WATERLOO — Pay attention to this word, fluoride. You may soon hear it a lot.

A decades-old controversy, out of public view for years, has erupted anew. Critics are once again attacking the fluoridation of drinking water. A public referendum is planned for Nov. 8, 2010.

The last time this was an issue here, Pierre Trudeau was prime minister, music was recorded on vinyl, and Great Britain was warring with Argentina. It was 1982.

The players have changed. The arguments haven’t.

Fluoride is added to water as a public health measure to help prevent tooth decay. This is common in Ontario, endorsed as safe and effective by a long list of health groups.

The U.S. Centers for Disease Control has called it one of the top 10 public health achievements of the last century.

But locally, Waterloo is the only city to add fluoride to its water. The same fluoridated water is also sent to St. Jacobs and Elmira in Woolwich Township, to a small portion of Kitchener, and to a few houses in Wilmot Township. They all share a water system.

Here’s what you can expect to hear in the coming months:

• Proponents will say the weight of the credible science strongly shows that adding fluoride strengthens tooth enamel and limits cavities, with no known health risks.

• Critics will claim the chemical used to fluoridate water is a threat. They will dismiss scientific assertions that fluoridation is sound. They will allege health risks including cancer, bone disease and dental damage.

• Fluoride proponents will in turn dismiss their assertions as scientifically unfounded.

While you ponder these competing health claims, it will become clear that disputes over science are just one part of the controversy. It’s also about personal rights, passionate opinions, and the fairness of the referendum process.

The last time this debate erupted, Waterloo was put on a rollercoaster.

The city has fluoridated its water since 1967. In 1981, critics forced a first referendum to get it out.

Neighbours erected competing lawn signs. People called each other names. A leading pro-fluoride campaigner said she was threatened anonymously.

“It was quite nasty,” recalls Marjorie Carroll, Waterloo’s mayor at the time.

Carroll supports fluoridation. She recalls being sent a postcard written in letters snipped from publications, like a ransom note from a kidnap caper. It said: “A fist in the face to you.”

Residents were asked to vote on an awkward question not written in plain English: “Are you in favour of the discontinuance of the fluoridation of the public water supply of this municipality?”

Mary Jane Mewhinney, on city council at the time, campaigned against fluoride. She contends it’s a violation of personal rights to force everyone to drink it.

“I was just very upset by the fact that you didn’t have a choice,” she recalls.

Fluoride critics lost the bitter 1981 referendum by just 313 votes. Undaunted, they pressed for a second referendum, held just 17 months later.

For the second vote, fluoride proponents pursued a low-key campaign, calculating it would be foolish to get into another shouting match.

Both sides adopted a more civil tone, Carroll recalls. Unlike the first referendum, the second vote was held during a municipal election. This put fluoride on a longer list of issues for the public to ponder.

In 1982, the pro-fluoride margin swelled to 2,838 residents. Fluoridation critics conceded a decisive defeat.

The issue fell out of public view, until Waterloo Coun. Angela Vieth revived it almost three decades later.

“I’m just pleased that it’s going to be brought up again,” Mewhinney said.

“I’m really quite surprised that this has come up again,” Carroll said.

Vieth has been unable to persuade council to stop fluoridating water. But her determined opposition to the practice has led to another public referendum, to be held during the next municipal election.

“We’re adding toxic waste to our perfectly fine drinking water,” Vieth said.

She’s persuaded fluoride has damaged the health of some residents. “I’m convinced that we shouldn’t be doing this. People are suffering because of it. We need to turn it off,” she said.

Coun. Karen Scian sees the debate as a controversy foisted on the public by one determined councillor who has limited community support.

She winces at the language used by Vieth and other critics to attack fluoride.

“You’re going to hear lots of words like toxic soup and poison and all sorts of things from the other side of the story,” Scian says. “It’s inflammatory.”

Scian is persuaded fluoridation is safe, effective and supported by science.

The latest Waterloo referendum is part of a wave of antifluoridation campaigns launched since 2008 in Ontario.

Several councils, including Hamilton, have voted to continue with fluoridation. Other councils, including Niagara and Thunder Bay, have balked at fluoridation.

Vieth points out the looming referendum on fluoride is unlikely to bind politicians. That’s because voter turnout is unlikely to exceed 50 per cent, the threshold required by law to make it binding.

“To me, it’s a waste of time, it’s a waste of effort, it’s a waste of money,” Vieth said.

She’s not reassured by the local tradition of respecting referendum results.

The public health department endorses fluoridation.

Authorities point to a rate of tooth decay among Waterloo schoolchildren at 32 per cent. That’s below the rate of 33 per cent in Cambridge and below the rate of 44 per cent in Kitchener, according to a 2006 study.

“It is a safe and effective way to prevent tooth decay, for a large number of people at a low cost,” said Dr. Liana Nolan, medical officer of health. “And there’s no known health risks associated with drinking fluoridated water within the recommended levels.”

Dr. Harry Hoediono, a Waterloo resident who practises family dentistry in Kitchener, says he sees far more tooth decay among the Kitchener children he sees than among Waterloo children.

He accuses fluoridation critics of practising a “misinformation campaign” that’s not based on credible science.

But if fluoridation is so safe and effective, why are authorities not pressing to also add it to drinking water in Kitchener and Cambridge?

“It’s my role to promote community water fluoridation,” Nolan said. “It’s not my role to force that on people.”

Kitchener residents voted against fluoridation in 1958 and again in 1967. The last result was 42 years ago, when the Beatles ruled the radio and before man walked on the moon.

Today, about a third of Kitchener residents wrongly believe their water is fluoridated, a public health survey found.

“We do know there is some confusion in the public’s mind,” Nolan said.