The Explainer: Plastics

Now that evidence suggests the metabolites of plasticizers in Alberto Contador's urine samples a reader wants to know if that's proof of doping.

Editor’s note: This Explainer column orignally was published in October.

Dear Explainer,
Another one bites the dust. The clenbuterol positive of Alberto Contador was bad enough, but now the news is that he has traces of plastic in his urine. So your theory last week – that the clenbuterol could be left over from stored blood – might be spot-on.

What now? Isn’t that enough evidence to close the case and boot this guy from the sport? What impact would regular testing for plastics do to help clean up the sport?
Washington, D.C.

Dear Ron,
I’m probably dating myself here, but I couldn’t help but remember that great scene from “The Graduate” when I first heard reports about the additional data regarding Contador’s test results being leaked to the press:

Just one word

Mr. McGuire: I want to say one word to you. Just one word.
Benjamin Braddock: Yes, sir.
Mr. McGuire: Are you listening?
Benjamin Braddock: Yes, I am.
Mr. McGuire: Plastics.
Benjamin Braddock: Just how do you mean that, sir?

I am assuming that back in 1967, Mr. McGuire’s amazingly prescient (and, as I recall, unheeded) career advice didn’t necessarily involve the future of doping in sport, but the news does raise some interesting possibilities. If testing for evidence of doping could also be used to show reliance upon the tools employed by dopers, then we’d all be a step closer to cleaning up the sport, right?

Well, not so fast.

First off, it’s worth noting that the original story, from a German television network reporter, included the caveat that the test was “new” and not yet “certified.” Well, what does that mean? Aberrant results? Readings that can’t be duplicated? Not really.

That other ‘new’ test
It might be helpful to go back and look at the technology involved in another test that sprang onto the scene six years ago. Most of you will recall that in 2004, the World Anti-Doping Agency surprised many by announcing the arrival of a “new” test for homologous blood doping. Unfortunately, for those involved, that announcement was coupled with a pair of positive tests, one of which then led to a long and expensive legal battle mounted by former Phonak rider Tyler Hamilton.

Indeed, much of Hamilton’s defense was based on the assertion that the test, known as “flow cytometry,” was new and, according to his legal team, “unproven.” And when it came to the question of testing for performance-enhancing methods, that was true. But even six years ago, flow cytometry was nowhere near being an infant technology. The first flow cytometry machine was developed in 1953 and the technology had been effectively used by hospitals to sub-type blood groups to ensure greater compatibility with donated blood for about 30 years before it was used for other purposes by WADA. (If you want to review the science behind flow cytometry, Dr. Shannon Sovndal wrote a terrific summary of the method for back in 2004.)

While the method was tried and true, its application to the detection of blood doping required something of a “Eureka!” moment, which came in 2000 when a group of researchers wrote a paper published in the journal Haematologica. That eventually led to the adoption of the “new” test in 2004.

The application of flow cytometry to doping was actually pretty straightforward. It was essentially a “binary” test, meaning there was either a secondary population of blood cells in your system or there was not. If there was a secondary population present, it had to come from somewhere.

And where would that be? Well, there were a few possibilities, including pregnancy, organ transplant, a rare phenomenon known as chimeraism (that’s the “disappearing twin” issue that was bandied about for a while) and blood transfusion. It’s a relatively short list and, in the case of an athlete accused of blood doping, one that can be reviewed quite easily. Pregnant? Not you, sir. Organ transplant? Well, probably not. Disappearing twin? There’s a test for that, too. Blood transfusion? If so, was it medically justified? If not, you’re busted.

Just one word: phthalates
So how does that relate to a test for the presence of plasticizers in human tissue?

Like flow cytometry, gas chromatography and gas chromatography-mass spectrometry, the technologies used to detect the presence of the chemicals used in the production of plastic, are well established. Chromatography was first developed more than a century ago and solid state gas chromatography is more than 60 years old.

The U.S. Environmental Protection Agency has been monitoring the presence of so-called “plasticizers” in human tissue for more than 40 years. Concerns were raised about the possible toxic effects of a family of industrial chemicals known as phthalates back in the 1970s. One of the most commonly used is di(2-ethylhexyl) phthalate, or DEHP.

