Comparison of stainless and mild steel welding fumes in generation of reactive oxygen species

Abstract

BackgroundWelding fumes consist of a wide range of complex metal oxide particles which can be deposited in all regions of the respiratory tract. The welding aerosol is not homogeneous and is generated mostly from the electrode/wire. Over 390,000 welders were reported in the U.S. in 2008 while over 1 million full-time welders were working worldwide. Many health effects are presently under investigation from exposure to welding fumes. Welding fume pulmonary effects have been associated with bronchitis, metal fume fever, cancer and functional changes in the lung. Our investigation focused on the generation of free radicals and reactive oxygen species from stainless and mild steel welding fumes generated by a gas metal arc robotic welder. An inhalation exposure chamber located at NIOSH was used to collect the welding fume particles.ResultsOur results show that hydroxyl radicals (.OH) were generated from reactions with H2O2 and after exposure to cells. Catalase reduced the generation of .OH from exposed cells indicating the involvement of H2O2. The welding fume suspension also showed the ability to cause lipid peroxidation, effect O2 consumption, induce H2O2 generation in cells, and cause DNA damage.ConclusionIncrease in oxidative damage observed in the cellular exposures correlated well with .OH generation in size and type of welding fumes, indicating the influence of metal type and transition state on radical production as well as associated damage. Our results demonstrate that both types of welding fumes are able to generate ROS and ROS-related damage over a range of particle sizes; however, the stainless steel fumes consistently showed a significantly higher reactivity and radical generation capacity. The chemical composition of the steel had a significant impact on the ROS generation capacity with the stainless steel containing Cr and Ni causing more damage than the mild steel. Our results suggest that welding fumes may cause acute lung injury. Since type of fume generated, particle size, and elapsed time after generation of the welding exposure are significant factors in radical generation and particle deposition these factors should be considered when developing protective strategies.

Lung biodurability and free radical production of cellulose nanomaterials

“…If the particle surface has transition metal present, such as Fe, then it may generate radicals through a Fenton-like reaction. Silica particles, chromium and welding fumes all generated free radical production under similar exposure conditions (Leonard et al, 2000, 2010; Vallyathan et al, 1999). In order for particles to generate free radicals in a cellular system, the cell must first recognize and react with the particles.…”

Incidence of rhinitis and asthma related to welding in Northern Europe

“…The pathophysiological mechanism for asthma development when working in stainless steel is not known, but the higher content of chromium (15-30%) and nickel (5-10%), the generation of higher levels of oxygen radicals, and that these metals may deposit for a longer time in the lung tissue, are thought to be important factors, and in some cases it is found positive skin prick tests to these metals giving evidence for a possible IgE-mediated specific mechanism [16,17]. A differentiation in the incidence and hazard ratio was not seen with adult-onset rhinitis in our study and may signify other mechanisms in the upper airways than in the lower airways; probably non-specific irritative mechanisms.…”

“…A characteristic aspect of the particles initially formed in the welding process is the small size, less than 0.5 µm [14,15]. They may therefore be anticipated for the most part to pass by the nasal mucosa, although LEONARD et al [16] in a paper on stainless and mild steel welding stress that welding fumes consist of a wide range of complex metal oxide particles which may form large agglomerated chains of particles of different sizes, and thus can be deposited in all regions of the respiratory tract. In welding fumes there are also irritative gases of which some are very water soluble (goes to upper airways) and some less water soluble (goes more to lower airways), and this may also in part explain why we find indications of rhinitis development in this occupation with mainly low molecular weight exposure.…”

Bcl-2 Overexpression Inhibits Generation of Intracellular Reactive Oxygen Species and Blocks Adriamycin-induced Apoptosis in Bladder Cancer Cells

“…Reactive oxygen species (ROS), such as O2·-, ·OH, and H 2 O 2 , are the principal species of intracellular oxidants (Leonard et al, 2010). They are generated as by-products of electron transport through the mitochondrial respiratory chain as well as by γ-ray and ultraviolet light irradiations (Kaur et al, 2001).…”