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For the record

Growth hormones in livestock

In July 2006, a story ran about the use of hormonal growth promotors in farming. One article in the Daily Mail was headlined “THE HORMONE SCANDAL: will Britons be forced to eat hormone injected beef?” and asked “Could there be clearer proof of the arrogance and indifference of those who are supposed to keep our food safe than the muzzling of John Verral?”

You can get the Daily Mail articles here and here.

Professor Richard Sharpe, a member of the Veterinary Products Committee Working Group in question, here replies. Summary of his main points

  • The Working Group was not asked to comment on the rights and wrongs of using hormonal growth promotors in farming
  • The scientific evidence does not indicate that the use of hormones in farming presents a risk to public health
  • There are good reasons to oppose the use of hormones in farming livestock and to support the ongoing EU ban, but from current scientific evidence they do not pose a risk to human health

Full comments from Professor Richard Sharpe

The Veterinary Products Committee (VPC) set up a sub-committee in 2002 to look at the use of sex steroid-based hormonal growth promoters (in particular, oestradiol) in livestock. It was charged with assessing whether recently undertaken research studies (and earlier research) provided any clear scientific evidence that the very low levels of hormone residues in meat from such animals posed any health risk to consumers. The Working Group was asked to make its assessment of risk to humans based on available scientific evidence; it was not asked to make recommendations on the rights and wrongs of the use of hormonal growth promoters, nor did its remit allow the expression of personal views that were not based on scientific evidence or which lay outside of the focus of the Working Group.

It was considered that postmenopausal women and infants/children would be the most susceptible groups, as their endogenous levels of sex steroids, such as oestradiol, are naturally low. Arguably the most serious consequence of additional oestradiol exposure would be an increase in risk of breast cancer so, as a reference, the Working Group used detailed scientific evidence that has calculated how much breast cancer risk in postmenopausal women increases with increase in exposure to oestrogens from outside of the body (e.g., as the result of taking hormone replacement tablets). Based on these data and the available measurements of the levels of oestradiol in meat from hormone-treated animals, the Working Group concluded that consumption of such meat would have negligible impact on breast cancer risk. It was similarly concluded that such consumption by children was also unlikely to have significant impact, based on the available scientific evidence. However, the Working Group drew attention to the fact that there are large data gaps and a general lack of information on the effects of very low levels of oestrogens in children.

The Danish review quoted by the Soil Association and by John Verrall, a member of the VCP Working Group, did not address the effects of low levels of oestradiol exposure on the human fetus and infant, but showed that the blood levels of oestradiol in infants/prepubertal children have been seriously overestimated in earlier studies, on which safe limits of hormone exposure have been based. They have therefore suggested that children of this age may be much more susceptible than was thought to exposure to low levels of exogenous oestrogens, for example from eating meat from animals treated with oestradiol growth promoters.  However, this is only an interpretation as there is no clear scientific evidence that such exposures actually do cause any health effects. Therefore, any talk about disease risk is pure speculation and has no solid scientific foundation. Studies on animals suggest that only high levels of exposure to oestradiol would be likely to induce adverse effects in infancy and such levels are many thousands of times higher than the minute hormone residues that have been shown to be present in beef from animals treated with oestradiol as a growth promoter.

Based on the precautionary principle, it can still be argued that because consumption of hormone residues in hormone-treated meat is an unnecessary additional exposure, it is unacceptable. This is not unreasonable (and would be my own personal standpoint), but it is not a position that is based on scientific evidence, rather it is based on the lack of relevant evidence. It also needs to be recognised that if this position is adopted, it has other implications. For example, in the UK/Europe, pregnant cattle are routinely slaughtered for meat. As levels of oestradiol are enormously high during pregnancy, the levels of oestradiol in meat from such animals is higher than that found as residues in meat from hormone-treated livestock, so should these animals be considered as being hormone-treated?

Let us be clear, the use of hormones for growth promotion purposes are of no benefit to the consumer (except by making the meat marginally cheaper), are of no benefit to the animals that are treated in this way and pose a potential risk to wildlife if excretion of the hormones contaminates pasture or waterways. These are good reasons to oppose the use of hormones in farming livestock: there is no need for opponents of artificial growth promoters to misrepresent the scientific evidence by suggesting that they pose a risk to human health.

Author: Sense About Science

Document type: For The Record

Published: 24 May 2007

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