DIRECTORY: Health > EPA Fluoride Standards > NRC Review > Relevance to Fluoridation

NEW: NRC Panel Member, Dr. Kathleen Thiessen, discusses relevance of NRC report to fluoridation - May 2, 2006

Fluoride Action Network
April 3, 2006

The relevance of the NRC Report to fluoridation.

by Paul Connett, PhD
Executive Director, FAN

On March 22, 2006, a prestigious 12-member panel of the National Research Council completed a three year review of the appropriateness of the Enviromental Protection Agency's (EPA) safe drinking water standard for fluoride (officially called the Maximum Contaminant Level Goal, or MCLG) which is currently set at 4 ppm. After one of the most thorough and objective reviews of the literature in 60 years, the NRC panel unanimously found that the MCLG is too high and has asked EPA to lower the standard in order to protect children against severe dental fluorosis and to protect all groups from bone fracture. They have asked the EPA to perform a risk assessment to determine what the standard should be.

Some have questioned the relevance of this action to water fluoridation, since the panel was not invited to examine the risks and benefits of artificial fluoridation, in which fluoride is added to water at about 1 ppm ostensibly to fight tooth decay. This column examines the findings presented in the NRC's 450 page report and explains why they are highly relevant and important to any consideration of water fluoridation. Here are the relevant concerns.

1) The disappearing "margin of safety." The gap between the level at which fluoride is added to water, ostensibly to protect teeth (1 ppm), is already very close to the level at which the EPA requires fluoride to be removed (4 ppm). The recommended lowering of MCLG will make this gap even smaller and thus even more relevant to water fluoridation at 1 ppm.

2) Dose cannot be controlled. This very small gap becomes even more significant when one recognizes that while engineers can usually control the level of fluoride added to water (although there have been accidents), they cannot control how much water people drink. Nor can they control the fluoride that people get from other sources such as dental products and treatments, processed foods and beverages, fluorinated medications, pesticides and air pollution.

3) Exposure analysis. The NRC was charged with finding out how much fluoride people are actually getting, considering the wide variations in water consumption and other sources. The MCLG of 4 ppm was derived from the "safe" dose of 8 milligrams per day on the assumption that the "average" adult drinks 2 liters of water per day. Many people drink far more water than this. Using the panel's exposure analysis it can be readily shown that some people will exceed a "safe" intake of fluoride (either expressed as a dose of 8 milligrams per day for an adult, or a dosage of 0.114 mg/kilogram bodyweight per day when considering infants, children and others with different bodyweights) even at 1 ppm.

4) Adverse Effects at low exposures. The extensive NRC report reviewed many animal and human studies where adverse effects on a variety of tissues and organs have been observed at relatively low levels of exposure to fluoride. Many of the effects were observed at lower water concentrations than 4 ppm, or lower doses than 8 mg per day or lower dosages than 0.114 mg/kg/day. These included increased uptake of aluminum into the brains of rats exposed to fluoride at 1 ppm; lowered IQ in children in Chinese studies at levels of 2.5-4.0 ppm; increased hip fracture rates in the elderly at levels between 1 and 4 ppm and lowered thyroid function at dosages as low as 0.01 mg/kg/day. As water intake is random and intake cannot be controlled, all of these studies become relevant for water consumption at 1 ppm.

5) Bone fractures. Hip fractures in the elderly were observed a) in Finland at water levels at or greater than 1.5 ppm (Kurttio, 1999); b) increasing in what appears a linear fashion between 1 ppm and 4.3 ppm in China (Li et al., 2001) and c) bone fractures were found to increase between 1.5 and 5.5 ppm in Mexico (Alarcon-Herrera et al., 2001). While the panel did not feel they had enough data to state exactly at what level hip fractures would increase, it did describe both the Kurtio and the Li studies as good studies. When the EPA does its health risk assessment on this issue they will have to take these studies into account. What the NRC report did was to point out that 4 ppm is not protective against bone fractures for a lifetime exposure. It did not indicate what level is protective against bone fractures for a lifetime exposure.

6) Thyroid function. Even more serious is the discussion the NRC provided on fluoride's impacts on the thyroid and the brain. For the thyroid gland the NRC panel report effects at levels up to 10 times lower than the dosage associated with the 4 ppm maximum level in water (0.114 mg/kg/day) and which are exceeded by millions of American children and adults drinking water at 1 ppm.

