146 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table II Ratings According to Urbach's System Testing Name of the Agent Rating Red Veterinary Petrolatum Red Veterinary Petrolatum with B-2 2-Ethyl hexyl salicylate 2-Ethoxy-p-methoxy cinnamate Homomenthyl salicylate Isobutyl-p-aminobenzoate p-Aminobenzoic acid 2-Hydroxy-4-methoxy benzophenone-5-sulfonic acid Good Oood Fair Poor Poor Poor Fair Fair Method The brass plate was superimposed on Urbach's system in the Petri dish and held firm with the help of two small pins. Fifty mõ of each sunscreen formula was first daubed in the numbered holes and rubbed in to form what appeared to be an even layer. This technique is a source of error in this procedure. Similarly, 50 mg of the polyethylene glycol 1500 was rubbed in the central hole. The dish was then exposed to the Westinghouse suniamp for 20 minutes at a distance of 25.5 cm. The degree of change in color was recorded at the central hole since polyethylene glycol 1500 allows all the radiant energy to pass and be absorbed by the system. This experiment was repeated five times, and the results were reproducible. On the basis of change in color of the substrate, the sunscreen agents were classified as good, fair, and poor. Results appear in Table II. DISCUSSION AND CONCLUSION It can be readily seen that the results obtained by the new method do not confirm those obtained by the spectral absorption method. For example, 2-hydroxy-4-methoxy benzophenone-5-sulfonic acid has a good ultraviolet absorption value but proved to be less absorbant by the new method, and 2-ethyl hexyl salicylate proved to be more absorbant by this method than by ultraviolet spectrum. Red Veterinary Petrola- tum, although it did not absorb well during spectrophotometric test, nevertheless, proved to absorb very well in the proposed method. For absolute surety, actual testing on a fairly large number of human subjects may be the only way. The advantages of the proposed method are: (a) product can be tested in its final form, (b) simplicity, and (c) low cost.

EVALUATION OF SUNSCREEN AGENTS 147 With further work, a quantitative method for measuring the color change can be developed, thus making this test more precise. ACKNOWLEDGMENT The author's appreciation is extended to Drs. Louis A. Luzzi and D. E. Cadwallader for their helpful suggestions. (Received August 8, 1966) REFERENCES (1) Urbach, F., Measuring exposure to ultraviolet rays, J. Am. Med. Assoc., 182, 1, 35 (Oct. 6, 1962). (2) Giese, A. C., Christensen, E., and Jeppson, J., Absorption spectra of some sunscreens for sunburn preparation, J. Am. Pharm. Assoc. Sci. Ed., 39, 30 (1950). (3) Giese, A. C., and Wells, J. M., Sweat and water-resistance sunburn preparation, Ibid., 35,208 (1946). (4) Knox, J. M., Sunscreens and their usefulness, Am. Perfumer Aromat., 75, 8, 42 (August, 1960). (5) Parke, R. F., and Sperandio, G. J., Evaluating sunscreen lotions, Drugs Std., 27, 1, 9 (1959). (6) Riegelman, S., and Penna, R. P., Effect of vehicle components on the absorption char- acteristics of sunscreen compounds, J. Soc. Cosmetic Chemists, 11, 5 (1960). (7) Urbach, F., News section, Medical World News, $, 122 (Aug. 14, 1964).