After testing nearly 100 tattoo inks, researchers reported that, even when the ink bottles had ingredient labels, those ingredients listed on them were often inaccurate. The team also detected small particles that could be harmful to cells.
In the US, the Food and Drug Administration regulates tattoo ink, but in South Africa, tattoo ink [PDF] is imported largely unregulated.
The researchers presented their findings at a meeting of the American Chemical Society (ACS).
“The idea for this project initially came about because I was interested in what happens when laser light is used to remove tattoos,” said lead researcher John Swierk, PhD. “But then I realised that very little is actually known about the composition of tattoo inks, so we started analysing popular brands.”
Tattoo artists interviewed to see what they knew about the inks they use on their customers could quickly identify a brand they preferred, but they didn’t know much about its contents. “Surprisingly, no dye shop makes pigment specific for tattoo ink,” Dr Swierk explained. “Big companies manufacture pigments for everything, such as paint and textiles. These same pigments are used in tattoo inks.” He also notes that tattoo artists must be licensed in the locales where they operate for safety reasons, yet no federal or local agency regulates the contents of the inks themselves.
Tattoo inks are made up of a pigment and a carrier solution. The pigment could be a molecular compound such as a blue pigment; a solid compound such as titanium dioxide, which is white; or a combination of the two compound types such as light blue ink, which contains both the molecular blue pigment and titanium dioxide. The carrier solution transports the pigment to the middle layer of skin and typically helps make the pigment more soluble, sometimes controlling the viscosity of the ink solution and perhaps containing an anti-inflammatory ingredient.
Dr Swierk’s team has been studying the particle size and molecular composition of tattoo pigments. From these analyses, they have confirmed the presence of ingredients that aren’t listed on some labels. For example, in one case ethanol was not listed, but the chemical analysis showed it was present in the ink. The team has also been able to identify what specific pigments are present in some inks.
“Every time we looked at one of the inks, we found something that gave me pause,” Dr Swierk said. “For example, 23 of 56 different inks analysed to date suggest an azo-containing dye is present.” Although many azo pigments are not health concerns when they are chemically intact, bacteria or UV light can degrade them into another nitrogen-based compound that is a potential carcinogen, according to the Joint Research Centre, which provides independent scientific advice to the European Union.
In addition, the team has analysed 16 inks using electron microscopy, and about half contained particles under 100nm. “That’s a concerning size range,” said Dr Swierk. “Particles of this size can get through the cell membrane and potentially cause harm.”
After the researchers run a few more tests and have the data peer reviewed, they will add the information to their website “What’s in My Ink?” “With these data, we want consumers and artists to make informed decisions and understand how accurate the provided information is,” said Dr Swierk.
Source: American Chemical Society
