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Apr 30, 2020

ACS Spring 2020 National Meeting & Expo

Pesticide exposure in drinking water and biomarker detection in human urine using high-resolution orbital ion trap mass spectrometry

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Abstract

Exposure to pesticides is a global health concern. To better understand health risks associated with pesticide exposure, monitoring of one’s environment (exposure characterization) and biomatrices (human biomonitoring) is essential. In addition to providing proof of internal exposure, biomonitoring allows investigation of endogenously formed compounds resulting from pesticide exposure. For example, potentially carcinogenic pesticide-associated N-nitroso compounds (PANNs) may form in the acidic environment of the stomach following exposure to nitrosatable pesticide residues in drinking water. Despite the advancement of technology used to identify a wide range of environmental pollutants and biomarkers, methods have not yet been developed for screening of PANNs in drinking water and urine. In this work, a comprehensive analytical method was developed for detecting nine nitrosatable pesticides and metabolites, as well as their PANNs, in groundwater and human urine using high-resolution orbital ion trap mass spectrometry. The novel sample preparation approach resulted in a suitable method for extraction of target analytes from urine; mean recoveries ranged between 96 to 116% (%RSD ≤ 10). To assess PANN formation in groundwater, target analytes were individually reacted at environmentally-relevant concentrations (≤ 20 µg L-1) with sodium nitrite and hydrochloric acid in water. Only ethylenethiourea (ETU) participated in PANN compound formation as evidenced by the tentative identification of N-nitrosoethylenethiourea (N-ETU); tentative identification was achieved by matching the accurate masses of theoretical and experimental N-ETU molecular ions with a mass error tolerance of 5 parts per million. N-ETU formation was then assessed in a pooled groundwater sample collected from an intensive agricultural region of Prince Edward Island, Canada. Evidence of N-ETU formation in the groundwater sample was observed in under 30 minutes at a pH value of 2.5 and at concentrations 20, 10, and 7.5 µg L-1, but not at 5 µg L-1. This work resulted in a single method capable of detecting PANN compounds and their parent pesticides in both groundwater and human urine. The results of the study show that ETU reacts with nitrite to form N-ETU at environmentally-relevant concentrations and that endogenous N-ETU formation may be a concern for individuals exposed to low concentrations of ETU.

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© Copyright 2019 Morressier GmbH.
All rights reserved.