Species-resolved exposure to fungi and bacteria, dust, and endotoxin during recycling of diverse waste types and systemic inflammatory response in workers

The waste recycling workforce is growing across Europe. This study investigates the airborne exposure of workers recycling plastic, paper/cardboard, and electronic (e) waste, and examines whether serum levels of inflammatory markers correlate with exposure. Exposure was measured repeatedly and analysed for inhalable and respirable dust, inhalable endotoxin, fungi, and bacteria. Microorganisms were identified using MALDI-TOF MS on cultured microorganisms and bacteria by 16S rRNA marker-gene sequencing. Blood samples collected at the end of each workday were analysed for three markers of inflammation. Waste types/tasks had an impact on exposure levels for all exposures and temperature on exposure to anaerobic bacteria. Exposure levels to dust, endotoxin, and anaerobic bacteria differed between workers. Exposures were highest for those handling paper/cardboard and plastic waste. The alpha diversity indices for most exposures did not differ between types of waste handled, but eWaste was associated with a lower species richness. Beta diversity did not differ between indoor temperatures or waste types except for mesophilic bacteria and bacteria (NGS-data). The species Aspergillus niger, Penicillium brevicompactum, Bacillus cereus, and Staphylococcus equorum were frequently detected. Serum levels of inflammatory markers increased with increasing exposure to dust, fungi or Penicillium spp, and anaerobic bacteria, but did not correlate with bacterial biodiversity indices. The study suggests further investigations of the impact of daily inhalation of bacteria able to grow anaerobically and fungi. Based on the high exposure levels, and the association between exposure and biomarkers of inflammation, it is advisable to explore risk management strategies aimed at minimizing worker exposure.