FUNDAMENTALS OF MICROBIOLOGY IN RELATION TO CLEANSING 69 Microbiological standards There is now considerable interest in microbiological standards for foods and some other products. This is a subject into which which no-one should enter without experience of the product as well as a knowledge of micro- biology. It is very easy to lay down standards which are impracticable, unnecessary or even just ridiculous. The basic requirements are (i) careful standardization of all aspects of sampling, transporting and storage of the sample, (it) standardization of laboratory testing, (iii) consideration of age of product, (iv) allowance for error of test, (v) selection of appropriate tests, (vi) proper interpretation of results. Standards should only be advisory, and are mainly a matter between buyer and seller. They can be particularly useful for purchasers of basic materials. For general quality control purposes standards set for pro- duction in the factory must be related to the microbiological behaviour of the product between production and final use. Some suggested standards are given in Table VII. In U.S.A. the F.D.A. have become very concerned with the problem of microbiological contamination of cosmetics, especially in relation to Ps. aeruginosa. It can be anticipated that they will shortly issue standards for this purpose, which will obviously be of the greatest importance for the British export trade. Table VII. Tentative microbiological standards for cosmetic preparations g-! or ml-! Satisfactory Doubtful Unsatisfactory Total colony count* 1 000 1 000-10 000 10 000 Presumptive coltforms* 10 10- 100 100 Faecal colt 1 1- 10 10 Staph. aureus* 1 1- 10 10 Ps. aeruginosa* 1 1- 10 10 Salmonella Not detectable in 100 g Fault producing organisms Impossible to generalise *=first priority in laboratory control work. Tests and standards for the efficiency of cleansing Cleansing consists of two treatments--physical cleaning and sterilization or disinfection. There is a steady trend towards combining these.

70 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Cleaning or detergency There is usually no need to assess this alone, or to set standards. If required, an assessment of residual organic matter can be obtained by allowing contact with a reactive chemical, e.g. chlorine, for a given time and then determining the loss in available chlorine. A simple 'spot test' is to take advantage of the fact that iodine, as in iodophors, stains organic matter a yellowish colour. Iodophors do not stain clean glass, stainless steel, etc., although allegations have been made to this effect. Any staining indicates a greasy or protein film, hard water scale, etc. Residual bacteria or 'sterility' If equipment has been properly cleaned and 'sterilized' the number of bacteria left will not exceed 1 per cm2 area by a swab test or 1 per ml capacity by a rinse test (14). These tests are therefore quite adequate to assess the efficiency of cleansing in a general sense. It can be assumed under ordinary working conditions that if these results are satisfactory (i.e. less than 1 colony per cm2 or ml) then all pathogens will have been killed or removed. It is also unlikely that FPO will have survived in sufficient numbers to cause trouble, but as a safeguard 1 000 cm 2 may be swabbed and the 20 ml Ringer solution added to a suitable enrichment medium (Table VI) for the cultivation of specific pathogens or FPO. Alternatively $ ml could be added to (i) mannitol salt broth (for Staphylococcus), (ii) selenite broth (for Salmonella), (iii) acetamide broth (for Pseudomonas aeruginosa), {iv) buffered citric acid broth pH $.$ {for yeasts and moulds), (the appropriate confirmatory tests must be made) but such a refinement is only necessary when a relevant problem arises. (Received: 4th $el)tember 1970• REFERENCES (1) Infantile gastroenteritis. Brit. Med. f. 3 2 (1970). {2) Johnson, S. A.M., Guzman, M. G. and Aguilera, C. T. Candida {Monilia) albicans. Effect of amino acids, glucose, pI-I, chlortetracycline, dibasic sodium and calcium phosphates and anaerobic and aerobic conditions on its growth..4 rch. Derrnatol. Syphilol. Chicago 70 49 (1954). (3) Anderson, N. A., Sage, D. N. and Spaulding, E. H. Oral moniliasis in newborn infants. .4rn. J. Dis. Child. 67 450 (1944). (4) Ludlam, G. B. and Henderson, J. L. Neonatal thrush in a maternity hospital. Lancet, l, 64 (1942). (5) Monori, S. and Varga, E. Antimicrobial effect of some cleaning materials used in the food industry. Budapesti Muszaki Egyet. Elm. Kern. Tansz., D S.•I. 26, 2211 (1962). (6) Knafelman, P. Improving the effectiveness of detergents. Mol. Prom., 24 29 (1963). D.S.A. 26 684. (7) Davis, J. G. The cleansability of various materials. Medical Officer, llO 299 (1963). {8) Davis, J. G. "Chemical sterilization" in Prog. Industr. Microbiol. ed. Hockenhull 8 141 (1968). (Churchill, London).