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Health effects of water fluoridation

9 July 2015

HRB conducts review and finds no definitive evidence that community water fluoridation has negative health effects.

The Health Research Board published an in-depth evidence review of existing research in relation to the health effects of community water fluoridation.

Dr Graham Love, Chief Executive at the Health Research Board says,

‘Having examined the research available, the HRB has found no definitive evidence that community water fluoridation is associated with negative health effects. Given the lack of peer-reviewed research and the inappropriate design of many studies to detect a causal relationship, further research would be required to provide definitive proof.’

The Department of Health asked the Health Research Board to determine ‘what is the impact on the systemic health of the population for those exposed to artificially fluoridated water between 0.4 and 1.5 parts per million (ppm) excluding dental health’.

There were two previously-published, highly-regarded systematic reviews on this topic; the York Review (2000)* and the Australian review (2007)**. The HRB review presents the evidence provided in these reviews and examines all additional research published in internationally peer-reviewed papers on the topic of fluoride and health effects between 2006 and June 2014***. This research related to musculoskeletal effects, IQ and neurological manifestations, cancer, cardiovascular disease, kidney disorders, thyroid disease, Down syndrome and mortality from any cause. 

In addition to examining research in areas of artificially fluoridated water between 0.4 and 1.5 ppm (non-endemic areas), the HRB also examined the research available  in areas where fluoride occurs naturally in the water at much higher levels (endemic areas). It is important to note that these endemic areas are in many ways different to community fluoridated areas such as Ireland, both in terms of the level of fluoride in the water and/or many other aspects pertaining to health, for example poor nutrition or the lack of essential vitamins and micronutrients.

A table summarising the findings, for both community fluoridated areas (such as Ireland) and endemic areas is available in the notes to editors below.

According to Dr Marie Sutton, lead author on the report at the HRB,

‘Research specifically examining the association between community water fluoridation and health effects is scarce. Most of the studies reviewed are not of a suitable design to prove, or disprove, a link between fluoride consumption and negative health effects.

Two studies that we reviewed in non-endemic regions did suggest a potential link between fluoride and negative health effects in the areas of bone health (osteosarcoma and bone density) and thyroid disease. Neither of these studies has the methodological rigour required to provide conclusive evidence that fluoride was responsible for these negative health effects.

Having examined the evidence, and given the lack of studies of appropriate design, further research would be required to establish any link between fluoride and negative health effects,’ concludes Dr Sutton.

The report can be viewed at the link below.

* McDonagh et al. (2000) A systematic Review of Water Fluoridation. York: NHS Centre for reviews and Dissemination, University of York.
**  National Health and Medical Research Council. (2007) A systematic review of the efficacy and safety of fluoridation. Canberra: NHMRC; Australian Government. 

*** There is a small overlap in the time period examined by the HRB and Australian review. This relates to completeness. There may have been a time lag between concluding the Australian Review and the publication of their report. Overlapping ensures no research study that happened during the time lag is overlooked.

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