Can a Burrito Actually Make You Fail a Drug Test?

We spoke with anti-doping expert Oliver Catlin about Olympic runner Shelby Houlihan's four-year ban from international competition.
Drew Schwartz
Brooklyn, US
Shelby Houlihan
Photo by Andy Lyons / Getty Images

Earlier this week, America’s leading middle distance runner, Shelby Houlihan, was banned from international competition for four years, leaving her ineligible to compete at the Tokyo Olympics this year and the Paris Olympics in 2024. The reason for her suspension, according to Houlihan: a bad burrito she ate from a food truck.

Back in December, Houlihan tested positive for nandrolone, a performance-enhancing steroid banned by the World Anti-Doping Agency (WADA). When WADA sent her an email letting her know about the positive test, she was shocked, according to a statement she posted to Instagram this week. 


“I had to read it over about ten times and google what it was that I had just tested positive for,” Houlihan wrote. “I had never even heard of nandrolone.”

As Houlihan tells it, she and her team scrambled to figure out how the drug, which is typically used for muscle building, could’ve gotten into her system. Part of that effort involved writing up a “food log” chronicling every meal she’d eaten during the week she was tested. The night before her 6 a.m. drug test, Houlihan claims, she ate a pork burrito from an “authentic Mexican food truck” in Beaverton, Oregon, where she lives.

She then learned that some pork—and particularly offal, which this food truck purportedly serves—can contain nandrolone. Studies show that after eating pork meat or offal, you can test positive for nandrolone at levels deemed illicit by WADA, and WADA itself has acknowledged the possibility.

Houlihan spent the next six months trying to convince WADA they had made an error, and eventually, she appealed the finding to WADA’s Athletics Integrity Unit (AIU), a regulatory body. But on Friday, the AIU upheld her suspension. (Under the WADA code, a single positive nandrolone test is enough to get you banned for four years.) Houlihan still has a shot at getting the ruling overturned by taking her case to a Swiss tribunal, but by the time she could appear before the court, she will have already missed her opportunity to qualify for this year’s Olympics. 


At first blush, Houlihan’s claim might sound far-fetched—but she’s adamant that she’s never taken a performance enhancing substance, and her coaches and colleagues are adamant about that, too. Plus, the research she cites is real, and it does suggest that even a small portion of pork could have caused her to fail her test, especially considering she allegedly ate that burrito just hours before giving WADA a urine sample.

To get a better idea of whether Houlihan’s claim holds up, I called Oliver Catlin, who’s worked in the world of anti-doping and athlete drug testing for nearly two decades. For years, he served as the finance and administrative director of the UCLA Olympic Analytical Laboratory, the world’s largest WADA-accredited drug testing facility. Now, he’s the president of the Banned Substances Control Group, a company that tests and certifies supplements to ensure they’re not contaminated with substances—like, for instance, nandrolone—that could get an athlete barred from competition. 

VICE: Does Houlihan’s explanation for why she failed her drug test make sense?
Oliver Catlin:
The science does suggest that it is possible to test positive for nandrolone after ingesting pork organs. A lot of documents out there consider it improbable, but the science does demonstrate the possibility.


Compounds in this family are endogenous steroids—things that may be produced naturally—that can also be of an exogenous, or foreign, origin. You're dealing with a drug that could be naturally present. And when we deal with naturally present drugs, we have to create a way in the system to distinguish natural presence from actual use of the drug. 

How good is the system at detecting that difference?
The World Anti-Doping Agency is equipped to deal with that, and it's certainly not the first time that they've dealt with nandrolone. Nandrolone has been a banned substance in sport for many, many years. So this has been known for some time, and the system would obviously do anything in its power to try to ensure fairness on behalf of the athlete.

From what you know about nandrolone, would it make sense for a middle distance runner like Houlihan to take it?
For a distance runner, I mean, no. You typically would consider distance runners using endurance drugs more so than you would consider them using something like nandrolone. If you build muscles, it could have some benefits, maybe to improve your kick or something at the end of the race. But it can also detract by putting on additional weight. 

Nandrolone is a very old substance. I can't remember when it was added to the WADA prohibited list, but I mean, we're talking decades. So from the standpoint of drugs that you could use to dope, this would not be a very good choice, simply because it's been around for so long, and we're so good at testing for it. 


How thorough, and how reliable, are the drug tests Olympians undergo?
The collection process requires, in most circumstances, an observed collection, which means somebody goes into the stall with you and literally watches you put the sample into the canister. There are procedures on how you need to maintain those samples while they're being sealed. The athlete has a chance to witness all of that. You sign for it so that you verify the custody of the sample. So there's a pretty evolved system built around sport drug testing—and that's just the collection side of the equation. 

