Objective To review peer-reviewed evidence on heat-not-burn tobacco products (HnB), their secondhand emissions and use by humans; to identify differences between independent and industry-funded studies.
Data sources Medline, Embase, PsycINFO, ProQuest, Scopus and Web of Science databases were searched up to 6 November 2017 for studies on HnB published after December 2009; reference lists were screened and other researchers contacted, yielding 637 records.
Study selection Thirty-one publications on HnB secondhand emissions (n=16) or use by humans (n=15) were selected by two reviewers with excellent agreement (k=0.75).
Data extraction Data on authors’ affiliations, HnB products, secondhand emissions and human exposure were extracted by one reviewer. Two reviewers assessed the quality of experimental HnB studies using the Effective Public Health Practice Project tool.
Data synthesis Twenty out of 31 studies were affiliated with tobacco industry. Studies on secondhand emissions varied by methodology, products and comparators. Compared with cigarettes, HnB delivered up to 83% of nicotine and reduced levels of harmful and potentially harmful toxicants by at least 62% and particulate matter by at least 75%. Experimental HnB use studies were limited to one product, reductions of human exposure to toxicants varied between 42% and 96%. HnB use suppressed urges to smoke, but participants rated HnB less satisfying than cigarettes. While limited by methodological heterogeneity, findings were largely similar for independent and industry-funded studies.
Conclusions Studies on HnB secondhand emissions and human use were heterogeneous and largely affiliated with the manufacturers. HnB exposed users and bystanders to toxicants, although at substantially lower levels than cigarettes.
- electronic nicotine delivery devices
- secondhand smoke
- harm reduction
- tobacco industry
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Contributors LSB conceived of the study idea, ES and LSB designed and implemented the searches and rated the quality of the included studies. ES extracted and synthesised the data and wrote the first and final version of the manuscript. All authors revised the manuscript and have approved its final version.
Funding This study was supported by a few sources. This review represents independent research funded by the NIHR-Wellcome Trust King’s Clinical Research Facility and the National Institute for Health Research (NIHR) Biomedical Research Centre at South London and Maudsley NHS Foundation Trust and King’s College London. Preliminary work was funded by Public Health England (ECM-4931), other funding sources include a Cancer Research UK (CRUK)/BUPA Foundation Cancer Prevention Fellowship (C52999/A19748) and the UK Centre for Tobacco and Alcohol Studies, a UK Clinical Research Collaboration Public Health Research: Centre of Excellence, funded by the Medical Research Council, British Heart Foundation, Cancer Research UK, Economic and Social Research Council and the NIHR under the auspices of the UK Clinical Research Collaboration (MR/K023195/1).
Disclaimer The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care.
Competing interests ES is a NIHR Maudsley Biomedical Research Centre PhD student in the Nicotine Research Group at the Institute of Psychiatry, Psychology & Neuroscience (IoPPN), King’s College London. He has no links with any tobacco or e-cigarette manufacturers. AMcN is a Professor of Tobacco Addiction and leads the Nicotine Research Group at the IoPPN, King’s College London. She is a Deputy Director of the UKCTAS. She receives funding for projects from a variety of funders such as CRUK and the National Institute for Health Research (NIHR) and has no links with any tobacco or e-cigarette manufacturers. LS is Senior Lecturer (Associate Professor) in Health Psychology at the Department of Behavioural Science and Health, University College London. He has received grants, personal fees and non-financial support (ie, research grants, consultancy, travel and hospitality) from Pfizer, Johnson & Johnson, the National Centre for Smoking Cessation and Training and Atlantis Health Care outside the submitted work. He has no links with any tobacco or e-cigarette manufacturers. LSB is a Senior Lecturer in the Nicotine Research Group at the IoPPN, King’s College London and a member of the UKCTAS. She is a CRUK/BUPA Foundation Cancer Prevention Fellow. She has no links with any tobacco or e-cigarette manufacturers.
Patient consent Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
Correction notice This article has been corrected since it was published Online First. Data in Table 5 has been updated as the authors identified a computational mistake.
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