Systemic inflammatory responses following welding inhalation challenge test

Serum zinc levels and body composition variability as trajectory for hyperlipidemic and dyslipidemic effect among welders exposed to welding fumes and smoking: A biomarker for cardiovascular health

Welding is a common method for joining metals by heating them to the welding temperature. Exposure to welding fumes has a serious effect on the health of welders. This study examined serum zinc variability and body composition as route for hyperlipidemia and dyslipidemia in welders exposed to welding fumes and smoking, exploring the possibilities for the risk of possible cardiovascular disease. The experimental case control design was adopted in the study. Forty apparently healthy adult males were randomly selected comprising of twenty control group (non-smokers and smokers without welding experience) and twenty experimental group (non-smokers and smokers with welding experience) welders. Data obtained were represented as Mean ± SEM while comparison of means across group was done by one-way ANOVA followed by Tukey's multiple comparison for post hoc test at p-value < 0.05 level of significance using Graph Pad prism version 8. The data obtained showed that the body mass index (BMI) of smokers (non-welders and welders) were slightly reduced while that of non-smoking welders was increased compared to the control. The serum zinc level increased among the smoking welders, while the smoking non-welders and non-smoking welders decreased when compared to the control group (p < 0.05). Exposure to welding fumes has been shown to increase total cholesterol levels compared to the control. Weld fumes significantly (p < 0.05) increased high-density lipoproteins (HDL) levels among smoking non-welders compared to the control group, while, HDL was reduced in non-smoking welders and smoking welders, respectively (p < 0.05). Triglyceride levels significantly (p < 0.05) increased in all experimental groups compared to control levels (p < 0.05). Exposure to welding fumes and smoking caused significant changes in serum zinc, HDL and triglycerides levels with implications for the formation of plaques around the arteries interfering with the effective flow of blood through the vascular system, with implications of hyperlipidemia and dyslipidemia. This study recommends that further studies should be done using biomarkers from urine or toe nails.

Effect biomarkers of nanoparticle-exposed workers: A scoping review

The widespread and increasing use of engineered nanomaterials (i.e., particulate materials measuring 1-100 nanometers (nm) in at least one dimension) poses a potential health and safety risk to exposed workers. The unique properties of nanomaterials have made nanomaterials useful in multiple industries. However, their production and use may compromise worker health, presenting an emerging occupational health hazard, the acute and chronic effects of which have not been fully assessed. In this scoping review, we critically assess the literature on biomarkers of effect from nanoparticles and discuss the utility of biomonitoring as a means of assessing the physiological effects of nanoparticle exposure among nanotechnology workers. Multiple databases were queried based on select inclusion and exclusion criteria according to PRISMA guidelines, and articles were independently screened by two topic experts. Of 286 articles initially retrieved, 28 were included after screening and eligibility. The reviewed articles indicated that sensitive effect biomarkers could reflect early health effects of exposure to nanoparticles in the workplace and may be useful for monitoring toxicological effects and associated risks.

Occupational exposure to fine particulate matter in the reinforced concrete production and its association with respiratory symptoms and lung function

BACKGROUND

Reinforced concrete production is widespread, but little is known about the occupational exposure to fine particulate matter (PM) in such workplaces, including from metalworking and concrete processing. Therefore, the aim was to characterize exposure to fine PM in the typical workplaces of the whole production cycle and to quantify the risk of respiratory symptoms and lung function in a cohort of reinforced concrete parts production industry.

METHODS

At a reinforced concrete parts producing facility in Almaty, we collected 50 personal PM2.5 samples from the main exposure sites and the measured mass concentrations using gravimetric method. Workers also completed questionnaires on a detailed working history, respiratory symptoms (chronic obstructive pulmonary disease (COPD) Assessment Tool (CAT)), followed by spirometry. The association of cumulative dose with CAT score and forced expiratory volume in one second (FEV1)/forced vital capacity (FVC) was tested with multiple regression.

RESULTS

The highest PM2.5 concentrations were found in the concrete-mixing unit (median 1180 µg/m3), followed by metalworking (510 µg/m3), armature workshop (375 µg/m3) and molding site (245 µg/m3), different from the concentrations in the office (29.5 µg/m3), Kruskall-Wallis p < 0.001. Cumulative PM2.5 dose, mg/m3-year (beta 0.10 (95% confidence interval (CI) 0.05; 0.15)) was strongly associated with CAT score, whereas production with FEV1/FVC (beta -4.96 (-8.31; -1.61)), independent of smoking and chronic bronchitis and sex.

