UKCAF website

Go to content

Main menu:

What the CDC fluorosis data really show

Documents > Science

The Fluoride Fantasy:
What the American CDC fluorosis data really mean.

Doug Cross, CBiol, FSB, Environmental Analyst (1)
8th December 2010

“The following tale of alien encounters is true. And by true, I mean false. It’s all lies.
But they’re entertaining lies, and in the end isn’t that the real truth?
The answer is no.” (2)

Last month the US National Center for Health Statistics (CDC) published a report (3) that claimed to show the prevalence of dental fluorosis amongst American teenagers. This has been seized on by both the pro- and the anti-fluoridation movements as evidence that water fluoridation both is and is not a danger to the public, and have published links to the document without further comment.

From my own examination of this report I believe that the way that these data have been presented could indeed be described as ‘entertaining lies’. Instead of accepting the authors’ claims at face value, a more skeptical scrutiny reveals that their conclusions are not merely wrong, they are highly misleading. CDC is well known for the strong pro-fluoridation bias in its reports, so it is worth back-tracking a little, to try to extract the real meaning of these newly disclosed data.

Fluoride poisoning - no threshold concentration that is not a threat to health.

Dental fluorosis is the only sign of chronic fluoride poisoning that is easily visible externally. It has only one cause - over-exposure to fluoride during early childhood. All forms of ingested fluoride, if present in excessive amounts, can lead to fluorosis, but in many regions the most significant source is drinking water.

In toxicological terms, the critical variable is the dose of a toxic substance - the more fluoride you swallow, the greater your risk of fluorosis.

Contrary to the assumption that there is an ‘optimal concentration’ of fluoride, there is in fact no concentration of fluoride in water that can be regarded as ‘safe’.(‘Tolerable’ has an entirely different meaning!) In its recent draft report to the European Commission the Scientific Committee on Health and Environmental Risk (SCHER) stated that
‘Systemic exposure to fluoride in drinking water is associated with an increased risk of dental and bone fluorosis in a dose-response manner without a detectable threshold.’ (4)

A change in the pattern - the water fluoridation ‘trade-off’ is no longer appropriate.

The ‘dose’ of fluoride that children swallow - measured by the concentration of fluoride in the water and the volume that they drink - has remained reasonably constant over the past half century, so the proportion of kids with fluorosis should have remained constant - the original ‘social contract’ whereby the balance between preventing dental decay and the development of fluorosis amongst a small proportion of children was accepted as a realistic ‘trade-off’.

But what has changed is the proportion of children within the American population that have actually been exposed that now develop fluorosis. So let’s look at these data again, only this time in their correct perspective.

The authors state that
In 1986–1987, 22.6% of adolescents aged 12–15 had dental fluorosis, whereas in 1999–2004, 40.7%
of adolescents aged 12–15 had dental fluorosis. . . . The prevalence of very mild fluorosis increased from 17.2% to 28.5% and mild fluorosis increased from 4.1% to 8.6%. The prevalence of moderate and severe fluorosis increased from 1.3% to 3.6%.

This obscures not only what has been happening, but also when. Since fluorosis develops in teenagers as the result of their exposure during early childhood, it is far more informative to relate these data to the average birth dates of these groups of adolescents. these were around 1973 in the first group, and 1988 in the second. So these fluorosis prevalence figures actually refer to the result of exposing American infants to fluoridated water between 22 and 37 years ago. So now we have to check what proportion of those infants would actually have lived in fluoridated water areas - and the result of that is startling.

Getting the numbers right - adjusting the CDC data to reflect the real world

The calculations of the prevalence of fluorosis in these two groups are given as their percentage values related to the entire adolescent population of the USA at the times the two studies were carried out. They do not relate to the actual ‘at risk’ populations of infants in 1973 and 1988. The proportion of all American children who lived in fluoridated water areas as infants changed substantially between those two years. So I have used CDC’s own data on the growth of fluoridation in the USA(5) to calculate how the raw data need to be adjusted to give a true indication of what happened to these two sets of infants.

According to CDC, only around 40% of American public water supplies were fluoridated in 1973, and this increased to around 56% by 1988. Today it seems to be levelling off at around 60-62%.

So the corrected prevalence of fluorosis in the first group is 22.6% / 0.40, or 56.5%, and in the second is 40.7% / 0.56, or 72.7%. That’s right - the proportion of children born around 1988 and who lived in fluoridated water areas, and who then went on to develop dental fluorosis, was actually around three quarters! The CDC claim that ‘less than one-quarter of persons aged 6-49 had dental fluorosis’ in 2004 is therefore grossly misleading, and appears designed to reassure the American public that it is safe to continue the expansion of the practice across the country. Nothing could be further from the truth.

Using these same correction factors, the prevalence of moderate and severe DF in children born around 1973 was not, as CDC claims, 1.3%, but 2.8% , whilst 6.9% of children born around 1988 and raised in fluoridated water areas later developed moderate or severe fluorosis. This is an increase of 150% in only fifteen years.

The significance of the rising proportion with fluorosis - recent increase in fluoride bioavailability

Overall, the proportion of ‘at risk’ American teenagers who developed all levels of fluorosis rose by 36% over that fifteen year period - a rise of over 2% annually. The severity of the condition also become greater, yet nowhere does the CDC study remark on this crucial escalation in the proportion of children developing fluorosis.

