Welding fume nanoparticles from solid and flux-cored wires: Solubility, toxicity, and role of fluorides

Y.S Hedberg,Z Wei,S Mccarrick,V Romanovski,J Theodore,E.M Westin,R Wagner,K.-A Persson,H.L Karlsson,I Odnevall Wallinder

doi:10.1016/j.jhazmat.2021.125273

Abstract

Welding fume particles are hazardous. Their toxicity likely depends on their composition and reactivity. This study aimed at exploring the role of sodium or other fluorides (NaF), which are intentionally added to flux-cored wire electrodes for stainless steel welding, on the solubility (in phosphate buffered saline) and toxicity of the generated welding fume particles. A multi-analytical particle characterization approach along with in-vitro cell assays was undertaken. The release of Cr(VI) and Mn from the particles was tested as a function of fluoride solution concentration. The welding fume particles containing NaF released significantly higher amounts of Cr(VI) compared with solid wire reference fumes, which was associated with increased cytotoxicity and genotoxicity in-vitro. No crystalline Na or potassium (K) containing chromates were observed. Cr(VI) was incorporated in an amorphous mixed oxide. Solution-added fluorides did not increase the solubility of Cr(VI), but contributed to a reduced Mn release from both solid and flux-cored wire fume particles and the reduction of Cr(VI) release from solid wire fume particles. Chemical speciation modeling suggested that metal fluoride complexes were not formed. The presence of NaF in the welding electrodes did not have any direct, but possibly an indirect, role in the Cr(VI) solubility of welding fumes.

Highlights

Welders without sufficient protection equipment are exposed to potentially hazardous welding fumes
Na and K may originate from fluorides that were intentionally added to the flux-cored wire (FCW) for controlled fluidity, viscosity, and arc stabilization during the welding process
This study aimed at exploring the role of NaF in flux-cored wire electrodes, as compared to solid wire electrodes, on the stainless steel welding fume composition, the solubility of Cr, Cr(VI), Mn, Ni, and Fe released from welding fume particles into phosphate buffered saline (PBS), cyto toxicity, and genotoxicity

Summary

Introduction

Welders without sufficient protection equipment are exposed to potentially hazardous welding fumes. A recent report commissioned by the Swedish Work Environment Authority (Andersson et al, 2019) estimates 71 death cases annually (based on 2016 data) in Sweden that could be directly related to welding fume (considering ischemic heart disease and lung cancer as death causes). This is more than the total annual death cases related to work accidents in all occu pations in Sweden. Welding fume consists of both potentially hazardous gases and particles, which often are nano-sized (Floros, 2018)

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