Prenatal Organophosphorus Pesticide Exposure and Child Neurodevelopment at 24 Months: An Analysis of Four Birth Cohorts

Background: Organophosphorus pesticides (OPs) are used in agriculture worldwide. Residential use was common in the United States prior to 2001.

Objectives: To conduct a pooled analysis of four birth cohorts (n = 936) to evaluate associations of prenatal exposure to OPs with child development at 24 months.

Methods: Using general linear models, we computed site-specific and pooled estimates of the association of total dialkyl (∑DAP), diethyl (∑DEP) and dimethylphosphate (∑DMP) metabolite concentrations in maternal prenatal urine with mental and psychomotor development indices (MDI/PDI), and evaluated heterogeneity by Center, race/ethnicity, and PON1 genotype.

Results: There was significant heterogeneity in the Center-specific estimates of association for ∑DAP and ∑DMP and the MDI (p = 0.09, and p = 0.05 respectively), as well as heterogeneity in the race/ethnicity-specific estimates for ∑DAP (p = 0.06) and ∑DMP (p = 0.02) and the MDI. Strong MDI associations in the CHAMACOS population per 10-fold increase in ∑DAP (β = – 4.17, 95% CI -7.00, -1.33) and ∑DMP (β = -3.64, 95% CI -5.97, -1.32) were influential, as were associations among Hispanics (β per 10-fold increase in ∑DAP = -2.91, 95% CI -4.71, -1.12). We generally found stronger negative associations of ∑DAP and ∑DEP with the 24 month MDI for carriers of the 192Q PON1 allele, particularly among blacks and Hispanics.

Conclusions: Data pooling was complicated by Center-related differences in subject characteristics, eligibility, and changes in regulations governing residential use of OPs during the study periods. Pooled summary estimates of prenatal exposure to OPs and neurodevelopment should be interpreted with caution due to significant heterogeneity in associations by Center, race/ethnicity and PON1 genotype. Subgroups with unique exposure profiles or susceptibilities may be at higher risk for adverse neurodevelopment following prenatal exposure.

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