TPHP, or triphenyl phosphate, is a plasticiser used in some nail polishes to keep the dried film flexible, and it draws attention because it is under scrutiny as a suspected endocrine (hormone) disruptor.
Also known as: triphenyl phosphate, TPP, TPHP nail polish, trifenylfosfaat
Triphenyl phosphate (TPHP) is an organophosphate that was adopted by polish makers as a replacement for dibutyl phthalate (DBP) after DBP fell out of use. Like any plasticiser it softens the nitrocellulose film so the coat bends with the nail. On an ingredient list it appears as triphenyl phosphate; some brands abbreviate it TPP.
The concern is endocrine disruption. Label Lookout describes TPHP as the chemical most free-from lists miss, because a polish can be 5-free or 7-free and still contain it (Label Lookout). It is usually the item that separates a 7-free list from a 9-free or 10-free one. Mooncat's 10-free list names it as TPP alongside DBP, toluene, formaldehyde and camphor (Mooncat), and Manucurist's 12-free blacklist includes it (Manucurist).
TPHP is not the same substance as TPO, the photoinitiator banned in EU gel polish from 1 September 2025. TPHP is a plasticiser found in air-dry lacquer; TPO only matters in products cured under a lamp. The similar abbreviations cause confusion in search results and on packaging.
The reliable check is the ingredient list under the International Nomenclature of Cosmetic Ingredients (INCI). If triphenyl phosphate is absent, the polish is TPHP-free, whatever number is printed on the front. Modern formulas that leave it out use citrate plasticisers such as acetyl tributyl citrate instead, which are also used in breathable polishes (Halalworthy).