An Australian research professor is warning that top-selling mouthwashes with high alcohol levels can cause oral cancer.
A review published in the Dental Journal of Australia says the ethanol in mouthwash allows dangerous substances to penetrate the lining of the mouth, causing harm.
"It increases the permeability of the mucosa to other carcinogens like nicotine," explains Professor McCullough. "But also the first breakdown product of alcohol with enzyme alcohol dehydrogenase is acetaldehyde. And acetaldehyde is a known human carcinogen."
Professor McCullough says tobacco is the leading cause of oral cancer, but alcohol also plays a part.
"There's always those patients who don't have either, neither smoked or drank considerably," he says. "And anecdotally we've all got patients who've reported over ten years of use of alcohol-containing mouthwashes."
He says there is enough evidence to suggest dentists should not be recommending long-term use, and earlier this evening the New Zealand Ministry of Health advised that it is not sensible to use alcohol-containing mouthwash long-term without advice from a dentist.
However not everyone believes the claims and some experts say more proof is needed.
"It hasn't actually been established that there is a direct relationship between mouthwashes with alcohol and oral cancer," Dr Neil Hewson from the Australian Dental Association says.
The Australian Dental Association endorses mouthwashes containing as much as 26 percent alcohol.
"We have a separate group of people that look into the criteria for our seal of approval and these people think at the moment it's still ok for Listerine and others to be approved," says Professor McCullough.
Dr Hewson says if people floss their teeth, brush properly and have a good diet then they should not need mouthwash at all.
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