One of the principal objectives of the Committee on Risk Assessment Methodology (CRAM) is to determine how risk assessment can be applied to ecological end points. The major environmental problems of the 1990s include such diverse stresses as contamination with toxic substances, overharvesting, habitat destruction, and climate change. Characteristic spatial scales for different types of stresses range from the local to the global. Yet, because priorities must be set at both the national and the local levels, consistent methods are needed for quantifying magnitudes of risks, comparing risks, and making risk-benefit tradeoffs.
A committee was established to plan a workshop on ecological risk assessment. A meeting was held in July 1990 to identify workshop objectives and develop a program. The planning committee agreed that the workshop should survey existing approaches to ecological risk assessment through discussion of specific case studies representative of the major types of environmental stresses, evaluate the applicability of the 1983 four-part risk assessment scheme to environmental assessment and regulation, and identify technical approaches and uncertainties that are common to many environmental problems.
The program began with the three keynote speakers: Terry Yosie, vice-president of the American Petroleum Institute, Mike Slimak, the deputy director of the Office of Ecological Processes and Effects Research, U.S. Environmental Protection Agency, and Warner North, a member of the committee that produced the NRC's 1983 report on human health risk assessment.
Case study presentations followed. Six case study papers were commissioned for the workshop to provide distinct examples of risk assessment problems: assessing the effects of tributyltin on Chesapeake Bay shellfish populations, testing of agricultural chemicals for effects on avian species, predicting the fate and effects of polychlorinated biphenyls (PCBs) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in aquatic ecosystems, quantifying the responses of northern spotted owl populations to habitat change, regulating species introductions, and determining the risks associated with overharvesting of the Georges Bank multispecies fishery. Each case study presentation was accompanied by comments from two discussants. The case studies were complemented by eight focused breakout sessions. Four of the breakout sessions were organized around components of the 1983 health risk assessment framework: hazard identification, dose-response assessment, exposure assessment, and risk characterization. Each of these sessions was co-chaired by an ecologist and a health risk assessment expert. The purpose of this format was to encourage interaction between the two disciplines and to investigate the applicability of the general concepts developed in the 1983 report to ecological risk assessment. The remaining four breakout sessions were organized around general risk assessment themes: modeling, uncertainty, valuation, and the role of risk assessment in the regulatory process. Dr. Thomas Lovejoy of the Smithsonian Institution was invited to give a closing presentation summarizing his views, based on attendance at the workshop, on the current status and future prospects of ecological risk assessment. Lovejoy's presentation is included in Appendix E.
Participants in the workshop included experts on the specific environmental problems covered in the case studies, representatives of federal and state agencies responsible for performing or evaluating ecological risk assessments, and experts on the technical disciplines (e.g., statistics, ecology, environmental chemistry, and resource economics) that form the scientific basis of ecological risk assessment. The case study papers, summaries of the discussions and plenary presentations, and the workshop findings are presented in this report.