Water is essential to our existence. We guzzle it down when exercising, mix it into our baby’s cereal and cook our family’s meals with it. It makes up 60 per cent of our bodies, 95 per cent of our blood and 22 per cent of our bones.

Without fresh drinking water, we’d die within days. No wonder we feel so passionate about its safety.

Fluoridated water — the kind that has poured from Hamilton taps since 1966 to prevent tooth decay — has become a hot-button issue now that city councillors must decide whether to continue adding it to our water.

Equipment needs to be replaced at the water treatment plant at a cost of $2.1 million. Rising chemical prices will bring annual costs to $1 million.

If the city stopped fluoridation, public health advocates say it would need to be replaced with dental programs to ensure residents living in poverty receive care. The program could cost anywhere from $250,000 to $1.8 million depending on its scope. Staff are looking into options and plan to report back next month.

Most health professionals in North America strongly support fluoridating community water. The U.S. Centers for Disease Control identified it as one of 10 great public health achievements of the 20th century.

Yet attitudes may be starting to shift. A small but growing number of environmentalists and health-care professionals are lobbying local governments to stop adding fluoride to public water supplies. Activists worry we’re ingesting too much fluoride through municipal water, food, drinks and dental products, creating health risks, including bone fractures, impaired thyroid function and lower intelligence.

Some recent research — considered tentative — suggests fluoride may be connected to the development in teenage boys of osteosarcoma, the rare bone cancer that killed Canadian hero Terry Fox. A further larger-scale study is pending from the Harvard School of Dentistry.

Both sides agree that consistent exposure to too much fluoride can cause dental fluorosis in children — the discolouring and disfiguring of emerging adult teeth.

Earlier this month, the Canadian Association of Physicians for the Environment (CAPE) issued a statement saying its members do not support water fluoridation, calling it unnecessary and potentially harmful. CAPE consists of nearly 3,500 health-care professionals and concerned citizens across Canada. About 60 per cent are medical doctors.

CAPE’s statement is applauded by anti-fluoride activists such as Waterdown resident Cindy Mayor, who blames her thyroid condition on fluoridated water. She now buys distilled water for drinking and cooking.

Mayor — a bookkeeper who also owns an office cleaning business — dedicates 30 to 40 hours a week researching water fluoridation and lobbying to have it removed from drinking water across Canada.

Mayor has no issue with topical fluoride treatments and fluoridated toothpaste to fight tooth decay. It’s the “mass medication” of people in fluoridated communities that worries her.

“It’s just so immoral and unhealthy,” says Mayor, who makes her views known through People for Safe Drinking Water, an anti-fluoride lobbying group.

Mayor also questions the cost-effectiveness, since the vast majority of our city water swirls down the drain as we shower and wash our clothing, dishes and cars.

Health professionals supporting her concerns include Dr. Hardy Limeback, associate professor and head of preventative dentistry at the University of Toronto’s faculty of dentistry.

Limeback was an outspoken opponent several years ago, and then faded away from the debate.

“I spent too much time defending my position,” says Limeback, who also spent three and a half years on a U.S. National Academies of Sciences committee that produced an extensive review in 2006 on fluoride toxicity. That report found the Environmental Protection Agency’s limit for fluoride in drinking water — four milligrams per litre — should be lowered because of potential health risks.

“Being publicly opposed to fluoridation hurt my academic career,” says Limeback. “I decided to focus more on teaching, dental practice and research, but I never completely stopped my activities on educating communities that wanted to hear more about fluoride toxicity.”

Limeback’s concerns include the use of acid or salt of hydrofluosilicic acid (HFA) to fluoridate drinking water. Most North American cities with fluoridated water — including Hamilton — use the acid or salt of HFA.

It is obtained directly from smokestack scrubbers when phosphate-rich soil is boiled with sulphuric acid and a fluoride-rich acid is produced.

“It is toxic, even in small amounts,” says Limeback. “For one thing, they do not bother to remove the heavy metal contaminants such as arsenic and radium that are carcinogenic at very, very low amounts (part per billion). HFA has never been tested for safe ingestion in humans. No government agency or researcher has ever looked for ill health effects in humans.”

However, most North American health professionals continue to support fluoride — including HFA — as a safe, cost effective and highly efficient public health measure.

“The big advantage of water fluoridation is that it benefits all residents in a community, regardless of age, socioeconomic status, education or employment,” Dr. Peter Cooney, Health Canada’s chief dental officer, writes in an open letter, dated July 30, on the Health Canada website.

The long list of supporters includes Health Canada, the Canadian Dental Association, the Canadian Pediatric Society, and the World Health Organization.

Dr. Chris Mackie, Hamilton’s associate medical officer of health, believes anti-fluoride lobbyists are quoting information from faulty studies.

While Mackie concedes there can never be 100 per cent certainty in science, he says: “Every time there has been a systematic examination of all the evidence, it has … said that fluoride is good for your teeth, it doesn’t cause cancer and it doesn’t cause developmental delays.”

An expert panel commissioned by Health Canada reported in June it did not find a link between fluoridated water and health concerns such as cancer, low intelligence and bone fractures. (The report’s findings and recommendations don’t mention thyroid.)

