Naturally occurring uranium poses a health risk in many parts of the State where the metal is present at elevated levels in drinking water, the conference on geological hazards heard.
A "significant percentage" of the 100-150,000 private wells in the State could contain high levels of uranium, which can cause cancer or kidney disease, Mr Kevin Cullen told the conference organised by the Institute of Geologists of Ireland.
Mr Cullen, who is managing director of environmental consultants White Young Green Ireland, said householders in areas where high levels were likely should have their wells tested for uranium. Where high levels were found, they should have their water supply treated or seek an alternative source.
Among the areas at risk were the south-east, Co Donegal and Co Galway, he said. A tributary of the River Slaney which contributes to a water supply has been found to contain uranium levels between three and six times the recommended level allowed in Canada. In the same area, a private well recorded a level almost 30 times that allowed in Canada.
While naturally occurring uranium is considered a hazard because of its chemical toxicity, the radioactive dose it produces in drinking water is regarded as safe. The EU had not set a recommended level of uranium in drinking water, Mr Cullen said.