Short answer, easy. The only thing wood won’t do, that plastic will, is flex. Everything else is not a problem.
But when They say “hand wash only”, They really mean it. See Death by Dishwasher below. Also search “sanitary” (below), if that’s your hangup with wood.
Continue reading Post #2007: How hard is it to switch to wood cutting boards?
This post is briefly explains why I’m tossing out my worn plastic cutting boards and mats, and rehabbing a few wooden cutting boards to take their place.
This, based on two absolutely ridiculous research findings regarding the amount of microplastic in the diet, as measured in credit cards per year.
This will all make sense by the time I’m done.
A few weeks back, you may have read that the average American eats a credit-card’s-worth of micro-plastic a week, on average. The obvious click-bait potential for such a bizarre and gross assertion meant that it got lots of attention on the internet. (The research has been around for a while, but for some reason, there was a recent resurgence of reporting on it.)
I’m not giving a reference for that, because, as discussed below, that’s total 💩.
But, because normal isn’t newsworthy, you’d be hard-pressed to find any internet mentions of the the debunking of that credit-card-a-week. Other scientists have taken the same (~) underlying data and calculated a weight of microplastic in the diet of around one-millionth of a credit-card a week. Just under five millionths-of-a-gram per week, not five grams per week.
(How? To be as charitable as I can, it turns out to be difficult to take counts of a few dozens of microscopic plastic fragments, in a few samples of food, and extrapolate those data to come up with the total weight of microplastic in the diet. As I read the scientific debate, the authors of the various “credit-card” studies simply made an exceptionally poor choice of extrapolation method.)
Now, you personally may have thought that that “credit-card-per-week” figure was implausible. And yet, because “microplastic in the diet” is such a squishy entity (starting with, invisible), you really had no way to prove that your instincts were correct.
Now, thankfully, somebody has jumped the shark. There’s a new study claiming that, in addition to plastic in the food chain, the use of plastic cutting boards adds a further ten credit-cards a year of plastic to the diet.(?)(!).
FWIW, this is the cutting board analysis refernce The piece that points out the problems with the 52-credit-cards-a-year analysis is this reference.
💩 ? Yep. Same reason as the credit-card-a-week study. See above.
But its useful in the following ways.
First, this most recent “credit-card-consumption” study is self-debunking for the average user. Because, while I’m not exactly sure what “microplastic in the diet” looks like, I for sure know what a plastic cutting board is.
Do the math, and at 5 grams per credit card, ten is just shy of two ounces a year. This research is claiming that the average person’s plastic cutting boards erode from knife cuts at the rate of (~) two ounces/year/household member.
Really? For your consideration, I offer Orange Cutting Mat (below), weighing in at a svelte 1.1 ounces:
If the erosion rate really were two ounces a year, the mat above would have been worn to shreds a decade or two ago. It’s old. Origins are lost in the mists of history. It’s used more-or-less daily. It’s obviously scratched from use.
And yet this venerable cutting mat continues to serve.
Worse — and for shame — the authors of this 10-credit-cards-a-year study could have convincingly debunked their own finding with a day of work and a kitchen scale. Weigh a cutting mat (per above, 32 grams). Chop vegetables on that mat for five hours (300 minutes) to simulate 30 days of typical household chopping. If the estimated two-ounces-per-year is correct, you’ll have lost about one credit-card’s-worth of plastic, or about 5 grams. At the end of the day, if the erosion rate was as-stated, that plastic mat ought to weigh just 28 grams. That amount of plastic weight loss should be easily detectable on a gram kitchen scale.
In other words, you can literally check their work by subtraction. With a kitchen scale. And a month’s worth of vegetable. And some manual labor. Just weigh the cutting mat pre- and post- a marathon cutting session.
But as importantly, this study makes you realize that, yep, some of the plastic from those scratches is exiting as tiny fragments. And you’re eating those tiny plastic fragments. Some of them, anyway. There’s no reason to think that the authors did their lab work incorrectly.
