Electronic cigarettes, embraced by users as a healthier alternative to smoking or a good way to quit, are picking up steam.
There's little research on how safe they might be or whether they're an effective strategy for kicking the habit, but more people are giving e-cigarettes a try every day.
About one in five adult cigarette smokers in the U.S. had tried electronic cigarettes in 2011, nearly twice as many as in 2010. Sales reached nearly $500 million in 2012 and are expected to double to $1 billion this year. As the market grows, even tobacco companies are jumping on board.
R.J. Reynolds Vapor Co. launched its Vuse electronic cigarette this summer in Colorado. Altria Group Inc., parent company of the nation's largest cigarette maker, Philip Morris USA, will soon debut its product, MarkTen, in Indiana.
Electronic cigarettes, or e-cigarettes, are a smoke-free alternative to the traditional paper cigarette. The most basic version, one that could be mistaken for an actual cigarette, is comprised of a liquid cartridge attached to a white cylinder containing a battery.
The battery heats the liquid into a vapor that the user inhales. Instead of smoking, it's come to be called "vaping."
The liquid is a mixture of propylene glycol (a common chemical used in many in food products), vegetable glycerin, flavoring and nicotine. The composition can vary greatly by manufacturer.
Typical electronic cigarettes range from around $10 for a standard e-cigarette that requires replacement liquid cartridges to as much as $70 for a polished wooden model that can be refilled.
Although prices vary, pre-filled liquid cartridges, each lasting about as long as a pack of cigarettes, usually cost a few dollars, and bottles of flavored e-liquid range from a few dollars to more than $10 depending on size.
But as the market grows, little conclusive research has been done to determine the health effects of inhaling a nicotine-laced vapor.
The e-liquids themselves are not required to meet any federal standards, although the FDA is expected to exercise its regulatory authority over the products later this year.
Approval by the FDA means that a nicotine product, such as a patch or gum, has met standards of safety and effectiveness, said Dr. Anne Joseph, a tobacco researcher at the University of Minnesota. For now, e-cigarettes are in a gray area and are not regulated as tobacco products or medical devices, even though they share similarities with both product categories.
Joseph adds that electronic cigarettes may not be all bad for current tobacco users, with a couple of important caveats: Nonsmokers shouldn't start, and e-cigarette consumers should use them only with the goal of quitting.
There's a lot scientists still don't know. That includes the actual chemical exposure that users receive compared with traditional smokers' intake; the way vaporized nicotine is absorbed by the body; and the effects of secondhand vapor.
"States and local governments are having to revisit clean indoor air laws, and that's important for a couple reasons," Joseph said. "One, we don't know what they are emitting into the air."
Also, she worries that use of e-cigarettes will undermine years of antismoking campaigns that have taken cigarettes out of public places.
Compared with traditional cigarettes, electronic cigarettes appear to have fewer toxins, but the impact of e-cigarettes on long-term health must be studied, the Centers for Disease Control and Prevention said in February.
"E-cigarette use is growing rapidly," Dr. Thomas Frieden, director of the CDC, said in a statement at the time. "There is still a lot we don't know about these products, including whether they will decrease or increase use of traditional cigarettes."
Katie Forster, who had tried to quit smoking with nicotine gum and patches, recently bought an e-cigarette.
"I did a lot of research" about the safety, said Forster, 26, who works for an accounting firm. "And if I'm picking between a cigarette and an (e-cigarette), it's the lesser of the two evils for me."
Forster, who said she'll stick with it until she can quit smoking completely, chose a more elaborate device with a rechargeable battery and a refillable liquid cartridge.
The liquid is available in hundreds of flavors with varying levels of nicotine. It's those flavors, with appealing names such as Mocha Madness, Cotton Candy, Bourbon, Cowboy and Cuban Supreme, that have been a point of contention for some who worry that teenagers may be enticed. And for now, there is no federal restriction on the sale of e-cigarettes to minors.
Cindy Armstrong, 57, of east Charlotte, smoked for more than 30 years. She tried to quit smoking many times, and had gotten down to about five cigarettes per day, but couldn't give them up completely.
"I analyzed when I liked to smoke, and I realized that it wasn't the nicotine so much as having the cigarette in my hand," she said.
When her boyfriend gave her an e-cigarette starter kit for Christmas, she never went back to smoking traditional cigarettes, and now, she only uses a disposable e-cigarette occasionally.
John Toohey, 45, of Ballantyne, quit smoking cigarettes within a few weeks of ordering an electronic cigarette.
"One of the great things with the e-cig is that you can gauge the nicotine," he said. "Even when I go to zero (nicotine), I'll probably still use it because it satisfies the hand-to-mouth craving."
Scientists and medical professionals, meanwhile, continue to offer the following caution: Long-term health effects of electronic cigarettes are unknown, and it could be years before consensus is reached about their safety.
What's an e-cigarette?
Electronic cigarettes feature flavored nicotine vapor instead of smoke. They appeal to smokers who want to kick the habit, but have struggled with gums or patches.
The current iteration of the e-cigarette is credited to a Chinese pharmacist named Hon Lik, who patented his product in 2003. Researchers urge caution because little is known about the long-term effects, but concede that e-cigarettes may be better for current smokers than traditional cigarettes.
Millions still smoking
An estimated 43.8 million people, or 19 percent of adults, in the United States smoke cigarettes.
Cigarette smoking is the leading cause of preventable death in the U.S., accounting for more than 440,000 deaths annually.
—From Centers for Disease Control and Prevention