Human Brain May Contain as Much as a Spoon's Worth of Microplastics
116 comments
·February 6, 2025timr
rthomas6
Well, it still tells us something. What are the upper and lower bounds of whole brain microplastic content, given that 25% variation?
timr
I couldn't begin to tell you. It's not a 25% variation, once you've extrapolated from the samples by 10,000x (or whatever). The 25% inter-sample error was on a few replicas of teeny tiny measurements. The post-extrapolation error bars are so wide that they're meaningless.
The Smithsonian magazine article is garbage. Ignore it. The paper is saying that they see longitudinal trends in plastic bioaccumulation in various cadaver tissues, and this is plausible. But no, you don't have a plastic spoon in your head. That's just panic porn.
sympil
How many microplastics in the brian are aceptable?
idiotsecant
Obviously parent post is not making the point you're trying to argue, only making the point that the measurement is flawed. If you are going to address their argument do it in good faith and address the strongest point. This isn't reddit
throwaway519
The parent is using HN pedantry to stroke an intellectual ego.
At no point did they mention other studies, methods, methodologies. Just point scoring hit and run. I felt the curt reply was wholly fustified.
Glib comments like the parent burnish the reputation of HN.
pinkmuffinere
Thankyou. I think I will quote your last two lines frequently.
sympil
I did address their point. The tendency with climate change, micro plastics, etc. is to deny, deny, deny, until it is too late. Perhaps we should err on the side of caution. In this situation its much better to err on the side of being overly cautious.
Experts wrote the research paper. Until otherwise demonstrated I will give them, the experts, the most generous interpretation per site guidelines. The experts addressed the concern by OP but OP calls it “brushing off”.
People can nitpick anything. The question remains, just how much microplastics are OK? If the answer is small then the study has merits despites its alleged issues.
morpheos137
[flagged]
Kapura
Remember that car tire degredation is a significant portion of microplastics in the environment. Investing in mass transit is as imperative as it was to move away from leaded gasoline.
hammock
And we need more lightweight cars , not heavier, since tire wear is proportional to vehicle weight to the fourth power. Ironically, CAFE regulations and EV incentives both did the opposite
ethagnawl
I'm not sure why you're being down voted for suggesting a practical and fact based solution. The USA is, regrettably, not making a pivot towards public transportation anytime in the near future. So, lighter cars are one way to address this issue.
You didn't expound upon your point about the unintended consequences of CAFE standards but they're very real. Instead of making smaller and more efficient sedans per the guidelines, car makers opted start making all of their vehicles "light trucks" -- 80%+ of new vehicles are SUVs or bubbly looking "crossovers" -- which are not subject to the same demanding standards. Small sedans also cost less and would require ongoing R&D to continue to meet the CAFE standards. The end result, as this thread is interested, is heavier vehicles with bigger tires and more plastic in the environment and our brains.
linotype
Los Angeles would be very difficult to transition at this point, it’s just too low density. It was better 100 years ago than it is now.
borski
You’re right, but the thing that leads us to lighter EVs is solid state batteries.
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repiret
Do you have a citation for the vehicle weight to the fourth figure? There is about a 2X variation in the weight of the vehicles I’ve owned, but even accounting for differences in tire size, I can’t come up with a 16x difference in how often I change the tires.
Thinking about it a different way, there isn’t much difference in recommended tire pressure among the autos I’ve owned. That means that the pressure between the road and the tire is relatively constant but the surface area of contact is directly proportional to vehicle weight. For a fixed contact pressure, I am struggling to imagine a physical process by which the rubber loss is not proportional to the contact area.
daemonologist
The fourth power law is usually applied to deformation of asphalt roadways (here's a citation for that: https://www.researchgate.net/profile/Maxwell-Lay/publication...); I haven't heard it applied to tires before. If I had to guess I'd agree with you - I would expect a smaller exponent, particularly if the tires are designed for the given load.
darkmighty
I know this figure comes from road wear. I don't know if it applies to tire wear, and indeed I suspect it doesn't, if only because tires tend to scale with vehicle weight as you mentioned. I think road wear may be associated with structural cracking of the road which may not change significantly with tire area.
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twelvechairs
Roads and road standards are a tragedy of the commons. People keep buying bigger cars and demanding more, wider lanes and parking spaces because they don't take any of the burden individually - it's the taxpayers as a whole that foot the bill.
Paradoxically most of the 'small government' types are often the biggest road users.
joseangel_sc
I don't think this is entirely true but we need more research https://youtu.be/FcnuaM-xdHw?si=6bvFQdUjHi28CugV
kijin
> tire wear is proportional to vehicle weight to the fourth power.
