Welding fume exposure and prevalence of chronic respiratory symptoms among welders in micro- and small-scale enterprise in Akaki Kality sub-city, Addis Ababa, Ethiopia: a comparative cross-sectional study

BACKGROUND

Exposure to welding fumes can lead to different respiratory health disorders, including lung cancer, due to long-term exposures. In Ethiopia, large numbers of people are engaged in the welding sector. Often, these workers are exposed to welding fumes at their workplaces, however, the level of exposure and its health effects have never been studied.

OBJECTIVE

To measure the level of personal welding fume exposure and assess chronic respiratory symptoms and associated factors, among micro and small-scale enterprise metal workshop workers, in Akaki Kality Sub city, Ethiopia.

METHODS

A comparative cross-sectional study involving 226 welders and 217 controls. Chronic respiratory symptoms were assessed using a standardized questionnaire adopted from the American Thoracic Society (ATS). Welding fumes were collected from the welder's breathing zone using 37 mm close-faced plastic cassettes fitted with Polyvinyl Chloride (PVC) filters connected to Casella pumps at an airflow rate of 2 L/min.

RESULT

The overall prevalence of chronic respiratory symptoms among welders and controls were 54 (23.9%) and 20 (9.2%) respectively. The geometric mean and geometric standard deviation (GSD) of personal welding fume exposure, among welders was 5.98 mg/m3 (± GSD = 1.54). In this study, 53.3% of the samples exceeded the Occupational Exposure Limit defined by the American Conference of Governmental Industrial Hygiene. Chronic respiratory symptoms were significantly associated with educational status (Adjusted Odds Ratio (AOR): 5.11, 95% CI: 1.35, 19.33), respiratory protective equipment use (AOR: 3.33, 95% CI: 1.52, 7.31), safety training (AOR: 2.41, 95% CI: 1.10, 5.28), smoking (AOR:3.57, 95% CI: 1.54, 8.23), welding machine maintenance (AOR: 1.87, 95% CI: 1.01, 3.59) and welding site (i.e. indoors vs. outdoor) (AOR: 6.85. 95% CI: 2.36, 19.89).

CONCLUSIONS

The prevalence of chronic respiratory symptoms among welding workers was significantly higher than controls. More than half of the samples exceeded the Occupational Exposure Limit. Educational status, implementation of safety training, and welding sites were significantly associated with chronic respiratory symptoms. The results suggested a need to reduce welding fume exposure to improve the respiratory health of the workers.

[Effects of electric welding on hearing loss and respiratory damage]

Objective: To investigate the occupational health status of electric welding workers and explore the effects of electric welding on hearing loss and respiratory damage. Methods: From August to December 2021, the cluster sampling method was used to select workers from an automobile manufacturer in Guangzhou City as research subjects: 636 welding workers in the welding workshop as the welding group, 757 assembly workers in the engine workshop and the final assembly workshop exposed to pure noise as the assembly group. Occupational disease hazard factors were detected for welding positions and assembly positions, and occupational health examination was carried out for research subjects. The occupational health status, the trends of hearing loss and respiratory abnormalities with working age were compared and analyzed between the two groups. Binary logistic regression was used to analyze the association between hearing loss and respiratory abnormalities in welding workers. Results: The excess rates of welding fumes, manganese and its compounds in the welding position were both 9.68% (3/31). Its noise exposure intensity [ (85.36±2.68) dB (A) ] and excess rate [48.39% (15/31) ] were not significantly different from those in the assembly position [ (84.86±3.28) dB (A) and 43.24% (16/37) ] (P>0.05). The results of the occupational health examination showed that the detection rates of hearing loss, digital radiography (DR) chest X-ray abnormality, alanine aminotransferase abnormality, deazelaic aminotransferase abnormality and white blood cell count abnormality of workers in the welding group were higher than those in the assembly group (P<0.05). The detection rates of hearing loss, DR chest X-ray abnormality, pulmonary ventilation abnormality in the welding group and the detection rate of hearing loss in the assembly group increased with the working age of the workers (P<0.05). The hearing loss detection rate and DR chest X-ray abnormality detection rate of the workers with ≥9 years working age in the welding group were both higher than those in the assembly group workers with same working age (P<0.05). The binary logistic regression analysis showed that abnormal pulmonary ventilation and abnormal DR chest X-ray were the risk factors for hearing loss in welding workers (OR=10.83, 95%CI: 7.31-16.06; OR=16.59, 95%CI: 5.72-48.10; P<0.05) . Conclusion: Hearing loss and respiratory damage are prominent problems among welding workers, and the detection rates of abnormality increase with the working age of the workers. Hearing loss in welding workers is associated with abnormal pulmonary ventilation and abnormal DR chest X-ray.

