Fluoride Action Network

Report into effects of water fluoridation expected

Source: Irish Medical Times | March 5th, 2015 | By Lloyd Mudiwa & Dara Gantly
Location: Ireland

A report into research commissioned by the Health Research Board at the request of the Department of Health into the benefits or disadvantages of the fluoridation of Irish water supplies is expected to be published this month, IMT has established.

Dr Diarmuid O’Donovan, Director of Public Health in the HSE, revealed the report was completed early in January and has been sent for international peer review to ensure accuracy and objectivity.

“It will be prepared for publication by the end of March and will be publicly available then. No detail of the report will be discussed until it is published,” he said.

Fluoridation is national policy and local authorities fluoridate the water on behalf of the HSE. There were concerns about fluoridation, Dr O’Donovan said, and there was a review under way to examine the evidence (positive and negative) of the impact of water fluoridation at its current level (0.6 to 0.8 part per million) on the health of the population and on the environment, and to also summarise gaps in the evidence base reported in the literature.

The review, based on a synthesis of published research, was broadened to include assessment of the impact in areas with high levels of naturally occurring fluoride, higher than the levels associated with community water fluoridation, he said.

Nonetheless, Dr O’Donovan maintained that there was strong evidence for the benefits of fluoridation, pointed out that Cochrane Review meta-analyses were internationally recognised as the gold standard in the evidence-base for medicine and healthcare.

“A review of 214 scientific studies found that fluoridation was associated with a reduction in dental decay and that there was no evidence of adverse potential effects,” he commented. “The US Centers for Disease Control says that water fluoridation is one of the top 10 public health interventions of the 20th Century,” he added.

However, a new study published in the Journal of Epidemiology & Community Health (doi:10.1136/jech-2014-204971) has found that water fluoridation above a certain level is linked to 30 per cent higher than expected rates of hypothyroidism in England — findings that have prompted the researchers to call for a rethink of public health policy to fluoridate the water supply in a bid to protect the nation’s tooth health.

In areas with fluoride levels above 0.7 mg/l, the authors found higher than expected rates of hypothyroidism than in areas with levels below this dilution. High rates of hypothyroidism were at least 30 per cent more likely in practices located in areas with fluoride levels in excess of 0.3 mg/l.

This was an observational study, so no definitive conclusions could be drawn about cause and effect, and the researchers emphasised that they were not able to take account of other sources of fluoride found in dental products and food and drink.

However, they pointed out that their findings echoed those of previous research, and that while they were only able to look at diagnosed hypothyroidism, there might also be other cases of impaired thyroid function that have not yet been diagnosed and treated.

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