THE SKIN TESTING OF NEW COSMETICS 323 Favorable results of the prophetic patch test should always be followed by usage tests among a thousand or more subjects over a period of at least two months. There is no test which equals the test of actual usage by a large group over a long period. Conversely, prophetic patch tests are unnecessary after a cosmetic has passed the test of common usage by the public over a period of time. It is like tasting the food after the banquet has been served. I will enumerate some modifica- tions of the prophetic patch test which I have successfully used in testing new cosmetics. In testing a new deodorant soap, I first performed closed patch tests with various dilutions of a well- known toilet soap to find what dilu- tion can remain on the skin under a covered patch for twenty-four hours without causing a reaction on most of the subjects. I found this to be 0.2 cc. of a 0.5 per cent solution of the soap on a piece of flannel 3 sq. cm. in area. Ten subjects were used for this preliminary test. Then 200 subjects were patch tested at thesame time with the same dilution and same amount of the new deodorant soap, the old toilet soap, and a deodorant soap long on the market. The two series of patch tests were performed ten days apart and when no more reactions resulted from the new deodorant soap than from each of the control soaps, the new deodorant soap was pronounced safe for the trial usage test by several thousand subjects. I was asked to perform prophetic patch tests on a new hair dye. The dye in addition to other in- gredients contained considerable ammonia. It was obvious that closed patch tests with ammonia would give reactions. It was also obvious that hair dyes are not cov- ered and sealed on to the hair and scalp. They are washed off after 15-30 minutes. In this case I decided to do open patch tests with all the shades of the dye and a hair dye long on the market was used as a control. The dye was applied each day for three days to the same area of skin and no reac- tions were noted. Ten days later the procedure was repeated on the same area of skin. When no re- actions were observed in any of the 200 subjects, the dye was pro- nounced safe for trial use on several thousand subjects. After it success- fully passed the trial usage test it was placed on the market. A new antiperspirant was tested by intensive actual usage, under observation• on 200 subjects for one month. A new hand lotion was similarly tested in addition to the covered patch test using an old hand lotion as a control. A new cold wave was tested under a covered patch using as a control a cold wave that had been on the market for some time. So appropriate prophetic patch tests can be devised for depilatories, nail lacquers, lipsticks, shampoos, creams, and any other cosmetics.

324 JOURNAL OF THE SOCIETY OF COSME'•IC CHEMISTS This paper is to call your atten- tion, when testing cosmetics, to the use of appropriate common-sense modifications of the original covered prophetic patch test which was de- vised for testing fabrics. EXPERIENCES WITH AND CONSIDERATIONS OF THE HUMAN PATCH TEST METHOD* By HERMAN A. SHELANSKI, P•.D. Industrial Toxicology Laboratories, Philadelphia ¾, Pa. SINCE PRE-HISTORIC times mankind has attempted various methods of improving their ap- pearance to make themselves more attractive. Thus tattoos, war paint, and cosmetics have been used in sundry cultures at different periods of time. Today, the manufacture of materials which come in contact with the skin includes many im- portant industries. These indus- tries owe their existence not only to the demand for their products or the improvement brought about by their products but also to the fact that these products are in- nocuous when they are applied to the human skin. It is self-evident that no matter how beautiful a certain preparation may make a woman, if this product causes illness, the demand for it would cease to exist. Therefore, it is necessary to as- certain if these products are in- nocuous before they are put on the market. The most logical method of obtaining conclusive proof is to test a substance on human skin. This is * Presented at the December 5, 1950, Meet- ing, New York City. the so-called skin patch test which has become so important in recent years, especially with the new F.D.A. regulations. However, even before human be- ings can be exposed to.any new sub- stance it is wise to investigate the substance's toxicity on animals. In this way, any substance with marked toxicity can be eliminated from general use before humans are tested. Without going into detail of these preliminary studies, suffice it to say that several species of animals should be used, the material tested not only on the skin but also on the conjunctiva of the eye. Once a new substance has suc- cessfully passed the preliminary tests on animals, the final test may be performed, namely patch test- ing on a series of human subjects. Although the human skin patch test had been used for many years, it was largely through the efforts of Dr. Louis Schwartz, Retired Chief of the Division of Dermatoses, United States Health Service, that the human patch test was developed