In animal studies, aluminum has demonstrated toxic effects at very high levels and chronic exposure, however, some studies on aluminum ammonium sulfate specifically did not show toxic effects. While aluminum is the most abundant metallic element in Earth’s crust and some exposure to it is normal from the air, water, earth, soil, and food, there is limited research on how exposure to aluminum added into food may affect humans. However, some research has determined potential associations between aluminum exposure and illnesses like Alzheimer’s disease and cancer. Other research has not confirmed these negative health associations. The amounts of aluminum used in food additives are regulated to ensure low levels of exposure to aluminum, however, some researchers have suggested that the burden of aluminum has grown and an individual may be unknowingly exposed to higher levels than thought.