Occupational risk factors, ultraviolet radiation, and ocular melanoma:: a case-control study in France

Background: Ultraviolet radiation has been suspected as a possible cause of ocular melanoma. Because this association is controversial, we examine the role of occupational exposure to ultraviolet radiation on the occurrence of this rare cancer. Material and methods: A population-based case-control study was conducted in 10 French administrative areas (departements). Cases were 50 patients with uveal melanoma diagnosed in 1995-1996. Controls were selected at random from electoral rolls, after stratification for age, gender, and area. Among 630 selected persons, 479 (76%) were interviewed. Data on personal characteristics, occupational history, and detailed information on each job held were obtained from face-to-face interviews using a standardized questionnaire. Estimates of occupational exposure to solar and artificial ultraviolet light were made using a job exposure matrix. Results: Results show elevated risks of ocular melanoma for people with light eye color, light skin color, and for subjects with several eye burns. The analysis based on the job exposure matrix showed a significantly increased risk of ocular melanoma in occupational groups exposed to artificial ultraviolet radiation, but not in outdoor occupational groups exposed to sunlight. An elevated risk of ocular melanoma was seen among welders (odds ratio = 7.3; 95% confidence interval = 2.6-20.1 for men), and a dose-response relationship with job duration was observed. The study also showed increased risk of ocular melanoma among male cooks, and among female metal workers and material handling operators. Conclusion: Following the present study, the existence of an excess risk of ocular melanoma in welders may now be considered as established. Exposure to ultraviolet light is a likely causal agent, but a possible role of other exposures in the welding processes should not be overlooked.