Microplastics in the human brain

[timr]

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."

[userbinator]

IMHO the more important part is they used pyrolysis gas chromatography, which breaks down all polymer chains.

Besides man-made plastics, guess what else has long hydrocarbon chains, occurs naturally in humans and other biological matter, and behaves similarly under pyrolysis...

https://en.wikipedia.org/wiki/Fatty_acid

Here's an interesting related article: https://www.oaepublish.com/articles/jeea.2022.04

Analysis of saturated, monounsaturated and polyunsaturated fats was demonstrated to form the same pyrolysis products as PE

[rthomas6]

Well, it still tells us something. What are the upper and lower bounds of whole brain microplastic content, given that 25% variation?

[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

[throwaway81523]

How did the amount of brain microplastic manage to double between 2016 and 2025? The amount of cars hasn't changed that much.

[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.

[CommanderData]

Government could force car tyre companies to invest in developing plastic free tyre alternatives?

If there's no regulation then there's no will or urgency to waste money doing so.

[meindnoch]

Mass rail transit.

[mythrwy]

Move away from big cities and high traffic areas in the meantime is my solution.

[newsclues]

I love breathing brake dust too!

[niceice]

What percentage is that?

[mondobe]

Perfect, I was hoping to increase my neuroplasticity.

[knowitnone]

I recognize and acknowledge your humorous post.

[nusl]

Doctors HATE this one trick! Click here to find out!

[HaZeust]

Nice.

[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)

[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.

[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.

[tcfhgj]

> Nobody is going to stop driving. Car tires are the largest source of microplastics.

many already have, bicycles and public transport ftw

[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.

[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).

[mindwok]

I find this hilarious. Why would they choose such a misleading unit

[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]

[1]: https://news.ycombinator.com/item?id=42958104

[SecretDreams]

That's not great

[TZubiri]

So more

[chiefalchemist]

As I understand it, they took a small sample of brain tissue, extracted the plastic, and then extrapolated that (based on the tissue sample size) over the whole of the brain.

This assumes the presence of plastic is evenly distributed throughout the brain, which isn't necessarily the case.

[medellin]

I would think that we would be seeing a lit more issues if we had that much plastic just in our brain. But maybe our body doesn’t mind all that much. I guess we will see how things play out in another 30 years though.

[mythrwy]

This is one of those headlines that smells like nonsense before even reading the article (doesn't mean it is nonsense, but the quantity advertised seems implausible).

[robocat]

I am hoping that they discover that polyethylene is a natural component of brain chemistry.

[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…

[_sys49152]

I rode a hard plastic bike seat on my bmx to school and back everyday. eyes emoji. my kids i shoot out will be g.i. joe figurines

[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

[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.

[alana314]

I think this is a conversion error. According to the ABC story about this the brain has 4800 micrograms of microplastics. That's alarming, but that is 4.8mg, which is .0048 grams. A plastic spoon is over 4g. They mixed up micro and milli and were off 1000x. ABC news: https://abcnews.go.com/Health/brain-tissue-higher-amounts-mi... Original study: https://www.nature.com/articles/s41591-024-03453-1

[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.

[kaiwen1]

Pre-print paper that concludes “may”, so by implication, also “may not”.

And also may, or may not, be harmful.

[renewiltord]

Sounds like methodological error. Like your black spatulas. Somewhere they’ve divided by zero, clamped, and averaged or something dumb like that.

[koolala]

I thought it was our gonads that had the most?

[jdiff]

This statement isn't necessarily at odds with that one.

[purplezooey]

Well, Vonnegut was right. It's just a dog's breakfast.

[synergy20]

why did not they got flushed by our digestive system,yes micro plastics are tiny,still they are too large to get into arteries and veins thus no way to reach the brain?

[stevenwoo]

Nanoplastics can be so small that they can get inside most cells even blood cell so could pass through gut lining and blood brain barrier and sometimes are shaped like the key/lock our body already uses for certain intracellular chemical interactions and interferes with the correct molecules doing work, so they can be both inert for the most part and harmful because our cells just don’t just eject them automatically - though there also appears to be some max amount based on exposure level. The vast majority we might eat is excreted in bowel movements and urine and it still accumulates in tissue due to ubiquity. article for laypeople https://www.npr.org/sections/shots-health-news/2024/12/18/nx...

[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.

[ed_mercer]

Even if you could invent it, I don’t think there would be demand for it (yet)

[booleandilemma]

Does it have a negative effect on us though?

I mean, assuming I do have a spoon's worth of microplastics in my brain, I don't notice any impairment.

I write JavaScript just fine.

[scotty79]

Cool. Now how much sand is in your brain? Equivalent of two glass spoons? Sand dust is way more abundant than plastic and similarly inert.

[crazygringo]

You're being downvoted, but I think it's a really good question.

We eat and breathe all sorts of stuff that comes in nano-sized particles. We've been inhaling smoke from cooking fire, eating plant matter crushed between rocks rubbing against each other, drinking water with dissolved bits of all sorts of things, and so forth for many millenia now.

The body seems to have mechanisms to clear most of this stuff out of us over time, no? Isn't our body chock-full of waste products from our cells that are constantly getting flushed out? Is there any reason to think that nanoplastics would be different?

[pfdietz]

Or plant fiber. You eat enormous amounts of this stuff that you can't break down.

[kijin]

Depends on where the sand is. I don't want that stuff in my lungs.

[megamike]

just a spoon full of plastic helps the medicine go down the medicine go down the......

[deadbabe]

Imagine if microplastics in the brain could somehow be utilized by neurons for really long term memory storage or something.

[TZubiri]

No

[SV_BubbleTime]

Nonsense article, you could fit way more than that.

[yapyap]

baity headlines that scare the shit out of you, exactly what I’m NOT looking for on HN

[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!”