ABSTRACT
Laboratory toxicity tests are particularly useful for evaluating candidate causes that can be acutely toxic or are present at high concentrations. This chapter provides a brief review of several types and applications of laboratory experiments useful for causal assessment, including standard toxicity tests, species sensitivity distributions, environmental media quality assessments, toxic identification evaluations, and laboratory microcosm approaches. The toxicity tests conducted for the Northern Rivers Basins Study helped link effects observed in the field to the causative agent, nutrients in the pulp mill effluent. Standard whole effluent toxicity tests were developed beginning in the 1970s and subsequently the testing of complex materials was extended to contaminated ambient waters and sediments. The use of laboratory testing in helping to establish causal relationships could be strengthened by conducting tests that include species that are representative of the affected organisms and which incorporate any affected functions as endpoints.
