Dr. Hardy Limeback on Water Fluoridation

March 12, 2014

Note: Dr. Limeback is Former President, Canadian Association for Dental Research, and Former Head of Preventative Dentistry at University of Toronto.


“My name is Dr. Hardy Limeback.

I served 3.5 years on the US National Academies of Sciences (NAS) Subcommittee on Fluoride in Drinking Water. The NAS is sometimes referred to as the ‘Supreme Court of Science’, an organization that sets up unbiased (or balanced) committees to review scientific issues of concern to Americans.   The committee on which I served examined the effects of fluoride in drinking water.

Our report, published March 22, 2006 and can be found online at http://www.nap.edu/catalog.php?record_id=11571

Our committee was funded by the US Environmental Protection Agency (EPA) – we were charged NOT to examine the benefits of fluoridation but we certainly reviewed all relevant literature on the toxicity of fluoride, including those at low levels of intake, including the toxic side effects of fluoridation.

It has taken years for the EPA to respond to our report.  It now acknowledges that fluoride in drinking water poses a problem and it has lowered its recommendation for levels of fluoride in drinking water to 0.7 mg/L (ppm). The American Dental Association and the Center for Disease Control in the US both agree that fluoridated tap water should not be used to make up infant formula, since that increases the risk of dental fluorosis. To me, dental fluorosis is a biomarker for fluoride poisoning. Health Canada, taking the recommendation of only profluoridation experts, failed to come up with the same warnings as in the USA but then Health Canada does not set fluoridation policy. Neither do the provinces. Municipalities set policies such as water fluoridation. As far as I know, Public Health Officials have made no effort to inform expectant mothers and mothers of newborn babies to avoid using fluoridated city tap water for making up infant formula.  Their inaction is regrettable.

I have personally conducted years of funded research at the University of Toronto on the topic of fluorosis (fluoride poisoning) and bone effects of fluoride intake.  A bone study, for which we received national funding, comparing donated hip bones of people who live in Toronto (fluoridated since 1963) to the bones of people from Montreal (Montreal has never been fluoridated), suggested disturbing negative changes in the bone quality of Torontonians. This is unacceptable. Fluoridation was only supposed to affect the teeth.

Since we studied a cross section of the population as they were selected for hip replacement, we were unable to examine only those people who were exposed to fluoridation for a lifetime. If we had been able to do this, we would have seen a much greater negative effect of fluoride since fluoride accumulates with age (our study confirmed that). Studies like ours indicate that not only does extra fluoride in the water cause defective enamel that is VERY expensive to treat but also defective bone.

The NAS committee (also called the NRC committee) examined the literature on the effects of fluoride on bone up until 2006. Since that time there have been more studies to confirm the link between fluoridation and bone changes, as well as a link to bone cancer. Our Toronto vs Montreal study was not included in the 2006 review by the US National Academies of Sciences because it only just got published in 2010.

I am also the co-author of studies that show that too much fluoride accumulation in the dentin of teeth (the tissue that supports enamel) causes its properties to change as well (Vieira et al 2006).

Fluoride has NOT been shown to be safe and effective. In fact, as more and more peer-reviewed studies on fluoride toxicity appear in the literature, it has become clear to me that the pendulum is certainly shifting to ‘not safe, and no longer effective’.

As a practicing dentist, I have been diagnosing and treating patients with dental fluorosis for over 30 years. My research on dental fluorosis, confirmed by the studies reported in the 2006 NAS report as well as the York review (McDonagh et al 2000), show fluoridation significantly increases the numbers of patients seeking expensive cosmetic repairs. No one in public health has ever accounted for the added costs in treating dental fluorosis when considering the cost-benefit ratio of fluoridation.

Our 2006 NAS report also concluded that there is a likelihood that fluoride can promote bone cancer. On page 336 it is stated “Fluoride appears to have the potential to initiate or promote cancers, particularly of the bone, but the evidence to date is tentative and mixed (Tables 10-4 and 10-5).” This alone should force the EPA to set a maximum contaminant level goal for fluoride in drinking water at ZERO (as it did for arsenic).

