J. Soc. Cosmetic Chemists, 19, 611-626 (Aug. 19, 1968) Influence of an Antibacterial Soap on Various Effluents from Axillae A. DRAVNIEKS, Ph.D.,* B. K. KROTOSZYNSKI, Ph.D.* W. E. LIEB, M.S.,p and E. JUNGERMANN, Ph.D. p Synopsis--The effects of an antibacterial soap on the density of axillary bacterial population, primary and secondary odor intensity, and water production were investigated over a period of several weeks on four subjects kept on a controlled skin-care regime. The soap contained 0.75% hexachlorophene and 0.75% 3,4,4•-trichlorocarbanilide. The antibacterial soap significantly depressed the bacterial population and the odor intensities from both sources. The soap had no systematic influence on the rate of water production. A thesis was ad- vanced to explain the origin of odor and the factors controlling its intensity. Novel tech- niques were used to collect axillary effluents and to measure odor-intensity from gas chro- matographically-resolved primary vapors. INTRODUCTION Antibacterial soaps are used to control odors emanating from the human axillary vault and from adjoining garments. Odor control is effected by the inhibitory action of the active soap additive on the growth of the odor-producing bacteria. The development of effective medicated soaps requires an objective method for evaluation of their antibacterial performance and their odor control. The performance of medicated soaps is presently investigated by either bacteriological methods or by a purely subjective method utilizing a panel of expert judges. It is commonly assumed that control of bacterial activity produces a corresponding reduction in odor level. This assumption is questionable * Olfactronics and Odor Sciences Center, IIT Research Institute, 10 West Thirty-fifth Street, Chicago, Ill. 60616. • Research and Development Department, Armour Grocery Products Co., 100 South Wacker Drive, Chicago, Ill. 60606. 611

612 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS for several reasons. First, odor is generated primarily by the action of microorganisms on apocrine sweat, while the usual bacterial counts evaluate the bacterial population density without reference to the con- centration of apocrine sweat. Second, odorous vapors are generated in primary sites (on the skin and the hair of axillae) as well as in secondary sites (in the axillary portions of garments), while bacterial counts relate to the primary sites only. Third, we have found (1) that when non- medicated soap is used for bathing, the bacterial density varies posi- tively with water generation in axillae, while the odor intensity from the primary sites decreases. Under the same conditions, individuals differ in the relation of the primary to secondary odors, and that a lower bac- terial count or a slower water generation could explain a decreased in- tensity of the secondary odors in some subjects. The most probable mechanism for the decrease of primary odor intensity with higher sweat- ing rates and higher bacterial counts is a decrease in the apocrine sweat concentration on skin when the eccrine sweat production and, conse- quently, water vapor generation, increase. Therefore, the actual rela- tionship between bacterial population and odor intensity rated by an outside observer can be much more involved than appears at first. Antibacterial agents are being added to contemporary soaps to de- crease the bacterial population density on skin including axillae. Por- tions of the agents are transferred with sweat and skin debris to clothing and can inhibit odorous vapor generation there. Therefore, among the effects observed is a reduction in primary odor and in secondary odor. Although the above observations hold in general, their quantitative interrelation is not well known. Recently, Dravnieks and Krotoszynski (2, 3) have developed techniques for (a) evaluation of odor intensities via gas chromatograms of odorous vapors and (b) vapor collection from axillary vaults. These techniques permit a more quantitative assess- ment of odor intensities than panels do and permit a comparison of rela- tive odor compositions from different axillae and collections. This paper describes axillary odor control by a medicated soap* as compared with that by a neutral soap.• The medicated soap contained 0.75% of hexachlorophene and 0.7,5% of 3,4,4'-trichlorocarbanilide as anti- bacterial agents in a neutral soap base. Answers were sought to the following questions: How efficient is this antibacterial system in depressing the bacterial population density, * Dial ©, Armour and Co. 1' Ivory ©, Procter and Gamble.