CONCLUSIONS

Mixing concrete and metalworks pose the greatest risk for worker's health in the reinforced concrete production from the inhalational exposure to aerosol, adversely affecting respiratory health.

Manganese, Iron, Lead, and Zinc Levels and Haematological Profile among Welders in Bibiani Anhwiaso Bekwai District, Ghana

Welders are exposed to metal ions or oxides through direct contact at occupational sites or indirectly through uptake from contaminated dust or air. This study was a case-control study designed to assess the levels of some heavy metals and the hematological profile of welders (cases) as compared to nonwelders (controls) from Bibiani Anhwiaso Bekwai District of Ghana, comparatively to determine whether their values are within acceptable international range. A quantitative-based survey using structured questionnaires was used to collect demographic data from purposively selected welders (n = 40) and nonwelders (n = 40) from the study area. Five (5 mL) blood samples were collected from the study participants and analyzed for blood cell count as well as levels of Mn, Fe, Pb, and Zn. There were no significant differences in the Mn, Zn, and Fe levels between the welders and nonwelders ( $p=0.431$ , 0.53 vs. 0.23 mg/L, $p=0.05$ , 0.41 vs. 0.15, $p=0.886$ , 1.82 vs. 1.11). The level of Pb was, however, significantly lower among welders compared to the nonwelders ( $p=0.016$ , 0.09 < 0.3 mg/L). The total white blood cell count did not differ significantly between welders and nonwelders ( $p=0.365$ , 5.16 vs. 4.85 × 109/L). However, the mixed cell fraction was significantly higher among welders compared to nonwelders ( $p=0.027$ , 0.34 × 109/L > 0.28 × 109/L). Red blood cell count and indices showed no significant differences between the welders and nonwelders. Hemoglobin levels in welders were, however, higher (14.47 g/dL) but this was not statistically significant compared to their nonwelder counterparts (13.85 g/dL). It was concluded from the study that welders in Bibiani Anhwiaso Bekwai District of the Western Region of Ghana had elevated levels of Pb in their bodies. This was associated with an increase in mixed white blood cell fraction platelets. However, the recorded levels were within the accepted physiological limits suggesting that the heavy metal exposure of welders had no clinically pathological significance.

Associations between welding fume exposure and blood hemostatic parameters among workers exposed to welding fumes in confined space in Chonburi, Thailand

Background

Occupational welding fumes contain varieties of toxic metal particles and may affect cardiovascular system like the Particulate Matters (PM). Few studies have focused on the effects of toxic metals on the hemodynamic balance; however, the reporting results were not consistent. This study aimed to investigate the association between toxic metals exposure (Chromium (Cr), Manganese (Mn) and Lead (Pb)) and blood hemostatic parameters status after a 3-week exposure cessation among workers exposed to welding fumes.

Methodology

Structured interviews and biological samplings were conducted for 86 male workers without a history of Anemia and Cardiovascular diseases (CVDs) and working in a confined space to construct crude oil tanks. Metal levels of Cr, Mn and Pb in urine were measured during the working days using Inductively Coupled Plasma Mass Spectrometer (ICP-MS) method. The concentrations of hemostatic proteins in blood (White blood cell counts (WBC), Lymphocytes, Monocyte, Eosinophil, Neutrophil, Hematocrit (Hct) were assessed after a 3 weeks exposure cessation. Workers were divided into groups based on occupation type (welder group and non-welder group), and based on metal levels (high and low exposure groups) for comparison. Linear regression models were used to explore the association between metal exposure and multiple blood hemostatic parameters adjusted for age, Body Mass Index (BMI), and smoking status.

