G Dabrera1, B Sampson2, R Ruggles3, G Leonardi4. 1. From the Field Epidemiology Training Programme, Centre for Infectious Disease Surveillance and Control, Public Health England, 61 Colindale Avenue, London NW9 5EQ, UK, European Programme for Intervention Epidemiology Training (EPIET), European Centre for Disease Prevention and Control, Stockholm, Sweden, gavindabrera@nhs.net. 2. SAS Trace Element Laboratory, Clinical Biochemistry, Charing Cross Hospital, Imperial College Healthcare NHS Trust, London W6 8RF, UK and. 3. Centre for Infectious Disease Surveillance and Control, Public Health England, 61 Colindale Avenue, London NW9 5EQ, UK. 4. Centre for Radiation, Chemicals and Environmental Hazards, Public Health England, Chilton, Didcot, Oxon, OX11 0RQ, UK.