Embryonic development assay with Daphnia magna:: application to toxicity of chlorophenols

Cladoceran embryos, derived from Daphnia magna, were used for the developmental toxicity assay system of chlorophenols (CPs) and the quantitative structure-activity relationships (QSAR) studies. As the toxicity end point, the median effective concentration (EC50s) to reduce hatchability was estimated. The EG50s for embryo hatchabilities were found to be significantly correlated to acute immobilization toxicity (24-h EC50s) with juveniles, and the embryo assay appeared to be more sensitive to CPs with higher water solubility than the juveniles assay. The EC50s for embryos were correlated with six physicochemical parameters, and the Pow (n-octanol/water partition coefficient) gave a good correlation in simple linear regression analysis, as is frequently stated in toxicity studies with aquatic organisms. These results suggest that in vitro hatchability assay using D. magna embryos are useful for ecotoxicity screening of aquatic pollutants.