Two thirds of all deodorants contain aluminum because it closes the pores and thus prevents sweating.
However, new studies have shown (film "Akte Alu" on Arte) that aluminum could be partly responsible for breast cancer. The close proximity to the armpits prompted a researcher to take a closer look at aluminum. It was clearly shown that cancer cells develop in breast tissue in the presence of aluminum, while aluminum-free samples remained cancer-free. It was also shown that aluminum promotes the spread and formation of metastases, which ultimately leads to the death of many patients.
It was also found that people who are exposed to aluminum develop Alzheimer's prematurely. Stomach medications for acid reflux often contain large amounts of aluminum.
In animal experiments, aluminum is used to make test animals allergic to certain substances.
If, for example, aluminum is administered together with apples, the mouse is subsequently allergic to apples.

So if you want to be on the safe side, you should make sure that you don't ingest aluminum or apply it to your skin ;-)