It turns out tattoos might not be as harmless as previously thought. New research reveals metallic nanoparticles from tattoo needles are slowly poising inked people.

A study published in the journal Particle and Fibre Toxicology indicates chomium and nickel particles from tattoo needles enter a recipient’s body and eventually amass around lymph nodes, where they’re held in place by ink particles from the tattoo. The infiltration can result in the formation of new allergies, the report states.

And while the presence of metal in lymph nodes will “poison” a person over time, the eventual severity of the damage is unclear, according to lead researcher Ines Schreiver. “The fact that all pigments and wear particles are deposited in lymph nodes calls for special attention to be placed on allergy development,” Schreiver says. “Unfortunately, today, we can’t determine the exact impact on human health and possible allergy development deriving from the tattoo needle wear.

These are long-term effects which can only be assessed in long-term epidemiological studies that monitor the health of thousands of people over decades.”

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