Scientific Opinion on re-evaluation of one flavouring substance 3-acetyl-2,5-dimethylthiophene [FL-no 15.024] from FGE.19 subgroup 5.2

The 26th Plenary meeting of the AFC Panel on 27-29 November 2007 discussed the flavouring group evaluation 19 (FGE.19) which included alpha, beta-unsaturated aldehydes or ketones considered to be a structural alert for genotoxicity. The flavour industry was requested to submit data on genotoxicity of 3-acetyl-2,5-dimethylthiophene [FL-no 15.024] (subgroup 5.2 in the FGE.19; the other substances of this subgroup were evaluated in FGE.224). An in vitro bacterial mutation assay was positive in Salmonella typhimurium strains TA98, TA100 and TA102 in the presence of rat liver metabolic activation system (S9-mix), and an in vivo study on mutant frequency in Muta™Mice was positive in liver after exposure to 3-acetyl-2,5-dimethylthiophene. Based on this outcome the CEF Panel considered 3-acetyl-2,5-dimethylthiophene as mutagenic in vitro and in vivo and concluded that its use as flavouring substance raises a safety concern.