TERT-independent telomere elongation and shelterin dysregulation after pulmonary exposure to stainless-steel welding fume in-vivo.

Telomeres are inert DNA sequences (TTAGGG) at the end of chromosomes that protect genetic information and maintain DNA integrity. Emerging evidence has demonstrated that telomere alteration can be closely related to occupational exposure and the development of various disease conditions, including cancer. However, the functions and underlying molecular mechanisms of telomere alteration and shelterin dysregulation after welding fume exposures have not been broadly defined. In this study, we analyzed telomere length and shelterin complex proteins in peripheral blood mononuclear cells (PBMCs) and in lung tissue recovered from male Sprague-Dawley rats following exposure by intratracheal instillation (ITI) to 2 mg/rat of manual metal arc-stainless steel (MMA-SS) welding fume particulate or saline (vehicle control). PBMCs and lung tissue were harvested at 30 d after instillation. Our study identified telomere elongation and shelterin dysregulation in PBMCs and lung tissue after welding fume exposure. Mechanistically, telomere elongation was independent of telomerase reverse transcriptase (TERT) activation. Collectively, our findings demonstrated that welding fume-induced telomere elongation was (a) TERT-independent and (b) associated with shelterin complex dysregulation. It is possible that an alteration of telomere length and its regulatory proteins may be utilized as predictive biomarkers for various disease conditions after welding fume exposure. This needs further investigation.

Enhancement of keratinocyte survival and migration elicited by interleukin 24 upregulation in dermal microvascular endothelium upon welding-fume exposure.

Occupational exposure to welding fumes constitutes a serious health concern. Although the effects of fumes on the respiratory tract have been investigated, few apparent reports were published on their effects on the skin. The purpose of this study was to investigate the effects of exposure to welding fumes on skin cells, focusing on interleukin-24 (IL-24), a cytokine involved in the pathophysiology of skin conditions, such as atopic dermatitis and psoriasis. Treatment with welding fumes increased IL-24 expression and production levels in human dermal microvascular endothelial cells (HDMEC) which were higher than that in normal human epidermal keratinocytes. IL-24 levels in Trolox and deferoxamine markedly suppressed welding fume-induced IL-24 expression in HDMEC, indicating that oxidative stress may be involved in this cytokine expression. IL-24 released from HDMEC protected keratinocytes from welding fume-induced damage and enhanced keratinocyte migration. Serum IL-24 was higher in welding workers than in general subjects and was positively correlated with elevated serum levels of 8-hydroxy-2'-deoxyguanosine, an oxidative stress marker. In summary, welding fumes enhanced IL-24 expression in HDMEC, stimulating keratinocyte survival and migration. IL-24 expression in endothelial cells may act as an adaptive response to welding-fume exposure in the skin.

Risk of bladder, kidney and prostate cancer from occupational exposure to welding fumes: a systematic review and meta-analysis.

BACKGROUND: Our aimed to conduct a meta-analysis of cohort studies on risk of genitourinary (GU) cancers in workers exposed to welding fumes (WF). METHODS: We performed a systematic review of studies published on Pubmed, Scopus and Embase following PRISMA criteria. Two researchers selected cohort studies on WF exposure. From 2582 articles, 7 non-overlapping studies were included. Quality of studies was scored according to CASP. We run a random effects meta-analysis to calculate the relative risk (RR) and 95% confidence intervals (CI) of GU cancer, overall and stratified by cancer, country, and quality score. RESULTS: We included seven studies reporting results on GU cancers, including prostate, bladder and kidney cancer (PC, BC, and KC). The RR was 1.19 (95% CI = 1.07-1.32, 16 risk estimates) for GU cancer; 1.13 (95% CI = 0.90-1.42, 4 risk estimates) for PC; 1.26 (95% CI = 0.98-1.60, 7 risk estimates) for BC and 1.28 (95% CI = 1.12-1.47, 5 risk estimates) for KC. Heterogeneity was present in all meta-analyses (p < 0.001). The increased risk was more pronounced in North American than in European studies (respectively, OR = 1.35, 95% CI = 1.18-1.55; OR = 1.13, 95% CI = 1.01-1.27 p heterogeneity = 0.03). There was no heterogeneity according to quality score (p = 0.4). Data were insufficient to investigate associations by industry or welding type. Publication bias for each cancer was excluded. CONCLUSION: This meta-analysis suggests increased risk of KC and BC, but not of PC, in workers exposed to WF. Confounding by other occupational and non-occupational risk factors could not be excluded. Data were not adequate to address the risk of specific exposure circumstances.

