Yes / Tattooing has long been practised in various societies all around the world and is becoming increasingly common and widespread in the West. Tattoo ink suspensions unquestionably contain pigments composed of nanoparticles, i.e., particles of sub-100 nm dimensions. It is widely acknowledged that nanoparticles have higher levels of chemical activity than their larger particle equivalents. However, assessment of the toxicity of tattoo inks has been the subject of little research and ink manufacturers are not obliged to disclose the exact composition of their products. This study examines tattoo ink particles in two fundamental skin components at the nanometre level. We use atomic force microscopy and light microscopy to examine cryosections of tattooed skin, exploring the collagen fibril networks in the dermis that contain ink nanoparticles. Further, we culture fibroblasts in diluted tattoo ink to explore both the immediate impact of ink pigment on cell viability and also to observe the interaction between particles and the cells.

Previous reports have shown that several tattoo inks available on the Swedish market contain prohibited substances. Although the regulatory framework has been in place since 2012, there is a lack of clarity about whether the contents of tattoo inks meet regulatory requirements or not. The purpose of this study was to find out if an active supervision is conducted to determine if the regulations on tattoo inks are met, focusing on the content of prohibited substances. 43 Swedish municipalities were given a survey about their experiences in conducting supervision of tattoo artists. Most municipalities have used the regulation (2012:503) on tattoo inks. Parts that involves giving information to the customer, labeling of tattoo ink containers and sterility have been more common in the supervision than the parts related to control of the tattoo inks content. It is today difficult and time consuming to verify the state of tattoo ink contents and to compare with the available lists included in the legislation. The study suggests the introduction of a simpler, standardized method for investigating whether a tattoo color contains prohibited substances or not.

No / In this study, we have shown how particles in carbon black tattoo ink accumulate in the human skin dermis using fine-resolution atomic force microscopy, with which a single ink particle in the collagenous network can be imaged. This information further demonstrates that tattoo inks are nano-particles. Further, we have deposited a commercially available tattoo ink on a glass slide and calculated a range of volumes for single ink particles.