Pesticides and pesticide degradates in groundwater used for public supply across the United States: Occurrence and human-health context

Environmental Science & Technology
By: , and 

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Abstract

This is the first assessment of groundwater from public-supply wells across the United States to analyze for >100 pesticide degradates and to provide human-health context for degradates without benchmarks. Samples from 1204 wells in aquifers representing 70% of the volume pumped for drinking supply were analyzed for 109 pesticides (active ingredients) and 116 degradates. Among the 41% of wells where pesticide compounds were detected, nearly two-thirds contained compound mixtures and three-quarters contained degradates. Atrazine, hexazinone, prometon, tebuthiuron, four atrazine degradates, and one metolachlor degradate were each detected in >5% of wells. Detection frequencies were largest for aquifers with more shallow, unconfined wells producing modern-age groundwater. To screen for potential human-health concerns, benchmark quotients (BQs) were calculated by dividing concentrations by the human-health benchmark, when available. For degradates without benchmarks, estimated values (estimated benchmark quotients (BQE)) were first calculated by assuming equimolar toxicity to the most toxic parent; final analysis excluded degradates with likely overestimated toxicity. Six pesticide compounds and 1.6% of wells had concentrations approaching levels of potential concern (individual or summed BQ or BQE values >0.1), and none exceeded these levels (values >1). Therefore, although pesticide compounds occurred frequently, concentrations were low, even accounting for mixtures and degradates without benchmarks.

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Publication type Article
Publication Subtype Journal Article
Title Pesticides and pesticide degradates in groundwater used for public supply across the United States: Occurrence and human-health context
Series title Environmental Science & Technology
DOI 10.1021/acs.est.0c05793
Volume 55
Issue 16
Year Published 2021
Language English
Publisher American Chemical Society
Contributing office(s) WMA - Earth System Processes Division
Description 11 p.
First page 362
Last page 372
Country United States
Other Geospatial Continental United States
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