Written by Gloria Tsang R.D.

Healthcastle.com recently received numerous questions regarding the safety of wild salmon and farm raised salmon and PCBs. On one hand, the American Heart Association recommends eating fish/salmon and their products to prevent heart disease.  On the other hand, recent media reported that some fish and farm raised salmon contain toxic substances. We will discuss a few major reports and some background information about farm raised salmon and PCBs so that you can make a sound decision.

What are PCBs?

Polychlorinated biphenyls PCBs are mixtures of up to 209 individual chlorinated compounds (known as congeners). There are no known natural sources of PCBs. PCBs are either oily liquids or solids that are colorless to light yellow. PCBs have been used as coolants and lubricants in transformers, capacitors, and other electrical equipment because they don't burn easily and are good insulators. The manufacture of PCBs was stopped in the U.S. in 1977 because of evidence they build up in the environment and can cause harmful health effects. However, PCBs persist in the environment. Fish absorb PCBs from contaminated sediments and from their food.

Farm Raised Salmon vs Farm Raised Salmon

  • David Suzuki Foundation: In January 2001, BBC News produced a program "Warnings from the Wild, The Price of Salmon". The program cited a pilot study conducted by Dr Easton with David Suzuki Foundation. The study found that farm raised salmon and the feed they were fed appeared to have a much higher level of contamination with respect to PCBs, organo-chlorine pesticides and polybrominated diphenyl ethers than did wild salmon. It concluded that it seems that contamination in farm fish comes from the feed.
  • EWG Report: In July 2003, the Environmental Working Group EWG released a report stating that farm raised salmon purchased in the United States contain the highest level of PCBs in the food supply system. In the report, EWG reported that farm raised salmon have 16 times PCBs found in wild salmon, 4 times the levels in beef, and 3.4 times the levels in other seafood. EWG recommends that consumers choose wild salmon instead of farm raised salmon, and they should eat an 8 oz serving of farm raised salmon no more than once a month.
  • Science Journal: In January 2004, the journal Science warned that farm raised salmon contain 10 times more toxins (PCBs, dioxin, etc.) than wild salmon. The study recommends that farm raised salmon should be eaten once a month, perhaps every two months as they pose cancer risks to the human beings.

Why do Farm Raised Salmon contain more PCBs than Wild Salmon?

  • Fishmeal/Feed: Studies found that the fishmeal fed to farm raised salmon is highly contaminated with PCBs
  • Farm Raised salmon are "fatter": farm raised salmon are generally bigger in size and contain more fat than wild salmon. PCBs are stored in fat and remain there for an extended period of time, therefore farm raised salmon contain more PCBs.

Government Guidelines?

The average level of PCBs in salmon is 0.027 ppm (parts per million)

  • FDA: The current FDA limit of PCBs in all fish is 2 ppm
  • Health Canada: The current Health Canada's guideline for PCBs in fish is 2 ppm.
  • EPA: The Environmental Protection Agency guideline on PCBs is much stricter. They recommend that fish with PCBs level between 0.024 to 0.048 ppm should be eaten 8 oz a month.

What does this mean? There is an obvious discrepancy in the limit set by various health agencies. Dr Mark Woodin of Tufts University noted that even if the strict EPA guidelines were known to be the right ones, they are based on the amount of PCBs that are thought to be capable of causing one additional cancer case in 100,000 people over a 70-year lifetime.


Key Message: So don't give up fish and salmon completely. It is a known fact that fish and salmon offer benefits in heart health. The benefits to heart health may outweigh the risk of getting cancer from eating farmed salmon. Choose a variety of fish and include them in a healthy well-balanced diet and practice the following:

  • Trim the skin and the visible fat as PCBs are store in the fat portion
  • Prepare your salmon to reduce a significant portion of fat such as grilling and broiling
  • Try canned salmon as almost all of them are wild salmon