Tattoo pigments in skin: determination and quantitative extraction of red tattoo pigments (2008)

The number of tattooed individuals increased significantly, especially among youth. In the United States, up to 24% of the population has tattoos, whereas in European countries like Germany about 9% and the United Kingdom about 12% are tattooed. Today frequently azo pigments are used for tattooing. These azo pigments are manufactured primarily for other purposes like printing, painting cars and coloring various consumer products. To estimate the risk of any health problems of tattooing, the colorant concentration in the skin and the human body after tattooing of the colorants must be determined. This has not been performed so far and was now firstly investigated by our research group. Therefore, an extraction method was established to determine the concentration of tattoo pigments and decomposition products quantitatively. The extraction of two widely used azo compounds, Pigment Red 22 (PR 22) and Rigment Red 9 (PR 9) and their laser induced decomposition were accomplished using recovery experiments and HPLC-DAD technology. For the pigments a nearly complete recovery was achieved from lysed skin (> 94%). The decomposition products were extracted from skin showing a recovery of up to 100%, except for one very volatile decomposition product. Based on this extraction procedure we could determine the amount of tattoo pigment punctured into skin. We tattooed excised pigskin and human skin with Pigment Red 22 under various conditions (concentration of the suspension, needle size and needle shape). After tattooing, we quantitatively extracted the pigment in order to determine the pigment concentration in skin (mean value 2.53 mg/cm²). Since PR 22 is cleaved by laser light into toxic or even carcinogenic compounds we investigated the influence of UVB radiation and natural sun light on PR 22. PR 22 was dissolved in different solvents. The solutions were irradiated with either UVB-radiation or with natural sunlight. An evident cleavage of the pigment was detected in all solvents, when exposed to UVB radiation or natural sunlight. To investigate transportation of tattoo pigments inside the body after tattooing, we established an animal model using SKH-1 hairless mice. The mice received tattoos with PR 22 on their back. The extraction of pigments immediately after tattooing yielded the concentration of PR 22 of 1.76 mg/cm2 that is placed in the body. In contrast to that, the extraction of PR 22 from skin 42 days after tattooing elucidates the extent of pigment transportation in the mice. Only 72 % of PR 22 remain inside the dermis. To investigate the decomposition of pigments by solar light, tattooed living mice were exposed to solar light for 31 days. We found that up to 60% of the pigment is cleaved. Ex vivo laser treatment of tattooed mouse skin showed that up to 50% of PR 22 located inside the mouse skin can be cleaved by laser light. For the first time we could quantitatively analyze real existing tattoos in human skin tissue. The extraction of a tattoo revealed PR 22 and PR 170 to be the red tattoo pigments used by the artist. Several years after tattooing the concentration of PR 22 inside the skin is 0.11 mg/cm2. The last chapter deals with an interesting additional problem of azo dyes. We describe a case report of a patient with a periungual basal cell carcinoma at the thumb. The specific feature of the reported case is the frequent exposure to fishing baits that he had stained with an unknown colorant. The use of chromatography, mass spectrometry and infrared spectroscopy revealed the colorant as the 1:2 chromium complex azo pigment Solvent Red 8.