Ten over-the-counter fish oil supplements - of the at least 200 brands estimated to be on the market - were tested by Mateel and found to contain toxins called polychlorinated biphenyls, or PCBs. The levels, not disclosed on labels, varied widely; some were far above what requires a warning label under California's Proposition 65 disclosure rules, which mandate that manufacturers list certain toxins in their products. Among those toxins are PCBs because of their carcinogenic risks as well as their link to reproductive problems. California has set an acceptable risk level for PCBs as carcinogens: a scant 90 billionths of a gram a day (90 nanograms). No acceptable risk level has been set for reproductive effects.

The tests, conducted on manufacturers' recommendations for daily dosages, which vary widely, found that three of the 10 products contained PCB levels above that benchmark for carcinogens. David Roe, an attorney for the environmental plaintiffs, says Mateel tested daily dosages because the results would yield a true measure of daily intake because most consumers follow label recommendations. The lowest level, found in Solgar's Norwegian Cod Liver Oil, was 70 times below the highest, found in Now Foods Salmon Oil. Different dosages could account for some of the variance among the products, but the tests found that concentration levels of PCBs varied as well.

Read the complete story at The San Francisco Chronicle.