Tracing surface-adhered and internalized microplastics in leafy vegetables across urban and rural agroecosystems:...

This study provides the first comprehensive assessment of surface-adhered and internalized microplastics (MPs) in eleven commonly consumed leafy vegetables from urban and rural agroecosystems in Bangladesh. We aimed to systematically investigate the occurrence, characteristics, and human exposure risks of surface-adhered and internalized MPs in these leafy vegetables. Surface MPs were removed via a triple-step protocol of soaking, ultrasonication, and sieving, while internal MPs recovered through Wet Peroxide Oxidation (WPO) and density separation. Polymer composition was determined using ATR-FTIR spectroscopy. Total MPs abundance ranged from 0.69 to 10.52 MPs/cm² (mean 3.96 ± 2.58), with urban samples (0.92-10.52 MPs/cm²) significantly exceeding rural levels (0.69-6.96 MPs/cm²; ANOVA: p < 0.05). Washing removed 54-91 % of surface MPs, yet internal MPs persisted at 0.22-3.44 MPs/cm² (mean 1.29 ± 0.99). Fibers dominated the identified MPs (>88 %), which were primarily composed of polyethylene (50-53 %) and polypropylene (23-25 %). Multivariate analyses indicated rural contamination originated from agricultural plastics (e.g., mulch films), while urban sources included textiles and packaging. Pollution load indices indicated extreme contamination (Total MPs: 171.65-774.83, Internal MPs: 95.38-463.54), whereas polymer hazard indices suggested a moderate hazard level (Total MPs: 12.37-24.96, Internal MPs: 7.16-33.55). The estimated daily intake for adults (Total MPs: 4.86-106.71, Internal MPs: 1.86-39.38MPs/kg/day) and children (Total MPs: 7.20-158.11, Internal MPs: 2.76-58.35MPs/kg/day) exceeded values reported for other foods. These findings demonstrate that leafy vegetables are significant vectors for human MP exposure, underscoring an urgent need for improved agroecosystem management and enhanced food safety monitoring.