The jury is still out on the safety of this. What is it?  Well, it's an ingredient in a lot of hair colors.  There is some indication that it can cause liver tumors.  It's a coal-tar based dye.  However, it has been linked to various cancers.  It's prohibited in the use of cosmetics even though it's still allowed in hair colors.  And according to skindeep.com, there is a growing body of evidence that this is not a safe thing to be applying to ourselves.