Research Product

Environmental Protection Agency's Office of Pesticide and Toxic Substance (OPTS) is required by law to supply industry with recommended test standards to determine the toxicity of new chemicals. One proposed series of test standards is the acute toxicity test, flow-through and static, using estuarine animals. In proposing a test standard, OPTS requires knowledge of the precision of the data generated in these tests i.e., The expected variability in test results, given the same standard, test chemical and test species. This final report summarizes the results of static and flow-through toxicity tests conducted by six laboratories using the chemicals endosulfan and silver nitrate. Saltwater species tested were the copepod, Acartia tonsa, the mysid shrimp, Mysidopsis bahia and the sheepshead minnow, Cyprinodon variegatus. Results of the M. bahia and C. variegatus tests indicated that the mean ratio of the highest LC50 to the lowest LC50 generated for each chemical and test type was 4.0 (i.e. the greatest variability in the LC50 values expected was a factor of 4.0). Results of A. tonsa studies were not conclusive because different practices were used in the culture, age selection and testing of the species by the participating laboratories.