Pneumotoxic effects of exposure to welding fumes: cross-week evaluation of Clara cell protein and manganese, in blood of shipyard workers

摘要

Welders exposed to fumes containing manganese (Mn) develop inflammatory changes in the lower airways. However, the assessment of pneumotoxic effects of welding fumes is limited because of the lack of adequate biomarkers of early toxic effects. Bronchiolar epithelial Clara cell secretory protein (CC16) has a potential role in pulmonary inflammation, and the fall in CC16 serum level is a useful biomarker of the dysfunction of the respiratory system. In the present study, a feasibility of CC 16 as an early biomarker of Mn-induced pneumotoxicity has been evaluated. Cross-week determination of Mn concentrations in plasma and urine as well as determination of CC16 and hyalu-ronic acid (HA), a marker of pulmonary inflammation, were performed in welders exposed to welding fumes and in unexposed shipyard workers. In addition, pulmonary function tests (FVC, FEV-1 FEF-50) were done in both groups, and airborne Mn levels in working environment were determined. The results demonstrate the increased prevalence of Mn levels in blood exceeding 8 mug/dm~3 in a group exposed to welding fumes. Furthermore, increased prevalence of respiratory dysfunction in subjects with Mn levels exceeding 8 ug/dm~3 was observed. On the basis of our data, the threshold limit for Mn concentration in blood is about 8 mug/dm~3. Serum CC16 concentrations were markedly decreased in welders in whom significant reductions of FEF-50 (less than 60% of predicted value) were observed. In addition, within the range exceeding the threshold value (> 8 ug/dm~3) we found close negative correlation between Mn and CC 16 concentrations. Thus, the present study demonstrates that CC16 is a good peripheral biomarker of early pneumotoxic effect produced by welding fumes.