Getting a permanent tattoo can cause toxic nanoparticles to travel inside the body, leading to chronic enlargement of the lymph nodes – an important part of our immune system, a study has warned. Toxic impurities that make up the ink in tattoos can travel inside the body in the form of nanoparticles and affect the lymph nodes, researchers said. Little is known about the potential impurities in the colour mixture applied to the skin. Most tattoo inks contain organic pigments, but also include preservatives and contaminants like nickel, chromium, manganese or cobalt. Besides carbon black, the second most common ingredient used in tattoo inks is titanium dioxide (TiO2), a white pigment usually applied to create certain shades when mixed with colorant, researchers said. TiO2 is also commonly used in food additives, sunscreens and paints. Delayed healing, along with skin elevation and itching, are often associated with white tattoos, and by consequence with the use of TiO2. The hazards that potentially derive from tattoos were previously known only by chemical analysis of the inks and their degradation products in vitro. Researchers at European Synchrotron Radiation Facility (ESRF) in Germany used X-ray fluorescence measurements which allowed them to locate titanium dioxide at the micro and nano range in the skin and the lymphatic environment. They found a broad range of particles up to several micrometres in size in human skin, but only smaller (nano) particles were transported to the lymph nodes. This may lead to the chronic enlargement of the lymph node and lifelong exposure, researchers said. Scientists also used the technique of Fourier transform infrared spectroscopy to assess biomolecular changes in the tissues in the proximity of the tattoo particles. “We already knew that pigments from tattoos would travel to the lymph nodes because of visual evidence. The lymph nodes become tinted with the colour of the tattoo. It is the response of the body to clean the site of entrance of the tattoo,” researchers said. “What we didn’t know is that they do it in a nano form, which implies that they may not have the same behaviour as the particles at a micro level. And that is the problem we don’t know how nanoparticles react,” said Bernhard Hesse, from ESRF.