J. SOC. COSMET. CHEM., 28, 243-257 (MAY 1977) Some aspects of the stratum corneum-organic solvent system A. F. EL-SHIMI* a•d H. M. PRINCEN Lever Brothers Company, 45 River Road, Edgewater, New Jersey 07020. Received March I5, I976. Synopsis A limited study of the SORPTION, DESORPTION, and DIFFUSION behavior of some ORGANIC VAPORS (benzene and toluene) in intact STRATUM CORNEUM has been carried out, and the results compared to WATER VAPOR. The effect of treating the comeurn in a mixture of ORGANIC SOLVENTS (chloroform-methanol) followed by water extraction, on the water vapor sorption, desorption and diffusion characteristics has been assessed. Scanning electron microscopy (SEM), was also used to examine the structural changes in the comeurn resulting from the organic solvents-water treatment. The shape of the benzene and toluene sorption ISOTHERMS was found to be compatible with type II in the BET classification. The diffusion process of the organic vapors in the corneum is much faster than that of water vapor. An increase by 3 orders of magnitude in the value olD, (intrinsic &flusion coefficient) has been observed as the concentration of organic vapor increases in the comeurn. Sequential treatment of GUINEA PIG comeurn in organic solvent and water resulted in a marked decrease in the water vapor sorption capacity in the high humidity range. The initial portions of the water vapor sorp- tion isotherms on the treated and intact corneum are the same (up to about 50 per cent RH). The diffusion of water vapor in the treated comeurn is 10 times as fast as in the intact comeurn. INTRODUCTION Th• hydradon of stratum comeurn has been the subject of a number of investigations (1-5). We have recently examined in detail the sorption, desorption, and diffusion be- havior of water vapor in a number of keratinous materials including stratum corneum obtained from excised human skin, guinea pig and neonatal rat corneum, and human hair (6-7). In this paper, we present the results of a limited investigation into the sorption, desorp- don, and diffusion characteristics of benzene and toluene vapors in human stratum cor- neum, and compare these to the results obtained with water vapor. We have also examined the effect of solvent damage (chloroform/methanol 2:1) on the water vapor sorption and diffusion in guinea pig stratum corneum in an attempt to identify the role of the physical structure of the corneum. *Present address: The Clorox Company, Technical Center, P.O. Box 493, Pleasanton, CA 94566. (To whom all future correspondence should be addressed.) 243