Pesticide metabolite concentrations in Queensland pre-schoolers – Exposure trends related to age and sex using urinary biomarkers

Abstract

This study aimed to assess pesticide concentration and composition trends associated with age and sex in Australian infants and toddlers. Individual urine samples (n = 400) were collected in 2014/5 from Queensland infants and toddlers aged 0–5 y and composited into 20 pools of 20 individual samples by age (of 5 strata) and sex. Nineteen biomarkers including organophosphate and pyrethroid pesticide metabolites, herbicides and metabolites, and an insect repellent, DEET, were measured. In total, seven organophosphate pesticide metabolites, three pyrethroid metabolites and one herbicide metabolite were detectable in >50% of the sample pools. A significant increase of concentrations of dimethyl phosphate, dimethyl dithiophosphate, diethyl thiophosphate (DETP), 3,5,6-trichloro-2-pyridinol (TCPY), 4-nitrophenol and 3-phenoxybenzoic acid with age was observed (with the p value of <0.0001 to 0.034). This suggested that exposure increases following weaning or as a result of increased dietary intake and mobility/activity. Significant age trends remained after adjustment for body weight and urine flow for DETP and TCPY (p = 0.029 and 0.016 respectively). The level of estimated “worst-case scenario” daily intake of chlorpyrifos from these pooled samples ranged from 0.40 to 1.8 μg/kg-day, which was below the Australian Acceptable Daily Intake guideline (3 μg/kg-day). This study presents the first dataset of age trends in concentrations of these pesticides for infants and toddlers and contributed to new understanding of exposure pathways and potential risks.