/fera/risk atra main.html.
USEPA. 2007d. Risk Communication in Action: The Risk Communication Workbook. EPA/625/R-05/00.
Cincinnati: Office of Research and Development, National Risk Management Research Laboratory.
http://nepis.epa.gov/Adobe/PDF/60000I2U.pdf.
USEPA. 2007e. Risk Communication in Action: The Tools of Message Mapping. EPA/625/R-06/012.
Cincinnati: Office of Research and Development, National Risk Management Research Laboratory.
http://nepis.epa.gov/Exe/ZvPURL.cgi?Dockev=60000IOS.txt.
USEPA. 2008. "Formaldehyde Emissions From Pressed Wood Products." Federal Register 73 (233):
73620-29. http://www.epa.gov/fedrgstr/EPA-TOX/2008/December/Dav-03/t28585.htm.
USEPA. 2009a. Guidance on the Development, Evaluation, and Application of Environmental Models.
EPA/100/K-09/003. Washington, D.C.: Office of the Science Advisor, Council for Regulatory
Environmental Modeling, http://www.epa.gov/crem/library/cred guidance 0309.pdf.
USEPA. 2009b. Supplemental Guidance for Inhalation Risk Assessment. Part F of Vol. 1 of Risk
Assessment Guidance for Superfiind. EPA/540/R-070/002. Washington, D.C.: Office of Superfund
Remediation and Technology Innovation, http://www.epa.gov/oswer/riskassessment/ragsf/index.htm.
USEPA. 2010a. Guidelines for Preparing Economic Analyses. EPA/240/R-10/001. Washington, D.C.:
Office of Policy, National Center for Environmental Economics.
http://vosemite.epa.gov/ee/epa/eertn.nsfyvwAN/EE-0568-50.pdf/Sfile/EE-0568-50.pdf.
USEPA. 2010b. Interim Guidance on Considering Environmental Justice During the Development of an
Action: EPA 's Action Development Process. Washington, D.C.: Office of Policy, Economics and
Innovation, http://www.epa.gov/environmentaliustice/resources/policv/considering-ej-in-rulemaking-
guide-07-2010.pdf.
USEPA. 2010c. "Proposed Significant New Use Rule for Multi-walled Carbon Nanotubes." Federal
Register 15 (22): 5546-51. http://www.regulations.gov/#!documentDetail:D=EPA-HQ-OPPT-2009-0686-
0001.
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USEPA. 2010d. Requirements for Submitting Electronic Pre-manufacture Notices (PMNs). Washington,
B.C.: Office of Chemical Safety and Pollution Prevention, Office of Pollution, Prevention and Toxics.
http: //www. epa.gov/opptintr/newchems/epmn/epmn-index.htm.
USEPA. 2010e. Quantitative Health Risk Assessmentfor Paniculate Matter. EPA/452/R-10/005.
Research Triangle Park, NC: Office of Air Quality Planning and Standards.
http://www.epa.gov/ttn/naaqs/standards/pm/data/PM_RA_FINAL_June_2010.pdf.
USEPA. 201 la. Definitions of the Most Commonly Used Public Stakeholder Involvement Terms. Office
of Strategic Environmental Management. Accessed 2011 November 11.
http://www.epa.gov/stakeholders/definit.htm.
USEPA. 201 Ib. Guidance for EPA Staff on Developing Quality Actions: EPA 's Action Development
Process. Washington, B.C.: Office of Policy.
http://vosemite.epa.gov/sab/SABPROBUCT.nsf/5088B3878A90053E8525788E005EC8B8/SFile/adp03-
00-ll.pdf.
USEPA. 201 Ic. Ecological: Planning and Scoping. Office of Solid Waste and Emergency Response.
Accessed 2011 November 11. http://www.epa.gov/oswer/riskassessment/eco_plan.htm.
