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Writer's pictureChristiana Mouski
Dec 5, 20244 min read

Salmon and PCBs

A few days ago I came across some articles claiming that farmed salmon is the most toxic food on the planet. So let’s investigate this claim

These articles mainly talk about PCBs.


What are PCBs?

PCBs, or polychlorinated biphenyls, are a group of toxic persistent organic pollutants (POPs).

It is estimated that more than 1.3 million tons of pure PCBs were manufactured between 1930 and 1993 in10 countries and were widely exported from, resulting in their use in at least 114 countries. The approximately 1.3 million tons, through dilution for use and subsequent mismanagement, have expanded to 17 million tons of PCB-contaminated materials and waste, with an estimated 20-35% of the PCBs already released into the environment.

Due to their persistence, bioaccumulation potential and toxicity, PCBs pose risks to the environment and our health. They bioaccumulate through the food chain and can reach worrying levels in animals and consequently in humans who will consume them through the food chain.

Fish consumption is a potential source of exposure to PCBs as they have clearly impacted the marine environment. Fish become contaminated with PCBs through contaminated sediments or by consuming contaminated prey. Over time, PCBs accumulate in the fatty tissues of fish and can reach levels thousands of times higher than in water.

In humans, PCBs are readily absorbed and stored in fatty tissue. They are slowly eliminated from the body and may take many years to be completely eliminated after exposure. They can accumulate in the body over time and are stored primarily in fat and the liver. They can also enter the body of infants through breastfeeding.

What are the potential health effects for people who consume PCBs?

  • They can cause neurodevelopmental problems in developing children.

  • At higher concentrations, short-term changes in liver function may occur without obvious symptoms.

  • Animal studies also show that PCBs can affect the immune, endocrine, and reproductive systems.

  • PCBs have been categorized by the International Agency for Research on Cancer (IARC) as “Probably carcinogenic to humans” (Group 2A). Group 2A indicates that there is strong evidence that it may cause cancer in humans, but it is not yet conclusive.

Fortunately, their presence in food and feed has fortunately decreased in recent years due to legislative measures and restrictive strategies by public authorities and industry. However, due to their long half-life and their persistence in nature, their abundance in the environment is still maintained and seafood, especially oily fish, is an important dietary source of them.

Wild VS Farmed Salmon

Two scientific articles from 2017 and 2020 (listed below) agree that farmed salmon, due to its highly controlled diet and new legislation, has lower levels of PCBs than wild salmon. However, both wild and farmed salmon have levels within limits. If we go back to studies from 2000, 2006 and generally older studies, we will notice that the data are very different.

Fatty fish like salmon are rich in beneficial nutrients like omega-3 fatty acids, so the benefits to physical and mental health may outweigh the potential risk of consuming low levels of PCBs.

The 2020 study reports that Concentrations of dioxins, PCBs, mercury and arsenic were three times higher in wild salmon compared to farmed salmon, but all well below EU maximum limits.

What I want you to keep in mind is that both farmed and wild salmon are still valuable sources of omega-3 fatty acids, vitamins and minerals, and the benefits in all cases are many. It is good to have some oily fish in our diet at least once a week and be a little careful with the information we receive

If you're interested, you can explore my sources listed below for further study!

Bibliography:

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