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Bioaccumulation of Microplastics in Decedent Human Brains (nih.gov)
131 points by apsec112 11 months ago | hide | past | favorite | 153 comments


Terrifying study: “total plastics mass concentration in brains increased over 50% in the past 8 years”. Their 2024 brain matter samples are on average 0.48% plastic by weight, if I am reading this correctly: “The brain samples, all derived from the frontal cortex, revealed substantially higher concentrations than liver or kidney, at 3,057 μg/g in 2016 samples and 4,806 μg/g (0.48%, by weight) in 2024 samples, ranging as high as 8,861 μg/g.”

The only good news is that apparently the brain can clear these particles; the problem is that there is a steadily increasing amount of exposure which means that rather than clearance, there is accumulation.


> Terrifying study

Easy on the hyperbole. Let's assume that this study is correct, and everyone at median age of 50 is walking around with this level of microplastics in the stated organs. Are we all dead? Disabled? Dying? No. Our lifespans are amongst the longest in human history. I'm doing OK. How about you?

Far bigger practical concerns are that we're fat and lethargic and suffering from metabolic disease, heart disease, cancer and diabetes en masse because we eat too much. About the only thing you can do with this finding is wave your hands around and make hypothetical links to this and that (as they do in the paper), or try to claim that this is really, secretly the underlying cause of the stuff that is actually, observably killing us.

I'm not saying there's no concern here, but I am not "terrified" of this. I am actually scared of getting fat, or falling down when I get old from being weak. These are things that happen to nearly all of us.

Anyway, first rule of science: when we look for things, we find things. If you are "terrified" by everything new you find, you are applying an emotional judgment to what you see, and not being objective enough.


> you are applying an emotional judgment to what you see, and not being objective enough.

The notion that scientists can or should be emotionless, and that this somehow produces 'objectivity', should really be consigned to the history books. Expectation and promotion of emotional detachment leads to burn out, anxiety, unrealistic expectations, unsupportive working environments, poor judgement, dehumanising of experimental subjects, etc etc etc. See the majority medical and psychiatric science history.

I'd far prefer different terminology. Maybe 'calm' or similar. Expecting and encouraging scientists to be calm is more realistic and achievable, and doesn't deny the fundamental reality that much of human existence has an emotional component.

Panicking over microplastics in human brains is surely an entirely understandable reaction. Rather than criticising it, we can learn from it. I want my healthcare researchers to be calm but strongly motivated.


> Are we all dead? Disabled? Dying

The problem with poisons is that we view them in a binary way. They're either bad, or they're not. They either hurt you, or they don't.

But in reality it doesn't always work this way. There's infinite levels of bad.

Eating off a lead plate, as the greeks did, is poisonous but certainty not deadly. Nobody was disabled.

Instead, the rich just slowly went insane over the course of their lives. Across decades, their mental state deteriorated as they grew mad. For their society, impossible to perceive. Too slow, too widespread.

Obviously we don't know the extent or even if there is anything bad about microplastics. But if there were, would we even be able to tell by the time we get there? Or would that just become life?


Could lead plates be found in the arctic, or in clouds ?

Personally I feel like the environmental contamination is the problem. Let's say we do workout this is causing some type of health issue, that's it , there is no way to fix this. We've contaminated everything with microplastics and there's little doubt , if we keep doing it, it WILL cause major issues, at least for the ecosystem, which we do rely on and that will have negative effects for us.


Yeah, I know. The dose makes the poison. Water is toxic if you drink enough of it.

The point is: without evidence that "the poison" is actually toxic, and certainly without evidence that it's more toxic than anything else you're regularly doing, then you're effectively just fretting. In the case of microplastics, we basically have neither. We have some weak lines of evidence of minor harm in other animals, and lots and lots of theories about what might happen.

Note that I didn't say "don't worry about it". I just said "don't be terrified".



I've read a few years ago (pre-Covid) on nanoplastics about fertility, late miscarriages and premature birth, they found a lot of correlations and wrote that further research is needed to find if it's more than that.

I don't really care about plastics, fertility or fœtus so I won't pretend I do, but if you do, maybe look into it?


>I am actually scared of getting fat

Not getting fat is easy, avoiding microplastics is not. One problem affects people with a certain lifestyle, the other affects everyone (it's an environmental issue).

Also, as the article points out, the amount of microplastics accumulated in living organisms is still rising. It's something that needs more attention.


I would argue obesity is also an environmental issue and is not necessarily an issue of lifestyle. Sort of akin to smoking 40 years ago. Yes that's a lifestyle but also not really.


I have to agree. Making a big deal about microplastics when we’re overweight, sedentary, and atherosclerotic seems like stepping over dollars to look for pennies.


Anecdote. I'm not overweight. I took control of that part of my health. With microplastics, I have very little or no agency over.


How so?

