Based on the findings of this report, e-cigarettes cannot be simply categorized as either beneficial or harmful to health. The net public health outcome depends on the balance between adverse outcomes (increased youth initiation of combustible tobacco cigarettes, low or even decreased cessation rates in adults, and a high-risk profile) and positive outcomes (very low youth initiation, high cessation rates in adults, and a low-risk profile). In some circumstances, adverse effects of e-cigarettes clearly warrant concern, such as the use of e-cigarettes among non-smoking adolescents and young adults, devices that are prone to explosion, and the presence of constituents in e-cigarette liquids that are of major health concern (e.g., diacetyl and some other flavorings). In other circumstances, namely regular combustible tobacco cigarette smokers who use e-cigarettes to successfully quit smoking, e-cigarettes may represent an opportunity to reduce smoking-related illness. For these reasons, e-cigarette regulation that merely considers whether to be restrictive or permissive to the marketing, manufacture, and sales of all e-cigarettes for all populations is unlikely to maximize benefits and minimize the risks.
A number of federal regulatory tools exist to maximize the benefits and minimize the harms of e-cigarettes. One of those is the adoption of product standards, which require that product characteristics related to e-cigarette devices (e.g., electrical power, heating element, customizability), e-liquid constituents (e.g., nicotine concentration, flavoring additives, solvents such as propylene glycol and glycerol), and packaging meet certain criteria to ensure maximal benefit to the population as a whole. The
Food and Drug Administration (FDA) has recently announced its intention to “explore clear and meaningful measures to make tobacco products less toxic, appealing and addictive. For example, the FDA intends to develop product standards to protect against known public health risks such as electronic nicotine delivery systems (ENDS) battery issues and concerns about children’s exposure to liquid nicotine” (CTP, 2017). More research that is optimally designed to compare and isolate the health effects of certain product characteristics from one another is needed. Overall, studies typically show that product characteristic variation and patterns of use can meaningfully alter the effects of e-cigarette use on important outcomes.
To provide data to inform regulatory strategies that maximize benefits and minimize the risks of e-cigarettes, research is needed to identify product characteristics with an unfavorable health profile across key outcomes. Evidence is needed that isolates the effects of certain product characteristics on (1) toxicity and long-term health risks; (2) appeal and uptake of e-cigarettes among youth and young adult non-smokers as well as the risk of transition to smoking; (3) appeal, uptake, and efficacy as a smoking cessation aid among regular combustible tobacco cigarette smokers; and (4) appeal, uptake, and effects on maintaining abstinence or precipitating relapse among former combustible tobacco cigarette smokers. Some product characteristics may pose much greater health risks with little potential benefit and be viable candidates for restrictive product standards. For example, if evidence were to identify certain flavor additives that increased toxicity and appeal to youth, but did not enhance appeal or efficacy as a smoking cessation aid, the development of product standards to prohibit the use of such additives would likely have net improvement on the health of the population. As demonstrated in Chapter 19, the effects of e-cigarette use on smoking cessation may carry considerable influence on the overall population health burden over the next 30 years. Consequently, data examining the influence of product-characteristic variation on combustible tobacco cigarette cessation are of particular value.
Other nascent issues that intersect with e-cigarettes are likely to have a major impact on population health and warrant attention, but have yet to receive significant scientific study. E-cigarettes can be placed within a broader class of “non-combustible” tobacco products that, like e-cigarettes, generate inhalable aerosols and may lack certain toxicants found in tobacco smoke (HHS, 2014; TAG, 2008). For example, heat-not-burn tobacco products (e.g., devices that aerosolize tobacco leaf mixtures without combustion) share many similarities to e-cigarettes, including the use of propylene glycol and an electric heating element. Phillip Morris’s heat-not-burn product iQOS, which electronically aerosolizes tobacco leaves soaked in the same solvents present in e-liquid, has sold more
than 3 million units and is currently available in more than 20 markets, but not in the United States (Reuters, 2017). In May 2017, Phillip Morris submitted modified-risk tobacco product (MRTP) applications to FDA for iQOS products and, if approved, would permit marketing with claims of reduced health risk.1 It is important for regulatory science to translate the same methodologies and research questions directed toward e-cigarettes addressed in this report to heat-not-burn products. Furthermore, patterns of poly-tobacco product use and transitions in use among e-cigarettes, heat-not-burn tobacco products, and combustible tobacco products will also necessitate study.
The use of e-cigarettes and other e-cigarette devices to aerosolize cannabis plants, oils, and waxes is another emergent issue. Estimates of ever using an e-cigarette device to use cannabis products in youth and young adult samples across North America range from 8 percent to 29 percent (Johnston et al., 2017; Leventhal, 2016; Morean et al., 2015). With increasing legalization of cannabis in the United States, the e-cigarette and cannabis commercial industries and customer bases are likely to become increasingly enmeshed. The retail market is flooded with devices and e-liquids devised for aerosolizing liquid cannabis preparations, including products that include both nicotine and cannabis (i.e., e-liquid infused with both tetrahydrocannabinol and nicotine). Knowledge and methodologies about e-cigarette products addressed in this report can be adapted to address the health impact of cannabis use in e-cigarette devices. Furthermore, use of aerosolized cannabis and cannabis products may become an increasingly common precursor to or outcome of e-cigarette use.
The above-mentioned issues reflect the nuanced and balanced consideration that should be taken with regard to scientific priorities for and policy implications from evidence on the health effects of e-cigarettes. Given how rapidly the e-cigarette product marketplace and user population are changing, there will undoubtedly be many new issues that are currently unknown and will require careful surveillance and scientific scrutiny. The approaches taken by the committee to evaluate the health effects of e-cigarettes in this report are anticipated to provide a generalizable template for future evaluations of the evidence.
CTP (Center for Tobacco Products). 2017. FDA announces comprehensive regulatory plan to shift trajectory of tobacco-related disease, death. https://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm568923.htm (accessed September 18, 2017).
1 Swedish Match submitted an MRTP application for a non-combustible tobacco product, Snus, on August 27, 2014.
HHS (U.S. Department of Health and Human Services). 2014. The health consequences of smoking—50 years of progress: A report of the Surgeon General. Atlanta, GA: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Disease Prevention and Health Promotion, Office on Smoking and Health.
Johnston, L. D., P. M. O’Malley, R. Miech, J. G. Bachman, and J. E. Schulenberg. 2017. Monitoring the Future national survey results on drug use, 1975–2016: Overview, key findings on adolescent drug use. Ann Arbor: Institute for Social Research, University of Michigan.
Leventhal, A. 2016. Adolescent use of alternative cannabis products: Epidemiology, correlates, and consequences. Paper presented at the College on Problems of Drug Dependence Annual Meeting, Palm Springs, CA.
Morean, M. E., G. Kong, D. R. Camenga, D. A. Cavallo, and S. Krishnan-Sarin. 2015. High school students’ use of electronic cigarettes to vaporize cannabis. Pediatrics 136(4): 611–616.
Reuters. 2017. Philip Morris says it has doubled supply of iQOS tobacco device in Japan. https://www.reuters.com/article/us-japan-ecigarettes/philip-morris-says-it-has-doubled-supply-of-iqos-tobacco-device-in-japan-idUSKBN1690DX (accessed October 11, 2017).
TAG (Tobacco Advisory Group of the Royal College of Physicians). 2008. Ending tobacco smoking in Britain: Radical strategies for prevention and harm reduction in nicotine addition. https://cdn.shopify.com/s/files/1/0924/4392/files/ending-tobacco-smoking.pdf?2801907981964551469 (accessed October 11, 2017).