PSEUDOMONADS IN COSMETICS 803 The preservation of formulations depend on many factors and the only reliable way to determine the resistance of a product to organism growth is to inoculate and test the product itself. In the author's laboratories a minimum incubation period of 13 weeks is utilized to determine the possible loss of preservation potency with time. Re-inoculation of the samples during incubation often demon- strates declining effectiveness of the preservation system. On one occa- sion during a prolonged product inoculation test the preservative re- pressed the inoculum for 17 weeks, but shortly thereafter vigorous growth and deterioration of the preparation ensued. Adaptation of pseudomonads can take place quickly, or very slowly over several weeks, and it is the latter which one has to watch (6). This may account for the sporadic spoilage reported in the field when control samples on shelves are in perfect condition (19). Preservation is interpreted by some as preventing the growth of micro-organisms. Does that definition fully protect the consumer? When pseudomonads introduced into a product survive, but do not multiply, can one really say, from what is known of the organism, that the preparation is adequately preserved? Kohn et al. (24), consider a preservative too slow-acting to be used in ophthalmic solutions if it could not sterilize a given pseudomonas suspension within one hour. Preparations are placed on preservation study to determine the ability of the product to withstand consumer use and abuse. The numbers of pseudomonads one finds in a product may have been introduced as incre- ments during use or developed as a result of growth. Regardless of the origin, the presence of a large number of pseudomonads over a significant period of time predicates a quality, health, and legal hazard. A small number of organisms surviving within a preparation may in time adapt to and proliferate in the product. It therefore follows that the only ade- quately preserved preparation is one that is essentially self-sterilizing. The sterilizing time however need not be measured in hours but in days or even weeks. The test organisms which the author employs have been taken from working formulations which were at one time contaminated, so that the screen contains strains adapted to and encountered by the laboratory's preparations. Screening methods should not be fixed since new strains of pseudomonads continually are isolated from domestic and foreign sources. It must be accepted that unforeseen and exceptional organisms or conditions may turn up during routine manufacture to inactivate a

8O4 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS preservation system. It is the author's view that the preservation ability of a product should be well in excess of the minimum necessary to inhibit the anticipated flora, and ideally one aims at a product that is self-sterilizing. In the author's experience, a self-sterilizing preparation can be achieved in most cosmetic and pharmaceutical products, without any significant increase in cost or loss of marketability. Sanitation Preservation should not be expected to compensate for insanitary or careless manufacturing or packaging. Aseptic production, with the ex- ception of eye preparations, is neither economical nor necessary. The product will therefore be microbiologically challenged, the magnitude and quality of which will vary with the ingredients, water supply, cleanli- ness, and season. This challenge may be most severe for it is here that continuing adaptation of the pseudomonads to the formulations takes place. The number of organisms from these sources has a bearing on their subsequent ability to proliferate within the preparation. Very small inocula have little opportunity to multiply. Large inocula in- crease the assault on the preservation system and increase the prob- ability that adaptive resistant pseudomonads will be introduced into the product. Ingredients themselves can be a potent source of contamination. In time the troublemakers are found, and microbial specifications are then added to future purchase contracts. Anionic detergents have frequently been a particular problem. Containers are rarely a problem but closures are. A liner may support growth or, by absorbing moisture from spat- terings of the product on the surface, alter the potency of the preserva- tives. Pseudomonads with borderline resistance can develop there, and once enhanced, infect and multiply within the preparation itself. Water supply is a particularly important source of Pseudomonas. The difficulty of eradicating this organism from water is underscored by the work of Belium and Koshi (25), who found that the resistance of Pseudomonas to chlorine ranged from 45-150 ppm. Water supply sys- tems should be monitored microbiologically, from the main to the manu- facturing tank inlet. Attention should be paid to the state of pipe work, valves, hoses, loops, and other sites of water stagnation. The water supply often contains a small number of organisms but without adequate control, water can issue from a tap or hose with thousands of pseudomo- nads and other gram-negatives/mi. A demineralizer may be a frequent source of this development. it provides a good medium for multiplica-