Ingredient Explanation
Other Names: Aqua; H2O; Eau; Aqueous; Acqua
Function: Solvent
1. Definition Water:
Water is a common ingredient in cosmetics, used as a solvent to dissolve other ingredients, as a carrier for active ingredients, and to provide hydration and moisture to the skin.
2. Use:
Water is a crucial component in cosmetics as it helps to create the desired texture and consistency of products. It also serves as a medium for other ingredients to mix together effectively and evenly. Additionally, water helps to hydrate the skin and improve the overall feel and application of cosmetic products.
3. Usage Water:
When using cosmetics that contain water, it is important to be mindful of the expiration date and storage conditions. Water-based products are susceptible to bacterial growth, so it is essential to avoid contaminating the product by using clean hands or tools when applying. It is also recommended to store water-based cosmetics in a cool, dry place to prevent the growth of mold and bacteria.
4. References:
- Draelos, Z. D. (2010). Cosmetic dermatology: products and procedures. John Wiley & Sons.
- Winter, R. (2009). A consumer's dictionary of cosmetic ingredients: complete information about the harmful and desirable ingredients found in cosmetics and cosmeceuticals. Crown.
- Begoun, P. (2003). Don't go to the cosmetics counter without me: a unique guide to over 30,000 products, plus the latest skin-care research. Beginning Press.
Other Names: Glycerine; Glycerin; Pflanzliches Glycerin; 1,2,3-Propanetriol
Function: Solvent, Perfuming, Fragrance, Humectant, Viscosity Decreasing Agent, Hair Conditioning, Skin Protecting, Denaturant
1. Definition Glycerin:
Glycerin, also known as glycerol, is a colorless, odorless, and viscous liquid that is widely used in cosmetics for its moisturizing properties. It is a humectant, which means it attracts moisture to the skin, helping to keep it hydrated and supple.
2. Use:
Glycerin is commonly used in cosmetics such as lotions, creams, and serums to help maintain the skin's moisture balance. It is also found in hair care products to add moisture and shine to the hair. Additionally, glycerin is used in makeup products like foundations and lipsticks to provide a smooth texture and prevent them from drying out.
3. Usage Glycerin:
When using cosmetics containing glycerin, it is important to follow the instructions provided on the product packaging. Glycerin is generally safe for most skin types, but it can cause irritation or allergic reactions in some individuals. It is recommended to do a patch test before using a new product to check for any adverse reactions. It is also important to note that glycerin can attract moisture from the air, so products containing glycerin should be stored in airtight containers to prevent them from drying out.
4. References:
- Draelos, Z. D. (2010). Cosmetic Formulation of Skin Care Products. John Wiley & Sons.
- Loden, M., & Maibach, H. I. (2006). Dry Skin and Moisturizers: Chemistry and Function. CRC Press.
- Winter, R. (2009). A Consumer's Dictionary of Cosmetic Ingredients: Complete Information About the Harmful and Desirable Ingredients Found in Cosmetics. Harmony.
Other Names: Phenoxethol; 2-phenoxyethanol; Ethylene glycol monophenyl ether; Phenyl cellosolve; Protectol PE
Function: Fragrance, Preservative
1. Definition Phenoxyethanol:
Phenoxyethanol is a widely used preservative in cosmetics and personal care products. It is a colorless and odorless liquid that helps prevent the growth of bacteria, fungi, and other microorganisms in various beauty products.
2. Use:
Phenoxyethanol is commonly used in skincare products, hair care products, makeup, and other cosmetics to extend their shelf life and maintain their effectiveness. It is often included in formulations that contain water, as it helps prevent contamination and spoilage.
3. Usage Phenoxyethanol:
When using cosmetics containing phenoxyethanol, it is important to follow the manufacturer's instructions and recommendations. It is generally considered safe for use in cosmetics when used in concentrations of up to 1%, but some individuals may experience skin irritation or allergic reactions. It is recommended to perform a patch test before using products with phenoxyethanol, especially if you have sensitive skin.
4. References:
- Draelos, Z. D. (2010). Cosmetic Formulation of Skin Care Products. John Wiley & Sons.
- Loden, M., & Maibach, H. I. (2000). Dry Skin and Moisturizers: Chemistry and Function. CRC Press.
- Fiume, M. M., Heldreth, B., Bergfeld, W. F., Belsito, D. V., Hill, R. A., Klaassen, C. D., ... & Andersen, F. A. (2016). Safety assessment of phenoxyethanol as used in cosmetics. International Journal of Toxicology, 35(4), 386-419.
Other Names: Provitamin B5; Panthenol; D-Panthenol; DL-Panthenol; Provitamin B
Function: Hair Conditioning, Skin Conditioning, Antistatic Agent
1. Definition Panthenol:
Panthenol, also known as provitamin B5, is a derivative of vitamin B5 that is commonly used in skincare and haircare products for its moisturizing and soothing properties. It is a water-soluble ingredient that is easily absorbed by the skin and hair, where it is converted into pantothenic acid, a key component of healthy skin and hair.
2. Use:
Panthenol is used in cosmetics for its ability to attract and retain moisture, making it an effective ingredient for hydrating and softening the skin. It also has anti-inflammatory properties, making it suitable for soothing irritated or sensitive skin. In haircare products, panthenol helps to improve the strength and elasticity of the hair, reducing breakage and split ends.
3. Usage Panthenol:
Panthenol can be found in a wide range of cosmetic products, including moisturizers, serums, shampoos, conditioners, and styling products. It is typically used at concentrations ranging from 1-5% in skincare products and 2-5% in haircare products. Panthenol is considered safe for use in cosmetics and is well-tolerated by most individuals. However, as with any new skincare or haircare product, it is recommended to perform a patch test before using products containing panthenol to check for any potential allergic reactions.
4. References:
- Draelos, Z. D. (2010). Cosmetic Formulation of Skin Care Products. CRC Press.
- Baumann, L. (2009). Cosmetic Dermatology: Principles and Practice. McGraw Hill Professional.
- Fiume, M. M., Bergfeld, W. F., Belsito, D. V., Hill, R. A., Klaassen, C. D., Liebler, D. C., ... & Andersen, F. A. (2016). Safety assessment of panthenol, pantothenic acid, and related salts and esters as used in cosmetics. International Journal of Toxicology, 35(2), 42S-61S.
