COSMETICS AND BATHROOM PRODUCTS:HAIR REMOVA L PRODUCTS (DEPILA TORIES).

HAIR REMOVA L PRODUCTS (DEPILA TORIES)

A chemical depilatory is a preparation in the form of a liquid or cream that is used to remove unwanted hair from the surface of the body.

Depilatory literally means “to deprive of hair” (Latin pilus, hair). As far back as 4000 to 3000 BC, women were known to use a depilatory containing orpiment (natural arsenic trisulfide), quicklime (used to make cement), and starch made into a paste. Around 500 BC, women made depilatory creams from medicinal drugs, such as bryonia. In the middle of the first century AD, Romans used depilatories with ingredients such as resin, pitch, white vine or ivy gum extract, ass’s fat, she-goat’s gall, bat’s blood, and powdered viper. During Elizabethan times, walnut oil, quicklime, or mixtures of vinegar and cat’s dung were applied to remove hair. In the early eighteenth century, American women applied poultices of caustic lye to burn hair away, and by the middle of the nineteenth century, powdered depilatories were marketed throughout the United States. In 1940, a New York-based company developed America’s most successful depilatory lotion as a result of wartime shortages of razor blade materials. The product included the active ingredient calcium thioglycolate, which destroys protein hair structure and reduces hair texture and strength.

Modern chemical depilatories are highly alkaline pastes, gels, aerosols, roll-on forms, creams, or lotions. The pH of these depilatories is usually between 10 and 12.5. They contain alkali or alkali-earth sulfides (usually up to 35 percent sodium, barium, or strontium sulfide) or mixtures of alkali- earth hydroxides (usually 5 to 10 percent potassium or calcium hydroxide), along with salts of aliphatic mercapto acids (usually 2 to 5 percent sodium or calcium thioglycolate, or thioglycolic acid). Combined, these overall alkaline active ingredients destroy some of the peptide bonds within the fibers of keratin protein that constitute each shaft of hair. When used in a product, the concentration of calcium thioglycolate [Ca(CH2SHCOO)2]

is generally maintained to yield desired results within a reasonable time

frame (five to fifteen minutes) depending on hair coarseness, while avoiding the potential to injure the skin. The alkaline pH can possibly damage and degrade dermal proteins, causing skin irritation, excess exfoliation, or allergic contact dermatitis. Fortunately, this dermal effect is usually temporary, lasting only hours or a few days. It is also recommended that consumers read product labels and select the formulation appropriate for the intended use, as skin sensitivity varies throughout potential applica- tion body areas (e.g., legs, bikini line, underarms, face). Acting like a chemical razor blade, chemical depilatories cause degradation of the hair keratin and deterioration of hair fibers to a gelatin-like mass. Because the protein structure of the hair is destroyed, the hair will easily separate from the skin surface and be manually removed by wiping or scraping. This hair removal process works best on soft, fine hair rather than coarse hair, and although the results vary with the individual, a few days to two weeks is the usual duration of the hair-free period.

Other chemical ingredients often included in commercial chemical depilatories are water, moisturizers and emollients (e.g., mineral oil, almond oil, sunflower seed oil, jojoba oil, lanolin, glycerin, propylene glycol, polysorbate 20), emulsifiers (e.g., cetearyl alcohol, ceteth-20, ceteareth-20, PPG-15 stearyl ether, sodium lauryl sulfate), antioxidant vitamins (e.g., tocopheryl acetate [vitamin E acetate], ascorbic acid [vitamin C]), binders and thickeners (e.g., silica, magnesium silicate, xanthan gum, copolymer, acrylates), fragrance, skin-soothing herbal extracts (e.g., Aloe vera, Ca- mellia oleifera, Anthemis nobilis flower, panax ginseng root), color pig- ments (e.g., titanium dioxide, iron oxide, chromium hydroxide green), antiseptic oils (e.g., bisabolol), chelating agents (e.g., sodium gluconate), and preservatives (e.g., urea).