It is that chemical, DEHP, that has raised eyebrows about Alberto Contador’s samples at the WADA-certified laboratory in Cologne, Germany. In addition to finding trace amounts of clenbuterol, the lab also found “high levels” of DEHP. DEHP is used in the production of medical equipment, such as blood bags and IV tubes. Case closed, right?

Phthalates: Something all of us have in common?

Well, not so fast.

The problem is that DEHP and other phthalates are commonly used in all sorts of things, not just medical devices. DEHP is used as a plasticizer in polyvinyl chloride (PVC). You probably come in contact with PVC dozens, if not hundreds, of times a day. Some of it is plasticized (softened) with phthalates and in other cases it is not. PVC is used in floor tiles, furniture upholstery, packaging material, the plastic film used to wrap meats in the supermarket, toys, water and sewage pipes. The hard versions, like those white water pipes you commonly see, have little or no plasticizer. The softened versions have higher levels.

We even relied on DEHP softened plastics to pacify our young children. In 2009, Congress passed regulations limiting the levels of phthalate plasticizers in children’s toys and other products that can be placed in a child’s mouth. Those limits have been in place in Europe since 1999. Despite the regulations intended to limit direct oral contact with DEHP and other phthalates, its use is widespread and the likelihood of environmental exposure remains fairly high.

While research continues, some suggest that long-term exposure to DEHP and other phthalates, particularly among children, results in endocrine disruption that could lead to changes in hormone levels, including an appearance of some female characteristics in young adolescent males and — some research suggests — a reduction in penis size.

All of those concerns (even that last one), however, are put aside in the case of medical necessity. Because of the injection of fluids, the most significant direct exposure to phthalates can come from medical equipment, including tubing, blood bags and the bags that hold the saline solutions riders may — under limited circumstances — legally use to rehydrate in big stage races.

Not yet verified
Therein lies the rub. It’s not that the test for plasticizers is new. The test is relatively straightforward. The problem that may keep the test from being “certified” quite yet is that there are still discussions as to precisely what levels of DEHP one could “reasonably” expect from environmental exposure versus those that might result from the use of medical devices.

In 1982, the U.S. National Institutes for Health produced a terrific paper that specifically addresses those concerns and the means by which levels of phthalates can be monitored. In their paper, “Toxic Potential of the Plasticizer Di(2-ethylhexyl) Phthalate in the Context of Its Disposition and Metabolism in Primates and Man” (those scientist types are always good for a catchy headline, aren’t they?) Carl C. Peck and Phillip W. Albro specifically address the questions about the toxic potential of DEHP, problems of detection and levels that one might expect from environmental exposure versus the levels of DEHP and its metabolites one might expect to see from medical uses.

Even then, however, the problem of a verifiable doping test isn’t solved. The debate will then be extended to the question of how one might be able to distinguish between levels that might be caused by the inappropriate infusion of blood products versus the currently legal use of those same medical devices (PVC bags and tubing) for rehydration. Even then, there may be a question of potential DEHP contamination of blood and urine samples after they have been submitted, depending on the storage medium used.

The question remains, from whence it came.
The question remains, from whence it came.

So, unlike the “binary” nature of the old flow cytometry test for a secondary population of red blood cells — in which it’s either there or it’s not — the plasticizer question comes down to the far less precise question of ratios.

The placement of the line is more subjective when it comes to measuring ratios. If you have doubts, look back at the old testosterone/epitestosterone standards. In a normal adult male, that level is generally around 1-to-1. In the old days, the ratio would have to exceed 10-to-1 before that triggered further analysis. In recent years, however, that was reduced to a 4-to-1 ratio. (Floyd Landis, by the way, had a T/E ratio of 11-to-1 after that fateful stage 17 ride in the 2006 Tour de France, so he would have tripped the meter under either standard.)

When it comes to DEHP, what is a reasonable level? If level X can be attributed to environmental exposure, where do you draw the line that tells the finders of fact in a doping case that there is strong evidence to suggest a violation?

It’s not that the question can’t be resolved. It’s a debate that may have a sound and very reasonable outcome. It’s just that the debate is probably one that is currently under way.

If there is a resolution, we may well see evidence of DEHP levels presented in a doping case against Alberto Contador. We may see the back-analysis of other riders’ samples in other cases. Indeed, the federal officials in charge of the investigation of alleged past doping practices on the U.S. Postal team have already suggested that might be an avenue they now wish to explore.

Plastics. Apparently there’s a future in that.

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