Genotoxicity and inflammatory potential of stainless steel welding fume particles: an in vitro study on standard vs Cr(VI)-reduced flux-cored wires and the role of released metals

Abstract

Welders are daily exposed to various levels of welding fumes containing several metals. This exposure can lead to an increased risk for different health effects which serves as a driving force to develop new methods that generate less toxic fumes. The aim of this study was to explore the role of released metals for welding particle-induced toxicity and to test the hypothesis that a reduction of Cr(VI) in welding fumes results in less toxicity by comparing the welding fume particles of optimized Cr(VI)-reduced flux-cored wires (FCWs) to standard FCWs. The welding particles were thoroughly characterized, and toxicity (cell viability, DNA damage and inflammation) was assessed following exposure to welding particles as well as their released metal fraction using cultured human bronchial epithelial cells (HBEC-3kt, 5–100 µg/mL) and human monocyte-derived macrophages (THP-1, 10–50 µg/mL). The results showed that all Cr was released as Cr(VI) for welding particles generated using standard FCWs whereas only minor levels (< 3% of total Cr) were released from the newly developed FCWs. Furthermore, the new FCWs were considerably less cytotoxic and did not cause any DNA damage in the doses tested. For the standard FCWs, the Cr(VI) released in cell media seemed to explain a large part of the cytotoxicity and DNA damage. In contrast, all particles caused rather similar inflammatory effects suggesting different underlying mechanisms. Taken together, this study suggests a potential benefit of substituting standard FCWs with Cr(VI)-reduced wires to achieve less toxic welding fumes and thus reduced risks for welders.

Modelled lung deposition and retention of welding fume particles in occupational scenarios: a comparison to doses used in vitro

“…The MPPD model has previously been used to correlate lung deposition of silver nanoparticles to reported in vitro toxic threshold of ionic silver by assuming dissolution to a certain extent (Smith and Skinner 2021). The release of hexavalent chromium has for instance been suggested to be largely involved in welding particle toxicity by us (McCarrick et al 2019(McCarrick et al , 2021 and others (Antonini et al 1999(Antonini et al , 2005McNeilly et al 2004), therefore this approach may be useful also for welding induced toxicity. To further refine dose estimates, MPPD models can also be combined with PBPK models, which has been carried out to derive target dose of manganese in human brain after inhalation of welding fumes (Ramoju et al 2017).…”

“…The in vitro doses used in the comparison were employed under submerged conditions for human bronchial epithelial cells (HBEC-3kt) (McCarrick et al 2021). Other in vitro studies investigating welding fume toxicity have applied nominal doses varying between 2 and 250 μg/mL with a lowest dose generally ranging from 2 to 6.25 μg/mL (Antonini et al 1999(Antonini et al , 2005McNeilly et al 2004;Leonard et al 2010;McCarrick et al 2019;Hedberg et al 2021). However, nominal media concentrations have been argued to be considered as measures of exposures rather than dose due to that they do not accurately reflect the dose in contact with the cells (Teeguarden et al 2007;Groothuis et al 2015).…”

“…Using in vitro systems, we and others have demonstrated toxic effects in cultured cells exposed to welding fume particles, including cytotoxicity, oxidative stress, DNA damage and inflammatory effects (Antonini et al 1999(Antonini et al , 2005McNeilly et al 2004;Leonard et al 2010;Shoeb et al 2017;McCarrick et al 2019McCarrick et al , 2021Hedberg et al 2021). In vitro toxicity test methods offer the potential for efficient, economical and ethical hazard testing as an alternative to animal testing.…”

New weldable 316L stainless flux-cored wires with reduced Cr(VI) fume emissions: part 2—round robin creating fume emission data sheets

“…Lab A used air-sealed packaging for the filters directly after fume collection and stored the filters in a desiccator (lower relative humidity than 10%) prior to and between analyses. Using this procedure, the Cr(VI) release was not altered for filters tested directly and after one year of storage [19,43].…”

“…The possibility to reach the highest productivity in all positions with the FCAW process serves as a driving force to decrease the emission rate and the amount of Cr(VI) in the welding fume. Experimental 316L flux-cored wires for reduced Cr(VI) in the fume emissions were investigated in an earlier work [43]. The results demonstrated that fumes containing lower amounts of Cr(VI) were less acute toxic regarding both cytotoxicity and DNA damage compared to the standard wires.…”