Nieuws - 8 december 2005

Hair betrays hormone use

Researchers at Rikilt have developed a method that enables forbidden hormones to be detected in the hair of cattle. The new technique helps hormone-hunters to get round a problem. If the researchers find the hormones in the hairs they can say with one hundred percent certainty that these have not been manufactured by the animal itself.

‘The hormones that we looked at are natural hormones,’ says Dr Michel Nielen from Rikilt. ‘Boldenone and testosterone, both powerful androgens found in commercial preparations, are also manufactured by cattle themselves. If you test the animals’ urine you find conversion products from the hormones, whether they have been given synthetic hormones or not.’

The use of testosterone, boldenone and other growth-promoting hormones is forbidden in the EU. Scientists fear that consumption of hormone-treated meat may have adverse health effects in the long term. Beef farmers, however, couldn’t care less about the law. Because they can earn more per cow if they use forbidden substances, a black market for hormone products has arisen. The ministry of agriculture tries to keep the matter under control by carrying out checks.

‘In the world of sport, doping police set certain limits when testing urine samples to determine whether athletes have used forbidden substances,’ explains Nielen. ‘If a metabolite is found in quantities over the limit, then the athlete has used doping. We can’t do that with cattle, because the natural fluctuation in hormone levels is too large.’

Nielen has solved that problem by not using urine from cattle but hair. Nielen and his colleagues will publish their findings in the Journal of Chromatography B, Analytical Technologies in the Biomedical and Life Sciences. The new technique makes use of the fact that manufacturers manipulate naturally occurring hormones.

‘In commercial preparations containing natural hormones, the hormones have been esterised,’ explains Nielen. ‘The hormones are attached to a fatty acid so that they circulate for longer in the body. In the body, enzymes remove the fatty acid from the hormone.’ This happens so quickly that the esters do not show up in the urine. But those particular enzymes are not active in the hairs, so synthetic hormone esters are stored there unchanged.

Because esterised versions of testosterone and boldenone do not occur naturally, the scientists’ discovery makes it possible to provide conclusive evidence that an animal has been given forbidden substances. The method is also sensitive. Nielen and his colleagues at Rikilt and the University of Gent in Belgium found intact esterised testosterone and boldenone in the hairs of cattle that had been given one single injection of illegal growth hormones two weeks earlier. / WK