Final Amended Safety Assessment of Hydroquinone as Used in Cosmetics

Abstract

Hydroquinone is an aromatic compound that functions in cosmetics as an antioxidant, fragrance, reducing agent, or polymerization inhibitor. Hydroquinone is also used as a skin bleaching agent. Safety and toxicity information indicate that hydroquinone is dermally absorbed in humans from both aqueous and alcoholic formulations and is excreted mainly as the glucuronide or sulfate conjugates. Hydroquinone is associated with altered immune function in vitro and in vivo in animals and an increased incidence of renal tubule cell tumors and leukemia in F344 rats, but the relevance to humans is uncertain. Quantitatively, however, the use of hydroquinone in cosmetics is unlikely to result in renal neoplasia through this mode of action. Thus, hydroquinone is safe at concentrations of ≤1% in hair dyes and is safe for use in nail adhesives. Hydroquinone should not be used in other leave-on cosmetics.

Chemical characterization and bioactive properties of two aromatic plants: Calendula officinalis L. (flowers) and Mentha cervina L. (leaves)

“…The composition of free sugars, organic acids and tocopherols of the dry plants and infusions is presented in Table 2. There is scarce information about C. officinalis, except regarding its use as a cosmetic ingredient 6 and its composition in water-soluble polysaccharides, 30 while no information about M. cervina was found. Five free sugars were identified in C. officinalis (xylose, fructose, glucose, sucrose and trehalose), while xylose could not be found in M. cervina.…”

“…5 According to the literature, the major constituents of C. officinalis included steroids, terpenoids, triterpenoids, phenolic acids, flavonoids and carotenoids. 6 Several reports experimentally confirm the pharmacological activities of this plant and also of its isolated compounds, including anti-inflammatory, anti-edematous, anti-HIV, 10 antibacterial and antifungal 3 activities, and wound healing by in vivo assays 7,8 and clinical trials in patients with head-and-neck cancer. 9 Other reported activities include immuno-stimulating and immunomodulatory, 11 spasmolytic, spasmogenic and gastroprotective, 12,13 insecticidal, 14 heart rate decrease, 15 cardioprotective, 16 geno-toxic and antigenotoxic dose-dependent, 17 antioxidant 4,[18][19][20] and antitumoral effects.…”

In vitro Dermal Absorption of Hydroquinone: Protocol Validation and Applicability on Illegal Skin-Whitening Cosmetics

“…This compound is known to have stability problems because it easily oxidizes to benzoquinone [17,18]. A brown/black discoloration appears when no precautions are taken to prevent oxidation.…”

Reduction in facial hyperpigmentation after treatment with a combination of topical niacinamide and tranexamic acid: a randomized, double‐blind, vehicle‐controlled trial

“…Irregular facial hyperpigmentation is a substantial contributor to the aged appearance of skin . As a result, technology that can effectively address pigment appearance is of interest, especially given proposed regulatory changes limiting the use of hydroquinone . Niacinamide is a member of the vitamin B3 family and can be used as an ingredient in cosmetic moisturizers.…”