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Beneath the Skin: The Unseen Impact of Metals in Tattoo Inks

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Beneath the Skin

What the metals do after the needle

Originally published September 24, 2024. Revised with research published since.

The last piece asked what’s in tattoo ink. This one asks what happens to it afterward, which turns out to be the harder question and the one where the evidence has moved most in the past two years.

I came at this from my own body first. I had unexplained health issues in the years after getting tattooed and went looking for a mechanism. That’s an honest starting point and a weak piece of evidence, and I want to be clear about both. One person noticing a pattern in his own life is how inquiry starts, not how it ends. Almost everything that follows is other people’s work.

The measurement everyone cites comes from a team at Ege University in Turkey, published by Sozer Karadagli, Cansever, Armagan and Sogut in Chemical Research in Toxicology in 2023. They ran inks through ICP-MS and found aluminum from 1,191 to 3,425 mg/kg, copper from 1.24 to 2,523, iron from 17 to 318, zinc from 2.6 to 47, nickel from 0.63 to 17.5, and cobalt under 1.1.

It’s three colors from three brands. Green, black and red. That’s a real signal about how variable these products are and it is not a survey of the market, and the distinction gets lost nearly every time the numbers get quoted.

Aluminum is in there mostly because of how pigments are manufactured. Organic pigments are commonly precipitated onto aluminum substrates or resinated with aluminum salts to make them stable and insoluble, and aluminum compounds get used as extenders and opacifiers. Nobody decided a tattoo needed aluminum. It came along with the chemistry. That’s a less dramatic story than intentional adulteration, and it matters practically, because it means hunting for aluminum-free ink is harder than reading a label.

What makes aluminum worth attention isn’t the amount. It’s that the body has no plan for it. Iron has transferrin and ferritin and hepcidin. Copper has ceruloplasmin and its own transporters. Aluminum has nothing, because nothing in our evolutionary history ever called for it. What it does instead is ride the iron system by resemblance, binding transferrin’s iron sites closely enough to get delivered into cells by a transport system built for something else. I went through that at length in the previous piece and won’t repeat it here.

The question that used to be speculative is what all this does to the immune system over time. It isn’t speculative anymore.

In late 2025 a group at the Institute for Research in Biomedicine in Bellinzona published a study in PNAS following tattoo ink through the lymphatic system in mice. The ink drained fast. Macrophages in the draining lymph node took it up, and many of those macrophages then died, which the researchers confirmed in human cells as well as mouse. Inflammation in that node was still clearly present two months later. And the ink changed how the animals responded to vaccines given into the same drainage territory, dampening the antibody response to an mRNA COVID vaccine and amplifying the response to a UV-inactivated influenza vaccine.

That last detail is the one I keep turning over. The effect wasn’t uniformly suppressive. It ran in both directions depending on the vaccine. That is not what you’d expect from a simple toxic burden, and it is exactly what you’d expect from a lymph node whose immune environment has been persistently altered. The system isn’t damaged so much as recalibrated, and nobody knows toward what.

This sits on top of what Schreiver and colleagues showed in 2017, mapping tattooed skin and draining lymph nodes with synchrotron X-ray fluorescence and finding pigment in the nodes. The migration was already established. What’s new is evidence about what the pigment does once it arrives.

Then there’s the epidemiology, which has arrived largely in the last two years.

A Swedish population-based case-control study published in eClinicalMedicine in 2024 looked at every incident lymphoma diagnosed in people aged 20 to 60 between 2007 and 2017, with three matched controls each. Tattooed people had a 21 percent higher adjusted risk of malignant lymphoma. That result was not statistically significant, and the subtype associations for diffuse large B-cell and follicular lymphoma had confidence intervals that crossed one.

Here’s the part that complicates the obvious story. The Swedish study found no dose response by tattooed body area. The highest risk showed up in people with tattoos smaller than a palm. If this were a straightforward matter of metal load, more ink should mean more risk, and it didn’t.

