Abstract
BackgroundNational data suggest widespread gestational exposure to organophosphate pesticides (OPs) based on the detection of OP metabolites in the urine of pregnant women. Associations with early infant neurobehavior are largely understudied, with only two studies reporting abnormal reflexes in newborns in association with gestational exposure to OPs. Our objective was to utilize biological markers of OP metabolites in pregnant women and a comprehensive assessment of infant neurobehavior to determine the association of gestational exposure to OPs with neurobehavioral outcomes during early infancy.MethodsAmong a cohort of 350 mother/infant pairs, we measured six common dialkylphosphate metabolites of OP pesticides in maternal urine, at two times during pregnancy (16 w & 26 w gestation), then calculated aggregate concentrations of diethylphosphate, dimethylphosphate, and total dialkyphosphate metabolites. We measured infant neurobehavior at about five weeks of age using the NICU Network Neurobehavioral Scale (NNNS), a comprehensive assessment of neurobehavior in young infants. Analyses of associations between gestational exposure to OPs and neurobehavior at five weeks included multiple linear and logistic regression.ResultsAfter adjustment for covariates, higher creatinine-corrected urinary concentrations of diethylphosphate metabolites were associated with improved attention and reduced lethargy and hypotonia in young infants. Higher creatinine-corrected urinary concentrations of total dialkylphosphate metabolites were associated with fewer signs of autonomic stress. Women who were white, married, had advanced education, and reported more frequent consumption of fresh fruits and vegetables had higher concentrations of OP metabolites during pregnancy.ConclusionsIn this sample of pregnant women whose urinary concentrations of dialkylphosphate metabolites are representative of national exposure levels, we found no detrimental effects of gestational exposure to OPs on neurobehavioral outcomes among young infants. These results are important as they suggest there may be minimal to no detectable adverse impact of low level prenatal OP exposure on the neurobehavior of young infants.
Highlights
National data suggest widespread gestational exposure to organophosphate pesticides (OPs) based on the detection of OP metabolites in the urine of pregnant women
Given the widespread exposure to OPs yet limited availability of conclusive studies evaluating their effect on infant neurobehavior, the purpose of the current study was to determine the association of prenatal exposure to OPs with neurobehavior during early infancy, measured with the NICU Network Neurobehavioral Scale (NNNS), in a sample of women with generally low exposure levels that may be more representative of national exposures levels than the two previous studies of women with high exposures
An additional limitation of this study relates to the narrow range and relatively low concentrations of dialkylphosphates in our cohort. While these factors may somewhat hinder our ability to detect neurobehavioral differences related to prenatal exposure, the urinary concentrations of these metabolites are reflective of those reported nationally and may increase our generalizability and relevance to a large percentage of the population. In this sample of young infants born to women who had urinary concentrations of dialkylphosphate metabolites of OP insecticides that are representative of the background exposure among U.S adult females, we found no evidence of detrimental effects of gestational exposure to OPs on neurobehavioral outcomes
Summary
National data suggest widespread gestational exposure to organophosphate pesticides (OPs) based on the detection of OP metabolites in the urine of pregnant women. Assessments such as the Neonatal Behavioral Assessment Scale (NBAS) [10] and the NICU Network Neurobehavioral Scale (NNNS) [11] have been critical in characterizing the early effects of gestational exposure to alcohol [12,13,14,15,16,17], drugs of abuse [18,19,20,21,22,23], and tobacco [15,24,25,26,27] These early infant neurobehavioral assessments have been only modestly utilized in environmental exposure research, but they show great promise in helping to illuminate the earliest detectable impact of gestational exposures to environmental toxicants. Such studies have reported associated outcomes related to prenatal exposures to polychlorinated biphenyls [28,29], methyl mercury [30], lead [31,32], phthalates [33,34], organochlorine pesticides [35,36], and OPs [37,38]
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