Usually associated with use in skin lighteners, especially those products marketed to women of color, hydroquinone may also be a contaminant in other cosmetics ingredients. Linked to cancer and organ-system toxicity, it is one of the most toxic ingredients used in personal care products.
What you need to know
Found in: Skin lighteners, facial and skin cleansers, facial moisturizers, hair conditioners, nail glue
What to look for on the label: Hydroquinone, tocopheral acetate, tocopheral, tocopheral linoleate, other ingredients with the root “toco”
Health concerns: Cancer, organ-system toxicity, allergies and immunotoxicity
Vulnerable populations: Women of color
Regulations: Banned from cosmetics in the European Union; restricted use in Canadian cosmetics. The U.S. Cosmetics Ingredients Review Panel indicates that hydroquinone is unsafe for use in products that are left on the skin [1,2], but because of lax enforcement, directions for skin-lightening products containing hydroquinone encourage frequent and consistent use on the skin 
What is 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 , and its use may exacerbate health hazards when used in conjunction with other products. In addition to its use in skin lighteners, hydroquinone is an impurity that can be found in ingredients commonly used in facial and skin cleansers, facial moisturizers and hair conditioners, including natural vitamin E (tocopherol) and synthetic vitamine E (tocopherol acetate).The chemical is allowed in personal care products in the United States in concentrations up to two percent. Although banned in the European Union, a UK news report found that products containing hydroquinone were relatively easy to procure [http://www.dailymail.co.uk/femail/article-428541/Dying-whiter-The-black-women-risk-lives-lighter-skin.html].
What are the health concerns?
Cancer: 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 . This increases skin cancer risks due to UV exposure, in addition to the carcinogenic effects of the chemical itself.
Organ-system toxicity: In addition to concerns about long-term toxicity, hydroquinone is linked to a skin condition called ochronosis in which the skin (our largest organ) becomes dark and thick .
How can you avoid this?
Consumers should avoid products that list hydroquinone, and exercise caution with products that contain vitamin E in its natural or synthetic forms (tocopherol acetate, tocopherol, tocopherol linoleate, and other ingredients with the root “toco”).
Further information including links to reports and press releases:
 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. 329–351.
 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. 1–7.
 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.
 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.
 Jimbow, K., Obata, H., Pathak, M. A. and Fitzpatrick, T. B., 1974. Mechanisms of depigmentation by hydroquinone. Journal of Investigative Dermatology 62, pp. 436–449.
 Burkhart CG (2007). Ochronosis. Emedicine. http://www.emedicine.com/DERM/topic476.htm. Accessed July 23, 2008.