Results

Urine Mn and Cr level of the welder group was significantly higher than the non-welder group (Mn: 0.96 VS 0.22 ug/g creatinine, p < 0.001; Cr: 0.63 VS 0.22 ug/g creatinine, p < 0.01). The mean value of Hct in the welder group was 44.58 ± 2.84 vol%, significantly higher than the non-welder group (43.07 ± 3.31 vol%, p = 0.026). The median value of WBC in the high Mn-exposed group (6.93 ± 1.59 X 10⁶ Cell/ml) was significantly lower than the low Mn-exposed group (7.90 ± 2.13 X 10⁶ Cell/ml, p = 0.018). The linear regression analyses showed that there was a significantly negative association between log transformed WBC value and the Mn exposure groups (high and low) after adjusting for age, BMI, and smoking status (β = - 0.049, p = 0.045), but no significant result was found between WBC and occupation types (welder and non-welder) (p > 0.05). Multiple linear regression analysis also showed positive association between Hct and occupational types (welder and non-welders) (β = 0.014, p = 0.055). The other hemostatic parameters were not different from controls when divided by occupation type or metal level groups.

Conclusions

Our results showed that welders were exposed to about 3 to 4 times higher Mn and Cr concentrations than non-welders. Moreover, one third of the non-welders were exposed to high-exposure groups of Mn and Cr metals. Regression models revealed a significant association of the WBC counts with the Mn exposure group. Therefore, we infer that Mn exposure may play a significant role on the blood hemostatic parameters of workers in the confined space. Hazard identification for non-welders should also be conducted in the confined space.

Fractional exhaled NO in a metalworking occupational cohort

PURPOSE

Secondary metalworking carries exposure to relatively heavy levels of respirable particulate. We investigated the extent to which metalworking is associated with increased exhaled nitric oxide (FeNO), an established inflammatory biomarker.

METHODS

We studied 80 metalworking factory employees in Kazakhstan. Informed by industrial hygiene data, we categorized them into three groups: (1) machine operators (41%); (2) welders or assemblers (33%); and (3) all others, including administrative and ancillary staff (26%). Participants completed questionnaires covering occupational history, smoking, home particulate sources, respiratory symptoms, and comorbidities. We measured exhaled carbon monoxide (CO), exhaled fractional nitric oxide (FeNO), and spirometric function. We used mixed-effects modeling to test the associations of occupational group with FeNO, adjusted for covariates.

RESULTS

The median age was 51.5 (interquartile range 20.5) years; 7% were women. Occupational group (p < 0.01), daily current cigarette smoking intensity (p < 0.05), and age (p < 0.05), each was statistically associated with FeNO. Welders, or assemblers (Group 2), who had intermediate particulate exposure, manifested significantly higher exhaled FeNO compared to machinists (Group 1, with the highest particulate exposure) and all others (Groups 3, the lowest particulate): adjusted Group 2 mean 44.8 ppb (95% confidence interval (CI) 33.8-55.9) vs. Group 1 24.6 ppb (95% 20.5-28.7) and Group 3, 24.3 ppb (95% CI 17.7-30.9). Secondhand smoking and height were not associated with FeNO.

CONCLUSION

In a metalworking industrial cohort, welders/assemblers manifested significantly higher levels of FeNO. This may reflect respiratory tract inflammation associated with airborne exposures specific to this group.

Welding fumes composition and their effects on blood heavy metals in albino rats

Toxic substances produced during welding include heavy metals, carbon monoxide, carbon dioxide, and nitrogen oxides. The study aims to evaluate the heavy metals concentration in welding fumes and the blood of the animals exposed to welding fumes. The fumes were collected from a welding site by a skilled welder and part of it was subjected to metals analysis. A total of 130 rats were divided into 13 groups. 12 groups were given doses calculated to correspond to real-life workers exposure regimes and 1 group served as control. The dosages were administered intratracheally after anesthetization weekly for 12 weeks. The animals were sacrificed and whole blood samples were collected for atomic absorption spectrophotometry. The metals in fumes analyzed were decreasing in order of Fe > K > Pb > Co > Cd > Ca > Ni > Mn > Zn > Cr > Al > Cu > Mg. Changes were observed in the behaviour of the test animals compared to the control indicating probable toxicity. The values of Pb, Cr, Fe, Mn, and Ni in the exposed animal's blood were higher than the control and increased relatively across the treatment groups. However, the values of Al and Zn were not significantly different from the control. These indicate that exposure to welding fumes having contained a significant amount of heavy metals has caused noticeable toxicity symptoms with simultaneous elevation in blood metal levels. Monitoring and regulation of these activities should be enforced by relevant authorities in Kano and Nigeria in general.

