GROWTH INHIBITION OF CORYNEFORM BACTERIA 217 Table III Results of a Comparison of Three Spray Preparations Product A: contains 2,4,4'-trichloro-2'-hydroxydiphenyl ether (0.26%, solubilized) Product B: contains HGQ (0.3%) Product C: placebo Sniff test AB 6 h: no difference in sniff potential AB 12 h: no difference in sniff potential A)(B 24 h: no difference in sniff potential Self-assessment Evaluation of the questionnaire revealed that the subjects reported no preference for either of the two products. Sniff test B)(C 3 h: B significantly better than C in sniff potential B)(C 12 h: B significantly better than C in sniff potential B)(C 24 h: B significantly better than C in sniff potential Self-assessment Evaluation of the questionnaire revealed: After 3 h and 12 h the subjects clearly preferred B. After 24 h the subjects reported that B seemed more effective. contained in a i-liter water sample under given test conditions (time, temperature, etc.) (23). The BOD subscript indicates the test period in days. The BOD5/COD ratio is often formed, which represents the relative biological degradability. The results of these types of test are naturally subject to variations. The information obtained on the degradation behavior, i.e., return of the component substance to the natural cycle, does, however, allow an estimation of the impact on the environment. Two grams of each product were mechanically shaken for 24 hours, the undissolved fraction separated, and the chemical and biochemical oxygen demand of the dissolved components determined. For this reason, the results are not related to the product itself but to the aqueous solution prepared as described. The data permit estimation of the degradability on the basis of the BOD5/COD ratio (4). Table IV shows that the soluble fraction of 2,2'-methylenebis(6-bromo-4-chlorophenol) has a very poor biological degradability. For 2,4,4'trichloro-2'-hydroxydiphenyl ether there is apparently a total inhibition of degradation by the microbiocidal effect. The natural product active substances named above have an acceptable degree of de- gradability. The degradation products are only CO 2 and H20 , as HGQ does not contain any nitrogen. (Also see Figure 3.) Furthermore, this finding indicates that although the synergistically acting HGQ mixture has a selective bactericidal effect, it is degraded naturally after use, which is not true of the first deodorant generation. DISCUSSION A major component of odor production is eliminated by growth inhibition of coryne- form bacteria. It seems probable that the coryneform bacteria do not themselves produce

218 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table IV Test Results Sample name Chemical Biochemical oxygen oxygen demand demand COD BOD 5 (mg/1) (mg/1) BODs/COD Glyceryl monolaurate (H) Farnesol (G) Phenoxyethanol (Q) HGQ 2,4,4'-Trichloro-2 '-hydroxydiphenyl ether 2,2'-Methylenebis-(6-bromo-4-chlorophenol) 1755 1069 483 217 3205 975 2880 728 453 5 778 15 0.61 O.45 O.3O O.25 -- 0.02 61 45 3O 25 0 2 E lOO 90 8o 70 6o 50 40 30 20 10 0 0 [] Glycerylmonolaurata [] Phenoxyethano! [] Farnesol [] HGQ 10 15 time periods [5 days] Figure 3. Biological degradabitity of HGQ and its ingredients (computed from BODs/COD). short-chain fatty acids (18) but that their enzymes release these compounds from apocrine sweat or physiological skin surface !ipids. Apparently only coryneform bacteria are capable of releasing odorous substances such as short-chain fatty acids (19) or steroids. It is remarkable that the bacteria population of the axillae is distinguished by two types of flora. There is a coccal dominance and a corynebacteria dominance (at least 75% of all aerobic bacteria are of the coryneform type). The population density of the coryneform flora is six times that of the coccal dominance (11). In an application concentration of 0.3% to 0.6%, HGQ acts as an effective deodorant