Vomitoxin
Animals that eat grain that has vomitoxin in it can have the vomitoxin stay in their bodies.  Chickens fed vomitoxin lay eggs with vomitoxin in them.  Pigs fed vomitoxin have meat with vomitoxin in it.  Cows fed vomitoxin give milk with vomitoxin in it.  However, there is usually less vomitoxin in the animal product than in the grain that the animal ate.