What's in it? Courmarin

Also known as: 2H-1-Benzopyran-2-One, Tonka Bean Camphor.

What's it used in? Fragrances, moisturisers, hair colourants, sunscreen. Smells like mown hay.

Any controversy? It's banned as a fragrance chemical in the EU. because of its adverse effects on the immune system and as a recognised consumer allergen. It's still used in US-distributed cosmetics.

The US Food and Drug Administration once approved it as a food additive but it is now banned from food. Some scientific literature also says it could be a cancer hazard.