Many people love gel nail polish for its durability and shiny gloss, but a new ban in Europe may have left mani-pedi devotees with some not-so-pretty concerns.

On Sept. 1, the European Union banned one of the key ingredients from being manufactured, sold or commercially used. Nail technicians in salons across the continent need to dispose of polishes containing trimethylbenzoyl diphenylphosphine oxide, or TPO, and switch to alternatives.

The chemical was classified as “carcinogenic, mutagenic, or toxic to reproduction” by European regulators after it was found to have reproductive toxicity effects in animal studies. In the United States, TPO remains legal and unrestricted in its use and sale.