D&C. According to the FDA, D&C is an identification that indicates a coloring agent has been approved as safe in drug and cosmetics products, but it does not apply to food.

daisy flower extract. There is no research showing this extract has any benefit for skin. Also known as tansy, it can cause severe contact dermatitis and is considered unsafe for topical application (Source: http://www.naturaldatabase.com).

dandelion extract. Can be a potent allergen (Source: Archives of Dermatology, January 1999, pages 67–70).

Daucus carota. Also known as wild carrot. It can have antioxidant properties, but applied topically it can cause dermatitis (Source: http://www.naturaldatabase.com).

DEA. See diethanolamine.

DEA oleth-10 phosphate. Used as an emulsifying agent, which is a group of ingredients essential to most cosmetic formulations because they can keep unlike ingredients mixed together smoothly (a prime example is oil and water).

Dead Sea minerals. Several studies demonstrate that Dead Sea minerals can have a positive effect on psoriatic skin (Sources: Israel Journal of Medical Sciences, November 2001, pages 828–832; British Journal of Dermatology, June 2001, pages 1154–1160; International Journal of Dermatology, February 2001, pages 158–159; and Journal of the American Academy of Dermatology, August 2000, pages 325–326). Psoriasis is a skin condition characterized by rapidly dividing, overactive skin cells. No one is quite sure how the Dead Sea minerals and salts affect psoriasis. One of the more popular theories regarding their benefit is that the mineral content of the water slows down the out-of-control cell division. Some research indicates that the benefit is cumulative and that the results can last for up to five months. However, there is no research showing that these minerals have any effect on wrinkles, dry skin, or acne.

decyl glucoside. Used as a gentle detergent cleansing agent. See surfactant.

dehydroepiandrosterone. See DHEA.

deionized/demineralized water. Filtered water used in cosmetics. All water used in cosmetic formulations goes through this process to remove components that could interfere with a product’s stability and performance.

denatured alcohol. See alcohol.

deoxyribonucleic acid. See DNA.

detergent cleansing agent. See surfactant.

deuterium oxide. See heavy water.

dextran. Polysaccharide that has water-binding properties for skin. See also mucopolysaccharide.

dextrin. Carbohydrate that is classified as a polysaccharide. It is used as an adhesive when mixed with water. For skin it can have water-binding properties.

DHA. See dihydroxyacetone.

DHEA. Also called prasterone and dehydroepiandrosterone, DHEA is a naturally occurring prohormone that is converted in the body primarily to androgens (male hormones), and to a lesser degree to estrogens. It is controversial as an oral supplement because long-term use has been associated with women developing secondary masculine traits, liver damage, disrupted menstrual cycles, and defects in fetuses. More superficial risks include hair loss, acne, and weight gain. Topically, it is possible that DHEA can increase collagen production and prevent collagen destruction by decreasing matrix metalloproteinases (MMP), but the research about this is extremely limited and the studies that do exist were performed only on a handful of people (Sources: Drug Delivery, September–October 2005, pages 275–280; Journal of Endocrinology, November 2005, pages 169–196; Journal of Investigative Dermatology, November 2005, pages 1053–1062, and February 2004, pages 315–323; Gynecological Endocrinology, December 2002, pages 431–441; http://www.fda.gov; and http://www.mayoclinic.com/health/dhea/NS_patient-dhea).

diatomaceous earth. Light-colored porous rock composed of the skeletons of minute sea creatures called diatoms. Typically used as an abrasive material in scrub products.

diazolidinyl urea. Formaldehyde-releasing preservative (Source: Contact Dermatitis, December 2000, pages 339–343). See formaldehyde-releasing preservative.

dibutyl phthalate. Very common ingredient in almost every nail polish and synthetic fragrance sold today. It is used as a plasticizer and is a key component in giving nail polish its unique properties. The Centers for Disease Control and Prevention (CDC, http://www.cdc.gov) published the National Report on Human Exposure to Environmental Chemicals—Results for Mono-butyl phthalate [which is] (metabolized from Dibutyl phthalate). The report noted that measurable levels of phthalate were found in the urine of the participants in the study. However, the CDC also stated that “Finding a measurable amount of one or more phthalate metabolites in urine does not mean that the level of one or more phthalates causes an adverse health effect. Whether phthalates at the levels of metabolites reported here are a cause for health concern is not yet known; more research is needed” (Sources: Centers for Disease Control and Prevention, www.cdc.gov/nceh/dls/report/results/Mono-butylPhthalate.htm; and Environmental Health Perspectives, December 2000, volume 108, issue 12). In animal tests, dibutyl phthalate has been shown to produce detrimental effects. The Environmental Working Group (EWG, http://www.ewg.org), an environmental research organization, found that “DBP is a developmental and reproductive toxin that in lab animals causes a broad range of birth defects and lifelong reproductive impairment in males [when] exposed in utero and shortly after birth. DBP damages the testes, prostate gland, epididymis, penis, and seminal vesicles. These effects persist throughout the animal’s life.” At this time, there is no conclusive or agreed-upon research pointing to phthalates being a problem for humans.

