Thor Christensen

When e-cigarettes first appeared a decade ago, they seemed like a healthy compromise for smokers who wanted to quit but simply couldn’t shake their addiction to nicotine.

But as the vaping movement gathers steam, health experts have grown increasingly worried about e-cigs and whether they might be hurting more people than they help — including impressionable teens.

E-cigarette vapor lacks the tar, smoke and carbon monoxide that make traditional cigarettes so dangerous. But the cocktail of nicotine and chemicals like formaldehyde in e-cigarettes poses a very real risk to heart health, says Dr. Parin Parikh, a Dallas cardiologist.

“It’s scary, because they’re addictive and totally unregulated, just like street drugs,” Parikh says. “E-cigarette companies aren’t required to disclose what substances are in them … so we don’t know what long-term effect they have on the heart or the brain.”

Invented in China, e-cigarettes hit the U.S. market in 2004. Sales have exploded in recent years, with hundreds of brands and thousands of flavors being sold in a growing number of gas stations, vape shops and online: The Smoke-Free Alternatives Trade Association says the e-cigarette industry will be worth $10 billion by 2017.

E-cigs come in several different shapes — some look like traditional cigarettes, others like pens or cylindrical pipes. But they all work on the same concept, with a heating element turning a liquid “juice” into a smokelike vapor you can inhale.

What exactly is in the juice is what health experts are worried about.

The FDA, which regulates tobacco products, has proposed regulation on Capitol Hill that would force e-cigarette companies to disclose their ingredients and follow certain rules about marketing and packaging. Until that happens, people are basically inhaling a mystery vapor.

“Without regulation, it’s really the wild, wild West,” says Amy Lukowski, a tobacco-treatment specialist and psychologist at National Jewish Health, a Denver-based academic medical research facility. “Some people will tell you ‘It’s just water vapor.’ But it’s not. It’s important for people to be wary of the dangers.”

A handful of e-cigarette companies say their products are nicotine-free. But the majority acknowledge that their products do contain nicotine — an addictive stimulant that causes blood vessels to restrict and increases blood pressure and heart rate.

“It doesn’t matter if it’s smoke or vapor — nicotine definitely causes adverse effects on cardiovascular health,” Parikh says.

Manufacturers counter that e-cigs provide a nicotine fix without all the dangerous chemicals in traditional cigarettes.

“There has been an amazing amount of scrutiny about a product that simply is providing what adults are seeking; the delivery of nicotine without the over 6,000 chemicals and 66 known carcinogens associated with the smoking of tobacco,” says a prepared statement from the Tobacco Vapor Electronic Cigarette Association.

But e-cigarettes aren’t necessarily carcinogen-free. In September, the Oakland, Calif.-based Center for Environmental Health commissioned a study testing nearly 100 e-cigarette products. The conclusion? “The majority of e-cigarette products tested produce high levels of the cancer-causing chemicals formaldehyde and acetaldehyde,” according to the report.

“People are being deceived,” says Michael Green, the center’s founder and executive director. “People know cigarettes cause cancer … they have the knowledge. But the e-cigarette companies are marketing their products as steam, so people think there’s no health impact. We’re not advocating that e-cigarettes be banned. We’re just advising they be honest in their marketing.”

Lukowski says people should be wary of e-cigs until more long-term studies are done — especially studies of propylene glycol, the petroleum-based compound that’s a major ingredient in almost all e-cigarette juice.

“If you heat up and change the chemistry of propylene glycol and inhale it, it’s going to have an impact,” she says. “We just don’t know yet what that impact is going to be.”

Proponents of e-cigarettes say that, at the very least, they help smokers quit regular cigarettes with a higher success rate than if they used nicotine gum or patches.

But Lukowski says many people use e-cigs in public places where they aren’t allowed to smoke and then go right back to regular cigarettes as soon as they’re in a smoke-friendly zone.

“We’re seeing a lot of dual use,” she says. “People intend to use it as an aid to quit, but it’s really not having that impact.”

One bigger worry is that e-cigarettes will get a whole new generation addicted to nicotine.

Right now, there’s no federal law forbidding the sale of e-cigarettes to minors. And while states including Texas have enacted their own e-cigarette bans for anyone under 18, teens can easily buy the products online.

The U.S. Centers for Disease Control and Prevention recently released statics showing skyrocketing e-cigarette use among teens, from 1.5 percent in 2011 to 13.4 percent in 2014. And a 2015 study in the Journal of the American Medical Association Pediatrics showed e-cig use among young people doesn’t discourage traditional cigarette use, and may even encourage it.

“It’s a gateway,” Lukowski says. “Adolescents are more vulnerable to nicotine addiction than adults. Their developing brains crave more nicotine, which can lead to dual use or abandoning e-cigarettes altogether and going to traditional combustible cigarettes.”

Teens also crave all things cool, which may be why e-cigarette companies have hired celebrity spokespeople for print and TV ads including Courtney Love, Jenny McCarthy and actor Stephen Dorff.

The e-cigarette firm Vapor Shark went so far as to put up billboards featuring Santa Claus saying “I don’t always vape, but when I do, I choose Vapor Shark.”

With e-cigarettes sold in flavors like cherry, chocolate, cookies-and-cream and even pizza, it’s hardly a surprise that teens are increasingly using them, says Green of the Center for Environmental Health.

“There’s no cop on the beat, so they’re marketing it to kids as hip and cool in a Joe Camel-esque way,” he says. “After everything our society has learned and done to help people not get addicted, and now e-cigarette companies are marketing to teens and selling candy flavors with no rules. … It’s galling. It doesn’t make sense. And it’s our responsibility to make it stop.”