Thursday, August 5, 1999 Published at 17:12 GMT 18:12 UK
Are drug tests reliable?
Athletes are losing confidence in drug tests
Failing a drug test can devastate an athlete's career but the latest controversy over nandrolone has seriously brought into question the reliability of the tests.
Nandrolone, a close chemical cousin of testosterone, was thought to be in this category up until this year. But a study has since shown that normal people can have a small but significant level in their bodies - 0.6 nanograms per millilitre of urine.
These false positives might be explained in a number of ways. Firstly, the stresses athletes place on their bodies in training and competing could raise the natural levels of banned substances.
"There is some evidence that after an event, an athlete's testosterone goes up," said Dr Wheeler. "Therefore if nandrolone is produced from testosterone, it could be that the nandrolone goes over the detection limit."
"We have to remember that the nandrolone studies used very few individuals and, crucially, not athletes."
"I went out and bought some in a sports shop this morning," said Dr Wheeler. "Therefore, athletes may in all innocence be taking supplements which contain steroids they don't know about but which will result in a positive test."
Furthermore, there is some suggestion that nandrolone can be found in meat injected with steroids, or vitamins. In women, the presence of nandrolone may be due to pregnancy or the use of some contraceptive pills.
Michelle Verroken of UK Sport says: "It is important to try to get to the bottom of this. Are we seeing athletes using supplements they haven't known the outcome of? Or is it due to the change in the way animals are being farmed? Or are we seeing athletes actually using nandrolone as a substance to increase their performance?"
Dr Wheeler says there is definitely a solution. The recent work has shown that naturally-occurring nandrolone breaks down in the body to a number of smaller molecules. The ratio of these break-down products is "profoundly different" in people who have taken nandrolone deliberately.
"But more, larger experiments are required as the study only used 30 normal people," he said. "And most research is lengthy."
The way it breaks down mean nandrolone is actually rather easier to detect than some other banned substances which also occur naturally in the body, such as growth hormones, which boost muscles.
It has been used for many years in endurance sports but a reliable test was only developed in June 1999.
Dr Wheeler sees adapting to change as the key part of drug testing. "The nandrolone tests were correct when they were introduced but they have to be reassessed in the light of new knowledge."