It recommends the continued use of fluoridated water, while taking steps to reduce fluorosis in children including decreasing slightly the amount of fluoride that can be added to municipal drinking water from 1.5 milligrams per litre to 0.7 mg/L. (Hamilton’s target for water fluoridation is already 0.7 mg/L). The report also recommends encouraging the availability and use of low-fluoride children’s toothpaste and suggesting to makers of infant formula fluoride levels in their products be reduced.

There was no evidence to suggest children should avoid drinking fluoridated water at the accepted levels in Canadian drinking water supplies. “The report overall is a strong endorsement of fluoridation of water,” says Mackie.

Supporters and opponents all point to the steep decline in tooth decay over the last half century as proof they’re right. Supporters say the decline is directly related to fluoridated water, while critics believe it has more to do with such things as better dental care, fluoridated toothpaste and diet. Decline in tooth decay also occurred in areas where water was not fluoridated.

The increased use of sugar substitutes and diet foods, better nutrition and an increase in access to dental care could be factors, says the University of Toronto’s Limeback.

“With our obsession with white, polished teeth and fresh breath, good oral hygiene has become ingrained in minds of even the poorest of people living in North American communities. Studies have shown that even people who frequent food banks regularly brush their teeth with toothpaste supplied at the food banks.”

The debate is a long-standing one, often as emotionally charged as it is based on science.

In the 1950s and 1960s, some opponents argued fluoridated water was a communist plot to control the population.

“It was a passionate issue when I started in public health in the late 1970s, says Dr. David Klooz , associate commissioner of Niagara Region Public Health.

He believes scares such as the Walkerton water scandal are partly responsible, as well as concerns over air quality and the environment.

Anti-fluoride lobbyists are realizing some successes. While municipal councils typically listen to the advice of their experts when making decisions, earlier this year, Niagara regional council voted not to add fluoride to its drinking water even though its local medical experts, including Klooz, recommended it.

Klooz believes infrastructure costs — combined with messages from anti-fluoride lobbyists — influenced council’s decision.

Other municipal councillors face a similar decision.

Waterloo voters will be asked in the 2010 election whether they want to keep fluoride in the drinking water.

In April, residents of Dryden voted against fluoride in their drinking water.

Special to The Hamilton Spectator, with Spectator files

The debate:

* Hamilton council must decide whether to continue adding fluoride to our drinking water because equipment at the water treatment plant needs to be replaced.

* Staff have been asked by council to provide information on the cost of targeted dental programs that would allow Hamilton to stop adding fluoride to its water. That report will to go to the board of health on Nov. 24.

What’s being said:

* “The medical officer of health and associate medical officer of health are very definitive that fluoride should stay in the water so it’s difficult for a councillor to take a position independent of the medical doctors we have here in Hamilton,” says Councillor Brian McHattie.

Even so, information being sent to him by anti-fluoride lobbyists is causing him to question fluoride’s safety. “I’m a little uncertain but I’m leaning towards wanting to see it removed.”

* Councillor Bob Bratina wonders if money could be better spent on topical fluoride treatments to prevent tooth decay. “I’m always concerned when we mass medicate.”

* Mayor Fred Eisenberger remains a strong supporter. “I believe we should continue adding fluoride to the water. This is because the socio-economic cost of not doing so would be greater for the majority of the citizens of Hamilton.”

The facts:

* Water fluoridation is the process of adjusting the level of fluoride in water to prevent tooth decay.

* Fluoride was first added to municipal drinking water in the 1940s in some North American cities. Hamilton has added it since 1966.

* About 45 per cent of Canadians have access to fluoridated water, according to Health Canada.

And fiction:

* In Stanley Kubrick’s 1964 cult classic Dr. Strangelove, an insane U.S. general plans to start a nuclear war with the Soviet Union to stop a Communist conspiracy to put fluoride in the water supply.

Across Ontario

Niagara Region: Welland, Pelham and parts of Thorold got fluoridated water in the mid-1960s. That lasted until 1999 when it was stopped due to infrastructure issues with treatment plants.

In February council said no to fluoride for the entire region. Dr. David Klooz, the associate commissioner for Niagara Region Public Health, believes that infrastructure costs combined with efforts by anti-fluoride lobbyists influenced council’s decision.

Waterloo: Waterloo Watch, a grassroots anti-fluoride group, is based here and members are aggressively lobbying against fluoride.

Waterloo Region fluoridates the water in Waterloo and parts of Woolwich Townships. Kitchener water doesn’t have fluoride, but Cambridge water has natural fluoridation. In the 2010 municipal election, Waterloo voters will be asked whether they want to keep fluoride in the drinking water.

Halton: Anti-fluoride lobbyists have been firing off e-mails to regional officials calling for an end to water fluoridation. Dr. Robert Nosal, the region’s medical officer of health, said his department is preparing a report on water fluoridation for the region’s health and social services committee for November. From there it will go to council.

The report will take into account new information on water fluoridation, says Nosal, who personally supports it as safe and effective.