THAT UNWANTED COSMETIC INGREDIENT--BACTERIA 135 Frequent sterilization of the resin beds in the ion exchanger, together with the addition of 0.075 per cent formalin to the finished product, resulted in clearing up this trouble. Apparently, bacterial contamination from this source has become quite common as Elsman and his co-workers make the following statement: "A bacteriological study has been made of demineralizing units em- ploying synthetic cation and anion exchange resins for the production of water with low mineral content. It has been established that there exists a wide variation in bacterial content in deionized water which is conditioned by the manner in which these units are operated. An al- most sterile product may be produced provided the deionizing units are used daily and the resins regenerated every three or four days. If, on the other hand, the resins are regenerated at infrequent periods--that is, several weeks apart--the bacterial content of the eflquent, notwithstanding its chemical purity, may be excessive, being considerably greater than the numbers of organisms in the raw water entering the unit. The stor- age of such water gives rise to exceedingly large numbers of bacteria within twenty-four hours after collection." Also, Cruickshanks & Braithwaite make the following statement about the sterilization of cation exchange resins: "Beds of exchangers become contaminated because of the filtering action that occurs when operating as softening units. There has been no evidence that the bacteria normally encountered in water supplies are able to utilize the resinous cation exchange material itself as a nu- trient. Bacterial growth in the bed appears to be due entirely to sus- pended, organic material filtered from the water supply. Such organic material is capable of supplying the food requirements of a wide variety of micro•Srganisms. In a majority of the cases where bacterial contam- ination is encountered, the complaintwill be only periodic and may even be seasonal. A sterilization treatment that could be employed safely when required to maintain the bed in sanitary condition, therefore, would be completely satisfactory for most installations." These authors found the use of 0.25 per cent formalin to be the best mate- rial and concentration for the sterilization of these beds. CAS• No. 2 This is quite similar to the first in that the manufacturer was making a liquid. cream shampoo, noticed the finished product was becoming slimy and showed the presence of numerous gas bubbles. In this instance, the manufacturer did not have an ion exchanger. However, the water that was stored in a large tank on the roof entered the plant by gravity and was filtered by passing it through a cone filter, resembling in detail the cone-shaped coils of twine one used to see in the grocery stores years ago. These filter cones were larger in diameter and were comprised of rather

136 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS thick, soft-textured cord. The water entered the center of the cone--that is, the inner hollow part--and was filtered as it was forced through the many layers of cord. This type of filter is quite efficient but one must re- place the used cones quite often as they become filled with organic matter and dirt which is excellent media for the support of bacterial growth. The filter cone in operation at this plant had a green color due to algae, bacteria and "what-not," while the original filter cone was practically white in color. Bacteriological inspection showed the presence of our old friend •lerobacter aerogenes and Pseudomonas aeruginosa, formerly known as Bacilius pyocyaneus. The incorporation of 0.1 per cent formalin into the shampoo and changing the filter cone every forty-eight hours solved this bacterial contamination problem. I should add--whenever one resorts to the use of formalin for preserva- tion purposes--one should be certain that neither citral nor proteinagenous materials are present. Citral produces a pink coloration with formalin and, naturally, proteins are solidified or set by means of formalin. In connection with the use of formalin as a preservative in the presence of protein, I will tell you of the misfortune of a manufacturer who pre- pared a liquid cream shampoo, thickened it with 2.75 per cent gelatin and added 0.15 per cent formalin. Extensive shelf tests were performed at both 37øC., and room temperature. These tests proved that the product was most stable at these temperatures against both bacterial invasion and chemical reaction. The manufacture of the product progressed satisfactorily until cold weather arrived. The cartoned material, stored in a cool warehouse, gelled and was actually like a piece of liver. Removing the product back to room temperatare did not reliquefy the shampoo. An immediate re-examination of the former laboratory samples showed they were still in excellent condition but, subjecting them to cold tempera- tures, also produced this nonreversible gelling phenomenon. It ultimately became necessary lo subject the cartoned material to 70øC., for forty-eight hours to reliquefy the shampoo. To do so required the equipping of a separate room with adequate heat and its control. After this treatment, the shampoo remained liquid even when resubjected to cold weather. It is, therefore, strongly recommended that shelf tests be performed at not only elevated and room temperatures but, also, at 50øC. (refrigerator temperature) and -8øC. (deep freeze temperature). C^sE No. 3 This case deals with a nationally distributed facial lotion. It had •been on the market for several years and, one day, the president of the com- pany examined a bottle of it while in a drug store. The emulsion had