Cocamide DEA, Lauramide DEA, Linoleamide DEA and Oleamide DEA are all fatty acids derivatives that are used in the formulation of shampoos, shower gels and other soaps, hair color, lotions, skin creams and other personal care and cosmetic products.
DEAs are used to create, increase, and stabilize foam (for soaps, shampoos, etc) and its also used as an emulsifier in other products.
One of the concerns with DEA is that they can be mild to moderate skin and eye irritants. Though its not classified as a carcinogen by the Environmental Production Agency (EPA), it has been reported by the National Toxicology Program (NTP) an increase liver and kidney tumors in mice from dermal exposure to DEA.
This common ingredient is banned in Europe.
More info on DEA:
Chemical Exposures: Will DEA Findings Wash?
Cynthia Washam
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1665417 Mentions potential fetal neural abnormalities in humans and also controversy on the matter on whether DEA is indeed harmful or safe.
Food and Chemical Toxicology – Abstract
ScienceDiet.com