Australians have been reassured that fluoride in drinking water is effective and safe, despite international studies linking it to lower IQs and thyroid problems.

The National Health and Medical Research Council expects to maintain its support for fluoridation of water supplies, based on the findings of a review so far.

The NHMRC review of scientific evidence on water fluoridation and health is being conducted by University of Sydney researchers.

“Fluoridation of drinking water remains the most effective and socially equitable means of achieving community-wide exposure to the caries (tooth decay) prevention effects of fluoride,” NHMRC chief Warwick Anderson said on Wednesday.

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UK research published earlier this week found water fluoridation could be linked to underactive thyroid cases, which in turn are linked to depression, obesity and fatigue.

The University of Kent study said doctor’s surgeries in high-fluoride areas like the West Midlands were nearly twice as likely to report high hypothyroidism prevalence than Greater Manchester, where it wasn’t added to drinking water.

Underactive thyroid cases were 30 per cent more likely in the areas of highest fluoridation, or more than 0.3mg/litre.

In Australia, the recommended fluoride level is 0.6mg/litre to 1.1 mg/litre.

A 2012 Chinese study found children who lived in areas with high fluoride exposure had lower IQ scores than those in low-exposure areas.

However, the exposed groups had access to drinking water with fluoride concentrations up to 11.5 mg/litre, so concentrations were above the level recommended for public drinking water in Australia.

Most Australian towns and cities were fluoridated in the 1960s and 1970s.

Fluoride naturally occurs in the water. Water fluoridation is the topping up of these levels to strengthen teeth against tooth decay.

The NHMRC is expected to release a draft paper on the findings of its fluoride review by the end of the year.