Background
Tattooing is an increasingly popular lifestyle trend: More than 20% of young adults in France and Germany are tattooed. In recent years, public concerns multiplied whether tattoos could cause cancer in humans, particularly lymphoma and skin cancer.
Tattooing involves the needle-assisted introduction of complex ink mixtures into the dermis. Chemical analyses repeatedly identified primary aromatic amines (PAAs), polycyclic aromatic hydrocarbons (PAHs), and metals in inks: substances classified as human carcinogens by the IARC Monographs program. The intradermal exposure to these compounds—distinct from oral or inhalational uptake—remains poorly understood. Following tattooing, insoluble pigments persist lifelong in the skin and accumulate in regional lymph nodes and potentially other organs.
To study whether tattooing impacts future cancer risks, we set up three cohort studies, all nested within existing population-wide cohort infrastructures: the French and German national cohorts Constances and NAKO, as well as the US Cancer-Prevention 3 (CPS-3) cohort. First insights from French Cancer Risk Attributable to the Body Art of Tattooing (CRABAT) study are presented here.
 
Objectives:
To investigate the effect of tattooing on skin cancer risks in the CRABAT study.
 
Methods: CRABAT collected tattoo exposure data in two phases: Minimal exposure data was assessed in the whole Constances population during annual follow-up in 2020/21. In a second wave, detailed tattoo information was collected via the validated EpiTAT questionnaire in 2023. Skin cancers overall, cutaneous melanoma (CM), and non-melanoma skin cancer (NMSC) diagnosed during 2007–2021 were retrieved from national health insurance data. As exposure was collected after possible disease ascertainment, risks of skin cancer with prior tattoo exposure were assessed using logistic regression and Cox proportional hazards models in a retrospective cohort design. All analyses were adjusted for common skin cancer risk factors retrieved from the Constances data pool.
 
Results: In total 1789 skin cancer diagnoses (1.6%; 693 CM, 1096 NMSC) were recorded among 111074 participants. Cumulative incidence percentages for all skin cancers and per subtype were higher in non-tattooed compared to tattooed individuals, overall and stratified by age group (+/- 45 years). The tattooed participants were generally more exposed to skin cancer risk factors.We did not find an association between binary tattoo exposure (yes/no) and any skin cancer type. In the highest exposure category of tattoo body surface (>2 hand palms), 2 cases were observed among 1633 participants (0.1%), yielding an odds ratio of 0.21 for overall skin cancer (95% CI: 0.05–0.83; reference no tattoos); The corresponding hazard ratio from the Cox model was of similar magnitude, though not significant (HR=0.26, 95% CI: 0.07–1.05).
 
Conclusion: Our results are suggestive of a protective effect against skin cancer. While counterintuitive at first, biologically plausible mechanisms exist. These mechanisms may include absorption of ultraviolet and high energy visible light radiation through dermal pigment instillations, but also positive effects of tattooing on immune surveillance mechanisms.