Effects of Exposure to Welding Fume on Lung Function: Results from the German WELDOX Study

Investigating the field effectiveness of respirators against metal particle exposure in various workplaces: a systematic review

Welders are exposed to high levels of metal fumes, which could be resulting in various health impairments. Respirators became a practical protective option in workplaces, as they are lightweight and easy to use. This systematic review attempts to explore the field effectiveness of using respirators to reduce metal particle exposure in workplaces. We reviewed papers published from 1900 to April 2019 in five major bibliographic databases, including Embase, Web of Science, Medline, Scopus, and CINAHL, along with organizational websites to cover gray literature. In total, 983 references were identified from the databases, out of which, 520 duplicates were removed from the EndNote database. The remaining 463 references were screened for their title and abstract. Out of 463, 70 references went through the full-text screening. Finally, eight papers, including 19 workplace respirator studies, satisfied all the inclusion criteria and were reviewed in this report. The geometric means for metal levels in workers' breathing zone with and without respirators were 9.4 and 1,777 µg/m³ for iron, 1.1 and 139 µg/m³ for lead, 2.1 and 242 µg/m³ for zinc, and 27 and 1,398 µg/m³ for manganese oxide, respectively. Most reviewed studies reported significant differences between measured metal particle levels among workers who worn respirators and who did not. In addition, results showed that N95 provided significantly less protection than elastomeric half facepieces, full-face respirators, and powered air-purifying respirators (p<0.001). More field studies are recommended to investigate Workplace Protection Factor (WPF) and fit factor (FF) of different respirators to understand the actual protection levels that they could be provided to control welding fume exposure among welders in various workplaces.

Modelled lung deposition and retention of welding fume particles in occupational scenarios: a comparison to doses used in vitro

Translating particle dose from in vitro systems to relevant human exposure remains a major challenge for the use of in vitro studies in assessing occupational hazard and risk of particle exposure. This study aimed to model the lung deposition and retention of welding fume particles following occupational scenarios and subsequently compare the lung doses to those used in vitro. We reviewed published welding fume concentrations and size distributions to identify input values simulating real-life exposure scenarios in the multiple path particle dosimetry (MPPD) model. The majority of the particles were reported to be below 0.1 μm and mass concentrations ranged between 0.05 and 45 mg/m³. Following 6-h exposure to 5 mg/m³ with a count median diameter of 50 nm, the tracheobronchial lung dose (0.89 µg/cm²) was found to exceed the in vitro cytotoxic cell dose (0.125 µg/cm²) previously assessed by us in human bronchial epithelial cells (HBEC-3kt). However, the tracheobronchial retention decreased rapidly when no exposure occurred, in contrast to the alveolar retention which builds-up over time and exceeded the in vitro cytotoxic cell dose after 1.5 working week. After 1 year, the tracheobronchial and alveolar retention was estimated to be 1.15 and 2.85 µg/cm², respectively. Exposure to low-end aerosol concentrations resulted in alveolar retention comparable to cytotoxic in vitro dose in HBEC-3kt after 15-20 years of welding. This study demonstrates the potential of combining real-life exposure data with particle deposition modelling to improve the understanding of in vitro concentrations in the context of human occupational exposure.

Welding Fumes, a Risk Factor for Lung Diseases

(1) Background: Welding fumes (WFs) are composed of fine and ultrafine particles, which may reach the distal airways and represent a risk factor for respiratory diseases. (2) Methods: In vitro and in vivo studies to understand WFs pathogenesis were selected. Epidemiological studies, original articles, review, and meta-analysis to examine solely respiratory disease in welders were included. A systematic literature search, using PubMed, National Institute for Occupational Safety and Health Technical Information Center (NIOSHTIC), and Web of Science databases, was performed. (3) Results: Dose, time of exposure, and composition of WFs affect lung injury. Inflammation, lung defense suppression, oxidative stress, DNA damage, and genotoxic effects were observed after exposure both to mild and stainless steel WFs. (4) Conclusions: The detection of lung diseases associated with specific occupational exposure is crucial as complete avoidance or reduction of the exposure is difficult to achieve. Further studies in the area of particle research may aid the understanding of mechanisms involved in welding-related lung disease and to expand knowledge in welding-related cardiovascular diseases.

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.

Analysis of inflammatory markers and metals in nasal lavage fluid of welders

Welding fumes may produce adverse health effects in the respiratory tract. To assess the relationship between exposure to welding fumes and inflammation in the upper airways, 190 male welders were examined from the WELDOX study (median age 40 yr, 54.7% smokers, and 32.9% atopics). Inhalable welding fumes were collected in the breathing zone of welders during a single shift. Chromium (Cr), nickel (Ni), manganese (Mn), and iron (Fe) were measured in the welding-fume samples and in postshift nasal lavage fluid (NALF). In addition, the numbers of particles and inflammatory biomarkers, including total and differential cell counts, interleukin (IL)-8, leukotriene (LT) B₄, 8-isoprostane (8-iso-PGF_2α), tissue inhibitor of metalloproteinase-1 (TIMP-1), and immunoreactive matrix metalloproteinase (MMP)-9, were determined. Metal concentrations in NALF correlated with airborne concentrations. No significant association was found between airborne metal concentrations and biomarkers of inflammation in NALF, whereas increasing metal concentrations in NALF resulted in increased concentrations of total protein, IL-8, MMP-9, and TIMP-1. LTB₄ and 8-iso PGF_2α were elevated at higher concentrations of Cr or Ni in NALF. The same was true for Fe, although the effects were less pronounced and of borderline significance. In conclusion, our results showed a significant association between the concentrations of metals and soluble inflammatory markers in the NALF of welders. The noninvasive collection of NALF is applicable in field studies, where it may serve as a suitable matrix to simultaneously assess biomarkers of exposure and effect in the upper respiratory tract in workers who are occupationally exposed to airborne hazardous substances.