Exploring the Chemical Complexity and Toxicological Behaviour of Semi-permanent Make-Up Pigments: A Systematic Review

Semi-permanent make-up (SPMU), or micropigmentation, involves implanting pigments into the dermal layer of the skin for cosmetic enhancement. Unlike topical cosmetics, which are rapidly cleared from the body, SPMU pigments persist in living tissues, raising unique toxicological considerations. These pigments often contain complex mixtures of inorganic colourants and metallic elements, including titanium dioxide nanoparticles, chromium, cadmium and mercury. Their physicochemical properties strongly influence their biological interactions and potential toxicity. This narrative systematic review, guided by PRISMA principles, examined current evidence on the chemical composition, toxicokinetics and mechanisms of toxicity associated with SPMU pigments. Findings show that pigment physicochemistry is central to determining biological activity. Reported mechanisms of action include the generation of reactive oxygen species, DNA damage, inflammatory responses and systemic distribution of pigment components. Additionally, many studies indicate widespread noncompliance with regulatory limits, particularly concerning chromium and other metals. The review underscores the urgent need for internationally harmonised regulation of SPMU pigments, including mandatory nanotoxicological evaluations to assess biocompatibility and ensure consumer safety. Strengthening regulatory frameworks would also support alignment with Sustainable Development Goals 3 (Good Health and Well-being), 6 (Clean Water and Sanitation) and 12 (Responsible Consumption and Production). Furthermore, the findings highlight the essential role of Somatologists as intermediaries who guide safe practice, educate clients and promote responsible use of SPMU technologies.