Twenty-three Chinese swimmers were given the OK to compete in the Tokyo Olympics in 2021 despite testing positive for trimetazidine, a banned substance used as a heart medication.

However, the World Anti-Doping Agency said the swimmers' tests had come up positive due to "inadvertently being exposed to the substance through contamination," a claim initially brought by the Chinese Doping Agency.

With the Paris Games' opening ceremony later this week, it's the first Olympics since the scandal, and decorated United States swimmer Katie Ledecky is skeptical.

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Katie Ledecky at time trials

Katie Ledecky of the United States after winning the women's 800-meter freestyle final at the 2024 U.S. Olympic Team Swimming Trials at Lucas Oil Stadium June 22, 2024, in Indianapolis. (Al Bello/Getty Images)

"I hope everyone here is going to be competing clean this week. But what really matters also is, were they training clean?" Ledecky said Wednesday. "Hopefully, that's been the case. Hopefully, there's been even testing around the world."

There is an ongoing U.S. investigation of the suspected doping by the Chinese swimmers, drawing the ire of the International Olympic Committee. While awarding the 2034 Winter Olympics to Salt Lake City Wednesday, the IOC pushed Utah officials to do what they can to stop the FBI probe.

"I think everyone's heard what the athletes think. They want transparency. They want further answers to the questions that still remain. At this point, we're here to race. We're going to race whoever's in the lanes next to us. We're not the ones paid to do the testing, so we hope that the people that are follow their own rules. That applies now and into the future."

The WADA said there had been "misleading information" spreading in the news, which led to its response. It said it had been given a tip by the U.S. Anti-Doping Agency as early as 2020 — before this case arose — about allegations of doping cover-ups in China but that USADA never followed up with evidence.

China swim team after winning medal

China celebrates its gold medal during the medal ceremony for the women's 4x200m freestyle relay during the Tokyo 2020 Olympic Summer Games at Tokyo Aquatics Centre.  (Rob Schumacher/USA Today Sports)

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However, the WADA says it "reviewed this case thoroughly" and "concluded that there was no concrete basis to challenge the asserted contamination."

The agency says it "followed all due process and diligently investigated every lead and line of inquiry in this matter."

The 30-member Chinese swim team won six medals in Tokyo, including three golds. Many of the athletes still compete for China and are expected to swim at the Paris Olympics.

China swim team

China's relay team celebrates a victory in the women's 4x200m freestyle relay final during the Tokyo 2020 Olympic Summer Games at Tokyo Aquatics Centre.  (Rob Schumacher/USA Today Sports)

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Ledecky is a seven-time gold medalist who will be competing in her fourth Olympic Games.

The Associated Press contributed to this report.

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