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Fluoridation of drinking water supplies: tapping into the debate

By Karen Blakey and Richard J. Q. McNally


Since their introduction in the United States in the 1940s, artificial fluoridation programmes have been credited with reducing tooth decay, particularly in deprived areas. They are acknowledged by the US Centers for Disease Control and Prevention as one of the ten great public health achievements of the 20th century (alongside vaccination and the recognition of tobacco use as a health hazard). Such plaudits however, have only gone on to fuel what is an extremely polarised ‘water fight’. Those opposed to artificial fluoridation continue to claim it causes a range of health conditions and diseases such as reduced IQ in children, reduced thyroid function, and increased risk of bone cancer. Regardless of the controversy, the one thing that everyone agrees upon is that little or no high quality research is available to confirm or refute any public concerns. The York systematic review of water fluoridation has previously highlighted the weakness of the evidence base by acknowledging the quality of the research included in the review was low to moderate.

Fluoride changes the structure of tooth enamel making it more resistant to acid attack and can reduce the incidence of tooth decay. This is why it is added to drinking water as part of artificial fluoridation programmes. The aim is to dose naturally occurring fluoride to a level that provides optimum benefit for the prevention of dental caries. The optimum range can depend on temperature but falls within the range of 0.7-1.2 parts per million (ppm) for Great Britain. Levels lower than 0.7ppm are considered to provide little or no benefit. Drinking water standards are set so that the level of fluoride must not exceed 1.5ppm in accordance with national regulations that come directly from EU law.

Glass-half-full

Severn Trent Water, Northumbrian Water, South Staffordshire Water, United Utilities, and Anglian Water are the only water companies in Great Britain that artificially fluoridate their water supply to a target level of 1 ppm. The legal agreements to fluoridate currently sit with the Secretary of State, acting through Public Health England, although local authorities are the ultimate decision makers when it comes to establishing, maintaining, adjusting or terminating artificial fluoridation programmes. As a programme dedicated to improving oral health, all of the associated costs come from the public health budget. Therefore, it is important to know that the money is being spent in the most effective way.

Our study has, for the first time, enabled an in-depth examination of the relationship between the incidence of two of the most common types of bone cancer that are found in children and young adults, osteosarcoma and Ewing sarcoma, and fluoride levels in drinking water across the whole of Great Britain. We have combined case data from population based cancer registries, fluoride monitoring data from water companies and census data within a computerised geographic information system, to enable us to carry out sophisticated geo-statistical analyses.

The study found no evidence of an association between fluoride in drinking water and osteosarcoma or Ewing sarcoma. The study also found no evidence that those who lived in an area of Great Britain with artificially fluoridated drinking water, or who were supplied with drinking water containing naturally occurring fluoride at a level within the optimal range, were at an increased risk of osteosarcoma or Ewing sarcoma.

It is important to note that finding no evidence of an association between the geographical occurrences of osteosarcoma or Ewing sarcoma and fluoride levels in drinking water, does not necessarily mean there is no association. Indeed, intake of fluids and food products that contain fluoride will not be the same for everyone and not taking this variation into consideration is one of the limitations of our study. Nevertheless, the methodologies we have developed could be used in the future to examine fluoride exposure over time and take other risk factors into consideration at an individual level. Such an approach could help the controversy surrounding artificial fluoridation ebb rather than flow.

Another important, although unexpected, finding arose from our use of fluoride monitoring data. We found that the fluoridation levels of approximately one third of the artificially fluoridated water supply zones were below 0.7ppm (the minimum limit of the optimum range). This finding reinforces that it is incorrect to assume an artificially fluoridated area is dosed up to 1ppm. In reality, it may be a lot less. A number of previous studies have mistakenly made this assumption making their conclusions unreliable. Our study shows that you cannot guarantee that fluoride levels in all artificially fluoridated water supply zones are close to the target level of 1ppm. Assuming that water fluoridation is a safe practice and evidence surrounding calculation of recommended dosage is reliable, this finding has economic implications in terms of public health. If public money is paying for artificial fluoridation shouldn’t the water supply zones be dosed up to a level that will provide the greatest benefit? If they aren’t then could it be that public money is merely being thrown down the drain?

