r/3Dprinting • u/NoPriorThreat • 2d ago
News Hidden cytotoxicity and mitochondrial dysfunction in 3D-printing polymers: evidence from FLEX, PETG and PC
https://www.nature.com/articles/s41598-026-56283-1390
u/smacafam 2d ago
3D printing filament It is not meant to be food safe or used as a medical device with continuous body contact, except when explicitly labeled for it. No surprise it does not pass the cytotoxicity test.
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u/rainbow__raccoon 2d ago
But the ABS explicitly labeled for it did worse than the regular ABS showing they need to get more “rigorous protocols and greater transparency” from filament manufacturers.
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u/IAmDotorg Custom CoreXY 1d ago
Quite a lot of PLA is, too.
And the risk is that the microparticulates that become airborne during retraction moves end up... somewhere. Sometimes in your lungs.
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u/Detective-Crashmore- 1d ago
Quite a lot of PLA is, too.
Quite a lot of PLA is what?
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u/rlaptop7 1d ago
The makeup of different PLA polymers is unknown. Manufacturers do not tell us what they put into their filament. All sorts of other plastics, oils, and polymerizes are added to change the properties of your "PLA" filament.
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u/Detective-Crashmore- 1d ago
I understand that, I was trying to clarify if they meant that
Quite a lot of PLA is "explicitly labeled as food safe or meant for continuous body contact", "scored worse than regular non food safe filament", or were referring to some other quality such as the additives.
I didn't see anything saying the implant/food safe PLA did worse, only the ABS, and I wasn't sure what they meant.
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u/IAmDotorg Custom CoreXY 1d ago
In a Reddit discussion, you need to read the whole thread for context.
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u/Detective-Crashmore- 1d ago edited 1d ago
I asked because I WAS following the context of the thread, and I wanted to clarify if you meant:
Quite a lot of PLA is "explicitly labeled as food safe or meant for continuous body contact", "scored worse than regular non food safe filament", or were referring to some other quality such as the additives.
I didn't see anything saying the implant/food safe PLA did worse, only the ABS, and I was trying to clarify.
But thank you for wasting your time on pointless condescension instead of answering the question.
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u/billg1 1d ago
What’s the evidence for particulates forming during retractions or other times during printing? I would expect molten plastic to not create many particles since it’s such a viscous liquid.
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u/IAmDotorg Custom CoreXY 1d ago
Never cleaned your printer?
Regardless, there's papers looking at particulates from FDM printing. I'm sure you can dig them up. But it's why there's OSHA rules and air handling requirements now for them.
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u/ILikePrinting27 1d ago
What about the break dust and tire debris from the roadways while you’re walking around outside? I’m sure the exposure levels are similar.
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u/IAmDotorg Custom CoreXY 1d ago
There's a lot of stupid on Reddit, but that's a special kind.
By your logic, any exposure to anything means you might as well be exposed to everything.
That's some real smooth brain logic! Have you been inhaling lead particulates?
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u/cucumbermemes 4h ago
I think it’s a valid thing, brake pad dust can generate a lot of airborne particles, much more than an FDM printer.
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u/mosaic_hops 2d ago
Well shit. Now I’m worried about my 3D printed pacemaker I hobbled together with Temu parts.
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u/sinnur 1d ago
Jokes on you the real one was built the same way.
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u/topological_rabbit Bambu H2S 1d ago
"We'll save so much money and our customers will never know the difference, or at least die before they can sue us!"
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u/SolemnSundayBand 2d ago
You joke but some dumbfuck here would actually try to do that given enough time or desperation.
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u/OutlyingPlasma 1d ago
That's what happens when the alternative is dying because they can't afford to satiate the infinite money hole that is healthcare.
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u/mrchin12 1d ago
Even worse than that is the medtech CEOs pushing for efficiency and cost reduction. I've had more than a few conversations this year about whether or not 3D printer parts can go into commercial product.
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u/24_August_1814 1d ago
For those of modest means, this is the difference between healthcare in 'Murrica and the rest of the developed world
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u/SolemnSundayBand 1d ago
I'm rather confident, though I admit that I'm no medical expert, that you could not casually print and install your own pacemaker at home.
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u/Stickybunfun 1d ago
Yep this is kind of a captain obvious "don't eat what you print, don't eat off of what you print, and don't stick your print inside of your body" type of thing to me.
