In what may end up being the most tumultuous year yet for the vaping industry, a team of Duke scientists has bad news for fans of mint or menthol flavored pods. One minty flavoring agent banned by the FDA for being unsafe as a food additive is present in high levels in several brands of e-cigarette products, some of which are still available on the market.
This agent, called pulegone, has a minty flavor similar to peppermint and is legally used in small amounts in menthol cigarettes. In small amounts, pulegone isn’t dangerous, but because it caused tumors in mice who consumed high amounts of synthetic pulegone, the FDA withdrew it from its list of approved food additives in October 2018. And whether it’s dangerous when inhaled in high amounts is still an open question.
In a research letter published Monday in JAMA Internal Medicine a team from Duke re-analyzed two sets of CDC data from 2015 to show that pulegone was present in high levels in five e-liquids: V2 Menthol, V2 Peppermint, Premium Menthol, South Beach Smoke Menthol, and South Beach Smoke Peppermint. Going by their estimations, vaping a pulegone-flavored e-liquid would expose someone to anywhere from 44 to 1,608 times more pulegone each day than smoking menthols.
Sairam Jabba, Ph.D., a study co-author and a researcher associate at Duke, tells Inverse that there’s enough pulegone in those e-liquids to make them potentially unsafe.
“Our risk analysis suggests that mint/menthol-flavored e-cigarette and mint snuff product users are exposed to pulegone levels that are higher than what FDA considers unacceptable for food products, raising serious health concerns for vapers using these products,” he says.
“This study is a proof of principle that there are mint/menthol flavored e-cigarette products out in the market and we do not know their composition and levels for pulegone,” Jabba explains. “So we are recommending that the FDA needs to implement regulations quickly and immediately to exclude harmful chemicals like pulegone and reduce the potential health risks to users.”
How Safe Are Vape Flavors?
These results come on the heels of the FDA’s announcement that it will outline a plan to remove non-tobacco-flavored e-cigarette products from the market. This move is in part a reaction to 380 cases of a vaping-related illness — though it doesn’t address the black market’s role in these cases. But it’s also a continuation of the FDA’s attempt to crack down on teen vaping after record-breaking numbers of teens took up the habit, according to 2018 numbers.
"So we are recommending that the FDA needs to implement regulations quickly."
However, results from studies like this latest one point to another problem. As these authors note in the paper there’s “no inhalation toxicity data for pulegone available.” In other words, even though the FDA has evaluated pulegone as a food additive, we don’t know how safe it is to inhale this product at all. But this isn’t too out of the ordinary for e-cigarette flavoring agents in general.
“With exception of very few flavor chemicals, for most of the e-cigarette flavor chemicals and e-cigarette aerosol chemicals, no long-term inhalation toxicity data is available,” Jabba says.
Jabba explains that the most studied e-cigarette flavoring agent is diacetyl — a chemical that’s been linked to a condition called popcorn lung. And he notes that rodent studies have suggested vanilla, cherry, and cinnamon flavoring used in e-cigarettes can act as “respiratory irritants.”
Pulegone is unique, though, because it was actually banned by the FDA already for posing risks when consumed in high amounts in food. But when it comes to regulating its use in e-liquid, there was no clear guidance on how it should be used safely (it’s present in menthols, after all).
“This demonstrates the inadequate regulatory situation in the USA for e-cigarette additives,” says Jabba, “FDA needs to implement new regulations quickly, to exclude hazardous chemicals and reduce harm and we hope our study will aid efforts towards this end.”
In that sense, we’re still shooting in the dark when it comes to assessing whether certain flavoring agents are dangerous to humans — and if they are, exactly how dangerous they are. But it’s not just about banning chemicals that we already know are dangerous, it’s about researching them so we have clear evidence that illuminates whether they’re safe or not.
Why These Results Aren’t Related to the “Vaping-Related Illness” (Yet)
Right now there are two big stories in the vaping world. The first is the strange spread of an undefined “vaping-related illness” (or illnesses) linked to black market vape products that has landed people in the hospital. But before that, there were still lingering questions about whether ingredients in legal e-liquids, including flavoring agents like pulegone, were safe in the long run.
"This demonstrates the inadequate regulatory situation in the USA for e-cigarette additives."
The first story has eclipsed the second for now. But in the research world scientists are still investigating the long-term health consequences of certain vape flavors. These results address the second question, showing that even if these flavors aren’t linked to acute illnesses, they’re present in high enough amounts to warrant a second look by the FDA.
Regardless of whether flavoring agents have a role to play in these vaping-related illnesses (that’s unconfirmed so far), this paper shows just how far regulation of the legal vaping landscape still has to go.
Abstract: Pulegone, a constituent of oil extracts prepared from mint plants, including peppermint, spearmint and pennyroyal, is a carcinogen that causes hepatic carcinomas, pulmonary metaplasia, and other neoplasms on oral administration in rodents. In 2018, the US Food and Drug Administration (FDA) banned synthetic pulegone as a food additive. Studies by the Centers for Disease Control and Prevention (CDC) detected substantial amounts of pulegone in mint- and menthol-flavored e-cigarette liquids and smokeless tobacco products marketed in the United States. The tobacco industry has minimized pulegone levels in cigarette flavorings because of toxicity concerns. Mint- and menthol-flavored e-cigarettes may be exempt from proposed federal regulations; therefore, the health risk associated with pulegone in these products should be considered.