1. Division of Epidemiology and Public Health; University of Nottingham; Clinical Sciences Building (Phase 2) Nottingham NG5 1PB U.K
2. British Geological Survey; Environmental Science Centre; Nottingham NG12 5GG U.K
3. Centre of Evidence Based Dermatology; University of Nottingham; King's Meadow Campus Nottingham NG7 2NR U.K