Scientists: Medications in water affecting fish behavior

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We’ve written before about the dangers of flushing medications down the toilet: A host of pharmaceuticals such as antibiotics, anticonvulsants and hormones have been found in the drinking water supplies of millions of Americans. And while some of these findings are surely the result of unwanted medications that had been flushed, experts are also aware that many of the medications we take aren’t completely absorbed by our bodies, ending up in sewer systems.

A study that appears in Science magazine  gives even more weight to these concerns. Scientists in southern Sweden found that fish living near a sewage treatment plant have low levels of psychoactive drugs — benzodiazepines — in their systems. Further study has scientists speculating that these anti-anxiety drugs are having an effect on the behavior of the fish. When they placed normal perch in a fish tank and added the same levels of the drugs, the fish started eating more aggressively and became more active, but also more antisocial.

In an interview with National Public Radio, environmental scientist Jonatan Klaminder says the drug “removes some of the fear, the sense of fear, from these fishes. So instead of being afraid they focus on feeding.” The implication is that in the wild, smaller fish may become more vulnerable to predation by larger fish, because they’ll lose their sense of caution.

NPR’s article goes on to quote Bryan Brooks, professor of environmental science and biomedical studies at Baylor University in Waco, Texas, who says that in most cases, pharmaceuticals in the water are at much lower concentrations than “what you might need to gain a therapeutic dose.” In other words, he’s saying there’s no discernible threat to people who might eat those fish or drink the water. In developing countries, however, Brooks says it’s a different story because levels of pharmaceuticals in the water there are much higher.

Clearly, more study is needed. In the meantime, we can all do our best to keep pharmaceuticals out of the water by following dosage instructions to the letter, and disposing of unwanted medications properly. We’ll let you know here when the next collection event is scheduled.