Competing interests CB's salary is paid by The University of Auckland and his research is supported by grants from the New Zealand Health Research Council (HRC), the University of Auckland and the NZ Heart Foundation. He has previously undertaken tobacco control research supported by the New Zealand Ministry of Health, and by Niconovum, Sweden, prior to the purchase of this company by RJ Reynolds. He is currently an investigator on a study involving reduced nicotine cigarettes in which the products were purchased by the University of Auckland from Vector Group Ltd, US. He has previously undertaken research on ENDS funded by HealthNZ, in which the study products were supplied by Ruyan, Hong Kong; and he is the principal investigator on an HRC-funded efficacy trial of ENDS that will use products provided by a NZ-based ENDS retailer. Other than these relationships, he has no conflicts of interest to declare. TE's salary is paid by Virginia Commonwealth University and his research is supported by grants from the US National Institutes of Health (R01CA103827 and R01CA120142). In the past he has served as a paid consultant to the National Association of Attorneys General regarding litigation against a tobacco company. He has served as an expert consultant for the World Health Organization regarding ENDS. Also, he has been retained by the US FDA as a consultant but, as of this writing, has not served in this capacity in any way and has received no payment from the FDA. Other than these relationships, he has no conflicts of interest to declare. J-FE's salary is paid by the University of Geneva. He has served as an unpaid expert consultant for the World Health Organization regarding ENDS, and as a paid consultant for Pfizer, a manufacturer of smoking cessation medications, in 2006–2007 (on the Swiss varenicline advisory board). The University of Geneva received trial medications from Pfizer in 2006 for a study conducted by J-FE. No competing interest since then. AF has no competing interests to declare. ML has researched various nicotine products including ENDS for several firms and universities, and advised several distributors, but has no financial interest in any of these.