A proposal to regulate the emerging e-cigarette industry, including a prohibition on using the products indoors, is headed for a vote by the full state Senate.

The Senate Commerce Committee approved the bill on Monday. The committee also voted down an amendment that would have allowed private businesses to continue to allow use of e-cigarettes, or "vaping," indoors on their property.

That provision has been heavily criticized by e-cigarette store owners and industry lobbyists, and it has been removed from a companion bill in the House. If the House and Senate approve differing versions of the bill, differences would have to be reconciled in a conference committee.

E-cigarette advocates say they offer a way to use nicotine that's not as unhealthy as cigarettes, and that the product has helped many smokers quit. The indoor ban's supporters say there are still many unknowns about possible health consequences of the vapors created by e-cigarettes.

"The risk inherent is unclear. It is not proven to be safe," said the ban's Senate sponsor, Sen. Kathy Sheran of Duluth.

Jesse Griffith owns Smokeless Smoking, an e-cigarette store in Woodbury. He said most in the industry don't oppose the bill's other main provision, to ban the sale of e-cigarettes to minors. But he said the indoor ban would have a negative effect on about 200 e-cigarette retailers, about 80 percent of whom have popped up in the last year.

"It will make it harder for businesses like our to survive," Griffith said. He argued that restricting the use of e-cigarettes could result in some former cigarette smokers lapsing back into the habit.

But Sen. Ron Latz, DFL-St. Louis Park, said there's not enough known about possible health ramifications for lawmakers to exempt vaping from Minnesota's Freedom to Breathe Act, which bans indoor smoking.

"If you workin a hotel, restaurant, bar or VFW, I'm not sure you want to be forced to choose between keeping your job and being exposed to some unknown array of chemicals being released into the atmosphere," Latz said.