Hexa-2,4-dienoic acid (CAS No.110-44-1, EC No.203-768-7, INCI: Sorbic Acid) is an ingredient listed in Cosing, with the function: Fragrance, Preservative.
It is regulated by the European Cosmetics Regulation 1223/2009 in Annex V/4 (Authorised preservatives), which limits its maximum concentration to 0.6% (as acid) in finished cosmetic products. It is not currently listed in Annex VI of the European CLP Regulation 1272/2008.

Germany intends to propose classifying the substance as follows.
• Skin Irrit. 2, H315 - Causes skin irritation.
• Eye Irrit. 2, H319 - Causes serious eye irritation.
• Skin Sens. 1B, H317 - May cause an allergic skin reaction.

Sources
• ECHA Weekly - Classification, Labelling and Packaging - New intentions and proposals to harmonise classification and labelling, ECHA, 19 August 2026
• Registry of CLH intentions until outcome - Hexa-2,4-dienoic acid, ECHA, 11 August 2026