In a statement released on Wednesday, the MLBPA said it agreed with the Commissioner's Office that "HGH use in baseball is not to be tolerated" but ultimately the union "will not compromise the commitment to fairness on which our Program always has been premised."
The current Major League Baseball Joint Drug Prevention and Treatment Program does not call for HGH testing because "no scientifically validated urine test exists" and "blood testing raises serious issues not associated with urine testing."
The MLBPA, which currently does not allow blood testing for any drug, said it would consider blood testing for HGH if the test is scientifically validated.
The issue of HGH testing has been in the forefront since the United Kingdom Anti-Doping authority announced a two-year ban for rugby player Terry Newton on Monday. Newton became the first athlete suspended for using HGH after failing a blood test.
The statement noted Newton's suspension but also pointed out that it is still the only positive test despite years of testing.
"This development warrants investigation and scrutiny; we already have conferred with our experts on this matter, and with the Commissioner's Office, and we immediately began gathering additional information," the statement read. "However, a report of a single uncontested positive does not scientifically validate a drug test. As press reports have suggested, there remains substantial debate in the testing community about the scientific validity of blood testing for HGH. And, as we understand it, even those who vouch for the scientific validity of this test acknowledge that it can detect use only 18-36 hours prior to collection."
The MLBPA also said it will continue to monitor HGH testing and will work closely with the Commissioner's Office to improve the current testing program.
"We have conferred initially with the Commissioner's Office about this reported positive test, as we do regarding any development in this area," the statement read. "We look forward to continuing to jointly explore all questions associated with this testing -- its scientific validity, its effectiveness in deterring use, its availability and the significant complications associated with blood testing, among others."
Rhett Bollinger is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.