After looking at a variety of popular tattoo samples for a new study, researchers found that nearly 50 per cent of the tattoo inks contained chemicals that could cause cancer.
At a meeting of the American Chemical Society in Chicago, Illinois, on Wednesday, researchers at Binghamton University presented their study, which was led by John Swierk, who is an assistant professor of inorganic chemistry at the school.
As noted by Swierk, there are two parts of tattoo inks: a pigment and a carrier solution. The pigment is a molecular or a solid compound, while the carrier fluids transport the pigment through different layers of the skin.
The scientist explained how he and his team went on to test 56 popular inks, before discovering that half of them contained a chemical that was not included on the label.
"Every time we looked at one of the inks, we found something that gave me pause," he told the ACS. "For example, 23 of 56 different inks analysed to date suggest an azo-containing dye is present."
Speaking to The Daily Mail about his work, Swierk noted that azo-compounds can degenerate when exposed to a lot of bacteria or under ultraviolet light, which comes through sunlight, and become "carcinogenic".
The chemist also acknowledged that there's still a lot to learn about pigments and how safe they are.
"We don't necessarily know what the pigments break down into and so that's the real concern," he said. "It's possible that you might have pigments that by themselves are safe, but that photo decomposes into something of concern."
In one sample, researchers detected ethanol, which can be used as a blood thinner, in the ink. However, it is still undetermined if that can put people's health at risk or not.
In the second part of the study, researcher investigated the size of the particles within 16 inks that are used for tattoos. They discovered that half of those inks had particles under 100 nanometers, which is "concerning" because the particles are then small enough to "get through the cell membrane and potentially cause harm".
At the meeting on Wednesday, shared via The Daily Mail, Swierk spoke about the small particles in the ink and how they could cause health problems, including cancer.
"When you get down to that size regime you start to have concerns about nanoparticles penetrating cells, getting into the nucleus of cells, and doing damage and causing problems like cancer that way," he said.
He also noted how there aren't any types of pigments that are used specifically for tattoos.
"Big companies manufacture pigments for everything, such as paint and textiles. These same pigments are used in tattoo inks," he added.
Earlier this year, the European Union banned the use of two pigments, blue 15:3 and green seven. The decision came after the company found that certain chemicals in the ink can cause "cancer or genetic mutations," with the ban put in place in 27 European countries. However, the colours are still being used in the United States.
From news to politics, travel to sport, culture to climate - The Independent has a host of free newsletters to suit your interests. To find the stories you want to read, and more, in your inbox, click here.