Study on the soluble and insoluble fume and hexavalent chromium emitted from a new covered electrode with micro and nano sized-sodium and potassium titanate-based flux

The present study discusses the effect of the addition of nano-sized arc stabilizing materials on fume emissions and its solubility characteristics. Micro and nano-sized sodium/potassium titanates were added to the SMAW electrode flux as a substitute for the conventional sodium and potassium silicate compounds. The total and soluble metal concentration of fumes from the newly developed electrodes were estimated and compared with that of commercially available electrodes. The estimation of fume formation rate and breathing zone concentration of fumes followed the ISO 15011-1 and ISO 10882-1 standard. An average 50% reduction in the soluble fraction of fumes was observed from the electrodes containing micro-sized potassium-titanate compounds, and the reduction was further improved by 60% when nano-sodium titanate was added to the flux. Whereas, the reduction in soluble metal concentration for potassium titanate coated electrodes were 45% and 55%, in that order, for their micro and nano-structured forms. The soluble fraction of hexavalent chromium from the electrodes containing 100% nano sodium/potassium titanates was reduced up to 50% in each impactor stage. The inclusion of nano-sized sodium titanate in the flux resulted in a reduction in fume formation rate up to 55% and breathing zone concentration of fumes by 58% compared to the conventional sodium silicate coated electrodes. The electrode assaying 100% nano-potassium titanate showed a reduction of 59% in fume formation rate and 61% in breathing zone concentration compared to that of conventional potassium silicate-coated electrodes.

Analysis of serum metabolome of laborers exposure to welding fume

OBJECTIVE

Welding fume exposure is inevitable of welding workers and poses a severe hazard to their health since welding is a necessary industrial process. Thus, preclinical diagnostic symptoms of worker exposure are of great importance. The aim of this study was to screen serum differential metabolites of welding fume exposure based on UPLC-QTOF-MS/MS.

METHODS

In 2019, 49 participants were recruited at a machinery manufacturing factory. The non-target metabolomics technique was used to clarify serum metabolic signatures in people exposed to welding fume. Differential metabolites were screened by OPLS-DA analysis and Student's t-test. The receiver operating characteristic curve evaluated the discriminatory power of differential metabolites. And the correlations between differential metabolites and metal concentrations in urine and whole blood were analyzed utilizing Pearson correlation analysis.

RESULTS

Thirty metabolites were increased significantly, and 5 metabolites were decreased. The differential metabolites are mainly enriched in the metabolism of arachidonic acid, glycero phospholipid, linoleic acid, and thiamine. These results observed that lysophosphatidylcholine (20:1/0:0) and phosphatidylglycerol(PGF1α/16:0) had a tremendous anticipating power with relatively increased AUC values (AUC > 0.9), and they also presented a significant correlation of Mo concentrations in whole blood and Cu concentrations in urine, respectively.

CONCLUSION

The serum metabolism was changed significantly after exposure to welding fume. Lysophosphatidylcholine (20:1/0:0) and phosphatidylglycerol (PGF1α/16:0) may be a potential biological mediator and biomarker for laborers exposure to welding fume.