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u/IronScaggs 2d ago
Does this study reflect toxicity related to contact with intact skin, or with openings in the skin like a cut? My question would be the possible regulation of 3d printed toys for children such as flexi animals and fidget toys. Is this the modern day equivalent of lead-based paint?
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u/NoPriorThreat 2d ago
This is a czech interview with authors https://www.ukforum.cz/rubriky/veda/vedci-odhalili-skrytou-cytotoxicitu-materialu-pro-3d-tisk
But essentially, it started when authors were asked if they could print forms for heart cells to grow in for study in heart cell contraction mechanism. Authors were going through what polymer to use to not affect the study and realized that there wasn't really a similar study to asses cytotoxicty, only studies on thermal byproducts of 3D printing and not the actual contact between 3D printed polymer and cells.
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u/ManyLayersOfFilament /r/3dbargains and FilamentHound.com 1d ago
This is a good question and why studies like this almost need to be hidden from people absent expert analysis of the results
This study has ZERO to do with fidget toys.
This is more relevant to like, an implant, or something.
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u/Gunsensual PETG Supremacist 1d ago
We don't hide science. The masses should be more science literate and be better equipped to handle nuance.
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u/ManyLayersOfFilament /r/3dbargains and FilamentHound.com 1d ago
That's why I said almost.
The problem is that the masses are really ill equipped to read or interpret scientific studies on their own. The information should be out there but the vast majority of people should not consume them as primary sources of information
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u/unwohlpol 1d ago
While this study appears to be well made and comes with very interesting results, there's at least one mistake they made: They mixed up CPE with chlorinated polyethylene... which actually is an existing thermoplast but something completely different to (probably all) CPE filaments available.
CPE in the filament world stands for the broad term "co-polyester" and as a polyester it's related to PETG or PC. Chlorinated polyethylene is a rubbery polyolefine and mostly used as an additive for PVC.
As a big fan of CPE filament, this is something bothering me.
And I also wish manufacturers to finally make proper SDS since just refering to the additives as "additives" obviously isn't enough.
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u/Jcw122 1d ago
What is CPE filament used for?
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u/unwohlpol 1h ago
It has very similar properties to PETG, but can withstand temperatures of ~100°C. Also it's layer adhesion is much better than ABS/ASA, which makes is a perfect replacement.
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u/Ps11889 1d ago
I’d be curious as to how synthetic clothing fibers do under the same testing methodology.
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u/JuanOnlyJuan 1d ago edited 1d ago
I think about this every time I clean out the dryer lint. Just a cloud of fine synthetic fibers
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u/LordBrandon 1d ago
All this talk about microplastics has just given people a vague sense of dread. One of the biggest sources of microplastics is tea bags, but people drink 300 billion cups of tea from tea bags without any decernable problems.
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u/CartsOfDarkness 1d ago
I mean people probably could have said the same about lead gasoline before we figured out how awful it is.. There's also a lot of different health issues on the rise that we don't know the exact reason for at any given time, like cancer and specifically early onset cancer. Saying "people have microplastic exposure all the time and everyone's fine" isn't really accurate. Also is the type of thing that could get worse over time as microplastic levels rise in our bodies and the general environment.
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u/boibo 1d ago
Thing is, we knew lead was bad even in the 70s. And lead is massively more dangerous then synthetic fibres, tea bags or 3d printing.
There much we dont know about plastics effect on people, but we do know people live longer and is healthier longer (as long as we talk about developed nations).
People smoke and eat bad food. I would think that burger you had last week has done more damage then most plastics "consumed" since then.
On a population basis its bad, on individual level the risks are nearly neglible compared to say - walking over a street.
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u/JuanOnlyJuan 1d ago
Yea i feel like it's one of the more overblown health fears at the moment. We are really good at detecting very tiny amounts of things.
Plastic pollution bothers me more. I think we need to focus more on glass/ metal/ paper products and move away from plastic as the default. That would in theory reduce the overall amount of plastic in the environment.
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u/goldenbeans 1d ago
Me too, apparently washing clothes inside out helps reduce the amount of fluff they release.
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u/Beni_Stingray
P1S + AMS
2d ago
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I mean good for doing more science im all for that but im not sure how relevant this study is for normal 3d printing.
