The chemical that makes gel manicures harden under UV light is about to disappear from British salon shelves. Diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide — known simply as TPO — has been classified as a reproductive toxin, and UK regulators are following through with a hard ban.
New products containing TPO can no longer be sold in Britain starting August 15, 2026. That gives the industry a tight window to restock with compliant formulas. But there’s a cushion for businesses that already have inventory: existing TPO-based products may still be used in salons until February 14, 2027. After that date, the substance is fully off-limits in manicure applications.
The UK is playing catch-up here. The European Union already imposed a
What the Science Says
TPO functions as a photoinitiator — the ingredient that triggers rapid hardening when gel polish meets UV light. Its regulatory downfall stems from animal studies. Rat experiments showed that high doses of TPO were associated with impaired fertility, leading to its classification under chemical regulations as a Category 1B reproductive toxicant.
That classification carries an automatic consequence: substances in this category cannot appear in over-the-counter cosmetics.
Experts, however, urge a measured reading of the risk. The concentrations found in finished nail products are low, they point out, and the chemical is applied topically to the nail plate, where absorption into the body is not straightforward. Still, the legal framework leaves no room for interpretation — once a substance is classified as 1B, a ban in consumer cosmetics is effectively mandatory.
Beyond Chemistry: UV Lamps and Acrylates Under Scrutiny
The TPO ban isn’t the only safety concern swirling around the gel manicure industry. A 2023 scientific study examined what UV curing lamps do to human skin cells. The findings were stark: a single 20-minute exposure killed 20 to 30 percent of cells. Three consecutive sessions pushed that figure to between 65 and 70 percent.
Industry insiders are also flagging the dangers of acrylates, particularly HEMA. Improper application or skin contact can trigger permanent allergies. That’s a serious concern beyond the nail salon — acrylates are widely used in dental technology, so a sensitized individual could face complications in medical settings down the line. Overzealous filing of the natural nail is another hazard that practitioners warn about.
What Replaces TPO?
The market has already adapted. TPO-free alternatives are now widely available, with manufacturers turning to different photoinitiators that deliver the same curing performance without the regulatory baggage.
For clients who want to sidestep the entire category of risks, some professionals point to Japanese manicure techniques. This approach skips chemical curing, acrylates, and UV exposure altogether — a method that neatly sidesteps the hazards that have put gel systems under the microscope.
