Is Cocamidopropyl Betaine Safe?

What is cocamidopropyl betaine

Cocamidopropyl betaine is a surfactant used in shampoos, toothpastes, body washes, hand soap and other cleaning products. It's used for its cleaning and lathering properties and is a zwitterionic ammonium compound. Derived from coconut oil and dimethylaminopropylamine, it's marketed as a "natural" cleanser. 

What are its risks?

The biggest problem that cocamidopropyl betaine has is that its processing aids, amidoamine and 3-dimethylaminopropylamine, can remain in the product.  These chemicals can cause contact dermatitis, eye irritation, and other allergic reactions.  In fact, the rate of allergic reactions to these impurities is so high that the American Contact Dermatitis Society named  cocamidopropyl betaine Allergen of the Year in 2004.  Source

Despite its high potential for allergic reactions, it's used in popular "hypoallergenic" products marketed to children and infants. Source

Because these chemicals are amines, they can, under certain conditions, create carcinogenic nitrosamines.  These nitrosamines not only can be found in products, but can also form downstream, contaminating waste water with these carcinogens. However, to be fair, these nitrosamines are only formed when the product is heated to above 350 degrees, or when the pH is moderately acidic (3.5 or lower).  Source Source

Some supplies of CAPB may contain propylene glycol as a solvent, which may not be disclosed on a product label. Source