Tattooing is one of the oldest forms of body art and self-expression known to humans. Otzi the Iceman, whose 3,300-year-old body was found perfectly preserved in the Alps, had over 60 simple tattoos made by rubbing soot into tiny cuts in the skin.
Cultures and civilizations around the globe have used tattoos as a part of self-expression, religious and spiritual traditions, and as a form of tribal identification. Apart from the pain associated with getting inked, tattooing was always a risky business.
In pre-modern times, the risk of contamination and infection was relatively high. Although traditional tattoos use natural ingredients, they could still contain toxic heavy metals or allergens that are dangerous to vulnerable individuals.
While modern tattooing equipment and practices considerably reduce the chances of infection, the synthetic dyes used today come with a whole bouquet of new concerns. For instance, some dyes have the potential to break down over time into carcinogenic amines.
This would not have been that much of a concern just 100 years ago when tattoos were restricted to specific groups like sailors, soldiers, and circus/carnival folk. The world today is vastly different, with 32% of American adults having at least one tattoo.
In this context, any increase in cancer risk posed by tattoo ink can be considered a matter of public health. This is why I feel it necessary to draw your attention to a recent study conducted by researchers at the University of Southern Denmark.
A Cancer Risk Study Using the World’s Best Twin Registry
The University of Southern Denmark (SDU) has the unique distinction of hosting one of the most comprehensive health databases of twins in the world. Started in 1954, the Danish Twin Registry tracks the health data of over 175,000 twins born in the country.
Twins, particularly identical twins, are highly valued in medical research since they offer an excellent natural control group. Diseases like cancer have both genetic and lifestyle/environmental causes that make comparison difficult between individuals.
Since twins have nearly identical DNA, if one twin catches a disease we can attribute it to environmental or lifestyle causes with a greater degree of confidence. In the case of tattoos, this would involve creating a group where only one twin has ink on their body.
Another study conducted in Denmark in 2021 proved highly useful for this purpose – the Danish Twin Tattoo Survey. Designed to look at the cultural and environmental factors that lead to tattooing, the study established a cohort of 9,000+ twins.
The SDU research team looked at the health data of twins picked from the Danish Twin Tattoo survey. This was collated with additional health data collected from the Twin Registry and the Danish Cancer Registry.
Two separate studies were conducted – a smaller case-cotwin study involving 316 twins born between 1960 and 1996, where at least one twin had been diagnosed with cancer by age 20; and a larger cohort study involving randomly selected 2,459 twin pairs.
The team primarily focused on the following types of cancers – lymphomas, skin cancers, and basal cell carcinomas. Smoking was also included as a compounding risk factor since smokers are more likely to get a tattoo according to the Twin Survey.
Tattoo Size is A Major Factor in Determining Cancer Risk
The cancer risk from tattoos is mainly due to the impact ink particles have on the body. Over time, they can travel to nearby lymph nodes and accumulate. This can set off inflammation, which over time, raises the risk of lymphomas.
The SDU study showed a clear indication of the impact tattoo ink can have on the lymph nodes over time. In individuals with larger tattoos (bigger than the size of a palm), the hazard rate for lymphomas was three times higher than those individuals who don’t have any tattoos.
A larger tattoo means your body has a greater volume of ink in the subdermis. With larger tattoos like “sleeves”, backpieces, and full-body suits, your lymph nodes are at higher risk of accumulating more ink particles over time.
The risk of developing skin cancer is also nearly doubled with larger tattoos (around 137% to be precise). With tattoos smaller than the size of your palm, the detected risk level for skin cancers was significantly lower at 65%.
The Role of Specific Colors Need Further Evaluation
Tattoo artists in the past had to make do with a very limited palette of colors sourced from natural ingredients like charcoal or soot (black), iron oxide (red), plant extracts (green), and other minerals (blue, yellow).
In stark contrast, a tattoo artist today has access to hundreds of different synthetic colors, available in metallic, pastel, muted, glow-in-the-dark, and many other shades. You can now have inky black and pure white tattoos, which were not easy to achieve in the past.
The catch – many of these pigments were originally created for industrial and other commercial applications. Black ink, the most widely used shade, is also the most problematic as it can contain potential carcinogens (polycyclic aromatic hydrocarbons).
Similarly, heavy metals like mercury (red pigments), lead (yellow and green), and cadmium (orange) are all toxic ingredients often found in tattoo ink. Large and elaborate tattoos often contain multiple colors, which can make accurate risk assessment difficult.
Key Takeaways of the SDU Study
Very few studies have looked at the correlation between tattoos and cancer. The main takeaway of the SDU study is that getting larger tattoos at a younger age (teens or early twenties) may increase cancer risk as one gets older.
With the popularity of tattooing on the rise, we need more research into the potential impact pigments can have on the human body in the long term. More importantly, government regulators need to take a closer look at the pigments being used in tattoo ink.
Meanwhile, the best option for ordinary consumers might be to exercise caution and restraint about getting inked. Avoiding very large tattoos that involve a lot of black and red ink could be a good idea, especially at a young age to reduce long-term exposure.
