1. National Allergy Research Center, Department of Dermatology and Allergy, Herlev and Gentofte Hospital University of Copenhagen Hellerup Denmark
2. Research Centre for Beauticians and Hairdressers, Department of Dermatology and Allergy, Herlev and Gentofte Hospital University of Copenhagen Hellerup Denmark
3. Department of Medical Informatics, Biometry and Epidemiology Friedrich‐Alexander Universiät Erlangen‐Nürnberg Erlangen Germany
4. Department of Dermatology and Allergy, Herlev and Gentofte Hospital University of Copenhagen Hellerup Denmark