Close to a tenth of Olympic athletes are using banned substances, and only one in ten of those are getting caught, warns former World Anti-Doping Agency chief Dick Pound. "People who have prepared in advance" and used drugs before the London Olympics "won't get caught," he tells CNN. "If you get caught you fail two tests—a drug test and an IQ test." Testers are constantly playing catch-up with athletes using new drugs, says Pound, a former vice president of the International Olympic Committee.
"You'd be pretty ambitious to say London 2012 was clean," he says. "There are drugs we don't know about yet so we need to keep finding them and hunting down the distribution networks." The problem, he says, is a lack of commitment from sports organizations. "They say it's too complicated, too expensive, and they're more worried about corruption. It is getting dumbed down." Three athletes have been banned from the London Games so far for failing drug tests, including an Albanian weightlifter and an Uzbek gymnast. (Read more 2012 London Olympics stories.)