If an aluminum compound, such as aluminum chlorohydrate or aluminum zirconium, which is very soluble, is used as an antiperspirant, that compound is readily absorbed. Once in the body, the aluminum portion of the molecule ionizes, forming free or radical aluminum (Al+++). This passes freely across cell membranes, and forms a physical plug, that when dissolved is selectively absorbed by the liver, kidney, brain, cartilage and bone marrow. It is this concentration of aluminum that has been the source of concern in the medical community and has prompted the research being done on alzheimer's disease and breast cancer victims. Potassium alum molecules have a negative ionic charge, making it unable to pass through the cell wall. They are not absorbed. This is why our deodorants are safe to use and will not cause high levels of aluminum in your system. Alum and aluminum are two different substances, with distinct chemical signatures. They possess different chemical properties which create different chemical attributes.