Scientists find unsafe levels of known carcinogen in menthol e-cigarettes

Menthol flavouring in e-cigarettes may cause cancer.
Menthol flavouring in e-cigarettes may cause cancer.

As doctors race to determine what is causing sudden and severe lung illnesses among some vapers, new research discovers dangerously high levels of a known carcinogen in menthol-flavoured electronic cigarettes.

The chemical (pulegone) is used as a menthol and mint flavouring, even though it was recently banned in foods, the researchers said.

Lung and liver cancer

"If pulegone is not allowed in food, there's no reason why it should be allowed in e-cigarettes," said lead researcher Sven-Eric Jordt. He's an associate professor of anaesthesiology at Duke University School of Medicine in Durham, North Carolina.

Because pulegone is known to cause lung and liver cancer in animals, the US Food and Drug Administration banned its use in foods in 2018 after pressure from consumer groups, Jordt explained.

But the FDA does not regulate pulegone's use in e-cigarettes or smokeless tobacco, which are touted as safer than tobacco cigarettes, he added.

Jordt said that tobacco companies began removing pulegone from cigarettes in the 1960s and 1970s because it was an irritant and consumers didn't like it.

That same strategy didn't transfer to e-cigarette companies, which use pulegone because it's a lot less expensive than other menthol and mint flavourings, Jordt explained.

"Many are small companies that likely buy some cheap compound, maybe even a skin oil or an oil for lamps or something," he said. "They're just buying the least expensive thing they can add to get the flavour."

Ban on all flavoured cigarettes

Reacting to a spate of severe lung infections tied to vaping and the soaring popularity of e-cigarettes among teens, the Trump administration announced last week that it would move to ban flavoured e-cigarettes.

On Monday, New York Gov. Andrew Cuomo, a Democrat, said he would use an executive order to ban most flavoured e-cigarettes in that state, with the notable exception of menthol flavour. Cuomo said he was not banning that flavour because it might help menthol cigarette smokers quit, but he added that might change in the future. On 4 September Michigan became the first state to ban all flavoured e-cigarettes.

According to Erika Sward, an assistant vice president for national advocacy at the American Lung Association, "We have a fundamental failure to protect the public from dangerous chemicals. And that is why FDA needs to step it up and why the public should not use e-cigarettes."

Sward also noted that e-cigarettes have only been on the market for about a decade, so the long-term effects of vaping aren't fully known yet.

"That's what the American Lung Association has been sounding the alarm bell about," she said. "The Wild West has been allowed to exist for too long. We're going to see the consequences of that for decades to come. So, don't use e-cigarettes."

For the study, Jordt and his colleague, Sairam Jabba, a Duke senior research associate, analysed several brands of regular menthol cigarettes, three e-cigarette brands and one smokeless tobacco brand, all of which contained pulegone.

A troubling study

The researchers compared levels of pulegone in these products with the level of pulegone known to cause cancer in animals.

E-cigarettes and smokeless tobacco contained levels of pulegone higher than what the FDA considers safe. In regular menthol cigarettes, the level of pulegone was below the danger level, the researchers found.

Stanton Glantz is a professor of medicine at the Center for Tobacco Control, Research and Education at the University of California, San Francisco. He said, "This is a troubling study that highlights the fact that the FDA's continuing refusal to remove menthol from cigarettes and other tobacco products is harming people."

Glantz added that the FDA has announced that it will be suspending the sale of menthol e-cigarettes, but the official policy has not yet been released.

The research letter was published online in JAMA Internal Medicine.

Image credit: iStock

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