1. Department of Occupational Medicine and Epidemiology; National Institute of Occupational Health (STAMI); N-0033 Oslo Norway
2. Department of National Work Environment Surveillance; National Institute of Occupational Health; N-0033 Oslo Norway
3. Norwegian Labour Inspectorate; 7468 Trondheim Norway
4. Department of Dermatology; Oslo University Hospital and Institute of Clinical Medicine, University of Oslo; 03180 Oslo Norway