Evaluating evidence of e-cig risks and benefits

The recent rise of e-cigarettes in the public sphere has fueled debate about public health efforts aimed at smoking cessation. Major evidence-based reviews from the United States and England have concluded that, for smokers, e-cigarettes are substantially safer than combustible cigarettes; however, they disagree about the implications for public health policy.

In an essay published in the American Journal of Public Health, Amy Fairchild, PhD, professor in the Health Policy and Management Department at the Texas A&M School of Public Health, Columbia University researcher Ronald Bayer, PhD, and School of Public Health doctoral candidate Ju Sung Lee explored how recent public health studies in the United States and England reached conclusions on e-cigarette use.

In the winter of 2018, the U.S. National Academy of Sciences, Engineering and Medicine (NASEM) and Public Health England (PHE) both released evaluations of the current body of evidence on e-cigarette use. Although some have considered these reports as more or less consistent—e-cigarettes can help in harm reduction—their conclusions on what the evidence indicates and what should count as evidence stand in stark contrast.

The main difference between the reports, Fairchild and colleagues state, turns on a key question: whose risk is of central concern, current smokers or nonsmokers and children? The PHE report focused more on reducing risks to smokers whereas the NASEM was concerned more with protecting the “innocent” children and bystanders.

Research has found that e-cigarettes are less harmful than conventional tobacco and that they could be useful for harm reduction or for helping smokers quit entirely; however, there are concerns that e-cigarettes may lead young nonsmokers, particularly teens, to begin consuming nicotine and step on a pathway that will lead to smoking.

The two reports were closest to agreement when it came to comparing e-cigarettes and conventional tobacco. The PHE and the NASEM reports both noted that e-cigarettes reduce exposure to harmful substances; however, they differed in the standard of evidence needed to fully endorse e-cigarettes for harm reduction. The PHE report noted risks to e-cigarette use and lingering uncertainties in the research, but still recommended that smokers switch. In contrast, the FDA report focused more on the uncertainties and risk, stopping far short of promoting efforts that would push e-cigarettes as a smoking substitute.

There were also differences in how the reports dealt with risks e-cigarettes pose to nonsmokers. The NASEM report, commissioned by the U.S. Food and Drug Administration (FDA), noted that e-cigarettes expose bystanders to nicotine and other potentially harmful substances, though at lower levels than smoking. Thus, efforts to limit bystander exposure to vapor from e-cigarettes was a key recommendation. In contrast, the PHE report found no evidence of health risks from secondhand vapor and that risks from secondhand e-cigarette nicotine exposure were minor.

The level of risk posed to children was another difference Fairchild, Bayer and Lee found between the two reports. The FDA report noted robust evidence that e-cigarette use increases the likelihood of using conventional tobacco in children and young adults. Thus, extra care must be taken to keep children away from e-cigarettes.

However, the PHE report found that the evidence did not warrant the fear that e-cigarettes could serve as a gateway to conventional tobacco for young people, with research showing that e-cigarettes were attracting relatively few children and young adults who had not previously smoked. Additionally, the report noted studies pointing to adult smoking, which could be reduced through e-cigarettes, as being a main influence on smoking among young adults.

The differences in what counts as evidence regarding e-cigarettes hinge on the main focuses of the two public health agencies, with NASEM and the FDA focused on protecting nonsmokers and preventing young people from accessing e-cigarettes and PHE most centrally concerned with reducing harm to current smokers. For NASEM, then, clinical trials represented the gold standard. PHE, in contrast, counted population-based ecological data as equally important.

Despite the differences in standards of evidence, it is no longer possible to argue that e-cigarettes are as or more harmful than combustible products when it comes to smokers. Indeed, a recent clinical trial published January 2019 in the New England Journal of Medicinehas provided additional evidence that e-cigarettes are effective for smoking cessation. Public health efforts, Fairchild and colleagues conclude, must now address deepening public misunderstanding of the relative risk of e-cigarettes risk with candor.