Everything you need to know about e-cigarettes

The explosion of e-cigarette use in recent years has sparked one of the most heated ongoing public health debates. Some argue these devices save lives; others say Big Tobacco is getting a new generation hooked on its products.

What is an e-cigarette?

E-cigarettes are slender, battery-powered devices that vaporize liquid nicotine to imitate conventional smoking. Using an e-cigarette can give a buzz similar to smoking cigarettes — except the buzz comes from the nicotine in vapor, not smoke.

When a user inhales from an e-cigarette's mouthpiece, the device powers up and then vaporizes some liquid nicotine, which is located in an insertable cartridge. The vaporized nicotine then flows through the device and into the user's mouth.

E-cigarettes can come in all shapes and sizes, and some look very similar to regular cigarettes. Right now, there are about 500 e-cigarette brands and more than 7,000 flavors on the market, and they work in different ways, delivering varying amounts of nicotine, toxins, and carcinogens.

How dangerous are e-cigarettes?

We don't actually know. As an American Heart Association review on e-cigarettes states: "In general, the health effects of e-cigarettes have not been well studied, and the potential harm incurred by long-term use of these devices remains completely unknown."

Based on the science so far, short-term exposure to e-cigarettes doesn’t appear to carry serious and immediate health effects. As the AHA points out, "The data on health effects to date, studied primarily in healthy people with short-term exposure, reveal little or no evidence of severe adverse events. Respiratory irritation and the bronchial constriction from a propylene glycol aerosol raise concerns about harm to people with asthma and chronic obstructive pulmonary disease, but one small study reports no harm but rather benefit when users quit smoking or smoke fewer cigarettes per day."

A man vapes. (Marco Prati/Shutterstock)

Keep in mind, however, that the research here is still early, and this conclusion on e-cigarettes could change once tens of thousands of people — and not just dozens or hundreds — have been studied.

Bigger questions center on the toxicity of e-cigarette’s aerosol and liquids — and their potential long-term effects. Maciej Goniewicz, of Roswell Park Cancer Institute, is one of the leading researchers in this area. In one study, he looked at 12 brands of e-cigarettes and found that their vapors were mostly composed of nicotine and a nicotine solvent (propylene glycol or vegetable glycerin). Also, the levels of toxicants and carcinogens in e-cigarette vapor were nine to 450 times less prevalent than in conventional cigarette smoke.

Though propylene glycol and glycerin are generally considered safe substances, not a lot is known about the long-term effects of daily inhalation, Goniewicz says. There’s some evidence from theater settings — in which propylene glycol has been used to create fog — that suggests it can be a lung irritant. Goniewicz has also found toxic substances and cancer-causing compounds, such as formaldehyde and acetaldehyde, in e-cigarettes.

Reasons for concern have popped up elsewhere — though, again, nothing conclusive yet. Some research has shown that cells exposed to e-cigarette vapor showed similar genetic changes as cells exposed to conventional cigarette smoke — raising concerns that e-cigarettes could potentially lead to lung cancer.

One big problem here: E-cigarette products vary widely, making them tough to study. "Some had a higher presence of the toxicants, while other products have very low levels or even undetectable levels of toxicants," Goniewicz said. What's more, research shows that the heating process in e-cigarettes can change the composition of potentially harmful chemicals. "If the temperature goes too high, then there are more toxicants," he warned.

Chris Bullen, an e-cigarette researcher and professor at the University of Auckland's school of public health, noted that newer electronic cigarettes use a heating control mechanism that prevents "cooking" the e-liquid, and reduces the risk of generating harmful aldehydes. He cautioned about drawing conclusions from older studies that may be based on out-of-date technology. But he also added that there's a lot of inconsistency in manufacturing quality: "Backyard operators" who make e-cigs may run the risk of contamination.

"Then there are the flavors," he added. "Very little is known about what happens with these when heated and inhaled for weeks, months or years."

How does the federal government regulate e-cigarettes?

While some countries have banned the devices outright, the US federal government doesn't regulate e-cigarettes, unless they're being marketed for therapeutic purposes. This is because the Family Smoking Prevention and Tobacco Control Act of 2009 gave the Food and Drug Administration the power to regulate the tobacco industry, but e-cigarettes — along with other tobacco-related merchandise such as cigars and nicotine gels — were left out.

