Final Report of the Cosmetic Ingredient Review Expert Panel on the Safety Assessment of Polyisobutene and Hydrogenated Polyisobutene as Used in Cosmetics1

摘要

Polyisobutene and Hydrogenated Polyisobutene are homopoly-mers of isobutene. These ingredients are produced in a wide range of molecular weights. Polybutene is a chemically related cosmetic ingredient previously determined to be safe as used in cosmetic products. Polyisobutene is used in cosmetic products as a binder, film former, and nonaqueous viscosity-increasing agent. Hydrogenated Polyisobutene functions as a skin-conditioning agent? emollient and nonaqueous viscosity-increasing agent with a wide range of uses in cosmetic formulations. The estimated octanol water partition coefficient for Hydrogenated Polyisobutene and Polybutene is log Kow of 13.27 and the estimated water solubility was 5.6 X 10~3 ng/L for Hydrogenated Polyisobutene and Polybutene. Acute oral toxicity testing demonstrated no effects other than lethargy in one rat study. The oral LD50 was >5.0 g/kg in rats. No short-term or subchronic animal toxicity data were available. A 2-year chronic oral toxicity study of Polybutene revealed no gross or microscopic pathological changes, and no changes in body weights or food consumption, hematological results, urology, or tumor formation that could be correlated with Polybutene ingestion, except that in the 20,000 ppm group, three out of six males that died between weeks 17 and 24 exhibited hematuria.