filling in for Wendy Zuckerman, and this is Science Versus.
Today, we are talking about tattoos.
Tattoos are more popular than ever, but lately they've been getting some flack.
Online, we're hearing that Toxic guy tattoo.
Upper chest Roman numerals.
That is always a toxic guy.
Everyone knows one of those guys.
No, not that kind of toxic.
Like poisonous.
It turns out tattoos are actually pretty unhealthy for us.
You're constantly being poisoned by the toxins.
If I were to go back in time with the knowledge I have now, I would not have the tattoos that I have.
People are pointing to tattoo ink, saying that it's full of stuff that you don't want in your body.
Every single person who has a tattoo has metals leaching into the bloodstream.
Mercury, lead, nickel and other harmful heavy metals that will slowly release in your body, adding to your toxic burden daily.
And ultimately, they say that the consequences can be serious.
A new study has found it could increase your risk of developing cancer.
21% chance of getting a malignant lymphoma with even small tattoos.
And if this risk is real, it would affect a lot of people.
According to surveys in the U.S. and Australia, a third of adults are tattooed.
And globally, that number is one in five.
So are these people making a terrible mistake?
If you get a tattoo, are you poisoning yourself and upping your risk of cancer?
And finally, has science found any benefits to getting inked?
Because when it comes to tattoos, there's a lot of... Upper chest Roman numerals.
But then there's science.
Science vs. Tattoos is coming up after the break.
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Welcome back.
We are here to talk about tattoos.
I'm Rose Rimler, and I'm here with Science vs. Editor and tattoo haver, Blythe Terrell.
Hi, Blythe.
Hey, Rose.
Famed tattoo hammer, I will say.
So how many tattoos do you have?
Where are they?
Spell it.
So the first one I got, I got with my good friend like when I was 18.
We both got flowers.
It's just like, I'm 18.
I have a flower.
My husband and I have one that's kind of like I love you in sign language.
It's stylized.
I have a stylized double helix.
On my ankle.
Very nerdy, very on theme.
And then my other one is the Batman logo, but it is the 1960s Batman.
I've always kind of been curious about it.
Why Batman?
So my initials are B-A-T-E.
And so it's been like a running joke.
Okay.
But you're the Batman.
Revealed on this podcast.
Have you ever worried about your tattoos?
I mean, my mom worried that I wouldn't get jobs.
But like health-wise I mean I guess only to the extent that I was like okay, is this guy getting like a clean needle out of the package?
But beyond that, no.
It has never come up for me.
Yeah.
And I was pretty surprised myself when I saw this stuff pop up online about tattoos being toxic.
I don't have any tattoos myself, but I know so many people who do.
So I really want to know, is this true or is this just BS?
Yeah.
Very curious to know what you found.
So, you know, obviously tattoos have been around thousands of years.
But interestingly, scientists have only recently begun to study tattoos, how the tattoo ink interacts with our biology.
This is kind of on the newer side of things.
Scientists like Santiago Gonzalez.
He is a toxicologist and immunologist at the University of Lugano in Switzerland.
Actually started by chance.
So we were not primarily oriented on the tattoo.
Here's what happened.
Santiago needed to label mice for an experiment they were doing about the immune system.
The way they had been doing.
That was putting a tag on the mouse's ear, like tagging their ears, which is very common.
But... I never liked it because it's a bit heavy and the animal is a bit annoying for the animal.
So, instead of tagging their ears, the scientists in his lab decided they were going to try tattooing the animals in order to like, mark them.
We basically have a tattoo machine which is exactly the same as the tattoo machine that is used by all the tattoo artists.
And we just do it normally.
Is it like teeny tiny?
Yeah, it's very small.
So obviously you have to be very, very careful.
So they're chugging along tattooing their mice to do their next experiment, which all seemed to work fine.
But then something unexpected happened.
My students told me.
You know, the lymph nodes of the animals are completely full with the ink of the tattoo.
Oh, gross.
And just as a reminder, lymph nodes are structures in the body that are part of the immune system.
They filter out lymph, which is a fluid that comes from the blood.
So Santiago's team was looking at one of the lymph nodes in the mouse's leg near its foot, which is what had been tattooed.
And they found that it got stained with the tattoo ink.
Okay.
