THE people of Greater Manchester could be asked as early as next year whether they want fluoride in the water.

But the scheme could cost up to £100m.

The possible cost is included in a report for local health chiefs who will have to decide whether to take the proposals any further.

They are now sending the report, which makes no recommendations, to the north west's 24 primary care trusts (PCT). The report outlines four possible schemes - costing between £35m and £102m to set up - for adding fluoride to the water system in parts of the region. But all of them include most of Greater Manchester.

The area has some of the worst dental health in the country with thousands of children suffering from tooth decay. In Birmingham, where the water is fluoridated, there are far fewer problems with children's teeth.

The British Dental Association say putting fluoride into some water supplies `could dramatically reduce the levels of tooth decay and give children a decent start in life'.

But anti-fluoride campaigners say it is potentially dangerous mass medication and oppose a public consultation, claiming people are being misled.

The report - by the Fluoridation Evaluation Group - also looks at other ways of giving youngsters fluoride including adding it to milk, giving out fluoride toothpaste, applying fluoride varnish to children's teeth and a public education scheme.

It found that schemes where fluoride is added to the water supply can increase the risk of fluorosis - staining on the teeth - but found no evidence that it led to a higher chance of bone fractures or cancer. If PCT bosses opt for a public consultation it would be run by regional health bosses at NHS North West and last for four months.

They have looked at four options: to add fluoride to the entire north west water supply (80 water plants); water supplied to Greater Manchester, Merseyside and parts of Lancashire (21 plants); Greater Manchester, Merseyside, parts of Lancashire and Cumbria (21 plants); 18 plants which supply most of Greater Manchester and Merseyside and parts of Lancashire and Cumbria. The schemes would cost between £2m and £6.5m a year to run.

Five-year-old children in Manchester have an average of 2.3 decayed, missing and filled teeth compared to 1.47 in the north west as a whole and just one across England.

Sheila Jones, from the British Fluoridation Society, said: "We would very much welcome a public consultation.

"If we had the same level of fluoride in water in Greater Manchester as there has been in Birmingham since 1964, 6,000 more five-year-olds would have not had tooth decay at all."

Steve Clarke, of Manchester Against Fluoridation, said Greater Manchester was being `sold a lie' by the pro-fluoride lobby. He said: "We are looking at spending tens of millions of pounds on something which doesn't work when the health authorities won't spend a few thousand on proven drugs for people with cancer."

Lester Ellman, of the British Dental Association, said: "In general most dentists are in favour of fluoride."