Effects of mild steel welding fume particles on pulmonary epithelial inflammation and endothelial activation

Welders have an increased risk for cardiovascular disease (CVD) following exposure to welding fumes. The underlying mechanisms are largely unknown; however, oxidative stress, systemic inflammation, and endothelial dysfunction have been suggested as contributing factors to particle-induced CVD. We investigated effects of mild steel welding fume (MSWF) on three target cell types: macrophages, pulmonary epithelial, and vascular endothelial cells. Cells were exposed to MSWF at nontoxic doses for 6 h/day, for five consecutive days. The expression of 40 genes involved in inflammation, fibrosis, and endothelial activation was analyzed. Moreover, changes in the reactive oxygen species production and migration capacity of cells were assessed. The expression of matrix metallopeptidase 1 (MMP1) was induced in both epithelial and endothelial cells following repeated exposure to MSWF. Although MMP1 is important in inflammatory responses in vivo, this effect was not concurrent with changes in the inflammatory status, cell proliferation, and migration capacities, nor did it induce oxidative stress in the cells. Thus, repeated exposure with low doses of MSWF was sufficient neither for inducing inflammatory stress in epithelial cells and macrophages nor for endothelial activation, and higher concentrations of MSWF or the nonparticle fraction of MSWF may be critical in causing the increased risk of CVD observed among welders.

Endogenous doesn't always mean innocuous: a scoping review of iron toxicity by inhalation

Ambient air pollution is a leading risk factor for the global burden of disease. One possible pathway of particulate matter (PM)-induced toxicity is through iron (Fe), the most abundant metal in the atmosphere. The aim of the review was to consider the complexity of Fe-mediated toxicity following inhalation exposure focusing on the chemical and surface reactivity of Fe as a transition metal and possible pathways of toxicity via reactive oxygen species (ROS) generation as well as considerations of size, morphology, and source of PM. A broad term search of 4 databases identified 2189 journal articles and reports examining exposure to Fe via inhalation in the past 10 years. These were sequentially analyzed by title, abstract and full-text to identify 87 articles publishing results on the toxicity of Fe-containing PM by inhalation or instillation to the respiratory system. The remaining 87 papers were examined to summarize research dealing with in vitro, in vivo and epidemiological studies involving PM containing Fe or iron oxide following inhalation or instillation. The major findings from these investigations are summarized and tabulated. Epidemiological studies showed that exposure to Fe oxide is correlated with an increased incidence of cancer, cardiovascular diseases, and several respiratory diseases. Iron PM was found to induce inflammatory effects in vitro and in vivo and to translocate to remote locations including the brain following inhalation. A potential pathway for the PM-containing Fe-mediated toxicity by inhalation is via the generation of ROS which leads to lipid peroxidation and DNA and protein oxidation. Our recommendations include an expansion of epidemiological, in vivo and in vitro studies, integrating research improvements outlined in this review, such as the method of particle preparation, cell line type, and animal model, to enhance our understanding of the complex biological interactions of these particles.

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.

Mild steel welding is associated with alterations in circulating levels of cancer-related proteins

Welding fumes were recently classified as carcinogenic to humans and worldwide millions work as welders or perform welding operations. The purpose of this study was to identify new biomarkers of welding-induced carcinogenesis. We evaluated a panel of 91 putative cancer-related proteins in serum in a cohort of welders working with mild steel (n = 77) and controls (n = 94) from southern Sweden sampled on two occasions 6-year apart using a longitudinal analysis (linear mixed models). The significant results from the longitudinal analysis were tested for reproducibility in welders (n = 88) and controls (n = 69) sampled once during the same sampling period as timepoint 1 or timepoint 2 (linear regression models), i.e., in a cross-sectional setting. The models were adjusted for age, body-mass index, and use of snus. All study participants were non-smokers at recruitment. Exposure to welding fumes was assessed using questionnaires and respirable dust measurement in the breathing zone that was adjusted for personal respiratory protection equipment. The median respirable dust in welders was 0.7 (0.2-4.2) and 0.5 (0.1-1.9) mg/m³ at the first and second timepoints, respectively. We identified 14 cancer-related proteins that were differentially expressed in welders versus controls in the longitudinal analysis, out of which three were also differentially expressed in the cross-sectional analysis (cross-sectional group). Namely, syndecan 1 (SDC1), folate receptor 1 (FOLR1), and secreted protein acidic and cysteine rich (SPARC) were downregulated, in welders compared with controls. In addition, FOLR1 was negatively associated with years welding. Disease and function analysis indicated that the top proteins are related to lung cancer as well as cell invasion and migration. Our study indicates that moderate exposure to welding fumes is associated with changes in circulating levels of putative cancer-related proteins, out of which FOLR1 showed a clear dose-response relationship. It is, however, unclear to which extent these changes are adaptive or potential early biomarkers of cancer.

