As e-liquids gained popularity, the world said goodbye to that quintessential secondhand smoke smell. The vaping and e-cigarette industries have introduced flavored liquids, ranging from Blue Raspberry Cotton Candy to Frozen Lime Drop. But as a recent series of studies from the UNC School of Medicine suggests, there may be some toxic ingredients masked behind these enticing names.
Robert Tarran, an associate professor in cell biology and physiology, co-authored a study published in PLOS Biology on March 27 in which human cells were exposed to e-cigarette and vaping flavors. With funding from the FDA, Tarran and his team found that the levels of toxicity amongst the 148 ingredients that they studied varied greatly.
As the research project manager in the Tarran lab, Flori Sassano co-authored the study with Tarran. She said their team narrowed down which chemicals to study based on which e-liquids were popular at the time, but it was challenging to study the liquids since they had so many added chemical ingredients.
“The conclusion or take-home message was that these e-cigarettes are very heterogeneous,” Sassano said. “So it’s hard to make conclusions out of only one or two because the chemicals in them are very different.”
Off all of the ingredients, vanillin and cinnamaldehyde were found to demonstrate the greatest effects of toxicity. In order to evaluate the toxicity of each of the chemicals, Tarran recommended that the added flavors should be compared to the base compound, propylene glycol, which is found in nicotine.
“If I was making the laws, I would say if an e-liquid had the same toxicity as just the base on its own, sell it,” Tarran said. “And if it’s more toxic, then it should go back and give it a second look.”
Currently, the vaping and e-cigarette industry operates with little to no regulations, enabling companies to sell products that are cheap but may potentially contain harmful ingredients. One such ingredient, diacetyl, is a buttery-flavored chemical that was previously found in microwave popcorn until it was linked to cases of bronchiolitis obliteran among factory workers who breathed it in. About 10 years later, it has returned to the market as a common, unregulated ingredient in e-cigarettes.
Tarran explained that this issue of harmful chemicals being sold to customers stems back to the unregulated market.
“A lot of them are made by companies that have just sprung up and the manufacturing is not regulated that well,” Tarran said. “So if you were like a big drug company, you would need to prove it’s safe. And for this stuff, you can buy the materials and just sell it without it being tested in humans or anything.”
Sven-Eric Jordt is an associate professor in anesthesiology, pharmacology and cancer biology through the Duke School of Medicine who also studies e-cigarettes and vaping but in the context of their effect on human development.
“We are specifically researching menthol, for example, as a flavor,” Jordt said. “It actually has pathological properties. It acts as a cooling agent that makes you feel cool while you’re inhaling it and it reduces the harshness of the vapor. And it actually makes you inhale more vapor and nicotine.”
Through this growing body of research, the risks of vaping are becoming better understood. UNC Research Specialist Bryan Zorn said there is no evidence to suggest that vaping is harmless, as people may have assumed.
“The FDA wants to know what hurts people and what doesn’t,” Zorn said. “And we have found a number of chemicals that hurt people that are in e-liquids that you can buy in Chapel Hill.”
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