86 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS 11o 70 Y ' 1•õ.04 - 20.õ94 B-•.343 X + • 43• 40 Lm• (M 'q- • (20 • (M TCC [/J9/c., 2 ] Figure 8. Correlation between skin surface roughness (Rz replica taken before washing) and TCC transfer rate using soap K (0.26% soluble TCC in nonylphenolpolyglycolether). Samples were taken after washing with running tap water of 35øC. This explanation is supported by the finding that the rougher skin of elderly people absorbs more deodorant than the smoother skin of younger volunteers. These results were also found using soap C and, to a lesser extent, when using soap D. INFLUENCE OF WATER TEMPERATURE The transfer rate is influenced by the temperature of the tap water used. In water of 30øC the amount of TCC transferred is higher than when using water of 40øC (Figure 9a). We found here that solubiIization of the mixture of the refattening agent and TCC (= variant of soap G) lowers this temperature dependence. INFLUENCE OF THE CONTENT OF SOLUBILIZER It can easily be recognized that the content of solubilizer in soap G is at a reasonable level with respect to distribution and bioavailability by comparison of the TCC transfer rate of soap G with that of soap K, which contains an excess of solubilizer (Figure 9b): The amount of transferred TCC drops by about 40% when soap K is used. ESTIMATION OF THE TIME-DEPENDENT TRANSFER OF TCC To estimate the percentage of TCC transferred to the skin during the washing proce- dure, an experiment was performed on one volunteer:

DEODORANT EFFICACY OF TCC 87 0.7 0.6 0.5 0.4 0.3 0.1 0.0 Vc:r'-i=nt o½ eoop G So=p C Figure 9a. Influence of temperature (30øC/40øC) on TCC transfer rates. Samples were taken after washing with soap G and a variant of soap G for 2 minutes. a) The combined surface of lower forearm and hand was estimated to be 1030 cm 2. b) After 30 seconds of washing (30ø(2, running tap water), the volunteer had used 1.6 g, and after 120 seconds 6.2 g of soap D.