Co-Authored by Amy L. Fairchild, Ronald Bayer, and Sharon H. Green

Over the past few years, the chances are high that you have seen fewer smokers and more vapers--that is, people using e-cigarettes. These devices have become ever more popular, but they also have ignited a bitter battle. Remarkably, this dispute has not pitted public health professionals against Big Tobacco flacks, as in decades past. Rather, the fight is playing out among scientists committed to drastically reducing if not eliminating the prevalence of smoking. Traditional cigarettes kill 480,000 Americans each year and will take one billion lives worldwide this century. Scientists around the world are actively debating: What can be done to stop them?

Given the anti-e-cigarette messaging of some influential anti-tobacco groups, many may be surprised to learn that it is increasingly difficult to make a scientific case against e-cigarettes. Last month, a second Cochrane Review--the gold standard when it comes to assessing the state of the evidence on hot topics from salt to fat to smoking--concluded that e-cigarettes may help smokers quit without serious health consequences. The review concluded that of all 24 studies included, not a single one reported serious health risks to vapers from up to two years of e-cigarette use. Like the first review in 2014, this update is guarded, but it also gives an approving nod to 15 currently ongoing randomized trials that are underway.



As the evidence moves in favor of e-cigarettes, this latest report is sure to add fuel to a raging firestorm. This debate highlights two key tensions. First, what do we do in the absence of scientific certainty about all possible harms? This question was at the heart of a furious exchange of letters between scientists over the course of 2014. This feud over e-cigarettes can't be understood absent the values that animate it.

Framing the position of those who favor e-cigarettes is Michael Russell, a pioneer of smoking cessation methods who famously wrote, "People smoke for nicotine but they die from the tar." By extension, many scientists argue that e-cigarettes can satisfy nicotine addictions without causing harmful exposures to tar and combustion. They believe e-cigarettes could drastically reduce if not eliminate cigarettes.

This "harm reduction" perspective acknowledges that many smokers cannot or will not quit. Even if e-cigarettes carry some risks, those risks are far less serious than those of smoking. Thus, weighing the risks of e-cigarettes requires a comparison to the well-documented harms of smoking.

On the other side of the debate are those who preach precaution. Until the uncertainty about e-cigarettes is resolved, these devices have no place in a public health anti-tobacco arsenal. And there is uncertainty regarding the harms smokeless products may pose, particularly in the face of unknowns about how the FDA's new regulatory regime may impact quality control. But even if e-cigarettes may be a better option for any individual smoker who wants to quit but cannot, how might they change the pattern of disease in the long run? The fundamental question, in other words, isn't how e-cigarettes might help or harm individuals, but whether they will change population-level smoking patterns.



This tension between harm reduction and precaution, then, highlights a second vital question: Whose risk matters?



In 2015, Public Health England, the United Kingdom's equivalent to the CDC, roiled the waters when it endorsed e-cigarettes for harm reduction. Remarkably, while they drew fire from the Lancet and the British Medical Journal, they received the backing of ASH, a major anti-tobacco NGO with an unimpeachable record of opposition to cigarettes. In 2016, they were also joined by the Royal College of Physicians, which advocated for a harm reduction approach that included not only e-cigarettes but also other forms of smokeless tobacco.



The positions of British organizations that embraced e-cigarettes reflected a long history of support for harm reduction. Also, the UK organizations have focused on populations in immediate, certain danger: smokers themselves.



In the US, in sharp contrast, federal agencies have remained staunchly opposed, not only because of precaution, but also because of a focus on a different population: vulnerable youth and non-smokers. Former FDA commissioner David Kessler and Campaign for Tobacco-Free Kids president Matthew Myers wrote in an op-ed in the New York Times, "we cannot afford to waste more time while the tobacco industry addicts another generation of kids." For advocates of precaution, protecting populations that haven't yet been seduced by tobacco has remained paramount. For the non-smoker, an e-cigarette does nothing but increase risk.

Data alone cannot tell us what to do. Interpreting the emerging evidence on e-cigarettes relies on values and priorities: harm reduction or precaution, immediate peril or potential risks. While there can be no question that the public health community must look for emerging scientific data regarding risks and benefits, we must acknowledge the values that animate the controversy. Only then will we be able to reduce the enormous health burden of tobacco.