Background: During the last decade, the number of people with ≥1 tattoo has increased noticeably within the European population. Despite this, limited safety information is available for tattoo inks. Objectives: To test the skin sensitization potential of 5 tattoo inks in vitro by using reconstructed human skin (RHS) and the contact sensitization biomarker interleukin (IL)-18. Methods: Two red and 3 black tattoo inks, 1 additive (Hamamelis virginiana extract) and 1 irritant control (lactic acid) were tested. The culture medium of RHS (reconstructed epidermis on a fibroblast-populated collagen hydrogel) was supplemented with test substances in a dose-dependent manner for 24 hours, after which cytotoxicity (histology; thiazolyl blue tetrazolium bromide assay) and skin sensitization potential (IL-18 secretion; enzyme-linked immunosorbent assay) were assessed. Results: All but 1 ink showed cytotoxicity. Notably, 1 red ink and 1 black ink were able to cause an inflammatory response, indicated by substantial release of IL-18, suggesting that these inks may be contact sensitizers. Conclusions: The in vitro RHS model showed that 4 tattoo inks were cytotoxic and 2 were able to cause an inflammatory IL-18 response, indicating that an individual may develop allergic contact dermatitis when exposed to these tattoo inks, as they contain contact sensitizers.
Bil, W., van der Bent, S. A. S., Spiekstra, S. W., Nazmi, K., Rustemeyer, T., & Gibbs, S. (2018). Comparison of the skin sensitization potential of 3 red and 2 black tattoo inks using interleukin-18 as a biomarker in a reconstructed human skin model. Contact Dermatitis, 79(6), 336-345. https://doi.org/10.1111/cod.13092