Salmon steaks are great sources of heart-healthy omega-3 fatty acids. But according to the Environmental Working Group (EWG), salmon can also contain dangerous doses of cancer-causing polychlorinated biphenyls (PCBs), especially if the fish comes from your local grocery store.
EWG found that store-bought salmon, most of which is farmed, contained 16 times the PCB levels of salmon caught in the wild. The Environmental Protection Agency considers these levels a health hazard, and if they were found in wild salmon would recommend eating the fish no more than once a month. The Food and Drug Administration, the agency responsible for fish sold in stores, says these PCB levels are safe for now. But it is investigating the primary source of the contaminant: the ground fish meal that farmed salmon eat.