The first commercial deodorants sold in the U.S. date back to the late 19th century, when a Philadelphia outfit launched the brand Mum, packaged as a jar of cream to be scooped up and applied by hand to your underarms—a messy high-maintenance affair, to say the least. The more convenient stick form commonly sold these days didn’t make headway until the 1950s, as manufacturers began to introduce antiperspirants to their formulas, using aluminum-based compounds that temporarily block sweat pores. Recent studies, however, suggest that these compounds may be harmful to our health, and can even increase the risk of breast cancer.