"Tattoos could give you cancer, new research suggests," is the entirely unsupported claim from the Mail Online.
The news come from a study that found evidence particles from tattoo ink can spread into lymph nodes – but it hasn't been proven that tattoo ink causes cancer.
Researchers used samples of skin and adjacent lymph nodes taken from six donors after autopsy.
Four of the donors had tattoos and were more likely to have substances like titanium in the lymph nodes. Lymph nodes are part of the lymphatic system, which in turn is part of the immune system.
The problem is the researchers didn't include important information about whether any of the donors had cancer, or what caused their deaths. This means it's not possible to claim that the tattoo ink particles found in lymph nodes cause cancer.
Tattoos have become far more popular in recent years, leading to concerns about their safety. The ink used in tattoos includes a mixture of organic and metal-based pigments and preservatives.
There's been little study of their effects on human health. This is partly because animal experiments are thought to be unethical, as tattoos are a matter of choice, not medical necessity.
Most safety concerns have focused on the need to ensure tattoo artists use sterile needles to prevent the spread of blood-borne diseases, such as hepatitis C.
We don't know whether the spread of ink particles into lymph nodes would have any significant impact on human health, let alone cause cancer.
Researchers were from the German Federal Institute for Risk Assessment, Physikalisch-Technische Bundesanstalt, and the Institute of Forensic Medicine in Germany, and the Department of X-ray Spectrometry European Synchrotron Radiation Facility in France.
The Guardian's reporting is balanced and accurate. But the Mail Online's coverage is less accurate, focusing on the "controversial" chemical titanium dioxide found in some tattoo inks, stating it's been "linked to cancer".
There's no evidence titanium dioxide is linked to cancer except possibly when inhaled, which would usually only be a risk for people who work in manufacturing.
This post-mortem research was carried out on tissue samples from people with and without tattoos.
The researchers used a variety of techniques, including X-ray fluorescence imaging, to measure levels of dyes and metals in skin and lymph nodes.
Lymph nodes are part of the body's immune system, and are located in the neck, armpits and groin.
Tiny foreign bodies such as nanoparticles of pigment can be swept up by lymph fluid or blood cells and transported to the lymph nodes.
The research doesn't tell us what effect these findings might have on people's health.
Researchers took samples of tattooed skin and lymph nodes from four people with tattoos and two people without to act as a control sample.
They ran a series of experiments to identify the types of pigments and particles in the skin and lymph nodes to see whether ink particles travelled to the lymph nodes and persisted there.
They also looked at tissue surrounding ink particles to see whether it differed from tissue not close to ink particles.
Using a range of techniques, they set out to answer four questions:
They used a number of advanced spectroscopy techniques to analyse the tissue.
Spectroscopy involves analysing a sample of organic matter by measuring the wavelength of the spectrum of light it produces – different elements produce distinct lines on the spectrum.
The researchers found:
The researchers said they found "strong evidence for both migration and long-term deposition of toxic elements and tattoo pigments" from tattoos on the skin into the lymph nodes.
They added they have found evidence for "alterations of biomolecules" in the tissues of skin affected by pigment particles, which may contribute to skin inflammation "and other adversities" connected with tattooing.
If you already have a tattoo, there's nothing in this study that should alarm you. It doesn't show that people with tattoos are more likely to get cancer, despite the scaremongering headlines.
The researchers explain how tattoo pigments are picked up as "foreign bodies" by the body's immune system and are then stored in the skin and lymph nodes.
But they can't tell us what effects this process has on our health. The researchers weren't told any medical information about the donor samples, such as any diseases they had (including cancer) or the cause of donors' deaths.
The study also has other limitations. It looked at samples from a small number of people, and an even smaller number of controls.
And some of the findings might not be linked to tattoos – for example, higher levels of iron in the lymph nodes might come from blood within the samples, and aluminium in armpit lymph nodes could be from antiperspirants.
If you're considering getting a tattoo, it might be worth thinking about whether you want to introduce pigments that include metals into your body unnecessarily.
While we don't know much about the possible effects now, harmful long-term effects can't be ruled out.
As well as asking a tattoo artist about the hygiene of their tattooing equipment, it may also be worth asking them about the types of pigments they plan to use and what's in them.
Titanium dioxide, for example, is known to increase inflammation and can delay healing.