A growing number of communities are choosing to stop adding fluoride to their water systems, even though the federal government and federal health officials maintain their full support for a measure they say provides a 25 percent reduction in tooth decay nationwide.

Last week, Pinellas County, on Florida’s west coast, voted to stop adding fluoride to its public water supply after starting the program seven years ago. The county joins about 200 jurisdictions from Georgia to Alaska that have chosen to end the practice in the last four years, motivated both by tight budgets and by skepticism about its benefits.

Eleven small cities or towns have opted out of fluoridating their water this year, including Fairbanks, Alaska, which acted after much deliberation and a comprehensive evaluation by a panel of scientists, doctors and dentists. The panel concluded that in Fairbanks, which has relatively high concentrations of naturally occurring fluoride, the extra dose no longer provided the help it once did and may, in fact, be harmful.

It is a view that also was shared by four out of seven commissioners in Pinellas County who first raised the proposal as a cost cutting measure.

“I’m in opposition to putting a medical treatment into the public drinking water supply without a vote of the people who drink that water,” said Norm Roche, a newly elected Republican county commissioner who spent 10 years doing policy research for the county Water Department and who led the turnaround effort. “We had a dozen to 15 doctors, dentists, dental hygienists and chemists here who want us to continue this practice but who could not agree themselves on how best to use fluoride.”

Some 700,000 people — 75 percent of the county — will be affected by the vote. The rest receive water from a different source.

But the United States Public Health Service and the Centers for Disease Control and Prevention say that the communities that stop adding fluoride to the water supply are misguided. The government continues to recommend the practice, which began in the 1940s and has had its share of recent successes, including San Diego’s move to fluoridate water this year after a long delay. Some 72 percent of the population in the country drinks water with added fluoride.

Keeping fluoride in water is especially important today because many people cannot afford dental care, public officials say.

“We have had big wins and significant losses,” Dr. William Bailey, chief dental officer for the Public Health Service and acting director for the Centers for Disease Control and Prevention’s division of oral health, said about the skirmishes over fluoridation. “Fluoridation helps people of all ages and income groups. And it helps people who can’t get in to receive care.”

The movement to stop fluoridating water has gained traction, in large part, because the government has recently cautioned the public about excessive fluoride. A report released late last year by the Centers for Disease Control and Prevention linked fluoride to an increase among children in dental fluorosis, which causes white or yellow spots on teeth. About 40 percent of children ages 12 to 15 had dental fluorosis, mostly very mild or mild cases, from 1999 to 2004. That percentage was 22.6 in a 1986-87 study.

Fluorosis is mostly a cosmetic problem that can sometimes be bleached away. But critics argue that spotted teeth are a warning that other bones in the body may be absorbing too much fluoride. Excessive fluoride can lead to increases in bone fractures in adults as well as pain and tenderness.

“Teeth are the window to the bones,” said Paul Connett, a retired professor of environmental chemistry and the director of the Fluoride Action Network, which advocates an end to fluoridated water.

Experts say that one possible factor in this increase may be that fluoridated water is consumed in vegetables and fruit, and juice and other beverages as well as tap water. And the consumption of beverages continues to increase.

In January, the federal Department of Health and Human Services recommended reducing the fluoride put into the water supply to 0.7 milligrams per liter of water. The longtime standard had ranged from 0.7 to 1.2 milligrams per liter. At the lowest level, the risk of fluorosis is decreased, the government says.

The government also informed parents of infants who exclusively use infant formula reconstituted with fluoridated water that their children face an increased risk of fluorosis and suggested they use low-fluoride water, like distilled water, some of the time. “It was a trigger,” said Mr. Connett. “People who had heard there is nothing wrong with fluoridation all of the sudden are hearing that kids are getting too much fluoride.”

Money worries and a growing distrust of government have also helped invigorate the movement. With the recession squeezing budgets and the cost of fluoride increasing (some fluoride is imported), communities have been more willing to take a look at the issue.

For decades, the issue of fluoridated water remained on the fringes. The John Birch Society took up the cause, seeing fluoride as a communist plot to poison the nation. References to Nazis using fluoride to pacify prisoners in concentration camps — a claim that was never proved — circulate even today. At least one person at the Pinellas County meeting made reference to both the Soviets and the Nazis.

But as more places, like Fairbanks and parts of Canada, take up the issue in a more measured way, it is shifting away from conspiracy and toward the mainstream.

The conclusion among these communities is that with fluoride now so widely available in toothpaste and mouthwash, there is less need to add it to water, which already has naturally occurring fluoride. Putting it in tap water, they say, is an imprecise way of distributing fluoride; how much fluoride a person gets depends on body weight and water consumed.

Doctors, scientists and dentists, including Dr. Bailey of the Public Health Service, mostly agree that fluoride works best when applied topically, directly to the teeth, as happens with brushing.

“The fact that no one really knows what dosage a given person receives from fluoridated water makes the subject of benefits and harms very difficult to quantify,” said Rainer Newberry, a professor of geochemistry at University of Alaska, Fairbanks, who sat on the committee that studied the issue prior to the June vote in Fairbanks. “And this presumably explains the number of studies with diverging conclusions.”

But Kenneth T. Welch, a Pinellas County commissioner who voted to continue adding fluoride to the water, said he was stunned by the commission’s decision, saying it was pushed by Tea Party supporters. He called for another vote on Tuesday but the outcome was the same. Fluoridation will end in the affected areas of the county by Dec. 31. The county expects to save $205,000 annually from halting fluoride use.

“Political rhetoric won out over science and the best advice of our medical and dental community,” Mr. Welch said.

Written by Lizette Alvarezn and published in the New York Times, October 13, 2011.

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