Effects of welding fumes on haematological parameters of male albino rats (Rattus norvegicus)

Welders or metal workers not being an exception are exposed to metals ions or oxides (fumes) at trace concentrations either through direct contact supplementation at occupational sites or indirectly through uptake from contaminated food, water or contaminated soil, dust, or air. The study aims to determine the effects of welding fumes exposure on haematological parameters in blood of experimental animals. The fumes were collected from welding sites during the activity by a skilled welder. 130 male experimental animals were utilized and made into 13 groups. 12 groups were given dosages calculated to correspond to real life workers exposure regimes and 1 group served as control. The dosages were administered intratracheally after been anaesthetized weekly for 12 weeks. The animals were sacrificed and whole blood samples were taken which was then subjected to haematological analysis. The parameters have revealed changes in values whereby RBC, WBC, % lymphocytes, HGB, HCT, MCV, MCH, PLT, PCT and P-LCC have exceeds the control groups values. There was an increase across the treatment groups. However, lymphocytes, MID, granulocytes, % granulocytes, MCHC and MPV have values which were less than the control and no different from one another statistically. This indicates that exposure to welding fumes could cause alterations to most RBC, WBC and PLT indices majorly by effecting an increase. Further studies should be carried out on the response of other markers of toxicity so as to have a broad perception of the effects.

Particle and vapor emissions from vat polymerization desktop-scale 3-dimensional printers

Little is known about emissions and exposure potential from vat polymerization additive manufacturing, a process that uses light-activated polymerization of a resin to build an object. Five vat polymerization printers (three stereolithography (SLA) and two digital light processing (DLP) were evaluated individually in a 12.85 m3 chamber. Aerosols (number, size) and total volatile organic compounds (TVOC) were measured using real-time monitors. Carbonyl vapors and particulate matter were collected for offline analysis using impingers and filters, respectively. During printing, particle emission yields (#/g printed) ranged from 1.3 ± 0.3 to 2.8 ± 2.6 x 108 (SLA printers) and from 3.3 ± 1.5 to 9.2 ± 3.0 x 108 (DLP printers). Yields for number of particles with sizes 5.6 to 560 nm (#/g printed) were 0.8 ± 0.1 to 2.1 ± 0.9 x 1010 and from 1.1 ± 0.3 to 4.0 ± 1.2 x 1010 for SLA and DLP printers, respectively. TVOC yield values (µg/g printed) ranged from 161 ± 47 to 322 ± 229 (SLA printers) and from 1281 ± 313 to 1931 ± 234 (DLP printers). Geometric mean mobility particle sizes were 41.1-45.1 nm for SLA printers and 15.3-28.8 nm for DLP printers. Mean particle and TVOC yields were statistically significantly higher and mean particle sizes were significantly smaller for DLP printers compared with SLA printers (p < 0.05). Energy dispersive X-ray analysis of individual particles qualitatively identified potential occupational carcinogens (chromium, nickel) as well as reactive metals implicated in generation of reactive oxygen species (iron, zinc). Lung deposition modeling indicates that about 15-37% of emitted particles would deposit in the pulmonary region (alveoli). Benzaldehyde (1.0-2.3 ppb) and acetone (0.7-18.0 ppb) were quantified in emissions from four of the printers and 4-oxopentanal (0.07 ppb) was detectable in the emissions from one printer. Vat polymerization printers emitted nanoscale particles that contained potential carcinogens, sensitizers, and reactive metals as well as carbonyl compound vapors. Differences in emissions between SLA and DLP printers indicate that the underlying technology is an important factor when considering exposure reduction strategies such as engineering controls.