Prenatal Pesticide Exposure and Neurodevelopment

Source: Conejo-Bolaños LD , Mora AM , Hernández-Bonilla D , et al . Prenatal current-use pesticide exposure and children’s neurodevelopment at one year of age in the Infants’ Environmental Health (ISA) birth cohort, Costa Rica. Environ Res. 2024;249:118222; doi: 10.1016/j.envres.2024.118222.Investigators from multiple institutions conducted a study to assess the association between prenatal exposure to commonly used pesticides and neurodevelopment. For the study, they reviewed data collected as part of Infants’ Environmental Health (ISA, based on the acronym in Spanish) cohort. For ISA, 451 pregnant women from Costa Rica were enrolled in 2010 and 2011. Eligible women were >15 years old, <33 weeks pregnant, and lived within 5 km of a banana plantation. In addition to collection of demographic and medical information, 1–3 urine samples were collected during pregnancy and analyzed for biomarkers of pesticides. Participants in the current study were children born to the women in the ISA cohort who had their neurodevelopment assessed at approximately 1 year of age using the Bayley Scales of Infant and Toddler Development, third edition (BSID-III). Prenatal exposure to 2,4-D, synthetic pyrethroids, pyrimethanil, thiabendazole, and chlorpyrifos, was documented based detection of the parent compound or a metabolite in the mothers of study infants during pregnancy. Separate linear regression models were used to assess the association between exposure to each of these pesticides and BSID-III scores for the language, motor, cognitive, and socioemotional domains, after controlling for multiple possible confounders. The analyses evaluated the association in all participants, and separately for girls and boys.Data were analyzed on 355 children whose mothers contributed at least 1 urine sample for assay and in whom the BSID-III was completed. Overall, 94% were born at term, and the mean age of their mothers was 24.1 ±6.6 years; 66% of the mothers were living below the Costa Rican poverty line. The mean age of study participants when they completed the BSID-III was 13.8 ±1.6 months. Mean scores for the language, motor, cognitive, and socioemotional domains of the BSID-III were 90.1, 97.3, 98.2, and 90.3, respectively. Prenatal exposure to 2,4-D was associated with significantly lower scores on the language and motor components of the BSID-III. The association was present in all participants and in boys; no significant effect was observed when the analysis was limited to girls only. Exposure to chlorpyrifos was associated with significantly lower motor scores, but only in boys, and girls who were exposed to pyrimethanil had significantly lower language scores. No effects in the cognitive or socioemotional domains were observed with any of the pesticides, and exposure to either synthetic pyrethroids or thiabendazole was not associated with a significant association with any of the outcomes.The authors conclude that prenatal exposure with pesticides that are commonly used was associated with negative effects on neurodevelopment when assessed at 1 year of age.Dr Bechtel has disclosed no financial relationship relevant to this commentary. This commentary does not contain a discussion of an unapproved/investigative use of a commercial product/device.Exposure to pesticides can have detrimental effects on human health.1 For example, children exposed to indoor or outdoor home insecticides or herbicides may have a higher risk of childhood hematopoietic cancers compared to those not exposed. (See AAP Grand Rounds. 2015;34[6]:66.)2 Other investigators have found that prenatal exposure to organophosphate, pyrethroid, or carbamate pesticides are associated with an increased risk of neurodevelopmental disorders in preschool children. (See AAP Grand Rounds. 2015;33[2]:16.)3In the current study, the authors found an association between prenatal exposure to 2,4-D, chlorpyrifos, and pyrimethanil and infant neurodevelopment during their first year of life. Higher prenatal urinary 2,4-D concentrations were associated with lower language and motor composite scores among all children at 1 year of age. Higher prenatal concentrations of the metabolite of chlorpyrifos were associated with lower cognitive composite scores among all children and lower motor composite scores among boys but not girls. Higher maternal urinary concentrations of the pyrimethanil metabolite were associated with lower scores for language abilities in girls. The Bayley-III composite scores for all infants at 1 year of age approached 100 for motor and cognitive scores, while language and socioemotional scores were lower. Girls had slightly higher language and socioemotional scores compared to boys.The study, however, has several significant limitations: Prenatal exposure to common pesticides is associated with neurodevelopmental delays in infants at 12 months of age born to poor, agrarian mothers.A virtually concurrent, cross-sectional US study found that higher county-levels of atrazine were associated with higher rates of gastroschisis.4 Although banned in numerous countries, atrazine is the second-most-commonly used herbicide in the US.