therefore recognized as the new record holder. Johnson was not the only participant whose success was questioned: Lewis had tested positive at the Olympic Trials for pseudoephedrine, ephedrine and phenylpropanolamine. Lewis defended himself, claiming that he had accidentally consumed the banned substances. After the supplements that he had taken were analyzed to prove his claims, the USOC accepted his claim of inadvertent use, since a dietary supplement he ingested was found to contain "Ma huang", the Chinese name for Ephedra (ephedrine is known to help weight loss). Fellow Santa Monica Track Club teammates Joe DeLoach and Floyd Heard were also found to have the same banned stimulants in their systems, and were cleared to compete for the same reason. The highest level of the stimulants Lewis recorded was 6 ppm, which was regarded as a positive test in 1988 but is now regarded as negative test. The acceptable level has been raised to ten parts per million for ephedrine and twenty-five parts per million for other substances. According to the IOC rules at the time, positive tests with levels lower than 10 ppm were cause of further investigation but not immediate ban. Neal Benowitz, a professor of medicine at UC San Francisco who is an expert on ephedrine and other stimulants, agreed that "These [levels] are what you'd see from someone taking cold or allergy medicines and are unlikely to have any effect on performance." Following Exum's revelations the IAAF acknowledged that at the 1988 Olympic Trials the USOC indeed followed the correct procedures in dealing with eight positive findings for ephedrine and ephedrine-related compounds in low concentration. Linford Christie of Great Britain was found to have metabolites of pseudoephedrine in his urine after a 200m heat at the same Olympics, but was later cleared of any wrongdoing. Of the top five competitors in the race, only former world record holder and eventual bronze medalist Calvin Smith of the US never failed a drug test during his career. Smith later said: "I should have been the gold medalist." The CBC radio documentary, Rewind, "Ben Johnson: A Hero Disgraced" broadcast on 19 September 2013, for the 25th anniversary of the race, stated 20 athletes tested positive for drugs but were cleared by the IOC at this 1988 Seoul Olympics. An IOC official stated that endocrine profiles done at those games indicated that 80 percent of the track and field athletes tested