Taking a Closer Look at Fluoride
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To most folks, the decades-old controversy over fluoride belongs to the realm of foil hats and ham radios, of black U.N. helicopters and Freemason conspiracy theories.
But the investigation of a Harvard University professor accused of playing down links between fluoride and bone cancer may signal a mainstreaming of the debate.
Millions of Americans consume fluoride through community drinking water. Mainstream medical groups like the American Dental Association and the Centers for Disease Control have staked their reputation on fluoride, having long praised fluoridation schemes as beneficial for healthy teeth.
But anti-fluoride activists say a growing body of peer-reviewed scientific evidence counters long-held assumptions about fluoride's safety, and they're turning up the heat.
Last month, the Environmental Working Group, a respected Washington-based watchdog organization, called public attention to a Harvard study that shows links between fluoride and bone cancer in young boys. That study, conducted in 2001 by Elise Bassin, a Harvard doctoral student, stated that "among males, exposure to fluoride at or above the target level was associated with an increased risk of developing [the rare form of bone cancer] osteosarcoma. The association was most apparent between ages 5-10, with a peak at 6 to 8 years of age."
The EWG, which claims Bassin's study is the most comprehensive of its kind to date, also formally accused Chester Douglass, a researcher at Harvard's dental school and Bassin's former supervisor, of playing down her results in a 2004 report to federal officials.
The EWG has asked the National Institutes of Environmental Health Sciences (NIEHS) to investigate Douglass and has called on federal officials to list fluoride as a potential carcinogen.
Douglass, who is the editor of an academic publication funded by the toothpaste industry, told officials that his $1.3 million federally funded study, which included Bassin's work, showed no significant link between fluoridated water and osteosarcoma.
Both Harvard and the NIEHS are investigating EWG's claims.
"The main point is that [Bassin's work] is the most robust epidemiological study to date on bone cancer and fluoride," said Tim Kropp, a senior scientist at EWG, adding that Bassin's methods were so rigorous and difficult that the methodology itself was published separately from the findings. In a letter to the NIEHS, his group claimed that by glossing over Bassin's research, Douglass violated federal laws against falsifying scientific data.
"The Harvard School of Dental Medicine takes all allegations of misconduct seriously and has a standard system for reviewing allegations of research impropriety," a Harvard spokesperson said in an email. "The School will also work in concert with the National Institute of Environmental Health Sciences in its review of the reporting of this research."
Though generations of dental students have been sold on the dental benefits of fluoride, studies over the last decade in particular have suggested a correlation with cancer. Studies conducted by the National Toxicology Program and the New Jersey Department of Health, have shown higher than normal incidents of cancer in male rats exposed to fluoridated water, for example.
Such studies have helped spawn grassroots opposition to fluoridation, and, since 1999, 70 U.S. communities have rejected fluoridation schemes, according to Fluoride Action Network, a watchdog group.
But fluoridation programs flourished even in the face of questions about health impacts. Kropp says the thrust behind fluoridation "is faceless. Some of the big proponents of fluoridation and some of the original experiments done, and done in faulty ways, aren't around anymore. But you have new generations of dentists and public health officials who were taught in school that this is fine, so there's no reason to go to the literature. It just gets passed down that way."
Nonetheless, more and more scientists are refusing to take fluoride's safety for granted.
Dr. Hardy Limeback, a leading Canadian expert and head of preventive dentistry at the University of Toronto, said he could not comment for this story because he is involved in a two-year review of fluoride for the National Academy of Sciences.
But Limeback, who once supported but now opposes fluoridation, has written extensively on fluoride's health risks, and his views are shared by many in the scientific community. He has written that global cavity rates have declined mostly as a result of fluoridated toothpaste and that topical applications rather than widespread applications through community water can prevent tooth decay. Limeback and others also point out that industrial sources of fluoride contain harmful chemicals and have not been tested properly.
"Hydrofluorosilicic acid is recovered from the smokestack scrubbers during the production of phosphate fertilizer and sold to most of the major cities in North America, which use this industrial grade source of fluoride to fluoridate drinking water, rather than the more expensive pharmaceutical grade sodium fluoride salt," he wrote in a public letter in April 2000. "Fluorosilicates have never been tested for safety in humans. Furthermore, these industrial-grade chemicals are contaminated with trace amounts of heavy metals such as lead, arsenic and radium that accumulate in humans."
Whether Limeback's views will influence the NAS's study remains to be seen. But the debate, for now at least, seems to be getting mainstream credentials.
Kelly Hearn is a former UPI staff writer who lives in Washington DC and Latin America. His work has appeared in the Christian Science Monitor, American Prospect, and other publications.