USGS study finds surprisingly extensive mixture of pollutants in U.S. waterways

Many U.S. waterways carry a variety of pollutants. The mixture of pollutants are more complex and potentially more dangerous than previously thought, a new study shows.

Researchers, led by U.S. Geological Survey and the Environmental Protection Agency, checked water samples from 38 streams across the United States for 719 organic chemicals and found more than 50 percent hosted at least one of the contaminants.

According to the new study, published this week in the journal Environmental Science and Technology, every stream -- even those in wild and uninhabited areas -- carried at least one of the organic contaminants, and some carried as many as 162.

The detected chemicals included: caffeine; insecticides and herbicides including glyphosate, as well as byproducts from their degradation; antibacterials such as triclosan and medications such as antihistamines and the diabetes drug metformin.

The study also showed that some of these compounds, which are designed to have biological activity, frequently occur together in streams.

Further research is needed to determine whether the potential for complex interactions between these chemicals pose a threat to aquatic wildlife, the food chain and human health, researchers said. Endit