Ah, it "reduce[s] the [refractive index] contrast between water and lipids, leading to optical transparency of live biological tissues." Craziest part being it was predicted using a classical optical model [1]!
Some tropical American frogs evolved to do it naturally (fam Centrolenidae). Some fishes also can do it also in a few different orders (Siluriformes and Perciformes at least), so in lower vertebrates it is possible and evolved several times.
But they have a different metabolism than ours and a mouse skin is much more thin than our own skin. I assume that this effect will work only on very small animals and the optical effect will hit some thickness limit somewhere. Could work on fingers but not in heart. At this moment my hype level is a 4 over 10.
But a few billion have ingested it in the past year, sometimes even in medical pill form to make yellow pills. Could be worse at higher doses but seems plausibly safe and worth further testing.
The poison, as they say, is in the dose... just speculating but the quantity of dye ingested versus that used to render skin transparent may be such that the former is relatively innocuous while the latter would be very harmful. In particular it seems to be genotoxic at relatively low levels so that would be concerning for use in humans.
I don't recall the case of anybody grabbing a doritos bag and seeing trough their fingers, but a lamp behind your hand definitely can turn your fingers translucent. Maybe with both effects combined?
The more valuable contribution here is probably the idea IMHO.
To know that the optical effects of the light can be manipulated with the correct stuff and we could search for it. An ointment seems of to be useful to a restricted volume, to maybe the first millimeters of the skin.
We evolved totally transparent proteins that are hard, resilient and harmless. We have them in the eyes so we know how to do it. If we could only suggest the body to temporarily accumulate those proteins in the upper layers of the skin, or we could inject temporarily the proteins in local areas of interest that would be awesome (and maybe safe as long as is our own human protein)...
On the skin the continuous shedding of the upper layers would probably self-fix the stuff.
I imagine it could eventually lead to a full invisibility serum, as documented in the classic Kevin Bacon film Hollow Man. Of course, we need to be aware of the side effects (mostly murderous rampaging).
You forgot blindness. If you're transparent, your eyes won't be able to refract light. Which is good if you also have homicidal urges, but awful if you get diarrhea.
(This might be the more desirable of the two outcomes. Otherwise you the man may be invisible, but everyone sees your intestinal contents floating in mid-air.)
The dose makes the poison. Considering that food usually don't make your tongue transparent [1], probably you need to use more than the usual amount to get the effect.
[1] Note that they get skin that is transparent only to one shade of red, it's not transparent to all the visible spectrum.
(1) "All things are poison, and nothing is without poison; the dosage alone makes it so a thing is not a poison."
(2) assume it isn't absorbed into the larger body. Still the tissue absorbing it got a YUUUUGEEE dose. Then presumably most of it is washed out minutes later. So under that assumption we worry about localized tissue damage ---- --- which, if we're talking about things like cancer patients here who commonly get zapped with X-rays and gamma rays and antimatter and such, is perhaps not out of the ordinary. If there's no systematic damage the main concern would be cancer. If the skin dies, it can be fixed. And heck, a lot of cancer treatments also cause cancer i.e. many children with blood cancers go onto later get other cancers due to the medicinal cure of their blood cancer side effect.
I’m surprised that this characteristic of an extremely common dye—being used in its main application, as a dye—hasn’t been described before. Surely there’s some limitation that’s obvious to those skilled in the chemical and biological arts?
Or is it really just a matter of serendipity waiting til now to lead anybody down the path of trying it this way?
The article says it's only to the depth it penetrates, so given that you have a lot of skin, comparatively, I'd guess it'd be hard to distinguish from the dye staining you weirdly for a bit.
on this point curcumin aka tumeric has a quite a similar though not perfectly the same wavelength-adsorption profile (i.e. anything with a strong yellow color)
tumeric / curcumin is often used a magic skin treatment type dealie. question is why are not all these wanting-to-have-youthful-skin type people discovering transparency! answer is below but TLDR human skin is thicker and doses are still low.
some main points from the paper( damned paywell, see supplement)
> the dye only goes about 1mm deep, so maybe that works magic in a mice but not so good in humans nor noticable.
> the dye comes it at arnd 0.5-1 molar solution. gmw is 500 g/mol ish. so 1M solution is 500g in 1L or 0.5g in 1 mL aka 500 mg in 1 mL. Okay, fine, you prepare this and rub 500 mg on your big toe from a little 1 mL aliquot. the daily limit or whatever for the food dye is around 4 mg! Soooo...
