Prenatal and childhood neonicotinoid exposure and neurodevelopment: A study in a young Taiwanese cohort

Neonicotinoid insecticides (NEOs) dominate the global pesticide market because of their low cost and effectiveness. However, epidemiological studies regarding the potential adverse health effects of exposure to NEOs before birth and in early childhood are limited. Therefore, this study investigated the associations between NEO exposure before birth and during early childhood and neurodevelopment. A total of 273 mother-child pairs were enrolled in this study. Mothers provided urine samples in the third trimester and breast milk during the first and third months of lactation. Their children provided urine samples and were evaluated for neurodevelopment by using the Bayley Scales of Infant and Toddler Development, Third Edition at 2-3 years (N = 96) and the Wechsler Preschool and Primary Scale of Intelligence, Fourth Edition (WPPSI-IV) at 4-6 years (N = 63). The sum of the concentrations of seven NEOs (ΣNEOs) and the relative potency factor of NEOs, based on comparison with imidacloprid (IMI_RPF), were used to assess total exposure to NEOs. Multivariate linear regression analyses were conducted to assess the associations between prenatal and childhood exposure to NEOs and neurodevelopment. The results of the analysis revealed that clothianidin (CLO) and thiamethoxam were the most common NEOs to which children in the Taipei metropolitan area were exposed and that exposure concentrations were high in the Taipei metropolitan area. Imidacloprid was the most frequently detected NEO during the postnatal period. Additionally, exposure to NEOs through breast milk was low. Exposure to CLO, ΣNEOs, and IMI_RPF in boys aged 4-6 years was negatively correlated with WPPSI-IV Fluid Reasoning Index. The results of this study indicate that exposure during the third trimester to NEOs does not affect neurodevelopment but that childhood exposure to NEOs may, especially for boys. Further studies with larger sample sizes are required to confirm the sex-specific associations between NEO exposure and neurodevelopment.