Exposure to Welding Fumes, Hexavalent Chromium, or Nickel and Lung Cancer Risk.

To investigate lung cancer risk of welding fumes, hexavalent chromium (Cr(VI)), and nickel (Ni), we analyzed 3,418 male lung cancer cases and 3,488 controls from two German case-control studies (1988-1996). We developed a welding-process exposure-matrix from measurements of these agents, which was linked with welding histories from a job-specific questionnaire to calculate cumulative exposure variables. Logistic regression models were fitted to estimate odds ratios with confidence intervals (CI) conditional on study and adjusted for age, smoking, and working in other at-risk occupations. Additionally, we mutually adjusted for the other exposure variables under study. Overall, 800 cases and 645 controls ever worked as regular or occasional welder. Odds ratios between lung cancer and high exposure were 1.55 (95% CI: 1.17, 2.05; median, 1.8 mg/m3 years) for welding fumes, 1.85 (95% CI: 1.35, 2.54; median, 1.4 μg/m3 years) for Cr(VI), and 1.60 (95% CI: 1.21, 2.12; median, 9 μg/m3 years) for Ni. Risk estimates increased with increasing cumulative exposure to welding fumes and with increasing exposure duration to Cr(VI) and to Ni. Our results showed that welding fumes, Cr(VI), and Ni may contribute independently to the excess lung cancer risk associated with welding. However, quantitative exposure assessment remains challenging.