What are aluminum salts in general?
Aluminum is a metal that we find everywhere today. In the form of foil, as cans for soft drinks and food or as a material in industry and private use. For years it has also been found in the form of metal salts in deodorants and antiperspirants. Antitranspirantien.
What are aluminum salts?
Metals can undergo ionic bonding by donating one or more electrons to a suitable nonmetal partner. Electromagnetic forces now hold these partners together. The most commonly used aluminum salt in deodorants is aluminum hydroxychloride (ACH).
It consists of a mixture of different aluminum salts with the recurring constituents, Al (aluminum), Cl (chlorine) and OH (hydroxide).
Why are aluminum salts used in deodorants?
ACH prevents excessive perspiration, reliable and long-lasting. It is relatively cheap, easy to dose and therefore has an excellent price-performance ratio. It can be used without limit, and is therefore, with many cosmetics manufacturers, very popular. In addition, there are few alternatives that fulfill this job as well as they do.
What are the problems with aluminum salts?
ACH acts in two main ways:
1) It extracts moisture from the skin, thus narrowing the sweat channels of the skin
2) It partially denatures the skin's proteins, creating a film over the skin that penetrates and blocks the pores and sweat ducts.
So Aluminum salts are proven to dry out the skin and destroy proteins to counter sweat. 
Also, ACH is a neurotoxin, which at higher concentrations affects the blood-brain barrier, a natural barrier to central nervous system (CNS) fluid trajectories. It can damage the DNA and affect the activities of genes. 
In addition, they are in strong suspicion to trigger breast cancer and Alzheimer's, but this is still controversial and it is disputed whether elevated aluminum concentrations in breast cancer tissue as a trigger or even as a by-product.
The fact is, however, that larger amounts of aluminum do not stay in the body and are separated from the kidneys, and then excreted. In humans with renal diseases such as kidney hypofunction, aluminum can accumulate in the body.
Are there natural and harmless alternatives?
Yes and at the same time no. There are some competitors who are harmless and gentle, but do not work comparably well with ACH. However, compromises must be made, and one's own health preceded by a slightly better performance.  
As alternatives, there are deodorants, which reduce the acidic environment by basic minerals, and thus the growth of bacteria, and thus malodour. They also partially protect against sweat leakage. But also natural oils and extracts such as grape, coriander, pomegranate or sage help to suppress odors. With fats and waxes, such as berries and beeswax, cocoa, and shea butter, excessive sweating can be avoided, at least for the most part.  
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