DETECTION THRESHOLDS OF CAPSAICIN 161 Table II Links Between Detection Thresholds and Questionnaire Items Do you regard yourself as having a sensitive facial skin? Does your facial skin react to emotion and/or stress? Does the expression "does not tolerate cold weather or a cold environment" apply to your facial skin? Does going out in the wind cause your facial skin to itch, burn, or sting? Do you consider yourself as having a facial skin prone to irritation? Does the expression "does not tolerate fast changes in temperature" apply to your facial skin? Do you consider yourself as having a reactive facial skin? Have you ever experienced an adverse reaction on your face to a cosmetic or toiletry product? Does the expression "does not tolerate hot weather or a hot environment" apply to your facial skin? Does your facial skin react to your monthly cycle? Does your facial skin react to spicy food? Do some cosmetics or toiletry products make your facial skin itch, sting, or burn? Do you consider that your facial skin reacts readily to cosmetics or toiletries? Did you suffer from eczema or dermatitis as a child? Do you avoid certaian cosmetics that you feel may cause your facial skin to react? Does going out in the sun cause your facial skin to itch, burn, or sting? Does your facial skin react to air pollution? Have you ever suffered from asthma or hayfever? Does your facial skin react to alcoholic drinks? Have you ever suffered from eczema or dermatitis? Kendall's -r6 values are arranged in decreasing order of statistical significance. Kendall's T6 value p 0.362 0.250 0.235 0.229 0.222 0.220 0.199 0.184 0.182 0.174 0.157 0.152 0.143 0.119 0.115 0.109 0.056 -0.056 0.052 0.032 0.001 0.001 0.001 0.002 0.002 0.003 0.006 0.012 0.013 0.017 0.032 0.037 0.050 0.104 0.116 0.138 0.444 0.447 0.476 0.660 emotion and/or stress and, to a lesser extent, with skin reactivity to spicy food and to the monthly cycle. There was no significant relationship with atopic diathesis and with skin reactivity to air pollution, to alcoholic beverages, or to sun. The strongest association with self-declared facial sensitive skin is illustrated by Figure 26, which shows its incidence in the six subpopulations classified by the detection threshold. Self-reported sensitive skin incidence was higher than the mean (63.5%) in the three groups who detected the lowest concentrations and lower than the mean for the three others. A very significant trend towards an association between the incidence of self-declared sensitive skin and the capsaicin threshold was noted (Cochran-Armitage p 0.001). In general, despite a higher incidence found for the concentration 3.16 x 10-4%, the lower the threshold, the higher the sensitive skin incidence. In addition to the association with the questionnaire items, we studied the correlation with age, known to influence self- perception of sensitive skin. Figure 3 shows the mean age in the six groups. We noted a significant trend toward a relationship between age and detected capsaicin concentra- tion Qonckheere Terpstra p = 0.0142): the older the subject, the higher the capsaicin detection threshold.

162 JOURNAL OF COSMETIC SCIENCE 42 40 l 38 ca CD CD 36 ca 34 CD 32 30 3,16.10-6% 1.10""% 3,16.10 ... % None Perceived capsaicin concentration Figure 3. Relationship between the capsaicin detection threshold and age. This figure shows the mean age in the six subpopulations classified according to detected capsaicin solution. Vertical bars denote one standard error of the mean. REPORTED SENSATION Table III shows the nature and the intensity of detected sensations in the 109 subjects who reached their detection threshold. A large variety of sensations was reported. The most frequent were stinging and burning sensations, but sensations of tingling, itching, tickling, tightness, coolness, and even a feeling of presence, were also recorded. The great majority of subjects (89.0%) reported only one sensation. The others (11.0%) reported Table III Nature and Intensity of the Reported Sensations at Detection Thresholds for the 109 Subjects Who Detected One of the Five Capsaicin Solutions N ature/ln tensity Stinging sensation Burning sensation Tingling sensation Itching sensation Feeling of presence Tickling sensation Burning and stinging sensation Stinging sensation and tightness Stinging and tickling sensation Stinging and tingling sensation Itching and tingling sensation Itching and stinging sensation Itching sensation and tightness Burning and tingling sensation Feeling of coolness M.D. Total M.D. = missing data. 2 37 24 8 7 6 5 4 2 1 2 102 (93.6%) 3 4 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 5 (4.6%) M.D. Total 0 41 (37.6%) 1 25 (22.9%) 0 9 (8.3%) 0 7 (6.4%) 0 6 (5.5%) 0 5 (4.6%) 5 (4.6%) 0 2 (1.8%) 0 1 (0.9%) 0 1 (0.9%) 0 1 (0.9%) 0 1 (0.9%) 0 1 (0.9%) 0 1 (0.9%) 0 1 (0.9%) 0 2(1.8%) 2 (1.8%) 109 (100%)