Cocamide diethanolamine (cocamide DEA) is a chemically-modified form of coconut oil, sometimes used as a thickener or foaming agent in a number of products. It has also been listed by the state of California as a known carcinogen, meaning manufacturers are required to include a warning on the label. But recent tests found 98 shampoos, soaps, and other personal care products, that contain the chemical but don’t have any warning.