07 October 2022

Tattoo Ink

Welcome back. Way back when, I blogged that I wasn’t wild about tattoos (see Temporary Tattoos Addendum). But I added: That’s not to say that I didn’t love temporary tattoo transfers when I was about 7 years old and they came in packs of bubble gum and boxes of Cracker Jack--even if you could just about wash them off. 

In those years, the only people I saw with tattoos (away from fairgrounds) were WWII veterans and later, veterans of the Korean conflict. Now, it seems that everyone has at least one tattoo (surveys vary, generally at least 30% U.S. population). And these tattoos don’t wash off. 

Poster of World War II veteran with D-Day tattoos for salute to Honor Flight Southland that transports California veterans from Los Angeles, San Bernadino and Orange counties to Washington, D.C. to visit their memorials (from www.tattoodo.com/articles/20-world-war-ii-tattoos-for-dday-4158).

In fact, as John Swierk, Ph.D., a Binghamton University chemistry professor points out, the inks used for today’s tattoos are not regulated in the U.S., even though tattoo artists must be licensed. The Food & Drug Administration classifies tattoos and tattoo ink as cosmetic products. 

Prof. Swierk and students in his lab have been studying the safety and photochemistry of tattoo inks. They have analyzed the composition of nearly 100 inks. He presented the results to date at this fall’s meeting of the American Chemical Society. I thought you’d find the topic and their work of interest.

A Bit About Tattoo Inks
Tattoos are inks, composed of a pigment dissolved in a liquid carrier, inserted into the skin to produce the color.

The carrier solution transports the pigment to the middle layer of skin, the dermis, and typically increases its solubility. It can also control the viscosity of the ink solution and may include an anti-inflammatory ingredient.

Tattoo’s depth into the dermis layer (from tattooing101.com/learn/tattoo-equipment/ink/).
The pigment could be a molecular compound, such as a blue pigment; a solid compound, such as white titanium dioxide; or a combination of the two, such as light blue ink. Tattoo ink pigments are manufactured by large companies and are the same as those used for everything, paint or textiles. No company makes pigments specifically for tattoo ink.

Prof. Swierk and the students interviewed tattoo artists and learned they could quickly identify the brand of ink they preferred, though they knew little about the ink contents.

Tattoo artist at work (from tattooglee.com/tattoo-needle-definition/).
Ink Analyses
To analyze the particle size and molecular composition of tattoo pigments, the researchers employed multiple analytical techniques (UV-visible, infrared, nuclear magnetic resonance and Raman spectroscopies; liquid chromatography and inductively coupled plasma mass spectrometries; microwave acid digestion, electron microscopy). They identified specific pigments in some inks and found ingredients not listed on the label (e.g., ethanol).

Their analyses frequently highlighted something disconcerting to Prof. Swierk. He reported, for example, that analysis of many inks suggested the presence of an azo-containing dye. While many azo pigments are not health concerns when chemically intact, they can be degraded by bacteria or ultraviolet light into another nitrogen-based compound that is a potential carcinogen.

Another example is that about half of the inks analyzed using electron microscopy contained particles smaller than 100 nanometers. Particles of that size can get through the cell membrane and potentially cause harm.

Tattoo removal is a general cause for concern. How the ink breaks down (e.g., after laser photolysis) and what products form are not fully known. Analytical techniques similar to those used to study pigments can be used for analysis, focusing on products potentially harmful to human health.

Laser tattoo removal (from thegardenmedspa.com/laser-tattoo-removal/).
Wrap Up
The researchers plan to complete testing, have the data peer reviewed, then add the information on the composition and potential risks of different inks to the website they developed, What’s in My Ink?

Their goal is to help the artists as well as consumers make informed decisions and understand the accuracy of the information.

Thanks for stopping by.

Exposing what’s in tattoo ink:
Article on EurekAlert! website with American Chemical Society meeting presentation abstract: www.eurekalert.org/news-releases/960976
YouTube video of review of work: www.youtube.com/watch?v=239bEv4pTTo&list=PL-qHxGvFeZV11YAygI6lgZ6yOq2nWwvv7&index=3

2020 article on tattoo ink safety from India’s myUpchar: www.firstpost.com/health/is-your-tattoo-ink-safe-7778391.html
2021 NPR article on tattoo ink safety: www.npr.org/sections/health-shots/2021/02/13/965549858/as-scientists-study-tattoo-ink-safety-europe-bans-two-widely-used-pigments
2021 systematic review of tattoo pigment degradation products in Journal of Exposure Science and Environmental Epidemiology: www.nature.com/articles/s41370-021-00364-y

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