TPO, explained: the EU ban and what it means for your polish

On September 1, 2025, an ingredient that quietly lived inside a huge share of the world's gel polish became illegal to sell in cosmetics across the European Union. The ingredient is TPO, and if you wear gel, the story is worth understanding, because it explains a wave of reformulations, salon menu changes, and TPO-free labels that is still rippling through the nail world.

What TPO is and what it does

TPO is short for trimethylbenzoyl diphenylphosphine oxide (the full chemical name is diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide). It is a photoinitiator: the ingredient in gel polish that absorbs light from a UV or LED lamp and kicks off the chain reaction that hardens liquid gel into a solid, glossy coat.

Photoinitiators are why gel cures in sixty seconds instead of air-drying for an hour. TPO was one of the most widely used because it works fast, cures deeply through pigmented layers, and resists yellowing. For years it was simply part of how gel worked.

What the EU actually did

The European Commission classified TPO as a category 1B reproductive toxicant under EU chemicals law, based primarily on animal studies. Under the EU's cosmetics regulation, substances with that classification are automatically prohibited in cosmetic products. The ban was adopted in Commission Regulation (EU) 2025/877, published in May 2025, and took effect on September 1, 2025.

The practical meaning inside the EU since that date:

• Cosmetic products containing TPO can no longer be sold or supplied, including products already sitting on shelves.
• Professional use counts too. Salons in the EU cannot legally use up old TPO stock.
• Brands selling in Europe reformulated with alternative photoinitiators, which is why so many gel lines relaunched with new formulas in 2025.

One important nuance the headlines often missed: the classification was driven by hazard identified in animal studies of ingested TPO, not by documented harm to people wearing gel manicures. Reputable chemistry and consumer-safety coverage at the time made this distinction clearly: the EU takes a precautionary approach, and once the classification landed, the cosmetics ban followed automatically. Regulators did not conclude that people who wore gel polish had been harmed.

What it means outside the EU

• United States: as of this writing, TPO is not banned. Polishes containing TPO remain legal to sell and use in the US. The FDA regulates cosmetics under a different framework, and no equivalent action has been taken.
• United Kingdom and elsewhere: the UK has its own cosmetics rules post-Brexit, and other markets have their own timelines. Rules move; if compliance matters to you professionally, check the current guidance where you live.

So an American shopper may still encounter TPO in gel formulas, which is exactly why the TPO-free label has traveled across the Atlantic. Some people want to match the EU standard as a precaution. Some brands sell one global formula and reformulated everywhere at once. Either way, TPO-free has become a label people actively look for.

Does this mean gel polish is dangerous?

This is the question everyone actually wants answered, so let us be precise about what is and is not known.

The EU classification reflects a hazard assessment: at some dose, by some route, TPO showed reproductive toxicity in animal studies. That is different from evidence that wearing gel manicures caused harm. When TPO cures under the lamp, it is consumed by the reaction it initiates; concerns focus on uncured product and residual amounts. Regulators in Europe judged that, given the classification, cosmetics should not contain it at all. Regulators in the US have not acted on it.

If you want to avoid TPO, that is a completely reasonable preference, and it is now an easy one to act on. If you have been wearing gel with TPO for years, the honest summary of the public record is: the EU acted out of precaution based on animal data, not because of documented harm to gel wearers.

How to find TPO-free polish

Polish Index™ tracks brand-stated certifications on every polish in the catalog, including TPO-Free. Browse everything we track with that label on our TPO-Free polishes hub, or start at the Clean Beauty section to combine it with other filters that matter to you, like HEMA-Free if you are also thinking about allergens (TPO and HEMA are different concerns: one is a regulatory story, the other is the most common gel allergen; our HEMA guide covers the difference).

As always: we report what brands publish about their formulas, and brands reformulate. For anything medically or professionally important, confirm against the label on the bottle in your hand.

Sources

• European Commission: TPO in nail products, questions and answers
• Chemistry World: "Why has the EU banned a key chemical in gel nail products?"
• Chemical & Engineering News: "The EU banned a common ingredient in gel nail polish. But don't panic."
• CNN Health: Europe bans TPO, classifying it as a reproductive toxicant