Scientists examine tattoo ink chemistry amid mounting safety concerns

Scientists at Binghamton University (State University of New York) analyzed nearly 100 different tattoo inks and found that the manufacturer’s ingredient labels (if used) are often inaccurate and that many inks contain tiny nanoscale particles that can harm human cells. . They presented their findings this week at the American Chemical Society (ACS) meeting in Chicago.

According to lead researcher John Swierk, a chemist at Binghamton, the project began when his group became interested in tattoos as tools for medical diagnostics. 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 at a press conference at the ACS meeting. “My group studies how light can trigger chemical reactions, so it was a natural match.”

That meant learning more about the chemical makeup of tattoo inks, which is also not well understood. One reason for this significant gap in scientific understanding is that at least in the US, tattoo ink manufacturers are not required to disclose the ingredients, and even if they do, there’s no real record of whether those disclosures are accurate. , by Heavy.

Typical tattoo ink contains one or more pigments (which give the ink its color) in a “carrier pack” to deliver the pigments into the skin. The pigments are the same as those used in paints and textiles. They can be small pieces of solid or individual molecules, such as titanium dioxide or iron oxide (for white or rust brown colors, respectively). As for the carrier packaging, most ink manufacturers use grain or rubbing alcohol, sometimes with a bit of witch hazel in the mix to help the skin heal after tattooing. There may also be other additives to adjust viscosity and keep pigment particles suspended in the carrier package.

First, the team interviewed several tattoo artists and found that while the artists had their favorite brands, they knew very little about the chemical makeup of their favorite inks. Then Swierk’s lab used a variety of methods to analyze a wide variety 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 various inks.

They found that many ingredients were not listed on the manufacturer’s labels, such as one ink that contained ethanol even though it was not on the label. And 23 of the inks analyzed so far show traces of an azo-containing dye. Such pigments are usually inert, but exposure to bacteria or UV light can cause them to break down into a nitrogen-based compound that can potentially cause cancer.

In addition, says Swierk, “Often the particle sizes used in tattoo inks are very small — less than 100 nanometers in diameter. They can cause damage, potentially cause cancer.” About half of the 18 inks analyzed by electron microscopy had particles in this worrying size range.

The European Commission has recently started tackling harmful chemicals in tattoo inks, including two commonly used blue and green pigments (Pigment Blue 15 and Pigment Green 7), claiming that they are often of low purity and may contain hazardous substances. “Anyone getting a tattoo in the US with blue or green tattoo ink should assume that those pigments will be absorbed,” says Swierk. “Most tattoo manufacturers stop selling blue and green inks in Europe [in response to the regulatory crackdown]not necessarily changing pigments, as there is no obvious replacement at this point.”

However, he added that while the EU’s scientific data is worrying, it is not yet the final conclusion on the overall safety of the pigments. “Those specific pigments have been used in tattooing for a long time,” says Swierk. “As with anything tattoo-related, it is the duty of consumers to make a decision about their particular comfort level and act accordingly.”

That’s why Swierk and his team created a fledgling website, What’s in My Ink? Their research will eventually form the first comprehensive survey of tattoo inks on the U.S. market, according to Swierk. Only rudimentary data from previous peer-reviewed studies is currently available on the site, but once his team has completed the analysis of commercial tattoo inks and the resulting data has gone through the peer-review process, the site will serve as a valuable resource. for consumers for information on the composition of tattoo inks.