Waterborne and sediment toxicity of fluoxetine to select organisms

Ecological risk assessments of pharmaceuticals are currently difficult because little-to-no aquatic hazard and exposure information exists in the peer-reviewed literature for most therapeutics. Recently several studies have identified fluoxetine, a widely prescribed antidepressant, in municipal effluents. To evaluate the potential aquatic toxicity of fluoxetine, single species laboratory toxicity tests were performed to assess hazard to aquatic biota. Average LC50 values for Ceriodaphnia dubia, Daphnia magna, and Pimephales promelas were 0.756 (234 μg/l), 2.65 (820 μg/l), and 2.28 μM (705 μg/l), respectively. Pseudokirchneriella subcapitata growth and C. dubia fecundity were decreased by 0.044 (14 μg/l) and 0.72 μM (223 μg/l) fluoxetine treatments, respectively. Oryias latipes survival was not affected by fluoxteine exposure up to a concentration of 28.9 μM (8.9 mg/l). An LC50 of 15.2 mg/kg was estimated for Chironomus tentans. Hyalella azteca survival was not affected up to 43 mg/kg fluoxetine sediment exposure. Growth lowest observed effect concentrations for C. tentans and H. azteca were 1.3 and 5.6 mg/kg, respectively. Our findings indicate that lowest measured fluoxetine effect levels are an order of magnitude higher than highest reported municipal effluent concentrations.