The World Anti-Doping Agency (WADA) has set up a review into whether cannabis should remain on its list of banned substances.

The move comes after American sprinter Sha'Carri Richardson missed the Tokyo Olympics due to the ban she received after testing positive for the substance at the US Olympic trials last June, although she later revealed that she had used cannabis following the death of her biological mother.

WADA announced in a statement on Tuesday that it has set up a review into the banned status of cannabis, that will be initiated next year.

"Following receipt of requests from a number of stakeholders, the (executive committee) endorsed the decision of the List Expert Advisory Group to initiate in 2022 a scientific review of the status of cannabis," WADA said in the statement.

"Cannabis is currently prohibited in competition and will continue to be in 2022."

21-year-old Richardson won the 100 metre event at the US trials in June, which were held a week after her biological mother's passing, recording the sixth-fastest women's time in history in the semi-finals.

However after testing positive, the qualification times were expunged and the one-month ban enforced.

After the trials took place in Eugene, Richardson spoke about what had been happening in her life.

"Last week, finding out my biological mother passed away and still choosing to pursue my dreams, still coming out here, still here to make the family that I do still have on this earth proud.

"And the fact [is] nobody knows what I go through. Everybody has struggles and I understand that, but y'all see me on this track and y'all see the poker face I put on, but nobody but them and my coach know what I go through on a day-to-day basis."