The media reports the results of sloppy vaping research, then quickly forgets them. We do not. What follows is a list of many of the low-quality studies that have investigated the alleged health risks of e-cigarette use. We'll regularly update this catalog of bad studies as necessary.
The past year has seen the publication of many studies alleging that e-cigarette use (vaping) carries very serious health consequences, everything from depression to erectile dysfunction and higher stroke risk. Each paper generated widespread media coverage, usually one news outlet duplicating the uncritical coverage of the last, giving consumers the false impression that vaping poses a greater health threat than it actually does. When we examined these studies in more detail, we identified their serious flaws and reported them to our readers.
But health reporters tend to obsess over a topic for a few days then forget it entirely, quickly moving on to the next exaggerated study. So in the spirit of developing a more comprehensive understanding of the health risks and benefits of vaping, here's a greatest-hits compilation of the questionable research that has hit the headlines in recent months. 
"Vaping doubled the risk of erectile dysfunction in men 20 and older," CNN reported last December. What they left out was that all the data gathered for the study was self-reported. Men were classified as having ED based on a 1-item question: “Many men experience problems with sexual intercourse. How would you describe your ability to get and keep an erection adequate for satisfactory intercourse?” Suffice it to say, this was far short of a reliable medical diagnosis.
The researchers also relied on study participants to report how much they vaped or smoked. Strangely, the study did not find a link between daily smoking and ED. It's not clear why only vaping would carry this risk, since cigarettes often contain more nicotine than the liquids consumed by vapers.
Experiencing ED is probably unpleasant, but suffering a stroke is, I assume, a truly frightening experience. So when the American Heart Association (AHA) announced that researchers had linked vaping to stroke risk, the media went berserk, reporting that “E-cigarette users have a 15% higher risk of stroke at a younger age than traditional tobacco smokers, according to preliminary findings.”
As it turns out, "preliminary" was the wrong word to use. The study was never published, though the authors were scheduled to present their results at the AHA's annual conference. They never did, and it could be because the results were less impressive upon closer inspection. While vapers suffered strokes earlier in life, smokers actually had a substantially higher overall risk, 6.75% compared to 1.09% for e-cigarette users.
The same month, November 2021, MSN reported that "The evidence against vaping is mounting, and a new study now links e-cigarettes with an increased risk for broken bones." This was a misleading summary at best. The researchers actually found that current vapers had a lower prevalence of fractures than former vapers. If vaping causes bone damage, why would quitting e-cigarettes be linked to more bone damage?
This example comes courtesy of the Truth Initiative. “Two health crises among youth — a mental health crisis and a vaping epidemic — pose increasing threats to a generation of young people,” the tobacco industry-funded activist group wrote in a September 2021 report. “While it is well known that nicotine harms developing brains … lesser known are the worrying connections between nicotine and mental health.”
TI acknowledged that "it is unknown whether a causal relationship between nicotine and mental health conditions exists," but much more can be said than that. It's actually quite likely that a link between nicotine consumption and depression exists; however, it probably runs in the opposite direction. People diagnosed with the depression smoke to alleviate their symptoms, because nicotine has a well-documented antidepressant effect.
Because many studies have documented the smoking cessation benefits of vaping, tobacco control researchers have simply changed how they measure success in studies of e-cigarettes. Smokers who switch from smoking to vaping are counted as having "relapsed" if they have so much as "one or two puffs" of a cigarette. We've examined two recent studies with this design. The problem here is that many smokers quit gradually, initially replacing some of their cigarette consumption with vaping, many of them ultimately giving up smoking entirely.
This claim isn't based on bad research so much as it's based on no research at all. ACSH has always opposed minors using any nicotine-containing product whatsoever, but we have to be honest about what the data show. Two important conclusions leap out of the evidence we've gathered so far: a minority, roughly 20 percent, of high school students have reported vaping at some point. However, the majority of these individuals are former cigarettes smokers, according to the authors of a 2021 study. "This [result] is consistent with other recent research showing that declines in cigarette use have accelerated after the introduction of [electronic cigarettes]," they wrote.
A January 2022 study suggested that e-cigarette users may harm the respiratory health of those around them via "secondhand vaping." The conclusion may have been plausible were it not for this odd detail: most of the study participants who reported symptoms caused by secondhand vape exposure were "also likely to have personal use of tobacco or cannabis products or secondhand exposure to combustible products," the study authors explained.
The obvious question is, how do they know it was passive vaping that caused the symptoms when a majority of these individuals were exposed to tobacco and marijuana during the study?
Vaping has proved very popular among ex-smokers, myself included. As a result, it's smart for public health researchers to investigate the risks and benefits of e-cigarettes. Whatever danger vaping poses should be honestly reported to the public. That said, poorly designed epidemiological studies that make unreasonable assumptions or ask the wrong questions only muddle the discussion, leaving consumers misinformed about vaping. Hopefully we'll see less of this low-caliber research in the future. If not, this list will continue to grow.
 Did we miss any? Post your suggestions in the comments.