Mechanisms of aluminium neurotoxicity in oxidative stress-induced ...

INTRODUCTION
and [Al13(OH)30] 9+ . The solid Al(OH)3 is the predominant species in the neutral pH
range, whereas the soluble tetrahedral aluminate [Al(OH)4] - predominates above pH 8.
Figure 21: Mole fraction of soluble aluminium ions as a function of solution pH in aqueous solution
(Priest 2004)
Sources of aluminium exposure
Environmental exposure
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Aluminium and its compounds are widely distributed in the environment
although most naturally occurring aluminium is bound and not readily bioavailable. As
example, this metal is present in a variety of minerals, such as silicates (feldspars and
micas), complexed with fluorine and sodium as cryolite, and is chiefly mined as
bauxite, a mineral containing 40-60% aluminium oxide (alumina) (Ganrot 1986).
Aluminium is a major constituent of atmospheric particulates, primarily found as
alumino-silicates, originating from natural soil erosion, mining or agricultural activities,
volcanic eruptions, or coal combustion. Atmospheric aluminium concentrations were
reported to range generally from 5 to 180 µg/m 3 (Sorenson et al. 1974) whereas
concentrations in industrial areas are often in the milligram per cubic meter range.