2007 ANNUAL SCIENTIFIC SEMINAR 575 To use water activity, you need to remember it only prevents growth, it is not cidal. It is mandatory for you to have good cGMP's in place and employ HACCP. Ingredients that lower water activity include salt and very water-binding molecules like glycols. Now What After you have followed these first steps you should confirm what will grow by seeing what grows in your product. Inoculate like you would do a Preservative Efficacy Tests (PET) and see if your formulation is inherently hostile to anything. Enrichment techniques are recommended. Now you need to see what kind of packaging sales plans to use. Is the packaging such that the consumer cannot contaminate it? Or is the type that is frequently contaminated? Compare a wide mouth jar to a tube with a narrow opening. This is vital in developing what would be an appropriate challenge test for the product and what would be your pass/fail criteria. In deciding what test to use, remember a typical cosmetic is easier to test than atypical products. The CTFA has recently developed methods for atypical cosmetics. Adding Preservatives How you add the preservative(s) is part of the development process. Almost all preservatives degrade under high heat, extreme pH and these conditions are a factor of time that the chemical is exposed to these conditions. Frequently the best procedure for typical cosmetics is to add the preservatives pre-dissolved in a water soluble solvent, below 40 °C. In deciding what preservative(s) to try, you should first see where marketing plans to sell the product. The US is the easiest country with almost no rules concerning preservatives. The EU has a permitted list and Japan has the most restricted. If marketing wants a "global" formulation, than you are limited by the most restricted market. Marketing may also restrict permitted preservatives by saying no parabens, no chlorine, no iodine, no formaldehyde containing chemicals, no ethylene oxide or even no glycols. Finally Run your product stability test and see if your preservative system still works after accelerated aging. If your system passes all of your safety, stability and PET tests, you may want to try these again using lower levels of preservatives. Most time, we over preserve because we lack the time and money to check a second or third time! Conclusion Remember that although it is not the primary purpose of preservatives to destroy contamination during manufacturing, we do need this. The "weaker" the preservative system, the better your cGMP"s!

576 JOURNAL OF COSMETIC SCIENCE SOLVING MANUFACTURING PROBLEMS IN EMULSION PRODUCTS T. Joseph Lin, Ph.D. 628 Enchanted Way, Pacific Palisades, CA 90272 Introduction Cosmetic manufacturers today are faced with increasing global competition and the ability to produce a wide range of products at a consistently high level of quality is extremely important. To reduce costs, manufactmers have increased batch sizes, and manufacturing failures are more expensive than ever in terms of lost materials and failure to meet scheduled delivery dates. Toe pressures and time demands on cosmetic chemists have never been greater. Moreover, to cope with fast-changing market demands, cosmetic chemists are often required to remove or add certain ingredients into the existing formulations to improve product performance or enhance perceived consumer value. One danger is increased ingredients complexity and the possibility of unexpected chemical reactions or physical interactions which may affect product performance and shelf life. Too often, because of the intense pressures of competition, insufficient time is allotted for stability testing of the reformulated products, resulting in stability failure and expensive product recalls. Among the various types of cosmetic formulations, emulsion-based products continue to enjoy popularity because they look elegant, provide nice skin feel, and are very versatile in applications. Allowing easy incorporation of many water and oil-soluble ingredients, they can be adopted to formulate a wide range of O/W or W/O type skin-care, sun-care and hair-care products. In the past, cosmetic formulators have generally tended to stick to their favorite "tried-and-true" emulsification systems, using mostly well-known and familiar ingredients to formulate new products. However, intense market competition has change the rules and formulation chemists are often forced to use new ingredients without a well-established performance record or accurate information about their physical/chemical properties. Natural, Organic and "Chemical-Free" Emulsions For example, the popularity of "natural/organic" foods has stimulated the market for "organic" or "natural" cosmetics. Formulation chemists at cosmetic manufacturers are pressured to come up with all-natural or "chemical-free" cosmetics. Chemists working for raw material suppliers are also pressed to come up with effective "natural" or "chemical-free" surfactants, preservatives and other functional materials. Since there are no universally agreed upon definitions for words like "chemical," "natural," or "organic," depending of how the terms are defined, such products can be difficult or nearly impossible to create. Unlike well-defined pure chemicals such as methylparaben or imidazolidinyl urea, a substance advertised as a "natural" preservative may be a complex mixture of many naturally-derived and synthetic materials of unknown chemical composition. This means there is surely a greater chance of unexpected interactions with other ingredients in the formulation which may cause product degradation and instability. Emulsion Stability and the Second Law of Thermodynamics By their nature, emulsified products consist of two incompatible liquids, usually a water-soluble phase and an oil-soluble phase. They are thermodynamically unstable, meaning that they all have a limited shelf life, and phase separation will take place some time after manufacturing. A minimum of two-year stability is required for most commercial cosmetic emulsions. This requirement would not be difficult to meet if we had a quick and reliable method or instrument to predict the shelf life of a particular emulsion.