COSMETICS AND BATHROOM PRODUCTS:DEODORANT/ANTIPERSPIRANT.

DEODORANT/ANTIPERSPIRANT

Sweat (perspiration) is the fluid produced by the secretory portion of the 3 to 4 million sweat (also called sudoriferous) glands located in the sub- cutaneous and/or dermis of the skin. There are two types of sweat glands, eccrine and apocrine, differentiated by their structure, location, and secretion chemistry. Eccrine glands are distributed throughout most of the skin and are highly concentrated on the palms, soles, forehead, face, and axillae (armpits). These glands function throughout life and secrete a slightly acidic solution containing a mixture of water, inorganic ions (e.g., sodium, potassium, and chloride), lactic acid, ascorbic acid, amino acids, urea, uric acid, ammonia, and glucose. This secretion tends to have no odor, and the body may be generally cooled after the evaporation of skin surface water from the eccrine-based sweat. However, bacteria (e.g., Staphylococcus species) may act on perspiration residue and sebum (natural body oil) to produce unpleasant odiferous products such as short-chain fatty acids and amines.

Apocrine glands, which secrete their products into hair follicles, are concentrated mainly in the skin of the axillae, pubic region, and pigmented areas of the breasts. Apocrine glands first function at the start of puberty and produce a more viscous solution than eccrine glands. Apocrine glands are typically stimulated during emotional stresses and sexual excitement. While these apocrine secretions alone yield little odor, bacteria that colonize nearby hair follicles may degrade the contents of apocrine fluids, producing malodorous chemicals.

Deodorants are products that typically contain a fragrance (e.g., musk scent from ethylene dodecanedioate) or perfume to disguise offending body odor and a germicide to destroy odor-producing bacteria. The germicide is usually a long-chain quaternary ammonium salt, various salts of zinc, a phenol such as triclosan, a chemical such as benzethonium chloride, or a broad-spectrum antibiotic (e.g., neomycin). In 1888, an unknown inven- tor from Philadelphia formulated deodorant, which contained zinc oxide. It was generally recognized as the first product to prevent odor and kill bacteria. Deodorants subsequently developed in the early twentieth century contained noxious chemicals such as cresylic acid or hexachlorophene.

Antiperspirants are usually deodorants that additionally impede the production of perspiration. Most antiperspirants contain active ingredients such as the aluminum chlorohydrates [e.g., Al2(OH)4Cl2 and Al2(OH)5Cl] or aluminum zirconium tetrachlorohydrex glycine complex. Aluminum salts function as astringents, producing an insoluble hydroxide gel in the sweat pores and thus physically blocking the release of secretory products by constricting the opening of the sweat gland ducts. The active ingredients in antiperspirants may also reduce odor, most likely by destroying bacteria that decompose the organic portion of the secretions. Because sweating is considered a natural, healthy body pro- cess, regular bathing and changing/washing of clothes make antiperspi- rants unnecessary for most individuals.

Deodorants and antiperspirants can be formulated into creams or lo- tions typically containing an oil base (e.g., cyclomethicone), solvents (e.g., polypropylene glycol [PPG] 14 butyl ether, stearyl alcohol, glycerin, or polyethylene glycol [PEG] 8 distearate), emollients (e.g., cyclopentasilox- ane or dimethicone), lubricants (e.g., hydrogenated castor oil or dimethicone copolyol), humectants (propylene glycol or dipropylene glycol), and antioxidant/preservatives (e.g., BHT, T-butyl hydroquinone, or cit- ric acid). Specialized brands may contain silica, talc, opacifying agents (e.g., glyceryl oleate), or antiwhitening agents (e.g., phenyl trimethi- cone). Deodorants and antiperspirants can also be dissolved in a solvent (e.g., denatured [ethanol] [SD] alcohol 40 or propylene carbonate) and applied as an aerosol with the use of a nonchlorofluorocarbon propellant (e.g., isobutane, butane, propane, 1,1-difluoroethane, or hydrofluoro- carbon 152a). The first antiperspirant aerosol deodorant was introduced in 1965. Modern aerosol antiperspirant deodorants also may contain an oil base (e.g., cyclomethicone), emollients (e.g., dimethicone), talc, silica or a modified magnesium aluminum silicate (e.g., quaternium-18 hec- torite), emulsifiers (e.g., isopropyl myristate), and fragrance.