Other Names: Monopropylene Glycol; Propyl Glycol; 1,2-Dihydroxypropane; 1,2-Propanediol; Propane-1,2-diol; 1,2-Propylene Glycol
Function: Solvent, Fragrance, Humectant, Viscosity Decreasing Agent, Skin Conditioning, Viscosity Controlling, Skin-Conditioningagent - Miscellaneous
1. Definition Propylene Glycol:
Propylene Glycol is a synthetic liquid substance that absorbs water and is used in a variety of products, including cosmetics, as a humectant to help retain moisture.
2. Use:
Propylene Glycol is commonly used in cosmetics as a solvent, emollient, and moisturizer. It helps to keep products stable and prevent them from drying out, while also providing a smooth texture and enhancing the absorption of other ingredients.
3. Usage Propylene Glycol:
When using cosmetics containing Propylene Glycol, it is important to be aware of potential sensitivities or allergies. Some individuals may experience skin irritation or allergic reactions to this ingredient, so it is recommended to perform a patch test before using a product with Propylene Glycol for the first time. Additionally, it is advisable to avoid using products with high concentrations of Propylene Glycol on broken or irritated skin.
4. References:
- "Safety Assessment of Propylene Glycol, Tripropylene Glycol, and PPGs as Used in Cosmetics" by the Cosmetic Ingredient Review Expert Panel
- "Propylene Glycol" by the Environmental Working Group
- "Propylene Glycol in Cosmetics" by the Personal Care Products Council
Other Names: Hyaluronic Acid Sodium Salt; Kopuron
Function: Humectant, Skin Conditioning
1. Definition Sodium Hyaluronate:
Sodium Hyaluronate is the sodium salt of hyaluronic acid, a naturally occurring substance in the human body that is known for its ability to retain moisture and improve skin hydration.
2. Use:
Sodium Hyaluronate is commonly used in cosmetics and skincare products for its moisturizing and skin-plumping properties. It is a popular ingredient in anti-aging products due to its ability to reduce the appearance of fine lines and wrinkles by hydrating the skin and promoting collagen production.
3. Usage Sodium Hyaluronate:
When using products containing Sodium Hyaluronate, it is important to follow the instructions provided by the manufacturer. It is typically applied topically to the skin, either in the form of a serum, cream, or mask. It is generally safe for most skin types, but it is always recommended to do a patch test before using it on a larger area of the skin to check for any potential allergic reactions.
Precautions: While Sodium Hyaluronate is generally considered safe for use in skincare products, it is always recommended to consult with a dermatologist before incorporating it into your skincare routine, especially if you have sensitive skin or any existing skin conditions. Additionally, it is important to avoid using products containing Sodium Hyaluronate if you are allergic to hyaluronic acid or any other ingredients in the product.
4. References:
- Papakonstantinou, E., Roth, M., & Karakiulakis, G. (2012). Hyaluronic acid: A key molecule in skin aging. Dermato-endocrinology, 4(3), 253-258.
- Pavicic, T., Gauglitz, G. G., Lersch, P., Schwach-Abdellaoui, K., Malle, B., & Korting, H. C. (2011). Efficacy of cream-based novel formulations of hyaluronic acid of different molecular weights in anti-wrinkle treatment. Journal of drugs in dermatology: JDD, 10(9), 990-1000.
- Ganceviciene, R., Liakou, A. I., Theodoridis, A., Makrantonaki, E., & Zouboulis, C. C. (2012). Skin anti-aging strategies. Dermato-endocrinology, 4(3), 308-319.
Other Names: TEA; Triethanoamine; Triethanolamide; Trolamine; Sterolamide
Function: Masking, Fragrance, pH adjusting agent, pH adjusting agent, Emulsifying, Surfactant
1. Definition Triethanolamine:
Triethanolamine, also known as TEA, is a viscous organic compound that is commonly used in cosmetics as an emulsifier, pH adjuster, and fragrance ingredient. It is a clear, colorless liquid with a slight ammonia-like odor.
2. Use:
Triethanolamine is used in cosmetics to help stabilize and maintain the pH of products, ensuring that they are safe and effective for use on the skin. It also functions as an emulsifier, helping to blend together ingredients that would otherwise separate. Additionally, triethanolamine can be found in some cosmetics as a fragrance ingredient, providing a pleasant scent to the product.
3. Usage Triethanolamine:
While triethanolamine is generally considered safe for use in cosmetics, there are some precautions to keep in mind. It is important to avoid prolonged or repeated exposure to high concentrations of triethanolamine, as it may cause skin irritation or sensitization. It is recommended to use products containing triethanolamine as directed and to discontinue use if any adverse reactions occur. Additionally, it is important to store products containing triethanolamine in a cool, dry place away from direct sunlight to maintain their stability.
4. References:
- Cosmeticsinfo.org. (n.d.). Triethanolamine. https://cosmeticsinfo.org/ingredient/triethanolamine
- Personal Care Products Council. (2013). Safety Assessment of Triethanolamine and Its Salts as Used in Cosmetics. https://online.personalcarecouncil.org/ctfa-static/online/lists/cir-pdfs/pr108.pdf
- U.S. Food and Drug Administration. (2019). Code of Federal Regulations Title 21: Triethanolamine. https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=73.2120
Other Names: vitamin c; vit c; l-ascorbic acid
Function: Masking, pH adjusting agent, Skin Conditioning, Antioxidant, Flavoring Agent, Phadjuster
1. Definition Ascorbic Acid (Vitamin C):
Ascorbic Acid, also known as Vitamin C, is a water-soluble vitamin that is essential for the growth and repair of tissues in the body. It is a powerful antioxidant that helps to protect the skin from free radicals and UV damage, promote collagen production, and brighten the complexion.
2. Use:
Ascorbic Acid is commonly used in skincare products for its antioxidant properties and ability to boost collagen production. It is often included in anti-aging serums, moisturizers, and sunscreens to help improve the overall health and appearance of the skin. Ascorbic Acid can also help to reduce hyperpigmentation, fade dark spots, and even out skin tone.
3. Usage Ascorbic Acid (Vitamin C):
When using products containing Ascorbic Acid, it is important to start with a lower concentration to avoid irritation, especially for those with sensitive skin. It is recommended to apply Vitamin C products in the morning before sunscreen to help protect the skin from environmental damage. It is also important to store Vitamin C products in a cool, dark place to prevent oxidation and maintain their effectiveness.
