Tattooing entails a high amount of tattoo colorants that is injected into skin. Tattoo colorants usually contain various substances of which the colouring component is the major ingredient that can be assigned to two different groups. Firstly, amorphous carbon particles (carbon black) are almost exclusively found in black tattoos. Secondly, tattooists use azo and polycyclic pigments to create nearly all colours of the visible spectrum. Due to their different but frequently complex chemistry, tattoo colorants usually contain various compounds like by-products and impurities which may exhibit health concerns. Professional tattooists inject that mixture into skin using the solid needles of tattoo machines. It is known that part of injected tattoo colorants is predominantly transported away from skin via lymphatic system. In addition to tattooing, exposure of tattooed skin to solar radiation or laser light may cause decomposition of pigment molecules leading to new and potential hazard chemical compounds. In light of the various hazard substances in the tattoo colorants and its decomposition products, tattooing might pose a health risk not only to skin but also to other organs of humans.