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A TIERED APPROACH TO WILDLIFE RISK ASSESSMENT
Citation:
Munns Jr., W R., C. Baker, M. Bradburn, T R. Gleason, T. M. Henry, S S. Heppell, N H. Schumaker, AND A S. Trebitz. A TIERED APPROACH TO WILDLIFE RISK ASSESSMENT. Presented at Society of Risk Analysis Conference, Atlanta GA, December 5-8, 1999.
Description:
Populations of several wildlife species are experiencing increased pressure from human-induced changes in landscape pattern, habitat quality, and toxic chemical exposure in the environment. Governmental agencies such as the U.S. Environmental Protection Agency (U.S. EPA) are required to assess risks to wildlife populations that result from these stressors, yet considerable uncertainty exists with respect to how such assessments should be conducted. This uncertainty is compounded by questions concerning appropriate spatial scales of analysis, extrapolation of response data among species and from individuals to populations, use of limited data sets, and interactions among stressors as they affect wildlife populations. To address these questions and improve methods for wildlife risk assessments, the U.S. EPA's National Health and Environmental Effects Research Laboratory is implementing a research strategy that involves development and evaluation of extrapolation methods and spatially- explicit population models to be used in a tiered risk assessment approach. Conceptually, the tiered approach consists of a series of complete ecological risk assessments arrayed from most general and broadly-based (screening level) to most realistic, accurate, and situation-specific (definitive level). Tiers in the array vary in the types of models used, the quality and quantity of data required, and the nature of risk conclusions developed. Reflective of the trend from general to specific should be a narrowing of the bounds of uncertainty around estimates of risk to the wildlife population. Decisions to move from one tier to the next depend in part upon the level of uncertainty acceptable in the estimate of risk and the feasibility of data collection required by the next tier. Our group is identifying and developing tools and methods appropriate for screening through definitive level assessments. The utility of these methods and the value of the overall approach will be demonstrated in future terrestrial and aquatic case studies.