HILLSBORO — The City Council meeting on Tuesday could turn into a scientific debate over the city’s water supply and children’s health.

Even before a children’s advocacy group plans to ask officials to fluoridate Hillsboro’s water, an opposition group is mounting a campaign to keep the chemical out.

Stand for Children, a national grass-roots volunteer organization with a Hillsboro chapter, will ask the council Tuesday night to place a measure on the Nov. 5 ballot to fluoridate city water.

But Beaverton Citizens for Safe Drinking Water, which has formed to oppose a similar plan in Beaverton that will be discussed Monday night, also will fight the effort in Hillsboro.

Beyond the arguments over health benefits, fluoridating the city’s water raises a host of legal and technical questions.

If city voters approve such a measure, will Hillsboro’s wholesale customers in Cornelius, Gaston and the L.A. Water Cooperative, in the Laurelwood area, get fluoridated water without any say?

If city voters turn down fluoridation, what happens to residents of east Hillsboro who already get fluoridated water from the Tualatin Valley Water District?

And if Hillsboro voters approve fluoridation, but Beaverton rejects it, how will Hillsboro add fluoride to a system that uses the same pipes for the two cities?

Laurie Johnson, a dental hygienist and Stand for Children member who lives in Aloha, said it’s clear that people who use fluoridated water have stronger teeth. In particular, it would help low-income children who don’t have access to proper dental care and the elderly, who are susceptible to decay because of medications that limit their saliva, which prevents disease.

“The research shows that fluoridation is the most important way of preventing decay in a community,” she said.

Johnson understands hesitancy to put chemicals in drinking water.

“But we can’t throw out the baby with the bath,” she said. “When we see something that benefits people’s health, we should use it.”

Most Hillsboro council members seemed to favor adding fluoride. But Mayor Tom Hughes said he is reluctant to place the measure on the Nov. 5 ballot, because city voters already face a local-option tax renewal, a library construction bond measure and countywide measures on library operations and fairgrounds redevelopment. Hughes doesn’t want to see fluoridation get lost in the mix.

Instead, he would rather see it on the ballot early next year.

Councilor Karen McKinney, who has a background in public health, said she grew up in Indiana with fluoridated water. She came to Oregon as a 22-year-old with only one filling. But without fluoride in the water here, she had to get five or six fillings within the first three years.

City Manager Tim Erwert, however, is not enthusiastic about adding fluoride. He points out the additional cost, which the city has not calculated, and the technical challenges. With alternatives such as fluoridated toothpaste and fluoride rinses available, he questions the wisdom of imposing fluoride on everyone.

“The main question is whether it should be a matter of choice,” Erwert said. “Once you put it in, it’s difficult to get it back out.”

Erwert is not eager to tackle such a divisive issue. “We don’t like that,” he said.

Alternatives suggested

Claire Darling, a founder of Beaverton Citizens for Safe Drinking Water, said she will try to convince the Hillsboro council that ingesting fluoride is not the way to prevent cavities. Instead, topical treatments such as tooth sealants, xylitol gum and fluoride rinses are more effective, Darling said. In addition, reducing sugar in the diet and providing dental hygiene education should be priorities.

“We don’t need to throw money at a solution that doesn’t work,” Darling said.

Opponents also point to the cumulative buildup from other sources of fluoride that, taken together with fluoridated drinking water, could lead to more fluorosis, a condition caused by too much fluoride that results in stained and pitted teeth.

And opponents question the effects on fish and other wildlife of the fluoride that gets into streams.

The Hillsboro council decision — and a vote of its residents — could affect water customers beyond Hillsboro.

Cornelius buys its water from Hillsboro. Cornelius City Manager Dick Kline said he hasn’t talked to Hillsboro officials about the possibility of the water being fluoridated but trusts that they will be sensitive to Cornelius’ concerns.

“I don’t feel like we’re in the driver’s seat, but I’m sure they would contact us and involve us,” Kline said.

Local opposition in Portland and Eugene regularly trumps supporters’ assertions that fluoridation brings health benefits and no proven harm. In four of the Legislature’s past five sessions, bills to require local fluoridation have died.

Portland, where voters first approved fluoridation and then voted it out in 1978, is one of only two among the nation’s 30 most populous cities where water is not fluoridated.

Oregon ranks low on fluoridation

A tally by the Atlanta-based U.S. Centers for Disease Control and Prevention confirms that fluoridation has long gained more converts outside Oregon than in it. Among 50 states and the District of Columbia, Oregon’s 22.7 percent ranked 46th in the proportion of residents served by public water systems who receive fluoride from them.

In the tally, published last year by the Centers for Disease Control, the statewide proportions ranged from 98.2 percent fluoridated for Minnesota to 2 percent for Utah. The nation’s capital was at 100 percent.

In Washington County, the proportion is about 47 percent, supplied by Tualatin Valley Water District and Forest Grove.

Although buying most of its water from Portland, the Tualatin Valley district has fluoridated most of its water since voters north and west of Beaverton approved the step in 1963.