What's in your tattoo ink might differ from what the label claims.

Over 80% of the inks analyzed in a recent investigation have been found to contain unlisted additives and pigments. John R. Swierk, the lead researcher, emphasized in a conversation with Tech Times that their deep dive into identifying the tattoo ink ingredients is intended to spark a dialogue about the need for accurate labeling to "empower artists and clients to be able to make informed choices" and take into account various allergies and health concerns.

Where does the tattoo ink go?

The machine tattoo artists use a cluster of mechanized needles that make hundreds of microscopic punctures in the skin. Each time a needle pricks the skin, it surpasses the skin's surface, the epidermis, and deposits a small amount of the tattoo ink onto the dermis, the second layer of the skin.

The immune system springs into action when tattoo ink is introduced into the body. It directs white blood cells toward the foreign object, the tattoo ink, to engulf it and subsequently eliminate it via the bloodstream. If the white blood cells were to follow through this process, then the tattoos wouldn't be permanent. Fortunately, the pigment particles in tattoo inks are too big to be eaten by the white cells, so the pigments just stick around in the dermis.

While most of a small amount of runaway ink escapes into the bloodstream, once in the blood, it can find its way to different organs in our body, like the liver or the lymph nodes.

Researchers have observed cases where the tattoo ink found in lymph nodes under the armpits can mimic the appearance of blue sentinel nodes or calcifications in axillary nodes, both of which can lead to misleading results in a mammography test carried out for breast cancer detection. Several studies have also found red tattoo inks at the center of allergic reactions in individuals.

"While there are potential concerns around some of the things that you find in tattoo inks, it's not established what is causing those problems in human health. We think it's important to study this [tattoo inks] so that when people have adverse reactions to tattoos, they have an understanding of what was in those inks that might be causing an adverse event and use that knowledge to get the right treatment," stated John. He also highlighted that the safety and health of things in tattooing is still very much an open question, at least in the US.

What's in the Ink?

Tattoo ink primarily consists of two components: the pigment and the carrier. The finely powdered pigment is dispersed in the liquid carrier that delivers it to the application site.

Historically, tattoo inks were prepared from naturally occurring materials like minerals, ground-up plants, or animal parts. One of the oldest examples of tattoos we have discovered so far belongs to Ötzi, the 5300-year-old Tyrolean iceman. Chemical analysis of the mummy revealed that the world's oldest tattoo ink was made of soot.

In the last few decades, the tattoo ink industry has seen a massive shift due to a significantly higher popularity of tattoos. This led to the market flooding with a wide range of inks ranging from usual colors to glow-in-the-dark variety.

"Pigment engineering and science has allowed companies to create much more vibrant colors that go in the skin better and seemingly had fewer health issues, but as time has gone on, new studies have found that these synthetic inks have a whole list of problems on their own," Brandon David, professional tattooer and founder of TattooSpace.com told Tech Times.

To keep up with the increasing demand for variety, manufacturers have started adopting more organic molecules commonly used as dyes in the textile, paint, and printing industries-for example, azo compounds.

The concern is less about ingredients and more about being used but not listed. 

The researchers from Birmingham University sourced 54 inks from nine brands common in the United States, both primary and small manufacturers. The inks were tested using a combination of analytical instruments- NMR spectroscopy, Raman spectroscopy, X-ray fluorescence spectroscopy, and mass spectrometry- to ensure all the ingredients, organic, inorganic, big or small, were identified.  

They found that 45 had significant discrepancies with the labeled contents and contained unlisted additives and pigments.

Over half of the samples had polyethylene glycol, an unlisted ingredient, repeated exposure to which has been linked to potential organ damage. Fifteen samples contained unlisted propylene glycol, which is "generally considered safe" but could lead to allergies for some. Other contaminants included an antibiotic often prescribed for urinary tract infections and 2-phenoxyethanol. Still, they could pose health risks like diarrhea in breastfeeding infants and add to the already rising global concern of antimicrobial resistance (AMR).

According to a 2018 study, over 20% of the US population and 12% of Europeans have at least one tattoo, which calls for stricter regulations around labeling what's in the ink. However, that is not the case. Brandon pointed out that the U.S. Food and Drug Administration (FDA) treats tattoos and tattoo ink as cosmetic products and exercises regulatory authority over the pigments used in tattooing due to a previous lack of evidence concerning safety problems.

"We don't know where the unlisted components are coming from. Whether it's an intentional addition or its contamination of raw materials, but either way, that highlights a failing of the manufacturing process," John said. "We are hopeful that their findings will encourage the manufacturers to be a little bit more thoughtful about their manufacturing approach."

About the author: Sanjukta Mondal is a chemist turned science journalist. Her work has appeared in The Hindu, Biospace, and other publications. Find her online at https://www.linkedin.com/in/sanjukta-mondal-181b3517b