Inhalation of iron-abundant gas metal arc welding-mild steel fume promotes lung tumors in mice

Abstract

Welding fumes were reclassified as a Group 1 carcinogen by the International Agency for Research on Cancer in 2017. Gas metal arc welding (GMAW) is a process widely used in industry. Fume generated from GMAW-mild steel (MS) is abundant in iron with some manganese, while GMAW-stainless steel (SS) fume also contains significant amounts of chromium and nickel, known carcinogenic metals. It has been shown that exposure to GMAW-SS fume in A/J mice promotes lung tumors. The objective was to determine if GMAW-MS fume, which lacks known carcinogenic metals, also promotes lung tumors in mice. Male A/J mice received a single intraperitoneal injection of corn oil or the initiator 3-methylcholanthrene (MCA; 10 μg/g) and, one week later, were exposed by whole-body inhalation to GMAW-MS aerosols for 4 hours/day x 4 days/week x 8 weeks at a mean concentration of 34.5 mg/m. Lung nodules were enumerated by gross examination at 30 weeks post-initiation. GMAW-MS fume significantly increased lung tumor multiplicity in mice initiated with MCA (21.86 ± 1.50) compared to MCA/air-exposed mice (8.34 ± 0.59). Histopathological analysis confirmed these findings and also revealed an absence of inflammation. Bronchoalveolar lavage analysis also indicated a lack of lung inflammation and toxicity after short-term inhalation exposure to GMAW-MS fume. In conclusion, this study demonstrates that inhalation of GMAW-MS fume promotes lung tumors in vivo and aligns with epidemiologic evidence that shows MS welders, despite less exposure to carcinogenic metals, are at an increased risk for lung cancer.

Welding Fumes, a Risk Factor for Lung Diseases

“…Male A/J mice were exposed by whole-body inhalation to GMAW-MS aerosol for 4 h/day for 4 days/week for 8 weeks at a mean concentration of 34.5 mg/m 3 . Results highlighted an increasing of lung tumor multiplicity and absence of lung inflammation [58]. To identify metal components that are most toxic and tumorigenic, metal components of GMAW fumes were investigated.…”

Regeneration of dust filters challenged with metallic nanoparticles: Influence of atmospheric aging

“…The efficient removal of these particles is of importance to ensure air quality in work places and to prevent their release into the environment due to their toxicity. Workers exposure to metallic fumes has been drawing a lot of attention recently (Falcone et al, 2018;Michalek et al, 2019;Bakri et al, 2019), especially since the classification of welding fumes as "Carcinogenic to humans" by the International Agency for Research on Cancer (Guha et al, 2017). It is estimated that millions of workers across the world are exposed to these fumes.…”

Critical Physicochemical Properties for Nanoparticle Toxicity: Impact of Surface Coating and Size on Particle-Induced Cell Transformation and Inflammatory Response

“…It is known there is some risk of occupational exposure to IONP 20,21 , with unknown or unreported adverse outcomes. In laboratory settings, some researchers report no effect following IONP exposure [93][94][95] , whereas others indicate that IONP or IONP-containing materials may induce genotoxicity 30,31,98,143 , neoplastic-like cell transformation 99,144 , in vivo tumor formation 145,146 , and neurotoxicity 147 .…”

“…GMA generated from mild steel welding (GMA-MS) contain roughly 80% iron/iron oxide particulates which fall within the nano-size range. GMA-MS exposure is associated with fibrotic lesions and elevated lung iron levels in humans 81 , as well as lung tumor development 145,146 and lung cancer progression 149 . Although GMA-MS contains largely insoluble iron, it still provides a useful reference for potential IONP-induced adverse outcomes, particularly those related to the induction or promotion of lung cancer.…”

“…The aims of this study were to assess the potential for IONP to induce neoplastic-like cell transformation within the context of an occupationally relevant sub-chronic in vitro exposure model (low dose/long term), and to examine the potential protective qualities of an amorphous silica coating under these conditions. GMA-MS particles were used as a positive control, as they have been previously shown to promote carcinogenic outcomes in vivo 145,146 . Particle induced changes in intracellular iron, ROS production, and DNA damage associated with the cell transformation were also evaluated throughout the long term exposure.…”