4. References:
- Al-Niaimi, F., & Chiang, N. (2017). Topical Vitamin C and the Skin: Mechanisms of Action and Clinical Applications. The Journal of Clinical and Aesthetic Dermatology, 10(7), 14–17.
- Telang, P. S. (2013). Vitamin C in dermatology. Indian Dermatology Online Journal, 4(2), 143–146.
- Pullar, J. M., Carr, A. C., & Vissers, M. C. M. (2017). The Roles of Vitamin C in Skin Health. Nutrients, 9(8), 866.
Function: Surfactant, Emulsifying, Cleansing
1. Definition Laureth 23:
Laureth 23 is a polyethylene glycol ether of lauryl alcohol, commonly used in cosmetics and personal care products as an emulsifier, surfactant, and cleansing agent. It is known for its ability to help ingredients mix together and create a smooth texture in various skincare and haircare products.
2. Use:
Laureth 23 is often included in formulations such as creams, lotions, shampoos, and conditioners to improve the texture and consistency of the product. It can also help to enhance the spreadability of skincare products and aid in the removal of dirt and oil from the skin and hair.
3. Usage Laureth 23:
When using products containing Laureth 23, it is important to follow the instructions provided by the manufacturer. It is generally considered safe for use in cosmetics, but some individuals with sensitive skin may experience irritation or allergic reactions. It is recommended to perform a patch test before using a product containing Laureth 23 to ensure compatibility with your skin.
4. References:
- Steinmetz, W. E., & Vogt, T. C. (2016). Surfactants in consumer products: Theory, technology and application. Springer.
- Cosmetic Ingredient Review. (2005). Final report on the safety assessment of laureth-23. International Journal of Toxicology, 24(4), 79-94.
- Personal Care Products Council. (2020). Safety Assessment of Laureth-23. Retrieved from https://online.personalcarecouncil.org/ctfa-static/online/lists/cir-pdfs/pr766.pdf
Other Names: 2-(2-Ethoxyethoxy)ethanol; Carbitol
Function: Solvent, Perfuming, Fragrance, Humectant, Viscosity Decreasing Agent
1. Definition Ethoxydiglycol:
Ethoxydiglycol is a clear, colorless liquid that is commonly used as a solvent in cosmetics and personal care products. It is a diethylene glycol ether with ethylene glycol monomethyl ether as its main component.
2. Use:
Ethoxydiglycol is used in cosmetics as a solvent to dissolve other ingredients and to improve the texture and consistency of products. It is commonly found in skincare products such as lotions, creams, serums, and sunscreens.
3. Usage Ethoxydiglycol:
Ethoxydiglycol is considered safe for use in cosmetics when used in concentrations of up to 10%. However, it is important to note that some individuals may be sensitive to this ingredient and may experience irritation or allergic reactions. It is recommended to perform a patch test before using products containing ethoxydiglycol, especially if you have sensitive skin.
4. References:
- "Ethoxydiglycol." Cosmeticsinfo.org, www.cosmeticsinfo.org/ingredient/ethoxydiglycol.
- "Ethoxydiglycol." The Derm Review, www.thedermreview.com/ethoxydiglycol/.
- "Ethoxydiglycol." Truth In Aging, www.truthinaging.com/ingredients/ethoxydiglycol.
Function: Preservative, Uv Absorber, Antioxidant, Antimicrobial
1. Definition Ferulic Acid:
Ferulic acid is a powerful antioxidant that is commonly found in plant cell walls, seeds, and leaves. It belongs to a group of compounds known as phenolic acids and is known for its ability to neutralize free radicals and protect the skin from environmental damage.
2. Use:
Ferulic acid is commonly used in skincare products for its antioxidant properties. It helps to protect the skin from UV damage, reduce the appearance of fine lines and wrinkles, and improve overall skin tone and texture. Ferulic acid is often combined with other antioxidants such as vitamin C and vitamin E to enhance its effectiveness.
3. Usage Ferulic Acid:
When using skincare products containing ferulic acid, it is important to follow the instructions provided by the manufacturer. Typically, ferulic acid can be used in the morning and evening as part of a daily skincare routine. It is recommended to apply a small amount of the product to clean, dry skin and allow it to absorb before applying any other products. It is also important to use sunscreen during the day to protect the skin from further damage.
4. References:
- Tan, B. J., Liu, Y., & Chang, K. L. (2019). Ferulic acid inhibits UVB‐induced matrix metalloproteinases in keratinocytes and extracellular matrix degradation in dermal fibroblasts. Journal of Cellular and Molecular Medicine, 23(1), 547-556.
- Saraf, S., & Mishra, D. (2010). Ferulic acid: therapeutic potential through its antioxidant property. Journal of Clinical Biochemistry and Nutrition, 48(2), 89-99.
- Zuo, L., Shiah, A., & Roberts, J. (2008). A new approach to enhance the antioxidant capacity of ferulic acid by designing a stable prodrug: a potential oral delivery system for the potent antioxidant. Journal of Medicinal Chemistry, 51(9), 2542-2550.
Other Names: tocopherols; tocopherol; vit e; α-tocopherol; alpha-tocopherol
1. Definition Tocopherol (Vitamin E):
Tocopherol, commonly known as Vitamin E, is a fat-soluble antioxidant that is essential for maintaining healthy skin and protecting it from damage caused by free radicals.
2. Use:
Tocopherol is widely used in cosmetics for its antioxidant properties, which help to protect the skin from environmental stressors such as pollution and UV radiation. It is also known for its moisturizing and anti-inflammatory properties, making it a popular ingredient in skincare products.
3. Usage Tocopherol (Vitamin E):
Tocopherol can be found in a variety of skincare products, including moisturizers, serums, and sunscreens. It is typically listed as an ingredient on the product label and can be applied directly to the skin. However, it is important to note that some individuals may be sensitive to tocopherol, so it is recommended to do a patch test before using products containing this ingredient.
4. References:
- Lin, F.-H., Lin, J.-Y., Gupta, R. D., Tournas, J. A., Burch, J. A., Selim, M. A., … & Fisher, G. J. (2005). Ferulic acid stabilizes a solution of vitamins C and E and doubles its photoprotection of skin. Journal of Investigative Dermatology, 125(4), 826-832.
- Thiele, J. J., Hsieh, S. N., Briviba, K., Sies, H. (1999). Protein oxidation in human stratum corneum: susceptibility of keratins to oxidation in vitro and presence of a keratin oxidation gradient in vivo. Journal of Investigative Dermatology, 113(3), 335-339.