USEPA. 20 lid. EPA Public Involvement. Office of Strategic Environmental Management. Accessed
2011 November 11. http://www.epa.gov/publicinvolvement/.
USEPA. 201 le. EPA 's Quality System for Environmental Data and Technology. Office of Environmental
Information. Accessed 2011 November 11. http://www.epa.gov/quality/.
USEPA. 201 If Exposure Factors Handbook. EPA/600/R-090/052F. Washington, B.C.: Office of
Research and Bevelopment, National Center for Environmental Assessment.
http://www.epa.gov/ncea/efh/pdfs/efh-complete.pdf
USEPA. 201 Ig. Highlights of the Exposure Factors Handbook. Final Report. EPA/600/R-
10/03 O.Washington, B.C.: Office of Research and Bevelopment, National Center for Environmental
Assessment. http://cfpub.epa.gov/ncea/risk/recordisplav.cfm?deid=221023.
USEPA. 201 Ih. Human Health: Planning and Scoping. Office of Solid Waste and Emergency Response.
Accessed 2011 November 11. http://www.epa.gov/oswer/riskassessment/human_health_plan.htm.
USEPA. 20 Hi. Life Cycle Assessment. Office of Research and Bevelopment, National Risk Management
Research Laboratory. Accessed 2011 November 11. http://www.epa.gov/nrmrl/std/lca/lca.html.
USEPA. 201 Ij. Multi-criteria Integrated Resource Assessment (MIRA). Region 3. Accessed 2011
November 11. http://www.epa.gov/reg3esdl/data/mira.htm.
USEPA. 201 Ik. Particulate Matter Standards—Documents From Current Review—Planning Documents.
Office of Air and Radiation. Accessed 2011 November 11.
http://www.epa.gov/ttn/naaqs/standards/pm/s_pm 2007_pd.html.
USEPA. 20111. Pesticide Program Dialogue Committee. Office of Pesticide Programs. Accessed 2011
November 11. http://www.epa.gOv/oppfeadl/cb/ppB.C./.
USEPA. 2011m. Plan EJ2014. Washington, B.C.: Office of Environmental Justice.
http://www.epa.gov/environmentaljustice/resources/policy/plan-ej-2014/plan-ej-2011-09.pdf
EPA RISK ASSESSMENT FORUM
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USEPA. 201 In. Resources for Planning New Data Collections. Office of Environmental Information.
Accessed 2011 November 11. http://www.epa.gov/quality/rnewdata.html.
USEPA. 2011o. Risk and Technology Review. Office of Air and Radiation. Accessed 2011 November 11.
http://www.epa.gov/ttn/atw/rrisk/rtrpg.html.
USEPA. 201 Ip. Risk Characterization Program. Science and Technology Policy Council. Last modified
2011 January 25. http://www.epa.gov/spc/2riskchr.htm.
USEPA. 2011q. Superfund Community Involvement. Superfund Program. Accessed 2011 November 11.
http: //www. epa.gov/superfund/community/.
USEPA. 201 Ir. Superfund Community Involvement Publications. Superfund Program. Accessed 2011
November 11. http://www.epa. gov/superfund/community/publications .htm.
USEPA. 2011s. Superfund Quality Assurance/Quality Control. Superfund Analytical Services/Contract
Laboratory Program (CLP). Accessed 2011 November 11.
http: //www. epa.gov/superfund/programs/clp/qaqc .htm.
USEPA. 201 It. Sustainability. Office of Research and Development. Accessed 2011 November 11.
http://www.epa.gov/sustainability/.
USEPA. 2012a. American Indian Environmental Office (AIEO). American Indian Environmental Office.
Accessed 2012 May 24. http://www.epa.gov/tribalportal/aieo/index.html.
USEPA. 2012b. Basic Information. Office of Environmental Justice. Accessed 2012 May 30.
http: //www. epa. gov/environmentalj ustice/basics/index.html.
USEPA. 2012c. Cacodylic Acid. Office of Pesticide Programs. Accessed 2012 May 28.
http://www.epa.gov/oppOOOO l/reregistration/cacodylic_acid/.
