Look, Mom--no cavities!

July 01, 2008

In the early 20th Century, a Colorado dentist noted a curious phenomenon: Almost all of the children he saw in his practice had stained or mottled teeth. The good news was that they had very few cavities. It turned out that both were caused by a high concentration of naturally occurring fluoride in the area's drinking water.

In severe cases, the condition now known as dental fluorosis causes cracked or pitted teeth; a related condition called skeletal fluorosis causes damage to bones and joints. Researchers concluded, not surprisingly, that megadoses of fluoride are not a good thing. But the far more significant finding was that modest levels of fluoride can help prevent tooth decay.

Today, more than two-thirds of Americans live in communities that add fluoride to their drinking water. The results are unimpeachable. In generations past, it was rare to make it to young adulthood without a mouthful of fillings. Now, almost 60 percent of kids ages 6 to 19 have never had a cavity at all.

Still, there have long been people who saw something nefarious in fluoridation. The madman protagonist of the 1964 film "Dr. Strangelove, or: How I Learned to Stop Worrying and Love the Bomb" declared fluoridation a Communist plot to "sap and impurify" Americans' bodies, but the script writers didn't fabricate that fantasy; they were merely repeating a crank rumor that wouldn't die. This and other shaky claims led many communities to resist fluoridation long after its benefits were well-established.

In recent years the anti-fluoride backlash has gathered steam. The notion of government medicating the water supply still doesn't sit well with some people. Others worry that fluoride causes cancer, attention deficit disorder, Down syndrome or infertility, or that it can lower the IQ.

The evidence for all of these is pretty skimpy, especially when placed alongside more than 60 years of documented cavity-fighting success. The U.S. Centers for Disease Control and Prevention ranks fluoridated water among the top 10 health achievements of the last century, right up there with vaccinations and control of infectious diseases. The American Dental Association, the American Medical Association, the World Health Organization and the CDC all stand solidly behind fluoridation.

That's not to say the science can't or shouldn't be refined. Researchers at the University of Iowa School of Dentistry have been following a group of children for more than 16 years to study the effects of fluoride. One concern is the uncertainty over how much fluoride is obtained from other sources, including non-organic produce, processed meats, juices, soda and, of course, toothpaste. While the researchers still support fluoridation, they suspect that very young children are getting more fluoride than they should.

In 2006, a National Research Council committee said infants and toddlers who drink fluoridated water get twice as much fluoride as they should, and others who drink lots of water -- athletes and construction workers, for example -- probably get too much too. The NRC study also found worrisome thyroid changes that it said bear more study. And it recommended the U.S. Environmental Protection Agency lower the maximum "safe" dose of fluoride from 4 parts per million to 2 parts per million. That's far more fluoride than any community is adding to its water supply -- most are less than 1 part per million -- but there's still that troublesome question of how much fluoride we're ingesting from other sources.

This is real science, not the musings of "Dr. Strangelove." But it's also fanning the passions of those who think fluoridated water is going to make us all grow a second head. A growing number of communities are opting out of fluoridation, or arguing about it. This is a very bad idea. After decades of steady improvement, the incidence of cavities is again rising among children ages 2 to 5, according to the CDC. The increase is attributed to a lack of access to health care and too many sugary snacks. Some also blame our taste for bottled water, which doesn't contain fluoride.

Some communities have already scaled back the amount of fluoride added to their water, and scientists are hard at work trying to determine the optimum dose. It may be that some calibration is in order. But there's next to zero evidence that suggests we should stop fluoridating altogether. Until there's a lot more of it, the anti-fluoride crowd should bite its tongue.