Fish feed additive banned in EU found in Tasmanian salmon at concerning levels, researchers say

A fish feed additive banned in the European Union out of concerns for health impacts in animals and humans has been found in Tasmanian salmon at concerning levels, say experts who are calling for tighter regulations.

Dr Christian Narkowicz, an organic chemist, last year commissioned the National Measurement Institute to test salmon for residues of ethoxyquin.

The compound, a synthetic antioxidant, was developed by Monsanto in the 1950s. It has been used to prevent fish meal from spontaneously combusting while being transported at sea.

The national regulator, the Australian Pesticides and Veterinary Medicines Authority, has set a maximum residue limit for ethoxyquin of 1mg per kilogram of salmon.

In the Tassal sample, the ethoxyquin level was 0.34mg/kg and the dimer level was 1.2mg/kg, resulting in a combined rate of 1.54mg/kg. In the Petuna sample, there was 0.11mg/kg of ethoxyquin and 0.91mg/kg of dimer, giving a sum of 1.02mg/kg.

Researchers say the maximum residue limits should also take into account levels of the ethoxyquin dimer.

The dimer is considered to have the same toxic potential as ethoxyquin itself, said Stuart McLean, emeritus professor at the University of Tasmania.

European regulators also expressed concerns about the presence of a compound called p-phenetidine, from which ethoxyquin is made, which can persist as an impurity in the product.

Narkowicz noted that the testing showed higher levels in Australian fish than were found in European studies before the EU ban.

Since the EU ban, other antioxidants have been used to stabilise fish feed during transportation, such as rosemary oil extract and tocopherols (vitamin E and vitamin E-like substances), Narkowicz said.

A spokesperson for Petuna said it predominantly sourced its feed from the Tasmanian company Biomar, which did not add ethoxyquin to its feed.

The firm said its results to date indicated it had at no time exceeded maximum residue limits.

A spokesperson for Tassal declined to comment.