 In February 2022, the World Journal of Oncology published an article by a team of 13 researchers, claiming that vapors are about as likely to get cancer as people who smoke traditional cigarettes. Citing this article, Stanton Glantz, a tobacco control activist and retired professor of medicine at the University of California, San Francisco, claimed that not only are there some carcinogens in e-cigarette aerosol, but now there is also direct evidence that people who use e-cigarettes are at increased risk of some cancers. And then the World Journal of Oncology's editors retracted the study because concerns have been raised regarding the article's methodology, source data processing, including statistical analysis, and reliability of conclusions. The editors of the journal and their paper's peer reviewers failed to notice the study's many flaws prior to publication, but they ultimately concluded that it was bad enough to retract. Even so, it's worth dwelling on the problems because they're typical of what we see with statistical studies on this topic and other public policy issues. The retracted study claimed a large sample size with data on 154,856 subjects. For assessing the cancer risk of vaping versus traditional smoking, but we should be looking at our vapors who never smoke traditional cigarettes and yet have cancer. There were 180 vapors with cancer in the study, but based on general population percentages, probably fewer than a hundred of them had never smoked traditional cigarettes. That's too small a sample to draw robust conclusions. The median age of vapors in the study was 25 versus 62 for the traditional smokers, and they had very different breakdowns of income, race, sex, and medical conditions. Adjusting for all these factors would require a minimum of a thousand observations. If researchers can query the same data sets and arrive at completely bizarre results that are as strong or even stronger than the ones they're reporting, they're doing something wrong. In this case, the authors claimed active vapors had 2.2 times the risk of cancer as a control group, but their logistic regression showed that people who never used cocaine, heroin, or methamphetamines also had a 2.2 times higher risk of getting cancer. Why didn't the authors run with this finding that cocaine might be a cancer preventative? Because it's absurd and would likely have brought ridicule. According to the researcher's data, being white raises your cancer risk by 2.6 times. Having a middle income of between 25,000 to 65,000 raises your risk 2.3 times. The authors didn't report these spectacular findings either. This paper is among the worst of the anti-vaping articles that managed to get published in respectable peer-reviewed journals and cited by regulators and legislators. But even the best studies haven't surmounted a key statistical issue, and they tended to distort the evidence to make vaping look dangerous. An analysis in internal and emergency medicine noted 11 flawed studies that linked vaping to various diseases. Some of these studies relied on surveys that don't report when respondents began vaping, but the population assessment of tobacco and health study reports age ranges for initiation of smoking and vaping as well as diagnoses. Based on that survey, the authors of the internal and emergency medicine article found that subjects diagnosed with cancer typically started vaping after they were diagnosed with their conditions. In fact, just 4% of e-cigarette users were definitely diagnosed after they started vaping. By contrast, about 98% of smokers were diagnosed after they started smoking. Overall, 99% of cases involved people with a history of smoking and just 2.3% of vapors diagnosed with one of the four health conditions covered by this study had never been cigarette smokers. The tiny population of vapors who never smoked traditional cigarettes and who started using e-cigarettes before being diagnosed with a health condition is hard to identify, unrepresentative of the general population, and likely to small to draw conclusions from. No amount of tricky statistical work can overcome this basic data issue. There's another problem with the way the results of these studies are reported. Even if it does turn out that vaping has negative health consequences, it may still be a net positive for users who otherwise would go back to traditional cigarettes. And banning e-cigarettes altogether would cause some people to turn to the black market to get their vaping fixed. Then they would have no idea what they're sucking into their lungs because there would be no quality control. In 2019, underground manufacturers of marijuana vapes mixed vitamin E acetate into their products, which likely explains why 2,807 people ended up hospitalized and 68 died. Proving that traditional cigarettes caused cancer, which they do, required two types of data, observational studies and experimental studies. First people noticed that cancer patients were more likely to be smokers than non-cancer patients, and then careful experimentation teased out some of the mechanisms by which smoking led to cancer. Observational studies even without data issues can show only in association, not causation. Although most vaping studies claim only in association, journalists, activists, and public officials are quick to assert causation. Experimental studies can show causation but can't measure the practical extent of an issue or possible offsetting factors. One experimental study of vaping that drew press attention was published in the Journal of Nuclear Medicine under the title Molecular Imaging of Pulmonary Inflammation in Electronic and Combustible Cigarette Users, a pilot study. A new study shows e-cigarettes caused more inflammation in the lungs than traditional cigarettes. The researchers at the University of Pennsylvania say vape devices cause unique damage to the lungs. That is not yet fully understood. One problem with this particular paper is that it studied only 15 people, five vapors, five users of traditional cigarettes, and five people who didn't smoke at all. However, carefully you select groups of five subjects that can't represent a broad enough cross-section of users to draw any solid conclusions. That would require hundreds of participants. This experiment also relied on screening volunteers and made no attempt at randomness or sampling the range of population, meaning that each of the three groups of five subjects differed from each other in important ways. The paper did not show that vaping causes increased lung damage. In fact, the research didn't check for that. Instead, it looked for