Why has the EU banned a key chemical in gel nail products?

As of the 1 September 2025, trimethylbenzoyl diphenylphosphine oxide (TPO) – a chemical ingredient in gel nail polish – was prohibited in cosmetic products in the EU after animal studies suggested it could be toxic to human reproduction.

The move has prompted discussion among users and professionals about the potential risk posed by TPO-containing products and, in countries like the UK where it is not yet banned, whether consumers should avoid them.