>on the latter point, safety, the supplement had a bunch of stuff where they were like "we did all the normal blood tests on the mice, and looked at the tissue, and looked to see if they died later, and it all looks good"
Maybe the concentration has to be high enough that this wouldn't happen often in practice? The point made below about mice having thinner skin makes sense too, though there are parts of the body where skin is quite thin, like ears and wrists.
I have a feeling that this will get tested by some intrepid YouTuber before the authors of the paper get approval from an ethics review board. I'll try to remember to Google this in a month or two.
>>The point made below about mice having thinner skin makes sense too, though there are parts of the body where skin is quite thin, like ears and wrists.
> At the moment, transparency is limited to the depth the dye penetrates, but Hong said microneedle patches or injections could deliver the dye more deeply.
It is stated to be slightly solvable in DMSO, so that may be already enough. Anyway, i've got the impression - layman from reading some related articles - with DMSO the solubility isn't that important in the sense that DMSO seems to be temporarily increasing physical permeativity of the tissues - kind of creates micropores - so that even some not very soluble stuff can probably get through. I have a small bottle of DMSO at home, wonder if should buy some Doritos on the way home :)
probably mixing dmso with tartrazine and rubbing it on thin skin. dmso is commonly used as an excipient to promote dermal penetration (of the stratum corneum) by drugs in topical preparations
UV damage to internal tissues seems unlikely given that the tartrazine dye they used absorbs strongly in the UV region of the spectrum. You can see this in Figure S1 A & B:
Also the abstract of the article notes that strong UV absorption is likely a prerequisite for this effect:
> We hypothesized that strongly absorbing molecules can achieve optical transparency in live biological tissues. By applying the Lorentz oscillator model for the dielectric properties of tissue components and absorbing molecules, we predicted that dye molecules with sharp absorption resonances in the near-ultraviolet spectrum (300 to 400 nm) and blue region of the visible spectrum (400 to 500 nm) are effective in raising the real part of the refractive index of the aqueous medium at longer wavelengths when dissolved in water, which is in agreement with the Kramers-Kronig relations. As a result, water-soluble dyes can effectively reduce the RI contrast between water and lipids, leading to optical transparency of live biological tissues.
However this kind of research into the effects of absorption bands on the transmission properties at interfaces might ultimately bring about more effective sunscreen formulations.
> UV damage to internal tissues seems unlikely given that the tartrazine dye they used absorbs strongly in the UV region of the spectrum
To expand: "the most hazardous UV radiation has wavelengths between 240 nm and 300 nm" [2]. While tartrazine has a lambda max at 425 nm in water [2], it has a second ridiculously-convenient peak around 260 nm [3].
TL; DR It should be mildly UV protective ceteris paribus.
like an x-ray, I'd risk that for a one-off doctors appointment, but I'd probably not risk it on my body at all times. maybe there are safer dyes that have the same effect
When my little brother was 3 or 4 he stepped on a nail in our yard, probably dropped during some recent construction. It went all the way through his poor little foot, straight through, out the top. I can see it, vividly, in my mind's eye. Mom scooped us up and rushed us, still barefoot, to the ER. I remember him being almost calm- not the way I would have reacted. They x-rayed his foot and soaked it in a tub of what I now know to be iodine to kill bacteria. I remember this clearly: it was the first time I'd ever seen an x-ray in real life, rather than just in alphabet books.
Fortunately the nail totally missed anything important, so they just pulled it out and bandaged him up- no worse for the wear. He went on to be an honest-to-God track star so it obviously didn't have any lasting effect.
Decades later we were talking about something and he said to me, "Why don't they use that x-ray water anymore?". I had no idea what he was talking about so I asked him to elaborate.
The way he remembers the incident is that they put his foot into a bucket of amber liquid and, once submerged, his skin became transparent. He looked in and saw his own bones, blood vessels, and- in the middle of it all- the nail that was causing such a fuss. He described wiggling his toes, flexing his ankle, and seeing the bones and tendons move, directly, with his own eyes.
His toddler brain, probably in shock, had combined the x-ray film and iodine bath. Over the years it had grown more detailed and reinforced. He described it with such clarity that I almost wondered if I hadn't been mistaken. He didn't believe me when I told him how I remember it. We called our mom who confirmed my version of events, plus did some googling, which finally convinced him.
