Heather Wardle1, Louisa Degenhardt2, Audrey Ceschia3, Shekhar Saxena4. 1. School of Social and Political Sciences, University of Glasgow, Glasgow, UK; London School of Hygiene & Tropical Medicine, London, UK. Electronic address: heather.wardle@glasgow.ac.uk. 2. National Drug and Alcohol Research Centre, Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia. 3. The Lancet Public Health, London, UK. 4. Harvard University, Cambridge, MA, USA.