We also know that fluoride is neurotoxic (see below).

I have looked at this from all angles and I have to conclude that fluoridated cities would save money on fluoridation costs, parents would save on costly dental bills treating dental fluorosis, dental decay rates would remain unchanged or even continue to decline (as has been demonstrated in many modern fluoridation cessation studies) and the health of city residents would improve when industrial waste products are no longer added to the drinking water.

I find it absurd that industrial toxic waste is shipped to the water treatment plants in large tanker trucks and trickled into the drinking water of major cities in North America. This not only puts water fluoridation employees at risk for serious injury, but if a major spill should occur releasing highly corrosive and poisonous hydrofluorosilicic acid into the atmosphere, people’s lives would be at stake. There have been documented deaths from accidental over-fluoridation and from spills of fluoridation chemicals in transit to water treatment plants.

Individual municipalities set fluoridation policies. That means that the city is responsible for the practice of fluoridation. I could not find anywhere in the Fluoridation Act (see http://www.e-laws.gov.on.ca/html/statutes/english/elaws_statutes_90f22_e.htm ) that states that cities have to provide alternatives to water fluoridation should city councils decide to halt the practice.

Several Canadian cities have decided it is not worth continuing the practice of fluoridation. Quebec City decided to halt fluoridation. Calgary city council voted to stop fluoridation without a referendum, as did Windsor recently. Waterloo decided to hold a referendum and voted to stop fluoridation. Overall in Canada, there have been many communities that have stopped fluoridation (see COF-COF.ca).

There is no doubt in my mind that fluoridation has next to no benefit in terms of reduced dental decay.  The modern literature is clear on that. Fluoridation cessation studies fail to show an increase in dental decay. In fact, caries rates continue to drop. The York review, held up as the best evidence for ‘safe and effective’ for fluoridation is flawed because it could not find a single randomized, double blinded clinical trial, and none of the clinical trials adjusted for confounding factors known to affect dental decay such as vitamin D levels, daily sugar intake, sweeteners, fissure sealant etc. Additionally, in their systematic review, the York reviewers made a grave error in estimating benefits by lumping modern studies with very old studies when decay rates were a lot higher. In the 1950’s, when fluoridation started to catch on, it was claimed that there was as much as a 40% benefit. Despite the evidence being very weak, fluoridation might have been worthwhile in those days, especially since fluoridated toothpastes were not introduced until the late 1960’s. After that, the benefit of fluoridation declined. Now, if there is any benefit at all, one could expect perhaps a 5-10% benefit in children. If half the children are already cavity free and the average decay rates are only two cavities per child it means cities have to fluoridate for 20 years in order to prevent one tooth for every fifth child from decaying. Clearly, that is NOT a policy that demonstrates fiscal responsibility and cities that do not do due diligence in terms of cost-benefit analysis are wasting tax payers money and may actually be putting their councillors in a position of liability.

The claim that every $1 spent on fluoridation saves $38 was never accurate, is not science-based and is the misinterpretation of a single article written by the oral health branch of the Center for Disease Control in the US.  It is an exceedingly misleading claim. In my opinion this is irresponsible and unprofessional.

The following is a summary of some of the current literature, which, in my opinion, shows that fluoridation is no longer safe and effective. There are thousands of studies for and against fluoridation from which to chose. I am presenting here the literature that continues to be ignored by those who want to promote fluoridation.

1. Fluoridation is no longer effective.

Fluoride in water has the effect of delaying tooth eruption and, therefore, simply delays dental decay (Komarek et al, 2005). The studies that water fluoridation works are over 25 years old and were carried out before the widespread use of fluoridated toothpaste. There are numerous modern studies to show that there no longer is a significant difference in dental decay rates between fluoridated and non-fluoridated areas (Armfield & Spencer, 2004; Slade et al, 2012).