biomarkers or chemicals thought to be associated with lung damage. By that measure, they found no difference between the five vapors and the control group of five people who had never vaped or smoked. The study did find that uptake of a chemical thought to react to a biomarker for lung damage was higher in the five vapors than in the control group. But the five cigarette smokers included in the study had a lower uptake of that chemical than the controls, which makes the conclusion suspect since we know traditional cigarettes cause lung damage. Most likely, the correlation can be attributed to random chance. And this was a pilot study, meaning it was aimed not at generating firm conclusions, but at testing procedures and determining which hypothesis could be tested in a subsequent study. The authors mentioned more than 30 statistical tests at the five percent level of significance, and they may have conducted more. A five percent significance level means there's a five percent chance of getting a positive result by random chance, even if there is no association at all in your data. With 30 tests, you expect 1.5 positive results, even if vaping is unrelated to lung health. The authors got two positive results out of 30, which is hardly strong evidence of anything. And the two results are among the least direct in terms of linking vaping to lung damage. The more direct tests of biomarkers fail to find any differences among the groups. A classic prohibitionist argument is that while a controversial activity may not be harmful in itself, it leads to bad things. In the case of vaping, several studies suggest that young vapors are something like seven times as likely to smoke traditional cigarettes in the future, than similar young people who don't vape. The data is pretty clear so far in the limited studies we have that it looks like it is a gateway for youth smoking. An off-sided paper in this area, e-cigarettes and future cigarette use, is typical of the genre. Out of 298 Southern California 17-year-old high school students who didn't vape, only 11 percent were smoking cigarettes a year later. Among those who were vaping at 17, 40 percent had taken up old fashioned cigarettes at 18. The paper did a lot of additional analysis, but this is the basic statistic driving the conclusion. To the author's credit, they were careful to label this an association between vaping and future smoking, rather than claiming that vaping caused future smoking. Yet when this paper was cited by regulatory authorities, they interpreted it as causal evidence and therefore as a justification to restrict vaping. There are reasons to be skeptical about this kind of research. Not everyone is honest when they fill out a survey, especially young people asked about activities that are frowned upon, and only 14 percent of the students interviewed at age 17 participated in the follow-up survey a year later. The missing students might be systematically different from the ones recorded in the study. It's also plausible that teenagers who vape differ from teenagers who don't, in ways that independently affect their likelihood of smoking. Perhaps the type of kid who vapes at 17 is more likely to smoke at 18. In that case, restricting vaping among 17-year-olds probably won't reduce smoking at age 18. In fact, some 17-year-old vapors will switch to traditional cigarettes or turn to underground purveyors of e-cigarettes, which would pose a much more serious health risk. There is plenty of evidence that many smokers use vaping to reduce or quit smoking. In fact, adolescent smoking has continued to fall as adolescent vaping has increased. Another anti-vaping argument is that it has negative mental or social health consequences. Studies like electronic cigarette use and mental health, the Canadian population-based study, suffer from the same issues as studies linking vaping to future smoking. It's easy to show that vapors have more psychological and social issues than non-vapors, but that's only an association. An obvious alternative explanation is that troubled kids are more likely to vape, either as a form of self-medication, or because they have less regard for adult opinion and rules, or perhaps because they are less supervised or have less to lose by acting in a deviant way. Even if we did have good observational studies suggesting that vaping is reliably associated with future smoking, or that vaping is associated with mental and health problems, we would still need experimental studies to support causal claims. Most real experiments are unethical since participants would have to be randomly assigned to either vape or avoid vaping, which is why researchers look for natural experiments. A good example of a natural experiment is intended and unintended effects of e-cigarette taxes on used tobacco use. The authors used data on youth smoking and vaping rates in 10 states and two large counties that enacted e-cigarette taxes between 2010 and 2019. They found that taxes were associated with a reduction in vaping among young people, but they were also associated with an increase in young people smoking traditional cigarettes. That's good evidence that vaping and smoking are substitutes. If vaping led to smoking, a decrease in vaping would lead to a decrease in smoking. Several other natural experiment studies reinforce the idea that vaping and smoking are substitutes, although the rate of substitution seems to vary in different populations. But we still have a lot to learn in this area. The evidence to date suggests that discouraging vaping will lead to increased smoking and very likely worse public health. This research suggests that the 15-20% e-cigarette tax, which was part of the original Build Back Better Act, though it was eventually taken out, probably would have reduced youth vaping by about 3% and increased youth smoking by about 2%. Given the evidence that vaping is far less hazardous than smoking, more teen smoking instead of vaping doesn't represent an improvement in public health. None of this research shows that vaping is safe, and it doesn't rule out the possibility of negative health effects that haven't been found yet. But in public policy, the most important question is instead of what? In real life, there are no solutions only trade-offs. There's overwhelming evidence that if the alternative of vaping is cigarette smoking, vaping represents a huge improvement for public health. Government officials generally fail to reason in these terms. They tax, ban, and regulate as if their policies exist in a vacuum, setting statistically dubious studies to support their preconceived policies.