Following a request from the European Commission, the EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids was asked to deliver a scientific opinion on re-evaluation of one flavouring substance 3-acetyl-2,5-dimethylthiophene [FL-no 15.024] from FGE.19 subgroup 5.2.
In the 26th Plenary meeting of the AFC Panel on 27-29 November 2007, EFSA discussed the flavouring group evaluation 19 (FGE.19) including flavouring substances which are alpha, beta-unsaturated aldehydes or ketones or precursors thereof. These structures are considered to be a structural alert for genotoxicity. 3-Acetyl-2,5-dimethylthiophene [FL-no 15.024] belongs to subgroup 5.2 in the FGE.19.
In 2013 the CEF Panel concluded in its Scientific Opinion on FGE.224 (EFSA, 2013) that for the substance 3-acetyl-2,5-dimethylthiophene [FL-no 15.024] no conclusion could be taken due to the lack of data on genotoxicity.
The missing data has now been submitted by the European Flavour Association to the European Commission which asked EFSA to evaluate this new information.
The data submitted consist of an in vitro bacterial mutation assay and an in vivo Muta™Mice study which were performed in compliance with Good Laboratory Practice and according to the OECD Guideline 471 and 488, respectively.
The bacterial mutation assay shows a dose-dependent positive outcome in the strains TA98, TA100 and TA102 in presence of Aroclor induced rat liver S9-mix (at non toxic concentrations), indicating that the mutagenicity observed in this assay is due to a metabolite of the substance.
In addition, an in vivo study in Muta™Mice has been performed monitoring mutant frequency in liver and duodenum, and counting of micronucleated reticulocytes in the peripheral blood. Results from this study showed a dose dependent increase in the mutant frequency for liver, while no dose-related effects where observed for mutant frequency in duodenum nor was an increase in micronucleated reticulocytes observed. The results of the in vivo study further support the hypothesis that the mutagenicity observed is due to a metabolite of the 3-acetyl-2,5-dimethylthiophene.
The CEF Panel concluded that 3-acetyl-2,5-dimethylthiophene is mutagenic both in vitro and in vivo and that therefore its use as flavouring substance raises a safety concern.