Effects Of Radon And Uv Exposure On Skin Cancer Mortality In Switzerland

Abstract

Background: Melanoma and non-melanoma skin cancer are among the most common types of cancer in Switzerland. Risk factors include exposure to ultraviolet (UV) radiation. Recently, radon attached on particles deposited on the skin has been suggested as an additional risk factor. Exposure gradients in Switzerland are considerable due to large differences in altitude (UV increases with altitude) and in geology and soil type (with varying radon levels). We aimed to investigate the mutual effects of UV and radon exposure on skin cancer mortality. Methods: The association between UV and radon exposure on skin cancer mortality (IDC10: C43-44) was investigated by Cox regression, with age as the underlying time scale and adjusted for confounders. We defined the starting at-risk population as adults aged 30+ from 01 Jan 2000, and applied right censoring at the age of event (death by skin cancer), emigration, or end of follow-up (31 Dec 2008). Exposure was modelled at address-level, representative of the period 2000-2008. Radon exposure was based on a national exposure prediction model developed and validated with the measurements from the Swiss Radon Database. Long-term UV exposure was modelled by linear regression using measurements of daily maximum UV index at 4 Swiss locations, 10x10km monthly global radiation grids and a 25x25m digital terrain model. Preliminary Results: The study population included 4.3 million adults and ~2300 deaths with skin cancer as the definitive primary cause. There was no correlation between the radon and long-term UV exposure (r = -0.01). Controlling for the alternate exposure, age-sex adjusted hazard ratios were 1.24 (95% CI: 1.10-1.39) per 100 Bq/m3 for radon and 1.08 (0.93-1.27) per increment in the UV index. Conclusions: A better understanding of the role of the UV radiation and radon exposure for skin cancer is of high public health relevance. Our study suggests that both radon and UV are risk factors for skin cancer.