322 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS 11oo 1 ooo -- 9OO 800 (• 700 r- E 600 2 5oo .o_ E 4OO 3OO 200 lOO o SLS10% 1 008 1'010 1'0.13 1'0.17 1:025 1.0.50 1 1.00 SLEC-132.8% [• Baseline El Day 1 '•O• Day 2 • Day 3 • Day 4 • Day 5 Figure 26. Electrical conductance--Mean baseline and post-patch application values with varying molar ratios of 1.0% SLS:SLEC-13. 150 '• 100 -- ._E 50 o SLS10% 1:008 1 0.10 1'013 1:017 1:0.25 1 0.50 1'100 SLEC-1328% I-• Baseline • Day 1 .'. '(• Day 2 %F•] Day 3 • Day 4 • Day 5 Figure 2D. Laser Doppler flowmetry--Mean baseline and post-patch application values with varying molar ratios of 1.0% SLS:SLEC-13. Day 2, to 1:0.09 on Day 3, 1:0.14 on Day 4, and 1:0.15 on Day 5. On Day 8, the ratio returned to the Day 2 ratio. For the panelists treated with SLS and SLEC-13 (Table IV), a mean molar ratio of 1:0.08 induced •50% of the SLS value on Day 2. The ratio declined on subsequent days to 1:0.09 on Day 3, 1:0.11 on Day 4, and 1:0.16 on Day 5. On Day 8, the mean molar ratio returned to the Day 2 ratio. A statistical difference was found between the two groups of panelists only on Day 4 (Table V). LASER DOPPLER FLOWMETRY MEASUREMENTS In the group of panelists treated with mixtures of SLS and SLEC-5 (Table III), the mean

ASSESSING REDUCTION OF SLS IRRITATION 323 SLS 1 0% 1 ß 0 08 1 ß 0.10 Baseline • Day 1 '013 Day 2 1.0.17 1'025 1'0.50 1'1.00 SLEC-13 2 8% •] Day 3 • Day 4 • Day 5 Figure 2E. Skin color reflectance--Mean baseline and post-patch application values with varying molar ratios of 1.0% SLS:SLEC-13. Table III Mean Molar Ratios of 1.0% SLS:SLEC-5 Inducing •50% of the SLS Value as Assessed by Five Evaluation Methods Day 2 Day 3 Day 4 Day 5 Day 8 Erythema scores TEWL Electrical conductance Laser Doppler flowmetry Skin color reflectance 1:0.09 1:0.13' 1:0.15' 1:0.18' 1:0.17' (29 %) (40%) (26%) (15 %) (21%) 1:0.10 1:0.16' 1:0.20' 1:0.28' 1:0.095 (48%) (29%) (20%) (23%) (7%) 1:0.08 1:0.09 1:0.14':• 1:0.15' 1:0.08:• (0%) (16%) (32 %) (26%) (0%) 1:0.08 1:0.15' 1:0.21' 1:0.34* 1:0.16'5 (0%) (97 %) (138%) (109%) (76%) 1:0.10 1:0.27' 1:0.30' 1:0.40' 1:0.28' (31%) (121%) (107%) (91%) (143%) Mean molar ratios are derived from the data of six panelists. Coefficients of variation are shown in parenthesis. * Significant difference at p 0.05 level from Day 2 within each evaluation method. • Significant difference at p 0.05 level from previous day within each evaluation method. molar ratio inducing •50% of the SLS value decreased progressively and significantly from 1:0.08 on Day 2, to 1:0.15 on Day 3, 1:0.21 on Day 4, and 1:0.34 on Day 5. On Day 8, the ratio of 1:0.16 was still significantly different from the Day 2 ratio. With regard to the panelists treated with SLS and SLEC-13 (Table IV), the mean molar ratios inducing skin response •50% of the SLS value were as follows: 1:0.08 on Day 2, 1:0.09 on Day 3, 1:0.14 on Day 4, and 1:0.16 on Day 5. The ratio of 1:0.09 on Day 8 was not significantly different from the Day 2 ratio. Statistical differences were found between the two groups of panelists on Days 5 and 8 (Table V).