10 Tetrasodium EDTA: is a preservative that’s made from the known carcinogen, formaldehyde and sodium cyanide. It is also a penetration enhancer, meaning it breaks down the skin's protective barrier, going right into your bloodstream. Used mainly in soaps and creams, many companies try to be "natural" using Tetrasodium EDTA instead of parabens to preserve their products, but it is toxic.