872 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS those of low moisture content can be classified as products which are not microbiologically susceptible. There appears to be little danger of user contamination becoming a hazard, or of the user contamination causing undesirable odor or physical changes in such products. Preservatives, which do not function in such systems, may not be necessary for either product or consumer protection. Our results showed that the level of consumer contamination of these products was very low and innocuous. The same is essentially true of very low moisture pressed products which are applied dry, e.g., powder blushers, powder eyeshadows, face powder, pressed powder. Our experience has been that the consumer contamination of all types of pressed products and stick products is on the surface only. Products which are applied by wetting may support microbiological proliferation depending on composition and the conditions of use, that is, remaining wet. In these types of products, preservatives play a more useful role. Reasonable levels of personal hygiene by the consumer regarding sponges, brushes or other wet applicators would seem the best method of reducing the microbial load applied to the skin when these types of products are used. Because of the method of use of liquid eyeliner (small skin area and small brush), we observed a minimal contamination level by the user. This may explain why the product with marginal preservative levels of 0.075% methyl paraben and 0.04% propyl paraben protected the product during the study even though this type of unpreserved formula was microbiologically susceptible. Since this type of product has an extended consumer use life, a more optimum preservation level is indi- cated. We found coagulase-positive Staphylococcus in unpreserved units after use, lending importance to adequate preservation. Based on these laboratory preservative studies, the higher preservative level used in the liquid liner study should protect against gross consumer contamination and abuse for an extended period of time. It is interesting that heavy levels of contamination were not observed in our study as reported for used eye make-up products by Wilson (2). Emulsion products which are applied by scooping out the product with the fingers are exposed to a heavier inoculation. A greater variety of contaminants was found in these products and yeasts and fungi grew copiously in the unpreserved moisturizing lotion product. While it was demonstrated that despite heavy consumer inoculation, the emulsion products studied could be adequately preserved and appeared to be self-

MICROBIOLOGICAL PROFILE OF COSMETICS 873 sterilizing, the situation is not always this simple. Other emulsion products have presented extremely difficult preservation problems. We do not like the term "self-sterilizing" and suggest that it not be used in reference to evaluating preservative systems for cosmetics. In order to determine if a cosmetic preservative system is actually self- sterilizing requires a study of microbes other than aerobic mesophiles. At the present state of knowledge, it is our opinion that a negative aerobic plate count (APC) indicates a cosmetic product of excellent micro- biological quality. Therefore, we suggest "negative by APC" as a possible substitute for self-sterilizing. It should be pointed out that the purpose of this study was not to recommend particular preservative systems for the products similar to those reported on, nor to endorse those preservatives which happened to be used. Also, it is not suggested that the subjects who participated in this study represent all consumers, or that the consumer inocula found represent the potential microbiological flora of consumers in the large. Further studies seem warranted to evaluate fully the problem of consumer contamination as it relates to product preservation and con- sumer safety. SUMMARY In summary, it may not be essential to add preservatives to non- aqueous products or dry applied pressed products of low moisture content as they are not susceptible to microbiological proliferation. Aqueous emulsion products do require the use of preservatives to protect against consumer contamination. Preservative systems were evaluated for those emulsion products studied which made them microbicidal to the user contamination encountered. (Received June 15, 1972) REFERENCES (1) Tenenbaum, S., Pseudomonads in cosmetics, •1. Soc. Cosmet. Chern., 18, 797-807 (1967). (2) Wilson, L. A., et al., Microbial contamination in ocular cosmetics, Arner. J. Opthalrnol., 71, 1298-1302 (1971).