The decision about whether to continue to add fluoride to the Oak Bluffs water supply will be put to town voters this spring.

Tuesday morning, the board of health voted unanimously to poll residents on the fluoridation question in a nonbinding resolution on the spring town election ballot.

“I just think that everybody needs to vote . . . it’s the people deciding and that is how government is supposed to work in my opinion,” said board member Patricia Bergeron.

The Oak Bluffs water district has been fluoridating the public water supply since April 1991, and is the only town on the Island to fluoridate its water supply.

The board of health brought the issue to the table earlier this year, and began discussing the practice with the water district, which adds fluoride to the water supply at each of the four major pumping stations. The board of health voted to fluoridate the water in 1987, although the actual practice began in 1991 with a $32,000 state public health prevention block grant, according to Gazette archives.

Board of health member John Campbell, who opposes fluoridation, suggested on Tuesday that the water district stop adding fluoride in advance of the vote, in order to return the choice to the public.

But his fellow board members declined that motion, saying they preferred to stick with the status quo until the ballot vote.

Ms. Bergeron said stopping fluoridation now would send a message to the town that the board had already decided.

“I think we are forcing an opinion on the people if we take it out,” she said. “It’s not up to us to take it out, it’s up to the people.”

Further, she said the fluoride had been present in the water supply for many years.

“It’s not going to kill anybody in the next few months,” she said.

“We do not know that,” Mr. Campbell said.

Of the 351 municipalities in the commonwealth, 140 fluoridate at least part of their public water supply, roughly 40 per cent.

Island dentists have defended fluoridation, a practice they say has far-reaching health benefits for adults and, especially, children. They say it lowers the incidence of cavities in the community, providing protection to the teeth of even those who cannot afford dental care.

But other community members warned that fluoride can be harmful, and that fluoridating the public water supply denies people the right to choose.

A public hearing in late September featured spirited debate between the two sides.

Ms. Bergeron said she was surprised by the intensity of some of the residents.

“I really was shocked at the intensity and the viciousness of people opposed to fluoride,” she said.

Board chairman William White agreed that tensions ran high at the hearing.

“There was a lot of passion on both ends, pro and con, for and against,” he said.

Mr. White said that if he were to vote this week, he’d support the removal of fluoride. Ms. Bergeron said she would vote to continue fluoridation.

The question will ultimately be decided by the board, which will take a final vote after ballots are cast this spring.

Despite his strong feelings in opposition to fluoridation, Mr. Campbell joined the others in a pledge to represent the wishes of the townspeople.

“I have no problem with the people deciding their own fate,” he said. “That is the whole purpose of bringing this up.”