A U.S. Geological Survey Study of data collected between 1992 and 2001 found pesticides in most rivers and steams in both urban and agricultural areas across the United States. Pesticides have been linked to cancer, birth defects and neurological disorders. While levels found in water were usually below that required to threaten humans, according to USGS scientists, they were often determined high enough to be a threat to wildlife.

Nearly 40 of the 100 pesticides included in the study accounted for the bulk of the discoveries in samples from fish, sediments and water. As expected, herbicides such as prometon, semazine and tebuthiuron, which are commonly used in cities, were found in urban streams, while atrazine, cyanazine and metolachlor, which are commonly used on farms, were found in agricultural area streams. Pesticides showed up in over 90 percent of the fish tissue samples in all areas.

“While the use of pesticides has resulted in a wide range of benefits to control weeds, insects and other pests, including increased food production and reduction of insect-borne disease, their use also raises questions about possible effects on the environment, including water quality,” said Robert Hirsh, the USGS associate director for water.

The report was based on an analysis of data from 51 major river basins and aquifer systems nationally, and a study of an aquifer system that runs through eight states from South Dakota to Texas, east of the Rocky Mountains. Data also indicated the presence of pesticides was much less common in groundwater.

“Water quality is of paramount importance to us,” said Jay Vroom, president of Croplife America. “And the USGS report correctly recognizes that the large majority of pesticide detections in streams and groundwater were trace amounts, far below scientifically based minimum levels set for protecting human health and the environment.” He stated further that just the presence of pesticides does not always mean there is cause for concern.

The report can be viewed at http://water.usgs.gov/pubs/circ./circ1291.