The researchers discovered that once a tattoo is made, the ink rapidly travels through the lymphatic system and, within hours, accumulates in large quantities in the lymph nodes — key organs of the body’s defense system. Inside these nodes, immune cells called macrophages actively capture all types of pigment. This ink uptake triggers an inflammatory response with two phases: an acute phase lasting about two days after tattooing, followed by a chronic phase that can persist for years. The chronic phase is particularly concerning because it weakens the immune system, potentially increasing the susceptibility to infections and cancer. The study also showed that macrophages cannot break down the ink like they would other pathogens, wich causes them to die, especially with red and black inks, suggesting these colors may be more toxic. As a result, ink remains trapped in the lymph nodes in a continuous cycle of capture and cell death, gradually affecting the immune system’s defensive capacity.
The study found that tattooed mice produced significantly lower levels of antibodies after vaccination. This effect is likely due to the impaired function of immune cells that remain associated with tattoo ink for long periods. Similarly, human immune cells previously exposed to ink also showed a weakened response to vaccination.
“Human immune cells”, not cells in humans.
That’s not to say this doesn’t happen in humans, it very well may. It’s intriguing research, but it’s still only demonstrated in mice. Important to always keep that in mind until we get better information (which this research is at least leading us to).
Lots of stuff happens in mice (or pigs, or a petri dish) and we find doesn’t replicate to homo sapiens.
It’s also important to keep on mind that the burden of proof is on something to prove it is safe, not that something is unsafe. It happening to human cells in mice would have me assume it happens to human cells in humans until proven otherwise (that’s the null hypothesis in this situation). But also I don’t have a tattoo or any interest in getting one so I’m not too bothered by this.
Humans have been tattooing each other for over 5000 years. I would argue that it’s not really a case of “they need to be proven to be safe”. That ship has sailed. If they are unsafe, we should know, but I think the burden of proof has definitely shifted on tattoos given their extensive history without obvious negative repercussion
What you’re missing is that the ingredients of tattoo ink have changed dramatically in the last 100 or so years.
Prior to then tattoo inks were made mostly with soot or black ash mixed with plant oils.
Nowadays the inks are almost entirely synthetic, sourced from the same companies that make industrial paint, and have been tested and some found to contain carbon black nanoparticles, Texanol, BHT, 2-phenoxyethanol, and various other things that are confirmed (or reasonably suspected) to be toxic and which definitely wouldn’t be in historical inks.
The proof should be entirely on the suppliers and administrators (tattooists) to confirm their ink and tattoos are safe, not the users. Yet their regulations are very lax in most countries, requiring no pharmaceutical testing even though they are injected into people’s skin.
Some refs: https://pubmed.ncbi.nlm.nih.gov/25833640/
https://pubmed.ncbi.nlm.nih.gov/38387033/
https://theconversation.com/whats-in-tattoo-ink-my-teams-chemical-analysis-found-ingredients-that-arent-on-the-label-and-could-cause-allergies-22481
I suspect the effect might be less significant in humans (not human cells, whole humans) because of the square-cube law.