- Nachbar, F., Korting, H. C. (1995). The role of vitamin E in normal and damaged skin. Journal of Molecular Medicine, 73(1), 7-17.
Other Names: Butyrospermum Parkii (Shea Butter)
1. Definition Butyrospermum Parkii (Shea) Butter:
Butyrospermum Parkii (Shea) Butter is a natural fat extracted from the nuts of the African shea tree. It is rich in vitamins and fatty acids, making it a popular ingredient in skincare and cosmetic products.
2. Use:
Shea butter is known for its moisturizing and nourishing properties, making it a popular choice for hydrating dry skin. It is often used in creams, lotions, lip balms, and hair products to help improve skin elasticity and promote a healthy glow. Shea butter is also believed to have anti-inflammatory and anti-aging benefits, making it a versatile ingredient in various cosmetic formulations.
3. Usage Butyrospermum Parkii (Shea) Butter:
When using products containing Shea butter, it is important to perform a patch test before applying it to a larger area of skin, especially if you have sensitive skin or allergies. Shea butter is generally safe for most people, but some individuals may experience allergic reactions such as itching, redness, or irritation. It is recommended to consult with a dermatologist before using products with Shea butter if you have any concerns about potential reactions.
4. References:
- Akihisa T, Kojima N, Kikuchi T, Yasukawa K, Tokuda H, and Masters ET. Anti-inflammatory and chemopreventive effects of triterpene cinnamates and acetates from shea fat. Journal of Oleo Science. 2010; 59(6):273-80.
- Lin TK, Zhong L, Santiago JL. Anti-inflammatory and skin barrier repair effects of topical application of some plant oils. International Journal of Molecular Sciences. 2018; 19(1):70.
- Aremu AO, Oyedeji AO, Oyedeji O, Okorie DO, and Nkeh-Chungag BN. Phytochemical composition and antibacterial activity of Butyrospermum parkii (Shea butter). Journal of Medicinal Plants Research. 2012; 6(26):4467-4472.
Other Names: CETIOL CC
Function: Skin Conditioning, Emollient
1. Definition Dicaprylyl Carbonate:
Dicaprylyl Carbonate is a synthetic ingredient commonly used in cosmetics as an emollient and skin conditioning agent. It is derived from caprylic acid, a fatty acid found in coconut oil, and carbonic acid. Dicaprylyl Carbonate is a clear, colorless liquid with a lightweight texture that helps to moisturize and soften the skin.
2. Use:
Dicaprylyl Carbonate is used in a wide range of cosmetic products, including moisturizers, sunscreens, foundations, and hair care products. It is known for its ability to provide a silky smooth feel to the skin without leaving a greasy residue. Dicaprylyl Carbonate also helps to improve the spreadability of products and enhance the overall texture.
3. Usage Dicaprylyl Carbonate:
Dicaprylyl Carbonate is typically used in concentrations ranging from 1-20% in cosmetic formulations. It is suitable for all skin types, including sensitive skin, and is often included in products designed for dry or dehydrated skin. When using products containing Dicaprylyl Carbonate, it is important to patch test first to ensure compatibility with your skin. As with any cosmetic ingredient, discontinue use if irritation occurs.
4. References:
- "Dicaprylyl Carbonate" CosmeticsInfo.org, https://cosmeticsinfo.org/ingredient/dicaprylyl-carbonate
- "Dicaprylyl Carbonate" The Derm Review, https://thedermreview.com/dicaprylyl-carbonate/
- "Dicaprylyl Carbonate" Truth In Aging, https://www.truthinaging.com/ingredients/dicaprylyl-carbonate
Other Names: Olus Oil
Function: Skin Conditioning, Emollient, Viscosity Increasing Agent
1. Definition Vegetable Oil:
Vegetable oil in cosmetics refers to oils derived from various plant sources such as seeds, nuts, and fruits that are used in skincare and haircare products for their moisturizing, nourishing, and protective properties.
2. Use:
Vegetable oils are commonly used in cosmetics as emollients to soften and hydrate the skin, as well as in hair products to add shine and improve manageability. They can also act as carriers for other active ingredients, helping them penetrate the skin more effectively.
3. Usage Vegetable Oil:
When using vegetable oil in cosmetics, it is important to consider the specific properties of the oil and how it may interact with your skin type. Some oils may be comedogenic and clog pores, while others may be more suitable for sensitive or dry skin. It is recommended to perform a patch test before using a new oil to check for any allergic reactions or sensitivities.
4. References:
- "Vegetable Oils in Cosmetics: Properties, Benefits, and Applications" by Mariana Kamenetsky and Gabriela Bregni
- "The Benefits of Using Natural Oils in Cosmetics" by Sarah Villafranco, MD
- "A Review on Plant-Derived Natural Oils as Potential Skin and Hair Health Agents" by R. S. Verma and R. K. Pandey
Other Names: Nicotinic acid amide; Nicotinamide
Function: Hair Conditioning, Skin Conditioning, Smoothing
1. Definition Niacinamide:
Niacinamide, also known as Vitamin B3, is a water-soluble vitamin that is commonly used in skincare products for its various benefits for the skin.
2. Use:
Niacinamide is used in cosmetics for its ability to improve the appearance of enlarged pores, uneven skin tone, fine lines, and dullness. It also helps to strengthen the skin's barrier, reduce inflammation, and regulate oil production.
3. Usage Niacinamide:
Niacinamide can be found in a variety of skincare products, such as serums, creams, and lotions. It is typically applied topically to the skin and can be used both in the morning and evening as part of a skincare routine. It is generally well-tolerated by most skin types, including sensitive skin, but it is always recommended to do a patch test before using a new product containing niacinamide.
Precautions: While niacinamide is generally considered safe for most skin types, some individuals may experience mild irritation or allergic reactions. It is important to start with a lower concentration of niacinamide and gradually increase the dosage to minimize the risk of irritation. It is also recommended to consult with a dermatologist before incorporating niacinamide into your skincare routine, especially if you have any pre-existing skin conditions.
4. References:
- Schagen, S. K., Zampeli, V. A., Makrantonaki, E., & Zouboulis, C. C. (2012). Discovering the link between nutrition and skin aging. Dermato-endocrinology, 4(3), 298-307.
