Rationale: Many welders experience bronchitis, metal fume fever, and lung function changes. The objective was to assess the effect of mild steel welding fume (MSWF) inhalation on lung injury, inflammation, defense responses, and fate of inhaled metals. Methods: Sprague-Dawley rats were exposed to MSWF at a concentration of 40 mg/m^3 x 3 hr/d x 3 or 10 d using a novel robotic welding fume generator. Controls were exposed to air. To assess lung defense responses, a group of animals were intratracheally inoculated with 5 x 10^4 Listeria monocytogenes 1 d after the last daily exposure. Welding particles were collected during exposure, and chemical composition and particle size were determined. After exposure, parameters of lung injury (lactate dehydrogenase and albumin), inflammation (PMN influx), and host defense (bacterial clearance) were measured. Also, multiple organs were recovered for metal analysis to assess fate of inhaled panicles. Results: The particles were composed primarily of Fe (80.6 %) and Mn ( 14.7 %) with a mass median aerodynamic diameter of 0.31 micro m. No significant difference was observed in lung injury or inflammation after MSWF inhalation at 1, 4, and 11 d after the last exposure. However, there were significantly more bacteria at 3 d after infection in the lungs of the animals exposed to MSWF compared to air controls. Significant elevations in lung Fe and Mn, liver Fe, and kidney Mn were observed after 10 d of exposure to MSWF compared to air. Conclusions: Acute exposure of rats to MSWF had no effect on injury and inflammation, but suppressed lung defense responses after infection. Also, metals in MSWF may translocate from the lungs to other organs, possibly causing systemic effects. Chronic inhalation studies are needed to further examine the health effects and fate of inhaled welding fume.
Pulmonary-system-disorders; Pulmonary-disorders; Respiratory-irritants; Respiratory-system-disorders; Alveolar-cells; Lung-cells; Lung-disorders; Welders-lung; Welding-industry; Metal-compounds; Metal-fume-fever; Metallic-compounds; Dust-particles; Particulate-dust; Bacterial-infections; Inhalation-studies