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Aluminum (Al) is the most abundant metal in the crust of the earth, where it is found in many types of ores: bauxite, gibbite, boehmite, as alumina, and in gems such as ruby, sapphire, and turquoise. The most naturally occurring isotope is27 Al. Aluminum is a nonessential element and a trace metal with a single oxidation state, Al3+.
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The aluminum industry is one of the largest industries in the world. Aluminum ores are converted to alumina and then reduced to aluminum metal. The first step usually involves refining bauxite at high temperature and pressure in a caustic soda to form alumina (aluminum oxide, Al2O3). The second step occurs by a special method, the Hall-Heroult process, in potrooms and uses electrolytic reduction to form aluminum. Aluminum is then used alone or is processed into alloys to build a variety of products that are anticorrosive.16 Aluminum is found in cookware, infant formula,21 foil, vaccines as an adjuvant to boost immune response,28 antiperspirants, antacids, and previously, in phosphate binders. It also contaminates hemodialysis (HD) fluids, intravenous (IV) fluids, total parenteral nutrition (TPN),38 albumin,39 and as alum solution (potassium aluminum sulfate or ammonium aluminum sulfate)—an astringent for bladder irrigation.96 In this chapter, aluminum metal is discussed as an occupational toxin with mainly lung manifestations. Aluminum salts, the more common form discussed in aluminum toxicity, primarily act as neurotoxins, with both acute and chronic toxicity.
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HISTORY AND EPIDEMIOLOGY
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The first case of aluminum toxicity with neurologic findings was reported in 1921. This patient had memory loss, tremor, and impaired coordination.86 Subsequently, a case series described occupational asthma in Norwegian aluminum (potroom) workers (“potroom asthma”).22 In 1947, 26% of German potroom workers exposed to high concentrations of aluminum dust mixed with mineral oil–based lubricants developed pulmonary fibrosis, “aluminosis”.24 Some potroom workers also developed neurologic findings described as a progressive encephalopathy and termed “potroom palsy,” with balance problems, intention tremors, decreased cognitive ability, and impaired memory, initially described in 1962.45,51,71
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In the 1970s, encephalopathy in patients with chronic kidney disease (CKD) was attributed to using aluminum salt–containing phosphate binders or, more rarely, to aluminum contaminated dialysis fluid. This clinical syndrome, known as “dialysis dementia,” develop after years of HD.77 By 1976, elevated serum aluminum concentrations were reported in encephalopathic HD patients.66 Both the relationship between aluminum and microcytic anemia as well as the connection between aluminum and osteomalacia in dialysis patients were recognized in 1978.17,88
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In 1982, alum (potassium aluminum sulfate or ammonium aluminum sulfate) was first used in the treatment of hemorrhagic cystitis.64 Neurotoxicity can develop if patients absorb alum systemically, especially if kidney insufficiency is present.
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More recently, aluminum has been linked to the spongiform leukoencephalopathy ...