Ecosystem health. II. Quantifying and predicting ecosystem effects of toxic chemicals: can mammalian testing be used for lab-to-field and field-to-lab extrapolations?

An understanding of the "health" of an ecosystem after exposure to toxic chemicals can be achieved through studies which concentrate on the description of effects on ecosystem homeostasis, identification of disruption, and determination of pathways between these. Studies using native mammals to determine effects of toxicants on terrestrial ecosystems must be designed so that they identify the populations at risk, select appropriate biological effect endpoints, and obtain appropriate numbers and types of samples and contextual ecological data. Accompanying laboratory studies are often needed to complement or confirm observations from the field. Although aquatic biologists routinely use about 10 selected native species for toxicological work, terrestrial biologists seem to prefer using laboratory mammals in "ecotoxicological" studies. Some have advocated using only laboratory rodents in a field setting, while others have suggested using both laboratory mammals and native species. We take the position that there are considerable limitations in the use of laboratory rodents in toxicological studies which purport to be meaningful with regard to prediction of toxicant-induced effects on ecological systems. Nevertheless, we are able to suggest an integrated plan that includes the systematic monitoring of native species in conjunction with laboratory animals exposed in the laboratory and in the field.