Anyway I just sent him this article. It's interesting that not only is the x-ray water he remembers theoretically possible, it would actually be amber.
That's fascinating! I also have a vivid childhood memory that I can see, clear as day, despite knowing as an adult that it's impossible. It's really uncomfortable to combine the facts that a.) memory is unreliable, and b.) memory is what gives me my sense of self.
(if you don't accept that second fact, that's fine, I'm not here to convince anyone or debate)
Historically there were actually "live" x-ray machines, where you could have seen yourself wiggling your toes. They aren't used now due to the horrific exposure to x-rays, but before that was understood to be bad they were used in shoe shops (!). I don't know that they were ever used in hospitals though
And of course the most harmed by fluoroscopes weren't the customers (bad enough) but the sales staff, who had multiple daily exposures day after week after month after year.
Checking your Wikipedia link: Yikes! These were used into the 1970s.
And of course industry denialism of any possible harm the devices might cause....
It took several minutes and a couple tries to get the exposure right on certain shots. They didn't seem overly concerned about the exposure. The person operating the machine didn't seem at all worried about it, so I didn't worry either. Can't rule out that I should have!
These days the machine itself should also warn if it's on too long, so perhaps the operator was relying on that. These days even UV treatment gets added to your record so that further treatments don't accumulate too much. Well, it does in the UK at least.
> UV treatment gets added to your record so that further treatments don't accumulate too much
Which also takes into account how much time you spend outside during daylight hours, right?? That seems like such a large confounding variable that it renders the hospital-side measurement kind of pointless...
Digital x-ray sensors require a much smaller exposure than film, and I'd guess a lot smaller exposure than a shoe sizer machine, too.
For multiple exposures in motion, it will add up, but assuming there's a reasonable diagnostic benefit and the total exposure isn't too long, and the staff is well protected, it's a reasonable risk.
I don't know why I'm replying to this other than to add another anecdote about the fungibility of memory.
I first saw a Macintosh computer around 1984/85 when I was 7 or 8 years old, and I vividly remember the color screen. They were demoing MacPaint or possibly a SuperPaint beta and I recall the palettes being in color. Except Macs at that time were black and white!
Now I realize that it was probably synesthesia where some of the gray patterns looked blue, yellow, brown or even pink. So basically it was like dreaming and seeing colors which don't exist. Although nearly all of my dreams are in black and white, and I only remember a handful of dreams that had color, like a recent one that had a fruit bowl with all of the colors.
I'm especially curious about the last link, because there's a remote chance that someone had a Mac Plus with a color video card that I was lucky enough to witness in a rare demo. But the odds of that are pretty slim. Maybe some old graybeard knows of such a thing.
Ya I'm positive it was a Mac Plus form factor and not an Apple ][ (cool brackets btw, very nostalgic). And 90% sure that the drawing program was MacPaint, although I can't explain why I remember it being in color.
-
While I'm here, I want to link back to an earlier comment I made about synesthesia where patterns look like colors:
I think this mechanism was at play because I had never seen a dot matrix black and white display before, and thought that the Mac OS checkerboard gray pattern was especially cool. I distinctly remember one of the darker gray patterns appearing blue. So I wonder if my mind filled in the pink/red like in the Coke image. The brick wall and roof tile patterns also stirred my imagination, perhaps triggering a feeling of red.
I think most people with sight have rod cells which are sensitive to cyan, so I've always wondered if a negative afterimage in low light could simulate red for people with varying degrees of color blindness, technically color shiftedness, since they can see colors like gold/khaki that people with ordinary vision can't see but only see as a secondary mix of red and green light making yellow:
Unfortunately Google broke their search engine so we can't link directly to images anymore, a 1000th reason why it maybe shouldn't exist as a company anymore due to its recent behavior, but I digress:
I also had dozens of concussions growing up feral in the 80s, and I think that may have exacerbated my neurodivergency and ADHD symptoms, giving me endless curiosity. I stumbled onto an article the other day about shroom microdosing possibly regrowing connections between brain cells to treat traumatic brain injury, similar to this one:
So I wonder if psychedelics and exercises to train the visual cortex to discern colors better, combined with various medications that might slightly shift the opsin receptor frequencies in the eye, could improve color discernment for some people.
