77O JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Tape stripping as used by Updegraff (1) involves applying an ad- hesive tape to the skin surface then removing the tape with an adhering layer of skin containing colonies of bacteria. This method allows one to determine the distribution of bacterial colonies in relation to area and depth of the epidermal layers. Skin swabbing (2) is performed with cotton or calcium alginate swabs. The swabs are placed in water or hexametaphosphate solution, the suspension is shaken thoroughly to distribute the organisms, and an aliquot is plated bacteriologically. Variations in bacterial counts can occur because of nonreproducibility in the pressure used in applying the swabs to the skin and because the number of bacteria removed from the swabs may vary with the e•ciency of the shaking. A more reproducible swabbing technique is utilized by Pachtman, et al. (3). An aliquot of a 0.1ø-/o aqueous solution of Triton X-100 ©* is piperted into a glass cylinder 23 mm in diameter pressed firmly against the skin. The skin is abraded gently with a glass rod or Teflon police- man for two minutes, then the solution is removed, diluted, and plated bacteriologically. Contact plates are made by adding liquefied nutrient agar to a Rodac plate• or small container, allowing the agar to harden, then pressing the plate with uniform pressure to the skin area to be tested. Plates are incubated at 37 øC for 48 hours, whereupon colonies are counted. Ulrich (2) stated that the method is reproducible for the first five plates taken sequentially from the same area of skin. Only bacteria on the surface of the skin are enumerated by this method. This paper deals primarily with handwashing as a technique for eval- uating skin degerming. Price (4) developed a procedure whereby bacteria are removed from the hands and forearms by scrubbing with a surgical scrub brush in a series of basins containing a standard volume of water. Bacteria are removed at a decreasing rate as determined by counting the bacteria in each basin, plotting a curve which can be used to calculate the total bacterial flora on the area tested. Counts are taken on ten to fourteen basins. If an antibacterial soap is used, the reduction in bacterial count as compared to the number obtained when a nonmedicated soap is used gives a measure of the effectiveness of the antibacterial product. * Iso-octyl phenoxy polyethoxy ethanol. Registered trade mark of Rohm & Haas Co., Philadelphia, Pa. t Distributed by Baltimore Biological Laboratories, Inc., Baltimore, Md. 21218.

HAND DEGERMING EVALUATION 771 Cade (5), also utilizing a multiple basin technique, determined that degerming could be evaluated after one to two weeks of test soap applica- tion. By counting the bacteria in the first, fourth, and fifth basins of a series, a curve was developed from the data obtained. Since bacterial removal beyond the fifth basin was constant when an effective bacterio- static soap was employed, it was considered unnecessary to go beyond five basins (5). Per cent reduction was calculated by comparing counts obtained with a bacteriostatic soap to those obtained with a control (nonmedicated) soap. The multiple-basin procedure was further modified by Roman, et al. (6) who used a baseline control of 1,580,000 bacteria per fifth basin for all participants on the panel and evaluated the degerming efficiency of a bacteriostatic soap in five days. This number was obtained from non- medicated soap washings. Similarly, Kooistra, et al. (7) used a control reference figure of 1,300,000 bacteria for the fifth basin, a value derived from more than 500 iv. dividual fifth basin handwashings. The assump- tion behind this method is that participants in any experiment have essentially the same number of bacteria on their hands at the outset. However, this hypothesis is not confirmed by the second basin data for control soaps presented in their paper. In the four handwashing tests mentioned the underlying assumption is that the bacterial counts from the hands of the individual or the group would have remained constant during the entire test period if a non- medicated soap had been used exclusively. Unlike the handwashing techniques just described, the procedure of Quinn, et al. (8) allows each participant to serve as his own control dur- ing the five-day evaluation period. This is accomplished by requiring the panelist to wash one of his hands, generally the left, with nonmedi- cated soap, reserving the other hand for the bacteriostatic soap. When either hand is being washed, the other is covered with a neoprene glove. Results are obtained by comparing counts from the hand using non- medicated soap with those from the one on which bacteriostatic soap is applied. Prior to the evaluation period, nonmedicated soap is used on both hands for seven days. Neoprene gloves are used by panelists when per- forming such chores as dishwashing, scrubbing, shampooing, etc. The Quinn procedure (8) has been used by the authors to evaluate skin degerming. Results obtained with two antibacterial soaps by means of tlfis split-use method are described here.