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.

Should have.

Should 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.