Mild steel and stainless steel welding fumes elicit pro-inflammatory and pro-oxidant effects in first trimester trophoblast cells

Risk for lung-related diseases associated with welding fumes in an occupational population: Evidence from a Cox model

Background

Welding fumes are a risk factor for welder pneumoconiosis. However, there is a lack of population information on the occurrence of welding fume-induced lung cancer, and little is known about the welding fume pathogenesis.

Methods

Welding fume and metal ion concentrations were assessed in a vehicle factory in Wuhan. A Cox regression model estimated lung-related disease risk in workers by independent and combined factors.

Results

Workers' exposures were divided into four grades; the highest exposure was among the welders in the maintenance workshop, the highest Mn and Fe exposure was 4 grades, and the highest Cr exposure was 3 grades. Subgroup analysis found that the risk of lung-related disease was 2.17 (95% CI: 1.31-3.57, p < 0.05) in welders compared with non-welders, and the risk of pulmonary disease in male welders was 2.24 (95% CI: 1.34-3.73, p < 0.05) compared to non-welders. Smoking welders had a 2.44 (95% CI: 1.32-4.51, p < 0.01) higher incidence of lung-related diseases than non-welders. Total years of work as an independent protective factor for lung-related disease risk was 0.72 (95% CI: 0.66-0.78, p < 0.01). As an independent risk factor, high-high and high-low exposure had a 5.39 (95% CI: 2.52-11.52, p < 0.001) and 2.17 (95% CI: 1.07-4.41, p < 0.05) higher risk for lung-related diseases, respectively.

Conclusions

High welding fume exposure is a significant risk factor for lung-related disease in workers.

Pregnancy Outcome in Women Exposed to Metal Fume in Welding: A Canadian Cohort Study

OBJECTIVES

Welding is a physically demanding job that entails exposure to metal fume and particles. There is little information on the effect of welding exposures on the outcome of a pregnancy conceived during a period when a woman was employed as a welder.

METHODS

Women welders recruited to the Workers Health in Apprenticeship Trades-Metal and Electrical (WHAT-ME) study were followed-up every 6 months for up to 5 years (January 2011-August 2018), and every pregnancy recorded. At the first 6-month follow-up, a detailed questionnaire was completed for the most recent day in welding, and this information was collected again at each follow-up and also from questionnaires completed during pregnancy. The date of conception was estimated for each pregnancy and the job at that date identified. Exposures to ergonomic factors, work schedule and perceptions of noise, heat and cold were extracted for the job at conception. Exposures to metals (aluminum, chromium, manganese, and nickel) and particles in welding fume were estimated from previously validated exposure algorithms reflecting the welding process, base metal and consumables of the job at the conception date. The effects of exposures were estimated in multilevel multivariable models allowing for confounding.

RESULTS

There were 242 pregnancies conceived by a welder working in her trade, 87 were before the first follow-up, 3 were after first follow-up but detailed information was not collected, 22 of those potentially included in the assessment group were in-trade but not welding leaving 122 pregnancies in 90 welders for analysis. Of these 91 resulted in a live birth and 31 in a fetal loss (27 miscarriages and 4 stillbirths). Mean birth weight for live births was 3365 g and gestation 39.4 weeks. Final models showed that risk of fetal loss increased with manipulating heavy objects [odds ratio (OR) = 5.13, 95% confidence interval (CI) 2.04-12.92], whole-body vibration (OR = 5.86, 95% CI 1.81-18.92), a higher rating for noise exposure intensity (OR = 1.52, 95% CI 1.24-1.85), and decreased with use of local exhaust ventilation (OR = 0.20, 95% CI 0.03-1.18). Gestation decreased with perceived heat intensity (β = -0.15, 95% CI -0.29 to -0.02) and number of previous pregnancies (β = -0.35, 95% CI -0.65 to -0.05). Birth weight was lower in those reporting whole-body vibration (β = -596 g, 95% CI -924 to -267) and increased with the welder's body mass index (β = 36 g, 95% CI 12-61). Estimates of exposure to metals and particles were unrelated to gestation or birth weight. In a bivariate analysis, allowing for the same welder reporting >1 pregnancy, estimated airborne aluminum exposure (and to a lesser degree exposure to nickel and particles) was related to greater risk of fetal loss (OR = 1.52, 95% CI 1.04-2.24) but neither aluminum nor the other estimated elements of welding fume added to the final model.

