The brain is a highly compartmentalized organ exceptionally susceptible to accumulation of metabolic errors. Alzheimer's disease (AD) is the most prevalent neurodegenerative disease of the elderly and is characterized by regional specificity of neural aberrations associated with higher cognitive functions. Aluminum (Al) is the most abundant neurotoxic metal on earth, widely bioavailable to humans and repeatedly shown to accumulate in AD-susceptible neuronal foci. In spite of this, the role of Al in AD has been heavily disputed based on the following claims: 1) bioavailable Al cannot enter the brain in sufficient amounts to cause damage, 2) excess Al is efficiently excreted from the body, and 3) Al accumulation in neurons is a consequence rather than a cause of neuronal loss. Research, however, reveals that: 1) very small amounts of Al are needed to produce neurotoxicity and this criterion is satisfied through dietary Al intake, 2) Al sequesters different transport mechanisms to actively traverse brain barriers, 3) incremental acquisition of small amounts of Al over a lifetime favors its selective accumulation in brain tissues, and 4) since 1911, experimental evidence has repeatedly demonstrated that chronic Al intoxication reproduces neuropathological hallmarks of AD. Misconceptions about Al bioavailability may have misled scientists regarding the significance of Al in the pathogenesis of AD. The hypothesis that Al significantly contributes to AD is built upon very solid experimental evidence and should not be dismissed. Immediate steps should be taken to lessen human exposure to Al, which may be the single most aggravating and avoidable factor related to AD.

Aluminum and Alzheimer's Disease: After a Century of Controversy, Is there a Plausible Link?

Effect of pH on the coagulation performance of Al-based coagulants and residual aluminum speciation during the treatment of humic acid–kaolin synthetic water

A highly selective fluorescent chemosensor for Al3+ derivated from 8-hydroxyquinoline

The synthesis and evaluation of a novel Schiff-base fluorescent probe L for detection of Al3+ are described. The structure of L was determined by X-ray and other spectroscopic data. The fluorescent spectra changes and microscopy images show that indicator L is highly selective for Al3+ not only in abiotic systems but also in living cells. Other metal ions failed to respond. The new probe could be used as an efficient tool for Al3+ monitoring in the environment and biological systems.

A selective, cell-permeable fluorescent probe for Al3+ in living cells.

Landfill leachate pretreatment by coagulation–flocculation process using iron-based coagulants: Optimization by response surface methodology

Aluminium (Al) is one of the trace inorganic metals present in drinking water. In addition to the naturally occurring Al in raw waters, use of Al-based coagulants especially Al 2(SO4)3 (alum) often leads to an increase in treated water Al concentrations. A high (3.6 to 6 mg/l) concentration of Al may precipitate as aluminium hydroxide giving rise to consumer complaints. Al is also a suspected causative agent of neurological disorders such as Alzheimer’s disease and presenile dementia. During conventional water treatment processes, Al undergoes various transformations (also called ‘speciation’ of Al) which are influenced by factor s such as pH, turbidity, temperature of water source, and the organic and inorganic ligands present in water. Chemical precipitat ion, reverse osmosis, electrodialysis and cation exchange methods are efficient in Al removal from water. This paper gives an overvi ew of the presence of Al in drinking water with reference to its speciation, removal (treatment methods), water supply and health problems, and the regulation of its levels in drinking water.

T. Viraraghavan

Papers

Aluminium in drinking water: An overview

Method development for drinking water aluminum measurement using a graphite furnace atomic absorption spectrophotometer