Triethanolamine

Triethanolamine,C6H15NO3, also known as TEA, may be a foreign chemical to many people. However, it is commonly used in cosmetics such as mascara, foundation, facial cleansers, and body wash. With both the properties of amines and alcohols, it is used in many industries as a buffer, conductor, or a surfactant. Hence the common use in cosmetics and its potential toxicity, there is an ongoing debate in whether triethanolamine should be prohibited from products of personal care or not.

Properties
Triethanolamine is colorless liquid with ammoniacal odor. It has the characteristic of viscosity, the ability to resist flowing, of 590.5 cP at 25°C in which is roughly 685 times greater than water. It has a higher density than water and is miscible, able dissolve in both cold and hot water, methanol, acetone, and diethyl ether. The melting point of triethanolamine is 21.6°C and the boiling point is 335.4°C. It is a basic compound with a pH of 10.5.

Because triethanolamine combines the properties of amines and alcohols, it exhibits the unique capability of undergoing reactions common to both groups. As an amine, triethanolamine is mildly alkaline and reacts with acids to form salts or soaps. As an alcohol, it is hygroscopic and can be esterfied. This unique property of hygroscopy, the ability to attract and hold water molecules, is one of the reasons why a lot of cosmetics contain triethanolamine.

Synthesis
The process of manufacturing triethanolamine includes several steps. First step of synthesizing triethanolamine is continuously bringing ammonia into contact with ethylene oxide under conditions allowing the formation of a reaction mixture comprising mono-, di- and triethanolamines. Next, continuously separating the ammonia that has not reacted from the reaction mixture while continuously separating triethanolamine from the mixture.

The process is characterized in a specific mixture of alkanolamines, comprising triethanolamine and from 0.5 to 50% by weight of at least one secondary dialkanolamine. It is prepared or isolated from the mixture, and in that triethanolamine is separated and isolated with a degree of purity equal to or greater than 99.2% by weight, by a continuous distillation of the specific mixture of alkanolamines. The improved present method of synthesis relates to a colorless triethanolamine having a high purity, that can be obtained by the process according to the invention which especially has a high resistance to coloration.

Uses
One common use of triethanolamine is in cosmetics, makeup products, such as eyeliners, mascara, eye shadows, blushers, make-up bases, foundations, hair dyes, shaving products, sunscreens, etc. Triethanolamine is used as an agent that reduces surface tension in emulsions. This allows the water-soluble and oil-soluble ingredients in a formula to blend better. Its strong basicity makes it useful in adjusting the pH of a cosmetic formula.

With the various properties, triethanolamine has a broad usage in industrial use. Triethanolamine inhibits corrosion, degreases metal, and as noted earlier, pH regulation agent. It is also used in manufacturing of plywood and paperboard as a buffer, printed circuit board as a conductor, pulp and paper as a surfactant, surface active agent.

Toxicity
Many consumers, concerned about the toxicity of triethanolamine, opinionize that it should be prohibited from its use in cosmetics. They believe that triethanolamine shows some carcinogenic potential in animal tests, and can react with other cosmetic ingredients to form nitrosamines, which are also known as carcinogens. Chris Kresser points out that even though manufacturers are advised to not use triethanolamine compounds in conjunction with other reactants that can form nitrosamines, the regulation of cosmetics is loose; according to the Cosmetic Ingredient Review panel, 89% of the 10,500 ingredients used in personal care products have not been evaluated for safety.

Thomson Reuters reported on the safety assessment of triethanolamine, diethanolamine, and monoehanolamine. According to the report, triethanolamine was practically nontoxic to slightly toxic in oral ingestion; long-term oral ingestion of the ethanolamines produced lesions, abnormal damage or change in the tissue of an organism, to the liver and kidney. It also showed little potential in skin irritation tests. The clinical skin testing showed mild skin irritation in concentrations above 5%. Triethanolamine did not cause DNA-damage inducible repair in an unscheduled DNA synthesis test. It was neither found to have carcinogenic, causing cancer, or cocarcinogenic, potentiating cancer, activity when dermally applied to mice for 18 months.

Although studies have shown that triethanolamine is nontoxic, the issue seems to be ongoing due to the loose regulation on cosmetics.

Video
Demonstration of the viscous property of triethanolamine. yuMsPCUMQvU