[Testing] instruments are a thousandfold more sensitive today than they were several decades ago. What that's done is drastically extend the detection window for anti-doping folks. Whereas in the old days you may have been able to use a drug and withdraw it in 20 days and be OK, now, you may use that same drug, and you may have to withdraw it 80 or 90 days before [your test]. Maybe it's even more than that. So steroid testing has improved vastly as the technology has improved.

Are these tests infallible, or could Houlihan’s result be a mistake?
The WADA system is excellent at finding the drugs they are targeting today. There is not much chance that they are making a mistake of misidentifying something and matching it to the drug in question. 

Why didn't Houlihan get a chance to take another test, like, a week after the one she failed? 
Well, there's a 24-hour circumstance where this [pork argument] would be relevant. If [a follow-up test] was negative, does that mean that she used a drug before and it's just finally down to a low enough level to where they’re not detecting it? You can't ever repeat that same point in time, is the challenge.


I looked through the WADA code, and there was one part of it that struck me as odd. It said that it's the athlete’s “personal duty” not to ingest any prohibited substances, and that “it is not necessary that intent, fault, negligence or knowing use on the athlete’s part be demonstrated in order to establish an anti-doping rule violation.” Meaning, they could accidentally ingest nandrolone—in a supplement, or in a cheeseburger, or in a pork burrito—and still get in trouble. It doesn't matter whether they intended to take it—all that matters is if it's there. Is that true?
Yes, it is. There have been a number of athletes that have been found positive with meat contamination, water contamination, and other issues, beyond just supplements. More and more pharmaceuticals are being found in drinking water, or in treated wastewater that could be used to irrigate a field. I was doing an investigation and ran into the reality that plants that were irrigated with treated wastewater from Phoenix, Arizona, were picking up a banned substance in sport from the treated wastewater, in measurable quantities. And this was in things like carrots. 


In the anti-doping community, we've kind of been on a ride where we're trying to be able to extend the window of detection, and test at lower and lower sensitivities and thresholds. But at some point you get to a question: How low is too low? And are you now at a point where you're picking up environmental contamination from things irrigated with treated wastewater, or things that get polluted from industrial contaminants? So we definitely have that to contend with. I think the WADA system is aware of it. I believe they are working on a technical document revision for next year that will factor in environmental contamination, and will consider how low is too low for certain drugs.

But as it stands now, it's like: You eat a burrito, or you eat a carrot, and it has one of these substances in it, and you test positive. The fact that you ingested that substance from eating a burrito or a carrot doesn’t matter—you still get punished, and maybe banned from your sport for four years.
That's the nightmare scenario for an athlete. I lived with U.S. Olympic athletes; I see how hard they train; I’ve gotten to know some of them. They worry about it constantly. I heard someone on a presentation I was listening to today worry about eating contaminated meat, or water, and so forth. It goes through their minds all the time. They put their lives into this sport, for the love of the sport. And to have that taken away by something that's totally out of your control—meat or water contamination, or what have you—is soul-crushing.


Let's say that Houlihan is telling the truth: She never took nandrolone, and she accidentally got some in her system from eating this burrito. What would be troubling to you about the fact that she was banned from her sport for four years anyway?
If she's telling the truth about the scenario, I don’t think anybody in anti-doping would want her to be penalized. Anti-doping folks are not in the business to penalize innocent athletes; quite the opposite. And so it is the system's job to try to determine, to the best of its ability, on what side of the equation the athlete falls. 

What are the chances that Houlihan can get this ban reversed? 
Well, I believe she can still appeal the finding, and they would review the same set of facts. There would be different people reviewing it. And who’s to say what the conclusion would be.

But I guess it's sort of a moot point, because by the time that appeal would happen, Houlihan will have already missed the Olympics.

It's so hard to get every element right of anti-doping. And anyone that works in anti-doping knows there's lives, at the end of the day, that are at stake. Entire lives have been dedicated for these purposes, and one single positive drug test can erase that in a second. To the athletes it affects, it's a huge issue. 

My gut says that she seems to be an innocent athlete that has somehow been harmed by the system. But we don't make judgments on our gut. Athletes will give you very convincing stories, even innocent ones. And it's hard to decipher the difference between knowing whether it's a story or a truth. That's why you build your system: so that your system takes the subjectivity out of your story.

This interview has been edited and condensed for length and clarity.

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