title: Probabilistic assessment of chlorpyrifos exposure to rice farmers in Viet Nam.
abstract: 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 μg/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 μg/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.
authors.affiliation: Centre for Environment and Population Health, Griffith School of Environment, Griffith University, 170 Kessel Road, Nathan, QLD, Australia. ptdzung70@yahoo.com
authors.forename: Dung Tri
authors.initials: DT
authors.lastname: Phung
authors.forename: Des
authors.initials: D
authors.lastname: Connell
authors.forename: Greg
authors.initials: G
authors.lastname: Miller
authors.forename: Cordia
authors.initials: C
authors.lastname: Chu
mesh_terms: D004390:Chlorpyrifos / Q000633:toxicity*; D016273:Occupational Exposure; D012275:Oryza; D010575:Pesticides / Q000633:toxicity*; D011336:Probability; D014744:Vietnam
chemical_list: D010575:Pesticides; D004390:Chlorpyrifos