TRANSEPIDERMAL MOISTURE LOSS 405 how these materials would perform under actual use conditions. Utilizing the thickness (use thickness) which a subject will use of a cosmetic material and the thickness-temperature variability matrix for transepidermal moisture loss rates, the fractional reduction in transepidermal moisture loss can be predicted under actual use conditions. Experiments which we have carried out with Vaseline brand petrolatum, 180 SUS Mineral Oil, 70 SUS Mineral Oil, and a typical emollient cream and lotion have shown that the materials such as mineral oil with the highest occlusivity may not be used for psychorheological reasons at a thickness which will provide advantageous fractional reductions in transepidermal moisture less. Conversely, emollient creams and lotions, while less occlusive in nature, have desirable psychorheological properties and will be used at use thick- nesses which will provide a significant reduction in transepidermal moisture loss rate. (Received May 3, 1973) REFERENCES (1) Blank, I. H., Factors which influence the water content of the skin, J. Invest. Derma- tol., 18, 433-40 (1952). (2) Blank, I. H., Further observations on factors which influence the water content ot the stratum comeurn, Ibid., 21, 259-69 (1953). (3) Blank, I. H., Mechanism of the action of agents used for the relief of dry skin, Proc. Sci. Sect. Toilet Goods Ass., 23, 19-23 (1955). (4) Blank, I. H., Action of emollient creams and their additives, J. Amer. Med. Ass., 164, 412-5 (1957). (5) Blank, I. H., Cosmetic versus topical therapeutic agents, J. Soc. Cosmet. Chem., 14, 433-41 (1963). (6) Gaul, L. E., and Underwood, G. B., Relation of dew point and barometric pressure to chapping of normal skin, J. Invest. Dermatol., 19, 9-19 (1952). (7) Gaul, L. E., Relation of dew point and barometric pressure to horny layer hydra- tion, Proc. Sci. Sect. Toilet Goods Ass., 40, 1-7 (1963). (8) Flesch, P., Chemical basis of emollient function in horny layers, Ibid., 40, 12-6 (1963). (9) Scheuplein, R. J., Mechanism of percutaneous absorption. II. Transient diffusion and the relative importance of various routes of skin penetration, J. Invest. Derma- tol., 48, 79-88 (1967). (10) Scheuplein. R. J., Properties ok the Skin as a Membrane, in Montagna, W., Pharma- cology and the Skin, Vol. XII, Advances in the Biology ok Skin, Appleton-Century Crofts Educational Div./Meredith Corp., New York, 1972, pp. 125-52. (11) Thiele, F. A. J., and Schutter, K., A new micro method for measuring the water- balance of the human skin. Salt crystal method. I. Apparatus, J. Invest. Dermatol, 39, 95-103 (1962). (12) van Cosselt, H. R. M., and Vierhaut, R. R., Registration of the insensible perspiration of small quantities of sweat, Dermatologica, 127, 255-8 (1963). (13) Spruit, D., and Malten, K. E., Epidermal water-barrier formation after stripping of normal skin, J. Invest. Dermatol., 45, 6-14 (1965). (14) Baker, H., and Kligman, A.M., Measurement of transepidermal water loss by elec- trical hygrometry. Instrumentation and responses to physical and chemical insults, Arch. Dermatol., 96, 441-52 (1967).

406 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS (15) (16) (17) (18) (19) (•o) (21) (22) (93) (24) (26) (27) (28) Frost, P., Weinstein, G., Bothwell, J. W., and Wildnauer, R., Ichtyosiform derma. toses. I. Studies of transepidermal water loss, Ibid., 98, 230 (1968). Goodman, A. B., and Wolf, A. V., Insensible water loss from a human skin as a func- tion of ambient vapor concentration, I. Appl. Physiol., 26, 203-7 (1969). Johnson, C., and Shuster, S., The measurement of transepidermal water loss, Brit. J. Dermatol. Suppl., 81, 40-6 (1969). Lamke, L. O., An instrument for estimating evaporation froin small skin surfaccs, Scand. J. Plast. Reconstr. Surg., 4, 1-7 (1970). Berube, G. R., Messinger, M., and Berdick, M., Measurement in vivo of transepi- dermal moisture loss, I. Soc. Cosmet. Chem., 22, 361-8 (1971). Powers, D. H., and Fox, C., A study of the effect of cosmetic ingredients, creams and ]orions on the rate of moisture loss from the skin, Proc. Sci. Sect. Toilet Goods Ass., 28, 21-5 (1957). Baker, H., Experimental studies on the influence of vehicles on percutaneous ab- sorption, J. Soc. Cosmet. Chem., 20, 239-52 (1969). Spruit, D., Interference of some substances with water vapor loss of human skin, Amer. Perf. Cosmet., 86, 27-32 (1971). Mezei, M., and Ryan, K. J., Effect of surfactants on epidermal permeability in rab- bits, J. Pharm. Sci., 61, 1329-31 (1972). Spruit, D., and Malten, K. E., Water vapour loss and skin barrier. An evaluation of some new findings, Trans. St. Iohn's Hosp. Dermatol. Soc., 57, 167-76 (1971). Grice, K., Sattar, H., Sharratt, M., and Baker, H., Skin temperature and transepi- dermal water loss, I. Invest. Dermatol., 57, 108-10 (1971). Barnett, G., Emollient Creams and Lotions, Chap. II, in Balsam, M. S., and Sagarin, E., Cosmetics: Science and Technology, 2nd Ed., Vol. I, Wiley-Inter- science, New York, 1972. Spruit, D., and Herweyer H. E. The ability of the skin to change its insensible perspiration, Dermatologica, 134, 364--70 (1967). Malin, H. V., Study of skin temperatures, Tex. State J. Med., 60, 376-8 (1964).