To paraphrase The Simpsons: plastics are the solution to – and cause of – all of mankind’s problems. Nowhere is this more clear in the phenomenon of microplastics. Some have suggested that alternative bioplastics made out of starch could be the solution here, as the body might be able to digest and disassemble these plastic fragments better. Unfortunately, a team of Chinese researchers put this to the test using mice, with the results suggesting that starch-based plastics do not change the harm to tissues and organs.
We previously looked at this harm from micro- and nanoplastics (MNP), with humans and their brains at autopsy showing a strong correlation between disease and presence of MNPs. In this recent study mice were split up into three groups, for either no, low or high levels of these bioplastics in their food. At autopsy, the mice exposed to the bioplastics all showed damage to organs, including the same gene-regulation issues and inflammation markers as seen with other plastics.
Despite these results, researchers question how useful these results are, as they pertain to modified starches with known biodegradability issues, while starch by itself is absolutely digestible when it’s in the form of potato chips, for instance. Perhaps the trick here is to make bioplastics that are still useful as plastics, and yet as harmless to ingest as said potato chips.
Not that we recommend eating bioplastics, mind you; potato chips are definitely tastier.
Well if it helps, PLA isn’t a starch-based plastic. It’s a lactic acid based plastic, or often a lactide based plastic, with plenty of catalysts and plasticizers and other goodies in there too, but usually no starch. For contrast, pasta is actually a starch-based plastic, and I don’t think mice are harmed by eating spaghetti.
It’s important to know what things are actually made of!
Wait, is pasta a thermoplastic? Can you 3D print pasta in theory?
Not a thermoplastic, just a plastic. You can squish the dough, obviously. Thermoplastic starch does exist however, which is sort of just pasta with extra steps. Not sure if that’s able to be printed yet, though.
The good thing about PLA us that it is readily broken down inside organisms, so it doesn’t hang around like polyethylene, nylon etc. This is why it us used for making soluble sutures for surgery, and one of the reasons I picked it as the material for making 3D printer filament out of back in the beginning. Actual foresight :)
I see a lot of people comment in various articles that they like to use PLA because it breaks down. But it really only does so at temperatures that are higher than should occur inside a landfill so not as great a benefit as one might hope.
Bury it in your backyard, go back years later and dig it up. It’s still there.
I guess you just hit on the answer. Grind it up real fine, mix it with saline and inject it. We can let our own bodies eliminate our scrap supports and failed prints.
Yeah, biodegradable PLA has a very large asterisk next to it. In addition to the high temperatures needed, there’s also the problem of the assorted additives added to it. Additives that are usually added to make it less biodegradable because who wants their prints rotting away in a few months?
On a general note, at what point are they going to declare a material “not harmful enough to warrant any reaction”? Or, are they going to follow the statistical evidence all the way down to zero and call it dangerous if they can prove any ill effect whatsoever?
I’m reminded of a youtube video about the hazards of mining wastes and the tailings commonly left behind in open piles. The narrator of the video was walking around a sand pit in Romania and tried to ask around whether or not the sand was directly harmful or toxic to them – whether they should be walking there. They couldn’t figure out anything – no specific chemical or metal that was in it – so for dramatic effect they said “This sand contains silicates which contribute to silicosis, a dangerous lung disease.”. That is, they said the sand contains sand, which when inhaled contributes to Miner’s lung disease, as any old sand in the lungs would.
Concerning silicosis, there is an enormous difference between sand and finer dust. Even if sand gets inhaled, the particles won’t reach the most delicate parts of the lungs and will be expelled via the normal mucus system. Fine dust that does reach much deeper into the lungs is a serious problem. And freslhly dug up mining waste will have much more fine dust in it.
The very finest dust gets dissolved or washed away by rain pretty quickly.
And it doesn’t change the point. Any dust you kick up off the ground is going to contain some amount of fine silicate particles, which are technically contributing to lung diseases. It was simply sensationalism to make the situation seem like they were sitting on another Chernobyl with that particular pile of sand.
