<P> In the early 1960s, the first aerosol antiperspirant in the marketplace was Gillette's Right Guard, whose brand was later sold to Henkel in 2006 . Aerosols were popular because they let the user dispense a spray without coming in contact with the underarm area . By the late 1960s, half of all the antiperspirants sold in the U.S. were aerosols, and continued to grow in all sales to 82% by the early 1970s . However, in the late 1970s two problems arose which greatly changed the popularity of these products . First, in 1977 the Food and Drug Administration (FDA) banned the active ingredient used in aerosols, aluminium zirconium chemicals, due to safety concerns over long term inhalation . Second, the Environmental Protection Agency (EPA) limited the use of chlorofluorocarbon (CFC) propellants used in aerosols due to awareness that these gases can contribute to depleting the ozone layer . As the popularity of aerosols slowly decreased, stick antiperspirants became more popular . </P> <P> Human perspiration is largely odorless until it is fermented by bacteria that thrive in hot, humid environments . The human underarm is among the most consistently warm areas on the surface of the human body, and sweat glands provide moisture, which when excreted, has a vital cooling effect . When adult armpits are washed with alkaline pH soap, the skin loses its acid mantle (pH 4.5 - 6), raising the skin pH and disrupting the skin barrier . As many bacteria thrive in this elevated pH environment, this makes the skin susceptible to bacterial colonization . The bacteria feed on the sweat from the apocrine glands and on dead skin and hair cells, releasing trans - 3 - methyl - 2 - hexenoic acid in their waste, which is the primary cause of body odor . Underarm hair wicks the moisture away from the skin and aids in keeping the skin dry enough to prevent or diminish bacterial colonization . The hair is less susceptible to bacterial growth and therefore is ideal for preventing the bacterial odor . </P> <P> Deodorants are classified and regulated as cosmetics by the U.S. Food and Drug Administration (FDA) and are designed to eliminate odor . Deodorants are often alcohol - based . Alcohol initially stimulates sweating, but may also temporarily kill bacteria . Other active ingredients in deodorants include sodium stearate, sodium chloride and stearyl alcohol . Deodorants can be formulated with other, more persistent antimicrobials such as triclosan that slow bacterial growth or with metal chelant compounds such as EDTA . Deodorants may contain perfume fragrances or natural essential oils intended to mask the odor of perspiration . In the past, deodorants included chemicals such as zinc oxide, acids, ammonium chloride, sodium bicarbonate and formaldehyde, but some of these ingredients were messy, irritating to the skin or even carcinogenic . </P> <P> Over-the - counter products labeled as "natural deodorant crystal" containing the chemical potassium alum, which contains aluminum, have gained new - found popularity as an alternative health product, in spite of concerns about possible contact dermatitis . A popular alternative to modern commercial deodorants is ammonium alum, which is a common type of alum, also containing aluminum, sold in crystal form and often referred to as a deodorant crystal . It has been used as a deodorant throughout history in Thailand, the Far East, Mexico and other countries . </P>

When did they start putting aluminum in deodorant