Caveat emptor: 90% of tattoo inks have unlabeled or mislabeled ingredients

Enlarge / New study finds that the chemicals listed on tattoo ink labels often don't match what's actually in the bottle. (credit: ohsarahrose/CC BY-SA 2.0)

If you live in the US and are planning on getting a tattoo any time soon, we've got some potentially unwelcome news. Many common commercial tattoo inks have either different ingredients than those listed on the label or additional substances that are not listed at all, according to a new paper published in the journal Analytical Chemistry. And there are other scientific studies suggesting that some of those ingredients could have adverse health effects, either in the form of allergic reactions or skin or other cancers.

“Our goal is to empower artists and their clients," said co-author John Swierk, a chemist at Binghamton University. "Tattoo artists are serious professionals who have dedicated their lives to this craft, and they want the best possible outcomes for their clients. We’re trying to highlight that there are some deficiencies in manufacturing and labeling.”

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