Aluminum (Al) is the most abundant metal in the crust of the earth with 27Al as the naturally occurring isotope. Aluminum is found in cookware, infant formula,21 foil, vaccines as an adjuvant to boost immune response,28 antiperspirants, antacids, and phosphate binders. It is also known to contaminate in 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.97 It has many industrial uses after extraction from bauxite. In the body, aluminum exists as a trivalent cation (Al3+). In this chapter, aluminum metal is discussed as an occupational toxin with mainly lung manifestations. Aluminum salts, the more common form discussed for aluminum toxicity, primarily act as neurotoxins with both acute and chronic toxicity.
Aluminum is a nonessential element and a trace metal with a single oxidation state, Al3+. Aluminum is the most abundant metal in the earth's crust where it is found in many types of ores: bauxite, gibbite, boehmite, as alumina, and in gems like ruby, sapphire, and turquoise.
The aluminum industry is one of the world's largest industries. 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
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"). These workers had a higher incidence of asthma than the general population.22 In 1947, another report described German workers who developed pulmonary fibrosis after exposure to high concentrations of aluminum dust (also called "pyro powder") mixed with mineral oil–based lubricants. This pulmonary fibrosis, "aluminosis," was present in 26% of the workers.24 Some potroom workers also developed neurologic findings described as a progressive encephalopathy and termed "potroom palsy."45,51 Initially described in 1962, these patients had balance problems, impaired memory, an intention tremor, and decreased cognitive ability.51,70
In the 1970s, encephalopathy in patients with renal failure was attributed to using aluminum-salt-containing phosphate binders or, more rarely, to aluminum-contaminated dialysis fluid. This clinical syndrome known as "dialysis dementia" developed after years of HD. Manifestations included dyspraxia and multifocal seizures.7 By 1976, elevated serum aluminum concentrations were reported in encephalopathic HD patients.6 Both the relationship between aluminum and microcytic anemia and the connection between aluminum and osteomalacia in dialysis patients were recognized in 1978.17,...