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Growth promoting hormone implants have been banned in the EU since 1988. The UK government has consistently opposed the ban on scientific grounds but dutifully supported it and introduced its ban in December 1986 well before the deadline.
The ban extends to imported beef from implanted cattle. The USA, where several hormone implant products are still licensed, considers the ban to be a non tariff trade barrier erected without proper risk assessment and has successfully pursued this view with the World Trade Organisation (WTO). The EU has maintained its ban and the outcome is a tariff war between the USA and EU.
In April 1999 the EU published scientific evidence that it claimed raised fresh concerns about the consumption of beef from treated cattle. Agriculture Minister Nick Brown requested the independent Veterinary Products Committee (VPC) to review the EU evidence. The report of an eminent VPC sub-group (October 1999) states that they were unable to support the EU conclusion that risks associated with the consumption of meat from hormone-treated cattle were greater than previously thought.
Steroid sex hormones are produced naturally in the human body and are important in the regulation of reproductive activity and growth. The main site of production of oestradiol is the ovaries; progesterone is produced in the ovaries and placenta, and testosterone in the testes. There is some production of the (oestrogenic) female hormone oestradiol in men and some production of the (androgenic) male hormone testosterone in women.
There are several synthetic steroids similar in basic structure to natural oestrogens and androgens. Another significant group of synthetic oestrogens of different structure is called stilbenes. Foods as diverse as eggs and cabbages contain steroid hormones, sometimes in unexpectedly high concentrations.
A number of natural and synthetic steroid hormones implanted in cattle as pellets or impregnated silicone under the skin of the ear at the start of the final finishing period produce remarkably consistent improvements in daily gain, feed conversion efficiency and carcass quality. These effects on growth give rise to their generic name, anabolic steroids. In general, oestrogens produce the greatest responses in male cattle and androgens in females. Combinations of oestrogenic and androgenic substances produce an additive response in male cattle.
The eating quality of beef from implanted and untreated cattle is similar. Residues in the meat are so low (parts per thousand billion) that ultra sensitive immunoassay techniques are required for detection. When natural hormone implants are used residues are little, if any, different from untreated cattle and residues of synthetic hormones are of the same order.
The VPC sub-group report points out that human consumption of residues from growth promoters is less than or similar to those in natural dietary ingredients such as eggs and far below amounts of hormones produced naturally by the human body. However, there would be a risk to humans from accidental ingestion of a whole implant. For this reason it is essential that cattle are implanted in the ear, which can be discarded after slaughter.
There had been controversy both in Europe and the USA about possible carcinogenic risks in beef from cattle implanted with stilbenes. In July 1981 they were banned in the EU with the agreement of all member states. (They are also banned in the US and other major cattle-producing countries.) However, there was disagreement within the EU about the use of five other implants including three natural hormones (oestradiol-17? testosterone and progesterone) and two synthetic substances (trenbolone and zeranol). These substances are still approved for use in the US and many other countries, including Australia, Canada and New Zealand.
A working group chaired by Prof G E Lamming was set up in 1981 to review the evidence. The group quickly reached the conclusion that the three natural hormones were safe but needed more experimental evidence on the two synthetic substances. Before they could report, events were overtaken by political pressure and a ban was announced. The group published its findings independently that trenbolone and zeranol did not present a risk to human health (Veterinary Record 24 October 1987). The VPC sub-group report broadly supports the conclusions of the Lamming committee, subject to reservations about the adequacy of residue data on zeranol and another synthetic steroid, melengestrol.
It is important to point out that in the 1970s there was just cause for concern about the use of hormones for growth promotion. In some EU member states where hormones were already banned, high doses of stilbenes in oily suspension were being injected directly into the shoulder muscle of veal calves. There were massive and persistent residues at the injection site that presented a serious risk to human health, especially if the contaminated veal was used in baby food.
Opponents of the ban argued that controlled use of implants was preferable to the black market that would inevitably follow a ban. So it has proved. A criminal black market in hormone products developed from bases in Belgium. Unscrupulous farmers implanted cattle in unusual sites, e.g. under the skin of the tail, to try and conceal the implants. This raised the risk of whole implants inadvertently entering the human food chain.
Worse still, farmers turned to other undesirable products, notably ?agonists such as clenbuterol administered as a feed additive. These products have a legitimate role in veterinary medicine but are not licensed in the EU for growth promotion.
The ?agonists have remarkable effects on the lean content of the carcass to an extent that conformation becomes more muscular which raises the sale price per kg of carcass. However, ?agonists have the highly detrimental characteristic of making beef tough and powdered formulations present risks to operators, and there have been reports of toxicity in consumers caused by residues in beef liver.
Illegal use was probably never significant in Great Britain but was rampant in European feedlots and in Ireland clenbuterol gained the doubtful sobriquet 'angel dust'. It is uncertain to what extent illegal use persists but it is probably much less now than in the years immediately following implementation of the ban.
There is no pressure within the EU to reverse the ban. The matter has passed beyond science into consumer and trade politics.
This note was prepared for BSAS by Dr David Allen, Beef Industry Consultant.
For further copies of this paper, please contact BSAS on 0131 445 4508.