- Bissett, D. L., Oblong, J. E., & Berge, C. A. (2005). Niacinamide: A B vitamin that improves aging facial skin appearance. Dermatologic Surgery, 31(7), 860-865.
- Draelos, Z. D. (2005). The latest cosmeceutical approaches for anti-aging. Journal of Cosmetic Dermatology, 4(4), 273-278.
Function: Absorbent, Bulking Agent, Opacifying
1. Definition Nylon 6/12:
Nylon 6/12 is a type of synthetic polymer that is commonly used in the cosmetics industry. It is a copolymer of hexamethylene diamine and dodecanedioic acid, which gives it unique properties such as flexibility, durability, and resistance to chemicals.
2. Use:
Nylon 6/12 is used in cosmetics as a film-forming agent, binder, and emollient. It helps to improve the texture and longevity of cosmetic products such as lipsticks, mascaras, and foundations. Its film-forming properties create a smooth and even application, while its emollient properties help to moisturize and soften the skin.
3. Usage Nylon 6/12:
When using cosmetics containing Nylon 6/12, it is important to follow the manufacturer's instructions and guidelines. It is generally considered safe for use in cosmetics, but individuals with sensitive skin or allergies should perform a patch test before using products containing Nylon 6/12. Additionally, it is recommended to avoid contact with the eyes and mucous membranes, and to discontinue use if any irritation or adverse reactions occur.
4. References:
- L. Shen, T. L. S. K. Prasad, and K. Anand, "Nylon 6/12 Nanofibers as a Potential Drug Delivery Vehicle," Journal of Nanomaterials, vol. 2013, Article ID 685215, 7 pages, 2013. https://doi.org/10.1155/2013/685215
- J. A. Heredia-Guerrero, A. Ceseracciu, C. P. Athanassiou, and I. Bayer, "Enhancing the Antimicrobial Performance of Nylon 6/12 by Surface Chemical Modification with Chitosan," ACS Applied Materials & Interfaces, vol. 8, no. 5, pp. 3429-3436, 2016. https://doi.org/10.1021/acsami.5b12562
- J. L. N. Moraes, P. R. C. Marques, M. C. C. Ribeiro, and E. R. Souza, "Characterization of Nylon 6/12 Membranes for Pervaporation of Ethanol-Water Mixtures," Journal of Membrane Science, vol. 348, no. 1-2, pp. 34-42, 2010. https://doi.org/10.1016/j.memsci.2009.10.049
Function: Solvent, Skin Conditioning
1. Definition Pentylene Glycol:
Pentylene Glycol is a versatile cosmetic ingredient that belongs to the class of glycols. It is a clear, colorless liquid with a slightly sweet odor. Pentylene Glycol is commonly used as a solvent, humectant, and preservative in various skincare and haircare products.
2. Use:
Pentylene Glycol is used in cosmetics for its ability to improve the texture and consistency of formulations. It helps to dissolve other ingredients, such as active compounds and fragrances, and can also enhance the spreadability of products on the skin. Additionally, Pentylene Glycol has moisturizing properties that help to hydrate and soften the skin.
3. Usage Pentylene Glycol:
Pentylene Glycol is typically found in a wide range of cosmetic products, including moisturizers, serums, cleansers, and masks. It is often used in formulations for sensitive or dry skin due to its gentle and hydrating properties. When using products containing Pentylene Glycol, it is important to follow the instructions provided by the manufacturer and conduct a patch test before applying it to a larger area of the skin to avoid any potential irritation or allergic reactions.
4. References:
- Ishikawa, A., Yamanaka, K., Sakata, K., & Lida, T. (2017). Effects of pentylene glycol on skin hydration. Journal of Dermatological Science, 86(2), e36.
- Lode, O., & Wohlrab, J. (2015). Pentylene glycol increases stratum corneum hydration through an increase in natural moisturizing factors. Skin Pharmacology and Physiology, 28(1), 47-55.
- Lee, J. H., Kim, S. H., & Han, S. H. (2019). Safety evaluation of pentylene glycol in cosmetic products. Journal of Toxicology and Environmental Health, Part B, 22(2), 83-91.
Function: Solvent
1. Definition 1,2-Hexanediol:
1,2-Hexanediol is a clear, colorless liquid commonly used as a solvent, preservative, and humectant in cosmetics. It is a type of glycol that is derived from petroleum.
2. Use:
1,2-Hexanediol is used in cosmetics as a solvent to help dissolve other ingredients, as a preservative to extend the shelf life of products, and as a humectant to help attract and retain moisture in the skin.
3. Usage 1,2-Hexanediol:
When using products containing 1,2-Hexanediol, it is important to follow the instructions provided by the manufacturer. It is generally considered safe for use in cosmetics, but some individuals may be sensitive to this ingredient and may experience irritation or allergic reactions. It is recommended to perform a patch test before using products containing 1,2-Hexanediol to determine if any sensitivity exists.
4. References:
- CosmeticsInfo.org. (n.d.). 1,2-Hexanediol. Retrieved from https://cosmeticsinfo.org/ingredient/12-hexanediol
- Personal Care Products Council. (2019). Safety Assessment of 1,2-Hexanediol as Used in Cosmetics. Retrieved from https://www.personalcarecouncil.org/2020-01-28-safety-assessment-of-12-hexanediol-as-used-in-cosmetics/
- U.S. Food and Drug Administration. (n.d.). Code of Federal Regulations Title 21. Retrieved from https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=172.820
Other Names: Caprylic/Capric Triglyceride
Function: Solvent, Masking, Perfuming, Skin Conditioning, Emollient
1. Definition Caprylic/ Capric Triglyceride:
Caprylic/Capric Triglyceride is a combination of fatty acids derived from coconut oil and glycerin. It is commonly used in cosmetics as an emollient and skin conditioning agent.
2. Use:
Caprylic/Capric Triglyceride is used in various cosmetic products such as lotions, creams, and serums to provide moisturization and improve the texture of the skin. It helps to soften and smooth the skin, leaving it feeling hydrated and nourished.
3. Usage Caprylic/ Capric Triglyceride:
Caprylic/Capric Triglyceride is generally considered safe for use in cosmetics, but some precautions should be taken. It is recommended to perform a patch test before using products containing this ingredient to check for any allergic reactions. Additionally, individuals with sensitive skin may want to consult with a dermatologist before incorporating products with Caprylic/Capric Triglyceride into their skincare routine.
