Mouthwashes and cancer

Alcohol-containing mouthwashes
linked to cancer

I heard years ago that mouthwashes like Listerine that contain alcohol can increase your risk of cancer of the mouth and throat. Alcohol in general is a carcinogen.

Anyway, I cut back on my use of Listerine from every night to two or three nights a week, while continuing to floss nightly. Listerine IS effective at controlling gum disease (gingivitis) and I can't see giving it up completely. I do have a problem with my gums, and somehow it didn't seem worth losing my teeth just to reduce a cancer risk that's already pretty low (especially among non-smokers). I found that occasional Listerine use prevented gum disease just fine. My checkups are still good.

Never gave it another thought until I came across a study in the Dental Journal of Australia (December 2008; 53(4): pages 302-305) that provides new evidence for the cancer link. Even more interesting is the charge that Listerine's makers engaged in a sinister plot. . .

Continued below...

The study made quite a splash Down Under, where sales of Listerine reportedly dropped by half in the year after it was published. One of the authors, Professor Michael McCullough, said some mouthwashes were more dangerous than wine or beer because they contain higher concentrations of alcohol — as high as 26 per cent.

"We see people with oral cancer who have no other risk factors than the use of alcohol-containing mouthwash, so what we've done with this study is review all the evidence that's out there," Professor McCullough said.

A spokesman for Johnson & Johnson, which makes Listerine, dismissed the study: "This small review includes only a selective group of clinical data. Evidence from at least ten epidemiological studies published over the last three decades strongly suggests that use of alcohol-containing rinses does not increase the risk of oral cancer."

Dental establishment says "no problem here"

The American Dental Association agrees that the alcohol contained in antiseptic mouthwash is safe and not a factor in oral cancers. Remember, these are the people who brought us mercury fillings and continue to insist they're safe, even while every informed consumer has run to the nearest alternative dentist to get them taken out. (See our Special Report The Secret Poison in Your Mouth.)

A 2003 article in Journal of the American Dental Association (134(8): pages 1079-1087) takes the party line. The authors sought out every study published in the previous 25 years that made a reference to mouthwash and the causes of cancer of the mouth and throat (oropharyngeal cancer or OPC). They found nine such studies.

They report, "The results of six of the studies reviewed are negative and provide no support for the hypothesis that use of alcohol-containing mouthwash increases the risk of OPC." The other three studies did show a link, but at least one of those was contradicted by a follow-up study, and another was flawed.

They conclude ". . .the weight of the evidence strongly suggests that use of alcohol-containing mouthwash does not increase the risk of OPC."

But I'm not quite ready to throw out the findings in the Australian study. Taking evidence from international research involving 3,210 people, the Australians found that daily use of mouthwash was "a significant risk factor" for head and neck cancer. The review was carried out in Cuba, Argentina and Brazil (not the most representative choice of countries, if you ask me).

The effects were worst in smokers. They experienced a nine-fold increased risk of cancers of the mouth, pharynx and larynx. Those who drank alcohol had more than five times the risk of those who don't. Reacting to the Australian study, a spokesman for the British Dental Association said the evidence was "not conclusive" and more research was needed.

Brazilian study gives more support

I poked around the internet and turned up another study to support the theory that mouthwashes contribute to oral cancer. Researchers from the University of Sao Paulo in Brazil reviewed case studies from 309 patients suffering from cancer of the mouth and pharynx, matched by sex and age with 468 control cases of people who were cancer-free.

The Brazilian researchers interviewed all these people to gather detailed information on their smoking and drinking habits, schooling, and oral health and hygiene (i.e. whether they brushed, flossed, used mouthwash, received professional dental care, etc.) They found that daily mouthwash use was associated with cancers of the pharynx and the mouth. Bleeding gums and failure to have dental visits were also strongly associated with cancer.

In another study, UK researchers found that use of low pH (acidic) mouthwashes over the long term causes erosion of the dental enamel and sensitivity in teeth. Most popular mouthwashes are highly acidic, including Listerine and Scope. This is isn't a cancer finding, but it's another good reason to be cautious about alcohol-containing mouthwashes.

