Probabilistic assessment of chlorpyrifos exposure to rice farmers in Viet Nam

• Published in: Journal of exposure science & environmental epidemiology Vol. 22; no. 4; pp. 417 - 423
• Main Authors: Phung, Dung Tri, Connell, Des, Miller, Greg, Chu, Cordia
• Format: Journal Article
• Language: English
• Published: New York Nature Publishing Group US 01.07.2012; Nature Publishing Group
• Subjects: 639/638/403; 692/700/478/174; 704/172/169/895; Application; Chlorpyrifos; Chlorpyrifos - toxicity; Epidemiology; Evaluation; Exposure; Farmers; Guidelines; Health aspects; High-performance liquid chromatography; Learning models (Stochastic processes); Liquid chromatography; Medical examination; Medicine; Medicine & Public Health; Metabolites; Multivariate analysis; Occupational Exposure; Organophosphates; original-article; Oryza; Oryza sativa; Pesticide application; Pesticides; Pesticides - toxicity; Probability; Protective equipment; Regression analysis; Rice; Rice workers; Statistical analysis; Trichloro-2-pyridinol; Vietnam; Vietnam; Chlorpyrifos; probabilistic assessment; Vietnam; farmers; exposure; absorbed daily dose
• ISSN: 1559-0631; 1559-064X; 1559-064X
• DOI: 10.1038/jes.2012.32

Chlorpyrifos is the most common organophosphate compound registered for agricultural use in Vietnam. The aim of this study was to evaluate chlorpyrifos exposure to rice farmers in Vietnam, using a probabilistic approach. Urine samples on a 24-h basis were collected from farmers before and post application of pesticide. Samples were analysed for 3,5,6-trichloro-2-pyridinol (TCP), the major urinary metabolite of chlorpyrifos, using an enzymatic pre-treatment for extraction and HPLC-MS/MS. Absorbed daily doses (ADD) of chlorpyrifos for farmers were subsequently estimated from the urinary TCP levels. The baseline and post-application exposure levels were evaluated at the 5th, 50th, and 95th percentile representing low, medium and high-exposure groups in the population. Regression analysis was applied to examine the association between exposure level and factors. The baseline exposure level, which ranged from 0.03 to 1.98  μ g/kg/day was below the chronic guidelines recommended by international and national bodies. However, the post-application exposure level, which ranged from 0.35 to 94  μ g/kg/day exceeded most of the acute guidelines at the 95th percentile level. Multivariate analysis provided strong evidence for a relationship between post-application exposure level and amount of chlorpyrifos used, as well as body coverage of personal protective equipment.