Analysis of the ecetoc aquatic toxicity (EAT) database V — The relevance of Daphnia magna as a representative test species

The ECETOC Aquatic Toxicity database was used to investigate the response of the Cladoceran Daphnia magna Straus in various types of toxicity test and to compare its sensitivity with that of other invertebrates and fish. Repeatability of 48-h EC50 data was good, the range being no more than a factor of 3 for eight of the eleven chemicals where multiple results were available. In 21-day tests, for both EC50 and NOEC, reproduction was a more sensitive endpoint than growth or lethality, but not markedly so. There was no general rule that D. magna was more, or less, sensitive than other invertebrates, including D. pulex. Lindane and Endosulphan were more toxic to fish than to Daphnia but the reverse was the case for Parathion, copper, a cationic surfactant and to a lesser extent cadmium. For another eight substances 48-hour tests with Daphnia would have predicted the 96-h EC50 to freshwater fish within a factor of 5 or less. The same was true for long-term studies with Daphnia and fish: there was no consistent difference in sensitivity (except that Daphnia was always more sensitive to metals) and the crustacean could be used to predict long-term toxicity to fish within a factor of 2 for half the non-metals and a factor of 5 for three-quarters of non-metals.