Dipropylene Glycol
Also known as DPG, Di-1,2-propylene glycol, Dipropylene glycol (mixed isomers)
“CIR Expert Panel says: safe as used in cosmetics.”
Dipropylene Glycol (DPG; CAS 25265-71-8; C6H14O3) is a mixture of propylene glycol dimer isomers used in cosmetic formulations as a humectant, solvent, and fragrance carrier. It is structurally a propylene glycol dimer — two propylene glycol units linked through an ether bond — and is not a simple diol, but is assessed alongside glycols in the CIR program. The Cosmetic Ingredient Review Expert Panel assessed dipropylene glycol together with butylene glycol, hexylene glycol, and ethoxydiglycol and concluded all four are safe as cosmetic ingredients in the present practices of use (J Am Coll Toxicol 4(5):223-48, 1985; reaffirmed without reopening the assessment in 2004, republished Int J Toxicol 25(Suppl 2):1-26, 2006). The QRT row carries Finding=S with no concentration conditions. DPG is widely used as a low-odor carrier solvent in fragrance applications and as a viscosity modifier in skin-care formulations.
Effective humectant that draws and retains moisture in the stratum corneum; widely used in lightweight hydrating formulations
Low-odor solvent and fragrance carrier; commonly used in perfumery and personal care as a diluent that extends fragrance without contributing its own scent
Good skin-feel and low viscosity make it useful as a spreadability enhancer in serums, toners, and emulsions
CIR Expert Panel concluded safe as used in cosmetics:223-48, 1985; reaffirmed 2004) — same assessment also clears butylene glycol, hexylene glycol, and ethoxydiglycol
- · Mild skin and eye irritation reported in animal studies at high concentrations; not a clinical concern at typical cosmetic use levels (CIR 1985)
As a propylene glycol-derived ether dimer, it shares some physicochemical properties with propylene glycol but is a distinct molecule with a separate CIR assessment history — the two should not be conflated
CIR Quick Reference Table (12/2017, revised 07/2018) - Dipropylene Glycol row: Finding 'S' (Safe), Citation 'JACT 4(5):223-48, 1985 confi…
“Dipropylene Glycol | S | | JACT 4(5):223- 48, 1985 confirmed 02/04 IJT 25(S2), 2006”— QRT-122017revised072018.pdf, p. 46