Remember, too, that these corrected data refer to children born no later than around 1988 - twenty years or so ago. If this trend has continued at a similar rate, then this suggests that virtually all children living in fluoridated water areas of America are now liable to develop some degree of dental fluorosis, with perhaps one in ten suffering from the most severely disfiguring forms.

This is a social and psychological disaster for young people at this emotionally vulnerable age, and it is undoubtedly not confined to mainland United States of America. Evidence of a similar escalation in fluoride toxicosis has emerged from a number of other states. For example, in Singapore, fluoridated since 1957, the prevalence of dental fluorosis amongst all children was 82.6% in 1996, even though the water contained 0.7mg/l of fluoride (6).

A world-wide problem

This epidemic of chronic fluoride toxicosis is not confined to areas where water is artificially fluoridated. Over a period of several thousand years, right up to the present, both dental and skeletal fluorosis have been extremely common amongst people of the Dilmun Culture in Bahrain, Their only significant source of ingestible fluoride has for centuries been an aquifer containing water with 1.3mg F/litre. From archaeological remains we know that up to 80% of adult teeth were carious. So dental decay was rife, yet in these same communities, the prevalence of dental fluorosis was around 50%, and up to 20% of the population had moderate or severe fluorosis.(7)

This convincingly refutes exposes the claim that fluoride prevents dental caries - most adult teeth in this population were rotten even when there was allegedly enough fluoride to protect them against decay. From this evidence, it is quite clear that fluoride does not prevent tooth decay.

Rise in fluorosis in unfluoridated communities.

But we now see that the prevalence of fluorosis is also increasing amongst people in unfluoridated communities. Since the ‘dose’ rate of fluoride in fluoridated water has remained virtually constant, the growth of chronic fluoride poisoning in all communities cannot be attributed to water fluoridation alone. Other sources of fluoride pollution are contributing to the growth of fluoride toxicosis, including the proliferation of fluorinated compounds used in agriculture and food processing that increase the human body burden.

As the proportion of people in a community who develop fluorosis approaches 100%, as may be happening now in America, any further rise in exposure to environmental sources of fluoride will not be reflected in the only visible indicator, dental fluorosis, in fluoridated water areas. The only measure of the pandemic of chronic fluoride toxicosis derived from other sources will be in the continuing rate at which the proportion of people in unfluoridated communities develop fluorosis.

Tackling the global problem of rising fluoride contamination.

In the early days of fluoridation, bioavailable forms of fluoride were rare, Now, thousands of complex fluorinated substances pervade our environment, and form a chemical threat that is only just becoming recognised within mainstream science. We cannot tolerate the ‘entertaining lies’ of the fluoridation proponents any longer - they are not based on honest and impartial skepticism but on a deliberate evasion of the scientific approach to evidence. Our children are the victims of their deceit.

These adjusted data confirm what other workers have already proposed. Fluorinated compounds are now becoming vastly more threatening environmental contaminants that they were back in the 1950s and 1960s, when water fluoridation was in its infancy. As Ekstrand et al noted a decade ago
fluoride intakes of infants and children have shown a rather steady increase since 1930, are likely to continue to increase, and will be associated with further increase in the prevalence of enamel fluorosis unless intervention measures are instituted." (8)

It is imperative that we find ways to reduce their exposure to all forms of fluoride, and the most effective and immediate way to achieve that goal, even if only temporarily, is to turn off the fluoridation taps at our water treatment works. Stopping this deliberate contamination of our water supplies will at least provide a respite that will protect millions of newborn infants from some of the risk of fluoride poisoning. It will allow scientists around the world to tackle the insidious and growing problem raised by less obvious sources of environmental fluoride contamination.

All Water Companies, Councils and States involved in this discredited practice have a moral obligation to take immediate action to protect the children from this avoidable and totally unnecessary threat to their health and welfare.


1 Address for correspondence
2 Introduction to a 1997 episode of The Simpsons entitled “The Springfield Files” cited by Michael Shermer: What skepticism reveals about science: A skeptic’s journey for truth in science. Scientific American Magazine, July 2009.
3 Beltrán-Aguilar ED, Barker L and Dye BA. Nov 2010, Prevalence and Severity of Dental Fluorosis in the United States, 199–2004 National Center for Health Statistics (
4 SCHER (Scientific Committee on Health and Environmental Risk). 2010. Critical review of any new evidence on the hazard profile, health effects, and human exposure to fluoride and the fluoridating agents of drinking water. European Commission. Directorate-General for Health & Consumers. May 18.
5 Fluoridation Growth by Population, United States 1940–2006. National Center for Chronic Disease Prevention and Health Promotion (
6 Lo GL, Bagramian RA..Prevalence of dental fluorosis in children in Singapore. Community Dent Oral Epidemiol. 1996 Feb;24(1):25-7 (
7 Frohlich B, Littleton J. An Analysis of dental pathology and diet on historic Bahrain. Paléorient 1989 (15-2).. 59-75 (
8 Fomon SJ, Ekstrand J, Ziegler EE. (2000). Fluoride intake and prevalence of dental fluorosis: trends in fluoride intake with special attention to infants. Journal of Public Health Dentistry 60(3):131-9. ( )

Back to content | Back to main menu