Para-phenylenediamine: Active ingredient in hair dyes is toxic.

Para-phenylenediamine (also tetrathydro-6-nitroquinoxaline) is commonly found in hair colouring products i.e., in almost all hair dyes.

Health Canada issues a warning August 2003 that PPD should not be used in "black henna" tattoo ink and paste since it is unsafe and should not be sold.

It is used in cosmetics, creates allergy, red skin rashes, contact dermatitis, itching, blisters, open sores, scarring and other potentially harmful effects.