Tattoo ink can migrate into lymph nodes and remain in skin for years, prompting an immune response the body cannot fully clear and potentially sustaining chronic inflammation.
Modern inks often contain industrial-use pigments, metal traces such as nickel and chromium, and compounds including azo pigments and polycyclic aromatic hydrocarbons that can provoke allergies or break down into potentially carcinogenic chemicals.
Colored inks—especially red, yellow and orange—are more often linked to persistent itching, swelling and granulomas, while black inks can contain carcinogenic hydrocarbons; laser removal or heavy sun exposure may worsen chemical breakdown.
Human evidence remains mixed: one observational study found tattooed people had a 29% higher melanoma risk, but researchers say no strong causal cancer link has yet been established.
The report also flags infection risks from broken skin and says limited regulation in many countries strengthens the case for stricter ink transparency, hygiene standards and more long-term safety research.