154 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS MODES OF OPERATION Example I Well-intentioned authors writing in reputable medical journals publish ar- ticles with all-inclusive titles linking allergie eontaet type dermatitis to a consumer product, not necessarily from a single inanufaeturer, such as a pow- der puff, nail base-coat, eye glass, and perfuxne. A vivid description of the eruption is linked to product usage and then conclusively proven by a lesser or greater eolleetion of sophisticated positive pateh test data. The effect of tiffs approach in the current elimate of consumerism and eon- trols is enormous. Immediately, the reader dermatologist acquires a new mini- syndrome and the nation's lay science writers uneover an exeiting threat to society to reveal in their syndicated columns. Even the Wall Street Journal runs an item on it. The author of one such report discovered 9 eases in a single year from an "average" practice in close proximity to a metropolitan area. In his hurried study 19 separate products in the class were involved. Let us aeeept the skin test data as unimpeachable and assume this author's experienee refieets what is happening in a practice population of approximately 100,000. Extrapolating these figures to the general population by any of several teeh- hies, we should expect 18,000 to 27,000 professionally recognized com- plaints annually to this class of consumer produet. In an informal poll of 12 dermatologists with American Board certification associated with a major metropolitan teaching eenter-men and women whose practices reflect experience from a population greater than 1,000,000-the yield of suspected eases of dermatitis attributable to the consumer produet in question did not reach 9 for the entire group in the more than 2 years since the original article was published. Why this wide discrepancy, particularly with consumer sales of this prod- uct category increasing anmmlly? Example II We are a society of collectors h'om antique automobiles to zithers. We search for the rare and dream of the unobtainable. Each time the stamp col- lector approaches the Postal Service window to purchase the latest com- memoratives he relives the fantasy of being handed a sheet of stamps with the airplane upside down. Some of my dermatologic colleagues achieve this exhilaration through publication of the medical curiosity (in this instance the first documented report of an allergic contact dermatitis to substance X) confirmed by positive skin patch test. There is no quarrel with the need for cataloguing such information. Per- haps the North American or International Contact Dermatitis Research Groups should be the repository. Why, however, is a trivial tidbit of knowl-

SKIN PATCH TEST 155 edge afforded the same status and prominence in dermatologic literature as a major advance in medical and scientific knowledge? Example HI Allergy is an acquired state of reactivity. It is manifested when specifi- cally sensitized tissue-the shock organ-is exposed t•o the allergen in question. A dose relationship exists. It is particularly characteristic for the allergic mcchanism to be activated by unusually minute amounts of the allergen. Although the foregoing statements are an oversimplification of the subject, they are basic tenets in the technic of skin patch testing. Deviation from these principles demands cautious interpretation of the test results. We are presently observing skin patch test technics that bear little or no relationship to customary usage of a consumer product (e.g., 10 times and 9,0 times use concentration of a suspected allergen, incorporation of irritating agents in the test vehicle, especially devised vehicles with unusual keratin or epidermal penetrating characteristics, and preliminary stripping of keratin). The test results from such procedures may complicate and confuse what they purport to simplify and the neomycin story illustrates it best. Current tabulations of common agents causing allergic contact type derma- titis position neomycin high on the roster. This questionable honor was be- latedly acquired because the conventional closed skin patch test with use- concentration .of neomycin failed to produce positive tests in selected patients in whom the association was suspected. However, when the test concentra- tion was increased by a factor of 10 or 20 times use, the harvest of positive results improved. Patients whose biologic mechanism persisted in being slug- gish, however, were then stimulated, or whipped, into conformity by a hypo- dermic intradermal injection of neomycin. Furthermore, the dermatologic lit- erature cautions the .observer not to be impatient in his search for positive skin tests. He is advised that delayed reactions are common. If early read- ings are negative, look again the reward will appear in 5 or 7 days. Since it takes about 5-7 days to "incubate" an allergic state where none existed be- fore, one should not really be surprised by the efficiency of this skin patch test technic, which is, unfortunately, the established procedure for demon- st-rating neomycin allergy. A startling piece of research in 1967 by Raab (2,3) revealed that neomycin shared a particularly basic chemical characteristic with a few other sub- stances, e.g., polymyxin B and compound 48/80. Raab showed that neomycin is capable of degranulating mast cells which pr. ovoke the release of histamine. Raab recognized that neomycin must have an allergy-producing potential similar to many other substances however, it is neomycin's mast cell depleting properties that are exceptional and have gone unrecognized. Skin testing with high concentrations or by intradermal injections of neomycin may elicit neo- mycin's particular irritant qualities, qualities that are not being separated from an allergic response (4).