The Minnesota Senate voted Thursday to bring the use of electronic cigarettes — known as "vaping" — under the same public space restrictions that apply to tobacco.

The bill now heads for a showdown with a less restrictive House version passed earlier this week that would ban vaping only at state buildings and public schools. While support for banning the sale of the devices to minors has garnered near-universal support, lawmakers are divided on whether to ban indoor use when the effects of vaping are still being studied.

"I'm going to work very hard to make certain that the bill stays whole," said the measure's sponsor, Sen. Kathy Sheran, DFL-Mankato, moments after the proposal passed 48-17 as part of the Senate's Health and Human Services Omnibus bill. Sheran noted that despite earlier reservations, Gov. Mark Dayton has agreed to sign the bill if it arrives at his desk.

"I've been successful in the Senate in persuading my colleagues to support this and I hope to now carry that over and persuade the House," she said.

The debate surrounding state regulation of electronic cigarettes is likely to be watched closely as a primer on how to handle a booming industry with a still somewhat mysterious product.

In the past year, 80 percent of Minnesota's 200 e-cigarette retailers have set up shop in kiosks and brick-and-mortar stores, garnering gratitude from users who say the devices are a safe alternative for those trying to quit smoking. But the devices, which can contain nicotine laced with various flavors that emit a vapor rather than smoke, concern some who say little is known about what chemicals secondhand vapors contain, and whether they're harmful.

"Six months ago most people didn't know what an e-cigarette was," said Rep. Laurie Halverson, DFL-Eagan, the House bill's sponsor. Halvorson removed the Senate language from her bill that would have placed e-cigarettes under the state's Clean Indoor Air Act, as a way to gain votes. Her version passed 86-46 as part of the House Health and Human Services Omnibus bill.

Halverson said she has seen a shift, with lawmakers changing their minds on the devices they once considered benign.

"I've had people who have gone from 'I think these [devices] are a good idea' to 'I'm with you 100 percent,' " she said.

However, on the Senate floor Thursday, opponents of the measure maintained that there is no research proving that secondhand vapors are harmful.

"At least with smoking you can argue there is a demonstrable secondary impact, that it hurts people," said Sen. Sean Nienow, R-Cambridge. "There is nothing anybody can point to that this electronic cigarette vapor hurts the guy two chairs down."

"I'm not willing to wait until proof of harm on something," countered Sen. Vicki Jensen, DFL-Owatonna. "Let's wait for proof it's OK."

The tobacco industry for decades fought any link between its product and cancer, contending that the research was inconclusive.

Last month, the federal Food and Drug Administration proposed regulations extending the agency's tobacco authority to e-cigarettes, warning that the devices haven't been fully studied. Halverson said the FDA isn't the only industry keeping a close eye on Minnesota's proceedings.

"We always pay attention when tobacco companies send lobbyists in from Washington, D.C.," she said. "You can certainly see this is a big investment."

Abby Simons • 651-925-5043