Compositional variations in metal nanoparticle components of welding fumes impact lung epithelial cell toxicity.

Welding fumes contain harmful metals and gas by-products associated with development of lung dysfunction, asthma, bronchitis, and lung cancer. Two prominent welding fume particulate metal components are nanosized iron (Fe) and manganese (Mn) which might induce oxidative stress and inflammation resulting in pulmonary injury. Welding fume toxicity may be dependent upon metal nanoparticle (NP) components. To examine toxicity of welding fume NP components, a system was constructed for controlled and continuous NP generation from commercial welding and customized electrodes with varying proportions of Fe and Mn. Aerosols generated consisted of nanosized particles and were compositionally consistent with each electrode. Human alveolar lung A459 epithelial cells were exposed to freshly generated metal NP mixtures at a target concentration of 100 µg/m3 for 6 hr and then harvested for assessment of cytotoxicity, generation of reactive oxygen species (ROS), and alterations in the expression of genes and proteins involved in metal regulation, inflammatory responses, and oxidative stress. Aerosol exposures decreased cell viability and induced increased ROS production. Assessment of gene expression demonstrated variable up-regulation in cellular mechanisms related to metal transport and storage, inflammation, and oxidative stress based upon aerosol composition. Specifically, interleukin-8 (IL-8) demonstrated the most robust changes in both transcriptional and protein levels after exposure. Interleukin-8 has been determined to serve as a primary cytokine mediating inflammatory responses induced by welding fume exposures in alveolar epithelial cells. Overall, this study demonstrated variations in cellular responses to metal NP mixtures suggesting compositional variations in NP content within welding fumes may influence inhalation toxicity.

Oxidative stress and DNA damage resulting from welding fumes exposure among professional welders: A systematic review and meta-analysis.

The present systematic review aimed to evaluate the associations between welding fumes exposure and changes in oxidative stress [superoxide dismutase (SOD) and malondialdehyde (MDA)] and DNA damage [8-hydroxy-2'-deoxyguanosine (8-OHdG) and DNA-protein crosslink (DPC)] markers in professional welders (PROSPERO CRD42022298115). Six electronic bibliographic databases were searched from inception through September 2021 to identify observational epidemiological studies evaluating the association between welding fumes exposures and changes in oxidative stress and DNA damage in professional welders. Two reviewers independently assessed the risk of bias and certainty of the evidence. A narrative synthesis of results was conducted using the Synthesis Without Meta-analysis (SWiM) method. Pooled mean differences with 95% confidence intervals were calculated in a random-effects meta-analysis for the outcomes of interest in the review. From 450 studies identified through the search strategy, 14 observational epidemiological studies were included in the review. Most studies reported significantly higher welding fumes levels in welders than in controls. The narrative synthesis results of SOD showed a significant difference between welders and controls, while the meta-analysis results of MDA did not show a significant difference between the studied groups (MD = 0.26; 95% CI, -0.03, 0.55). The meta-analysis results of 8-OHdG (MD = 9.38; 95% CI, 0.55-18.21) and DPC (MD = 1.07; 95% CI, 0.14-2) revealed significantly differences between the studied groups. The included studies were at high risk of exclusion and confounding bias. The certainty of the evidence for oxidative stress and DNA damage results were very low and moderate, respectively. Exposure to welding fumes and metal particles is associated with DNA damage in professional welders, and 8-OHdG and DPC might be considered reliable markers to assess DNA damage resulting from exposure to welding fumes. We recommend, however, that the evaluation of oxidative stress resulting from welding fumes exposure not be solely based on MDA and SOD.

Respiratory health disorders among workers in some Egyptian welding enterprises.