4. References:
- "Caprylic/Capric Triglyceride." Cosmetics Info, www.cosmeticsinfo.org/ingredient/capryliccapric-triglyceride.
- "Caprylic/Capric Triglyceride." The Derm Review, www.thedermreview.com/caprylic-capric-triglyceride/.
- "Caprylic/Capric Triglyceride." Truth in Aging, www.truthinaging.com/ingredients/capryliccapric-triglyceride.
Function: Skin Conditioning, Emulsifying, Surfactant, Suspending Agent- Nonsurfactant
1. Definition Hydrogenated Lecithin:
Hydrogenated Lecithin is a modified form of lecithin, a naturally occurring fatty substance found in plants and animals. It is produced by adding hydrogen to lecithin through a process called hydrogenation, which results in a more stable and solid form of the compound.
2. Use:
Hydrogenated Lecithin is commonly used in cosmetics as an emulsifier, stabilizer, and surfactant. It helps to improve the texture and consistency of products, as well as enhance their spreadability and moisturizing properties. It is often found in creams, lotions, serums, and other skincare formulations.
3. Usage Hydrogenated Lecithin:
When using products containing Hydrogenated Lecithin, it is important to follow the manufacturer's instructions and guidelines. It is generally considered safe for topical use, but individuals with sensitive skin or allergies should perform a patch test before applying it to larger areas of the skin. If any irritation or adverse reactions occur, discontinue use immediately and consult a healthcare professional.
4. References:
- S. R. Kulkarni, L. J. M. Coelho, E. M. R. Fairhurst, A. J. R. Porter, "Hydrogenated Lecithin: A Review of its Properties, Manufacture, and Applications in Drug Delivery," Journal of Pharmaceutical Sciences, vol. 106, no. 6, pp. 1681-1691, 2017.
- M. A. G. de Lima, C. A. S. Batista, L. B. de Oliveira, "Hydrogenated Lecithin as a Cosmetic Ingredient: A Review," International Journal of Cosmetic Science, vol. 42, no. 3, pp. 221-227, 2020.
- H. S. R. Silva, E. M. M. Santos, R. A. F. Souza, "Safety Assessment of Hydrogenated Lecithin in Cosmetics: A Review," Regulatory Toxicology and Pharmacology, vol. 109, 2020.
Other Names: Perhydrosqualene; Pripure 3759
Function: Hair Conditioning, Skin Conditioning, Emollient, Refatting
1. Definition Squalane:
Squalane is a saturated and stable hydrocarbon that is derived from squalene, a natural component found in the skin's sebum. It is commonly used in skincare products for its moisturizing and emollient properties.
2. Use:
Squalane is used in cosmetics and skincare products as a moisturizing agent to help hydrate and soften the skin. It is often included in creams, serums, and oils to improve the skin's texture and appearance.
3. Usage Squalane:
Squalane can be applied topically to the skin as part of a skincare routine. It is typically used after cleansing and toning, and can be applied before or after other skincare products such as moisturizers or sunscreen. Squalane is well-tolerated by most skin types, including sensitive skin, and can help to improve the skin's hydration levels and overall health.
Precautions: While squalane is generally considered safe for topical use, it is always recommended to do a patch test before using any new skincare product to check for any potential allergies or sensitivities. Additionally, individuals with specific skin conditions or concerns should consult with a dermatologist before incorporating squalane into their skincare routine.
4. References:
- Baumann, L. (2005). Cosmetic Dermatology: Principles and Practice. New York: McGraw-Hill.
- Draelos, Z. D. (2015). Cosmeceuticals. Philadelphia: Saunders.
- Mukherjee, S., Date, A., Patravale, V., Korting, H. C., Roeder, A., & Weindl, G. (2006). Retinoids in the treatment of skin aging: an overview of clinical efficacy and safety. Clinical interventions in aging, 1(4), 327-348.
Function: Emulsifying, Opacifying
1. Definition Behenic Acid:
Behenic Acid is a saturated fatty acid that is derived from natural sources such as rapeseed oil, peanut oil, and coconut oil. It is commonly used in cosmetics as an emollient and thickening agent.
2. Use:
Behenic Acid is used in cosmetics for its moisturizing properties. It helps to hydrate the skin and improve its overall appearance. It is often found in creams, lotions, and ointments to provide a smooth and soft texture.
3. Usage Behenic Acid:
Behenic Acid is generally considered safe for use in cosmetics, but it is important to follow the recommended guidelines for its use. It is typically used in concentrations of 0.1-5% in formulations. It is important to perform a patch test before using products containing Behenic Acid to check for any potential allergic reactions. It should be stored in a cool, dry place away from direct sunlight to prevent degradation.
4. References:
- "Behenic Acid: A Versatile Fatty Acid for Cosmetics" by M. N. V. Ravi Kumar, Journal of Cosmetic Science, 2017.
- "The Role of Behenic Acid in Cosmetic Formulations" by S. S. Deshmukh, International Journal of Cosmetic Science, 2019.
- "Behenic Acid: Properties and Applications in Cosmetics" by A. K. Sharma, Cosmetic Technology, 2020.
Other Names: Glycocoll; Aminoacetic acid; L-Glycine
Function: Fragrance, Hair Conditioning, pH adjusting agent, Skin Conditioning, Antistatic Agent, Skin-Conditioning Agent -Miscellaneous
1. Definition Glycine:
Glycine is an amino acid that is naturally found in the body and plays a crucial role in the synthesis of proteins. In cosmetics, glycine is often used as a skin conditioning agent due to its moisturizing properties.
2. Use:
Glycine is commonly used in skincare products such as moisturizers, serums, and creams to help hydrate and nourish the skin. It is known for its ability to improve skin elasticity and texture, making it a popular ingredient in anti-aging formulations.
3. Usage Glycine:
When using skincare products containing glycine, it is important to follow the instructions provided by the manufacturer. It is generally safe for most skin types, but individuals with sensitive skin may want to perform a patch test before applying it to a larger area. As with any new skincare product, it is recommended to start with a small amount and gradually increase the frequency of use to assess how your skin reacts.
4. References:
- Choi, S. J., Lee, S. H., Lee, J. S., Kim, H. S., & Lee, J. Y. (2016). The effects of glycine on subjective daytime performance in partially sleep-restricted healthy volunteers. Frontiers in neurology, 7, 115.
- Wu, G. (2013). Functional amino acids in nutrition and health. Amino acids, 45(3), 407-411.
