Antiperspirants and deodorants are used to mask, remove or decrease perspiration odors, prevent their development, or do all of these.
Fresh perspiration from the clean body has a mild and generally no objectionable odor. Perspiration undergoes considerable change on standing because of bacterial decomposition.
Body odor emanating from the skin is a natural phenomenon and occurs in almost all men and women if the skin is not frequently cleansed of sweat residues, sebum and bacteria. The natural bacteria flora of the skin is not removed entirely by washing with soap and water, and although the number are reduced, millions of bacterial exist. As the sweat and sebaceous gland ducts are unaffected by washing, they can rapidly multiply and replenish those which are removed by washing. Odor is produced by the breakdown of the organic fraction of sweat and sebum by the natural skin bacteria. The bacteria isolated from the skin can be divided into two groups-
a) Resident- Those bacteria which have their normal habitat on the skin surface or in the glands and ducts.
b) Transient- Those bacteria which are incidentally deposited on the skin from the atmosphere or clothing.
Both types of bacteria play a good role for body odor. Two types of sweat glands are found in body. They are- a) Eccrine or small gland which occurs all over the body and b) Apocrine or large gland which are found in association with hair follicles and sebaceous glands.
The eccrine glands open via a thin duct directly on to the surface of the skin while the apocrine glands generally open into a hair follicle. The eccrine glands are true secretory glands producing clear aqueous sweat that assists the regulation of body temperature by evaporation. These glands respond to thermal stimuli and also to reflexes of the central nervous system and hence are responsible for both hot and cold sweating. On the other hand apocrine glands do not respond to thermal stimuli but react promptly to mental stimulation, producing a more concentrated milky sweat, which has characteristic odor of its own. Eccrine sweat is free from bacteria when freshly secreted and becomes contaminated on reaching the skin surface, whereas apocrine sweat is mixed with the rich flora of the sebaceous ducts and hair follicles immediately on secretion.
Sweat from both types of glands, combined with sebum and epithelical debris on the skin surface provides ideal conditions for bacterial growth, which is left unchecked, fairly rapidly produces odor.
Odor controlling agents:
In order to control the objectionable odors of perspiration, it is necessary either to check the flow of excess perspiration or to eliminate its odor, or both. Among the odor controlling agents, the main types are-
o Antiperspirants and
o Deodorants.
Antiperspirants:
A variety of substances which have astringent action to inhibit the flow of perspiration is called antiperspirants. Astringent action make body tissue contract and stop bleeding.
Antiperspirant products are marketed as creams, lotions, sticks, powders and spray form. The FDA product and ingredient review panel for over-the-counter antiperspirants (OTC panel) has assigned three classifications to antiperspirants: category 1, safe to use; category 2, does not meet requirements, remove offending materials; category 3, may be marketed while testing continues.
Mechanism of Antiperspirants-
Antiperspirants narrowing the openings of the sweat ducts and form a keratonic plug in the sweat duct orifice to obstruct the flow of sweat.
Raw materials-
Salts of metals such as aluminium, iron, chromium, lead, mercury, zinc and zirconium have astringent properties which may be demonstrated by protein precipitation. But some of these produce discoloration and have toxic effect and are not suitable for cosmetic preparation.
Salts of aluminium and zinc are most commonly used. The astringency of these salts is also dependent on the anion. Sulfate, chloride, chlorhydroxide and phenolsulfonate have been most widely used, although basic formate, lactate, sulfamate and the alums are also found in antiperspirant products.
The aluminium compound has been most widely used in antiperspirant preparation. Among them aluminium chlorhydroxide complex commonly referred as aluminium chlorhydrate or aluminium chlorhydroxide is widely used. Because it is not irritating or sensitizing to normal skin and cause little or no damage to fabrics. Other compounds that have been used are: basic aluminium bromide, iodide, and nitrate, and basic aluminium hydroxychloride-zirconyl hydroxyl oxychloride, with and without glycine.
Most of the salts which show good astringent properties have a low pH (2.5-4.2) and causes skin irritation & corrosiveness to fabrics. The pH of such a product may be satisfactorily modified to reduce skin irritation by addition of small amounts of zinc oxide, magnesium oxide, aluminium hydroxide, or triethanolamine.
Deodorants:
Since many people who do not perspire excessively are concerned with body odor, a wide variety of products which are deodorant and not antiperspirant have been successively marketed. Since most body odor is the result of bacterial action on perspiration, a satisfactory deodorant product must contain an effective antibacterial agent.
Many aluminium salts have both astringent and antiseptic properties. So, product containing astringent aluminium salts act as both antiperspirant and deodorant. Compounds of metals other than aluminium have been used in deodorant products. Zinc oxide, zinc peroxide and zinc stearate are mildly astringent and antiseptic and can be used in deodorant powders. Zinc phenosulphonate is also antiseptic and mildly astringent and is useful ingredient of liquid deodorant.
The bisphenols, particularly hexachlorophene, have been most widely used in deodorant products. The retention of such products on the skin makes them peculiarly effective with repeated use. Other phenolic antibacterials which have been found effective in body deodorants are para-chloro-meta-xylenol (PCMX) and dichloro-meta-xylenol (DCMX). The phenolic odor of these products is objectionable in many products.