Personal choices go a long way, here. Exclusively use glass and metal cookware, utensils, food containers, and straws. Don't paint your fingernails, or if you do, don't chew your nails. Don't eat fast food, takeout, or DoorDash, be selective about your restaurants (tour the kitchen if you can). Wash your vegetables. Buy from butchers that wrap in non-plasticized paper. Don't live in cities with poor air quality. Replace StainMaster carpets with ceramic tile. Don't eat large predatory fish like tuna, (avoid large predatory animals in general, as they are metals and plastics concentration machines). Buy bottled water in glass only, or filter your own.

Can you reduce your intake to zero? No, but you can get pretty close.


This accounts for an extremely small part of your microplastic intake. The vast majority comes from air particles from tires, and then the rest from water due to washing synthetic fabrics.

Until you can figure out how to stop breathing and drinking, you have microplastics in your body. In fact there's no organisms left on Earth without microplastics in their body. Which is why everyone is making a fuss. If this does turn out to be a problem, we're kind of fucked.


Well, that's a great point: let's concede that you have no control over this. What, exactly, would you have the rest of us do, other than panic?

This kind of "terror" is usually little more than a backdoor way for someone to advance their low-evidence "science" agenda:

"I'm scared of X, therefore all of you must worry about it too, and that means stop doing/using X, and/or do exactly what I say to minimize the impact of X."


I don't understand why talking about it is treated as panic. I'm certainly not panicing, but it seems to me you're freaking out a bit about this.

I'm not saying you have to do anything. I'm saying that microplastics are prolific, and we don't understand the effects. That's just reality.

Personally, I believe on a political scale we should be reducing our plastic consumption. Because it creates far too much waste.


The entire thread is in response to someone calling this study "terrifying". That was the entire point of my comment, and what I am talking about.

You'll note that I never said that we shouldn't do more research. You'll also note that sibling comment (agreeing with you) is calling for regulation and government action. So maybe you are just calling for research, but...

> Push for better understanding and maybe regulations to help reduce the impact. Again, with getting fat I have agency over. It's on me to do it. With microplastics, government action is needed, so we need to be better informed and press government to act on our interest.


> What, exactly, would you have the rest of us do, other than panic?

Advocate for a reduction in plastic manufacturing, consumption and waste. It's pretty straightforward. We did it with lead. I acknowledge that there are certain things that we make with plastic that modern society requires to function. For the rest, if we cannot manage to figure out how to keep this stuff out of our bodies and brains, then we should be replacing it with alternatives.

The part about this study that I personally find terrifying is the trajectory. A 50% increase in 8 years is astonishing. Without more data points we don't know what curve we are on right now (logarithmic? exponential?) but is this an experiment we really want to be running on our brains? I can tell you that this experiment participant wants to opt out immediately.

We are talking about bioaccumulation of an environmental pollutant in critical human organs here. The precautionary principle would seem to apply.


> Advocate for a reduction in plastic manufacturing, consumption and waste. It's pretty straightforward.

Well, thanks for being explicit about it, I guess.

> We did it with lead.

Yeah, you skipped a step: we know that lead is toxic. It's not an unproven hypothesis.

> The part about this study that I personally find terrifying is the trajectory. A 50% increase in 8 years is astonishing.

I mean...maybe? The methodology is pretty uncalibrated, the demographics of the groups is completely unknown, and the ug/g estimates they're making don't pass a common sense test. Far more likely that you can't read anything into the time-series comparisons.

Still not terrified.


I agree my sibling comment by consteval . I am also not panicking.

> What, exactly, would you have the rest of us do, other than panic?

Push for better understanding and maybe regulations to help reduce the impact. Again, with getting fat I have agency over. It's on me to do it. With microplastics, government action is needed, so we need to be better informed and press government to act on our interest.


What if plastics make people fat


Yeah, you're doing what I just said: waving your hands and speculating that this finding is the secret reason for the other problems.


I didn't see any hand-waving? It was a legitimate question and one which you offered no evidence for/against. Certainly, we know little to nothing about the total range of side-effects from accumulated plastic. Could be negligible, could cause major issues that we just don't understand yet.


It's not my job to offer evidence against every hypothetical claim of harm. There are infinite of those, and one of me.

It is my job (all scientists' jobs) to call out panic based on "science". More generally, the people who want you to believe that X hurts you (for whatever value of X) need to bring solid evidence, not just unproven hypotheses.


If we don’t talk about the problem, maybe it will just go away.


>Terrifying study: “total plastics mass concentration in brains increased over 50% in the past 8 years

If as you claim the brain can clear out these particles, why is it terrifying? I have been asking for why microplastics are harmful and gotten a lot of great ideas but almost no studies or evidence. I guess we need to start researching the causal effects of MPs and not just how much MPs there are everywhere.


Elon Musk seems to think the whole microplastics worry is BS. What a joke he has become in just a few short years.


You mean the smartest guy ever ?


