Low-level detection of pesticides…so what?

Excerpt

New images about the nature and extent of waterborne pesticides are emerging from scientific investigations in 20 major watersheds across the country. Aside from offering hard data about where and which pesticides have been found, these findings bear on a variety of significant issues confronting national and state policymakers such as gauging human and ecological exposure, identifying key nonpoint sources of pesticides, and updating management and regulatory approaches to water quality. The paucity of conclusive studies on the links between waterborne pesticides and human and ecological health limit the degree to which risks can be evaluated. However, a policy approach that seeks to use the insights that are available while filling in gaps in scientific knowledge will ensure that water-quality management and regulations, as they evolve, reflect actual environmental conditions.

The overall picture emerging from discoveries by the U.S. Geological Survey's National Water Quality Assessment Program (NAWQA) since 1993 is of mixtures of pesticides that typically occur at low levels, punctuated by seasonal pulses in concentration. Ninety-five percent of streams and 50 percent of wells near agricultural and urban areas contain at least one pesticide and often contain detectable levels of 2 or more. The specific …