talc. Naturally occurring silicate mineral (any group of substances containing negative ions composed of silicon and oxygen) of magnesium. Current, extensive research indicates there is no increased risk of lung cancer when using talc-based products or for those involved in the manufacture of talc products (Source: Occupational and Environmental Medicine, January 2006, pages 4–9), although there is epidemiological evidence that frequent use of pure talc over the female genital area may increase the risk of ovarian cancer (Sources: International Journal of Cancer, November 2004, pages 458–464; and Anticancer Research, March-April 2003, pages 1955–1960). However, a study review in Regulatory Toxicology and Pharmacology (August 2002, pages 40–50) stated that “Talc is not genotoxic, [it] is not carcinogenic when injected into ovaries of rats.… There is no credible evidence of a cancer risk from inhalation of cosmetic talc by humans.”

tallow. Substance extracted from the fatty deposits of animals, especially from suet (the fat of cattle and sheep). Tallow is often used to make soap and candles. In soap, because of its fat content, it can be a problem for breakouts.

tamanu oil. From a tree native to Polynesia. It is reputed to have wondrous wound-healing properties, as well as being a cure-all for almost every skin ailment you can think of, from acne to eczema to psoriasis, but all of the miraculous claims are hinged on anecdotal, not scientific, evidence. There’s no harm in using this oil in skin care—like most oils, it is composed of phospholipids and glycolipids, and these are natural constituents of healthy skin and are good water-binding agents. Tamanu oil may have anti-inflammatory properties and there is some research showing it has anti-tumor properties, though this has not been proven in any direct research on skin.

Tanacetum parthenium. See feverfew extract.

tangerine oil. Fragrant, volatile citrus oil that can be a skin irritant.

tannic acid. Potent antioxidant; it may have some anticarcinogenic properties (Sources: Bioorganic & Medicinal Chemistry Letters, June 2002, pages 1567–1570; and Nutrition and Cancer, 1998, volume 32, number 2, pages 81–85).

tannin. Component of many plants. It can have an anti-tumor benefit when consumed in tea or foods (Source: Nutrition and Cancer, 1998, volume 32, number 2, pages 81–85). There is some research on animals showing that this benefit may translate to skin (Source: Photochemistry and Photobiology, June 1998, pages 663–668). Tannins can also have constricting properties on skin, and may cause irritation with repeated use.

Taraktogenos kurzii. See chaulmoogra oil.

Taraxacum officinale. See dandelion extract.

tartaric acid. See AHA.

Tazorac. Chemically known as tazarotene, it is a synthetically derived retinoid with properties similar to those of tretinoin (active ingredient in Retin-A and Renova). Tazorac is a brand-name prescription drug, owned by Allergan, that is available in gel and cream textures and is prescribed for managing acne. Tazarotene is also sold under the brand name Avage (also from Allergan), and this version is marketed for treating wrinkles and sun-induced skin discolorations. Tazarotene works similarly to tretinoin by modulating cell differentiation and proliferation. It also has anti-inflammatory and immune-modifying properties, which is why it is used (often successfully) as a topical prescription for managing psoriasis (Sources: http://www.emedicine.com; and American Journal of Clinical Dermatology, June 2005, pages 255–272).

TEA. See triethanolamine.

tea tree oil. Also known as melaleuca, from the name of its plant source, Melaleuca alternifolia. It can have disinfecting properties that have been shown to be effective against the bacteria that cause blemishes. According to Healthnotes Review of Complementary and Integrative Medicine (http://www.healthwell.com/healthnotes/Herb/Tea_Tree.cfm) and the Medical Journal of Australia (October 1990, pages 455–458), 5% tea tree oil and 2.5% benzoyl peroxide are effective in reducing the number of blemishes, with a significantly better result for benzoyl peroxide when compared to the tea tree oil. Skin oiliness was lessened significantly in the benzoyl peroxide group versus the tea tree oil group. However, the tea tree oil had somewhat less irritating side effects. Concentrations of 5% to 10% are recommended. However, the amount present in most skin-care products is usually less than 1% and, therefore, considered not effective for disinfecting. See Paula’s article “Tea Tree Oil—Melaleuca,” at http://www.cosmeticscop.com.

