Chemical, physical, and lubricant properties of magnesium stearate.

Three batches of commercial magnesium stearate were characterized in terms of their fatty acid composition, moisture content, and specific surface area. None of these variables appeared to have any effect on the lubricant activity of the samples. The lubricant properties of the compound were further examined using three hydrates of laboratory-prepared (pure) magnesium stearate. Based on the results obtained from the pure samples, it appears that differences in the lubricant properties of magnesium stearate are correlated with differences in moisture content and crystalline structure.

The influence of hard water (calcium) and surfactants on irritant contact dermatitis.

Although the induction of irritant contact dermatitis has been extensively studied for surfactants, the role of the environmental factor water hardness (i.e., calcium content) on the induction process has not received attention. Our objective was to investigate differences in surfactant-induced irritant skin reactions from cumulative exposure to 3 different personal cleansing agents and determine whether the irritation potential can be affected by the hardness of the water. 2 commonly used exaggerated washing procedures were variously employed to evaluate representative sodium soap, triethanolamine-soap, or synthetic detergent cleansers under conditions where the water hardness varied from 0-grain to 11-grain (gr). Subjects were clinically evaluated for skin dryness, skin redness, and instrumentally for hydration. Soap binding to skin was quantified using Fourier transform infrared reflectance spectroscopy. Using the more mild wash procedure, skin sites treated under conditions of hard, 11 gr water were significantly drier, had more erythema, and were less hydrated than corresponding sites treated with deionized 0 gr water. All 3 surfactant cleanser behaved similarly. We also found the hardness of the rinse water to be the more significant factor versus that of the wash water. Effect of water hardness on soap binding to skin revealed a similar outcome. Under a more exaggerated wash condition the relationship between water hardness and irritation broke down.

Safety assessment of enzyme-containing personal cleansing products: exposure characterization and development of IgE antibody to enzymes after a 6-month use test.

BACKGROUND: Enzyme-containing personal cleansing products were being considered for the consumer market. Although enzymes have been marketed safely for many years as ingredients in laundry products, their use in a personal cleansing application represented a new type of exposure for consumers that was not supported by the historical safety data. An exposure assessment and additional safety data would be needed before marketing to ensure consumer safety. OBJECTIVE: The work in this paper was designed to evaluate the potential for inhalation exposure to the enzyme during use of this new product while showering. Then a clinical trial was conducted to determine whether or not the level, duration, and routes of exposure encountered during use of this product would induce a Type I sensitization response to the enzyme. METHODS: Exposure was assessed during normal showering activities by collecting air samples with both high volume and personal samplers and quantitating enzyme levels with an ELISA. To assess the potential for sensitization, panelists were asked to use a prototype protease-containing bar product for all personal cleansing tasks and to keep a use diary reporting any associated symptoms. Physical and dermatologic examinations and skin prick tests with enzyme were conducted before the test commenced and at 2-month intervals. RESULTS: Exposure assessment results showed that airborne enzyme levels were primarily dependent on the concentration of the enzyme in the personal cleansing product. Mean values for total airborne enzyme protein ranged from 5.7 to 11.8 ng/m3 when enzyme concentration, time of use, and measurement technique remained constant. After 6 months of at-home product use, four of 61 test subjects using the enzyme-containing bar had positive skin prick test responses when tested with the enzyme. The skin prick test data were supplemented with serologic analyses, which detected IgE specific for the protease enzyme. None of these subjects showed any clinical symptoms indicative of allergic reaction. CONCLUSION: The ability of enzymes to induce development of allergic antibodies in this study led to the conclusion that this prototype enzyme-containing personal cleansing bar would represent an inappropriate use of enzymes in a consumer product application. The likelihood of both induction of an immunologic response and subsequent elicitation of allergy symptoms in a small but significant fraction of the user population was high. This finding resulted in the decision to halt further development of this prototype.

Leg wash protocol to assess the skin moisturization potential of personal cleansing products.

Many personal cleansers claim to provide a skin moisturization benefit, but there has been relatively little discussion in the scientific literature of the clinical methods that provide the basis for such claims. We have developed a leg wash method to assess the dry skin improvement potential of personal cleansing products. The protocol is performed on 'natural' dry leg skin to avoid potential confounds that may result from applying cleansers to soap-damaged skin. Washes are conducted over a period of days or weeks, with visual and instrumental assessments performed at various times throughout the period to characterize products' short-term and cumulative skin effects. Studies conducted with a variety of personal cleansing technologies demonstrate the method's ability to discriminate products on the basis of their dry skin improvement potential. Further, results from a series of eleven leg wash studies conducted with the same treatment pair under different test conditions (time of year, test facility, expert grader) demonstrate the protocol's robustness. The data generated under this protocol show that personal cleansing products differ widely in their ability to improve dry skin. Our results indicate that there is a wide range of efficacy among moisturizing personal cleansing products, with some products delivering a significant dry skin improvement benefit even for periods as long as 24 hours.