Welding fumes contain a complex mixture of metallic oxides that pose a risk to welders' respiratory systems. This study aimed to evaluate respiratory health disorders among workers in some Egyptian welding enterprises and their relationship to the workplace environment. This research was performed from January 1st, 2019 to February 28th, 2021 in welding enterprises in Birket El-Sabaa, a randomly selected district of Menoufia governorate, Egypt. A cross-sectional comparative study was conducted on 110 welders and 110 non-occupationally exposed subjects. Environmental studies were carried out for total welding fumes, respirable dust, and manganese air levels. Spirometric measures and manganese levels in whole blood were applied. Analysis of the personal air samples revealed that the mean values of welding fumes, respirable dust, and manganese air levels were higher than the international permissible levels. Welders had a higher significant prevalence of respiratory manifestations (rhinitis, cough, expectoration, wheezes, dyspnea, and chronic bronchitis) as well as decreased spirometric measures (FVC%, FEV1%, FEV1/FVC%, and FEF25-75%) than controls. The mean value of whole blood manganese level was statistically significantly higher among welders than that of the controls (3.35 ± 0.5 and 1.81 ± 0.79 ng/mL; respectively). A significant relationship was reported between longer work time and the prevalence of respiratory manifestations and decreased spirometric measurements. The use of masks/respirators was associated with a reduced prevalence of respiratory manifestations. Finally, welders that are exposed to welding fumes at concentrations higher than the permissible levels in welding establishments suffer from adverse respiratory problems, as shown by increased prevalence of respiratory manifestations and lower spirometric measurements. Regular use of high-quality personal protective equipment, especially masks, as well as periodic medical examinations for welders, is highly urged.

Welding Fume Instillation in Isolated Perfused Mouse Lungs-Effects of Zinc- and Copper-Containing Welding Fumes.

Zinc- and copper-containing welding fumes can cause systemic inflammation after exposure in humans. Recent ex vivo studies have shown that the observed inflammation originates from exposed immune cells. In vitro studies identified the soluble fraction of metal particles as the main effectors. Isolated perfused mouse lungs (IPLs) were perfused and ventilated for 270 min. Lungs were instilled with saline solution (control), welding fume particle suspension (WFs) or the soluble fraction of the welding fumes (SF-WFs). Bronchoalveolar lavage fluid (BALF) and perfusate samples were analyzed for cytokine levels and lung tissue mRNA expression levels were analyzed via RT-PCR. All lungs instilled with WFs did not complete the experiments due to a fatal reduction in tidal volume. Accordingly, IL-6 and MPO levels were significantly higher in BALF of WF lungs compared to the control. IL-6 and MPO mRNA expression levels were also increased for WFs. Lungs instilled with SF-WFs only showed mild reactions in tidal volume, with BALF and mRNA expression levels not significantly differing from the control. Zinc- and copper-containing welding fume particles adversely affect IPLs when instilled, as evidenced by the fatal loss in tidal volume and increased cytokine expression and secretion. The effects are mainly caused by the particles, not by the soluble fraction.

Personal and area exposure assessment at a stainless steel fabrication facility: an evaluation of inhalable, time-resolved PM10, and bioavailable airborne metals.

This study describes a comprehensive exposure assessment in a stainless steel welding facility, measuring personal inhalable PM and metals, time-resolved PM10 area metals, and the bioavailable fraction of area inhalable metals. Eighteen participants wore personal inhalable samplers for two, nonconsecutive shifts. Area inhalable samplers and a time-resolved PM10 X-ray fluorescence spectrometer were used in different work areas each sampling day. Inhalable and bioavailable metals were analyzed using inductively coupled plasma mass spectrometry (ICP-MS). Median exposures to chromium, nickel, and manganese across all measured shifts were 66 (range: 13-300) µg/m3, 29 (5.7-132) µg/m3, and 22 (1.5-119) µg/m3, respectively. Most exposure variation was seen between workers ( 0.79

[Investigation on occupational hazards in 20 automobile manufacturing enterprises in Shandong Province].

