In the past few years, e-cigarette use has exploded in the United States, with sales more than doubling annually. It’s expected that by 2017, the e-cigarette industry will be worth over $10 billion a year, and by 2021, e-cigarettes will take over the tobacco market with more sales than traditional cigarettes.

Their popularity stems from their deliverance of addictive nicotine without the other effects of traditional smoking. But few medical debates attract the level of passion and venom as the current battle over e-cigarettes. A growing number of scientists and medical professionals are condemning e-cigarette use (or “vaping”), with opponents claiming that e-cigarettes are simply an avenue for increased nicotine addiction, pulling in teens and children with fruity flavors and ubiquitous advertising. On the other hand, proponents say that these battery-operated nicotine vaporizers are saving lives by providing an alternative to smoking, one of the most deadly habits a person can have.

With all of the opinions flying around, it can be hard to tease apart the facts from the rhetoric. Here are the most common myths about e-cigarettes so you can make your own informed decision.

Myth 1: E-cigarettes are completely safe.

Fact: E-cigarettes are less toxic than conventional cigarettes, but still pose health risks.

You may have seen the recent pronouncement from Public Health England stating that e-cigarettes are “95 percent safer” than conventional cigarettes. While some question the validity of the number, the fact is, e-cigarettes do produce fewer carcinogenic toxins than regular cigarettes — thus, yes, they are “safer” than smoking regular cigarettes.

But “safer” doesn’t mean “safe”: Studies have shown that e-cigarettes produce the same kinds of short-term changes in lung function as cigarettes, and there are no current evaluations of long-term effects from vaping. And more recently, a new study from found that e-cigarette flavorings contain compounds that are linked to lung disease. As one review concludes, “electronic cigarettes can hardly be considered harmless.”

Professionals are particularly concerned about the so-called safety of e-cigarette use by children and teens. In 2014, the National Youth Tobacco Survey found that, for the first time, e-cigarettes overtook cigarettes as the most commonly used tobacco product among middle (3.9 percent) and high school students (13.4 percent). Some suggest that this sudden uptick is a result of TV, radio, and Internet advertising, which glamorize vaping — commercials that would be illegal today for other tobacco products. And while e-cigarettes might have fewer carcinogens than regular cigarettes, they still contain nicotine, which can impair brain development and cause mood disorders in adolescents.

Myth 2: E-cigarettes only emit water vapor, eliminating the dangers of secondhand smoke exposure.

Fact: E-cigarettes produce fewer toxic compounds, but the same amount of fine particles as conventional cigarettes.

Many people believe that e-cigarettes produce nothing that could lead to secondhand effects. The manufacturers are particularly to blame for this myth, as some still make the claim on their websites that their products only produce “harmless water vapor.” But research has shown that e-cigarettes, though “smokeless,” do produce potentially harmful vapors — just not to the same degree as regular cigarettes.

For example, a recent study found that while e-cigarettes produce less nicotine or other toxic compounds than traditional cigarettes, they produce the same amount of ultrafine particles that can become embedded in lung tissue and lead to respiratory problems. And vapors released from e-cigarettes are definitely harmful secondhand. So again, it’s a matter of degree — vaping is better than smoking, but the best thing for your body and those around you would be neither.

Myth 3: E-cigarettes are the most effective way to quit smoking.

Fact: Study results are mixed, with studies finding e-cigarette use reduces likelihood of quitting and may even lead to tobacco use.

One of the most hotly debated facets of e-cigarettes is whether they live up to claims that they help smokers quit. The World Health Organization estimates that smoking is responsible for almost 9 percent of all deaths worldwide, not to mention health care costs or reduced quality of life. Every cigarette costs the smoker 11 minutes of life, scientists say. So if e-cigarettes really do meaningfully reduce smoking, then they absolutely have life-saving potential.

But many argue that such claims are exaggerated or even false, and instead, that e-cigarettes are leading people — particularly teens — to smoke more. Critics of e-cigarettes are quick to point out that the electronic versions are not subject to the same advertising, flavoring, or sales restrictions as conventional nicotine products. They argue that money, rather than public health, is the main motivation of e-cigarette producers: “By moving into the e-cigarette market, the tobacco industry is only maintaining its predatory practices and increasing profits,” write medical and public health authorities in a letter to the World Health Organization Director-General Margaret Chan.

So what does the science say? Unfortunately, results to date are inconclusive. Some studies suggest that e-cigarettes might help smokers quit. For example, one study found e-cigarettes were more effective than other smoking-cessation aides. But another study found that while e-cigarette smokers were more likely to stay away from regular cigarettes, adding e-cigarettes on top of smoking didn’t reduce their bad habits. And other studies have found that e-cigarette use actually decreases a smoker’s likelihood of quitting. The evidence is all over the place. While that doesn’t mean e-cigarettes are useless, it does call into question the notion that they’re a quitting panacea.

But more troubling are recent studies that seem to bolster critics’ fears that vaping may even increase cigarette smoking, especially in adolescents. Studies are finding that students who’ve never used tobacco products regularly use e-cigarettes. And a study in the Journal of the American Medical Association found that ninth graders who had used e-cigarettes were more likely to start smoking within the next year. Similarly, a study of college smokers found that those which tried e-cigarettes didn’t reduce their habit, and instead, were more likely to continue smoking than those that didn’t.

The ultimate question becomes whether e-cigarettes should be regulated with the same laws as regular cigarettes. So far, governments seem to be leaning toward more stringent legislation, though current laws are still much more relaxed (there are even states where it is legal for minors to by e-cigarettes). One option is to list and regulate e-cigarettes as a medicine, like nicotine patches or other stop-smoking aides.

As for your health, e-cigarettes are better than smoking, but that’s a pretty low bar. The best thing for you and those around you is to kick nicotine for good.