REACTIONS TO EYE COSMETICS 251 Contact dermatitis resulting from eye area products is rarely severe and is manifested by periorbital erythema of varying degrees, some edema, scaling, itching, and burning. Irritant contact dermatitis is encountered more often than the allergic form. Although the cutaneous manifestations of both forms are virtually indistinguishable, the pathogenesis differs. 2. PATHOGENESIS Allergic contact dermatitis involves cell-mediated immunity and occurs only in individuals who are prone after adequate exposure to a sensitizing substance (16). Proneness may be a genetically determined trait influenced by environmental and local factors such as damaged skin and occlusion. The initial step in sensitization is the combination of the contacting hapten (chemical) with an epidermal protein to produce a hapten-carrier conjugate that is immunogenic. Re-exposure after a given period to the same or an immunologically related chemical is followed by an allergic reaction referred to as a delayed eczematous response, i.e., allergic contact dermatitis. The interval between the initial contact and the development of the allergic response, i.e., the sensitization (incubation) period varies considerably, rarely shorter than seven to ten days or it may- be a matter of months to years depending on the opportunity for exposure and the sensitizing potential of the chemical. Once established this form and allergy often persists for life. While sensitization to eye area cosmetics may develop de novo in the course of applying and reapplying a product, most reactions seem to occur in previously sensitized individuals who were exposed some time in the past to the same or related allergen in topical medicaments or their environment (11). The pathogenesis of irritant contact dermatitis is not entirely clear. Two types are recognized--the acute type elicited by a single application of a strong irritant such as caustic materials and the chronic form in response to mild (cumulative) irritants requiring multiple exposures Before a reaction ensues (17). Irritants in eye area cosmetics and in cosmetics in general belong to the latter category. Though most if not all individuals react to the first exposure to a strong irritant, the capacity to react to mild irritants varies considerably (18). Atopics (individuals who have or have had asthma, hay fever and/or atopic dermatitis) and fair skinned individuals who tan poorly appear to be more vulnerable. Factors such as over-exposure, aggressive cleansing, and adverse environmental conditions are also thought to play a role (17, 18). In the author's view an additional factor may be the additive effect of more than one potential mild irritant in a given formulation. 3. ALLERGENS IN EYE AREA COSMETICS Preservatives, antioxidants, and resins are the principal allergens. Preservatives: Parabens, with few exceptions (vide infra) are common to all eye area products. These esters of parahydroxybenzoic acid are combined not infrequently, with at least one other antimicrobial such as phenyl mercuric acetate, imidazolidinyl urea (Germall 115 ©) or quaternium 15 (Dowicil 200 ©) to insure adequate protection against yeasts, molds, and pseudomonads which are widely distributed in nature.

252 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Quaternium-15, imidazolidinyl urea, and DMDM hydantoin are formaldehyde donors. The latter is used less frequently than the other two compounds. Quaternium-15 has been shown to be a more active formaldehyde releaser than imidazolidinyl urea (19). Allergic reactions may be elicited by the compound per se or by the released formaldehyde (21, 22). Fisher (23) maintains imidazolidinyl urea is a much safer preservative than quaternium-15 for formaldehyde-sensitive individuals. Potassium sorbate is also used as a preservative in eye area products. Sensitization to this agent is reported (24). Antioxidants: Butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA)per se or BHA in combination with propyl gallate and citric acid in propylene glycol (Tenox II ©) are found in hydrous and anhydrous formulations. Each component including the vehicle (propylene glycol) of Tenox II © has been implicated in hypersensitivity reactions (25-28). Resins: Dehydroabietyl alcohol (Abitol ©) is a notorious sensitizer that may cross react with abletic acid in adhesive and with rosin (colophony) (29, 30). Miscellaneous allergens: Propylene glycol is used infrequently in eye area cosmetics. This solubilizer and antimicrobial agent is more likely to induce subjective irritation or irritant contact dermatitis than allergic contact dermatitis (31). Allergic reactions to propylene glycol are reported (28, 32). Hydrogenated lanolin and lanolin oil are used at times in eye area cosmetics. Hypersensitivity to hydrogenated lanolin has been shown to be greater than to anhydrous lanolin (33). Nickel: Eye cosmetics contaminated with nickel have been the cause of eyelid dermatitis in nickel-sensitized women. Levels of nickel as high as 250 ppm (atomic absorption spectometry) have been found in iron oxide pigments (34). Fragrance is rarely used. 4. IRRITANTS IN EYE AREA COSMETICS The irritancy potential of propylene glycol was recognized before its allergenicity (31). Soap emulsifiers, surfactants, and solvents other than propylene glycol are among the known irritants. It is anticipated that other mild irritants may be recognized in time (11). 5. ASCERTAINING THE CAUSE OF CONTACT DERMATITIS Finding the cause may be difficult, especially when more than one product is suspect, not an unusual situation. A systematic approach such as the one outlined below may be considered. Step 1: A carefully taken history of exposure is of paramount importance. It should include inquiry as to agents other than eye area cosmetics that are known to elicit contact dermatitis, the introduction of a new product, and the renewal or refill of a