88 .JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS three other common preservatives, Methylparaben, Propylparaben and Quaternium-15, were included for comparison purposes. (All concentrations of DMDM Hydantoin referred to hereafter in this paper are of the 55% aqueous solution.) The nineteen samples were actually variations of the following four typical cosmetic products: (a) Lotion Shampoo (b) Liquid Hair Conditioner (c) Henna Cream Conditioner (18.1% animal protein) (d) Hand Cream Special procedures used for preparing the different formulations were as follows: Formula Preservative Code No. Product Used Formulation Procedure 1. Lotion Shampoo Methylparaben (0.1%) Propylparaben (0.03%) 2. Lotion Shampoo Quaternium-15 (0.3%) 3. Lotion Shampoo DMDM Hydantoin (0.3%) 4. Lotion Shampoo DMDM Hydantoin (0.15%) 5. Lotion Shampoo Methylparaben (0.1%) Propylparaben (0.1%) 6. Liquid Hair Methylparaben (0.1%) Conditioner Propylparaben (0.03%) 7. Liquid Hair Quaternium-15 (0.15%) Conditioner 8. Liquid Hair DMDM Hydantoin (0.15%) Conditioner 9. Liquid Hair DMDM Hydantoin (0.15%) Conditioner 10. Henna Cream Control Conditioner 11. Henna Cream Methylparaben (0.1%) Conditioner Propylparaben (0.1%) 12. Henna Cream Quaternium-15 (0.15%) Conditioner 13. Henna Cream DMDM Hydantoin (0.25%) Conditioner 14. Henna Cream DMDM Hydantoin (0.50%) Conditioner 15. Hand Cream Control 16. Hand Cream Methylparaben (0.1%) Propylparaben (0.1%) 17. Hand Cream Quaternium-15 (0.15%) 18. Hand Cream DMDM Hydantoin (0.2%) 19. Hand Cream DMDM Hydantoin (0.4%) Heated to 80øC. to solubilize the Parabens. Heated to 80øC. to solubilize the Quaternium-15. Heated to 80øC. Actually not necessary for DMDM Hydantoin. Mixed at room temperature. Heated to 80øC. to solubilize the Parabens. Heated to 80øC. to solubilize the Parabens. Heated to 80øC. to solubilize the Quaternium-15. Heated to 80øC. Actually not necessary for DMDM Hydantoin. Mixed at room temperature. Mixed at room temperature. Heated to 80øC. to solubilize the Parabens. Heated to 80øC. to solubilize the Quaternium-15. Mixed at room temperature. Mixed at room temperature. Mixed at room temperature. Heated to 80øC. to solubilze the Parabens. Heated to 80øC. to solubilize the Quaternium-15. Mixed at room temperature. Mixed at room temperature.

DMDM HYDANTOIN AS A COSMETIC PRESERVATIVE 89 DMDM Hydantoin was dissolved in the aqueous fraction of the four typical cosmetic formulations shown in Table I through IV, at concentrations of 0.15-0.5%. EFFECTIVENESS Each test formulation was inoculated with the microorganisms shown in Table V, using the test procedure described in United States Pharmacopeia (1). The bacteria were cultivated on trypticase soy agar slants for 24 hr at 35øC. The ½. albicans and Table V Test Organisms Aspergillus niger ATCC 16404 Candida albicans ATCC 10231 Escherichia coli ATCC 4352 Staphylococcus aureus ATCC 6538 Pseudomonas aeruginosa ATCC 9027 Aspergillus mold were cultivated on sabouraud dextrose agar at 25øC for 48 hr and 1 wk, respectively. The bacteria and the yeast were harvested by washing the cells from the slants with sterile saline. Aspergillus was harvested by gently rubbing the spores from the slant with sterile saline containing 0.05% Polysorbate 80. The number of colony-forming units per ml were determined in each case with each organism. Twenty-gram portions of the samples were placed into sterile plastic cups--one for each organism--and inoculated with the test organism. The containers were incubated at 25øC for a total of 28 days (d) with periodic examination. Examination was made initially, after 7, 14, 21 and 28 d. Plate counts were prepared using trypticase soy agar for the bacteria and potato dextrose agar for the yeasts and molds. RESULTS AND DISCUSSION The Results of the Microorganism counts on the various test formulations are shown in Tables VI-IX. Table VI Lotion Shampoo The Parabens (Sample//1) and DMDM Hydantoin (Sample//4) required over 14 days to reduce mold (A.n.) and yeast (C.a.) count to 0. All other systems were effective at the 7 day count period. Sample//4, DMDM Hydantoin was effective at the end of 7 days on the rechallenge test.