Tattoos are a form of art and expression that adorns millions of bodies worldwide. But behind the dark lines lies an equally dark secret: the tattoo ink ingredients.

Recent research from Binghamton University has unveiled startling discrepancies between what is listed on tattoo ink labels and the actual ingredients within these bottles. Of the 54 inks they subjected to chemical analysis, 45 of them — a staggering 90% — contained pigments and additives that were not listed on the ink bottle’s official ingredient list.

Ink detective work

Tattoo inks consist of tiny solid pigment particles, dyes, and binders mixed into a liquid, usually water. The colors you see in a tattoo result from light bouncing off these particles and dyes or being absorbed by them. But there’s more to these ingredients than just pigment and water.

Previously, researchers at Binghamton University in New York noticed unlisted substances in the inks while researching the effects of light on tattoos. This spurred a wider investigation that set them on a path to gather and analyze tattoo inks from nine manufacturers across the United States. These included international and small, local manufacturers, and involved 54 tattoo ink products in six different colors.

Their findings were alarming: 90% of the inks examined contained major discrepancies compared to their labels. This included different pigments and unlisted additives — such as polyethylene glycol, which poses a risk of organ damage, and propylene glycol, a known allergen — among other contaminants.

Some of the more concerning unlisted ingredients include antibiotics and substances harmful to nursing infants. People with allergies are probably the most at risk of suffering complications from poorly-labeled tattoo ink. Tattoos are notoriously difficult to remove and an unlisted allergen, such as nickel, could cause years of skin irritation. Red pigments are particularly problematic, although it has been clear why — perhaps these ‘missing’ ingredients provide a hint.

Time to regulate tattoo ink in the US

It’s unclear how these substances have ended up in the ink products. And it’s rather unlikely they were intentional additions. It could be a problem due to poorly sourced ingredients across the supply chain. Where there are many different producers from across the world, each contributes to the final product’s contents.

“We’re hoping the manufacturers take this as an opportunity to reevaluate their processes, and that artists and clients take this as an opportunity to push for better labeling and manufacturing,” said John Swierk, Assistant Professor of Chemistry at Binghamton University.

This research arrives at just the right time. With the passage of the Modernization of Cosmetics Regulation Act (MoCRA) at the end of 2022, the FDA now has the authority to regulate tattoo inks. This study will undoubtedly help influence regulatory discussions and the future of tattoo ink safety.

“Our goal in a lot of this research is to empower artists and their clients. Tattoo artists are serious professionals who have dedicated their lives to this craft and they want the best possible outcomes for their clients,” Swierk said. “We’re trying to highlight that there are some deficiencies in manufacturing and labeling.”

If you’re interested in learning more about what’s inside tattoo inks, Swierk and colleagues have set up a website called “What’s in My Ink?”. This resource can help you make a more informed decision before inking up.

“Our goal with “What’s in My Ink?” is to help artists and consumers make informed choices. As chemists, we have access to tools that the average person doesn’t, which allows us to really look into inks and evaluate what’s in them. People should be free to make their own decisions but we want to provide them with the best information we can. For example, others have that some inks might contain a high level of chromium or nickel. If you have an allergy to those metals, you would want to know that so that you can avoid those inks,” Swierk told ZME Science in a previous article.

The findings appeared in the journal Analytical Chemistry.