Aluminum is the third most abundant element in the Earth's crust and the most abundant metallic element. Present in all environmental media in the form of salts and oxides, its physicochemical properties also make it a widely used metal for various applications: construction, transportation, packaging, food processing, kitchenware, pharmaceuticals, surgery, cosmetology, and drinking water treatment. Measuring aluminum levels is challenging, and although its toxicity depends on its speciation, only total aluminum is typically measured in environmental and biological matrices. Regardless of the route of exposure, aluminum absorption is low (less than 1% for oral and dermal routes, up to 3% for the respiratory route). Human exposure is primarily dietary, with less than 5% of intake coming from drinking water in France. Deodorants and antiperspirants can also be a significant source of aluminum intake. The most exposed populations currently include dialysis patients, long-term users of antacids, and aluminum industry workers. The toxic effects of aluminum, observed during high levels of chronic exposure, are primarily neurological (encephalopathy, disturbances in psychomotor functions), skeletal (osteomalacia), and hematological (microcytic anemia). Aluminum is also responsible for immunological and allergic reactions. Other suspected effects have not been confirmed, notably Alzheimer’s disease. (R.A.)