> The brain samples, all derived from the frontal cortex, revealed substantially higher concentrations than liver or kidney, at 3,057 μg/g in 2016 samples and 4,806 μg/g (0.48%, by weight) in 2024 samples, ranging as high as 8,861 μg/g.

Brains were 0.5% plastic by weight? The highest value was nearly 1% plastic.

That seems hard to believe.


That’s actually great news - neuroplasticity turns out to increase as we age.


Booo. Well done on the pun.


Angry upvote


Please don’t do this. Reddit exists, keep HN high quality less jokey. If there is humor it should be hacker culture, not low hanging.


This


Yup. They're extrapolating from uncalibrated GC/MS curves, and normalizing by mass of pre-processed sample. They also don't give any of the un-normalized data. I have zero faith in the accuracy of these numbers, but some faith in the inter-group comparisons.

The sensitivity of the GC/MS method makes me hypothesize that the stated values are massively inflated. Whatever error there was in that original measurement is probably amplified like crazy in scaling up to ug/g estimates.


That seems very unbelievable. A >1 inch ball of solid plastic in the brain? So essentially a solid plastic golf ball?

How is it even getting to the brain- isn’t there a blood brain barrier that even pathogens have a hard time getting through?


https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10141840/

> Micro- and Nanoplastics Breach the Blood–Brain Barrier (BBB): Biomolecular Corona’s Role Revealed

> The blood–brain barrier (BBB) is an important biological barrier that protects the brain from harmful substances. In our study we performed short term uptake studies in mice with orally administered polystyrene micro-/nanoparticles (9.55 µm, 1.14 µm, 0.293 µm). We show that nanometer sized particles—but not bigger particles—reach the brain within only 2 h after gavage. To understand the transport mechanism, we performed coarse-grained molecular dynamics simulations on the interaction of DOPC bilayers with a polystyrene nanoparticle in the presence and absence of various coronae. We found that the composition of the biomolecular corona surrounding the plastic particles was critical for passage through the BBB. Cholesterol molecules enhanced the uptake of these contaminants into the membrane of the BBB, whereas the protein model inhibited it.


So, in theory, a diet higher in protein and lower in cholesterol ought to be somewhat protective against nanoplastics crossing the blood brain barrier.


Except that most cholesterol is made in your body, and dietary sources don’t move that needle much.


What are you even talking about?


They found some brains have 1% of plastic in them by weight. 1% of the human brain by weight is 14g. A solid 14g plastic ball is 1.2 inches in diameter which is about the size of a golf ball.


Most plastic is like 1.5 grams/cm^3; that's like 9 cubic centimeters, or less than 1/4 the volume of a golf ball.

When you're saying "about" and then cubing the number you can have a pretty significant difference.


Average density of plastic is closer to 1.2g/cm3 which is what I was using.


You'd only be off by a factor of 3 instead of 4, then.

In any case, comparing it to a solid ball isn't so useful. Even the idea of "density" for something that is dispersed as small particles isn't too useful; proportion of mass is really the only useful metric.


This is not correct. A golf ball is closer to 1.7 inches in diameter, which is nearly three times the size of a 1.2 inch diameter ball in terms of volume.


[flagged]


You can’t be serious.


We’ve really screwed the pooch on this one. How many cancers, chronic diseases, birth defects, are a result of our mass pollution of this once pristine oasis of life, the only one we have?


If microplastics are directly causing illnesses and birth defects then we would've found out already. Past cases of mass illness caused by pollutants (lead gasoline, asbestos, minamata disease, thalidomide, chimney sweep's carcinoma, etc.) were uncovered quickly and usually addressed not long after. The fact we still can't pinpoint exactly how microplastics are harming us beyond that they are in places where they are not supposed to be, The one reassuring thing about this whole ordeal is plastics are largely inert, that's why they take forever to degrade.


I didn't go and look up the others but this argument by similarity, at least when applied to asbestos says the exact opposite to the claim you're trying to make. It's generally considered that industry/government was aware of the issues relating to asbestos in the '30s (and _started_ doing things about it then) but it wasn't until the 70's/80's (depending on the country) that its use was mostly stopped (and in places like Australia it wasn't outright banned until 2003).


And? That span is within an individual's lifetime, which is not very long in the context of human history. As of now there's zero sign any entity with regulatory power is doing anything about microplastics.

Also, why are you trying to deliver a point without looking up most of the examples I've listed? Do you expect that to be a convincing argument?


Each of us only gets one life. If most of that time is spent being unnecessarily exposed to pollutants with adverse health effects, then we have good reason to be outraged.

Consider also that some pollutants accumulate in the food chain, impacting future generations, for an indefinite time. Such as mercury in seafood.


Good news is tuna is not the only form of seafood you can eat! Perhaps you can try channeling that outrage into real tangible activism, any minute now.


You cannot be serious?

Do you think the problem will go away over time? Are you OK with having fewer things that you can eat without poisoning yourself? Do you realize we only have so many reservoirs from which calories can come from?

