PETROLATUM AND COMEDOGENICITY 47 Professional adult women seem especially vulnerable to episodic "breakouts," often lasting for decades into menopause. By contrast, ache is uncommon in post-adolescent males. I have ventured the speculation that post-adolescent female acne is due to release of androgenic corticosteroids, induced by work-associated stress, superimposed on household duties and marital commitments. The work of Lucky et al. has made it clear that the onset of acne in prepubertal girls is closely correlated with the serum level of adrenal androgens, notably dehydroepiandrosterone (20). Stress is a well known stim- ulus for the synthesis of adrenal androgens. It must also be said that genuine ache cosmetica has not altogether disappeared. There are literally hundreds of producers of cosmetic products throughout the world, and many do not adequately test their wares. I have randomly collected from the pocketbooks of my patients a surprising number of exotic skin care products by unregistered foreign manufacturers. Some of these were comedogenic in the rabbit assay. Petroleum jelly is an exceedingly complex mixture of hundreds of saturated hydrocar- bons. It is produced by the fractional distillation of petroleum. During the process, petrolatum remains in the bottom portion as a semisolid, bluish-colored material. It is then refined exhaustively to remove color, aromatic hydrocarbons, odoriferous materials, and other "impurities." Petrolatum is known generically as soft white paraffin. Speci- fications for acceptability are given in the U.S. Pharmacopea. Vaseline © is the trade- name of petrolatum made by Chesebrough-Ponds. Piewig et al. in their report on pomade ache in Afro-American males, specifically incriminated Vaseline © among other greasy grooming products (9). Herein lies an interesting story that is worth recounting. It turns out that Vaseline has become a generic term for almost any hydrophobic grease. Recently, we bought "Vas- eline" at six local pharmacies whose customers are mainly Afro-Americans. In only three stores was the product bona fide Vaseline © . The other three were Vaseline-like greases of unknown composition made by unfamiliar manufacturers. We found these three to be comedogenic in the revised rabbit model. Accordingly, in reports that incriminate Vaseline as comedogenic, one must check the source. This study is not intended as a recommendation of petrolatum for the treatment of inflammatory acne vulgaris. However, it does show the benefits of moisturization for inflammatory ache. Dermatologists routinely inveigh against oily cosmetics for ache sufferers. Patients are urged to seek oil-free cosmetics. This advice has not been supported by scientific studies. Comedogenicity has nothing whatever to do with oiliness the latter is a physical attribute and not a chemical entity. Some of the most potent comedogenic substances, dioxin for example, are non-oily. On the other hand, many classical oils, notably vegetable oils, are usually non-comedogenic. Chemical structure determines comedogenicity. As yet, acnegenicity cannot be pre- dicted by structure. The mechanism underlying comedogenicity is unknown. Why corneocytes stick to each other to form horny impactions is still a mystery. REFERENCES (1) A.M. Kligman and O. H. Mills, Ache cosmetica, Arch. Dermatol., 106, 843 (1972). (2) A. Zatulone and N. A. Konnerth, Comedogenicity testing of cosmetics, Cutis, 39, 591 (1987).

48 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS (3) S. B. Frank, Is the rabbit ear model prophetic ofacnegenicity,J. Am. Acad. Dermatol., 6, 373 (1982). (4) J. A. Fulton, Comedogenicity and irritancy of commonly used ingredients in skin care products, J. Soc. Cosmet. Chem., 40, 321 (1989). (5) F. P. Nelson and J. R. Rumsfield, Cosmetics, contents and function, Int. J. Dermatol., 27, 665 (1988). (6) Z. D. Draelos, Assessing the complexity of cosmetic ingredients, Cosmet. Der•tol., 7, 17 (1994). (7) A.M. Kligman, Improved procedure for assessing acnegenicity (comedogenicity) in the rabbit ear model, J. Toxico/. C•tan. Oc•/. Toxicol., 4, 395 (1990). (8) G. Plewig and A.M. Kligman, Ache and Rosacea, 2nd ed. (Springer-Verlag, New York, 1993). (9) G. Plewig, J. E. Fulton, and A.M. Kligman, Pomade ache, Arch. Dermatol., tot, 580 (1970). (t0) XV. E. Morris and S.C. Kwan, Use of the rabbit ear model in evaluating the comedogenic potential of cosmetic ingredients, J. Soc. Cosmet. Chem., 34, 215 (1983). (11) O. H. Mills and A.M. Kligman, The follicular biopsy, Der•tologia, 167, 57 (1983). (12) A. Pagnoni, A.M. Kligman, and S. el Gammal, Determination of density of follicles on various regions of the face by cyanoacrylate biopsy, Br. J. Der•tol., 131, 862 (1994). (13) J. A. Mezick, G. Thorne, M. C. Bhatia, L. M. Shea, and R. J. Capetola, "The Rabbit Ear Micro- comedo Prevention Assay," in klodds in Derr•tology, Vol. 3, H. I. Maibach and N.J. Lowe, Eds. (S. Karger, Basel, 1987), p. 68. (14) O. H. Mills and A.M. Kligman, Drugs that are ineffective in the treatment of ache vulgaris, Br. J. Der•to/., 128, 371 (1983). (15) R. Ghadially, L. Halkier-Sorensen, and P.M. Elias, Effects of petrolaturn on stratum corneum structure and function, J. Am. Acad. Der•tol., 26, 387-396 (1992). (16) B. A. Newman and F. F. Feldman, Adult premenstrual ache, Arch. Der•tol. Syph., 69, 350 (1954). (17) E. Epstein, Incidence of facial ache in adults, Dermato/. Digest, 7, 49 (1968). (18) A.M. Kligman, Post-adolescent ache in women, C•th, 48, 75 (1991). (19) A.M. Kligman, A critical look at ache cosmetica. J. C•tan. Aging Cosmet. Dermatol., 2, 109 (1989). (20) A. XV. Lucky, F. M. Biro, G. A. Huster, A.D. Leach, J. A. Morrison, and J. Ratterman, Ache vulgaris in premenarchy girls, Arch. Der•tol., 130, 308 (1994).