T. J. Norberg-King C.G. Ingersoll D.A. Benoit G.T. Ankley P. V. Winger J. Kubitz J.M. Lazorchak M.E. Smith E. Greer F.J. Dwyer D.J. Call K.E. Day P. Kennedy M. Stinson G.A. Burton Jr. 1996 <p><span>Standard 10-d whole-sediment toxicity test methods have recently been developed by the U.S. Environmental Protection Agency (EPA) for the amphipod </span><i>Hyalella azteca</i><span> and the midge </span><i>Chironomus tentans</i><span>. An interlaboratory evaluation of method precision was performed using a group of seven to 10 laboratories, representing government, academia, and environmental consulting firms. The test methods followed the EPA protocols for 4-d water-only reference toxicant (KCl) testing (static exposure) and for 10-d whole-sediment testing. Test sediments included control sediment, two copper-containing sediments, and a sediment contaminated primarily with polycyclic aromatic hydrocarbons. Reference toxicant tests resulted in </span><i>H. azteca</i><span> and </span><i>C. tentans</i><span> median lethal concentration (LC50) values with coefficents of variation (CVs) of 15.8 and 19.6%, respectively. Whole sediments which were moderately contaminated provided the best estimates of precision using CVs. </span><i>Hyalella azteca</i><span> and </span><i>C. tentans</i><span> tests in moderately contaminated sediments exhibited LC50 CVs of 38.9 and 13.5%, respectively. The CV for </span><i>C. tentans</i><span> growth was 31.9%. Only 3% (1 of 28) of samples exceeded acceptable interlaboratory precision limits for the </span><i>H. azteca</i><span> survival tests. No samples exceeded the intralaboratory precision limit for </span><i>H. azteca</i><span> or </span><i>C. tentans</i><span> survival tests. However, intralaboratory variability limits for </span><i>C. tentans</i><span> growth were exceeded by 80 and 100% of the laboratories for a moderately toxic and control sample, respectively. Interlaboratory variability limits for </span><i>C. tentans</i><span> survival were not exceeded by any laboratory. The results showed these test methods to have relatively low variance and acceptable levels of precision in interlaboratory comparisons.</span></p> application/pdf 10.1002/etc.5620150812 en Wiley Interlaboratory study of precision: Hyalella azteca and Chironomus tentans freshwater sediment toxicity assays article