The Government wants 40 per cent of England’s water supply to be fluoridated to reduce high levels of tooth decay. But its critics say it has been linked to conditions such as hypothyrodism (underactive thyroid gland). Here we explain what you should know.

Q: What is fluoride?

A: A naturally occurring mineral found in water and some foods (such as tea and fish). It can also be chemically produced – as in toothpaste. Fluoride strengthens tooth enamel and makes teeth more resistant to acid attacks.

Q: What is water fluoridation? How does it work?

A: ‘Fluoride, like other minerals, is a natural constituent of all water supplies; fluoridation is the process of topping up low natural levels to a safe level known to be beneficial to dental health – around one part of fluoride to one million parts of water,’ says Michael Lennon, professor of clinical dentistry at the University of Sheffield and adviser to the British Fluoridation Society.

Fluoride at this level occurs naturally in water supplies in some places throughout the world. The purpose of fluoridation is to reduce tooth decay.’

Q: Who has fluoridated water?

A: Only ten per cent of the UK’s water supplies are fluoridated – mainly in the West Midlands and North-East England, which were fluoridated in the Sixties. Worldwide, about 355million householders receive fluoridated water, including about 70 per cent of the US population.

Q: Why do we need fluoride in water?

A: ‘In fluoridated areas children experience less toothache and have fewer dental abscesses. Adults keep more of their own teeth for longer and suffer less root decay, and the cost to the NHS is reduced substantially,’ says Prof Lennon.

Q: Does drinking fluoridated water really protect teeth better than a fluoride toothpaste?

A: ‘No,’ says Paul Connett, professor of chemistry at Lawrence University in New York and scientific adviser to the Pure Water Association. ‘Leading researchers are now acknowledging that fluoride’s benefits are mainly topical (applying it directly to the teeth) and not systemic.

‘In other words, you don’t have to swallow fluoride to protect teeth. World Health Organisation figures show no difference in tooth decay in 12-year-olds between the vast majority of European countries which are not fluoridated and the few that are.’

Q: What are the other worries with fluoride?

A: Excess fluoride can cause dental fluorosis, where the tooth enamel becomes mottled and discoloured from too much fluoride while the permanent teeth are still developing. Studies have also linked fluoridation with hypothyroidism (underactive thyroid), bone diseases, cancers, infertility, early onset of puberty and hyperactivity. Eighteen studies have also shown drinking fluoridated water lowers IQ.

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