Take care where your rice is grown.


Why do you accuse me of being against addressing these issues? I am merely pointing out these are not existential crises because there is currently no evidence supporting such claims. It may change in the future, but until then I'm not jumping on this ship.

Ultraprocessed foods are already poison and most of us, probably including you, are consuming them regularly. Are you OK with that? And what is this talk about caloric reservoirs? Humans 8000 years ago had far fewer options and they still survived long enough to pass cultural lineages down to us. Most of your "caloric reservoirs" did not exist before the 20th century because the science and industry that created them did not exist.


Compared with the other examples you gave, I think one of the differences with micro- and nanoplastic and their growing bioaccumulation, is that if/when we discover that some level of concentration of it causes noticeable issues, it will be very hard to reverse, and it will be globally abundant (i.e. throughout the entire food chain). We'll be stuck with the problem for a very very long time.

It's not like we'll be able to just outlaw it and be done with the issue after a few years. So for this specific polluant, it feels right that we should be cautious and look for solutions as quickly as we can.


Humans 8000 years ago got their food from an environment that wasn't contaminated with ubiquitous, unnaturally occurring, forever chemicals.

Ultra processed foods are a problem and likely contributing to the plastic problem. I do what I can to reduce my reliance on both. Yet the solution won't be the few educated among us stopping ourselves. It must be regulated collectively or we'll remain in a prisoners dilemma as the pollutants accumulate.


> And? That span is within an individual's lifetime, which is not very long in the context of human history. As of now there's zero sign any entity with regulatory power is doing anything about microplastics.

Primarily, I _am_interested with health outcomes within my and my children's lifespan so that's the sort of time span I'm primarily concerned about. If the comparison to asbestos hold's true then we still have a _long_ time (long enough that any potential deleterious effects will be felt by all currently living and soon to be living members of my family) before any sort of regulatory action will be taken regardless of the health impacts.

> Also, why are you trying to deliver a point without looking up most of the examples I've listed? Do you expect that to be a convincing argument?

Because I'm _not_ your fact-checker. You're other examples may well follow a much quicker time-frame between discovery and strong regulatory action; I don't really care one way or the other, since at least one example shows a course of history which would play out poorly for those of us alive _now_ and exposed to increasing levels of environmental plastics.


Nature killed more people when the oasis was pristine. Life pre-plastic was shorter, more brutish and a lot less comfortable.


We can get rid of plastics without throwing out every medical and QoL invention...


This comment won't age well if we keep polluting the environment the way we are. Plastics will continue to grow as a problem if we keep using them at the scale we do.


The world retarded backwards socially in the last decade, standard of living declined, lowered testosterone levels, lower sperm counts, lower fertility rates, and perhaps lower IQ.

I suspected mass induced psychosis around Covid times. Now I suspect all the plastic people are consuming.


I’m wondering the same thing. What is the evidence they Microplastics are harmful?


> The extent to which microplastics cause harm or toxicity is unclear, although recent studies associated MNP [micro- and nanoplastic] presence in carotid atheromas with increased inflammation and risk of future adverse cardiovascular events²⁻³. In controlled exposure studies, MNPs clearly enhance or drive toxic outcomes⁴⁻⁶. The mantra of the field of toxicology – “dose makes the poison” (Paracelsus) – renders such discoveries as easily anticipated; what is not clearly understood is the internal dose in humans.


In plain English? And is correlation causation or no?


I'll take a stab at it, but I'm not a doctor or a biologist.

Cyanide will kill you. Almonds have trace amounts of cyanide. You can eat almonds till you get sick, but that tiny amount of cyanide won't kill you. The dose makes the poison. On the other hand, those fancy car-fentanyl, if a flake touches your skin, you'll od and die. It's super super toxic.

One flake of microplastics in your body isn't going to do anything.

Now,

> although recent studies associated MNP [micro- and nanoplastic] presence in carotid atheromas with increased inflammation and risk of future adverse cardiovascular events

It's not like every muscle fires on every heartbeat. They try, but some are old or dead. There are a lot of them, all working together. And they're constantly repairing or regrowing new muscle cells. How does the heart shed microplastic? Can it? How much till the immune system kicks in and starts causing inflammation? Inflammation is generally good, but super dangerous in the heart. Too much inflammation, and well, it stops firing correctly.

> what is not clearly understood is the internal dose in humans.

How much microplastic is too much? nobody knows. Seems like, you get too much, and repair systems start kicking in. The repair systems can't actually fix anything, but make you weak/sick, and you're generally worse off. When some other thing shocks the system, your body is already in panic mode, so the "normal" response of panicking doesn't change anything. Odds are, you just die.


Not that this was your point, but you can't absorb carfentanyl through your skin.


In plain English: There exists a dosage that causes problems, we don't know what it is. If this trend continues, we will most likely find out what it is the painful way.