USEPA. 2012d. Cumulative Risk Assessment Methods and Tools. Office of Pesticide Programs. Accessed
2012 May 28. http://www.epa.gov/oppsrrdl/cumulative/methods tools.htm.
USEPA. 2012e. EPA Science Inventory. Office of Research and Development. Accessed 2012 May 24.
http ://cfpub .epa.gov/si/.
USEPA. 2012f Ethics, Regulations, and Policies. Office of the Science Advisor. Accessed 2012 May 24.
http: //www. epa.gov/phre/policy .htm.
USEPA. 2012g. Glossary. Risk Assessment. Last modified 2012 July 31.
http://www.epa.gov/riskassessment/glossary.htm.
USEPA. 2012h. Guidance & Tools. EPA. Accessed 2012 May 28.
http://www.epa.gov/risk assessment/guidance .htm.
USEPA. 2012i. National Ambient Air Quality Standards (NAAQS). Office of Air and Radiation. Accessed
2012 May 30. http://www.epa.gov/ttn/naaqs/.
USEPA. 2012J. Policy & Guidance. Office of Environmental Justice. Accessed 2012 May 24.
http://www.epa.gov/environmentaliustice/resources/policv/.
EPA RISK ASSESSMENT FORUM
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USEPA. 2012k. Process for Developing IRISHealth Assessments. Integrated Risk Information System
(IRIS). Accessed 2012 May 28. http://www.epa.gov/iris/process.htm.
USEPA. 20121. Process of Reviewing the National Ambient Air Quality Standards. Office of Air and
Radiation. Accessed 2012 May 24. http://www.epa.gov/ttn/naaqs/review.html.
USEPA. 2012m. Public Involvement Policy and Related Documents. Office of Strategic Environmental
Management. Accessed 2012 May 24. http://www.epa.gov/publicinvolvement/public/.
USEPA. 2012o. Robust Summaries and Test Plans. High Production Volume (HPV) Challenge Program.
Accessed 2012 May 28. http://www.epa.gov/hpv/pubs/summaries/viewsrch.htm.
USEPA. 2012p. Site Conceptual Model. Region 8. Accessed 2012 May 24.
http://www.epa.gov/region8/r8risk/hh scm.html.
USEPA. 2012q. Step 2—Dose-Response Assessment. EPA. Accessed 2012 May 28.
http://www.epa.gov/riskassessment/dose-response.htm.
USEPA. 2012r. Step 4—Risk Characterization. EPA. Last modified 2012 July 31.
http://www.epa.gov/risk assessment/risk-characterization.htm.
USEPA. 2012s. U.S. Environmental Protection Agency Scientific Integrity Policy. Washington, B.C.:
Office of Research and Development, http://www.epa.gov/research/htm/scientific-integrity .htm.
USEPA. 2013a. 2013 EPA TSCA Work Plan and Action Plan Risk Assessments and Data Collection
Activities. Office of Pollution Prevention and Toxics. Last modified 2013 April 22.
http://www.epa.gov/oppt/existingchemicals/pubs/2013wpractivities.html.
USEPA. 2013b. Draft Technical Guidance for Assessing Environmental Justice in Regulatory Analysis.
Washington, D.C.: Accessed 2013 August 16.
http://vosemite.epa.gOv/sab/sabproduct.nsf/0/OF7DlAOD7D15001B8525783000673AC3/SFile/EP A-HQ-
OA-2013-0320-0002ni.pdf
USEPA. 2013c. Reaffirmation of the U.S. Environmental Protection Agency's 1995 Policy of Evaluating
Health Risks to Children. Washington, D.C.: Office of the Administrator 2013 October 2013.
USEPA. 2014. Risk Assessment. EPA. Accessed 2012 May 28. http://www.epa.gov/risk/.