As I've gotten older, I've come to realize that our memories and perception of reality itself can change over time, because everything we perceive is actually in our minds. So for example, I had forgotten about the Mac Plus for 30-40 years, but now the memory is more vivid because it's connected to recent thoughts through time.
It's going to be weird in 10-20 years when something like Neuralink allows us to see without using our eyes. I suspect that we will discover new colors in the ultraviolet and infrared range that birds and insects see that we haven't seen before, as well as new impossible colors like green plus magenta/purple making octarine, the color of magic:
> Tartrazine is among six artificial colors for which the European Union requires products that contain them to be marked with the statement May have an adverse effect on activity and attention in children.
> The FDA requires that the Precautions section of prescription drug labels include the warning statement, "This product contains FD&C Yellow No. 5 (tartrazine) which may cause allergic-type reactions (including bronchial asthma) in certain susceptible persons.
Huh, I never expected to find out that the Ghouls from Leiber’s Fafhrd and the Grey Mouser books were actually plausible.
(They were perfectly normal medieval fantasy humans, except for their flesh and organs being mostly transparent, so you just saw a pinkish skeleton with a faint shimmer around it.)
173 comments
[ 4.2 ms ] story [ 250 ms ] thread[1] https://en.wikipedia.org/wiki/Lorentz_oscillator_model
Source: Doritos
Some tropical American frogs evolved to do it naturally (fam Centrolenidae). Some fishes also can do it also in a few different orders (Siluriformes and Perciformes at least), so in lower vertebrates it is possible and evolved several times.
But they have a different metabolism than ours and a mouse skin is much more thin than our own skin. I assume that this effect will work only on very small animals and the optical effect will hit some thickness limit somewhere. Could work on fingers but not in heart. At this moment my hype level is a 4 over 10.
But a few billion have ingested it in the past year, sometimes even in medical pill form to make yellow pills. Could be worse at higher doses but seems plausibly safe and worth further testing.
The more valuable contribution here is probably the idea IMHO.
To know that the optical effects of the light can be manipulated with the correct stuff and we could search for it. An ointment seems of to be useful to a restricted volume, to maybe the first millimeters of the skin.
We evolved totally transparent proteins that are hard, resilient and harmless. We have them in the eyes so we know how to do it. If we could only suggest the body to temporarily accumulate those proteins in the upper layers of the skin, or we could inject temporarily the proteins in local areas of interest that would be awesome (and maybe safe as long as is our own human protein)...
On the skin the continuous shedding of the upper layers would probably self-fix the stuff.
Common side effects include rash, constipation, nausea, diarrhea, dizziness, homicidal urges, drowsiness, insomnia, headache, and dry mouth.
(This might be the more desirable of the two outcomes. Otherwise you the man may be invisible, but everyone sees your intestinal contents floating in mid-air.)
But given that we already eat large amounts of it with no harmful side effects, the expectations are good.
[1] Note that they get skin that is transparent only to one shade of red, it's not transparent to all the visible spectrum.
The effect of a substance is usually three orders of magnitude lower when you rub it on your skin vs. when you swallow it.
Going out on a limb and guessing you're at an effective dose for something when it's making your skin transparent.
(2) assume it isn't absorbed into the larger body. Still the tissue absorbing it got a YUUUUGEEE dose. Then presumably most of it is washed out minutes later. So under that assumption we worry about localized tissue damage ---- --- which, if we're talking about things like cancer patients here who commonly get zapped with X-rays and gamma rays and antimatter and such, is perhaps not out of the ordinary. If there's no systematic damage the main concern would be cancer. If the skin dies, it can be fixed. And heck, a lot of cancer treatments also cause cancer i.e. many children with blood cancers go onto later get other cancers due to the medicinal cure of their blood cancer side effect.
Or is it really just a matter of serendipity waiting til now to lead anybody down the path of trying it this way?
tumeric / curcumin is often used a magic skin treatment type dealie. question is why are not all these wanting-to-have-youthful-skin type people discovering transparency! answer is below but TLDR human skin is thicker and doses are still low.
some main points from the paper( damned paywell, see supplement) > the dye only goes about 1mm deep, so maybe that works magic in a mice but not so good in humans nor noticable. > the dye comes it at arnd 0.5-1 molar solution. gmw is 500 g/mol ish. so 1M solution is 500g in 1L or 0.5g in 1 mL aka 500 mg in 1 mL. Okay, fine, you prepare this and rub 500 mg on your big toe from a little 1 mL aliquot. the daily limit or whatever for the food dye is around 4 mg! Soooo... >on the latter point, safety, the supplement had a bunch of stuff where they were like "we did all the normal blood tests on the mice, and looked at the tissue, and looked to see if they died later, and it all looks good"
I have a feeling that this will get tested by some intrepid YouTuber before the authors of the paper get approval from an ethics review board. I'll try to remember to Google this in a month or two.
