Associations of Prenatal Exposure to Organophosphate Pesticide Metabolites with Gestational Age and Birth Weight

BACKGROUND: Prenatal exposure to organophosphate (OP) insecticides, a widely used class of pesticides, may be associated with decreased gestational age and lower birth weight. Single nucleotide polymorphisms in paroxanase (PON1) enzyme genotypes may modify the relationships between OP exposure and perinatal outcomes. OBJECTIVE: We examined the relationship of prenatal OP insecticide exposure, measured using urinary dialkyl phosphate (DAP) metabolite concentrations, With gestational age and birth weight. METHODS: We measured the concentrations of six nonspecific DAP metabolites of OP insecticides in two maternal spot urine samples collected in a prospective birth cohort. We performed multi-variable regression to examine associations between the sum of six DAP concentrations (Sigma DAP) with gestational age and birth weight. We also examined whether these associations differed according to infant PON1(192) and PON1(-108) genotypes. RESULTS: Among 306 mother-infant dyads, a 10-fold increase in Sigma DAP concentrations was associated with a decrease in covariate-adjusted gestational age [-0.5 weeks; 95% confidence interval (Cl): -0.8, 0.1] and birth weight (-151 gt CI: -287, -16); the decrements in birth weight were attenuated after adjusting for gestational age. The relationship between Sigma DAP concentrations and gestational age was stronger for white (-0.7 weeks; CI: -1.1, -0.3) than for black (-0.1 weeks; 95% CI: -0.9, 0.6) newborns. In contrast, there was a greater decrease in birth weight with increasing urinary Sigma DAP concentrations for black (-188 g; CI: -395, 19) than for white (-118 g; CI: -296, 60) newborns. Decrements in birth weight and gestational age associated with Sigma DAP concentrations were greatest among infants with PON1(192QR) and PON-108CT genotypes. CONCLUSIONS: Prenatal urinary Sigma DAP concentrations were associated with shortened gestation and reduced birth weight in this cohort, but the effects differed by race/ethnicity and PON1(192/108) genotypes.