Human biomonitoring of a urinary propetamphos metabolite using gas chromatography–mass spectrometry

Abstract

Objectives: Propetamphos (PPT) is an organophosphate pesticide (OP) widely used to control insects in public health settings and methylethylphosphoramidothioate (MEPT) is a urinary exposure marker of PPT. The objectives of this study were to develop a biomonitoring method for urinary MEPT using gas chromatography–mass spectrometry (GC–MS) and to measure urinary MEPT concentrations in occupational and non-occupational human populations. Methods: Analytes derivatized with pentafluorobenzyl bromide were analyzed by GC–MS and dibutyl phosphate was used as an internal standard. The validated method was applied to urine samples collected from occupational PPT sprayers (n=15), non-PPT sprayers (n=15) who did not spray PPT but sprayed other OPs, and control subjects (n=80) living in Aichi, Japan. Results: Calibration curves were obtained using standard-spiked pooled urine samples, and the coefficients of determination were ≥0.98. The limit of detection (LOD) was 10 μg/L. The within-run precision and between-run precision ranged from 17.5% to 19.4% and 10.4% to 18.1%, respectively. The detection rates of urinary MEPT in the PPT sprayers, non-PPT sprayers, and control subjects were 26.7%, 6.7%, and 2.5%, respectively. The concentration ranges for creatinine-unadjusted MEPT were <LOD–22.3, <LOD–21.9 and <LOD–13.8 μg/L, and creatinine-adjusted MEPT were <LOD–12.1, <LOD–12.7 and <LOD–7.9 μg/g creatinine, for the respective groups (PPT sprayers, non-PPT sprayers and controls). Conclusions: This study established a biomonitoring method that can measure urinary MEPT in spraying and non-spraying workers with exposure levels ≥10 μg/L.