1. Institute of Environmental Medicine; Karolinska Institutet; 171 77 Stockholm Sweden
2. Department of Dermato-Allergology, National Allergy Research Centre; Copenhagen University Hospital Gentofte; 2900 Hellerup Denmark
3. Department of Chemistry and Molecular Biology, Dermatochemistry; University of Gothenburg; 405 30 Gothenburg Sweden
4. Department of Medical Informatics, Biometry and Epidemiology; Friedrich-Alexander-University Erlangen/Nürnberg; 91054 Erlangen Germany
5. Department of Cutaneous Allergy, St John's Institute of Dermatology; Guy's Hospital; London SE1 9RT UK