Urinary microplastic contaminants in primary school children: Associations with behavioral development.

Behavioral problems in children have been increasingly linked to environmental exposures. Microplastics (MPs), prevalent in urban environments, are emerging contaminants with potential neurodevelopmental effects. This study examines the relationship between urinary MPs and behavioral outcomes among primary school children in Shenyang, China. This study was conducted involving 1000 children aged 6-9 years from 40 schools across Shenyang. Urinary MPs, including polyamide (PA), polypropylene (PP), and polyvinyl chloride (PVC), were quantified using optical microscopy. Behavioral outcomes were assessed using the Strengths and Difficulties Questionnaire (SDQ). Mixed-effect negative binomial models evaluated associations between MPs and SDQ scores, adjusting for relevant covariates. The median urinary total microplastic concentration was 9 particles/100 mL. Increased particle counts of urinary MPs were positively associated with higher scores for emotional problems, conduct problems, hyperactivity, and peer problems. Total microplastic levels were linked to increased emotional symptoms (estimate: 0.128, 95 % CI: 0.065-0.198, p < 0.001), conduct problems (estimate: 0.231, 95 % CI: 0.140-0.323, p < 0.001), and hyperactivity (estimate: 0.168, 95 % CI: 0.101-0.235, p < 0.001). Peer relationship issues were also elevated with higher urinary microplastic levels (estimate: 0.206, 95 % CI: 0.133-0.271, p < 0.001). Conversely, prosocial behaviors declined with increased microplastic concentrations (estimate: -0.125, 95 % CI: -0.192 to -0.052, p = 0.001). Stratified analyses indicated no significant differences in these associations between boys and girls. Overall, urinary microplastic concentrations were significantly associated with adverse behavioral outcomes in children, highlighting the potential neurodevelopmental risks of microplastic exposure.