A Danish twin study published in BMC Public Health in 2025 found close to the opposite. Using the Danish Twin Registry, which allows control for shared genetics and upbringing, tattoos larger than a palm carried a hazard ratio of 2.73 for lymphoma and 2.37 for skin cancer. Median time from first tattoo to lymphoma diagnosis was eight years.

Two good studies, opposite findings on dose. An exploratory meta-analysis in 2025 pooled the case-control work and did not resolve it. I don’t know how to reconcile them and I’d be suspicious of anyone who says they do. What can be said is that the association keeps appearing across independent populations, that the proposed mechanism now has direct experimental support, and that the dose relationship is unsettled in a way that should make everyone slower.

One line of evidence deserves more hedging than it usually gets. A 2013 mouse study from Gherardi’s group in France, published in BMC Medicine, showed aluminum particles carried out of injected muscle inside monocyte-lineage cells and eventually detected in brain tissue. It gets cited widely as proof that macrophages ferry aluminum across the blood-brain barrier. The authors themselves describe that as a possible mechanism rather than a demonstrated one, the model was intramuscular injection rather than dermal deposition, the particle numbers reaching brain were very small, and some of the funding came from patient advocacy organizations with a position on the question. It’s worth knowing about. It is not the settled finding it gets treated as.

Aluminum isn’t the only metal in the bottle. Copper runs across a two-thousand-fold range between the lowest and highest samples in that Turkish data, which is less a fact about tattoos than a fact about quality control. Nickel is a well-established contact allergen and shows up in real quantities. Iron I’d frame differently than most people do: the problem with iron is rarely the raw amount, it’s whether copper-dependent regulation can direct it. Iron the body can’t chaperone is iron that generates oxidative stress. That’s true of dietary iron and there’s no reason to think dermal iron is exempt.

Which brings me to removal, where the popular accounts are worse than the research.

Laser removal carries a real chemical risk, and it isn’t the one usually named. The hazard isn’t mercury in red pigment, which was largely phased out decades ago. It’s that lasers break pigments into other compounds. Azo pigments cleave into aromatic amines including 2-methyl-5-nitroaniline, 3,3′-dichlorobenzidine and o-toluidine, several of them carcinogenic, and 3,3′-dichlorobenzidine has been shown to cause DNA strand breaks in human skin cells. Copper phthalocyanine blue releases hydrogen cyanide under ruby laser irradiation, at concentrations high enough to compromise skin cell viability in vitro. That’s CI 74160, the same pigment I held up in the last piece as an example of good manufacturer disclosure and which the EU subsequently restricted. It keeps turning out to be the interesting one.

On the non-laser side, you’ll see bentonite clay recommended, usually with a rationale about the clay’s negative charge attracting positively charged metal ions and drawing the ink out. That rationale doesn’t work. Pigment sits in the dermis, below the barrier layer, in insoluble crystals and largely inside cells. Nothing spread on the surface of intact skin reaches it, and the pigment carries no net charge to attract.

What does exist is a family of non-laser methods used mostly on permanent makeup, where a solution is needled into the skin rather than applied on top. Saline systems are the common ones, and some, including UNDO, use bentonite. These produce real pigment loss. But the working part isn’t the clay, it’s the wound. A hypertonic solution needled into the dermis pulls water out of pigment-holding cells, pigment travels upward into the scab that forms, and the scab carries some of it away when it sheds. Wound healing is doing the labor. The clay is a passenger.

Two things follow. Permanent makeup is deposited shallower and less densely than body ink, which is why these methods have a foothold on eyebrows and very little of one on a sleeve. And the dermatology literature on non-laser removal in general, covering salabrasion, acid peels and chemical injection, is consistent about scarring and dyspigmentation, which is why laser remains the standard despite its own problems. Nearly everything written in favor of saline and clay removal comes from the companies selling the solutions and the academies training people to use them. That’s the same standard of evidence I declined to accept from ink manufacturers earlier in this series.

The part that matters most here is simpler than any of it. Every removal method that works, laser included, works by mobilizing pigment out of where it settled and handing it to the lymphatic system. If persistent lymph node inflammation is the thing driving someone toward removal, then all the available options send a larger bolus down that same road. Slower is not the same as gentler. I don’t have a clean answer to that, and I’d rather name it than pretend the natural-sounding option sidesteps the problem.

