LIBERAL Democrats are set to block Labour plans to add fluoride to Scotland’s water.

And a compromise proposal – holding local referendums on the issue – is also likely to be thrown out.

Scotland has an appalling record of dental health, with 55 per cent of children having dental disease by the age of five.

Deputy health minister Tom McCabe, who has been put in charge of the issue, is eager to press ahead with fluoridation, seen by supporters as the best way of tackling the problem of rotten teeth.

But many Lib Dems view it as “mass medication” and an infringement of civil liberties. And official party policy is against adding fluoride to the water supply.

Lib Dem health spokesman Mike Rumbles said:

“We all accept the need to tackle the issue of dental decay, but if we can focus on troublespots we can do it by giving free fluoride toothpaste to people and make sure there is a proper education campaign.

“However, I understand if it came to a vote it would be a conscience issue.

“I would vote against it and I would urge my Lib Dem colleagues to vote against any attempt to fluoridate the water supply.”

A public consultation on the issue closed 18 months ago, following a massive response.

About 1700 letters and e-mails were received, along with more than 1000 pre-printed campaign postcards against the move and several petitions with more than 6500 names.

But the Scottish Executive has still not announced what it plans to do.

A working group has been established involving Labour and Lib Dem MSPs to try to resolve the impasse between them and Mr McCabe has suggested a compromise involving individual health boards holding referendums on the matter.

But Mr Rumbles added: “As far as I’m concerned, it is wrong to mass medicate the water supply and allowing someone else to do it is equally wrong.”

Unless most of the Lib Dems can be won over, the Labour-led Executive will risk defeat in any vote.

Scottish Nationalists, Conservatives, Greens and Scottish Socialists have all spoken out against putting fluoride in the water.

A Lib Dem insider said: “This is going to be a huge subject. It is a burning issue for a lot of people.”

Edinburgh West MSP Margaret Smith said she had an open mind. “I would have to be persuaded,” she said.

Mike Pringle, MSP for Edinburgh South, also said he had no fixed view on the matter and was ready to listen to the arguments.

The Executive has said it wants to raise the number of five-year-olds with no dental disease from 45 per cent across Scotland to 60 per cent by 2010.

Some experts say that is unattainable without fluoridation of the water supply.

Research shows children at the ages of five and six in places such as Moray, where the water supply has large amounts of fluoride occurring naturally, and Newcastle and Birmingham, where fluoride is deliberately added, have over 90 per cent fewer decayed teeth than those living in non-fluoridated areas.

Greater Glasgow NHS board announced last month it is to hold its own public consultation on fluoridation with a decision due in December.

An Executive spokesman said no decision had yet been made, but it hoped to publish its response as soon as possible.