The NFL hopes to start testing players for human growth hormone in the wake of a test that led to the suspension of a British rugby player.
NFL spokesman Greg Aiello said Wednesday that the league had made a proposal to its players in January regarding HGH. Discussions are ongoing, he said.
"Our position is that HGH testing has advanced to the point where we are taking steps to incorporate it into our program," Aiello said. "We have proposed it to the union."
The NFLPA's player development director, Stacy Robinson, said in a statement that the union "has supported research to find a suitable test that will detect sustained HGH use."
"We believe in and collectively bargained for a system that supports the testing of all banned substances," he said.
Said George Atallah, the union's assistant executive director of external affairs, to the Washington Post: "At this point, there's no reason to believe that blood-testing for NFL players will or should be implemented. We should instead focus on preserving the drug-testing policy that we have in place."
The NFL has used preseason blood tests since at least 2006 for cholesterol and tryglycerates. Major League Baseball has had urine testing since 2003 but not blood testing.
The issue of HGH testing has gained renewed interest in the wake of the United Kingdom Anti-Doping authority announcing a two-year ban Monday for rugby player Terry Newton, saying he had tested positive and become the first athlete suspended for using HGH.
The substance is believed by some to hasten healing, but there is still a debate over whether it increases strength.
A blood test for HGH has been in existence since the 2004 Athens Olympics and available in the U.S. since 2008, according to United States Anti-Doping Agency executive director Travis Tygart.
Tygart said the test was available to professional leagues, but only through World Anti-Doping Agency labs.
"It's one that's been well-vetted, well-discussed," he said by telephone from London. "Further research has been done to get it to a point where it's scientifically valid, and we're happy to help any entity that's interested in having an effective test, whether we're involved with their program or not, getting them comfortable with the validity of the science."
While MLB can institute blood tests for players on minor league rosters, it must reach an agreement with the players' association to start blood testing for unionized players on 40-man big league rosters.
"We are well aware of the important news with respect to the HGH blood test in England," Major League Baseball said in a statement. "We are consulting with our experts concerning immediate steps for our minor league drug program and next steps for our major league drug program. The commissioner remains committed to the position that we must act aggressively to deal with the issue of HGH."
Tygart said the window for detecting HGH through the test is three days at the most, making it most useful for out-of-competition testing. According to Weiner, it may be even shorter.
"Even those who vouch for the science behind the test acknowledge that it can detect use only for a day or so prior to collection," he said.
The Associated Press contributed to this report