E123 o Amaranto is a common food colour, an azo dye and an ingredient on the European food additives list.

This azo dye, which can mostly be found in soft drinks, has the prerogative of splitting rather easily into amines, organic ammonia derivatives, and is believed to cause mutagenicity and tumours (1).

Safety

The problem with azo dyes (monoazo or diazo) is photocatalytic degradation leading to oxidation and the subsequent formation of impurities such as aromatic amines, some of which have carcinogenic activity.

References_________________________________________________________________________

(1) Buledi JA, Solangi AR, Hyder A, Khand NH, Memon SA, Mallah A, Mahar N, Dragoi EN, Show P, Behzadpour M, Karimi-Maleh H. Selective oxidation of amaranth dye in soft drinks through tin oxide decorated reduced graphene oxide nanocomposite based electrochemical sensor. Food Chem Toxicol. 2022 Jul;165:113177. doi: 10.1016/j.fct.2022.113177.

(2) Barros, W. R., Steter, J. R., Lanza, M. R., & Motheo, A. J. (2014). Degradation of amaranth dye in alkaline medium by ultrasonic cavitation coupled with electrochemical oxidation using a boron-doped diamond anode. Electrochimica Acta, 143, 180-187.