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The World Anti-Doping Agency takes another look at 'the risks of contaminants' appearing in food and medicine.

Many thoughts flash through your mind when you ponder whether to risk buying a food truck burrito. Is the truck clean? Is the meat cooked? Will I be able to successfully digest it? One thought that probably wouldn't occur, however, is: Could this burrito cost me the Olympics?

This is the case for American runner Shelby Houlihan, whose chances of making the Tokyo 2020 Olympics were squashed on June 11, when the Court of Arbitration banned her from the sport for four years after she tested positive for an anabolic steroid called nandrolone.

Houlihan, who holds US records for the 1,500 and 5,000 metres and made the final of the 5000 metres event in Rio in 2016, alleges that she ingested the substance through a pork burrito containing pig offal, that she purchased from an authentic Mexican food truck near her house in Oregon.

"It has long been understood by WADA [World Anti-Doping Agency] that eating pork can lead to a false positive for nandrolone," Houlihan said, in a Zoom press conference on June 14. "Although my levels were consistent with those of subjects in studies who were tested 10 hours after eating this source, and WADA technical guidelines require the lab to consider it when analysing nandrolone, the lab never accounted for this possibility."

A spokesperson for WADA declined to comment on Houlihan's case.

'I feel completely devastated, lost, broken, angry, confused and betrayed by the very sport that I've loved and poured myself into.'

Houlihan is one in a long line of elite athletes who have had their tests come back positive due to trace amounts of banned substances which they claim were due to contaminated sources.

American long jumper Jarrion Lawson, who placed fourth in the Rio 2016 Summer Olympics, was banned for four years after testing positive for a metabolite of trenbolone, a synthetic anabolic steroid, that he consumed in a bowl of Japanese teriyaki beef. Two years after the positive test, he was finally exonerated of the doping offence, after providing proof of a receipt to a restaurant whose beef supplier did in fact use the substance in their cattle production.

American track and field athlete Brenda Martinez, tested positive for hydrochlorothiazide in 2020 after taking a WADA-approved anti-depressant medication that was contaminated with a diuretic. After testing of the medication proved her claims, she faced no further suspension.

Though both of these athletes were found to be innocent, their positive test results were still made public, as WADA requires all violations to be announced regardless of whether or not the athlete is deemed at fault.

Tracey Holmes, host of "The Ticket" podcast, and a sports reporter for the ABC, says this is one of the issues with sport. "What we see is that people who have been caught for doping, sometimes they're caught for the most minuscule amounts of things that cannot be performance enhancing at all. But the testing system is so good that you can have infected … whatever. I can consume something today and I will test positive this afternoon, and their lives have been ruined."

"Once you're called a drug cheat, you are always a drug cheat. It is very, very difficult to come back from and people don't want to touch you," Holmes said. "You become toxic."

In 2019, WADA set up The Working Group to "assess the risks of contaminants" appearing in food and medicine. On May 21 this year they announced that they had approved Minimum Reporting Levels for diuretics and growth promoters, to deal with "contamination with substances included in WADA's Prohibited List, particularly as it refers to meat and medication".

"Inadvertent doping due to the contamination of meat or medication is a very complex issue, especially in light of the ever-growing levels of sensitivity achieved in the detection of prohibited substances by WADA-accredited laboratories," Dr Olivier Rabin, WADA Senior Executive Director for Science and International Partnership, said in a statement.

Houlihan and her team remain determined to clear her name, forging ahead with an appeal to the Swiss Federal Tribunal, but with the often-short length of an athlete's career, the damage may have already been done.

"I feel completely devastated, lost, broken, angry, confused and betrayed by the very sport that I've loved and poured myself into," said Houlihan. "I am told that appeals of this kind are difficult to win, but I continue to believe that the truth will prevail."

One thing is certain, with the sensitivity of tests continuing to increase, there will be a lot of elite athletes thinking twice before ordering a pork burrito from their local food truck.

Read more of Newsworthy's Tokyo 2020 series focussing on the challenges – physical, psychological, financial and social – athletes must overcome to compete with the best of the best.