j. Cosmet. Sci., 49, 377-383 (November/December 1998) Non-comedogenic and hypoallergenic properties of jojoba oil and hydrogenated jojoba oil D. J. ARQUETTE, E. M. BAILYN, J. PALENSKE, D. DEVORN BERGMAN, and L. A. RHEINS, American Jojoba Oil Association, Gilbert, AZ (D.J.A.) and California Skin Research Institute, San Diego, CA (E.M.B., J.P., D.d.V.B., L.A.R.). Accepted for publication October 15, 1998. INTRODUCTION Jojoba oil and its derivatives have found broad and growing application in cosmetic and personal care products. The jojoba plant (Simmondsia chinensis) is native to the Sonoran Desert that straddles the border of Mexico and the United States. Commercial planta- tions have been established in various suitable growing regions including Mexico, the United States, Argentina, Peru, and Israel. The oil from the seed of the jojoba plant is unique in that it is a pure liquid wax ester, not a triaclyglyceride typical of most seed lipids. Its composition is close to that of sperm whale oil, which was used abundantly in cosmetic formulations before being banned by various treaties protecting the whales' existence in the early 1970s. Its chemical structure gives jojoba derivatives high stability and resistance to oxidation and degradation, enabling its storage for years in closed containers, in contrast to oils that become rancid and decompose with time. The liquid wax is composed of esters derived from C•s, C2o, C22, and C24 monounsaturated acids and alcohols, as demon- strated in Figure 1 (1). Hydrogenated jojoba oil retains the same structure, with the elimination of the double bonds (Figure 2). The fully hydrogenated wax esters form a hard white solid with a melting point of 69-70øC. The history and the botanical, agrotechnical, and economic aspects of the plant and the wax are presented elsewhere (2). Although widely accepted for their non-occlusive properties, little clinical data to substantiate the effect(s) of these products on the skin exist. In this paper, the safety of jojoba oil and hydrogenated jojoba oil was investigated. Draize and colleagues, in 1944, developed the Draize test for skin corrosivity and irritation using the rabbit skin and eye (3). Draize also developed early versions of an exaggerated patch test for irritation in humans. Later modifications by Maibach and Marzuli led over the years to the development of the so-called modified human Draize 377

378 JOURNAL OF COSMETIC SCIENCE ( Z,Z)-C H 3 (C H2)7C H =C H (C H2)rnC OO(C H2) n C H=C H (C H2)7 C H 3 m = 7, 9, 11, 13 n = 8, 10, 12, 14 m(%) - 11, 71, 14, 1 n(%) = 1, 45, 44, 9 Figure 1. Jojoba oil structure. patch test, or the human repeat insult patch test (HRIPT), to assess the contact sensi- tization potential of a material (4). The development of a human follicular biopsy comedogenicity study, as developed by Mills and Kligman in 1981, provided a physiologically relevant test to assess comedone formation (5). Because African-American men have a greater propensity for comedones/ acne, due to large pilosebacceous glands located in the upper back, they are often included in routine comedogenicity studies to exaggerate the potential for comedone formation of raw and/or finished product materials. Negative results in this particular population, when compared to the appropriate controls, provide a convincing set of data for non-comedogenicity claims. To determine the safety of potential new products containing jojoba oil (both refined and pure), as well as hydrogenated jojoba oil, three preliminary studies were undertaken to evaluate their comedogenicity, and their phototoxic and allergenic potential(s). MATERIALS AND METHODS Two grades of jojoba oil, refined and pure, are available commercially. Both are expeller- pressed (mechanically extracted). The refined jojoba oil is filtered and refined with a dilute caustic to remove free fatty acids and hydratable phospholipids. The oil is bleached to remove all the color using a montmorilonite clay. Vacuum deodorization removes any remaining odors. Pasteurization is accomplished during the deodorization process. The pure jojoba oil receives only filtration and pasteurization, retaining the typical golden color and nutty aroma. Hydrogenated jojoba oil is produced by the nickel catalyzed hydrogenation of refined jojoba oil. The hydrogenated oil is bleached and deodorized. The physical properties of the materials are listed in Table I. Initially, these three substances were tested for cutaneous allergenic potential using the HRIPT, an adaptation of the Draize patch test (3,4). HUMAN REPEAT INSULT PATCH TEST (HRIPT) The purpose of the HRIPT was to evaluate the potential of one or more of jojoba test articles to induce allergic contact sensitization. Briefly, test articles were applied to the skin of the back utilizing a patch system under occlusive conditions in order to exag- gerate exposure conditions. Each patch remained in place for approximately 48 hours