Fluoride in drinking water — credited with dramatically cutting cavities and tooth decay — may now be too much of a good thing. Getting too much of it causes spots on some kids' teeth.
A reported increase in the spotting problem is one reason the federal government will announce Friday it plans to lower the recommended levels for fluoride in water supplies — the first such change in nearly 50 years.
About 2 out of 5 adolescents have tooth streaking or spottiness because of too much fluoride, a surprising government study found recently. In some extreme cases, teeth can even be pitted by the mineral — though many cases are so mild only dentists notice it. The problem is generally considered cosmetic.
Health officials note that most communities have fluoride in their water supplies, and toothpaste has it too. Some kids are even given fluoride supplements.
The U.S. Department of Health and Human Services is announcing a proposal to change the recommended fluoride level to 0.7 milligrams per liter of water. And the Environmental Protection Agency will review whether the maximum cutoff of 4 milligrams per liter is too high.
The standard since 1962 has been a range of 0.7 to 1.2 milligrams per liter.
The Centers for Disease Control and Prevention reports that the splotchy tooth condition, fluorosis, is unexpectedly common in kids ages 12 through 15. And it appears to have grown much more common since the 1980s.
"One of the things that we're most concerned about is exactly that," said an administration official who was not authorized to speak publicly before the release of the report. The official described the government's plans in an interview with The Associated Press.
But there are other concerns, too. A scientific report five years ago said that people who consume a lifetime of too much fluoride — an amount over EPA's limit of 4 milligrams — can lead to crippling bone abnormalities and brittleness.
That and other research issued Friday by the EPA about health effects of fluoride are sure to re-energize groups that still oppose adding it to water supplies.
The American Dental Association released a statement applauding the government announcement to change fluoride guidance.
Fluoride is a mineral that exists naturally in water and soil. About 70 years ago, scientists discovered that people whose supplies naturally had more fluoride also had fewer cavities. Some locales have naturally occurring fluoridation levels above 1.2. Today, most public drinking water is fluoridated, especially in larger cities. An estimated 64 percent of Americans drink fluoridated water.
Portland, Ore., is one of the largest cities that doesn't fluoridate its water.
Bill Zepp of the Oregon Dental Association said the city's anti-fluoridation activists will embrace the recommended fluoride changes "as some type of win."
Maryland is the most fluoridated state, with nearly every resident on a fluoridated system. In contrast, only about 11 percent of Hawaii residents are on fluoridated water, according to government statistics.
Fluoridation has been fought for decades by people who worried about its effects, including conspiracy theorists who feared it was a plot to make people submissive to government power.
Those battles continue.
"It's amazing that people have been so convinced that this is an OK thing to do," said Deborah Catrow said Friday. She successfully fought a ballot proposal in 2005 that would have added fluoride to drinking water in Springfield, Ohio.
Reducing fluoride would be a good start, but she hopes it will be eliminated altogether from municipal water supplies.
Catrow said it was hard standing up to City Hall, the American Dental Association and the state health department. "Anybody who was anti-fluoride was considered crazy at the time," she said.
In New York, the village of Cobleskill in Schoharie County — west of Albany — stopped adding fluoride to its drinking water in 2007 after the longtime water superintendent became convinced the additive was contributing to his knee problems. Two years later, the village reversed the move after dentists and doctors complained.
In March, 2006, the National Academy of Sciences released a report recommending that the EPA lower its maximum standard for fluoride in drinking water to below 4 milligrams. The report warned severe fluorosis could occur at 2 milligrams. Also, a majority of the report's authors said a lifetime of drinking water with fluoride at 4 milligrams or higher could raise the risk of broken bones.
Late last year, lawyers for the Fluoride Action Network, Beyond Pesticides, and Environmental Working Group threatened legal action if the EPA did not lower its ceiling on fluoride.
In Europe, fluoride is rarely added to water supplies. In Britain, only about 10 percent of the population has fluoridated water. It's been a controversial issue there, with critics arguing people shouldn't be forced to have "medical treatment" forced on them. In recent years, the UK has tried to add fluoride to communities with the worst dental health but there's still considerable opposition.
In the early years of fluoridation in the United States, the range of levels was created because people in warmer climates drank more water, therefore getting more fluoride than cooler regions. Over time, that difference leveled out with air conditioning, the senior administration official said.
Fluorosis has generally been seen as the primary down side of fluoride.
According to the CDC, nearly 23 percent of children ages 12-15 had fluorosis in a study done in 1986 and 1987. That rose to 41 percent in the more recent study, which covered the years 1999 through 2004.
"We're not necessarily surprised to see this slow rise in mild fluorosis," Dr. William Kohn, director of the CDC's division of oral health, said in a recent interview.
Health officials have hesitated to call it a problem, however. In most kids, it's barely noticeable; even dentists have trouble seeing it, and sometimes don't bother to tell their unknowing patients.
Meanwhile, the U.S. prevalence of tooth decay in at least one tooth among teens has declined from about 90 percent to 60 percent. Health officials call water fluoridation one of the 10 greatest public health accomplishments of the last century.
"One of water fluoridation's biggest advantages is that it benefits all residents of a community — at home, work, school, or play. And fluoridation's effectiveness in preventing tooth decay is not limited to children, but extends throughout life, resulting in improved oral health," said HHS Assistant Secretary for Health Dr. Howard Koh, in a statement.
Indeed, many health leaders continue to be worried about cavities, particularly among poor families with kids who eat a lot of sweets but don't get much dental care.
Secretary Kathleen Sebelius could make a final decision on details of the changes within a few months, the administration official said.