Toronto — If fluoride is in our water supply, toothpaste, mouthwash and those foul-tasting rinses and pastes to which our dentists subject us, are some of us getting too much?

Health advocates have wondered about this for decades. Now the concern is getting some ivory-tower support, and that’s cranked up the efforts of both the pro-fluoridation and anti-fluoridation forces.

Hardy Limeback, head of preventive dentistry at the University of Toronto’s faculty of dentistry, believes that most of us are overfluoridated.

“Kids exposed to all these sources are getting too much — they are past the optimum,” says Dr. Limeback, a former fluoride and consumer products expert for the Canadian Dental Association. “We know for sure that kids who ingest more than the optimum amount before the age of 6 will have fluorosis on their permanent teeth.”

He says dozens of children arrive at his Mississauga practice to be treated for dental fluorosis, a condition in which overexposure to fluoride causes white mottling and flecking on a child’s teeth. He worries that the rate of dental fluorosis — Canadian studies indicate that as many as 60 per cent of children have some form of fluorosis, whether they drink fluoridated water or not — speaks to a bigger threat to their health.

But the Ontario Dentists Association disagrees. Last week, it sent out a three-page bulletin to dentists saying that dental fluorosis is a cosmetic problem, not a health problem.

The bulletin also concluded: “Scientific consensus has never linked water fluoridation with any negative health effects.”

Certainly, there is a tradeoff with water fluoridation: Large population studies have shown that it can reduce dental decay in a community by as much as 50 per cent to 60 per cent.

But the evidence is equally clear that people don’t need to consume fluoride to reap its benefits: They just need the powerful agent to come into contact with their teeth.

And the side effects of swallowing trace amounts of fluoride every day are still open to question. “There hasn’t been a single study to show that exposure over a lifetime is safe,” counters Dr. Limeback.

But mounting research shows that all this fluoride may, at the very least, weaken our bones in the long run. In a 1997 review of the literature on fluoride’s effect on human bones, an article in the Australian and New Zealand Journal of Public Health said: “Evidence of skeletal fluorosis has been reported in at least nine studies from five countries with fluoride concentrations in drinking water of 0.7 to 2.5 ppm.”

Dr. Limeback, meanwhile, believes that dental fluorosis is enough of a public health worry. “Since when is a cosmetic problem not a problem when the patient must seek dental treatment to fix it. If every tooth has fluorosis that is unesthetic and unappealing, it could be treated with everything from micro-abrasion [polishing], veneers or bleaching.”

But don’t panic yet. Not all Canadian municipalities add fluoride to their drinking water, so you may not be at full risk. Have a chat with your dentist. The Canadian Dental Association recommends that dentists be aware of the total fluoride from all sources to which patients, notably children, are exposed. Find out if your dentist is on top of it.

Drinking bottled water or using a reverse osmosis filtration device on household taps is an option, but that may be too costly for some. It’s also important to make sure you and your children ingest as little of fluoridated toothpaste as possible after brushing your teeth. You might not want to use fluoridated toothpaste at all with children under 6.