Compendium of the most significant studies with reference to properties, intake, effects.

Belsito, M., Hill, R. A., Klaassen, C. D., Liebler, D., Marks Jr, J. G., & Ronald, C. (2012). On the Safety Assessment of Ethanolamides as Used in Cosmetics. Final Amended Report.

Abstract. The CIR Expert Panel re-reviewed the safety of isostearamide, myristamide, and stearamide MEA as used in cosmetics, and included 25 additional ethanolamides that are secondary carboxamides comprised of the amidation products of alkyl carboxylic acids and ethanolamine, concluding that these ingredients are safe in the present practices of use and concentration when formulated to be non-irritating, and that these ingredients should not be used in cosmetic products in which N-nitroso compounds may be formed. Most of the ethanolamides are reported to function in cosmetics as hair conditioning agents, skin conditioning agents, and surfactant – foam boosters; a few are reported to have other uses. The Panel reviewed available animal and clinical data, as well as information from previous CIR reports.

Martiryan, A. I., Shahinyan, G. A., & Vardapetyan, V. V. (2022). Antiradical activity, base-catalyzed hydrolysis and partition coefficients of some surfactants. Colloid and Interface Science Communications, 50, 100653.

Abstract. Antiradical activity and some environmental characteristics such as biodegradability and bioavailability of several coconut oil derived surfactants have been studied by photometry and UV–Vis absorption spectroscopy. The effects of polar group size and type were revealed using non-ionic surfactants cocamide monoethanolamine, cocamide diethanolamine, amphoteric surfactant cocamidopropyl betaine, and anionic surfactants sodium lauryl sulfate and sodium alfa olefin sulfonate. Free radical scavenging properties were examined by determination of rate constant of the reaction with hydroxyl radicals. To calculate the rate constant the competitive reaction between hydroxyl radicals and p-nitroso-N,N-dimethyl aniline was investigated. The results show pronounced antioxidant activity of surfactants. To confirm the environmentally friendly character of mentioned surfactants the biodegradability and accumulation were studied using base-catalyzed hydrolysis and partition coefficient between n-octanol/water layers. The obtained results show that type of head group and the carbon chain structure have major effect on these properties.

Mertens S, Gilissen L, Goossens A. Allergic contact dermatitis caused by cocamide diethanolamine. Contact Dermatitis. 2016 Jul;75(1):20-4. doi: 10.1111/cod.12580. Epub 2016 May 3. PMID: 27144883.

Hoeman KW, Culbertson CT. A novel, environmentally friendly sodium lauryl ether sulfate-, cocamidopropyl betaine-, cocamide monoethanolamine-containing buffer for MEKC on microfluidic devices. Electrophoresis. 2008 Dec;29(24):4900-5. doi: 10.1002/elps.200800463.

Abstract. A new buffer has been developed for fast, high-efficiency separations of amino acids by MEKC. This buffer was more environmentally friendly than the most commonly used surfactant-containing buffers for MEKC separations. It used a commercially available dishwashing soap by Seventh Generation (Burlington, VT, USA), which contained three micelle-forming agents. The mixed micelles were composed of sodium lauryl ether sulfate (anionic), cocamidopropyl betaine (zwitterionic), and cocamide monoethanolamine (non-ionic). The optimized buffer contained 5.0% w/w Seventh Generation Free & Clear dishwashing soap, 10 mM sodium borate, and was completely void of organics. The lack of organics and the biodegradability of the surfactant molecules made this buffer more environmentally friendly than typical SDS-containing buffers. This new buffer also had a different selectivity and provided faster separations with higher separation efficiencies than SDS-based buffers. Fast separations of BODIPY FL labeled amino acids yielded peaks with separation efficiencies greater than 100,000 in less than 20 s.

Yavrukova VI, Radulova GM, Danov KD, Kralchevsky PA, Xu H, Ung YW, Petkov JT. Rheology of mixed solutions of sulfonated methyl esters and betaine in relation to the growth of giant micelles and shampoo applications. Adv Colloid Interface Sci. 2020 Jan;275:102062. doi: 10.1016/j.cis.2019.102062.

Forsby A, Norman KG, El Andaloussi-Lilja J, Lundqvist J, Walczak V, Curren R, Martin K, Tierney NK. Using novel in vitro NociOcular assay based on TRPV1 channel activation for prediction of eye sting potential of baby shampoos. Toxicol Sci. 2012 Oct;129(2):325-31. doi: 10.1093/toxsci/kfs198.

Abstract  The transient receptor potential vanilloid type 1 (TRPV1) channel is one of the most well-characterized pain-inducing receptors. The purpose of this study was to predict human eye stinging of 19 baby bath and shampoo formulations by studying TRPV1 activity, as measured by increase in intracellular free Ca(2+). The NociOcular test, a novel recombinant neuronal in vitro model with high expression of functional TRPV1 channels, was used to test formulations containing a variety of surfactants, preservatives, and fragrances. TRPV1-specific Ca(2+) influx was abolished when the TRPV1 channel antagonist capsazepine was applied to the cells prior to shampoo samples. The positive control, an adult shampoo that contains cocamide monoethanolamine (CMEA), a known stinging ingredient, was the most active sample tested in the NociOcular test. The negative control, a marketed baby shampoo, was negative in the NociOcular and human tests. Seven of the formulations induced stinging in the human test, and of those six were positive in the NociOcular test. Twelve formulations were classified as nonstinging in the human test, and of those ten were negative in the NociOcular test. There was no correlation between the clinical stinging results for the baby formulations and the data generated from other in vitro eye irritation assays (cytosensor microphysiometer, neutral red uptake, EpiOcular, transepithelial permeability). Our data support that the TRPV1 channel is a principal mediator of eye-stinging sensation induced by baby bath and shampoo formulations and that the NociOcular test may be a valuable in vitro tool to predict human eye-stinging sensation.

Wu HY, Shih CL, Lee T, Chen TY, Lin LC, Lin KY, Chang HC, Chuang IC, Liou SY, Liao PC. Development and validation of an analytical procedure for quantitation of surfactants in dishwashing detergents using ultra-performance liquid chromatography-mass spectrometry. Talanta. 2019 Mar 1;194:778-785. doi: 10.1016/j.talanta.2018.10.084.

Diethanolamine | FDA