1. Central Research and Support Establishment, Home Office Forensic Science Service, Aldermaston, Reading, Berkshire, RG7 4PN
2. Toxicology Unit, Department of Cardiological Sciences, St George's Hospital Medical School, Cranmer Terrace, Tooting, London SE17 0RE
3. Occupational Medicine and Hygiene Laboratories, Health and Safety Executive, 403 Edgeware Road, London NW2 6LN
4. Department of Chemical Pathology, St Helier Hospital, Wrythe Lane, Carshalton, Surrey SM5 1AA1