Usually associated with use in skin lighteners, hydroquinone may also be a contaminant in other cosmetics ingredients. It's one of the worst ingredients used in personal care products and may disproportionately affect women of color, who are more likely to be exposed to hydroquinone if they use skin lightening products.
Products That May Contain Hydroquinone
Hydroquinone is commonly found in products marketed to lighten the skin, and is one of the most toxic ingredients still used in cosmetics. It is marketed most aggressively to women of color who also tend to use a greater number of beauty care products (i,ii). As a result, individuals who use skin lighteners with hydroquinone may also use other products with highly toxic ingredients, such as those found in hair relaxers, hair colorings, nail products and some glues used in hair extensions. Very little research has explored how the health effects of a single chemical are increased with exposure to other chemicals, but the research that has been done suggests that some effects are considerably magnified (iii).
In addition to its purposeful use in skin lighteners, hydroquinone may be an impurity in ingredients commonly found in facial and skin cleansers, facial moisturizers and hair conditioners. These ingredients include tocopheral acetate, found in 24.9 percent of products in the Environmental Working Group's Skin Deep database; tocopheral, found in 12.1 percent of products; tocopheral linoleate and other ingredients with the root toco.
Hydroquinone works by decreasing the production of melanin pigments in the skin. Because the chemical lightens skin by reducing melanin, it simultaneously increases exposure to UVA and UVB rays deep in the skin (iv). This increases skin cancer risks due to UV exposure, in addition to the carcinogenic effects of the chemical itself. The chemical is allowed in personal care products in the United States in concentrations up to 2 percent. Although banned in the European Union, a UK news report found that products containing hydroquinone were relatively easy to procure.
The U.S. Cosmetics Ingredient Review Panel indicates that hydroquinone is unsafe for use in products that are left on the skin (v,vi), but due to lax enforcement, directions for skin lightening products containing hydroquinone encourage frequent and consistent use on the skin (vii).
The Environmental Working Group's Skin Deep database, which compares cosmetic ingredients to more than 50 international toxics databases, identifies hydroquinone as a carcinogen, immunotoxicant and developmental and reproductive toxicant, and also identifies concerns regarding the ingredient's risks for various organ systems, the endocrine system and neurotoxicity (viii).
In addition to concerns about long-term toxicity, hydroquinone is linked to a skin condition called ochronosis in which the skin becomes dark and thick (ix).
i Malkan, S (2007). Not Just a Pretty Face: The Ugly Side of the Beauty Industry, pp. 70-71. Gabriola, BC, Canada: New Society Publishers.
ii MRI Buying Styles Fall 2005; Roper NOP World Health and Beauty Aids Study May 2005; Yanklevich Monitor Multicultural Marketing Study 2005 (in collaboration with Burrell and Karzenny/FSU), as reported on Essence.com.
iii Gray, J (2008). State of the Evidence: The Connection between Breast Cancer and the Environment. San Francisco, CA: Breast Cancer Fund.
iv Jimbow, K., Obata, H., Pathak, M. A. and Fitzpatrick, T. B., 1974. Mechanisms of depigmentation by hydroquinone. Journal of Investigative Dermatology 62, pp. 436449.
v CIR (Cosmetic Ingredient Review Expert Panel) Final report on the safety assessment of t-butyl hydroquinone. 1986.Journal of the American College of Toxicology 5, pp. 329351.
vi CIR (Cosmetic Ingredient Review Expert Panel) Final report on the safety assessment of t-butyl hydroquinone, 1991. Journal of the American College of Toxicology 10, pp. 17.
vii Environmental Working Group. Skin Deep. Product search for Physicians Complex 6% Skin Bleaching Cream owned by CosMed. Online at www.cosmeticsdatabase.com. Accessed July 23, 2008.
viii Environmental Working Group. Skin Deep. Hydroquinone. Available online: http://www.cosmeticsdatabase.com/ingredient.php?ingred06=703041. Accessed December 9, 2008.
ix Burkhart CG (2007). Ochronosis. Emedicine. http://www.emedicine.com/DERM/topic476.htm. Accessed July 23, 2008.