Microbial exposure during recycling of domestic waste: a cross-sectional study of composition and associations with inflammatory markers.

Objectives: This study aims to investigate (1) the microbial community composition by work characteristics and (2) the association between microbial genera level and inflammatory markers among recycling workers.

Methods: In this cross-sectional study, inhalable dust was collected with personal samplers from 49 production (86 samples) and 10 administrative workers (15 samples). Four groups of micro-organisms were identified down to species-level (aerobic and anaerobic bacteria, and fungi grown at 25°C and 37°C). Inflammatory markers were measured in serum collected at the end of the work shift. Microbial community composition was investigated using redundancy analysis and heatmaps. Associations between the most prevalent microbial genera and inflammatory markers were explored by mixed-effects regression.

Results: Community composition of all groups of micro-organisms except fungi (37°C) differed between production and administrative workers and by type of waste and season among the production workers. Overall, Bacillus, Staphylococcus, Aspergillus and Penicillium were the most prevalent genera. CC16 concentrations increased with Penicillium genus level, C reactive protein and serum amyloid A with Staphylococcus, interleukin 2 (IL-2) and tumour necrosis factor with Bacillus, and IL-8 with Aspergillus. IL-1B decreased with Staphylococcus genus level. Remaining analyses showed no statistically significant associations between microbial genera level and inflammatory markers.

Conclusions: Recycling workers are exposed to different compositions of microbial species than administrative workers depending on the type of waste handled and season. Specific systemic inflammatory effects were suggested for a limited number of microbial genera that need to be corroborated by future studies.