Uptake and depuration of pharmaceuticals in reclaimed water by mosquito fish (Gambusia holbrooki): a worst-case, multiple-exposure scenario.

Previous studies showed that caffeine, diphenhydramine, and carbamazepine were bioconcentrated by mosquito fish (Gambusia holbrooki) from freshwater bodies directly affected by reclaimed water. To understand the uptake, depuration, and bioconcentration factors (BCFs) under the worst-case conditions, the authors exposed 84 mosquito fish to reclaimed water under static renewal for 7 d, followed by a 14-d depuration phase in clean water. Characterization of the exposure media revealed the presence of 26 pharmaceuticals, whereas only 5 pharmaceuticals-caffeine, diphenhydramine, diltiazem, carbamazepine, and ibuprofen-were present in the organisms after only 5 h of exposure. Caffeine, diltiazem, and carbamazepine were quickly taken up by mosquito fish following a similar uptake curve. Diphenhydramine and ibuprofen, on the other hand, were more gradually taken up by mosquito fish but were also eliminated fairly quickly, resulting in the 2 shortest depuration half-lives at 34 h and 32 h, respectively. For comparison, BCFs based on rate constants (BCFb ), steady-state concentrations (BCFa ), and saturation-state concentrations (BCFc ) were calculated. Values of BCFb ranged from 0.23 to 29 and increased in the order of caffeine < carbamazepine < diltiazem < diphenhydramine < ibuprofen. Values of BCFa and BCFc ranged from 2.0 to 28 and increased in the order of carbamazepine < caffeine < diltiazem < diphenhydramine < ibuprofen. This is the first study using a nonartificial exposure-treated wastewater matrix to generate pharmacokinetic data for pharmaceutical mixtures in aquatic organisms. Environ Toxicol Chem 2013;32:1752-1758. © 2013 SETAC.