Microplastic exposure and the role of dietary patterns in school-aged children

Microplastics (MPs) have permeated all aspects of human life. This study aimed to assess MP exposure in schoolchildren's urine and dietary patterns' role in it. We followed up 10-year-olds from the Ma'anshan Birth Cohort (MABC), using a Laser Direct Infrared instrument to qualitatively/quantitatively assess MP levels in 1,308 children's urine. The zero-inflated negative binomial (ZINB) model analyzed associations between the Mediterranean Diet Quality Index for Children and Adolescents (KIDMED) and MP exposure. A total of 19 types of MP particles were identified in urine samples. The median total MP abundance was 250 particles/mL, with an overall detection rate of 91.29%. Among all detected MP types, polytetrafluoroethylene (PTFE) exhibited the highest detection rate (50.19%). Small-sized particles (20-100 μm) accounted for 98.04% of all detected MPs. Increases in children's KIDMED index were associated with a greater probability of zero abundance in urine for polylactic acid (PLA), ethylene-vinyl acetate copolymer (EVA), and polyvinyl alcohol (PVA) (PLA: β (95% CI) = 0.094 (0.004, 0.184); EVA: β (95% CI) = 0.113 (0.027, 0.199); PVA: β (95% CI) = 0.058 (0.001, 0.115)). Additionally, increases in the KIDMED index were associated with higher non-zero abundance levels of polyamide (PA) and lower non-zero abundance levels of PTFE (PA: β (95% CI) = 0.063 (0.020, 0.106); PTFE: β (95% CI) = -0.057 (-0.096, -0.018)). In summary, 19 MP types were detected in children's urine, with this study identifying an association between the KIDMED index and exposure levels of several MPs.