Diphenyl(2,4,6-trimethylbenzoyl)phosphinoxid

Large Crystals; Liquid; Liquid; CBI; Dry Powder

Solid (yellow powder)

Danger

H317: May cause an allergic skin reaction [Warning Sensitization, Skin]

P203, P261, P272, P280, P302+P352, P318, P321, P333+P317, P362+P364, P405, and P501 (click each P-code to see the statement)

This chemical does not meet GHS hazard criteria for 0.4% (13 of 3088) of reports.

Warning

H317 (12.5%): May cause an allergic skin reaction [Warning Sensitization, Skin]

Chemical: Phosphine oxide, diphenyl(2,4,6-trimethylbenzoyl)-

Hazard Traits - Reproductive Toxicity

Methanone, (diphenylphosphinyl)(2,4,6-trimethylphenyl)- is listed on the EPA's Chemical Data Reporting (CDR) system. Manufacturers and importers of Methanone, (diphenylphosphinyl)(2,4,6-trimethylphenyl)- are required to report information about their production and use of this chemical to the EPA under the Toxic Substances Control Act (TSCA). (40 eCFR Part 711)

PMN - indicates a commenced PMN (Pre-Manufacture Notices) substance.

Status: Active Update: 03-03-2022 https://echa.europa.eu/registration-dossier/-/registered-dossier/13110

Substance: diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide

Skin Sens. 1 (12.5%)

Reproductive toxicity - category 2

Repr. 1B

A 2014 Expert Opinion by the European Commission's Scientific Committee on Consumer Safety (SCCS) noted that the acute oral LD50 of Trimethylbenzoyl diphenylphosphine oxide (TPO) in rats was greater than 5000 mg/kg body weight, the dermal LD50 in rats was greater than 2000 mg/kg body weight, and that no data are available for acute inhalation toxicity. Also, the 2014 Expert Opinion described 28-day and 90-day oral studies in rats. The NOAEL in the 28-day study was 50 mg/kg body weight/day and the NOAEL in the 90-day study was 100 mg/kg body weight/day. Further, TPO showed irritation potential to rabbit skin and rabbit eyes, showed moderate sensitization potential in a Local Lymph Node Assay (LLNA) test in mice, and showed no genotoxic/mutagenic potential in bacterial gene mutation and Chinese hamster V79 cell assays. In addition, the 2014 Expert Opinion noted that no carcinogenicity are available while repeated dose toxicity studies in rats found marked testicular atrophy. The 2014 Expert Opinion concluded that Trimethylbenzoyl diphenylphosphine oxide (TPO) is safe when used as a nail modelling product at a concentration of at maximum 5.0%. However, the 2014 SCCS Expert Opinion noted that TPO is considered a moderate skin sensitizer and that other potential uses in cosmetic products cannot be evaluated without further documentation. Further evaluation led to the European Commission prohibitiing the use of TPO in cosmetic products beginning on September 1, 2025 (via the adoption of Commission Regulation (EU) 2025/877). This was the result of TPO being classified as a CMR category 1B reproductive toxicant by Commission Delegated Regulation (EU) 2024/197 under the CLP Regulation (Regulation (EC) No 1272/2008), and this classification triggered the mandatory inclusion of TPO in Annex II (prohibited substances) of the Cosmetics Regulation via Regulation (EU) 2025/877.

A 2021 review describes in detail the mechanism of actionr of trimethylbenzoyl-diphenylphosphine oxide as a type-1 photoinitiator in dental resin composites. It undergoes rapid cleavage from a triplet excited state to yield two radicals (trimethylbenzoyl radical and diphenylphosphinoyl radical) that initiate polymerization.

Solvent

The European Commission prohibited the use of TPO in cosmetic products beginning on September 1, 2025 (via the adoption of Commission Regulation (EU) 2025/877). This was the result of TPO being classified as a CMR category 1B reproductive toxicant by Commission Delegated Regulation (EU) 2024/197 under the CLP Regulation (Regulation (EC) No 1272/2008), and this classification triggered the mandatory inclusion of TPO in Annex II (prohibited substances) of the Cosmetics Regulation via Regulation (EU) 2025/877.

Not Known or Reasonably Ascertainable

A 2021 review describes use as a photoinitiator in dental resin composites.

Printing Ink Manufacturing

Methanone, (diphenylphosphinyl)(2,4,6-trimethylphenyl)-: ACTIVE