TEA-lauryl sulfate. While there is abundant research showing sodium lauryl sulfate is a sensitizing cleansing agent, there is no similar supporting research for TEA-lauryl sulfate. However, because the relationship between the two is so close, I decided to recommend against using either of them. The basis for this is a judgment call, made from a desire to protect skin from sensitization; however, there are no specific studies I can cite for this recommendation, although there are those who will understandably disagree with my conclusion. See sodium lauryl sulfate.

terephthalylidine dicamphor sulfonic acid. See Mexoryl SX.

Terminalia catappa. Can be a potent antioxidant (Source: Anticancer Research, January-February 2001, pages 237–243).

Terminalia sericea. Herb that is effective against some forms of gram-positive and gram-negative bacteria when used in pure form, but is not effective against acne-causing bacteria. It also has anti-inflammatory and antifungal properties (Sources: Journal of Ethnopharmacology, January 2006, pages 135–138, and June 2005, pages 301–308).

Terminalia sericea extract. Extract that has anti-inflammatory and antibacterial properties, but there is no research showing it has any effect on the appearance of cellulite (Sources: Journal of Ethnopharmacology, February 2005, pages 43–47; and European Journal of Pharmaceutics and Biopharmaceutics, March 2003, Pages 191–198).

tetradibutyl pentaeriththrityl hydroxyhydrocinnamate. See antioxidant.

tetrahexyldecyl ascorbate. Stable form of vitamin C. See vitamin C.

tetrahydrobisdemethoxycurcumin. Antioxidant and anti-inflammatory plant extract. See curcumin.

tetrahydrodemethoxycurcumin. See curcumin and turmeric.

tetrahydrodiferuloylmethane. Antioxidant and anti-inflammatory plant extract. See curcumin.

tetrahydromethoxycurcumin. Antioxidant and anti-inflammatory plant extract. See curcumin.

tetrahydroxypropyl ethylenediamine. See chelating agent.

tetrasodium EDTA. Chelating agent used to prevent minerals present in formulations from bonding to other ingredients.

tetrasodium etidronate. Used as a chelating agent in cosmetics to prevent varying mineral components from binding together and negatively affecting the formulation.

thiamine HCL. Vitamin B1. There is no research showing this to be effective when applied topically on skin.

thickening agent. Substances that can have a soft to hard waxlike texture or a creamy, emollient feel, and that can be great lubricants. There are literally thousands of ingredients in this category that give each and every lotion, cream, lipstick, foundation, and mascara, as well as other cosmetic products, their distinctive feel and form.

thiodipropionic acid. Acid-based synthetic antioxidant. There is no research pertaining to its benefit for skin, but in theory, and when stably packaged, it should exert an antioxidant effect when applied topically.

thioglycolate. Compound used in permanent waves and depilatories either to alter the structure of hair or to dissolve it. These are potent skin irritants.

thiotaurine. Amino acid. Potentially, it can have antioxidant properties for skin (Source: Shiseido Corporation, http://www.shiseido.co.jp/e/e9608let/html/let00027.htm). See amino acid.

threonine. See amino acid.

thyme extract. Extract derived from the thyme plant. It can have potent antioxidant properties (Source: Journal of Agricultural Food Chemistry, March 2002, pages 1845–1851). Its fragrant component can also cause skin irritation.

thyme oil. See thyme extract.

thymus hydrolysate. Form of animal thymus derived by acid, enzyme, or other methods of hydrolysis. It can have water-binding properties for skin, but has no other special or unique benefit.

Thymus serpillum extract. Extract of wild thyme. See thyme extract.

Thymus vulgaris. See thyme extract.

Tilia cordata. See linden flower extract.

Tinosorb M. See Tinosorb S.

