32 JOURNAL OF THE SOCIETY OF COSMETIC CHEM1STS even dangerous. These materials are best sterilized by a gaseous or heating process before formulation. Solids of biological origin, including egg and milk products and dried animal and plant extracts, may also contain pathogens, including salmonellae, E. coli and staphylococci. Spoilage of the solid raw matehal itself is largely due to mould growth on the surface due to improper storage with inadequate coverings in a damp enviromnent or under conditions of fluctuating temperature. Powders Spoilage of products in powdered form due to visible mould growth also occurs under damp conditions. Again the possibility of illness due to micro- bial contamination is an important consideration and it is particularly necessary to ensure that topical preparations do not contain Clostridia spores. There is no clear evidence of a relationship between the presence of contaminants and irritation due to cosmetic powders but more than a few hundred organisms per gram is undesirable and powders for use on broken skin should be prepared from sterilized raw materials. This precaution also applies to those powders and other solid cosmetics which are intended to be applied in the region of the eyes. Tablets, pastilles and lozenges Visible spoilage of tablets, generally manifested as surface discoloura- tion, may be caused by the growth of moulds. Spores from the environment, container or tablet itself may find sufficient moisture to initiate growth on the tablet surface even under apparently dry conditions. For instance, fluctuations in temperature or variations between those in different parts of the container can cause corresponding changes in rh. If an rh of around 70•o is exceeded where mould spores reside then spoilage is possible, although this may occur slowly as a high enough rh may be achieved only spasmodically. In experiments with Paracetamol Tablets, B.P. we have found that, while spoilage could be prevented by attention to storage con- ditions and the value of preservatives was limited, the incorporation of 0.1•o propyl p-hydroxybenzoate retarded the onset and extent of mould growth, even under damp storage conditions, in laboratory and large-scale trials (24). Interest has recently been shown in the carriage of contaminating pathogens by products of this type. Synthetic drugs in tablet form usually carry less than 100 organisms per tablet but those compounded with natural drugs may contain up to 105 organisms, often Gram-positive spore-

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