By Luke Andrews

Researchers found that nearly half of tattoo inks contain azo-compounds, which can degenerate under ultra-violet light into a chemical that could cause cancer. Many also contained particles small enough to get into a cell's nucleus and trigger cancerous mutations.

About three in ten Americans have tattoos, estimates suggest, but the industry is largely unmonitored by regulators. Blue and green tattoo dyes are already banned by regulators in the EU over potential cancer concerns. Tattoo ink may contain toxic cancer-causing chemicals, a new study finds.

Scientists at State University of New York (SUNY) found that nearly half of a 56-sample of tattoo inks they investigated had azo-compounds, which degenerate under ultra-violet light — emitted in sunlight — into cancer-causing chemicals.

Many also contained particles below 100 nanometers (nm) in size, which they said could get into a cell's nucleus and trigger cancerous mutations.

The tattoo industry is largely unmonitored in the United States, researchers say, despite up to three in ten Americans having one. In Europe blue and green pigments have now been outlawed over concerns they could cause cancer.

Someone getting a tattoo is already at risk of a bacterial infection because the skin is breached, or contracting a bloodborne disease — like hepatitis B and C — if equipment is not cleaned properly. Over time, recipients may also develop nodules or granulomas around the tattoo or scar tissue.

About two in five Americans already have a tattoo, with the numbers continuing to rise as body art gains social acceptance.

Little is known about what is actually in the inks used, researchers say, as the Food and Drug Administration (FDA) is not keeping a close eye on the industry.

The SUNY researchers investigated several popular tattoo inks and presented their findings Wednesday at the fall meeting of the American Chemical Society in Chicago, Illinois.

A tattoo is made up of two parts. The main piece is the pigment, which can be a molecular compound — like blue pigment — or a solid compound — such as titanium dioxide.

They also contain carrier fluids — typically alcohol-based — that bring the pigment into position between two layers of skin.

In the study, the scientists tested 56 inks and found several had substances that were not listed on the label.

In one case, ethanol — which can help thin blood — was spotted in the tattoo ink. It was unclear whether this posed any health risks.

Some 23 pigments — typically blues and greens — were also found to contain azo-compounds, which can become 'carcinogenic' if they are exposed to too much sunlight or lots of bacteria.

Dr. John Swierk, the chemist who led the study, told DailyMail.com: 'We don't necessarily know what the pigments break down into and so that's the real concern.

'It's possible that you might have pigments that by themselves are safe, but that photodecompose into something of concern.'

For the second part of the study, the scientists also investigated the size of particles in 16 inks used in tattoos.

This showed that half — including black pigments — had particles below 100 nm, which were 'concerning' because they could 'get through the cell membrane and potentially cause harm.'

Speaking at a press conference today, Swierk said: '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 added: 'Big companies manufacture pigments for everything, such as paint and textiles. These same pigments are used in tattoo inks.'

The scientists are now aiming to build the first comprehensive database of ingredients in different tattoo inks in the United States.

They have yet to investigate the impact of having a tattoo removed, which is typically done via a laser.

Specific concern was raised over two pigments — blue 15:3 and green 7 — which potentially caused cancer in 2020 amid warnings from some scientists. The European Union — which includes 27 European countries but not the UK — banned their use in tattoos in January.

But some authorities including those in Germany warned the ban was 'too far', saying more evidence was needed that they were potentially toxic. Tests by German regulators found both had a 'low level' of toxicity.

These colors remain in use in the United States, and there is no sign that authorities are moving to ban them.

American health authorities warn that getting a tattoo already poses several other health risks because the skin is pierced — opening up a risk of bacterial or bloodborne infection.

They also say in rare cases the tattoo can cause problems with an MRI scan, making it harder for doctors to diagnose conditions like cancer.

There may also be problems with having a tattoo removed, with the lasers potentially causing pain, blistering and crusting.

Swierck added: 'We have the same concerns [of cancer risks] about laser tattoo removal, since we don't understand how the laser is transforming the pigments.'