How much fluoride is too much?

Scientific American has reopened an age-old debate in its January issue with a feature story titled "Second Thoughts about Fluoride."

Author Dan Fagin focuses on a 2006 report issued by the National Research Council (NRC) -- based on two years of reviewing studies. The bottom line? The report suggests the Environment Protection Agency's (EPA) current limit (4 mg/L) of fluoride in drinking water should be lowered to protect children from fluorosis, which causes yellowing and pitting of the enamel. In adults, overexposure to fluoride may also cause bone cancer, damage to the brain and thyroid gland, and mild skeletal fluorosis, according to the NRC report.

"Most fluoridated water contains much less fluoride than the EPA limit, but the situation is worrisome because there is so much uncertainty over how much additional fluoride we ingest from food, beverages and dental products," writes Fagin. Fagin interviewed Steven M. Levy, director of the Iowa Fluoride Study, which has tracked the subtle effects of fluoride on 700 Iowa children for the past 16 years. Levy's research team found that there was "an average of 0.73 mg/L (fluoride) in cranberry-juice cocktail, 0.71 mg/L in ice pops, 0.99 mg/L in beef gravy and 2.10 mg/L in canned crabmeat."

According to Levy, "instead of just pushing for more fluoride, we need to find the right balance." Levy's study found that "Iowa children who lived in communities where the water was fluoridated were 50% more likely to have mild fluorosis ... than children living in non-fluoridated areas of the state," writes Fagin.

However, organizations such as the American Dental Association and the U.S. Public Health Service remain unimpressed, reports Fagin.

And although the ADA has acknowledged the article, so far there has been no direct response. The ADA's official stance on fluoride: "For over five decades, the American Dental Association has continuously endorsed the fluoridation of community water supplies and the use of fluoride-containing products as safe and effective measures for preventing tooth decay".

Meanwhile, anti-fluoridation organizations have trumpeted the magazine's story to press their point. "Fluoride, the most consumed drug in the USA, is deliberately added to 2/3 of public water supplies theoretically to reduce tooth decay, but with no scientifically valid evidence proving safety or effectiveness," said lawyer Paul Beeber, President, New York State Coalition Opposed to Fluoridation in a press release.