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Michael: Electronic cigarettes, or e-cigs, as the kids call them, seem to be everywhere these days, from Super Bowl ads to talk shows. They claim to help people quit smoking, or at least provide a safer alternative to cigarettes. See, your average cigarette is filled with tobacco, which is the leaves of tobacco plants prepared with some chemicals. When you burn tobacco, you’re inhaling thousands of compounds, including some that are toxic, or addictive like nicotine.

E-cigs, on the other hand, are battery-powered and turn a chemical mixture, or e-liquid, into a vapor that you inhale. But are they really better for you than cigarettes? Turns out, there’s not much conclusive research about e-cigs, so we still don’t really know how they could affect human health. When you turn on an e-cigarette, a small, metal coil warms up and heats the e-liquid, turning it into a vapor that you inhale through a mouthpiece.

The original e-cigs were developed around 2002 or 2003, and mimicked the size and shape of cigarettes. But now there are vaporizers, vape pens, or vape mods, which are larger devices with different features, such as adjustable power levels for more or less vapor and adjustable flavor intensity with each puff. E-liquids usually have three main ingredients: there’s propylene glycol, a chemical used in food and cosmetics to keep them moist; artificial flavorings, like menthol or bubble gum; and sometimes nicotine.

Since e-cigs only vaporize a few ingredients, they’re supposedly a safer alternative to smoking tobacco, which produces lots of toxic chemicals. But the research is complicated – most studies aren’t conclusive, and sometimes they contradict each other. In the United States, the FDA didn’t begin regulating e-cigs until this August, so there have been concerns about quality.

For example, Multiple studies from 2012 to 2016, found that tiny metal particles could break off from some heating coils when they get hot. Over time, inhaling those metal particles could damage someone’s lungs. There were also concerns about the quality of e-liquids – like, before they were regulated, nicotine was sometimes found in products that claimed to be nicotine-free.

You might have even heard that e-liquids contain an ingredient in antifreeze called diethylene glycol, which is toxic to humans. That’s actually a myth. In 2009, the FDA did study two companies’ e-cigarette products, and found this chemical in one e-liquid sample. But the findings haven’t been replicated since, so it’s likely that this sample was just contaminated from another source.

Regardless, the new FDA regulations will monitor the quality of coils and e-liquids, the EU adopted similar safety requirements in 2014, and health organizations from other countries will probably follow suit.

But we still don’t know much about their long-term effects, because e-cigarettes haven’t been around long enough for detailed studies. Take the e-liquid ingredient propylene glycol. Even though the FDA declares it safe in food and cosmetics, we don’t know what happens in the long-term when you breathe it in. One 2015 study from the New England Journal of Medicine reported that heating propylene glycol could potentially produce formaldehyde-releasing agents, which are chemicals that could become formaldehyde as they break down.

If you did dissections in high school biology, you might remember formaldehyde as the smelly chemical that preserves dead bodies. And extended exposure to formaldehyde vapor leads to an increased risk of cancer. Then again, we don’t know if these chemicals have the same health effects as exposure to pure formaldehyde. And we don’t even know for sure that heating propylene glycol with e-cigarette coils creates these formaldehyde-releasing agents, because the study hasn't been repeated.

One of the reasons it’s so hard to study the health effects of e-cigs is because the research methods that scientists use to study cigarettes don’t transfer that well. To understand the chemicals in cigarette smoke, for example, scientists can use machines that simulate how often a smoker takes a puff and how much smoke they inhale.

But with customizable vape pens, different studies have been using different vaporizers, power settings, and e-liquids. So it’s hard to compare results, and no one knows exactly how much vapor the average user breathes in. Also, scientists have learned how the chemicals in tobacco smoke interact with our bodies: These chemicals react with compounds in certain cells, cause lung damage, and leave behind byproducts that turn up in hair or urine.

Unfortunately, right now, no one knows what cellular components the e-liquid ingredients might be reacting with, and what byproducts might be created. Like I said, it’s complicated. Now, the health risks of e-cigarettes might be inconclusive, but can they at least help smokers quit? There are plenty of anecdotal success stories, which is awesome! Except there’s not really conclusive, scientific evidence to prove e-cigarettes help – lots of different studies say different things.

One study published in the journal Addiction tracked nearly 6000 British cigarette-smokers between 2009 and 2014. They found that more people who used e-cigs quit smoking altogether than those who used over-the-counter aids like patches or gum, or no aids at all. But a similar study in 2013 from the journal of Nicotine and Tobacco Research saw the opposite in nearly 3,000 Americans who called smoking quitline services.

They surveyed these people seven months later, and reported that e-cigarette users were less likely to quit smoking. It’s possible that e-cigs could be helpful because people think they are, which is something we call the placebo effect. Ultimately, though, there’s just a lot we don’t know about the science of e-cigarettes. As scientists do more rigorous, repeatable, large-scale research, we’re hoping to find some more answers. But right now, it’s only safe to say that we really don’t know how safe they are.

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