|
Items in cart [4] |
Questions? Call 888-624-8373 |
| Copyright © 2009. National Academy of Sciences. All rights reserved. Terms of Use and Privacy Statement |
Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter.
Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 283
Issues in Risk Assessment
Appendix D
Opening Plenary Presentations
Terry F. Yosie Building Ecological Risk Assessment As A Policy Tool
Terry F. Yosie, vice president for health and environment of the American Petroleum Institute and former director of the Science Advisory Board, EPA, provided a broad policy view of issues related to ecological risk assessment. Dr. Yosie noted first that ecological risks have only recently been placed on the nation's policy agenda, in response to increasing public awareness of acid deposition, ozone depletion, climatic change, and other real or potential ecological problems. National and international concern for the environment will stimulate the search for methods and tools for managing ecological risks in the same way that concerns over environmental sources of cancer have stimulated the development of scientific methods and policy tools for regulating human exposure to carcinogens.
Dr. Yosie then posed six questions that must be answered as part of the development of ecological risk assessment methods.
What is ecological risk assessment?
Why is it needed?
What are the key methodological issues in using ecological risk assessment as a policy tool?
OCR for page 284
Issues in Risk Assessment
What appropriate lessons can be learned from the health risk assessment experience?
How should ecological risk assessment be applied?
What are the needs and future directions for ecological risk assessment?
On the first question, Dr. Yosie noted that previous definitions of ecological risk assessment have ranged from simple statements of principle, such as the definition proposed by the Society for Environmental Toxicology and Chemistry (SETAC, 1987),
a set of formal scientific methods for estimating the probabilities and magnitudes of undesired effects [on plants, animals, and ecosystems] resulting from the release of chemicals, other human actions, or natural catastrophes.
to elaborate schemes for tiered toxicity testing, such as the hazard evaluation procedure used by the Monsanto Corporation (Kimerle et al., 1978). He suggested that an intermediate level of complexity is needed so that the risk assessment methods are simple and accessible enough for writers, policy analysts, and journalists to use with ease, but also technical enough to be useful to scientists and be responsive to advances in science.
Dr. Yosie provided three reasons why policy makers need ecological risk assessment. First, ecological risk assessments can help policy makers correctly diagnose environmental problems before the problems become crises. As an example, he cited EPA's assessment of the health and ecological risks of stratospheric ozone depletion, which stimulated the development of an international agreement to phase out chlorinated fluorocarbons (CFCs). Second, risk assessment is needed to set priorities, as was recently done in the EPA Science Advisory Board Report Reducing Risk (EPA, 1990). Third, risk assessment is needed to delineate the link between rational choices and societal values. The debate over global climate change, for example, is ultimately a debate over the responsibility of the current generation to future generations. Risk assessment can clarify the debate by making explicit the climate change consequences of different policy proposals.
As to the methodological issues central to using ecological risk assess-
OCR for page 285
Issues in Risk Assessment
ment as a policy tool, Dr. Yosie identified the determination of baseline conditions of ecosystems as a means of assessing the need for protection from development and the estimation of the magnitude of naturally-occurring environmental change in the absence of human intervention.
Dr. Yosie noted that, despite some successes, health risk assessment had yielded few lessons in health-policy decision-making. In part, the failure reflects that it has been more difficult than anticipated to develop and apply health risk assessment methods. In addition, health risk assessments have often been colored by ideological considerations (e.g., arguments over the concept of the maximum exposed individual) or have bogged down over technical questions (e.g., the relevance of rodent data to human risk). In Dr. Yosie's view, these debates have not assisted policy-makers in making informed public health decisions, but they can and they should. There will be increased pressure from EPA, Congress, and the private sector to address broader questions. There is a danger that ecological risk assessment will follow a similarly narrow path, but there is still time to prevent this from happening.
Dr. Yosie provided two examples of how ecological risk assessment can be applied in policy making. Both government and industry, for different reasons, need ecological risk assessment as an aid in contingency planning for and response to oil spills and other kinds of accidents that have ecological impacts. The U.S. oil industry alone will spend more than $900 million over the next 5 years in improving its capability to prevent or respond to oil spills; ecological risk assessment can aid in ensuring cost effectiveness. Similarly, ecological risk assessment can contribute to implementation of total quality management, which is being adopted in many organizations; pollutant releases or obvious ecological impacts can be indicators of inefficient operation.
