For years, dental sealers and commonly used white fillings have been considered safer alternatives to once-traditional mercury-based amalgam fillings.

But now some of the newer sealants and fillings are raising concerns because they may contain small amounts of bisphenol A (BPA), a chemical which was recently declared a potentially dangerous substance by Health Canada.

BPA acts like the hormone estrogen and studies suggest it may trigger early puberty, attention deficit disorders, and some cancers. That's why Health Canada announced this month that it wants it removed from baby bottles and infant-formula cans.

BPA is also used to manufacture sealants and fillings used regularly in many dentists' offices across the country. Although there have been a few studies that suggest that the products can leak miniscule amounts of chemicals into a patient's saliva after they're applied, Health Canada and some dentists says the levels don't appear to cause a health hazard.

"When it comes to something like a dental sealant, there is a very, very small amount of material. (It) just fills in the little groove on the biting surface of the tooth. In terms of the amount of exposure, it is very minimal and very little to no risk at all," says Dr. Peter Chan of the B.C. Pediatric Dental Society.

Critics disagree.

"This is not the sort of chemical that we should be putting in people's mouths, particularly children's mouths," says Aaron Freemen, policy director of Environmental Defence.

The Canadian Dental Association says some dentists are moving away from using products that contain BPA.

"Just to make sure that we don't create long term problems, we are looking for materials that would not be containing BPA," says the Canadian Dental Association's Dr. Benoit Soucy.

But dentists note that avoiding products with BPA may not be so simple. Dentists may not always know which products contain it.

"The best news that we've had on that front recently is that Health Canada is putting together a data base of materials that contain BPA, and that will allow us to identify with certainty which materials contain BPA and which materials don't," Soucy said.

Based on a report by CTV's medical correspondent Avis Favaro and producer Elizabeth St. Philip