The Department of Agriculture last night banned the use of three trace elements in food for cattle as it awaits the results of dioxin tests on a tonne of pre-mix material.
The banned substances are carbosan copper, addarome cattle '97 and manganese oxide, in which preliminary testing revealed traces of dioxins.
Dioxins are potentially lethal if ingested in food and can build up in the body, causing cancers and other major health problems.
The Department yesterday said it believed the source of the contamination was in a batch of imported feed ingredients from the United States.
It seized the consignment and sent samples away for analysis, which is expected to take seven to 10 days.
It also advised the 10 other companies involved in pre-mixing for the feed industry not to use the three elements.
However, it said that any material already made up or on farms could be used because the existing testing regime would have identified any problems.
"The last batch was tested a month ago and found to be clear, so all feed or pre-mix made before then can be used," said a Department spokesman last night. He said all actions taken by the Department were purely precautionary.
"The quantities of these ingredients used in compounded animal feed are minute and are very unlikely to cause any problems.
"We are talking about one nanogram per kilogram and these are very, very minute quantities we're are talking about," he said.
The spokesman added that officials were satisfied that the Department now had possession of all of what is believed to be the dioxin-contaminated pre-mix material.
"We do not believe that any of the other pre-mix companies have imported material from the same source but nevertheless we have told them not to use any of the three elements involved in their product until this matter is resolved," he said.
He said the last batch containing the three suspect elements had been tested for dioxins a month ago and the Department was satisfied that there was no contamination then.
"For that reason there is no necessity to impose a ban on feed already made up but if necessary we will do so," he said.
He confirmed that the Department had informed the European Commission's alert system about the potential difficulty and was in contact with Brussels.
The Irish Commissioner, Mr David Byrne, who has responsibility for health and consumer protection, last year placed animal feed in the Rapid Alert System, which was set up as a result of a dioxin scare in Belgium.
This scare cost the Belgian food industry millions of euro when contaminated milk entered the food chain.