http://en.wikipedia.org/wiki/Aluminium

The toxicity of aluminium

The toxicity of aluminium can be traced to increased deposition in bone and the central nervous system, particularly in the presence of reduced renal function. Because aluminium competes with calcium for absorption, increased amounts of dietary aluminium may contribute to the reduced skeletal mineralization (osteopenia) observed in preterm infants and infants with growth retardation. Full-term infants with normal renal function do not seem to be at substantial risk from aluminium toxicity from soy protein-based formulas. Aluminium can cause neurotoxicity in very high doses which can alter the function of the blood-brain barrier.[30] It is one of the few abundant elements that have no known function in living cells. A small percentage of people are allergic to it — they experience contact dermatitis: an itchy rash from using styptic or antiperspirant products, digestive disorders and inability to absorb nutrients from eating food cooked in aluminium pans, and vomiting and other symptoms of poisoning from ingesting such products as Amphojel, and Maalox (antacids). Such allergies are extremely rare though, in other people aluminium is not considered as toxic as heavy metals, but there is evidence of some toxicity if it is consumed in excessive amounts. The use of aluminium cookware, popular because of its corrosion resistance and good heat conduction, has not been shown to lead to aluminium toxicity in general. Excessive consumption of antacids containing aluminium compounds and excessive use of aluminium-containing antiperspirants are more likely causes of toxicity. Aluminium increases estrogen-related gene expression in human breast cancer cells grown in the laboratory.[31] These salts' estrogen-like effects have led to their classification as a metalloestrogen.

It has been suggested that aluminium is a cause of Alzheimer's disease, as some brain plaques have been found to contain the metal. Research in this area has been inconclusive; aluminium accumulation may be a consequence of the Alzheimer's damage, not the cause. In any event, if there is any toxicity of aluminium it must be via a very specific mechanism, since total human exposure to the element in the form of naturally occurring clay in soil and dust is enormously large over a lifetime.[32][33]