Mouthwashes containing alcohol can significantly increase the risk of oral cancer, a new study suggests.
Scientists in Australia claim there is now 'sufficient evidence' linking the alcohol in mouthwashes to the disease and that such products should be taken off shop shelves and labelled with health warnings to protect the public.
In a review of the latest research, the scientists found evidence that the ethanol was allowing cancer-causing substances – such as nicotine – to permeate the lining of the mouth more easily, making it harmful.
Prof Michael McCullough, professor of oral medicine at the University of Melbourne, Australia, who led the study, said the alcohol in mouthwashes can also produce a substance called acetaldehyde, a 'known human carcinogen'.
"We see people with oral cancer who have no other risk factors than the use of alcohol-containing mouthwash, so what we've done is review all the evidence," Prof McCullough explained.
"We believe there should be warnings. If it was a facial cream that had the effect of reducing acne but had a four-to-five-fold increased risk of skin cancer, no one would be recommending it."
The Melbourne University research team studied more than 3,200 people and found the effects of daily mouthwash use were worst in smokers, who had a nine-fold increased risk of cancers of the oral cavity, pharynx and larynx. There was also a five-fold increase found among those who drank alcohol.
They also found that the most popular mouthwashes contained higher concentrations of alcohol than drinks such as wine or beer.
The findings, published in the Dental Journal of Australia, were supported by cancer organisations and other groups. A spokesman for Cancer Research UK spokesman stressed that "alcohol definitely causes mouth cancer" .
Dr Philip Stemmer, from London's Fresh Breath Centre, added: "There's no need for mouthwash to contain alcohol – I recommend patients use an alcohol-free mouthwash instead."
But Johnson and Johnson, manufacturers of leading brand Listerine, played down the scare. A spokesman said the product was safe and "the most extensively tested mouthwash in the world".
Dr Nigel Carter, the chief executive of the British Dental Health Foundation (BDHF), rejected the findings and said: "A recent, and more thorough review of all available evidence carried out by leading experts on behalf of the foundation concluded there were no proven links between alcohol-containing mouthwashes and increased incidence of mouth cancer ."
