Description

Cocamidopropyl betaine is a synthetic chemical derived from coconut oil used in many personal care products. The chemical is used to create thicker and foamier textured products. However, there are some concerns about toxic impurities in Cocamidopropyl betaine that make it a skin irritant to some people. Products with Cocamidopropyl betaine should be used with caution.

Synthesis method

Cocamidopropyl betaine is prepared by reacting coconut fatty acids (obtained from coconut oil) with dimethylaminopropylamine, yielding cocamidopropyl dimethylamine, which is subsequently allowed to react with sodium monochloroacetate to give the end product cocamidopropyl betaine. It carries both an anionic group (the carboxylic acid moiety) and a cationic center (the quaternary ammonium moiety). Consequently, it has properties of both anionic and cationic surfactants. The lipophilic tail is formed by coconut fatty acids, a mixture of fatty acids with chain lengths varying between C-8 and C-18. Cocamidopropyl betaine is, therefore, a mixture of several compounds with the same basic structure but with differing lipophilic tails of the reactants and intermediates involved in its synthesis, a significant impurity being dimethylaminopropylamine[1].

Allergen research

Cocamidopropyl betaine may cause allergic reactions and skin sensitivity and has been suspected to be a possible environmental toxin. The chemical is subject to impurities created during its manufacturing process that can cause adverse skin reactions.

Irritant reactions to at least one of the test substances were seen in 39% of the 1092 patients tested. Fifteen (1.3%) patients showed allergic reactions: 13 to Cocamidopropyl dimethylamine, 11 to dimethylaminopropylamine, 8 to oleamidopropyl dimethylamine, and 2 to Cocamidopropyl betaine. Concomitant reactions to Cocamidopropyl dimethylamine, dimethylaminopropylamine, and oleamidopropyl dimethylamine were common. Ten of the 15 patients were diagnosed with occupational allergic contact dermatitis caused by Cocamidopropyl betaine-related compounds[2]. The sources of occupational exposure included hair care products, hair colors, perm wave solutions, and liquid soaps. Multiple contact allergies and exposure to several irritant factors were common, and all patients had hand eczema. Hence, Cocamidopropyl betaine itself is probably not an allergen. Occupational allergic contact dermatitis caused by Cocamidopropyl betaine-related compounds is relatively rare and, unlike non-occupational Cocamidopropyl betaine-related allergy, typically manifests as hand dermatitis.

Side effects

Cocamidopropyl betaine may cause side effects such as:

Contact dermatitis

Eye irritation, such as itching and pain

Side effects may be worsened during pregnancy. Additionally, the likelihood of being exposed to impurities that arise during Cocamidopropyl betaine’s production is probable.

References

[1] Anton C. de Groot, J. Willem Weyland, Henk B. van der Walle. “Contact allergy to cocamidopropyl betaine.” Contact Dermatitis 33 6 (1995): 419–422.

[2] Katri Suuronen, Kristiina Aalto-Korte, Maria Pesonen. “Occupational contact allergy to cocamidopropyl betaine and its impurities.” Contact Dermatitis 66 5 (2012): 286–292.