TPO in Nail Products — Is It Safe?
Also known as: Trimethylbenzoyl Diphenylphosphine Oxide, 2,4,6-Trimethylbenzoyl-diphenylphosphine oxide
About TPO
TPO (Trimethylbenzoyl Diphenylphosphine Oxide) is a photoinitiator used in UV/LED curable gel nail products to initiate polymerization upon light exposure. It has been classified as a potential skin sensitizer, and there are concerns about endocrine-disrupting properties. The EU has tightened restrictions on its use in cosmetics. Incomplete curing (under-curing a gel layer) can leave residual unreacted TPO, significantly increasing dermal exposure risk.
Quick Answer
- TPO is a photoinitiator, not a builder gel monomer.
- TPO-free does not mean HEMA-free, and HEMA-free does not mean TPO-free.
- Lamp compatibility and cure time matter because photoinitiators are part of the curing system.
Common product types
Regulatory status
European Commission guidance says TPO-containing cosmetic products are prohibited on the EU market from September 1, 2025 after CMR category 1B classification and inclusion in Annex II of the Cosmetics Regulation.
TPO-Free Alternatives
These products are marked HEMA-free in our database and do not disclose TPO. They are lower-risk starting points, not allergy-proof choices.
FAQ
What is TPO?
TPO (Trimethylbenzoyl Diphenylphosphine Oxide) is a photoinitiator used in UV/LED curable gel nail products to initiate polymerization upon light exposure. It has been classified as a potential skin sensitizer, and there are concerns about endocrine-disrupting properties. The EU has tightened restrictions on its use in cosmetics. Incomplete curing (under-curing a gel layer) can leave residual unreacted TPO, significantly increasing dermal exposure risk.
How dangerous is TPO in nail products?
TPO is classified as medium risk in our system. Photoinitiator used in UV/LED gel systems. Potential sensitizer and endocrine disruptor concern.
What are other names for TPO on ingredient labels?
TPO may also appear as: Trimethylbenzoyl Diphenylphosphine Oxide, 2,4,6-Trimethylbenzoyl-diphenylphosphine oxide.
Sources
Ingredient Disclaimer
This page is educational and does not diagnose allergy. Ingredient labels and formulas can change; verify the current package and ask a healthcare professional if you have symptoms or a known acrylate allergy.