"People are being exposed to PCBs through these products and they're not being told," said Roe.
When environmental activists tested 10 different fish oil supplements, they found every one contained PCBs.
According to California law, people should not be exposed to more than 90 nanograms of this carcinogen a day. But they claim their results showed three of the 10 contained more than that, including Nature Made Cod Liver Oil, NOW Foods Salmon Oil and Double Strength Cod Liver Oil.
"You can protect yourselves by shopping for the ones with the lowest levels," said Roe.
CVS, Rite Aid, Omega Protein and SOLGAR all declined to comment on the lawsuit. And GNC, NOW Health Group, Twin Lab and Pharmavite, maker of Nature Made, all said their fish oil supplements pass strict tests and comply with all state and federal laws.
But experts caution that before you toss your supplement you should call the toll free number on your favorite brand and get the facts. And perhaps look to state and federal authorities to declare which ones are truly unsafe, as there are many unanswered questions about testing.
"You have to look at the kind of laboratory and who did the work," said Dr. Roger Clemens, USC School of Pharmacy. "Also you would want to check to see if they have a valid EPA methodology that has been certified by the agency, before beginning to examine the data."