J. Soc. Cosmet. Chem. 23 45-71 (1972) ¸ 1972 Society of Cosmetic Chemists of Great Britain d 1 f ' b'lgy Fun amenta s o m•cro •o o ß 1 ß ß 3n re ation to cleansing 3n the cosmetics industry j. G. DAVIS* Presented on 18th November 1970 at the Symposium on 'Cleansing' organised by the Society of Cosmetic Chemists of Great Britain in Bournemouth, Hants. Synopsis--The fundamental MICROBIOLOGICAL aspects of modem methods of CLEAN- ING and STERILIZING equipment with special reference to the HAZARDS of COSMETIC PREPARATIONS. INTRODUCTION Almost every operation involving handling of foods and other materials which can be contaminated by organisms of human or other animal origin is in theory a hazard to health. In practice it is fortunately only a few which are known to be a serious hazard, for example contact with a person suffering from a certain disease, rewarming of processed meat dishes, etc. From the hygienic point of view therefore the degree of risk has to be assessed in relation to the cost of preventive measures. Not only the chances of contamination and infection, but the growth-permitting proper- ties of the commodity, the conditions of storage and its intrinsic nature from the microbiological point of view are equallyimportant. The more favourable the conditions for growth of micro-organisms in the product, the more effective should be the preventive measures adopted in the factory. For the present purpose we may define hygiene as a system of pre- cautions to maintain safety and keeping quality (KQ) in cosmetic products. *Consultant Microbiologist, 9 Gerrard Street, London, WIV 7LJ. 45

46 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS The causative agents in this problem are micro-organisms, so that scienti- fically it becomes a question of how we should kill them or control their growth. Basically the same principles and methods apply to both pathogens and fault-producing organisms {FPO). The trend of technology today is clearly towards aseptic packaging of liquid products, and more efficient use of refrigeration to maintain keeping quality. From the bacteriological point of view these two methods imply an increasing importance for heat-resistant spores, psychro-philic (-trophic) organisms and environmental sanitation. Hitherto industries employing sub-sterilization heat treatments have been particularly concerned with the numbers of thermoduric organisms in their raw materials but with the gradual change to UHT heat treatment methods these types will become of less importance. The status of hygiene in industry One of the greatest difficulties with which the new thinkers in industry have had to contend has been the long established general tradition that cleaning of any sort is a menial occupation and of no importance, so that the poorest types of labour were usually employed. This was a fallacy of the first magnitude, a fact which is now realized. No aspect of processing is more important than the cleaning and sterilizing of equipment. SIGNIFICANCE OF BACTERIA IN COSMETICS Safety and commercial or keeping quality The safety {freedom from any pathogens) and KQ of any product are quite distinct properties and must never be confused. A commodity may be safe but of poor KQ and it can be dangerous but commercially satisfac- tory. Laboratory control tests must therefore cover both aspects. A product may have such physical and chemical properties that one or both types of test are unnecessary. Dryness and acidity are in practice the dominant conditions in this respect, dryness for all micro-organisms and acidity for all pathogens and most bacteria. Acidity is no deterrent for yeasts and moulds, and in fact often favours them. In general it may be said that cosmetic preparations, like foods, should either be free from micro-organisms capable of damaging the product, or