Ethoxyquin and its breakdown products in farmed salmon muscle
What it found
In Atlantic salmon, ethoxyquin fed in the diet built up in muscle and was not fully cleared after two weeks of clean feeding.
A main breakdown product, EQDM, made up almost all of what remained.
What they found
Animal and lab studies
Breakdown products found
Four substances were found in the muscle of the salmon: ethoxyquin itself, quinone imine, de-ethylated ethoxyquin, and EQDM. EQDM was the main one.
Ethoxyquin cleared quickly
Ethoxyquin levels in the muscle dropped fast, with a half-life of 2.4 days.
EQDM rose as ethoxyquin fell
As ethoxyquin levels fell, EQDM levels rose. The total amount of the two together stayed the same after the 2 weeks of clean feeding.
Depuration not complete
The required 14 days of clean feeding before slaughter in Norway was not enough to completely remove ethoxyquin-related leftovers from the salmon.
EQDM dominated after depuration
After the clean feeding period, EQDM made up 99% of the combined amount of ethoxyquin and EQDM in all groups.
Feed level controls residues
The amounts of ethoxyquin and EQDM in the fish depended on how much ethoxyquin was in the feed. This means the leftovers in the fish can be controlled by adjusting the feed.
What the authors conclude
“The mandatory 14 days depuration period prior to slaughtering of farmed salmon in Norway was not sufficient for complete elimination of EQ-derived residuals.”
Also in their conclusions
- They say the mandatory 14 days depuration period prior to slaughtering of farmed salmon in Norway was not sufficient for complete elimination of EQ-derived residuals.
- They note that possible toxicological effects of EQDM are not known.
- They state that the theoretical amount of EQ and EQDM consumed in one meal of farmed salmon would be under the recommended ADI, provided that the fish were raised on feed with no more than 150 mg EQ/kg feed, which is the EU maximum limit for EQ in fish feed.
How it was done
Atlantic salmon were fed ethoxyquin for 12 weeks, then given clean feed for 2 weeks. The researchers measured ethoxyquin and its breakdown products in the fish muscle.
What it can’t tell you
- We summarised it from the abstract only.
- This study looked only at salmon muscle. It cannot show what these residues might do in people who eat the fish.
- The possible toxicological effects of EQDM are not known, so this study cannot say whether it is harmful.
Who paid
- Authors work at
- National Institute of Nutrition and Seafood Research (NIFES), Norway
The paper
- Title
- Accumulation and depuration of the synthetic antioxidant ethoxyquin in the muscle of Atlantic salmon (Salmo salar L.)
- Type
- Study
- Evidence
- Animals and lab studies
- Summarised from
- Abstract only
- Cite
- Bohne VJ, Lundebye AK, Hamre K (2008). Accumulation and depuration of the synthetic antioxidant ethoxyquin in the muscle of Atlantic salmon (Salmo salar L.). Food and chemical toxicology. doi:10.1016/j.fct.2008.01.028PubMed 18329775DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error