Aluminum is a common element found throughout the environment. While ubiquitous, elevated levels in the blood, known as aluminum toxicity or hyperaluminemia, can lead to health concerns. Understanding how aluminum enters and is processed by the body helps explain factors leading to high levels.
Everyday Sources of Aluminum
Aluminum is routinely encountered through daily exposures. Food and beverages contribute significantly, as aluminum can leach from cookware, packaging, and processing equipment into the food. Acidic or salty foods, for instance, can cause aluminum to transfer from foil or cans. Drinking water also contains aluminum, often due to its use in water treatment processes, though levels vary.
Beyond food and water, aluminum is found in various consumer products. Antiperspirants commonly use aluminum salts, and some cosmetics, like lipsticks and eyeshadows, may contain the element. Certain over-the-counter medications, such as antacids and buffered aspirin, include aluminum compounds. While these sources contribute small amounts, they are generally not the primary cause of high blood levels in healthy individuals.
How the Body Manages Aluminum
The human body manages aluminum exposure, absorbing only a small fraction of ingested aluminum. Absorption primarily occurs through the gastrointestinal tract, with less than 1% of dietary aluminum entering the bloodstream. Once absorbed, aluminum travels in the blood, largely binding to proteins, predominantly transferrin.
The kidneys play the primary role in excreting absorbed aluminum. In individuals with healthy kidney function, this system efficiently filters and eliminates aluminum, preventing significant accumulation. While urine is the main route for systemic aluminum excretion, feces and sweat also contribute. If the body’s ability to excrete aluminum is compromised, even typical exposures can lead to its buildup in tissues.
Medical Conditions and Therapies
Impaired kidney function is a common cause of high aluminum levels. When kidneys are diseased, such as in chronic kidney disease or end-stage renal disease, their ability to efficiently excrete aluminum is severely reduced, leading to accumulation. This retention can result in aluminum depositing in various tissues, including bone and brain.
Patients undergoing dialysis are at particular risk for aluminum toxicity. Historically, high aluminum levels in dialysate water were a major concern, leading to “dialysis encephalopathy.” While water purification improvements have made this less common, aluminum-containing phosphate binders, prescribed to dialysis patients to control phosphorus, can still contribute to accumulation if used long-term or in high doses.
Prolonged intravenous nutrition (PN) can also be a source of aluminum exposure, especially in vulnerable populations like infants or critically ill patients. Aluminum can contaminate PN solutions, and premature infants are at higher risk due to immature kidneys and prolonged support needs. The Food and Drug Administration (FDA) recommends a daily aluminum intake limit of 5 micrograms per kilogram per day for neonates receiving total parenteral nutrition.
Certain aluminum-containing medications, when used extensively or at high doses, can also lead to elevated blood aluminum. This includes some antacids that bind to phosphate in the gut, contributing to aluminum accumulation over time. For patients with kidney dysfunction, long-term use of such medications is a particular concern, as their bodies cannot effectively clear absorbed aluminum.
High-Risk Environmental and Occupational Exposure
Beyond everyday and medical factors, certain environmental and occupational settings can lead to significantly higher aluminum exposure. Individuals working in industries such as aluminum smelting, welding, or manufacturing are at increased risk due to exposure to aluminum dust or fumes. Inhalation of these fine particles can result in their retention in the lungs, from where aluminum can be released into the bloodstream and distributed to organs like bones and the brain.
Occupational exposure limits are set to manage these risks, with permissible exposure limits for aluminum welding fumes. Long-term exposure to aluminum dust and fumes in these industrial settings has been linked to respiratory issues like pulmonary fibrosis, chronic bronchitis, and a lung disease called aluminosis. Monitoring of aluminum levels in air and workers’ biological samples is often employed to mitigate these risks.
Rare instances of highly contaminated water sources or specific geological areas can also contribute to elevated aluminum levels. Aluminum is abundant in the Earth’s crust and can naturally leach into water supplies from soil and rocks, especially in acidic environments. Industrial processes and mining activities can also release aluminum into the environment, potentially impacting local water and soil quality.