ABSTRACTS 43 the scales and to change the mechanical character of the cuticle from a hard elastic to a soft viscoelas- tic material. These and other important results on hair are discussed in detail. The guinea pig as a model for predicting photoallergic contact dermatitis William P. Jordan, Jr., M.D., Medical College of Virginia, MCV Station, Richmond, VA 23298. This report describes modifications in the tech- nique used for both the induction and elicitation of photoallergic contact dermatitis (PACD) in the guinea pig. These changes have improved the reliability of this animal as the model of choice for screening chemicals or products for their tendency to produce PACD. The induction period consists of 15 exposures of the test substance to shoulder skin that has been abraded with a nylon brush rotating at 13,000 rpm. One hour later, the test site is irradiated with broadband UVA from a source having some irradiance below 320 nm (UVA/b). The animals receive 450J/cm 2 of UVA during the three week induction period. The elicitation (chal- lenge) test is repeated for two consecutive days. Each day, the test material, if a liquid, is applied to two sites every 30 to 60 minutes for six hours then one of the sites receives 20 J/cm 2 of UVA. These photo-induction and photooelicitation procedures have demonstrated that low level concentrations (0.25% range) of 6-methyl coumarin or musk ambrette will both induce and elicit PACD in the guinea pig. This report adds more evidence that the induction of PACD in the guinea pig is dependent on broadband UVA. Studies of the epidermis using fluorescent dyes and cyanoacrylate stripping Peter T. Pugli•se, M.D., Xienta, Inc., 225 Long Ave., Hillside, NJ 07027. The purpose of this study was to develop a simple and inexpensive method of determining both the chemical and morphological characteristics of the epidermis. By adapting existing technology from several fields, a method was developed which employs specific fluorescent dyes which are capa- ble of staining certain selective epidermal proteins. The dyes are first applied to the skin in low concentrations and allowed to dry. A small drop of cyanoacrylate glue is placed on a microscope slide and gently pressed to the dyed surface. After sixty seconds the slide is removed with a peeling motion, carrying away several layers of stratum corneum. Visualization of the preparation with a microscope equipped for fluorescence allows three dimensional viewing of the topography of the skin. Hair follicles, sweat ducts, dermatoglyphs and other surface structures are easily seen. Both the inner and outer surface of the preparation may be viewed by turning the slide over and viewing through the glass to the under surface. Specific stains, such as acridine orange, berberine, and mercurochrome will allow study of the keratin of stratum corneum, nuclei, DNA and RNA, SH and S-S bonds and connective tissue. This technique may be used to demonstrate efficacy of products by taking samples before and after use. The method is applicable to establishing substantivity, cleansing, hydration, and defining certain chemical reactions. New test methodology for observing irritant and allergic reactions Robert L. Reitschel, M.D., Emory University School of Medicine, 215 Woodruff Memorial Bldg., Atlanta, GA. Methods which predict allergic contact dermatitis are many and their utility is proven. Among the more common types of testing procedures are the modified Draize test and maximization test. Irritant reactions are more varied in presentation and include stinging, urticaria, erythemas, and dermati- tis. Evaluation of irritant potential is presently studied by repeated insult patch testing and scarifi- cation. Newer technologies are being investigated in hopes of increasing the reproducibility of the predictive nature of irritancy testing. The swelling behavior of human hair and epidermal membrane Clarence R. Robbins, Ph.D. and K. M. Fernee, Colgate-Palmolive Co., 909 River Rd., Piscataway, NJ 08854. The swelling behavior of hfiman hair and of epider- mal membrane are compared. The results show that the microfibril-matrix models proposed to explain the swelling and extension behavior of wool fiber can also qualitatively account for the swelling behavior of hair and stratum corneum. The outer layers of human skin swell more in thickness than in area, and hair more in diameter than length. This behavior is consistent with the orientation of helical proteins in both substrates. Epidermal membrane is more sensitive than hair is to water, anionic surfactant, or formic acid, but less sensitive to thioglycolic acid. Anionic surfactants produce greater swelling than cationics, with highly specific surfactant-structure effects on the epidermal membrane. These results indicate that the location and immediate environment of bind-