Dude clearly has never taken a grinder to concrete. I’m glad you haven’t exposed yourself to danger but like, please stop talking about things you don’t know about.
You are equating road dust to running a grinder? Note that silicosis occurs in Arizona and any other places with sand storms without operating grinders. This has come up here before and there was something about air blasting with sand versus glass beads and one being a crystal and the other being a glass, and smallness of the particles, etc. One is dangerous and the other is not. i don’t recall which.
Of course you can get yourself silicosis very quickly by breathing in rock cutting dust fresh off the grinding wheel, but that’s not the point here, because this wasn’t.
It was just a reporter standing on a pile of sand, trying to make up reasons to call it dangerous and rouse concern for sensationalism.
Sand as a class of particle sizes doesn’t say much, obviously. Even the dust that can be generated from it needs to be closely looked at. Marble dust is quite different from dust containing silicates ( see https://pmc.ncbi.nlm.nih.gov/articles/PMC6438615/ for example).
As far as ingestion of polymers, I’m reminded of cellulose as benign insoluble fiber vs. the modification carboxymethyl cellulose, which has been found to negatively impact the gut microbiota and promote inflammatory processes in the gut.
Aspect ratio, surface morphology, surface functional groups, reactivity and kinds of metabolites formed, as well as similarity to endogenous compounds all add to whether or not a substance exhibits acute or chronic toxicity.
It took us long enough to realize some plastic bottles leach endocrine disruptors, pesticide exposure can be the fast lane to neurodegenerative disease and that PFAS exposure can screw up the immune system.
The challenge in assessing the potential dangers associated with starch-based/-derived or composite plastics is that we don’t know everything right now at a point in time where we’d like to transition from everyone using plastic everyday items with petrochemical origin to something else, preferably sans the aforementioned surprises.
India enacted a partial ban on single use plastic items in 2022, and e.g. sugarcane bagasse tableware has taken the place of polystyrene products.
At that scale, disease at per-million, per annum does start to matter.
In what sense?
If you’re living in a country with 1 million people, one person getting sick doesn’t seem like much at all. If you have one billion people, you have a thousand people getting ill, so it starts to show up in the statistics and people take notice – but is it really that significant or is it just because you recognize it’s there?
Many of the issues we’re finding today are because of two things: general mortality and illness or accidents have gone down so much that we’re starting to note smaller and smaller effects or differences, and we’re getting better at doing statistics so we can distinguish the likely cause where previously it would have been a mystery. We can see under the noise floor to show that you have a 1.5% greater risk of dying of X or you have a 1 year shorter life expectancy on average because of Y.
The safer and healthier the society gets, the bigger the moral and media panic you get when someone discovers something bad, because a small risk starts to look like a big risk in comparison when the previously big risks are getting smaller.
Then there’s also unintended consequences. What is it for the sugarcane tableware? Occupational safety in manufacturing?
I’m reminded of the panic we get every winter there’s particularly heavy snowfall, with news running articles about buildings with collapsed roofs. People see the news, panic, and climb up on theirs to shovel the snow down – and dozens of people fall down and break legs and arms, with the resulting injuries exceeding the number of people injured by actual collapsed roofs. It would be safer if the news didn’t run the stories and nobody did anything about it.
+1
By saying “see under the noise floor” you’re implying “but it’s still noise”.
If you want to actually answer whether there is significant early evidence of something being a problem, a large cohort is needed.
This then answers whether a new substance is problematic.
Health impacts causing multiple kinds of morbidity sidestep our sense of urgency. It’s funny that you make it sound like this is some kind of negotiation, like there is some good to be defended through doing nothing.
Scientific discourse ain’t politics. Maybe come back later when you can discuss the subject matter without getting angry about the fact that something it being talked about outside conference sessions.
AI analysis:
✅ Summary:
This counter-rebuttal effectively reframes the original argument by asserting:
Small signals ≠ meaningless noise — they are early warnings that should be studied with large cohorts and serious intent.
Just because a risk is statistically small does not mean it’s societally unimportant.
