Effects Of Radon And UV Exposure On Skin Cancer Mortality Ů A Swiss National Cohort Analysis

Danielle VIENNEAU, Swiss Tropical and Public Health Institute, Switzerland
DE HOOGH K. 1,2 , HAURI D. 3,4 , VICEDO-CABRERA A. 1,2 , HUSS A. 5 , R÷÷SLI M. 1,2

1 Swiss Tropical and Public Health Institute, Basel, Switzerland
2 University of Basel, Basel, Switzerland
3 Federal Statistical Office, Espace de líEurope 10, Neuch‚tel, Switzerland
4 ImmoCompass AG, Untere Zšune 3, Zurich, Switzerland
5 Institute for Risk Assessment Sciences, University Utrecht, Utrecht, the Netherlands

Purpose: Skin cancer incidence in Switzerland is among the highest in the world. In addition to exposure to ultraviolet (UV) radiation, radon alpha particles attached to aerosols can adhere to the skin and potentially cause carcinogenic effects. Exposure gradients in Switzerland are considerable due to large differences in geology and soil type (radon) and altitude (UV). We investigate the mutual effects of radon and UV exposure on skin cancer mortality.
Methods: Cox proportional hazard regression with age as the time axis was used to study the association between exposures and skin cancer mortality (IDC10: C43-44) in all Swiss adults aged >20 for the period 04 Dec 2000 to 31 Dec 2008 using the Swiss National Cohort. Exposures during the study period were modelled at address-level. Radon derived from our prediction model, validated with measurements from the Swiss Radon Database. Long-term erythemal weighted UV dose was modelled using daily maximum UV index measurements, monthly global radiation, and a digital terrain model. Cox models were adjusted for sex, civil status, language, education, job position, neighbourhood socio-economic position and UV exposure from outdoor occupation.
Results: The study included 4.3 million adults (mean age 48 years) and ~2300 skin cancer deaths (definitive primary cause). Radon and long-term UV exposure were not correlated (r =-0.01). We found the baseline hazard for radon decreased with age. Adjusting for the alternative exposure, hazard ratios ranged from 1.67 (95% CI: 1.17-2.38; at 20 years) to 1.16 (1.06-1.28; at 80 years) per 100 Bq/m3 radon and 1.09 (1.01-1.18; all ages) per 1 W/m2 in UV dose.
Conclusions: Our study suggests both UV and radon are relevant risk factors. A better understanding of the role of radon exposure in relation to skin cancer risk is of high public health relevance.
Funding source: Swiss National Science Foundation