j. Cosmet. Sci., 51,267-273 (September/October 2000) The use of chemical probes to assess the facial reactivity of women, comparing their self-perception of sensitive skin JAMES P. BOWMAN, ANNA K. FLOYD, and ANGELA ZNANIECKI, Hill Top Research, Inc., P.O. Box 429501, Cincinnati, OH 45147 ALBERT M. KLIGMAN and TRACY STOUDEMAYER, S.K.I.N., Inc., 151 East Tenth Avenue, Conshohocken, PA 19428 and OTTO H. MILLS, UMDNJ and Foundation for Basic Cutaneous Research, 123 South Franklin Street, Doylestown, PA 18901. Accepted for publication August 31, 2000. Synopsis "Sensitive skin" is a term that has a very distinct meaning to each individual, but over a large group the definition may vary considerably. In this study approximately 1000 Caucasian females (ages 18 to 65) in five geographically diverse locations (Arizona, Ohio, New Jersey, Manitoba, and Florida) were recruited to answer a questionnaire that specifically asked, "Do you have sensitive skin?" and also documented derma- tological parameters and reactions to products. Three chemical probes were applied to each volunteer on separate visits to the laboratory: 10% aqueous lactic acid, 10% balsam of Peru, and 10:90 chloroform/ methanol. Burning/stinging responses were recorded each minute for up to ten minutes. The endpoints for analysis were (a) time in minutes for perceived burning/stinging and (b) maximum score achieved. The study was undertaken to compare individuals who classified themselves on a written questionnaire as having sensitive skin with a group of individuals self-classified as having non-sensitive skin. The response param- eters for each of the chemical probes were correlated with the subject's self-assessment of sensitive skin condition, skin medical history, and tendencies for personal care product selection. With each of the chemical probes, a statistically significant difference was found between the responsiveness of the self- assessed sensitive skin and non-sensitive skin groups for the parameters measured (time to perceived burning/stinging and maximum score achieved). However, there were a large number of subjects self- perceived as sensitive who did not respond to any of the chemical probes, while others self-perceived as non-sensitive responded strongly. Analysis of demographic and response data did not identify any specific profile of responders and non-responders. These results indicate that individual perception of sensitive skin by self-assessment may not always conform to the functional determination of sensitivity to chemical probes. INTRODUCTION When normal adult American women are asked whether they have sensitive skin, a large Anna K. Floyd's present address is Schering-Plough Health Care Products, Inc., 3030 Jackson Avenue, Memphis, TN 38151. 267

268 JOURNAL OF COSMETIC SCIENCE proportion respond positively. Producers of skin care products are well aware that many women report that they are intolerant to a variety of cosmetic formulations, citing sunscreens, fragrances, and moisturizers as most often troublesome. By "sensitive skin" some respondents mean any adverse event including various rashes, breakouts, and assorted visible dermatoses, mainly focused on the face (1). A sizeable number of women with self-assessed "sensitive skin" record a variety of purely subjective discomforts that occur in the absence of clinical signs. These include stinging, burning, itching, tight- ness, and other vague sensations. The question arises regarding the credibility of these assessments, especially the sub- clinical neurosensory reactions. Among the pressing issues are: Can women with sensi- tive skin be identified by clinical examinations? Is there a recognizable phenotype such as oily, dry, or photodamaged skin? What tests are available to validate the presence of sensitive skin? Should pre-marketing surveys of new skin care products be carried out in panels of women who have been objectively identified as having sensitive skin? We examined the sensitivity of chemical probes to assess the prevalence and severity of sensitive skin. MATERIALS AND METHODS Approximately 1000 adult white females (ages 18 to 65) were recruited from five geographically diverse locations in the North American continent: Arizona, Ohio, New Jersey, Manitoba, and Florida. This study compared the responses of two populations who by self-assessments perceived themselves to have sensitive or non-sensitive skin to three chemical probes, each of which elicited characteristic reactions. In each test site approximately 200 women participated, 40% of whom had sensitive skin while 60% were non-sensitive. There was an attempt to enroll 50% from each group. At the first visit each subject answered a 20-item questionnaire that specifically asked, "Do you have sensitive skin?" and gave a detailed account of adverse reactions to facial skin care products. Applications of the chemical probes were randomized to opposite sides of the face. There were three visits at least two days apart, with one probe being applied at one time. The three chemical probes were applied on separate visits in accordance with the meth- ods outlined below see (Figure 1). A script was provided to standardize the wording used when communicating with the subjects regarding subjective responses. Burning/ stinging responses were recorded each minute for up to ten minutes, utilizing the following grading scale: 0 = none, 1 = mild, 2 = moderate, 3 -- severe. The endpoints for analysis were (a) time in minutes to perceived burning/stinging and (b) maximum score achieved. STATISTICAL ANALYSIS The data used in the statistical analysis were the times to perceive the specified sensory response and the maximum score achieved. Student's t-test was used to establish whether there were statistically significant differences to each of the three probes between the two groups (sensitive vs non-sensitive)at the 0.05% level.