And, if you follow the thread here, because 10/52 =~ 20% based on the well-known Universal Law of Credit Card Accounting, using plastic cutting boards ups your dietary consumption of microplastic by 20%. Or so. Under the assumption that both studies embody the same degree of (gross) overstatement of the actual weight of plastic.
I don’t know whether the actual amount of microplastic in the diet causes significant harm or not.
On the one hand, humans have been using copious amounts of plastic for decades. If there is some health hazard from microlastic in the diet, chances are good that it has already occurred. I suspect we’re hearing a lot about microplastic due to some change in technology that makes it easier and cheaper to detect.
(Take that cynicism with a grain of salt, as my entire house is carpeted in cut-pile polyester wall-to-wall (Post #1943, carpet fiber burn test). And, accordingly, I must surely live in veritable airborne-microplastic-polyester-fiber-fragment miasma.)
On the other hand, you at least have to recall the mechanism of action of asbestos for lung cancer. My recollection is that it was a micro-fiber disruption argument, The fiber in question, thought to spur generation of lung cancer, was an eensy asbestos fiber fragment that got inside the lung cell. And proceeded to screw up the works just enough, when that cell next divided. That’s how I recall the theory of it.
So, durable microscopic fibers (or other plastic bits) can’t be readily dismissed. Plausibly, it only takes a tiny amount of that stuff to cause whatever havoc it’s going to cause.
The upshot is that while the jury’s out on the dangers of microplastic in the diet, there’s no sense in force-feeding yourself with it.
Not when you can easily cut your food up on something else.
As final insult to injury, I note two things.
First, as I read it, based on the underlying data used, that 10-credit-cards-a-year from use of plastic cutting boards would be in addition to the estimated 52 credit-cards’-worth already supposedly in the diet. So the purported total now stands at 62 credit-cards a year, for those who both eat food and use plastic cutting boards.
Second, I infer from this glimpse of the literature that there’s a whole slew of scientific papers in the pipeline that use minor variants on this same (bad) extrapolation methodology. So, changes are, there’s now going to be a string of articles showing the mind-boggling amounts of microplastic you eat due to fill-in-the-blank. These will, of course, be rapidly popularized on the internet, because they put the “ick” in clickbait. Literal accuracy is not required, only some plausible (i.e., science journal) source.
Let me give you the argument, to see if you buy it. (Read Post #1941 and Post #1942 to see where I’m coming from on this issue.)
1: We’ve been using plastic, including artificial fibers, in the U.S., for a long time. 2: Therefore, best guess, whatever microplastic does to humans, it has already done that to us. Plus, 3: personally, as it turns out, I live in a microplastic-fiber-rich environment. I think.
Regarding that last point: The wall-to-wall carpet that came with my house is polyester fiber. Not only do I walk around on the cut-off ends of pieces of artificial-fiber yarn whenever I change locations within my home, the fiber is polyester, which typically gets fingered as potentially harmful microplastic.
My guess is that this surely (surely!) generates a microplastic-fiber-fragment-rich living environment. (But to be clear, there’s only a bit of research to support that, as outlined in this reference.) And there are a lot of people in the same boat. A lot of folks who spend a lot of hours in places with synthetic-fiber wall-to-wall carpet.
The upshot is that if microplastic from polyester fibers is a major health hazard, even if that only shows up late in life via a cancer effect, you’d think we’d have noticed it by now. We’ve had a lot of time and variation in chronic exposure to do so.
Restated: If there were significant human health effects from typical exposures to microplastic, you’d think we’d have noticed by now.
But how, from this viewpoint, can you explain why we are suddenly seeing and hearing so much about microplastic? How do you explain that, if it has, as you say, been there all along?
My guess? I guess that we’re now seeing it because we’re now looking for it.
One guess for the uptick is a change in or diffusion of microplastic-detection technology. The best studies seem to use some fairly exotic equipment, something I take to be a microscopic infrared spectrometer. Maybe those have gotten cheaper, or maybe it’s just the case that more people have access to the required equipment. Alternatively, other studies appear to use minimal equipment, but may require significant time. The publishable standard of measurement is so low (particles per liter) that maybe a lab with the right filter paper (and a microscope and some lab assistants) can quantify microplastic-in-blank to a publishable degree.
