Epidemiology studies have been unable to correlate chronic adverse lung effects associated with exposure to specific welding fumes generated from different processes. The objective of this study was to use an animal model to compare the persistence of deposited particles and the inflammatory potential after inhalation of stainless steel welding fume (SS WF) or mild steel welding fume (MS WF), the two most common fumes used in U.S. industry. Male Sprague-Dawley rats were exposed to 40 mg/m3 of SS WF or MS WF for 3 hr/day for 3 days. Controls were exposed to filtered air. Generated fume was collected in the breathing zone of the animals, and particle size, morphology, and composition were determined. Bronchoalveolar lavage was done on days 1, 4, 8, 11, 22, and 43 after the last exposure to assess lung injury/inflammation and to recover lung phagocytes. SS WF and MS WF were similar in particle morphology and size with mass median aerodynamic diameters of 0.26 and 0.31 um, respectively. Chemical composition of the fumes was different- SS WF: 57 % Fe, 20 % Cr, 14 % Mn, 9 % Ni; MS WF: 81 % Fe, 15 % Mn. There was no effect of MS WF on lung injury/inflammation at any time point compared to air control. Lung injury was elevated through 11 days after exposure to SS WF, whereas inflammation was delayed and not significantly increased until day 11 compared to control. SS WF also was associated with greater recovery of welding fume-laden cells from the lungs at all time points compared to the MS WF group. Few cells contained MS WF particles at 22 days, whereas 25 % of cells recovered from the SS WF group still contained particles at 43 days. Thus, it appears that clearance of SS WF is impaired compared to MS WF, which may explain the delayed and persistent inflammatory response. These observations could be related to the presence of insoluble carcinogenic metals in SS WF, such as Cr or Ni, which may play a role in the development of chronic lung disease.
Biological-effects; Biological-factors; Breathing-zone; Carcinogenicity; Cell-metabolism; Cellular-reactions; Epidemiolog; Exposure-assessment; Exposure-levels; Exposure-methods; Inhalation-studies; Laboratory-animals; Lung-disorders; Lung-function; Lung-irritants; Microscopic-analysis; Microscopy; Metal-fumes; Particulates; Pulmonary-system-disorders; Pulmonary-disorders; Pulmonary-function-tests; Particle-aerodynamics; Particulate-dust; Respiratory-hypersensitivity; Respiratory-irritants; Respiratory-system-disorders; Statistical-analysis; Welders-lung; Welding-industry
The Toxicologist. Society of Toxicology 48th Annual Meeting and ToxExpo, March 15-19, 2009, Baltimore, Maryland