Examination of the exposome in an animal model: The impact of high fat diet and rat strain on local and systemic immune markers following occupational welding fume exposure

The goal of this study was to investigate the impact of multiple exposomal factors (genetics, lifestyle factors, environmental/occupational exposures) on pulmonary inflammation and corresponding alterations in local/systemic immune parameters. Accordingly, male Sprague-Dawley (SD) and Brown Norway (BN) rats were maintained on either regular (Reg) or high fat (HF) diets for 24wk. Welding fume (WF) exposure (inhalation) occurred between 7 and 12wk. Rats were euthanized at 7, 12, and 24wk to evaluate local and systemic immune markers corresponding to the baseline, exposure, and recovery phases of the study, respectively. At 7wk, HF-fed animals exhibited several immune alterations (blood leukocyte/neutrophil number, lymph node B-cell proportionality)-effects which were more pronounced in SD rats. Indices of lung injury/inflammation were elevated in all WF-exposed animals at 12wk; however, diet appeared to preferentially impact SD rats at this time point, as several inflammatory markers (lymph node cellularity, lung neutrophils) were further elevated in HF over Reg animals. Overall, SD rats exhibited the greatest capacity for recovery by 24wk. In BN rats, resolution of immune alterations was further compromised by HF diet, as many exposure-induced alterations in local/systemic immune markers were still evident in HF/WF animals at 24wk. Collectively, HF diet appeared to have a greater impact on global immune status and exposure-induced lung injury in SD rats, but a more pronounced effect on inflammation resolution in BN rats. These results illustrate the combined impact of genetic, lifestyle, and environmental factors in modulating immunological responsivity and emphasize the importance of the exposome in shaping biological responses.

Characterization of welding fume and airborne heavy metals in electronic manufacturing workshops in Hangzhou, China: implication for occupational population exposure

Occupational exposure to contaminants created by electronic manufacturing process is not well characterized. The aim of this study was to carry out risk assessments of exposure to welding fume and airborne heavy metals (HMs) in electronic manufacturing workshops. Seventy-six air samples were collected from five sites in Hangzhou, China. In welding workshops, the most abundant contaminant found was welding fume, followed by Fe, Mn, Zn, Cu, Pb, Cd, and Cr. The concentration of Mn was positively correlated with Fe (r = 0.906). When compared with non-welding workshops, the Fe content in the air of welding workshops increased significantly (P < 0.05), while the Cu content decreased significantly (P < 0.05). Singapore semi-quantitative health risk assessment model and the United States Environmental Protection Agency (US EPA) inhalation risk assessment model were applied to assess the occupational exposure. In welding workshops, the levels of 8-h time weighted average (8 h-TWA) calculated for welding fume (range 0.288 ~ 6.281 mg/m³), Mn (range Nd ~ 0.829 mg/m³), and Fe (range 0.027 ~ 2.234 mg/m³) partly exceeded the permissible limits. While, in non-welding workshops, the average of 8 h-TWA for Cu (0.411 mg/m³) was higher than the limit. The risk rates (RR) assessed for Pb (2.4 vs 1.7), Mn (2.0 vs 1.4), and Fe (1.4 vs 1.0) were higher in welding workshops than that in non-welding workshops, but Cu (1.0 vs 2.2) were lower. The mean excess lifetime cancer risks (ELCR) in welding (5.59E - 06 per 1000 people) and non-welding (1.88E - 06 per 1000 people) workshops were acceptable. The mean non-cancer risk (HQ) estimated for Mn was greater than 10 in both welding (HQ = 164) and non-welding (HQ = 11.1) workshops. These results indicate that there was a risk of occupational exposure implication in the electronic manufacturing workshops. Reducing contaminant exposure through engineering controls and management strategies, such as efficient ventilation and reducing exposure hours, is thus suggested.

[Current status and research progress of occupational health monitoring in welding fume operations]

Welding operations are widely present in the manufacturing production process, involving a large number of occupational groups, and are the key occupations where work injuries and occupational diseases occur in China. For different welding processes and welding materials, the content and focus of occupational health monitoring are different. At present, the item of occupational health examination in welding operation is in poor consistency with the on-site exposure of occupational hazard factors, and it is mainly concentrated in the stage of disease development, which can not reflect the early health damage caused by welding dust exposure in time. The emergence of biomarkers of welding dust can make up for this defect. Therefore, it is of great significance to describe the current situation of occupational health monitoring of welding dust and summarize the research progress of related biomarkers for the early prevention of diseases caused by welding dust and the practice of occupational health monitoring.

