Health says the recent hospitalization of about two dozen people in the Midwest who had breathing problems after vaping shows "why e-cigarettes are so dangerous." Since we don't know what these patients were vaping or whether it was actually the cause of their symptoms, that conclusion is quite a leap.

So far 15 cases have been reported in Wisconsin, at least six in Illinois, and at least four in Minnesota. In addition to shortness of breath, the patients' symptoms have included coughing, fever, vomiting, diarrhea, headache, dizziness, and chest pain. "It's unclear exactly what the patients—many of whom are young adults—had been inhaling or what type of devices they were using," NBC News reports. "Nor do doctors know where they had purchased the devices or e-liquids." The New York Times notes that "officials are not yet clear whether vaping caused the injuries, and if so, what ingredient in the e-cigarette or vaping systems was responsible."

The assumption that vaping caused the breathing problems seems to be based on little more than supposition. "We are continuing to interview patients so we can identify a possible cause," Andrea Palm, secretary-designee of the Wisconsin Department of Health Services, said in a press release. "All patients reported vaping prior to their hospitalization, but we don't know all the products they used at this time. The products used could include a number of substances, including nicotine, THC, synthetic cannabinoids, or a combination of these."

Emily Chapman, the chief medical officer for Children's Minnesota, a pediatric health system based in Minneapolis, told NBC, "We know there are certain characteristics in common with these cases, but we have not been able to get to the bottom of exactly what aspect of the vaping habit or product or solvent or oil is causing the injury." David Gummin, the medical director of the Wisconsin Poison Center, likewise told the Times: "We don't yet know the causative agent. We have no leads pointing to a specific substance other than those that are associated with smoking or vaping."

The Times says "one hypothesis" is that "the teenagers had purchased a nicotine or cannabis-derived vaping product that had been used once, and then refilled with dangerous substances that would be hard to detect." The paper notes that "patients reported using open-tank systems and devices with interchangeable cartridges," meaning they were not necessarily using commercially produced e-liquids.

At least some of the patients were vaping not nicotine but a cannabis extract, or what they thought was a cannabis extract. "People will buy them from the states where it is legal and they'll bring them back to states such as Wisconsin where it's not legal," the brother of one patient told NBC. "You don't know if you're buying something from a middleman that picked it up from a dispensary or if you're buying it from somebody who has tampered with it and made their own mixture. You literally don't know what you're inhaling into your body."

In this context, linking these cases to Juul, the leading e-cigarette company, seems like a non sequitur. Yet that is what both NBC and the Times did, citing a 2018 study that found some flavoring agents used in e-cigarettes, when mixed with solvents, produce acetyl compounds that can irritate the lungs. It's not clear what that has to do with breathing problems people experience after vaping black-market cannabis extracts or synthetic cannabinoids.

"There are still many unanswered questions, but the health harms emerging from the current epidemic of youth vaping in Minnesota continue to increase," Ruth Lynfield, medical director at the Minnesota Department of Health, said in a press release. Since the "unanswered questions" include which products the patients used and what drugs they delivered, tying these cases to the "epidemic of youth vaping," a phrase associated with the use of commercially produced nicotine delivery devices such as Juul, makes little sense.

Lynfield added that "we are encouraging providers and parents to be on the look-out for vaping as a cause for unexplained breathing problems and lung injury and disease," which pretty much guarantees that we will hear about more cases supposedly caused by e-cigarettes. "Could it be that these particular patients were smoking something in common?" Christy Sadreameli, a pediatric pulmonologist at the Johns Hopkins Hospital in Baltimore, said in an interview with NBC News. "Definitely possible. It's also possible that as clusters become evident to physicians, we start to look out for things more."

In other words, once people hear that "vaping"—of what exactly, we're not sure—causes breathing problems, they are more likely to attribute breathing problems to vaping, reinforcing the impression that a causal relationship has been established, which in turn encourages more such reports, and so on. Even when symptoms actually are related to vaping, the specific agent and causal mechanism, which may differ from case to case, are lost in a sea of anecdotes. Without that information, blaming these cases on "vaping" in general, implying that all forms of it are equally dangerous, is about as helpful as blaming food poisoning on eating.