Ink composition and regulation might vary regionally. The original article mentions
> The most frequently used tattoo ink is black. Black ink typically contains soot products like carbon black, which is listed as possibly carcinogenic to humans (mainly based on studies of carbon black inhalation and risk of lung cancer) by the International Agency for Research on Cancer (IARC) [13]. Through the incomplete combustion used for carbon black production, polycyclic aromatic hydrocarbons (PAHs) are formed as byproducts. One of the most dangerous of these is benzo[a]pyrene (BaP), which is classified as carcinogenic to humans by the IARC [14].
You really don't want benzo[a]pyrene floating around your system, it's a potent carcinogen that's been firmly established by many studies. Some papers focus on directly on PAHs and tattoos, for example this PLoS One 2014 paper: https://pubmed.ncbi.nlm.nih.gov/24670978/
> The most frequently used tattoo ink is black. Black ink typically contains soot products like carbon black, which is listed as possibly carcinogenic to humans (mainly based on studies of carbon black inhalation and risk of lung cancer) by the International Agency for Research on Cancer (IARC) [13]. Through the incomplete combustion used for carbon black production, polycyclic aromatic hydrocarbons (PAHs) are formed as byproducts. One of the most dangerous of these is benzo[a]pyrene (BaP), which is classified as carcinogenic to humans by the IARC [14].
You really don't want benzo[a]pyrene floating around your system, it's a potent carcinogen that's been firmly established by many studies. Some papers focus on directly on PAHs and tattoos, for example this PLoS One 2014 paper: https://pubmed.ncbi.nlm.nih.gov/24670978/