Organophosphate

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Organophosphate Pesticide Exposure in School-Aged Children Living in Rice and Aquacultural Farming Regions of Thailand

Organophosphate pesticides (OPs) are widely used in agricultural sectors in Thailand because of their broad spectrum toxicity for insects. Previous studies have documented that children residing in agricultural areas have higher exposure to OPs than children living in other residential areas in the region. The objective of this study was to quantify urinary biomarkers of OP exposure and determine the environmental conditions and activities that predict their levels among children living in Central Thailand farming regions. In October 2011, fifty-three 6-8 year old participants were recruited from Pathum Thani Province, Thailand. Twenty-four lived in rice farming communities at Khlong Luang District where OPs are the pesticides used most frequently. Twenty-nine participants, living in aquacultural farming communities at Lum Luk Ka District where OPs are not used, were recruited to serve as controls for pathways of exposure (e.g., residential, dietary) other than occupational/paraoccupational exposures encountered in rice farming. Household environments and participants’ activities were assessed using a parental-structured interview. Urine samples (first morning voids) were collected from participants for OP urinary metabolite (i.e., dialkylphosphates (DAPs) and 3,5,6-trichloro-2-pyridinol or (TCPy) measurements. The levels of most urinary OP metabolites were significantly higher in participants who lived in a rice farming community than those who lived in an aquacultural farming community (p<0.05). The results from linear regression analysis revealed that the frequency of OP application on rice farms (∑DAP; p=0.001, TCPy; p = 0.001) and living in a rice farming community (∑DAP; p=0.009, TCPy; p<0.001) were significant predictors of urinary DAP metabolite levels in participants. Increasing TCPy levels were significantly related to proximity to rice farm (p=0.03), being with parent while working on a farm (p=0.02), playing on a farm (p=0.03), and the presence of observable dirt accumulated on the child’s body (p=0.02). In conclusion, OP metabolite levels among children who live in rice farming communities were strongly influenced by farming activity, household environments, and child behaviors suggesting that these are the primary pathways in which children living in these agricultural communities in Thailand were exposed to OPs. The extent to which these exposures result in adverse health effects is not known and requires further investigation.

Reference: Juthasiri Rohitrattana, Wattasit Siriwong, Tanasorn Tunsaringkarn, Parinya Panuwet, P. Barry Ryan, Dana B. Barr, Mark G. Robson, and Nancy Fiedler. Organophosphate Pesticide Exposure Among Children Living in Farmland: Evidence of Household Environment and Children Activities. Journal of Agromedicine, in press.