What is TPO?
- Common Name: TPO
- INCI Name: Trimethylbenzoyl Diphenylphosphine Oxide
- CAS No.: 75980-60-8
- EC No.: 278-355-8
- Function: An ingredient used as a photo-initiator in UV / LED cure gel nail polishes.
- Regulatory Status: TPO is prohibited for use in cosmetic products within both the UK and EU, having been classified as a Category 1B CMR (Carcinogenic, Mutagenic or Reprotoxic) substance for reproductive toxicity.
Why has it been banned?
Under Regulation (EC) No. 1272/2008 (CLP), TPO has been classified as a Category 1B reproductive toxicant. As a result, it is automatically prohibited for use in cosmetic products under the EU Cosmetics Regulation (EC) No. 1223/2009 unless the Scientific Committee on Consumer Safety (SCCS) evaluates the substance and concludes that it is safe for cosmetic use.
The classification is based on evidence from repeated oral-dose toxicity studies in laboratory animals, which demonstrated adverse effects on male fertility. Consequently, TPO has been identified as presenting a potential risk to human health and is no longer permitted in cosmetic products.
What does this mean for nail polish brands and professionals?
Within the EU, TPO has been prohibited for use in cosmetic products since 1 September 2025.
In the UK, the prohibition takes effect on 15 August 2026. From this date, no new cosmetic products containing TPO may be placed on the UK market.
Products that have already been placed on the market may continue to be supplied until the off-shelf deadline of 14 February 2027. After this date, cosmetic products containing TPO must no longer be made available for sale, allowing businesses time to transition to reformulated products that do not contain the banned ingredient.
For further information on the TPO ban, we recommend visiting the Cosmetic, Toiletry and Perfumery Association (CTPA) website, where a dedicated factsheet is available.
How can ESP help?
ESP has many years of experience supporting cosmetic brands and manufacturers with shelf-life extension studies and stability testing.
We can design a tailored testing protocol to demonstrate that your reformulated products remain within specification throughout their intended shelf life, continue to meet customer expectations, and remain safe for consumer use.
With the full UK ban (14 February 2027) approaching, we also offer an expedited testing service to help you meet regulatory timelines.
If you would like to discuss your requirements or learn more about how ESP can support your transition away from TPO, please get in touch with our team.