The role of wildlife species in the assessment of biological impact from chronic exposure to persistent chemicals.

Assessments of chemical toxicity have regularly placed reliance upon experimental studies which employ environmentally unrealistic exposure regimes. This approach ignores the long-term low-level nature of environmental exposure which facilitates the development of factors which modify the toxicity of such chemicals. Examples of such adaptive mechanisms will be taken from the author's own studies. Factors discussed include the development of protective trace element interactions in target organs, the induction of specific metal-binding proteins, and the alteration of the distribution of chemicals at the organ and organelle level. Exposure-response investigations in wildlife are not restricted to the organism level and the impact of an environmentally released chemical upon breeding success and population dynamics can also be investigated. Disadvantages and problems associated with this kind of study, such as multiple pollutant exposure and variability in response, will also be considered.