Ecological risk assessment was not included in the Commission's legislative mandate, but we would be remiss if, in a report on the use of risk assessment in regulatory programs, we considered only human health. Indeed, protection of human health and protection of the environment are often dual goals of the laws and regulations that use risk assessment to inform decision-making. The ability to sustain our ecosystems is crucial to our well-being, as they are used for producing food, forests, or fiber, or for recreation and pleasure in the out-of-doors.

FINDING 3.5: There have been a number of attempts to develop a uniform ecological risk assessment approach. EPA's framework for evaluating ecological risk (figure 3.1) has emerged as a useful way to organize many kinds of information about risks to the environment, although it does not yet include an explicit role for stakeholders. Guidance for implementation of the EPA framework is needed.

RECOMMENDATION: EPA and other agencies should continue together to implement EPA's ecological risk assessment framework. EPA and other agencies should develop clear guidance for putting various problems into context, choosing methods and tools for characterizing exposure and effects, characterizing uncertainty, and applying weight-of-evidence evaluations. For consistency with the Commission's risk-management framework, the critical addition of stakeholder involvement should be highlighted, starting with the problem-formulation stage.

RATIONALE

Ecological risk assessment has been used informally for many years to make decisions about resource management and pollution control. Within the last few years, a concerted effort has been made to define ecological risk assessment and to establish a common language for discussing approaches and results. At the same time, ecological risk assessments have been conducted by an increasing number of agencies, such as the Department of the Interior, the Department of Agriculture, and the National Marine Fisheries Service. As detailed in the Menzie-Cura report prepared for the Commission (see appendix A.5 for abstract), there is a growing consensus that the EPA ecological risk-assessment framework (EPA1992b), as it has evolved since 1992, can fulfill a wide range of needs, from providing information on environmental pollution to informing resource management and regulatory decision-making. Each agency should develop guidance on the use of the framework appropriate to its needs.

Compared with the framework for human-health risk assessment (NRC 1983), the EPA framework for ecological risk assessment changes the first step from hazard identification to problem identification in a holistic context. In the problem-formulation stage, the environmental values to be protected and the goals of the assessment should be defined. In addition, the appropriate level of ecological organization (such as individual species, population, or community), the end points or potential receptors of stress, and the ways to measure the end points must be identified. Thus, this approach is consistent with the Commission's proposed framework for risk management.

Ecological risk assessment has no commonly accepted starting point. For example, some might focus on the need to maintain biological diversity, others might be drawn to protecting particular plants or animals, and still others might relate to aesthetic quality. Balancing those disparate goals is the challenge of the problem-formulation stage. The likelihood of success will be increased by including stakeholders in the process at this early stage. Figure 3.1 reflects the Commission's proposal to add stakeholders, explicitly, to the participants in the problem-formulation stage of EPA's framework. Many small or well-defined assessments can be parts of established regulatory programs in which it might not be practical to involve stakeholders in every case. However, stakeholder involvement certainly should be considered for larger local or regional assessments in which affected parties hold a range of interests and values.

In a review of ecological risk-assessment case studies (EPA 1993), EPA concluded that the strengths and weaknesses of the studies seemed to originate, in large part, from decisions made during the problem-formulation stage. However, there is very little guidance on how this process should occur and who should be involved in it. The addition of stakeholders in this stage requires guidance from EPA on which parties to include and when and how to include them.

In particular, it is important to identify federal, state, and local agency stakeholders with responsibilities for the resources being analyzed.

The collaboration that we recommend among risk assessors, risk managers, and stakeholders provides opportunities to bridge gaps in understanding, language systems, and values. If the affected parties do not participate in the early decisions about goals, end points, and measurements, the analysis is likely to fail to provide information useful for decision-making. Consideration of economic and legal issues will also be facilitated by the early inclusion of stakeholders. Stakeholder involvement in the problem formulation stage of an ecological risk assessment has been endorsed by a range of organizations, including the Environmental Defense Fund, the American Industrial Health Council, the Risk Science Institute, the State of California, and Environment Canada.