Surgical excision is the accurate term for the last resort, with grafting only where the area is large enough to require it. It removes the tissue that holds the pigment. It’s real, it’s invasive, and it trades a tattoo for a scar.

People vary in how they respond to all of this, and the honest list of what predicts trouble is short: a history of contact allergy to nickel or cobalt, existing autoimmune disease, and how much ink is going in and where. Beyond that, most of what gets asserted about individual susceptibility is confident guessing.

The practical advice hasn’t changed much. Ask your artist what brand they use and whether they can show you the safety data sheet with CI numbers on it. If you’ve reacted to nickel jewelry or cheap earrings, say so beforehand rather than after. If you’re getting something large, know that the epidemiology on large tattoos is the part that currently looks least reassuring.

None of this is an argument against tattoos, and I still have mine. What’s changed is that the questions have gotten sharper rather than getting answered. Two years ago the concern about chronic immune activation was a plausible story built out of adjuvant chemistry. Now there’s a lymph node in a mouse still inflamed two months later, a vaccine response that moved in both directions, and a lymphoma association that shows up across independent populations while stubbornly refusing to behave like a dose.

I don’t think that means what the loudest people on either side of this say it means. It means we’re roughly where we should have been before a few hundred million people got tattooed, which is at the beginning.

References

Sozer Karadagli, S., Cansever, I., Armagan, G., & Sogut, O. (2023). Are Some Metals in Tattoo Inks Harmful to Health? An Analytical Approach. Chemical Research in Toxicology, 36(1), 104-111.

Capucetti, A., Falivene, J., Pizzichetti, C., et al. (2025). Tattoo ink induces inflammation in the draining lymph node and alters the immune response to vaccination. PNAS, 122(48), e2510392122.

Schreiver, I., Hesse, B., Seim, C., et al. (2017). Synchrotron-based μ-XRF mapping and μ-FTIR microscopy enable to look into the fate and effects of tattoo pigments in human skin. Scientific Reports, 7(1), 11395.

Nielsen, C., Jerkeman, M., & Jöud, A. S. (2024). Tattoos as a risk factor for malignant lymphoma: a population-based case-control study. eClinicalMedicine, 72, 102649.

Clemmensen, S. B., Mengel-From, J., Kaprio, J., Frederiksen, H., & Hjelmborg, J. v. B. (2025). Tattoo ink exposure is associated with lymphoma and skin cancers: a Danish study of twins. BMC Public Health, 25, 170.

Schreiver, I., Hutzler, C., Laux, P., Berlien, H.-P., & Luch, A. (2015). Formation of highly toxic hydrogen cyanide upon ruby laser irradiation of the tattoo pigment phthalocyanine blue. Scientific Reports, 5, 12915.

Vasold, R., Naarmann, N., Ulrich, H., et al. (2004). Tattoo pigments are cleaved by laser light: the chemical analysis in vitro provides evidence for hazardous compounds. Photochemistry and Photobiology, 80(2), 185-190.

Hering, H., Sung, A. Y., Röder, N., Hutzler, C., Berlien, H.-P., & Laux, P. (2018). Laser Irradiation of Organic Tattoo Pigments Releases Carcinogens with 3,3′-Dichlorobenzidine Inducing DNA Strand Breaks in Human Skin Cells. Journal of Investigative Dermatology, 138(12), 2687-2690.

Dash, S., & Behera, B. (2023). Non-laser treatment for tattoo removal. Journal of Cosmetic Dermatology, 22(4), 1200-1207.

Khan, Z., Combadière, C., Authier, F.-J., et al. (2013). Slow CCL2-dependent translocation of biopersistent particles from muscle to brain. BMC Medicine, 11, 99.

Exley, C. (2020). An aluminium adjuvant in a vaccine is an acute exposure to aluminium. Journal of Trace Elements in Medicine and Biology, 57, 57-59.

