200 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS (34) (35) (36) (37) (38) (39) (40) (41) (42) (43) (44) (45) (46) (47) (48) G. Imokawa, S. Akasaki, Y. Minematsu, and M. Kawai, Importance of intercellular lipids in water- retention properties of the stratum corneum: Induction and recovery study of surfactant dry skin, Arch. Dermatol. Res., 281, 45-51 (1989). A. W. Fulmer and G. J. Kramer, Stratum corneum lipid abnormalities in surfactant-induced dry scaly skin, J. Invest. Dermatol., 86, 598-602 (1986). M. Fartasch, T. L. Diepgen, and O. P. Hornstein, Morphological changes of epidermal lipid layers of stratum corneum in sodium lauryl sulfate induced dry skin: A functional and ultrastructural study, J. Invest. Dermatol., 96, 617 (1991). M. Rieger, Skin lipids and their importance to cosmetic science, Cosmet. Toiletr., 102(7), 36-49 (1987). A. W. Rawlings, A. Watkinson, J. Rogers, H. J. Mayo, and I. R. Scott, Abnormalities in stratum corneum structure, lipid composition, and desmosome degradation in soap-induced winter xerosis, J. Soc. Cosmet. Chem., 45, 203-220 (1994). K. P. Ananthapadmanabhan, M. Misra, K. K. Yu, and M.P. Aronson, Unpublished results, Uni- lever Research, 1996. S. Mukherjee, S. Prowell, K. Hoyberg, R. Gursky, M. Davies, C. L. Meyers, K. P. Ananthapad- manabhan, and M. Aronson, Cleanser induced structural changes in corneum. Presented at the 53rd Annual Meeting of the American Academy of Dermatology New Orleans, February 1995. M. Takahashi, M. Aizawa, K. Miyazawa, and Y. Machida, Effects of surface active agents on stratum corneum cell adhesion,"J. Soc. Cosmet. Chem., 38, 21-28 (1987). T. Egelrud and A. Lundstrom, The dependence of detergent induced cell dissociation in non-palmo- plantar stratum corneum on endogenous proteolysis, J. Invest. Dermatol., 90, 456-459 (1992). C. S. King, P. J. Dykes, and R. Marks, Preparation and characterization of the nonionic detergent soluble proteins of human stratum comeum, J. Invest. Dermatol., 79, 297-302 (1982). L. D. Rhein, C. R. Robbins, K. Fernee, and R. Cantore, Surfactant structure effects on swelling of isolated human stratum corneum, J. Soc. Cosmet. Chem., 37, 125-139 (1986). J. D. Middleton, The mechanism of water binding in stratum corneum, Brit. J. Dermatol., 80, 437-450 (1968). J. D. Middleton, The mechanism of action of surfactants on the water binding properties of isolated stratum corneum, J. Soc. Cosmet. Chem., 20, 399-412 (1969). E. D. Goddard, Substantivity through cationic substitution, Cosmet. Toiletr., 102, 71-78 (1987). R. I. Murahata and M. P. Aronson, The relationship between solution pH and clinical irritancy for carboxylic acid-based personal washing products, J. Soc. Cosmet. Chem., 45, 239-246 (1994).

j. Soc. Cosmet. Chem., 47, 201-211 (July/August 1996) Photochemical alterations in human hair. Part II1: Investigations of internal lipids EDO HOTING, Hans Schwarzkopf GmbH, D-22763 Hamburg, Germany, and MONIKA ZIMMERMANN, Deutsches Wollforschungsinstitut an der RWTH Aachen e.V., D-52062 Aachen, Germany. Accepted for publication October 3, 1996. Synopsis Investigations of the internal lipids of human hair were performed after irradiation with simulated sunlight (global) or specific ranges of UV-B, UV-A, visible light, or IR. A mild extraction method and quantitative determination of internal lipids separated by thin-layer chromatography (TLC) allows the detection of significant differences between the photochemical response of black and blond hair. Using the example of cholesterol and free fatty acids, it could be demonstrated that the visible range of sunlight destroys the internal lipids to a considerably higher extent than exposure to UV-B and UV-A ranges. The photochemical destruction of lipids is largely retarded by the pigment eumelanin. INTRODUCTION The inner or internal lipids (IL) of keratinized fibers, together with globular proteins, form a cell membrane complex (CMC) that connects the keratinous cuticle and cortex cells to a uniform tissue complex. Human hair contains 1.9-5 % (1,2) and wool fibers only 0.7-1.2% IL (3). Despite this low amount, the cell membrane lipids are very important as they make possible a continuous pathway of diffusion into the fiber (4-6). Furthermore, according to recent investigations on human hair, a correlation exists between the amount of IL and the moisture content in the hair (7). A reduction of the amount of lipids by solvent extraction (8) and oxidative damage during chlorine bleaching of wool (9) or during permanent waving of hair (2) favor the diffusion of foreign materials into the fiber (10). It is known that irradiation of human hair with sunlight destroys, via photooxidation, melanin (11-13) as well as protein components (13-16), which destruction is accom- panied by clear alterations of mechanical properties (17-19). However, up to now the photochemically induced modification of the IL has not been investigated. In wool research important indications of the photochemical lability of IL have been published (20,21). The aim of this investigation is to gain basic knowledge about the influence of sunlight 201