diethanolamine. Colorless liquid used as a solvent and pH adjuster. Also used as a lather agent in skin- and hair-care products when coupled with a foaming or detergent cleansing agent. In 1999 the National Toxicology Program (NTP) completed a study that found an association between cancer and tumors in laboratory animals and the application of diethanolamine (DEA) and certain DEA-related ingredients to their skin (Sources: Study #TR-478, Toxicology and Carcinogenesis Studies of Diethanolamine, CAS No. 111-42-2, July 1999—http://ntp-server.niehs.nih.gov/; and Food Chemistry and Toxicology, January 2004, pages 127–134). For the DEA-related ingredients, the NTP study suggested that the carcinogenic response is linked to possible residual levels of DEA. However, the NTP study did not establish a link between DEA and the risk of cancer in humans. According to the FDA (Source: Office of Cosmetics and Colors Fact Sheet, December 9, 1999), “Although DEA itself is used in very few cosmetics, DEA-related ingredients (e.g., oleamide DEA, lauramide DEA, cocamide DEA) are widely used in a variety of cosmetic products. These ingredients function as emulsifiers or foaming agents and are generally used at levels of 1% to 5%. The FDA takes these NTP findings very seriously and is in the process of carefully evaluating the studies and test data to determine the real risk, if any, to consumers. The Agency believes that at the present time there is no reason for consumers to be alarmed based on the usage of these ingredients in cosmetics. Consumers wishing to avoid cosmetics containing DEA or its conjugates may do so by reviewing the ingredient statement required to appear on the outer container label of cosmetics offered for retail sale to consumers.” A study from 1999 on the potential effects of DEA involved applying a pure concentration of this ingredient directly to mouse skin for a period of 14 weeks (minimum) and 2 years (maximum). The study reported no evidence of carcinogenicity when low doses (50–100 mg per kilogram of body weight) were used. Internal changes to organs (liver, kidneys) and external signs (inflammation, ulcers) were found as the dosages of DEA increased (up to 800 mg was used) (Source: National Toxicology Program Technical Report Service, volume 478, July 1999, pages 134–212). Although the results of this study are interesting, it is still unrelated to how DEA is used in cosmetics products and how consumers use them. In most instances, our contact with DEA in any form is brief, and most likely is not cause for alarm.

diethylhexyl malate. Emollient and skin-conditioning agent derived from the solvent ethyl hexanediol.

dihydroxyacetone. Ingredient present in all self-tanners that affects the color of skin. Derived from sugar, it reacts with amino acids found in the top layers of skin to create a shade of brown; the effect takes place within two to six hours and it can build color depth with every reapplication. It has a long history of safe use.

diisopropyl adipate. Used as a film-forming agent, emollient, and skin-conditioning agent.

diisostearoyl trimethylolpropane siloxy silicate. Skin-conditioning agent in the silicone family. See silicone.

dimethicone. See silicone.

dimethicone copolyol. See silicone.

dimethicone crosspolymer. Silicone derivative used as a stabilizing or suspending agent or as a thickener. See silicone.

dimethiconol. See silicone.

dimethyl capramide. Functions as a stabilizer and solvent in cosmetics.

dimethyl ether. Colorless gas used as a propellant in aerosol products. It is toxic if inhaled and can be irritating to skin (Source: Handbook of Cosmetic and Personal Care Additives, Second Edition, volume 2, 2002, Synapse Information Resources, Inc.).

dimethyl MEA. See dimethylaminoethanol (DMAE).