CONCLUSIONS

In this group of women actively engaged in welding during the time surrounding conception, the outcome of pregnancy was strongly related to work exposures, particularly vibration (reported in grinding tasks), manipulation of heavy objects, and perceived intensity of noise and heat. The study was unable to show an independent effect of exposure to metal fume constituents.

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

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.

SO2 derivatives induce dysfunction in human trophoblasts via inhibiting ROS/IL-6/STAT3 pathway

BACKGROUND

Epidemiological studies have revealed that sulfur dioxides (SO₂) can increase the risk of pregnancy complications such as missed abortion in the first trimester, stillbirth, preterm birth, small for gestational age, gestational diabetes mellitus and preeclampsia, but the mechanisms underlying these findings remains unknown. What is known, however, is that trophoblasts, a type of fetal cell exerting vital immunologic functions to maintain a successful pregnancy, are usually involved in the pathogenic mechanism of pregnancy complications.

OBJECTIVE

To study the effect of SO₂ derivatives (bisulfite and sulfite, 1:3 M/M) on the function of trophoblasts.

METHODS

Swan.71 trophoblast cells were treated with various concentrations of SO₂ derivatives to determine the effect of SO₂ derivatives on cellular viability by CKK8. Flow cytometry was performed to analyze the effect of SO₂ derivatives on apoptosis, cell cycle and intracellular ROS. Wound healing assay and transwell assay were conducted to examine the migration and invasion of Swan.71 cells. Inflammation-related cytokines in the supernatant (IL-1β, IL-6, IL-8, IL-10 and TNF-α) were measured by IMMULITE®1000 Systems (SIEMENS). The expression level of NLRP3, Caspase1, MMP9, MMP2, STAT3, and p-STAT3 were evaluated by Western Blotting.

RESULTS

Exposure to SO₂ derivatives significantly decreased cellular viability, arrested cell cycle at S/G2/M phase and induced cell apoptosis of Swan.71 trophoblasts. In addition, the migration and invasion of Swan.71 cell were significantly inhibited. SO₂ derivatives also significantly increased IL-1β secretion while it is NLRP3/Caspase1 independent. IL-6 secretion was significant inhibited accompanied by decreased STAT3 phosphorylation and expression of MMP2 and MMP9. The intracellular ROS level was significantly suppressed by SO₂ derivatives.

CONCLUSION

SO₂ derivatives exert toxic effects on trophoblasts which results in: suppressing cellular viability and intracellular ROS level, interfering with cell proliferation through arresting cell cycle, inducing cell apoptosis, disturbing inflammation-related cytokines secretion and inhibiting motility. Decreased ROS/IL-6/STAT3 levels play a role in inhibited cell viability, cell cycle arrest, apoptosis and defective motility.

Mild steel and stainless steel welding fumes elicit pro-inflammatory and pro-oxidant effects in first trimester trophoblast cells

Problem

As more women join the skilled‐trade workforce, the effects of workplace exposures on pregnancy need to be explored. This study aims to identify the effects of mild steel and stainless steel welding fume exposures on cultured placental trophoblast cells.

Method of study

Welding fumes (mild steel and stainless steel) were generously donated by Lincoln Electric. Electron microscopy was used to characterize welding fume particle size and the ability of particles to enter extravillous trophoblast cells (HTR‐8/SVneo). Cellular viability, free radical production, cytokine production, and ability of cells to maintain invasive properties were analyzed, respectively, by WST‐1, electron paramagnetic resonance, DCFH‐DA, V‐plex MULTI‐SPOT assay system, and a matrix gel invasion assay.

Results

For all three welding fume types, average particle size was <210 nm. HTR‐8/SVneo cells internalized welding particles, and nuclear condensation was observed. Cellular viability was significantly decreased at the high dose of 100 µg/mL for all three welding fumes, and stainless steel generated the greatest production of the hydroxyl radical, and intracellular reactive oxygen species. Production of the cytokines IL‐1β and TNFα were not observed in response to welding fume exposure, but IL‐6 and IL‐8 were. Finally, the invasive capability of cells was decreased upon exposure to both mild steel and stainless steel welding fumes.

Conclusion

Welding fumes are cytotoxic to extravillous trophoblasts, as is evident by the production of free radicals, pro‐inflammatory cytokines, and the observed decrease in invasive capabilities.