Last week, the Food and Drug Administration for the first time proposed rules for regulating e-cigarettes, including prohibiting sales to minors and requiring producers to register with the agency and disclose manufacturing processes.

But many crucial questions still fall to the states. Should there be indoor vaping bans, for example, or excise taxes? The F.D.A., in its release on Thursday, didn’t address marketing or whether to ban flavorings, which some critics say appeal to children. State-imposed limits played a big role in reducing traditional cigarette use, and health officials said states could play a similar role this time, pulling back the reins on e-cigarettes until more is known about their potential hazards.

For instance, some studies show carcinogens in the vapor, particularly in a new generation of more powerful e-cigarettes. Liquid nicotine is toxic and it can be absorbed into the skin. Public health officials shudder when they hear about people like Mr. Whitson, who mixes the e-juice without gloves — and just a few feet from a crib where his 4-month-old daughter sometimes sleeps. (He says that he’s careful and that the company uses only “food-grade products that are kosher.”)

Oklahoma has already taken a few steps. Gov. Mary Fallin has prohibited vaping on state property, and last week signed a law prohibiting sales to minors. Some 18 percent of Oklahoma high-school students have experimented with vaping, nearly double the national average. While the F.D.A. rules would also prevent those teenagers from buying e-cigarettes, they are now just proposals.

The prospect of further regulation troubles many small-business people here, including Sean Gore, a former rodeo cowboy and recovered meth addict turned consultant to the oil and gas industry, who has become a leader in the state’s vaping industry. On May 1, he plans to open his third vape shop in the Oklahoma City area, and he also serves as chairman of the state industry lobbying group, the Oklahoma Vapor Advocacy League. He welcomes regulations like outlawing sales to minors. But others worry him, like product regulation, which he fears could subject even small vape shops that make their own products and mix their own liquids to federal oversight. That might be costly to the shops, which he views as the right-spirited pioneers of the e-cigarette boom.

He also opposes state action to raise taxes, limit marketing or ban vaping indoors. More rules, he fears, would work only to benefit deep-pocketed tobacco companies that have also entered the $2 billion e-cigarette industry. Regulation, he said, will take “a product that has the potential to save thousands of lives and give it back to the industry that’s killing people.”

Most galling to him are rules that prohibit e-cigarette makers from claiming, without providing scientific evidence, that their products are safer than cigarettes. “It doesn’t take a rocket scientist to figure out these products are much safer than cancer sticks,” he said. While health officials drag their feet, Mr. Gore asked, “How many more people have to die?”