Abstract  The category contains four structurally related propylene glycol ethers: - Propylene Glycol n-Butyl Ether (PnB, 5131-66-8, major (“alpha”) isomer, 29387-86-8 isomeric mixture) - Dipropylene Glycol n-Butyl Ether (DPnB, 29911-28-2 major isomer or 35884-42-5 isomeric mixture)) - Dipropylene Glycol Methyl Ether Acetate (DPMA, 88917-22-0 isomeric mixture) - Tripropylene Glycol Methyl Ether (TPM, 20324-33-8 one of the isomers and 25498-49-1 isomeric mixture) The alpha (secondary alcohol) form is kinetically favored during synthesis. PnB is available as the isomeric mixture in which the alpha isomer is the predominant isomer (ca. 95%. DPnB, DPMA and TPM are commercially produced as mixtures of isomeric components in which the internal ether linkages may be adjacent to either primary or secondary carbon atoms. Thus, for DPMA and DPnB the commercially produced products may contain up to 4 such isomers. In the case of TPM, the commercially produced product may contain up to 8 such isomers. Data for these propylene glycol ethers are supplemented with data from three propylene glycol ethers that are closely related to the category members in molecular structure, physicochemical properties and toxicity and thus extend the category. These compounds are: - Propylene Glycol Methyl Ether (PM; CAS No. 107-98-2) - Propylene Glycol Methyl Ether Acetate (PMA; CAS No. 108-65-6) - Dipropylene Glycol Methyl Ether (DPM; CAS No. 34590-94-8 isomeric mixture and 20324-32-7 major isomer) PM and PMA were reviewed at SIAM 11 and DPM was reviewed at SIAM 12. All were assigned as low priority for further work.

Abstract  The Cosmetic Ingredient Review (CIR) Expert Panel (Panel) assessed the safety of 46 butyl polyoxyalkylene ethers that share a common structural motif, namely a butyl chain (4 carbon alkyl chain) bound to a polyoxyalkylene (PPG, PEG, or both); 23 of these ethers were previously reviewed by the Panel, and 23 are reviewed for the first time. Most of the butyl polyoxyalkylene ethers have several functions in cosmetics, but the most common functions include hair conditioning agent and skin conditioning agent, and many function as fragrance ingredients. Upon review of new data, including frequency and concentration of use, and data from previous CIR reports and on read-across analogs, the Panel concluded that these ingredients are safe in the present practices of use and concentration in cosmetics when formulated to be non-irritating.