Elevated hair manganese with normal blood manganese level has been reported in cases of chronic Mn
toxicity [18], emphasizing the fact that some toxic metals may be preferentially excreted in the hair. Hair
concentrations of manganese are thought to be the more accurate reflection of chronic exposure than
blood manganese which, at lower levels, can vary somewhat in the short term according to dietary intake
and thus may not reflect long-term intake or exposure. In contrast, the manganese content of hair will
reflect the metal uptake averaged over the duration of the follicle formation [19]. The mechanism of
manganese uptake into hair is not well understood, but its affinity for melanin, a coloured protein present
in hair and skin, could be involved