While it's still debated, it seems likely that the BPAs in plastic will be classified as mildly carcinogenic at some point. It's probably not a big concern to be touching your phone case but maybe more so if it's millions of particles permanently inside you.


Maybe so, but think of the shareholders!!!


Blaming shareholders is an easy cop out, but most people’s appetite for cheap plastic things is insatiable.

It’s not like corporations are taking plastics out into the wilderness just for fun.


Indeed. Which is why we need collective action to overcome the power corporations have over an uneducated and apathetic population. A population they oversee through regulatory capture, advertising, curated studies, and (increasingly legalized) bribery of government officials.


Are the microplastics found in the environment coming from corporations production residues or from people’s consumption residues ?

I would say a relevant part of them comes from individuals. If you believe the issue is important enough, then raising awareness is the right direction so they take healthier choices. However most of the worlds population lives in developing countries, and microplastics are very low in their list of priorities, their top priority is actually making to the end of the month with enough food, shelter and some medical care or even education for them or their kids.

Blaming everything on greedy corporations is a very superficial analysis.


Individuals don’t make the plastic. It may come from post consumer waste, but it is manufactured by the corporations. Individual action is unlikely to make a dent in this issue.


Agreed though I see the current situation as just yet another result of the inherent flaws in human reasoning where some significant percentage of the population can't reason sufficiently well to make reasonably optimal choices (e.g., conservative science denialism).

This is why we, as a population, won't agree to curb CO2 sufficiently to address climate change but instead will simply adjust and, maybe eventually, accept geoengineering based approaches. That said, the next 10 years will be telling in how conservatives react to much higher home owner's insurance premiums...


Countries where micro plastics are more prevalent are ones where shareholders are less powerful (e.g. China).

https://www.newsweek.com/microplastic-map-reveals-countries-...

> When it comes to microplastic inhalation, Mongolia and China came in joint first place, with citizens of both countries inhaling more than 2.8 million microplastic particles a month. The United Kingdom came in third place, in joint place with Ireland, inhaling 791,500 particles per month. By comparison, the U.S. came in near the bottom of this list, in position 104 out of the 109 countries assessed, with only 10,500 microplastic particles inhaled per month.

Which country has the biggest stock market? US https://www.statista.com/statistics/710680/global-stock-mark...

Which country comes near last in inhalable microplastics: US

So you should be thanking shareholders if you live in the US (most are probably voters too!).


I think China is special case because they’re the world’s factory. They produce for several countries’ shareholders, including their own.


They're special case because they don't care about environmental protection unless there's a photo-op and headline that the government can use to look good.


Then what are you waiting for?

Ask your representatives today to ban all goods using China’s supply chain, and start producing all your country’s needs in your own soil.

Then measure the inhalable microplastics stats, that way we can know for sure if your country’s “environmental protection” is viable or just an excuse to offload dirty work to developing countries.


Shareholders have more power than the CCP in China?

Remember the US is second in manufacturing next to China.

https://www.brookings.edu/articles/global-manufacturing-scor....

Why isn’t the US as polluted then?


Very amusing that after decades of warnings about microplastics, there haven't been any studies to move beyond the point of 'maybe they cause issues'. We can all only assume that they do, of course, because any normal society not entirely captured by capital would allocate money to research this topic thoroughly. The fact that we haven't means that they know it causes issues but it would be costly to do cleanup.


People are researching it, there is funding for it [1]. It’s a challenging thing to research.

Is it microplastics or nanoplastics or both?

How many types of plastic are there, half a dozen? What type of plastic do you want to test, what about multiple plastics in different proportions?

It can be difficult to identify mechanisms behind adverse reactions to more obvious stressors, let alone something like this which appears more chronic, long-term, and insidious.

1. https://grants.nih.gov/grants/guide/notice-files/NOT-ES-23-0...


> How many types of plastic are there, half a dozen?

Several dozen major ones, starting at cellulose.

And before you think I'm missing the point: Well, no, cellulose didn't biodegrade for what IIRC several hundred million years. That's why there's no such coal.

It still barely biodegrades.


Not to mention, good luck finding adequate controls in humans.


You would have to do comparative and longitudinal studies. Or at least some kind of factor analysis.


Or there is no big enough sample size to compare against. How do you even establish a baseline without a control group?


Because there is no apparent acute symptom of microplastic contamination inside our bodies that have been identified yet. If microplastics have even a fraction of the harm of actual carcinogens like polycyclic aromatic hydrocarbons (which can lodge in DNA strands), we'd be witnessing mass illness events already.


That's too optimistic to be point of being naive, substances in general only cause damage above certain threshold, so there is high possibility that we are not seeing widespread harm because it hasn't reached that threshold on most people.


Plastic is chemically inert which should raise the threshold quite significantly. The question that needs to be answered is "What does/would acute plastic poisoning even look like?" I am by no means an expert, but I wouldn't be surprised if mechanically it could lead to increased clotting for the same reason sediment clogs pipes.

