180 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS 0.030 0.025 0.020 0.015 0.010 0.005 0.000 I I I I I 0 1 2 3 4 5 Time (Weeks) Figure 3. Effect of storage temperature on the permeation of salicylic acid through micro-Yucatan pig skin (skin stored before dermatoming). ß 4øC, ¸ -15 øC. * Statistically significant value from the initial result. Each error bar represents the standard error of the mean. Table I Water/SA Flux Ratios During the Four-Week Period of Study Storage condition Skin dermatomed Skin stored before Skin dermatomed and dried dermatoming before storage before storage Time (weeks) 4øC - 15 øC 4øC - 15 øC 4øC - 15 øC 0 292.3 292.3 281.2 281.2 281.2 281.2 1 322.0 329.2 212.4' 295.7 270.4 273.8 2 470.0* 397.6* 320.2 340.4* 280.0 281.0 3 329.0 251.4 330.2 332.3* 270.2 236.7 4 368.5* 251.6 313.3 294.4 293.2 296.1 * Statistically different from initial results.

ASSESSING SKIN BARRIER INTEGRITY 181 • 5 • 4 _ _ I I I I I 0 I 2 3 4 5 Time (Weeks) Figure 4. Effect of storage temperature on the permeation of water through micro-Yucatan pig skin (skin dermatomed before storage). ß 4øC, ¸ -15øC. * Statistically significant value from the initial result. Each error bar represents the standard error of the mean. displayed in Table II. The flux values for the two molecules through ventral and dorsal skin were not significantly different. PERMEATION OF WATER AND SA THROUGH YUCATAN PIG SKIN OBTAINED FROM DIFFERENT AREAS OF THE BODY OF THE PIG Cumulative amounts of water and SA permeating over time through the back, left ham, and right ham were obtained. The values of water and SA fluxes were calculated and are displayed in Table II. The flux values for the two molecules through the back, left ham, and right ham were not significantly different. VARIATION IN PERMEABILITY AMONG PIGS STUDIED During this study, the initial flux values of water and SA through pig skin and the flux ratios were calculated for three different pigs. The data are plotted in Figure 8. The average rates of permeation for both water and SA were 2.58 + 0.19 mg/cm2/hour and