MICROBIOLOGICAL SPOILAGE 1N PHARMACEUTICALS AND COSMETICS 733 bearing bacteria, per tablet. Large numbers of enteric pathogens such as salmonellae have also been found and tablets containing biological products have been incriminated in outbreaks of salmonellosis (25). Pastilles and lozenges of the boiled sweet type are not generally found to suffer from microbial spoilage as heating during manufacture has a sterilizing action and often individual dry wrappings are used to prevent surface contamination. However, when pastilles are dusted with starch powder, moulds may be introduced and these can give rise to discolouration under poor storage conditions. Solid cosmetics Lipsticks often contain preservatives but some are still subject to mould 'blooms'. Mould grows on the lipstick while it is inside the lipstick case, often after the product has become moistened by breath during use. Moisture, perhaps from saliva, may also initiate growth in preparations of mascara which often contain many bacteria. There is also a danger of con- tamination via the brush which can pick up organisms from the skin during use and similar dangers are present with solid cakes of make-up. Preser- vatives have limited use in this situation, perhaps because they are ad- sorbed onto the solid material. In addition their concentration must be limited for fear of irritation to the eyes. Packaging materials Containers for pharmaceuticals and cosmetics are becoming increasingly elegant and are now made from a large variety of materials, particularly plastics. This should result in a reduction in microbial spoilage because plastics are not biodegradable like the cellulose materials, paper and card. In addition the latter, being absorbent, soak up liquids thus providing a substrate for moulds. In any case, liners of paper and card and cork closures often contain many micro-organisms and therefore frequently are a source of mould contamination whereas plastic closures are free from this defect. However, plastics suffer from some disadvantages. They are porous to varying degrees and some allow the diffusion of oxygen and carbon-dioxide and may thus facilitate microbial growth in the packed product. They also encourage condensation of water and, if mould spores are present, can facilitate spoilage by these organisms. Soap, for instance, gives off moisture, and, if wrapped with an impermeable plastic over paper or card, may be- come discoloured due to mould growth on the damp paper. Sometimes

734 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS paper wrappings can be protected from spoilage by the incorporation of a preservative into them, but this is not entirely without difficulties. CONCLUSIONS Microbial spoilage of pharmaceuticals and cosmetics is significant both from health and economic viewpoints and obviously should be prevented. It is dear that disease-causing organisms must be excluded, although sometimes it may be difficult to decide if an opportunist pathogen will be troublesome in a specific product. The situation with regard to spoilage micro-organisms, in the strict sense, is less dear as much is still to be learnt about the biochemical and microbiological mechanisms involved certainly there is room for further fundamental studies in this fascinating field. Deleterious changes will be avoided, of course, if all microbes are excluded from a product but it is not practicable to treat most pharma- ceuticals and cosmetics as sterile products. Indeed, neither may this be desirable as we do not live in a sterile world and products, like human beings, must also survive in the presence of some micro-organisms. This raises the difficult question of how many organisms of what sort are accept- able in a given product. Several millions of organisms per gram are usually present in foods before decomposition reaches the point where it is detect- able to the senses (26) and this is generally also true of liquid pharma- ceuticals and cosmetics. It also applies to more solid products where, although organisms may be concentrated at a focus, nevertheless they have to be present in some millions before the resulting colonies become trouble- some. Contamination of pharmaceuticals and cosmetics with fewer cells may herald populations of spoilage potential if the contaminants can multiply this is a matter of experience and experiment. Preservatives cannot always be relied upon to prevent the multiplication of micro- organisms because the ideal universal preservative does not exist and there- fore the choice for each product is an individual, and often not entirely successful, matter. In any case preservatives are no substitute for good hygiene during production. Lower viable counts in a product may represent the survivors of a larger population which has already caused decomposition but this is often obvious. A few hundred viable organisms per gram are generally of little consequence. The presence of many thousands of organisms, however, is usually a matter of concern as a count of this magnitude frequently in- dicates that spoilage will occur. To attempt to define more precise numerical