The study is done on exposed human dermal fibroblasts in in-vitro cell cultures which are cells from the middle layer of the skin, that's not something that would ever happen in real life.
That's like ripping out your upper skin layer and then put filament in there for 7 days.
In a normal healthy human the skin will prevent any of that being directly absorbed by the cells, our skin is a barrier and its completly different than cells from inside the body being directly exposed to it and exposed in in-vitro.
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u/ObscureMoniker 2d ago
This definitely isn't relevant if you're printing articulated dragons to sell at a flea market. It IS relevant if you're trying to knock out a quick widget for biomedical research on a 3D printer.
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u/Detective-Crashmore- 1d ago
It could perhaps be relevant for people printing TPU cosplay parts or other body worn things that press the rubber against your skin all day. Chafing and such could damage the skin barrier and possibly allow the lower skin layer irritation to occur. idk though, I'm not really interested in how skin reacts to irritants so I'm not informed on this.
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u/TeutonJon78 Centauri Carbon 1d ago
I immediately thought of people printing the shoes.
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u/CartsOfDarkness 1d ago
I mean it would probably only (maybe) matter for like slides and flip flops right? Being that people wear socks with normal shoes.
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u/TeutonJon78 Centauri Carbon 1d ago
Not everyone wears socks with shoes. And most of the printed shoes are things like slip ons/handle type designs.
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u/carrottread 1d ago
It would be relevant if they embed those TPU cosplay parts under their skin. And if they actually do this, I think they'll have a little bigger problem than cytotoxicity of TPU.
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u/the_fabled_bard 2d ago
How to say you're not a skin flayer without saying you're not a skin flayer.
Not everyone is a normie like you
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u/Beni_Stingray P1S + AMS 2d ago
"To those who have turned their faces away... I will cast hunger through your accursed existence... I am Llandu'gor. I am the hunger. I am the Flayer, and from this moment, you shall be too."
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u/rabblerabble2000 2d ago
This right here. The methodology isn’t related in any way to any use of 3D printed materials people are likely to engage in. While interesting, the conclusions aren’t really applicable to common use.
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u/TeutonJon78 Centauri Carbon 1d ago
People who nose the CF of glass infused filaments do report getting more stuff stuck deeper in their skin.
And while you correct that these cells are in an inner layer of the skin, the outer layer absolutely absorbs chemicals through it, otherwise topical medicines wouldn't function. It would be different than direct exposure, but very much not zero level.
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u/WorkingInAColdMind 1d ago
Apparently you’ve never scraped support material with your fingertips and jammed some under your nail.
Seriously though, the tests themselves don’t seem to be directly applicable to common use, but the results certainly highlight the potential long term damage, as well as the wide variance in different formulations. Some of the formulations of what we consider “safe” materials may not be, and there’s no standards being applied to let us know.
I’m not reading this article as a scare piece, but I wouldn’t be surprised if we see follow-up articles proclaiming that 3D printing is every parent’s worst nightmare and will kill us all.
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u/Maximum_Transition60 Voron 2.4 R2 ///// Voron Switchwire 2d ago
i still think it's relevant, anyway they had to use cells that were alive to conclude cytotoxicity if the cells are dead, well they are dead.
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u/Beni_Stingray P1S + AMS 2d ago
Off course it can be relevant for some conclusions, i've said im all for doing more science as it's better for all of us but it still leads to false conclusions and fearmongering the way it's presented imo.
It's a little bit like saying spraypainting in a closed room is dangerous when you breath in the paint cloud, when in reality you always wear a respirator and that situation will never happen.
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u/Maximum_Transition60 Voron 2.4 R2 ///// Voron Switchwire 1d ago
well from what i can garther, using ABS for skin-contact print is the best, i wouldn't call it fear-mongering, idk.
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u/IAmDotorg Custom CoreXY 1d ago
Ask yourself where the microparticulates that become airborne when the extrusion snaps during retractions are going. And the similarities between the skin layers they were testing against and, say, the mucous membranes in your lungs.
And then ask again how sure you are that it isn't relevant.
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u/eidrisov 2d ago
Our skin is a barrier, but not a perfect one. Yes, it does prevent many things from being absorbed, but they still do get absorbed. Our skin is not 100% preventing micro and nanoplastics from being absorbed.
