Canadians got a wake-up call on the importance of water supply safety in May 2000 when seven residents of Walkerton, Ont. died as a direct result of drinking tap water contaminated with E. coli.

An inquiry concluded water utility workers failed to use adequate amounts of chlorine, among other mistakes.

American health officials began adding chlorine to drinking water in 1908 to kill waterborne pathogens that can cause typhoid fever, dysentery and cholera.

Chlorine can react with organic matter to form potentially harmful byproducts called trihalomethanes (TMHs), which include chloroform. But most agree chlorine’s benefits outweigh its risks.

Fluoride is another kettle of fish. Fluoride isn’t added to water to make it safer, it’s added so those drinking it will have fewer cavities.

Grand Rapids, Mich. became the first city to add fluoride to its water supply in 1945, after scientists discovered that those living where drinking water had naturally-occurring fluoride levels of about one part per million had fewer cavities. Other communities, especially in North America, soon jumped onboard.

But the relevance and safety of fluoridation has been questioned for decades.

Friday, the U.S. Department of Health and Human Services announced it will lower the recommended level of fluoride because of concerns too much fluoride is causing a tooth-streaking condition called fluorosis in adolescents and studies that indicate a prolonged, high-intake of fluoride can increase bone abnormalities and fractures.

And Calgary is looking into removing fluoride from its municipal water supply. Opponents to fluoridation cite its cost and health concerns as reasons to cease the practice.

There’s not much of a hue and cry against fluoridation in Cape Breton. In March 2009, Cape Breton Regional Municipality water utility manager Mike MacKeigan said the CBRM should continue using fluoride until Health Canada, the World Health Organization and the Canadian Dental Association “go on record as opposing the use of fluoride in drinking water.”

MacKeigan’s comments were in response to local activist Marlene Kane, who opposes fluoridation, calling fluoride “unprocessed hazardous waste” and referencing health concerns.

Fluoridation is not universal even among the CBRM’s water treatment plants. It’s only used in the same plants that added fluoride prior to amalgamation.

There are strong arguments against fluoridation: it costs thousands of dollars, possible health risks, its spotty implementation and the fact that fluoride is readily available in products such as toothpaste.

But MacKeigan has a point. It’s understandable that the CBRM would take its cues on fluoridation from larger bodies with balanced scientific expertise. A groundswell of opposition from residents would likely sway council, but that hasn’t happened yet by any means.