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Biological monitoring of chlorpyrifos exposure to rice farmers in Vietnam.

Abstract
Chlorpyrifos is the most common organophosphate insecticide registered for use in Vietnam and is widely used in agriculture, particularly rice farming. However, chlorpyrifos exposure to and adverse effects on farmers has not been evaluated. In this study, biological monitoring of chlorpyrifos exposure in a group of rice farmers was conducted after a typical application event using back-pack spraying. Urine samples (24 h) were collected from the rice farmers before and post insecticide application. Samples were analysed for 3,5,6-trichloropyridinol (TCP), the major urinary metabolite of chlorpyrifos, using an enzymatic pre-treatment before extraction followed by HPLC-MS/MS. Absorbed Daily Dose (ADD) of chlorpyrifos for farmers were then estimated from urinary TCP levels, expressed as μg g(-1)creatinine. The analytical method for urinary TCP had a low detection limit (0.6 μg L(-1)), acceptable recovery values (80-114%), and low relative percentage differences in duplicate and repeated samples. Post-application chlorpyrifos ADD of farmers varied from 0.4 to 94.2 μg kg(-1) (body weight) d(-1) with a mean of 19.4 μg kg(-1) d(-1) which was approximately 80-fold higher than the mean baseline exposure level (0.24 μg kg(-1) d(-1)). Hazard Quotients (ratio of the mean ADD for rice farmers to acute oral reference dose) calculated using acute oral reference doses recommended by United States and Australian agencies varied from 2.1 (Australian NRA), 4.2 (US EPA) to 6.9 (ATSDR). Biological monitoring using HPLC-MS/MS analysis of urinary TCP (24 h) was found to be an effective method for measuring chlorpyrifos exposure among farmers. This case study found that Vietnamese rice farmers had relatively high exposures to chlorpyrifos after application, which were likely to have adverse health effects.
AuthorsDung Tri Phung, Des Connell, Greg Miller, Mary Hodge, Renu Patel, Ron Cheng, Manel Abeyewardene, Cordia Chu
JournalChemosphere (Chemosphere) Vol. 87 Issue 4 Pg. 294-300 (Apr 2012) ISSN: 1879-1298 [Electronic] England
PMID22209251 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
CopyrightCopyright © 2011 Elsevier Ltd. All rights reserved.
Chemical References
  • Environmental Pollutants
  • Insecticides
  • Chlorpyrifos
Topics
  • Adult
  • Agriculture
  • Chlorpyrifos (urine)
  • Environmental Monitoring
  • Environmental Pollutants (urine)
  • Female
  • Humans
  • Insecticides (urine)
  • Male
  • Middle Aged
  • Occupational Exposure (analysis, statistics & numerical data)
  • Oryza
  • Vietnam
  • Young Adult

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