Microplastics in the Brain: What the New Research Found and What It Means For You
If you’ve seen headlines suggesting microplastics are showing up in human brains, you’re not imagining things.
In February 2025, a peer-reviewed study in Nature Medicine entitled “Bioaccumulation of Microplastics in Decedent Human Brains” reported that micro- and nanoplastics were detected in human brain tissue collected during autopsies, and that measured concentrations in their dataset were higher in 2024 than in 2016.
That’s a big deal—because it moves the plastic crisis beyond beaches and wildlife and into the realm of human biology. So let’s discuss the nature of the study, its findings, and what it means for you.
What counts as “microplastics” (and why “nano” matters)
Microplastics are generally defined as plastic pieces smaller than 5 millimeters.
Over time, larger plastics break down into smaller fragments, and microplastics can further degrade into nanoplastics—often described as smaller than 1 micrometer (µm).
That size difference matters because tiny particles can behave differently in the body, and they’re also harder to measure consistently, which is why studies sometimes produce confusing or conflicting results.
The Nature Medicine study (in plain English)
Researchers obtained de-identified postmortem human samples of:
Brain (frontal cortex)
Liver
Kidney
They compared samples from 2016 vs. 2024 from the same medical investigator’s office, and also included a time-series of older brain samples spanning earlier years (1993-2013). To detect and quantify plastics, they used pyrolysis gas chromatography–mass spectrometry (Py-GC/MS) alongside other visualization/validation approaches.
What the study found
1) Concentrations in the brain measured higher than in the liver and kidney
The study reported brain micro/nanoplastics concentrations 7-30 times greater than in the liver and kidney in the study’s dataset.
2) The 2024 samples were higher than 2016 samples
In the frontal cortex samples they analyzed, the study reported medians around:
2016 brain samples: 3,345 µg/g
2024 brain samples: 4,917 µg/g
They also reported liver and brain samples from 2024 were significantly higher than 2016 in their statistical analysis.
3) Polyethylene showed up as the dominant polymer
The study’s polymer breakdown suggests polyethylene (PE) was the most abundant polymer detected, and the paper describes PE as accumulating more in brain relative to liver or kidney.
Notably, polyethylene is one of the most common plastics used across packaging and consumer products such as shopping bags, cutting boards, drink bottles, children’s toys, cling wrap, etc. —so it’s consistent with broad, everyday exposure rather than a niche source.
4) A dementia subgroup was reported as higher
The study also compared a dementia cohort (brain samples with documented dementia diagnosis) to non-dementia samples and reported higher concentrations in that subgroup. While it is worth emphasizing that the data set here is limited and it does not establish that plastics cause dementia, the paper does acknowledge that MNPs worsened diseases and created toxicity in both cells and animal subjects in other controlled studies. Surely, we would do well to limit our exposure to microplastics and the potential health risks that they pose.
What you can do right now
Even with unanswered questions regarding the long-term effects of higher plastic concentrations in the brain, there are practical steps that reduce likely exposure and reduce plastic pollution overall—meaning they’re worth doing regardless of where the science lands.
1) Reduce single-use plastics where it’s easy to do
Less single-use plastic means less plastic waste in the environment, where it fragments into microplastics over time.
2) Rethink bottled water as a default habit
In January 2024, researchers reported an average of ~240,000 plastic particles per liter in bottled water across three brands tested using an advanced detection method, with ~90% being nanoplastics.
Does that prove bottled water leads to brain plastics? No.
But it does support a common-sense move: if you have safe tap water, a reusable bottle and a good filter can reduce reliance on plastic packaging (and save money).
3) Avoid heating food in plastic
Heat can increase the release of plastic particles and chemicals from food-contact plastics, and multiple public-facing outlets now recommend minimizing heat and plastic contact as a reasonable precaution.
4) Support research
If measurement is inconsistent, policymaking becomes guesswork and accountability gets easier to dodge. The fact that Nature Medicine published both the original findings and a formal methodological critique shows the field is actively working toward more rigorous standards.
Why Tidey focuses upstream
Here’s the frustrating truth:
Once plastic enters rivers and oceans, it doesn’t just “go away.” It breaks down. It spreads. It becomes harder to recover and harder to measure.
That’s why Tidey is built around a simple strategy: stop plastic at the source (before it reaches waterways) and track the results in a way people can trust.
If microplastics are showing up in places as personal as human tissue, then upstream prevention becomes more than an environmental strategy—it becomes a long-term public health strategy too.
Sources: Nature Paper, EPA, Kirkfield.co, NIH, Washington Post, UCSF, Henry Ford Health
