Tests ordered by an environmental watchdog group revealed the presence of a cancer-causing chemical in dozens of personal care products that lack a warning label required by California law.
The compound, a chemically modified form of coconut oil—cocamide diethanolamine (cocamide DEA)—is used as a foaming agent or thickener in soaps, shampoos, conditioners, and similar products.
http://health.yahoo.net/articles/beauty/cancer-causing-chemical-found-98-shampoos-and-soaps