Is There Sufficient Data to Ban TPO in UK?

8 days ago

Written by Dr Sepideh Yaghmaei

8 days ago

Written by Dr Sepideh Yaghmaei

After hearing about the ban on certain nail gel polishes in the UK (linked to fertility concerns in animals), I became curious. What exactly in the data was so alarming that it justified such a widespread restriction?

TPO (trimethylbenzoyl diphenylphosphine oxide) is a photoinitiator used in many UV- and LED-cured gel nail polishes. It helps the formulas harden and cure under the lamps, contributing to the durable, glossy finish that made gel manicures so popular. It is typically present at low concentrations (1–5 %, maximum reported around 4 %) and is largely broken down during the curing process, with any residual amounts trapped in the hardened polymer.

The ban is already in force: TPO has been prohibited from new cosmetic products placed on the Great Britain market as of 15 August 2026. This follows the earlier EU ban that took effect on 1 September 2025. Existing stock can continue to be sold or supplied until 14 February 2027, after which distributors can no longer make TPO-containing products available.

Nail technicians in England, Scotland and Wales may still use any remaining products they already hold after that date (according to guidance from the Cosmetic, Toiletry and Perfumery Association developed with Trading Standards). Northern Ireland already follows the EU rules.

According to the Cosmetic Ingredient Review (CIR) safety assessment of TPO, the only findings of infertility or reproductive toxicity — including testicular atrophy, reduced sperm production and quality, zero fertility index, and extended diestrus — come from oral (gavage) studies in rats. These effects appeared at high doses, typically hundreds of milligrams per kilogram of body weight per day (for example, effects at 250–1000 mg/kg/day, with no-observed-adverse-effect levels around 50–100 mg/kg/day depending on the study).No reproductive or infertility effects have been reported from dermal or topical application studies at relevant doses. The CIR assessment also contains no human studies at all.

In nail gel polish the concentration is far lower, it is applied only to the nail plate, most of the TPO is consumed during UV/LED curing, and any residual amount left is extremely small. Estimated human systemic exposure from a full set of nails is thousands of times lower than the oral doses that caused effects in the animal studies. So the reproductive findings are limited to high-dose oral consumption in animals and do not reflect the way, or the amount, TPO is used in gel nail products.

I’m firmly committed to working with what nature provides and deliberately avoiding lab-synthesized ingredients. I don’t even wear nail polish — instead, I simply use pure balm butters to give my nails a natural shine and keep the cuticles soft and healthy. That’s exactly why this sweeping ban leaves me so unconvinced: when the only evidence of harm comes from extreme, high-dose oral studies in animals that bear no resemblance to real-world use, is such a heavy-handed restriction truly justified?

It will be interesting to see how long this ban holds — or whether the industry simply introduces another synthetic replacement so the popular gel-nail trend can continue unchanged.