Tinosorb S. In Europe there are two sunscreen ingredients—Tinosorb S (bis-ethylhexyloxyphenol methoxyphenyl triazine) and Tinosorb M (methylene bis-benzotriazolyl tetramethylbutylphenol)—that are approved for sun protection across the entire range of UVA radiation (Sources: Photochemistry and Photobiology, September 2001, pages 401–406; and Ciba Specialty Chemicals Corporation, North America, http://www.cibasc.com). Whether they are preferred over the other UVA-protecting ingredients used in sunscreens has not been established. At this time, neither Tinosorb M nor Tinosorb S has been approved for use in the United States or Canada. See UVA.

tissue respiratory factor (TRF). Trade name for a form of yeast suspended in alcohol. There is only one independent study, performed on animals, that showed it to have some wound-healing benefits (Source: Journal of Burn Care Rehabilitation, March–April 1999, pages 155–162).

titanium dioxide. Inert earth mineral used as a thickening, whitening, lubricating, and sunscreen ingredient in cosmetics. It protects skin from UVA and UVB radiation and is considered to have no risk of skin irritation (Sources: http://www.photodermatology.com/sunprotection.htm; and Skin Therapy Letter, 1997, volume 2, number 5). See UVA.

Tocopherol. See vitamin E.

tocopherol acetate. See vitamin E.

tocopheryl acetate. See vitamin E.

tocopheryl lineolate. See vitamin E.

tocotrienols. Superpotent forms of vitamin E that are considered stable and powerful antioxidants. There is some research showing that tocotrienols are more potent than other forms of vitamin E for antioxidant activity (Source: Journal of Nutrition, February 2001, pages 369S–373S), but the studies cited in this review were all performed on animal models or in vitro. According to the University of California at Berkeley’s Wellness Guide to Dietary Supplements (October 1999), “[Tocotrienol] research in humans is very limited, and the results conflicting.” The research that has been done has centered on large doses of oral tocotrienols, animal studies, or test-tube trials. Companies that want you to believe that tocotrienols are now the answer for your skin are only guessing whether or not the laboratory evidence translates to human skin as it exists in the real world (Source: Healthnotes Review of Complementary and Integrative Medicine, http://www.healthnotes.com). Full-scale clinical studies on humans to assess the benefits of topical tocotrienols have not yet been performed, so for now (as is true for all antioxidants), choosing it as the “best” one is a leap of faith. See vitamin E.

tomato extract. Extract that has weak antioxidant properties (Source: Free Radical Research, February 2002, pages 217–233). Tomatoes contain lycopene, which is a significant antioxidant, but it is more bioavailable from tomato paste than from fresh tomatoes (Source: American Journal of Clinical Nutrition, 1997, volume 66, number 1, pages 116–122). It can also be a potential skin irritant depending on what part of the tomato is used, but there is no way to know that from an ingredient label. See lycopene.

tormentil extract. Plant that can be irritating due to its tannin content, which causes skin constriction.

tourmaline. Inert, though complex, mineral. One of its unique properties is that it is piezoelectric, meaning that it generates an electrical charge when under pressure, which is why it’s typically used in pressure gauges. Tourmaline is also pyroelectric, which means that it generates an electrical charge during a temperature change (either increase or decrease). One of the results of generating such an electric charge is that dust particles will become attached to one end of a tourmaline crystal. However, none of that can take place in a cosmetic. There is no published research showing tourmaline has any proven effect on skin whatsoever. See Paula’s article “Tourmaline,” at http://www.cosmeticscop.com.

tragacanth. Natural gum used as a thickener in cosmetics.

transforming growth factor (TGF). Stimulates wound healing and collagen growth. See human growth factor.

trehalose. Plant sugar that has water-binding properties for skin.

tretinoin. Topical, prescription-only medication that can improve skin cell production after skin has been damaged. It is the active ingredient in Retin-A, Renova, Tazorac, and Avita. One of the more significant problems of sun damage is abnormal and mutated cell growth. An article in Clinics in Geriatric Medicine (November 2001, pages 643–659) stated that “Studies that have elucidated photoaging pathophysiology have produced significant evidence that topical tretinoin (all-trans retinoic acid), the only agent approved so far for the treatment of photoaging, also works to prevent it” (Sources: Cosmetic Dermatology, December 2001, page 38; and Journal of Investigative Dermatology, 2001, volume 111, pages 778–784). Tretinoin affects and improves actual cell production deep in the dermis, far away from the surface of skin (Sources: Clinical and Experimental Dermatology, October 2001, pages 613–618; Clinics in Geriatric Medicine, November 2001, pages 643–659; and Photochemistry and Photobiology, February 1999, pages 154–157).