Objective: To investigate the current situation of occupational hazards in automobile manufacturing enterprises in Shandong Province. Methods: From February to May 2019, the convenience sampling method was adopted to conduct on-site occupational health surveys with 20 automobile manufacturing enterprises in Shandong Province as the survey subjects, to detect the occupational hazard factors in the workplaces and individual exposure levels, and to analyze the occupational health check results of operators. Results: There were 13 small-sized, 4 medium-sized and 3 large-sized enterprises among the 20 automobile manufacturing enterprises. The detection results of benzene and toluene in the workplaces met the occupational exposure limits, and the detection results of welding fumes, manganese and its compounds, and xylene exceed the occupational exposure limits. The maximum short-term exposure concentration (C(STE)) of welding fume in the air of workplaces was 24.23 mg/m(3), and the over-standard rate was 11.0% (16/146) . The maximum time-weighted average concentration (C(TWA)) of welding fume of operators is 10.60 mg/m(3), and the over-standard rate was 11.0% (8/73) . The maximum C(STE) of manganese and its compounds in the air of workplaces was 0.879 mg/m(3), and the of manganese and its compounds of operators was 0.175 mg/m(3), and the over-standard rate was 5.7% (4/70) . The maximum xylene C(STE) in the air of workplaces was 230.00 mg/m(3), and the over-standard rate was 3.9% (2/51) . The maximum xylene C(TWA) of operators was 70.40 mg/m(3), the over-standard rate was 3.6% (1/28) . Among the 4775 workers exposed to occupational hazards, 38 (0.80%) were suspected of electric welder's pneumoconiosis, 27 (0.57%) were suspected of manganese poisoning and 31 (0.65%) were suspected of chronic low-concentration benzene and benzene series poisoning. The detection rates of suspected occupational diseases among workers in small and medium-sized enterprises were relatively high, 2.86% (30/1048) and 4.51% (51/1132) respectively. There was a statistically significant difference in the detection rates of suspected occupational diseases among the operators of different scale automobile manufacturers (P<0.05) . Conclusion: The exposure levels of electric welding fumes, manganese and its compounds in welding jobs and xylene exposure levels in spray painting jobsin Shandong Province's automobile manufacturing enterprises are more serious. The supervision and management of occupational hygiene should be strengthened, the working environment should be improved, and the health of welding and painting workers should be protected.

A possible relationship between telomere length and markers of neurodegeneration in rat brain after welding fume inhalation exposure.

Inhalation of welding fume (WF) can result in the deposition of toxic metals, such as manganese (Mn), in the brain and may cause neurological changes in exposed workers. Alterations in telomere length are indicative of cellular aging and, possibly, neurodegeneration. Here, we investigated the effect of WF inhalation on telomere length and markers of neurodegeneration in whole brain tissue in rats. Male Fischer-344 (F-344) rats were exposed by inhalation to stainless steel WF (20 mg/m3 x 3 h/d x 4 d/wk x 5 wk) or filtered air (control). Telomere length, DNA-methylation, gene expression of Trf1, Trf2, ATM, and APP, protein expression of p-Tau, α-synuclein, and presenilin 1 and 2 were assessed in whole brain tissue at 12 wk after WF exposure ended. Results suggest that WF inhalation increased telomere length without affecting telomerase in whole brain. Moreover, we observed that components of the shelterin complex, Trf1 and Trf2, play an important role in telomere end protection, and their regulation may be responsible for the increase in telomere length. In addition, expression of different neurodegeneration markers, such as p-Tau, presenilin 1-2 and α-synuclein proteins, were increased in brain tissue from the WF-exposed rats as compared to control. These findings suggest a possible correlation between epigenetic modifications, telomere length alteration, and neurodegeneration because of the presence of factors in serum after WF exposure that may cause extra-pulmonary effects as well as the translocation of potentially neurotoxic metals associated with WF to the central nervous system (CNS). Further studies are needed to investigate the brain region specificity and temporal response of these effects.

Exposure to metal fumes and circulating miRNAs in Algerian welders.

PURPOSE: A cross-sectional study was conducted in a group of Algerian welders to study the relationship between the exposure to metal particles from welding fumes and the concentration of three circulating miRNAs, miR-21, miR-146a and miR-155, as markers of renal function injury. METHODS: Characteristics of the subjects and the curriculum laboris were determined by questionnaires. We measured the concentrations of metals in blood and urine samples using ICP-MS. The three circulating miRNAs studied were measured by quantitative PCR. Associations between miRNAs and internal exposure markers were assessed by simple and multiple regression analyses. RESULTS: miR-21 was significantly lower among welders (p = 0.017), compared with controls, adjusted for age, body mass index, smoking status and seniority. Significant adjusted associations were observed between miR-21 or miR-155 and urinary chromium (p = 0.005 or p = 0.041, respectively), miR-146a and urinary nickel (p = 0.019). The results of the multivariate analysis showed that duration of employment was the main factor responsible for the variation of miRNAs among welders. CONCLUSION: In conclusion, a recent exposure to certain metals, mainly chromium and nickel, appears to be associated to a decrease in plasma expression of miR-21, miR-146a and miR-155. Further larger studies would help to determine the mechanisms of action of metal particles on miRNA expression.

