August 06, 2006

Landis' Goose Is Cooked

It looks like Floyd Landis will soon be Tour de France champion no more.

Landis' B sample confirmed a very high ratio (11/1) of testosterone to epitestosterone. Furthermore, both his A and B samples were subjected to carbon isotope ratio testing, and came back positive for the presence of exogenous (synthetic) testosterone in the urine.

The carbon isotope ratio test is quite definitive. The New York Times ran a nice description of the test last week, when rumours leaked out that Landis' A sample had been positive. The test measures the ratios of two different naturally occurring isotopes of carbon in urinary testosterone. 13C and 12C are chemically identical, but can be distinguished by their mass, for example, in a mass spectrometer. Since bodies get their carbon supply from food, the actual ratio of 13C to 12C in the body is slightly influenced by diet. However, it should be the same for any chemical that the body produces. The test procedure controls for this effect by using some other hormone in the urine as a reference:

The test determines whether the testosterone in the athlete's urine has less carbon-13 than another naturally occurring hormone in the urine, like cholesterol. The test is considered positive when the carbon isotope ratio — the amount of carbon-13 compared to carbon-12 — is three or more units higher in the athlete's testosterone than it is in the comparison hormone. It is evidence that the testosterone in the urine was not made by the athlete's body.

Landis' slim hopes will now rest on the defense that either his body was tampered with (somebody slipped him a dose of testosterone without his knowledge, a.k.a. the Trevor Graham defense), or his sample was tampered with. From my own experience, I can tell you that there are a number of safeguards in place to prevent tampering between the collection point and the laboratory. After that, I can't say very much.

Of course, it is always possible that somebody at the lab intentionally or inadvertently contaminated Landis' sample. Conspiracy theories will continue to thrive, I am sure. It is also possible that the isotope ratio test result is simply a statistical false positive — it would be foolish to claim that any detection tool has a false positive rate equal to zero. The long and the short of it, though, is that Landis has failed the tests under the rules that the UCI plays by, and he will be unable to prove contamination unless he finds somebody who wants to confess. This isn't like an American-style court of law, where Landis only has to raise a reasonable doubt. The burden of proof in this defense is very high, indeed almost impossible to meet.

The doping case against Floyd Landis has been an opportunity to learn more, and write more, about the anti-doping procedures that WADA and its labs use for detecting testosterone. A few weeks ago, before the Landis and Gatlin positives, I looked at the testing statistics for 2005 and decided that the current testosterone test has a significant false positive problem. I have learned a bit more about the issue by following Landis' case. I still believe that most of the "positives" for testosterone in those statistics are false alarms; however, I now understand that most of those cases do not result in doping sanctions, which mitigates somewhat my concern about the test threshold. I'm going to look at the WADA numbers again, as well as some references that other bloggers turned up because of the Landis case, and see if I can refine my conclusions.

I still think that the media, in general, did a poor job reporting the facts of this story. Unfortunately, most of the off-the-cuff conclusions that the press jumped to have turned out to be correct! There are unlikely to be any lessons learned on that front.

Furthermore, I still am not comfortable with the way Landis' case has been handled by the UCI or by Landis' team (Phonak). As I wrote back here, Landis was being tried in the press before due process had been completed; before the results of the isotope ratio test had been provided to him (and perhaps before it had even been performed), and before the B sample results had been confirmed. As Landis himself has pointed out, Justin Gatlin's case was handled using a very different set of rules. And even though the process eventually confirmed Landis' guilt, that doesn't excuse what happened.

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