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About a third of all Americans have a tattoo. That's according to one survey. And among those age 18 to 34, it's 40%. Yes, that is a lot of ink. NPR's Nell Greenfieldboyce reports that scientists now want to understand what's in tattoo ink and what happens to those substances in the body over time.
(SOUNDBITE OF TATTOO MACHINE BUZZING)
NELL GREENFIELDBOYCE, BYLINE: Despite the pandemic, Tattoo Paradise in Washington, D.C., has plenty of customers. They all wear masks, but a couple of guys are shirtless, exposing their skin for artists who apply ink with buzzing tattoo machines. The shop's owner is Matt Knopp. He says when he first started getting tattooed 30 years ago, information about ink could be hard to come by.
MATT KNOPP: You know, this is magic. You know, they poured stuff out of these bottles that were wrapped and hidden. And, you know, you wouldn't - you couldn't know what it was. You didn't know where they got it from.
GREENFIELDBOYCE: Artists might make their own ink and test it on themselves.
KNOPP: And then they would see if there's any kind of reaction, you know, the skin - did it bubble up? You know, did it just come out? Did it, you know, cause itchiness? Did it do stuff like that?
GREENFIELDBOYCE: Tattooing has gotten so popular these days, there's lots of ink manufacturers making a rainbow of colors. Anybody can buy a bottle online.
KNOPP: So maybe you like red from this company, but you like the green from that company and the blue from that company and, you know, this color from that company. Nowadays, you have those options.
GREENFIELDBOYCE: But the industry has grown without much oversight. And that leaves the small number of scientists who study tattoos asking some pretty basic questions. The first is, what chemicals are in tattoo inks?
JOHN SWIERK: Ink manufacturers aren't even required to disclose what they put into the inks in this country.
GREENFIELDBOYCE: John Swierk is a chemist at Binghamton University. He says the Food and Drug Administration doesn't get involved with tattoo ink unless someone reports a specific safety problem like, say, bacterial contamination.
SWIERK: Within the U.S., there really hasn't been a lot of effort placed into understanding what goes into these inks.
GREENFIELDBOYCE: He's investigating that now because he just got a grant from the National Institutes of Health to look into how these chemicals can be transformed by light, either sunlight that fades a tattoo or a laser that removes it. Tattoos can change over time, which raises another fundamental question. Once tattoo ink is injected into someone's skin, what exactly happens to it?
SWIERK: The whole kind of picture right down to what a tattoo actually looks like in the body is still a surprisingly open research question.
GREENFIELDBOYCE: Swierk says the ink can contain dyes and little bits of solids held together with plastics.
SWIERK: The body really just does not have a lot of tools that are capable of digesting and metabolizing those things.
GREENFIELDBOYCE: So instead, it tries to encapsulate them. It's only been in the last few years that scientists have identified the skin cells that hold on to tattoo pigments. It looks like they get taken up by a kind of immune cell. When one of those cells dies, it releases its bit of pigment and a new immune cell in the skin nabs it. Still, the cells' ongoing effort to contain the chemicals in tattoo ink isn't perfect.
SWIERK: We know that when you get a tattoo that the pigments can become mobile within the body.
GREENFIELDBOYCE: They can end up in the lymph nodes. Surgeons who biopsy lymph nodes can see that they're stained with color. That leads to another open question. If some tattooing chemicals move through the body, what are the potential health risks? Ines Shiver works at the German Federal Institute for Risk Assessment. She says, in tattooing, you can frequently find substances that are either known or thought to cause cancer or damage DNA. But it's hard to know what effect, if any, they might have.
INES SHIVER: In the long term, it's very, very hard to connect cancer to a tattoo.
GREENFIELDBOYCE: Still, she says researchers in Europe are trying to study this. What is clear is that tattoo inks can sometimes trigger allergies. Allergic reactions with symptoms like itching, swelling, redness affect only a small percentage of tattooed people. But given that a tattoo isn't like a piece of jewelry that you can just take off and given the huge numbers of people getting tattooed...
SHIVER: It's really a severe side effect that has to be addressed.
GREENFIELDBOYCE: Red is the color most often linked to allergies. Hundreds of different compounds can be red, however. And Shiver says maybe the trouble isn't the red pigment itself. It could be some other ingredient or impurity associated with it. She and her colleagues want to identify the culprits.
SHIVER: And hopefully find one or multiple substances. Then we can go and say, please don't use these.
GREENFIELDBOYCE: It might end up being more than saying please. In Europe, where she works, tattoo inks are regulated. They have to be labeled with their ingredients. There's limits on certain chemicals. Ink can get pulled from the market because of stuff like excessive nickel, cadmium, arsenic. At the beginning of this year, the European Union started phasing out a couple of widely used blue and green pigments. The tattoo community there is fighting the move. Matt Knopp, the tattoo artist in D.C., is aware that things are very different across the Atlantic.
KNOPP: And it's strange because some of those, you know, you almost feel that - how are you only allowed to use certain inks? You know, you can't tell me that all these other inks are bad, especially when I'm using them in the States.
GREENFIELDBOYCE: He thinks the inks are fine and worries about a witch hunt. Scientists like John Swierk say they're not anti-tattoo. They understand how meaningful this ancient art form can be.
SWIERK: What I want to do is I want to empower artists and clients to really make informed decisions.
GREENFIELDBOYCE: After all, some of those clients are the tattooed people working in his lab.
Nell Greenfieldboyce, NPR News.
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