1. Introduction

1.1 Definition of tattoo ink:

Tattoo inks are defined as substances or preparations made from substances that are placed in or under the skin as a means of creating permanent markings and are intended to alter one’s appearance. Accordingly, tattoo inks used for conventional tattooing, as well as permanent makeup and inks for medical applications—particularly in plastic, aesthetic, and reconstructive surgery—fall into the category of tattooing agents.