The UFC’s drug-testing partner USADA has handed out four six-month suspensions after four fighters tested positive for ostarine.

Former flyweight champion Nicco Montano, Sean O’Malley, Marvin Vettori and former UFC fighter Augusto Mendes all tested positive for trace amounts of ostarine which the agency says is ‘consistent with supplement contamination’.

“The trace amounts of ostarine found in each of the athlete’s samples was made possible by sensitive laboratory detection capabilities,” USADA said in a press release on Monday. “However, as detection windows increase and the potential time between ingestion and detection lengthens, it has become more difficult for athletes to identify a contaminated product that may be the source of their positive test. As a consequence, the investigation period in ostarine cases is frequently relatively long, as has been the case in each of the cases announced today.”

O’Malley (tests taken from September 5 and December 8, 2018), Vettori (August 24, 2018) and Mendes (March 7, 2018) are now all eligible for competition due to their retroactive suspensions but Montano (October 25, 2018) is still suspended.

Ostarine, which is a selective androgen receptor modulator (SARM), holds performance-enhancing properties and carries a suspension length of two years from USADA if intentional use is found. Ostarine is also currently illegal in the USA but is commonly found as a contaminant in dietary supplements.