PCBs, antibiotics, and other contaminates. PCBs are the persistent cancer – causing chemicals that contaminate the environment and the food supply. Studies have found that PCB concentrations in farm raised salmon on average have almost eight times higher the concentrations than wild salmon. (Getting your Omega- 3s vs. avoiding those PCB’s). The PCBs in farm – raised salmon come from the feed, which is made from smaller fish like herring, anchovies, and sardines. Also farmers use antibiotics to prevent