Unlike with regular cigarettes, the nicotine in electronic cigarettes comes in liquid form, and the device electrically heats the solution to vaporize it into an inhalable mist. But some users have found a way to bypass the heating system and drip the liquid directly onto the exposed heating coil.

The purpose is to create denser vapor for a greater throat impact. High school students use the term "dripping" to describe this method for getting a bigger hit of nicotine from e-cigs.

The concern is that an already unhealthy habit is made more dangerous by potentially creating an increased exposure to the non-nicotine toxic elements that are emitted with the higher burning temperature of the coil.

A group of researchers recently investigated the nicotine and volatile aldehyde toxins emitted from a direct dripping system and measured temperatures related to the system. They found that the volatile aldehyde toxins greatly exceed the values that had been reported for the use of e-cigs in general. The temperatures ranged from 130 degrees to 350 degrees, and with these temperatures there are likely to be high toxic emissions.

Recent reports indicate that over 25 percent of high school students use nicotine products — 3.2 percent cigarettes only, 15.8 percent used e-cigs only and 7.5 percent used both. Studies have found that the use of nicotine is associated with risk behaviors. A risk behavior is changing the use of e-cig in such a way as to increase pleasure, but also increase harm.

Additional surveys found that over 25 percent of those using e-cigs had used the system for dripping. The reasons offered were that dripping produced thicker clouds of vapor, made the flavors taste better, produced a stronger throat hit and just curiosity.

The developing brains of teenagers are more vulnerable to nicotine and the additional harm that the toxins add. Dr. Karen Wilson, the chief of general pediatrics at Mount Sinai Health System in New York City recently offered her thoughts on dripping.

"Adolescents should not be using nicotine at all," Wilson said. "It changes the brain chemistry, and adolescents are uniquely susceptible to the addictive properties of nicotine."

The lead researcher in the study of high school students said students often learn about dripping from the internet.

"This is one of the reasons why teens seem to like these devices. They like that they can do these novel things with them," said Suchitra Krishnan-Sarin, Ph.D. and a professor of psychiatry at Yale University School of Medicine in New Haven, Connecticut. "They say it makes the flavors taste better and gives you a stronger hit."

The flavorings used in e-cigs can be a major contributor to the toxins emitted by e-cigs. Additives specific to flavors are damaging to young lungs, and there is even greater concern in the greater concentrations that dripping creates.

As of Aug. 8, 2016, the Food and Drug Administration is regulating e-cigs as tobacco products, but the ruling is new and the rules governing such products are still under development. But one thing is clear, oversight is necessary to better ensure protection of vulnerable teenagers.