With the Oxford Dictionaries naming “vape” as 2014’s Word of the Year and a new study showing e-cigarette vaping has surpassed traditional cigarette smoking among U.S. teens, the debate over whether the practice is safe for users and those around them is heating up.

Federal and state lawmakers are grappling with how to regulate electronic cigarettes — alternatively called e-cigs, vape pens, e-hookahs, vaporizers — while health experts try to decide whether they help people quit smoking cigarettes or serve as a gateway into the habit.

This year will see “big fights about this, especially as a lot of major tobacco companies continue to take over the e-cigarette market,” said Stanton Glantz, a longtime antismoking activist and director of UCSF’s Center for Tobacco Control Research and Education. “The big question is, are the politicians going to side with the tobacco companies or the public?”

Most health experts consider e-cigarettes — battery-operated tubes that produce an inhalable vapor from liquid nicotine — to be safer than combustible cigarettes because they expose the user to fewer toxic chemicals. But they caution that more research is needed to determine the vapors’ effects on health. The devices can also be used to vape cannabis or candy-flavored liquids, either with or without nicotine.

The San Francisco Department of Public Health is set to kick off a public awareness campaign against e-cigarettes Monday. The campaign, part of the city’s Tobacco Free Project funded by the state tobacco tax, calls e-cigarettes harmful and says the flavored ones “hook teens on nicotine to replace smokers.”

Several studies released last month focused attention on the devices. A National Institutes of Health survey found that 10th-graders are now more likely to have tried an e-cigarette (about 16 percent) than a traditional cigarette (7 percent). A study published in the medical journal Pediatrics found that 29 percent of teens in Hawaii have used e-cigarettes.

With e-cigarette sales predicted to grow by 24 percent annually through 2018, big tobacco companies such as R.J. Reynolds, Lorillard and Altria are jumping into the business by buying up brands. Some Wall Street analysts expect e-cigarettes to surpass traditional cigarettes within a decade.

Much about the vaping industry remains hazy. E-cigarettes fall into a legislative gray area — they’re not medical devices and they’re not actually smoked, so they are largely unregulated.

But that’s starting to change. The U.S. Food and Drug Administration announced plans in April to start regulating e-cigarettes, and cities including San Francisco, Los Angeles, Chicago and New York enacted laws last year that treat the devices much like traditional cigarettes, meaning they can’t be used where smoking is banned.

California has banned the sale of e-cigarettes to minors, but further attempts to restrict their use have stalled. A bill by state Sen. Ellen Corbett, D-San Leandro, to prohibit the sale of e-cigarettes in vending machines failed in an Assembly committee last year.

UCSF’s Glantz and some of his colleagues have criticized some vaping regulatory efforts that put the products in a different category than cigarettes. To Glantz, anything that delivers nicotine should be treated like a tobacco product.

Urging common sense

The pro-vaping side agrees that sales should be prohibited to minors but argues that the devices shouldn’t be lumped in the same category as cigarettes.

“What we might end up with is all these different states having different laws and all these different municipalities having different interpretations,” said Stefan Didak of Oakley, co-president of the Northern California chapter of the Smoke-Free Alternatives Trade Association, which represents the vapor industry.

The industry group encouraged people who use vapor products to use common sense even in the absence of regulations — meaning, don’t vape on planes and other places where smoking is generally prohibited. But Didak said overly restrictive regulations may create unintended consequences.

“If you over-regulate things and are too strict, people are just going to order (vapor products) directly from some Chinese website,” he said. “It may actually encourage less-safe products on the market.”

The question over whether e-cigarettes encourage or discourage smoking, especially among youths, also remains under debate. Some studies show they help people quit; others show the opposite.

Educating the public

Didak says he’s proof of vaping’s effectiveness: He used it to wean himself off a 35-year cigarette habit.

“There is evidence that shows e-cigarettes help people quit smoking. But depending on who you ask, there’s probably a report someone can bring up that supports their (opposing) argument as well,” said Seibo Shen, founder and chief executive officer of VapeXhale, a San Francisco company that encourages healthy vaping by using specific techniques and materials in its products.

Shen’s company creates home-based vaporizers mainly for medical marijuana but is working to create portable devices. He said vaping is gaining acceptance and that the industry needs to be responsible.

“We’re very much into educating and making sure people understand not just how to use it but ... when and where to use the device appropriately,” Shen said. “Hopefully, we can start shaping the way people think about how they’re supposed to be used and how they’re not supposed to be used.”

Victoria Colliver is a San Francisco Chronicle staff writer. E-mail: vcolliver@sfchronicle.com Twitter: @vcolliver