368 JOURNAL OF COSMETIC SCIENCE ACKNOWLEDGMENTS The authors wish to thank L. Gauchet for her efforts in the realization of the tests, and D. Saint-L•ger, C. Bouillon, D. Good, and B. Hibon for reviewing the manuscript. The authors wish to express their thanks to J. Scot for the restoration of the device system and to J. C. Garson and S. Vicic for their large contribution to the preliminary tests. REFERENCES (1) C. R. Robbins, Chemical and Physical Behavior of Human Hair (Van Nostrand Reinhold, New York, 1979), pp. 153-207. (2) J. A. Swift, The cuticle controls bending stiffness of hair, J. Cosmet. Sci., 51, 37-38 (2000). (3) A. N. Parbhu, W. G. Bryson, and R. Lal, Disulphide bonds in the outer layer of keratin fibers confer higher mechanical rigidity: Correlative nano-indentation and elasticity measurements with an AFM, Biochemistry, 38, 11755-11761 (1999). (4) R.M. Khayatt, and N.H. Chamberlain, The bending modulus of animal fibers, J. Text. Imt., 39, 185-197 (1948). (5) H. M. Elder, The tensile, compresslye and bending moduli of some monofilament materials,J. Text. Inst. 57, T8-14 (1966). (6) G.V. Scott, and C. R. Robbins, Stiffness of human hair fiber, J. Soc. Cosmet. Chem., 29, 469-485 (1978). (7) J. D. Owen, The application of Searle's single and double pendulum method to single fiber rigidity measurements, J. Text. Inst., 56, 329-339 (1965). (8) J.-C. Garson, M. Vidalis, P. Roussopoulos and J.-L. Ldv&que, Les propri6tds vibratoires transversales des fibres de kdratine. Influence de l'eau et d'autres agents, Int. J. Cosmet. So, 2, 231-241 (1980). (9) S. P. Timoshenko and J. N. Goodier, Theory of Elasticity, Third Edition (McGraw Hill International Editions, 1970), pp. 284-288. (10) J. A. Swift, Some simple theoretical considerations on the bending stiffness of human hair, J. Cosmet. Sci., 17,245-253 (1995). (11) B. M. Chapman, The bending stress-strain properties of single fibers and the effect of temperature and relative humidity, J. Text. Inst., 64, 312-327 (1973). (12) C. Zviak, Science des traitements capillaires (Edition Masson, 1988), pp. 40-44. (13) F.J. Wortmann, Bending relaxation properties of human hair and permanent-waving performance,J. Cosmet. Chem., 41, 123-139 (1990).

j. Cosmet. Sci., 52, 369-375 (November/December 2001) A modified cup scrub method for assessing the antibacterial substantivity of personal cleansing products WARD L. BILLHIMER, CINDY A. BERGE, JAN S. ENGLEHART, GAYLE Y. RAINS, and BRUCE H. KESWICK, The Procter O Gamble Company, Cincinnati, OH 45241. Accepted for publication August 15, 2001. Synopsis An improved in vivo method for evaluating the antibacterial substantivity or residual effectiveness of bar soaps and other personal cleansing products is presented. The effectiveness of an antibacterial bar soap containing 1.5 % 3, 4, 4'-trichlorocarbanilide (TCC) versus its soap vehicle was evaluated under simulated conditions considered optimal for bacterial growth, proliferation, and possible infection. A washout period to clear the skin of any antimicrobial agents previously used was followed by a treatment period in which the subjects washed one of their forearms with the antibacterial soap and the other forearm with the soap vehicle. Either immediately or 24 hours following the final wash, three test sites on both forearms were inoculated with S. aureus and occluded with Hill Top Chamber © patches. At intervals of 30 minutes, two hours and five hours, the patches were removed. The bacteria on the skin were harvested using the Williamson-Kligman scrub technique (1,2) to determine the number of surviving CFUs at each time period. The method successfully demonstrated that sufficient TCC had remained on the skin for 24 hours after the final wash to effectively inhibit the growth ofS. aureus on the skin for as long as five hours after inoculation. INTRODUCTION Skin infections due to Staphylococcus aureus such as folliculitis, furuncles, carbuncles, impetigo, and wound infections, are recognized as a common health problem (3,4). The regular use of an antibacterial soap for personal cleansing has the potential to control the growth of S. aureus on the skin and to aid in the prevention of these diseases. The surfactant base removes bacteria from the skin while depositing an active ingredient that can help to control the regrowth of remaining organisms and help to prevent the colonization of other transient, potentially pathogenic organisms. Demonstrating the disease prevention potential of an antibacterial soap under consumer conditions requires significantly large numbers of subjects and extensive amounts of time, and it is often financially prohibitive. Instead, it is useful to demonstrate the benefits of washing with antibacterial soaps by using controlled clinical methods designed to demonstrate the differences between plain soap and water (placebo) and the product containing an antibacterial agent. 369