CHANGES IN STRATUM CORNEUM 121 p 2-- Surfactan[ e r 0 c -! e -2 o SLS -3 n -4 a -6 g -7 e -B • SLES -9 c -tO h a -i2 g -t4-- 8 -t5 -- ,PEG20 I]a¾! Day2 Day:] Day4 I]a¾5 Fine! EvaIuaf. ton Figure lO. Relative change of brightness (treated vs. control•ycle 2) during one week of daily treat- ments, January-February 1990. For quantitative image analysis of the skin replicas, useful information was obtained on changes of the mean depth of the dermatoglyphics by calculating the mean ratio of the shadow areas to the shadow perimeters. Figures 14 and 15, respectively, show the mean ratios of all three subgroups at day 1 before exposure to surfactants and at day 5 after ten 45-minute patches in the two different test cycles. Significant changes between these two days were observed in the sites treated with SLS in both test cycles. No significance was calculated for the sites treated with either SLES or PEG-20 glyceryl monotallowate. DISCUSSION The daily treatments and measurements by a battery of instrumental, morphometric, and clinical methods demonstrated advantages over that of a single treatment and/or measurement procedure. The protocol of twice-daily patch applications for 45 minutes each provided the advantage of gradual skin changes in contrast to the effects obtained from a single 24-hour patch application. Together with the multiple measurements taken at daily intervals, important information was obtained with regard to the SC response to an irritant, which could be useful toward understanding the mechanisms of the induced changes. The consistency and the reproducibility of all measurement parameters were well dem- onstrated by the body of data obtained from both surfactant-treated and water-treated sites. The water-treated control sites showed no significant differences between day-

122 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table XI Clinical Scores (S.D.) of Treated Sites in Test Cycle 1 During One Week of Daily Treatments, October-November 19897 Day 1 Day 2 Day 3 Day 4 Day 5 Final 0.00 0.00 0.83* 2.17' 2.67* 2.00* Erythema (0.00) (0.00) (0.45) (0.98) (1.03)2.50*0.17(0.55)(0.41)1.83*0.67' (0.8 SLS Scaling 0.00 0.33 0.83* 1.33* (0.00) (0.52) (0.41) (0.52) (0.41) Fissuring 0.00 0.00 0.00 0.33 (0.00) (0.00) (0.00) (0.52) (0.52) 0.00 0.00 0.00 0.00 0.00 0.00 Erythema (0.00) (0.00) (0.00) (0.00) (0.00)0.500.00(0.55)(0.00)0.170.00(0.00) (0.0 SLES Scaling 0.00 0.00 0.17 0.50 (0.00) (0.00) (0.41) (0.55) (0.41) 0.00 0.00 0.00 0.00 Fissuring (0.00) (0.00) (0.00) (0.00) 0.00 0.00 0.00 0.00 0.00 0.00 Erythema (0.00) (0.00) (0.00) (0.00) (0.00)0.000.00(0.00)(0.00)0.000.00(0.00)(0.00) (0.0 0.00 0.00 0.00 0.00 Tallowate Scaling (0.00) (0.00) (0.00) (0.00) 0.00 0.00 0.00 0.00 Fissuring (0.00) (0.00) (0.00) (0.00) ? Each score is the mean value of six subjects. * Indicates a significant difference at p = 0.05 level from the pretest score. to-day mean values, between subgroups in the same test cycle, or between the two test cycles. The clinical observations for the surfactant-treated sites were similar for both test cycles. However, changes with SLS were noted slightly earlier during the winter test cycle. On the other hand, measured values, particularly for SLS, were larger during the winter test cycle. The correlation between TEWL and MF values of SLS-treated sites in both test cycles was determined using the least squares method. The correlation coefficients ofr = 0.69 in the first cycle and r = 0.78 in the second cycle were significant (p = 0.03 and p = 0.02, respectively). The correlations between TEWL and +a* were r = 0.96 (p = 0.005) in test cycle 1 and r = 0.91 (p = 0.01) in test cycle 2. For TEWL vs. visual erythema, r = 0.86 (p = 0.04) in test cycle 1 and 0.90 (p = 0.01) in test cycle 2. For +a* vs. visual erythema, r = 0.92 (p = 0.03) and 0.94 (p = 0.008) for test cycles 1 and 2, respectively. TEWL measurements best indicated the changes with regard to the barrier function of the SC. The repeated exposures to SLS resulted in a progressive increase of TEWL from the patched sites, reflecting a loss of the capacity of the SC to retain water. The higher TEWL values observed after four days of treatments may be the result of severe damage or partial destruction of the SC itself. The degree of increase of TEWL with SLES was far less than that caused by SLS. For the test sites treated by PEG-20 glyceryl monotallowate, the changes in TEWL showed no significant differences over the control sites in both test cycles. Although the relative