Occupational metal exposure and systemic inflammation among recycling workers engaged in domestic waste sorting, shredding, and material extraction.

INTRODUCTION

The amount of metal-containing waste being recycled and the number of employees in these recycling industries, an important part of the green transition, are increasing. It is essential to ensure that the workers are not exposed to harmful levels of metals during work. This study aims to document current biomarker exposure levels of metals and investigate the association between metals and inflammatory biomarkers among recycling workers.

METHODS

In this cross-sectional study, concentrations of lead, mercury, copper, cobalt, cadmium, chromium, manganese, nickel, and selenium were measured in urine pre-shift and whole blood post-shift among 101 recycling workers from 12 companies mainly recycling domestic waste. Serum concentrations of inflammatory markers (CRP, SAA, CC16, IL1B, IL2, IL4, IL5, IL6, IL8, IL10, IL13, and TNF) were measured. Associations between metal levels by work task, waste fractions, and inflammatory markers were explored by linear mixed-effects models.

RESULTS

Overall, we observed no substantial differences in metal concentrations between production and administrative workers. However, nickel and lead blood levels, and mercury urine levels were highest among workers handling metal and electronic/hazardous waste. Compared to administrative workers, metal levels were in adjusted analysis increased in some job tasks (nickel for paper/cardboard; lead and cadmium for plastic/biowaste/metals; mercury for electronics/hazardous waste handling). After adjusting for potential confounders, including endotoxins, increasing lead, nickel, and copper blood levels were associated with increasing concentrations of CRP, SAA, IL1B, IL8, and/or TNF.

CONCLUSIONS

We found overall no increased levels of metals among recycling workers. However, the highest levels of metals were found among workers handling metal and electronics/hazardous waste. Nickel, lead, and copper in blood were associated with increased inflammatory markers, but for other metals the associations were less clear. The findings highlight metal exposure from specific waste fractions and underscore the need for further research on potential health effects in the growing recycling industry.