[kijin]

Prion concentration varies greatly from one part of a cow to another, because prions gravitate toward nerve tissue for some reason. The brain is definitely dangerous to eat. So are the eyes, the spinal cord, and parts of the intestines. Muscle tissue on the other hand is said to be much less dangerous. I don't know how much less, though.

Remember that all risks are relative. Just like radiation, there's likely to be a background level of prions in the soil that you can't avoid even if you only eat vegetables. The question is how much prion exposure you can tolerate without having noticeable symptoms within your lifetime.