A new study has found that brightly coloured tattoos could be leaking potentially toxic heavy metals into people's lymph nodes.
The scientists from the European Synchotron Radiation Facility (ESRF) in Grenoble, France, discovered that tattoo needles can shed miniscule particles of nickel and chromium - which can cause allergic reactions - when a particular pigment is used in the tattooing.
That particular pigment is white titanium dioxide and it is often used to mix with colours such as red, green and blue for colourful tattoos.
This could leave some people having an allergic reaction to their own tattoos.
A 2015 study revealed that around 10 percent of the 300 New Yorkers surveyed experienced an adverse reaction. Redness, swelling, and rashes around the tattoo site were the most common reactions. However, this was then attributed to the ink, rather than the microscopic metal.
The team on the latest study reckon it is actually the metal that causes people to have a bad reaction after getting a tattoo. They also plan to do further research into what other effects these potentially toxic metals could have.
Ines Schreiver, one of the authors for ESRF, said: "We were following up on our previous study, by trying to find the link between iron, chromium and nickel and the colouring of the inks.
"After studying several human tissue samples and finding metallic components, we realized that there must be something else. Then we thought of testing the needle and that was our 'eureka' moment."
Their findings were published in the journal Particle and Fibre Toxicology.
They discovered that when titanium dioxide is used, the needle erodes. However, when only black carbon ink is used, this doesn't happen.
Another of the authors, Hiram Castillo, said: "There is more to tattoos than meet the eye.
"It is not only about the cleanliness of the parlour, the sterilization of the equipment or even about the pigments. Now we find that needle wear also has an impact in your body."
These metal particles measure in at between 50 nanometres to two micrometres long. To put that into context, two micrometres is about the same length as a bacterium cell.
Whilst that sounds small and harmless, nano particles are considered to be more harmful as they have a larger surface area per volume, which increases their potential toxicity.
Schreiver reiterated their desire to perform further studies. She added: "Unfortunately, today, we can't determine the exact impact on human health and possible allergy development deriving from the tattoo needle wear.
"These are long-term effects which can only be assessed in long-term epidemiological studies that monitor the health of thousands of people over decades."
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