Pyrethroid

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Pyrethroid Insecticide Exposure in School-Aged Children Living in Rice and Aquacultural Farming Regions of Thailand

Background: Pyrethroid insecticides (PYR) are commonly used in rice farms and household pest control in Thailand. No investigative study has yet been made regarding factors associated with PYR exposure among Thai children.

Objective: This study aims to compare the levels of PYR exposure between children living in rice farms (high intensity PYR used) and aquacultural areas (low intensity PYR used) during the wet and dry seasons in Thailand during which different amounts of PYR are applied. Environmental conditions and common activities of children were used to identify factors associated with PYR exposure.

Methods: A cross-sectional study was done during the wet and dry seasons, respectively. A total of 53 participants aged between 6 and 8 years old were recruited from rice and aquacultural areas. The parental-structured interview was used to gather information about PYR use, household environments and participants’ activities. First voided morning urine samples were collected for PYR urinary metabolites (i.e. 3-phenoxybenzoic acid (3-PBA) and cis/trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (DCCA)) measurements. Hand wipe samples were collected during home visiting to measure PYR residues on the hands.

Results and Discussion: The concentrations of urinary PYR metabolites were not significantly different between participants who lived in rice farming and those who lived in aquacultural area during both wet and dry seasons. Both participant groups had slightly increased urinary PYR metabolites during the wet season compared to the dry season. The results from linear regression analysis revealed that some environmental conditions and activities or practices may be used to predict trends of PYR exposure. Frequency of PYR use in farms (β=0.004) and households (β=0.07), proximity to rice farm (β=0.09), playing in rice farms (β=0.11), and oral exposure from objects exposed to PYR (β=0.08) were likely to be related to increased concentrations of PYR metabolites. These findings suggest that PYR use in rice farms and households may be significant sources of PYR exposure among children living in agricultural areas. However, a bigger sample size may be necessary in a subsequent study that will explore the association between long-term exposure to pesticide and their health effects on children.

Reference: Juthasiri Rohitrattana, Wattasit Siriwong, Nancy Fiedler and Mark G. Robson. Pyrethroid Insecticide Exposure in Children Living in Rice and Aquacultural Farming Regions of Thailand. Risk Management and Healthcare Policy, in press.