Pneumoconiotic effects of welding-fume particles from mild and stainless steel deposited in the lung of the rat

Abstract

Rats were exposed to single periods of inhalation of fumes generated by arc welding. Two processes were compared: either manual metal arc (MMA) using flux-coated mild steel (MS) electrodes or metal inert-gas (MIG) welding with stainless steel (SS). Widespread but small deposits of fume particles were cleared effectively from alveoli and airways. Peribronchial and subpleural aggregates of particle-laden macrophages remained. More massive and persistent lung-burdens were established by intratracheal administration of suspensions of fume-particles (10 mg and 50 mg, single doses). Initial pneumonitis was attributed to irritant gases or soluble toxic components of particles. MIG-SS particle deposits were more persistent and lesions more severe, inhibition of phagocytosis or clearance and damage to epithelial cells being associated with possible toxic effects in macrophages. Both types of particle caused alveolar epithelial thickening, with proliferation of granular pneumocytes and exudation of lamellar material. Foam cells appeared in alveoli. Long-term effects (80-300 days) involved formation of nodular aggregates of particle-laden macrophages. Giant cells were formed. Nodules containing MIG-SS material were irregular and surrounded by collapsed and thickened epithelium. Soluble chromium or nickel constituents are cited as probable active agents producing effects resembling those of cytotoxic non-fibrogenic dusts, e.g., soluble silicas . MMA-MS particles produced low-grade fibrotic ( collagenised ) changes.

Pulmonary function abnormalities and airway irritation symptoms of metal fumes exposure on automobile spot welders

“…Severe inflammation and mild derangement of the alveolar wall was revealed in early stages of lung fibrosis, and less inflammation but marked derangement of the alveolar wall was observed in the middle or late stages. The interaction of several components of welding fumes including metal oxides and ozone, may lead to a complex pattern of damage to lung tissues after exceeding the clearance capacity of the bronchial and alveolar epithelium [Stern et al, 1983;Hicks et al, 1984;Muller and Grewe, 1992]. An increased inflammatory response initiates an over-load phenomenon especially after deposition of ultrafine particles of welding fumes [Donaldson et al, 1999].…”

Interstitial pulmonary fibrosis after severe exposure to welding fumes

“…In contrast, lung ®brosis of known particular etiology show ®brotic reactions of interstitial lung tissue with direct topographical relationship to mostly perivascular, peribronchiolar, and pleural dust deposits [Voss et al, 1991;Mu Èller and Verhoff, 2000;Verhoff and Mu Èller, 2000]. The interaction of several components of welding fumes including metal oxides and ozone, may lead to a complex pattern of damage to lung tissue after exceeding the clearance capacity of the bronchial and alveolar epithelium [Stern et al, 1983;Hicks et al, 1984;Mu Èller and Grewe, 1992]. By combining X-ray microanalysis (EDX) with SEM it is possible to determine the distribution of speci®c elements embedded in areas of lung tissue and to establish the close topographical relationship with interstitial ®brotic reactions [Guidotti et al, 1978;Morgenroth and Verhagen-Schro Èter, 1984;Funahashi et al, 1988;Mu Èller and Verhoff, 2000].…”

“…Several investigations of inhaled arc welding fumes in experimental animals have also shown ®brogenic effects after exposure, mostly of less than 2 years [Hicks et al, 1983;Hicks et al, 1984;Muhle et al, 1988Muhle et al, , 1990Yurui and Yu, 1988;Morrow et al, 1991;Last et al, 1993;Obersdo Èrster, 1995;Antonini et al, 1996]. The``overload phenomenon'' may explain the ®ndings of the close topographical relationship between welding fume associated lung dust burden embedded in interstitial ®brogenic reactions.…”

Physicochemical Characterization of Simulated Welding Fumes from a Spark Discharge System

“…Only few welding fume inhalation exposure systems have been developed because of the numerous different types of welding processes employed in the workplace and the difficulties with generating a fume with stable output over extended periods of time. Hicks et al (1984) used experienced welders to generate fumes from various welding types for the head-only exposure and the intratracheal instillation. Difficulties with this system included the need to hire experienced welders to operate the system and disruptions in output because the base metal and welding materials required replacement every few minutes.…”