216 JOURNAL OF COSMETIC SCIENCE Table V Overall Analysis of Variance Overall mean Group 1 (18--45) Group 2 (65-80) 8.81 7.95 n = 26 per group. The p-value for the group effect was 0 .1510, indicating no significant difference between groups. COMPARISON OF TEST ARTICLES FOR EACH GROUP The Friedman analysis indicated significant differences between test articles for each group (p 0.001). Both groups differentiated the most irritating test articles (G and A) from the remaining samples test article K differentiated from those less irritating test articles test articles B, D, and H differentiated from samples F, CJ, and E and test article F separated from test articles C, J, and E. A summary of these analyses is shown in Table VI. ANALYSIS BY TEST ARTICLE Additional analyses were conducted evaluating for differences between groups for each test article separately. There were no significant differences between groups for the Table VI Comparision of Test Articles for Each Group Group 1 (18--45) Group 2 (65-80) Test article G A K B D H F C J E Significant comparisons at p 0.05 Test article means* 24.7 22.0 11.0 10.2 8.7 6.7 3.0 0.8 0.6 0.3 G,A VS K,B,D,H,F,C,J,E K vs B,D,H,F,C,J,E B,D, vs H,F,C,J,E H vs F,C,J,E F vs C,J,E Test article G 22.6 A 21.8 K 10.6 D 7.7 B 7.0 H 6.2 F 1.9 C 0.7 J 0.6 E 0.3 Significant comparisons at p 0.05 * Test article means joined together are not significantly different. Test article means* G,A VS K,B,D,H,F,C,J,E K vs D,B,H,F,C,J,E D vs B,H,F,C,J,E B,H vs F,C,J,E F vs C,J,E

EFFECTS OF AGE ON IRRITATION RESPONSES 217 Table VII Analysis of Variance Results Test article means A B C D E F G H J K Group 1 22.0 10.2 0.8 8.7 0.3 3.0 24.7 6.7 0.6 11.0 Group 2 21.8 7.0 0.7 7.7 0.3 1.9 22.6 6.2 0.6 10.6 p-value* 0.500 0.128 0.500 0.228 0.500 0.086 0.225 0.500 0.500 0.500 n = 26 per group. * No significant differences between groups for individual test article analyses. individual test article analyses. A summary of those analyses is shown in Table VII and Figure 1. DISCUSSION Testing for cutaneous irritation is one of the most important aspects of cosmetic product safety development because irritancy accounts for the greatest number of complaints related to product use. Yet, little verification or improvement of the most accepted test has occurred since its inception (1,2). Our results indicate that test subjects over the age of 65 can discriminate products in a similar manner as younger test subjects. Certainly, there will be test products that are manufactured for use by consumers younger than 65 years of age, and excluding older age subjects in the testing of those products may be appropriate. However, based on the results of this research, one can utilize subjects over the age of 65 when warranted or necessary with the assurance that 30 25 20 15 10 5 0 A B C D E F G H J K I GJ 1 a-4s 11!'11 ss-ao I Figure 1. Patch test scores (average subject total).