E-cigarettes have become popular, but their effect on health is still uncertain

Since e-cigarettes began showing up on the Internet and in mall kiosks in 2006, they've attracted several million users worldwide, and there are more than 200 brands from which to choose. Sales were estimated to have reached nearly $2 billion in 2013, and tobacco company executives have noted that e-cigarettes are eating into traditional cigarette sales. However, there is still much to be learned about e-cigarettes, including the long-term effects they have on users' health.

"They're so new that we don't know what chemicals are contained in e-cigarettes and we don't know the short- or long-term impacts," says Dara Jirkovsky, manager of health promotion for the American Lung Association Plains-Gulf Region.

E-cigarettes are plastic or metal tubes, usually the size of a cigarette, that heat a liquid nicotine solution instead of burning tobacco. That creates vapor, sometimes flavored, that users inhale.

Smokers like e-cigarettes because the nicotine-infused vapor looks like smoke but is said not to contain the thousands of chemicals, tar or odor of regular cigarettes. Some smokers use e-cigarettes as a way to quit smoking tobacco, or to cut down.

This photo taken on Wednesday, March 2, 2011, shows Blair Roberts, a 22-year-old sales associate at Colorado E-Smokes as he holds an electronic cigarette and the filter end that holds the liquid nicotine solution at an E-Smokes store in Aurora, Colorado. (AP Photo/Ed Andrieski)

Tyrone Owens, owner and founder of MO Vapes, which has several locations throughout Southeast Missouri, switched from cigarettes to vapors about two years ago because he worked in an environment where smoking was frowned on. Now, he's off nicotine for good, and he says many of his customers have had similar experiences. He says e-cigarettes are more effective for smoking cessation than patches or gums.

Because e-cigarettes allow users to adjust the amount of nicotine, he explains, users can get the nicotine their bodies crave, but gradually lower the amount until none is needed at all. He adds that smoking is very much a physical habit: reach for the lighter, bring the cigarette to the mouth and repeat. E-cigarettes continue that constant motion but cut down on the nicotine, so users are only trying to break one habit at a time.

"The best part of e-cigarettes is the fact that I don't smell like an ashtray," says Owens. "I save money on cologne because I don't have to spray as much. One or two spritzes will last me all day. My breath doesn't smell nasty, my teeth aren't yellow and I smell shower clean all day."

However, there's still not much scientific evidence showing e-cigarettes help smokers quit or smoke less, and it's unclear how safe they are.

Some believe lightly regulating electronic cigarettes might actually be better for public health overall, if smokers switch and e-cigarettes really are safer. One big draw of e-cigarettes is that, for now, they can be used in public places where smoking is not normally allowed -- e-cigarettes came along after the passage of most state smoking bans and other smoke-free policies, Jirkovsky says. However, as new laws and ordinances are being passed, they are beginning to include wording about e-cigarettes, says Melissa Allen, health educator at the Bollinger County Health Department.

Another worry about e-cigarettes is they may keep smokers addicted or encourage others to start using e-cigarettes, and even eventually tobacco products.

"The most concerning thing is that there are all these different flavors, and things like that are more appealing to younger people and children," says Allen. "If they're marketing them to children, it opens the door up to start smoking regular cigarettes."

In April, the U.S. Food and Drug Administration moved to regulate the marketing and sale of e-cigarettes, particularly to minors. The agency said the proposal sets a foundation for regulating the products, but the rules don't immediately ban the wide array of flavors of e-cigarettes, curb marketing on places like TV or set product standards. Once the new rules are finalized, the agency could propose more restrictions on e-cigarettes, though officials haven't provided a timetable for that action. The agency is conducting research to better understand the safety of the devices and who is using them.

In addition to prohibiting sales to minors and requiring health labels that warn users that nicotine is an addictive chemical, e-cigarette makers also would be required to register their products with the FDA and disclose ingredients. They also would not be allowed to claim their products are safer than other tobacco products.

They also couldn't use words such as "light" or "mild" to describe their products, give out free samples or sell their products in vending machines unless they are in a place open only to adults, such as a bar.

Companies also will be required to submit applications for premarket review within two years. As long as an e-cigarette maker has submitted the application, the FDA will allow the products to stay on the market while they are being reviewed. That would mean companies would have to submit an application for all e-cigarettes now being sold.

In the meantime, Allen and Jirkovsky urge consumers to use e-cigarettes with caution.

"We don't know that they're safe because there is no long-term evidence," says Allen. "Don't assume they're safe. Do some research and talk to your doctor."

Adds Jirkovsky, "You don't want to play around with your health or gamble with your long-term health effects. It's not worth the risk."

On the other hand, Owens says he believes e-cigarettes are here to stay, and hopes the industry can come to an agreement with cigarette companies, pharmacies and governments. He's seen firsthand the difference between cigarettes and e-cigarettes, and he hopes others will, too.

"We're not trying to fight anybody," he says. "We're trying to help human beings."

The Associated Press contributed to this report.