44 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS ing sites in the membrane determine the ability of surfactants to disrupt and to swell the outer layers of skin. We suspect similar directional interactions between hair and different surfactants, but the swelling effects were too small to permit facile measurement with that substrate. PRESERVATIVES Evaluating preservative candidates for suita- bility Thomas E. Haag, Mallinckrodt, Inc., St. Louis, MO 63147. The search for new compounds effective as antimi- crobial agents is an expensive and time consuming process. The fine balance between human toxicity and antimicrobial activity is hard to achieve, thus new preservatives entering the marketplace are few and far between. The search continues, however, for the ideal preservative. Many of the factors to consider in evaluating a new compound are similar to those encountered by formulating chemists choosing a preservative system for new formula- tions. Topics to be discussed include determining antimicrobial activity, stability, partition coeffi- cients, compatibility with formulation compo- nents, toxicity, cost, and registration. Collaborative study of procedures for deter- mining the preservation efficacy of water- miscible mascaras Leo Judge, Ph.D., Saul Tenenbaum, Donald G. Ahern, Ph.D., Kerby Farrington, Ph.D., Joe Madden, Ph.D., John L. Smith, Ph.D. and John Yablonski, Revlon Inc., 945 Zerega Ave., Bronx, NY 1O473. Two different conceptual approaches are in use for the antimicrobial challenge testing of mascaras: in one, the preservation system is challenged by moni- toring the product for a spectrum of microorga- nisms and assaying periodically for microbial survival in the other, the double-membrane chal- lenge procedure, microbial inhibitors from the product diffuse through a micro-layer of water and cause rapid death of the challenge organisms deposited on the surface of a membrane. The present collaborative study was undertaken to compare standardized versions of both procedures. Mascaras prepared by industry to be either adequately, marginally or inadequately preserved were simultaneously challenged by the participat- ing laboratories. The results show the excellent reproducibility and statistical confidence between laboratories using each method and agreement between the two procedures. Microbiological aspects of raw material pres- ervation Peter A. Nielsen, Ph.D., Vick Divisions Research and Development, Mr. Vernon, NY 10553. Raw materials used in cosmetic and toiletry prod- ucts, whether of natural or synthetic origin, may contain micro-organisms or serve as substrates for their growth. The presence of large numbers of organisms is potentially hazardous. The micro- biologist should identify troublesome raw materi- als and recommend corrective measures. Some raw materials are inherently microbiocidal and are thus self-preserving. Others, because of their physical state, will not support growth but may nevertheless contain organisms. If such a microbial load is unacceptably high or includes undesirable micro- bial species, it may be necessary to treat these raw materials with a lethal agent to reduce or eliminate the microbial population. Still other raw materials, such as protein solutions, may not only contain microorganisms but may also serve as culture media for their proliferation. These supportive materials require an added antimicrobial substance to preclude microbial growth. The choice of preservative depends upon the physical properties and chemical nature of the material, and the types of organisms present. The preservative must be compatible with the formulation in which it will be used and active against the spectrum of organisms in the material. It must also be stable as well as nontoxic. An accelerated preservation test ElizabethJ. Scibienski, Ph.D.,JohnJ. O'Neill Ph.D. and Catherine A. Mead, Avon Products Inc., Suffern, NY 10901. An accelerated preservation test (APT) procedure that involves addition of nutrient/buffer salts and glucose to aqueous products has been developed. This test can identify within 7 days: inadequately preserved products marginally preserved products which fail late in a twelve-week double-challenge test with 106 bacteria per gram products that are poorly preserved against fungal spores and which would allow persistence of viable spores. Extensive testing with APT and twelve-week challenge-test procedures have revealed excellent correlation for a wide variety of products (e.g., shampoos, condi- tioners, creams, lotions and water-based make- ups).