Individual and Mixture Effects of Selected Pharmaceuticals and Personal Care Products on the Marine Phytoplankton Species Dunaliella tertiolecta

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Pharmaceuticals and personal care products (PPCPs) entering the environment may have detrimental effects on aquatic organisms. Simvastatin, clofibric acid, diclofenac, carbamazepine, fluoxetine, and triclosan represent some of the most commonly used and/or detected PPCPs in aquatic environments. This study analyzed the individual and mixture toxicity of these six PPCPs to the marine phytoplankton species Dunaliella tertiolecta using a standard 96-hour static algal bioassay protocol. All PPCPs tested had a significant effect on D. tertiolecta population cell density. However, of the six PPCPs tested, only triclosan yielded toxicity at typical environmental concentrations. The 96-hour EC(50) values for triclosan, fluoxetine, simvastatin, diclofenac, and clofibric acid were 3.55 microg/L, 169.81 microg/L, 22,800 microg/L, 185,690 microg/L, and 224,180 microg/L, respectively. An EC(50) value could not be determined for carbamazepine; however, the highest concentration tested (80,000 microg/L) reduced cell density by 42%. Both mixtures tested-simvastatin-clofibric acid and fluoxetine-triclosan-demonstrated additive toxicity. The presence of PPCP mixtures may decrease the toxicity threshold for phytoplankton populations. Detrimental effects on phytoplankton populations could ultimately impact nutrient cycling and food availability to higher trophic levels. The results of this study are a first step toward identifying the risk of PPCPs to estuarine organisms and may benefit environmental resource managers.