Ethoxiquin has been found in Tasmanian salmon at concerning levels, local news reported, and experts are calling for tighter regulations.

Christian Narkowicz, an organic chemist, last year commissioned the National Measurement Institute to test salmon for residues of ethoxyquin. The national regulator, the Australian Pesticides and Veterinary Medicines Authority, has set a maximum residue limit for ethoxyquin of 1mg per kilogram of salmon. The testing commissioned by Narkowicz found that ethoxyquin levels in three brands of Tasmanian salmon were within the maximum residue limits. However, it found that in Tassal and Petuna salmon there were significant levels of ethoxyquin dimer – two ethoxyquin molecules joined together – which forms as the additive undergoes chemical changes.

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.

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

The European Commission suspended the use of ethoxyquin as an animal feed additive in 2017.