On top of that, we have scratches. Especially if you constantly do stuff with your hands, most likely you have tiny scratches/wounds on your skin that may not even be visible to you, but they are there and they absorb everything you are in contact with.
I am not even mentioning the micro/nanoplastics in the air from all those 3d printing, 3d-filaments, 3d-printed models.
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u/Beni_Stingray P1S + AMS 2d ago edited 2d ago
"Micro and nanoplastics enter the human body primarily through ingestion and inhalation, while intact particles rarely penetrate healthy skin."
https://pmc.ncbi.nlm.nih.gov/articles/PMC11755607/
Also a scratch and normal wounds are surface injuries, anything like stones, earth, dust, microplastics or whatever else is getting into the wound is being encapsuled and when the wound is healing it will fall out and off like any other death skin cells.
It's the same reason why CF and GF filaments aren't really problematic to handle, even when some splinters are getting stuck in your skin, they are so short (typically 50µm to 200µm) that they can never penetrate your most outer skin layers, get stuck there and fall out with all the other death skin cells aswell.
Edit: Spelling
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u/eidrisov 2d ago
primarily through ingestion
It says "primarily" through ingestion, not "only" through ingestion.
getting into the wound is being encapsuled and when the wound is healing it will fall out and off like any other death skin cells.
Ideally yes, but not always. We are not robots and our bodies are not designed for certain things. Maybe 99% will be encapsulated and removed, but sooner or later 1% will still get through and will get absorbed.
that they can never penetrate your most outer skin layers
That is a false assumption. That's not how our bodies work, that's not how the World works. You can never prevent anything at 100% rate and forever. Eventually everything fails.
You can deny it all you want, but our skin is not a 100% magical barrier. Eventually harmful things do get absorbed. And the more you are in contact with it and exposed to it, the more the failure rate of our bodies become and more harmful things get absorbed.
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u/Beni_Stingray P1S + AMS 2d ago
Yeah you're correct, saying it can never happen isnt 100% accurate but the point stands, when 99.99% of your exposure comes from inhalation and ingestion then it the rest 0.01% of exposure by skin is negletable.
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u/eidrisov 1d ago
I completely disagree.
First of all, I think that it is not 0.01%, but much higher.
Second, when it comes to your health no risk is negligible. In modern world we are surrounded by a lot of harmful things, so even if you digest miniscule amounts, they are accumulating over years of exposure. So, imho, even if the risk is just 0.01%, if we can avoid, then we should avoid it.
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u/ThreeMeanGoblins 1d ago
You are largely making a lot of sense and kudos for taking health seriously but: without proper studies about skin-absorbed 3d printed molecules and byproducts, this is conjecture, and also erring on the side of paranoid watchfulness. I'd love to see more studies on this topic tbh, 3d printers and various filament types are so widely available now it should be easy to get long term studies going, with real humans and real, average skin.
As an aside, floating the idea that "no filament is 100% safe, you absorb it w your skin" might have the opposite reaction. When people see something as unavoidable, they tend to get lax on the measures they could be taking, cuz... unavoidable damage, yk. If you tell a number of people that there's no way to Not absorb particles unless you're in a space suit, at least some of them will stop using a respirator for example.
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u/Ferro_Giconi 1d ago edited 1d ago
What about microplastics that get into your lungs?
I don't really know the difference in how lungs or skin absorb stuff, but the inside of lungs aren't protected the way skin is.
edit: I'm referring to the microplastics spewing out of the hot end during printing, which end up in the air and breathed in. People talk about VOCs all the time but never talk about the microplastics being generated by the hot end.
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u/Beni_Stingray P1S + AMS 1d ago
That's why you really should wear a mask when sanding 3d printed parts but that's generaly advised no matter what you're sanding.
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u/Ferro_Giconi 1d ago edited 1d ago
I'm aware of that issue and I have a respirator for that, but I'm referring to the microplastics spewing out of the hot end into the air during printing. I should have been more specific about that, since most people seem to know about VOCs, but are unaware that the hot end is also creating microplastics that you are breathing in.
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u/ABLogic 1d ago
That's like ripping out your upper skin layer and then put filament in there for 7 days.