Karen Blakey is a Research Assistant at the Institute of Health & Society, Newcastle University. She is interested in geographical information systems and the spatial analysis of disease registry data. Richard J.Q. McNally is a Reader in Epidemiology at the Institute of Health & Society, Newcastle University. He is interested in spatial epidemiology, the epidemiology of chronic diseases and the statistical analysis of registry data. They are authors of the paper Is fluoride a risk factor for bone cancer? Small area analysis of osteosarcoma and Ewing sarcoma diagnosed among 0-49-year-olds in Great Britain, 1980-2005, which is published in the International Journal of Epidemiology.

The International Journal of Epidemiology is an essential requirement for anyone who needs to keep up to date with epidemiological advances and new developments throughout the world. It encourages communication among those engaged in the research, teaching, and application of epidemiology of both communicable and non-communicable disease, including research into health services and medical care.

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Image credit: Glass half full. By Jenny Downing. CC-BY-2.0 via Wikimedia Commons

Recent Comments

  1. Maureen Jones

    Your analysis was of “0 – 49 year-olds”? You failed to do an age-specific analysis?

    “Intake and Metabolism of Fluoride”
    “Overall, an average of 86.8% of the dose was retained by the infants, which is about 50% higher than would be expected for adults. They concluded that “…the pharmacokinetics of fluoride in infants reveal(s) a completely different pattern compared to what has been found in adults.” There is a clear need for more information about the renal handling and general metabolism of fluoride in young children and the elderly.” Advances in Dental Research 8(1);5-14, June, 1994

    Both osteosarcoma and hip fracture incidence are significantly linked to water fluoridated at the “optimal” 1 ppm. In three published studies, osteosarcoma is linked to rapidly growing bone of children rather than to adult bone.

    1) Ph.D. dissertation student Elise Bassin, using the data collected by her Harvard professor Chester Douglass, first eliminated his data for adult males and females and then by looking at exposures for each year of age was able to uncover a 700% increased incidence of osteosarcoma for males exposed to fluoridated water (1 ppm ) between age 5 and 10.

    “The evaluation of age-specific effects distinguishes our study from the other investigations. Rothman (37) has warned that failure to identify the appropriate time window for exposure may result in misclassification which can adversely affect the ability to detect an association.”
    Bassin (2006) Cancer Causes and Control 17: 421-8.

    2) Likewise, the Journal of American Medical Association, August 12, 1992, Brigham City, Utah hip fracture study showed in Figure 1 that the age specific window-of-injury for women is the approximately fifteen years (perimenopause) prior to menopause, a period of increased bone remodeling and uptake of embrittling fluoride. This age specific window resulted in a 100% increase in hip fracture for women at age 75 and would most likely have been much higher had the women grown up on fluoridated water as well.

    Maureen Jones, Archivist for 20 years
    Citizens for Safe Drinking Water
    FluorideAlert.org
    Keepers-of-the-Well.org
    1205 Sierra Ave.
    San Jose, CA 95126
    408 297-8487

  2. jwillie6

    Every human being has the right to choose via Informed Consent.
    It is illegal for a doctor or a dentist to force anyone to take a drug or chemical.
    Regarding floride, it should be illegal for the government as well. Water fluoridation should be stopped everywhere immediately as it is nothing more than a legal way for chemical companies to get rid of toxic waste while profiting.
    The solution for the fluoridation issue is very simple.
    SIMPLE SOLUTION:
    1. Take the toxic waste fluoride chemical out of the drinking water.
    2. It is still legal and available, so those who wish to take it can then put fluoride in their own glass of water.
    3. Leave the rest of us out of it, giving everyone the freedom of choice.
    PROBLEM SOLVED FOR EVERYONE.

  3. Aidan O'Donnell

    As I doctor myself (and an informed one), I want fluoride in my drinking water. I want it there for my kids, I want it there for me, and I want it there for my community.

    Fluoride isn’t “toxic waste”. It’s present naturally in many mineral waters, and in many artificial beverages, including tea.

    My suggestion is that, where municipal water supplies are deficient in fluoride, it should be added. For those who don’t want fluoride in their water, fluoride-free drinks are still legal and available, so you can buy your own.

    But you might want to throw out your tea bags at the same time.

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