Let's hope no-one gets it on their eyelids.
Since when do mice not have skulls?
For live skulls, it's considered white rude to check.
Reverse tattoos incoming.
t. chem student
see https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3460663/
https://www.science.org/doi/suppl/10.1126/science.adm6869/su...
Also the abstract of the article notes that strong UV absorption is likely a prerequisite for this effect:
> We hypothesized that strongly absorbing molecules can achieve optical transparency in live biological tissues. By applying the Lorentz oscillator model for the dielectric properties of tissue components and absorbing molecules, we predicted that dye molecules with sharp absorption resonances in the near-ultraviolet spectrum (300 to 400 nm) and blue region of the visible spectrum (400 to 500 nm) are effective in raising the real part of the refractive index of the aqueous medium at longer wavelengths when dissolved in water, which is in agreement with the Kramers-Kronig relations. As a result, water-soluble dyes can effectively reduce the RI contrast between water and lipids, leading to optical transparency of live biological tissues.
https://www.science.org/doi/10.1126/science.adm6869
However this kind of research into the effects of absorption bands on the transmission properties at interfaces might ultimately bring about more effective sunscreen formulations.
To expand: "the most hazardous UV radiation has wavelengths between 240 nm and 300 nm" [2]. While tartrazine has a lambda max at 425 nm in water [2], it has a second ridiculously-convenient peak around 260 nm [3].
TL; DR It should be mildly UV protective ceteris paribus.
[1] https://ehs.umass.edu/sites/default/files/UV%20Fact%20Sheet....
[2] https://pubchem.ncbi.nlm.nih.gov/compound/Tartrazine#section...
[3] https://www.aatbio.com/absorbance-uv-visible-spectrum-graph-...
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5326541/
like an x-ray, I'd risk that for a one-off doctors appointment, but I'd probably not risk it on my body at all times. maybe there are safer dyes that have the same effect
Given the effect is optical, perhaps encapsulation in benign, transparent beads? (Could be particularly effective is the goal is a tattoo.)
Fortunately the nail totally missed anything important, so they just pulled it out and bandaged him up- no worse for the wear. He went on to be an honest-to-God track star so it obviously didn't have any lasting effect.
Decades later we were talking about something and he said to me, "Why don't they use that x-ray water anymore?". I had no idea what he was talking about so I asked him to elaborate.
The way he remembers the incident is that they put his foot into a bucket of amber liquid and, once submerged, his skin became transparent. He looked in and saw his own bones, blood vessels, and- in the middle of it all- the nail that was causing such a fuss. He described wiggling his toes, flexing his ankle, and seeing the bones and tendons move, directly, with his own eyes.
His toddler brain, probably in shock, had combined the x-ray film and iodine bath. Over the years it had grown more detailed and reinforced. He described it with such clarity that I almost wondered if I hadn't been mistaken. He didn't believe me when I told him how I remember it. We called our mom who confirmed my version of events, plus did some googling, which finally convinced him.
Anyway I just sent him this article. It's interesting that not only is the x-ray water he remembers theoretically possible, it would actually be amber.
(if you don't accept that second fact, that's fine, I'm not here to convince anyone or debate)
Historically there were actually "live" x-ray machines, where you could have seen yourself wiggling your toes. They aren't used now due to the horrific exposure to x-rays, but before that was understood to be bad they were used in shoe shops (!). I don't know that they were ever used in hospitals though
https://en.m.wikipedia.org/wiki/Shoe-fitting_fluoroscope
Checking your Wikipedia link: Yikes! These were used into the 1970s.
And of course industry denialism of any possible harm the devices might cause....
SMFH
https://www.museumofquackery.com/devices/shoexray.htm
At least they had the good sense to give it up when notified.
Edit: This is the type of machine it was: https://www.dmxworks.com/
Which also takes into account how much time you spend outside during daylight hours, right?? That seems like such a large confounding variable that it renders the hospital-side measurement kind of pointless...
