A man smokes a Philip Morris IQOS electronic cigarette in Tokyo. (Akio Kon/Bloomberg News)

The Food and Drug Administration cleared Philip Morris International’s IQOS — a heat-not-burn tobacco device designed as an alternative to conventional cigarettes — for sale in the United States.

The product consists of a tube that gently heats up sticks of tobacco instead of burning them, making what’s inhaled less harmful than conventional cigarette smoke. Philip Morris has made the device a key part of its plans for growth. The device is already sold in dozens of other countries with varying success, but it has triggered debate among U.S. health experts over whether IQOS would help or hurt overall public health.

The FDA, in announcing the decision, said the marketing of the devices is “appropriate” for public health because “the products produce fewer or lower levels of some toxins than combustible cigarettes.” The agency also said it has placed stringent marketing restrictions on the products in an effort to prevent minors from using the device.

Health experts worry the device could attract minors and people who did not previously smoke, or that current smokers may adopt the device without giving up their smoking, exacerbating their health risks from tobacco rather than improving them.

An estimated 14 percent of adults in the United States, or 34 million adults, smoke cigarettes. And smoking remains the country’s leading cause of preventable disease and death, accounting for about 1 in 5 deaths every year. Companies and some experts have pushed devices like IQOS as possible alternatives to help bring down those rates. At the same time, the country’s tobacco use rates are at historic lows, and health experts worry new nicotine and tobacco product could slow the downward trend or even reverse it.

On Tuesday, the FDA pointed out that while IQOS has been cleared for sale, it has not been officially “approved” by the agency. That’s because all tobacco products are potentially harmful and addictive, and people who do not use them should not start, the agency said.

Mitch Zeller, director of the FDA’s Center for Tobacco Products, said the IQOS review, which took almost two years, took into consideration the risks and benefits to the population as a whole. “This includes how the products may impact youth use of nicotine and tobacco, and the potential for the products to completely move adult smokers away from use of combustible cigarettes,” he said.

The FDA said that because IQOS delivers nicotine levels close to those in conventional cigarettes, users of the device may be able to completely switch from those cigarettes to IQOS.

The agency has not made a decision yet on a separate application by the company to market the product by claiming that it is less harmful than other tobacco products or that it would reduce the risk of disease.

Philip Morris chief executive André Calantzopoulos called Tuesday’s announcement “an important step,” especially for those who have struggled to quit smoking. “For them IQOS offers a smoke-free alternative to continued smoking,” he said.

Philip Morris is the manufacturer of the device and heat sticks, but Altria will sell and market them in the United States. In a statement, Altria said it intends to introduce IQOS first in Atlanta “to learn as much as possible, as quickly as possible” about how it may perform in the U.S. market.

While the product is a “heat-not-burn” device, it meets the technical definition of a cigarette under the federal Food, Drug and Cosmetic Act. Thus, Philip Morris and Altria will be barred from advertising the device on television and radio. In addition, the FDA said, it is placing restrictions on how the product is marketed on websites and social media platforms.

As smoking in the United States has dropped to all-time lows, Philip Morris has made huge investments in IQOS and other smokeless tobacco products, spending $3 billion to develop them.

By using heat instead of flame, Philip Morris says, IQOS eliminates 90 to 95 percent of toxic compounds in cigarette smoke.

FDA’s announcement on Tuesday is sure to generate fierce debate in coming months.

“People opposed to it will point out rightly that it’s not safe. People on the other side will point out that it’s less harmful than smoking and could be a good alternative,” said Michael Eriksen, a former Centers for Disease Control official and tobacco expert at Georgia State University. “The linchpin is whether these devices actually lead people to stop smoking.”

Studies in other countries have shown mixed results, with some smokers who try alternatives — such as vaping or heated tobacco — adopting them in addition to conventional smoking.

“If people in the U.S. end up using devices like this in addition to smoking, it would have been better for them to have never bought it at all,” Eriksen said.

With IQOS now cleared for U.S. sales, the fierce debate over IQOS will shift to how it is marketed. An advisory FDA panel last year rejected claims by Philip Morris that IQOS reduces the risk and harm of smoking.

The panel agreed with the company's claim that its smokeless cigarette reduces smokers’ exposure to harmful toxins but said the company had not proved conclusively that that would result in less harm and disease overall.

How the FDA rules on the marketing could influence how successful the device becomes nationwide. If the FDA approves the company’s marketing application, IQOS would be the first tobacco product to carry the U.S. government’s stamp as a less harmful alternative to cigarettes — a marketing coup for Philip Morris.

“Fewer toxins does not mean safe,” said Erika Sward, assistant vice president of national advocacy for the American Lung Association. Her association has expressed concerns about the short-term and long-term impact of IQOS on lung health and also questioned “whether it will further discourage current smokers from ending their addiction altogether.” To reduce their risk of disease, she said, smokers should quit all types of tobacco products.

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