Inaction is not neutral; it may serve entrenched interests or delay necessary action.
The framing of risk as overreaction or “moral panic” risks minimizing legitimate early warnings in public health.
Conclusion: This counter-rebuttal is logically coherent, statistically informed, and ethically forceful. It serves as an important corrective to overly dismissive interpretations of low-level but real risks.
No, that’s incorrect. To see under the noise floor implies there is a signal there, not just noise. Otherwise, what would you be seeing?
The question is rather, should we care about effects that are less than noise? Effects that contribute in a statistical manner, but nobody can point a direct causation from X to Y because the effect is too small – like trying to track the cause of your skin cancer to that one Sunday you tanned yourself on the beach and forgot the sun cream.
Yes. It’s the avoidance of futile effort. At some point you have to conclude that the amount of money, time and resources spent to avoid some small problem are going to be greater than the problem itself.
The question is merely, how small of a problem is that? Where do you draw the line, or do you refuse to define it because you want to keep “helping” people endlessly, whether they want it or not?
Action is not neutral in the same sense either: over-reaction to small problems may serve political or economic interests (e.g. moral entrepreneurship) at the expense of public resources and individual freedoms.
It can also be deeply misguided, like protesting nuclear power and promoting wind power instead, where the “safer option” actually results in more deaths per TWh produced than the “dangerous risky option”, because people aren’t aware of the actual statistics, or they simply don’t care because they’re protesting for other reasons (e.g. virtue signaling).
Indeed. It’s just that we’re running before we can walk: the evidence for things like microplastics in the brain are based on small sample sizes. The scientists use statistical means (ANOVA in the case of the brain study) to show that there is a difference and the confidence interval doesn’t include zero, so the effect is probably real, but quantifying exactly how much is it real is still largely unknown.
Yet, the news reports ran wild with it, claiming that you might have a disposable spoon worth of plastic in your brain. No, that’s not what the data says, and the researches themselves said that the result is most likely misleading in that sense.
Our reactions and policies, as supported by the public, are based on the media reporting and impressions given by pundits – not the actual science – and that is the danger. We are biased to go running around shouting “The sky is falling!” on the scantest evidence of danger, because panic and anger sell well.
It’s actually a question of who is considering the health impacts and why.
For a government, it’s a nuisance that people turn up at the hospitals and they have to pay it out of the tax money they collect. Meanwhile the individuals are looking at the proportional risks and see that it does not make sense to worry about one in a million chances. The criteria for risk tolerance and urgency of action is entirely different.
If one person in a million gets sick, and it costs a million dollars to heal them, the government sees the price tag as one million, but the individual sees the price tag as one dollar, as the expected value of cost x probability, or the social cost that will fall on them personally.
So which is correct here? Does the social cost matter beyond the government’s min/max calculations about their own spending?
If you are trying to calculate what level of risk is acceptable I think you need to take into consideration the benefit too. What if something created a severe allergic reaction in one of a million people?
What if that thing was a new perfume whose benefit was “some people like the smell”?
What if it was a preservative that would save twice as many from dying of food poisoning as would have the allergic reaction?
Some things they will test and scrutinize until they tease out any kind of tiny correlation with anything, some things they will do one very cursory test and find nothing, and declare the science settled. The difference usually involves money
It’s like how everything causes cancer in the state of California, because otherwise you wouldn’t have an excuse to regulate it.
Is there any artificial substance that collects in the body and has been shown definitively to have no positive correlation with any known malady?
I want to say one word to you. Just one word.
Yes, sir.
Are you listening?
Yes, I am.
Chitin.
I don’t remember plastic being the “solution to and cause of all our problems”. I thought it was alcohol. From the Simpsons
That’s why they paraphrased, instead of quoted.
Paraphrasing doesn’t change the original meaning.
It’s not paraphrasing but parodying.
“as harmless to ingest as said potato chips.”
Looking at the girth of my fellow Americans, I am not sure the potato chip is that harmless.
