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Tattoo ink composition
Although people have decorated their bodies for millennia for ceremonial and religious reasons, many people today adorn themselves with images tattooed onto their skin as a form of self-expression.
And, from realistic faces to elaborate nature scenes, tattoos eventually became an art form.
However, even though this is a global movement, the inks used to make tattoos are not even regulated in most countries, resulting in products whose components are largely a mystery.
Seeking to unravel this mystery, scientists analyzed nearly 100 tattoo inks sold in the US and found that even when these products include a label listing their ingredients, those listings are often not accurate. The team also detected small particles in the inks that could be harmful to cells.
Finally, the team interviewed well-known tattoo artists to see what they knew about the inks they used on their clients. Artists quickly identified a brand they liked, but didn’t know much about the contents of their favorite paint.
“Surprisingly, no dye company produces specific pigments for tattoo ink,” said Professor John Swierk of the University of Binghamton (UK). “Big companies make pigments for everything, like inks and fabrics. These same pigments are used in tattoo inks.”
Another curious factor is that tattoo artists need to obtain licenses in the places where they operate, including for health safety reasons, but, at least in the US, where the research was carried out, no federal or local agency regulates the contents of the inks themselves.
How tattoo inks are made
Tattoo inks contain two parts: A pigment and a carrier solution. The pigment can be a molecular compound, such as a blue pigment; a solid compound, such as titanium dioxide, which is white; or a combination of the two types of compounds, such as light blue ink, which contains molecular blue pigment and titanium dioxide.
The carrier solution carries the pigment to the middle layer of the skin and normally helps to make the pigment more soluble. It can also control the viscosity of the paint and sometimes includes an anti-inflammatory ingredient.
The team investigated the particle size and molecular composition of tattoo pigments using a variety of techniques such as Raman spectroscopy, nuclear magnetic resonance spectroscopy and electron microscopy.
In 16 inks analyzed in detail, about half contained particles smaller than 100 nm, which classifies them as nanoparticles. “That’s a worrying size range,” says Swierk. “Parts of this size can cross the cell membrane and potentially cause damage.”
Carcinogen and nanoparticles
The researchers also 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 that it was present in the ink. The team was also able to identify which specific pigments are present in some paints.
“Every time we looked at one of the paints, we found something that made us stop,” said Swierk. “For example, 23 of 56 different inks analyzed to date suggest that an azo-containing dye is present.”
While many azo pigments do not cause health problems when chemically intact, bacteria or ultraviolet light can degrade them into another nitrogen-based compound, which is a potential carcinogen.
Article: What’s in my ink: the analysis of tattoo ink composition
Authors: Kelli Moseman, Presenter; John Swierk
Publication: Proceedings of the ACS Fall 2022
#ingredients #tattoo #inks