1. Department of Medical Informatics, Biometry and Epidemiology; University of Erlangen/Nürnberg; 91054 Erlangen Germany
2. Department of Public Health, Occupational Medicine; University of Trieste; 34129 Trieste Italy
3. Department of Dermatology; University of Naples Federico II; 80131 Naples Italy
4. Department of Dermatology; Chapel Allerton Hospital; LS7 4SA Leeds UK
5. Nofer Institute of Occupational Medicine; 91-348 Lodz Poland
6. Faculty of Medicine and Health Science, Institute of Medical Science; Jan Kochanowski University; 25-317 Kielce Poland
7. Department of Dermatology, University Medical Centre Groningen; University of Groningen; 9700 RB Groningen The Netherlands
8. previously Department of Dermatology; University of Witten/Herdecke; 58448 Witten Germany
9. previously Department of Dermatology; Klinikum Dortmund; 44137 Dortmund Germany
10. Allergy Unit, Department of Dermatology; University Hospital and University of Basel; 4031 Basel Switzerland