Preliminary study to investigate the distribution and effects of certain metals after inhalation of welding fumes in mice

The most important welding processes used are the gas metal arc (GMA) welding, the tungsten inert gas (TIG) welding, and the manual metal arc (MMA) welding processes. The goal of our investigation was to monitor the distribution of iron (Fe), manganese (Mn), calcium (Ca), and magnesium (Mg) in the lung, spleen, liver, and kidney of mice after inhalation exposure of different welding methods using different steel base materials. The treatment groups were the following: MMA-mild steel, MMA-molybdenum-manganese (MoMn) alloy, TIG-mild steel, and TIG-stainless steel. The samples were taken 24 and 96 h after the treatments. Most importantly, it was found that the Mn concentration in the lung' samples of the MMA-mild steel and the MMA-MoMn groups was increased extremely at both sampling times and in the spleen' samples also. In the TIG groups, the rise of the Mn concentration was only considerable in the lungs and spleens at 24 h, and emerged concentration was found in the liver in 96 h samples. Histopathology demonstrated emerged siderin content in the spleens of the treated animals and in siderin filled macrophages in the lungs mostly in all treated groups. Traces of high-level glycogen retention was found in the MMA groups at both sampling times. Similar glycogen retention in TIG-Ms and TIG stainless group's liver samples and emerged number of vacuoles, especially in the hepatocytes of the TIG-stainless steel 96 h group were also found. The mentioned results raise the consequence that there is a considerable difference in the kinetics of the Mn distribution between the MMA- and the TIG-fume-treated groups. Hence, the result suggests that manganese has a particle-size-dependent toxico-kinetics property. The anomaly of the glycogen metabolism indicates the systemic effect of the welding fumes. Also, the numerous vacuoles mentioned above show a possible liver-specific adverse effect of some components of the TIG-stainless steel welding fumes.

Analytical method using SEM-EDS for metal elements present in particulate matter generated from stainless steel flux-cored arc welding process

Welding fumes (WFs) can cause occupational pneumonoconiosis and other diseases in workers. WFs have complex chemical composition and morphology depending on the welding conditions. The WF surface is a key factor affecting those diseases. The objective of this study was to establish an analytical method focused on characterizing individual WFs and welding slags (WSs) formed during CO₂ arc welding processes for knowledge acquisition of risk assessment. Especially, the characterization was focused on the elemental distributions near the surfaces obtained using fluxing agents and size of the WFs. WFs were collected using personal samplers. After welding, WS was also collected. The fluxing elemental distribution (e.g., Bi) near the surfaces WS and WFs were analyzed through scanning electron microscopy and energy-dispersive X-ray spectroscopy. As a result, some of the micron-sized spherical particles (SPs) grew by incorporating nanosized primary particles composed of other metal species. The fluxing agents formed elemental distribution patterns on the SP surface. Bi were dotted in an agglomerate. Mn amount in WS depends on Mn amount in the WFs. These results obtained through the analysis of both the WS and WF surface as well as the particle sizes will facilitate the establishment of exposure assessment models.

Distribution of Lung-RADS categories according to job type in a single shipyard workers

Background

Recently, lung cancer screenings based on age and smoking history using low-dose computed tomography (LDCT) have begun in Korea. This study aimed to evaluate the distribution of lung imaging reporting and data system (Lung-RADS) categories in shipyard workers exposed to lung carcinogens such as nickel, chromium, and welding fumes according to job type, to provide basic data regarding indications for LDCT in shipyard workers.

Methods

This study included 6,326 workers from a single shipyard, who underwent health examinations with LDCT between January 2010 and December 2018. Data on age, smoking status and history, medical history, and job type were investigated. The participants were categorized into high-exposure, low-exposure, and non-exposure job groups based on the estimated exposure level of nickel, chromium, and welding fumes according to job type. Cox proportional hazard regression analysis was used to determine the difference between exposure groups in Lung-RADS category ≥ 3 (3, 4A, and 4B).

Results

Out of all participants, 97 (1.5%) participants were classified into Lung-RADS category ≥ 3 and 7 (0.1%) participants were confirmed as lung cancer. The positive predictive value (ratio of diagnosed lung cancer cases to Lung-RADS category ≥ 3) was 7.2%. The hazard ratio (HR) of Lung-RADS category ≥ 3 was 1.451 (95% confidence interval [CI]: 0.911–2.309) in low-exposure and 1.692 (95% CI: 1.007–2.843) in high-exposure job group. Adjusting for age and pack-years, the HR was statistically significant only in the high-exposure job group (HR: 1.689; 95% CI: 1.004–2.841).

