From realistic faces to elaborate nature scenes, tattoos are a true art form. Although people have been decorating their bodies for millennia for ceremonial and religious reasons, many people today adorn themselves with these images as a form of self-expression. But the inks used for tattoos are unregulated in the United States, resulting in products whose components are largely a mystery. Now researchers have analyzed nearly 100 inks and report that even when these products include an ingredient label, the listings are often not accurate. The team also detected small particles that could be harmful to cells.
The researchers will present their results today at the fall meeting of the American Chemical Society (ACS).
“The idea for this project came about because I was interested in what happens when laser light is used to remove tattoos,” says John Swierk, Ph.D., the project’s principal investigator. “But then I realized that very little was known about the composition of tattoo inks, so we started analyzing popular brands.”
Swierk and undergraduate students in his lab interviewed tattoo artists to see what they knew about the inks they use on their clients. Artists could quickly identify a brand they liked best, but they didn’t know much about its content. “Surprisingly, no dye shop makes a specific pigment for tattoo ink,” says Swierk. “Big companies make pigments for everything, like paint and textiles. Those same pigments are used in tattoo inks.” He also notes that tattoo artists must be licensed in the localities where they operate for safety reasons, but no federal or local agency regulates the content of the inks themselves.
Tattoo inks contain two parts: a pigment and a carrier solution. The pigment could be a molecular compound such as a blue pigment; a solid compound such as titanium dioxide, which is white; or a combination of both types of compounds such as light blue ink, which contains both molecular blue pigment and titanium dioxide. The carrier solution transports the pigment to the middle layer of the skin and generally helps to make the pigment more soluble. It can also control the viscosity of the ink solution and sometimes includes an anti-inflammatory ingredient.
Swierk’s team at the University of Binghamton (State University of New York) studied the particle size and molecular composition of tattoo pigments using various techniques, such as Raman spectroscopy, spectroscopy by nuclear magnetic resonance and electron microscopy. From these analyses, they confirmed the presence of ingredients that are not listed on some labels. For example, in one case, ethanol was not listed, but chemical analysis showed it was present in the ink. The team was also able to identify specific pigments present in certain inks.
“Every time we looked at one of the inks, we found something that made me think,” says Swierk. “For example, 23 of 56 different inks analyzed to date suggest that an azo-containing dye is present.” Although many azo pigments do not cause health problems when chemically intact, bacteria or ultraviolet light can degrade them into another potentially carcinogenic nitrogen-based compound, according to the Joint Research Center, which provides independent scientific advice to the European Union. .
Additionally, the team analyzed 16 inks using electron microscopy, and about half contained particles smaller than 100 nm. “It’s a concerning size range,” says Swierk. “Particles of this size can cross the cell membrane and potentially cause damage.”
After the researchers have run a few more tests and the data has been peer-reviewed, they will add the information to their “What’s in My Ink?” website. “With this data, we want consumers and artists to make informed decisions and understand how accurate the information provided is,” says Swierk.
The researchers acknowledge support and funding from Binghamton University (State University of New York).
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