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.

90 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table ¾I Lotion Shampoo Microorganism Count Per Gram of Product Organism and Initial Preservative System Count 7 Day 14 Day 21 Day 28 Day Twenty-eight Day Preservative Test #1 A.n. 1.4 x 106 1700 300 0 0 C.a. 6.4 x 106 1300 100 0 0 Methylparaben 0.1% E.c. 3.4 x 106 100 0 0 0 Propylparaben 0.03% S.a. 8.5 x 106 100 0 0 0 P.a. 4.0 x lO 6 1oo o o o #2 A.n. 1.4 x 106 100 0 0 0 C.a. 6.4 x 106 100 0 0 0 Quaternium-15 0.3% E.c. 3.4 x 106 100 0 0 0 S.a. 8.5 x 10 6 100 0 0 0 P.a. 4.0 x 106 100 0 0 0 #3 A.n. 1.4 X 106 100 0 0 0 C.a. 6.4 x 106 100 0 0 0 DMDM Hydantoin 0.3% E.c. 3.4 x 106 100 0 0 0 (80øC) S.a. 8.5 x 106 100 0 0 0 P.a. 4.0 x 106 100 0 0 0 //4 A.n. 1.4 x 106 1600 500 0 0 C.a. 6.4 x 106 3700 100 0 0 DMDM Hydantoin 0.15% E.c. 3.4 x 106 100 0 0 0 (Room Temperature) S.a. 8.5 x 106 100 0 0 0 P.a. 4.0 x 106 100 0 0 0 #5 A.n. 1.4 x 106 100 0 0 0 C.a. 6.4 x lO 6 1oo o o o Methylparaben 0.1% E.c. 3.4 x 106 100 0 0 0 Propylparaben 0.1% S.a. 8.5 x 106 100 0 0 0 P.a. 4.0 x 106 100 0 0 0 Twenty-eight Day Preservative Test (Rechallenge) #3 A.n. 2.1 X 106 0 0 0 0 C.a. 1.8 X 106 0 0 0 0 DMDM Hydantoin 0.3% E.c. 1.0 x 106 0 0 0 0 (80øC) S.a. 1.4 x 106 0 0 0 0 P.a. 4.0 x 106 0 0 0 0 if4 A.n. 2.1 x 106 0 0 0 0 C.a. 1.8 x 106 0 0 0 0 DMDM Hydantoin 0.15% E.c. 1.0 x 106 0 0 0 0 (Room Temperature) S.a. 1.4 x 106 0 0 0 0 P.a. 4.0 X 106 0 0 0 0 (o) denotes no growth