How do tattoos affect our immune system?

Humans have been tattooing their skin for thousands of years, and the practice has grown in popularity across the world in recent decades.

However, tattoos don’t come without risks to our health and immune systems, experts say.

The risk of contracting an infection or disease via unsanitary or cross-contaminated tattoo needles is well documented, but those risks have declined over time as more sophisticated hygiene standards have been implemented globally.

Less is known, however, about the long-term impacts of tattoo ink once it enters the human body and how it interacts with our immune system once it’s there.

Research has found that certain substances in tattoo ink can be identified by immune cells and carried to the lymph nodes, where they can accumulate over time.

A recent study published in the medical journal Immunity & Inflammation found that this process can “induce a prominent and long-term inflammatory response.”

The study also found that the presence of tattoo ink at the site of vaccine injection “modulated immune responses in a vaccine-specific manner.”

Researchers said they observed a reduced response to the COVID-19 vaccine but an enhanced response to the UV-inactivated flu vaccine, “reflecting differences in the mechanisms of action between these vaccine classes.”

University of Western Ontario chemist Yolanda Hedberg, who was not associated with the study, said anything that causes inflammation is generally not good for tissue, as it can increase the risk of other diseases including cancer and neurodegenerative conditions.

What is in tattoo ink?

Like needle hygiene, tattoo ink itself has become generally less dangerous over time, Hedberg told CTVNews.ca in an interview.

“Older tattoos (from) 100 years ago were containing chromium-6 and nickel and all those bright metal oxide pigments that can be quite highly toxic. Some of them like lead chromate are very toxic – we have gotten rid of most of those,” Hedberg said.

Modern tattoo ink contains a variety of coloured pigments, which Hedberg said are essentially dyes that are contained within a shell so that they remain intact and do not dissolve within the skin once injected.

Those pigments typically contain azo dyes, which are classified as synthetic organic compounds used to add vibrant colour to things like processed food, cosmetics and paints.

Hedberg said that tattoo inks today present significantly lower health risks compared to the older more toxic ones, “but they still have a risk, and the main risks with them are two parts; one is allergy and the other is cancer.”

Allergic reactions, which encompass a wide range of immune responses to substances the body deems unsafe, are the most common negative effects reported by people who have gotten tattoos, Hedberg said.

“The problem with allergies is that you don’t know if you will develop it, and if you develop it, you can’t get rid of the tattoo,” she said.

“Even if you laser it away, it just distributes the dye in your body, so, you get the allergy everywhere. It’s not solvable.”

Do tattoos increase cancer risk?

Hedberg said that the risk of severe reactions or complications from tattoos remains relatively rare, and tattoos have yet to be linked directly to the development of specific cancers. However, recent research has suggested that tattoos can increase someone’s risk of getting the disease.

“In the past five years, we have had several studies that came out that were long term, and they all found a slightly increased (cancer) risk,” she said.

“One of the most convincing studies was a twin study in Denmark, where they basically looked at twins and those that were tattooed versus those that were not, and they clearly saw an increased risk.”

The study, published in January of last year, looked at more than 2,000 twins born between 1960 and 1996. Researchers concluded that the data suggested “an increased hazard of lymphoma and skin cancers among tattooed individuals.”

“It’s not a big risk compared to smoking or something, of course, it’s not that big, but it is a statistically significant increased risk,” Hedberg said.

Despite these findings, current evidence continues to suggest that tattoos represent a “relatively low” overall health risk, Hedberg said, noting that some amount of risk exists in almost every aspect of life.

“Having a tattoo is increasing some health risks slightly,” she said, “but not very much.”