Does this mean that a bus that weighs 10 times as much as a small car will produce 10000 times as much tire dust? If it does, I'm not sure if investing in buses will reduce tire dust at all. A bus can replace a lot of cars, but 10000 is a stretch. We need more trains.
zamadatix
I think the root observation here comes from https://en.wikipedia.org/wiki/Fourth_power_law which really talks about the inferred stress to the road for given weight on the axle, not tire wear based on vehicle weight. The above seems to be using a simplification based on passenger cars staying with 4 tires across 2 axles but how this relates to tire wear is going to be a bit more complicated when you start talking about vehicles which can have more axles, more tires per axle, and significantly larger tires.
I'd believe buses have a lot of tire wear compared to an individual car but I wouldn't use that relation as proof of just how many times so.
penjelly
trams were popular in tons of places before, I understand they improved traffic significantly compared even to today, and they'd still have a positive effect now, I think. But most places shifted towards a car centric focus and we lost those.
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guelo
None of these things are going to happen. Voters keep voting with their votes and their wallets that they want bigger cars and don't care about climate change. Meanwhile billionaires have hijacked most of our mass media as we blow by the 1.5°C Paris agreement and Trump dismantles our science institutions.
penjelly
EV/hybrid only "zones" in Europe are crazy to me because the electric cars leech more tire carbon into the air anyway. Some regulation seems intelligent on the surface, but the devil is in the details.
hatthew
Solid/particulate pollution from tires is definitely a problem, but in terms of carbon specifically isn't it many orders of magnitude less than the carbon from gas engines or electric power plants?
dashundchen
EV/hybrids also have regenerative brakes so emit less brake dust. Between emissions, tires, and brakes I'd be curious to see how it balances out.
But really cycling and transit are the way to go to make cities more liveable. Personal cars take too much space in a city and ruin the built environment for everyone not in one.
throwaway81523
How did the amount of brain microplastic manage to double between 2016 and 2025? The amount of cars hasn't changed that much.
markerz
Perhaps you're thinking our body is at equilibrium with the amount of plastic in our environment, but the reality may be that our body accumulates microplastics from the environment and they become concentrated over time. Kind of like how we can't get rid of heavy metals from our body, so eating lots of fish accumulates mercury to toxic levels. But eating fish is a conscious decision whereas microplastic exposure is an unavoidable fact of life now.
JKCalhoun
User hammock, in this thread, may have suggested an answer.
7e
Or one could just mandate that tires contain only biodegradable ingredients. That seems an inevitable step since wheel isn't going away no matter what the level of public transportation is. Some public transit, like busses and some subways, use rubber tires today.
newsclues
I love breathing brake dust too!
mythrwy
Move away from big cities and high traffic areas in the meantime is my solution.
shironandonon_
Doesn’t work. It’s in the rainwater. No rainwater on earth is safe to drink.
mythrwy
Does osmosis remove? Is it in all groundwater?
Because I have a well. A deep one. And an osmosis system.
dymk
Hope you never have to drive to the grocery store
nozzlegear
My grocery store is literally in another town 20 miles away. I have an EV but apparently those are even worse for microplastic generation. Am I screwed?
epistasis
Imagine a grocery store that is within a short walking distance, such that you don't need to haul a weeks worth of groceries but can get fresh food every single day.
US supermarkets are massive, take forever to buy small amounts of groceries, and even the walk to and from the car is long.
A better world is possible! (If better grocery stores constitute a "better world")
mc3301
15 minute cities is the answer.
bilbo0s
Not only that, but if you're close to a road at all, you'll intake the micro-plastics and nano-plastics.
So you really need to move away from roads. That's possible, but it's really hard to do in most developed nations. Just moving away from a city won't get you to where you need to be. Even when you get there, you have other issues. Like, food, energy, water/sewage treatment, etc.
I don't think people realize how difficult it would be to get away from this particular pollutant in our environment. I mean most of us don't own 500 acres in the Brazilian, Namibian, or Ghanaian countryside that we can retreat to. Even Brazil may be too far gone at this point to be honest. And Brazil is enormous. A lot of space. The number of tolerable nations that would have unaffected areas is decreasing fast. This really is a global problem.
ETA: Some remote parts of Canada and Alaska might fit the bill? Assuming you're not big on quality of life.
mythrwy
I don't think you understand where I'm living.
"Microplastic Free", no, there is no such thing right now. But I'm very far from any major roads/interstates and hundreds of miles to any big city. I didn't move out here to avoid microplastics though, it just (maybe) turned out that way.
I'm actually not terribly afraid of microplastics at all, I just don't like urban environments.
forgetfreeman
Hope you never have to haul a family of 4 worth of groceries on a bus.
hackernoops
[flagged]
shironandonon_
I like the analogy where other articles have said we have microplastics in our brain about the size of a credit card (which generally weigh between 4g and 10g) better.
