SKIN PATCH TEST 157 closed skin patch test with fresh 2% PPD in pctrolatum, the recognized stan- dard concentration and vehicle. Upon removal of the patch a one to two- plus reaction was observed twenty-four hours later the test site was clearly confirmed as a strong one-plus reaction. A contralateral control site with pet- rolatum alone was negative In the intervening month between treatment and test, information was received from the manufacturer that the hair color- ing product in question was of the "permanent" or oxidation type and con- tained PPD and related dye intermediates in its formulation. Despite the clinical and laboratory evidence in this patient, the final diag- nosis of allergic eczematous contact type dermatitis due to PPD could be and was wrong. The admonition against further exposure to hair coloring prod- ucts was unnecessary. A. A. Fisher and this author have studied a number of PPD patch test-positive individuals who tolerate repeated and routine ex- posure to PPD-containing hair coloring products without adverse reactions. (7,8). Such individuals demonstrate a one-plus or slightly greater reaction to the 4S-hour closed skin patch test with 2% PPD in petrolatum. The manufac- turer's recommended open 24-hour skin test with the product is usually nega- tive in such subjects. This open type product-use-skin test is more practical as a screening procedure than previously realized. Any number of common household products, allergens as well as primary irritants-from hair spray to oven cleaner-used the evening before the ap- pearance of the eruption could have accounted for the patient's presenting dermatitis. The presence of an allergic state proven by skin patch test does not neces- sarily reflect a subject's threshold of response tmder actual conditions of ex- posure to the consumer product. Dose relationship under contrived test con- ditions are not the same as dose relationships under use conditions. SUMMARY The foregoing are a few examples of many. They are offered as representa- tive of the ongoing confusion to which the scientific, medical, and industrial communities should direct their attention. The skin patch test is a valuable means to an end. Rigid discipline is required to avoid reversal of this equa- tion. A beguilingly simple procedure provokes an extremely complex biologic mechanism subject to all the vagaries that can be associated with the re- spome of living tissue. It behooves the practitioner to be humble in his in- terpretation. Perhaps the cause-and-effect relationship seemingly confirmed by skin patch test data may be mere coincidence. Does it stand the test .of time? Is the relationship reproducible by others? A local .or a temporary situation or the zeal of an investigator are worthy of consideration. Established scientific pnb- lications might act more critically toward disseminating valuable contribu- tions. Newsletters would be a better means for expressing personal experi-

158 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS cnccs or to test the validity of inadequately ripened concepts. Scientists rep- resenting industry have been known to cooperate with physicians in the critical preparation of a scientific publication. More of such mutual respect and understanding must be cultivated. All will benefit thereby. (Received May 3, 1973) REFERENCES (1) Jadassohn, J., A contribution to the study of dermatoses produced by drags, Verb. Deutsch. Derre. Ges., 1896, pp. 103--29, in Elking, L. (trans.), Selected Essays and Monographs, New Sydenham Society, London, 1900, pp. 207-29. (2) Raab, W., Zur histaminfreisetzenden Wirking yon Neomycin: die Reaktivitat von Neo- mycin mir Heparin, Arch. Klin. Exp. Dermatol., 230, 319--28 (1967). (3) Raab, W. P., Mast cell depleting properties of Neomycin, ]. Invest. Dermatol., 50, 138-40 (1968). (4) Raab, W. P., Letter to Editor, Allergic and anaphylaetoid inflammation, J. Amer. Med. Ass., 201, 157-8 (July 10, 1967). (5) Sehorr, W. F., et al., Corss-sensitivity and aminoglyeoside antibiotics, Arch. Dermatol., 107, 533-9 (1973). (6) Hjorth, N., and Thomsen, K., Differences in the sensitizing capacity of Neomycin in creams and in ointments, Brit. J. Dermatol., 80, 163-9 (1968). (7) Fisher, A. A., and Brauer, E. W., Oxidation-type hair dyes: correlation between the diagnostic closed and consumer-oriented open skin tests, presented at 14th Interna- tional Congress of Dermatology, Padua-Venice, May 22-27, 1972 (Free Communica- tion No. 537). (8) Fisher, A. A., and Dorman, R. I., The clinical significance of weak positive patch tes! reactions to certain allergens, Curls, 11, 450-3 (April 1973).