Chemical purity and toxicology of pigments used in tattoo inks

The safety of tattoo inks has obviously increased in Europe since the existence of European Union Resolution ResAP(2008)1, which resulted in the improved quality control of pigment raw materials due to the definition of impurity limits that manufacturers can refer to. High-performance pigments are mostly used in tattoo inks, and these pigments are supposed to be chemically inert and offer high light fastness and low migration in solvents. However, these pigments were not developed or produced for applications involving long-term stay in the dermis or contact with bodily fluids. Therefore, these pigments often do not comply with the purity limits of the resolution; however, it is required that every distributed tattoo ink does not contain aromatic amines and not exceed the limits of heavy metals or polycyclic aromatic hydrocarbons. Current toxicity studies of pigments underline that no ecotoxicological threat to human health or to the environment should be expected. However, the pigment as well as its impurities and coating materials must be considered. In order to evaluate the safety of pigments according to their impurities, two different validated sample preparation methods are necessary: (1) simulation of their long-term stay in the bodily fluid of the dermis and (2) simulation of cleavage due to laser removal or ultraviolet exposure. The development of standardized, validated and well-adapted methods for this application has to be part of prospective efforts. Concerning legislation, it might be appropriate that the first regulative approaches be based on those of cosmetics.