MILDNESS ASSESSMENT TECHNIQUES 193 skin, mimicking most normal-use conditions. Results from the flex wash method, however, are dependent on product interaction with the surface and lower layers of the skin. While there are instances where this type of exposure could occur during home use (for example, wound cleansing or product use on sun-damaged skin), this certainly cannot be considered the norm. Thus, while the forearm wash and flex wash methods both provide measures of product mildness, these measures are based on different exposure models. Given the consistency of the forearm wash and home-use data gener- ated with both soap and syndet bars, the forearm wash exposure model appears to be more relevant to actual consumer use conditions than is the flex wash exposure model. SUMMARY The mildness of several personal cleansing products was measured using two exaggerated wash protocols--a forearm wash method and a flex wash method. The forearm wash method more accurately predicted home-use results when soap bars were tested. Both exaggerated methods yielded similar mildness pictures when syndet bars were tested however, the forearm wash method was more discriminating. Experiments designed to measure implement effects show that the towel used in the forearm wash method induces minimal damage to the stratum corneum, while damage induced in the flex wash method is due to both implement and product effects. The results indicate that while both exaggerated methods provide a measure of product mildness, the methods are based on different models of consumer use and exposure. REFERENCES (1) P. J. Frosch and A.M. Kligman, The soap chamber method for assessing the irritancy of soaps, J. Am. Acad. Dermatol., 1, 35-41 (1979). (2) P. J. Frosch, "Irritancy of Soaps and Detergent Bars," in Principles of Cosmetics for the Dermatologist, P. H. Frost and S. T. Horwith, Eds. (C. V. Mosby, St. Louis, 1982), pp. 5-12. (3) G. Sauermann, A. Doerschner, U. Hoppe, and P. Wittern, Comparative study of skin care efficacy and in-use properties of soap and surfactant bars, J. Soc. Cosmet. Chem., 37, 309-327 (1986). (4) B. Komp, Skin compatibility tests--Importance in skin cleansing product development, Cosmet. Toiletr., 102, 89-94 (1987). (5) B. Komp and A. K. Reng, Developing ether sulfate-free surfactant formulations, Cosmet. Toiletr., 104, 41-45 (1989). (6) M. F. Lukacovic, F. E. Dunlap, S. E. Michaels, M. O. Visscher, and D. D. Watson, Forearm wash test to evaluate the clinical mildness of cleansing products,J. Soc. Cosmet. Chem., 39, 355-366 (1988). (7) D. D. Strube, S. W. Koontz, R. I. Murhata, and R. F. Theiler, The flex wash test: A method for evaluating the mildness of personal washing products, J. Soc. Cosmet. Chem., 40, 297-306 (1989).

J. Soc. Cosmet. Chem., 43, 195-206 (July/August 1992) Absence of effects of dimethicone- and non-dimethicone-containing shampoos on daily hair loss rates PREYA KULLAVANIJAYA, PIMONPUN GRITIYARANGSAN, PRAVIT BISALBUTRA, RANOKVALAI KULTHANAN, and CAROLINE W. CARDIN The Institute of Dermatology, 420/7 Rajvithi Road, Bangkok 10400, Thailand (P.K., P.G., P.B., R oK. ), and The Procter & Gamble Company, Sharon Woods Technical Center, Cincinnati, OH 45241 (C. W. C. ). Received June 15, I991. Synopsis Shampoos are designed for cleansing and conditioning hair. During normal use, these products come in contact with hair and skin in very diluted concentrations for very short periods of time and are generally recognized as safe by dermatologists (1). Despite the above, when consumers change hair care products, they have a tendency to be more attentive to the conditions of their hair and scalp and to attribute any perceived change, especially any seen as negative, to the new product. One issue that is always of concern is hair loss or, in consumer terms, hair fall occurring shortly after switching to a new shampoo. To understand why consumers associate hair fall to the use of shampoo, a clinical study was conducted to examine daily hair loss rates in a large population of 404 healthy Thai females using either a dimethicone- or non-dimethicone-containing cosmetic shampoo for a period of six weeks. In addition, perceptual infor- mation was obtained on hair fall, hair health, and causes of hair shedding and hair loss. While published estimates of average daily hair loss rates range from 34.8 to 180 hairs (2-7), this study found mean hair loss rates ranging from 28 to 35 per day in a population of 404 healthy Thai females over a period of six weeks. These daily hair loss rates are consistent with reported findings in the normal population (2-3,8). There were no significant differences in the total, telogen, anagen, and broken hair loss rates between the three different shampoo groups. As expected, significantly higher hair loss rates were noted on shampoo versus non-shampoo days. No differences were noted in the perception of hair fall in subjects using the three different shampoos. In this study, we determined why consumers associate hair fall with the use of shampoo. While subjects perceived hair fall as a natural process in hair regrowth and therefore unrelated to hair thinning or balding, they attributed any increased hair fall from grooming to the use of unsuitable shampoos, more so than to the grooming processes of combing/brushing or to chemical modification. Other factors known to contrib- ute to abnormal hair loss were not perceived by the subjects as likely causes of hair fall. 195