j. Soc. Cosmet. Chem., 43, 187-193 (July/August, 1992) Comparison of exaggerated and normal use techniques for assessing the mildness of personal cleansers B. H. KESWICK, K. D. ERTEL, and M. O. VISSCHER, The Procter & Gamble Company, 11520 Reed Hartman Highway, Cincinnati, Ohio 45241. Received December 31, 1991. Synopsis A variety of exaggerated-exposure wash techniques have been used to evaluate the mildness of personal cleansing products in lieu of clinical evaluation during normal use. This study compares two exaggerated methods, a forearm wash method and a flex wash method, to home-use studies to determine how well the exaggerated methods approximate ad lib usage. The results indicate that the forearm wash method is a better predictor of product mildness under home-use conditions when soap bars are used. Both exaggerated methods yield similar mildness pictures when syndet bars are used, although the forearm wash method is more discriminating. The flex wash implement (sponge) induces greater damage to the stratum corneum than does the forearm wash implement (towel). However, this does not account for the total damage observed when product is applied in the flex wash method. A significant amount of damage is apparently due to product reaching and interacting with lower layers of the skin once the barrier's integrity has been compromised by the sponge. The results indicate that the forearm and flex wash methods are based on different exposure models, and that the model on which the forearm wash is based is more predictive of actual consumer use conditions than is the model on which the flex wash is based. INTRODUCTION An important characteristic of bar soap products is their mildness, as this is often a major determinant of consumer acceptance. Methods originally developed to assess personal cleanser mildness, such as patch and chamber tests, have been criticized because they do not reflect consumer usage patterns (1-3). More recently, exaggerated protocols (2-7) have been developed to mimic consumer-use conditions and allow mildness pre- dictions to be made in a relatively short time. The following work examines two five-day exaggerated wash protocols based on published procedures--a flex wash method (7) and a forearm wash method (6). Mildness results obtained by each method are compared to results obtained in home-use studies to see how well the exaggerated wash protocols predict results generated under actual use conditions. EXPERIMENTAL STUDY POPULATION Healthy male and female volunteers were recruited as test subjects. All prospective 187

188 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS subjects were screened prior to enrollment to assure that they had no history of sensi- tivity or allergy to soap or detergent products, and that they had not used prescribed anti-inflammatory or antibiotic drugs for at least three weeks prior to study start-up. Female subjects were also screened to assure that they were not pregnant or lactating. Informed consent was obtained from all subjects prior to their being issued product or beginning treatments. MATERIALS Test products were either commercially available cleansing bars or cleansing bar pro- totypes. The major formula components of the test products are reported in Table I. Products provided to the test laboratories were coded such that subjects and test site personnel, including trained graders, were unaware of product identities. Masslinn © towels (Chicopee Mills, New Brunswick, NJ) were used as wash implements in the forearm wash method JAECE Identi-Plug © (size D, JAECE Industries, Inc., Ton- awanda, N-Y) or Cerafoam (1.75" diameter, Wilfred Heath Ltd., Stoke-On-Trent, England) sponges were used as wash implements in the flex wash method. TEST METHODS All studies were conducted at independent testing laboratories. The home-use, forearm wash, and flex wash studies were run during the period from winter to early spring. The flex wash implement study was run in late summer however, this method is reported to yield results that are free from seasonal variation (7). The numbers of subjects enrolled in the exaggerated method studies were consistent with those specified in the literature the number of subjects enrolled in each of the home-use studies was based on prior testing experience with similar products. Subjects in the home-use studies were randomly assigned a single product to take home and use for four (soap bars) or twelve (syndet bars) week periods. Subjects periodically returned to the test facility for a visual evaluation of the redness and dryness induced by product usage. The exaggerated studies were run as paired comparisons, with a single product randomly assigned for use on each arm. Key features of the exaggerated wash methods are summarized in Table II. Table I Major Formula Components of the Test Products Used in These Studies Test code Major formula components Sodium tallowate, sodium cocoyl isethionate, sodium cocoate, stearic acid, sodium iesthionate, coconut fatty acid Soap (sodium tallowate and sodium cocoate or palm kernalate types), sodium cocoglyceryl ether sulfonate, glycerin, coconut or palm kernel acid, polyquaternium-7, guar hydroxypropyltrimonium chloride Sodium alkylglyceryl ether sulfonate, sodium lauroyl sarcosinate, sodium soap, stearic acid, lauric acid, Polyquarternium-7, Polyquarternium-10 Sodium cocoyl isethionate, stearic acid, sodium tallowate, sodium isethionate, coconut acid, sodium stearate, sodium dodecylbenzenesulfonate, sodium cocoate or sodium palm kernelate