Trends in long term exposure to propoxur and pyrethroids in young children in the Philippines

Abstract

Background/aim: Pesticides are neurotoxic and can adversely affect children's neurobehavioral outcome. Ongoing pesticide exposure has to be monitored in the study of long term outcome of pesticide adverse effects since changes in the type and amount of exposure can influence outcome. The aim of this paper is to describe the trend in long term pesticide exposure in children through the analysis of pesticides in their hair.

Patients and methods: As part of an NIH study on the long term effects of pesticide exposure in young children, ongoing exposure to pesticides was determined by the analysis of children's hair for propoxur and pyrethroids by gas chromatography/mass spectrometry at 2, 4 and 6 years of age.

Results: There were significant changes in the prevalence and concentration of propoxur and pyrethroids in children's hair at 2, 4 and 6 years of age. At ages 2 and 4 years, the prevalence of propoxur exposure increased from 12.4% to 24.1% (p<0.001) but dramatically decreased to 1.7% at 6 years (p<0.001). For bioallethrin, the prevalence of exposure steadily increased from 2 years (0.7%, p<0.001) to 4 years (12.4%, p<0.001) and to 6 years (18.4% p<0.001). Exposure to transfluthrin significantly increased from 4 years (1.0%) to 6 years (9.2%, p<0.001). There were also significantly higher median concentrations of bioallethrin at 2 compared to 4 years and for propoxur at 2 years compared to 6 years. Between 4 and 6 years, there was a higher median concentration of propoxur at 4 compared to 6 years and for transfluthrin and bioallethrin, at 6 compared to 4 years.

Conclusion: Changes in the prevalence and concentration of exposure to propoxur and pyrethroids in children at 2, 4 and 6 years of age are related to the progress in ambulation of young children and to changes in the formulation of home spray pesticides. Thus, periodic monitoring of pesticide exposure is necessary when studying the long term effects of pesticide exposure in the neurodevelopment of young children.

Keywords: Biomarkers; Environmental exposure; Hair; House dust; Pesticides; Young children.