(I think that this last point, more than anything else, explains the view that microplastic is an inexhaustible source of clickbait, via finding microplastic in any (e.g.) bodily fluid or organ that you care to examine closely enough.)
A second guess for the uptick is that we now bother to look for microplastics, in both the human and natural environments.
One the one hand, maybe we look more often because “microplastic” is clickbait-du-jour. An internet-fed fad. A response to economic rewards for attracting eyes to your article. After all, every N days, somebody finds microplastic in some new (and yuck-inducing) substance and/or bodily fluid and/or internal organ. And that makes great clickbait. Particularly for the closet doomscrollers.
On the other hand, microplastic is part of a legitimate concern about plastic in the environment, overall. I mean, how many times have we heard this story, only to find out it has an unhappy ending:
There's this stuff? We use a lot of it. But it doesn't decompose well. So, where does it end up?
But in any case, I’m betting that any human health impacts of microplastic are pretty subtle. Not that I’ve done any research on that, but just from a feeling that we’ve been living with plastic for so long, I think we’d have seen something by now.
OTOH, I live in a house with polyester wall-to-wall. So take this FWIW.
Most internet sources assure me that only four fibers are likely to be found in the pile of modern wall-to-wall carpet. A handful of sources add a fifth (acrylic). Perusal of current offerings at Home Depot adds a sixth (triexta).
I think I can plausibly narrow it down to three, in my case, by eliminating these:
Triexta appears to be new enough that it’s not going to be the fiber in my 20-year-old wall-to-wall carpet.
Acrylic appears rare enough, in wall-to-wall carpeting, that I can’t actually find any roll-type carpet made with acrylic fiber currently offered for sale.
Polyolefin fibers appear to be used only in the cheapest carpet materials. At Home Depot, that’s what their self-stick carpet tiles are made of. That’s not going to be the basis for my well-wearing 20-year-old wall-to-wall.
N.B. 1: SD means solution dyed, that is, that is, the plastic itself is dyed before the fibers are spun from it. As opposed to dying the fibers after-the-fact. This apparently is by far the preferred method for durability in modern carpeting.
N.B. 2: Olefin (a.k.a. polyolefin) is a polymer (long molecule made from simple building blocks) where the basic building blocks are straight-chain alkanes (carbon and hydrogen and nothing else). If you make it out of propane feedstock, you get polypropylene. If you make it out of ethane feedstock, you get polyethylene. I assume they use polyolefin when they make the fiber out of whatever’s handy, or from a mix of feedstocks.
The most commonly-suggested way to tell what a carpet is made of is to burn (a bit of) it. Condensing the guidance from this site:
Wool barely burns, extinguishes itself, leaves ash, and smells like burning hair.
Nylon burns well, with a smokeless blue flame, leaves a gray/black blob of melted plastic. And stinks. (I’ve sealed the ends of enough nylon rope to know that. It’s your classic burning plastic smell, but does not stink quite so badly as the smell of burning electronics, which is typically the smell of burning PVC (plastic wire insulation).
Polyester burns well, with a smoky orange flame, sputters and drips as it burns, leaves a shiny plastic bead, and smells “sweet” as it burns. (Really?)
Pretty sure this carpet isn’t wool. So it boils down to burning a bit of it, and seeing if it stinks. If so, it’s nylon. If not, polyester.
What I didn’t realize is that you need a pretty good chunk of fibers to be able to do this test. First time I tried it, I had a fluffy bit of fibers, and they simply shrank away from the flame. Second time I got an entire piece of yarn, twisted it tightly, and got it to burn.
Results: Sputtering flame, no ash, and no stink. I’m pretty sure my carpet is polyester. I could refresh my memory with a bit of nylon cord, or burn a bit of known polyester fabric, but I think this all makes sense. Plus, burning nylon really stinks. Like “don’t do that inside” stinks. And while this did not smell “sweet”, this basically didn’t smell like much at all. Which pretty much rules out nylon.
