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Water Fluoridation
Fluoridation of Drinking Water – Further Study is Needed
Eric Richards, M.S., MPH student
Walden University
PH 6165-1
Instructor: Dr. Rebecca Heick
Winter Quarter, 2009
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Introduction
It has been estimated that approximately 40% of municipal drinking water in the United
States is fluoridated, with a concentration in the range of 1.01 ± 0.15 mg/ml (Miller-Ihli,
Pehrssonb, Cutrifellib , and Holden, 2003). Some estimates have put the percentage of
fluoridated public drinking water as high as 70% (CDC, 2008).
The practice of water fluoridation has caused great controversy since the early to mid
twentieth century. During this time, opposition to water fluoridation ranged from communitybased political movement (Citizens for Safe Drinking Water, 2009) to organizations of scientists,
such as the Environmental Protection Agency scientists of National Federation of Federal
Employees Local 2050 (Fluoride Action Network, 2009).
There are various theories as to why water fluoridation is supported and opposed;
theories that have nothing to do with Public Health per se. For example, as the fluoride for
fluoridation is produced through the utilization of waste silicofluorides produced by the
aluminum, steel and fertilizer industries, it has been proposed that utilizing this waste for water
fluoridation provides these industries with a less expensive way of disposing of waste and a
potentially lucrative side business. In addition, it has been proposed that the support of
fluoridation by the United States Public Health Service (USPHS) was because of the
appointment in 1947 of Oscar Ewing, formerly Chief Counsel of the Aluminum Company of
America, to the head of USPHS; it’s theorized that Ewing’s motivations may have been less than
pure (The Fluoride Debate, 2000). Conversely, sociological theories have been proposed to
explain why individuals may be opposed to fluoridation: such as general hostility toward the
medical profession and lack of understanding with regard to Public Health’s role (Simmel, 1962)
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This article does not endeavor to answer the question as to why the United States has
decided to systematically fluoridate public water. Rather, the following analysis is in response to
a simple question: are there sufficient data, of sufficient quality, in-line with current standards to
justify the use public water fluoridation?
Criteria for Evaluation
Fluoride as utilized in dental products (e.g. toothpastes) are considered medicinal
products (i.e. drugs) and regulated by the Food and Drug Administration (FDA, 2009). This
should not be surprising, as the statutory definition of a drug includes any substance that is
intended for use in the diagnosis, cure, mitigation, treatment, or prevention of a disease and/or
because they are intended to affect the structure or function of the body (Food, Drug and
Cosmetic Act, n.d.). As tooth decay is acknowledged as a disease (American Dental Association
[ADA], 2005), certainly the health claims associated with public water fluoridation fit squarely
into this statutory definition of a drug: namely, the claim that fluoridation is “a safe and costeffective way to prevent tooth decay” (CDC, 2009a). As such, it might be useful to utilize the
criteria usually mandated for the approval of drugs per law and regulation: namely, providing
substantial evidence of the safety and efficacy of the product via two adequate and wellcontrolled clinical studies (FDA, 1998).
Effectiveness
The American Dental Association claims that an overwhelming amount of evidence
exists to support the effectiveness of water fluoridation (ADA, 2005). Indeed, there is a plethora
of information about water fluoridation dating back to the 1940s. One question though is whether
or not these studies are of sufficient quality to give a reliable answer. In the ADA’s own
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description of the evidence, the vast preponderance of evidence comes from cross-sectional
studies, a study design known to be open to confounding and bias.
As the ADA assessment of effectiveness gives little information concerning the relative
quality of the studies, it may be useful to look toward other, peer-reviewed, assessments of the
data. McDonagh et al. (2000) conducted a comprehensive, systematic review and meta-analysis
of the available literature on the subject. In all, two hundred and fourteen studies were included
in the analysis, which assessed the evidence presented on efficacy (e.g. dental carries, missing
/filled teeth, decay, etc.) as well as safety. A discussion of the safety assessment is presented later
in this paper.
McDonagh et al. (2000) found that water fluoridation was associated with a decreased
incidence of dental carries (median 14.6%, range -5.0% to 64.0%) as well a decrease in the
number of decayed, missing and filled teeth (median 2.25, range 0.5 to 4.4). Importantly, the
study found that all the studies were of low to moderate quality; in fact, none of the studies were
considered of high quality. The authors noted that many studies did not present an analysis at all
and those that did failed to even attempt controlling for confounding factors such as age, sex,
social class, tooth type, total fluoride consumption, etc. (McDonagh et al., 2000).
In the absence of well-controlled studies, observational and cross-sectional studies seem
to be the only means available to assess the effectiveness of water fluoridation. With this in
mind, it is interesting to look at any difference that might exist in the prevalence of poor dental
health between the United States, where water fluoridation is common, and that of Europe,
where the majority of countries have forbidden the practice of public water fluoridation (Farkas,
1982; Auermann and Lingelbach, 1964).
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It has been noted that the prevalence of dental carries in the United States has decreased
over the last century; a phenomenon credited to the implementation of fluoridation (ADA, 2005).
