THE VARIABILITY OF THE SKIN 375 Moreover "natural skin cream" may crystallize when exposed to low temperatures. Corresponding to this is an inactivity of the cellular com- ponents of the epidermis, which in my opinion makes it probable that, on the one hand, this skin is not readily capable of spontaneous recovery, and will react in an unexpected way to the local application of ointments, but, on the other hand, does not easily react with exanthema on internal noxa. CONCLUSION It is hoped that the foregoing has presented a general idea of the great variability of the skin. As the anatomical and physiological investigation of the skin is directed more and more to quantitative aspects it will become possible to analyze more accurately than now, the effects of cosmetics under various circumstances, in various individuals, on different paris of the human skin. (Received: 7th February 196•t.) REFERENCES (1) A. G. Matoltsy, Z. Schragger and M. N. Matoltsy, J. invest. Dermatol. 38 251 (1962). (2) H. Pfleiderer Z. exptl. g/led. 90 24S (1933). (3) J. W. H. Malt Dermatologica 104 19 (19S2). (4) R. K. Winkelman, S. R. Scheen, R. A. Pyka and M. B. Coventry in W. Montagna and R. A. Ellis Advances in biology of skin Vol. II--Bloodvessels and circulation 1 (1961) (Pergamon Press Ltd., Oxford). {5) R. H. Fox and O. G. Edholm ,Brit. Med. ,Bull. 19 110 (1962). (6) T. Bedford J. Hyg. 35 307 (1935). (7) A. C. Burton and G. Froese J. Appl. l•hysiol. 10 235 (1957). (8) J. R. DePalma, S. R. M. Reynolds and F. I. Foster Am. Heart J. 23 377 (1942). (9) H. Pinkus Dermatologica 117 369 (1958). (10) J. W. H. Malt Ned. Tijdschr. Geneesk. 107 2017 (1963). (11) P. V. Marcussen J. Invest. Dermatol. ,10 263 (1963). {12) J. S. Strauss, A.M. Kligman and P. E. Pochi J. Invest. Dermatol. 39 139 (1962). .(13) N. N. Epstein in R. B. Rees Dermatoses due to environmental and physical factors 37 (1962) (Ch. C. Thomas, Springfield). (14) D. TXV. Smithers Lancet i 493 (1962). (15) G. Swanbeck Acta Dermato-Venerol. 39 Suppl. 43 1 (1959).

J. so½. Cosmetic Chemists 15 377-384 (1964) THE NEED FOR RABBIT SKIN STUDIES IN EVALUATING COSMETIC SAFETY I. LEVENSTEIN, Ph.D.* l•resented at the Symposium on "Toxicology of Cosmetic Materials", at Leamington, Warwicks., on 20th November 1963. The usefulness o• animal data in evaluating the safety o• cosmetic preparations is described. In •our examples cited the primary irritation in each o• three rabbits was confirmed by patch tests on twenty-five humans. The Food, Drug and Cosmetic Act under the jurisdiction of the U.S.A. Department of Health, Education and Welfare defines the term "Cosmetic" as (a) "Any article or articles intended to be rubbed, poured, sprinkled, or sprayed on, introduced into, or otherwise applied to the human body or any part thereof for the cleansing, beautifying, promoting attractive- ness, or altering the appearance", and (b) "any articles intended for use as a component of the aforementioned articles, except soap." Many new pro- ducts are compounded every year which fit this definition. Some contain old formulations and mixtures in new containers, but many incorporate new complex chemical materials which by virtue of some physiological activity, impart a beneficial change to the skin. These new materials may possess the ability to cause primary irritation, sensitization, systemic toxicity or blindness to the user. It is therefore necessary to evaluate the safety of each new preparation so that any toxic reactions may be discovered before the product is placed upon the market. The most reliable informa- tion, which would indicate the extent of toxicity of a product, can only be obtained from actual use in the human. Since, however, this type of experimentation may lead to dangerous consequences, a laboratory method must be developed which will give a measure of the risk associated with the use of a new preparation. It must be a reproducible procedure which can be relied upon to warn the cosmetic manufacturer of those materials which may be potentially dangerous if applied to the human. In investigating a new cosmetic for its safety, the oral toxicity, eye responses and skin reactions must be studied and evaluated. This paper is limited to those procedures which, we believe, are effective in determining the *Leberco Laboratories, Roselle Park, N.J., U.S.A. 6 377