Yang and coworkers presented interesting data regarding an inflammatory response in rats exposed to manual metal arc stainless steel welding fumes (Yang et al., Citation2009). The rats inhaled total suspended particulate concentrations of 52 mg/m3 (low dose) and 85 mg/m3 (high dose) 2 h/day for 1 month. After a recovery period of 1 month, they were further exposed to 44 mg/m3 (low dose) and 80 mg/m3 (high dose) 2 h/day for 1 month. After both the first and second exposure periods, there were clear signs of pulmonary inflammation. After the first exposure, there was a clear increase of alveolar macrophages, polymorphonuclear cells (PMNs), and lymphocytes. The inflammation sign regarding the number of macrophages was consistent in both exposures, showing similar numbers of cells. On the contrary, the inflammation mediated by PMNs and lymphocytes was more intense in the second exposure compared with the first exposure. The authors did not find any signs of fibrosis in the alveolar spaces in any of the exposed groups. The authors discuss their observations in relation to a process of welding-fume-induced pneumoconiosis.
There are at least one case report (Wergeland et al., Citation2001) and several epidemiological studies showing an increased mortality among welders due to pneumonia (Beaumont et al., Citation1980), pneumococcal and unspecified lobar pneumonia (Coggon et al., Citation1994; Palmer et al., Citation2009).
The findings by Yang and coworkers in their animal model would further increase in interest if the discussion were widened to the possible relationship between welding fume exposure and the occurrence of pneumonia.
Declaration of interest
The author declares that there is no conflict of interest regarding this letter to the editor.
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