The United States Anti-Doping Agency said the athletes in question had sought the requisite approvals to take typically prohibited substances, and that none of the drug positives constituted a violation.
Athletes with particular medical conditions may apply for special permission to take banned substances; the list of such prohibited drugs is updated each year.
The International Tennis Federation confirmed that exceptions were granted for Serena and Venus Williams to take substances included on that list, certifying the organization had approved them.
In each of the situations, the athlete has done everything right in adhering to the global rules for obtaining permission to use a needed medication, said Travis T. Tygart, president of the United States Anti-Doping Agency. Its unthinkable that in the Olympic movement, hackers would illegally obtain confidential medical information in an attempt to smear athletes to make it look as if they have done something wrong.
