Microplastic inhalation in waste management workers: evidence from nasal lavage and sputum analysis in a municipal...

Although landfills are considered significant sources of microplastics, workers' inhalation exposure has not yet been measured. This study provides direct evidence of microplastic inhalation among landfill workers by examining pre- and post-shift changes in respiratory samples and across occupational groups. 23 personnel were divided into three groups: office (n = 7), field (n = 12), and recycling plant (n = 4). Nasal lavage and induced sputum samples were collected before/after the work shift. Microplastics were extracted after digestion and density separation, identified under a stereomicroscope, and their polymer type was confirmed by Raman spectroscopy. Nonparametric tests were used to analyze intra- and inter-group differences. Microplastics were found in 100% of the samples, and their concentration increased significantly in both sample types after the shift. The mean particle count rose from 20.5 to 28.5 MPs/10 ml in nasal lavage and from 12.1 to 19.4 particles/10 ml in sputum (p < 0.001). Fibers were dominant (>70% pre-shift; >60% post-shift. Low-Density Polyethylene, polyamide, polypropylene and polyethylene Terephthalate constituted the main distribution of polymers. Regression models identified occupational exposure and smoking as the main determining factors for significantly increasing post-shift microplastic loads in both respiratory samples. The load of microplastics in nasal lavage and sputum was also highly correlated (r_s > 0.85). Occupational activity in landfills significantly increases the burden of inhalable microplastics and shows a clear pattern of increasing exposure with increasing occupational exposure (recycling > field > office). Nasal lavage is a valid, less invasive indicator for occupational monitoring and extensive epidemiological assessments.