As little as one meal a week of B.C. farmed salmon could pose health hazards, according to a Vancouver geneticist. Michael Easton says he found elevated levels of PCBs in salmon raised in pens along Canada's west coast.

Easton is blaming the feed used to fatten the fish and promote their rapid growth. He says it's laced with PCBs.

, The study was published in February in Chemosphere, an international science journal that specializes in environmental chemistry.

The study one of the first to look at contaminant levels in farmed fish showed that farmed fish contained nearly 10 times the toxic load of some types of PCBs, or polychlorinated biphenyls, as wild salmon.

Easton's study estimates that Canadians should not eat more than one to three meals of farmed salmon a week. He used World Health Organization standards for PCB exposure to come up with that figure. Health Canada's guidelines are far looser. It has concluded that 20 to 138 portions of farmed salmon a week is safe.

Although Easton's study suggested that PCB levels are higher in farmed salmon than in wild salmon, it did find one benefit. The study concluded farmed salmon contained less mercury than wild salmon.