Vanity of vanities, all is vanity. It is amazing what people will do with the belief that they are becoming more beautiful. The folllowing is from the hydroquinone MSDS.
"Skin: May cause skin sensitization, an allergic reaction, which becomes evident upon re-exposure to this material. May cause dermatitis. Causes redness and pain. May be harmful if absorbed through the skin. Repeated exposure may cause hyperpigmentation of fair skin and depigmentation of dark skin. Causes skin irritation and possible burns. Substance is readily absorbed through the skin.