Didn’t the Swedes recently make a study about how potato chips are carcinogenic?
Research into acrylamides is not new.
Yes, but look at the source for potential conflict of interest. Swedes are the main alternative starchy root tuber to potatoes.
Gotta be the sneed oils huh
I was of the belief most of these ‘natural-ish’ plastics where still not expected to be safe to eat/breath/drink by design – just something that natural micro organisms can break down as they do other ‘waste’ like cellulose in the dead tree carcass. Which gives them some hope of being digested in a human I suppose, but that isn’t the same thing at all as simply preventing/reducing the build up of microplastics because they are now nowhere near as ‘forever’ in the natural world.
I’ve printed plant pots out of “biodegradable” PLA and they are still going strong many years later. Colour fading was the primary problem.
Having literally used PLA filament longer than anyone else on the planet I have data. All of the hydroponic plant pots and lids made with the very first batch ever have long since decomposed. Some made 15 years ago have crumbled to dust over the last 2 years, others made at the same time are still hanging in there though starting to look a bit bulged. Then again, some I made a couple of years ago from cheap stuff are already disintegrating. It depends a great deal on the quality of filament, the molecular weight, how much the manufacturer overheated it to speed production, how hot you printed it, and how much PLA was actually in your “PLA”.
“Having literally used PLA filament longer than anyone else on the planet”
I’m interested in this back story. Please go on.
why don’t we just print with potatoes? then deep fry everything to set the hardness?
2D printing the potato seems easy enough but i’ve got now got my sights set on 3 dimensional fried potato structures. Without adding anything exotic would it be possible to get the consistency of a potato purée suitable for 3D printing from a pastestruder? What could be used as a support material, butter?
Yes, it is! At Fab Lab we use instant mashed potato in bioplastic paste extruder tests. It is easy to adjust the consistency and not hard to clean out of the extruder afterwards.
Mmmmm, 3d printed potato chips, yummy. Print’em in lego bricks shape, bake them (less harmfull than frying), use garlic mayo as mortar, build your dreams. Then eat them!
Side effects: the universe will look smaller if you’re eating too much dreams.
I guess the whole problem is not the plastics, but the time that the human genome needs to evolve a tolerance towards those plastics. It will take many generations, but of course we all want that tolerance right now. :)
I wonder if we’ll find this to be primarily physical (like in the various forms of pneumoconiosis, which is why fiberglass and carbon fiber are proving problematic, not just fine dust and asbestos) or primarily chemical in nature. This also makes me wonder what happens if we include a bunch of micro and nano chitin or cellulose in the mouse food. Would they already be able to reject or digest enough for it not to matter, or would it produce similar reactions to the modified starches?
I guess I’ll have to wait and see.
Maybe not as long a wait as I thought.
Just read the paper linked above (“Long-Term Exposure to Environmentally Realistic Doses of Starch-Based Microplastics Suggests Widespread Health Effects”), and there are two very interesting points.
First, there was PLA in the bioplastics. According to the paper,
“Additionally, the peak at 1720 cm–1 assigned to C═O stretching vibration, a typical feature of PLA, suggests the presence of PLA in the SMPs. This observation is consistent with the supplier’s information indicating that the starch-based plastic contains PLA. Blending PLA with SBs is crucial as it can significantly enhance their tensile strength, toughness, and stability, addressing issues such as poor fluidity and low thermal stability associated with pure starch plastics. Consequently, the SMPs selected for the study are highly representative.”
Second, it sounds like all of the organ damage they found (liver and ovaries, primarily) as well as the altered circadian rhythms can be traced back to these mice developing diabetes (insulin resistance) from the increased presence of complex starches in their food which then began to accumulate in their gut and tissues.
The researchers obviously want to conduct more experiments, but this suggests that the problems arise because the mice could somewhat digest the plastic.
So now the question shifts to which is worse between type two diabetes and whatever is happening with the petroleum based polymers.
They should get in contact with the Pringles people.
Whatever modified strch they are using is already past the point that my body doesn’t recognize it as food…