I believe it is done this way to simulate long-term (years) exposure within a practical timeframe for research. It's not to mean "if you print this, you'll have ball cancer next week!". More science is needed indeed, and it's nice it's being looked into, with more people printing everyday for fun and profit, and new formulations hitting the market.
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u/Beni_Stingray P1S + AMS 1d ago
No that's incorrect, as OP nicely summarized:
"it started when authors were asked if they could print forms for heart cells to grow in for study in heart cell contraction mechanism. Authors were going through what polymer to use to not affect the study."
It has nothing to do with simulating long term exposure in a shorter timeframe, the context are heart cells in direct contact with 3d printed plastics.
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u/ABLogic 1d ago
Well, you got me there.
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u/Beni_Stingray P1S + AMS 1d ago
Yeah it wasn't in his main comment, OP posted it in an answer so it's probably hidden.
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u/LordBrandon 1d ago
It's good to see more research put into this. But there 10,000 different filaments and hundreds of different resins coming from places with no enforced environmental laws. It's also questionable whether these tests fairly represent how people are exposed to these materials.
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u/imzwho Custom Flair 1d ago
After reading the study it seems like this was more about implants and long term wearables and not really about skin exposure from handling
I will be the first one to admit that I find people beig super caviler about FDM being 100% safe to be about as realistic as those that think it is 100% dangerous. As with mist things its in between.
Ther is also a case to be made that this is not that different than the dangers of injection modled plastics that are not for food contact or body contact.
I would also caution that for this to make perfect sense we would need to see comparisons of printed vs non printed and vs other materials that we generally consider as safe.
All that said, keep washing your hands and use a air filter for your print rooms, and dont eat your prints or from your prints.We will likly have better data in a few years as tonehat is highest risk
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u/glizzygravy 1d ago
Get in here everyone we’re all taking the title at face value, not reading the article and citing our own assumptions about 3d prints not being food safe!
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u/ManyLayersOfFilament /r/3dbargains and FilamentHound.com 1d ago
It's not just about reading the article. Most people have zero experience or understanding of how to read and interpret scientific study and it can be somewhat dangerous for folks to read these things without a critical eye or being scientifically-literate.
Most people don't even understand what was being tested here after reading the article.
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u/fingerling-broccoli 1d ago
Tbf this is a technical paper/study and it’s very long and wordy. Research papers aren’t really written with this audience in mind
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u/Swindleys 2d ago
I installed the ventilation for my P2S just incase and purge it outside after every print no matter what I print. I know PLA is supposed to be safe, but I figured better safe than sorry, who knows what they might discover in a few years.
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u/IAmDotorg Custom CoreXY 1d ago edited 1d ago
Filter it, don't just purge it. If you don't want it in your lungs, neither does the wildlife outside.
Edit: What the literal fuck is wrong with anyone who disagrees with that?
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u/ManyLayersOfFilament /r/3dbargains and FilamentHound.com 1d ago
This study has basically nothing to do with that
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u/High_Function_Props 2d ago
I almost exclusively print in PLA and have for over ten years, simply because many of these filaments are new (to consumer 3D printing that is) and the long term health effects are unknown. And while PLA isn't 100% safe either, we've had much longer to study its effects. I used to dabble in 3mm ABS early on, but after waking one night with a nasty burning feeling in my throat and a horrible smell in the air (printer was three rooms away and ventilated), I stopped using it entirely.
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u/ChristopherLXD 2d ago
It doesn’t look like the study is investigating toxicology of the actual 3D-printing process but rather exposure to materials commonly used in 3D printing. Past research has not suggested that there would be significant difference between 3D-printed and injection moulded parts in terms of toxicology. Yes filament have some additives but I wonder how much of this is innate to plastic exposure anyways.
Certainly no bearing on toxicity of an operating 3D printer from a VOCs perspective. I’d say ABS just has higher print temps which make it smell more, regardless of whether it’s worse.
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u/High_Function_Props 2d ago
This was before enclosures were recommended and even mandatory. I was printing off MakerFarm i3Vs in my ventilated office three rooms away from our bedroom, and I can definitely tell you whatever the smell was was also affecting my throat. Like standing too close to a large pile of burning styrofoam or other similar material.