That doesn't sound good.
It's not what they expected.
And it kind of messed up that experiment.
Oh.
That's not what they were studying.
Right.
It's not what they were studying.
They were just using the tattoos to label the mice for another experiment.
But after seeing this, they decided to do an experiment where they tattooed the mice and then watched where the ink went in a more controlled way.
Okay.
So we did all this again and then took photos of the lymph nodes two months later.
So let me show you. oh oh yeah you can really see like that's really you can really see the ink in there like it's it's bright yeah it's a few different colors of ink and you can see like when one mouse has a pretty bright blue limp node like bulbous little goofy thing so how did that happen Well, OK, so your body has these white blood cells are called macrophages that go around gobbling up stuff that they think shouldn't be there.
So this is typically like bacteria, broken bits of cells.
When you get a tattoo, macrophages in your skin, they go around and they slurp up some of that ink.
And it turns out that they're also bringing that ink to the lymph nodes.
And scientists have also seen this in people.
We've had case studies documenting it, like if someone with tattoos goes in to get their lymph node biopsied for whatever reason.
Pathologists will sometimes find ink in the lymph node.
And Santiago's team also found this when they looked at lymph nodes from people, which led him to conclude When you are tattooing your skin, you are also tattooing your lymph nodes.
Okay, so...
We have tattooed lymph nodes, but does that automatically equal some kind of a problem?
Well, it's possible.
I mean, if the lymph node is involved, that means the immune system is involved in some way.
So Santiago's team also checked levels of immune markers in the mice's bodies to see if they were elevated.
That would suggest that they were stressed out, basically.
These are molecules that are part of the body's stress response to injuries or illness.
And he did find that these molecules increased in both the lymph taken from the lymph node and in the mice's blood.
But most of that activation went back to normal after a week or so from getting the tattoo, which makes sense.
Like, of course, you'd have a temporary... inflammatory response to a bunch of needles in your skin.
But there was one exception, a molecule associated with chronic inflammation.
It's actually called alarmin.
Great.
Yeah.
What was the alarmin doing, Rose?
It was alarmed.
It was raised even two months post tattooing, which Santiago argues should have been past the initial healing phase of the tattoo.
Uh-huh.
Okay.
So how worried should we be about that?
Well, you know, Santiago's study was kind of exploratory.
It showed some hints of some immune system weirdness in mice.
It wasn't looking at long-term issues in real people.
So, zooming out to other studies, we do start to see that this activation of the immune system might be a problem for some people.
I read this case study, a guy from Poland.
He had a full-blown immune reaction to his tattoo four months after he got it.
He lost his hair.
He developed vitiligo.
What's that?
That's like a skin, a change in the color of your skin.
Okay.
And he had to get the tattoo essentially cut out of his arm.
There's another series of cases that was published recently in Australia about people who got this allergic reaction to their tattoo ink and it attacked their eyes.
Oh, my God.
And some of them even had vision loss.
Those examples are extreme.
And they're not that common.
But in general, we do see a lot of allergic reactions to tattoos.
Just typically it's confined to the skin.
Actually, you know what that makes me think of, Rose?
So the other day I was sitting with my husband and he looked at me and he was like do your tattoos ever itch?
And I was like, no.
Do your tattoos ever itch?
And you know what else rose?
He has some like immune system stuff going on a little bit.
Another autoimmune system thing.
So I kind of had this feeling as you say this, I'm like.
Oh, I wonder if, like suddenly, there's this change and, like the itchy, like Jack's tattoos are getting a little itchy.
I wonder if it's related.
Okay, interesting.
Well, the best numbers I could find on how common this is, this like sort of skin reaction to tattoos.
It comes from a survey of people with tattoos in Germany.
And it found that about 9 of people reported persistent skin problems at least a month after they got their tattoo.
And so it sounds like he might be in that unlucky sliver of people.
Lucky in love, unlucky in tattoos.
Obviously.
So this happens to a fraction of unlucky people, 9% in that German study.
But there are other reasons to be concerned about tattoo ink that's more universal for everyone who gets tattooed.
One of those things is the fact that a lot of tattoo ink contains chemicals that we think are Possibly carcinogenic.
Hmm.
And that includes black ink.
