Scientists from Germany and the European Synchrotron Radiation Facility in France analyzed the bodies of four donors with tattoos and compared them with two donors without tattoos.
They found that tissue samples from two of the inked donors had stained lymph nodes matching the elements on the pigments on their skin.
Among the nanoparticles were five elements that they identified as “toxic,” which were aluminum, chromium, iron, nickel and copper.
The tissue donors were anonymous, so the researchers did not have any health information about them. The study stopped short of suggesting that the nanoparticles can cause any adverse health effects.
But the researchers say their findings should be taken into account for those planning on getting tattoos.
“When someone gets a tattoo, they are often very careful in choosing a parlour where they use sterile needles that haven’t been used previously,” said one of the study’s authors, Hiram Castillo. “No one checks the chemical composition of the colours, but our study shows that maybe they should.”
Dr. Lisa Kellett, a Toronto-based dermatologist who has been practicing for 25 years, said the findings are not surprising, especially because it is well known that tattoo pigment can migrate (for example, when tattoos get blurrier over time because of ink migration).
Kellett explained that our bodies are programmed to try to get rid of anything foreign, which is one of the lymphatic system’s main functions.
“The lymphatic system is so critical to our immune system,” she said. “When you see tattoo ink in the lymph nodes, it’s doing its job in trying to protect the human organism.”
WATCH: Dr. Shelley Duggan talks about the basics of tattoo safety
Dr. Matthew Cheung, a hematologist who works primarily with lymphoma patients, concurred with Kellett, adding that the study sheds new light on the type, concentration and size of the particles found in the lymph nodes.
“The concern would be that we know of heavy metals at certain concentrations or certain oxidized states could be harmful. For example, they could interfere with cellular function or cause cell injury,” he said.
“They have the potential to be harmful but we just don’t know at this level of research at the concentrations of the particles that were found, at this point in time, whether these findings have clinical relevance.”
Kellett says the greatest risks that come with tattoos are contracting communicable or local infections or developing an allergy to the ink. But she says the presence of pigment in your lymph nodes, in her opinion, is not going to cause major damage or injury.
“In general, the amount of ink is such a small part of your body that it’s not significant,” she said.
However, she cautioned that coloured lymph nodes may pose an issue for doctors treating melanoma patients.
Kellett explained that lymph node pigmentation is often used as a marker for malignant melanoma patients, and tattoo ink that mimics this pigmentation may affect a patient’s diagnosis and staging.
Cheung says the take-home message from the study is that it highlights how little we know about the long-term safety of tattoos. As the U.K.’s National Health Service points out, there is very little research on the effects of tattoos on human health, due to ethical issues.
“There really hasn’t been long-term studies that look at the health implications, beyond what happens in the skin,” he said. “For people thinking about getting tattoos, they should at least consider the possible risks that they’re quoted go deeper than what happens in the skin.”
According to Health Canada, cosmetic pigments such as tattoo ink are not specifically approved by the government body. Instead, they maintain a “hotlist” of ingredients that are restricted or prohibited in cosmetics.
For more coverage on the safety risks of tattoos, click here.