MONTREAL • A World Anti-Doping Agency (Wada) report published on Thursday found that "serious logistical failings" affected anti-doping efforts at the Rio de Janeiro Olympics.
The report of the independent observers who were sent to the Games by Wada, by invitation of the International Olympic Committee (IOC), outlines cases of athletes targeted for testing who "simply could not be found".
A lack of adequately-trained anti-doping personnel - including chaperones to take athletes through test procedures - contributed to the inability to meet daily targets for out-of-competition testing in the athletes' village.
"On some days, up to 50 per cent of planned target tests were aborted in this way," the report said.
In total, almost 500 fewer anti-doping tests were carried out at the Games in August than originally planned. Some 5,380 tests were scheduled but just 4,882 took place.
Of the 450 athlete biological passport tests planned, only 47 were carried out.
4,882 of the 5,380 scheduled drug tests took place.
Rate of missed tests on some days.
Problems surfaced at competition venues as well, with chaperones denied access to some areas and therefore unable to accompany athletes throughout a test, while many of the doping control officers were inadequately trained in sample collection and other procedures.
Despite the flaws, commission chair Jonathan Taylor said the anti-doping programme in Rio "was able to achieve a number of positive outcomes in the face of very challenging circumstances".
"Despite staffing issues, resource constraints and other logistical difficulties, those tasked with implementation of the programme, and in particular the volunteers, deserve immense credit for ensuring that the rights of clean athletes were safeguarded," Taylor said.
He also commended the IOC for its use of new techniques, including pre-Games testing and information gathering and the establishment of a new Court of Arbitration division to handle anti-doping cases as a first-instance panel.
The report praised improvements made to Rio's anti-doping laboratory, which was suspended by Wada just six weeks before the Games for failing to meet international standards.
The report said the lab was "superbly equipped, operated very securely and generally very efficiently, and now represents an outstanding legacy from the Games for the anti-doping movement in South America".