Final Report On the Safety Assessment of Iodopropynyl Butylcarbamate (IPBC)

Abstract

Iodopropynyl Butylcarbamate (IPBC) functions as a preservative in a wide variety of cosmetic formulations. Although concentrations as high as 0.1% have been reported, most applications appear to require this preservative at less than 0.0125%. IPBC readily penetrates through the skin. The average acute oral LD50 in rats is 1.47 g/kg. Rats fed IPBC for 4 weeks had increased liver weights and decreased plasma cholinesterase activity, and rats fed IPBC for 13 weeks had transient behavior alteration, increased liver weights, hepatocyte enlargement, stomach lesions, and decreased weight gain. Rats administered IPBC as dusts and liquid aerosols had labored breathing—lung edema, emphysema, and reddened lungs were observed after exposure. Dermal irritation, but no evidence of skin sensitization, was seen in animal studies. At concentrations of 0.5%, IPBC caused iritis and conjunctival irritation in rabbit eyes, but exposure to concentrations up to 0.015% produced only slight conjunctival redness. IPBC was not genotoxic, with or without metabolic activation. No evidence of carcinogenic potential was found in a 104-week chronic oral toxicity study using rats. Reductions in weight gain were observed, along with inflammation of the nonglandular stomach and lesions in the submaxillary salivary gland. In reproductive and developmental toxicity studies using rats and mice, IPBC had no significant effect on fertility, reproductive performance, or on the incidence of fetal malformations. IPBC was found to be mildly irritating, but not sensitizing in clinical testing. At concentrations up to 0.1%, IPBC was not comedogenic in clinical tests. Given the acute inhalation toxicity observed in animals, the potential for mild irritation, and the absence of any data on comedogenicity at concentrations higher than 0.1 % in clinical tests, the Expert Panel concluded that IPBC is safe as a cosmetic ingredient at concentrations ≤0.1 %, but that it should not be used in products intended to be aerosolized.