An estimated 40% of Danish women and 33% of men have obtained tattoos by the age of 25. Overall, about 14% of the Danish population, or 600,000 people, has a tattoo.
The most frequently used tattoo ink is black. Black ink contains carbon black and benzopyrene, which have been listed as possible carcinogens by the International Agency for Research on Cancer (IARC). Colored inks contain azo compounds that may release carcinogenic aromatic amines following exposure to sunlight or laser treatment to remove tattoos.
Tattoo ink doesn’t remain confined to the skin. Instead, ink particles migrate to the lymph nodes, where they accumulate over time. The immune system recognizes the particles to be foreign substances. Tattoo ink may trigger chronic inflammation in the lymph nodes and eventually weaken the immune system.
A collaborative study by researchers from the University of Southern Denmark’s Department of Public Health and Department of Clinical Research, along with the University of Helsinki, examined the possible health effects of ink migration. The study was based on data from the Danish Twin Tattoo Cohort, where researchers had information from more than 5,900 Danish twins. The Danish Twin Tattoo Cohort was linked to the Danish Cancer Registry so that it could analyze cancer occurrence among the participants.
The researchers were able to compare twin pairs where one had cancer, but they otherwise had similar genetic factors and environmental influences. The major finding of the study was that individuals with tattoos were more frequently diagnosed with skin cancer and lymphoma compared to those without tattoos. The risk of developing skin cancer was 1.62 times higher among tattooed than non-tattooed participants. The bigger the tattoo and the longer it existed, the greater the risk of malignancy. Large tattoos were defined as those bigger than the palm of the hand. The risk for developing skin cancer was 2.4 (95% CI 1.1-5.1) times higher and the risk of lymphoma was 2.7 (95% CI 1.3-5.6) times higher for individuals with large tattoos compared to those without tattoos.
Reference
Clemmensen SB et al.Tattoo ink exposure is associated with lymphoma and skin cancers – a Danish study of twins. BMC Public Health, January 15, 2025; 25:
DOI: 10.1186/s12889-025-21413-3
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