e-Cigarettes are less harmful than combustible tobacco products, but they may also spur youths and adolescents to go on to smoke conventional cigarettes, says a major report from the National Academies of Sciences, Engineering, and Medicine (NAS).
Although the NAS panel had trouble finding significant data to answer many questions about the short- and long-term health effects and potential benefits of e-cigarettes, the data were strong enough in some areas to make clear statements, said Committee Chair David L. Eaton, PhD, dean and vice provost, Graduate School, and professor of environmental and occupational health sciences, School of Public Health, University of Washington, Seattle.
e-Cigarettes “cannot really be simply characterized as beneficial or harmful,” he said. “The evidence that we reviewed certainly suggests that while they’re not without health risks, they are certainly likely to be far less harmful than tobacco products,” said Dr Eaton during a briefing.
The report, which was created to gather evidence to guide the US Food and Drug Administration’s (FDA’s) regulation of e-cigarettes, was released on January 23, just a day before an FDA advisory panel will announce their results of a review of an electronic smoking device that Philip Morris is seeking to market as being less harmful than cigarettes.
The FDA said in a statement that the NAS panel’s “research will play a critical role as the agency moves forward with its comprehensive plan for tobacco and nicotine regulation, which focuses on addressing the role that nicotine plays in keeping smokers addicted to combustible cigarettes by proposing to lower the level of nicotine in cigarettes to minimally or nonaddictive levels, and encouraging innovation to help smokers completely transition to potentially less harmful products, such as ENDS, or e-cigarettes.”
The NAS committee did not endorse e-cigarette use and was not charged with making recommendations for clinicians or smokers. But panelist Nancy A. Rigotti, MD, said the report does provide some guidance.
“As someone who takes care of adult cigarette smokers, I think it’s important to tell our patients that quitting smoking is the most important thing they can do for their health,” said Dr Rigotti, professor of medicine, Harvard Medical School, director, Tobacco Research and Treatment Center, and associate chief, Division of General Internal Medicine, Massachusetts General Hospital, Boston. “There are already effective FDA-approved smoking cessation devices that we would recommend first, but that the report does support perhaps considering using e-cigarettes,” she said. She noted that “if people do use e-cigarettes to quit, they should not use them dually.”
Youth at Greatest Risk
However, youths and adolescents are different.
“In terms of thinking about my own children, I’d advise them to avoid all tobacco products, including e-cigarettes, because nicotine is addictive and could have harmful effects on the adolescent developing brain,” said Adam Leventhal, PhD, associate professor, Division of Health Behavior Research, Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles.
e-Cigarettes have gained in popularity during the past decade among youths and adolescents. From 2016 to 2017, 1 in 3 high school seniors used some kind of electronic vaping device filled with marijuana, nicotine, or flavoring, according to a 2017 survey from the National Institute on Drug Abuse. About one third of those surveyed said they used the devices to vape nicotine. About one half said they only inhaled flavoring.
The NAS committee found “substantial evidence” that e-cigarette use increases the risk of ever using combustible tobacco cigarettes among youths and young adults. “That evidence base was large enough and consistent enough and strong enough to lead the committee to conclude that there was substantial evidence of an association between e-cigarette use and later ever-use of combustible tobacco cigarette smoking,” said Dr Leventhal.
FDA Commissioner Scott Gottlieb, MD called this finding “particularly troubling.”
There was “moderate” evidence that e-cigarette use increases the frequency and intensity of smoking. The committee found even less, “limited” evidence that e-cigarette use increases, in the near term, the duration of subsequent combustible tobacco cigarette smoking. The report did not address use of marijuana in vaping or other electronic devices.
Most of the flavorings used in e-cigarettes are generally regarded as safe by the FDA, said the committee, but it noted that the FDA’s imprimatur relates to food, “and most have not been studied for safety when inhaled with an e-cigarette.”
The panel documented other potential harms to children and adolescents, including moderate evidence for increased coughing and wheezing and an increase in asthma exacerbations.
The dearth of answers in many areas is “deeply troubling,” said Matthew L. Myers, president, Campaign for Tobacco-Free Kids, in a statement. “Numerous surveys show that e-cigarettes have become the most commonly used tobacco product among youth, surpassing traditional cigarettes,” he said.
Myers called for full and immediate FDA regulation of e-cigarettes “in order to obtain the information needed to provide the public and smokers with the answers to these vital questions, to prevent these products from undermining decades of progress in reducing youth smoking, and to assess and identify which, if any, specific e-cigarettes are effective at helping smokers quit all tobacco products or switch completely away from cigarettes.”
Observational studies have shown that frequent use of e-cigarettes is associated with an increase in the likelihood of smoking cessation, but “overall, there is limited evidence that e-cigarettes may be effective aids to promote smoking cessation,” according to the report.
The panel notes that e-cigarette users become dependent on the devices, “though with apparently less risk and severity than that of combustible tobacco cigarettes.”
Not surprisingly, e-cigarettes with nicotine were more effective for quitting smoking than those without nicotine, said Dr Rigotti. He note that the benefit has been seen with nicotine-replacement therapies.
But she said, “there was insufficient evidence to help us with the more important question for public health — to know whether or not e-cigarettes are as or more effective as cessation aids compared to no treatment or to FDA-approved smoking cessation treatments.”
Less Toxic, but Still Toxic
Most e-cigarette products “contain and emit numerous potentially toxic substances,” says the report.
But the effects of exposure to those substances is not as clear. Exposure is “significantly lower compared with combustible tobacco cigarettes,” said the panel, but it added that “the number, quantity, and characteristics of potentially toxic substances emitted from e-cigarettes is highly variable and depends on product characteristics (including device and e-liquid characteristics) and how the device is operated.”
e-Cigarette aerosol was found by the panel to contain metals, and limited evidence suggests that, with the exception of cadmium, such metals could be present in greater numbers than in combustible tobacco.
The evidence is substantial that some of the chemicals present in that aerosol (such as formaldehyde and acrolein) are capable of causing DNA damage and mutagenesis, supporting “the biological plausibility that long-term exposure to e-cigarette aerosols could increase risk of cancer and adverse reproductive outcomes,” says the report.
But many questions about carcinogenicity are unanswered, said the panel, noting, for instance, that “there is no available evidence whether or not e-cigarette use is associated with intermediate cancer endpoints in humans.”
Evidence is nonexistent as to whether e-cigarettes cause respiratory diseases in humans or affect pregnancy outcomes or the developing fetus.
Substituting e-cigarettes for smoking reduces exposure to toxicants and carcinogens and may reduce short-term harm to several organ systems, but there is little evidence on long-term health effects, and none at all as to whether morbidity or mortality differs for dual users in comparison with other users.
The committee attempted to model any potential public health benefit with increased use of e-cigarettes. The panel said that if use increases quit rates, it expected short-term public health benefits. But if it drives more youths to take up smoking, the benefit would be lower.
Under the worst assumptions, “the modeling projects a net public health loss,” said panelist David Mendez, PhD, associate professor, Department of Health Management and Policy, School of Public Health, University of Michigan, Ann Arbor.
“Ultimately, this report helps identify areas that need further study to better understand the net public health impact of e-cigarettes as we continue our work on policies to protect kids and significantly reduce tobacco-related disease and death,” said Dr Gottlieb.
“We need to put novel products like e-cigarettes through an appropriate series of regulatory gates to fully evaluate their risks and maximize their potential benefits,” he said.
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