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.
[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."
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...
I couldn't begin to tell you [1]. 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.
[1] Actually...I just asked Gemini and it reminded me that the expected variance of a draw from a distribution, scaled by factor C, should have a variance of the scaled sample distribution that grows with C^2. So, if we scale up the measurement by a factor of 10,000, we'd expect the variance of the scaled estimate to be proportional to 10,000^2.
I may be misunderstanding you, but it sounds like you're claiming that they had e.g. 10 tiny samples of tissue, that their measurements had an average 25% variation across those 10 samples, and that therefore the whole brain estimate (mass 10,000x that of a single sample) therefore has a much greater uncertainty. But doesn't the standard error of the mean get reduced by the square root of the number of samples? i.e. if you had 10 samples with 25% variation across samples, and you're taking their mean, the error of that mean should be 25% / sqrt(10) = 8%. And that should be the relative error for the scaled up whole-brain microplastic concentration as well. Or is there some other source of variation that I'm missing?
You're talking about reduction in statistical variance due to replication of measurement (and then averaging). I'm talking about what happens when they extrapolate from that value by a huge factor (which is what they've done, and the silly article does egregiously).
The paper isn't clear what they mean when they said "~25% within-sample coefficient of variation", so I can't directly address what you're asking, but it's tangential to the point I'm making. My naïve interpretation is that they did an ANOVA, and reported the within-group variance, or something similar.
All I'm saying in my footnote is that, whatever the final point estimate, scaling it by a factor of C will affect the variance of the final sample distribution by C^2. So for example, if you have an 8% variance on the measurement at ug/g, and you scale it by 1300 (for 1300g; what the interwebs tells me is the mass of a standard human brain), then you'd expect the variance of the scaled measurement to be 1300^2 * 8%.
That makes a ton of assumptions that probably don't hold in practice -- and I expect the real error to be larger -- but illustrates the point.
...so you are saying that the probability distribution indicates that there is a 50% probability that there more than a spoon's worth of plastic in our brain?
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.
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
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.
Los Angeles is one of few US cities that is managing to build at least some new transit lines. Increasing density in desirable cities is actually pretty easy, all you have to is make it legal (by-right zoning) and then the market will do the immensely productive and profitable thing.
I find it interesting that at a certain time in Los Angeles, a segment of society could afford a craftsman cottage house, but not afford an automobile. This was the prime era of the Pacific Electric streetcar suburb, say around 1890-1920. Today, obviously, anyone who can afford a house anywhere in the country can afford an automobile.
The end of the Pacific Electric system was not a conspiracy theory by tire companies or anything like that; the price of the cars dropped and that's what consumers preferred, i.m.o.
From an infrastructure perspective building out instead of up is incredibly expensive. Not just transport but also water, sewage, electricity and internet.
Yeah, I’d expect EVs to get lighter over time as technology progresses. Car bloat is a much bigger problem. Totally insane that little practical city cars like the Honda Fit have gone practically extinct in the US in favor of bigger, heavier cars that don’t even necessarily bring improved cargo capacity for all that extra bulk.
I have a 2018 Fit and it's a fantastic car. It gets 36 MPG and has much more interior space than it would seem. I've had taller people ride in it comfortably and its crowning achievement was fitting a hot water heater in the cargo area with the rear seat split -- without having to remove the child car seat on the other side. Pair a roof rack and you really don't need more -- especially day-to-day.
It's a crying shame that they've stopped selling them in the US. Marketing (the real men need their Rams, thank you very much!) and the CAFE loophole seem to have won the day, though, and we're all worse off for it.
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.
The solution to tragedies of the commons is to internalize externalities. Tax should scale with carbon use, congestion contribution, and microplastic emission.
> 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.
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.
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.
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.
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.
This Engineering Explained video seems pretty thorough. The short of it is that your intuition is in the right direction, its definitely not to the fourth power of weight. Vehicle weight does contribute to wear but according to Continental its less important than driving style and road curviness.
Most studies I've seen on this topic agree that the amount of pollution created is not linear, and this also makes intuitive sense. The heavier your vehicle, the wider and/or larger diameter your tires need to be to give it the required amount of grip. If those bigger tires wear out in the same time as your smaller vehicle tires, you've already created considerably more pollution.
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.
Also motorcycles/scooters. Unless you have children or live in a place with serious snow a motorcycle and a car sharing app/rentals for when you need to haul a sofa or something is a great combo.
Cheap, easy maintenance, good fuel economy and speed, traffic jam immunity..
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 reactionary billionaires have hijacked most of our mass media as we blow by the 1.5°C Paris agreement and Trump dismantles our science institutions.
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.
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?
> These particles can include synthetic rubber, plastics, carbon black, and trace metals (like zinc)
you're correct. I mistakenly thought it was only carbon coming off the tires. So yeah, EVs have a significantly lower carbon output that ICE vehicles. My point still stands but thanks for the callout.
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.
These zones are generally densely populated areas, and in Europe they usually have low speed limits, and roads design to encourage driving at low speeds.
To think that the minuscule difference in tire dust is significant at all, compared to the pollutants that EVs completely eliminates, is absolutely ridiculous.
