Neonatal meconium reveals concurrent microplastic and metal exposure in an urban South Asian birth cohort

Abstract Neonatal meconium provides a non-invasive matrix for assessing prenatal or near-birth exposure to environmental contaminants. Although microplastics and metals have each been reported in human biological samples, integrated assessments of concurrent particle and metal exposure in meconium remain scarce, particularly in South Asia. In this cross-sectional biomonitoring study, meconium from 30 Cesarean-delivered neonates born in Dhaka, Bangladesh, was analyzed for microplastic occurrence, morphology, and polymer composition using stereomicroscopy, scanning electron microscopy, and Raman spectroscopy, and for fifteen metals using inductively coupled plasma mass spectrometry. Maternal breast milk from a subset of lactating mothers was analyzed as a complementary maternal exposure context. Microplastics were detected in all analyzable meconium samples (n=28), with a median burden of 149 particles/g wet weight, dominated by polyethylene terephthalate fragments and nylon fibers. All fifteen measured metals were also detected in all analyzable meconium samples, with median Pb and Cr concentrations of 1.18 and 3.92 µg/g dry weight, respectively. No microplastic-metal associations remained significant after multiple-testing correction, suggesting partly distinct exposure or accumulation pathways. Here, we show that neonatal meconium captures concurrent microplastic and metal exposure in an urban South Asian birth cohort. This study provides one of the first integrated meconium-based assessments of concurrent microplastic and metal exposure from the region and highlights meconium as a practical matrix for early-life biomonitoring.