Since the revelation that 23 elite Chinese swimmers tested positive before the 2021 Olympics for a banned performance-enhancing drug, Chinese and antidoping officials have repeatedly defended their decision not to discipline the athletes by invoking scientific analysis.

The officials said the science — which relied heavily on hastily arranged human trials of the drug in question — backed up their conclusion that the swimmers were unwittingly contaminated, most likely through food served to them at a hotel where they were staying during a meet.

But an examination by The New York Times of the secret human trials conducted by the Chinese during their investigation into the positive tests and interviews with experts suggests the science is not as clear-cut as the officials have claimed.

The results cited by China have never been made public. But The Times obtained a copy of the research and shared it with five doctors and scientists with expertise in research, antidoping efforts and toxicology.

All five said that the research was not nearly as unequivocal as the Chinese made it out to be.

“Their conclusions are not intellectually honest,” said Dr. David Juurlink, the head of the Division of Clinical Pharmacology and Toxicology at the University of Toronto, who reviewed the data. “They make a conclusion that is not backed up by what they found in their study. If you submitted this to a scientific journal worth its salt, that conclusion would be laughed at.”

Faced with scrutiny for its handling of the episode and others like it, the World Anti-Doping Agency has cited China’s science as it has tried to deflect criticism that it looked the other way when confronting a pattern of positive tests among Chinese athletes.