Relationship between urinary levels of organophosphate metabolites and pesticide exposures among rural school boys of the Western Cape

Abstract

Background: Current evidence on the relationship between demographic, socio-economic and pesticide exposure risk factors and urinary levels of organophosphate pesticide metabolites among children is generally incomplete and conflicting in some cases. This study investigated the relationship between socio-economic, demographic and reported pesticide exposure related behaviours and characteristics in relation to urinary levels dialkyl phosphate (DAP) metabolites among boys from rural Western Cape, South Africa. Methods: A cross-sectional study of 183 school boys from three agricultural intense areas was conducted. Measurements included a questionnaire on demographic, socio-economic and pesticide exposure risk and analysis of urinary DAP metabolites (diethyl (DEP), dimethyl (DMP) and dimethyl triphosphate (DMTP)). Results: DAP, DEP, DMP and DMTP were detected with median concentrations of 68.3 ng/ml, 5.5 ng/ml, 32.6 ng/ml and 16.7 ng/ml, respectively. Most of the boys (70%) lived on farms with a median age of 12 years (range: 5 -19.5 years). The sum of DAP levels decreased in a dose dependant manner with age. Children older than 14 years had less DAP levels (β =-68.1, p=0.05) than children 9 years and younger. DAP levels also varied significantly with area, with the levels highest in Grabouw, followed by Piketberg (β=-54.2, p=0.01). Other weaker and non-significant predictors of increased DAP levels were household income, member of household work with pesticides, living on farm, drinking water from an open water source and eating crops from the vineyard and /or garden. Conclusion: The study provide evidence that lower age and residential area are predictors of increased urinary DAP concentrations among boys. Additionally, pesticide exposure factors such as member of household work with pesticide, living on the farm, drinking water from an open water source and eating crops from vineyard also determines increased DAP levels. Further studies with larger sample sizes and longitudinal designs are recommended.