Microplastics in the Bronchoalveolar Lavage Fluid of Chinese Children: Associations with Age, City Development, and Disease Features

This study characterized the occurrence patterns of microplastics (MPs) in the bronchoalveolar lavage fluid (BALF) of children with pulmonary diseases. MPs were detected in 89.6% of BALF samples with an average of 4.31 ± 2.77 items/10 mL, supporting the hypothesis that inhalation is a significant pathway of airborne MP exposure to pediatric lungs. Inhaled MPs were predominantly composed of 10 polymer types [e.g., polypropylene (41.9%), polyethylene (19.4%), and polyester (13.6%)], with the majority being smaller than 20 μm. MP levels in BALF exhibited a negative correlation with children's age, probably owing to the preferential crawling and tumbling actions in indoor environments and underdeveloped immune systems of young children. Participants living in urban areas suffered from higher pulmonary MP exposure, likely due to higher environmental levels, compared with suburban/rural residents (P < 0.05). Although no significant differences were found between MP levels in pediatric lungs with community-acquired pneumonia (CAP) and asthma (P > 0.05), the severe CAP group displayed significantly higher MP contamination than the nonsevere group (P < 0.05), indicating that some yet undiscovered relationship(s) between inhaled MPs and pediatric pulmonary diseases may exist.