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).

218 JOURNAL OF COSMETIC SCIENCE test article differentiation can be achieved. We speculate that it would be appropriate to have 10% of a test panel over the age of 65, and potentially more if a product is marketed to that segment of the population. CONCLUSIONS Data from both groups of test subjects similarly differentiated mild to moderately irritating chemicals. The conclusions arrived at in this study indicate that older subjects should not necessarily be excluded in comparative studies of irritancy. REFERENCES (1) B. M. Lanman, E. B. Elvers, and C. J. Howard, The role of human patch testing in a product devel­ opment program, joint Conference on Cosmetic Sciences, The Toilet Goods Association (currently The Cosmetic, Toiletry and Fragrance Association), Washington, D. C., April 21-23, 1968. (2) R. S. Berger and J.P. Bowman, A reappraisal of the 21-day cumulative irritation test in man, J. Toxicol. Cut. Ocul. Toxicol., l, 109-115 (1982).