Occupational Exposure to Welding Fumes and the Risk of Bladder Cancer: A Systematic Review and Meta-Analysis.

[BACKGROUND] Occupational exposure to welding fumes has been suggested as a potential risk factor for bladder cancer, but evidence remains inconclusive. This review aimed to systematically evaluate the association between welding fume exposure and risk of bladder cancer through a meta-analysis of observational studies.

[METHODS] A comprehensive literature search was conducted in PubMed, Embase, and the Cochrane Library. Eligible studies were identified based on predefined criteria. The pooled odds ratio (OR) and 95% confidence interval (CI) were calculated using a random-effects model. Subgroup analyses were performed based on study design, publication year, geographic region, sex, and exposure assessment methods.

[RESULTS] A total of 34 epidemiological studies were included. The pooled analysis revealed a 20% increased risk of bladder cancer among welders (OR = 1.20, 95% CI: 1.11-1.30). This association remained statistically significant in analyses restricted to studies that adjusted for both age and smoking. Subgroup analyses indicated variation by publication period, geographic region, and exposure assessment method. Sensitivity analyses restricted to high-quality studies confirmed the robustness of the findings.

[CONCLUSIONS] Welding fume exposure is associated with an elevated risk of bladder cancer. These findings suggest the need for improved occupational safety measures, exposure monitoring, and further research to clarify underlying biological mechanisms and dose-response relationships.