Doctors have long warned about the health hazards of smoking, but they aren't quite sure how to handle electronic cigarettes and vaping.
Now a $2 billion-a-year industry, e-cigarettes are often branded as the smokeless alternative to cigarettes or as a tool to stop smoking altogether. The battery-powered devices turn nicotine-infused flavored oils into vapor, which is puffed like a cigarette. But very little is known about their health effects.
• Industry awaits looming federal regulation
As state and local lawmakers struggle with the growing popularity of electronic cigarettes, doctors too, are grappling with what to tell their patients.
"We have had a lot of years to know the harm of tobacco. E-cigarettes have been around since 2007, so there just has not been a body of evidence developed yet to say what's in them," said Dr. Pete Dehnel, who recently moderated a panel on e-cigarettes for the Minnesota Medical Association and the Twin Cities Medical Society.
"How are they harmful? How are they beneficial?" he asked. "We just don't have the science."
Supporters of the devices say the e-cigarettes are a safe alternative to smoking tobacco and point to a recent survey in the scientific journal Addiction that reported 60 percent of people trying to quit smoking on their own were more likely to succeed with e-cigarettes than with pure willpower or over the counter nicotine replacement therapies.
But the use of e-cigarettes is moving ahead of definitive scientific proof of benefits or harm, observers say. The U.S. Food and Drug Administration has just started the process to decide how to regulate the e-cigarette industry.
Last week, a group of 53 doctors and public health workers urged the World Health Organization not to adopt a restrictive strategy on e-cigarettes or classify e-cigarettes as tobacco. In an open letter to the organization, the group argued that e-cigarettes could be "among the most significant health innovations of the 21st Century."
Beyond the opinions and studies of effectiveness, researchers don't know for sure what e-cigarette vapor does to lungs.
"That's the great unknown," said Dehnel. "Whatever has been mixed in with the e-cigarettes hasn't been regulated or tested by anybody, so we can't say that. If you look at two different products they might be entirely different."
That lack of solid research puts doctors in a tough position, said University of Minnesota Medical Professor Dr. Anne Joseph.
While she will not discourage someone quitting smoking from trying e-cigarettes, Joseph also is not recommending them.
"They're probably on a spectrum between no tobacco at all and combustible cigarettes, and we just don't know where on that span they're going to land," she said.
E-cigarettes could bring smoking back into vogue, Joseph cautioned. Because cigarettes are now banned in almost all buildings now, people don't see them as much. She said she worries e-cigarettes could bring nicotine use back into the public sphere.
The state Legislature recently banned e-cigarettes in government buildings and public universities, and made them illegal to sell to minors.
Whatever the concerns, e-cigarettes are a better alternative to smoking, said Cap O'Rourke, a lobbyist for e-cigarette retailers in the state.
"I think this is really about a harm reduction strategy. And any product we can get that is giving people an alternative to cigarettes" is good for public health, O'Rourke said.
Dr. Richard Hurt at the Mayo Clinic's nicotine dependence center says he fields a lot of questions about e-cigarettes from smokers desperate to quit.
But he believes e-cigarettes may create a new problem that looks like addiction.
"What we have now begun to see are people that have switched to e-cigarettes from some other tobacco product who now want to stop e-cigarettes," Hurt said.
"We are kind of stuck in limbo because we don't have very good evidence about how to treat that," he added. "So we're treating it basically like we would a smoker."