The European Union (EU) has banned the gel nail polish ingredient trimethylbenzoyl diphenylphosphine oxide (TPO) due to concerns that it is carcinogenic, mutagenic, or toxic to reproduction based on animal studies.
As of September 1, 2025, nail salons and manufacturers in Norway, Switzerland, and all 27 EU member states must immediately stop selling, using, or disposing of TPO-based products, Sky News reports.
TPO causes gel polish to harden under ultraviolet UV light, helping it dry faster and last longer.
It is classified as a Category 1B CMR (carcinogen, mutagen, reprotoxic) substance. Under EU law, classifying an ingredient as a CMR substance triggers an automatic ban on products containing it. The EU TPO ban is seen as precautionary, as scientists have not yet evidenced any risk to humans. Companies must now reformulate their products to be TPO-free.
TPO is still legal in the U.S., and the U.S. Food and Drug Administration (FDA) has not banned it. The UK is considering imposing a similar ban in late 2026, according to media reports.
“TPO was found to cause rodent fertility problems when the animals were fed the ingredient,” explains Zoe Diana Draelos, MD, a Dermatologist in solo private practice in High Point, NC, and President of Dermatology Consulting Services, PLLC. “TPO-free nail products are currently available so that the ingredient can be easily avoided.”
