Berlin: Over 30 per cent of athletes who competed at the 2011 World Championships admitted to having used banned substances in the past, according to a World Anti-Doping Agency-commissioned study released on Tuesday.
The study, conducted by researchers from Germany's University of Tuebingen and Harvard Medical School in 2011, found that more than 30 per cent of world championship participants and over 45 per cent of athletes at the 2011 Pan-Arab Games said they had taken banned drugs.
The researchers asked a total of 2,167 athletes whether they had used banned substances. A combined total of 5,187 athletes competed at those two events.
The 2011 World Championships were held in Daegu, South Korea while Qatar hosted the Pan-Arab Games that year.
A process of indirect questioning was used for the study titled "Doping in Two Elite Athletics Competitions Assessed by Randomized-Response Surveys" in order to guard the athletes' anonymity.
More than 90 per cent of athletes asked to take part agreed to do so.
Only 0.5 per cent of drugs tests in Daegu were positive while the figure was 3.6 per cent at the Pan-Arab Games.
"The study shows that biological tests of blood and urine reveal only a fraction of doping cases," said Harrison Pope, Harvard Medical School professor.
The study's release had been delayed for years as the researchers wrangled with the World Anti-Doping Agency (WADA) and the international association of athletics federations (IAAF) over how it was to be published.