MONOETHANOLAMINE (MEA)
TYPE OF INGREDIENT
pH adjuster/buffering agent, emulsifying agent, surfactant
COMMONLY FOUND IN
Rinse-off hair coloring, hair curling and hair care products
WHAT ARE THE BENEFITS OF MONOETHANOLAMINE (MEA)?
Monoethanolamine (MEA) functions as a pH stabilizer, emulsification agent and surfactant. All cosmetic uses of MEA are in rinse-off hair products. MEA has a highly alkaline pH that is helpful to maintain the stability and efficacy of oxidative hair coloring products.
MEA also functions as an emulsifier to blend water and oil components. Salts of MEA are used as surfactants to aid in cleansing and/or shampooing.
MEA is more commonly used outside of dermatology as a rust inhibitor in water-based metal working fluids. In this industry, MEA is beneficial due to its emulsifying properties and ability to protect against corrosion.
WHAT ARE MONOETHANOLAMINE (MEA)?
Monoethanolamine (MEA) is a short chain alkanolamine formed by aminating ethylene oxide with ammonia. MEA is the most alkaline of the ethanolamine family, which also contains triethanolomaine (TEA) and diethanolamine (DEA). The highly alkaline pH of MEA makes it effective in specific applications, such as hair dyes and perms, where it helps to open the hair cuticle for better product penetration. A by-product of DEA is nitrosamine, a known carcinogen, which is why DEA is prohibited from use in cosmetic products. Additionally, MEA and TEA must be 99% pure, with a maximum of 0.5% traces of secondary alkanolamines such as DEA.
ARE MONOETHANOLAMINE (MEA) SAFE FOR ALL SKIN TYPES AND TONES?
The Cosmetic Ingredient Review (CIR) Expert Panel states that MEA is safe for only discontinuous, brief use, followed by thorough rinsing from the surface of the skin. High concentrations of MEA can be irritating to the skin. There have been reports of allergic and irritant contact dermatitis to MEA-containing hair dyes and products. Additionally, MEA has been recognized as a notable allergen in metal workers continuously exposed to water-based metalworking fluids.
CONTRAINDICATIONS
As stated above, products containing MEA must always be rinsed off and should be avoided in anyone with a known allergy to MEA.
Sources:
Lessmann H, Uter W, Schnuch A, Geier J (2009). Skin sensitizing properties of the ethanolamines mono-, di-, and triethanolamine. Data analysis of a multicentre surveillance network (IVDK*) and review of the literature. Contact Dermatitis 60: 243–255
Fiume MM, Heldreth BA, Bergfeld WF, Belsito DV, Hill RA, Klaassen CD, Liebler DC, Marks JG, Shank RC, Siaga TJ, Snyder PW, Andersen FA (2015). Safety Assessment of Ethanolamine and Ethanolamine Salts as Used in Cosmetics. International Journal of Toxicology 34: 84S-98S.
CIR (Cosmetic Ingredient Review). Final report on the safety assessment of triethanolamine, diethanolamine, and monoethanolamine. J Am Coll Toxicol 1983: 2: 183–235.
Seo JA, Bae IH, Jang WH, Kim JG, Bak SY, Han SH, Park YH, Lim KM (2012). Hydrogen peroxide and monoethanolamine are the key causative ingredients for hair dye-induced dermatitis and hair loss. Journal of Dermatologic Science. 66(1): 12-19.
