Teenagers have found a new way to worry their parents. Never mind plain old vaping — now, it’s all about dripping.

The term refers to the practice of applying nicotine liquid directly to the heated coils of an e-cigarette or other vaporizer to produce thick clouds of nicotine vapor.

A new Yale University study of high school students in Connecticut, published in the journal Pediatrics, suggested that the approach was gaining favor among teenagers as a way to produce more flavorful clouds of vapor and “a stronger throat hit.”

Of the teenagers who reported using e-cigarettes, about a fourth said they had hacked the devices to allow dripping.

The study defines e-cigarettes, which come in a variety of forms, as tools that “electrically heat and vaporize e-liquids to produce inhalable vapors.” Those liquids typically contain nicotine and are available in different flavors.

In dripping, the liquid is manually applied to the e-cigarette’s heated inner coil, rather than allowing it to flow there via an automatic wick system.

The study was based on anonymous surveys of 7,045 high school students in Connecticut. A full 1,874 said they had indulged in vaping with e-cigarettes at some point, though researchers counted only 1,080 after winnowing out some surveys with inconsistent answers. Of those, 282 said they had tried dripping.

Dr. Suchitra Krishnan-Sarin, a psychiatry professor at Yale and lead author of the study, wasn’t surprised about the prevalence of vaping. “Teens are certainly drawn to both the novelty of the product and the availability of different flavors,” she said.

A CBS News report and other summaries of the Yale findings may have been be the first that many parents had heard of the practice. But Blake Brown, 32, who blogs extensively about vaping, said in a phone interview that dripping is nothing new.

“There’s a side of vaping that’s super simple, and that’s what most of the public sees,” he said. “There’s also a different side to vaping where people like to tinker around with things, take things apart.”

Manufacturers, he added, have already caught on to the dripping trend and created vaping devices that feature exposed coils, allowing users easier access to drip their liquid manually.

“You’re getting more of a smooth draw and the flavor is enhanced greatly,” he said. “Compared to the standard e-cigs you can get, it’s like, you can go buy a Prius or you can go buy a Corvette.”

Mr. Brown emphasized, however, that vaping is for adults — not teenagers.

The Yale study was not designed to investigate health risks, but Dr. Krishnan-Sarin pointed to recent research from the American University of Beirut suggesting that dripping — which can expose the nicotine liquid to higher temperatures than normal — may release higher levels of carcinogens.

She said more research is necessary to fully understand the long-term effects of vaping and e-cigarettes.

Lawmakers have scrambled to regulate vaping, which gained popularity only recently as an alternative to traditional methods of smoking and chewing tobacco. According to a history compiled by the Consumer Advocates for Smoke Free Alternatives Association, modern e-cigarettes did not make their way to the United States until 2006. (The organization also documents a smattering of prototype patents dating as far back as 1930.)

Differing state approaches led to a patchwork of regulations until last year, when federal law made it illegal to sell e-cigarettes to anyone under 18.

But as the Yale study makes clear, teenagers — in Connecticut, at least — are undeterred by the law.

“My message to parents always is: It’s not a good idea for your kids to use these e-cigarettes until we know more about the safety and toxicity of these products,” Dr. Krishnan-Sarin said.