ABSTRACTS 379 introduced into the marketplace for the control of dental plaque. Sanguinaria is a bontanical extract obtained from the plant Sanguinaria canadensis. San- guinaria is composed of benzophenanthridine alka- loids and sanguinarine is the prominent alkaloid. Sanguinarine has a unique iminim ion chemistry that is responsible for its effectiveness against dental plaque formation. This presentation will include a review of clinical safety and efficacy studies. Both toothpaste and oral rinse clinical studies will be reviewed. Studies on the retention of sanguinarine in the oral cavity and its antimicrobial action against plaque-forming micro-organisms will be presented as a rational mechanism of action. Certain qualitative changes in plaque as a means of reducing gingivitis will also be considered. Sanguinarine rep- resents an innovative new ingredient for use in the oral cavity with potential against plaque, gingivitis, and periodontal diseases. SESSION III IN VITRO SAFETY In vitro approaches to toxicity testing: A status report Roland M. Nardone, Ph.D., Department of Bi- ology and the Center for Advanced Training in Cell and Molecular Biology, Catholic University of America, Washington, D.C. 20064 Prompted by the partial successes of short-term cell culture tests for the evaluation of the potential mu- tagenicity and carcinogenicity of chemicals and the growing concern for the use of animals for toxicity testing, programs for the evaluation of target-spe- cific chemicals are being developed. The strategies which may be employed to develop such tests and the difficulties and opportunities which they present will be described and analyzed. Ocular and neuronal in vitro test development will be emphasized. Hydrophobicity of n-lauroyl amino acid as a pa- rameter to determine primary skin and eye ir- ritation Kazutami Sakamoto, Ph.D., Ajinomoto USA, Inc., 9 West 57th Street, Suite 4625, New York, NY 1OO19 Hydrophobicity of N-lauroyl (C•2 fatty acid acyl) amino acids (LAA) were measured by reversed phase HPLC and TLC. The order of hydrophobiciry of LAA, which corresponds to the character of side- chain residue of each amino acid, is found as fol- lows: the Phe Ile Leu Val Trp Pro Ala Gyl Set Glu. The primary skin and eye irritation for rabbits is tested by the Draize method and compared to the hydrophobicity. A good relationship is found be- tween hydrophobicity and primary eye irritation, which is that lower hydrophobicity corresponds to lower irritation. A similar relationship is found for LAA between hydrophobicity and hemolysis for human red cells. In contrast, the primary skin ir- ritation is inversely proportioned to the hydropho- bicity, except for glutamic acid. As a result, it is assumed that hydrophobicity is a useful parameter to evaluate skin and eye irritation. Of the LAA's which have already been tested, N-lauroyl glutamic acid seems to be the mildest material. Determination of surfactant irritancy from the swelling behavior of a collagen membrane J. Blake-Haskins, D. Scala, L. Rhein, and C. R. Robbins, Colgate-Palmolive Co., 909 River Road, Piscataway, NJ 08854 Swelling of a collagen membrane by surfactants has been established as an in vitro method to evaluate anionic surfactant potential. The method was used to study the relationship of surfactant structure to swelling activity for alkyl sulfates and ethoxylated alcohol sulfates, in which the carbon chain number and ethylene oxide number were varied systemati- cally. Results show that the C12 homologue in- duced the most swelling and that membrane swelling is inversely proportional to ethylene oxide content. Swelling response is dose-dependent. The assay was used to investigate surfactant interactions additions of amphoteric surfactants to an anionic surfactant reduce the amount of swelling caused by the anionic alone. Results of this in vitro test cor- relate with findings from established in vitro and in vivo laboratory and clinical irritation assessments. These findings suggest a mechanism of skin irrita- tion in which collagen is disrupted, leading to swelling of the skin. SESSION IV GENERAL PAPERS Surfactant structure effects on stratum cor- neum swelling Linda D. Rhein, Ph.D., C. R. Robbins and K. Fernee, Colgate Palmolive Co., 909 River Road, Piscataway, NJ 08854 Surfactants in solution induce swelling of isolated stratum corneum (Robbins and Fernee Putterman, et al.). The highest levels of swelling observed were for anionic surfactants, and very little swelling oc- curred with cationics and nonionics. For a homol- ogous series of alkyl sulfates, swelling was maximal for the C12 homologue. We have now extended these studies to examine effects of structural variants of surfactants on swelling of stratum corneum. Swelling caused by surfactants increased with time, was dose dependent, and was saturable with in- creasing concentration. The extent of swelling was reduced with increased ethoxylation of dodecyl sul- fate and depended upon the counterion. For ho- mologous series of various anionic surfactants, max-

