394 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS subject of debate for decades, but unfortunately one has not come to definite conclusions so far. A broader debate at the beginning of the nineties facing new experimental evidence forwarded recently might at least contribute a lot to, if not solve, the entire problem. Unfortunately, a few statements made by Dr. Rieger are not entirely correct from my point of view. In the first place, we have not "failed to provide data on the time elapsed between skin washing and... measurements": it is clearly stated in the section entitled "Time Course of Investigations" that measurements were performed "at about the middle of the application interval, i.e., at least six hours after the last cleansing procedure." In the second place, we do not totally underscore the potential role of the pH of the cleansing preparations used on its ingredients. We do state in the Discussion section that "in particular, differences in the pH value might affect substantivity of various ingredients and moreover direct antimicrobial properties of ingredients such as benzyl alcohol and methyl-isothiazolinone itself." Such a statement, however, has to be based on theoretic considerations rather than defined knowledge insofar as a particular complex preparation is concerned. For this reason, it seems to be wise not to include the statement in the Materials and Methods section. The core of the criticism by Dr. Rieger, however, seems to be that a variety of different factors might be the basis for the differential effect of the two preparations compared. He speaks of a "formidable task" to obtain more insight in vivo, and in fact it is. Therefore, it seems much more helpful just to take the two following pieces of evidence from the present experiment: 1) The long-term use of skin cleansers differing in their pH value influences the pH of the skin surface, and 2) the number of propionibacteria on the skin surface differs accordingly. The idea of a causal relationship between both phenomena probably can be much better substantiated in continuous culture experi- ments with the various microorganisms found on the skin. At the time when the present trial was performed we already had evidence from batch culture that there is a sharp rise in the specific growth rate of Propionibacterium aches, changing the pH of the medium from pH 5.5 to pH 6.0, while this is not the case with coagulase-negative staphylococci. This experience has been cited in the Introduction section of the paper. In the mean- time, however, continuous culture experiments have been performed using a chemostat. They have shown that again Propionibacterium aches, but not Staphylococcus epidermidis demonstrate a critically different growth behavior just within the comparatively small pH range to be influenced by skin washing procedures (1). REFERENCE (1) H. C. Korting, A. Lukacs, M. Vogt, J. Urban, W. Ehret, and G. Ruckdeschel, Influence of the pH-value on the growth of Staphylococcus epidermidis, Staphylococcus aureus and Propionibacterium acnes in continuous culture, Zbl. Hyg. Umweltmed., in press. H. C. Korting 8000 Munich 2, Germany

j. Soc. Cosmet. Chem., 42, 395-396 (November/December 1991) AUTHOR INDEX Bergmann, W. R., see Swafford, S. K., 235 Bielfeldt, S., see Schrader, K., 385 Bieli, E., see Gabard, B., 299 Braun-falco, O., see Lukacs, A., 159 Carlotti, M. E. Auto-oxidation of linoleic acid in cosmetic formulation, 285 Charaf, U. K., Phospholipid liposomes/surfactant interactions as predictors of skin irritation, 71 Charig, A., Inhibitor of odor-producing axillary bacterial exoenzymes, 133 Clarke, J., Influence of hair volume and texture on hair body of tresses, 341 Clarke, M. T., see Hutter, J. M., 87 Crawford, R. J., see Robbins, C. R., 59 Dember, W. N., see Warm, J. S., 199 Deppert, T. M., Substantivity of dyes and surfactants containing isothiuronium groups to hair, 1 Eigen, E., see Charig, A., 133 Froebe, C., see Charig, A., 133 Fthenakis, C., In vivo assessment of skin elasticity using ballistometry, 211 Fueghelman, M., A comment on "Bending Relaxation Properties of human hair and permanent waving performance, 129 Fujii, M., see Okano, Y., 45 Fukuda, M., see Maeda, K., 361 Futterweit, W., see Rushton, D. H., 317 Gabard, B., Measurement of lipod deposition on the skin of the forearm: Comparison of different bath oils, 299 Gabriel, K. L., see Zhou, J., 105 Gartstein V., see Kajs, T. M., 249 Gasco, M. R., see Carlotti, M. E., 285 Gehring, W., Effects of pH changes in a specific detergent multicomponent emulsion on the water content of stratum corneum, 327 Gehse, M., see Gehring, W., 327 Gloor, M., see Gehring, W., 327 Goddard, E. D., Novel gelling structures based on polymer/surfactant systems, 19 Greiner, K., see Korting, H. C., 147 Hamm, G., see Korting, H. C., 147 Hart, G. L., see Charaf, U. K., 71 Hashimoto-Kumasaka, K., see Saijo, S., 379 Holt, L. A., Cationic-Anionic surfactant interactions on wool: Implications for the conditioning of human hair, 351 Hubner, K., see Korting, H. C., 147 Hutter, J. M., Colloid titration: A method to quantify the adsorption of cationic polymer by bleached hair, 87 Italia, M.P., Gas Chromatographic determination of 1,4-dioxane at the parts-per-million level in consumer shampoo products, 97 Jachowicz, J. Z., see Deppert, T. M., 1 Just, E. K., see Hutter, J. M., 87 Kajs, T. M., Review of the instrumental assessment of skin: Effects of cleansing products, 249 Kingsley, D. H., see Rushton, D. H., 317 Kingsley, P., see Rushton, D. H., 317 Korting, H. C., Changes in skin pH and resident flora by washing with synthetic detergent preparations at pH 5.5 and 8.5, 147 Korting, H. C., see Lukacs, A., 159 Lent, B., see Mintz, G. R., 35 Leung, P.S., see Goodard, E. D., 19 Levine, M. J., see Murphy, T. D., 167 Lichtin, J. L., see Hutter, J. M., 87 Lichtin, J. L., see Swafford, S. K., 235 Lichtin, J. L., see Zhou, J., 105 Lukacs, A., Efficacy of a deodorant and its components: triethylcirate and perfume, 159 Maeda, K., In vitro effectiveness of several whitening cosmetic components in human melanocytes, 361 Maes, D., see Fthenakis, C., 211 Mark, R., see Zhou, J., 105 Masaki, H., see Okano, Y., 45 Mei, I., see Oei, H. H. Y., 309 Migliorese, K. G., see Swafford, S. K., 235 395