Even if it requires 'macroplastics' concentrations to cause problems, inert still doesn't mean harmless. One example which comes to mind is that senescent cells are 'inert' compared to cancer cells and they appear to be responsible for /have a role in aging's damage to tissues.


And? Where is the threshold? Science is not based on vibes. Starting a movement without evidence is called mass hysteria.


Science has pretty much determined the ill effects of global warming and we haven't stopped that despite the overwhelming evidence, why makes you think there would be a significant movement over this issue -that like you correctly point out its highly speculative-?


> we'd be witnessing mass illness events already

We ARE, it's just that nobody cares (or can figure out why)

50% of men will get cancer. Autoimmune diseases become more prolific over time. Fertility has been spiraling for decades. Mental health issues are on the rise.


haven't been any studies to move beyond the point of 'maybe they cause issues'.

People don't get any engagement and media sensationalism for finding no evidence. Now that society is biased towards that instead of truth, "maybe" is the best they can do.


Actually any society captured by capital would allocate exactly the amount of money that people have the interest to allocate to the topic of microplastics either via donations from regular citizens, Philanthropists or as part of the budget of research institutions and Universities. And it is probably the most capitalistic societies the ones that can raise the funds to finance this type of research. In this case, by the University of Nee Mexico in the US.


There are studies on microplastic toxicity already. These are linked directly in the OP article:

Even at low concentrations (1–30 µg/ml), photoaged microspheres at 1 and 5 µm in diameter exerted more pronounced biological responses in the A549 cells than was caused by pristine microspheres. High-content imaging analysis revealed S and G2 cell cycle accumulation and morphological changes, which were also more pronounced in A549 cells treated with photoaged microspheres, and further influenced by the size, dose, and time of exposures. Polystyrene microspheres reduced monolayer barrier integrity and slowed regrowth in a wound healing assay in a manner dependent on dose, photoaging, and size of the microsphere. UV-photoaging generally enhanced the toxicity of polystyrene microspheres in A549 cells

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10176241/

Maternal exposure to microplastics and nanoplastics has been shown to result in fetal growth restriction in mice. [...] Maternal exposure to both microplastics and nanoplastics resulted in evidence of placental dysfunction that was highly dependent on the particle size. The umbilical artery blood flow increased by 48% in the microplastic-exposed group and decreased by 25% in the nanoplastic-exposed group compared to controls (p < 0.05). The microplastic- and nanoplastic-exposed fetuses showed a significant decrease in the middle cerebral artery pulsatility index of 10% and 13%, respectively, compared to controls (p < 0.05), indicating vasodilation of the cerebral circulation, a fetal adaptation that is part of the brain sparing response to preserve oxygen delivery. Hemodynamic markers of placental dysfunction and fetal hypoxia were more pronounced in the group exposed to polystyrene nanoplastics, suggesting nanoplastic exposure during human pregnancy has the potential to disrupt fetal brain development, which in turn may cause suboptimal neurodevelopmental outcomes.

https://pubmed.ncbi.nlm.nih.gov/37724921/

PS-MPs can decrease transepithelial electrical resistance by depleting zonula occludens proteins. Indeed, decreased α1-antitrypsin levels in BEAS-2B cells suggest that exposure to PS-MPs increases the risk for chronic obstructive pulmonary disease, and high concentrations of PS-MPs can induce these adverse responses. While low PS-MP levels can only disrupt the protective pulmonary barrier, they may also increase the risk for lung disease. Collectively, our findings indicate that PS-MP inhalation may influence human respiratory health.

https://pubmed.ncbi.nlm.nih.gov/31727530/

(TL;DR; they are affecting our bodies for the worse, even as feti)


> The ubiquitous presence of plastics, especially polymer-derived particulates ranging from 500 micrometers in diameter down to 1 nanometer, defined as micro- and nanoplastics (MNP)

Aren't plastics by design long chains of molecules? 1 nm is like a handful of atoms at most afaik. How small do plastics get?


Yes, a carbon-carbon bond is around 0.1-0.2nm. At these scales, these "plastics" are closer to monomers than polymers.

A 10-carbon chain with its hydrogens attached can hardly be called "polyethylene"; it is a higher alkane and behaves more like wax or mineral oil than what most people would call a plastic:

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

I wonder if the PE they are finding is actually https://en.wikipedia.org/wiki/Petroleum_jelly


They can still be long chains - the quote mentions diameter, not length.


Ohh, that's a good point. I wonder how tightly they pack.


> Formalin-fixed tissue samples (approximately 500mg) were digested with 10% potassium hydroxide for 3d at 40°C with intermittent manual mixing to ensure even and thorough digestion.

"you think your job is bad, kaitlyn? get a load of what dr. campen's got me doing this week!"


Only the Polytron reduces an entire mouse to a soup-like homogenate in 30 seconds.

https://www.thomassci.com/Equipment/Homogenizers/_/Polytron-...


mmm, my favorite! but hold the potassium hydroxide this time, i'm going to need my esophagus later tonight. and go easy on the formalin


The scariest part for me is that there's essentially no escape from microplastics. If it turns out that they're greatly harmful, what can you really do?


