Not sure what point you are trying to make here, and I'm sometimes confused which athlete you are asking about ... Most of the answers to your questions are obvious: Why do we not get hundreds of failed tests from contaminated beef: - Not all beef is contaminated. Risk of contamination varies widely by country. Different countries like China, Mexico, USA, and countries in Europe are subject to widely varying standards for giving hormones to cattle. If the UK leaves Europe, and strikes a agriculture deal with the USA, they will surely experience an influx of the same contaminated meat, combined with relaxed labelling standards that would hinder athletes making informed choices. - Within a country, contamination will vary depending on how the beef is produced -- i.e. organic beef will likely not be contaminated with hormones. - Urine testing will not always catch contaminated beef, due to short windows (days?) and concentration levels too low to be detectable. If odds are so low, why are recent top athletes testing positive? (Don't recall if you asked that question, but it was asked above): - Testing is not uniform. Top athletes are tested more. Most athletes in all countries are not in the OOC testing pool. Even in competition, unless they win medals, most athletes will only be selected for testing at random. - Some testing is getting better. Low levels that were previously undetectable are now detectable in some labs. Is there evidence of steroids causing an AAF? - Yes and no. - One of the factors against Lawson was the expert statement that "There is no evidence that residues of Trenbolone in US meat can lead (and have led to) adverse findings, as confirmed by the expert witness Professor Ayotte;" - However NADOs have warned against beef from Mexico and China: For example, "On February 11, 2019 the ITF published a warning on the risks of ingesting Clenbuterol and Trenbolone when eating beef or liver in Mexico or China ..." and USADA wrote: "USADA, WADA and other anti-doping agencies have issued specific warnings about this problem in China and Mexico." Presumably these warnings are based on evidence. Is there evidence that the beef was contaminated? - I think the answer for all athletes is "no". The standard of proof is a "balance of probability" and "more likely than not". So athletes recently eating beef in Mexico will likely score higher on this balance of probability, without specific evidence that the beef consumed was contaminated. - In the case of Jarrion Lawson, the "tribunal" accepted that it was possible, but that Lawson failed to show that it was "probable". What do you mean by "assumption of innocence"? All athletes from all countries are "assumed innocent" until proven guilty, and then the burden shifts to the athlete. This initial assumption of innocence is a fundamental pillar of justice in countries like the USA and UK. American Jarrion Lawson just had his 4-year ban upheld by CAS for failing to meet the higher burden of "balance of probabilities", notwithstanding the initial assumption of innocence. Other Americans, like Wilson and Claye, met this burden of proof to the satisfaction of USADA. It's hard to speak for other countries/sports in hypotheticals, but I'm sure UKAD offers a similar "assumption of innocence" to UK athletes.