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Can tattoos protect your skin from the sun’s harmful rays, or do they make things worse? A new study I conducted with colleagues suggests there may be cause for concern. We found that people with tattoos had a 29% higher risk of developing melanoma, a serious form of skin cancer often linked to ultraviolet (UV) exposure.

However, tattoos did not appear to increase the risk of squamous cell carcinoma, another type of skin cancer related to UV damage. Although both cancers share a common cause, they arise from different cell types and differ in severity, with melanoma being far more dangerous.

Tattoos are a powerful form of self-expression and a cornerstone of modern identity. In Sweden, around one in three adults is tattooed, showing how body art has moved firmly into the mainstream. Yet despite their popularity, scientists still do not know whether tattoos have any impact on health, or how any potential effects might unfold over time.

Epidemiologists are now trying to answer these questions. The work is challenging because people who choose to get tattoos often differ from those who do not in ways that can influence health outcomes.

Another difficulty is that most health records do not note whether someone is tattooed, which means long-term patterns are hard to study. Without this basic information, it becomes difficult to know whether tattoos themselves play a role in health or whether differences are driven by other factors.

Melanoma and squamous cell carcinoma both develop slowly and are relatively uncommon, which makes long-term research challenging. Following large groups of tattooed and non-tattooed people for many years would be expensive and time-consuming. So our team used a different approach. We started with people who had already been diagnosed with cancer and looked backward to see who had tattoos. This type of research, known as a case-control study, is an efficient way to detect potential associations.

Sweden maintains high-quality national registers that record information on health and demographics. From the National Cancer Register, we identified everyone aged 20 to 60 who was diagnosed with melanoma in 2017 or squamous cell carcinoma between 2014 and 2017.

This included 2,880 melanoma cases and 2,821 squamous cell carcinoma cases. For each case, we selected three comparison people of the same age and sex from the Total Population Register, who had not been diagnosed with skin cancer.

We then sent questionnaires to all participants, asking about tattoos, including decorative tattoos, permanent makeup and medical tattoos, as well as their size, location, and age at first tattoo. This allowed us to establish whether someone had been tattooed before or after developing cancer.

A total of 5,695 people took part in the melanoma study (1,598 with melanoma) and 6,151 in the squamous cell carcinoma study (1,600 with that cancer).

People with tattoos were 29% more likely to develop melanoma compared with those without tattoos. The risk increase seemed to be highest in those who had tattoos for more than ten years, although the numbers were smaller in this group, so results should be interpreted cautiously.

For squamous cell carcinoma, tattoos made no difference. The results were consistent across analyses, suggesting no link between tattoos and this type of skin cancer.

We also found no evidence that larger tattoos increased risk. This was unexpected, since larger tattoos contain more ink and therefore more potentially harmful substances.

One possible explanation is that tattoo ink does not remain confined to the skin. The body’s immune system treats it as a foreign substance and transports some ink particles to the lymph nodes. These particles can stay there long-term. While we do not yet know whether this causes harm, it could potentially lead to chronic inflammation, which has been linked to cancer development.

Another explanation may be measurement error: people tend to overestimate tattoo size. Future studies using more precise measures may help clarify this.

Lifestyle and confounding factors

What makes this study unique is the range of lifestyle factors we could consider. We included data on sun exposure (both occupational and recreational), tanning bed use, smoking, education level, marital status and household income. We also factored in skin type, pigmentation, age and sex.

These details matter because they can influence both who gets tattoos and who develops cancer. For instance, people who spend a lot of time in the sun may be more likely to have tattoos and to develop melanoma. Accounting for these differences reduces bias and strengthens confidence in the results.

In research, this issue is known as confounding. If confounding factors are not properly controlled, they can distort findings and lead to misleading conclusions.

Recent US research suggested that large tattoos might even reduce the risk of melanoma, but that study did not control for key factors such as skin type or UV exposure. The results may therefore reflect behaviour rather than biology. For example, people with large tattoos may avoid sunbathing or tanning beds to protect their body art, which would naturally reduce UV damage.

Read more: Do multiple tattoos protect against skin cancer, as a recent study suggests?

So, do tattoos cause skin cancer? The simple answer is that we do not know yet. Our results suggest a possible link between tattoos and melanoma, but one study is never enough to prove causation.

More research is needed to explore potential biological mechanisms, such as chronic inflammation, and to examine how different types of ink or colours might interact with UV exposure. The composition of tattoo pigments varies widely, and many contain compounds that can break down into harmful by-products when exposed to sunlight or laser removal treatments.

If you have tattoos, there is no need for panic, but awareness matters. Continue to protect your skin from UV radiation just as you would otherwise: use sunscreen, avoid excessive tanning and check your skin regularly for new or changing moles.

Our findings highlight the need for long-term monitoring and better data collection on tattoos in health records. With tattoos now common worldwide, this is an important public health issue. Continued research into the biology of tattoos and their long-term effects will help ensure that people can make informed choices about their bodies, their art and their health.

This article is republished from The Conversation, a nonprofit, independent news organization bringing you facts and trustworthy analysis to help you make sense of our complex world. It was written by: Christel Nielsen, Lund University

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Christel Nielsen receives funding from The Swedish Research Council for Sustainable Development, The Crafoord Foundation, and The Magnus Bergvall Foundation.