Doctors want the Welsh Assembly to help force water companies to put fluoride in the national water supply.

The British Medical Association says fluoridisation would help stop tooth decay in young people.

The health watchdog wants ministers to pressure the UK Government for a law change, which would require water providers to add fluoride if suppliers demand it.

Fluoride in water

Hardens enamel coating of teeth Helps prevent tooth decay In UK, 10% of water supplies have fluoride Councils can request suppliers add fluoride Companies are not legally bound to include it Evidence source: NHS CRD, 2000

It believes the move would halve tooth decay amongst five-year-olds in deprived areas within five years.

"Tooth decay remains a significant public health problem in Wales, particularly in socially deprived areas, and dental health inequalities are widening," said Dr Bob Broughton, the BMA's Welsh secretary.

"Children from less well-off backgrounds may have five times more tooth decay than those in the highest social classes.

"Most water has an inadequate level of fluoride for protection against dental caries.

"In areas which do have adequate natural levels of fluoride in water, children have very low levels of dental caries.

"Every month of delay sees the inequalities in dental health widening."

Cancer claim

Opponents claim fluoride is a toxin that can cause cancer, bone diseases such as osteoporosis and Down's Syndrome.

Belgium's government is set to ban chewing gums containing fluoride because it fears it leads to brittle bone disease and nervous system damage.

But the NHS Centre for Reviews and Dissemination found children in fluoridated areas suffered 15% less tooth decay than those in other areas.

They had fewer decayed, missing and filled teeth because it hardened their enamel and there is no negative effect on heath, the informative body said.

This is just some of the conflicting research surrounding the topic.

About 10% of the UK's water supplies are fluoridated, with some local authorities asking water companies to add fluoride and others refusing it.