Aluminum is what gives antiperspirants their wetness-fighting ability, and they're highly effective. Commercial deodorants can contain up to 25 percent aluminum salts by weight.

Nobody really knows what aluminum does in the human body.

Dr. Philippa Darby of the U.K.'s University of Reading recently published a paper in the Journal of Applied Toxicology showing that aluminum salts increase estrogen-related gene expression in cultured human breast cancer cells.

In other words, the aluminum appears to mimic estrogen under lab conditions. Elevated estrogen levels are tied to a higher risk of breast cancer.

Thai Sticks — are large, smooth crystals of potassium alum (potassium aluminum sulfate). Potassium alum is a naturally occurring form of aluminum salt. The difference between potassium alum and aluminum chlorohydrate is that potassium alum is a much larger molecule, not thought to be absorbable through human skin. Wet the stone and apply it like a conventional roll on. Rinse and set it aside to dry. That's it.

Mainline manufacturer Adidas also makes a non-aluminum deodorant: Adidas 24-Hr Control.