Butter and cream produced here before the removal of carbosan copper from cattle rations is to be tested for dioxin, it was learned yesterday.
Three weeks ago routine testing of ingredients for cattle feed imported from the US found that the carbosan copper had been contaminated.
The Department of Agriculture, Food and Rural Development had seized the 3.5 tonnes of feed ingredients from a premix plant before it was included in any animal feed.
In a follow-up operation, it asked the feed industry to withdraw and destroy any feed which might contain carbosan copper.
When the carbosan copper, which was imported via the UK, was found to be dioxin contaminated, the Department banned its use from all animal feed.
The Food Safety Authority of Ireland, which was involved in the investigations, said at the time that the batch seized presented no threat to public health.
The Department of Agriculture, which had alerted the EU's Rapid Alert System to a possible problem, said last night that it was testing butter made before the banning of carbosan copper in cattle feed.
It said that as a result of the Irish experience other EU countries were being asked to check for possible contamination from the shipment and tests were being carried out in the UK and France.
"We are carrying out our tests for certification purposes, to protect our exports because we are satisfied no contamination occurred here from the substance," said a spokesman.
He said the Food Safety Authority was conducting tests on cream at co-ops and other milk processing centres.
Minute quantities of minerals are used in cattle feed for animals which are being farmed intensively.