Precisely how metals get from the coil into the surrounding e-liquid is another mystery. These toxins, when inhaled, could potentially damage a person's lungs, liver, heart, and brain.
Just for perspective, the U.S. Food and Drug Administration hasn't regulated e-cigarettes yet.
Ana María Rule, senior author of the study, said that e-cigarette companies and vapers must be aware that the way these coils are now made appears to cause them to leak harmful toxins.
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They tested whether the e-liquids in the devices' refilling tanks and the aerosol produced contain any toxic metals. Vaping-inhaling this aerosol as if it were cigarette smoke-is popular especially among teens, young adults, and former smokers. This is big news considering that almost 15% of 8th, 10th and 12th grade students in public and private schools has used e-cigarettes in the past month.
Vaping is popular in part because it provides a nicotine "hit" and the look and feel of tobacco smoking, but without some of smoking's extreme health risks. Evidence that vaping isn't entirely safe continues to accumulate, however.
Higher concentrations of toxic materials were also found in the aerosols generated by the devices, Forbes said. While the study's authors hypothesize that the metals appear in the e-cig vapor thanks to the metal coils, they do not know how arsenic apparently finds it way into the e-cig refill liquid itself.
From the difference, it has been concluded that the metals had come from the coils. Close to 50% of the cases showed lead concentrations higher than health-based limits defined by the Environmental Protection Agency. Similarly, median aerosol concentrations of nickel, chromium and manganese approached or exceeded safe limits.
'These were median levels only, ' says senior study author Dr Ana María Rule.
Previous studies on metals in e-cigarettes were focused on cigalikes, early devices that contained a disposable cartomizer with a coil and preloaded e-liquid.
Bad news, vapers. Your e-cigs might not be the healthier alternative to cigarettes you think they are.
The levels of metals in the dispensers - where the e-liquid is kept before it is heated - were nominal and of little concern. Rule believes the heating coils found in the tanks could somehow be transferring metal into the aerosol.
For the study, 56 daily e-cigarette users from vaping conventions and e-cigarette shops around Baltimore participated. Researchers were particularly curious as to whether the metal coil that heats the liquid in e-cigs was leeching toxic metals or generating them. Other studies, including one a year ago from Rule's group, have detected significant levels of toxic metals in e-liquids exposed to the e-cigarette heating coil. The refill e-liquid also detected significant levels of arsenic. Rule's team plans further studies.