Ask someone to name a poison and arsenic will be one of the first things to come to mind. Oddly enough, it is fed to chickens because it makes their blood vessels appear pinker and, therefore, fresher. On top of this, arsenic-laced chicken manure is commonly used to feed cows, spreading the substance to their meat as well.
Found in: Poultry and manure fed cows
Health Hazards: Cancer
Banned in: European Union