Share This Post

More To Explore

Beneath the Skin: The Unseen Impact of Metals in Tattoo Inks

Beneath the Skin

What the metals do after the needle

Originally published September 24, 2024. Revised with research published since.

The last piece asked what’s in tattoo ink. This one asks what happens to it afterward, which turns out to be the harder question and the one where the evidence has moved most in the past two years.

I came at this from my own body first. I had unexplained health issues in the years after getting tattooed and went looking for a mechanism. That’s an honest starting point and a weak piece of evidence, and I want to be clear about both. One person noticing a pattern in his own life is how inquiry starts, not how it ends. Almost everything that follows is other people’s work.

The measurement everyone cites comes from a team at Ege University in Turkey, published by Sozer Karadagli, Cansever, Armagan and Sogut in Chemical Research in Toxicology in 2023. They ran inks through ICP-MS and found aluminum from 1,191 to 3,425 mg/kg, copper from 1.24 to 2,523, iron from 17 to 318, zinc from 2.6 to 47, nickel from 0.63 to 17.5, and cobalt under 1.1.

It’s three colors from three brands. Green, black and red. That’s a real signal about how variable these products are and it is not a survey of the market, and the distinction gets lost nearly every time the numbers get quoted.

Aluminum is in there mostly because of how pigments are manufactured. Organic pigments are commonly precipitated onto aluminum substrates or resinated with aluminum salts to make them stable and insoluble, and aluminum compounds get used as extenders and opacifiers. Nobody decided a tattoo needed aluminum. It came along with the chemistry. That’s a less dramatic story than intentional adulteration, and it matters practically, because it means hunting for aluminum-free ink is harder than reading a label.

What makes aluminum worth attention isn’t the amount. It’s that the body has no plan for it. Iron has transferrin and ferritin and hepcidin. Copper has ceruloplasmin and its own transporters. Aluminum has nothing, because nothing in our evolutionary history ever called for it. What it does instead is ride the iron system by resemblance, binding transferrin’s iron sites closely enough to get delivered into cells by a transport system built for something else. I went through that at length in the previous piece and won’t repeat it here.

The question that used to be speculative is what all this does to the immune system over time. It isn’t speculative anymore.

In late 2025 a group at the Institute for Research in Biomedicine in Bellinzona published a study in PNAS following tattoo ink through the lymphatic system in mice. The ink drained fast. Macrophages in the draining lymph node took it up, and many of those macrophages then died, which the researchers confirmed in human cells as well as mouse. Inflammation in that node was still clearly present two months later. And the ink changed how the animals responded to vaccines given into the same drainage territory, dampening the antibody response to an mRNA COVID vaccine and amplifying the response to a UV-inactivated influenza vaccine.

That last detail is the one I keep turning over. The effect wasn’t uniformly suppressive. It ran in both directions depending on the vaccine. That is not what you’d expect from a simple toxic burden, and it is exactly what you’d expect from a lymph node whose immune environment has been persistently altered. The system isn’t damaged so much as recalibrated, and nobody knows toward what.

This sits on top of what Schreiver and colleagues showed in 2017, mapping tattooed skin and draining lymph nodes with synchrotron X-ray fluorescence and finding pigment in the nodes. The migration was already established. What’s new is evidence about what the pigment does once it arrives.

Then there’s the epidemiology, which has arrived largely in the last two years.

A Swedish population-based case-control study published in eClinicalMedicine in 2024 looked at every incident lymphoma diagnosed in people aged 20 to 60 between 2007 and 2017, with three matched controls each. Tattooed people had a 21 percent higher adjusted risk of malignant lymphoma. That result was not statistically significant, and the subtype associations for diffuse large B-cell and follicular lymphoma had confidence intervals that crossed one.

Here’s the part that complicates the obvious story. The Swedish study found no dose response by tattooed body area. The highest risk showed up in people with tattoos smaller than a palm. If this were a straightforward matter of metal load, more ink should mean more risk, and it didn’t.