I may try some different test, if I can find one.
But odds are, given that this is 20-year-old decent-grade grade wall-to-wall carpet, with some worn spots, clearly made of synthetic, and the fiber burns without a stink, this is polyester.
The entire floor of my house is covered with the cut ends of polyester yarn. And has been for the past 16 years or so.
All this time, not only did this not bother me, heck, it was downright comfy to walk on.
But now that my eyes have been opened, I see this as a comfy source of microplastic polyester fibers.
Should I care about that, or not? Or do anything differently, now that I know?
Time to let this percolate a bit more.
In my last post, I pinned down what I did and didn’t know about microplastic. And, while I don’t (yet) think this spells the end of civilization, what I learned has given me pause.
With the just-prior post as background, I spend this post homing in on the questions that I should be asking.
They are:
1) What are my likely sources of greatest exposure?
2) How does this stuff break down? What is the half-life of microplastic, particularly fibers, in various environments (including human tissue).
2B) Are we seeing this topic frequently in the popular press because microplastic has been building up in the environment (that is, it’s now a much greater hazard than in the immediate past), or because we’re looking for it and/or we now have the means to find it?
3) Are nano-scale (really tiny) fibers a particular concern?
I’m only going to address the first question, in this post.
Understand my background as a health economist. Surgeons have been implanting chunks of plastic and metal into people for more than 70 years. (The first pacemaker implant took place in the late 1950s. Modern metal-and-plastic hip replacements go back somewhat further.) So the right materials, properly chosen, won’t interact with the body at all. OTOH, there’s a long list of materials that were tried and rejected, because they were not so inert.
So my prejudice is that incorporating random bits of plastic into your body is probably a bad idea. The only question is, how bad is it? And can you avoid it?
The first question to ask for any environmental health hazard is, 1) What are my likely sources of greatest exposure?
For airborne fibers, if I walk through it logically, my greatest source of exposure almost certainly has to be the wall-to-wall carpeting in my home. It’s indoors, it contains a huge amount of fiber, it’s clearly synthetic fiber, and it is constantly being abraded by walking on it. And it’s “clipped”, that is, every strand of carpet yarn has been sheared off, so that it’s an entire floor surface consisting of the cut ends of synthetic yarn. In my house, every floor surface save bathroom, kitchen, and foyer is covered in the stuff.
For me, it’s a big, fiber-generating surface that I shuffle my feet across, every time I change locations within my house.
Reading up on it, I’m guessing it has maybe 60 ounces of carpet pile per square yard, a.k.a., “face weight” 60 carpeting. Doing the math, that means my house contains somewhere around 700 pounds of carpet fibers. In the form of short pieces of yarn, with their cut ends exposed, for me to walk on. I’m pretty sure that outweighs all other cloth in this household, by a wide margin. True, on any given day, most of it just sits there. But so does most of the clothing in my closet.
I can only think of two things arguing against this being my greatest source of airborne synthetic fiber exposure.
The first is that, whatever it’s made of (I have no clue), it’s made to resist abrasion. It was here when we moved into this house in 2007, and it looks about the same now as it did then. (To within my ability to tell. What I mean is, no obvious new wear spots have developed in the past 15 years.)
The second is a potential “inverse-square-law” for inhaled fiber concentrations. That is, for a given rate of fiber shedding, the closer you are to the source of the airborne fibers, the more of them you may be likely to inhale. If that’s true, then the fibers shed from stuff that’s right under your nose — shirts, sweaters, scarves, coats — might matter more than the fibers shed at your feet.
And if I put all that together, I come up with the obvious conclusion that crawling around on wall-to-wall carpet may not be smart. Not that I’m planning to do that any time soon, if I have any say in it. But the point being that having infants crawl around on your wall-to-wall carpeting might require a rethink. Putting that differently, if you’re not worried about your kids crawling around on wall-to-wall carpet, I don’t see much point in being worried about this topic at all. Because, outside of a factory, it’s hard for me to imagine where you could get a higher concentration of inhaled artificial fibers than in crawling across modern wall-to-wall carpeting.
