Mad Cow Disease, which is a nasty condition where the brain basically turns into a sponge, it can take up to 10 years to show itself, and most die within a year of symptoms. Oh, and there is no cure, I think it's got a 100% fatality rate, or close to it. Apparently the UK was one place that had a really bad outbreak of the disease, which can be contracted through using BO supplements that have been produced using unsafe BO. There are very few that use Argentinian BO, the only safe source other than the US which doesn't produce it that I know of. And what few companies that use it charge more for their supplements, Bountiful Breast is the only one I know of that is supposed to use it and it's expensive. Any BO that costs drastically less probably got theirs from China or some other unsafe source. There's a lot of controversy over Ultra Breasts product, one forum user was told that they use US produced BO, but I've found they claim to use Argentinian, and another person on another forum claims that she found evidence that they get them from China. I guess it's hard to know for sure where anyone gets theirs from for sure, and with it taking up to 10 years for the disease to surface someone can think their using a safe product and end up being dead from it in about a decade. Personally as much as I want larger breasts I just don't think it's worth the risk myself, nothing's worth shortening your life over, not even larger breasts, but that's just my opinion. Here's a few sites for you to check out if you don't already know what it is...
http://www.mad-cow.org/
http://en.wikipedia.org/wiki/Bovine_spongiform_encephalopathy
http://www.cdc.gov/ncidod/dvrd/bse/
http://kidshealth.org/teen/infections/bacterial_viral/mad_cow_disease.html
http://www.emedicinehealth.com/mad_cow_disease_and_variant_creutzfeldt-jakob_dis/article_em.htm
This should give you a good explanation of why the UK doesn't want BO or other products that could be contaminated with the disease. From what I've found before I think the UK had a very nasty outbreak of it once, and I can't blame them for not wanting another one, I know I wouldn't want to go that way. :-X