Occupational solar UV-exposure and risk of cutaneous melanoma among Danish workers: A nationwide cohort study

Cutaneous melanoma poses a growing global health concern, with solar ultraviolet radiation (UVR) as its main risk factor. Outdoor workers may be at increased risk due to prolonged occupational solar UVR exposure, but evidence remains limited.

To examine the risk of melanoma associated with occupational solar UVR exposure in a nationwide cohort of Danish workers.

Using Danish national registers, we established a cohort of all individuals employed between 1977 and 2015 and linked occupational histories to first-time melanoma diagnoses in the Danish Cancer Registry. Cumulative occupational solar UVR exposure was estimated by matching occupational histories to a European job exposure matrix and expressed as cumulative standard erythema dose (SED)-years. Incidence rate ratios (IRRs) for cutaneous melanoma were calculated using discrete-time hazard models, and exposure-response relations were further examined with restricted cubic splines. We adjusted for age, sex, calendar year, smoking, dermatological or immunological disease, organ transplantation, parental history of melanoma and medications.

Among 2.9 million workers followed for a median of 19 years, 11,344 workers developed cutaneous melanoma. The median cumulative occupational solar UVR exposure was 5.99 SED-years. Melanoma incidence increased with increasing cumulative exposure, reaching a peak IRR of 1.59 (1.43-1.76) at 14.80 SED-years in the spline analysis, and with an adjusted IRR of 1.57 (95% CI: 1.43-1.71) for workers in the highest vs. the lowest exposure quartile.

Occupational solar UVR exposure was associated with an exposure-response relation increase in melanoma risk. These findings highlight the urgent need for workplace sun-protection policies.