Postnatal pesticide exposure and executive function in children and adolescents: Findings from South Africa.

INTRODUCTION

Postnatal pesticide exposure and its impact on executive functioning (EF) in children and adolescents remains underexplored, particularly in African agricultural contexts. This study investigated associations between urinary pesticide biomarkers and EF in the Child health Agricultural Pesticide study in South Africa (CapSA).

METHODS

Data from 445 participants (mean age: 10.6 years; 55.3 % male) were analysed. EF was assessed using three Cambridge Neuropsychological Test Automated Battery (CANTAB) subtests: the Multitasking Test (MTT, cognitive flexibility), Rapid Visual Information Processing (RVP, inhibitory control), and Spatial Working Memory (SWM, visuospatial working memory). Average levels of 13 pesticide biomarkers-spanning insecticides (organophosphates, pyrethroids), fungicides (dithiocarbamates, triazoles, succinate dehydrogenase inhibitors), and herbicides (phenoxy acids)-were calculated from two spot urine samples collected in 2017 and 2019. Associations between specific gravity-adjusted, log10-transformed biomarker-levels (ng/mL) and EF z-scores were estimated using multivariate linear regression, adjusting for agricultural setting, child and maternal characteristics, and household factors.

RESULTS

Twelve of thirteen pesticide biomarkers showed widespread detection, with several (TCPy, 3-PBA, OH-TEB, ETU, and 2,4-D) detected in over 98 % of samples. Higher average levels of TCPy (β = -0.14; 95 % CI: 0.27, -0.01) and BCP (-0.08; -0.15, -0.02) were associated with poorer cognitive flexibility. Higher average levels of TCPy (-0.18; -0.31, -0.05), BCP (-0.08; -0.14, -0.01), cis-DCCA (-0.15; -0.31, 0.00), and OH-P (-0.09; -0.16, -0.03) were associated with poorer inhibitory control. No significant associations were observed for visuospatial working memory.

CONCLUSIONS

Findings suggest postnatal exposure to specific organophosphates, pyrethroids and triazoles may impair specific EF domains. Results highlight the need for biologically informed exposure assessments and targeted interventions in agricultural populations.