By April 2011, the FDA announced it was going to address this loophole. Then, in April 2014, the agency proposed a draft rule that will redefine e-cigarettes as "tobacco products." Once finalized and enacted in another few years, e-cigarettes will be FDA-regulated under the Tobacco Control Act. Among other things, this would:

• Ban e-cigarette sales to minors
• Require health warning labels on e-cigarettes, which would warn of the possibility of addiction
• Prohibit vending machine sales of e-cigarettes except in places that don't allow minors
• Require e-cigarette manufacturers to register a list of their products' ingredients
• Require an FDA review of marketing plans
• Require FDA approval of any claims about e-cigarettes' benefits, such as the claim that e-cigarettes can help people quit cigarettes
• Ban free samples of e-cigarettes

The FDA's rules don't include some restrictions that health advocates called for: They don't halt online sales of e-cigarettes, prevent television and radio advertising, or ban the marketing of appealing flavors.

Some public health officials and vaping advocates think that regulating e-cigarettes as tobacco products is overkill; after all, the devices don't even hold tobacco. They also worry that if e-cigarettes are regulated too heavily or barred from the market, the public could miss out on a device that could have saved lives. Some experts also think heavy regulation could halt innovation, deterring manufacturers from creating more advanced devices with better nicotine delivery systems that could help reduce smoking.

As Peter Hajek, a professor at Queen Mary University of London, put it, "Regulators need to watch out for intended consequences of overzealous regulation, such as stifling such developments or making e-cigarettes more expensive and less attractive to smokers; and also avoid conveying a message that e-cigarettes are regulated as strictly [as] or even more strictly than cigarettes because they are as bad."

FDA officials are conducting a scientific review of e-cigarettes and their effects. Until then, states, counties, and cities have been enacting their own e-cigarette regulations. The American Nonsmokers' Rights Foundation tracks which lower levels of government have acted here.

Are e-cigarettes safer than regular cigarettes?

Most researchers cautiously lean toward "yes" — despite the unknowns.

Because the immediate harms of e-cigarettes appear to be minimal compared with regular cigarettes, many researchers agree that there's a compelling case to be made for e-cigarettes as a harm-reduction tool for heavy smokers, at least in the short term.

The tougher question is how the long-term impacts of e-cigarettes compare to the long-term impacts of smoking. "It's probably fair to say that a long-term e-cigarette user is not going to die from tobacco-caused disease," says Thomas Eissenberg, co-director of the Center for the Study of Tobacco Products. "But it's not clear whether they'll die from an e-cigarette-caused disease and whether their rates of death will be less than, more than, or the same as the rates of death we see from tobacco-caused diseases."

What makes e-cigarette vapor different from tobacco smoke?

E-cigarettes don't contain tobacco. Instead, they contain liquid nicotine (sometimes with flavoring).

Conventional cigarettes, on the other hand, contain tobacco and all the additives tobacco companies include to make the product taste or feel a certain way.

Another key difference is that tobacco is burned and inhaled as smoke, while e-cigarettes just heat up liquid nicotine to turn it into an odorless vapor.

Is nicotine, on its own, harmful?

(Melanie Tata/Flickr)

Some researchers — especially those who view e-cigarettes more favorably — argue that nicotine in and of itself doesn’t harm people. The problem, they say, is the tobacco and other chemicals in combustible cigarettes.

The more staunch tobacco-control types argue that nicotine itself is dangerous and addictive and that it should be avoided. That puts e-cigarettes in a less favorable light.

The truth likely lies somewhere in between. As one review stated, "Nicotine is the addictive chemical in tobacco smoke, but its involvement in smoking-related harm (outside pregnancy) is very small, if any, compared to cigarette smoking." Another systematic review pointed out that nicotine can have a variety of potential health effects, from raising one's cardiovascular risk to causing birth defects in pregnant women.

