E-cigarettes are safer than cigarettes but that doesn’t mean they’re harmless.
When e-cigarettes first appeared on store shelves a few years back, they were marketed as a sleek, discreet technology that could help adult smokers kick a potentially deadly habit.
Flash forward to 2018, the year the Juul vape device took over three-quarters of the US e-cigarette market. Instead of catering to adult smokers, the e-cigarette industry appeared to be overwhelmingly targeting nonsmoking youth.
Maciej Goniewicz, one of the leading e-cigarette researchers based at Roswell Park Comprehensive Cancer Center in Buffalo, has watched the shift unfold up close: The volunteers who come forward for his e-cigarette studies seem to be getting younger.
“[These are] people who were breathing pure air for a long time — and have never smoked tobacco cigarettes — who now have started using e-cigarettes,” Goniewicz said.
Now he and other researchers around the world are scrambling to figure out what impact this new habit might have on developing bodies and brains in the long term.
While no one questions the fact that e-cigarettes are far safer than tobacco, one of the deadliest consumer products known to man, evidence keeps emerging to suggest that e-cigarettes could be somewhat dangerous, especially for hearts and lungs. There’s also a growing body of research suggesting that vaping can lead to smoking or that people wind up maintaining both habits.
Before we dive into the emerging health concerns, a couple of words of caution. Since people haven’t been vaping for very long, the science is still preliminary — and far from conclusive. It may take decades for any diseases possibly caused by e-cigarettes to fully surface, particularly in the young, healthy people now using them.
There’s also the problem of making generalizations about e-cigs: There are hundreds of devices on the market, and each one delivers different levels of nicotine (or no nicotine at all) and a slightly different cocktail of chemicals. With these caveats in mind, I asked researchers to share what worries them most. Here’s what they told me.
The nicotine in e-cigarettes may stress the cardiovascular system
When you turn on an e-cigarette, you’re heating a liquid that contains flavors and other chemicals, and often, nicotine.
Some devices, in particular Juul, deliver spectacularly high doses of nicotine. (Juul says one of its e-liquid pods is equal to a pack of cigarettes in terms of nicotine.)
“Nicotine [in e-cigarettes] does the same thing as [combustible] cigarettes,” said Neal Benowitz, a professor of medicine at the University of California San Francisco who’s been studying the link between e-cigarettes and heart health. It can increase the adrenaline circulating in our bodies, and activate the sympathetic nervous system (our “fight or flight” response), raising blood pressure, speeding up the heart rate, and causing the arteries — the vessels that carry blood — to narrow.
In January of last year, the National Academies of Sciences, Engineering, and Medicine in its assessment of the evidence on the health impact of vaping determined that there was “insufficient” evidence that e-cigarette use leads to long-term changes in heart rate and blood pressure.
But Goniewicz told Vox that’s rapidly changing. The impact of e-cigarettes on the body’s cardiovascular system is an emerging area of research — with more studies piling up to suggest vaping could in fact be bad for the heart.
In a review of the literature, for the Nature Reviews Cardiology journal, Benowitz and his co-authors made the case that while we don’t yet know what that means for long-term health outcomes, it’s possible nicotine in e-cigarettes will contribute to cardiovascular events, “particularly in people with underlying cardiovascular disease.”
Several recent observational studies have found a link between regular vaping and an increased risk of heart attacks, strokes, and coronary artery disease. The studies don’t prove e-cigarettes cause these conditions, but given the known cardiovascular effects of nicotine, there’s likely a lot more to learn about vaping and its effect on these diseases.
The microscopic particles e-cigarettes emit have been linked to heart attacks, high blood pressure, and coronary artery disease
Even when vapor is nicotine-free, it may carry other heart health risks. The heating element in e-cigarettes emits tiny particles, sometimes including metals, and these can lodge themselves deep into the lungs and get absorbed into the body’s circulatory system. “That’s where we see the potential cardiovascular toxicity,” Goniewicz said.
Researchers don’t yet know what risks e-cigarette aerosol particles carry, but these tiny particles have been studied extensively in the context of air pollution and tobacco smoking. In those studies, researchers have linked exposure to small particles with a range of bad cardiovascular outcomes — including heart attacks, high blood pressure, and coronary artery disease.
The thinking is that when we’re exposed to large particles — like dust — our bodies mount a defense against them. Namely, we cough, kicking these foreign pollutants out of our respiratory tract. But with fine particulate matter, that defense mechanism doesn’t kick in — and again, these micro contaminants can seep into our lungs and cardiovascular system.