What is interesting to note is that a similar reduction in the prevalence of dental carries has been
seen in much of Europe, despite the fact water fluoridation is not widely applied (Mathaler,
2004; Mathaler , O'Mullane, and Vrbic, 1996). In addition, if one compares dental carries
prevalence in industrialized European nations to that seen in the United States, one sees similar
rates (WHO, 2009). If the magnitude of effect from fluoridation were large, one would expect to
see a substantive difference in the prevalence of dental carries in industrialized nations that
practiced water fluoridation when compared to those that do not.
Safety
The other, equally important, half of a drug assessment is its safety. The ADA (2005)
categorically states that, at the recommended levels, fluoridation of the water is safe - noting no
known adverse effects in diseases ranging from Alzheimer’s disease to cancer.
In the meta-analysis by McDonagh et al. (2000) noted above, the safety of fluoridation
was evaluated for similar parameters. In that evaluation, the only significant adverse finding,
based on the evidence available, was the dose-dependent increase in dental fluorosis. Dental
fluorosis is an increased porosity of the surface, resulting in an increase in the opaqueness of the
teeth leading potentially to extremely chalky white teeth (Fejerskov, Manji, and Baelum , 1990) .
In the study by McDonagh et al. (2000), dental fluorosis that would be considered aesthetically
displeasing was found in 12.5% (CI: 7.0% to 21.5%) of the study population. Other, more
serious adverse health outcomes, such as cancer, Down’s syndrome, reduction in IQ, and
Alzheimer’s disease were not found to be associated with water fluoridation (McDonagh et al.,
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2000). It should be noted though that the authors bemoaned the fact that studies were inadequate
to assess such risks and were unable to even pool the data due to varying outcome measures.
From a nonclinical perspective, there are a plethora of studies noting the toxic effects of
fluoride in large acute doses: for example, renal toxicity (Taylor, Scott, Maynard, Smith, and
Hodgeb,1961); reproductive toxicity (Ahmad, Al-Hiyasat, Elbetieha , Homa Darmani, and
Jordan, 2000) and bone formation (Pak, Zerwekh, and Antich , 1995). From a clinical
standpoint, there does not appear to be a clear answer with regard to low dose, life-long
exposure, in that robust clinical assessment (i.e. prospective, well-controlled safety studies) have
not been conducted. Nonetheless, some of these potential safety concerns have caused entities
such as the European Union to question the practice of water fluoridation (European
Commission, 2009).
What is troubling about public water fluoridation from a safety perspective is not so
much the demonstration, or lack of demonstration, of toxic effects – it’s the lack of adequate
assessment. Surely, in order to understand the potential of fluoride to cause something as elusive
as cancer, a study design more rigorous than an observational, cross-sectional study is needed.
Position Statement
It is not the position of this author that water fluoridation is safe or unsafe. Nor is it
proposed that water fluoridation is ineffective; the available evidence seems to indicate a modest
effect in preventing tooth decay. Rather, it is this author’s position that water fluoridation has not
been sufficiently studied to justify the most widely used medicinal treatment to date. For a
medicinal product that is, involuntarily, utilized by literally millions of Americans on a daily
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basis, it would seem logical to demand the same type of rigorous, adequately powered and wellcontrolled studies that we demand of medications which are used in a fraction of said population.
What if it were proposed to add minute levels of statins to the public water supply?
Intuitively this might seem like a fine idea; heart disease is the leading cause of death in the
United States (CDC, 2009b) and statins have been proven to reduce the risk of myocardial
infarction, stroke and angina (Blumenthal, 2000).
Of course, the sensible response to such a proposal would be to highlight the lack of
evidence to support the use of statins in such a wide-spread manner. In addition, dosing would be
problematic, as we wouldn’t be able to control the dose for each individual, and we haven’t
adequately quantified the safety profile of the drug in the context of life-long, high cumulative
exposures. Interestingly, the same thing could be said for fluoride. Once more, there’s an irony in
this comparison because we have more rigorous, well-controlled clinical data testing the efficacy
and safety of statins than we do with fluoride.
Why do we accept a lesser standard for public water fluoridation? It is this author’s
position that we shouldn’t.
Water Fluoridation
Selected Further Reading
The following are some selected readings that offer perspectives counter to the
conventional wisdom of pro-fluoridation.
The Fluoride Debate (2000). A Response to the American Dental Association’s Booklet
Fluoridation Facts. Accessible at http://www.fluoridedebate.com/
McDonagh M.S., Whiting P.F., Wilson P.W., Sutton A.J., Chestnutt I., Cooper J., Misso K.,
Bradley M., Treasure E.,Kleijnen J. (2000). Systematic review of water fluoridation.
British Medical Journal. 321:855–9
Why EPA Headquarters Union of Scientists Opposes Fluoridation. Accessible at
http://www.nteu280.org/Issues/Fluoride/NTEU280-Fluoride.htm
The Fluoride Action Network: Broadening public awareness about fluoride. Accessible at
http://www.fluoridealert.org/
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References
Ahmad S Al-Hiyasat A.S., Elbetieha A.M., Homa Darmani H., Jordan I. (2000). Reproductive
Toxic Effects of Ingestion of Sodium Fluoride in Female Rats. Fluoride Vol. 33 No. 2 7984
American Dental Association (2005). Fluoridation Facts. Retrieved from ADA website on
January 01, 2010 at http://www.ada.org/public/topics/fluoride/facts/fluoridation_facts.pdf
Auermann, E., and H. Lingelbach. 1964. "Status and Prospects of Fluoridation in Europe."
