Higher respiratory microplastic burden in patients with lung malignancy: A prospective bronchoscopy study.

Microplastics are an emerging airborne environmental exposure, but their distribution within human respiratory compartments remains poorly defined. In this prospective observational study, we investigated the presence, burden, and characteristics of microplastics in bronchoalveolar lavage (BAL) fluid and paired airway-tissue samples obtained during diagnostic bronchoscopy in 100 adults, including 50 patients with newly diagnosed lung malignancy and 50 non-malignant controls. Suspected microplastics were identified using alkaline digestion, filtration, stereomicroscopy, and transmitted-light microscopy, with micro-Raman spectroscopy performed on a representative subset. Across 150 respiratory specimens, 232 suspected microplastic particles were identified optically, with at least one such particle observed in 70% of patients and 60% of specimens. Raman analysis of 117 particles identified 19 polymer-confirmed particles and 46 with synthetic pigment-dominated spectra without polymer confirmation; 52 yielded fluorescence-only spectra. In the BAL cohort, suspected microplastics were detected more frequently in the malignancy group than in controls and particle counts were higher. In multivariable analyses adjusting for age, sex, and cumulative smoking exposure, higher optically derived particle burden remained associated with malignancy. In the paired subset, overall detection frequency and total burden were higher in the malignancy group, and, within the malignancy subgroup, higher BAL particle counts were associated with lower tissue particle counts. Suspected microplastics were detectable across multiple respiratory compartments, with differences observed between airway-accessible and tissue-associated particles. These findings support the feasibility of assessing microplastics in clinically obtained respiratory samples and highlight the importance of integrated airway-tissue approaches for characterizing the distribution of inhaled environmental particles in the human lung.