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

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 > 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.