Finally, Dr. Yosie tried to map out the future of ecological risk assessment with a conceptual policy-triangle. One part of the triangle is ecological risk assessment, which identifies ecological problems, assesses their magnitudes, and provides a perspective on priorities. The second part of the triangle is pollution prevention, aided by the insights provided by ecological risk assessment. Ecological risk assessment and pollution prevention support the third leg, sustainable development. Sustainable development assumes a balanced approach whereby economic growth and environmental improvements proceed together to improve both living standards and the quality of human life and ecosystems.
OCR for page 286
Issues in Risk Assessment
That approach is already being adopted, as evidenced by the phaseout of CFCs, reduction of chlorine bleaching agents in the manufacture of paper products, and the Administration's recent proposal for ''debt for nature" swaps with developing nations.
In conclusion, Dr. Yosie stated that we should develop a capability for ecological risk assessment that is forward-looking and prevention-oriented, as well as backward-looking and remediation-oriented.
D. Warner North: Relationship Of Workshop To Nrc's 1983 Red Book Report
D. Warner North, a member of the committee that produced the 1983 NRC report Risk Assessment in the Federal Government: Managing the Process, provided an overview of the purpose and potential of risk assessment as portrayed in that report. Dr. North argued that the descriptions of the principles of risk assessment and the process for carrying out risk assessment in the 1983 report, which has had a substantial impact on the conduct of human health risk assessment, provide lessons and insights that apply to ecological risk assessment.
In Dr. North's view, the purpose of the 1983 committee effort was not to provide a summary of risk assessment, but to seek institutional mechanisms for carrying out risk assessment that would be effective in supporting contentious regulatory decisions. The committee found the basic problem in human health risk assessment to be incompleteness of data—a finding that clearly applies to ecological risk assessment as well. That problem is resolved, not by altering institutional arrangements for performing risk assessment, but by improving the process by which risk assessments are made.
Perhaps the most widely reproduced part of the 1983 report is its description of the elements of risk assessment and risk management. These are reproduced in the current committee report as Figure 3-1 (Chapter 3). The elements collectively provide a bridge between science and risk management, which might be more generally denoted as policy. Risk assessment can provide a consistent process for summarizing science to support regulatory decision-making by federal agencies. The process of providing the scientific basis must be consistent and flexible
OCR for page 287
Issues in Risk Assessment
before regulatory policies for managing risks can be evolved that are consistent and yet permit change based on the evolution of scientific knowledge.
Scientific knowledge is incomplete, and the multiplicity of resulting uncertainties needs to be dealt with by making choices among sets of scientifically plausible options. Rather than having those critical choices left to the discretion of individual risk assessors or the influence of risk managers, who might desire to regulate or not regulate in a specific situation on the basis of nonscientific considerations, the 1983 report suggests these choices can be made systematically with a risk assessment policy that is consistent with science and permits exceptions based on science. The report presents as its lead recommendation that
regulatory agencies should maintain a clear conceptual distinction between assessment of risks and the consideration of risk management alternatives; that is, the scientific findings and policy judgments embodied in risk assessments should be explicitly distinguished from the political, economic, and technical considerations that influence the design and choice of regulatory strategies.
The implication is that the scientific issues resulting from gaps in data and in theoretical understanding should be dealt with in a consistent and predictable way. Furthermore, the scientific issues should be carefully distinguished from nonscientific issues on which policy discretion is expected and for which the decision-maker is held responsible.
It can be argued that health risk assessment practice has gone too far in separating risk assessment and risk management. The 1983 report advocated conceptual distinction, not separation. The report states that
the importance of distinguishing between risk assessment and risk management does not imply that they should be isolated from each other; in practice they interact, and communication in both directions is desirable and should not be disrupted.
Furthermore, risk assessment must serve an assortment of functions in support of risk management, from initial screening and priority-setting exercises to major regulatory decisions with profound economic and public health consequences. Simple procedures appropriate for screen-
OCR for page 288
Issues in Risk Assessment
ing and priority-setting "may have to yield to more sophisticated and detailed scientific arguments when a substance's commercial life is at stake and the agency's decision may be challenged in court." Unfortunately, the same simple procedures used for health risk assessment in simple screening applications have often been used for risk assessment in support of major regulatory decisions as well. Rarely has the flexibility been used to bring in "more sophisticated and detailed scientific arguments" to replace the default assumptions, even though such departures are permitted under health risk assessment guidelines.
Dr. North then returned to a discussion of the four elements or steps in the risk assessment paradigm. Not all these steps are always required: a risk assessment might stop with the first step, hazard identification. The definitions of the steps can be translated from the context of health risk to the context of ecological risk quite readily:
Hazard identification. The determination of whether a particular chemical (stress agent) is or is not causally linked to particular ecological effects.
