A move to add fluoride to most of Sonoma County's drinking water to improve dental health received a significant boost Tuesday from the Board of Supervisors.
The board's unanimous decision backing further study of a practice common across the country and recommended by leading national and international health agencies still provoked emotional protests from some speakers.
They proclaimed fluoride a health danger and decried government tinkering with the water supply, comments that drew unusually sharp rebukes from two supervisors.
"While I respect everyone's right to free speech, the hyperbole shared today was off the charts. Off the charts," Supervisor Mike McGuire said.
His response came after several speakers alluded to fluoride's addition to water systems in Europe last century, a move that one speaker said was used for "mass mind control" by totalitarian regimes in Germany and the Soviet Union.
Another called fluoride a "witches' brew of pollutants" in the U.S. water system.
"You don't improve the health of children by giving them poison," said Deborah Tavares, a frequent board critic active in property rights issues.
McGuire called the claims "scare tactics" and the theories "an absolute insult" to a proposed initiative aimed at combating an epidemic of dental decay.
Supervisor David Rabbitt linked the comments to arguments put forward by opponents of vaccines.
"Vaccines, fluoride. They're not poison," he said. "I sit up here and I'm bewildered because as a society we're now living longer than ever, thanks to those vaccines, thanks to fluoride for our teeth. That's a fact."
The protests came from 10 speakers, some of them regular board critics and others who have rallied around property rights and against land-use planning efforts.
They turned a largely procedural update about an ongoing county oral health initiative into a battleground over science and a forum for theories about fluoride's worth.
The compound has been introduced in small amounts into the U.S. drinking supply since 1945 to improve dental health.
The practice has been backed by the Centers for Disease Control and Prevention, the U.S. Surgeon General, the World Health Organization and the American Dental Association, which called water fluoridation "the single most effective public health measure to prevent dental decay."
Today, 72.4 percent of the nation's population — or about 196 million people — served by public water systems are receiving fluoridated water.
In Sonoma County, the only fluoridated water is delivered to residents of Healdsburg and the adjacent Fitch Mountain area.
For several years the county has been studying the addition of fluoride for nearly three quarters of the county, including 350,000 residents served by the Sonoma County Water Agency in Windsor, Santa Rosa, Rohnert Park, Cotati, Petaluma, Sonoma and the Valley of the Moon.
Supervisors signaled Tuesday they consider that move an imperative to deal with what they described as a growing teeth care crisis, especially among lower-income families.
A 2009 county survey found that 52 percent of Sonoma County third-graders had a history of dental decay, exceeding the state average.