We have met the enemy, and he is us.
In my case, I’m going to start by trying to figure out what my carpet is made of. It was here when we moved in, and I have no clue what the fiber is. Nylon is a good guess, and everything I read says that nylon, in particular, is a fiber that you’d like to avoid breathing in, owing to what it produces as it slowly breaks down.
And I may be a little more diligent in vacuuming. Given that the vacuum (in theory) has a HEPA-level filter on it, that (in theory) couldn’t hurt.
From the prior post, it was absolutely clear that routinely inhaling a lot of nylon fiber is bad for you. There’s even a name for the resulting condition — flock worker’s lung.
But so what? Inhaling high levels of almost any fiber or powder is bad for you, be it coal dust, silicon dust, cotton dust, copier toner, wood dust, or what have you.
It’s still an open question as to whether or not there are identifiable health effects from absorption of microplastic at levels commonly found in the environment.
But, from my own perspective, given how picky medical device manufacturers are about the materials they will use for implantable medical devices, it’s a pretty good bet that inhaling and ingesting random plastic bits and fibers is probably not good for you. How bad, exactly, we can argue about. But almost surely not a good thing.
My first thought, in a situation like this, is to test for it. Measure it. See what my exposure is.
But I don’t think that’s possible, practically speaking. I already have a “PM 2.5” meter, bought in response to the Canadian forest fires of 2023. That almost uniformly shows lower airborne particulate levels inside my house than outside. And that responds to all kinds of particulates, of which the tiny minority is likely to be microplastic fibers.
So this is a case of flying blind. I can’t tell how much I’m exposed to and I have no clear idea what harm that exposure might do, anyway.
In that case, I can at least try to identify the easily-avoidable sources of microplastic, and so reduce my exposure until better information develops. I might even go so far as to change what I buy, to avoid funding the production of even more items that shed microplastic. (E.g., avoid synthetics in my next batch of shirts). But I’d want to look at the full implications of that first.
So I’m stuck at the “identify my exposures” stage. My water filter appears to take care of most of the microplastic that might make it into my tap water. (Though I have no idea what it does with the very smallest particles). And for airborne fiber, my biggest exposure has to be wall-to-wall carpet. But this house was built for it, and replacing the existing wall-to-wall with hard-surface flooring would be ludicrously expensive.
Time to step back and let this percolate a bit.
Seems like every week I read another story about microplastics.
At some point in all that reading, it dawned on me that I didn’t actually know what microplastic is. Sure, micro meaning small, and plastic, meaning plastic. But that’s as deep as my understanding went.
Turns out, there are good reasons for my confusion. The term “microplastic” is used for everything from shreds of plastic you can see, down to nano-scale bits that you’d need an electron microscope to see. From the plastic chips left over from recycling, down to aerosol-sized microscopic fibers. The microplastic in your tap water (fibers, mostly polyester) really isn’t the same stuff as the microplastic in your bottled water (particles, mostly bits of PETE or HDPE plastic).
Let me narrow down my interest to microplastic in my tap water. Or maybe, microplastic in the air I breathe.
What’s that all about? What is it, exactly? How much is there? Will my water filter remove it? How about an air filter? Is it harmful in the concentrations I’m routinely exposed to?
Weirdly, for something that seems to be in the news a lot, I could not find out much in the way of hard facts. In this post, I at least begin to pin down why I’m not finding answers to those basic questions.
Other than the fact that my Brita water filter promises to remove most of it. Whatever it is. I think.
Source: Brita.com, data for the “elite” filter, not their standard filter.
The popular press on this issue yields a coherent if superficial story about the environmental danger of microplastic.
It’s invisible. Municipal tap water, for example, typically contains bits of plastic that are too small to be seen with the naked eye. It is not present in enough density to give the water a cloudy or turbid appearance. Nor does it affect the smell or taste of the water.
