A person walks into Wal-Mart with the goal to pick up some toothpaste. As they find the aisle, which contains toothpaste, they come across some mouthwash. She thinks that it cannot hurt to purchase some as the container claims the product cleans your mouth and makes your smile whiter. Although these claims may be true, there may be a danger present in using this mouthwash. Is mouthwash associated with oral cancer?
40,000 Americans and around 640,000 people in the world are diagnosed with oral cancer annually. The deaths that result from oral cancer are over 7,800 a year.
The ingredients in certain mouthwashes are said to be carcinogenic. Fluoride, formaldehyde, and saccharin, (or common ingredients found in mouthwash) have been suspected to be cancer triggers. The U.S. Environmental Protection Agency claims formaldehyde is a “probable human carcinogen.” Studies in the 1980s revealed that rats exposed to formaldehyde ended up having nasal cancer in fact (but no proof has shown it causes cancer in humans yet).
The Dental Journal of Australia has made the claim that alcohol-based mouthwashes and an increased risk of oral cancers correlate as a result of causation (the mouthwash causes oral cancer).
One study completed by researchers from the University of Glasgow Dental School studied 1,963 patients with cancer of the oral cavity, oropharynx, hypopharynx, larynx or esophagus and then tested another 1,993 people as control subjects from nine different countries. The researchers seemed to find a link between mouthwash and cancer after removing the causation of oral cancer from smoking, alcohol, and low socioeconomic status. Scores were interpreted to analyze oral health and dental care. Odd ratios (which help us identify the probability one thing is associated with another) of low versus high scores of oral health and dental care and confidence intervals were used to adjust for confounding factors. The odd ratios for the absolute frequent use of mouthwash (in which is considered the use of mouthwash 3 or more times a day), was 3.23 with the confidence interval ranging from 1.68-6.19. This proof is very strong as odd ratios over 1 show a strong correlation between two things but only 1.8% of cases and 0.8% of controls reported using mouthwash 3 or more times a day. This information was said to show a link between oral cancer and mouthwash. There needs to be more research however as no known mechanism has been found.
Professor Wolfgang Ahrens, Deputy Director of the BIPS says, “These results are really important. Up until now, it was not really known if these dental risk factors were independent of the well known risks for mouth and throat cancers – smoking, alcohol and low socioeconomic status.” The researchers found, “frequent use of mouthwashes (3-plus times per day) was associated with an elevated risk of developing mouth and throat cancer.”
The Journal of Oral Oncology has gone into depth to discuss whether or not mouthwash is the causation for oral cancer. It analyzed 10 major control case studies that have been performed in the last three decades to observe this phenomenon. Of the 10 reviewed, 7 showed there was no consistent association with mouthwash and oral cancer, while the 3 others had very minor proof to link the two.
In 1991, a study found that the risk of oral cancer was elevated by 40% for males and 60% for female who used mouthwash containing alcohol after adjusting for tobacco and alcohol use. Thus, raising some concern there are many confounding factors linked to raising the risks of cancer. Since then, a handful of other studies have been completed, but they cannot directly prove the causation of oral cancer thanks to mouthwash.
There have been numerous studies in which show there is a connection between cancer and mouthwash but yet again, there are too many confounding variables to be aware of. The numbers in the studies are too insignificant to worry researchers yet. The null hypothesis has not been rejected so far. I would tell people to keep using mouthwash but to limit the use of it to no more than twice as day as little evidence shows high use of the mouthwash shows some concern in elevating oral cancer risks.