RFK Jr Says You Have A Spoonful Of Plastic In Your Brain – But Do You Really? We Asked The Experts

That all sounds rather scary. This reporter, for one, would not willingly place a spoonful of plastic into his own brain if given the choice. Certainly not one that grows exponentially larger over time. But is this measurement really accurate, and, ultimately, is it really something we should be worried about?

There is certainly a lot more plastic in our environment than ever before. A 2017 study that attempted to calculate how much found that we produced around 6,300 megatonnes of plastic waste between 1950 and 2015, of which 4,900 megatonnes (60 percent of all plastic ever produced by that point) either ended up in landfills or was simply discarded. If you want help visualizing this gargantuan number, you can think of it as 15,000 Empire State Buildings' worth by weight.

Very little of this plastic biodegrades in any meaningful way, but sunlight and abrasion from wind, rain, and any number of other factors cause it to fragment over time, producing particles that are millimeters or micrometers in size. These are microplastics – they've been found everywhere from Antarctica to the bottom of the Mariana Trench, and they appear to be traveling around our planet via the atmosphere.

It’s clear that we encounter microplastics in the environment every day, but what that means for human health is less straightforward. Studies of human cells have shown that microplastics can cause cell death, allergic response, and damage to the cell surface membrane. “Harmful effects on cells are in many cases the initiating event for health effects,” researcher Evangelos Danopoulos at Hull York Medical School in the UK explained to The Guardian in 2021.

To know whether real-world exposure is actually causing harm, however, you first need to know precisely how much plastic is getting into the body, into which organs, and what state it is in when it gets there. That, you might think, has a simple solution: just measure it. But attempts to do so have sparked incendiary debate, bringing us back to that study RFK Jr cited, which elicited such disdain from one researcher that he called it "a joke" in a recent article, also in The Guardian

So, what was that study, what did it find, and did it really deserve to be lambasted like that?

The study in question was published in February 2025 in Nature Medicine by a team led by Matthew Campen at the University of New Mexico. Campen's team analyzed brain tissue from postmortem donors – centering on 28 from 2016 and 24 from 2024, with some additional samples from earlier time periods – and found microplastics were present in every sample, and that they appeared to have risen nearly 50 percent from 2016 to 2024.

The brains they tested from 2024 had a median microplastic content of 4.9 milligrams per gram, which does indeed come out to something like 7 grams, or roughly a spoonful, in the average brain. So RFK Jr wasn't making those numbers up. But ever since the work was published, researchers have expressed their concern that this finding is an overestimation.

Such pioneering attempts are highly valuable, even if they were not perfect. I greatly admire their efforts in advancing this field.

Xiaolin Chen

The problem comes partly from the ever-present risk of contamination that is par for the course with microplastics research – the samples used here weren't collected specifically for microplastics analysis, and it is unknown what might have happened to them before they were analyzed that might have boosted the level of microplastics within. IFLScience reported as such when we covered the story last year.

There are also concerns over pyrolysis-gas chromatography-mass spectrometry, or Py-GC/MS, one of the methods Campen's team used to quantify how much plastic was in their samples. The technique works by heating the sample until it vaporizes, then identifying the breakdown products of any polymers, such as those from plastics, that were present. But fat produces breakdown molecules that closely resemble those from common plastics polyethylene and PVC – and the brain contains a significant amount of fat.

Researchers disagree on quite how much of a problem this poses in practice, but the concern is that studies using Py-GC/MS on brain tissue could be detecting lipids rather than plastic, making concentrations appear higher than they actually are.

In an article challenging Campen's team's findings, critics drew up a list of what best-practice techniques should look like. This included running filtered water through exactly the same preparation as real tissue to account for background levels of plastics; using validated digestion protocols to break down organic matter before analysis; and deploying multiple analytical techniques whose results can be checked against one another.

The question, then, is do we have any other attempts to find out how much plastic is in the brain, and how did they go about doing it? Luckily we do, and it is actually a very recent study by researchers including Xiaolin Chen at Beijing Tiantan Hospital in China.

Chen's team collected 156 brain tissue samples from 113 patients undergoing surgery for brain tumors, alongside 35 healthy brain samples from five postmortem donors. All samples were collected using strict plastic-free protocols, and they ran filtered-water blanks through their experiments to monitor the background levels of microplastics.

Using four methods – laser direct infrared spectroscopy, scanning electron microscopy, optical photothermal infrared spectroscopy, and Py-GC/MS – they found microplastics or nanoplastics in 99.4 percent of diseased tissue samples and 100 percent of healthy ones.

We may never have a method that everyone agrees on.

Matthew Campen

In contrast with Campen's team, Chen and colleagues found plastic at a median concentration of just 0.053 milligrams per gram in healthy tissue, or roughly 100 times less than the 4.9 milligrams per gram Campen's group reported. Rather than a spoonful – or, indeed, a single plastic spoon's worth, as Campen originally illustrated it – this is more like two or three grains of uncooked rice, or about 70 milligrams of plastic, per brain.

"Although the Nature Medicine study had methodological limitations, its significance remains undeniable," Chen told IFLScience. "At the time, no standardized protocols existed in this field to guide best practices. Therefore, such pioneering attempts are highly valuable, even if they were not perfect. I greatly admire their efforts in advancing this field."

Is that it then? We can just swap out the image of a spoon or spoonful and replace it with a few grains of rice? Admittedly, that also doesn't sound like a fantastic amount of plastic to have rattling around up there, but we can at least take comfort in it being a lot less than a spoon's worth.

Perhaps the better thing to learn from this whole affair is that, given the massive variance between these two studies, we should take the results of both of them with a pinch of salt. Marja Lamoree, a microplastics researcher at Vrije Universiteit Amsterdam who has herself published work in this area, put it like this in an email to IFLScience: 

"There are flaws in both papers, like there are undoubtedly flaws in ours, but the expectation that this field is already mature enough to put an accurate number on a measurement is false. I usually say that I think our own results could turn out to be e.g. twice as low, or 5 times higher than we now report, due to progress in the field. This does not mean the work is useless."

As microplastics detection methods mature, the real figure for the amount of plastic in the brain could end up wildly different from either Chen's number or Campen's. As Lamoree notes, this is a research field "in its infancy, while the general public is being fed with sensational scraps of information."

Campen also acknowledges this: "There are a number of factors and we may never have a method that everyone agrees on," he told IFLScience. "I think we are all limited by bandwidth and make methodological choices based on a number of meritorious considerations. Seeing other groups move the field forward one or two steps at a time is really helpful to the larger pool of scientists."

So, with that in mind, the huge injection of funding RFK Jr announced could be exactly what microplastics research needs – not to remove plastic from your brain, necessarily, but at least to come to a better understanding of what these results are telling us, and then potentially designing experiments that are more comparable and building out our picture of what's really going on.

Microplastic pollution certainly has the potential to be a serious public health concern, and the question of what it does inside the human body deserves attention. But you probably don't need to go around worrying about a spoonful of plastic sitting in your skull, growing by 50 percent every decade. That particular image, vivid as it is, perhaps tells us more about the state of science communication than it does about the state of your brain.

All “explainer” articles are confirmed by fact checkers to be correct at time of publishing. Text, images, and links may be edited, removed, or added to at a later date to keep information current.