I read somewhere one can donate blood plasma to reduce the levels in your blood (and give it to someone else who presumably has more immediate problems). This does nothing for the stuff in your organs not in blood but it’s something to be proactive.


They're obviously not, or we would've seen the effects by now (around a century of plastics in use.)

Remember when RF was the boogeyman? Paranoia about microwave ovens and cellphones causing cancer and other illnesses?


Yes but the amount of plastic in use has increased dramatically. Also there’s evidence that the process of recycling plastic is what creates a lot of the problematic microplastics. We only very recently started recycling plastic.


Go live somewhere in Northern Canada


The artic is already contaminated: https://www.nature.com/articles/s43017-022-00279-8

Even the Antarctica is starting to see microplastics: https://www.smithsonianmag.com/smart-news/in-a-first-micropl...


Yes, of course, the whole planet is polluted. But I read that 80% of microplastics pollution comes from tires. If you can get away from the cities, you can almost be free from the majority of pollution.


But I just bought a cybertruck for some reason?


what boggles the mind is that there doesn't seem to be any way to avoid absorbing this stuff. it's in the food, the air, the water. even if you try to filter the air or filter your water.. the filters are made from plastic!


We messed up.

Monkeys with hand Grenades. Humans with plastics.


tom lehrer seems appropriate right about now — https://www.youtube.com/watch?v=JPrAuF2f_oI


The paper shows 2024 brains are worse than 2016 brains. Why? It’s not that long, and it’s not like the decade prior to 2016 had less plastics.


Reasonably significant transition to PEX piping for domestic water supply starting in 2004 following a surge in copper pipe pricing.


Just guessing here, but I doubt PEX piping is a major contributor, seeing as it's solid plastic that doesn't shed and is rarely exposed to the elements. The most common sources of micro plastics appear to be things like synthetic fibers in clothing, particles coming off of car tires as they wear down, manufactured plastic particulate like micro-beads/glitter, and plastic objects in the ocean that break down into smaller and smaller pieces due to physical abrasion, sun, damage, etc.


This makes me happy I have copper plumbing with nice, healthy 1970s lead solder.


Make sure it's organic, grass fed, lead solder


Seems like a reasonable possibility considering the notable jump in PE in the kidneys.


Phew, glad I only drink water ampoules.


24 and 27 samples? Seems like a pretty good setup for sampling errors.


> total plastics mass concentration in brains increased over 50% in the past 8 years

I wonder if this correlates with the rise in the use of 'compostable' (i.e. weaker) plastics, that are more likely to break down during use.


>The mean (and standard deviation) age of 2016 decedents was 50.0 (±11.4) years and 52.3 (±16.8) years for the 2024 decedents.

27 organ material samples from 2016 and 24 samples from 2024 - but they don't say if they're from different people. I assume they are but it's not stated.

Just wondering how much the increased age would have contributed to differences between the two years.


These were from autopsies.

It was different people who died in different years.


I thought they were from dead bodies?


I'm curious how they get in there. In food, through the gut then to the blood, then the organs? Or do we breathe them?


This could be what caused the rise in Autism in Children. On the other hand, having grown up in a world where glass was used for everything. Cutting yourself on shard of glass from a glass bottle in the grass or alleyway was pretty common. Sometimes deadly when it cut a child's vain.


I thought it was difficult for many things to pass through the blood brain barrier. How are these particles making it through?



Is it just that any nanometer size particles make ot through, or is it just for select particles like plastic? Like if nanometer particles make it through, why do many drugs get blocked - are they just larger than a few nanometers (seems unlikely, but I don't know)?


My uninformed guess is the blood brain barrier is an evolved barrier that's very good at not letting things found in nature through, like various compounds, viruses, bacteria etc.

We have no evolved defence against compounds and materials developed in the last century.


Am I the only person that is skeptical about this papers findings? 0.5% just seems implausible to me. The study is preprint (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11100893/) and it states that "The present data are derived from novel analytical chemistry methods that have yet to be widely adopted and refined" - "pyrolysis gas chromatography-mass spectrometry".

This different paper talks about this approach and its limitations: https://www.mdpi.com/2673-8929/1/2/16

"Prior to Pyr-GC/MS analysis, environmental samples undergo purification steps to isolate MP from the environmental matrix. However, this purification is not complete, and several organic and mineral constituents survive these treatment steps, especially in complex matrices such as sediments or soils. Hurley et al. [15] reported that the efficiency of removing organic matter from soil varied from 34% to 108% depending on the used reagent (H2O2, Fenton’s reagent, NaOH, KOH). These remaining particles will hamper the characterization and quantification of MP particles through Pyr-GC/MS. Upon thermal cracking, the polymers release pyrolysis products of lower molecular weight. Some of these products are defined as indicator compounds when they allow the detection of targeted polymers. However, some constituents of the remaining natural organic matter may release the same pyrolysis products as the targeted polymers [15,16,17,18], hence a potential MP overestimation. The identification of pyrolysis products that are specific to the targeted polymers is therefore necessary."

