Advertising for traditional cigarettes is strictly regulated: No cowboys looking cool, no cartoons and no bright colors that play up candy-flavored cigarettes that might appeal to kids.

Yet these bans don’t apply to e-cigarettes or vapes — increasingly a choice for experimentation by adolescents and young adults. These smoking products use chemical solutions with nicotine flavored with “juices” that have names like “Bubble Pop,” “Strawberry Cotton Candy” and “Peanut Butter Cup.” People inhale these as if they were smoking a traditional cigarette.

Young adults who are exposed to advertisements for these non-cigarette tobacco products are significantly more likely to try them, according to a study of nearly 11,000 people ages 12 to 24 published Monday in JAMA.

Anti-smoking advocates battled for decades against the tobacco industry’s cigarette-marketing strategy geared to young people. What many viewed as “first-step” restrictions on traditional “combustible” cigarettes were advanced as part of the 2001 tobacco Master Settlement Agreement between state attorneys general and the industry. But many worry that gaps still exist.

“Our study reinforces that tobacco product marketing continues to be an important contributor to tobacco use among young people,” wrote the study authors.

Thirty-six percent of 12- to 17-year-olds who had never used tobacco but were receptive to ads ended up trying e-cigs by the end of the study.

Study participants were selected because they answered survey questions that indicated they were at low risk of using tobacco. They said they had never touched tobacco and “definitely” would not in the next year.

But almost 5 percent of them tried smoking e-cigarettes for the first time over the next 12 months, saying the ads for these particular products appealed to them more than ads for regular cigarette ads.

That translates to 224,000 new smokers a year, according to John Pierce, the lead researcher and a professor in the Department of Family Medicine and Public Health at University of California-San Diego Cancer Center.

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“If that happens every year, we’re going to have a huge problem with cigarettes again,” Pierce said.

During the past 10 years, a “dramatic shift” has occurred in the tobacco product marketplace, with e-cigarettes, hookah tobacco water pipes and small cigars gaining significant heft in sales — especially among this young population, noted an editorial that accompanied the study by Adam Leventhal and Jessica Barrington-Trimis of the University of Southern California’s Keck School of Medicine.

Sabina Rasoulov, 21, said she mostly sees people vaping on social media like Snapchat, and sees it as an easy alternative to cigarettes. She was not part of the study.

She also said, though, that her vaping habits have less to do with ads and more to do with her peers.

Rasoulov, a senior at the University of Maryland, occasionally uses a Juul, a brand of e-cigarette, mostly when she’s drinking. The floor of the bar near campus where she works becomes littered with them by the end of the night.

“When I work in the bar, every person has it in their hand,” Rasoulov said. “It’s like the new fidget spinner.”

The researchers compiled a copy of every ad for cigarettes, vapes and e-cigs for a year in 2013.

One of the study’s limitations, though, is it did not include online or social media marketing ad images.

The reserachers randomly assigned each person 20 ads and asked if they had seen each one and if they liked it. Those two questions determined how “receptive” each person was to the different kinds of ads.

One 15-year-old freshman from Bethlehem, N.Y., said he has vaped for almost a year. He said his parents know he vapes and disapprove. He also said a lot of his friends use vapes. He was not involved in the study.

He sees a lot of ads for vapes online and on billboards but doesn’t think the advertising makes much of a difference.

Still, he said, “it’s a constant reminder that it’s something out there for you to do.”

The study found that two-thirds of 18- to 21-year-olds and 44 percent of 12- to 14-year-olds were receptive to the ads. This finding was one of the alarms raised by researchers.

“If they’re only advertising to people who can buy the products,” said Pierce, then the ads shouldn’t be finding such traction among “almost half of the people [in the study] under the age of 18.” The odds, according to the study, were 60 percent higher that young people who were receptive to the ads would try e-cigarettes or vapes within a year.

That receptivity peaks around 21 years old, the age by which most tobacco users try tobacco for the first time.

Pierce and his team wanted to learn how much of that was because of advertising for e-cigarettes, which is unregulated.

Until now, there’s been “little evidence” on the degree to which advertising for these types of non-cigarette tobacco products plays a role in whether and when the adolescent and young adult market begins using them, wrote Leventhal and Barrington-Trimis in the editorial, making the findings “important for policy and prevention.”

Anti-smoking advocates have also been focused for a long time on the notion that e-cig use can be a gateway to traditional cigarette smoking. And the ads again draw scrutiny. Pierce points to early e-cigarette ads, which featured celebrities smoking e-cigs in chic locations.

“The only way you can tell it’s vaping and not cigarette smoking is because it has a blue tip on it,” Pierce said. “It’s straight up the old cigarette ads.”

But the 15-year-old high schooler drew a clear line between vaping and traditional cigarette use.

His grandfather died of lung cancer, he said, and he and his friends grew up seeing anti-cigarette ads on TV and considers this to be different.

“Vaping comes in a wide variety of flavors,” he said, noting that his choice is mint. “Cigarettes, I’ve heard, are just disgusting.”

He said seniors at his high school buy vaping supplies for underclassmen to get around the age restriction, and it’s not the nicotine that keeps him vaping.

“It’s the sleek design,” he said. “It just kind of becomes a part of you when you carry it around all the time.”

There’s another key advantage: Adults can also use e-cigarettes and vapes in places where traditional cigarettes aren’t allowed.

“There’s no question that there’s more social acceptability at the moment,” Pierce said.

And Rasoulov confirmed this idea.

“I just perceive it as an indoor cigarette,” she said. “It’s convenient. I don’t need to go outside, and it doesn’t smell at all.”

And this perception?

“We would argue a lot of that is because of the advertising,” Pierce said.

KHN’s coverage of children’s health care issues is supported in part by the Heising-Simons Foundation.