Testing water quality for pesticide pollution

Abstract

Information from the first phase of the USA's National Water Quality Assessment (NAWQA) Program shows that pesticides are widespread in streams and ground water, and occur in geographical and seasonal patterns that follow land use and related pesticide use. The most heavily used compounds account for most detections, and most pesticides found in the environment usually occur as mixtures. Almost every stream sample collected contained at least one pesticide. For drinking water, the NAWQA results usually provide good news about individual pesticides in relation to current regulations and criteria. However, the extent of risk to humans here is not yet known, because the criteria cover limited numbers of pesticides and potential effects. The NAWQA results show a high potential for pesticide impacts on aquatic life in some streams, especially those where concentrations of more than one pesticide approach or exceed aquatic-life criteria for long time periods. This feature describes the NAWQA Programs's scope and structure, discusses the widespread occurrence of pesticides in natural waters, gives examples of use-detection relationships and considers the environmental significance of the Programs's findings and their implications for NAWQA. The NAWQA design may be modified to improve assessment in future studies.