Effects of Toxicants on Aquatic Populations

In the United States, the Environmental Protection Agency regulates chemicals under several legislative acts, two of which are the Toxic Substances Control Act (TSCA) and the Federal Insecticides, Fungicides, and Rodenticides Act (FIFRA). The Agency regulates chemicals under these acts using, in part, the assessment of risks both to humans and to the environment. A scientifically based methodology of high utility to assist in evaluating environmental risk posed by the introduction of chemicals is currently under development. The purpose of this article is to provide indications of past developments, of current theoretical research, and of directions of environmental risk assessment of chemical stress on populations. Fate and effects at the community and ecosystem level are, at this stage, only speculative.