Ecotoxicology : An Opportunity for the Experimental Sciences

The primary purpose of ecotoxicology is to provide a means of predicting the probability of harm from the use of chemicals or other environmental stressors (e.g., heat or suspended solids) upon complex natural systems. Although this statement may appear platitudinous, an examination of toxicological literature involving non-human species shows an inordinate preoccupation with studies of dose-response curves at the single species level of biological organization and relatively few studies dealing with properties at higher levels of biological organization such as natural communities and ecosystems. Detractors of the attempts to incorporate ecological principles into the field of environmental toxicology to a degree sufficient to justify the term “ecotoxicology” often categorize such attempts as impractical. However, the field of ecotoxicology will not reach maturity until it involves toxicity tests at different levels of biological organization using end points or parameters characteristic of these levels and the results of laboratory tests are validated in a scientifically justifiable way in the natural systems that the tests are presumably designed to protect. This manuscript explores the present situation with regard to the major components of the hazard evaluation process in ecotoxicology– (1) screening or range-finding tests, (2) predictive toxicity tests, (3) validating or confirming tests, and (4) monitoring. A clear tendency in the literature in recent years has been to incorporate a higher degree of environmental realism into laboratory ecotoxicological tests and to be concerned in principle, if rarely in practice, about the validation or confirmation of the predictions made on these tests. However, it is abundantly clear that of the four components just mentioned the first two have received inordinate attention (particularly at the single species level) while the latter two have received relatively little attention. In order for the field of ecotoxicology to develop properly, a balance must be reached in both research activities and practical application of all four components of the ecotoxicological hazard evaluation process.