Tattoo Inks in General Usage Contain Nanoparticles

T. Høgsberg; K. Loeschner; D. Lö; J. Serup

Disclosures

The British Journal of Dermatology. 2011;165(6):1210-1218. 

In This Article

Abstract and Introduction

Abstract

Background To our knowledge tattooing has never been thought of as a method of introducing nanoparticles (NPs) into the human body by the intradermal route, and as such it has never been a topic of research in nanotoxicology. The content of NPs in tattoo inks is unknown.
Objectives To classify the particle sizes in tattoo inks in general usage.
Methods The particle size was measured by laser diffraction, electron microscopy and X-ray diffraction.
Results The size of the pigments could be divided into three main classes. The black pigments were the smallest, the white pigments the largest and the coloured pigments had a size in between the two. The vast majority of the tested tattoo inks contained significant amounts of NPs except for the white pigments. The black pigments were almost pure NPs, i.e. particles with at least one dimension < 100 nm.
Conclusions The finding of NPs in tattoo inks in general usage is new and may contribute to the understanding of tattoo ink kinetics. How the body responds to NP tattoo pigments should be examined further.

Introduction

Millions of people worldwide are tattooed. An American study found that up to 24% of persons aged between 18 and 50 years had tattoos.[1] A recent Danish survey showed that 13% of people aged between 15 and 25 years were tattooed.[2] In 2002, the Danish Ministry of the Environment identified the 17 most common pigments used in tattoo ink in Denmark. The report concluded that all the colorants were pigments as opposed to dyes. Pigments are mostly crystalline particles with insolubility as a key property, which makes them useful as permanent tattoo inks. If a pigment is degraded into molecules it loses its colour.[3,4]

In the literature, the unregulated chemistry as well as the unknown effects and consequences of tattoo ink have been addressed.[5,6] In 2003 and 2008, the European Commission published guidelines on the chemical composition of tattoo inks.[7,8] These recommendations were adopted by Switzerland, Germany and the Netherlands in modified versions.

Nevertheless, the pigments used for tattooing seem well tolerated by the skin with few complications reported in the medical literature.[9] No clear relationship between tattoo exposure and skin cancer or cancers in general in humans has been established. Case reports on malignancies such as melanoma, basal cell carcinomas, squamous cell carcinomas and keratoacanthomas have been published.[10–13] However, malignancies in tattoos are likely to be a matter of simple coincidence rather than causality.

A few studies have investigated the size of tattoo pigments by transmission electron microscopy (TEM) and found a particle size range of 10–5000 nm in both in vitro and in vivo experiments in biopsies from tattoos in humans.[14–16] The in vivo studies found black pigments < 100 nm situated in intracellular lysosomes. It is commonly agreed that nanoparticles (NPs) are defined as particles with at least one dimension < 100 nm.[17] NPs in tattoo inks have not been a topic of research in nanotoxicology. To date, there has been no systematic measurements of particle sizes in a panel of commonly used tattoo inks and the content of NPs in tattoo inks is therefore unknown.

Traditionally, risk assessments regarding NPs have dealt with exposure from inhalation, ingestion and absorption through the skin.[18] Currently, there is increased use of nanomaterials in many useful applications such as food and medicine. NPs are for example considered as medicines for drug targeting.[19] However, these same nanostructure-dependent and desirable properties may potentially lead to nanostructure-dependent biological activity that differs from and is not directly predicted by the bulk phase of the same chemical.[20] Typically, the biological activity of particles increases as the size of the particles decreases.[21]

We wish to stress that this study should not incite fear in the large population of individuals already tattooed as millions and millions of tattooed people have not experienced adverse consequences, and the overall safety profile of tattoos is remarkably high.

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