Conclusions

Based on LDCT and Lung-RADS, among male shipyard workers, Lung-RADS category ≥ 3 were significantly higher in the high-exposure job group. Their HR tended to be > 1.0 and was statistically significant in the high-exposure job group. Additional studies should be conducted to establish more elaborate LDCT indications for occupational health examination.

[Research on the short-term effects of welding fumes on workers' lung function: a panel study]

Objective: To explore the short-term effects of welding fumes on workers' lung function in the welding environment preliminarily, and provide reference for future research. Methods: In October 2020, the lung function of the subjects was repeatedly measured before and after the working shift with a panel study. The paired t test was used to compare the lung function before and after the shift, and the linear mixed effects model was used to analyze the short-term changes of lung function. Results: 36 male welders were included, and the average age was (30.72±5.21) years, average employed year was (4.36±2.17) years. And the average concentration of welding fume was (1.27±0.49) mg/m(3). The forced vital capacity (FVC) , forced expiratory volume in the first second (FEV1) and peak expiratory flow (PEF) of welders after the shift were significantly lower than those before the shift (t=19.52, 48.13, 62.03, P<0.05) . After adjusting the workers' age, BMI and employed years, the changes of FVC% and FEV1% with the concentration of welding fume were statistically significant (β=-1.02, 95%CI: -1.54--0.52; β=-1.56, 95%CI: -1.95--1.16; P<0.01) . In another word, for the 1 mg/m(3) increase of welding fume in the working environment, compared with the baseline, the FVC decreases by 1.02%, and FEV1 decreases by 1.56%. Conclusion: Short-term exposure to welding fumes in workplace can reduce the lung function of welders.

Metal enriched quasi-ultrafine particles from stainless steel gas metal arc welding induced genetic and epigenetic alterations in BEAS-2B cells

Recent evidence has supported welding fume (WF)-derived ultrafine particles (UFP) could be the driving force of their adverse health effects. However, UFP have not yet been extensively studied and are currently not included in present air quality standards/guidelines. Here, attention was focused on the underlying genetic and epigenetic mechanisms by which the quasi-UFP (Q-UFP, i.e., ≤ 0.25 μm) of the WF emitted by gas metal arc welding-stainless steel (GMAW-SS) exert their toxicity in human bronchial epithelial BEAS-2B cells. The Q-UFP under study showed a monomodal size distribution in number centered on 104.4 ± 52.3 nm and a zeta potential of -13.8 ± 0.3 mV. They were enriched in Fe > Cr > Mn > Si, and displayed a relatively high intrinsic oxidative potential. Dose-dependent activation of nuclear factor erythroid 2-related factor 2 and nuclear factor-kappa B signaling pathway, glutathione alteration, and DNA, protein and lipid oxidative damage were reported in BEAS-2B cells acutely (1.5 and 9 μg/cm², 24 h) or repeatedly (0.25 and 1.5 μg/cm², 3 × 24 h) exposed to Q-UFP (p < 0.05). Alterations of the Histone H3 acetylation were reported for any exposure (p < 0.05). Differentially regulated miRNA and mRNA indicated the activation of some critical cell signaling pathways related to oxidative stress, inflammation, and cell cycle deregulation towards apoptosis. Taken together, these results highlighted the urgent need to better evaluate the respective toxicity of the different metals and to include the Q-UFP fraction of WF in current air quality standards/guidelines relevant to the occupational settings.

[Application of five methods in the occupational health risk assessment of workers exposed to welding fumes]

Objective: To assess the health risks of welding fume jobs with five occupational health risk assessment methods, and to compare the advantages, disadvantages and applicability of these methods in the health risk assessment of welding fume. Methods: The International Commission for Mining and Metals (ICMM) occupational health risk assessment method, MES method, the qualitative method and comprehensive index method in GBZ/T 298-2017 "Technical Guidelines for Occupational Health Risk Assessment of Chemical Hazardous Factors in the Workplace" were used to assess the risk of welding fume exposure positions in four manufacturing enterprises in Tianjin in March, 2020. The assessment results of different methods were standardized by risk ratio (RR) . Results: After the results were standardized, the results of enterprises 1, 2 and 4 were negligible risks, enterprise 3 was medium risk in the ICMM matrix method and MES method, and the results of ICMM quantitative method for each enterprise were negligible risk, low risk, extremely high risk and low risk, respectively. The results of the qualitative assessment of the guidelines for all companies were negligible risks, and the comprehensive index method were medium risks. Conclusion: The five models are all suitable for occupational health risk assessment of welding fumes, but they all have certain shortcomings. They should be combined with qualitative and semi-quantitative assessment results for comprehensive analysis.

