1. Departmento de Dermatologia, Universidad de Sevilla, Avenida Dr Fedriani S/N, 41071 - Sevilla, Spain
2. Institute of Environmental Chemistry, University of Umeå, S-901 87 Umeå, Sweden
3. MRC Toxicology Unit, MRC Laboratories, Woodmansterne Road, Carshalton, Surrey, SM5 4EF, UK