Triethanolamine (TEA) is widely used as an ingredient in cosmetic products, household cleaning products, textiles, herbicides, and pharmaceutical ointments. The most widespread human exposure to TEA occurs in cosmetics where it is used in combination with fatty acids as an emulsifying agent and also as a thickening agent, fragrance ingredient, and pH adjuster. The TEA was reported to be used in cosmetic creams and lotions at a concentration between 1% and 2% (1). In 1983, the Cosmetic Ingredient Review (CIR) Expert Panel concluded that the use of TEA was safe in cosmetic rinse-off formulations, and should not exceed a concentration of 5% in leave-on products (2). Acute toxicity studies in animals demonstrated that prolonged or repeated exposure to TEA can cause severe skin irritation or impairment of vision (3). Chronic application of high dermal doses of TEA can lead to systemic toxicity (3). The National Toxicology Program (NTP) examined TEA carcinogenicity by the dermal route because of its widespread use and because of the potential for its conversion to N-nitrosodiethanolamine. The NTP concluded in 1999 that its preliminary ﬁndings of liver carcinogenicity in mice were invalid because of the presence of a Helicobacter hepaticus infection that complicated the interpretation of the study (4).