Child exposure to organophosphate and pyrethroid insecticides measured in urine, wristbands, and household dust and its implications for child health in South Africa: A panel study.

Background: Children in agricultural areas are exposed to organophosphate (OP) and pyrethroid (PYR) insecticides. This explorative study investigated child exposure to OPs and PYRs, comparing temporal and spatial exposure variability within and among urine, wristbands, and dust samples. Methods: During spraying season 2018, 38 South African children in two agricultural areas (Grabouw/Hex River Valley) and settings (farm/village) participated in a seven-day study. Child urine and household dust samples were collected on days 1 and 7. Children and their guardians were wearing silicone wristbands for seven days. Intraclass correlation coefficients (ICCs) evaluated temporal agreements between repeated urine and dust samples, Spearman rank correlations (Rs) evaluated the correlations among matrices, and linear mixed-effect models investigated spatial exposure predictors. A risk assessment was performed using reverse dosimetry. Results: Eighteen OPs/PYRs were targeted in urine, wristbands, and dust. Levels of chlorpyrifos in dust (ICC = 0.92) and diethylphosphate biomarker in urine (ICC = 0.42) showed strong and moderate temporal agreement between day 1 and day 7, respectively. Weak agreements were observed for all others. There was mostly a weak correlation among the three matrices (Rs = -0.12 to 0.35), except for chlorpyrifos in dust and its biomarker 3,5,6-trichloro-2-pyridinol in urine (Rs = 0.44). No differences in exposure levels between living locations were observed. However, 21% of the urine biomarker levels exceeded the health-risk threshold for OP exposure. Conclusions: Observed high short-term variability in exposure levels during spraying season highlights the need for repeated sampling. The weak correlation between the exposure matrices points to different environmental and behavioral exposure pathways. Exceeding risk thresholds for OP should be further investigated.

Relation between organophosphate pesticide metabolite concentrations with pesticide exposures, socio-economic factors and lifestyles: A cross-sectional study among school boys in the rural Western Cape, South Africa.

Evidence on the relationship between lifestyle, socio-economic factors and pesticide exposure and urinary concentrations of organophosphate (OP) pesticide metabolites among children is generally incomplete. This study investigated the relationship between socio-economic factors and reported pesticide exposures and the sum of three urinary concentrations of dialkyl phosphate metabolites (DAP) among boys living in the rural areas of the Western Cape, South Africa. Data was collected during a cross-sectional study of 183 boys from three agricultural intense areas. Measurements included a questionnaire on socio-economic and pesticide exposures and urinary DAP concentrations. Most boys (70%) lived on farms with a median age of 12 years (range: 5.0-19.5 years). Children aged >14 years had lower DAP urine concentrations (median = 39.9 ng/ml; ß = -68.1 ng/ml; 95% CI: -136.8, 0.6) than children aged 9 years and younger (median = 107.0 ng/ml). DAP concentrations also varied significantly with area, with concentrations in the grape farming area, Hex River Valley (median = 61.8 ng/ml; ß = -52.1; 95% CI: -97.9, -6.3 ng/ml) and the wheat farming area, Piketberg (median = 72.4 ng/ml; ß = -54.2; 95% CI: 98.8, -9.7 ng/ml) lower than those in the pome farming area, Grabouw (median = 79.9 ng/ml). Other weaker and non-significant associations with increased DAP levels were found with increased household income, member of household working with pesticides, living on a farm, drinking water from an open water source and eating crops from the vineyard and or garden. The study found younger age and living in and around apple and grape farms to be associated with increased urinary DAP concentrations. Additionally, there were other pesticide exposures and socio-economic and lifestyle factors that were weakly associated with elevated urinary DAP levels requiring further study. The study provided more evidence on factors associated to urinary DAP concentrations especially in developing country settings.

A prospective cohort study of school-going children investigating reproductive and neurobehavioral health effects due to environmental pesticide exposure in the Western Cape, South Africa: study protocol.

BACKGROUND: Research on reproductive health effects on children from low-level, long-term exposure to pesticides currently used in the agricultural industry is limited and those on neurobehavioral effects have produced conflicting evidence. We aim at investigating the association between pesticide exposure on the reproductive health and neurobehavior of children in South Africa, by including potential relevant co-exposures from the use of electronic media and maternal alcohol consumption. METHODS: The design entails a prospective cohort study with a follow-up duration of 2 years starting in 2017, including 1000 school going children between the ages of 9 to 16 years old. Children are enrolled with equal distribution in sex and residence on farms and non-farms in three different agricultural areas (mainly apple, table grapes and wheat farming systems) in the Western Cape, South Africa. The neurobehavior primary health outcome of cognitive functioning was measured through the iPad-based CAmbridge Neuropsychological Test Automated Battery (CANTAB) including domains for attention, memory, and processing speed. The reproductive health outcomes include testicular size in boys and breast size in girls assessed in a physical examination, and blood samples to detect hormone levels and anthropometric measurements. Information on pesticide exposure, co-exposures and relevant confounders are obtained through structured questionnaire interviews with the children and their guardians. Environmental occurrence of pesticides will be determined while using a structured interview with farm owners and review of spraying records and collection of passive water and air samples in all three areas. Pesticide metabolites will be analysed in urine and hair samples collected from the study subjects every 4 months starting at baseline. DISCUSSION: The inclusion of three different agricultural areas will yield a wide range of pesticide exposure situations. The prospective longitudinal design is a further strength of this study to evaluate the reproductive and neurobehavioural effects of different pesticides on children. This research will inform relevant policies and regulatory bodies to improve the health, safety and learning environments for children and families in agricultural settings.