The World Anti-Doping Agency (Wada) is considering an appeal to the Court of Arbitration for Sport (Cas) after American sprinter Erriyon Knighton avoided a ban for taking a banned substance.

Knighton, 20, tested positive for trenbolone – a banned substance used for muscle growth – in March.

An independent arbitrator ruled on 19 June that Knighton more than likely digested the substance by consuming contaminated meat.

The decision cleared the 200m sprinter to compete in the United States’ Olympic trials, which start in Friday in Oregon.

But Wada says it will await a breakdown of the decision before deciding whether to launch an appeal.

“Once Wada has the full reasoned decision, it will study that, along with the case file, with its usual scepticism and diligence,” a Wada spokesperson told BBC Sport.

They added it would be “extremely rare” to test positive for trenbolone by consuming contaminated meat.

Trenbolone is a known livestock growth promoter that is used legally in beef cattle produced in, and exported to, the United States.

Usada (United States Anti-Doping Agency) chief executive, Travis Tygart said “justice” had been served following Knighton’s clearance.