Si alguien lleva tattoos de más de 10 años, es probable que simpáticos visitantes como el níquel, cadmio, plomo, hidrocarburo aromático policíclico, anilina, etc estén alojados permanentemente bajo su piel, al ser sustancias que se describen en estudios de la época.
https://mst.dk/service/publikationer/publikationsarkiv/2012/jun/chemical-substances-in-tattoo-ink/
En el 2016, la European Commission’s Joint Research Centre los seguía identificando en la composición de las tintas.
https://www.webmd.com/skin-problems-and-treatments/news/20160826/how-safe-tattoo-ink
Los propios tatuadores reconocen que a veces no pueden estar seguros de la tinta que utilizan.
"Tattoo artists also have concerns. “There are certainly really good producers of ink. But some of the inks on the market weren’t intended for tattooing. They just put them in a fancy bottle, put a dragon on the bottle, and write ‘tattoo’ on it,” said Jens Bergström, who has been a tattoo artist for 20 years and owns the Heavenly Ink Tattoo & Piercing studio in Åkersberga, Sweden. “That’s how easy it is, and that’s the danger,” said Bergström, who was a panelist at ESOF."
"The 118-page JRC report—which compiled surveillance, ingredient analysis, and adverse reaction data—found that
tattoo and permanent makeup products containing dangerous substances or contaminated by microbes “are available on the EU market."
https://cen.acs.org/articles/94/i33/chemicals-tattoo.html 
