An increasing presence of organic pigments has been observed in the ink used in American tattoos, with the identification of allergenic pigments in symptomatic patients often challenging. Investigators identified 44 pigments that were composed of organic dyes and a few inorganic metallic oxides and carbon, according to the results of a recent study published in the Journal of the American Academy of Dermatology.

The researchers sought to explore the listed contents of tattoo inks that are sold and manufactured by wholesalers in the United States and summarize reports of allergic contact dermatitis to identified pigments.

Historically, tattoo inks contained metallic pigments with the potential to induce allergic contact dermatitis. Data on the current use of these pigments in tattoo ink are sparse. The investigators conducted an internet search with the use of specific keywords, in which pigment information listed in tattoo product inserts was collected and assessed. The searches were performed on June 7 and June 8, 2018, by the primary study investigator.

A total of 1416 unique inks were evaluated. Overall, the average bottle of ink included 3 pigments. There were a total of 44 distinct pigments identified, with 10 of them containing inorganic metallic pigments such as iron, barium, copper, zinc, titanium, and molybdenum. These metals occurred as iron oxide, barium sulfide, zinc ferrite, and titanium dioxide, whereas copper and molybdenum were complexed with organic phthalocyanine rings or xanthene rings, respectively.

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The remaining 34 organic pigments contained carbon (3 were black pigments made exclusively from carbon), diketopyrrolopyrrole, azo, quinacridone, dioxazine, anthraquinone, or quinophthalone dyes. The organic dyes contained all of the orange pigments, as well as a majority of the red, yellow, and violet pigments.

Based on a literature search, 25% (11 of 44) of the distinct pigments identified were suspected of causing contact dermatitis. Of these, 11 pigments were thought to cause allergic contact dermatitis, with 5 of these confirmed by patch testing.

The researchers concluded that the findings from this study underscore the diversity of pigments that are currently used in tattoos in the United States. They demonstrate that relatively few inks comprise the metallic pigments to which allergic contact dermatitis has traditionally been ascribed. Clinicians who use the patch test should be made aware of these new pigments.

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Reference

Liszewski W, Warshaw EM. Pigments in American tattoo inks and their propensity to elicit allergic contact dermatitis [published online February 4, 2019]. J Am Acad Dermatol. doi: 10.1016/j.jaad.2019.01.078.