Based on these observations, it is not clear why the NRC panel did not recommend a safe level of fluoride lower than 1 ppm. Their failure to do so appears to hang on the slenderest of threads: the chance that these findings on thyroid function in the peer reviewed literature in Europe, Russia, and China may not apply to people in the US. We can always do with more research to confirm findings like these but the lack of research on these matters in the US should not leave us with any confidence in this situation. It should be a matter of grave concern that this research has not been done here, even though the artificial fluoridation program has been going on now for 60 years and as early as 1940, researchers were writing about fluoride's impact on the thyroid gland (DeEds, F., 1940).

7) Huge data gaps. The NRC panel makes many research recommendations which reveal huge data gaps in basic research on fluoride's toxicity in the US. What it didn't say, but I am prepared to do so, is that the US Public Health Service's 56 year-old adherence to the water fluoridation program has severely limited meaningful research into fluoride's health effects. Most of the research money has been spent on dental research with little or no attention to other body tissues and organ systems.

As the NRC panel's research recommendations indicate, no significant efforts have been made in the US to track the levels of fluoride in urine, plasma or bones of the American people. Such basic baseline research is critical if one wishes to seriously explore whether there is a connection between fluoride exposure and health effects reported in the literature such as hypothyroidism, neurological effects, arthritis or other conditions afflicting millions of people. In the US, we have been flying blind on these matters. Hopefully, the NRC's review will stimulate some serious research by independent scientists (not those chosen to support the interests of the fluoridation program) in the future.

8) Uncertainties. The NRC panel has strongly recommended that the US EPA conduct a health risk assessment in order to ascertain a new MCLG which is protective of the American people -- and that includes more vulnerable subsets of the population, such as infants, the elderly, and those with diabeties, kidney impairment or heart disease. Because the NRC report has shown that the literature indicates very serious concerns and uncertainties, when the EPA does an updated health risk assessment on these endpoints, these uncertainties alone should force a margin of safety which will produce a new MCLG lower than the 1 ppm now used in water fluoridation.

9) The lack of signficant benefit from fluoridation not examined. The assumption that all is well with water fluoriation because the NRC panel didn't examine this practice is highly misleading. Had the panel members been required to look at the benefits they would have been shocked on how poor the science is that supports this practice. According to the UK York Review (2000) there is not one grade A study. They might also have been surprised to find that most European countries do not fluoridate their water but according to WHO figures their children's teeth are just as good if not better than ours. Moreover, the largest NIDR study of tooth decay in the US could find very little difference in the permanent teeth of children who had lived all their lives in fluoridated compared to non-fluoridated communities (Brunelle and Carlos, 1990). To this we can add the fact that US cities which have been fluoridating for years are reporting a dental crisis. This reflects the fact that there is a much stronger relation between tooth decay and standard of living than one can ever find with ingested fluoride.

10) The fluoridating agents in water fluoridation programs. Also as a consequence of not reviewing the water fluoridation program, the panel did not have to deal with the fact that the chemicals used in water fluoridation are not the same as the fluoride that occurs naturally in some water supplies. The chemicals used are contaminated industrial grade materials, which do not occur naturally, but are obtained from the scrubbing liquor of the pollution control devices of the phosphate fertilizer industry. These contaminated silicon fluorides have received little significant toxicological testing, on the flimsy grounds that once diluted the silicon fluoride compounds will completely dissociate into free fluoride ions and the contaminants will all be below levels of concern, even though some of them like arsenic and lead have an MCLG of zero and thus should not be deliberately added to the water supply

Conclusion: On many fronts, this important review from the National Academy of Sciences is of the utmost relevance to water fluoridation. There is such a small margin of safety between a small benefit to teeth and a huge risk to health - and none for some high water consumers - that it is time to halt this practice forthwith. Calling for more research after it has been halted is fine. But to do that research while we continue to dose 162 million Americans daily without firm knowledge of what levels will cause damage to health is preposterous. It amounts to the largest experiment with the public's health ever conducted. If nothing else it violates the Nuremburg Code which strictly forbids human experimentation without the informed consent of the patient. The vast majority of individuals being exposed have never given their consent, and, until now, very few have been fully informed on the downside of overexposure to fluoride.