The U.S. Food and Drug Administration (FDA) proposed the first potential federal regulations for the $2 billion e-cigarette industry on Thursday, Reuters reports.

The new rules would ban e-cigarette sales to minors, and manufacturers of such products would have to disclose the e-cigarette ingredients to the FDA.

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Furthermore, the new rules would prohibit companies from handing out free e-cigarette samples, as well as selling e-cigarette products through vending machines (except in adult-only venues). Manufacturers would also have to place health warnings on e-cigarette products that say nicotine is addictive, though they would have two years to do so if the regulation is made official.

However, the FDA did not propose limiting advertising, flavored products or online sales — all things that e-cigarette critics deem important to keep these products away from kids.

"Without swift action from the administration to finalize the rule and take the necessary regulatory steps, many manufacturers of these products can continue to engage in practices, such as advertising and use of flavors, which make them attractive and accessible to youth," said American Cancer Society's Cancer Action Network CEO, Dr. John Seffrin.

In the absence of federal restrictions, major cities such as New York, Chicago and Los Angeles have severely restricted e-cigarette use in recent months. In New York City, for example, anyone "vaping" an e-cigarette will soon only be allowed to do so in the privacy of their own home or in designated smoking areas.

E-cigarette smoking or "vaping" simulates tobacco smoking by vaporizing a liquid solution. The vapor is flavored and can contain nicotine; the health benefits or risks of e-cigarettes are still a subject of debate.

Though there is no definitive study on the safety of e-cigarettes, one study published in The Lancet showed that those who use the electronic products are not much more likely to quit smoking than anyone who uses a nicotine patch. The finding runs counter to many claims made by e-cigarette proponents, who say vaping helps people wean off of smoking.

The FDA proposal "lays the foundation" for other actions and activities, FDA Commissioner Margaret Hamburg told NBC News. “We want to move as quickly as we can but it is a process and it will take time."

After a public-comment period of 75 days, and after the proposed rules are finalized, manufacturers will have 24 months to submit an application for their products to remain on the market.

“We don’t know as much about the safety and risks of e-cigarettes and that is why we want to be able to regulate them,” said Hamburg.