Is tattoo ink really safe? Scientists discover chemicals that ‘potentially cause harm’

CHICAGO — Tattoos are a common sight in society today. Despite their widespread appeal, the United States does not regulate this industry — even though tattoo artists need local licenses and use a variety of chemicals. Now, a new study has discovered that many tattoo inks may contain substances that are harmful to the human body.

Researchers analyzed nearly 100 inks and found that even when products have an ingredient label, the lists are often inaccurate. Some even contain tiny particles that can seep under the skin and potentially cause cancer.

“The idea for this project initially came about because I was interested in what happens when laser light is used to remove tattoos,” says John Swierk, Ph.D., the project’s principal investigator, in a media release. “But then I realized that very little is actually known about the composition of tattoo inks, so we started analyzing popular brands.”

Swierk and his team interviewed U.S. tattoo artists to see what they know about the inks they use on their customers. Although these artists are capable of quickly identifying the brands of ink they use, it turns out few know much about the chemicals in them.

“Surprisingly, no dye shop makes pigment specific for tattoo ink,” Swierk explains. “Big companies manufacture pigments for everything, such as paint and textiles. These same pigments are used in tattoo inks.”

The team adds that there are currently no federal or local agencies which regulate the contents in tattoo ink — even though artists need a license to operate for safety reasons.

So, what’s hiding in tattoo ink?

Tattoo inks have two parts, a pigment and a carrier solution. The pigment can be a molecular compound (a blue pigment), a solid compound like titanium dioxide (which is white), or a combination of the two (light blue ink).

The carrier solution transports this pigment to the middle layer of skin and also makes the pigment more soluble. The carrier solution can also control the thickness of the ink and may include an anti-inflammatory ingredient as well.

Swierk’s team at Binghamton University used Raman spectroscopy, nuclear magnetic resonance spectroscopy, and electron microscopy to study the particle size and molecular composition of dozens of tattoo pigments during their investigation.

Results revealed the presence of ingredients that many tattoo inks don’t list on their ingredient labels. For example, one ink contained ethanol, which the product did not advertise.

“Every time we looked at one of the inks, we found something that gave me pause,” Swierk reports. “For example, 23 of 56 different inks analyzed to date suggest an azo-containing dye is present.”

While many azo pigments are harmless when they are chemically intact, the researchers warn that bacteria or ultraviolet light can degrade them. This turns them into a nitrogen-based compound that can potentially cause cancer.

Moreover, the team analyzed 16 inks using electron microscopy and about half contained particles smaller than 100 nanometers.

“That’s a concerning size range,” Swierk concludes. “Particles of this size can get through the cell membrane and potentially cause harm.”

The researchers are presenting their findings at the fall meeting of the American Chemical Society (ACS).

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