[Results analysis of occupational physical examination for major occupational hazards exposed laborer in 2018 in Guangzhou]

Objective: To analyze the results of occupational physical examination for major occupational hazard exposed laborer in 2018 in Guangzhou, to provide scientific basis for occupational health supervise. Methods: In January 2019, descriptive epidemiological methods were used as the data sources of the Occupational Disease and Occupational Health Information Surveillance System and the report data of Guangzhou Occupational Health Inspection Agency, collecting 2733 employers from 28 Occupational Health Inspection Organizations in 11 administrative regions of Guangzhou from January to December 2018, as well as the occupational health examination data of 97688 workers exposed to the occupational-disease-risk factors, to analyze the inspection of suspected occupational diseases and contraindications during the period of work of the workers who were monitored for the occupational hazard factors (silicon dust, welding fume, benzene, lead, Ethylene Dichloride, N-hexane, high temperature and hand-transmitted vibration) . Results: Total 128 cases of suspected occupational disease were detected, including 3 suspected silicosis, 8 suspected welder＇s pneumoconiosis, 17 suspected other pneumoconiosis, 10 suspected benzene poisoning, 1 suspected lead poisoning and 89 suspected noise deafness. There were 2061 cases of occupational contraindication, among which 550 cases were contraindication of high temperature, 261 cases were benzene and 1089 cases were noise. Conclusion: The Occupational Health Inspection Institution of this city should continuously monitor the occupational health status of the harmful workers during their work, do a good job of prevention, and strengthen the labor protection.

[An investigation of occupational exposure to welding fume, manganese, and manganese compounds in a large container manufacturing enterprise]

Objective: To investigate the current status of the occupational hazards of welding fume, manganese, and manganese compounds in the welding environment of a large container manufacturing enterprise, as well as the status of occupational health examination of workers, and to provide a basis for improving the welding environment of this enterprise. Methods: In August 2016, July 2017, and August 2018, convenience sampling was used to perform an on-site occupational hygiene survey of the welding workshop for three consecutive years, and welding fume, manganese and, manganese compounds (counted as manganese dioxide) were measured for their workplace exposure concentrations and exposure levels in workers. A comprehensive analysis was performed for the results of occupational health examination. Results: Welding fume, manganese, and manganese compounds in the welding environment gradually increased from 2016 to 2018 (χ(2)(trend)=5.14 and 5.54, P<0.05). The maximum over-standard rate of concentration-short term exposure limit was 43.3% (13/30) for welding fume and 40.0% (12/30) for manganese and its compounds, and the maximum over-standard rate of time-weighted average concentration was 26.7% (8/30) for welding fume and 23.3% (7/30) for manganese and its compounds. Abnormalities were observed in the occupational health examination of welding workers in 2016-2018, among which respiratory system abnormalities (cough, expectoration, and wheezing), nervous system abnormalities (dizziness, fatigue, sleep disorders, amnesia, hyperhidrosis, and palpitations), and electrocardiogram abnormalities (bundle conduction block) had an incidence rate of above 10.0%, and the incidence rate of abnormalities on posterior-anterior X-ray high-kV chest radiograph was close to 8.9% (30/336) . Conclusion: There is severe exposure to welding fume, manganese, and manganese compounds among workers in this enterprise, which cause great hazards to the health of workers. It is necessary to strengthen occupational health management, take measures to improve the welding environment, and enhance occupational disease prevention.

