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

ABSTRACT

Organophosphate pesticides (OPs) are widely used in agricultural sectors in Thailand. Previous studies have documented that children residing in agricultural areas have higher exposure to OPs than children living in other residential areas. 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, 53 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 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 [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 < .05). The results from linear regression analysis revealed that the frequency of OP application on rice farms (∑DAP: P = .001; TCPy: P = .001) and living in a rice farming community (∑DAP: P = .009; TCPy: P < .001) were significant predictors of urinary DAP metabolite levels in participants. Increasing TCPy levels were significantly related to proximity to rice farm (P = .03), being with parent while working on a farm (P = .02), playing on a farm (P = .03), and the presence of observable dirt accumulated on the child’s body (P = .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.

KEYWORDS:

• Activity
• children
• dialkylphosphates (DAPs)
• environment
• organophosphate pesticides (OPs)
• 3,5,6-trichloro-2-pyridinol (TCPy)

ACKNOWLEDGMENTS

The authors would like to thank Dr. Tippawan Prapamontol and her staff at the Pollution and Environmental Health Research Program, Research Institute for Health Sciences (RIHES), Chiang Mai University, for their dedicated work on DAP analysis. The authors would like to thank to Drs. Buppha Raksanam, Phiman Thirarattanasunthon, Pajaree Abdullakasim, Nutta Taneepanichskul, and Saowanee Norkaew, Ms. Arpaporn Ussanarassamee, Ms. Supasuta Sukcharoenphol, and Mr. Weerayut Kulsuwiponchai for their data collection and field work throughout the study. The authors also would like to deeply thank the Khlong 7 Tumbon Health Promoting Hospital and Lum Luk Ka Hospital and children participants and families, without whom this study would not be possible. Lastly, the authors thank Ms. Priya E D’Souza for her assistance in editing the manuscript.