Aluminum is not present in deodorants, but it is a common ingredient in antiperspirants. The main function of aluminum in antiperspirants is to reduce sweating by blocking the sweat ducts on the skins surface. When applied, aluminum salts in antiperspirants dissolve on the skin and "melt" into the pores, plugging them up and preventing some of the sweat from being released. This blocking action helps to reduce the amount of sweat that reaches the skin's surface, keeping you dry.
Some research suggests that aluminum-containing underarm antiperspirants, which are applied frequently and left on the skin near the breast, may be absorbed by the skin and have estrogen-like (hormonal) effects. Because estrogen can promote the growth of breast cancer cells, some scientists have suggested that the aluminum-based compounds in antiperspirants may contribute to the development of breast cancer. However, no studies to date have confirmed any substantial adverse effects of aluminum that could contribute to increased breast cancer risks.
