ST. PETERSBURG — Tyler Davis took a long drag on his e-cigarette and contemplated the sweet flavor that filled his lungs.
"It tastes like Froot Loops," the 19-year-old said, sounding like a wine connoisseur identifying the notes in a fine Cabernet Sauvignon. "Or Lucky Charms."
Davis makes weekly visits to City Vapor and E-Cig in St. Petersburg to sample the latest flavors of liquid nicotine. He vapes partly because of the low cost and partly because of the variety of flavors.
"There are endless possibilities," he said after trying another flavor called Doc's Custard that reminded him of graham crackers.
But changes are coming to the fast-growing industry. The Food and Drug Administration is considering a slate of new regulations that could put smaller liquid nicotine distributors out of business and have a ripple effect on Tampa Bay area vape shops.
"We're trying to keep up with it all," said Todd Evans, who owns City Vapor and E-Cig.
E-cigarettes are battery-operated gadgets that heat up liquid nicotine — known as "e-liquid" among enthusiasts — producing a flavorful vapor for users to inhale. Some devices look like traditional cigarettes. Others come in bright colors or metallic finishes.
Advocates say electronic smokes are less harmful than traditional ones because users do not inhale carcinogen-filled smoke. But little is known about the long-term effect of vaping or liquid nicotine.
"Public health researchers are really playing catch-up with the explosion of e-cigarettes onto the marketplace," said Thomas Brandon, director of the Tobacco Research and Intervention Program at Tampa's Moffitt Cancer Center, which recently received a $3.6 million grant from the National Institutes of Health to study e-cigarette use.
One thing is clear: E-cigarettes are becoming more popular, and not just among former cigarette smokers. The National Youth Tobacco Survey found e-cigarette use among high school students jumped from 4.5 percent in 2013 to 13.4 percent in 2014.
Last year, Florida lawmakers passed a law prohibiting the sale of e-cigarettes to minors.
The FDA, however, has been slower to act. The agency proposed a rule in early 2014 that would allow it to regulate e-cigarettes like tobacco products. But the rule has yet to be finalized.
"There are a lot of critics who feel (the FDA) has moved much more slowly than it should have to bring about some sort of regulatory parity between tobacco and liquid nicotine," said Richard Blau, a Tampa lawyer and chair of GrayRobinson's Alcohol Beverage and Food Law Department.
The FDA inched forward in late June, issuing a call for data, research and comments about liquid nicotine to "help the agency make the best decisions about possible regulatory actions."
FDA officials said the move was inspired by an increase in calls to poison control centers related to liquid nicotine poisoning. (More than half of calls involved small children ingesting the liquid or absorbing it through their eyes or skin, according to the Centers for Disease Control and Prevention.)
The comment period runs through Aug. 31.
The FDA hasn't said exactly what kind of proposed regulations could be coming for liquid nicotine. But the agency has expressed interest in exploring whether it should be sold in childproof packaging or accompanied by a warning label.
Florida Surgeon General John Armstrong has already voiced his support for both measures.
"Warning labels on e-cigarettes and other nicotine delivery devices, which are currently unregulated, would be an important step in educating the public about the dangers of nicotine addiction, the fundamental reason individuals persist in using tobacco products," Armstrong wrote in a July 22 statement.
Those regulations wouldn't bother Alycia Singleton, the operations manager at St. Petersburg's Vapor Vault.
"I think it's a necessity," she said. "Every once in a while, you get some e-liquid in your mouth. That's not an issue. But when you have young children who smell the flavors and want to drink it, you do have to make (the package) childproof."
Singleton's shop is already making adjustments in anticipation of the potential regulations. Most of the liquid nicotine she sells comes in childproof bottles, she said.
E-liquid companies like Pasco-based Power House Vapors also are responding. Co-founder Matt Palancia said he is working to change the packaging for his products, which come in flavors like creamy blueberry cheesecake and pomegranate-French vanilla.
"We're making moves pretty quickly," Palancia said.
But Palancia conceded the potential regulations could drive up costs for some smaller e-liquid companies, potentially putting them out of business. And that could mean fewer choices for consumers.
The FDA also could move forward with tougher regulations involving advertising practices — or even a requirement that companies only market new tobacco products after FDA review, as was considered in the agency's 2014 proposal. Analysts say a measure like that would deliver a blow to the smaller players in the industry.
Evans, who runs City Vapor and E-Cig, said he will be watching closely.
"The plan is to stay one step ahead," he said.
Contact Kathleen McGrory at firstname.lastname@example.org or (727) 893-8330. Follow @kmcgrory.