Unraveling the real pigment composition of tattoo inks: the case of bi-components phthalocyanine based greens

Uncovering the real content of tattoo inks is becoming of primary importance, due to the growing extent of tattooing practice. Prior to any consideration on possible toxicity of pigments or of other ink components (generally indicated as vehicle) it is vital to assess whether the inks composition matches the corresponding safety sheets. This is even more important, in consideration of the rising sensitivity of control institutions which are issuing tattoo inks regulations, albeit slowly, in some countries worldwide. In the present study, we selected and analyzed two phthalocyanine-based green tattoo inks, the Mint Green and the Lime Green by Eternal Ink, Inc., each containing a second pigment, either white or yellowish, respectively, along with green one. Investigations were carried out both on the inks and on the reference pigments with multiple techniques, i.e. UV-Vis, FT-IR, Raman spectroscopy, and SEM-EDX analysis. We found several difformities between data sheets and actual pigments content, the main one being the presence of green pigment PG7 (hexadecachloro copper phthalocyanine), which is restricted in Switzerland and Germany, instead of the declared green pigment PG36 (hexabromo decachloro copper phthalocyanine). Two bottles of Lime Green were analyzed, each reporting a different yellow additional pigment on the bottle outer label, i.e. a diazo compound routinely labeled as PY74 and a monoazo compound, usually labeled PY14, both permitted. According to the safety sheet, Lime Greens should contain PY74, but in both cases we found PY14, instead. Finally, Mint Green is lightened with TiO2, but there was the additional presence of Al and Si which was not mentioned in the safety sheet.