One of the United States' most promising athletes will likely have to skip the upcoming Tokyo Olympics. Sprinter Sha'Carri Richardson, 21, has tested positive for a "prohibited substance," which disqualifies her performance at the U.S. Olympic Trials, according to media reports. If the story is true, the disqualification would make her ineligible to participate in the Olympic Games. However, one report claims Richardson has been suspended for 30 days due to a marijuana violation -- which would make her miss the 100-meter event, but not the 4x100 meter relay. So far, there's been no official word from neither Richardson nor Olympics officials -- although Richardson has reportedly pulled out of Sunday's Diamond League meeting in Stockholm, where she was scheduled to run 200 meters. On Thursday, the sprinter tweeted just three words: "I am human."