For multiple exposures in motion, it will add up, but assuming there's a reasonable diagnostic benefit and the total exposure isn't too long, and the staff is well protected, it's a reasonable risk.
I first saw a Macintosh computer around 1984/85 when I was 7 or 8 years old, and I vividly remember the color screen. They were demoing MacPaint or possibly a SuperPaint beta and I recall the palettes being in color. Except Macs at that time were black and white!
Now I realize that it was probably synesthesia where some of the gray patterns looked blue, yellow, brown or even pink. So basically it was like dreaming and seeing colors which don't exist. Although nearly all of my dreams are in black and white, and I only remember a handful of dreams that had color, like a recent one that had a fruit bowl with all of the colors.
https://en.wikipedia.org/wiki/SuperPaint_(Macintosh)
https://en.wikipedia.org/wiki/Macintosh_Color_Classic (hadn't been created yet)
https://www.youtube.com/watch?v=UVcv8ORSZEQ Color Macintosh Plus (mod)
https://www.youtube.com/watch?v=slY_F1MxGlk The Mac Plus had modern multi monitor support in 1986 and I got it working! (not me!)
I'm especially curious about the last link, because there's a remote chance that someone had a Mac Plus with a color video card that I was lucky enough to witness in a rare demo. But the odds of that are pretty slim. Maybe some old graybeard knows of such a thing.
-
While I'm here, I want to link back to an earlier comment I made about synesthesia where patterns look like colors:
https://news.ycombinator.com/item?id=40602237
https://gagadget.com/en/446542-a-photo-of-a-coca-cola-can-th...
I think this mechanism was at play because I had never seen a dot matrix black and white display before, and thought that the Mac OS checkerboard gray pattern was especially cool. I distinctly remember one of the darker gray patterns appearing blue. So I wonder if my mind filled in the pink/red like in the Coke image. The brick wall and roof tile patterns also stirred my imagination, perhaps triggering a feeling of red.
I think most people with sight have rod cells which are sensitive to cyan, so I've always wondered if a negative afterimage in low light could simulate red for people with varying degrees of color blindness, technically color shiftedness, since they can see colors like gold/khaki that people with ordinary vision can't see but only see as a secondary mix of red and green light making yellow:
https://www.google.com/search?q=negative+afterimage (click Images for examples)
Unfortunately Google broke their search engine so we can't link directly to images anymore, a 1000th reason why it maybe shouldn't exist as a company anymore due to its recent behavior, but I digress:
https://stackoverflow.com/questions/21530274/format-for-a-ur...
I also had dozens of concussions growing up feral in the 80s, and I think that may have exacerbated my neurodivergency and ADHD symptoms, giving me endless curiosity. I stumbled onto an article the other day about shroom microdosing possibly regrowing connections between brain cells to treat traumatic brain injury, similar to this one:
https://jmvfh.utpjournals.press/doi/full/10.3138/jmvfh-2022-...
So I wonder if psychedelics and exercises to train the visual cortex to discern colors better, combined with various medications that might slightly shift the opsin receptor frequencies in the eye, could improve color discernment for some people.
As I've gotten older, I've come to realize that our memories and perception of reality itself can change over time, because everything we perceive is actually in our minds. So for example, I had forgotten about the Mac Plus for 30-40 years, but now the memory is more vivid because it's connected to recent thoughts through time.
It's going to be weird in 10-20 years when something like Neuralink allows us to see without using our eyes. I suspect that we will discover new colors in the ultraviolet and infrared range that birds and insects see that we haven't seen before, as well as new impossible colors like green plus magenta/purple making octarine, the color of magic:
https://www.colourlovers.com/blog/2008/04/19/octarine-the-im...
I guess t...
Also related: https://www.ycombinator.com/companies/eden-2
> Tartrazine is among six artificial colors for which the European Union requires products that contain them to be marked with the statement May have an adverse effect on activity and attention in children.
> The FDA requires that the Precautions section of prescription drug labels include the warning statement, "This product contains FD&C Yellow No. 5 (tartrazine) which may cause allergic-type reactions (including bronchial asthma) in certain susceptible persons.
(They were perfectly normal medieval fantasy humans, except for their flesh and organs being mostly transparent, so you just saw a pinkish skeleton with a faint shimmer around it.)
Scientists use food dye found in Doritos to make see-through mice
My first reaction was, what the heck have I been smoking?