One of two studies published by the European Commission concluded that six hormones used to stimulate growth in cattle pose threats of differing severity and that children may be specially at risk. However, it highlighted one, 17 beta-oestradiol, which it said must be considered a complete carcinogen with "both tumour-initiating and tumour-promoting effects".
"In plain language," European Union scientists argued, "this means that even small additional doses of residues of this hormone in meat arising from its use as a growth promoter in cattle has an inherent risk of causing cancer.
"Of the various susceptible risk groups," the scientists added, "prepubertal children is the group of greatest concern."
The findings could have a serious effect on transatlantic relations as diplomats on both sides try to avert a full-scale trade war. Since the bitter dispute over the EU's banana imports, the US has been lobbying hard to secure the removal of Europe's decade-old embargo on US hormone- treated beef.
The US has the support of the World Trade Organisation, which ruled in February that the EU must lift the ban by 13 May, unless it has enough scientific evidence to prove that the meat is harmful.
Last week, the EU announced a widening of the terms of the embargo from 15 June to include meat imported from the US and marketed as "hormone- free". That ban was ordered by the Standing Veterinary Committee after scientific tests showed that 12 per cent of supposedly hormone-free US beef contained hormone residues.Reuse content