Pesticides in Groundwater of the United States: Decadal‐Scale Changes, 1993–2011

Abstract

The national occurrence of 83 pesticide compounds in groundwater of the United States and decadal-scale changes in concentrations for 35 compounds were assessed for the 20-year period from 1993-2011. Samples were collected from 1271 wells in 58 nationally distributed well networks. Networks consisted of shallow (mostly monitoring) wells in agricultural and urban land-use areas and deeper (mostly domestic and public supply) wells in major aquifers in mixed land-use areas. Wells were sampled once during 1993-2001 and once during 2002-2011. Pesticides were frequently detected (53% of all samples), but concentrations seldom exceeded human-health benchmarks (1.8% of all samples). 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 categories of well networks nationally aggregated by land use. For agricultural networks, concentrations of atrazine, metolachlor, and prometon decreased from the first decade to the second decade. For urban networks, deethylatrazine concentrations increased and prometon concentrations decreased. For major aquifers, concentrations of deethylatrazine and simazine increased. The directions of concentration changes for individual well networks generally were consistent with changes determined from nationally aggregated data. Altogether, 36 of the 58 individual well networks had statistically significant changes in concentrations of one or more pesticides between decades, with the majority of changes attributed to the five most frequently detected pesticide compounds. The magnitudes of median decadal-scale concentration changes were small-ranging from -0.09 to 0.03 µg/L-and were 35- to 230,000-fold less than human-health benchmarks.

Groundwater Pesticide Levels and the Association With Parkinson Disease

“…The atrazine concentrations in groundwater in Colorado are predominantly below the Environmental Protection Agency maximum contaminant level of 3.0 mg/L with 2% of samples exceeding this level, a percentage similar to what was found in other groundwater studies. 16 This study reports a significant association in a large cohort between a predicted exposure defined by subject residence and PD with an indicated dose-response relationship. Past research has involved smaller cohorts (100 cases).…”

Short-term oral atrazine exposure alters the plasma metabolome of male C57BL/6 mice and disrupts α-linolenate, tryptophan, tyrosine and other major metabolic pathways

“…Atrazine (ATR) is a widely used herbicide and the most commonly detected pesticide in the groundwater, soil, and rain in agricultural areas of the US (Majewski et al 2014;Toccalino et al 2014). Groundwater ATR concentrations at levels close to the regulatory threshold value of 0.1 µg/L were reported 20 years after it was banned in Germany (Vonberg et al 2014); 14 C-labeled ATR could be detected in soil 22 years after application (Jablonowski et al 2009), indicating environmental persistence and widespread potential for chronic, environmental exposures to low levels of ATR.…”

Auxin Herbicides and Pesticide Mixtures in Groundwater of a Canadian Prairie Province

“…Thus, only 15% of the 105 compounds analyzed for were detected. Other groundwater studies detected 20 to 82% of the pesticide compounds screened for, with between 20 and 83 compounds included in these studies (ECCC, 2005; Woudneh et al, 2009; Silva et al, 2012; Toccalino et al, 2014). 89 compounds were not detected, including 28 current‐use pesticides in Canada of which 21 pesticides are recommended for use in Alberta crop production (Alberta Crop Protection Guide, 2015) (Supplemental Table S1).…”