Black tattoo inks are a source of problematic substances such as dibutyl phthalate

Tattooing has recently become increasingly popular. Using tiny needles, tattooists place the tattoo ink in the dermis along with numerous unknown ingredients. Most tattoos consist of black inks, which are predominantly composed of soot products (carbon black with polycyclic aromatic hydrocarbons).

Black tattoos cause skin problems, including allergic reactions, but the responsible substance frequently remains unknown.

We applied gas chromatograph-mass spectrometry analysis to search for hazardous compounds in 14 different commercially available black tattoo ink samples.

The analysis revealed that all inks contained the softener substance dibutyl phthalate (0.12-691.2 µg/g). Some of the inks contained hexachloro-1,3-butadiene (0.08-4.52 µg/g), metheneamine (0.08-21.64 µg/g), dibenzofuran (0.02-1.62 µg/g), benzophenone (0.26-556.66 µg/g), and 9-fluorenone (0.04-3.04 µg/g).

The sensitizing agent dibutyl phthalate acts directly on keratinocytes and can drive Th2 responses following skin exposure via induction of thymic stromal lymphopoietin gene expression. Hexachloro-1,3-butadiene is genotoxic in vitro and 9-fluorenone is cytotoxic, generating reactive oxygen species under light exposure. The substances found in the inks might be partially responsible for adverse skin reactions to tattoos.