Final Report of the Safety Assessment of Isobutane, Isopentane, n-Butane, and Propane

Abstract

Isobutane, Isopentane, n-Butane, and Propane are low molecular weight alkanes, generally used in cosmetic products as aerosol propellants. Isobutane, Isopentane, n-Butane, and Propane were found not to be mutagenic in Ames Tests, both with and without metabolic activation. In eye irritation studies in rabbits, Isobutane caused very slight iridial and corneal irritation. Both n-Butane and Propane were mildly to moderately irritating to the skin of rabbits. Isobutane, at 22% in a hair spray, was not toxic to rabbits in an acute inhalation study. Subchronic inhalation of Isobutane and Propane produced no toxicity in two animal species. Acute inhalation of Isopentane, n-Butane, and Isobutane was shown to sensitize the myocardium of test animals to epinephrine. No significant systemic abnormalities occurred in human subjects during an acute inhalation study of Isobutane, n-Butane and Propane. Propane caused no human mucosal irritation. A Propane-Isobutane mixture, present at 64.5% and 70.0% in two different cosmetic formulations, caused no skin irritation in 125 human volunteers. On the basis of the available information presented herein, Isobutane, Isopentane, n-Butane and Propane are considered safe as cosmetic ingredients under present conditions of concentration and use.