Aluminum toxicity species differences

Aluminum-hydroxy species are known to exhibit different biological activity. For xample, data have shown that some leafy plants are sensitive to Al3+ while others are mown to be sensitive to Al(OH) monomers. It has also been shown that polymeric duminum (more than one A1 atom per molecule) is toxic to some organisms. Alumi-lum is one of the cations most difficult to predict in the soil solution. This is because t has the ability to form complex ions such as sulfate pairs and hydroxy-AI monomers ind polymers. 

Several animal studies have examined potential age-related differences in the distribution, neurotoxicity, skeletal toxicity, and interactions of aluminum. However, conflicting results have been found and the database is not adequate to assess whether these differences are due to the animal species tested, the aluminum compound used, or the route of exposure. Additionally, there are no studies on the influence of immature renal function on aluminum retention in the body and no studies on the long-term effects of aluminum exposure on skeletal maturation or neurotoxicity. Multiple species studies examining a wide range of effects in immature, mature, and older animals would be useful in assessing the children s susceptibility to the toxicity of aluminum. 

Arsenic consists of two major oxyanions, As(III) and As(V) in water (Smedley et al, 2002). These two As species exhibit very different affinities to the mineral surfaces, and the retention of both As(V) and As(III) is strongly pH dependent (Meng et al, 2000) Both inorganic and organic states of the As(III) tend to be more toxic to humans than those of the As(V) forms. The efficiency of most separation methods for As(III) removal is low. To obtain an effective and efficient separation, an oxidation process, which can convert As(III) to As(V), is necessary. Upon efficient oxidation, as a pretreatment, the total removal of As can be effectively improved (Bissen et al, 2003). Different oxidants have been investigated in the As oxidation process, e.g. O2, O3, H2O2, zero-valent aluminum and iron, activated carbon and manganese (Bissen et al, 2003). 

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