A review of the practice of adding fluoride to water supplies has found no definitive evidence that it causes negative health effects.
Further research would be required to establish any link between fluoride and negative health effects, according to the Health Research Board, which carried out the review.
The authors found a paucity of international research specifically examining the link between community water fluoridation and health effects and decided most of the studies examined were not of a suitable design to either prove or disprove a link.
The Department of Health asked the board last year to determine the impact on health of the population exposed to artificially fluoridated water between 0.4 and 1.5 parts per million (ppm).
Water in Ireland is currently fluoridated at between 0.6 and 0.8 ppm, half the limit permitted by the World Health Organisation.
Considerable opposition
Water has been fluoridated in Ireland since 1964 as a way of improving dental health but there is considerable opposition to the policy.
A number of councils have voted against the use of fluoridation or asked for further health studies.
The board’s review relies heavily on two international studies on the topic - the York review from 2000 and an Australian review from 2007.
It also examines all additional research published in internationally peer-reviewed papers on the topic of fluoride and health effects between 2006 and 2014.
The review also examines research into “endemic areas” where fluoride occurs naturally in the water, often at high levels. This is not the case in Ireland.
‘No definitive evidence’
"Having examined the research available, the board has found no definitive evidence that community water fluoridation is associated with positive or negative systemic health effects," said Dr Graham Love, HRB chief executive.
“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 review found no definitive evidence to link fluoridation to increased bone fractures, reduced IQ, cancer, heart disease, kidney disorders, Down syndrome or increased mortality from all causes.
In relation to an alleged link to bone cancer, it said the literature pointed to “mixed” effects and no link had been proven. “Therefore, it is difficult to draw a definitive conclusion.”
One study has suggested a link between fluoridation and thyroid disease but the HRB review said there was no definitive evidence of this and more research was required.
