It seems like a day can’t go past without microplastics turning up in some new part of the human body. Recent studies have claimed to find them in lungs, livers, kidneys, and now in brains. Articles in both mainstream and fringe media tell us we’re being slowly turned to plastic, most likely with serious health consequences. This story has a visceral attraction. There’s something captivating about the idea of invisible little bits of modernity contaminating the very cells of our bodies, even inserting themselves into the architecture of our minds, causing dementia and other neurodegenerative diseases. It’s downright spooky.
But is it true? While I am far from a denialist about the dangers of the modern food system generally and microplastics specifically (take a look at a list of my recent blog posts) it’s critical to be both accurate and measured when trying to gauge what we know and what we don’t. Every day we hear about new potential dangers posed by the modern world, and it behooves us to view them soberly.
Let’s look at the recent study on microplastics in the brain. It was reported by dozens of outlets, generally with very alarming headlines. I’ve read several of these, and all of them are completely credulous of the claims made in the paper — that the concentration of plastics is increasing, that its likely 0.5% of brain tissue by weight, that it is probably a contributor to neurological diseases. I’m not linking to these because I don’t want to support the publication of such shoddy journalism, but a quick google search will turn up endless examples if you’re interested.
While I’m not in a position to assess the validity of the details of the study itself, I can say that the way it’s been covered is completely ridiculous. The first thing to point out, and I can’t emphasize how significant this is, is that the study under discussion, the study that has launched dozens of breathless articles, is a preprint. That is, independent scientists versed in the analytical methodologies used and familiar with the larger body of literature have not subjected it to the sort of rigorous criticism that good, reproducible science relies on.
So in the paper, when the authors claim they have accounted for potential contamination of the samples by external sources (plastic is used in all sorts of things!) I find their explanations persuasive, but I have no idea if I should, I have no idea what proper controls would look like, let alone whether those used in the study qualify, and I don’t even have the assurance of independent experts that I should trust the results. The fact that this is such a new area of research means questions of process should be put under special scrutiny, and even if this paper does pass peer review, no single study is anything like dispositive.
There are other issues. The study used a very small number of samples, 27 from 2016 and 24 from 2024. All were collected from the Albuquerque area. This is large enough to explore whether further research is needed, but far too small to make sweeping statements about what is going on at a population level. Unless I’m missing something, the claim that level of microplastics in the brain are increasing is based on the difference between the 2016 and 2024 samples, which, again, numbered 27 and 24 respectively. I’m no statistician, but it seems like a leap to draw a line between two small data sets and call it a trend, let alone to claim that trend describes the country as a whole.
And the authors don’t stop there. In the conclusion they explicitly draw a connection — not a causal connection, but a connection nonetheless — between this supposed trend and increasing rates of Alzheimer’s and other neurodegenerative diseases, a connection science journalists enthusiastically echo.
To be clear, I suspect microplastics are bad. I take common sense measures aimed at reducing the likelihood that my family and I are consuming them in large quantities. But I readily admit that I’m driven by a combination of common sense and precaution, not settled science. The study of how microplastics impact health is in its infancy. Soon, I hope, we will have standardized methods for measuring them. I hope these will be used to assess thousands of sample rather than dozens, which would begin to illuminate just how widespread they are, as well as the most common ways they are entering human bodies. Even at that point it is incredibly unlikely that we will be able to draw a straight line from them to any particular health outcome, though we will be able to more effectively reduce our exposure to them.
The hard thing to do, whether you’re assessing the risk of microplastics or buying a car or crossing a busy street is to recognize the impossibility of making a perfect decision, to dismiss anyone who claims to have perfect information, and to nevertheless go ahead and make a choice.
