**3.5 Hair disorders**

Human hair is naturally exposed to a certain amount of chromium [104] that come from various sources [105–107]. Excessive and repeated exposures of chromium in certain environmental condition cause discoloration of blond, dyed-blond, and white hair (to become green) [108–110] and cause rapid hair fall [111, 112]. The mechanisms of these two effects are still unclear. Hair discoloration is probably the result of interaction between chromium ions (and also copper and nickel) and protein in hair (keratin) [113], while rapid hair fall may be related to several mechanisms such as promoting premature end of hair cycle [114] or disruption of hair shaft formation [115].
