There seems to be a great deal of confusion and deliberate misinformation about certain aspects of the Houlihan case, which are worth clarifying. Many commentators seem uncomfortable with the uncertainty that surrounds her case and, in their zeal to combat doping, have engaged in rumor and unfounded accusations against Houlihan and others, choosing to be certain that she and her associates are wrongdoers. This witch hunting is a moral defect and will not lead to a positive result for anyone in the sport. I have no idea whether Houlihan is a "clean" athlete or not, but what I am certain of after researching her case in depth, is that she is not receiving any kind of due process in this specific case, and if nothing changes, WADA is coming for all of you, either by way of a single questionable test, or through guilt by association. I have spread this post out in three sections to make it more digestible and easier to reply (Burritogate, The Sample, What Does It All Mean).
Part 1: Burritogate
First of all, it is entirely possible a Mexican food truck would be serving the parts of a male pig that are typically high in nandrolone, which does not in any way imply it was wild boar meat imported from Mexico or some other foolish assertion. If you're going to assassinate someone's character, at least spend 3 minutes on Google to determine that a "boar" is simply a male pig, which in no way implies it was wild or rare. It also seems entirely reasonable that someone would prefer to order food from a provider in an outdoor setting at the height of a pandemic rather than from inside a restaurant.
In American factory farming, boars are typically castrated unless they are chosen to be breeders. The reason this is done is because a minority of them (say 15% +/-10) will otherwise produce an unpleasant odor known as "boar taint" that is much more noticeable to some people than others, though it is perfectly safe to eat. Many farmers are turning to the drug Improvest, approved by the FDA in 2011, to immunologically castrate pigs temporarily instead of the traditional surgical method performed at a much younger age. If an immunologically castrated pig is not butchered in a prescribed time window, there is more of a chance it will contain higher levels of nandrolone. But that's only one possible explanation for the hit of nandrolone Shelby ingested in December.
More likely is that the pork was sourced from a small local farmer who didn't bother castrating their male pig (which makes more sense when raising pigs at a small scale), or that it was a cryptorchid pig where the testes are not always visible. For an adventurous read on cryptorchidism in pigs see:
www.minipiginfo.com/complicated-mini-pig-reproductive-disorders.html
In any case, the point is that the consumption of pig offal is quite common and, if you think about it, there will never be any shortage of such parts wherever pigs are butchered. Here's a revealing discussion among small-time growers about whether and how to castrate their pigs, that leaves me with the impression there's lots of uncastrated male pig meat out there.
https://www.homesteadingtoday.com/threads/improvest-vs-castration.433139
To give an idea of the range of nandrolone in various types of pigs and their organs, there is an excellent table on Page 73 of "Analyses for Hormonal Substances in Food Producing Animals".
https://books.google.com/books?id=5nEoDwAAQBAJ&pg=PA73
It shows, for example, a range of nandrolone in the liver of 11 boars that was between 1-63 nanograms per gram, so the level will really depend on the pig that day and which part is ingested. Many people have referenced the 2000 Bizec study in which subjects ate 310 grams of pork, saying that's a huge amount, but understand those 310 grams included regular meat as well as nandrolone-rich liver and kidney. A burrito from Chipotle can weigh more than 650 grams, so it's not implausible Shelby could have gotten a large hit of nandrolone from a virile pig on that unlucky day and it wouldn't necessarily take 300 grams to do it.
Many have noted she ordered a steak burrito and said she should have noticed it was pork right away and asked for a replacement on the spot. Maybe where you live is different, but in my experience, Mexican take-out places are notorious for getting orders mixed up, and it's easy to understand how they might want to push cheaper pork burritos out the door anyway. It's also worth asking all those athletes and foodies out there who claim to avoid pork offal if they actually make it a strict practice to refuse foods like bratwurst, liverwurst and bologna that also contain pork liver and other "trimmings" which could contain nandrolone. Here's a great description of a local Beaverton farm that makes its own sausage and sells it at the Beaverton Farmers Market. I'm sure it's absolutely delicious.