Mass-size distribution and concentration of metals from personal exposure to arc welding fume in pipeline construction: a case report

We investigate exposure to welding fume metals in pipeline construction, which are responsible for severe respiratory problems. We analyzed air samples obtained using size-fractioning cascade impactors that were attached to the welders performing shielded metal and gas tungsten arc welding outdoors. Iron, aluminum, zinc, chromium, manganese, copper, nickel, and lead concentrations in the water-soluble (WS) and water-insoluble (WI) portions were determined separately, using inductively coupled plasma mass spectrometry. The mass-size distribution of welding fume matches a log-normal distribution with two modes. The metal concentrations in the welding fume were ranked as follows: Fe>Al>Zn>Cr>Mn>Ni>Cu>Pb. In the WS portion, the capacities of metals dissolving in water are correlated with the metal species but particle sizes. Particularly, Zn, Mn, and Pb exhibit relatively higher capacities than Cu, Cr, Al, Fe, and Ni. Exposure of the gas-exchange region of the lungs to WS metals were in the range of 4.9% to 34.6% of the corresponding metals in air by considering the particle-size selection in lungs, metal composition by particle size, and the capacities of each metal dissolving in water.

Altered ion transport in normal human bronchial epithelial cells following exposure to chemically distinct metal welding fume particles

Welding fume inhalation causes pulmonary toxicity, including susceptibility to infection. We hypothesized that airway epithelial ion transport is a target of fume toxicity, and investigated the effects of fume particulates from manual metal arc-stainless steel (MMA-SS) and gas metal arc-mild steel (GMA-MS) on ion transport in normal human bronchial epithelium (NHBE) cultured in air-interface. MMA-SS particles, more soluble than GMA-MS particles, contain Cr, Ni, Fe and Mn; GMA-MS particles contain Fe and Mn. MMA-SS or GMA-MS particles (0.0167-166.7μg/cm²) were applied apically to NHBEs. After 18h transepithelial potential difference (V_t), resistance (R_t), and short circuit current (I_sc) were measured. Particle effects on Na⁺ and Cl¯ channels and the Na⁺,K⁺,2Cl¯-cotransporter were evaluated using amiloride (apical), 5-nitro-2-[(3-phenylpropyl)amino]benzoic acid (NPPB, apical), and bumetanide (basolateral), respectively. MMA-SS (0.0167-16.7μg/cm²) increased basal V_t. Only 16.7μg/cm² GMA-MS increased basal V_t significantly. MMA-SS or GMA-MS exposure potentiated I_sc responses (decreases) to amiloride and bumetanide, while not affecting those to NPPB, GMA-MS to a lesser degree than MMA-SS. Variable effects on R_t were observed in response to amiloride, and bumetanide. Generally, MMA-SS was more potent in altering responses to amiloride and bumetanide than GMA-MS. Hyperpolarization occurred in the absence of LDH release, but decreases in V_t, R_t, and I_sc at higher fume particulate doses accompanied LDH release, to a greater extent for MMA-SS. Thus, Na⁺ transport and Na⁺,K⁺,2Cl¯-cotransport are affected by fume exposure; MMA-MS is more potent than GMA-MS. Enhanced Na⁺ absorption and decreased airway surface liquid could compromise defenses against infection.

Increase in oxidative stress levels following welding fume inhalation: a controlled human exposure study

BACKGROUND

Tungsten inert gas (TIG) welding represents one of the most widely used metal joining processes in industry. It has been shown to generate a large majority of particles at the nanoscale and to have low mass emission rates when compared to other types of welding. Despite evidence that TIG fume particles may produce reactive oxygen species (ROS), limited data is available for the time course changes of particle-associated oxidative stress in exposed TIG welders.

METHODS

Twenty non-smoking male welding apprentices were exposed to TIG welding fumes for 60 min under controlled, well-ventilated settings. Exhaled breathe condensate (EBC), blood and urine were collected before exposure, immediately after exposure, 1 h and 3 h post exposure. Volunteers participated in a control day to account for oxidative stress fluctuations due to circadian rhythm. Biological liquids were assessed for total reducing capacity, hydrogen peroxide (H2O2), malondialdehyde (MDA), and 8-hydroxy-2'-deoxyguanosine (8-OHdG) concentrations at each time point. A linear mixed model was used to assess within day and between day differences.

