What is it?
A synthetic polymer made from stearyl alcohol, an 18-carbon fatty alcohol, and octyldodecanol, a branched 20-carbon fatty alcohol, joined to citric acid and crosslinked with propanediol, a small diol. The European Union’s cosmetic ingredient database lists its function as humectant, an ingredient that helps skin hold moisture. It is a newer ingredient with far less published safety data than its building blocks.
Key information
- The EU's CosIng database lists it as a humectant, with no restrictions and no opinion from the EU's Scientific Committee on Consumer Safety.
- We found no published safety assessment or test data for this exact ingredient, and it does not appear in the CIR's 2022 table of safety conclusions.
- The CIR Expert Panel has found its building blocks, stearyl alcohol, octyldodecanol, propanediol and citric acid, safe as used in cosmetics.
More information
Citric acid has three acid groups, so one molecule can bond to several alcohol molecules at once. Citrate esters are typically made by condensing an alcohol with citric acid; here the acid is esterified with stearyl alcohol and octyldodecanol, and propanediol links the chains into a crosslinked polyester. The name does not tell you the proportions or the size of the polymer. The EU’s CosIng database lists no restrictions on its use in cosmetics.
We found no Cosmetic Ingredient Review (CIR) assessment of this crosspolymer and no published skin irritation or allergy tests on it, so the case for its safety rests on its parts. The CIR Expert Panel concluded in 1985 that stearyl alcohol and octyldodecanol are safe as used, noting very low toxicity when swallowed and a very low potential for irritation and allergy in clinical patch tests, and it later reaffirmed both. It found propanediol safe as used in 2018, and in 2012 concluded that citric acid and 20 alkyl citrate esters are safe as used. Citric acid and stearyl citrate are generally recognized as safe (GRAS) as direct food additives in the U.S., and stearyl citrate is readily broken down to stearyl alcohol and citric acid in dogs. Trioctyldodecyl citrate, which carries the same octyldodecyl groups, did not irritate or sensitize human skin, although undiluted it was a mild sensitizer in a mouse test.
In short, nothing about its building blocks suggests a concern at cosmetic use levels, but the finished polymer has not been independently assessed, and we found no data on whether any of it passes into the skin. Its close relative behenyl/octyldodecyl/propanediol citrate crosspolymer is in the same position.
Sources: European Commission CosIng: Stearyl/Octyldodecyl Citrate Crosspolymer; Cosmetic Ingredient Review: Final report on the safety assessment of citric acid, inorganic citrate salts, and alkyl citrate esters (2012); Journal of the American College of Toxicology (1985), via Cosmetic Ingredient Review: Final report on the safety assessment of stearyl alcohol, oleyl alcohol and octyl dodecanol; Cosmetic Ingredient Review: Quick reference table of safety conclusions (September 2022)
