114 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Surfacan BOO 700 BOO o SLS 500 400 aO0 x SLES 200 io0 o -•00-- • PEG20 Dayi DayE Day3 Day4 Day5 Final Evaluation time Figure 3. Relative change of electrical conductance (treated vs. controlcycle 1) during one week of daily treatments, October-November 1989. MOISTURE FACTOR (MF) INDEXES BY FTIR SPECTROSCOPIC MEASUREMENT Tables V and VI show mean MF indexes with standard deviations for treated sites during test cycles 1 and 2, respectively. An increased MF index value suggests an increase in the water content of the stratum corneum. Figures 5 and 6 illustrate the corresponding mean relative percentage changes. In both test cycles, MF indexes obtained from SLS-patched sites were significantly increased when the test day's values were compared with the pretest values. The results from the two test cycles were similar, and no significant differences were noted between the two test cycles. No statistically significant differences were observed in SLES or PEG-20 glyceryl monotallowate-patched sites either within the same test cycle or between the two test cycles. SKIN ERYTHEMA INDEX (+ a*) Tables VII and VIII show the mean + a* values with standard deviations for SLS, SLES, and PEG-20 glyceryl monotallowate-treated sites during test cycles 1 and 2. Figures 7 and 8 illustrate the mean relative percentage changes during the two test cycles. No statistical differences in a* values were detected in test sites exposed to either SLES or PEG-20 glyceryl monotallowate during both test cycles.

CHANGES IN STRATUM CORNEUM 115 Surfactant tt00- iooo 900 o SLS BOO 700 600 500 400 • SLES 300 200 ioo o - iO0 • ß PEG20 Dayi Day2 Day3 Day4 Day5 Final Evaluation Figure 4. Relative change of electrical conductance (treated vs. control-•cycle 2) during one week of daily treatments, January-February 1990. Table V Mean MF Values (S.D.) of Treated Sites in Test Cycle I During One Week of Daily Treatments, October-November 1989' Baseline Day 1 Day 2 Day 3 Day 4 Day 5 Final 1.05 1.15 1.24 • 1.391 1.38 • 1.411 1.14 SLS (0.04) (0.06) (0.09) (0.09) (0.05) (0.02) (0.04) 1.10 1.09 1.15 1.16 1.15 1.14 1.13 SLES (0.03) (0.05) (0.03) (0.05) (0.04) (0.03) (0.02) 1.09 1.07 1.11 1.10 1.13 1.10 1.12 Tallowate (0.03) (0.03) (0.03) (0.03) (0.05) (0.04) (0.02) * Each value is the mean of six subjects. 1 Represents a significant difference at p = 0.05 level from the baseline value within each subgroup. Gradual increases of + a* values were observed in all SLS-patched sites in both test cycles. In test cycle 1, a statistically significant increase was noted at day 3, while in test cycle 2, a significant difference was observed a day earlier. The control sites for both cycles showed no significant differences from the pretest mean values. As shown in Figures 7 and 8, the relative changes in + a* caused by SLS were greater in test cy- cle 2.