WHO (World Health Organization). 2008. Guidance Document on Characterizing and Communicating
Uncertainty in Exposure Assessment. Geneva: WHO.
http://www.who.int/ipcs/methods/harmonization/areas/uncertainty%20.pdf
Zartarian, V. G., J. Xue, H. A. Ozkaynak, W. Dang, G. Glen, L. Smith, and C. Stallings., 2005. A
Probabilistic Exposure Assessment for Children Who Contact CCA-Treated Playsets and Decks. Final
Report. EPA/600/X-05/. Washington D.C.: Office of Pesticide Programs.
http://www.regulations.gov/#!documentDetail:D=EPA-HQ-OPP-2003-0250-0059;oldLink=false.
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Appendix I. Examples of EPA Program-Specific Resources and Guidance on Risk
Assessment Activities
EPA Risk Assessment Portal
• A useful source of information on Agency risk assessment terms and guidance documents for
readers of this Framework is EPA's Risk Assessment Portal (USEPA 2012n).
http: //www. epa.gov/risk/
Air Toxics Program (Office of Air Quality Planning and Standards [OAQPS])
• Air Toxics Risk Assessment Reference Library. Developed for conducting air toxics analyses at
the facility- and community-scale. The library provides information on the fundamental principles
of risk-based assessment for air toxics and how to apply those principles in different settings, as
well as strategies for reducing risk at the local level.
o Volume 1: Technical Resource Manual
(http://www.epa.gov/ttn/fera/risk atravol 1 .html).
o Volume 2: Facility-Specific Assessment
(http://www.epa.gov/ttn/fera/risk_atra_vol2.html).
o Volume 3: Community-Scale Assessment
(http://www.epa.gov/ttn/fera/risk_atra_vol3.html).
• Residual Risk: Report to Congress (http://www.epa.gov/ttn/oarpg/t3/reports/risk rep.pdf).
Hazardous Waste Program (Office of Solid Waste and Emergency Response [OSWER])
• RCRA Public Participation Manual
(http://www.epa.gov/wastes/hazard/tsd/permit/pubpart/manual.htm').
National Ambient Air Quality Standards Program (NAAQS) (OAQPS)
• Process of Reviewing the National Ambient Air Quality Standards. Process for NAAQS reviews,
including the role of risk assessment (http://www.epa.gov/ttn/naaqs/review.html).
• Risk Assessment and Modeling—Criteria Air Pollutant Risk Assessment. Recent NAAQS risk
assessments (http://www.epa.gov/ttn/fera/risk criteria.html).
• National Ambient Air Quality Standards. Current documents for NAAQS reviews
(http://www.epa.gov/ttn/naaqs/).
Pesticides Program (Office of Pesticide Programs)
• Science Policy Issues and Guidance Documents (http://www.epa.gov/oppfeadl/trac/science/).
• Models and Databases (http://www.epa.gov/pesticides/science/models_db.htm).
• Public Participation Process for Registration Actions
(http://www.epa.gov/pesticides/regulating/public-participation-process.html).
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Safe Drinking Water Program (Office of Water)
• Public Access to Information & Public Involvement. Public Access Information for the Safe
Drinking Water Act (SDWA)
(http://water.epa.gov/lawsregs/guidance/sdwa/upload/2009 08 28 sdwa fs 30ann_publicinvolv
e web.pdf).
Superfund Program (OSWER)
• Superfund Risk Assessment. Risk assessment resources and guidance
(http://www.epa.gov/oswer/riskassessment/risk superfund.htm).
• Risk Assessment Guidance for Superfund: Volume 1—Human Health Evaluation Manual.
Supplement to Part A: Community Involvement in Superfund Risk Assessments
(http://www.epa.gov/oswer/riskassessment/ragsa/pdf/ci ra.pdf).
• Community Involvement Guidance and Publications. Guidance and publications for EPA's
Superfund program (http://www.epa.gov/superfund/communitv/involvement.htm).
EPA RISK ASSESSMENT FORUM
63
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