Safety and efficacy of ethoxyquin (6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline) for all animal species

ethoxyquin, p-phenetidine, ethoxyquin quinone imine, antioxidant, genotoxicity, toxicity, safety
First published in the EFSA Journal
18 November 2015
21 October 2015
Scientific Opinion


The additive ethoxyquin contains ≥ 91 % ethoxyquin, ≤ 8 % ethoxyquin polymers and ≤ 3 % p-phenetidine. It is intended for use in all animal species as an antioxidant at a maximum content of 50 mg/kg complete feed. Ethoxyquin is rapidly absorbed after oral administration. Ethoxyquin oxidation in feed materials and in animals leads to four main compounds: 2,4-dimethyl-6-ethoxyquinoline, ethoxyquin N-oxide, ethoxyquin quinone imine, and ethoxyquin dimer (detected only in fishmeal and in salmon). Ethoxyquin itself is not genotoxic or carcinogenic, and does not cause developmental toxicity. The lowest NOAEL (based on studies in rats and dogs) is 2 mg/kg body weight per day. The genotoxic profile of the dimer reflects that of ethoxyquin. Ethoxyquin quinone imine shows structural alerts for mutagenicity, carcinogenicity and DNA binding; no conclusion on the absence of genotoxicity of ethoxyquin quinone imine is possible. p-Phenetidine is a recognised possible mutagen. Concentrations of 50 mg ethoxyquin/kg and 11 mg ethoxyquin/kg complete feed might be considered as potentially safe for chickens and breeders and for dogs, respectively. No conclusion on potential safe levels for other poultry, pigs, ruminants, fish and cats is possible. Overall, when considering the presence of p-phenetidine in the additive, no conclusion on any safe level of the additive for target animals can be drawn. An assessment of safety for the consumer is prevented by the lack of exposure data, the absence of a safe level of exposure and the presence of p-phenetidine in ethoxyquin. The respirable mist of ethoxyquin is of low toxicity. Ethoxyquin is not a dermal irritant, but is considered a potential irritant to eyes and other mucous membranes and a skin sensitiser. No conclusion on the safety for the environment can be made. Ethoxyquin is a potent antioxidant; however, no data confirm its efficacy at the proposed use level.

Panel members at the time of adoption

Gabriele Aquilina, Vasileios Bampidis, Maria de Lourdes Bastos, Georges Bories, Andrew Chesson, Pier Sandro Cocconcelli, Gerhard Flachowsky, Jürgen Gropp, Boris Kolar, Maryline Kouba, Secundino López Puente, Marta López-Alonso, Alberto Mantovani, Baltasar Mayo, Fernando Ramos, Guido Rychen, Maria Saarela, Roberto Edoardo Villa, Robert John Wallace and Pieter Wester.
Panel on Additives and Products or Substances used in Animal Feed
EFSA Journal 2015;13(11):4272
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