A group of Irish dentists has called for a ban on the addition of fluoride to tap water following a US study which found that exposure to fluoride increased the risk of a bone cancer in boys.

The rare cancer - osteosarcoma - accounts for about 3 per cent of childhood cancers. The study is a part of a doctorate by Dr Elise Beth Bassin for the Harvard School of Dental Medicine.

It found that boys exposed to fluoride between the ages of five and 10 were likely to suffer an increased rate of osteosarcoma between the ages of 10 and 19.

The research is still going through the peer review process but its findings have been highlighted by the Environmental Working Group, a Washington research organisation.

The group has asked that fluoride in tap water be added to the US government's classified list of substances known, or thought, to cause cancer.

Dr Don MacAuley, chairman of Irish Dentists Opposing Fluoridation (IDOF) said the findings did not surprise him as Irish dentists were seeing fluoride tooth damage every day in their work.

"And as the teeth are the windows of the skeleton we question what this chemical is doing to our patients' bones," he said. "Now we read more evidence that fluoride can cause bone cancer while our health minister plays a delaying game of forums and expert groups."

A spokesman for the Department of Health said the department was aware of the study but it noted that the research had not yet been published. "If the research is published, the Department of Health and Children would be happy to refer it to the expert body on fluorides and health for their consideration," the spokesman said.