J. Cosmet. Sci.! 56, 213-218 Quly/August 2005) Effects of age on human cumulative irritation responses JAMES P. BOWMAN, Hill Top Research Inc., P.O. Box 138, Miamiville, OH 45147 ALBERT M. KLIGMAN and TRACY STOUDEMAYER, S.K.I.N., Inc., 151 East Tenth Avenue, Conshohocken, PA 19428 and JOSEPH NICHOLSON, Product Investigations, 151 East Tenth Avenue, Conshohocken PA 19428. Accepted for publication April 4, 2005. Synopsis A 10-day cumulative irritation test was conducted to evaluate whether or not test subjects 65 years of age and older would rank eleven test materials the same as subjects 18 to 45 years of age The test materials consisted of mild to moderately irritating chemicals. The test articles were ranked similarly for both groups of subjects. Statistical analysis indicated no significant difference between the groups of subjects. Thus older subjects should not necessarily be excluded in comparative studies of irritancy. INTRODUCTION The 21-day cumulative irritation test is utilized to determine the irritation potential and/or comparative irritation of a wide range of topical drugs, cosmetics, cleaners, and occupational chemicals. Typically, protocols exclude subjects who are over the age of 65. This exclusion is thought to be a carryover from excluding older subjects from allergic contact dermatitis studies, as the immune system tends to decrease in its ability to respond with advancing age. However, many topical products are purchased by con­ sumers in this age group. The aim of the present study was to determine if subjects over the age of 65 would rank potential irritants in the same order as younger persons. METHODS The procedure is a modification of that described by Lanman et al. (1) and Berger and Bowman (2). Informed consent was obtained. Two groups were evaluated: Group 1 consisted of subjects 18 to 45 years of age and Group 2 consisted of subjects aged 65 to 80. The individual samples were applied to sites on the skin of the back for contact periods lasting 24 hours. Patches were applied for five consecutive days and, following a one-day rest (Sunday), were applied for four consecutive days. Patches were removed by laboratory technicians and patch sites were evaluated 30 minutes later. Each subject 213

214 JOURNAL OF COSMETIC SCIENCE received nine applications of the test materials to the same sites. Any site reaching a maximum grade (grade 3 or 4 see Table I, scoring scale) was not repatched for the remainder of the study. The test materials are listed in Table II. Irritation was scored classically using a 100-watt incandescent blue bulb lamp as the artificial light source. The scorer was blinded as to the treatment assignments A five-point scale was used (Table I). STATISTICAL ANALYSIS The source data are the actual patch test scores recorded following visual evaluation of the sites on days 2, 3, 4, 5, 7, 8, 9, 10, and 11. Data used in the statistical analyses were the actual scores up to and including termination of patching. When a strong response prohibited repatching, the value at the time of termination was entered into the analyses for all scoring days till the end. Subjects that withdrew from the test were omitted from the analysis. The following statistical analyses were performed: 1. Overall analysis comparing irritation levels of Group 1 (18-45) to those of Group 2 (65-80). 2. Analysis comparing the irritation levels of the test articles within each group. 3. Analysis comparing the irritation levels of Group 1 and Group 2 for each test article. The patch test scores for each test article were summed across all test days for each test subject. For analyses 1 and 3, analysis of variance was utilized for analysis 2, the overall test article scores were ranked within each subject and then analyzed using the Friedman rank sum test. Table I Scoring Scale 0 = No erythema visible 1 = Faint erythema 2 = Moderate erythema 3 = Intense erythema 4 = Erythema with edema, vesicles, or papules A (0.2% SLS) Table II Test Materials B (0.1 % benzalkonium chloride/distilled water) C (50% xylenes/petrolatum) D (0.1 % Retin A cream) E (50% isopropyl myristate/petrolatum) F (75% propylene glycol/distilled water) G (DOAK Formula 405 AHA facial day cream) H (Lachydrin 12 lotion) I (OXY 10 benzoyl peroxide vanishing cream) J (Lacticare lotion) K (Carmol 10)