U.S. Geological Survey - Environmental Health
U.S. Geological Survey (USGS) scientists have completed the most comprehensive evaluation to date (2014) of decadal–scale changes in pesticide concentrations in groundwater of the United States. Such assessments are essential for tracking long–term responses to changes in pesticide use and land–management practices.
The five most frequently detected pesticide compounds—atrazine, deethylatrazine, simazine, metolachlor, and prometon—each had statistically significant (p < 0.1) changes in concentrations between decades in one or more types of well networks, nationally aggregated by land use.
Altogether, 36 of the 58 individual well networks had statistically significant changes in concentrations of one or more pesticides between decades. The magnitudes of median decadal–scale concentration changes were small—ranging from –0.09 to 0.03 micorgrams per liter (µg/L)—and were 35– to 230,000–fold less than human–health benchmarks.
This study was funded by the USGS National Water–Quality Assessment (NAWQA) Program.
Pesticides in groundwater of the United States–Decadal–scale changes, 1993–2011: Groundwater, 2014, 52, Issue S1, pages 112–125, doi:10.1111/gwat.12176.