Two Clemson University football players will have to sit out the 2019 season after losing an appeal based on failed drug tests.

Sports Illustrated reported on Friday that tight end Braden Galloway and offensive lineman Zach Giella will be ineligible to compete in 2019 after Ostarine, a banned substance, was found in trace amounts in drug tests they were administered in December. The two, along with former defensive lineman Dexter Lawrence, now a member of the NFL’s New York Giants, sat out of Clemson’s College Football Playoff games.

Ostarine is, according to the U.S. Anti-Doping Agency, a trademarked name for a Selective Androgen Receptor Modulator (SARM) that has not been approved for human use or consumption. The agency says that the substance is being studied as a treatment for certain muscle wasting diseases, such as osteoporosis and cancer.

A statement by a representative for Galloway and Giella said that neither player was aware of how the substance made it into their systems — and that those claims were backed up by a polygraph test. The statement also suggests that “Ostarine is a wide-spread contaminant which is placed in other consumer products without identifying it on the label. This can produce a very low concentration of Ostarine upon testing.”

View the full statement below:

For its part, the USADA admits that there are products that contain ostarine, but notes that they are illegal.

The agency’s website says that ostarine can sometimes be marketed as ‘legal steroids,’ and says that some dietary supplement manufacturers may illegally put SARMs into their products, and omit the substance from the label.

Despite the evidence presented by the players at their appeal, including additional tests both before and after their positive results that came back negative for PEDs, both will be unable to compete this season.

Jason Scott is Online Managing Editor of Athletic Business.