Eilish McColgan says there needs to be standardised testing in all countries to catch out drugs cheats in athletics.
The Scottish 5,000m runner says the testing is too “slack” in some countries, and that not enough is being done outside of competitions.
It comes after a Wada report on the anti-doping methods employed at Rio 2016 highlighted “serious failings”.
“If I’m on the start line, am I sure that 99% of athletes are clean? Of course I’m not,” she said.
“The testing procedures from country to country does vary and it’s quite slack in certain places.
“It’s not something to dwell on. I can’t tuck other athletes in at night and tell them to be good.”
The World Anti-Doping Agency said many athletes who had been targeted for testing in Rio “simply could not be found”.
It added that, on some days, “up to 50% of tests were aborted”.
“It’s disappointing,” McColgan told BBC 5 live’s Friday Sports Panel. “I’d love to know the exact reasons the tests weren’t carried out. It’s a bit of a strange one.
“The logistics in general around the Olympic Games weren’t the best. It was nothing compared to what London was. London was very slick.
“The general organisation in Rio was a bit trickier, I suppose. So it’s not a huge surprise to me but it’s a shame that the clean athletes are the ones missing out.”
McColgan, who finished 13th in the women’s 5,000m final after switching from the 3,000m steeplechase earlier this year, was not tested in Rio.
She believes testing at major events is insufficient and more needs to be done throughout the year.
“Testing at the championships is not the be-all and end-all; I don’t think you’re going to catch all the drug cheats there,” said the 25-year-old.
“The majority of people have been working hard and training hard all year, and the people that have been cheating have been cheating hard all year.
“By the time they get to the Games their work has been done and it really needs to filter back to out of competition testing. I think that’s really where you’re going to start catching people.”