(Bill O’Leary/The Washington Post)

In 2003, after his father died from a tobacco habit, a Chinese pharmacist named Hon Lik developed an electronic device to vaporize nicotine. A precursor to what are now called e-cigarettes or vaporizers, the device’s goal was to deliver nicotine without the carcinogens. Lik’s first attempt relied on ultrasonic technology to create vapor, but the guts of electronic cigarettes today are, as a rule, battery-powered heating coils. These coils, known as atomizers, turn liquids — often flavored, with nicknames like e-liquid or juice, and frequently but not always containing nicotine — into vapor.

As e-cigarettes grew in popularity in the mid-to-late 2000s, users did not stop tinkering with the technology. Mass-produced cartridges, pre-filled with the nicotine liquid of various concentrations, are common.

But one technique eschews the tanks or cartridges; the juice is manually dropped directly onto the coil, and the resulting vapor inhaled. (Devices can now be purchased specifically for this purpose, or modified.) The technique, called “dripping,” may be popular among teenage e-cigarette users, reported researchers on Monday in the journal Pediatrics.

In a survey of 7,000 high schoolers in Connecticut, just over 1,000 reported using e-cigarettes. Of these, 1 in 4 said they had tried dripping. The concern, the authors noted, was that teenagers may be attempting to drip but accidentally exposing themselves to unsafe levels of e-liquids. “What we are discovering with our work with youth is that kids are actually using these electronic products for other behaviors, not just for vaping e-liquids from cartridges or tanks,” said Yale University psychiatry professor Suchitra Krishnan-Sarin, an author of the study, in a news release.

Between 2013 and 2014, rates of e-cigarette use by high schoolers increased from under 5 percent to 13.4 percent, the Centers for Disease Control and Prevention found, at the same time as tobacco use dropped. In 2016, federal law banned children under the age of 18 from buying e-cigarettes. As the new study indicates, the law has not halted teen vaping. But it could not be said from the report whether dripping was increasing or decreasing in popularity among the teenage crowd — the report was the first to examine the practice of dripping, at all, among the high school set.

Krishnan-Sarin and her colleagues found that most of those who dripped did so to produce “thicker clouds of vapor.” But a few teens reported they dripped because it made the flavors “taste better” or produced a “stronger throat hit”; a fifth said they dripped out of curiosity.

In the paper, the researchers warned that dripping, instead of a “standard puff” of an e-cigarette, possibly exposed the teenagers to higher concentrations of vaporized nicotine. “Everybody assumes vaping is a safer way [than cigarettes] of administering nicotine,” Krishnan-Sarin said, “but we know so little about the risks of vaping.”

The degree of Lik’s success in removing the danger from nicotine delivery has been the subject of intense debate. Some studies indicate that it is possible for e-cigarettes to help users quit smoking; others counter that e-cigarettes might complement a conventional tobacco habit, or even desensitize teenagers who vape to the dangers of smoking. But e-cigarette proponents point out that the devices, because they omit the tar-producing combustion of tobacco, are preferable to cigarettes.

A new study in the journal Annals of Internal Medicine, also published Monday, tracked the levels of nicotine and cancer-causing chemicals in 181 people, including e-cigarette users, former smokers who vape and cigarette smokers, for six months. Those who restricted themselves to vaporizers or e-cigarettes only were exposed to lower levels of carcinogens. Former smokers who now only used e-cigarettes, for instance, had a 97.5 percent reduction of NNAL, the form of a tobacco-specific carcinogen that is excreted in urine.

“What we found is that using e-cigarettes alone results in very low exposure to toxins and carcinogens,” Lion Shahab, a health psychologist at University College London and an author of the Annals of Internal Medicine paper, told New Scientist on Monday.

Almost all e-cigarette science comes with the caveat that more research is needed. Pinning down just how safe the technology is a challenge. One issue, noted Pennsylvania State University chemist Kurt Kistler to Motherboard in 2016, stems from the “huge variety of devices” used.

That variety is also reflected in nicotine delivery technique, like dripping over puffing. Research led by Virginia Commonwealth University’s Alan Shihadeh revealed that dripping at very high coil temperatures — from 266 degrees to upward of 662 degrees — produced “high toxicant emissions.”

“If I was in a torture chamber and you said I had to puff on something, I’d choose an e-cigarette over a regular cigarette,” Shihadeh told the New York Times in 2014. “But if you said I could choose an e-cigarette or clean air, I’d definitely choose clean air.” He went on to say: “And I definitely wouldn’t drip.”

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