What are the molecular differences between permanent makeup pigments and tattoo inks, and why are they eventually eliminated from the body?

Permanent makeup (micropigmentation) dyes are pigments with a much smaller molecular size than tattoo inks, usually water or glycerin-based, and containing organic and mineral ingredients. Tattoo inks contain heavy metals and are injected into the deepest layer of the skin, the “subdermis” (reticular dermis); therefore, they are permanent. Permanent makeup pigments, on the other hand, are deposited in the more superficial layer of the skin, the “epidermis-dermis junction” (papillary dermis). These pigments are broken down and eliminated naturally from the body over time by macrophages and the skin’s natural shedding/renewal cycle; therefore, their permanence is not lifelong, but lasts between 1-3 years.