Using mouthwash could increase risk of cancer by nine times, claim scientists

Published on Monday 12 January 2009 21:14

MOUTHWASHES containing alcohol can cause oral cancer and should be removed from supermarket shelves, a dental health study claims.

Scientists say there is now "sufficient evidence" that such mouthwashes contribute to an increased risk of the disease.

The ethanol in mouthwash is thought to allow cancer-causing substances to permeate the lining of the mouth.

Michael McCullough, associate professor of oral medicine at the University of Melbourne, Australia, who led the study, said: "We see people with oral cancer who have no other risk factors than the use of (mouthwash containing alcohol], so what we've done is review all the evidence.

"Since this article, further evidence has come out, too. We believe there should be warnings. If it was a facial cream that had the effect of reducing acne but had a four to fivefold increased risk of skin cancer, no-one would be recommending it."

Professor McCullough, chair of the Australian Dental Association's therapeutics committee, said the alcohol in mouthwashes "increases the permeability" of the mucus membrane to other carcinogens, such as nicotine.

A toxic breakdown product of alcohol called acetaldehyde that may accumulate in the oral cavity when swished around the mouth is also a "known human carcinogen," he said.

Top-selling mouthwashes contain as much as 26 per cent alcohol.

Smoking and alcohol are well-established risk factors in causing cancer, but the use of mouthwash containing alcohol is more controversial.

Prof McCullough and co- author Dr Camile Farah, director of research at the University of Queensland's School of Dentistry, recommended mouthwash be restricted to "short-term" medical use or replaced by alcohol-free products.

The review reported evidence from an international study of 3,210 people, which found daily mouthwash use was a "significant risk factor" for head and neck cancer – irrespective of whether users also drank alcohol or smoked.

But the effects of mouthwash were worst in smokers, who had a ninefold increased risk of cancers of the oral cavity, pharynx and larynx. Those who also drank alcohol had more than five times the risk.

However, Professor Damien Walmsley, scientific adviser to the British Dental Association, said further research was needed to substantiate the claims.

"Excessive consumption of alcohol and tobacco are well recognised in the UK as risk factors for developing oral cancers," he said.

"This paper raises interesting issues, but the evidence showing any link between the prolonged use of mouthwashes containing alcohol and oral cancer is not conclusive, and requires further trials to establish if there is a genuine connection.

"If patients are in any doubt about using mouthwash, they should consult their dentist."

Dr Nigel Carter, the chief executive of the British Dental Health Foundation, 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.

"The public should not worry."

Last night, a spokeswoman for Johnson & Johnson Ltd UK, the manufacturer of Listerine, said: "There is no scientific evidence to support an association between the use of alcohol- containing mouthwashes, such as Listerine, and an increased risk of oral cancer."