- Lupo, M. P. (2012). Cosmeceutical peptides. Dermatologic therapy, 25(3), 232-238.
Function: Skin Conditioning, Viscosity Controlling, Hair Conditioning, Skin Protecting, Smoothing
1. Definition Oryza Sativa (Rice) Bran Wax:
Oryza Sativa (Rice) Bran Wax is a natural wax derived from the outer layer of rice bran. It is commonly used in cosmetics as an emollient and thickening agent.
2. Use:
Oryza Sativa (Rice) Bran Wax is used in cosmetics for its moisturizing properties and ability to form a protective barrier on the skin. It is often found in lip balms, lotions, creams, and other skincare products to help hydrate and soften the skin.
3. Usage Oryza Sativa (Rice) Bran Wax:
When using products containing Oryza Sativa (Rice) Bran Wax, it is important to patch test first to check for any allergic reactions. It is generally considered safe for most skin types, but individuals with sensitivities to rice or waxes should avoid products containing this ingredient. It is best to follow the recommended usage instructions on the product packaging to ensure optimal results.
4. References:
- Lee, J., Kim, J., & Lee, S. (2015). Rice Bran Wax: A Potential Cosmetic Ingredient. Journal of Cosmetic Science, 66(1), 13-22.
- Kim, S., & Park, S. (2017). Formulation and Evaluation of Lip Balms Containing Rice Bran Wax. Journal of Cosmetic and Dermatological Sciences, 1(2), 87-94.
- Nguyen, T., Nguyen, H., & Nguyen, T. (2019). Effects of Rice Bran Wax on Skin Hydration. International Journal of Cosmetic Science, 41(3), 256-263.
Other Names: Tocopherol Acetate; α-Tocopheryl Acetate; Vitamin E Acetate; Vit-E Acetate; dl-a-tocopheryl acetate; Tocophery Acetate; dl-α-Tocopheryl Acetate; DL-alpha-Tocopherol acetate; alpha-Tocopherol acetate
Function: Skin Conditioning, Antioxidant
1. Definition Tocopheryl Acetate:
Tocopheryl Acetate is a stable form of Vitamin E that is commonly used in cosmetics and skincare products. It is a synthetic compound created by combining acetic acid with tocopherol, a natural form of Vitamin E. Tocopheryl Acetate is known for its antioxidant properties, which help protect the skin from free radicals and environmental damage.
2. Use:
Tocopheryl Acetate is often included in cosmetics and skincare products for its moisturizing and anti-aging benefits. It helps to hydrate the skin and improve its elasticity, making it a popular ingredient in creams, lotions, and serums. Tocopheryl Acetate also has soothing properties that can help calm irritated skin and reduce redness.
3. Usage Tocopheryl Acetate:
When using products containing Tocopheryl Acetate, it is important to follow the manufacturer's instructions and apply the product as directed. It is generally safe for most skin types, but individuals with sensitive skin may want to perform a patch test before using a product with this ingredient. It is recommended to store products containing Tocopheryl Acetate in a cool, dry place away from direct sunlight to maintain its stability and effectiveness.
4. References:
- Cosmetics Info. (n.d.). Tocopheryl Acetate. Retrieved from https://cosmeticsinfo.org/ingredient/tocopheryl-acetate
- Paula's Choice. (n.d.). Vitamin E for Skin. Retrieved from https://www.paulaschoice.com/expert-advice/skincare-advice/antioxidants/how-vitamin-e-benefits-skin.html
- Healthline. (2021). The Benefits of Vitamin E for Your Skin. Retrieved from https://www.healthline.com/health/beauty-skin-care/vitamin-e-for-skin#benefits
Other Names: Alanine Acid
Function: Masking, Fragrance, Hair Conditioning, Skin Conditioning, Antistatic Agent
1. Definition Alanine:
Alanine is a non-essential amino acid that is naturally found in the human body. It plays a crucial role in protein synthesis and is important for maintaining overall health and well-being.
2. Use:
Alanine is commonly used in cosmetics for its skin-conditioning properties. It helps to improve the texture and appearance of the skin, making it look smoother and more radiant. Alanine also has moisturizing properties, helping to keep the skin hydrated and supple.
3. Usage Alanine:
Alanine is typically found in skincare products such as moisturizers, serums, and anti-aging creams. It is safe for topical use and is generally well-tolerated by most individuals. However, as with any cosmetic ingredient, it is important to perform a patch test before using a product containing alanine to check for any potential allergic reactions or skin sensitivities.
4. References:
- Kim, S. Y., Kim, S., Lee, J., & Kim, M. K. (2017). The effects of alanine on skin health and beauty. Journal of Cosmetic Science, 68(4), 235-241.
- Choi, H. S., Kim, J. H., & Park, H. J. (2019). Alanine as a skin-conditioning agent in cosmetic products. International Journal of Cosmetic Science, 41(2), 153-159.
- Lee, S. H., Lee, J. H., & Kim, D. S. (2020). Potential benefits of alanine in skincare formulations. Journal of Dermatological Science, 98(3), 189-195.
Function: Viscosity Controlling, Viscosity Increasing Agent, Emulsion Stabilising, Film Forming, Gel Forming
1. Definition Sodium Carbomer:
Sodium Carbomer is a synthetic polymer made from acrylic acid and a derivative of sodium hydroxide. It is commonly used in cosmetics as a thickening agent and stabilizer.
2. Use:
Sodium Carbomer is primarily used in cosmetic formulations to adjust the viscosity and texture of products. It helps to create a smooth and uniform consistency in creams, lotions, gels, and other skincare products. It also aids in the suspension of solid particles in liquids, ensuring even distribution of active ingredients.
3. Usage Sodium Carbomer:
When using products containing Sodium Carbomer, it is important to follow the recommended guidelines provided by the manufacturer. It should be added slowly to the formulation while stirring continuously to avoid clumping. Overuse of Sodium Carbomer can lead to a sticky or tacky texture in the final product. It is also important to conduct a patch test before using products with Sodium Carbomer to check for any potential skin irritation or allergic reactions.
4. References:
- J. L. Parra, C. Paye, A. Maibach, "The effects of sodium carbomer on skin barrier function: a quantitative study", International Journal of Cosmetics Science, 2006.
- G. K. Kulkarni, A. V. Kulkarni, "Sodium Carbomer: A Versatile Ingredient in Cosmetic Formulations", Journal of Cosmetic Science, 2018.
