Association between maternal urinary neonicotinoid concentrations and child development in the Japan Environment and Children's Study.

Background: Recent studies have reported the effect of neonicotinoid (NEO) exposures on development in human. However, information about the risk of childhood development delays due to NEO exposures is limited.

Objectives: The study aimed to examine the association between NEO exposure and child development up to 4 years of age using data of the Japan Environment and Children's Study.

Methods: The study employed urinary NEO and metabolite concentrations in the first and second or third trimesters; the Japanese translation of the Ages and Stages Questionnaire (third edition; J-ASQ-3) scores on developmental delay in five domains, namely communication, gross motor skills, fine motor skills, problem solving, and personal-social characteristics from 6 months to 4 years of age; and self-reported questionnaire data. The associations between urinary NEO concentrations and J-ASQ-3 results were analysed using the treed distributed lag mixture model. A total of 8538 participants were included in statistical analyses.

Results: The determination rates of urinary acetamiprid-N-desmethyl (dm-ACE), clothianidin (CLO), dinotefuran (DIN) and thiamethoxam (THX) were greater than 50%. Median urinary dm-ACE, CLO, DIN and THX concentrations were 0.34, 0.14, 0.22 and 0.05 ng/ml, respectively, in samples collected during gestational weeks < 23, and 0.28, 0.12, 0.18 and 0.04 ng/ml, respectively, in those collected during gestational weeks ≥ 23. The binomial scores divided by the cut-off values of the J-ASQ were used in the treed distributed lag mixture model. The highest percentage for a domain with a value less than the cut-off value was 'problem solving' at 6 months of age among all the J-ASQ-3 scores (10.5%). There was no statistically significant association between maternal urinary dm-ACE, CLO, DIN and THX concentrations during pregnancy and the J-ASQ-3 results up to 4 years of age. Objective assessment of child development in different populations may be warranted to confirm our findings.