The 41-year-old tested positive for the banned diuretic hydrochlorothiazide (HCTZ) after an out-of-competition test on August 24.

During USADA’s investigation into the case, Brown provided USADA with records of a permitted oral prescription medication that he was taking at the time of his positive test. 

The medication did not list HCTZ or any other prohibited substances on the label. 

Detailed laboratory analysis on multiple tablets on the medication found HCTZ contamination at a level consistent with Brown’s positive test, however. 

Brown will subsequently not face a period of ineligibility for his positive test, and because the sample was collected out-of-competition, there are no competitive results to disqualify.

"If an athlete ingests a prohibited substance from a completely innocent source, such as contaminated medication, meat, or water, and there is no effect on performance, there should not be a violation or a public announcement," said USADA chief executive Travis T. Tygart.

"We have now had 26 of these tragic no-fault cases since 2016, and the injustice keeps happening. 

"How many more athletes will suffer and resources will be wasted before we, as a World Anti-Doping Agency (WADA) community, reform the system to be more fair, effective, and efficient?"

Tygart has previously criticised WADA as part of a long-running dispute between the organisations.

Brown was born with a congenital birth defect and had his leg amputated as a result. 

He began competing in Para-triathlon in 2010 and earned a bronze medal at the Para-triathlon World Cup event in Tokyo in August 2019. 

The competition was a test event for the Tokyo 2020 Paralympic Games, which have now been postponed to 2021 due to the COVID-19 pandemic. 

Brown has expressed his ambition of competing for a medal at the Games next year.