The other nicotine question has to do with whether e-cigs even deliver enough to satisfy smokers. We know from this Cochrane systematic review that if you want to help people quit smoking, you need to give them nicotine. Yet studies, such as this one in Nature, found that the nicotine delivery to the bloodstream from these devices varied, and was still much slower and lower than the concentrations that regular cigarettes give smokers. "Compared to smoking one tobacco cigarette," the researchers wrote, "the [e-cigarette] devices and liquid used in this study delivered one-third to one-fourth the amount of nicotine after five minutes of use."

How many people use e-cigarettes?

E-cigarettes have become increasingly popular in recent years. In 2015, the Centers for Disease Control and Prevention (CDC) reported that the use of e-cigarette devices among middle school and high school students tripled between 2013 and 2014. That means about 13 percent of students now use them — outstripping the number who smoke conventional cigarettes.

Use of e-cigarettes is on the rise. (Pew Charitable Trust)

By 2017, sales of e-cigarettes in the US are expected to surpass those of conventional cigarettes, reaching $10 billion. The three major tobacco companies, through their buying up of small e-cigarette companies, could share 75 percent of these profits over the next 10 years.

Do e-cigarettes help people quit smoking?

The evidence on quitting is still limited and has mixed results.

So far, two randomized studies (here and here) have looked into the question of quitting — and both found that e-cigarettes may indeed help smokers quit. Another lower-quality web-based survey came to the same conclusion.

But not everyone's convinced. As a systematic review by the Cochrane Library noted: "The small number of trials, low event rates and wide confidence intervals around the estimates mean that our confidence in the result is rated 'low.'" For example, there were weaknesses in the randomized trials. One trial compared e-cigarettes with nicotine patches for helping people quit. But participants had to go out and pick up the patches from the pharmacy, whereas e-cigs were delivered to their doorsteps — a difference that could have biased the results in favor of e-cigarettes.

Other evidence, meanwhile, suggests that e-cigarettes may not be so effective at helping people smoke fewer traditional cigarettes. A study published in JAMA Internal Medicine in 2014 concluded: "E-cigarette use by smokers was not followed by greater quitting, or reduction in consumption one year later." Another 2015 study in the journal Addiction found that daily use of e-cigarettes seemed to be associated with an increase in the rate of attempts to quit smoking and less smoking, though not increased rates of quitting. These were both observational studies, so lower quality than the randomized trials.

And there are lots of harder questions that remain unanswered, as the American Thoracic Society has noted. Could e-cigarettes prolong the process of quitting? Could they make quitting less likely? For now, we don't know.

Is secondhand e-cig vapor bad for you?

A comprehensive analysis of the research, published by the American Heart Association, suggests e-cigarette vapor contaminates the air with nicotine and toxins, but the long-term health effects of exposure to these secondhand chemicals remain unknown.

Roswell Park Cancer Institute researchers found e-cigarette vapor leaves nicotine in indoor environments, but they didn't find significant traces of tobacco-based toxins such as carbon monoxide. And conventional cigarettes left 10 times more nicotine than e-cigarettes. But the study, the authors cautioned, looked at a limited number of chemicals.

Other researchers at the Roswell Park Cancer Institute found traces of select toxins in e-cigarette vapors, but these various toxins were nine to 450 times less prevalent than in conventional cigarette smoke. Another study from German health researchers also found increased levels of some toxins in the air following e-cigarette use.

So it's still unclear whether consistent exposure to secondhand nicotine and toxins, especially the low levels left by e-cigarettes, could be dangerous to someone's health in the long term.

Meanwhile, secondhand smoking from conventional cigarettes, as the Mayo Clinic explains, is proven to be very bad for people's health.

The answer to the secondhand vapor question could be crucial to public health policy: e-cigarette supporters argue that the public ban on smoking shouldn't apply to e-cigarettes because secondhand vapor isn't proven to be dangerous. Whether that claim holds up in future research could decide if people can legally use e-cigarettes in public settings.

Can e-cigarettes explode?

E-cigarettes are electrical devices, so they can explode. Here is one example:

Still, like most electronic malfunctions, it's rare. People can generally use their e-cigarettes without worry of explosions.

You didn't answer my question!

This is very much a work in progress. It will continue to be updated as events unfold, new research gets published, and fresh questions emerge.

So if you have additional questions or comments or quibbles or complaints, send a note to Julia Belluz: julia.belluz@vox.com.

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