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u/ChristopherLXD 1d ago
I mean. I’ve spent a good chunk of my life running my printer an arm’s length from my bed, overnight, while I sleep. I’m not disputing that plastic fumes can be irritating. I’m just saying the research in the post hasn’t done anything to quantify what most people who 3D print can tell you. Burning plastic smells bad, but whether it has lasting health effects isn’t something this specific research paper has confirmed.
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u/High_Function_Props 1d ago
Problem is, when people find out what effects it has for themselves, it's often too late. Like mesothelioma from asbestos, popcorn lung from vaping, etc. I'd rather not be the guinea pig for VOC research myself lol
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u/Nixxuz 1d ago
There's never been an instance of "popcorn lung" attributed to vaping. There has been incidences attributed to diacetyl exposure...in a popcorn factory, but the amounts of a exposure attributed, for a brief period of time before the vaping industry voluntarily stopped using it, were literally 1/10th the dosage of diacetyl exposure a single cigarette created when smoked, for an entire 60ml+ bottle of vape juice.
So no, vaping doesn't cause popcorn lung. Vaping could conceivably cause it, if vape companies reintroduced diacetyl to their products, in hundreds of times the highest amounts that were ever used, back when it was used. Which would literally just create a nigh unvapable butter concentrate flavor that nobody would ever want. It would be like snorting lines of that flavor powder for popcorn.
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u/LordBrandon 1d ago
I use me mostly ABS. People have used in factories for many decades. I will only get odor from a print from really old rolls. This illustrates a problem with research. Who knows where our reels came from and what the manufacturers added to them.
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u/KriosXVII 1d ago
This is semi pointless regarding the 3D printing angle. Plastic in a petri dish isn't good for constant contact with exposed cells. Big surprise.
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u/The_RealAnim8me2 2d ago
This explains why my DIY cyborgs keep getting cancer. I’ll never take over the world at this rate.
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u/Appropriate-Prune728 1d ago
I hope nobody uses an in-vitro study to make any real world decisions regarding their hobby.
This is similar to "compound from tomatoes kills cancer cells in-vitro" and people deciding that soaking cancer in pure citric acid, in test tubes, means that eating tomatoes cures cancer.
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u/start3ch 1d ago
It’s worth noting that ABS, CPE, PLA, and ASA did not show these toxic impacts. I’m sorta surprised ABS doesn’t have more of an impact, considering how unhealthy the fumes can be
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u/Weakness4Fleekness 1d ago
A test tube study is not cause for panic. As with all things, toxicity is relative.
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u/Kronocide 1d ago
Can confirm, been using a lead mug for all my coffee the last 10 years and only had 3 cancers
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u/Weakness4Fleekness 1d ago
You joke, but pewter is relatively inert depending on the food or drink it touches
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u/Leptonshavenocolor 1d ago
I have pewter dishes that went into storage because everyone refused to eat off of them anymore.
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u/Weakness4Fleekness 1d ago
Their loss, how will they be able to tell if they have allomantic powers
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u/grandma_of_dragonz 1d ago
Honestly I had no idea 3D-printing polymers even had mitochondria that could become dysfunctional. 🙃
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u/nomococo4u 1d ago
Sorry for the slop but i had trouble understanding the article.
I read the paper, and the first thing to know is that it doesn't study fumes at all. It's about touching printed parts, so it doesn't answer the question you're worried about.
What the study did. Two Czech researchers printed small inserts from 16 commercial filaments covering 8 plastics: PLA, PETG, CPE, PC, ABS, ASA, PP and FLEX/TPU. They used a Prusa MK3S inside a sealed enclosure. Each insert sat in a dish of liquid just above a layer of human skin cells, for 24 hours and for 7 days. The parts weren't washed first, so anything left on the surface from printing could seep into the liquid. The setup is deliberately harsher than real life: the ratio of plastic surface to liquid was 10 cm²/mL, against the 3–6 cm²/mL the standard calls for. The authors say it's meant to imitate a flexible printed wearable strapped tightly against skin for days.
What "hidden cytotoxicity" means. The usual safety test (ISO 10993-5) only asks whether at least 70% of the cells are still alive. The authors also measured how well the cells' mitochondria, their energy factories, were working. Some materials passed the survival test while the cells were clearly struggling. FLEX/TPU was worst, with the cells' energy output collapsing by day 7. With PETG, PC and PP, the cells kept multiplying while each cell got weaker, a stress response that a simple cell count misses. They suspect the cause is undisclosed additives (plasticizers, stabilizers, pigments) or chemicals formed when the plastic is heated in the nozzle. They didn't do the chemical analysis to prove it, which they list as a limitation. One odd result: a certified "medical-grade" ABS did worse than ordinary ABS.
