Triethanolamine (TEA) is a clear, viscous liquid used to reduce the surface tension in emulsions. This allows the water-soluble and oil-soluble ingredients in a formula to blend better. It is a strong base, which makes it useful in adjusting the pH of a cosmetic formula. TEA is completely soluble in water and is rapidly biodegradable.
TEA neutralizes fatty acids and solubilizes oils and other ingredients that are not completely soluble in water. TEA combines the properties of both amines and alcohols and can undergo reactions common to both groups. As an amine, TEA reacts with acids because it is mildly alkaline, and forms soaps. When TEA acts as an alcohol it is hygroscopic and can cause the esterification of free fatty acids.
TEA can solidify or crystallize in cool temperatures because the freezing point is 70.9 °F. If your TEA is not a viscous pourable liquid when you receive it, simply give the container a warm water bath.
The FDA includes TEA on its list of indirect food additives, which means TEA may be used in adhesives in contact with food and to assist in the washing or peeling of fruits and vegetables. The safety of TEA has been assessed by the CIR Expert Panel and they concluded that TEA is safe for use in cosmetics and personal care products designed for discontinuous, brief use followed by thorough rinsing from the surface of the skin. In products intended for prolonged contact with the skin, the concentration of TEA should not exceed 5%.
TEA is lumped in with some other ingredients that have earned it the warning, “should not be used in products containing N-nitrosating agents to prevent the formation of nitrosamines.” However, because TEA is a tertiary amine, it does not react with nitrosating agents to produce nitrosamines. Using very sensitive analytical tools, a study by the Regulatory Toxicology and Pharmacology found when TEA was ingested with sodium nitrite, no significant nitrosamine formation was found. The CIR Expert Panel also recognized that TEA is a mild skin and eye irritants and irritation increased with elevated concentrations, which again is why formulations should not exceed 5%.
TEA is a good example of how animal testing, where animals are given large doses of an ingredient, does not translate accurately to human topical application. In one study by the National Toxicology Program, there was in increased occurrence of liver tumors in mice that were dosed dermally with TEA over their lifetime. However, in another study it did not cause tumors in rats treated the same or in mice that were genetically engineered to be more sensitive. It also did not damage genetic material. Research has now proven the most likely cause of tumors in the mice that formed liver tumors was due to the TEA causing a deficiency in choline. Humans are resistant to the development of choline deficiency and test animals are not. In addition, cosmetics that use TEA are not ingested, nor is it applied dermally at 100% concentrations over your lifetime.