Toxic ink used for tattoos could seep into the body and increase the risk of cancer, experts have warned.
According to The Sunday Times nanoparticles enter via the bloodstream and settle in major organs - such as kidneys - causing them to stop functioning normally.
As many as five percent of tattoo studios are believed to use ink that contains carcinogenic compounds - such as colbalt and mercury - according to Times Of india.
Scientists are calling for greater regulation of tattoo dyes and Tattoo Ink Manufacturers of Europe group are campaigning to remove all carcinogenic ink from use.
Desmond Tobin, director of Bradford University's centre for skin sciences, was shocked to discover there was no regulation on inks, The Sunday Times reports.
"We need to do more work," he said. "But there is no question that these substances can be toxic."
Jorgen Serup, professor of dermatology at Copenhagen's university hospital, found carcinogenic chemicals in 13 out of 21 commonly used tattoo inks in Europe.
"Millions of Europeans are now being tattooed with chemical substances of unknown origin," he said "Until now, no one has really looked at the risks, and we need to get proper research going in this field."
"People should be given written information about the inks that are used on them. It may be that, like cigarette smoking, they still choose to take the risk, but they need to be informed," he said.