Lung Toxicity Profile of Inhaled Copper-Nickel Welding Fume in A/J Mice

The process of stainless steel welding creates fumes rich in carcinogenic metals such as chromium (Cr). Welding consumables devoid of Cr are being produced in attempt to limit worker exposures to potentially toxic and carcinogenic metals. The study objective was to characterize a copper-nickel (Cu-Ni) fume generated using gas metal arc welding (GMAW) and determine the pulmonary deposition and toxicity of the fume in mice exposed by inhalation. Male A/J mice (6 – 8 weeks of age) were exposed to air or Cu-Ni welding fumes for 2 (low deposition) or 4 (high deposition) hours/day for 10 days. Mice were sacrificed and bronchoalveolar lavage (BAL), macrophage function, and histopathological analysis were performed at various timepoints post-exposure to evaluate resolution. Characterization of the fume indicated that most of the particles were between 0.1 and 1 µm in diameter, with a mass median aerodynamic diameter of 0.43 µm. Metal content of the fume was primarily Cu (~76%) and Ni (~12%). After exposure, BAL macrophages had a reduced ability to phagocytose E. coli at 1 and 7 days and lung cytotoxicity was evident and significant (>12-19% fold change). Loss of body weight was also significant at these two early timepoints. Lung inflammation, the predominant lesion identified by histopathology, was observed as a subacute response early that progressively resolved by 28 days with only macrophage aggregates remaining late (84 days). Future studies are planned to investigate the tumorigenic potential of Cu-Ni fume in A/J mice.Read less