Same goes for other toxic chemicals e-cigarettes produce when they’re heated, such as acetaldehyde, formaldehyde, and acrolein.
“We already have sufficient evidence from hundreds of studies that link exposure to those chemicals with disease outcomes,” Goniewicz said. “We know that formaldehyde can cause cancer and that acrolein can cause certain cardiovascular diseases.” So there’s no conclusive evidence directly linking this aspect of e-cigarette use to long-term cardiovascular outcomes. But based on these studies, researchers believe such a link is plausible.
E-cigarette vapor may irritate the lungs
Much of the harm caused by tobacco smoking comes from the combustion process — smoke wears down the cells lining the lungs, damaging them, and making them more penetrable to the irritating, and cancer-causing, chemicals in cigarettes. Since electronic cigarettes don’t burn tobacco, the vapor they produce is thought to be much less harmful than conventional cigarette smoke. But that doesn’t mean vapor is harmless.
Breathing vapor into the lungs can irritate them — and that’s been demonstrated in recent research on wheezing. Wheezing — that high-pitched sound caused by narrowed and abnormal airways — is more than just an annoyance: It can be a sign of emphysema, heart failure, and lung cancer.
Researchers recently tracked 28,000 adults to tease out whether e-cigarettes exacerbate wheezing. Some of the people in the study were current vapers who used only e-cigarettes; others were smokers only; still others were dual users (who smoked and vaped); and finally, there were also folks who didn’t smoke or vape at all.
Compared with that last group — the non-users — the risk of wheezing among the vapers doubled.
When the researchers looked at the study participants’ history of vaping or smoking, they came to even more interesting findings: The risk of wheezing was higher in current vapers who were also ex-smokers than in ex-smokers who did not vape. In other words, it wasn’t just a vaper’s potential history of smoking that was driving the uptick in wheezing among vapers. “Therefore,” the authors concluded, “promoting complete cessation of both smoking and vaping will be beneficial to maximize the risk reduction of wheezing and other related respiratory symptoms.”
Other studies have focused on whether e-cigarette users are more likely to develop chronic obstructive pulmonary disease (COPD), a set of lung complications that make it hard to breathe. Research in mice and human airway cells showed that nicotine-containing e-cigarette vapor seemed to trigger “effects normally associated with the development of COPD.”
In preliminary human studies, researchers also found associations between regular vaping and COPD. But again, this human research was observational — not experimental — so it’s not yet clear that vaping caused COPD. (For example, it’s possible the people who have COPD are more likely to use electronic cigarettes, such as ex-smokers seeking a harm-reduction method.)
Still, Benowitz said, “You don’t want to put stuff in your lungs that could cause lung inflammation. My biggest concern about e-cigarettes is that if you’re not a cigarette smoker, they could potentially aggravate asthma, cause a cough, and increase the risk of respiratory tract infection — like cold, flu and bronchitis.”
Does vaping help people quit smoking or lead to more smoking?
We still don’t know for sure whether the rise in vaping is leading to fewer adults smoking tobacco. The best available research on the question was published earlier this year in the New England Journal of Medicine. The randomized trial on e-cigarettes showed people who were randomly assigned to use e-cigarettes quit smoking at almost double the rate of people who were randomly assigned to nicotine replacement therapy.
But while e-cigarettes performed better than nicotine replacement therapy in the study, they only helped a minority of participants in the vaping group quit.
On the other hand, there is strong evidence that e-cigarettes may act as a gateway to traditional cigarette smoking among youth. The National Academies of Sciences, Engineering, and Medicine report on the health impact of e-cigarettes assessed 10 high-quality studies on this gateway question, and they all pointed to the same effect.
“The evidence base was large enough and consistent enough and strong enough to conclude that there’s an association between e-cigarette use and ever-use of combustible tobacco [cigarettes],” said Adam Leventhal, a member of the report committee, last January. But what’s less clear is whether young people are just more likely to try cigarettes after vaping, or whether they then go on to become long-term smokers.
Either way, this is a very important finding because another key question about the introduction of e-cigarettes to the market has been what impact they’ll have on youth smoking rates, which have dropped precipitously in recent years. Right now, like many e-cigarette health questions, we don’t know the results for certain. But it’s probably time we start paying attention to the possibilities.