In utero pesticide exposure and children's neurodevelopment: A summary of findings from the CHAMACOS cohort

Organochlorine (OC) pesticides such as DDT are still used in some countries for malaria control and organophosphate (OP) pesticides are widely used in agriculture and in homes. Animal studies suggest that even moderate doses of these chemicals are neurodevelopmental toxicants, but there are few studies in humans. We examined the relationship of children's neurodevelopment with in utero exposure, measured as levels of DDT and its breakdown product, DDE, in maternal blood during pregnancy, and levels of OP metabolites in maternal urine in the CHAMACOS (Center for the Health Assessment of Mothers and Children of Salinas) study. CHAMACOS is a birth cohort study of low-income, primarily Mexican immigrant farmworker women and their children living in the Salinas Valley, California. We examined children's performance on the Brazelton Neonatal Assessment Scales (BNBAS) after birth, on the mental and psychomotor development indices of the Bayley Scales of Infant Development (BSID) at 6, 12 and 24 months of age, and with mothers' report of child behavior on the Child Behavior Checklist at 24 months of age. Maternal serum levels of DDT and DDE were not associated with BNBAS performance but were significantly associated with decreases in mental and psychomotor development scores on the BSID at different ages. Maternal urinary OP metabolites were associated with increased numbers of abnormal reflexes on the BNBAS, decreased mental development scores at 24 months of age, and increased odds of maternally reported Pervasive Developmental Disorder at 24 months. We will discuss the policy implications of this work.