Oxidative stress status of Turkish welders.

Welding, a fabrication process that joins metals or thermoplastics by causing coalescence, is indispensable in modern society and ubiquitous in industry. Welding generates fumes that contain several metals and gases that comprise fine and ultrafine particles with the potential for adverse effects. Although health risks of welders have been evaluated in different populations, occupational exposure to welding fumes is still considered to be an important health problem, especially in developing countries. The aim of this study was to investigate the effects of welding fume exposure on important oxidative stress parameters such as superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), total glutathione (GSH), glutathione peroxidase (GPx), malondialdehyde (MDA), and 8-hydroxy-2'-deoxyguanosine (8-OHdG) in Turkish welders (n = 48). The influence of confounding factors such as age, smoking habits, alcohol consumption, and duration of exposure on the studied parameters was also analyzed. In our study, significant decreases in the levels of GSH and activities of CAT, SOD, and GPx and significant increases of MDA, 8-OHdG levels and GR activity were found in the workers compared to the controls. There was a negative correlation between GSH levels and alcohol usage. Also, older workers (≥35 years) had significantly higher GR levels than younger workers. But smoking and alcohol usage, duration of exposure, and utilization of protective measures had no significant effect on the studied parameters in the workers. These results indicate that occupational exposure to welding fumes appears to induce oxidative stress and oxidative DNA damage.

[Research progress on the effects of welding fumes exposure on lung].

Welding is an important industrial activity worldwide which involving millions of practitioners. Due to the influence of welding method, welding dust concentration, ventilation, weather and other factors, the exposure of the welder is different. And resulting in different respiratory symptoms, including decreased lung function, welder's pneumoconiosis and even lung cancer, which seriously affects the life quality of the worker. Through referring to literatures, the research status of welding dust and respiratory diseases was summarized to provide direction for future research.

Welding fumes and lung cancer: a meta-analysis of case-control and cohort studies.

BACKGROUND: An estimated 110 million workers are exposed to welding fumes worldwide. Welding fumes are classified by the International Agency for Research on Cancer as carcinogenic to humans (group 1), based on sufficient evidence of lung cancer from epidemiological studies. OBJECTIVE: To conduct a meta-analysis of case-control and cohort studies on welding or exposure to welding fumes and risk of lung cancer, accounting for confounding by exposure to asbestos and tobacco smoking. METHODS: The literature was searched comprehensively in PubMed, reference lists of relevant publications and additional databases. Overlapping populations were removed. Meta-relative risks (mRRs) were calculated using random effects models. Publication bias was assessed using funnel plot, Eggers's test and Begg's test. RESULTS: Forty-five studies met the inclusion criteria (20 case-control, 25 cohort/nested case-control), which reduced to 37 when overlapping study populations were removed. For 'ever' compared with 'never' being a welder or exposed to welding fumes, mRRs and 95% CIs were 1.29 (1.20 to 1.39; I2=26.4%; 22 studies) for cohort studies, 1.87 (1.53 to 2.29; I2=44.1%; 15 studies) for case-control studies and 1.17 (1.04 to 1.38; I2=41.2%) for 8 case-control studies that adjusted for smoking and asbestos exposure. The mRRs were 1.32 (95% CI 1.20 to 1.45; I2=6.3%; 15 studies) among 'shipyard welders', 1.44 (95% CI 1.07 to 1.95; I2=35.8%; 3 studies) for 'mild steel welders' and 1.38 (95% CI 0.89 to 2.13; I2=68.1%; 5 studies) among 'stainless steel welders'. Increased risks persisted regardless of time period, geographic location, study design, occupational setting, exposure assessment method and histological subtype. CONCLUSIONS: These results support the conclusion that exposure to welding fumes increases the risk of lung cancer, regardless of the type of steel welded, the welding method (arc vs gas welding) and independent of exposure to asbestos or tobacco smoking.

Dependence of welding fume particle toxicity on electrode type and current intensity assessed by microalgae growth inhibition test.

