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• Misleading representation of SCHER Report
  John F Beal
  Published on: 16 February 2017
• A missed opportunity? Fluoridation and hypothyroidism - correlation or causation.
  Douglas W Cross
  Published on: 11 August 2016
• a cup of tea
  Michael E Godfrey
  Published on: 23 March 2016

• Published on: 16 February 2017

  Misleading representation of SCHER Report

  • John F Beal, Hon Senior Lecturer in Dental Public Health
  • Other Contributors:
    • Michael A Lennon

  Sirs, Peckham et al's selective reporting of the findings of the SCHER report (2011) risks giving readers of your journal a highly misleading interpretation of data on the fluoride intake of children in areas supplied with water containing 1 mg/l of fluoride.

  Careful analysis of the full detail of the SCHER report (2011) shows that 6 to 12 year olds will not exceed the recommended upper limit (UL) of 2.5 mg per...

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  Sirs, Peckham et al's selective reporting of the findings of the SCHER report (2011) risks giving readers of your journal a highly misleading interpretation of data on the fluoride intake of children in areas supplied with water containing 1 mg/l of fluoride.

  Careful analysis of the full detail of the SCHER report (2011) shows that 6 to 12 year olds will not exceed the recommended upper limit (UL) of 2.5 mg per day even if they are routinely taking fluoride supplements (as tablets, drops or lozenges), swallowing 10% of their toothpaste, and consuming around two or three times as much water per day as the European Food Safety Authority (EFSA) estimates to be likely. It also shows that 1 to 6 year olds are very unlikely to exceed the recommended UL of 1.5 mg of fluoride per day unless they are routinely taking fluoride supplements, swallowing around 40% of their toothpaste and possibly also putting more than the recommended amount of paste on their brush.

  SCHER's estimates were based on figures provided by EFSA which, in its earlier 2005 report, states: "Children aged 1-8 years have fluoride intakes from food and water well below the UL provided the fluoride content of their drinking water is not higher than 1.0 mg/l." It also states: "For children older than eight years and adults the probability of exceeding the UL on a normal diet is estimated to be low. However, consumption of water with a high fluoride content, e.g., more than 2-3 mg/l, predisposes to exceeding the UL." The target level in fluoridation schemes in England is 1 mg/l.

  The above suggests that Peckham et al have not correctly represented what SCHER was saying in the body of its report. Further, it should be borne in mind that medical and dental practitioners in England do not prescribe fluoride supplements to children in fluoridated areas and that parents are advised to supervise their children's toothbrushing up to about the age of seven - in both fluoridated and non-fluoridated areas - to ensure that they put only a pea-sized amount of toothpaste on the brush and they do not swallow any after they have finished brushing.

  Finally, in the specific context of the Peckham et al hypothesis on hypothyroidism, it is worth noting SCHER's conclusion that "a systematic evaluation of human studies does not suggest a potential thyroid effect at realistic human exposures to fluoride."

  Yours sincerely,

  Michael A Lennon OBE Professor Emeritus University of Sheffield

  Dr John F Beal MBE Hon Senior Lecturer in Dental Public Health University of Leeds

  Conflict of Interest:

  Dr John Beal - Vice Chair, British Fluoridation Prof Michael Lennon - Scientific Advisor, British Fluoridation Society

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  Conflict of Interest:
  None declared.

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• Published on: 11 August 2016

  A missed opportunity? Fluoridation and hypothyroidism - correlation or causation.

  • Douglas W Cross, Environmental Consultant

  The analysis of data on the prevalence of hypothyroidism in areas with different concentrations of fluoride in the public drinking water supplies, by workers at the University of Kent,[1] is interesting but by no means conclusive. The authors rightly emphasise that their findings do not prove that fluoridation causes people to develop the condition,but only that there is a clear correlation. In fact this study raises m...

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  The analysis of data on the prevalence of hypothyroidism in areas with different concentrations of fluoride in the public drinking water supplies, by workers at the University of Kent,[1] is interesting but by no means conclusive. The authors rightly emphasise that their findings do not prove that fluoridation causes people to develop the condition,but only that there is a clear correlation. In fact this study raises more questions that it actually answers.

  Public Health England's Water Fluoridation Health Monitoring Report for England 2014 [2], so widely cited by supporters of the practice, is in fact riddled with statistical improprieties. It has become the norm for the dental public health sector to dismiss all complaints that fluoridation is harmful to thyroid function, and the 2014 PHE report fails to mention it at all. This study appears to challenge that position.

