Letter from Kathleen Thiessen to the Lee County (Florida) School Board
SENES Oak Ridge Inc.
Center for Risk Analysis
December 7, 1998
Members of the Lee County School Board
c/o Lanny W. Moore, Sr.
445 Keenan Avenue
Ft. Myers, FL 33919
Dear School Board Members:
At the request of my father, Lanny W. Moore, Sr., I am submitting a brief statement to the Lee County School Board regarding the issue of water fluoridation. By way of background, I hold a doctoral degree from the University of Tennessee-Oak Ridge Graduate School of Biomedical Sciences, and I have worked in the general field of health risk assessment for 12 years. As a staff member of the Oak Ridge national Laboratory, I authored a Health Issue Assessment for the U.S. Environmental Protection Agency entitled Summary Review of Health Effects Associated with Hydrogen Fluoride and Related Compounds (EPA/600/8-89/002F, December 1988). I have recently reviewed materials submitted to the School Board by Kenneth Case, in addition to my 1988 report and a sample of material available on the Internet.
My 1988 report was a review of available scientific literature (through January 1987) and dealt primarily with human exposure to airborne fluoride. The EPA’s main concern initially was hydrogen fluoride, but at my request, "related compounds" (other fluoride-containing compounds) were included in the report. Intake of airborne fluoride is typically small in relation to total intake of fluoride. The major sources of human exposure to fluoride are food, fluoridated water, and dentifrices; cigarette smoking can be important as well. I pointed out in the 1988 report that (a) health effects from chronic fluoride exposure are dependent on total fluoride intake from all sources; (b) people with renal dysfunction (kidney disease) are at higher risk for toxic effects caused by fluoride (due to slower clearance of fluoride from the body); (c) at least some of the decline in tooth decay attributed to fluoridated water may in fact be due to other causes (e.g., changes in dietary patterns, changes in immune status, or use of topical fluorides); and (d) the beneficial effects and adverse effects of fluoride must be weighed in determining the optimal dose for humans, and in particular, the optimal level to be maintained in public water supplies.
A significant amount of new information on fluoride use and toxicity has become available since my report was published, and I have not been able to do an extensive review at this time. Several significant items from my brief review of recent literature should be noted:
- Most laboratory studies on fluoride toxicity appear to have used sodium fluoride in distilled water; for other forms of fluoride commonly used in fluoridation, few or no studies have been performed. The potential health effects of fluoridated tap water as it is consumed by people in their homes, schools, and businesses have not been examined directly.
- Human exposures in many studies are considered in terms of the fluoride level in the local water supply, rather than in terms of the actual fluoride consumption by individuals. With this approach, differences in health effects with different levels of fluoride intake can be obscured.
- The apparent association of water fluoridation with increased lead levels in tap water is intriguing and deserves some serious attention.
- The trend in other countries (e.g., in Europe) is away from fluoridation of public water supplies.
My review to date suggests that a link between water fluoridation and previously unacknowledged adverse health effects is plausible and that total fluoride consumption by individuals may actually be higher than it is generally considered to be. In particular, persons with renal dysfunction (reduced elimination of fluoride) or high water intake (e.g., athletes, outdoor laborers, diabetics) may be at risk of developing fluoride-related health effects.
If water fluoridation is truly associated with increased lead levels and consequent toxicity, it definitely has an impact on the students for which the Lee County School Board is responsible. Lead intake by children is clearly associated with neurobiological and behavior problems. If only for this reason, the School Board has a vested interest in establishing whether fluoridation in public water supplies is ultimately beneficial or detrimental to members of the public, and to children in particular.
I recommend, therefore, that the Lee County School Board submit a formal request to the State Department of Health or other appropriate authorities to investigate water fluoridation as a public health issue. In particular, a scientist or group of scientists with a record of openness, scientific integrity, and public credibility should be asked to do a thorough review of the available scientific and medical evidence. Because some individuals or organizations may have a financial or political stake in public water fluoridation, an impartial and credible review is essential. The requested investigation should include an examination of actual fluoride intakes (including fluoride levels in food, etc.) by different categories of individuals (by age, activity level, socioeconomic status, location, etc.), not just population averages. If the review concludes that water fluoridation is indeed beneficial, the optimal levels should be reexamined in light of current dietary intakes, and individuals who may be at higher risk of fluoride toxicity should be clearly informed. The School Board or individual schools should also consider making bottled water available for outdoor activities (e.g., P.E. classes, athletics, etc.) where water consumption can be expected to be high.
Please feel free to contact me if I can be of further assisstance to you in this matter.
Kathleen M. Thiessen, Ph.D.
Senior Scientist and Director
Last modified: 10 July 1999