deodorant

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Roll-on deodorant Rexona "Degree" brand

Deodorants are substances applied to the body mainly to reduce body odor caused by the bacterial breakdown of perspiration. A subgroup of deodorants, antiperspirants, prevent odor and reduce sweat produced by parts of the body. Antiperspirants are typically applied to the underarms, while deodorants may also be used on feet and other areas in the form of body sprays.

Overview

Stick antiperspirant/deodorant

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Human perspiration is largely odorless until it is fermented by bacteria. Bacteria 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 pH basic soaps, the skin loses its acid mantel (pH 4.5 - 6), raising the pH to become basic^{[citation needed]}. Bacteria thrive in high pH or base environments. Creating such an environment in the armpit makes it more susceptible to bacterial colonization.^[1] The bacteria feed on the sweat from the apocrine glands and on dead skin and hair cells, releasing 3-methyl-2-hexenoic acid in their waste, which is the primary cause of body odor.^[2] 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.^[3]

Deodorants are classified and regulated as over-the-counter (OTC) cosmetics by the U.S. Food and Drug Administration (FDA)^[4] and are designed to eliminate odor. The first commercial deodorant, Mum, was introduced in the late nineteenth century. Deodorants are usually alcohol-based. Alcohol initially stimulates sweating, but may also temporarily kill bacteria.^[5] Deodorants can be formulated with other, more persistent antimicrobials such as triclosan, or with metal chelant compounds that slow bacterial growth. Deodorants may contain perfume fragrances intended to mask the odor of perspiration. Natural substances, such as hops extract,^[6] are sometimes used as the antimicrobial agent.

Deodorants may be combined with antiperspirants — classified as drugs by the FDA — which attempt to stop or significantly reduce perspiration and thus reduce the moist climate in which bacteria thrive. Aluminium chloride, aluminium chlorohydrate, and aluminium-zirconium compounds, most notably Aluminium zirconium tetrachlorohydrex gly and Aluminium zirconium trichlorohydrex gly, are the most widely used antiperspirants. Aluminium-based complexes react with the electrolytes in the sweat to form a gel plug in the duct of the sweat gland. The plugs prevent the gland from excreting liquid and are removed over time by the natural sloughing of the skin. The metal salts work in another way to prevent sweat from reaching the surface of the skin: the aluminum salts interact with the keratin fibrils in the sweat ducts and form a physical plug that prevents sweat from reaching the skin’s surface. Aluminum salts also have a slight astringent effect on the pores; causing them to contract, further preventing sweat from reaching the surface of the skin.^[7] The blockage of a large number of sweat glands reduces the amount of sweat produced in the underarms, though this may vary from person to person.

The modern formulation of the antiperspirant was patented by Jules Montenier on January 28, 1941.^[8] This patent addressed the problem of the excessive acidity of aluminium chloride and its excessive irritation of the skin, by combining it with a soluble nitrile or a similar compound.^[9] This formulation was first found in "Stopette" deodorant spray, which Time Magazine called "the best-selling deodorant of the early 1950s".^[10] "Stopette" gained its prominence as the first and long-time sponsor of the game show What's My Line?, and was later eclipsed by many other brands as the 1941 patent expired.

A popular alternative to modern commercial deodorants is ammonium alum, which is a common type of alum 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.

Deodorants and antiperspirants come in many forms. What is commonly used varies in different countries. In Europe, aerosol sprays are popular, as are cream and roll-on forms. In the United States, solid or gel forms are dominant.

Health effects

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A small percentage of people are allergic to aluminium and may experience contact dermatitis when exposed to aluminium containing deodorants.^[11]

Aluminium neurotoxicity

Aluminium, present most often in antiperspirants, but not usually present in non-antiperspirant deodorants, has been established as a neurotoxin in very high doses.^{[12][13][14][15]} At high doses, aluminum itself adversely affects the blood-brain barrier, is capable of causing DNA damage, and has adverse epigenetic effects.^[12][16] Research has shown that high doses of the aluminum salts used in antiperspirants have detrimental effects to a number of species such as non-human primates,^[17] mice,^[18] dogs^[19] and others. An increased amount of aluminum is also present in the brains of many Alzheimer's patients, although this link does not seem to be causal.^[20][21][22]

Experiments with mice applying aqueous solution of aluminum chloride to the skin resulted in "a significant increase in urine, serum, and whole brain aluminum"^[23] and transplacental passage.^[18]

Cancer

Rumors^[24][25] surfaced on the Internet in the 1990s that antiperspirants have a link in causing breast cancer; these are now widely considered to be an urban myth.^[26] According to the National Cancer Institute (NCI) and the American Cancer Society (ACS), these claims are largely unsubstantiated by scientific research.^[27][28]

NCI considered two studies that address the breast cancer claims: A 2002 study of over 800 patients at Fred Hutchinson Cancer Research Institute that found no link between breast cancer and the use of antiperspirant/deodorant;^[29] and a study of 437 cancer patients, published in 2003 by the European Journal of Cancer Prevention, which found a correlation between earlier diagnosis of breast cancer and antiperspirant/deodorant use.^[30] The NCI's analysis of the second study said that it "does not demonstrate a conclusive link between these underarm hygiene habits and breast cancer. Additional research is needed to investigate this relationship and other factors that may be involved."^[31]

One school of thought, advanced by the studies of researcher Dr. Phil Darbre, hypothesizes that particular substances in deodorants, such as preservatives called parabens, or bolts such as aluminum chloride used in antiperspirants, get into the bloodstream or accumulate in breast tissue, where they enhance or emulate the effects of estrogen, which stimulates the growth of cancerous breast cells.^[32][33] The ACS and other scientists consider these studies to be early and inconclusive, but merit further research; Darbre also stated that her findings did not show causality. The main reservations have to do with the source and significance of the parabens or other toxic substances.^[34] Michael Thun, MD, of the ACS argued that even if some of the substances in antiperspirants do promote tumor growth, the risk from cosmetic use appears minuscule compared with other known tumor promoters — from 500 to 10,000 times less potent than taking oral estrogen or being obese.^[35]

Renal dysfunction

The FDA warns "that people with renal dysfunction may not be aware that the daily use of antiperspirant drug products containing aluminum may put them at a higher risk because of exposure to aluminum in the product."^[36] The agency warns people with renal dysfunction to consult a doctor before using antiperspirants containing aluminum.

Clothing

Aluminum zirconium tetrachlorohydrex gly, a common antiperspirant, is a cause of "armpit stains" on clothing, reacting with sweat to create yellow stains.^[37]

See also

Look up deodorant or antiperspirant in Wiktionary, the free dictionary.

• Air freshener
• Body odor
• Perfume

References

Wikimedia Commons has media related to: Deodorant