380 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS imal swelling occured between C 12 and C 14 carbon atoms. Surfactant interactions to reduce swelling were found e.g., addition of ethoxylated alcohol sulfates and amphoterics to anionics produced less swelling than the anionics alone. The results sug- gest mechanisms of action of surfactants and a basis for in vivo irritation. The use of magnitude estimation with para- metric statistical methods in the subjective measurement of axillary odor Mark J. Levine and Penelope Giles, American Cy- anamid Company, Consumer Products Research Di- vision, 697 Route 46, Clifton, NJ 07015 A conventional axillary deodorant clinical study in- volves 3-6 trained odor judges providing numerical ratings of human axillary malodor intensities. A 0- 5 or 0-10 rating scale is typically used. This paper discusses the use of the magnitude estimation rating scale method in these studies. In addition, clinical evaluation studies are presented. Advantages of the magnitude estimation method include scientific va- lidity grounded in psychological literature, ratio scale properties supporting deodorant efficacy mea- surement in terms of "percent odor reduction," and statistical validity, flexibility, power, and conve- nience. A data analysis involving a total of 562 subject evaluations provides empirical justification for applying parametric statistical methods (t-tests, analysis of variance, regression, etc.) to the loga- rithm of the judge ratings. A simple method for analyzing data containing some zero ratings (whose logarithm is undefined) is presented. Subjects with higher initial odor levels are shown to yield greater percent odor reductions than those with lower ini- tial odor levels. Study designs which control for this factor are recommended. The power to detect small product efficacy differences is shown to be dimin- ished in studies which include other deodorants with large efficacy differences. Some considerations in the selection and training of judges are presented. Stabilization of oil-in-water emulsions by gums Joel L. Zatz, Ph.D., and Bernard Ip, Rutgers Uni- versity College of Pharmacy, P.O. Box 789, Pis- cataway, NJ 08854 Model emulsions containing 10% mineral oil, oleth 3, oleth 10, methylparaben, propylparaben, water, and several concentrations of selected gums were prepared. A two-step procedure, designed to pre- vent variations in initial particle size in emulsions containing the same emulsifier concentration, was employed. Median particle size, measured by an electronic sizing technique, was inversely related to emulsifier concentration. There was no change in particle size distribution of the emulsions after storage for 7 months. Viscosity values for emulsions containing xanthan gum did not change signifi- cantly during the storage period. In emulsions con- taining 0.25 to 1.0% emulsifier, addition of xan- than gum decreased the creaming rate to about the same extent. The logarithm of creaming rate was a linear function of gum concentration, making it possible to compare different gums quantitatively. The order of effectiveness in retarding creaming was xanthan gum carbosymethylcellulose, high viscosity methylcellulose, 4000 cp. Thiol reduction of hair fibers in the presence of exogenous disulfides J. Cincotta, E.J. Klemm, L. Salce, S. Barrow., Zotos International, Inc., 100 Tokeneke Road, Darien, CT 06820 Reduction of keratin hair fibers with excess thiol proceeds in a two-step equilibrium reaction. Factors affecting this equilibrium were examined using amino acid analyses and fiber bundle tensile tech- niques. When hair fibers were treated with either ammonium thioglycolate or glycerly monothiogly- colate, at a fixed pH and concentration, the rate and extent of reduction of these fibers were curtailed when exogenous disulfides were added to the re- acting medium. Observations were made under var- ious experimental conditions. Attempts were made to correlate loss of tensile properties of hair fiber bundles with percent keratin reduction in the pres- ence of thioIs containing exogenous disulfides. Loss of fiber bundle tensile properties were found to be related to the concentration of disulfide added to the thiol solution. Results of the experimental data obtained in these studies will be discussed. Applications of matrix engineering in skin care E. A. Balazs, M.D., P. A. Band, Ph.D., A. K. Leshchiner, Ph.D., and E. A. Leschiner, Ph.D., Biomatrix, Inc., P.O. Box 536, Ridgefield, NJ 07657 Matrix engineering is a technology based on the naturally occurring polymers found in the inter- cellur matrix of all animal tissues. Based on the in vivo functions of connective tissue biopolymers, spe- cialized properties of human tissues can be mim- icked or enhanced. Derivatives and modifications of hyaluronic acid (HA) molecular networks have skin care applications arising from both their intrinsic properties and their ability to act as a cosmetic de- livery system. Using such HA-based materials, ef- ficacious cosmetic ingredients such as petrolatum can be delivered in formulations which mask their undesirable properties. Matrix engineering-based methods which bridge the gap between aesthetics and efficacy will be presented, and their impact on the classical differentiation of formulations into oils, lotions, and creams will be discussed.