Sounds like the detection methods and methodology for microplastics are evolving. It is plausible that the amounts are materially over estimated.

Another thing that seems implausible is the increase between 2016 and 2024? "our finding that total plastics mass concentration in brains increased over 50% in the past 8 years.". 50% in 8 years! Is the world really that different in terms of plastic exposure 2024 vs. 2016. Unless something has fundamentally changed with the food supply in this period how can this be possible? Plastic production is increasing (https://www.statista.com/statistics/282732/global-production...) but for a 50% increase in this period something would have to have fundamentally changed with exposure routes in this period.


The paper states the liver has 145 μg/g, about 30 times less than the brain but still a surprisingly high number. However, it is challenging to use that as a point of comparison. Would one expect the liver would have more than the brain because it is filtering blood, or less because it has mechanisms to prevent bioaccumulation ?


What is the evidence that Microplastics are harmful?


Doc here. It’s hard to prove.

You can’t do a double-blind randomized control trial.

And we have barely learned to measure these nanoplastics.

But there are starting to be strong correlations between the plastic occurrence and terrible diseases. Recent data on atherosclerosis + infarcts is horrible.

Recent data on testes production of sperm cells also looks very damning.

In summary, there are a few unexplained things in medicine that might very well be caused by plastics. Eg. More colon cancer in young people in the west. Eg. Declining sperm quality in the last 30 years in the west. Yes, it could be foods, but it doesn’t explain the whole picture. Plastics could be it.

My guess is that a LOT of nasty studies will come out in the next years.

I switched to glass and metal for all my food and water, for as much as I can control it.


Aren't microplastics a much bigger problem in Asia than in the West? I would guess that the negative effects of microplastics would show up in Asia first, rather than the West.


Depends. They are currently higher in Asia, but I would guess they were higher in the west before the last few decades.


We also don’t have a definitive cause of the obesity epidemic. It wouldn’t surprise me if it turns out to be caused by plastics exposure.


Another thing you can do to limit your exposure is to move far away from high-traffic roads. Tire dust is a major factor in exposure.


> You can’t do a double-blind randomized control trial.

You could on animals.


Yes, and I guarantee the first comment on that future HN article will be: "In mice" and dismiss the study.


There’s a review on this:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9885170/

> Endocrine toxicity induced by MPs is an emerging issue, despite the subject being rarely documented, there is growing evidence for ingested MPs bioaccumulation in mammalian tissues and organs with deleterious outcomes including endocrine abnormalities, reproductive toxicity, gut microbiota dysbiosis, and defective immunological responses in rodents, rats and mice.

And:

> However, there are still no conclusive research reports that have determined the direct consequences of MPs and NPs on the hypothalamus, pituitary, and adrenal gland.

However, “absence of evidence is not evidence of absence.” These microplastics are definitely on the more suspicious side, just like tobacco use was.


In an alternate universe the onus of safety would reside with those introducing copious quantities of something into human environments.

Unfortunately we do not live in that universe.


If we took that approach with everything nobody would be using cellphones.


And between the 1.6M distracted driving crashes each year, social media and educational impacts it would have been the right thing to do.

https://www.prnewswire.com/news-releases/national-safety-cou...


Nobody would be using cellphones now you mean. They would be evetually. The benefits of patience outweigh the costs.


Sounds good to me!


Yeah, safety takes decades to study conclusively, it’s simply antithetical to fast-paced industrial world.

Sometimes I read accounts on industrial revolution England and think “how the heck people survive THAT.” Several decades from now there will be people who think of us the same way haha.


From TFA

The extent to which microplastics cause harm or toxicity is unclear, although recent studies associated MNP presence in carotid atheromas with increased inflammation and risk of future adverse cardiovascular events2,3. In controlled exposure studies, MNPs clearly enhance or drive toxic outcomes4–6. The mantra of the field of toxicology – “dose makes the poison” (Paracelsus) – renders such discoveries as easily anticipated; what is not clearly understood is the internal dose in humans.


So… we don’t know. Please take back your profanity and your downvote.

An association means little considering Microplastics are more commonly found in garbage ultraprocessed food.

And the second part of your quote is saying we can make anything toxic in a controlled exposure if we dose it high enough


This is why the term ”common sense” is a good term


"Common sense" is basically the opposite of science.


I like science, but that doesn't mean it has to be the end-all-be-all. Otherwise it would be a religion.

There are situations where overthinking it is bad. Yes, obviously, microplastics in your brain are bad for you. Common sense. Any delay because "the science isn't there yet" does more harm than good.


This is a preprint. It has not yet been peer reviewed by a journal.




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