Objectives: Most studies on occupational risk factors for melanoma have focused on ultra-violet radiation (UVR) exposure from outdoor work. This study investigates a broader range of occupational exposures including UVR, ionizing and non-ionizing radiation, benzene, poly- and monocyclic aromatic hydrocarbons, hexavalent chromium, nickel, coal tar, black carbon, ozone, soot and nitrous oxides with skin cancer in a working-age population-based prospective cohort.

Methods: Adult residents (20 to 65 years) in the cantons of Fribourg, Ticino, Vaud, Valais, Neuchâtel, and Genève at the 2000 census were included (n = 1,077,487). Incident cases of primary melanoma and squamous cell carcinoma (SCC) of the skin were retrieved from cantonal cancer registries until 2012. Job-exposure matrices were used to assign exposures, using two assessment methods to explore exposure misclassification (i.e. conservative approach for main analyses vs. inclusive approach for sensitivity analyses). Cox proportional hazard models, with age as timescale and adjusted for demographic and environmental factors (residential radon, ambient UVR, and PM_2.5 concentrations) were used to estimate hazard ratios (HR) in relation to each occupational exposure.

Results: 2757 incident melanoma cases were observed during an average of 8.4 years follow-up. Occupational exposure to UVR and black carbon were associated with melanoma incidence (HR = 1.23; 95 % CI: 1.02-1.50 and HR = 1.59; 95 % CI: 1.18-2.13, respectively). Occupational exposure to ionizing radiation and ozone were only associated with melanoma when using the inclusive exposure assessment method. No associations were found for SCC incidence.

Conclusion: UVR and air pollution in occupational settings were associated with melanoma incidence. Melanoma related to these risk factors is only recognized as an occupational disease in a few countries, while other occupational risk factors are largely neglected.