Saying a “spoon’s worth” seems to be downplaying the unmitigated potential risk. We have no idea what will happen as we (and all the other creatures on earth) keep storing more and more microplastics in our organs.
Nobody is going to stop driving. Car tires are the largest source of microplastics.
(actually I don’t drive though so who am I to judge)
wruza
Not to mention that all spoons are different. I always get confused about “half a spoon”. Is it half of a “pile” or there must be half of its surface visible from above, while the subject matter is flat in the spoon (i.e. the lateral projection shows only the spoon). And should you account for the pile slope in case of bulk materials? And then when you figure that out, your spoon may be anywhere 0.5-1.5x in size/depth than someone else’s. It may be literally 3x times more or less. But even that is still less inexact than measurement extrapolation methods that the article uses, according to the top commenter.
plagiarist
I was trying to figure out from the headline if they meant enough microplastics to fill the bowl of a spoon or microplastics equivalent to a plastic spoon. I don't know why everyone is allergic to weights and measures.
If they're going for shock value they should use something more sinister than a spoon. Like enough plastic to make a little decorative Halloween spider. People would be more frightened by a spider than a spoonful of plastic.
roenxi
> unmitigated potential risk
The risk does seem fairly mitigated, most of us will make it through today fine. The only part of my brain I can account for now is the 1x credit card worth of plastic, all the other bits are a mystery. Death was inevitable before the microplastics, remains inevitable after the microplastics and things seem fine so far.
We don't know much about the risks of anything. People regularly douse themselves with mind-altering substances and ingest the weirdest variety of stuff.
rTX5CMRXIfFG
Shortening your period of observation so that the effects have not occurred yet does not mean it’s “mitigated”.
And your philosophy of your own mortality is just as reductive, because humans have been trying to survive since time immemorial and do not actively work on their deaths unless in an unhealthy mental state.
card_zero
Seems like a more important problem, then, the part where people inevitably die. I mean compared to having some plastic in their heads.
itishappy
> The risk does seem fairly mitigated, most of us will make it through today fine.
This is an incorrect usage of the word "mitigate." To mitigate means to lessen the risk. Mitigation requires action.
I suspect you mean that the risks are "overstated."
roenxi
I barely think the risks have been stated at all. They found a correlation between high levels of microplastics in the brain and dementia. There is a correlation between a bunch of things and dementia. I expect there is a correlation between good health and dementia, unhealthy people would tend to die off young without the time to fall apart mentally.
SmirkingRevenge
Would be nice if just once these sorts of things could have beneficial effects.
card_zero
Like the ship-produced aerosols that seeded clouds, increased albedo, and cooled the planet, in what James Hanson has called a "Faustian bargain". We successfully stopped that with regulations.
tcfhgj
> Nobody is going to stop driving. Car tires are the largest source of microplastics.
many already have, bicycles and public transport ftw
lenerdenator
There's realistically fewer than twenty metro areas in the US where the majority of commuters could rely solely on biking and public transit for everything. Twenty might be generous, even.
sien
Since the pandemic passenger car miles, airline miles are back at pre-pandemic levels.
Transit use is at 80% of pre-pandemic levels.
https://ti.org/antiplanner/?p=22722
Farebox recovery ratios have consequently become even worse.
The new US government is also presumably not going to fund much transit expansion.
It'd be interesting to see if more people work from home on a given day than use mass transit to get to work.
It's also pretty similar in Australia at least and probably in more places around the world.
idle_zealot
There is a positive spin on this: the majority of Americans already live in or near dense urban centers. If we had solid public transportation only within these centers and to adjacent suburbs we would eliminate most car trips. That's bot much physical area to cover.
knowitnone
still rubber so still microplastics?
card_zero
To me, the spoon sounds scarier. But I don't think there's a right answer to how scary a new phenomenon should be made to sound. You want it to sound scarier, this thing we don't know much about? Won't that happen naturally since everybody's ready to be scared of news anyway? Is it being downplayed? Relative to what, hunches? The information should be presented dispassionately, but engagingly, and that is an impossible combination, so it what we'll actually get is always something with the wrong overtones.
mondobe
Perfect, I was hoping to increase my neuroplasticity.
knowitnone
I recognize and acknowledge your humorous post.
bhaney
> not a spoonful, but the same weight as a plastic spoon
oh
smnrchrds
- There is a horrifying 512-ounce version that they call Child size. How is this a Child-sized soda?
- Well, it's roughly the size of a two-year old child, if the child were liquefied.
silisili
That's both a misleading headline and a really odd unit of measurement. So odd that I wouldn't be surprised if the US adopted it as the official unit of measurement of microplastics (I kid, as an American).
ryandrake
How many Bald Eagle Per Football Fields would that amount to?
upghost
do we need a unit conversion for how many spoonfuls of plastic are in a plastic spoon?? seems like it might be important for this article.
