Recent and ever exposure predictors of urinary pesticide biomarkers among children in South Africa: A two - year longitudinal study.
Residents of agricultural regions are exposed to complex mixtures of agricultural and household pesticides, yet determinants of exposure remain poorly characterized in low-and middle-income countries, limiting accurate exposure assessment and health risk evaluation. This study aimed to identify self-reported recent and ever behavioural and environmental factors associated with urinary pesticide biomarker levels among children living in three agricultural areas of the Western Cape, South Africa. Between 2017 and 2019, 533 children aged 9-15 years provided 1,814 spot urine samples and completed exposure questionnaires up to five times. Parents and children provided information on exposure factors such as farm residence, use of household pesticides, seeing spray drifts and various pesticide exposure activities. Fourteen biomarkers of pyrethroids, organophosphates, triazoles and dithiocarbamates were quantified using liquid chromatography-tandem mass spectrometry and corrected for specific gravity. Associations between exposure factors and biomarker levels were evaluated using linear mixed-effects models. Recent household pesticide use was associated with up to 57% higher levels of 12 biomarkers, while recent spray drifts exposure was associated with up to 30% higher levels of eight biomarkers. Ever household pesticide use and ever exposure to spray drifts were associated with up to 30% higher levels of IMPy, 2,4-D and 4F3PBA. Use of open drinking water sources was associated with higher TCPy, BCP and ETU levels. Recent exposure factors were consistently associated with urinary biomarker levels than ever exposure factors. The identified exposure factors can inform pesticide exposure characterization in epidemiological analyses and targeted interventions to reduce children's exposure in agricultural communities.