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).

324 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table IV Mean Molar Ratios of 1.0% SLS:SLEC-13 Inducing •50% of 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 1:0.09 1:0.12 1:0.15':1: 1:0.115 (9%) (16%) (11%) (14%) (30%) 1:0.10 1:0.10 1:0.12' 1:0.18'$ 1:0.095 (21%) (22%) (22%) (15%) (16%) 1:0.08 1:0.09 1:0.11 1:0.16'$ 1:0.085 (0%) (16%) (21%) (55%) (0%) 1:0.08 1:0.09 1:0.14'$ 1:0.16' 1:0.095 (0%) (16%) (68%) (58%) (16%) 1:0.09 1:0.11 1:0.16'$ 1:0.18' 1:0.14' (16%) (20%) (36%) (15%) (21%) 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. Table V Comparison of Mean Molar Ratios of 1.0% SLS:SLEC-5 or -13 Inducing •50% of the SLS Value as Assessed by Five Evaluation Methods Day 2 Day 3 Day 4 Day 5 Day 8 Erythema scores SLEC-5 1:0.09 1:0.13' 1:0.15' 1:0.18 1:0.17' SLEC- 13 1:0.09 1:0.09 1:0.12 1:0.15 1:0.11 TEWL SLEC-5 1:0.10 1:0.16' 1:0.20' 1:0.28' 1:0.09 SLEC- 13 1:0.10 1:0.10 1:0.12 1:0.18 1:0.09 Electrical conductance SLEC-5 1:0.08 1:0.09 1:0.14' 1:0.15 1:0.08 SLEC- 13 1:0.08 1:0.09 1:0.11 1:0.16 1:0.08 Laser Doppler flowmetry SLEC-5 1:0.08 1:0.15 1:0.21 1:0.34' 1:0.16' SLEC- 13 1:0.08 1:0.09 1:0.14 1:0.16 1:0.09 Skin color reflectance SLEC-5 1:0.10 1:0.27' 1:0.30 1:0.40' 1:0.28' SLEC- 13 1:0.09 1:0.11 1:0.16 1:0.18 1:0.14 Mean molar ratios are derived from the data of six panelists. * Significant difference at p 0.05 level between SLEC-5 and SLEC-13 on each particular day within each particular evaluation method. SKIN COLOR REFLECTANCE MEASUREMENTS In the group of panelists treated with mixtures of SLS and SLEC-5 (Table III), the mean molar ratio inducing •50% of the SLS value dropped precipitously from 1:0.10 on Day 2, to 1:0.27 on Day 3, 1:0.30 on Day 4, and 1:0.40 on Day 5. On Day 8, the ratio of 1:0.28 was still significantly different from the Day 2 ratio.