Recent water fluoridation cessation studies show that dental fluorosis (a mottling of the enamel caused by fluoride) declines but there is no corresponding increase in dental decay (e.g. Maupome et al 2001; See also


Public health will claim there is still a dental decay crisis. With the national average in Europe of only two decayed teeth per child (World Health Organization data), down from more than 15 decayed teeth in the 1940s and 1950s before fluoridated toothpaste, as much as half of all children grow up not having a single filling. This remarkable success has been achieved in most European countries without fluoridation. The “crisis” of dental decay often mentioned is the result, to a major extent, of sugar abuse, especially soda pop. A 2005 report by Jacobsen of the Center for Science in the Public Interest said that U.S. children consume 40 to 44 percent of their daily refined sugar in the form of soft drinks.  The World Health Organization recently recommended that the consumption of sugar be reduced worldwide.  http://www.who.int/mediacentre/news/notes/2014/consultation-sugar-guideline/en/ “Doctors have applauded the WHO’s new recommendations, saying that sugar intake directly leads to obesity and tooth decay.” http://time.com/12905/who-sugar-reccommendations/

Since most soft drinks are themselves fluoridated, the small amount of fluoride is obviously not helping.

The families of children with rampant dental decay need professional assistance. It appears they are not getting it. Children who grow up in low-income families cannot afford dental care and are at higher risk of dental decay (Brennan & Spencer 2014). Untreated dental decay and lack of professional intervention result in more dental decay. The York review was unable to show that fluoridation benefited poor people to any greater extent than other groups of the population. The York review, and others that followed, including the Systematic Review of the Efficacy and Safety of Fluoridation conducted recently in Australia http://www.nhmrc.gov.au/publications/synopses/eh41syn.htm and Health Canada’s review of fluoridated water http://www.hc-sc.gc.ca/ewh-semt/pubs/water-eau/2008-fluoride-fluorure/index-eng.php failed to identify even one double-blinded, randomized prospective clinical trial to prove that fluoridation works.

This means that the reviewers failed to show the level of evidence for efficacy that is required in North America for a medicine to be approved.  None of the studies conducted to date addressed whether fluoridation can reduce the prevalence or severity of early dental decay in nursing infants (baby bottle syndrome). A very large percentage of dentists in North America do not accept patients on government assistance because they lose money treating these patients.

In my opinion, Public health officials responsible for community programs are misleading the public by stating that ingesting fluoride “makes the teeth stronger.” Fluoride is not an essential nutrient. It does not make developing teeth better prepared to resist dental decay before they erupt into the oral environment (Limeback 1999).

Nearly all authorities (ADA, CDA, CDC etc.) now admit that the mechanism of fluoridation, if it works, works through topical mechanisms, not systemic. Saliva secretions from increased fluoride ingestion (fluoridated water) are 50 to 100 times LOWER than foods and beverages in the diet and 50,000 times lower than the fluoride levels in fluoridated toothpaste. Thus systemic fluoride secreted in the saliva is an insignificant source of topical fluoride.

2. Fluoridation is the main cause of dental fluorosis.

Fluoride doses by the end user can’t be controlled when only one concentration of fluoride is available in the drinking water.  Babies and toddlers get too much fluoride when tap water is used to make formula (Brothwell & Limeback, 2003). Since the majority of daily fluoride comes from the drinking water in fluoridated areas, the risk for dental fluorosis greatly increases (2006 NAS Report). This is born out by a systematic review of several published fluorosis studies (Hujoel et al 2009). Fluoridated tap water should not be used to reconstitute infant formula.

We have tripled our exposure to fluoride since fluoridation was conceived in the 1940s. This has lead to every third child with dental fluorosis (CDC, 2005). Fluorosis is not just a cosmetic effect. The more severe forms are associated with an increase in dental decay (2006 NAS Report) and the psychological impact on children is a negative one. Up to 10% of the children these days have objectionable (moderate) dental fluorosis. Severe fluorosis occurs in up to 3% of the population. These are not insignificant in terms of proportions of the population affected. Most children with moderate to severe fluorosis will seek extensive restorative work costing thousands of dollars per patient. Dental fluorosis can be reduced by turning off the fluoridation taps without affecting dental decay rates – see


3. Chemicals that are used in fluoridation have not been tested for safety.

All the animal cancer studies were done using sodium fluoride. There is more than enough evidence to show that even this form of fluoride has the potential to promote cancer because it accumulates in the bone and produces levels that are high enough to induce cancer (2006 NAS Report). Some communities use sodium fluoride in their drinking water, but even that chemical is not the same fluoride added to toothpaste. Most cities instead use hydrofluorosilicic acid (or its salt). H2SiF6 is concentrated directly from the smokestack scrubbers during the production of phosphate fertilizer, shipped to water treatment plants and trickled directly into the drinking water. It is industrial grade fluoride contaminated with trace amounts of carcinogens such as arsenic and radionuclides.

