With the cycling world awaiting the verdict of the Spanish cycling federation concerning Alberto Contador's positive test result for clenbuterol, anti-doping scientists are continuing to debate over the best way to separate intentional doping with the substance and innocent meat contamination.
Several recent clenbuterol positives have been based on infinitely small amounts of the drug in the athletes' urine, suggesting a possible contamination with clenbuterol-treated meat. And because there is no threshold for the muscle booster, innocent athletes who did not dope could be unfairly punished.
German table tennis player Dimitrij Ovtcharov, who tested positive for the drug in August 2010, was cleared by his national federation in October because he provided his hair to be tested, further supporting his claim that the positive came from ingested meat.
"Clenbuterol sticks at least 20 times better to dark hair than to blonde," Detlef Thieme, director of Germany's WADA-accredited lab in Kreischa, told AP. After Ovtcharov's hair test was negative, it offered additional evidence that he didn't cheat. Had Ovtcharov been blonde, that result would have been "rather vague," added Thieme, whose lab performed the test.
However, the World Anti-Doping Agency (WADA) has since appealed the acquittal to the Court of Arbitration for Sport (CAS) - a move it is likely to repeat should the Spanish cycling federation decide to clear the 2010 Tour de France winner Contador.
But within the scientific world, anti-doping experts point out that WADA's zero-tolerance policy for clenbuterol should be re-examined. Zhao Jian, deputy director-general of China's Anti-Doping Agency, said that the absence of a threshold for the substance is "not fair" because of a great possibility of punishing innocent athletes.
Still, Zhao warned that dopers could use a threshold to escape punishment, as long as they tested below the limit. "It could give a green light to those who deliberately use," he said.
Germany's Thieme suggested loosening the rules temporarily, while scientists pinpoint the risk of meat contamination with greater certainty. "That would be smart," he said.
At the moment, "in order to protect the integrity of the ongoing proceedings", WADA is not commenting on the scientific investigation of clenbuterol positives, or whether it would be willing to introduce a threshold.
Another rider waiting for the outcome of Contador's case is Li Fuyu, who used to ride for RadioShack but was released after testing positive for clenbuterol in March 2010. Like Contador, the clenbuterol traces found in Li's urine were infinitely small, and the Chinese rider also blamed contaminated meat for the positive.
Officially, Li has been banned for two years by his federation, but if Contador is cleared, the Chinese cycling federation could shorten his supension. "Since his case is the same as that of Contador, he has to wait for the outcome of Contador," said a Chinese cycling official by the surname of Niu. "If Contador is acquitted, it’s possible that an adjustment will be made in (Li's) punishment."
The Spanish cycling federation is expected to provide a sentence on Contador by February 15.