You know, a lot of your tattoos are black, I noticed.
I think they're, yeah, most of them are black.
Okay, great.
What are you going to tell me about black ink, Rose?
Carcinogenic?
Black ink is basically soot.
Great.
So it's like yeah, like if I were a chimney sweep instead of a podcaster.
Is that what's going on here?
Yes.
Right.
But this is what makes some people worried that tattoos might cause cancer.
And we're going to need some more science to figure that out.
Okay.
So we're going to have to go to Sweden.
Sweden.
I'm ready.
All right.
Always ready.
And that is coming up after the break.
Welcome back.
We're talking about tattoos today.
I'm here with Blythe Terrell.
Hi, Blythe.
Hey, Ruth.
So it turns out there are some reasons to be concerned about tattoos.
We know that the ink doesn't just stay put static in our skin.
It's actually interacting with our immune system, getting into our lymph nodes.
We know that some of the ink might be bad for us, might be even carcinogenic.
But we want to know, like, what are the consequences?
Right.
Besides just you feeling superior to me for that.
Because you don't have tattoos and I do.
We know that people without tattoos are better.
But are they healthier?
I spoke about this with Christelle Nielsen.
She works at Lund University in Sweden.
She is an epidemiologist who focuses on environmental toxins typically stuff like forever chemicals.
But a few years ago, she got curious about potential toxins in tattoos.
And I might have one or two tattoos myself.
So that triggered the interest.
What do you have?
I have a dragon on my arm.
That's awesome.
And I was young in the 90s, so I might have...
Chinese sign on my lower back.
A Chinese character on your lower back?
I'm just laughing because you laugh.
It's a stereotype.
But I don't have a tribal.
I have to say that.
What does the Chinese character mean?
It's supposed to mean horse because I'm born in the year of the horse.
But I showed it to my daughter's friend who knows Chinese.
And she said, I've never seen that sign before.
So I don't know what it means.
This is the classic tattoo horror story of the 90s.
Yeah.
So she's relatable is what I'm saying.
Yes, she's very relatable.
So she decided to learn Chinese.
No, no, she didn't.
She decided to look into tattoos and health.
I was ready to go with you on that journey.
She zoomed in on cancer for the reasons we talked about before the potential carcinogenic ink and also cancer.
We know that chronic inflammation can lead to cancer.
So she dove into that beautiful Scandinavian public health data that we love so much here at Science Versus.
In Sweden we have these very, very in terms of research useful national registries where we all end up, whether we like it or not.
So it has full population coverage.
And especially for cancer, we have the National Cancer Registry.
So if you get diagnosed with cancer in Sweden, any cancer, you will end up there.
So she and her team decided to focus on two types of cancer that they could see plausibly being connected to tattoos.
Skin cancers, including melanoma.
It's kind of obvious.
Yes.
But also lymphoma, that's cancer of the lymph system.
Right, because we know that the ink is in the lymph system.
Right, right.
So that makes sense.
Okay, got it.
And so they pulled the records of everyone in Sweden who had been diagnosed with those cancers between the ages of 20 and 60.
And then they set out to find who among them had tattoos.
So we called...
And in that case, we contacted their next of kin.
I see.
With the main point then of understanding whether the relative had had tattoos or not.
And they also gathered a group of like matched people who did not have cancer, sort of like matched controls.
And they sent out questionnaires to them as well.
A lot of lifestyle stuff, but also like lots of questions about tattoos.
Not just like, do you have a tattoo, but how many do you have?
How big is it?
When'd you get it?
Where'd you get it?
All that kind of stuff.
People really got excited about this.
They sent Christelle like all these emails and stuff.
Like they wanted to tell her all about their tattoos.
Oh.
It's nice to get to know your participants in a way.
And some still send me postcards.
It's really, really sweet.
So the data started coming back and Christelle was working closely with one of her co-authors.
But this is during the pandemic.
They weren't together that much.
So one day Christelle found herself just crunching the data alone.
I was in my house, it was just me and I had the data there and I just Oh no.
Yeah, so she found something when it came to cancer risk.
So first, lymphoma.
We saw an increased risk of lymphoma among those with tattoos.
Compared to those who did not have tattoos, their risk was 20% increased.
They also found about a 30% increased risk of melanoma.
