When Emma DePape cautions her classmates that their habit of puffing on trendy, fruit-flavored electronic cigarettes exposes them to more nicotine than a pack of regular cigarettes, she’s usually brushed off.

Vaping, they tell her, is less dangerous than smoking. Plus, it seems like everybody’s doing it: in school bathrooms and parking lots, in posts on Instagram, in their bedrooms at home at night, their parents none the wiser.

“Anytime I mention [the risks] to a person I know who vapes, they say they don’t care, don’t worry about it, you’re not going to make me stop,” said DePape, a senior at Hopkins High School.

As the U.S. Food and Drug Administration launches an unprecedented crackdown on the manufacturers and sellers of e-cigarettes to slow what it calls an “epidemic” of teen vaping, schools across Minnesota are waging their own battles against the trend.

Some administrators and school staff members concede they’ve been caught off guard by the surging popularity of e-cigarettes, particularly because it follows a decadeslong drop in teen smoking. But with 19 percent of high school students reporting that they’d used vaping devices in a 2017 state Department of Health survey — a number many in schools expect to go up this year — school officials are now paying close attention.

At Hopkins High School, administrators and Hennepin County public health workers held a student listening session last year to learn more about the prevalence of e-cigarette use in and around the school, and why so many students were willing to try it. Cathy Rude, a community health specialist with Hennepin County, said many users are misinformed — or uninformed — about the health hazards of vaping.

E-cigarettes are battery operated and filled with liquid that typically contains nicotine and a variety of other chemicals. The devices are marketed as a way to help people addicted to traditional tobacco products break the habit, and Rude said many teens believe that makes them a safe alternative to smoking.

The reality, however, is that many e-cigarettes contain considerable amounts of nicotine and produce a vapor that may include unsafe levels of heavy metals. It’s also often unclear exactly what chemicals are in the e-liquid, because it is not regulated by the government.

“A lot of kids think it’s water and it can’t hurt them,” Rude said.

Meanwhile, the e-liquid comes in a range of flavors with big appeal among teens, such as blue raspberry, s’mores, cookies and cream, and even one designed to taste like Sour Patch Kids candy. One of the most popular vaping devices, the flash-drive-sized Juul, can be lit up with a rainbow of colors in what users call “party mode.”

The FDA recently gave e-cigarette manufacturers 60 days to prove they could keep the devices from underage users and threatened to pull flavored varieties off the market if they fail at that task.

As vaping as grown in popularity, controversy over it has also intensified. In June, San Francisco voters backed a ban on the selling of favored tobacco products, including vaping liquids. The measure, which passed despite an expensive advertising campaign funded by R.J. Reynolds Tobacco Co., is the most restrictive in the nation.

Lexi Stephenson, a senior at Hopkins High, said she frequently sees images popping up in her social media feeds promoting vaping for aromatherapy. No matter what piques their interest, Stephenson said, many teens get hooked — and even start seeking out other ways to get their nicotine fix.

“I feel like vaping leads to cigarettes for a lot of people,” she said.

That possibility has many health officials, school administrators and some students, including Stephenson and DePape, alarmed. Both students are members of Hopkins’ Student Wellness Committee, which has recently been focusing some of its activity on educating students about vaping. The group has put together a public-service poster campaign, which they hope will end up in schools across the state.

Some of the group’s members have taken an active role in trying to get local laws about tobacco sales changed, including in Minnetonka, where the city is considering raising the sales age to 21. For now, students in the group said it’s easy for their peers to get e-cigarettes at any age, buying them from older peers or even going online and ordering them directly. A Juul device sells for $34.95 on the company’s website, while a pack of four flavored Juul “pods” goes for $15.99.

School officials said students are also increasingly flaunting their e-cigarette use on social media — a risk because it’s evidence of behavior in violation of school honor codes and statewide rules for participating in athletics.

Kathryn Bennett, dean of students at Wayzata High School, said school officials find students vaping on campus on a weekly basis — though few students are caught multiple times. If a student is caught with an e-cigarette, administrators call a meeting with the student, his or her parents and a chemical health specialist and try to come up with a plan to help the student stop vaping.

Bennett said it’s important that parents know the trend is widespread, cutting across students of all backgrounds and interests. The district has begun hosting information sessions for parents to bring them up to speed about how to spot the devices and why they should be concerned about their children using them.

“Our biggest message is: Always have an eye open,” she said.

Rude, with Hennepin County, said all of the schools in the county have updated their tobacco policies to include e-cigarettes, and many have added to their health class curriculum to add more information for students. But some are having a harder time than others in slowing the popularity of the devices among their students.

“They’re seeing more of it, and I don’t know if they have the staff and resources to chase it all down,” she said. “They do their best.”