tribehenin. Also known as glyceryl tribehenate, a skin-conditioning agent that is a mixture of glycerin and behenic acid. See glycerin and fatty acid.

tricaprylin. Mixture of glycerin and caprylic acid. Has emollient properties and is used as a skin-conditioning agent. See glycerin.

triclosan. Good antibacterial agent used in many products, from those for oral hygiene to cleansers (Sources: Federation of European Microbiological Societies Microbiology Letter, August 2001, pages 1–7; and American Journal of Infection Control, April 2000, pages 184–196). However, whether triclosan is effective for treatment of acne has not been researched. There is also controversy over whether or not triclosan may contribute to creating strains of bacteria that are resistant to antibiotics due to its overuse in cosmetic products. There also is concern about whether, in practical use, it can in fact impart the benefits of disinfection indicated on the label (Source: Journal of Hospital Infection, August 2001, Supplement A, pages S4–S8).

tridecyl salicylate. Salt form of salicylic acid (BHA). When it is no longer an acid (as in this case), salicylic acid no longer has exfoliating properties.

tridecyl stearate. Used in cosmetics as a thickening agent and emollient.

tridecyl trimellitate. Used as a skin-conditioning agent and thickening agent. See thickening agent.

triethanolamine. Used in cosmetics as a pH balancer. Like all amines, it has the potential for creating nitrosamines. There is controversy as to whether this poses a real problem for skin, given the low concentrations used in cosmetics and the theory that nitrosamines cannot penetrate skin.

triethoxycaprylylsilane. Silicone that functions as a binding agent and emulsifier. See silicone.

Trifolium pratense. See red clover.

triglyceride. Used as an emollient and thickening agent in cosmetics. See glyceryl ester and natural moisturizing factor (NMF).

trihydroxystearin. Mixture of glycerin and fatty acids used as an emollient and thickening agent. See fatty acid.

trilaurin. Group of ingredients that are triesters of glycerin and aliphatic acids, and known generically as glyceryl triesters. These are used in cosmetic products as thickening agents and emollients (Source: International Journal of Toxicology, 2001, volume 20, Supplement 4, pages 61–94).

trimethylsiloxysilicate. Used as a skin-conditioning and occlusive agent. See silicone.

trioclanolin. Derived from lanolin and used as a texture enhancer, most commonly in powder-based products such as eyeshadows and powder blush.

trioctanoin. Used as an emollient and thickening agent in cosmetics. See trilaurin.

trioctyldodecyl citrate. Mixture of octyldodecanol and citric acid used as a skin-conditioning agent and emollient. See octyldodecanol and citric acid.

trisodium EDTA. Similar to tetrasodium EDTA. Used as a water-softening and chelating agent (a compound that binds and separates metals, keeping them from bonding to other ingredients). See tetrasodium EDTA.

Triticum vulgare oil. See wheat germ oil.

tryptophan. See amino acid.

turmeric. Spice made from the dried, ground root of a plant; its extract is called curcumin. A natural yellow food coloring that has potent antioxidant properties (Sources: Food Chemistry and Toxicology, August 2002, pages 1091–1097; and Planta Medica, December 2001, pages 876–877). Because it is a potent spice, it also may have irritating properties for skin.

Tussilago farfara. See coltsfoot.

tyrosinase. Enzyme that stimulates melanin production. See tyrosine.

tyrosine. Amino acid in skin that initiates the production of melanin (melanin is the component of skin that gives it “color”). According to information on the FDA’s Web site (http://www.fda.gov), tyrosine’s “use is based on the assumption that it penetrates the skin, increases the tyrosine content of the melanocytes, and thus enhances melanin formation. This effect has not been documented in the scientific literature. In fact, an animal study reported a few years ago demonstrated that ingestion or topical application of tyrosine has no effect on melanogenesis [the creation of melanin].” Tyrosine is important to the structure of almost all proteins in the body. However, the chemical pathway needed for tyrosine to function is complex, and this pathway cannot be duplicated by including tyrosine in a skin-care product or by applying it topically.