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The feds are coming for your crème brûlée. In an announcement scheduled for next week, the Food and Drug Administration is expected to roll out new restrictions on the sale of e-cigarette and vaping products, according to The Washington Post. The reported changes will be an aggressive next step in the agency’s ongoing effort to curb vaping’s explosive popularity with American teens, and they’ll remove many super-popular flavored products from a majority of the brick-and-mortar locations where they’re currently sold in the United States.

Before vapers start hoarding their preferred pods, though, consider that the changes are complicated, to put it mildly. The restrictions, which a spokesperson for the FDA would not confirm, will reportedly apply to the closed-pod systems particularly popular among teens, but not to refillable tank vapes. The ban will affect flavored products, except for mint and menthol, because those flavors are also widely available in conventional cigarettes. The flavored pods will be removed from convenience stores and gas stations, but big-box stores and grocery stores seem to still be able to sell them, in addition to vape and tobacco shops.

The incredible specificity of these new rules is a way for the FDA to balance vaping’s potential harm to teens with the need to make safer cigarette alternatives available for people who already smoke. It’s an intricate, complicated maneuver aimed at protecting two separate groups whose best interests are at odds. Essentially, the FDA is trying to use federal law to solve a mango-flavored trolley problem.

At the heart of the controversial rise of teen vapers is Juul Labs, a California-based company whose exponential growth in recent years has given it a 73 percent market share in the $2.5 billion American e-cigarette market. Like cigarettes, vapes draw their nicotine from tobacco, but instead of lighting up, users get their hit from a liquid sold in both closed pods and refillable tanks, depending on which brand’s system they choose. That liquid is then heated, creating the vapor that gives the product category its name.

Juul has sold millions of its ultra-popular vapes, which use a closed-pod system. The only way to use one is to buy its refills, which have been available both in stores and online. The pods come in tobacco-flavored versions and ones with additives that create sweet or fruity flavors, which have been a particular target of critical ire for their potential appeal to underage vapers. But on Friday, CNBC reported that in response to the FDA’s expected changes, Juul will soon announce plans to voluntarily remove all of its flavored products from most brick-and-mortar stores. It’s unclear if that includes vape and tobacco shops. (The company declined a request for comment.)

Since its 2015 launch, Juul has been an object of particular fascination among teens. At first, the company’s ads had a far brighter, more youthful feel. Now, as an apparent concession to regulators and critics, its ads feature only people over age 35 who have actually quit cigarettes by vaping. Despite the change in advertising demographics, the brand’s small, slender vapes look like flash drives and charge via USB, which makes them ultra-portable and, for teens, easy to conceal from parents and teachers.

Vape juice (its actual name!) contains tobacco derivatives, so its sale is legally restricted to people age 18 and over. Juul’s website verifies a shopper’s age during account creation. According to experts, though, that isn’t enough to keep the product out of teens’ hands. Bonnie Halpern-Felsher, a developmental psychologist and professor of pediatrics at Stanford University, says that teens vapers’ first stop isn’t at stores. “The majority of youth get their products from each other, and second from smoke or vape shops. Youth are not getting them from convenience stores,” she says.

Because of the lucrative black market in teen social circles, even if the products are removed from most brick-and-mortar locations, it would only take an enterprising underage teen with a helpful older sibling (or simply an 18-year-old high-school senior) to keep a whole school stocked up on Juul pods. Moreover, Halpern-Felsher says her recent research indicates teens like the mint and menthol options—the ones the FDA will reportedly allow to remain widely available in stores—just as much as the fruitier flavors. “We need to ban flavors across the board, in all areas of sales,” Halpern-Felsher says. “This is a good first step, but it’s not enough.”

Chyke Doubeni, a professor of family medicine and community health at the University of Pennsylvania, echoed Halpern-Felsher’s call for further availability restrictions. “It is crucial to reduce the ease with which these products can be obtained,” he says. Doubeni’s past research has shown that when young people perceive tobacco products as readily available, they’re more likely to use them.

Despite vaping’s cultural reputation as a bad habit for misbehaving teens, its defenders are concerned about overregulation for completely different public-health reasons. Greg Conley, the president of the American Vaping Association, agrees with Halpern-Felsher that teens often buy vape products from one another, but he instead sees that as a reason not to bother regulating the products out of convenience stores. “This reported move by FDA Commissioner [Scott] Gottlieb will only make it harder for adult smokers to switch to a far less harmful alternative,” he told me. “Not every town has a vape shop, which means for many smokers, it’ll be easier to pick up a pack of Marlboros or Camels.”

Although unflavored vape products would still be widely available in stores under the new FDA restrictions, Conley says that’s not enough for current smokers to get the maximum health benefits. Halpern-Felsher is less convinced by that argument. “Gottlieb keeps saying we need flavors to help adults quit, but there’s no evidence that flavors help adults quit smoking cigarettes,” she says.

These competing concerns leave the FDA trying to thread a particularly tricky needle: How do they get these products into the hands of the people who need them, while keeping them away from people who don’t already smoke? Vaping in general does show promise as a diversion product, even for hard-core smokers, a group of people who historically have a very hard time quitting a very dangerous habit. Because of the relative novelty of e-cigarettes, there’s no long-term data on what kind of health impacts vaping might have (and there’s little consumer transparency about what’s actually in vape juice), but medical professionals are generally doubtful that it could be worse for active smokers than continuing to smoke.

The vaping industry is in a unique spot. It can’t market its products as explicitly intended for smoking cessation, because that would open manufacturers up to the more stringent FDA regulations for medical devices instead of those for tobacco products. It also can’t market its products as a recreational option to the demographic that seems most eager to adopt them, because it’s illegal to sell tobacco to teens.

So now the FDA must try and steer the trolley that’s barreling toward an increasing number of consumers. Because vaping started out as recreational (and because cigarettes, a much more harmful recreational product, show no signs of ever being banned), it seems unlikely that regulators will push the vape industry onto an explicitly medicalized path anytime soon. And if e-cigarettes remain a consumer product, at least some teenagers are likely to get swept up by their USB-powered gleam. Moderate restrictions can reduce potential harm, but they can’t completely stop the teen entrepreneur in fourth period.

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