EVALUATION OF ANTIBACTERIAL SOAP BARS 349 The skin degerming effectiveness of Antibacterial Bar A (2% BSA, TFC, and TCC) and that of Antibacterial Bar B (0.75% TCC plus 0.75% G-11) are compared in Fig. 3. Each bar on the graph, the mean number of bacteria recovered in the fifth basin, is representative of a single 9-10 member panel. The data were collected over the same general time period. The mean number of bacteria found after four day's regimented use of Bar A ranged from 1,900 to 11,000 for the in- dividual panels with an over-all mean of 5,700. Figure 1. For Bar B, the range 1.3 0 1 2 3 Percent Concentration of Hexachlorophene Skin degerming effectiveness of various levels of an antibacterial incorporated into a bar soap matrix was 48,100 to 91,000 with a mean of 65,100. An analysis of variance showed that the difference between the two bars was statistically sig- nificant (P 0.01). The data presented in Table III and Figs. 1, 2, and 3 demonstrated the capabilities of a refined technique involving usage and handwashing sampling under controlled laboratory conditions. While these results are realistic and valid for the conditions of usage exposure prescribed for the panelists, the ultimate test is to determine degerming effects resulting from normal consumer usage. For normal consumer usage studies, large panels of housewives are employed. Each subject is given unidentified bars (different shapes, colors, etc.) of the test soap to use at home for all handwashing and bathing. No other restrictions with regard to either soap or detergent exposure are imposed on the subjects. In order to make the test practi- cal for use with large numbers of panelists, second basin counts are l •' l

350 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS as a quantitative sample of the resident bacteria on the skin. Note should be made that these second basin values are influenced more by transient bacteria than the fifth basin values used in the laboratory 1.3 Figure 2. Skin degerming effectiveness of antibacterial bar soaps 3 4 1 2 3 9.0 4 REPLICATE DETERMINATIONS SOAP A* SOAP B** *Antibacterial additive 2% Mixture of BSA• TFC• and TCC ** Antibacterial additive: 0.75% TCC + 0.75% G-11 Figure 3. Skin degerming effectiveness of two different antibac- terial systems evaluations and are, therefore, somewhat less reproducible. The greater variability of the individual counts is compensated for by use of larger numbers of test subjects.