Ethoxyquin

Ethoxyquin (EQ) is a synthetic antioxidant that is often added to fish meal to prevent it from exploding during transport by sea and storage.

During 2020, ethoxyquin as an additive in feed was phased out, because it was no longer approved for use in the EU and Norway. It is not permitted to use ethoxyquin as an additive in food

Before this, feed containing fish meal therefore also could contain ethoxyquin. Ethoxyquin is transferred from the feed to the fish fillet, but there it is quickly transformed into other compounds.

With the help of new analytical tools, researchers have ascertained which compounds ethoxyquin is transformed into in the fish fillet. They found many different compounds, with the most common one being ethoxyquin dimer (EQDM). Ethoxyquin dimer has a long half-life and takes a long time to disappear from salmon fillets.

There is no evidence of exposure to ethoxyquin causing any harm to humans, but in experiments, mice given high doses of it showed signs of oxidative stress and of disruptions to their metabolism of fat that could be a precursor to fatty liver.