We use chemicals to mask or prevent unpleasant body odors and sweat. There are two kinds of sweat- eccrine and apocrine. Eccrine sweat, produced in eccrine sweat glands (see Figure 4.3) on almost all parts of the skin, is the cooling mechanism of your body. ANTIPERSPIRANTS AND DEODORANTS

Figure 4.3 Cross section of skin.

Whenever exercise or environment threatens to raise your temperature, eccrine sweat is exuded onto skin to evaporate. Evaporation, being endothermic, takes away excess heat energy so that your body temperature remains fairly constant. Besides water, eccrine sweat contains some organic compounds and salts but does not produce offensive odors.

Apocrine sweat, however, is a different story. Apocrine glands terminate in hair follicles (see Figure 4.3) at only a few places on your body- your underarms being one of those locations..

Your nervous system activates these glands, which secrete liquid in proportion to the stress you feel. Although mostly water, about I percent of apocrine sweat consists of fat, cellular fragments, and bacteria. When exposed to the air, bacteria begin to flourish, producing smelly 'compounds and hence body odor

There are five ways products can combat this body odor: 1. Inhibit the production of apocrine sweat 2. Prevent the sweat produced from reaching the open air on the skin 3. Kill offending bacteria in the exposed sweat 4. Decompose foul-smelling substances the bacteria create 5. Mask odors with more pleasant fragrances.

Clearly, the most effective actions are at the top of the list. The federal government requires that manufacturers reveal the general action of their product. If it works by Methods 1 or 2 above, then it can be called an antiperspirant. If it works by any of the others, it must be called a deodorant. Some products with combinations of ingredients can claim to be both.

The active ingredient in most antiperspirants is one of the aluminum chlorohydrates, A1 2 (OH) 5 Cl or A1 2 (OH) 4 Cl 2, or a zirconium-aluminum salt. These are water-soluble ionic compounds that produce A1 3+ ions in solution. Aluminum ions bind to the ducts of sweat glands, shrinking the openings and forming an aluminum-keratin complex that plugs up many ducts.

The flow of perspiration is reduced or, for some glands, prevented altogether. In addition, aluminum chlorohydrates kill bacteria in the apocrine sweat that does reach the skin. This pore-clogging action cannot be used by everyone. Because sebum glands open up in the same places the apocrine glands do, both can get obstructed. For certain susceptible people, rashes (sort of an underarm acne) can develop.

Deodorants, which have ingredients to kill bacteria and absorb, decompose (by oxidation), or mask odors, are alternatives for people who are unable to use antiperspirants. Besides providing a pleasing aroma, they include ingredients such as alcohols (which kill bacteria by dehydrating them) and various phenols (which kill bacteria by denaturing their proteins).

Antiprespirant /deodorant cream Stearic acid 14.0 Bees wax 2.0 Liquid paraffin 1.0 Tween Al-chlorhydrate 12.0 Cetrimide 1.0 Water to 100

Deodorant Stick Stearic acid 3.4 Sodium hydroxide 0.6 D.water 1.0 Glycerol 7.5 Cetrimide 0.75 Ethanol 75

Deodorant Stick Stearic acid 7.5 Sodium carbonate 2.5 Glycerol 89 Cetrimide 1

. Deodorant acceptable claims Absorbent that helps keep you dry Anti ‐ odourant Controls odour Deodorant Fights bad odour Kills odour ‐ causing bacter

Deodorant unacceptable claims Antiperspirant (for products that do not affect perspiration) Controls perspiration Controls sweat

Antiperspirant acceptable claims 24 hour antiperspirant effect (products that demonstrate 20% sweat reduction within a 24 ‐ hour period) Antiperspirant Body responsive Clinical (qualified as clinical testing) Clinical protection (must be qualified with “clinically proven extra effective wetness protection”, and must demonstrate 30% or more sweat

Antiperspirant acceptable claims reduction within a period of 24 hours) Clinically tested/proven/trials Extra effective (products that demonstrate 30% or more sweat reduction within a 24 ‐ hour period) Helps keep you dry Protects against wetness Reduces (or provides protection against) underarm perspiration

Antiperspirant unacceptable claims Clinical (unqualified) Clinical protection (unqualified) Clinical strength/effect/action Helps check, halt or stop underarm wetness, dampness or perspiration Hyperhidrosis Persistent protection (i.e., usually significantly greater than 24 hours, based on a mechanism of action that modifies organic function)