HYGIENIC MANUFACTURE AND PRESERVATION 721 1. INTRODUCTION 1.1 The problem of manufacturing hygiene Every responsible person concerned with the manufacture of toiletry and cosmetic preparations is aware of the need for clean operating condi- tions. The need to include a preservative in order to prevent microbial spoilage of susceptible products is also universally accepted. Good hygiene and efficient preservation call for detailed consideration of many complex factors. This monograph, prepared by a working party on behalf of the Society of Cosmetic Chemists of Great Britain, has been ratified by the Council of the Society. It is a guide to assist in solving the various problems likely to arise. Fortunately there is little evidence that actual harm has ever been experienced by users in consequence of infection transmitted by a cosmetic or toiletry product. Nevertheless, complacency could be dangerous. Microbial deterioration does not always give rise to obvious changes in a product and identification of the source of skin infections is often difficult. The importance of recognizing and excluding product contamination is underlined by the fact that many species of micro-organisms once believed to be harmless are now known to be capable of assuming a pathogenic role. It is therefore incumbent upon the manufacturer to institute an adequate routine of microbiological quality control. Monitoring the microbiological status of toiletries and cosmetics should preferably be accorded comparable importance to the control of chemical purity. These contentions imply that personnel adequately trained in microbiology should be available to the control laboratory establishment of a toiletries or cosmetics manufacturer. A microbiologist engaged in quality control should have adequate authority to discharge his duty within the provisions of the Code of Good Practice for the toiletry and cosmetic industry. Products under test for microbial contamination may need to be held for several days before release for sale. 1.2 Standards for microbial contamination If it were feasible to apply an unqualified requirement that every product should be sterile, or, in other words, totally devoid of living micro-organisms, the control problem would be relatively simple. Despite the theoretical attractions of this approach, however, it must be recognized that cosmetic preparations are not usually sterile and the achievement of such a standard would result in a great increase in production costs. There is no evidence that this would be justifiable in terms of any real additional

722 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS safeguard to the public. It is therefore necessary to examine xvhether special circumstances exist for which an absolute standard of sterility is warranted and, in other cases, to what extent the requirement may reasonably be relaxed. Some authorities favour an acceptance target representing a particular level of microbial contamination such as 100 micro-organisms per gramme. Contamination levels are apt to vary widely in a comparatively short space of time and the particular species of micro-organisms present may be far more significant than the actual numbers. This approach without qualifica- tions therefore has little to commend it. Standards which apply the most stringent requirements when these are particularly appropriate and which are less rigid in other circumstances, will give adequate protection for the consumer without a prohibitive increase in manufacturin• costs. A set of Standards is being prepared by the joint Select Committee of the Toilet Preparations Federation Ltd. and the Society of Cosmetic Chem- ists of Great Britain. To avoid confusion, separate recommendations are omitted from this monograph, which therefore deals mainly with methods for achieving a satisfactory level of manufacturing hygiene and techniques for establishing preservation capacity and for monitoring the extent of microbial contamination. 1.3 Definitions For the purpose of this monograph, "toiletry" and "cosmetic" are taken to be synonymous. All temperatures are given in degrees Celsius. 2. GENERAL CONSIDERATIONS 2.1 Compliance with standards Standards need to be considered in relation to the efforts necessary to achieve them and the methods to be employed for verifying compliance. For example, the selection of raw materials and packaging components free from or having a low incidence of microbial contamination will matefid ally help to avoid a high level of contamination in the finished product the bacterial content of water used in manufacturing processes is of partic- ular importance in this connection. Similarly, processing conditions should be carefully scrutinized to limit adventitious contamination. Factory design and lay-out, personnel training and arrangements for cleaning