A study released this week by Baylor University shows that fish caught in five rivers across the U.S. harbor low-levels of several pharmaceuticals, including drugs that lower cholesterol levels, antidepressants, anti-convulsants, and drugs that treat allergies, high blood pressure, and bipolar disorder. The study was the first to examine the levels of pharmaceuticals in freshwater fish on a national scale.

Researchers took fish from rivers in Chicago, Dallas, Orlando, Phoenix, and Philadelphia, all of which collect the outflow from wastewater treatment plants. For comparison, they also tested fish from a river in New Mexico that is unaffected by human pollution.

Scientists tested the fish for the presence of 24 different pharmaceuticals and 12 chemicals found in beauty products. They found trace amounts of seven pharmaceuticals and two chemicals form beauty products in fish at all five river sites. The drugs included gemfibrozil, diphenhydramine, carbamazepine, norfluoxetine, fluoxetine and sertraline. The chemicals they found were galaxolide and tonalide, which are fragrances used in soap and other beauty products. None of the drugs or chemicals were found at the New Mexico river site.

While the amounts of the drugs found in the fish were very low – hundreds of thousands of times less than a therapeutic dose – what has the researchers and the Environmental Protection Agency (EPA) concerned is the effects of long-term consumption of trace amounts of medicines, especially in unknown combinations. Some evidence suggests that combinations of these pharmaceuticals, even in small amounts, could have a negative effect on the growth of human cells.

It is likely that fish absorb the pharmaceuticals because the rivers they live in are contaminated with traces of drugs that are not removed in wastewater treatment plants. Most of the drugs come from the un-metabolized byproducts of pharmaceuticals that people have taken and then excreted, while a smaller amount comes from unused drugs dumped down the drain.

A year ago, a separate study found trace amounts of pharmaceuticals in the drinking water of several major metropolitan areas.

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_{Photo: kasperbs, Flickr, Creative Commons}