American sprinter Sha'Carri Richardson fails drug test according to sources

America's fastest woman Sha'Carri Richardson is reported to have failed a drugs test that could see her miss the Tokyo Olympics.

The sprinter is said to have tested positive for cannabis after she won the 100m at the US trials last month, according to sources.

So far there's been no confirmation of the story, but Richardson has tweeted: ''I am human.'' Cannabis was banned by WADA on 1st January this year, and suspension can range from one month to a maximum of four years.