A temporary tattoo might be the only way to get a blue or green tattoo in Europe for a while.
A recent ban on some ink ingredients with links to potential health effects has wiped
out lots of colors, but most notably two important blue and green pigments that
are really hard to find good replacements for. What are they, why are they banned,
and where does tattoo chemistry go from here? We got glucose sensing,
pH sensing, sunblock reapplication sensing. It's about to be a lot more than just artwork.
[Ding sound] Should have. Should've put this on the other way around.
First, let's just quickly talk about how tattoos work. A solid pigment is
suspended in a liquid carrier and an artist uses a needle to insert that ink into the dermis layer of
the skin, leaving the solid pigment behind. It's important that the pigment isn't water-soluble,
so it doesn't just dissolve away in your body. The pigment molecules are also too
big for the immune system to break them down effectively, so they get trapped there in cells
called fibroblasts and macrophages. This leaves behind a permanent mark.
Now, your tattoos might fade a little bit due to exposure to UV light degrading
down those molecules or fibroblasts dying off over time. But typically,
once you've got a tattoo, it's going to hang around for a long time.
The pigment molecules used in tattooing have historically been pretty lightly regulated.
The FDA considers tattoo inks to be cosmetic products. Easy, breezy, beautiful. Tattoo ink.
So in the US it doesn't have to approve an ink before it goes on the market. Instead,
it'll just step in if a problem comes up. Though there are a lot of things like hygiene
and sanitation that regulatory bodies do take very seriously when it comes to tattooing.
The laid back approach might not be the best in all cases since multiple
studies have found that some inks don't contain the pigments that they say they
do or contain additional unlisted ingredients, occasionally things like heavy metals. Not good.
This approach might be about to change however. A new act called the Modernization of Cosmetics
Regulation Act of 2022 was just signed, and it increases FDA oversight on things like
cosmetics and tattoos. But in Europe, things have already started to change.
In early 2022, a set of European Union regulations called REACH started to regulate which tattoo
pigments could or couldn't be used. It took a much more proactive approach than what we have
here. The new regulations say that there needs to be evidence the pigment is safe in order to
be used rather than just an absence of evidence that it's harmful. At the time REACH banned 25
different tattoo pigments that fell mostly in the red, orange, and yellow color space. These
were mostly pigments that contain azo bonds. Is it azo or azo? I really do think it's azo.
No azo. Azo or azo.
These were mostly pigments that contain azo bonds, double bonds between nitrogen atoms.
In these pigments, the azo bonds are connected to aromatic compounds. The azo bonds can break
down when exposed to light, degrading the pigments and releasing aromatic nitrogen compounds that are
known to cause cancer. Considering there were other safer replacements out there for many of
these pigments, the ban wasn't a huge deal in the tattooing industry. It was just kind of annoying.
But in January of 2023, additional pigments were added to the banned list,
including blue 15:3 and green 7. Unfortunately,
there aren't really good substitutes for these colors and tattoo artists are incredibly worried
about finding replacements for them. Bad news for tattoos today guys.
So the EU banned a couple of chemicals. Hard to say goodbye to these inks today.
It also won't just affect blue and green inks. Lots of ink colors,
including purples and pinks and browns also include those pigments to get
the colors just right. So palettes are about to get a lot more muted.
Okay, so why is the EU worried about the safety of these two molecules specifically? Well, first,
let's take a look at their structures. This is so ugly. Clearly not a chemistry teacher.
You can see that they each contain a copper atom right in their centers.
This makes a lot of sense for a blue or green pigment. Think of the beautiful
green patina of the copper Statue of Liberty. Originally from the EU. The
copper atom is held inside a phthalocyanine structure. These structures are widely used
as dyes because of their intense blue and green colors, and they look pretty
similar in structure to another green pigment you're probably familiar with, chlorophyll.
These pigments are pretty stable when exposed to visible and UV light. But with intentional
laser tattoo removal, these compounds can degrade into things like benzene and hydrogen cyanide.
Benzene can interfere with cell and immune system functioning. And hydrogen cyanide,
literally a hydrogen stuck onto a cyanide molecule can mess up all kinds of things like
cellular respiration. This means that the cell's whole energy source is just cut off. It's bad.
A 2015
study found that as the hydrogen cyanide levels increased, cell viability decreased. The cells
died. Not ideal. But this study used a very strong laser to break down these pigments and
then separately looked at how hydrogen cyanide affected cells in a dish. And the authors
themselves even note that things like tattoo size, pigment concentration, and the amount
of light exposure could all impact how much or how little cyanide is produced in your body.
