Citral

citral (geranial + neral)

What it is: A mixture of two isomers – geranial and neral – with a strong lemon smell.
Why it is used: An intense lemon tone that lemon oil alone would not give.
Where you usually find it: Lemongrass, litsea cubeba, lemon peel; soaps, shampoos, perfumes.
Role in the fragrance: Top note.
Notes in the atlas: Bergamot

What EU law says

Annex III to Regulation (EC) No 1223/2009: its presence must be indicated in the list of ingredients when its concentration exceeds 0.001% in leave-on and 0.01% in rinse-off products. One of the 26 allergens introduced by Directive 2003/15/EC. In detergents it is listed above 0.01% by weight under Regulation (EC) No 648/2004.

In detail: fragrance allergens and the deadlines of Regulation 2023/1545