What's my take? I don't have a high level of trust in America's dental establishment. The main problem is their lack of credibility, especially in light of the mercury issue. But when it comes to alcohol-containing mouthwashes the evidence seems mixed. I think what we're probably seeing here is a slight increase in a type of cancer that doesn't cause many deaths.

This reminds me of the controversy about cell phones and brain cancer. The studies are contradictory and confusing, the argument goes back and forth, and the whole problem can be solved just by making moderate use of whatever the supposed carcinogen is, instead of overdoing it.

Johnson & Johnson introduced non-alcohol Listerine,
Maybe because of the Australian study

While pooh-poohing the cancer link, Johnson & Johnson has introduced Listerine Zero, an alcohol-free product. They're also embroiled in a lawsuit with the maker of a test to detect oral cancer.

If you go to a dentist regularly, you probably know the dental profession has gotten into the cancer detection business. In the course of your regular exam they subject you to a test to see if you've got cancer of the mouth.

Well, a Johnson & Johnson subsidiary entered into a sales agreement with the manufacturer of one such test, with the idea that J&J's nationwide sales force would sell the oral cancer test to dentists. J&J promised its partner a huge roll-out. As part of the exclusive sales agreement, the J&J outfit required the other party to get rid of its own sales force and terminate other distribution deals.

But, what do you know, J&J did almost nothing to market the test, the suit alleges. In the year following the agreement, J&J's sales team, numbering more than 100, sold less than half as much product as the other party's tiny four-person sales team had sold in the six months before J&J entered the picture.

According to the lawsuit, a J&J Consumer Product Vice President named Jim Murphy allegedly told the other company that J&J "was leery of highlighting the risk of oral cancer and was worried that if [its subsidiary] were to sell both Listerine and OralCDx [the cancer test], it would lend credence to the link between Listerine and oral cancer, and could be construed as a tacit acknowledgment by J&J of the validity of the conclusions of the Australian oral cancer study." All of this was taking place around the time J&J launched Listerine Zero, the new alcohol-free product.

The plaintiff in this suit seems to think J&J deliberately tried to bury its cancer test because it would appear J&J was admitting Listerine may indeed cause cancer.

The suit alleges, "Listerine Zero was carefully branded to conceal the fact that it was developed primarily in response to the Australian mouthwash oral cancer study and the subsequent sales drop in Listerine's Australian sales. The advertising for that product makes no mention of the fact that it may reduce the risks associated with mouthwashes containing alcohol and instead emphasizes only its 'less intense' flavor."

J&J's comment on all this was that "The company is confident that we have engaged in proper business practices and we look forward to the opportunity to resolve this matter through the legal system."

Common sense from an average citizen. . .

One blogger commented, "If they come out and say that the new product is to reduce the cancer risk — they'd open themselves up to liability for past users." That sounds about right. Instead, they quietly introduce an alcohol-free product while denying they've ever done anything wrong. And maybe, just maybe, they decided that it would look bad for them to market a test to detect oral cancer.

Moderate use of alcohol-containing mouthwashes is probably pretty safe, especially if you don't smoke and you drink alcohol only moderately. The mouthwashes are probably not a huge cancer risk for nonsmokers. It's probably a greater risk to drink wine, beer or spirits every day or several times a week.

There are about 35,000-40,000 cases of mouth and throat cancer every year in the United States and somewhat more than 8,000 deaths.

That's roughly similar to the number of deaths from skin cancer, and far fewer than the number of deaths from the major cancers, the ones you need to worry about most: colon, breast, prostate, lung, pancreas, liver. If detected early, mouth and throat cancer is reportedly pretty easy to cure, even by the incompetent methods of conventional medicine. And if you go to a dentist regularly, one who uses the cancer test, you've got a pretty good shot at early detection.

Best regards,

Lee Euler,
Publisher