Well article says a teaspoon has 7g mass, and just spitballin here but I'd say a plastic spoon has about 1g/cm^3 density. And there are 4.83cm^3 in a teaspoon. So I guess in fact there are 1.44 teaspoons of teaspoon in the brain. Or would that be 1.44 tsp^2...?
But I'm an American and I have at least 3 imperial teaspoons of microplastic in my brain or gosh darnit I'm 2 bald eagles short of a touch down. If you know what I'm sayin.[1]
mindwok
I find this hilarious. Why would they choose such a misleading unit
card_zero
Isn't it about the same?
How big is a spoon, anyway?
SecretDreams
That's not great
null
jondwillis
Really regretting chewing on all of those straws as a kid, eating hot food out of all of those takeout trays, keeping my car windows open, living near roads… and…
adriand
The only good news here is that it's possible that the body can clear the plastics. This is from the linked study:
> While we suspected that MNPs might accumulate in the body over a lifespan, the lack of correlation between total plastics and decedent age (P = 0.87 for brain data) does not support this (Supplementary Fig. 1). However, total mass concentration of plastics in the brains analyzed in this study increased by approximately 50% in the past 8 years. Thus, we postulate that the exponentially increasing environmental concentrations of MNPs2,14 may analogously increase internal maximal concentrations. Although there are few studies to draw on yet performed in mammals, in zebrafish exposed to constant concentrations, nanoplastic uptake increased to a stable plateau and cleared after exposure15; however, the maximal internal concentrations were increased proportionately with higher nanoplastic exposure concentrations. While clearance rates and elimination routes of MNPs from the brain remain uncharacterized, it is possible that an equilibrium—albeit variable between people—might occur between exposure, uptake and clearance, with environmental exposure concentrations ultimately determining the internal body burden.
Which means that if we were to take action on this, we might actually be able to reduce our exposure. Unfortunately, things are going in the wrong direction.
I keep thinking it would be nice if microplastic exposure were to start generating the kind of focus and controversy that is currently taking place with vaccines and autism spectrum disorder.
russdill
My understanding is the best thing you can be doing along with reducing exposure is regular blood donation
card_zero
Pass the microplastics along to some other sucker, a cunning plan.
lemonberry
Interesting. My father has received a ton of donor blood over the past few years. Once he's gone I'll be donating regularly. My father's alive because dozens of people donated.
To anyone here that has made a deposit to the blood bank: we thank you.
knowitnone
blood bank CEO thanks you too because the make millions selling your blood
ericd
So what you’re saying is that leeches as medicine are coming back.
throwaway657656
dilution is the solution to the pollution
throwaway657656
>>environmental exposure concentrations ultimately determining the internal body burden.
As another commenter asked "How did the amount of brain microplastic manage to double between 2016 and 2025?" It is doubtful that the environmental concentration level doubled during this time.
latentcall
So are we okay with this? We don’t want to hurt industries or the market so we should accept this, right? I think it’s extremely important that Nestle and Coca Cola continue to be successful. I certainly don’t mind eating plastic if it means the market does well.
Okay I’m sorry for the snark but when these articles come up some are like “the studies are inconclusive of the effects” but I’m just like “there’s plastic in your brain!”
mreid
I must have some of that microplastic in my brain since I misread the start of the title as "Human, Brian May, ..." and then couldn't parse the rest properly.
odyssey7
Is there no molecule that could be designed which would break down microplastics throughout the body, without harming biological materials? Or even just the blood stream?
I’m not a chemist, but it seems like if this can be done it would be huge.
yapyap
baity headlines that scare the shit out of you, exactly what I’m NOT looking for on HN
null
This paper came up as a pre-print. You can't make the extrapolation that the headline is making - they're using gas chromatography to estimate quantities from 1-2mg samples, and then extrapolating to get to these scary sounding whole-organ estimates. If you look at the paper [1], you'll see that the microplastics in in situ samples are not discernible by light microscopy, and that there was a ~25% variation in within sample measurement of the GC [2], indicating a great deal of uncertainty in the precision of the fundamental measurement (the authors brush this off; see quote below).
Basically, you've got an extremely sensitive measurement system being used to make tiny measurements, and then they extrapolate these measurements by a huge factor to get to ug/g estimates. Further extrapolating (to the weight of an organ, say) when you know that there's 25% inter-sample variation, is just guaranteed to be nonsense.
[1] https://www.nature.com/articles/s41591-024-03453-1
[2] "Both analytical laboratories (UNM and OSU) observed a ~25% within-sample coefficient of variation, which does not alter the conclusions regarding temporal trends or accumulation in brains relative to other tissues, given the magnitude of those effects."