Wow, that seems big.
Is that big?
Well, here's Christelle on that.
So we're talking about relative risk increases.
So the risk on an individual level is small.
People shouldn't be freaking out.
Because it's like it's that sort of situation where a 20 percent increase risk is serious but the original risk might be very small.
So the new risk, even 20% higher, is still not like astronomical.
Is that the idea?
Exactly.
So like in the US, according to the National Cancer Institute, the absolute risk of getting lymphoma is about 22.
So if we apply Christelle's finding to that, it suggests that a tattoo might make that risk go from 22 to 264.
And then for melanoma, it would be like starting at 2.2%, going to 2.9%.
Like sort of for the average person.
Okay.
I mean, right.
So it's not nothing, obviously.
Yeah.
And...
So maybe, if you're a person who's already at increased risk or whatever, that's something, maybe you want to factor that in.
Exactly.
And there are a couple other studies that have looked into this and not all of them find this link to cancer, but the strongest and biggest studies do find this link, like a similar one that was done in Denmark.
Well, but what about like, is there any... reason to think there might be some confounders.
Like, do people who have tattoos tend to have a different kind of lifestyle?
Or like be more likely to party or engage in other behaviors?
Rose, that like might contribute to cancer risk or that kind of stuff?
So, these studies do try to adjust for that as best they can.
But, yeah, it's... probably not perfect.
And there is some evidence that people who have tattoos might do some.
On the whole are more likely to do some risky behavior compared to people who don't have tattoos.
So smoking is something that has come up in the literature.
I think it's like these cancers are not particularly associated with smoking.
Okay, so it sounds like you think there's something here.
Yes, I do.
And I do.
Partly because I think the studies, Christelle's and the other study from Denmark are good studies.
And also, it seems like we have a mechanism that's plausible.
It just, it does make some sense.
Rose, should I get all my tattoos removed?
Because you can, right?
There are ways to get tattoos removed.
Yeah, you can get them removed with lasers.
And you might want to do that if you're freaked out about what I just said or you know you got a Chinese character on your lower back and you actually don't know what it means.
And in fact outside of this, studies do find that something like 20 to 25 of people regret at least one tattoo.
Christelle says the thing about that is for as little as we know about the effect of tattoo ink on the body, we know even less about what happens when we shoot lasers at tattoos.
So...
They need to get through the body to get out in the other end, basically.
The laser blasts the ink into smaller fragments that the immune system then can go and clean up.
But you're still like getting your immune system to, you know, you're triggering an immune response.
And you're also changing the molecules automatically.
And some of those are worse than the original molecules in the ink.
So, for example, we know that a lot of the colors in tattoo inks are made with nitrogen groups called azos.
And when azos are broken apart, they can form compounds that we know are carcinogenic.
So we might set off a cascade of... exposure?
Might be.
I mean, there's a lot we don't know.
We should be getting more information about tattoos generally over the next five or 10 years.
Christelle is going to keep studying people.
She's got this cohort, you know, she's going to keep studying them.
There's another project that's backed by the World Health Organization that's getting off the ground, following people with tattoos over a number of years.
So we're going to find out more about tattoos and health.
I think that we as a society, we will continue to get inked.
And then we need to make sure that it's safe to do it.
Absolutely.
And I think what we do in the show right is like try to give you the information, to like make that decision for yourself.
You know, we're not cops.
But even when I think about it, I'm like I knowing all this, like I don't know, you know, like maybe I still would have gotten my tattoos because I like them.
You know what I mean?
Like, I'm not sure if knowing this would have been quite enough for me to be like, never.
Right.
Well yeah, I mean, and the thing is like, with anything that we talk about, it's always like risk versus benefit, you know.
Benefit looks cool.
No, there are real benefits, Blythe.
It's more than just looking cool.
And I have one final guest to introduce you to, to tell us a little bit more about that.
His name is Viren Swamy.
He is a professor of social psychology at Anglia Ruskin University in the UK.
Being tattooed or being able to get a tattoo is a small marker of agency.
It says I am allowed to own my own body and do what I want with my body.
Historically, essentially, tattoos were the preserve of what psychologists have called outgroups.
And outgroups simply mean marginalized communities.
So, like in the West and in communities colonized by the West, tattooing has been associated with being in an outgroup.
