LONDON -- A new test that can detect the use of human growth hormone for up to 21 days has been endorsed by international anti-doping officials, moving a step closer to a potential breakthrough against doping at next year's London Olympics.
U.S. Anti-Doping Agency CEO Travis Tygart told The Associated Press on Monday the "biomarker" test for HGH won strong consensus among doping scientists and experts from around the world who attended a London symposium on detecting growth factors.
The test, which still needs final validation by the World Anti-Doping Agency, widely extends the detection window from the current "isoform" test, which can only identify HGH use going back 12 to 72 hours.
The new test, which also uses blood samples, can go back "anywhere from 10 days to 21 days" and could be a significant deterrent against one of the most potent performance-enhancers in sports, Tygart said.
"This is an important step," he said. "We're hopeful it's going to be approved by WADA soon."
In addition to its possible use at the Olympics or in international sports, the test would also be valid for the NFL, whose players' union has yet to agree to introduction of any HGH testing.
The biomarker test was the main focus of a closed-door conference over the weekend that was jointly organized by USADA and UK Anti-Doping.
"The consensus ... is that this test is a well-validated, scientifically reliable test which extends the window of detection and would also be important to implement," Tygart told the AP following a separate anti-doping and ethics symposium Monday in London.
He said the biomarker test had been supported by more than 30 peer-reviewed scientific articles.
The isoform test, first used in 2004, is designed to detect the presence of synthetic HGH in the body. By contrast, the biomarker test scans for chemicals produced by the body after HGH use, detecting "the effects of using human growth hormone," Tygart said.
The biomarker test could be used alone or together with the isoform test.
"The two tests are complementary," Tygart said.
WADA has to go through its own scientific validation process before the new test can go into effect.
"I would hope it's imminent," Tygart said. "Clean athletes, once they're satisfied that it's scientifically validated and should be used, they want it out there immediately."
Olivier Niggli, legal director of WADA, said the agency would assess the new test fully before giving it the go-ahead.
"Scientists are always very optimistic," he told the AP. "We'll see where exactly where we are. We'll see whether every aspect is covered. Before anything comes into place, we want to make sure we have the answers to the questions we'll get when we go try (the test) for the first time.
"It's very promising. There's still a bit of work to be done but we're getting there."
Niggli was coy about whether the new test would be in place at London's 2012 Games, which start in July.
"If it would be, I wouldn't tell you," he said. "We want to keep the element of surprise."
While HGH testing has taken place at the Olympics since 2004, no positive tests for the hormone have ever been recorded at the Games. Outside of the Olympics, there have been eight positive tests for HGH in seven sports detected at seven different labs.
In the most recent case, two-time Olympic cross-country skiing champion Andrus Veerpalu of Estonia was banned for three years by the sport's governing body in August. The federation said he tested positive for HGH in Estonia in January while preparing for the world championships.
Tygart and Niggli both defended the isoform test against questions raised by the NFL Players Association. The NFL would be the first major professional sports league to implement HGH testing.
Blood testing for HGH was part of the collective bargaining deal struck between the league and players this summer -- but only if the union agreed to the methods. The union has asked for more information about the process and questioned the safety and reliability of the test.
"There is complete consensus that it's a good test, is scientifically reliable, has been well validated and should be used by any entity, professional or Olympic, that wants to protect clean athletes," Tygart said.
Niggli added: "This is a test which was done over many, many years. We've got a lot of studies behind it. We're very comfortable to defend it."