A Danish twin study published in BMC Public Health in 2025 found close to the opposite. Using the Danish Twin Registry, which allows control for shared genetics and upbringing, tattoos larger than a palm carried a hazard ratio of 2.73 for lymphoma and 2.37 for skin cancer. Median time from first tattoo to lymphoma diagnosis was eight years.

Two good studies, opposite findings on dose. An exploratory meta-analysis in 2025 pooled the case-control work and did not resolve it. I don’t know how to reconcile them and I’d be suspicious of anyone who says they do. What can be said is that the association keeps appearing across independent populations, that the proposed mechanism now has direct experimental support, and that the dose relationship is unsettled in a way that should make everyone slower.

One line of evidence deserves more hedging than it usually gets. A 2013 mouse study from Gherardi’s group in France, published in BMC Medicine, showed aluminum particles carried out of injected muscle inside monocyte-lineage cells and eventually detected in brain tissue. It gets cited widely as proof that macrophages ferry aluminum across the blood-brain barrier. The authors themselves describe that as a possible mechanism rather than a demonstrated one, the model was intramuscular injection rather than dermal deposition, the particle numbers reaching brain were very small, and some of the funding came from patient advocacy organizations with a position on the question. It’s worth knowing about. It is not the settled finding it gets treated as.

Aluminum isn’t the only metal in the bottle. Copper runs across a two-thousand-fold range between the lowest and highest samples in that Turkish data, which is less a fact about tattoos than a fact about quality control. Nickel is a well-established contact allergen and shows up in real quantities. Iron I’d frame differently than most people do: the problem with iron is rarely the raw amount, it’s whether copper-dependent regulation can direct it. Iron the body can’t chaperone is iron that generates oxidative stress. That’s true of dietary iron and there’s no reason to think dermal iron is exempt.

Which brings me to removal, where the popular accounts are worse than the research.

Laser removal carries a real chemical risk, and it isn’t the one usually named. The hazard isn’t mercury in red pigment, which was largely phased out decades ago. It’s that lasers break pigments into other compounds. Azo pigments cleave into aromatic amines including 2-methyl-5-nitroaniline, 3,3′-dichlorobenzidine and o-toluidine, several of them carcinogenic, and 3,3′-dichlorobenzidine has been shown to cause DNA strand breaks in human skin cells. Copper phthalocyanine blue releases hydrogen cyanide under ruby laser irradiation, at concentrations high enough to compromise skin cell viability in vitro. That’s CI 74160, the same pigment I held up in the last piece as an example of good manufacturer disclosure and which the EU subsequently restricted. It keeps turning out to be the interesting one.

On the non-laser side, you’ll see bentonite clay recommended, usually with a rationale about the clay’s negative charge attracting positively charged metal ions and drawing the ink out. That rationale doesn’t work. Pigment sits in the dermis, below the barrier layer, in insoluble crystals and largely inside cells. Nothing spread on the surface of intact skin reaches it, and the pigment carries no net charge to attract.

What does exist is a family of non-laser methods used mostly on permanent makeup, where a solution is needled into the skin rather than applied on top. Saline systems are the common ones, and some, including UNDO, use bentonite. These produce real pigment loss. But the working part isn’t the clay, it’s the wound. A hypertonic solution needled into the dermis pulls water out of pigment-holding cells, pigment travels upward into the scab that forms, and the scab carries some of it away when it sheds. Wound healing is doing the labor. The clay is a passenger.

Two things follow. Permanent makeup is deposited shallower and less densely than body ink, which is why these methods have a foothold on eyebrows and very little of one on a sleeve. And the dermatology literature on non-laser removal in general, covering salabrasion, acid peels and chemical injection, is consistent about scarring and dyspigmentation, which is why laser remains the standard despite its own problems. Nearly everything written in favor of saline and clay removal comes from the companies selling the solutions and the academies training people to use them. That’s the same standard of evidence I declined to accept from ink manufacturers earlier in this series.

The part that matters most here is simpler than any of it. Every removal method that works, laser included, works by mobilizing pigment out of where it settled and handing it to the lymphatic system. If persistent lymph node inflammation is the thing driving someone toward removal, then all the available options send a larger bolus down that same road. Slower is not the same as gentler. I don’t have a clean answer to that, and I’d rather name it than pretend the natural-sounding option sidesteps the problem.

