Prozac exposure found to disrupt mussel reproduction

The research, presented this week at the national meeting of the American Chemical Society*, was conducted to better understand the environmental impact of pharmaceuticals in waste water.

More and more studies are turning up evidence of common drugs and their breakdown products in the nation's waterways (see NIST Tech Beat, www.nist.gov/

public_affairs/techbeat/tb2005_1222.htm#drugs), raising concerns about potential health impacts for both humans and animals from low-level but continuous exposure to the chemicals. NIST and NCSU researchers at the Hollings Marine Laboratory (Charleston, S.C.) examined the effect of fluoxetine, a selective serotonin reuptake inhibitor (SSRI) on a native freshwater mussel (Elliptio complanata). Fluoxetine, sold under the trade name ProzacTM, is one of the most heavily prescribed antidepressants in the United States. In humans, it acts to increase the levels of serotonin at nerve synapses, relieving depression and associated illnesses. But for a number of aquatic species, serotonin moderates the reproductive system–and has been used to artificially induce spawning in bivalves.

At laboratory test concentrations, they found, fluoxetine caused female mussels carrying larvae to release them prematurely, and often, before they were viable, disrupting their reproductive cycle. Approximately 70 percent of the almost 300 species of North American freshwater mussels are considered vulnerable to extinction or already extinct.

The finding also raises questions about the effect of fluoxetine on other aquatic species that share similar endocrine mechanisms. The research team currently is gathering environmental samples from local waters and sediments to compare environmental concentrations with their findings.