Scientists have expressed renewed concern about antidepressants in U.S. waterways following research that shows the drugs, even at the low concentrations seen in some streams, can alter the brains and behavior of fish. According to a report in Environmental Health News (EHN), researchers at the University of Wisconsin-Milwaukee found that male minnows exposed to small doses of Prozac in laboratories ignored females and at slightly higher levels – levels still found in some wastewater – they became aggressive, killing females. The researchers also studied the antidepressant venlafaxine (Effexor). EHN stated that antidepressants are the highest-documented drugs contaminating U.S. waterways.
The EHN report said the drugs appear to exert their effects “by scrambling how genes in the fish brains are expressed, or turned on and off.” Genes, of course, are the “blueprints” that determine an organism’s observable characteristics and behavior. But just how those blueprints are followed – known as gene expression – can be altered by environmental factors. The researchers found that even minute amounts of antidepressants were disrupting the growth of neurons, causing what “appeared to be architectural changes to the young minnows’ brains.”
Concerns about antidepressants in U.S. waterways have been voiced for over a decade. In 2000, the University of Arizona’s Water Resources Research Center published an article entitled Pharmaceuticals in our Water Supplies, noting the presence of a number of psychiatric drugs in U.S. streams and rivers. In 2003, CNN reported that antidepressants in waterways were affecting frogs and fish, and in 2006, Science Daily covered findings presented at the national meeting of the American Chemical Society, where researchers expressed alarm that concentrations of Prozac found in lakes and streams had been shown to disrupt the reproductive cycle of freshwater mussels, increasing their risk of extinction.
Rebecca Klaper, a professor of freshwater sciences interviewed for the EHN story, said that the similarity of the human and fish brain structure raises questions about whether traces of antidepressants and other pharmaceuticals in drinking water might harm human health. A 2008 U.S. Geological Survey of 74 waterways used for drinking water in 25 states found 53 had one or more of three dozen pharmaceuticals. The brain effects found in the fish would also appear to fit well with known associations between the use of antidepressants by pregnant women and a number of brain-related problems in their babies, including birth defects related to the skull and brain, autism, and low Apgar scores.