Contamination of meat by heavy metals, veterinary drugs and pesticides is a problem which the U.S. government has for the most part ignored. And while bacterial contaminants can be killed by cooking, chemical residues stay in the meat.
“Sick dairy cows are given medications to help them recover, but if it appears an animal will die, it's often sold to a slaughterhouse as quickly as possible, in time to kill it before it dies.”
Sources:FSIS National Residue Program for Cattle (PDF)
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