When Marion Jones tested positive for the prohibited performance-enhancing drug EPO at the U.S. track and field championships in June, it seemed anti-doping sleuths finally had the goods on her after years of rumors.
Now the controversial sprinter, who won five medals at the Sydney Olympics, has been exonerated and the credibility of the EPO test is in question because the backup “B” sample contradicted the positive A test, an extremely rare occurrence.
“We’re interested in any case when the ‘A’ and ‘B’ don’t match,” said World Anti-Doping Agency chairman Dick Pound, “both from the perspective of trying to improve the test if there was a technical glitch and understanding how the differences arose.”
Of the more than 500,000 anti-doping tests conducted by 33 WADA-accredited laboratories around the world in the past three years, there were nearly 9,300 positives among the “A” samples. “B” sample tests contradict the “A” sample tests only two to four times a year, according to WADA statistics.
“In the realm of biology and laboratory science, that’s incredibly good statistics,” said Dr. Gary Wadler, an internationally respected anti-doping expert. “If it happens to be a high-profile situation, it captures attention.”
While refusing to address the Jones case directly, anti-doping experts say there are several possible explanations for the “B” sample not matching the “A” sample, though the urine specimen is taken at the same time and then divided into two bottles. The “B” sample is analyzed only if the “A” sample tests positive, in order to protect the athlete from false positives.
It could be that the “A” sample was a false positive, although the laws of probability say it’s just as likely the “B” sample was a false negative.
A second possibility is that the “A” sample is borderline positive and the “B” sample comes back negative even if the results are virtually identical.
“Any test, when you get close to the limit of detection – when there’s so little material that it’s difficult to see – it can be positive on one attempt and negative on another,” said Larry Bowers, senior managing director for technical and information resources at the U.S. Anti-Doping Agency. “The same thing holds for thresholds. If it’s right at the threshold, it becomes a difficult proposition. That’s just due to the normal variability of testing.”
For example, Wadler said, if he tested a patient’s blood sugar five times in a row he wouldn’t get the same number five times. The same goes for testing EPO or other performance-enhancing drugs.
“I’d get them pretty close, but I wouldn’t get them precise,” Wadler said. “If you’re straddling the threshold, you could wind up with that sort of thing.”
Another possibility is that the prohibited substance in the “B” sample might deteriorate or “degrade” following the “A” sample test. Anti-doping agencies strive to run the second test as soon as possible once the “A” sample comes back positive, but the athlete, representatives and other interested parties are legally entitled to be present when the test is run. Coordinating such a gathering can take time.
“Some compounds degrade rapidly, some do not,” Bowers said. “A good example of one that disappears relatively quickly would be marijuana. If you wanted to make a test (result) change from above a threshold to below a threshold, one way you can do that would be to delay the time between the ‘A’ and the ‘B’ (test). The compound just disappears from the urine.”
Jones’ attorney, Howard Jacobs, said he was hard-pressed to explain the discrepancy because he hadn’t seen any documentation from the “B” test and very little from the “A” test.
“From what I heard, it appeared that the ‘A’ was questionable as a positive anyway,” Jacobs said. “It’s not surprising that the ‘B’ comes back negative in that case.”
Legal challenges fail
Jacobs said there are problems with the EPO test because the criteria for analyzing the results – interpreting molecular data from a digital image called an electopherogram – is “overly subjective.”
Jacobs challenged that in a 2004 case involving distance runner Eddy Hellebuyck, but the Court of Arbitration for Sport – the final arbiter of doping disputes – rejected his argument. It suspended Hellebuyck, saying “the validity of the testing procedure has been the subject of a number of studies that have been published in peer-reviewed journals.”
The EPO test was first used at the 2000 Sydney Olympics. Three cross country skiers forfeited medals at the 2002 Salt Lake Olympics after testing positive.
“Scientists from around the world confirmed the reliability of the urine-based EPO test,” said Travis Tygart, general counsel for the U.S. Anti-Doping Agency. “It’s also been vigorously challenged by some of the world’s top defense counsels and has withstood challenge before the Court of Arbitration for Sport.”
Bernard Lagat, a distance runner, gave a positive “A” sample for EPO in 2003 that was contradicted by the “B” sample. Lagat sued WADA and the international track federation in a German court, seeking 500,000 Euros ($636,000) in compensation and an injunction against the test being performed. The court ruled against him last week.
EPO is a naturally occurring hormone that regulates red blood cell production. The administration of synthetic EPO boosts endurance by increasing the ratio of oxygen-carrying red cells in the blood.
EPO helps sprinters
Some wondered why a sprinter such as Jones would seek to enhance her aerobic capacity, but disgraced sprinter Kelli White said she found EPO greatly enhanced her recovery times during training. White, who pleaded guilty in 2004 to using several illegal substances including EPO as a result of the BALCO scandal, won the 100 and 200 meters at the 2003 world championships when Jones was taking a year off to have a baby.
Jones repeatedly has insisted she never has used performance-enhancing drugs although her name also surfaced in the BALCO case.
“She was consistent with that in this case, that she had not taken EPO, ever,” Jacobs said. “I think at a certain point, people have to accept that and stop harassing her.”
Even the outspoken Pound said it was appropriate to clear Jones.
“We’d rather let some who may be guilty go free than sanction somebody who shouldn’t be sanctioned,” he said.
Others worry about the damage the case may have done to the credibility of anti-doping enforcement. Wadler said he is certain athletes have become more reluctant to cheat since the formation of WADA and USADA in 2000.
“We cannot allow the enormous progress of the last six years to be undermined by sensationalism,” Wadler said. “There is too much at stake.”
Staff writer John Meyer can be reached at 303-954-1616 or jmeyer@denverpost.com.
