1. Department of Dermato-Allergology; National Allergy Research Centre, Copenhagen University Hospital Gentofte; 2900 Hellerup Denmark
2. Department of Dermato-Allergology; Copenhagen University Hospital Gentofte; 2900 Hellerup Denmark
3. The National Research Centre for the Working Environment; 2100 Copenhagen Denmark
4. Department of Occupational and Environmental Medicine; Copenhagen University Hospital Bispebjerg; 2400 Copenhagen Denmark