Dose-response assessment. The determination of the relation between the magnitude of exposure and the probability of occurrence of the effects in question.
Exposure assessment. The determination of the extent of exposure before or after application of regulatory controls.
Risk characterization. The description of the nature and often the magnitude of ecological risk, including attendant uncertainty.
However, the terms magnitude of exposure and extent of exposure might require replacement with a more general measure of ecological stress.
The major thrust of the 1983 report was not to recommend that risk assessment be carried out with the four steps. Rather, most of the recommendations addressed the process of summarizing the science in support of risk management. In addition to the first recommendation on the conceptual distinction between risk assessment and risk management, the report recommended that risk assessments be made publicly available as written documents in advance of regulatory decisions and that such risk assessments be subjected to peer review by scientists from outside the agency. Uniform guidelines should be developed for the use of federal agencies in the risk assessment process, and these guidelines
OCR for page 289
Issues in Risk Assessment
should be comprehensive, detailed, and flexible enough "to consider unique scientific evidence in particular instances." Finally, the 1983 report recommended establishment of a "Board on Risk Assessment Methods." Some of the suggested functions of the board are now being carried out by CRAM.
Michael Slimak: U.S. Environmental Protection Agency Activities In Ecological Risk Assessment
Michael Slimak, deputy director of EPA's Office of Ecological Processes and Effects Research, presented an overview of EPA's past and present activities in ecological risk assessment. Dr. Slimak identified five major problems that have made these assessments difficult to perform in a consistent way:
The need to consider multiple species and levels of biological organization;
The diversity and multiplicity of end points (e.g., mortality and biochemical cycling);
The simultaneous actions of multiple stressors, such as pollution and habitat loss;
The difficulty of relating ecological changes to societal values;
The multiplicity of regulatory mandates under which EPA operates.
Dr. Slimak defined ecological risk assessment as a "probabilistic statement of the 'outcome' [effects] associated with an ecological receptor being exposed to some form of stress." He then described some of the agency's approaches to assessing exposures and outcomes, focusing on two generic classifications: predictive or "bottom-up" assessments for single chemicals, as exemplified by the regulation of pesticides and toxic chemicals, and holistic or "top-down" assessments, such as assessments of wetland loss, effects of acid deposition, and global climate change. Most of EPA's attention has been devoted to predicting ecological effects of single chemicals from laboratory toxicity-test data. Although relatively elaborate guidelines and procedures have been developed for this purpose, the predictive approach has inherent weaknesses
OCR for page 290
Issues in Risk Assessment
that have long been recognized. Recently, water quality regulation has moved toward a top-down approach based on measurement of community integrity from field data.
Many of the problems facing EPA are not amenable to the predictive approach, either because they involve stresses other than toxic chemicals or because they involve direct observation of adverse ecological changes. Examples discussed by Dr. Slimak include explanation of dolphin-stranding incidents, a reported worldwide amphibian decline, and performance of ecological assessments at Superfund sites. Such studies involve difficult scientific problems. The National Acidic Precipitation Assessment Program's assessment of the relationship of sulfur dioxide deposition to aquatic resource quality (NAPAP, 1991) best demonstrates problems encountered by EPA.
For the last 5 years, EPA has been conducting an ecological risk assessment research program focused on developing better predictive models for single-chemical assessments. A major new initiative, the Environmental Monitoring and Assessment Program (EMAP), will attempt to measure ecosystem quality on regional and national scales through a nationwide monitoring program. The results will be used to determine the success of EPA's regulatory programs and to support future risk assessments.
The EPA Risk Assessment Forum has initiated the development of guidelines for ecological risk assessment analogous to the existing guidelines for health risk assessment. A series of risk assessment colloquia was held during 1990. The proceedings were summarized and published in early 1991 in a report entitled Issues in Ecological Risk Assessment . A "framework document," intended to provide the conceptual basis for detailed guidelines, is now being reviewed (EPA, 1992a). A strategy for subject-specific guidelines structured around ecosystem types, levels of biological organization, end points, and stressors is being developed simultaneously. Case studies illustrating current practice are being developed and a report containing case studies will be announced in the Federal Register (EPA, 1992b).
Dr. Slimak closed his presentation by raising issues for consideration at the CRAM workshop:
The amenability of ecological risk assessments to biostatistical treatment;
End point identification and selection;
OCR for page 291
Issues in Risk Assessment
Ecological values;
The relationship of the 1983 paradigm to regulatory processes;
The relationship between risk assessment and risk management.
OCR for page 292
Issues in Risk Assessment
This page in the original is blank.
Representative terms from entire chapter:
health risk
