PCBs - Is Farmed Salmon safe to eat?
Written by Gloria Tsang, RD
Published in Nov 2004; Updated in Jun 2008
(HealthCastle.com) We've had a lot of questions lately regarding the safety of farmed salmon and PCBs. On one hand, the American Heart Association recommends eating fish and fish products to prevent heart disease. On the other hand, recent media reports claim that some fish and farmed salmon contain toxic substances. We will discuss a few major reports and some background information about farmed 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 banned in the U.S. in 1979 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.
Farmed Salmon have always been under the gun
- 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 the David Suzuki Foundation. The study found that farmed salmon and the feed they were given 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 contamination in farm fish comes seems to from the feed.
- EWG Report: In July 2003, the Environmental Working Group (EWG) released a report stating that farmed salmon purchased in the United States contain the highest level of PCBs in the food supply system. In the report, EWG reported that farmed salmon have 16 times the 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 instead of farmed salmon, and they should eat an 8 oz serving of farmed salmon no more than once a month.
- Science Journal: In January 2004, the journal Science warned that farmed salmon contain 10 times more toxins (PCBs, dioxin, etc.) than wild salmon. The study recommends that farmed salmon should be eaten only once a month, or perhaps only every two months, as they pose cancer risks to the human beings.
Why do Farmed Salmon contain more PCBs than Wild Salmon?
- Fishmeal/Feed: Studies found that the fishmeal fed to farmed salmon is highly contaminated with PCBs
- Farmed salmon are "fatter": Farmed 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, so farmed salmon contain more PCBs.
Are there Government Guidelines on PCBs?
The average level of PCBs in salmon is 0.027 ppm (parts per million)
- FDA: The current Food and Drug Administration limit of PCBs in all fish is 2 ppm
- Health Canada: The current Health Canada guideline for PCBs in fish is 2 ppm.
- EPA: The Environmental Protection Agency guideline on PCBs is much stricter. They recommend that fish with PCB levels between 0.024 to 0.048 ppm should be eaten up to a maximum of 8 oz a month.
What does this means? There is an obvious discrepancy in the limits set by various health agencies. Dr Mark Woodin of Tufts University noted that the strict EPA guidelines 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.
The Bottom Line
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 different kinds of fish and include them in a healthy, well-balanced diet. Also try the following tips:
- Trim the skin and the visible fat from your fish, since PCBs are stored in the fat portion
- Prepare your salmon in a way that reduces a significant portion of fat, such as grilling and broiling
- Try canned salmon, since almost all of them are wild salmon