Plasticizer Complicates Sports Doping Tests

Last week, Alberto Contador, a three-time Tour de France champion from Spain, was found guilty of doping after he tested positive in 2010 for a performance-enhancing drug called clenbuterol. What complicates the case is that a phthalate plasticizer also was found in his system. The plasticizer is found in IV blood bags and invited allegations that Contador had an illegal blood transfusion known as blood doping. Contador is now banned from racing for two years.

Brett Israel reports for Environmental Health News that “The World Anti-Doping Agency (WADA) funded research to develop a plasticizer test that would catch cheating cyclists, but so far it’s not the smoking gun that many have hoped for.”

Sports doping used to be pretty simple: If athletes took performance-enhancing drugs, those drugs could usually be found with blood or urine tests. Now, athletes are tested for banned substances, illegal medical procedures, and trace evidence of blood doping, such as the phthalate plasticizer. (Theoretically, blood doping boosts red blood cell count to bring more oxygen to lungs and muscles.)

Israel reports:

Some experts — and Contador — say that these chemical residues are widespread so there is a lot of doubt about how they got into an athlete’s body. But others say that spikes of these chemicals, at levels much higher than normal, are a red flag for doping. Due to the controversy, funding for the test to detect these chemicals was discontinued in November 2011.

Israel writes that Contador plans to appeal the ruling because “widespread use of plasticizers in the environment has clouded the testing efforts of the sport’s doping police.”

The plasticizer under scrutiny related to doping is called bis(2-ethylhexyl)phthalate, or DEHP. The class of chemicals can “mimic estrogen or disrupt testosterone,” Israel writes.

How ubiquitous is DEHP? Israel spoke with Shanna Swan, a reproductive epidemiologist at the Mount Sinai School of Medicine in New York, who has studied the effects of phthalates on infant boys. She said that “ninety-eight percent of people in the U.S.A. have measurable levels.”

DEHP is found in numerous sources — from IV blood bags to food. Joe Braun, an epidemiologist at Harvard University, told Israel that the largest source of DEHP exposure is food, which leaches from some plastic food wraps and containers.

Contador claimed that he ate tainted steaks. Israel explains:

Contador claims that the clenbuterol got into his system when he ate tainted steaks. The WADA and the International Cycling Union said that the drug most likely came from an illegal blood transfusion, because the plasticizer spike was detected the day before he tested positive for clenbuterol. The Court of Arbitration for Sport in Lausanne, Switzerland, agreed, overturning an earlier ruling by the Spanish cycling federation.

According to scientists, “the tainted steaks theory could not be easily dismissed,” however, “research has linked blood transfusions to spikes in DEHP,” Israel writes.

Contador maintains his innocence. Israel writes, “Contador’s argument, as summarized in the ruling, is that ‘the transfusion theory is scientifically impossible’ and that ‘a spike of phthalates can be attributed to any number of legitimate reasons.’”