Interestingly, there have been reports of people having adverse effects after
getting blue and green tattoos removed, including one case report
where the patients experienced lymph node swelling after the removal. But typically,
this resolved on its own. And while these pigments are typically pretty stable in UV light,
it just doesn't hurt to always put sunblock on your tattoos, keep them healthy and bright.
Surprisingly though, these breakdown products aren't what got these two pigments added to
the EU's no-no list. The REACH regulations want proof that a pigment is safe before
it can be used. But there isn't that kind of data for these two pigments.
These pigments were part of some older research potentially linking pigments in permanent hair
dyes to bladder cancer. Now, I should note that this older research doesn't specifically call out
these two blue and green pigments. In fact, the research didn't specify which pigments in the hair
dye could be causing cancer. So European Cosmetic Regulations banned all of them,
almost all of them, not all of them. So there wasn't really specific data
saying that they were harmful, but there also wasn't clear data saying that they were safe.
A 2020 analysis by the German Federal Institute for Risk Assessment reviewed
these two pigments and found them to have a low level of toxicity, but they also acknowledged
that there just wasn't a lot of data. So because there wasn't this whole big pile of safety data,
the REACH regulations decided to be cautious and added these to their banned list as well.
So until someone can submit data proving that they're safe, the regulations are
sticking with the conservative approach of not using them. Some tattoo artists have started a
petition to save them, not just because they want to keep using these pigments,
but also because they're worried that because there aren't great safe replacements,
artists might start using other even less regulated ingredients as a substitute.
So the industry needs to find some substitutes, but that is harder than it sounds. It's not
that there's something intrinsically unsafe about blue or green pigments,
but there just aren't other options on the market right now. This is more of a business and
historical problem than a chemical one. Companies don't make tattoo specific pigments. Instead,
ink makers have to purchase pigments made for other uses. Things like iron
oxides for brown colors, carbon black for blacks, and titanium dioxide for whites.
So the pigment manufacturers aren't doing tattoo specific safety trials.
Ink makers have had to choose pigments kind of through trial and error to see which ones are
best at holding up their color over time and result in few to no negative reactions when
injected into the skin. This isn't going to be enough for regulators going forward,
and unfortunately, despite the tattoo industry beginning to ask for these kinds of studies,
there's just not a lot of tattoo research cash floating around in
order to pressure big companies to either make new pigments or study the ones that they have.
But there is research on lots of really fascinating inks that can
react with your body and environment to not just create a pretty picture,
but also tell you something about what is going on inside of you.
For example, a group in Germany published a paper that uses specific molecular inks to create
embedded sensors in the skin to detect changes in blood chemistry, looking for things like albumin,
which is a main component of your blood plasma, pH, and glucose levels. Imagine having a tiny
tattoo that changed color from yellow to green as your blood glucose increased, giving
diabetics a peek at what's going on inside their metabolism without having to prick their fingers.
The process works by tattooing three molecules into the skin, glucose oxidase, peroxidase,
and 3,3′,5,5′ tetramethylbenzidine or TMB. And this is a compound often used in research
labs as a colored indicator. So when glucose is present, it's oxidized by ambient oxygen and the
G-O-D to become D-gluconolactone. Gluconolactone. D-gluconolactone. Stuttered there. So when glucose
is present, it's oxidized by ambient oxygen and the G-O-D to become D-gluconolactone. Great.
Now this reaction also produces hydrogen peroxide. Now that hydrogen peroxide works
with the P-O-D to oxidize the TMB, and this gives off a blue-green dye. Can we just use
this as a pigment replacement? No, not unless you want your yellow sunshine to sometimes turn
into a green dye. That's not great. So the more glucose is present, the darker green the tattoo.
Currently, this is just proof of principle in pig skin, but it could be used in the
future to give diabetics a quicker look at what their blood sugar looks like.
There are also some groups that have been developing inks that react to
ultraviolet light, like the kind of light giving you a sunburn on
your beach day in order to make simple sensors for when you need to reapply
your sunscreen. Now one is a blue ink that complies with the new regulations,
but it only appears in sunlight. That's good for testing when you need more sun protection,
but not so good for keeping your blue smurf tattoo or my fancier Reactions tattoo looking
good. For now though, I think I'm going to get a tattoo that just tells you to like, comment and
subscribe right across my forehead so you never forget to do the ... Ah, we don't do that here.
I don't know if that was useful. I hope it was.