The laboratory that tested Marion Jones' A and B samples is expected to report to the World Anti-Doping Agency within two weeks on why the results did not match.
``The laboratory concerned will conduct a discovery analysis to know why this occurred,'' WADA director general David Howman said Saturday. ``In any case where the B sample does not match the A sample, we ask the laboratory for a full report. The lab and the technician involved give a total analysis of why.''
Howman, speaking at a three-day anti-doping symposium organized by the International Association of Athletics Federations, told The Associated Press there were possible reasons why the A and B samples had not matched.
He said the sample may have deteriorated or the banned substance may have faded from the sample between the time it were tested.
``With EPO there is micro-dosing and the substance only stays in the system a certain time,'' said Howman, who added that there is reason to believe new types of EPO have been developed that disappear from the urine more quickly.
Howman also raised the possibility of sample manipulation.
``Powders can be slipped into the sample, powders that can have a corrosive effect over time,'' Howman said. ``You have to remember that there is more testing nowadays, and also cheaters are finding new ways to ensure the B sample does not match the A sample.''
Jones tested positive for EPO on June 23 at the U.S. track and field championships in Indianapolis, where she won the 100 metres for a 14th national title. She immediately requested a B sample be tested, which was negative.
``That's why there is a B sample,'' Howman said. ``She's been exonerated. You can't revisit the case.''
The tests were conducted at a UCLA laboratory that routinely examines samples for the U.S. Anti-Doping Agency.
WADA recently considered eliminating the testing of B samples. This would have meant that athletes would be considered guilty and sanctioned following a single positive test.
``A B sample which does not confirm the A sample is a very rare occurrence,'' said Arne Ljungqvist, chairman of the International Olympic Committee's medical commission, member of WADA's executive committee and an IAAF senior vice-president.
``I can tell you some time ago we were on the verge of doing away with the B sample. There was a strong argument that the B sample always confirmed the A sample and was an unnecessary burden. But this is not the right time to do away with the B sample right now.''
