ORGANISM GROWTH IN COMMERCIAl, COSMETICS 393 quaternary ammonium salt and the effectiveness of sorbic acid when substi- tuted for the quaternary ammonium salt/phenolic ester combination but not for the quaternary salt alone could best be resolved by a comparison of the complete formulations of both preparations. The results of testing two vanishing creams and two hair grooming preparations arepresented in Table 5 and depict a situation similar to the one discussed with the cleansing creams. Both vanishing creams appeared to be of the same composition from our limited knowledge and since neither cream supported organism growth with a parahydroxybenzoate system or with a sorbic acid preservative system, no difference in composition was suggested by differing resistances to organism growth. The hair grooming preparations also appear to be the same from the composition information available and although neither preparation supported organism growth when preserved with sorbic acid, Hair Groom 1 with aparahydroxybenzoate ester system supported heavy growths of d/ternaria tenuis, dspet•i//us niger, Penicillium chrysogenum and Rhizopus nigricans, while Hair Groom 2 with parahydroxybenzoate preservatives supported only slight to moderate growths of dllernaria tenuis, Mucor plumbeus and Rhizopus nigricans. Here, again, a comparison of' complete formulations is needed to explain observations which do not coincide when the hair grooming preparations are assumed to be identical on the basis of similarities of type and concen- tration of emulsifiers and preservatives. This short study suggests that: 1. The results of an organism inhibition test of a preservative in a labo- ratory culture medium containing a nonionic surfactant are not always typi- cal of the behavior of that preservative in a finished cosmetic emulsion which includes the preservative and surfactant used in the test. Since little in the way of proven correlation exists between the results of such component testing and preservative behavior in a particular finished prod- uct is best determined at the present time by testing the finished product itself for its resistance to organism growth. 2. Combinations of parahydroxybenzoate esters and parahydroxyben- zoate esters with dehydroacetic acid, used to preserve many cosmetic products, will probably provide adequate protection for cosmetic emulsions even in the presence of nonionic surface active agents. Where these pre- servatives fail, sorbic acid appears to provide adequate protection. SUMMARY Three typical cosmetic emulsions based on nonionic surfactants xvere prepared and preserved first with a mixture of methyl and propyl para- hydroxybenzoates and then with sorbic acid. Testing of these preparations with six different micro6rganisms for a period of three months indicated that the phenolic preservatives were more effective in finished preparation

394 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS than would be expected in light of some studies based on component testing which have appeared in recent technical literature. Where the para- hydroxybenzoate esters failed in preserving these samples, sorbic acid ap- peared to provide adequate protection. Eighteen commercial cosmetic emulsions based on nonionic surfactant systems were obtained from commercial sources in two almost identical groups: one group contained the preservative currently used by the manu- facturer to protect it, while the other group used sorbic acid as its preserva- tive. Both modifications of these commercial cosmetics were tested with nine micro•3rganisms for their resistance to organism growth during a period of three months. Results of this evaluation reinforced the findings of the previous study in that the parahydroxybenzoate esters were more effective in finished formulations than had been predicted from their performance in component testing and that sorbic acid appeared to afford adequate pro- tection in most cases where the phenolic esters failed. Both sections of this study support the contention that the preservation of nonionic cosmetic emulsions depends upon more factors than interaction between preservative and nonionic surfactant and that the only consistently reliable way to determine the resistance of a cosmetic emulsion to organism growth is to test the finished product itself. Acknowledgement: The microbiological testing of all of the samples connected with this study was performed by Drs. Linwood Tice and Martin Barr of the Philadelphia College of Pharmacy and Science. (9) (10) (11) (12) (13)• (14) (15) (16) (17) (18) (•9) (_00) (2l) REFERENCES (1) Beckett, A. H., and Robinson, A. E., Soap, Perfumet7 & Cosmetics, 31,454 (1958). (2) Fisher, C. V., rim. 5 e. Public Health, 32, 389 (1942). (3) Gershenfeld, L., and Wilin, B., zlm. 5 e. Pharm., 113, 215 (1941). Gershenfeld, L., and Peristein, D., Ibid., 113, 89 (1941). (4) Gregg, R. M., and Zopf, L. C., 5 e. zlm. Pharm. ,fssoc., Sci. Ed., 40, 390 (1951). (5) Bolle, A., and Mirimanoff, A., JI. Pharm. and Pharmacol., 2, 685 (1950). (6) Hadgraft, J. W., Ibid., 6, 816 (1954). (7) Lawrence, C. A., and Erlandson, A. L., 5 e. zlm. Pharm. zlssoc., Sci. Ed., 42, 352 (1953). Erlandson, A. L., and Lawrence, C. A., Science, 118, 274 (1953). (8) deNavarre, M. G., )t. Soc. Cosmetic Chemists, 8, 68, 371 (1957). deNavarre, M. G., and Bailey, H. E., Ibid., 7, 427 (1956). Lord, C. F., and Husa, W. J., 5 e. ztm. Pharm. zlssoc., Sci. Ed., 43, 438 (1954). Barr, M., and Tice, L. F., Ibid., 46, 442 (1957). Aalto, T. R., Firman, M. C., and Rigler, N. E., Ibid., 42, 449 (1953). Patel, N. K., and Kostenbauder, H. B., Ibid., 47, 289 (1958). Wedderburn, D. I,., •7. Soc. Cosmetic Chemists, 9, 210 (1958). Higuchi, T., and l,ach, J. L., JI- .4m. Pharm. •ssoc., Sci. Ed., 43, 465 (1954). Hall, C. S., and deNavarre, M. G., Proc. Sci. Sect. Toilet Goods zlssoc., 27, 29 (1957). Weiden, M. J. H., and Norton, L. B., )t. Colloid Sci., 8, 606 (1953). Rdzols, E. J., Grtmdy, W. E., Kirchmeyer, F. J., and Sylvester, J. C. 5 e. zlm. Pharm. zlssoc., Sci. Ed., 44, 613 (1955). Tice, L. F., and Barr, M., .7. Soc. Cosmetic Chemists, 9, 171 (1958). Fischer, E., and Szabo, L. J., Atrzneimittel-Forsch., 8, 31 (1958). Klarmann, E.G., Arm. Perfumer zfromat., 73, 53 (1959). Maruzzella, J. C., and Henry, P. A., 5 e. Arm. Pharm. zls•oc., Sci. Ed., 47, 471 (195.8). Sagarin, E., Editor, "Cosmetics-Science and Technology," New York, Interscience Publishers, Inc. (1957), p. 1036. (23) Sagatin, E., Editor, Ibid., 1052.