1. Department of Dermatology and Allergy, Technical University of Munich, 80802 Munich, Germany
2. Department of Medical Informatics, Biometry and Epidemiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
3. Section for Environmental Monitoring and Radon- and UV-Protection, Norwegian Radiation and Nuclears Safety Authority, NO-1332 Østeras, Norway