Is a skin-lightening agent. It bleaches the skin, which can be helpful when treating different forms of hyperpigmentation. studies in rodents show some evidence that hydroquinone may act as a carcinogen or cancer-causing chemical, although its cancer-causing properties have yet to be proved in humans. Hydroquinone also has been linked with the medical condition known as ochronosis in which the skin becomes dark and thick. Hydroquinone has already been banned in Japan, the European Union, and Australia.