Determination and Assessment of Glyphosate Exposure Among Farmers from Northern Part of Thailand

Abstract

Background and Objective: The most popular herbicide used for crops in Northern Thailand is glyphosate which is a systemic, post-emergent, non-selective herbicide. The aim of present study was to modify a high performance liquid chromatographic-based method for analyzing of urine samples from farmers of Northern Thailand. Materials and Methods: The urine samples was cleaned by Solid Phase Extraction (SPE) after derivatization with 9-fluorenylmethoxycarbonyl chloride (FMOC-Cl) and quantified by using high performance liquid chromatography with fluorescence detector (HPLC-FLD) to assessed glyphosate residue. Results: The modified HPLC-FLD method showed good accuracy and precision. The percent recovery levels obtained using control urine samples spiked at glyphosate concentrations of 2, 5 and 10 µg LG1 were 91.2, 79.7 and 103.9, respectively. The precision (RSD%) assessments reported as , inter- and intra-batch variation were in rage of 3.9-11.5%. The limit of detection and limit of quantification were 0.5 and 2.0 µg LG1 respectively. The modified HPLC-FLD method was applied to urine samples of farmers in Northern Thailand (Chiang Mai, Chiang Rai and Payao provinces) for analysis of glyphosate residue. The results showed glyphosate residue in 44.8% of urine samples collected with mean concentration 13.70±13.30 µg LG1 (11.89±26.08 µmol molG1 creatinine) and the corresponding geometric mean was 9.50 µg LG1 (5.88 µmol molG1 creatinine). Conclusion: The study successfully validated an HPLC-FLD for analyzing of glyphosate concentrations in human urine samples. The validated method was applied to measure glyphosate levels in urine samples collected from farmers of Northern Thailand region. The results indicated measurable glyphosate levels in 48% urine samples collected. In summary, the modified HPLC-FLD method may be used to assess the glyphosate body burden. Key