A Chinese expert in pharmaceutical analysis has called for further analysis of U.S. swimmers’ samples to sort out controversy over their flushed faces at the Paris Olympic Games. Despite the conclusion of the Paris Olympics, debate continues over the facial discolouration observed in some American swimmers after they competed in Paris.

The expert, who asked not to be named, pointed out that it is crucial to base any suspicions on concrete evidence, reports Xinhua.

“Without proper scientific testing, accusations of drug use by any athletes remain unfounded and lack the necessary rigor from results in laboratory analysis,” said the expert.

One substance that has sparked online speculation is myo-inositol trispyrophosphate (ITPP), which can cause a red or purple complexion after intense physical activity. Although ITPP is not specifically listed in the World Anti-Doping Agency’s (WADA’s) Prohibited List, it fits the definition of prohibited methods (M1.2): Artificially enhancing the uptake, transport or delivery of oxygen.

ITPP could help treat conditions such as heart disease, cancer and Alzheimer’s disease. However, scientific studies have shown that the drug can enhance the maximum exercise capacity in laboratory mice, raising fears that it could be misused by athletes seeking a competitive edge.

“The Paris Olympic laboratory could develop a specific testing method to analyze the athletes’ samples for this substance if it was not initially screened during the Games. Alternatively, the samples can be sent to another WADA-approved doping control laboratory with the capability to further test the suspected substances at IOC or WADA’s discretion,” he said.

It can be found in public scientific literature that, a doping control research group from German Sport University Cologne, he said, had already published a reliable method to detect ITPP in human urine in 2014.

The 2015 World Anti-Doping Code officially incorporated the provision extending the storage period for athletes’ doping test samples to 10 years. Since the Athens 2004 Olympics, the IOC has preserved doping test samples from each edition of the Games, which allows for re-testing of samples whenever new, reliable testing methods are developed to ensure fair competition and maintain public trust in the integrity of the Olympics.