Abstract
Maleic Acid is a dicarboxylic acid that functions as a fragrance ingredient and pH adjuster in cosmetics—it is used in a few cosmetic product formulations at low concentrations. Maleic Acid is commonly used in research studies to induce Fanconi syndrome in rats and dogs in an attempt to study the mechanism of this disease. One such study found decreased glomerular filtration rate in rats given 9.0 mmol/kg, but not with 1.5 mmol/kg, Maleic Acid intraperitoneally. Preincubation with 0.75 mmol/L of Maleic Acid reduced sperm penetration of golden hamster eggs to zero. Maleic Acid failed to induce any significant increases in revertant count in strains TA1535, TA1537, TA98, and TA100 at concentrations up to 7500 µg/plate. A concentration of 2.0 × 10 -2 M Maleic Acid did show a positive pattern in a DNA synthesis inhibition test. Maleic Acid at 10%, pH 1.0, applied for 30 s on rabbit eyes, caused permanent opacity. A 1% solution, pH 1.0, applied for 2 min caused cloudiness of the cornea, but no lasting injury, and a 5% solution, also at pH 1.0, had a similar but more intense effect, with recovery delayed 6 to 7 days. Application of 10µl Maleic Acid (pH not stated) to the volar forearm and labia majora of 21 female Caucasians produced an inflammatory response at 24 and 48 h, which varied from minimal erythema to marked erythema with marked vesiculation. Maleic Acid at 20% (pH not stated) applied to one forearm daily for a period of 6 weeks to 50 human subjects produced acute vesicular dermatitis in 17 subjects, who were dropped from the study. Only five of the remaining subjects accommodated to the treatment, the rest had varying degrees of inflammation or hyperirritable skin. Although Maleic Acid itself may be a dermal and/or ocular irritant, its use as a pH adjustor in cosmetic formulations dictates that most of the acid will be neutralized into various maleate salts. Therefore, the concentration of free Maleic Acid is expected to be low, and dermal or systemic toxicity is not expected to be a concern. The safety of Maleic Acid as a pH adjustor should not be based on the concentration of use, but on the amount of free Maleic Acid that remains after neutralizing the formulation. There is no reason to expect this ingredient to induce any toxicity when used for this purpose. The Cosmetic Ingredient Review (CIR) Expert Panel concluded that Maleic Acid is safe for use in cosmetic formulations as a pH adjustor in the practices of use as described in this safety assessment.