Think Before You Ink: Are Tattoos Safe?
Tattoo Ink Research
In a laboratory within FDA's Arkansas-based National Center for Toxicological Research (NCTR), research chemist Paul Howard, Ph.D., and his team are investigating tattoo inks to find out
- the chemical composition of the inks and how they break down (metabolize) in the body;
- the short-term and long-term safety of pigments used in tattoo inks;
- how the body responds to the interaction of light with the inks.
"There have been no systematic studies of the safety of tattoo inks," says Howard, "so we are trying to ask-and answer-some fundamental questions." For example, some tattoos fade over time or fade when they are exposed to sunlight. And laser light is used to remove tattoos. "We want to know what happens to the ink," says Howard. "Where does the pigment go?"
NCTR researchers are exploring several possibilities:
- The body cells may digest and destroy the ink, just as they rid the body of bacteria and other foreign matter as a defense against infection. NCTR studies show that a common pigment used in yellow tattoo inks, Pigment Yellow 74, may be broken down by enzymes, or metabolized. "Just like the body metabolizes and excretes other substances, the body may metabolize small amounts of the tattoo pigment to make it more water soluble, and out it goes," says Howard.
- Sunlight may cause the ink to break down so it is less visible. NCTR researchers have found that Pigment Yellow 74 decomposes in sunlight, breaking down into components that are colorless. The pigment components may still be there, says Howard, and we don't know if these are potentially toxic.
- The skin cells containing the ink may be killed by sunlight or laser light and ink breakdown products may disperse through the body.
Research has also shown that some pigment migrates from the tattoo site to the body's lymph nodes, says Howard. Lymph nodes are part of the lymphatic system, a collection of fluid-carrying vessels in the body that filter out disease-causing organisms. Whether the migration of tattoo ink has health consequences or not is still unknown. NCTR is doing further research to answer this and other questions about the safety of tattoo inks.