It’s everywhere. These bits are too small to be filtered out completely by typical municipal water plants. And once you start looking for it, you can find some amount of microplastic almost everywhere. Not just tap water, but: Bottled water. Bottled soda. Even in things that are bottled in glass bottles. Animal tissue. Breast milk. Rivers. The oceans. Fish. The soil. The air. The clouds.
(Ah, yeah, in addition to eating and drinking it, you breathe it in the form of floating dust particles.)
It might be bad for you. I haven’t yet come across hard evidence one way or the other, at levels seen by the average U.S. resident, but the most common analogy is with asbestos. Exposure to asbestos fibers is associated with cancer presumably because the fibers were small enough to enter cells and perturb DNA replication. A lot of microplastic is in the form of fibers, some of which are likely small enough to enter cells. So this is a plausible if unproven concern.
And that combination makes it hard to sort fact from fiction. Look at the phrases in red above. In the internet-driven world, you know what means. It means that “microplastic” is an ideal and practically inexhaustible source of click-bait. Between the people who make their living out of scaring you, and the people make their living out of mindlessly repeating stuff they gathered off the internet, let’s just say that the facts appear thin on the ground.
On top of which, everybody hates on plastic. Even as we, collectively, use vast amounts of it. So you’ve got some degree of axe-grinding dressed as fact-finding, thrown into the mix.
To be clear, I’m not dismissing this as a threat. This, even though our public health authorities don’t seem to have any handle on it. But that has happened before (think, leaded gasoline). Sometimes widespread harm is only understood well after-the-fact.
Three things make me hesitate before I freak out over microplastic.
Thing 1: It’s not as if plastic is a new thing. We’ve been using lots of plastic, for a long time, here in the U.S., and world-wide. Whatever-it-is that microplastic does to you, chances are that it’s been doing that to you, to a greater or lesser degree, all your life.
Up until COVID, U.S. life expectancy had been increasing consistent with its historical trend. So whatever it is that plastic in the environment is doing to us, it’s small enough not to perturb that trend. It doesn’t mean it has no effect, it just strongly suggests that the population-level health effects, at typical exposure rates, are likely small.
There needs to be one major caveat there: Assuming it isn’t just slowly accumulating. And we’re only now beginning to reap what we’ve been sowing for the past N decades. Haven’t stumbled across any evidence suggesting that, so far.
Thing 2: It’s not as if having harmful material in your air or drinking water is new, either. For example, Virginia requires that all public water supplies are tested, and that those test results be made public. So I know there’s lead in my drinking water, but the 90th percentile of water samples in my town showed 1.5 parts per billion, lead. That’s low enough that I cross it off my list of things to worry about. (Source: 2022 water quality report testing 2021 water, Town of Vienna).
Thing 3: This is a newly-recognized potential health hazard, and that means that there are no answers to even the most basic questions. This really wasn’t on the public-health radar screen a decade ago, near as I can tell.
Suppose, for example, you wanted to see the equivalent of the report shown above, but for the microplastic content of your local tap water. How much is there, in parts-per-million or parts-per-billion, and does that exceed some safety threshold? You would discover that:
Believe it or not, I don’t get paid by the word. So let me just state some key facts that I think I’ve learned, without citation as to sources, then cut to the chase regarding health effects.
A few observations.
First, taken as a whole, this likely explains why nobody routinely tests tap water for it. There’s no standard definition of it. There’s no hard evidence of human harm, let alone some agreed-upon maximum threshold for safety. It takes specialized equipment and techniques to measure. And there’s a good chance of contamination from the testing lab.
Second, there’s some obvious potential for mischief in reporting the presence of microplastic in (fill-in-the-blank), in that this stuff is everywhere. That is, there’s going to be a background level of microplastic in any testing lab. If you don’t net that out, you’ve got the potential to report finding microplastic in pretty much anything you care to test.
That is, do factory workers get sick from breathing in high levels of synthetic fibers?
