SORPTION BY STRATUM CORNEUM 553 REFERENCES (8) (9) (lC) (11) (12) (13) (1) R. B. Kundsin and C. W. Walter, Investigations on adsorption of benzalkonimn chloride U.S.P. by skin, gloves, and sponges, Arch. Surg. Chicago, 75, 1036-42 (1957). (2) M. E. Cinn, S. C. Dunn, and E. Jungermann, Contact angle studies on viable human skin: II. Effect of snrfactant ionic type in pretreatment, J. Amer. Oil Chem. Soc., 47, •c3•5 (197()). (3) F. S. Cooperman, Prr•tein hydrolysatcs as skin moisturizers, Amer. Cosmet. Perf., 87, ( 5-7 (1972). (4) E. D. Goddard, J. A. Faucher, R. J. Scott, and M. E. Turney, Adsorption of Polymer JR on keratinous surfaces, J. Soc. Cosmet. Chem., 26, 539-50 (1975). (5) F. W. Stone and J. M. Rutherford, U.S. Pat. 3,472,840, Oct. 14, 1969. (6) W. Broxvn, Hydroxyethyl Cellulose, a study of its macromolecular properties in •sol,,tion, Ark. Kemi, 18, 227-83 (1961). (7) E. J. Singer, P. C. Wegmann, M. D. Lehman, M. S. Christensen, and L. J. Vinson, Barr er development, nltrastructure, and sulfhydryl content of the fetal epidermis, y. Soc. Cosmet. Chem., 22, 119-37 (1971). J. Crank, The mathematics of diffusion, Oxford Univ. Press, Oxford, England, 1956, Pp. 18-9. A. V. Hill, D•ffusion of oxygen and lactic acid through tissues, Proc. Roy. Soc. Set. B., 104, 39-96 (1928). O. Kedem and A. Katchalsky, Diffusion of polyelectrolytes in salt-free solutions, .I. Polym. Sci., 15, 321-34 (1955). D. E. Loveday, An in virtro method for studying percutaneous absorption, J. Soc. Cosmet. Chem., 12, 224-39 (1961). R. J. Scheuplein, Mechanism of Percutaneous Absorption II, J. Invest. Dermaiol., 48, 79-88, (1967). E. D. Goddard, T. S. Phillips, and R. B. Hannan, Water soluble polymer-surfactant interaction I., J. Soc. Cosmet. Chem., 26, 461-75 (1975).

]. Soc. Cosmet. Chem., 27, 555-558 (November 1976) Diffusion Theory Analysis of Transepidermal Water Loss Through Occlusive Films EUGENE R. COOPER, Ph.D. and BARRY F. VAN DUZEE, Ph.D.* Synopsis: Composite membrane DIFFUSION THEORY is applied to TRANSEPIDER- MAL WATER LOSS measurements across skin treated with OCCLUSIVE FILMS. Since the permeability of stratum corneum increases with hydration, it is shown that certain films can be applied to skin to increase transepidermal water loss. Thus, even increase in trans- epidermal water loss can indicate that the film is l•ydrating the skin quite well. INTRODUCTION Cosmetic chemists have long been concerned with enhancing the barrier properties of the skin. The benefits derived from an intact resistive barrier range from enhanced skin condition to prevention of environmental insult from gases, fumes, dirt, and microbes. One of the main advantages which results from the application of an occlusive cosmetic barrier is enhanced skin condition (1-3). As a result, there has been an effort to find materials which reduce the transepidermal water loss (TWL) of skin and which might be incorporated into cosmetic for- mulations (4). This search has been conducted by measuring the water loss through skin in vivo before and after application of a potential occlusive agent. However, this method of screening occlusive agents may eliminate some compounds which are actually good hydrating agents. Application of 3 mg/cm 2 of petrolatum to the surface of skin results in an immediate decrease in the rate of insensible water loss followed by an in- crease in the rate to a value higher than the original one after about 3 h. *The Procter & Gamble Company, Miami Valley Laboratories, Cincinnati, Ohio 45247. 555