The devil is in the details, yes. Have you considered that the policy makers have actually looked into the details? Have you looked into the details? Have you read any detailed reports about tire wear or did you just make up a problem based on your own intuition? Because I’ve seen reports from EV fleet operators that indicate that they see no difference in tire wear. Most likely the added weight (which isn’t all that much for modern, smaller EVs.. you know, the ones that people actually drive in urban/suburban areas in Europe) as a factor is drowned by other larger factors.
And we’re not that far away from EVs with the same or lower weight than their ICE counterparts, so getting these kinds of policies in place has some forward-looking aspects to them as well.
Excessive NO2 emissions spewed by diesel engines not meeting regulations very literally removed years from our collective life spans in city centres across the world.
Despite their own health hazards no amount of tire particulate from EV's can achieve that level of widespread public health impact.
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.
You can probably reduce microplastic consumption, but it is quite a pain and more expensive. Try buying everything at the store not wrapped/bottled in plastic. This does not even work as well as you might think as many things are wrapped in plastic and then presented as if they were not. For example, breakfast sausages in the meat display at my local Whole Foods are wrapped in paper when they give it to you, but come to the store in ~1lb plastic wrapped packages.
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.
Do you consume drinks? Meat? Produce? All these things are chock full of their own micro plastics. It's unavoidable. We can probably reduce contamination but our children's children's children won't be free of it, not until organisms evolve to efficiently eat it. Then we'll have whole other sets of problems.
Do I consume drinks? No, except water and instant coffee, no soda, no beer. Meat? Yes in small quantities and much of it comes from the local environment. I grow most of my own produce, with RO water.
Yes they are unavoidable, just the plastic containers etc probably give some and I do eat candies and imported bananas and bread etc. But pretty sure I get a lot lower dose than most people.
However I'm not sure it matters that much until a mechanism of actual damage is established.
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")
> you don't need to haul a weeks worth of groceries but can get fresh food every single day
I lived that life in my 20s
Turns out I don't actually want to go to the grocery store every day. I want to go once a week and stock up, which I can do thanks to inventions like the refrigerator and the automobile
no judgment on you in particular, but i’m not a fan of this thought process. I believe it’s a major cause for why americans (statistically) are so obese. and i say this as an american that lives in a city but has family in the suburbs.
running errands with your own two feet every day by walking, cycling, etc keeps people healthy and lean. this country has a major car problem. it’s sad.
of course one can go to the gym to stay lean and healthy, but that’s even more time consuming than stopping by the store for 5 minutes on the way home, and it requires extreme motivation. Hardly an improvement i’d say.
I don't believe it. If you lived right next door to the grocery shop would you still only go once a week and stock up?
Nobody wants less flexibility, rigid plans and higher maintenance costs. I think what you really want is a big house with lots of space away from other people and since you can't have your cake and eat it too you've sacrificed everything else.
Well good news, nothing is stoping you from bringing home a full cartful of groceries that walking distance either. You just have more options.
Now, if you are really attached to your car and are only open to using your car for groceries, stay in suburbia, it's oversupplied through centralized planning and not at risk of going anywhere!
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.
You can have really very good quality of life in remote areas. You just might die before you get help if you have a heart attack or something. But the rest of the time it's great!
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?
An EV is objectively not worse for the environment. And virtually all vehicles contain large amounts of plastic (eg PVC). I recently heard model year 2024 vehicles are ~30% plastic by weight.
I’d wait until somebody can clearly state what the demonstrated harms of microplastics are before you conclude that there’s nothing you can do. An EV reduces emissions that we KNOW are bad, and over their lifetimes, the reduction is huge compared to an ICE vehicle. If you’re worried, though, walk or bike whenever you can.
Biking to grocery store is not an option for you, but you can still make a difference if you think about it. Eg, go to the store less frequently. Switch to a chest freezer for perishables. And so on. Draw up an energy budget and do the math.
There is a cost to human life, sure. But you can make it work if you really care enough. You are definitely not screwed.
"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.
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)
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.
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.
I mean, what are we really going to do about it? So much chaos in the world, I don't think many are focusing on keeping plastics out of our body. No one's championing it.
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.
Like the ship-produced aerosols that seeded clouds, increased albedo, and cooled the planet, in what James Hansen has called a "Faustian bargain". We successfully stopped that with regulations.
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.
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.
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.
That may be true, but you don’t have to rely on biking for “everything.” Some biking is better than no biking.
I live in a small college town a couple of miles from the college. I walk, run, or bike to work nearly every day. But I am not a purist about it. We have a snowstorm forecast for tomorrow so I am going to drive (my EV). Would it be better for the environment if I walked? Probably? Does one trip really make that much of a difference though? Probably not.
I think there are likely many many places where people can walk or bike to some of the things if not all of the things. People really should do that more (not the least reason because biking is wonderful). Biking to the grocery store is mostly impractical for me as it is many miles away. But that’s ok! I am doing other things.
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.
I live "in" a major American city. Well, a reasonably major Midwestern city. It's roughly a third the size of Rhode Island. It has half a million people in it.
Unfortunately a bicyclist on the road will be exposed to far more tire microplastics than drivers in their enclosed cabins with filtered and recirculated air.
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.
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).
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]
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.
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.
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).
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…
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.
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.
Cool, what was I gonna do with it? Unless we're selling to Dracula, owning external blood is highly regulated. So anyone buying has some credentials to use it.
>>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.
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.
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?
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...
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.
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?
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!”
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."