Study: Groundwater Hasn't Retained Pesticide Contaminants

Results from a decade-long study by the U.S. Geological Survey show that groundwater throughout the United States hasn't retained a high concentration of pesticide contamination, despite the widespread use of such chemicals.

"The results of this study are encouraging for the future state of the nation's groundwater quality with respect to pesticides," said data analyzer Laura Bexfield in a news release. "Despite sustained use of many popular pesticides and the introduction of new ones, results as a whole did not indicate increasing detection rates or concentrations in shallow or drinking-water resources over the 10 years studied."

The study — published in the current issue of the Journal of Environmental Quality — is part of the USGS' National Water Quality Assessment Program and one of the first national studies on pesticides in groundwater.

In the study, samples taken from over 300 wells across the country from 1993-1995 were compared with samples taken from 2001-2003. They were analyzed for 80 compounds, and only six of the compounds were detected in water from at least 10 wells during both sampling time periods. The compounds detected occurred at concentrations more than 10 times lower than EPA drinking water standards.

A statement from the American Society of Agronomy — which publishes the Journal of Environmental Quality — notes that characterizing trends in the presence of pesticides and their concentrations in groundwater across a long period of time is important for determining how quickly such systems respond to changes in chemical use and in identifying compounds that may pose a threat to water quality.