ANIMAL AND HUMAN TESTING IN SKIN CARE 207 Returning to the routine Schwartz-Peck human patch test--its stand- ardization is so well established that if the proper technique is adhered to and a sufficient number of individuals tested, the predictions of irritation and sensitization potentials are good. Neither test is satisfactory to deter- mine the so-called "hardening" reaction, but these have been observed by all of us on both skin and mucus membranes. Perhaps the most striking instance in our experience has been the induced toughening of gum tissue through massage with a dentifrice material that was definitely a primary irritant. On initial use of this preparation in a number of instances an erosion or superficial ulceration of the gums occurred. The inflam- matory reaction was severe and it seemed that further use of dentifrice was inadvisable if not impossible. However, amazingly enough in each in- stance with continued use the gums healed completely and the reaction did not again manifest itself in these subjects. The true sensitivity reactions have been much more difficult to predict than the primary irritations we have discussed previously. One reason for this is that the animal will apparently only respond to the strong sensitizer while man is much more susceptible. The techniques for measuring sensi- tivity reactions are essentially expansions and modifications of those methods used for measuring irritation. The standard method is the afore-men- tioned patch skin test. This is the standard human skin test and when done correctlywill give very comparable results between similar materials. Some- times the standard patch test will indicate that a test material rnay be more irritating than it really is under use conditions. This is par- ticularly true when one is testing soaps. If a group of well-known brands of toilet soaps are tested comparatively, there will be very close agree- ment between brands, but the test will show an inordinately large number of skin reactions to all. This high reaction incidence is due to a mild chemical burn or dehydration due to prolonged contact of the skin with the soap solution. It illustrates why the routine test overgrades at times. Here we have exaggerated readings because the closed patch test is an artificial condition. The "soap reaction" may become so prominent that true differences between test materials may be masked. Incidentally a test on distilled water was run at the same time as the soaps because re- cently in court trial involving a hair dye preparation, the question was asked of one of us to "name one substance in the world to which someone might not be allergic." Distilled water was named and the defense at- torney sited a published case in Detroit where that had been the offender. You see we had a few mild reactions. In the case of the soaps, the test itself was more drastic than use would have been. The reverse, i.e., where the test failed to predict reactions is shown in Table 1. Here the grades of positive response are shown in two groups: (1) erythema with induration (2 plus and over), (2) erythema without induration (1 plus). Three lotions

208 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS TABLE 1--PATCH AND USE TEST (LOTIONS AND OINTMENTS PP, OPHETIC PATCH TEST-- HUWA•'S) (200 INmVmUAI•S) (ScI•WARTZ-PECK) -Percentage Response- •---Initial .... --Challenge Lotions --• A B C A B C Erythema • induration 0 2 4 (2 week interim) 1 0 2 Erythema g induration 25 46 31 (2 week interim) 8 17 23 Ointments -,- X Y Z X Y Z Erythema • induration 2 11 3 (2 week interim) 1 12 0 Erythema õ induration 16 20 6 (2 week interim) 13 19 10 and three ointments were tested. The patch test response indicated very slight primary irritation from the lotions but no suspect sensitization re- actions. The ointments also gave very little indication of potential sensi- tization. Analysis of the data of Table 1 would not suggest that any of these materials would be detrimental in conditions of proper use, but actually one of them was not benign. The patch test simply had not mim- icked the use conditions sufficiently closely. The same preparations were given the use test that we would so strongly recommend, by other groups of individuals for a three week period between the initial and final closed patch tests. The materials were cosmetic and dermatological preparations therefore, the use conditions demanded both normal individuals and pa- tients with dermatoses. Table 2 shows what incorporation of use conditions into the prophetic patch test procedure can do. The test individuals actu- ally used the various preparations in recommended manner for three weeks. Then two weeks after cessation of use they were given a challenge patch test to elicit sensitization potentials. In the columns which show the re- actions observed during use, of particular note are the 19 individuals of TAm, E 2--PROPHErrIc PATCH TEST (LOTIONS Am) OINTUENTS PATCH ANr• UsE TEST-- HUMANS) (Tl•Atr B-SPOOlS) % % Positive Positive --Ini- Chal- Test No. and Type tial lenge Material Individual Patch Reactions, 3 week use Patch Lotion A 74 normals 1.5 lJotion B 76 normals 3.0 Lotion C 81 clinical dermato- 15 logic Ointment X 50 normals 2.0 14 known reactors to X 7.0 Ointment Y 100 acne 10 Ointment Z 71 seborrhea and acne 1.4 1--vesicular irritation 1--mild 0 erythema hands, arms 2--erythema and dryness hands 0 and wrists 1--erythema and pruritis 2--vesic- 12.0 ular reaction 3--infections secondary to occlusion 2--axillary adenopathy 0 4--axillary adenopathy 14.0 3--irritation of axillae 3--irritation and aggravation of 12.0 condition 19--flare up of lesions 12.5