Historically, workers in cotton mills suffered from a high incidence of brown lung. This was the result of chronic exposure to high levels cotton dust, or to the dust of other organic fibers (jute, hemp, and so on.)
Is there anything to suggest that the same thing happens with chronic exposure to high levels of fragments of synthetic fibers?
Short answer: Yes, starting with Flock Workers Lung (.pdf). This was recognized around the year 2000, in workers in Massachusetts plants that produced nylon flocking for use in producing velour-type fabrics. In those plants, long nylon fibers were chopped into short lengths. Inhaling airborne nylon fiber fragments led to inflammation, reduced lung function, and asthsma-like symptoms.
Whether polyester fiber fragments increase risk of lung cancer in factory workers is still an open question. One study of a quarter-million female textile workers in Shanhai, China found no association between synthetic fiber exposure and cancer (reference). By contrast, a study of one large industrial plant in France found that greater exposure to fiber dust was associated with increased risk of developing lung cancer (reference), but the dust was from a mix of fibers, including asbestos.
The upshot of this is that heavy exposure to large amounts of airborne synthetic fibers can mess up your lungs fairly badly. This is definitely true for nylon, and may be true for other synthetic fibers. (Several studies suggest to me that nylon fibers are particularly noxious, for reasons that appear related to what they release as they break down.)
This should come as no surprise, as chronic exposure to large amounts of almost any type of dust causes lung problems. Sometimes the diseases have names, such as black lung for coal dust, mesothelioma for asbestos, siliconiosis (sp?) for silicon dust, and so on. Sometimes, fiber will damage the lungs, but there is no specific name, for example, damage caused by breathing wood dust in a woodworking environment. Name a dust, and an excess probably causes problems. Toner? Yep. Fiberglass? Yep. And so on.
No. Not that I found.
First, it’s a good bet that most people will have some microplastic in their lungs. One small study in London (reference), using lung tissue samples that had been removed from people for various reasons. It looks like they found a small number of microplastic particles in every sample they tested, although the number was not hugely higher than the background rate in the test lab. By contrast, another study (reference) found 24 microplastic fibers total, in a sample of about 100 bits of lung tissue, but those fibers were more likely to be found in tumors than in normal lung tissue.
But in terms of linking population-level exposure to disease rate, I haven’t seen much. And the studies of factory workers suggest why. Where there appears to be an association between synthetic fiber exposure and cancer, say, we’re talking about modest increases (50% higher risk) for relatively rare cancers. If the massive exposure you’d get from working in a textile mill has only a modest impact, you may not be able to see much impact from the vastly lower exposure of the general population.
That said, there are some hints. There was a nice in-vitro study where polyester fibers inhibited the healing of lung “organoids”. And one of the studies of lung tissue found that plastic fibers were more likely to be found in lung tumors than in healthy lung tissue.
This is just a note-to-self that I now need to look up how water filtration works.
With COVID, I got up to speed on how air filters and N95 masks filter out aerosols. It’s not at all obvious, and it’s nothing like passing material through a fine-mesh filter.
For example, the hardest particle to capture is about 0.3 microns. That’s why N95 masks are rated as producing a 95% reduction in 0.3 micron particles. They actually produce a greater reduction in particles both larger and smaller than 0.3 microns.
I’m pretty sure that water filtration cannot possibly work the same way. For example, 3M Filtrete material takes advantage of Brownian motion of particles in the air, in order to bring the most difficult-to-capture particles (0.3 micron) into contact with the electrostatically-charged filter material. Well, that’s not going to work in a dense fluid like water. Brownian motion won’t move particles far enough.
But I just plain don’t know. For example, the Brita filter at the start of this posting is rated for capturing particles in the 0.5 to 1.0 micron (micrometer) range. Is this like an air filter, so I can be assured that it captures even higher percentages of particles larger and smaller than that? Or does that mean it simply doesn’t capture particles below 0.5 microns?
I just have a hunch that if you poured water through an N95 mask, it wouldn’t filter the water. But I need to get up to speed on the basic science.
