The debate over fluoridating public water supplies, a measure long credited with producing a dramatic drop in tooth decay in the United States, is being rekindled by new studies suggesting the decline may have more to do with other causes, including other sources of fluoride.
The most exhaustive study ever conducted on the dental health of American children, conducted in 1986-87, has confirmed the great decline in cavities in the last 10 years, but it found much less difference than expected between areas with and without fluoridated water.
That has set off the latest skirmish in a long-running battle so polarized that both sides have been accused of making sweeping propagandistic statements that go far beyond the facts.
Proponents call fluoridation one of the greatest of public health success stories, an effective, low-cost, no-risk program. Opponents call it ineffective and dangerous.
Some recent assessments of the evidence by impartial scientists have reached conclusions somewhere in the middle ground.
Recently-released reports by the New York state Department of Public Health and an expert panel appointed by the US Surgeon General, for example, dispute the American Dental Association’s blanket claim that there are no adverse health effects from fluoridation. However, they also dispute claims that the practice is ineffective in reducing tooth decay.
But fluoridation’s effectiveness may be less than earlier studies had indicated, according to a new study by the National Institute for Dental Research. The largest study in the 40 years since fluoridation of US water supplies began, it covers almost 40,000 children, aged 5 to 17, in 84 areas across the country.
John A. Yiamouyiannis, a biochemist and fluoridation critic, has written a paper saying the NIDR data show no difference in decay rates between areas with fluoridated and unfluoridated water supplies. NIDR scientists have produced a report saying the same data show 18 percent less decay in the fluoridated areas, a difference they call significant, but which is far below the 40 to 60 percent reduction claimed by the American Dental Association. Neither paper has yet been published.
Yiamouyiannis, who has been crusading against fluoridation for 20 years, compared the number of decayed, missing and filled teeth (a standard index of dental health) among children in areas with fluoridation, without fluoridation, and with partial fluoridation. He found no statistically significant differences among children of any age group.
He then eliminated all the children who had ever moved, about half of the sample group, thus focusing only on those who had spent their whole lives in either fluoridated or unfluoridated areas. The results were the same.
Many scientists are scornful of Yiamouyiannis, who has been associated with campaigns for laetrile, a discredited cancer treatment, and has claimed that fluoride causes everything from cancer to AIDS – claims generally considered to be without foundation. Gregory Connolly, director of the Office of Dental Health of the Massachusetts Department of Public Health said last week, “I don’t respect him as a scientist… The man is a zealot.”
NIDR scientists Janet Brunelle and James Carlos did a similar analysis of the data but used a different index: the number of decayed, missing or filled tooth surfaces. On that basis, they found those who had always lived in fluoridated areas had 18 percent fewer damaged teeth than with unfluoridated water.
Even by that index, there were anomalies. In the Midwest, for unexplained reasons, the rate was slightly higher for the fluoridated areas than unfluoridated ones.
All sides agree that the rate of tooth decay has declined dramatically over the last two decades in both fluoridated and unfluoridated areas. While the reasons for the decline have not been established, health specialists think it may be due to a combination of better nutrition, better dental care, use of antibiotics and use of fluoridated toothpaste and rinses.
In an 1988 article in the Journal of the American Dental Association, researcher Stanley B. Heifetz of NIDR found the same trend: “The current reported decline in caries tooth decay in the US and other Western industrialized countries has been observed in both fluoridated and nonfluoridated communities, with percentage reductions in each community apparently about the same.”
NIDR’s Brunelle and Carlos concluded that because of wide use of fluoride in toothpaste and rinses, and its prevalence in food, “practically all US children are exposed to fluoride to some degree. . . It is therefore not surprising that the caries-preventive effect of water fluoridation has appeared to decrease over time.”
“. . .It is doubtful an unequivocal explanation of this trend can be found.”
Connolly, of the state public health department, thinks the differences between fluoridated and unfluoridated areas may be more apparent in low-income areas, where supplements such as fluoride rinses may be less available or less widely used. “In many areas you’re not seeing differences as great,” he said, “but in low-income areas you do.”
While the argument has tended to be highly polarized, there are some signs that more open-minded debate is beginning on the issues of fluoridation’s safety and effectiveness. Last summer, an article in Chemical and Engineering News, a weekly journal of the American Chemical Society, examined the evidence on safety and effectiveness and found many unresolved questions. The ADA, fluoridation’s biggest promoter, is unequivocal on the safety issue. An ADA booklet called “Fluoridation Facts” says fluoride at the recommended levels “has no harmful effect in humans.” The booklet says “additional studies on the effects of fluorides in humans are not required” and “there is no scientific basis for doubting the medical safety” of the program.
That conclusion is challenged, however, by a study by the New York state Department of Health, dated November 1988 but just made public last month. It concluded that fluoridation is effective in preventing cavities but “further studies are required to resolve questions of hypersensitivity to fluoride, the susceptibility of individuals with kidney insufficiency to fluoride, and the effects of fluoride on human fertility.”
Last month, Medical Tribune, a weekly publication for health professionals, revealed that a panel appointed to study the issue in 1983 by C. Everett Koop, then surgeon general, also raised questions about health effects. All mention of those issues, however, was edited out of the panel’s final report, which backed Koop’s unequivocal endorsement of fluoridation.
One negative health effect that everyone acknowledges is dental fluorosis, an indelible mottling of tooth enamel that can range from barely noticeable white flecks to disfiguring brown or black stains. The ADA says it may occur in 10-15 percent of children who get the recommended amount of fluoride.
The omission of health concerns from the panel’s final report is “shocking, it’s absolutely shocking,” charged Robert Carton, an EPA environmental scientist and president of the union that represents the agency’s scientific staff. Carton appeared at a recent news conference in Washington at which Yiamouyiannis discussed his analysis.
Carton said the uncertainties about health effects raised by Koop’s panel and the New York state report show that fluoridation critics such as Yiamouyiannis who have been raising such questions for years are “not the crazies that everybody made them out to be.”