CONSTABLE RESEARCH B.V.

E-cigarette aerosol contains fewer numbers and lower levels of most toxicants than does smoke from combustible tobacco cigarettes. Exposure to nicotine and to toxicants from the aerosolization of e-cigarette ingredients is dependent on user and device characteristics. Laboratory tests of e-cigarette ingredients, in vitro toxicological tests, and short-term human studies suggest that e-cigarettes are likely to be far less harmful than combustible tobacco cigarettes. However, the absolute risks of the products cannot be unambiguously determined at this time. Long-term health effects, of particular concern for youth who become dependent on such products, are not yet clear.

Although e-cigarette use might cause youth to transition to combustible tobacco products, it might also increase adult cessation of combustible tobacco cigarettes. The net public health effect, harm or benefit, of e-cigarettes depends on three factors: their effect on youth initiation of combustible tobacco products, their effect on adult cessation of combustible tobacco products, and their intrinsic toxicity. If e-cigarette use by adult smokers leads to long-term abstinence from combustible tobacco cigarettes, the benefit to public health could be considerable. Without that health benefit for adult smokers, e-cigarette use could cause considerable harm to public health in the short and long term due both to the inherent harms of exposure to e-cigarette toxicants and to the harms related to subsequent combustible tobacco use by those who begin using e-cigarettes in their youth. Find out the most unharmful products at vaprzon.

Population modeling is a useful strategy to help estimate the balance of potential benefits and harms from e-cigarettes in the short term before more definite scientific data are available. Factors that would promote the potential health benefits associated with these products include determining with more precision

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Suggested Citation:”Summary.” National Academies of Sciences, Engineering, and Medicine. 2018. Public Health Consequences of E-Cigarettes. Washington, DC: The National Academies Press. doi: 10.17226/24952.×

under which conditions e-cigarettes could serve as an effective smoking cessation aid, discouraging their use among youth through tobacco control strategies such as education and restrictions on products particularly appealing to youth, and increasing their safety through data-driven product engineering and design.

Millions of Americans use electronic cigarettes (e-cigarettes), even as rates of smoking1 combustible tobacco cigarettes continue to decline among youth and adults. In 2016, youth e-cigarette use was substantially higher than cigarette smoking or use of any other tobacco product. A common picture emerges from national surveys. Prevalence of use increases with age in children and youth. E-cigarette use also varies by gender, with typically greater use among boys than girls. E-cigarette use also varies by race and ethnicity, with higher rates of use among youth who identify as Hispanic and non-Hispanic white compared with black, Asian, and other races. Early results suggest that use stabilized or decreased in youth between 2015 and 2016, despite increases between 2011 and 2015 across a range of measures and surveys. Substantial proportions of youth report using non-nicotine electronic cigarettes. Rates of e-cigarette use among adults are relatively low when compared with youth e-cigarette use and to adult combustible tobacco cigarette smoking. Most adult e-cigarette users report currently using other tobacco products. Among adults, as among youth, patterns of use vary by demographic subgroups—age, gender, and race and ethnicity. E-cigarette use is generally greatest among young adults and decreases with age in adults. Few adults begin using e-cigarettes who are not already using combustible tobacco cigarettes.

Despite their popularity, little is known about their health effects, and perceptions of potential risks and benefits of e-cigarette use vary widely among the public, users of e-cigarettes, health care providers, and the public health community. For example, whether e-cigarette use confers lower risk of addiction compared with combustible tobacco cigarettes is one point of controversy. Electronic cigarettes contain constituents that are not inert and are likely to have some negative health effects on their own. However, because the known risks of combustible tobacco are so great, understanding the net public health effect of e-cigarettes requires understanding not only the inherent risks of e-cigarettes, but also the relationship between e-cigarette use and combustible tobacco cigarette use.

Furthermore, concerns have been raised that e-cigarettes will induce youth to begin using combustible tobacco cigarettes. E-cigarette use among youth and young adults is especially worrying if e-cigarettes cause

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1 The committee uses the verb “smoke” to refer to use of combustible tobacco cigarettes and “vape” to refer to use of e-cigarettes. Similarly “smoker” refers to someone who uses combustible tobacco cigarettes.

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Suggested Citation:”Summary.” National Academies of Sciences, Engineering, and Medicine. 2018. Public Health Consequences of E-Cigarettes. Washington, DC: The National Academies Press. doi: 10.17226/24952.×

dependence or the normalization of smoking behavior, and subsequently lead youth and young adults to start smoking combustible tobacco cigarettes. This is of particular concern for youth who otherwise would never have smoked. Among adult populations, to the extent that e-cigarette use promotes either reduction or complete abstinence from combustible tobacco smoking, e-cigarettes may help to reduce health risks.

E-cigarettes are regulated as tobacco products2 by the Center for Tobacco Products of the Food and Drug Administration (FDA), which requested that the National Academies of Sciences, Engineering, and Medicine convene a committee of experts to conduct a review of the emerging evidence about e-cigarettes and health, make recommendations for the improvement of this research, and highlight gaps that are a priority for future research. The Statement of Task can be found in Box S-1.

The committee undertook a comprehensive review of the scientific literature regarding key constituents in e-cigarettes, human health effects, initiation and cessation of combustible tobacco cigarette use, and harm reduction. The committee considered the quality of individual studies, as well as the totality of the evidence to provide structured and consistent conclusions on the strength of the evidence. See Box S-2 for a summary of the framework the committee used for those conclusions. The committee notes that the framework is a guide, but that a great deal of expert judgment—in the evaluation of individual studies and in bodies of evidence—is always involved. The Annex to this Summary includes a compilation of the conclusions grouped by level of evidence, whereas they are listed by type of outcome in the sections that follow.

CONSTITUENTS
E-cigarettes contain liquids (referred to as e-liquids) that are aerosolized upon operation of the device. E-liquids typically contain nicotine (although some users prefer zero-nicotine solutions), flavorings, and humectants. Nicotine is a well-understood compound with known central and peripheral nervous system effects. It causes dependence and addiction, and exposure to nicotine from e-cigarettes likely elevates the cardiovascular disease risk in people with pre-existing cardiovascular disease(s), but the cardiovascular risk in people without cardiovascular disease(s) is uncertain. Based on studies of long-term users of nicotine replacement
National Academies of Sciences, Engineering, and Medicine. 2018. Public Health Consequences of E-Cigarettes. Washington, DC: The National Academies Press. https://doi.org/10.17226/24952.