If you’re unnerved by the idea that a typical package of hamburger might contain flesh from hundreds, if not thousands, of cows, you may be surprised to know the oil in your fish oil capsule may be derived from several different species, including sardines, herring, anchovies, tuna, cod, krill (a shrimp-like planktonic crustacean), and even farm-raised salmon. Furthermore, these fish, which get their omega-3 from eating micro-algae, may come from shallow waters near heavily populated shores—where heavy metals, toxins, PCBs, and other pollutants concentrate—not from cold, deep, and relatively unpolluted oceans.The problem grew public last year when a lawsuit was filed in California (which requires labeling of products containing PCBs) against CVS Pharmacy, Inc.; General Nutrition Corp. (GNC); Now Health Group, Inc.; Omega Protein, Inc.; Pharmavite LLC (Nature Made brand); Rite Aid Corp.; Solgar, Inc.; and TwinLab Corp. The suit claimed that some of these brands contain at much as 70 times the level of PCBs as in other brands. Omega-3s are referred to as “essential” fatty acids because the human body is i …