Welding fumes are a major source of metal oxide particles, ozone, carbon monoxide, carbon dioxide, nitrogen oxides, and many other toxic substances. Hazardous properties and the level of toxicity of welding fumes depend mostly on the welding electrode type and the welding regime parameters. The specific objective of this study was to evaluate the aquatic toxicity of metal welding fume particles in vivo on microalga Heterosigma akashiwo. The quantity and size of particles were measured by flow cytometry using a scattering laser light with a wavelength of 405 nm. The number of microalgae cells after 72 h and 7 days exposition with welding fume particle suspensions was evaluated by flow cytometry. Morphological changes of the microalga were observed by optical microscopy. The toxic effect was demonstrated as a significant reduction of cell density after exposure of microalgae to welding fume particles. The greatest impact on the growth of microalga was caused by particles with high rutile content. It was shown that the adverse effect of metal oxide particles depends more on the chemical composition of particles in welding fume while the number and dispersity of particles had no noticeable toxic influence on microalgae. The findings of this research confirm the fact that the toxicity of welding fume particles can be significantly reduced by using rutile-cellulose coated electrodes.

Grouping schemes of welding fume exposure in shipyard welders.

Welding fume exposure can increase the risk of chronic obstructive pulmonary disease (COPD). The aim of this study was to evaluate the optimal grouping schemes of welding fume exposure in shipyard welders for future accurate examination of the association between welding fume exposure and COPD. Industrial hygiene records, including welding fume measurements between 2002 and 2009 were collected from a shipyard. A total of 2,360 personal welding fume measurements was compiled with a geometric mean of 1.66 mg/m3 and a geometric standard deviation of 4.02. Welding jobs were categorized into 8 groups. There were 9 working areas. To obtain the optimal grouping scheme, various grouping schemes were created using job, area, and job*area combination. To compare various grouping schemes, contrast and precision were calculated for each grouping scheme. For all measurement data, group mean ranking method created by ranking geometric means of the job*area combination into 3 groups (group mean ranking method) showed the best contrast and precision values among various grouping schemes, followed by grouping based on the job. For a subset of the data excluding job*area combinations with less than 10 measurements, grouping based on the job showed greater contrast than group mean ranking method, while for other subsets, including only repeated measurement data or further excluding job*area combinations with less than 10 measurements from the repeated measurement subset, group mean ranking method showed greater contrast than grouping based on the job. Our results showed that group mean ranking or grouping based on the job could be a candidate for the optimal grouping schemes in this shipyard. Our efforts for optimal grouping scheme may aid future cohort study to elucidate the association between welding fume exposure and COPD.

Lifetime occupational exposure to metals and welding fumes, and risk of glioma: a 7-country population-based case-control study.

BACKGROUND: Brain tumor etiology is poorly understood. Based on their ability to pass through the blood-brain barrier, it has been hypothesized that exposure to metals may increase the risk of brain cancer. Results from the few epidemiological studies on this issue are limited and inconsistent. METHODS: We investigated the relationship between glioma risk and occupational exposure to five metals - lead, cadmium, nickel, chromium and iron- as well as to welding fumes, using data from the seven-country INTEROCC study. A total of 1800 incident glioma cases and 5160 controls aged 30-69 years were included in the analysis. Lifetime occupational exposure to the agents was assessed using the INTEROCC JEM, a modified version of the Finnish job exposure matrix FINJEM. RESULTS: In general, cases had a slightly higher prevalence of exposure to the various metals and welding fumes than did controls, with the prevalence among ever exposed ranging between 1.7 and 2.2% for cadmium to 10.2 and 13.6% for iron among controls and cases, respectively. However, in multivariable logistic regression analyses, there was no association between ever exposure to any of the agents and risk of glioma with odds ratios (95% confidence intervals) ranging from 0.8 (0.7-1.0) for lead to 1.1 (0.7-1.6) for cadmium. Results were consistent across models considering cumulative exposure or duration, as well as in all sensitivity analyses conducted. CONCLUSIONS: Findings from this large-scale international study provide no evidence for an association between occupational exposure to any of the metals under scrutiny or welding fumes, and risk of glioma.

Exposure to welding fumes and lower airway infection with Streptococcus pneumoniae.

