The Sebastopol City Council voted unanimously Tuesday night to join the city of Cotati in opposing fluoridation of Sonoma County’s drinking water, even if its own water supply would not be directly affected.

The 5-0 vote came despite a written, last-minute plea from county Board of Supervisors Chairman David Rabbitt, who asked the council to hold off on its discussion pending the completion of ongoing engineering, financial and wildlife studies related to the fluoridation proposal.

Study findings should be available later this year, in addition to results from an upcoming survey of local kindergarten and third-grade students and what they reveal about what Rabbitt called “a ‘silent epidemic’ of dental disease.”

“It is the Board of Supervisors’ opinion that to weigh in without the benefit of the information from these actions would be imprudent,” Rabbitt wrote.

The county is considering fluoridation as part of a multi-pronged effort to address an incidence of tooth decay that exceeds the state average, according to a 2009 county survey of local school kids.

The 2009 survey found that more than half of Sonoma County third-graders had a history of dental decay, local health officials said.

Fluoride, a chemical compound, has been introduced in small amounts into the U.S. drinking supply since 1945 to improve dental health. Three-quarters of Americans on community water systems now get fluoride in their water.

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.”

But a growing chorus of skeptics across the country opposes fluoridation as both unnecessary and potentially dangerous. Among the various evidence they cite are warnings even on toothpaste tubes that caution against ingesting too much of the product.

The city of Sebastopol has an independent groundwater system and would not be directly affected by fluoridation of drinking water provided by the Sonoma County Water Agency to about 350,000 Sonoma County consumers.

City officials have nonetheless raised concerns about fluoride leaching into local waterways and are opposed to paying for treatment of fluoride-tainted wastewater through their partnership in the regional waste water treatment system.

Members of the public, including two local dentists, also challenged the efficacy of fluoridated water in fighting tooth decay. They voiced concerns about the potential affects on thyroid function and other health factors, and raised the specter of environmental pollution from wastewater still tainted with fluoride, as often happens with other pharmaceuticals that pass through treatment processes.

Councilman Patrick Slayter said Tuesday that divining the truth between competing opinions on fluoride was beyond his ability at present, but said he had a definite issue with the fact that consumers of fluoridated water would have no choice in the matter.

His colleagues on the council agreed.