What is in tattoo ink?

Image source: hindustantimes.com

From life-like faces to elaborate nature scenes, tattoos are a true art form. Although people have decorated 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 several parts of the world resulting in products whose components are largely a mystery. Now, researchers have analyzed almost 100 inks and report that even when these products include an ingredient label, the lists often aren't accurate. The team also detected small particles that could be harmful to cells.

Big companies manufacture pigments for everything, such as paint and textiles. These same pigments are used in tattoo inks.

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 the two compound types such as light blue ink, which contains both the molecular blue pigment and titanium dioxide. The carrier solution transports the pigment to the middle layer of skin and typically helps make the pigment more soluble. It can also control the viscosity of the ink solution and sometimes includes an anti-inflammatory ingredient.

Researchers have been investigating 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. From these analyses, they have confirmed the presence of ingredients that aren't listed on some labels. For example, in one case ethanol was not listed, but the chemical analysis showed it was present in the ink. The team has also been able to identify what specific pigments are present in some inks.

23 of 56 different inks analyzed to date suggest an azo-containing dye is present. Although many azo pigments do not cause health concerns when they are chemically intact, bacteria or UV light can degrade them into another nitrogen-based compound that is a potential carcinogen, according to the Joint Research Centre, which provides independent scientific advice to the European Union.

In addition, the team has analyzed 16 inks using electron microscopy, and about half contained particles smaller than 100 nm. "That's a concerning size range" say researchers. "Particles of this size can get through the cell membrane and potentially cause harm."

After the researchers run a few more tests and have the data peer reviewed, they will add the information to their website "What's in My Ink?" With these data, they want consumers and artists to make informed decisions and understand how accurate the provided information is.

What's in my ink: the analysis of tattoo ink composition, ACS Fall 2022. www.acs.org/content/acs/en/mee … tings/fall-2022.html