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A new American study has found users of mint and menthol e-cigarettes are exposed to high levels of the carcinogen pulegone.
Pulegone has been banned as a food additive, and the intake of the substance from vaping is higher than from menthol cigarettes.
One of the authors of the study, Dr Sairam Jabba, from the Duke University School of Medicine in North Carolina, told Morning Report the levels of pulegone is cause for alarm.
"Mint and menthol e-cigarette users are getting much more pulegone than would have been considered safe for FDA food intake.
"This raises serious health concerns for vapers using these products."
Pulegone is known to be a respiratory irritant, but the reason for the ban in food products by the FDA was that it was shown to be a carcinogen.
Dr Jabba said there have been no long term studies on the effects in humans.
He said there is a lot more research that needs to be done before people can claim vaping is safer than smoking.
"There is more and more information that is coming out saying that vaping could also cause serious respiratory health issues."
He said his team is pushing for the FDA to ban chemicals such as pulegone from use in e-cigarette liquids.