Environmental Health: Health Effects of Aluminum and Its Compounds

Health Effects of Aluminum and Its Compounds

 

■  Properties

Aluminum is a lightweight, silver-white metal and is the most abundant metal element in the Earth's crust. It is highly reactive and is not found in its pure metallic form in nature. Instead, it is typically found combined with other elements, most commonly oxygen, silicon, and fluorine, in various natural sources such as soils, minerals (like sapphire, ruby, and turquoise), rocks (especially igneous rocks), and clays. Aluminum finds wide-ranging applications, including the production of beverage cans, pots and pans, airplanes, foil, as well as its use in antacids, food additives, and many other products.

 

■   Globally Harmonized System of Classification & Labeling of Chemicals

H250: Catches fire spontaneously if exposed to air H261: In contact with water releases flammable gas

 

■    Environmental exposure in the general population

In the general population, aluminum is mainly exposed through the digestive system, food such as flour and baking powder, and consumer products such as antacids and cosmetics. The average adult in the United States consumes approximately 7-9 mg of aluminum per day through food. Aluminum enters the body through the lungs in small amounts through the air.

 

■     Occupational exposure

Occupational exposure to aluminum occurs primarily in the mining and processing of aluminum ore, in the production of aluminum metal, alloys and compounds, and in secondary industries that use aluminum products. In the case of occupational exposure, respiratory exposure is more problematic than oral exposure, and an example is the occurrence of pulmonary fibrosis in aluminum industry workers.

 

■    Biological properties and mechanisms

When people breathe in aluminum at work, about 2% of it gets absorbed into their bloodstream. If they consume aluminum through water, only about 0.1-0.4% is absorbed, but this rate increases if they consume it with citrate or in acidic conditions.

Aluminum can hitch a ride across the blood-brain barrier with transferrin, a protein that carries iron and has receptors in many tissues.

In the body, about 60% of aluminum goes to the bones, 25% to the lungs, 10% to muscles, 3% to the liver, and 1% to the brain. As people age, the amount of aluminum in their tissues tends to increase.

Most of the aluminum in the blood (over 95%) is filtered out by the kidneys and ends up in urine. If someone's kidneys aren't working well, they might have higher aluminum levels, which can lead to brain and bone problems.

Aluminum can mess with how the body absorbs other stuff in the gut. For example, it blocks fluoride absorption and lowers how much calcium, iron, and salicylic acid the body can take in. If aluminum grabs onto phosphorus, it can lead to phosphate levels dropping and potentially cause bone softening. It also slows down gut movement, which is why aluminum-based antacids often cause constipation.

 

 

■    Environmental health effects

 

<Acute Effects>

Aluminum poisoning isn't common in the short term. Most cases happen in people with kidney problems or those exposed to aluminum at work. The main organs affected are the lungs, bones, and central nervous system.

 

<Chronic Effects>

Lungs and Bones: Breathing in aluminum dust at work can lead to lung scarring (pulmonary fibrosis). When healthy people consume too much aluminum from antacids, it can cause softening of the bones (osteomalacia). This happens because aluminum messes with how the body absorbs phosphate. It can also happen in kidney patients exposed to aluminum during dialysis.

 Nervous System: Aluminum harms the nervous system in lab animals, causing nerve damage and even death. While there's evidence of this in animals, it's not well-studied in humans.

 

<Dialysis Dementia>

 This is a slow brain disorder seen in people on long-term dialysis for kidney failure. It starts with speech problems and leads to dementia, seizures, and muscle jerks. It's thought to be caused by aluminum poisoning. Patients get aluminum from medications given during dialysis. To prevent it, doctors should avoid giving aluminum-based meds and check aluminum levels in dialysis fluid.

 

■     References

• Casarett & Doull’s Toxicology : The Basic Science Of Poisons, 2019.
• ATSDR. Toxicological Profile for Aluminum. Atlanta, GA: Agency for Toxic Substances and Disease Registry; 2008.
• Available at: https://www. atsdr.cdc.gov/toxprofiles/TP.asp?id=191&tid=34.
• Whitehead MW, Thompson RP, Powell JJ. Regulation of metal absorption in the gastrointestinal tract. Gut. 1996;39:625–628.
• Rubio C, Rubio-Osornio M, Retana-Marquez S, et al. In vivo experimental models of epilepsy. Cent Nerv Syst Agents Med Chem. 2010;10:298–309.
• Kandimalla R, Vallamkondu J, Corgiat EB, et al. Understanding aspects of aluminum exposure in Alzheimer’s disease development. Brain Pathol. 2016;26:139–154.