article in the Telegraph
"They claimed there was now "sufficient evidence" that mouthwashes containing alcohol contribute to an increased risk of the disease that they should be taken off supermarket shelves and labelled with health warnings.
In a review of the latest studies, the scientists found evidence that the ethanol in mouthwash was allowing cancer-causing substances to permeate the lining of the mouth more easily and therefore cause harm.
Professor Michael McCulloch, chairman of the Australian Dental Association's therapeutics committee and associate professor of oral medicine at Melbourne University, said the alcohol in mouthwashes "increases the permeability of the mucosa" to carcinogens like nicotine.
He added that a toxic breakdown product of alcohol called acetaldehyde that may accumulate in the oral cavity when swished around the mouth is also a carcinogen."