Feb 16, 1990
The Fluoride Bombshell
The scientific equivalent of an atomic bomb has just fallen on America's public health establishment. After 40 years of official claims that the addition of fluoride to community water supplies was a safe way to fight cavities, a new study ordered by Congress appears to show that "fluoride may be a carcinogen," in the words of one Environmental Protection Agency memo.
First hints of a cancer link
As early as 1954, Alfred Taylor at the University of Texas' Clayton Foundation Biochemical Institute produced a careful study showing that as little as one part per million (ppm) of fluoride in the drinking water of cancer-prone mice shortened their lifespan by an average of 9 percent.
Mice aren't people, of course, merely convenient if imperfect experimental substitutes. But in July 1977, John Yiamouyiannis, a biochemist, and Dean Burk, former head of the National Cancer Institute's cytochemistry section, published the results of a major survey of cancer death rates in U.S. cities. They found that cancer mortality rates, which had been rising about equally in the cities before fluoridation, began rising faster in cities that fluoridated their water. Although subjected to intense scrutiny and criticism, the study helped prompt congressional action that resulted in the recent National Toxicology Program study.
The biochemical basis of fluoride's possible link to cancer has been demonstrated in a wide variety of experiments indicating that fluoride inhibits enzyme activity essential to protein formation and the synthesis of DNA, the basic building block of genes.
In 1976, Dr. Aly Mohamed of the University of Missouri summed up the available evidence as suggesting that "the presence of fluoride in water may represent a genetic hazard to humans." In 1984 , three Japanese researchers concluded in the journal Cancer Research that "a potential for carcinogenicity of this chemical, which is widely used by humans, is suggested."
Fluoride: a poison
The effects of less acute fluorine poisoning range from discoloration and pitting of the teeth (dental fluorosis) to skeletal abnormalities, vomiting and diarrhea, kidney failure and spasms. Most of these maladies don't show up except when people take fluoride supplements or drink water unusually rich in fluoride. But dental fluorosis seems to have become more common since the onset of fluoridation. Sensitive individuals suffer from fluoride even at extremely low levels. And people with kidney problems are especially at risk because they cannot flush fluoride efficiently from their system.
These effects may be compounded by the largely unnoticed increase in average fluoride consumption. Foods and beverages processed with fluoridated water didn't exist when health authorities set recommended fluoride levels in the water.
Two specialists from the National Institute of Dental Research disclosed in a 1984 journal article that "a not-too-wide margin of safety exists between the optimum daily intake of fluoride to prevent caries and that which causes signs of advanced chronic fluoride intoxication."
Fluoride treatments, they warned, often cause nausea and vomiting in children and may cause renal dysfunction, a matter aggravated by the tendency of many pediatricians to over prescribed fluorides. (In the right hands, however, they concluded that "the risk of adverse effects is small.")
Sufficient uncertainties about fluoride's effects remain that a standard reference, Meyler's Side Effects of Drugs, warned in its 10th edition (1984) that "it is arguable that one should consider fluoride involvement as a cause in many ailments currently defying our diagnostic efforts, unless or until its role can be definitely excluded."
Pushing doubts aside
Medical Tribune, a news weekly, last year published some of the deliberations of a scientific panel convened by Koop -to study the fluoride controversy. The experts were quoted as saying "I realize that we have few facts and many unknowns," and "I just don't know where the truth is" - caveats Koop kept to himself in public statements.
In 1986, the EPA actually raised the permissible level of fluoride in drinking water. The EPA's own union of professional employees took the remarkable step of denouncing the action as political. The local's president, Robert Carton, Ph.D., branded the agency's review of evidence "a shoddy job, bordering on scientific fraud. You could call it a coverup.- The EPA has ordered a new review in light of the findings of the National Toxicology Program.
What makes the fluoride safety controversy all the more troubling are questions about its efficacy. Most dentists hold fluoridation responsible for the general decline in caries. A recent journal article by Ernest Newerun, professor of oral biology at the University of California at San Francisco, concluded that the available data "show a consistently and substantially lower caries prevalence in fluoridated communities."
Some controlled studies in Australia, New Zealand and Europe, however, show the unfluoridated areas enjoyed an equally impressive, if still unexplained, decline. (many healthy and advanced nations, including .Sweden, West Germany and Japan do not fluoridate.)
How much risk is acceptable?
At a minimum, some eminent dental authorities argue, public water agencies that do fluoridate - like EBMUD - should reassess the level in light of clear evidence that fluoride is now widespread in the food chain.
And if fluoride does prove to be a carcinogen, the Safe Drinking Water Act may leave those agencies no choice but to take it out of all water supplies. The challenge to public health authorities then will be to educate every American to brush well and see a dentist regularly - not to rely on fluoridation of the water as a miracle cure.
© Oakland Tribune