The health of our streams is a reflection of the overall quality of our nation’s waters. The extent of chemical contamination in streams is often a principal driver in whether a given stream is considered healthy or impaired. Chemical contaminants reach streams from many human activities such as farming, industry, sewage treatment and urban runoff. Understanding the degree to which our streams are polluted with chemical contaminants is critical to developing effective plans to maintain, manage and restore them.
The mixture of compounds present in stream waters was the focus of two recent studies from EPA and U.S. Geological Survey. Researchers took samples from 38 streams across the United States. One study analyzed the samples for more than 700 chemical contaminants, while the other study used a suite of in vitro bioassays to look for hormone receptor activity. They found organic contaminants at all sampling sites, including pharmaceuticals, insecticides, herbicides, and antibacterials, with many sites having hundreds of chemicals detected. Further, estrogen receptor activity occurred in nearly every site and several locations displayed androgen and glucocorticoid receptor activity.
Additional study is needed to determine if the contaminants present and their concentrations pose a risk to aquatic life, the food chain, or humans. You can read more about this work in a recent article in Popular Science, popsci.com.