The analysis stage of ecological risk assessment consists of two distinct, interrelated activities, characterization of exposure and characterization of ecological effects. During exposure characterization, the spatial and temporal distribution of a stressor or stressors and contact with ecological components are predicted or measured. During effects characterization, the adverse effects elicited by stressors and the cause-effect relationships are evaluated. Additional research is needed into the effects of multiple chemical, physical, and biological stressors and the appropriate metrics to assess effects. An important diagnostic tool for identifying effects is the index of biotic integrity developed by Karr (1991), who testified before the Commission in Seattle. Although not a perfect tool, the index of biotic integrity is in use by more than 30 states in their water-quality programs. Guidance is needed on when to use it and other tools of varied complexity, such as fate and transport models, toxicity tests, and field studies for a given problem. In its 1996 report Ecological Risk Assessment: Sound Science Makes Good Business Sense, the American Industrial Health Council suggests that addressing multiple species and multiple exposure pathways at different levels of ecosystem organization is best done with an iterative, tiered approach to data acquisition. The Commission agrees. Because ecological risk assessments can be data intensive, guidance on when to conduct a tiered, iterative approach is needed. The intensity of data collection should be commensurate with the environmental benefits of greater certainty and the needs of stakeholders involved in the decision-making process.

Finally, in the risk-characterization stage, characterizations of exposure and of ecological effects are integrated to evaluate the likelihood that exposures and adverse ecological effects will be associated with specific stressors. Risk characterization for ecological risk assessment has been subject to little standardization. For example, there are many sources of uncertainty in ecological risk assessment. Guidance in the use of qualitative and quantitative descriptions of uncertainty is needed. The strengths and weaknesses of the analyses must be described, together with the assumptions and uncertainties. Explicit directions and examples could greatly improve the conduct of risk characterization in ecological risk assessment.

In some cases, risk characterization is presented simply as a restatement of test results. In other cases, it is viewed as the final stage of a weight-of-evidence evaluation, a process of evaluating the underlying data and studies for accuracy, reliability, and relevance. There is no consensus on how to evaluate the weight-of-evidence in the context of ecological risk assessment or how it should be applied. The approach reflects one person's professional judgment, and the conclusions might not be transparent to others. The professional judgments that underpin weight-of-evidence evaluations should be examined and be made more explicit. Guidance in conducting both quantitative and qualitative weight-of-evidence evaluations should then be developed. The risk characterization must synthesize and provide information that can be applied to risk-management decisions, again with extensive consultation with stakeholders (figure 3.1).

The EPA ecological risk-assessment framework has been most successful in analyzing risks associated with chemical stressors--the scenario most similar to typical human-health risk assessments. However, the framework is being used with greater frequency for more complex problems. For example, EPA's Office of Water has experimented with changing the sequence of some of the components of the framework and has developed conceptual models at multiple organizational levels of the ecosystem; this version of ecological risk assessment is being used to assist in understanding stressors and their effects on watershed ecosystems (see section 6.1.3). In addition, the recently formed Office of Sustainable Ecosystems and Communities is leading an effort to focus on ecological risk assessment beyond toxic effects to individual organisms rather a system approach that examines the food web or the broader landscape. Another appropriate use of EPA's ecological risk-assessment framework would be in analyzing the impact on wildlife of chemicals that may disrupt endocrine functions.

The ecological risk-assessment framework must be refined as agencies gain experience with its application to include biological, physical, and social stressors if it is to assist in addressing such important problems as protecting biological diversity, maintaining ecosystem health, and guiding sustainable development. It is timely to work with the international community to harmonize methods while the development of the paradigm is still in its infancy in the United States and abroad. As the Organization for Economic Cooperation and Development noted in its report Environmental Performance Review of the United States, "knowledge about the conditions and trends of biodiversity in the U.S. is limited" (OECD 1996). Measurement tools, models, field studies, and surveillance of the consequences of risk-management decisions are critically needed.