It might be in every glass of water you drink–tasteless, colourless and odourless. It might be saving your teeth from cavities, or slowly poisoning you. Most public health officials and dentists don’t question its benefits, while a few scientists have argued against its use. "It" is fluoride, a compound added at about one part per million (ppm) to municipal water supplies from which just over half of us drink.

Leading proponents of water fluoridation include dental associations and government public health agencies. The American Dental Association calls fluoride a "nutrient" and the "key reason" why tooth decay has declined in the past few decades. The Canadian Dental Association claims that "Where fluoride has been added to municipal water supplies, there has been a marked decline in tooth decay rates–between 35 and 50 percent in children and 30 percent in adults," and that "Children need fluoride protection while their teeth are developing." Health Canada echoes these assurances.

However, there is another side to the story that prompts the question of side-effects, the least of which is dental fluorosis, a mottling or pitting of the teeth that most official organizations dismiss as cosmetic. Indeed, some scientists and public health officials oppose water fluoridation. Dr. Hardy Limeback, head of preventive dentistry at the University of Toronto, is one of them; he has publicly criticized the practice since April 1999. John Colquhoun was New Zealand’s top promoter of water fluoridation until a world-study tour in 1980, during which he realized improvements in dental health were already occurring in unfluoridated areas, begging the question of fluoride’s effectiveness. Paul Connett is a chemistry professor at St. Lawrence University in Canton, New York. His opposition began while doing some research when his town proposed to stop fluoridating in the mid-1990s. He was a founding member of the Fluoride Action Network and now manages a comprehensive anti-fluoridation Web site at fluoridealert.org. Even the union of scientists within the US Environmental Protection Agency voiced its opposition in 1999.

Reasons For Concern

The key issues surrounding water fluoridation involve safety and effectiveness. Water fluoridation results in systemic bodily exposure to fluoride (yet the purported benefits of fluoride are mainly topical, on the tooth surfaces). Fluoride is absorbed by some organs and body systems, notably bones, and this can be quite harmful. There is evidence of an elevated risk of bone fractures and degenerative bone disease in fluoridated areas, and the risk of bone cancer (osteosarcoma) is 40 percent higher in fluoridated areas in Ireland and three times higher in fluoridated counties in New Jersey.

Among children with dental fluorosis, Chinese scientists have found lower IQ scores. Polish scientists have found bone structure disturbances. Epidemiological studies in the US have shown a higher risk of Down’s syndrome, particularly among young mothers, in the most highly fluoridated areas.

In addition to concerns of fluoride exposure, heavy metals (lead, arsenic and radium, among others) are common contaminants of the silicofluorides that most Canadian cities add to their water supplies. The levels of heavy metals are usually only around one part per billion (ppb), but this is still enough to have negative effects, particularly as they accumulate in the body over years. Arsenic, often the most concentrated heavy metal contaminant, is associated with cancer and is particularly toxic to the liver, kidneys, and nervous and circulatory systems. Studies on more than 400,000 children have consistently found elevated lead levels in children consuming water that contains silicofluorides. Lead is a potent neurotoxin and, according to Limeback, can increase cavity rates. Radium is associated with an elevated risk of leukemia and bone cancer.

The Effectiveness Question

David Crowe likes to analyze the science behind current approaches to medicine and public health, particularly relating to infectious diseases. He is the president of the Alberta Reappraising AIDS Society (aras.ab.ca) and can be reached at David.Crowe@aras.ab.ca or (403) 220-0129. He has an HBSc in biology and mathematics.

Source: alive #243, January 2003