A deodorant is a substance applied to the body to prevent body odor caused by the bacterial breakdown of perspiration in armpits, feet, and other areas of the body. A subgroup of deodorants, antiperspirants, affect odor as well as prevent sweating by affecting sweat glands.Antiperspirants are typically applied to the underarms, while deodorants may also be used on feet and other areas in the form of body sprays. Aerosol antiperspirant products may, however, be applied to non-underarm body areas where excessive sweating (hyperhidrosis) is a problem. Aerosol antiperspirants may be particularly helpful to control sweat on the feet. It's recommended that a person try the antiperspirant on a small area of the skin first, to make sure that he/she does not have a reaction to it. Solid-form antiperspirants may be used along the hairline or bra line if these areas have problematic sweating. Again, test on a small area of the skin first. In the United States, the Food and Drug Administration classifies and regulates most deodorants as cosmetics, but classifies antiperspirants as over-the-counter drugs.The first commercial deodorant, Mum, was introduced and patented in the late nineteenth century by an inventor in Philadelphia, Pennsylvania, whose name has been lost to history. The product was briefly withdrawn from the market in the U.S., but is currently available at U.S. retailers under the brand Ban. The modern formulation of the antiperspirant was patented by Jules Montenier on January 28, 1941. This formulation was first found in "Stopette" deodorant spray, which Time Magazine called "the best-selling deodorant of the early 1950s". Stopette was later eclipsed by many other brands as the 1941 patent expired.A small percentage of people are allergic to aluminum and may experience contact dermatitis when exposed to deodorants containing aluminium. There is a popular myth that deodorant use is linked to breast cancer, but research has shown no such link exists.