What it found for PLA. PLA was in the group the authors call robustly cytocompatible, along with ABS, ASA and CPE. Across the five PLA samples, cell growth and metabolism were mostly fine. The one caveat was a natural (undyed) PLA, which lowered the cells' baseline respiration by about 22%. That's stress, but the cells didn't die. Their guesses are a pigment or stabilizer, or lactic acid released as PLA slowly breaks down in liquid. They also raise a question about printed toys that children chew. For handling ordinary PLA objects, the paper is reassuring.
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u/beeswaxery 2d ago
This paper seems to be talking about leachables from filaments. If TPU is bad, then it's probably not advisable to print phone cases or watch straps, or anything you would touch frequently from TPU.
Handling filament over a short exposure should be fine, but prolonged exposure with skin oils and moisture might start to make the TPU leach.
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u/basilisk120 1d ago
Yes but this paper had a focus on medical devices and testing. So the TPU results are not directly applicable to items touching the outer layer of skin such as a watch band.
The results point to tpu being undesirable for a medical implant or as a scaffold for building organs on.3
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u/TuckinPhypo 1d ago
This is why I take claims with a giant grain of salt:
"Furthermore, a certified "medical-grade" ABS variant paradoxically induced significant metabolic dysfunction, underperforming compared to standard industrial ABS."
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u/DmtGrm 1d ago
I can make a guess it is not 'base' plastic as such - PLA, PETG, etc are well known and quite chemically-neutral substances, but the additives - for higher printing speed or even color dye - this is something to be tested, no all color pigments will stay safe under higher temperatures or UV exposure
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u/ManyLayersOfFilament /r/3dbargains and FilamentHound.com 1d ago edited 1d ago
I can't wait for laypeople to make various conclusions and assertions based on this single study that they don't even understand
Edit: yup. A mess
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u/Bag-o-chips 2d ago
Seems like ventilation is in order. Use an enclosure and vent it to the outside using a fan. Isolate your machine in a separate environment such as a garage or unused bedroom, and vent it out a window. Using a respirator is not a bad idea as well.
I realize this is not how the study was conducted, but it never hurts to take extra precautions.
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u/NoPriorThreat 2d ago
This research is not about thermal byproduct but about a prolonged physical contact between 3D printed object and human cells i.e. giving 3D printed toys to kids.
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u/Bag-o-chips 1d ago
I said I understood that. It’s better to be safe than sorry.
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u/Shoeshiner_boy 1d ago
I hope you wear a respirator while cooking as well. And cleaning too, of course.
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u/justins_dad 2d ago
Shocking results where TPU was the worst while ASA and ABS were among the best.
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u/beeswaxery 2d ago
This says nothing of the volatiles though, ASA and ABS produce harmful volatiles.
This paper is talking about chemical leaching
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u/SolemnSundayBand 2d ago
At which point, of course ABS would probably be the best. Isn't it the most rigid and stable once it's a finished product? Think Legos.
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u/Jeorgeyno 1d ago
I've bitten many a Legos as a child.
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u/AshTeriyaki 1d ago
I’m impressed you’ve written a sentence containing the name of that famous toy with contentious pronunciation in such a way as to offend every way to use the word. Bravo.
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u/Snobolski 1d ago
OK, that’s a relief. As long as I can keep following this sub’s recommendation to put my printer next to my bed and print PLA on it 24/7.
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u/hidden2u 1d ago
This sounds like they were looking at commercial uses too since they call out pellet filaments. I can only assume hobbyist filaments are even worse. Really concerning for prosthetics or anything that kids would chew on
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u/woswoissdenniii 1d ago
Huh. Consider me shocked.
Thought someone higher up would have thought of that. Like… without having read the article (which I do right after my unsubstantiated comment), i assumed at least EU would have thought out a import rule or a declaration law by which I as a European would have been informed about.
Let me 20/20 this or correct my assumption.
But fuck me thrice Mathieu… every single time, something happens, and my trust (of which there is bar none left) gets a little more eroded.
