Photo by: ilovetattoos from Pixabay / March 28, 2018
Tattoos are now a common way for people, especially younger adults, to express themselves. As millions of people dive into tattoo culture, it raises an important question: What actually happens to the ink once it enters the body?
There has been increasing concern about tattoo safety, partly because there’s still very limited research on the long-term health effects of tattoo ink. Some studies have indicated that tiny pigment particles can travel from the skin into nearby lymph nodes and, in some cases, even enter the bloodstream, potentially affecting other organs. Researchers are still investigating whether these deposits have harmful effects on our skin, immune system, or internal organs. Different ink colors also carry their own potential risks. For example, black ink might contain carbon black, which could be a potential carcinogen, while red, blue, and yellow inks can break down into harmful substances when exposed to sunlight or during laser removal.
One emerging concept in this area of research is the “ink deposit hypothesis.” Essentially, tattoo ink particles can remain in the skin for years and may move to lymph nodes or other tissues. These deposits may trigger an immune response, leading to low-level inflammation in surrounding areas. Over time, this persistent inflammation may contribute to abnormal cell growth and an increased risk of cancer.
To determine whether tattoos may raise the risk of cancer, researchers examined data from the Danish Twin Tattoo Cohort (DTTC), which started in 2021. Twins were used for the study because comparing one twin who has cancer to their twin who doesn’t helps separate genetic and shared environmental influences from the effects of tattoos. Both identical and fraternal twins were part of the sample, making the study more robust. Participants provided information through questionnaires about their tattoos, including their presence, size, colors, and the age of their first tattoos, as well as lifestyle factors like smoking, drinking, exercise, and education. The focus was on skin cancers, basal cell carcinoma (the most common type of skin cancer), and lymphomas because tattoo ink is known to settle in the skin and lymph nodes, which could trigger chronic immune reactions that, in turn, might increase cancer risk.
To ensure accurate results, the researchers only considered tattoos obtained before a cancer diagnosis, thereby ensuring a more precise exposure assessment and avoiding any confusion from tattoos added after someone already had cancer. The study also considered tattoo size (small vs. large) and color, though assessing the impact of individual pigments was challenging, as many tattoos use multiple colors.
The findings were noteworthy: tattooed individuals exhibited an elevated risk of skin cancer and lymphoma, with larger tattoos associated with a higher risk than smaller ones. In particular, the twin study showed a noticeably higher likelihood of developing skin cancer, especially basal cell carcinoma, supporting the idea that pigment left in the skin and lymph nodes could trigger chronic low-grade inflammation. Even seemingly harmless tattoos may gradually deposit small amounts of pigment beyond the skin over many years, potentially contributing to an increased cancer risk. However, when viewed in the broader context of population-level data—such as reports from Nordic countries where more recent birth cohorts do not show marked increases in age-specific rates of non-Hodgkin lymphoma or non-melanoma skin cancer—any contribution from tattoos appears too subtle to meaningfully influence overall cancer trends.
However, the study has limitations. For certain cancers, such as bladder and urinary tract cancers, there were too few cases for a thorough analysis. The questionnaire didn’t distinguish between decorative, cosmetic, or medical tattoos, which may introduce bias. Additionally, sun exposure, a major factor for skin cancer, was not tracked. The study included only cancer survivors and participants born after 1960, which may limit its generalizability.
A few practical considerations arise from this research. Tattoos could potentially delay the detection of cancer, as the ink may conceal early skin lesions. Laser removal may release more ink particles into the body. There’s also an unconfirmed chance that ink could reach a baby during pregnancy or breastfeeding. These uncertainties highlight the need for further research into ink composition, safer removal techniques, and long-term health implications.
Public health initiatives could help reduce these risks. Since the choice to get a tattoo often stems more from cultural and environmental influences than genetic factors, awareness campaigns might be effective. Until more solid evidence is available, caution is advised for anyone considering getting or removing tattoos.
As tattoos continue to gain popularity, understanding the long-term health implications is essential. Ongoing research into safer ink formulations, removal methods, and biological pathways may help ensure safer tattoo practices and better public health guidance in the future.
Written by Niyayesh Tajoddini, a Biotechnology student focusing on molecular sciences and public health.
Article edited by Priscilla Wong, a Fourth-Year Biological Sciences (Immunology) student at the University of Edinburgh, and an Online News Editor for EUSci.
Resources:
Clemmensen, S. B., Mengel-From, J., Kaprio, J., Frederiksen, H., & von Bornemann Hjelmborg, J. (2025). Tattoo ink exposure is associated with lymphoma and skin cancers – a Danish study of twins. BMC Public Health, 25, 170. https://doi.org/10.1186/s12889-025-21413-3
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