When fluoridation chemicals are used, arsenic levels are increased by as much as 1 parts per billion (10% of the maximum 10 parts per billion allowed by Health Canada and the EPA). Even at this level, the increased risk for cancer (Kurttio et al 1999) from the added arsenic is unacceptable and immoral.

In addition, using hydrofluorosilicic acid instead of industrial grade sodium fluoride has an added risk of increasing lead accumulation in children (Masters et al 2000; Coplan et al 2007; Maas et al 2007). In their study, the CDC confirmed that this observation holds true for people living in old houses (Macek et al 2006). Sawan et al (2010) showed how fluoride increases lead uptake in a strictly controlled animal model system. Furthermore, when lead is incorporated into tooth enamel it INCREASES the risk for dental decay (Pradeep & Hedge, 2013)

4. Fluoride negatively affects bone.

Cancer: Osteosarcoma (bone cancer) has been identified as a risk in young boys in a recently published Harvard study (Bassin et al 2006). The author of this study, Dr. Elise Bassin, acknowledges that perhaps it is the use of these untested and contaminated fluorosilicates mentioned above that caused the over 500% increase risk of bone cancer in young boys. The EPA was unsure about designating fluoride as a potential carcinogen in 2006 because it wanted to wait for the final study from the Harvard group (Kim et al 2011). The Kim study failed to refute the age-sensitive risk for osteosarcoma that Dr. Bassin found. As far as I know, the EPA has still to determine the carcinogenicity of fluoride.

Bone fracture: Drinking on average 1 litre/day of naturally fluoridated water at 4 parts per million increases your risk for bone pain and bone fractures (2006 NAS Report). A study by one of the leading profluoridation researchers in America showed that low daily intake of fluoride in the drinking water changed bone density in boys (Levy et al 2009). Since fluoride accumulates in bone with age, one of the concerns of the 2006 NAS committee was an increase risk for hip fracture or other bone fractures. Our own published study at our university on fluoride in bone (Chachra et al 2010) shows a negative effect on bone architecture in Torontonians who have lived only a portion of their lives in fluoridated Toronto. Fluoridation studies have never properly shown that fluoride is safe in individuals who cannot control their dose, or in patients who retain too much fluoride. For example, patients with renal failure have high fluoride in their bones and get renal osteodystrophy (Ng et al 2004).

5. Fluoride harms many soft tissue organs

The thyroid: Our 2006 NAS Report outlines in great detail the detrimental effect that fluoride has on the endocrine system, especially the thyroid. People who are deficient in iodine are especially negatively affected by fluoride in drinking water, even as low as 1 ppm.

The brain: In addition to the added accumulation of lead (a known neurotoxin) in children living in fluoridated cities, fluoride itself is a known neurotoxin. We are only now starting to understand how fluoride affects the brain. Several recent studies (reviewed by Choi et al 2012 at Harvard in a meta-analysis) suggest that fluoride in drinking water is associated with lowered IQ. Studies conducted by Luke (2001) showed that fluoride can be found in high amounts in the pineal gland and that it affects melatonin production.

My conclusion:

In my expert opinion, as a researcher, educator, dentist and past member of the NAS Subcommittee on Fluoride in Drinking Water, the evidence that fluoridation is more harmful than beneficial is now overwhelming and cities that reject considering ALL the recent data do so at risk of future legal action.


Dr. Hardy Limeback BSc, PhD, DDS
Professor Emeritus and Former Head, Preventive Dentistry,
Faculty of Dentistry,
University of Toronto


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