Surgical excision is the accurate term for the last resort, with grafting only where the area is large enough to require it. It removes the tissue that holds the pigment. It’s real, it’s invasive, and it trades a tattoo for a scar.

People vary in how they respond to all of this, and the honest list of what predicts trouble is short: a history of contact allergy to nickel or cobalt, existing autoimmune disease, and how much ink is going in and where. Beyond that, most of what gets asserted about individual susceptibility is confident guessing.

The practical advice hasn’t changed much. Ask your artist what brand they use and whether they can show you the safety data sheet with CI numbers on it. If you’ve reacted to nickel jewelry or cheap earrings, say so beforehand rather than after. If you’re getting something large, know that the epidemiology on large tattoos is the part that currently looks least reassuring.

None of this is an argument against tattoos, and I still have mine. What’s changed is that the questions have gotten sharper rather than getting answered. Two years ago the concern about chronic immune activation was a plausible story built out of adjuvant chemistry. Now there’s a lymph node in a mouse still inflamed two months later, a vaccine response that moved in both directions, and a lymphoma association that shows up across independent populations while stubbornly refusing to behave like a dose.

I don’t think that means what the loudest people on either side of this say it means. It means we’re roughly where we should have been before a few hundred million people got tattooed, which is at the beginning.

References

Sozer Karadagli, S., Cansever, I., Armagan, G., & Sogut, O. (2023). Are Some Metals in Tattoo Inks Harmful to Health? An Analytical Approach. Chemical Research in Toxicology, 36(1), 104-111.

Capucetti, A., Falivene, J., Pizzichetti, C., et al. (2025). Tattoo ink induces inflammation in the draining lymph node and alters the immune response to vaccination. PNAS, 122(48), e2510392122.

Schreiver, I., Hesse, B., Seim, C., et al. (2017). Synchrotron-based μ-XRF mapping and μ-FTIR microscopy enable to look into the fate and effects of tattoo pigments in human skin. Scientific Reports, 7(1), 11395.

Nielsen, C., Jerkeman, M., & Jöud, A. S. (2024). Tattoos as a risk factor for malignant lymphoma: a population-based case-control study. eClinicalMedicine, 72, 102649.

Clemmensen, S. B., Mengel-From, J., Kaprio, J., Frederiksen, H., & Hjelmborg, J. v. B. (2025). Tattoo ink exposure is associated with lymphoma and skin cancers: a Danish study of twins. BMC Public Health, 25, 170.

Schreiver, I., Hutzler, C., Laux, P., Berlien, H.-P., & Luch, A. (2015). Formation of highly toxic hydrogen cyanide upon ruby laser irradiation of the tattoo pigment phthalocyanine blue. Scientific Reports, 5, 12915.

Vasold, R., Naarmann, N., Ulrich, H., et al. (2004). Tattoo pigments are cleaved by laser light: the chemical analysis in vitro provides evidence for hazardous compounds. Photochemistry and Photobiology, 80(2), 185-190.

Hering, H., Sung, A. Y., Röder, N., Hutzler, C., Berlien, H.-P., & Laux, P. (2018). Laser Irradiation of Organic Tattoo Pigments Releases Carcinogens with 3,3′-Dichlorobenzidine Inducing DNA Strand Breaks in Human Skin Cells. Journal of Investigative Dermatology, 138(12), 2687-2690.

Dash, S., & Behera, B. (2023). Non-laser treatment for tattoo removal. Journal of Cosmetic Dermatology, 22(4), 1200-1207.

Khan, Z., Combadière, C., Authier, F.-J., et al. (2013). Slow CCL2-dependent translocation of biopersistent particles from muscle to brain. BMC Medicine, 11, 99.

Exley, C. (2020). An aluminium adjuvant in a vaccine is an acute exposure to aluminium. Journal of Trace Elements in Medicine and Biology, 57, 57-59.

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More To Explore

Mineral Shaman
Contact Me