Ref ID : 4573
Sean M. Richards, Christian J. Wilson, David J. Johnson, Dawn M. Castle, Monica Lam, Scott A. Mabury, Paul K. Sibley, and Keith R. Solomon; Effects of Pharmaceutical Mixtures in Aquatic Microcosms. Environmental Toxicology & Chemistry 23(4):1035-1042, 2004
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Pharmaceuticals have a wide range of biological properties and are released into the environment in relatively large amounts, yet little information is available regarding their effects or potential ecological risks. We exposed outdoor aquatic microcosms to combinations of ibuprofen (a nonsteroidal anti-inflammatory drug), fluoxetine (a selective serotonin reuptake inhibitor), and ciprofloxacin (a DNA gyrase-inhibiting antibiotic) at concentrations of 6, 10, and 10 µg/L, respectively (low treatment [LT]); 60, 100, and 100 µg/L, respectively (medium treatment [MT]); and 600, 1,000 and 1,000 µg/L, respectively (high treatment [HT]). We maintained these concentrations for 35 days. Few response were observed in the LT; however, effects were observed in the MT and HT. Fish mortality occurred in the MT (<35 days) and in the HT (<4 days). Phytoplankton increased in abundance and decreased in diversity (number of taxa) in the HT, with consistent trends being observed in the MT and LT. Zooplankton also showed increased abundance and decrease in diversity in the HT, with consistent trends being observed in the MT. Multivariate analyses for zooplankton and phytoplankton suggested interactions between these communities. Lemna gibba and Myriophyllum spp. showed mortality in the HT; growth of L. gibba was also reduced in the MT. Bacterial abundance did not change in the HT. All responses were observed at concentrations well below the equivalent pharmacologically active concentrations in mammals. Although the present data do not suggest that ibuprofen, fluoxetine, and ciprofloxacin are individually causing adverse effects in surface-water environments, questions remain about additive response from mixtures.