IRRITATION POTENTIAL OF PERSONAL CLEANSERS 75 product. The eight-site FCAT design described in this work is not suitable for mea- suring these attributes, since the application areas are too small to allow accurate self-assessment of skin condition. In these cases, a four-site design that divides each forearm into upper and lower halves may be used. The four-site design retains the benefits previously noted for the eight-site design and provides a large enough appli- cation area for subjects to assess their skin condition. A second example of a situation requiring an experimental design modification is one in which products are intended to improve some aspect of skin condition, such as dry skin appearance. In this case, the design modification involves conducting the wash proce- dure on the legs, where it is referred to as a leg controlled application technique, or LCAT. Since the legs are naturally drier than the forearms, average scores at baseline lie nearer the middle of the visual dryness scale, providing additional "room" for skin improvement during treatment. As with the forearm model, the LCAT can be run as a four- or eight-site design, depending on the number of test products involved and the type of endpoint measures desired. CONCLUSIONS The forearm controlled application technique, or FCAT, provides an efficient means to estimate the relative irritation potential of personal cleansers. The method provides greater precision and sensitivity than typical two-sample tests and minimizes confound- ing effects due to biological diversity. The FCAT is robust, that is, it is able to discriminate the relative irritation potential of personal cleansers under a wide variety of test conditions. Further, the method has been shown to provide relative mildness rankings across a range of product compositions that are consistent with expectations based on formula differences. REFERENCES (1) M. F. Lukacovic, F. E. Dunlap, S. E. Michaels, M. O. Visscher, and D. D. Watson, Forearm wash test to evaluate the mildness of cleansing products, J. Soc. Cosmet. Chem., 39, 355-366 (1988). (2) M. O. Visscher, S. E. Michaels, and B. H. Keswick, A clinical test method for assessing the irritation potential of skin cleansing products. 48th Annual Meeting of the American Academy of Dermatology, San Francisco, December 2-7, 1989. (3) B. H. Keswick, K. D. Ertel, and M. O. Visscher, A comparison of exaggerated and normal use techniques for assessing the mildness of personal cleansers, J. Soc. Cosmet. Chem.,43, 187-193 (1992). (4) J. A. Faucher, E. D. Goddard, R. B. Hannan, and A.M. Kligman, Protection of the skin by a cationic cellulose polymer, Cosmet. Toiletr., 92, 39-44 (1977). (5) P. Pugliese, G. Hines, and W. Wielinga, Skin protective properties of a cationic guar derivative, Cosmet. Toiletr., 105, 105-1! ! (1990). (6) P. T. Sharko, R. I. Murahata, J. J. Leyden, and G. L. Grove, Arm wash with instrumental evalu- ation--A sensitive technique for differentiating the irritation potential of personal washing products, J. Dermoclinical Eval. Soc., 2, 19-27 (1991). (7) V. Rogiers, M.P. Derde, G. Verleye, and D. Roseeuw, Standardized conditions needed for skin surface hydration measurements, Cosmet. Toiletr. 105, 73-82 (1990). (8) H. Tagami, "Hardware and Measuring Principle: Skin Conductance," in Bioengineering of the Skin.' Water and the Stratum Corneum, P. Eisner, E. Berardesca, and H. I. Maibach, Eds. (CRC Press, Boca Raton, FL, 1994), pp. 197-204. (9) B. M. Morrison Jr., S. W. Babulak, D. D. Scala, and F. A. Simion, A comparison of instrumental

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