The accusations centre around Alberto Salazar, coach of the Nike Oregon Project (NOP), and his star American runner Galen Rupp. It's alleged that Salazar instructed Rupp to take banned substances including prednisone and testosterone.
The NOP was responsible for an astonishing 1-2 finish in the 10,000 metres at the 2012 Olympic Games, with Britain's Mo Farah winning gold and Rupp taking silver, upsetting the best African runners.
The whistleblowers include former athletes and coaches. Among them, high profile U.S. marathoner Kara Goucher, and Steve Magness, head coach of the University of Houston cross-country team.
Both left the NOP and were known to be at odds with Salazar's training philosophy.
Top Canadian in group
Cam Levins of Black Creek, B.C., trains in Salazar's group alongside both Rupp and Farah. Neither Levins nor Farah have been accused of any wrongdoing.
Athletics Canada is watching the situation closely and has been in close contact with Levins, who just set the Canadian record for the 10,000m on Saturday at the Prefontaine Classic.
"He trains really hard," Peter Eriksson, head coach of Canada's track and field team to CBCSports.ca. "I don't see him being at any risk."
Eriksson said his staff was made aware of the impending BBC report 24 hours before its release, and he knew about the allegations "a month ago," after meeting with Salazar.
The NOP coach told Eriksson that there were a few disgruntled former athletes and coaches with an axe to grind who were starting rumours about improper use of supplements and other substances. But none of it was true, Salazar told Eriksson.
"The rumours have been going around for a while and they are not substantiated," Eriksson said.
Eriksson doesn't believe Levins will be implicated.
"Our athletes are well tested a lot of different times of the year. It's really hard to get away with anything."
Although Levins competes internationally for Canada, he spends most of his time training under Salazar, who isn't affiliated with Athletics Canada.
"I met [Salazar] three or four times," Eriksson said.
"Do I trust him? He has been coaching for a long time, knows what he's doing and works well with a lot of athletes."Suggest a correction