By Clair Weaver
January 11, 2009 12:00am
AUSTRALIA'S top-selling mouthwashes can cause oral cancer and should be pulled from supermarket shelves immediately.
Leading independent experts have issued this strong warning after investigating latest scientific evidence linking alcohol-containing mouthwashes to the deadly disease.
Their review, published in the Dental Journal of Australia, concludes there is now ``sufficient evidence'' that "alcohol-containing mouthwashes contribute to the increased risk of development of oral cancer''.
The ethanol in mouthwash is thought to allow cancer-causing substances to permeate the lining of the mouth more easily and cause harm.
Acetaldehyde, a toxic by-product of alcohol that may accumulate in the oral cavity when swished around the mouth, is also believed to be carcinogenic.
Listerine, the nation's biggest-selling mouthwash and a brand endorsed by the Australian Dental Association (ADA), contains as much as 26 per cent alcohol.
Mouthwash is one of the fastest-growing grocery products in Australia, with the category now worth more than $75 million, according to latest Nielsen market research.
Lead review author ProfessorMichael McCullough has told The Sunday Telegraph alcohol-containing mouthwash should be reclassified as prescription-only and carry written health warnings.
Prof McCullough, chair of the ADA's therapeutics committee and associate professor of oral medicine at the University of Melbourne, is calling on the ADA to urgently re-assess its seal of approval on mouthwashes containing alcohol.
"We see people with oral cancer who have no other risk factors than the use of alcohol-containing mouthwash, so what we've done in this study is review all the evidence that's out there,'' he said.
"Since this article came out, 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 five-fold increased risk of skin cancer, no one would be recommending it.''
Oral cancer is a gruelling and mutilating disease that afflicts more than 800 Australians each year and kills half of them within five years of being diagnosed.
Smoking and alcohol consumption are well-established risk factors, but alcohol-containing mouthwash use 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 versions.
"(We) further feel it is inadvisable for oral health-care professionals to recommend the long-term use of alcohol-containing mouthwashes,'' they concluded.
The review reported evidence from an international study of 3210 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 nine-fold increased risk of cancers of the oral cavity, pharynx and larynx.
Those who also drank alcohol had more than five times the risk - and even those who neither drank nor smoked still ran a four- to five-fold risk of contracting cancer.
A Brazilian study has also found regular mouthwash use is associated with oral cancer regardless of alcohol or tobacco consumption.
"Mouthwash products are in contact with the oral mucosa as much as alcoholic beverages, and may cause chemical aggression of the cells,'' researchers from the University of Sao Paulo said.
They said the role of ethanol in causing DNA damage needed to be explored further.
A review in the Journal of Occupational Medicine and Toxicology last year said it would be "prudent, precautionary public-health policy to generally refrain from using ethanol in (mouthwash) products'' because of "doubts about the safety of alcohol-containing oral products''.
Prof McCullough said the most popular mouthwashes contained higher concentrations of alcohol than drinks such as wine or beer.
"If you have a glass of wine, you tend to swallow it,'' he said.
"With mouthwash, you have a higher level of alcohol and spend longer swishing it around your mouth.
"The alcohol that is present in your mouth is turned into acetaldehyde.''
Regular alcohol consumption was a cancer risk, Prof McCullough said, but usually did not involve swishing it around the mouth.
Eating while drinking increased salivation, which lowered the risks, he said.
"The most significant difference (between alcohol and alcohol-containing mouthwash) is that one is for pleasure and the other is being recommended as a health product.''
Cancer Council NSW chief executive Andrew Penman said the review was "interesting'', but called for further research.
"I think it's quite a well-thought-out proposition, but it does warrant further investigation,'' he said.
