A comparison of the chronic effects of human pharmaceuticals on two cladocerans, Daphnia magna and Ceriodaphnia dubia.

Scientific researchers and regulators are focusing attention on trace quantities of pharmaceuticals in wastewater effluents and surface waters, resulting in an increased level of concern regarding the potential environmental impact of these compounds. The current European regulatory guideline requires evaluation of the chronic effects of active pharmaceutical ingredients on Daphniamagna. Based on the life cycle of D. magna, chronic studies to establish survival and reproductive endpoints require a 21 d exposure period. A similar organism, Ceriodaphniadubia, has a shorter life cycle and therefore survival and reproductive endpoints may be established following 7d of exposure. No observed effect concentrations and lowest observed effect concentrations for survival and reproduction were obtained for D. magna and C. dubia following exposure to six human pharmaceuticals and two metabolites (i.e. celecoxib, linezolid, varenicline, sunitinib, Compound A, ziprasidone and the M1 and M4 metabolites of torcetrapib). These data were evaluated to determine whether one organism may be considered more sensitive. Survival and reproduction data obtained from the C. dubia study provide similar outcomes to D. magna when determining the predicted environmental concentration/predicted no effect concentration (PEC/PNEC) ratios for surface water. Based on these data, C. dubia may be used as a cost-effective alternative and representative invertebrate species when assessing the potential risk of human pharmaceuticals.