32 JOURNAL OF COSMETIC SCIENCE formula behaved differently in terms of vitamin A palmitate penetration when the vitamin was combined with glycolic acid, whereas the behavior of the cream and gel cream formulas were not affected, also showing the well known fact that vehicle inter- feres with the skin penetration of active principles. ACKNOWLEDGMENT The research in this article was supported by FAPESP. REFERENCES (1) R. Hermitte, Aged skin, retinoids and alpha hydroxy acids, Cosmet. Toiletr., 107, 63-67 (1992). (2) B. Idson, Vitamins and the skin, Cosmt. Toiletr., 108, 79-94 (1993). (3) P.M. B. G. Maia Campos, Estudos da Estabilidade Quoemica e da Absoffcio "In Vivo" da Vitamina A em Prepara•-•es Cosmgticas Para a Pele, Ribeirgo Preto, 1994, 120pp. Tese (Doutorado) Faculdade de Ci&ncias FarmacSuticas de Ribeirgo Preto, Universidade de Sgo Paulo. (4) P.M. B. G. Maia Campos, S. A. Benetton, and G. M. Eccleston, The influence of the vehicle in the penetration of vitamin A into the skin, Cosmet. Toiletr. (in press). (5) A. Nilson, "Efectos Cosmeto16gicos de las Vitaminas," in: Congresso Latino Americano e Ibmrico de Qu micos Cosm6ticos, 10, Caracas, 1991. Anais, Caracas, Sociedade Venezolana de CiSncias Cosm&i- cas, 1991, pp. 2-16. (6) M. I. R. Santoro, P.M. B. G. Maia Campos, and E. R. M. Hackman, Determining vitamins A, D3 and E in creams: High performance liquid chromatography, Cosmet. Toiletr., 108, 71-74 (1993). (7) W. P. Smith, Hydroxy acids and skin aging, Cosmet. Toiletr., 109, 41-48 (1994). (8) J. Van Scott and R.J. Yu, Alpha hydroxy acids: Procedures for use in clinical practice, Cutis., 93, 222-228 (1989). (9) D. F. Counts, F. F. Skreko, J. Mcbee, and G. Wich, The effect ofretinyl palmirate on skin composition and morphometry, J. Soc. Cosmet. Chem., 39, 235-240 (1988). (10) B. Idson, Vitamins and the skin, Cosmet. Toiletr., 108, 79-94 (1993). (11) P.M. B. G. Maia Campos, Vitaminas lipossolfiveis em cosm&icos, Cosmet. Toiletr., 4, 30-33 (1992). (12) H. Shaefer and A. Zesch, Penetration of vitamin A acid into human skin, Acta Dermatol. Venerol., 55, 50-55 (1975). (13) M.J. Stiller et al., Topical 8% glycolic acid and 8% L-lactic acid creams for the treatment of photodamaged skin, Arch. Dermatol., 132, 631-636 (1996). (14) E.J. Van Scott and R.J. Yu, Alpha hydroxy acids: Therapeutic potentials, Can. J. Dermatol., 1, 108-112 (1989). (15) D. D. Munro, The relationship between percutaneous absorption and stratum corneum retention, Br. J. Dermatol., 81, 92-97 (Suppl. 4). (16) P.M. B. G. Maia Campos, G. Ricci, et al., "Avaliaggo da Estabilidade e Estudo, s Histopatol6gicos e Estereo16gicos de Formulag6es Dermocosm&icas Contendo Vitamina A e/ou Acido Glic61ico," in: Congresso Latino Americano e Ibmrico de Qu•micos Cosm&icos, 12, Sgo Paulo, 1995. Anais, Sgo Paulo, Associaggo Brasileira de Cosmetologia, pp. 46-70 (1995). (17) G. Maia Campos, G. M. C. Software Verscio 6.1, Ribeirgo Preto, Departamento de Estomatologia, Faculdade de Odontologia de Ribeirgo Preto, Universidade de Sgo Paulo. (18) J. Boehnlein, A. Sakr, J. L. Lichtin, and R. L. Bronaugh. Characterization of esterase and alcohol dehydrogenase activity in skin: Metabolism of retinyl palmirate to retinol (vitamin A) during percu- taneous absorption, Pharm. Res., 11, 1155-1159 (1994).

j. Cosmet. Sci., 49, 33-38 (January/February 1998) Pyranine, a fluorescent dye, detects subclinical injury to sodium lauryl sulfate A. PAGNONI, A.M. KLIGMAN, and T. STOUDEMAYER, S.K.I.N. Inc., 151 E. loth Avenue, Conshohocken, PA 19428 (A.P., A.M.K., T.S.), and Department of Dermatology, University of Pennsylvania, 415 Curie Blvd., Philadelphia PA 19104 (A.M.K. ). Accepted for publication February 16, 1998. Presented at the 58th SID Meeting, April 1997. Synopsis Anionic surfactants may damage the horny layer barrier in the absence of clinical signs of irritation. Increased permeability increases susceptibility to exogenous chemical insults. We describe herein a rapid method for detecting invisible disruption of the barrier by sodium lauryl sulfate (SLS). Low concentrations of SLS, insufficient to induce visible changes, were applied occlusively in Hill Top chambers to the volar forearms of normal women for 24 hours. One hour after removal of the chambers, pyranine, a water-soluble fluorescent dye, was applied with a cotton-tip applicator and allowed to dry. The dye was gently washed off 30 minutes later. The intensity of the fluorescence was visualized under Wood's light immediately and 24 hours later. Ultraviolet photos were obtained for photographic documentation. Measurements of transepidermal water loss were made at the same time. Concentrations of 0.025% and 0.1% SLS caused, in most of the subjects, no visible reactions. However, in comparison to a control water patch, both sites fiuoresced strongly under Wood's light, more so with 0.1% SLS. Transepidermal water loss also increased, proportionally to concentration, validating barrier disruption. 0.005% SLS was below the threshold of injury by this methodology. Pyranine fluorescence appears to be a useful technique for evaluating subclinical barrier damage from detergents. INTRODUCTION Irritant reactions are common and important in clinical and occupational dermatology. There has recently been a great interest in the mildness of skin care products, especially surfactants and soaps. In a competitive market place, manufacturers vie with each other to prove claims of superior mildness. Clinical methods for grading visible signs of irritation are giving way to bioengineering techniques, which provide more accurate, more discriminating, and more objective data in comparative studies. A noteworthy advantage is the ability to measure subclinical, nonvisible changes. Many sophisticated instruments are available for measuring various features of the irritation reaction, including transepidermal water loss (TEWL), scanning 33