Some teens who use e-cigarettes are now to turning to 'dripping' e-liquids directly onto exposed heater coils to produce thicker clouds of vapor, better flavor, a stronger throat hit, or simply out of curiosity, found a study published online today from Pediatrics.

For the study, researchers surveyed 7,045 students from eight Connecticut high schools. Among the 1,080 students who had ever used e-cigarettes, more than 26 percent had used e-cigarettes for dripping. An analysis of data suggested male white teens who used e-cigarettes more frequently were more likely to use 'dripping'.

We asked the study's lead author Suchitra Krishnan-Sarin, PhD, a professor in the Department of Psychiatry, and vice-chair of the Human Investigations Committee at Yale University School of Medicine, more about the study's findings:

Did the number of students who had ever used e-cigarettes surprise you? Do these results reflect what is happening nationally?

We did not know what to expect. We had anecdotal evidence that youth were choosing to directly drip liquid onto exposed heater coils, instead of the normal use of an e-cigarettes where an automatic wick feeds the liquid into the electrical heater.  However, no one had systematically assessed the use of this behavior.  So, in one way the fact that 1 in 4 e-cigarette teen users were participating in this alternative use behavior was a surprise.  We do know if these results reflect what is happening nationally since this is the first report assessing the rates of dripping among youth. We are not aware of any national data that has examined this issue.

Is 'dripping' a new trend among those who use e-cigarettes?

We have not examined how long this behavior has been going on among youth or adults. Online blogs on use of e-cigarettes for dripping have emerged over the past couple of years; however, it is hard to say if e-cigarette users have always participated in this behavior or whether it is a new trend.  The fact of the matter is that it has never been systematically studied before.

What does the existing research say that suggests this variation carries risks for users?

There is one study that used machine-generated aerosols to examine nicotine and volatile aldehyde emissions from one type of direct drip atomizers (which is an add-on part that can be purchased for an e-cigarette device).  They observed that volatile aldehyde emissions (like formaldehyde) were higher with direct dripping than with conventional e-cigarette or combustible cigarette use.  We need more studies like this to examine the risks of this alternative use behavior.  

What's your advice for parents when talking to their teens about e-cigarettes and the potential risks of variations such as dripping?

The risks of short term and long term use of e-cigarettes are not known. While e-cigarettes may contain less toxicants than cigarettes, e-cigarettes contain many other chemicals like propylene glycol and glycerin which when heated at high temperatures (like with "dripping") can produce high levels of carcinogenic compounds like aldehydes.

E-liquids also contain many flavor chemicals, such as aldehydes, vanillins, and alcohols, which are considered safe for ingestion, but little is known about the toxicity of inhaling these chemicals, especially at high temperatures. So, along with encouraging their teen to not use cigarettes, parents should also encourage them to not use e-cigarettes, and especially avoid alternative behaviors like dripping.  

What are your next steps in research?

We need to know so much more about use of 'dripping' among teens.  We are continuing our efforts to determine how often teens use 'dripping"'and how they modify their e-liquids and e-cigarette devices for this behavior. We need develop a basic understanding of these issues to estimate the risk posed by this alternative use behavior.

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