Are there drugs circulating in your local lake? An article in Stormwater a couple of years back looked at the question of pharmaceutical products in surface waters. Some of them come from discharge from wastewater treatment plants, which are not designed to filter out all these products; another potential source is drugs that people dispose of in the trash. Although their presence in measurable—though usually very small—quantities is disturbing, it has been unclear exactly what effect, if any, they might be having on the environment—until now.
A recent Time magazine article reports on a study in Sweden in which researchers looked at the effects of medications on perch downstream of a wastewater treatment plant. As the article points out, the usual toxicity tests don’t really apply in such cases, because many drugs don’t actually kill fish or other animals. Some, however, can alter their behavior.
The Swedish study found traces of the anti-anxiety drug oxazepam in the river downstream of the treatment plant and also—in higher concentrations—in the tissue of fish living in the river, which would indicate bioaccumulation. Researchers then studied the effects of the drug on fish behavior, exposing different groups of fish to clean water, water with the same concentration of the drug found in the river, and water with a much higher concentration. The article describes the tests and the results in detail, but the upshot is that, after a weeklong exposure to the anti-anxiety drug, the fish became “bolder”—avoiding other fish and venturing into unknown situations more than a typical perch would do. As one of the researchers points out, “That’s bad, if you’re a little schooling fish.”
Whether studies such as these will eventually lead to new regulations or to a push for new kinds of filtering technologies is still an open question.