Salmon may not be as healthy as you thought, thanks to ethoxyquin!


Salmon is known as a healthy food, rich in Omega-3 fatty acids. What you may not have known is that most Atlantic farmed salmon is contaminated with chemicals such as ethoxyquin (EQ), butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA) that is used to preserve fish food.

What is ethoxyquin?

Ethoxyquin is a synthetic antioxidant that’s added to fish food for preservation. In other words, it prevents the fat in the fish food from becoming rancid. The European Union has outlawed the use of ethoxyquin as a pesticide and has established strict limits for vegetables, fruits, nuts and meat. However, there are no limits for ethoxyquin in fish.

The problem is that measurable amounts of the chemicals in fish food remain in the fish we eat and thus get transferred into the human body. In a study from 2010, scientists determined that consuming 300 g of commercially farmed salmon would contribute at most 15% of the acceptable daily intake (ADI) of ethoxyquin for a 60 kg adult.

Other chemicals

While the contamination of a 300 g portion of Atlantic salmon with ethoxyquin would not exceed a contribution of 15% of the ADI, BHT on the other hand, would contribute up to 75% of the ADI. Both the United States and the European Union allow the use of small amounts of BHT as a food additive. There doesn’t seem to be any regulation of its use in fishmeal that I could find. Butylated hydroxyanisole, also known as food additive E320, is a newer antioxidant, that has started replacing BHT. The National Institute of Health (NIH), states that there is sufficient evidence of carcinogenicity for BHA in animals, meaning it’s likely to cause cancer. For humans, there is not enough data available.

What’s the issue with synthetic antioxidants?

Chemicals such as EQ, BHT and BHA are toxic, and while levels for the acceptable daily intake have been established, there are no long-term studies available that have determined the effects of those chemicals on the human body. The German toxicologist Prof. Daniel Dietrich is very clear about that he does not want to have any of those chemicals in his body (original interview in German). The European Food Safety Authority (EFSA) has reviewed ethoxyquin in 2015 and determined that there is a lack of data to assess the safety of this chemical as a feed additive or its safety for consumers and the environment. However, EFSA indicated that one of its metabolites, ethoxyquin quinone imine, could be possibly genotoxic, and p-phenetidine, an impurity that could be present from the manufacturing process, could be potentially mutagenic. That means, ethoxyquin and its by-products could potentially damage your DNA.

What has the Norwegian fish industry to say?

It shouldn’t come as a surprise that the Norwegian National Institute of Nutrition and Seafood Research (NIFES) claims that the levels of ethoxyquin in the fish feed are safe for humans. But the fact of the matter is, we don’t know if that is true, due to the lack of long-term studies.

What I do know is that I prefer to err on the side of caution and not eat chemicals that have been forbidden to be used as pesticides and that I can’t pronounce.

Ethoxyquin - farmed salmon
Net pens at Marine Harvest salmon farm in Norway are submerged in ocean water. MARINE HARVEST ASA (Image credit WSJ)

The salmon I consume

I like salmon and eat it regularly, and we usually buy the Kirkland brand of Costco. After I had learned about the use of those toxic chemicals in fish feed, I reached out to Costco to inquire if their salmon is affected as well. In the first response from their corporate communications center, they referred me to their Sustainable Fisheries page. That page references an initiative of the World Wildlife Fund (WWF) called Salmon Aquaculture Dialogue (SAD). SAD is a voluntary standard for responsible salmon aquaculture. Costo’s goal is only to work with suppliers that adhere to that standard. The problem is that SAD does not cover the use of synthetic antioxidants in fish feed. So I reached out to Costco again to ask for clarification. I also reached out to Whole Foods, Kroger, and Publix with the following results:

Costco: “Unfortunately, we are not able to provide a response to your question at this time.”

Kroger: No response.

Publix: “None of our suppliers use Ethoxyquin or butylated hydroxytoluene in their processes. However,  Ethoxyquin is required to be added to fish-meal to prevent it from exploding during sea transport and storage. The European Union has set a combined upper limit for ethoxyquin and other antioxidants (BHA and BHT) of 150 mg per kg of feed. Data obtained from fish-feed and feed-ingredient monitoring programs have not revealed any instances of this limit being exceeded in salmon feed.”

Walmart: No response.

Whole Foods: Couldn’t provide any information by the time I published this article. Should I receive more information, I will update this post.

It was discouraging to learn, that only Publix could or was willing to share meaningful information about the use of synthetic antioxidants in fish feed. And even they admitted the use of those chemicals in fish-meal while giving no indication, how much of them end up in the fish meat we consume.

Risk limited to fish?

Unfortunately, all of the three preservatives I mentioned above, are used in many other areas as well, including makeup, pet food, skin care products or other food we eat. That motivates me, even more, to buy organic food, if possible.


Similar to breeding cows, pigs, and chicken, the goal of the fish industry is to grow and sell their product as quickly as possible, and they do whatever it takes to make that happen. That often means the use of pharmaceuticals (such as antibiotics) and toxic additives to fish feed. These days, most meat and poultry is properly labeled, allowing consumers to make educated purchase decisions. I have yet to see a label that indicated whether or not the manufacturer used toxic chemicals to feed the fish. Going forward, I’ll stick to wild-caught salmon whenever I can. If you take fish-oil capsules, also make sure you buy a brand that uses wild-caught instead of farmed salmon, such as the ones from Life Science.

Michael Kummer

🇦🇹 Austrian 📜 Blogger 👨‍👩‍👧‍👦 Father of a princess and a preemie 🥑 Fan of Paleo lifestyle 💻 Technologist ✈️ Frequent flyer 📱Amateur photographer