Europeans are the world's fussiest eaters and the use of hormones in meat production is probably top of their blacklist of abhorrent practices. There is a deep-rooted mistrust when it comes to administering such growth promoters to cattle, even if significant amounts of hormones are naturally found in foods derived from animals, and even plants.

This attitude is not due to BSE, whose ramifications are still being felt. Cultural detestation of interference in food has taken hold, which the North American does not easily identify with. This is strengthening EU resolve in its determination to retain a bar on US beef, 90 per cent of which is produced using a combination of up to six growth hormones (banned by the EU since 1989).

Five of the hormones are used as ear implants in cattle. The most notorious, says the European Commission, is oestradiol 17 beta, a natural hormone. Other natural agents used are testosterone and progesterone, while synthetic versions are zeranol and trenbolone - the sixth, melangestrol acetate, is added to feed but is not of huge concern in Europe. "Lean muscle builder", clenbuterol (angel dust) is illegal on both sides of the Atlantic.

The sizing-up between the US and the EU has centred around scientific evidence to justify a ban. No one disputes that oestradiol causes cancer in high doses. But the EU is "still investigating health effects" - in the face of US scepticism. But in a sensational development within the past fortnight, the Commission veterinary committee on public health said it had uncovered new evidence of oestradiol's cancer link, notably "tumour-initiating and tumour-promoting effects".

It remains to be seen if the findings are new. Professor of animal husbandry, Prof. James Roche of UCD Veterinary College, notes that salt given in similarly high quantities would be cancerous. Equally, animals and humans would not survive without oestradiol. It is essential for reproduction, formation of mammary glands and milk production.

A "huge trial" is on-going within the US population and, to his knowledge, there have been no significant health problems. The hormone must be given correctly and in the appropriate dose, he adds. Oestradiol, for example, can be given as hormone replacement therapy when male cattle have testes removed - its use has been cleared by key regulators such as the US FDA, the World Health Organisation and UN Food and Agriculture Organisation.

Prof. Roche says the debate has moved on from science to politics, with trade now looming large. "Why is the US consumer happy and the European consumer is not? That is the real issue. European politicians have bowed to consumer pressure. The ban is on political grounds."

The roots of mistrust go back to the 1950s and use in high doses of an oestradiol product in cattle called DES. It led to increased vaginal cancers in women and cancer in the offspring of mothers with the condition. In Italy, babies feed on DES-treated meat developed breasts. "From that point on, hormones were damned in consumer minds," Prof. Roche says. A picture of a baby's head imposed on a female body on the cover of the German magazine Der Spiegel, implying "this is what hormones do to you", sealed their fate. Scientists, he contends, have failed dismally to convince consumers, and demonstrate the difference between safe and dangerous hormones, and between high and low doses. Illegal use of anabolic steroids is a different story, he stresses.

The Food Safety Authority of Ireland chief executive Dr Patrick Wall says permitting hormone-treated beef into Europe is not on the agenda as it is illegal and the EU veterinary committee view means it is not likely to gain access. From a consumer perspective, he would have concerns if relaxed regulations allowed widespread use of hormones.

The one outstanding question is whether the EU scientific committee discovered "new facts". A senior commission source told The Irish Times there were "new indications" that gave cause for concern. It remains to be seen when full details will be revealed. Depending on US retaliation, the EU may release the evidence to the World Trade Organisation (the referee who has sided with the US) in June.

Ultimately the EU will defend its ban even if there are no health concerns. It just so happens it may have scientific proof this time.