Scientists Explore Tattoo Ink Chemistry Amid Growing Safety Concerns

Scientists have discovered that tattoo ink ingredient labels are often inaccurate and that some inks contain nanoscale particles that could damage human cells.
Enlarge / Scientists have discovered that tattoo ink ingredient labels are often inaccurate and that some inks contain nanoscale particles that could damage human cells.

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Scientists from Binghamton University (State University of New York) analyzed nearly 100 tattoo inks and found that manufacturers’ ingredient labels (when used) are often inaccurate and that many inks contain small nanoscale particles that could be harmful to human cells. They presented their findings to this week American Chemical Society meeting (ACS) in Chicago.

According to lead researcher John Swierk, a chemist at Binghamton, the project began when his group became interested in tattoos as medical diagnostic tools. This shifted to an interest in laser tattoo removal, specifically how laser light causes tattoos to fade. “We realized we didn’t understand much about the interaction between light and tattoos,” Swierk said during a press briefing at the ACS meeting. “My group studies how light can cause chemical reactions, so it was a natural fit.”

This meant learning more about the chemical makeup of tattoo inks, which is also not well understood. One of the reasons for this significant gap in scientific understanding is that in the United States, at least, manufacturers of tattoo inks are not required to disclose ingredients, and even when they do, there is no There is no real control over whether these disclosures are correct, per Swierk.

Typical tattoo ink contains one or more pigments (which give the ink its color) in a “carrier package” to help deliver the pigments to the skin. The pigments are the same as those used in paints and textiles. These can be small pieces of solids or discrete molecules, such as titanium dioxide or iron oxide (for white or rusty brown colors, respectively). When it comes to carrier wraps, most ink manufacturers use grit or rubbing alcohol, sometimes with a little witch hazel added to the mix to help the skin heal after the tattoo process. There may also be other additives to adjust the viscosity and keep the pigment particles suspended in the carrier package.

The European Union recently cracked down on blue and green pigments used in tattoo inks.
Enlarge / The European Union recently cracked down on blue and green pigments used in tattoo inks.

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First, the team interviewed several tattoo artists and found that while the artists had their favorite brands, they knew very little about the chemical composition of their favorite inks. Next, Swierk’s lab used a variety of methods to analyze a wide range of commonly used tattoo inks, including Raman spectroscopy, nuclear magnetic resonance spectroscopy, and electron microscopy. This allowed them to identify specific pigments and other ingredients in the different inks.

They found that many ingredients did not appear on manufacturers’ labels, such as ink containing ethanol even though it was not listed on the label. And 23 of the inks analyzed so far show evidence of an azo-containing dye. These pigments are generally inert, but exposure to bacteria or UV light can degrade them into a nitrogen-based compound that can cause cancer.

Also, says Swierk, “Often the particle sizes used in tattoo inks are very small – less than 100 nanometers in diameter. When you get to that size regime, you start to worry about nanoparticles getting into the skin. cells, entering the nucleus and causing damage, possibly causing cancer.” About half of the 18 inks analyzed under the electron microscope had particles in this worrying size range.

Bottles of colored ink mixed in a box in a tattoo parlor in Berlin.
Enlarge / Bottles of colored ink mixed in a box in a tattoo parlor in Berlin.

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The European Commission recently began cracking down on harmful chemicals in tattoo ink, including two widely used blue and green pigments (Pigment Blue 15 and Pigment Green 7), saying they are often of low purity and can contain hazardous substances. “Anyone who gets tattooed in the United States with blue or green tattoo inks should assume these pigments of concern are going to be included,” Swierk said. “Most tattoo manufacturers stop selling blue and green inks in Europe [in response to the regulatory crackdown]without necessarily changing pigments, as there is no obvious replacement at the moment.”

However, he added that while the EU science data is concerning, it is not yet the definitive conclusion on the overall safety of the pigments. “These particular pigments have been used in tattooing for a very long time,” Swierk said. “As with all things tattooing, it’s up to consumers to make a decision about their particular comfort level and then proceed accordingly.”

That’s why Swierk and his team created a fledgling website, what’s in my ink? Their research will ultimately be the first comprehensive survey of tattoo inks in the US market, by Swierk. There is currently only rudimentary data from previous peer-reviewed studies available on the site, but once his team completes its analysis of commercial tattoo inks and the resulting data goes through the process of peer-reviewed, the site will serve as a valuable resource for consumers. information on the composition of tattoo inks.

The science and chemistry at play in our skin reacts with tattoo ink.

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