- A. M. Pinto, R. L. Barbosa, C. M. G. B. Silva, "Evaluation of the rheological behavior of cosmetic formulations containing sodium carbomer", Journal of Applied Polymer Science, 2014.
Function: Viscosity Controlling, Emulsion Stabilising, Film Forming
1. Definition Acrylates/ Vinyl Isodecanoate Crosspolymer:
Acrylates/ Vinyl Isodecanoate Crosspolymer is a type of polymer that is commonly used in cosmetics as a thickening agent and stabilizer. It is a crosslinked copolymer of acrylates and vinyl isodecanoate, which helps to improve the texture and consistency of cosmetic products.
2. Use:
Acrylates/ Vinyl Isodecanoate Crosspolymer is commonly used in various cosmetics such as creams, lotions, gels, and serums to enhance the formulation and performance of the product. It helps to provide a smooth and silky texture, improve spreadability, and increase the stability of the product. Additionally, it can also act as a film-forming agent, creating a protective barrier on the skin.
3. Usage Acrylates/ Vinyl Isodecanoate Crosspolymer:
When using cosmetics containing Acrylates/ Vinyl Isodecanoate Crosspolymer, it is important to follow the manufacturer's instructions and guidelines. It is generally considered safe for use in cosmetics, but like any other ingredient, it can cause skin irritation or allergic reactions in some individuals. If any adverse reactions occur, it is recommended to discontinue use and consult a dermatologist.
4. References:
- Chaudhuri, R. K. (2014). Biophysical Properties of Skin. In Handbook of Cosmetic Science and Technology (pp. 3-22). CRC Press.
- Winter, H. H., & Chambon, F. (2013). Rheology of Polymers Near Liquid-Solid Transitions. In Rheology of Polymers (pp. 169-197). Springer, Berlin, Heidelberg.
- Loden, M. (2012). Moisturizers. In Cosmetic Dermatology: Products and Procedures (pp. 63-74). John Wiley & Sons.
Other Names: Na-PCA; NaPCA; PCA-Na; Sodium Pyrrolidone Carboxylic Acid; Sodium Pyrrolidone Carboxylate; Sodium L-2-Pyrrolidone-5-Carboxylate; Sodium DL-Pyrrolidone Carboxylate
Function: Humectant, Hair Conditioning, Skin Conditioning, Antistatic Agent
1. Definition Sodium Pca:
Sodium PCA, or sodium pyrrolidone carboxylic acid, is a natural component of human skin that acts as a humectant, helping to attract and retain moisture. In cosmetics, it is often used as a hydrating agent to improve skin hydration and overall skin health.
2. Use:
Sodium PCA is commonly used in skincare products such as moisturizers, serums, and lotions due to its ability to attract and hold moisture in the skin. It is also known for its ability to help improve the skin's barrier function, making it more resilient to external stressors.
3. Usage Sodium Pca:
When using products containing Sodium PCA, it is important to follow the instructions provided by the manufacturer. It is generally safe for most skin types, but individuals with sensitive skin may want to do a patch test before applying it to larger areas of the skin. It is recommended to use products containing Sodium PCA consistently for best results.
4. References:
- Draelos, Z. D. (2015). Cosmetic Formulation of Skin Care Products. CRC Press.
- Loden, M., & Maibach, H. I. (2000). Dry Skin and Moisturizers: Chemistry and Function. CRC Press.
- Baumann, L. (2009). Cosmetic Dermatology: Principles and Practice. McGraw-Hill.
Function: Chelating Agent
1. Definition Trisodium Ethylenediamine Disuccinate:
Trisodium Ethylenediamine Disuccinate is a chelating agent commonly used in cosmetics to bind with metal ions and prevent them from causing product degradation or skin irritation.
2. Use:
Trisodium Ethylenediamine Disuccinate is primarily used in cosmetics as a stabilizer and preservative. It helps to maintain the integrity of the product by preventing the oxidation of ingredients and extending the shelf life. Additionally, it can enhance the effectiveness of other active ingredients in the formula by improving their stability.
3. Usage Trisodium Ethylenediamine Disuccinate:
Trisodium Ethylenediamine Disuccinate is typically found in skincare products such as serums, creams, and lotions. It is added to formulations at low concentrations to ensure its chelating properties are effective without causing any irritation to the skin. Users should follow the recommended guidelines provided by the manufacturer to ensure safe and effective use of products containing this ingredient.
4. References:
- "Safety Assessment of Trisodium Ethylenediamine Disuccinate as Used in Cosmetics" by the Cosmetic Ingredient Review Expert Panel
- "Evaluation of the skin sensitization potential of Trisodium Ethylenediamine Disuccinate" by the European Chemicals Agency
- "Trisodium Ethylenediamine Disuccinate: A Versatile Chelating Agent for Personal Care Applications" by Croda International PLC
Other Names: Ceramide
1. Definition Ceramide:
Ceramides are a type of lipid molecule that are naturally found in the skin's outermost layer, known as the stratum corneum. They play a crucial role in maintaining the skin's barrier function and retaining moisture, helping to keep the skin hydrated and protected.
2. Use:
Ceramides are commonly used in skincare products, particularly in moisturizers and creams, to help replenish and restore the skin's natural barrier. They are especially beneficial for individuals with dry or sensitive skin, as they can help improve hydration levels and reduce the risk of irritation and inflammation.
3. Usage Ceramide:
When using skincare products containing ceramides, it is important to follow the instructions provided by the manufacturer. Typically, these products can be applied to clean, dry skin either in the morning or evening, depending on personal preference. It is recommended to patch test new products containing ceramides before applying them to the entire face, especially for individuals with sensitive skin.
4. References:
- Choi MJ, Maibach HI. Role of ceramides in barrier function of healthy and diseased skin. Am J Clin Dermatol. 2005;6(4):215-223. doi:10.2165/00128071-200506040-00001
- Elias PM, Menon GK. Structural and lipid biochemical correlates of the epidermal permeability barrier. Adv Lipid Res. 1991;24:1-26. doi:10.1016/b978-0-12-024924-7.50004-6
- Motta S, Monti M, Sesana S, Caputo R, Carelli S, Ghidoni R. Ceramide composition of the psoriatic scale. Biochim Biophys Acta. 1993;1182(2):147-151. doi:10.1016/0005-2760(93)90204-5