Consumer safety of dietary ethoxyquin dimer exposure

Ethoxyquin, a synthetic anti-oxidant, is one of a number of authorized technological feed additives (E324) used as an ingredient in animal feed. The use of ethoxyquin as a direct additive in food products meant for human consumption is currently not permitted in Europe, however, the use of ethoxyquin in fish feed, may result in residues of this compound and its metabolites in the edible part of fish. Ethoxyquin is currently under reauthorisation in the European Union, and documentation on the safety of this feed additive for animals and consumers of food products of animal origin is required. Ethoxyquin used in salmon feed is metabolized and found in salmon fillet mainly as ethoxyquin dimer. Consumer safety assessment of ethoxyquin and ethoxyquin dimer present in foods of animal origin by the European Food Safety Authority in 2015 was prevented by a lack of toxicological exposure data. In this project, we have therefore planned a toxicological exposure study with mice, in order to determine effect levels of sub-chronic dietary exposure to ethoxyquin dimer. Male mice will be exposed to increasing levels of ethoxyquin dimer (EQDM) through their diet for the duration of 90 days, including levels relevant for human exposure through fish consumption. Since the planned study is a toxicological experiment, a moderate stress will be imposed on the animals, however at the highest doses chosen, we do not expect acute toxicity and harmful effects will thus be limited. The dose-response design includes 7 doses of EQDM, including a negative control and an additional reference group exposed to ethoxyquin (8 experimental groups in total). This design allows for calculation of a "bench-mark dose" model, which can be used for derivation of a safe margin of EQDM exposure. The number of animals included is in compliance with the official guidelines for testing of chemicals established by the Organization for Economic Co-Operation (OECD), in order to assure quality and relevance of the obtained results. However, in order to reduce the number of animals, the planned experiment includes only males, which have been shown to be more sensitive to oral ethoxyquin exposure, thereby cutting the number of animals used by half. In addition, the application of an inbred mouse strain (Balb/c) facilitates the use of the minimum number of animals required per experimental group according to the OECD guidelines (10 animals per group; 80 animals in total).
The results of this study will contribute with relevant knowledge for future safety assessments regarding human exposure to EQDM present in food.