  In this new study the authors report that there is an at least 30% greater prevalence of hypothyroidism in areas with more than 0.3mg/l of fluoride in the public water supplies. However, this limit is not a threshold; it is merely the dividing point between two out of the three arbitrarily chosen ranges of fluoride concentration in drinking water. The apparent 'boundary' between a safe and an unsafe concentration of fluoride is an experimental artifact, not a representation of what happens in real life.

  So it is only permissible to draw a generalised conclusion from this study. This is disappointing. Fluoride overdose is now endemic - half of all children growing up in fluoridated water areas develop at least some detectable form of dental fluorosis, the only visible biomarker for incipient fluoride toxicosis. In non-fluoridated areas the prevalence of this condition is around one quarter.

  Clearly, other sources of bioavailable fluoride are already contributing to this undesirable body-burden. If there is a causative link between fluoride absorption and thyroid function, then it is reasonable to propose that all bioavailable fluoride sources may contribute to the problem. This would imply that that many people may be prone to hypothyroidism due to the increasing background contamination of our foods and dental products with fluoride. If so, this might suggest that the extra fluoride in some water supplies may be pushing more people over the threshold at which GPs start to notice that more of their patients have this condition.

  Another missed opportunity?

  There is one intriguing feature of this study that illustrates what could be done to clarify our understanding of the medical consequences of water fluoridation, if only the government would stop prevaricating and put some real effort into sorting out the whole mess.

  This new study compares hypothyroidism prevalence across the country with data on the average annual fluoride level maintained in drinking water supplies during 2012. Those of us in the Lake District will be aware that, although the authors show (correctly) that West Cumbria was not fluoridated in 2012, in fact the region has been fluoridated since around 1970.

  The local water supplier, United Utilities, shut down its fluoridation activities in 2007 to carry out maintenance, resuming fluoridation in September 2013. So for six years those people who had been drinking fully fluoridated water for up to almost forty years had their access to the 'benefits' of this product interrupted.

  Both accidents and anomalies can provide unique opportunities to examine novel questions that that may never be considered when looking at generalised data, and this six year halt to fluoridation in West Cumbria provided just such an opportunity. So it is unfortunatle that the new study does not reveal whether the risk of hypothyroidism in West Combria is elevated.

  It would have been enormously interesting to learn how prevalent hypothyroidism was in this area before and during, and is now after, that fluoride-free interlude. Was the prevalence of the condition elevated before fluoridation stopped? If so, did it fall, during the hiatus in supply? And has it increased again since?

  Presumably raw data are available to answer these questions, but have not yet been analysed. It would be fascinating to see whether or not the prevalence of hypothyroidism changed. The results of such an analysis might yet provide support for proposing that correlation may reasonably imply causation and, if so, whether stopping the practice in other fluoridated areas might bring similar relief to the afflicted.

  Douglas Cross, CSci, CBiol. FSB.

  References

  1. Peckham S, Lowery D, Spencer S.(2015) Are fluoride levels in drinking water associated with hypothyroidism prevalence in England? A large observational study of GP practice data and fluoride levels in drinking water. J Epidemiol Community Health 2015;0:1-6. doi:10.1136/jech-2014-204971

  2. Public Health England. Water Fluoridation. Health monitoring report for England 2014. PHE publications gateway number: 2013547, 2014.

  Conflict of Interest:

  None declared

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  Conflict of Interest:
  None declared.

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• Published on: 23 March 2016

  a cup of tea

  • Michael E Godfrey, Doctor

  It appears somewhat bizarre that authorities have ignored a widely consumed source of fluoride from tea although insisting on community water fluoridation (CWF) to reduce dental decay. Notably, black tea in commercial teabags contains significant levels of fluoride. This is especially so when sourced from Kenya with volcanic soils compounded by fluoride from superphosphate fertilisers. Mechanical harvesting then includes...

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  It appears somewhat bizarre that authorities have ignored a widely consumed source of fluoride from tea although insisting on community water fluoridation (CWF) to reduce dental decay. Notably, black tea in commercial teabags contains significant levels of fluoride. This is especially so when sourced from Kenya with volcanic soils compounded by fluoride from superphosphate fertilisers. Mechanical harvesting then includes older leaves with higher fluoride content than the young hand- picked tips. Habitual tea drinkers with a daily consumption of 3 cups of tea could already be obtaining more than adequate or safe fluoride intake based on the WHO (2002) upper limit recommendations of 2mg/day for children and 4mg for adults. Peckham's multicentre GP study revealing 30% higher hypothyroidism in areas where the water supply exceeded 0.3ppm of fluoride must raise serious questions regarding HFSA toxicity as nationwide, the British are traditionally tea drinkers. Thus all areas would already be getting fluoride from tea yet only those with CWF had increased hypothyroidism rates.

  Conflict of Interest:

  None

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  Conflict of Interest:
  None declared.

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