Like think of sailors in the 1700s.
But it's mainstream in other parts of the world, like in Polynesia.
And even though today in the West, tattoos are not as stigmatized, researchers still find an echo of that motivation.
So this is interesting.
The demographic in the US that is most likely to get tattooed.
This is according to a Pew Research survey from a few years ago.
Queer women.
68% of people who identify as queer women have at least one tattoo.
Interesting.
That makes a lot of sense to Viren.
It goes back to the idea of being part of an out-group.
I think any communities that has a history of marginalization will try and reclaim the body in some way.
It's also the same reason why some researchers have talked about how women who have had a history of sexual or physical abuse tend to get tattooed.
Again, it's a way of reclaiming the body and saying, this body is mine.
And we do have some evidence that getting tattooed can help people feel better about themselves.
A few years ago, Viren went to a tattoo shop in London and he surveyed people before and after they got their first tattoo, and also followed up with them a little bit later.
He did stuff like he was assessing their self-esteem.
He asked them, how do you feel about your body?
How do you feel about how you look?
And it turns out that, after they got their tattoo, People reported being happier with their bodies, appreciating their bodies more, feeling like they were more unique as a result of getting tattoos, and feeling lower anxiety about their appearance.
Another study found this too.
This study actually had college students design a temporary tattoo that an artist painted on them.
It lasted a couple weeks.
Uh-huh.
And they measured their self-esteem and how they felt before and after that temporary tattoo.
And it also gave them a boost.
Oh, that's fun.
Yeah.
I think it's telling that most people don't regret their tattoos even years later.
Remember that stat I told you earlier?
It's like maybe 20% of people regret their tattoos.
That means 80% don't.
Yeah, totally.
I'm among the 80%, Rose.
Okay.
Well, I was going to ask you how are you feeling about tattoos after all that information and your husband's itchy arm?
Well yeah, I guess I should tell him to keep an eye out for anything else that might go on.
That's unnerving here right, um?
But yeah, you know, i mean, i think for the generally speaking.
I go into things thinking like oh, it's an internet meme, people are, you know, freaking out or whatever.
It's toxic, don't do it.
And so i expect those things to be kind of not true.
That's my baseline.
I'm skeptical, i guess.
So I think it's really useful to know that maybe there is something there.
I don't know.
Overall, I guess it doesn't freak me out about the tattoos that I have now.
Yeah.
Well, let me ask you this.
Would you get another one?
I don't know.
Do you want to?
Do you have any planned?
I have been thinking about it.
I've had a particular stegosaurus in mind for a while.
Of course.
Yeah.
Well, I will say.
One thing we didn't talk about was like are you more at risk if you have more tattoos?
Yeah.
Well, that's it.
Yeah.
And Christelle's study found no, but the Denmark study found yes, or like bigger tattoos.
And Christelle actually thinks that her finding was sort of an artifact of the way she asked the question.
So she thinks it's very possible.
The more tattoos or the more ink.
If you get like a really ink filled tattoo, very likely could have a higher risk associated with it.
We don't have all the receipts for that.
Something to consider.
Okay.
I can do that, Rose.
I can consider it.
Consider it.
Thank you so much.
Thank you.
And that's Science Versus.
Blythe, you should know that there are 77 citations in this week's episode.
Wow.
Okay.
And you can tell folks where to find them, Blythe?
Yes.
You can find them in our transcript, which we link to in our show notes.
All right.
This episode was produced by Rose Rumler with help from Blythe Terrell Aketi Foster-Keys, Meryl Horn and Michelle Dang.
Wendy Zuckerman is our executive producer.
We're edited by Blythe Terrell.
Fact-checking by Diane Kelly.
Mix and sound design by Bumi Hidaka and Bobby Lord.
Music written by Bobby Lord, Bumi Hidaka, So Wiley, Emma Munger, and Peter Leonard.
Special thanks to all the experts we spoke with for this episode, including Dr Senia Clemenson, Professor David Kreebel, Dr John Swirk.
Natasha Chinotti, Dr. Sandrine Anri, Professor Chris Lin, and Tricia Allen.
Science Versus is a Spotify Studios original.
Listen for free on Spotify or wherever you get your podcasts.
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