LAUSANNE, Switzerland (AP) — Former Olympic champion swimmer Roland Schoeman has been banned for one year after testing positive for a black market substance considered to be a cancer risk.

The 39-year-old South African tested positive for GW501516 in May, swimming body FINA said in a published ruling.

Schoeman had been in training to qualify for the 2020 Tokyo Olympics. He won three medals — including gold in the 4×100-meter freestyle relay — at the 2004 Athens Olympics. He is also a three-time world champion who set a world record while winning the 50-meter butterfly title in 2005 in Montreal.

FINA’s doping panel imposed a one-year ban that expires on May 17, the governing body said Wednesday.

The substance GW501516 is banned by the World Anti-Doping Agency in the category of “hormones and metabolic modulators.” WADA alerted athletes in 2013 that GW501516 failed medical trials and was a toxic threat to health if used as a performance enhancer.

“(It’s) a developmental drug that was withdrawn from research by the pharmaceutical company and terminated when serious toxicities were discovered in pre-clinical studies,” WADA warned seven years ago.

Schoeman can appeal against the ban at the Court of Arbitration for Sport.

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