Final Report On the Safety Assessment of Sodium Alpha-Olefin Sulfonates

Abstract

Sodium C14-16 OlefinSulfonate, Sodium C12-14 Olefin Sulfonate, Sodium C 14-18 Olefin Sulfonate, and Sodium C16-18 Olefin Sulfonate are the Sodium α-Olefin Sulfonates used in cosmetics as surfactant-cleansing agents. The highest concentration reportedly is 16% in shampoos and bath and shower products. These ingredients are a mixture of long-chain sulfonate salts prepared by sulfonation of α-olefins of various carbon chain lengths noted as subscripts. In the manufacture of these ingredients, delta and gamma sultones may be produced. Sodium α-Olefin Sulfonates are poorly absorbed through normal skin, but are significantly absorbed through damaged skin. Acute oral LD50 values were 1.3 2.4g/kg in rats and 2.5-4.3 g/kg in mice. Short-term toxicity studies using rats showed no consistent effects, even with exposures in the 0.5-1.0 g/kg range. Concentrations above 10% produced moderate ocular irritation and a concentration of 5% produced mild ocular irritation in rabbits. In reproductive and developmental toxicity studies, fetal abnormalities were noted, but only at doses that were maternally toxic. Genotoxicity data were mostly negative and oral and dermal carcinogenicity studies were negative. Various animal and clinical studies found irritation and sensitization. Sensitization was attributed to low level gamma sultone residues. Because gamma sultones are demonstrated sensitizers at very low levels, it was concluded that any product containing Sodium α-Olefin Sulfonates should have very little gamma sultone residues. The gamma sultone levels should not exceed 10 ppm for saturated (alkane) sultones, 1 ppm for chloro-sultones, and 0.1 ppm for unsaturated sultones. Sodium α-Olefin Sulfonates are otherwise considered safe for use in rinse-off products. Based on concerns about irritation, were Sodium α-Olefin Sulfonates to be used in leave-on products, it was concluded that concentrations should not exceed 2% for such uses.