[Medium-term Daphnia test. Evaluation of the toxicity of various trace metals in the presence of humic acids].

Toxicity of copper, cadmium and zinc complexed by the EDTA and HPO4(2)- ligands has recently been studied by the use of the short-term daphnia test. In order to detect the toxicity due to very small quantities of metals present in water in free ionic state or in complexed species formed with humic matters, a medium term test on Daphnia magna has been developed for a better appreciation of lethal and sublethal effects. Collected data are statistically analysed with the use, for instance, of "Lowest Rejected Concentration Tested" previously proposed by Skalski. The test defined in our laboratory allows to point out cadmium concentrations as small as 5 micrograms.l-1.