dimethylaminoethanol (DMAE). What little research there is about DMAE relates to its effect as an oral supplement, and the findings are mixed. DMAE, known chemically as 2-dimethyl-amino-ethanol, has been available in Europe under the product name Deanol for over 30 years. As an oral supplement it is popularly known for improving mental alertness, much like Ginkgo biloba and coenzyme Q10. However, the research about DMAE does not show the same positive results found with the other two supplements. Because DMAE is chemically similar to choline, it is thought to stimulate production of acetylcholine, and because acetylcholine is a brain neurotransmitter, it’s easy to see how it could be associated with brain function. However, only a handful of studies have looked at DMAE for that purpose and they have not been conclusive in the least, while some have shown that DMAE may be problematic or not very effective (Sources: Mechanisms of Aging and Development, February 1988, pages 129–138; Neuropharmacology, June 1989, pages, 557–561; and European Neurology, 1991, pages 423–425). Despite the lack of evidence supporting any claim that DMAE has any effect on skin, there are hundreds of Web sites claiming that it does. It is possible that DMAE can help protect the cell membrane, and keeping cells intact can have benefit, but so far that appears to be only conjecture, not fact.

A study published in The British Journal of Dermatology (May 2007) has shown contrary evidence that it may actually pose risks for the skin. In vitro tests of the pure substance, as well as tests of creams that contain DMAE, demonstrated a fairly fast and significant increase in protective elements around the skin cell. However, a short time later the researchers observed a significant decrease in cell growth and in some cases they found that it had halted cell growth altogether.

Dioscorea villosa extract. See wild yam extract.

dipentaerythrityl hexacaprylate/hexacaprate. Mixture of fatty acids used as an emollient and thickening agent.

dipotassium glycyrrhizinate. See anti-irritant and licorice extract.

di-PPG-3 myristyl ether adipate. Derivative of myristyl alcohol (a fatty alcohol) and adipic acid (a buffering and neutralizing ingredient). It is used as a skin-conditioning agent and solvent in cosmetics.

disodium cocoamphodiacetate. Mild detergent cleansing agent. See surfactant.

disodium diglyceryl phosphate. Used as an emollient and thickening agent in cosmetics. See glyceryl ester.

disodium EDTA. See EDTA.

disodium glyceryl phosphate. Used as an emollient and thickening agent in cosmetics. See glyceryl ester.

disodium lauraminopropionate. A mild surfactant. See surfactant.

disodium rutinyl disulfate. No research shows this antioxidant has any impact on cellulite.

disteardimonium hectorite. Used as a suspending agent, often with pigments.

DMAE. See dimethylaminoethanol (DMAE).

DMDM hydantoin. Formaldehyde-releasing preservative (Source: Household and Personal Products Industry, May 2001, “Preserving Personal Care and Household Products”). See formaldehyde-releasing preservative.

DNA. Abbreviation for deoxyribonucleic acid. DNA is found in all cells. It is the primary component of genes—and genes are the means by which cells transmit hereditary characteristics. DNA is the basis for all genetic structure; its components include adenine (A), guanine (G), thymine (T), and cytosine (C). It is the mapping of these substances that makes up the genetic code of all human traits and cellular functions. DNA is also the genetic material that is required for all cellular division and growth. Including DNA in a skin-care product is pointless because it cannot in and of itself affect a cell’s genetic elements. The formation of DNA is a complex process within the cell that requires a multitude of proteins and enzymes for it to have an effect on the body’s genetic material. It is also doubtful that you would want to ever put anything on your skin that could affect genetic material, particularly via a cosmetic for which there are no safety or efficacy regulations. Beyond that, any successful attempt to affect what DNA does would potentially create a significant risk of cancer.

docosahexaenoic acid. See fatty acid.

dog rose. See rose hip.

dogwood. There is a small amount of research showing that dogwood has antioxidant and anti-inflammatory properties (Source: Journal of Agricultural Food Chemistry, April 2002, pages 2519–2523).

dong quai. Latin name Angelica polymorpha sinensis, is an herb that has been shown in some studies to have estrogenic activity and a positive effect in mitigating menopausal and pre-menopausal symptoms, although several other studies disprove this (Sources: Archives of Gynecology and Obsterics, November 2007, pages 463–469; Journal of the American Pharmaceutical Association, March–April 2000, pages 327–329; and Fertility and Sterility, December 1997, pages 981–986). There is also research showing that it can stimulate the growth of breast cancer cells (Source: Menopause, March–April 2002, pages 145–150) and research indicating it has antioxidant properties (Source: Journal of Agricultural Food Chemistry, May 2007, pages 3358–3362). There are no studies showing that dong quai has any effect topically on skin.

Dromiceius oil. See emu oil.

dulse. See algae.

Durvillaea antarctica extract. Extract derived from a species of algae (Durvillea antarctica). See algae.