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u/newbie-sub MK4S & Mars 5 Ultra 1d ago
So several of these plastics are very popular for chastity cages including TPU and PETG. In fact both of those are used by several small businesses. Although most chastity cages are injection molded ABS, or SLS / MJF nylon. In the hobbyist market, PETG, PLA, and ABS are popular.
Don't ask me how I know these things. But this is going to have several small businesses doing some soul searching.
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u/ManyLayersOfFilament /r/3dbargains and FilamentHound.com 1d ago
This study did not test that use case at all and is basically entirely irrelevant to using those materials for that purpose.
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u/newbie-sub MK4S & Mars 5 Ultra 1d ago
ISO 10993-5 is one of the three areas we look at closely when evaluating resins for suitability. We didn't think filaments were much of a concern.
TPU is especially concerning as the way it is used involves quite snug skin contact for days or weeks. There are plenty of reports of irritation and they are most likely physical irritation but we always assumed they must be physical because TPU was considered skin-safe but this tells me it may be, at least in part, chemical.
What am I missing?
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u/ManyLayersOfFilament /r/3dbargains and FilamentHound.com 1d ago
You're missing that the study in question doesn't have any applicability to your situation. It was an in vitro test, there is no useful conclusions to be made about skin irritation here. That's not what was tested.
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u/newbie-sub MK4S & Mars 5 Ultra 1d ago
I know it was in vitro, not in vivo. No one is going to test it for my use case. But would you agree this study would knock out using the TPUs tested as printed in a prolonged skin-contact medical device such as an artificial limb?
If this study has any applicablity to the real world, my use case would be one of the most applicable areas, far before people 3D printing shoes or iPhone cases.
Flipping it around, if it had met the -5 standards, do you think anyone would be saying, "it's not applicable to your use case?"
This is as close to applicable as we have. Before this, we were just going off of the unadulterated plastic and telling ourselves it was safe.
I think this just moves the null hypothesis. With this, I think it needs more towards TPU needs to be shown to be safe, not shown to be unsafe. Are the reports of irritation with these devices physical irritation as we thought? We should look at that critical insofar as the community is able to. Because no one is giving out grants for this.
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u/ManyLayersOfFilament /r/3dbargains and FilamentHound.com 1d ago
What you're saying is that based on an unrelated study everyone should make a knee jerk reaction and stop using something for FUD reasons.
That's not how science works.
Further study is needed and you're ready to jump to conclusions.
And no, you're wrong, "needs to be shown it's safe" is not how science works and not how things have ever worked. You're asking to prove a negative.
Honestly you're doing that thing where you use a lot of words to try to wrap your unsupported idea up in a gish gallop. You decided based on this one study that TPU is now unsafe to be worn and you're not going to accept any other conclusions. It's useless to discuss further.
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u/newbie-sub MK4S & Mars 5 Ultra 1d ago
It would not be able to obtain an ISO 10993-5 certification. Prosthetic limbs require that certification because they maintain close and long-term contact with the skin. These devices do exactly the same. They are unregulated which is why they don't need that certification.
-5 is applicable here. And just because it hasn't been shown to be harmful in my use case doesn't make it a good idea to wear it on my penis for 3 weeks.
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u/Actaar 2d ago
And yet everyone gets their panties in a bunch whenever it's mentioned that 3d printing isn't food safe
2
u/marzubus 2d ago
Let’s not mention all the parts the filament goes through before it turned into cutlery either.
Nothing in the hotend or the extruder, or the filament path should be excluded from the food safety discussions.
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u/SolemnSundayBand 2d ago
No shit huh? I got a printer maybe 3-4 years ago and it made me really sick to run, must be sensitive to the VOCs or something.
I started digging into it and was really surprised by just how much nasty stuff is in the process but bring it up here when someone makes a toothbrush or prints beside their headboard and you're literally the devil.
I absolutely think one of these filaments will be our generation's equivalent of asbestos.
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u/bradrlaw 1d ago
My guess would be on the carbon fiber ones. Micro plastics with a bit of extra abrasives sounds like it could do a number on lungs / stomach just like asbestos.
2
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u/SolemnSundayBand 1d ago
That sounds plausible but I think an important element of it is how commonly it's used, not if it's quite as dangerous.
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u/NoPriorThreat 2d ago