BACKGROUND: Welders are at increased risk of pneumococcal pneumonia. The mechanism for this association is not known. The capacity of pneumococci to adhere to and infect lower airway cells is mediated by host-expressed platelet-activating factor receptor (PAFR). OBJECTIVE: We sought to assess the effect of mild steel welding fumes (MS-WF) on PAFR-dependent pneumococcal adhesion and infection to human airway cells in vitro and on pneumococcal airway infection in a mouse model. METHODS: The oxidative potential of MS-WF was assessed by their capacity to reduce antioxidants in vitro. Pneumococcal adhesion and infection of A549, BEAS-2B, and primary human bronchial airway cells were assessed by means of quantitative bacterial culture and expressed as colony-forming units (CFU). After intranasal instillation of MS-WF, mice were infected with Streptococcus pneumoniae, and bronchoalveolar lavage fluid (BALF) and lung CFU values were determined. PAFR protein levels were assessed by using immunofluorescence and immunohistochemistry, and PAFR mRNA expression was assessed by using quantitative PCR. PAFR was blocked by CV-3988, and oxidative stress was attenuated by N-acetylcysteine. RESULTS: MS-WF exhibited high oxidative potential. In A549 and BEAS-2B cells MS-WF increased pneumococcal adhesion and infection and PAFR protein expression. Both CV-3988 and N-acetylcysteine reduced MS-WF-stimulated pneumococcal adhesion and infection of airway cells. MS-WF increased mouse lung PAFR mRNA expression and increased BALF and lung pneumococcal CFU values. In MS-WF-exposed mice CV-3988 reduced BALF CFU values. CONCLUSIONS: Hypersusceptibility of welders to pneumococcal pneumonia is in part mediated by the capacity of welding fumes to increase PAFR-dependent pneumococcal adhesion and infection of lower airway cells.

Characterization of Tungsten Inert Gas (TIG) Welding Fume Generated by Apprentice Welders.

Tungsten inert gas welding (TIG) represents one of the most widely used metal joining processes in industry. Its propensity to generate a greater portion of welding fume particles at the nanoscale poses a potential occupational health hazard for workers. However, current literature lacks comprehensive characterization of TIG welding fume particles. Even less is known about welding fumes generated by welding apprentices with little experience in welding. We characterized TIG welding fume generated by apprentice welders (N = 20) in a ventilated exposure cabin. Exposure assessment was conducted for each apprentice welder at the breathing zone (BZ) inside of the welding helmet and at a near-field (NF) location, 60cm away from the welding task. We characterized particulate matter (PM4), particle number concentration and particle size, particle morphology, chemical composition, reactive oxygen species (ROS) production potential, and gaseous components. The mean particle number concentration at the BZ was 1.69E+06 particles cm(-3), with a mean geometric mean diameter of 45nm. On average across all subjects, 92% of the particle counts at the BZ were below 100nm. We observed elevated concentrations of tungsten, which was most likely due to electrode consumption. Mean ROS production potential of TIG welding fumes at the BZ exceeded average concentrations previously found in traffic-polluted air. Furthermore, ROS production potential was significantly higher for apprentices that burned their metal during their welding task. We recommend that future exposure assessments take into consideration welding performance as a potential exposure modifier for apprentice welders or welders with minimal training.

Assessment of DNA damage as an index of genetic toxicity in welding microenvironments among iron-based industries.

Welding is used extensively in different industries. Welders are always at a risk of exposure to a number of gases and metal-containing fumes in their respective microenvironments in which they work. Welding fumes consist of a wide range of complex metal oxide particles which can deposit in different parts of their bodies causing serious health problems. In the present study, 35 welders (age: 33.80 ± 1.04 years) from two iron-based industries have been assessed for DNA damage in peripheral blood lymphocytes using single-cell gel electrophoresis. An equal number of subjects (N = 35; age: 30.40 ± 1.51 years) matched to exposed subjects with respect to sex, age, socioeconomic status, smoking, and alcoholic habits were taken as controls. The results revealed that the damaged cell frequency (DCF) and mean comet tail length (CTL) in welders were significantly higher as compared to the controls (DCF: 69.74 ± 1.68 vs. 31.14 ± 1.67 and CTL: 29.21 ± 1.48 vs. 1.47 ± 0.08; p < 0.05). The effect of confounding factors such as age, duration of exposure, smoking, and drinking habits was also studied. Blood lead levels also showed a positive correlation with duration of exposure and CTL, and the overall results indicated an increased genetic damage as an index of genotoxicity in workers occupationally engaged in welding microenvironments.