Pinellas County commissioners voted 4-3 Tuesday to cease putting fluoride into their water, making it the largest urban county in Florida to discontinue the practice. The move will halt fluoride-injected water from reaching about 700,000 residents but does not include the city of St. Petersburg and three other cities, says Commissioner Ken Welch, who voted to keep fluoride.

Commissioner Norm Roche voted to end the fluoride treatment, saying it was a “social sort of program” the county should avoid, the St. PetersburgTimes reported.

Opponents such as the Fluoride Action Network say the fluoride could harm children and should not be administered by the government. “Fluoride is a toxic substance,” said Tea Party activist Tony Caso, the Times reported. “This is all part of an agenda that’s being pushed forth by the so-called globalists in our government … to keep the people stupid so they don’t realize what’s going on.”

Fluoride advocates, including the American Dental Association, insist the practice reduces cavities, especially among poorer residents who can’t afford dental care.

Welch says a few people at Tuesday’s meeting identifying themselves as Tea Party activists “hijacked” the issue, calling the practice a government attempt to “dumb down” residents and likening it to Soviet and Nazi practices. The ban was passed despite testimony of more than a dozen dentists and others advocating the practice, he says. “We’re going to pay a price for this for generations to come,” Welch says.

Judson Phillips, a founder of the Tea Party Nation, says the issue has not been widely discussed at the national level and he doesn’t know the activists who pushed for the ban in Florida. “It’s not a hot-button Tea Party issue,” he says.

Cities across the USA have been adding fluoride to their water since the 1940s as a way to prevent tooth decay and promote oral health, according to the Centers for Disease Control and Prevention. When the count was last taken in 2008, more than 195 million residents, or 72% of the U.S. population then, had access to optimally fluoridated water, according to the CDC.

The CDC named adding fluoride to public water one of the “Ten Great Public Health Achievements” of the 20th century.

Critics say fluoride can harm the enamel on the teeth of young children. More than 200 communities have stopped adding fluoride to water supplies in the past 10 years, according to a count by the Fluoride Action Network. During the same period, however, more than 300 communities began adding fluoride, says Edmond Hewlett, a professor at UCLA’s School of Dentistry and an American Dental Association spokesman.

Fluoride “reduces the risk of getting cavities. It’s highly available to everyone who drinks that water,” Hewlett says. “It benefits everyone.”