Research Product

Under the Federal Insecticide, Fungicide and Rodenticide Act, the Toxic Substances Control Act and the Clean Water Act, the U.S. Environmental Protection Agency (EPA) is charged with determining if the manufacture, use, or disposal of a chemical will present an unreasonable risk of harm to the environment. Typically, management decisions are based on protecting populations of organisms. However, the Endangered Species Act requires that, in some cases, managers must estimate the take of individuals to determine if the loss of individuals might adversely affect a population of an endangered or threatened (listed) species. The most direct assessment would be to determine the sensitivity of a listed species to a particular contaminant or perturbation. However, this direct approach would be time consuming and expensive because it might require development of organism culturing and handling procedures, some species may not be amenable to culture, there might be multiple species to be considered, and would be contaminant specific. The data we have generated indicates that in 96-h acute toxicity tests, if rainbow trout is used as a test species, a species typically used in pesticide registration or water quality criteria derivation, those procedures which protect the rainbow trout would likely be protective of most listed aquatic fish species. If a safety factor is needed to estimate 96-h LC50s for listed fish species, our data indicates that 0.5 would be a conservative estimator. Also, if EPA water quality criteria are recalculated by eliminating certain species from the data set, such as rainbow trout, then listed fish species might not be adequately protected.