Adverse effect of pre- and postnatal exposure to carbamate and pyrethroid pesticides on cognition in children at 4 and 6 years of age: A prospective study

ABSTRACT

Objective@#To determine the adverse effect of pre- and postnatal exposure to carbamate (propoxur) and pyrethroid pesticides on children's cognitive functions at 4 and 6 years of age. @*Method@#As part of a prospective cohort study among children with known pre- and postnatal exposure to propoxur and pyrethroids, children were examined at time points, 4 and 6 years, to determine the adverse effect of pesticide exposure on neurocognitive function, i.e., intelligence (IQ) using the WPPSI-III test. Pre- and postnatal pesticide exposures were measured by meconium and hair analysis, respectively, using gas chromatography-mass spectrometry (GCMS).@*Results@#Seven hundred twenty-four (724) maternal/children dyads were seen at four years and 717 at six years of age. Their mean (SD) full-scale IQ was low on average 83.9 (10.2) at four years and 83.6 (8.6) at six years. Prenatal but not postnatal exposure to propoxur (-0.139, p=0.01) and pyrethroids (-0.097, p=0.05) were significantly correlated (negative) with full-scale IQ at four years but not at six years. The confounders that were significantly correlated to full-scale IQ at four and/or six years of age were maternal IQ, child’s weight, height, head circumference, socio-economic status, child environment, and stimulation at home (HOME) violence or abuse at home. Regression analysis of pesticides and confounders showed similar results, except for weight and head circumference.@*Conclusion@#We conclude that prenatal exposure to propoxur and pyrethroids had a negative effect on the children’s IQ at four years but no longer at six years. Thus, the ability of the child’s IQ to recover from the adverse effect of intrauterine pesticide insult may be attributable to the neuronal plasticity of its brain. Similarly, confounders to these outcome measures are multiple and are essential to address when evaluating the effect of pesticides on neuro-cognitive development in children.