(CNN) -- The Food and Drug Administration is making another attempt at regulating electronic cigarettes and other tobacco products.
On Thursday, the agency proposed rules that call for strict regulation of electronic cigarettes, cigars, pipe tobacco, nicotine gels, water pipe tobacco and hookahs. Currently, the FDA only has regulatory authority over cigarettes, smokeless tobacco and roll-your-own tobacco.
When these recommendations are finalized following a 75-day public comment period, the age limit to buy the products is expected to be at least 18, although individual states could choose to set it higher.
Health warnings would also be required and the sale of the products in vending machines would be prohibited. Initially, the only health warning required for e-cigarettes would be about the potential for addiction to nicotine.
Manufacturers would be required to register all their products and ingredients with the FDA. They would only be able to market new products after an FDA review, and they would need to provide scientific evidence before making any claims of direct or implied risk reduction associated with their product.
Companies would also no longer be allowed to give out free samples.
After the public comment period and once the proposed rules are finalized, manufacturers will have 24 months to submit an application to allow their products to remain on the market or submit a new product application.
E-cigarettes deliver nicotine to the user as a vapor. They are usually battery-operated and come with a replaceable cartridge that contains liquid nicotine. When heated, the liquid in the cartridge turns into a vapor that's inhaled.
Most look like cigarettes, cigars or pipes, but some resemble pens or USB memory sticks. Because they have not been fully studied, the FDA says it's unknown what health risks they pose, how much nicotine or other chemicals are actually being inhaled or whether there is any benefit to using them.
Last year, the Centers for Disease Control and Prevention reported that the percentage of high school students who reported ever using an e-cigarette more than doubled in one year, from 4.7% to 10% between 2011 and 2012.
As electronic cigarettes have increased in popularity, so have the number of calls to poison control centers nationwide. According to a recent CDC report, poison control centers logged 215 calls involving e-cigarettes in February alone. Of those calls, 51% involved children.
"It's really the wild, wild west out there," says Margaret Hamburg, FDA commissioner. "Because e-cigarettes are increasingly in the marketplace. They're coming in different sizes, shapes and flavors in terms of the nicotine in them, and there's very worrisome data that show that young people in particular are starting to take up e-cigarettes, especially the flavored ones and that might be a gateway to other harmful tobacco products."
Hamburg says they don't know how many types are on the market, another reason why regulation is critical.
"We're already conducting research and working with partners in the research community to better understand patterns of use of these e-cigarettes and to learn more about the way in which they work and the delivery of the nicotine through e-cigarettes. But until we can really regulate them, we can't have all the information we need and we can't take all the actions that we might want to to be able to best address the public health issues associated with them."
Nicotine is a drug and poison experts say the concentrated liquid form used in e-cigarettes is highly toxic even in small doses. It can be inhaled or absorbed through the skin.
"Responsibly marketed and properly regulated, it is possible that e-cigarettes could benefit public health if they help significantly reduce the number of people who use conventional cigarettes and die of tobacco-related disease," Matthew Myers, president of Campaign for Tobacco-Free Kids, said in February.
But a lot of unanswered questions remain, according to Dr. Michael Eriksen, dean of the School of Public Health at Georgia State University, one of 14 U.S. institutions conducting FDA-funded research on electronic cigarettes,
"How concentrated is liquid nicotine? Are there impurities in it? Is it properly handled like a pesticide?" he says. "Nicotine is a pesticide fundamentally and we take so many precautions about pesticides for our lawns and how to wear gloves. But what precautions do consumers take when they put the nicotine vials in? People treat it [liquid nicotine] as sugar when it's a toxin."
Harold Wimmer, president and CEO of the American Lung Association, believes nicotine is highly addictive whether used in a regular cigarette or an e-cigarette.
So how safe are e-cigarettes? Hamburg says it's buyer beware.
"We think that there's a lot of information that needs to be understood about e-cigarettes and their use. We're trying to help provide some of that information through research that we're conducting," she says.
"But we need the tools that regulation provides to be able to get critical new knowledge about e-cigarettes and to be able to put in place a framework that will protect the American public and potentially e-cigarette users, and really address the issues of what are the health consequences and what are the potential benefits."
Hamburg believes these new rules will change the landscape.
If the FDA broadens its authority to regulate tobacco products, she says, it will make a major contribution to the health of Americans.