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

Sarah Mccarrick,Kjell-Arne Persson,Inger Odnevall,Valentin Romanovski,Elin M Westin,Zheng Wei,Klara Trydell,Yolanda S Hedberg,Hanna L Karlsson,Richard Wagner

doi:10.1007/s00204-021-03116-x

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.

Highlights

Welders are a large occupational group being exposed to welding fumes inevitably created during the welding process
Our findings demonstrate that Cr(VI)-reduced flux-cored wires (FCWs) were, less potent in inducing cytotoxicity and DNA damage in human lung cells compared to standard FCWs
Even though this study suggests a potential benefit of substituting standard FCWs with Cr(VI)-reduced wires to achieve less toxic welding fumes it should be noted that the risk for the welders is determined by the welding fume generation rate since this largely affects the level of exposure

Summary

Introduction

Welders are a large occupational group being exposed to welding fumes inevitably created during the welding process. Welding fumes have been associated with many respiratory health outcomes including bronchitis, airway irritation and inflammation (Antonini 2003; Riccelli et al 2020) and have recently been reclassified as group 1 carcinogens by the International Agency for Research on Cancer (IARC 2017). The use of proper ventilation or personal protection equipment may be impractical or ineffective, resulting in an inevitable exposure to high levels of welding fumes. The soluble fraction of stainless steel welding fume particles, being predominantly Cr, has been implied to be an important aspect in their toxicity (McNeilly et al 2004; Antonini et al 2005; Shoeb et al 2017). The understanding of the mechanisms by which welding fumes and the associated metals result in toxicity and carcinogenesis could aid in the development of safer welding equipment as well as in improved regulations of occupational exposures to welding fume

Objectives

Methods

Results

Discussion

Conclusion