American Journal of Public Health and the Nation's Health 54: 1545-1550.
Blumenthal R.S. (2000). Statins: Effective antiatherosclerotic therapy. American Heart
Journal, 139 (4), pp. 577-583.
Center for Disease Control and Prevention (2009a). FastStats. Retrieved from the CDC website
on January 20, 2010 at http://www.cdc.gov/nchs/FASTATS/lcod.htm
Center for Disease Control and Prevention (2009b). Community Water Fluoridation – Benefits.
Retrieved from the CDC website on January 15, 2010 at
http://www.cdc.gov/fluoridation/benefits.htm
Center for Disease Control and Prevention; Morbidity and Mortality Monthly Report. July 11,
2008 / 57(27);737-741. Retrieved from the CDC website on January 15, 2010 at
http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5727a1.htm
Citizens for Safe Drinking Water (2009). Retrieved on January 14, 2010 at
http://www.nofluoride.com/index.cfm#4Reasons
European Commission (2009). Public Consultation: call for the submission of new (after 2005)
information or data on the hazard profile, health effects, and human exposure to fluoride
and information and data on the health risks that may be associated with the use of most
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common drinking water fluoridation agents like silicofluorides (e.g. (hydro)fluorosilicic
acid, sodium silicofluoride). Retrieved from the EC website on January 6, 2010 at
http://ec.europa.eu/health/ph_risk/committees/04_scher/scher_call_info_04_en.htm
Farkas, E.J. 1982. "Water Fluoridation in Eleven Countries." Social Science and Medicine 16:
2155-2158
Fejerskov O, Manji F, Baelum V. (1990). The nature and mechanisms of dental fluorosis in man.
Journal Dental Research.;69 Spec No:692-700; discussion 721
Fluoride Action Network (2009). Letters/Statements from Union on Fluoride. Retrieved on
January 15, 2010 at http://www.fluoridealert.org/health/epa/memos/union/index.html
Food and Drug Administration (2009). Drugs; FDA Basics. Retrieved from the FDA website on
January 14, 2010 at http://www.fda.gov/AboutFDA/Basics/ucm192696.htm
Food and Drug Administration (1998). Guidance for Industry: Providing Clinical Evidence of
Effectiveness for Human Drug and Biological Products. Retrieved from the FDA website
on January 15, 2010 at
http://www.fda.gov/downloads/Drugs/GuidanceComplianceRegulatoryInformation/Guid
ances/UCM078749.pdf
Food, Drug and Cosmetic Act of 19??, 21 U.S.C. 321 (n.d.) Retrieved from the FDA website on
January 15, 2010 at
http://www.fda.gov/RegulatoryInformation/Legislation/FederalFoodDrugandCosmeticAc
tFDCAct/FDCActChaptersIandIIShortTitleandDefinitions/ucm086297.htm
Mathaler T.M., (2004). Changes in Dental Caries 1953–2003. Caries Research 38:173–181 DOI:
10.1159/000077752
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Mathaler T.M., O'Mullane DM, Vrbic V. (1996). The prevalence of dental caries in Europe
1990-1995. ORCA Saturday afternoon symposium 1995. Caries Research; 30(4):237-55.
McDonagh M.S., Whiting P.F., Wilson P.W., Sutton A.J., Chestnutt I., Cooper J., Misso K.,
Bradley M., Treasure E.,Kleijnen J. (2000). Systematic review of water fluoridation.
British Medical Journal. 321:855–9
Miller-Ihli N., Pehrssonb P., Cutrifellib R, Holden J. (2003). Fluoride content of municipal water
in the United States: what percentage is fluoridated? Journal of Food Composition and
Analysis 16; 621–628
Pak C.Y.C, Zerwekh J.E., Antich P (1995) Anabolic effects of fluoride on bone Trends in
Endocrinology and Metabolism. Volume 6, Issue 7, Pages 229-234
Simmel, A. (1962) . Some Correlates of Opinion on Fluoridation. Presentation to the Dental
Health Section of the American Public Health Association at the Eighty-Ninth Annual
Meeting in Detroit, Mich., November 14, 1961.
Taylor J.M, Scott J.K., Maynard E.A., Smith F.A, Hodgeb H.C. (1961). Toxic effects of fluoride
on the rat kidney: Acute injury from single large doses. Toxicology and Applied
Pharmacology; 3, 278-289
The Fluoride Debate (2000). A Response to the American Dental Association’s Booklet
Fluoridation Facts. Compiled by Anita Shattuck. Health Way House.
World Health Organization (2009). WHO Oral Health Country/Area Profile Program. Retrieved
from WHO and Malmo University website on January 3, 2010 at
http://www.whocollab.od.mah.se/index.html