RESULTS

Significant increases in the measured biomarkers were found at 3 h post exposure. At 3 h post exposure, we found a 24 % increase in plasma-H2O2 concentrations ([95%CI: 4 % to 46 %], p = 0.01); a 91 % increase in urinary-H2O2 ([2 % to 258 %], p = 0.04); a 14 % increase in plasma-8-OHdG ([0 % to 31 %], p = 0.049); and a 45 % increase in urinary-8-OHdG ([3 % to 105 %], p = 0.03). Doubling particle number concentration (PNC) exposure was associated with a 22 % increase of plasma-8-OHdG at 3 h post exposure (p = 0.01).

CONCLUSION

A 60-min exposure to TIG welding fume in a controlled, well-ventilated setting induced acute oxidative stress at 3 h post exposure in healthy, non-smoking apprentice welders not chronically exposed to welding fumes. As mass concentration of TIG welding fume particles is very low when compared to other types of welding, it is recommended that additional exposure metrics such as PNC are considered for occupational risk assessments. Our findings highlight the importance of increasing awareness of TIG welding fume toxicity, especially given the realities of welding workplaces that may lack ventilation; and beliefs among interviewed welders that TIG represents a cleaner and safer welding process.

Inverse association between toenail arsenic and body mass index in a population of welders

Recent data show that arsenic may play a role in obesity-related diseases. However, urinary arsenic studies report an inverse association between arsenic level and body mass index (BMI). We explored whether toenail arsenic, a long-term exposure measure, was associated with BMI in 74 welders with known arsenic exposure. BMI showed significant inverse associations with toenail arsenic (p=0.01), which persisted in models adjusted for demographics, diet and work history. It is unclear whether low arsenic biomarker concentrations in high BMI subjects truly reflect lower exposures, or instead reflect internal or metabolic changes that alter arsenic metabolism and tissue deposition.

Cancer Risk Assessment in Welder's Under Different Exposure Scenarios

BACKGROUND

Welders exposure to nickel and hexavalent chromium in welding fumes is associated with increase of cancer risk in welders. In this study we calculated cancer risk due to exposure to these compounds in welders.

METHODS

The role of exposure parameters in welders on derived incremental lifetime cancer risk were determined by stochastic modeling of cancer risk. Input parameters were determined by field investigation in Iranian welders in 2013 and literature review.

RESULTS

The 90% upper band cancer risk due to hexavalent chromium and nickel exposure was in the range of 6.03E-03 to 2.12E-02 and 7.18E-03 to 2.61E-02 respectively. Scenario analysis showed that asthmatic and project welders are significantly at higher cancer risk in comparison with other welders (P<0.05). Shift duration was responsible for 37% and 33% of variances for hexavalent chromium and nickel respectively.

CONCLUSIONS

Welders are at high and unacceptable risk of cancer. Control measures according to scenario analysis findings are advisable.

Assessment of welders exposure to carcinogen metals from manual metal arc welding in gas transmission pipelines, iran

BACKGROUND

Welding can produce dangerous fumes containing various metals especially carcinogenic ones. Occupational exposure to welding fumes is associated with lung cancer. Therefore, welders in Gas Transmission Pipelines are known as a high-risk group. This study was designed to determinate the amounts of metals Cr, Ni, and Cd in breathing zone and urine of welders and to assess the possibility of introducing urinary metals as a biomarker due to occupational exposure.

METHODS

In this cross sectional study, 94 individuals from Gas Transmission Pipelines welders, Iran, Borujen in 2011 were selected and classified into 3 groups including Welders, Back Welders and Assistances. The sampling procedures were performed according to NIOSH 7300 for total chromium, nickel, and cadmium and NIOSH 7600 for Cr+6. For all participants urine samples were collected during the entire work shift and metals in urine were determined according to NIOSH 8310.

RESULTS

Back Welders and Assistances groups had maximum and minimum exposure to total fume and its elements, respectively. In addition, results showed that there are significant differences (P<0.05) between Welders and Back Welders with Assistances group in exposure with total fume and elements except Ni. Urinary concentrations of three metals including Cr, Cd and Ni among all welders were about 4.5, 12 and 14-fold greater than those detected in controls, respectively. Weak correlations were found between airborne and urinary metals concentrations (R2: Cr=0.45, Cd=0.298, Ni=0.362).

CONCLUSION

Urinary metals concentrations could not be considerate as a biomarker for welders' exposure assessment.