Embryonic development assay with Daphnia magna: application to toxicity ofchlorophenols

Cladoceran embryos, derived from Daphnia magna, were used for the developme ntal toxicity assay system of chlorophenols (CPs) and the quantitative stru cture-activity relationships (QSAR) studies. As the toxicity end point, the median effective concentration (EC50s) to reduce hatchability was estimate d. The EG50s for embryo hatchabilities were found to be significantly corre lated to acute immobilization toxicity (24-h EC50s) with juveniles, and the embryo assay appeared to be more sensitive to CPs with higher water solubi lity than the juveniles assay. The EC50s for embryos were correlated with s ix physicochemical parameters, and the Pow (n-octanol/water partition coeff icient) gave a good correlation in simple linear regression analysis, as is frequently stated in toxicity studies with aquatic organisms. These result s suggest that in vitro hatchability assay using D. magna embryos are usefu l for ecotoxicity screening of aquatic pollutants.