A weekly health led newsletter grounded in evidence-based medicine along with prospective randomized controlled trials (RCTs) by medical specialists. Our goal is to help you make sense of complex scientific information and turn it into clear, evidenced based practices you can use to make better decisions about your health and wellness.

Matthew Campen did not expect to find plastics in the brain.

He is a toxicologist at the University of New Mexico. He had already found microplastics in human lungs, in testes, and arterial plaque. None of that surprised him much. Those tissues are in contact with the outside world, one way or another. But the brain sits behind the blood-brain barrier, one of the most selective filtering systems in human biology, evolved over thousands of years to keep foreign particles out.

In 2025, Campen and his team published their brain tissue findings in Nature Medicine.

Every single sample contained plastic.

Not just simple trace amounts from contamination. The brain tissue of people who died in 2024 contained roughly 50 percent more plastic than the brain tissue of people who died in 2016. The dominant polymer was polyethylene. Under electron microscopy, it appeared as nanoscale shard-like fragments.

This issue is about what we actually know, what we honestly do not know just yet, and what you can do about it without waiting for regulators who will not report back until 2027.

TL;DR

THE BIOLOGY

Your body is continuously swallowing and breathing plastic.

The ingestion route is the obvious one. Microplastics shed from packaging into food and drink, from the epoxy linings of canned beverages, and from plastic containers when heated. A 2021 systematic review estimated humans ingest between 0.1 and 5 grams of microplastics weekly. A separate particle analysis put the count at 39,000 to 52,000 particles per year from food and water alone.

The inhalation route is the one most people do not think about. Synthetic textiles, tire wear, and indoor dust shed plastic fibers continuously. Indoor air carries elevated concentrations because polyester clothing, carpets, and upholstered furniture release particles constantly. Most adults spend over 90 percent of their time indoors.

Particle size determines how deep any of this travels.

Microplastics above a few microns tend to stay in the gut or respiratory mucosa and get cleared. Nanoplastics, below one micron, are the problem. They are small enough to cross the membranes that evolved to stop them. They enter capillary beds, achieve systemic circulation, and reach tissue that should never encounter an environmental contaminant.

That is how plastic ends up in a placenta, in the wall of an artery, or in the frontal cortex (brain) of a person who did nothing unusual.

DEEP DIVE

The blood brain barrier called BBB deserves a moment, because the finding only lands properly if you understand what it was supposed to prevent.

The blood-brain barrier is a wall of tightly sealed endothelial cells lining the brain's blood vessels. It evolved to maintain the precise chemical environment neurons require. It blocks pathogens. It blocks most drugs. Pharmaceutical companies spend billions trying to get medications past it.

Nanoplastics find their way past this barrier..

Researchers believe the mechanism is the "biomolecular corona": a protein and lipid coating that forms around nanoplastics when they enter the bloodstream. The body's own transport proteins camouflage the plastic particles. The BBB's (blood-brain barrier)  receptor systems see something that looks like a legitimate molecule and actively ferry it across. Once inside, there is no exit.

Campen's autopsy data showed brain tissue concentrations averaging around 4,800 micrograms per gram in 2024 samples. That is approximately 0.5 percent of brain tissue by weight. Higher than any other organ sampled.

People with dementia in the cohort had far higher concentrations than those without.

What mechanistic research in cell and animal models does show: nanoplastics in brain tissue can trigger microglial activation, producing chronic neuroinflammation. They can also disrupt mitochondrial membranes. Plastic particle surfaces have been shown to seed the kind of protein aggregation associated with Alzheimer's pathology.

These are not yet proven human clinical outcomes. They are the reasons this finding is being taken seriously.

CARDIOVASCULAR

In March 2024, Raffaele Marfella's team at the University of Campania published a study in the New England Journal of Medicine.

257 patients undergoing carotid artery surgery. The excised plaque was analyzed for plastic. Polyethylene was noted in 58.4 percent of samples, with a mean concentration 21.7 micrograms per milligram of plaque. Some samples also contained polyvinyl chloride (a molecule commonly found in pipes, window frames, and flooring.)

Then the team followed those patients for 34 months.

The ones whose plaque contained detectable plastic had a hazard ratio (rate at which an event occurs in a treatment group compared to those with no intervention at all) of 4.53 for a composite of heart attack, stroke, or death. Confidence interval 2.00 to 10.27 was noted. FYI, a confidence interval not including 1 warrants the data statistically significant, meaning there is validity to the data. That is not a rounding error. That is a 4.5-fold difference in 34 months.

REPRODUCTIVE HEALTH

In May 2024, Yu and colleagues at the University of New Mexico published findings in Toxicological Sciences.

They analyzed testicular tissue from 23 humans and 47 dogs. Every single human sample contained microplastics. Every dog sample too. Human mean concentration was 328 micrograms per gram, three times the dog samples.

A separate cohort study examining semen directly found 15 distinct plastic polymer types in human samples. Participants with detectable PET (polyethylene terephthalate) plastic in their semen had sperm progressive motility of 20.6 percent. Those without detectable PET: 34.9 percent. This means the sperm motility was slower in those with plastic, which sounds plausible.

Two mechanisms are proposed. The first is physical: nanoplastics crossing the blood-testis barrier and triggering cellular stress in the seminiferous tubules. The second is chemical: BPA and phthalates leaching from particles and interfering with androgen receptor signaling, also suppressing testosterone synthesis at the Leydig cell level.

The chemical mechanism is well-documented in cell models. Its magnitude in adult men at typical real-world exposure levels is not yet quantified.

EXPOSURE SOURCE

Almost every aluminum can in the world is lined with epoxy resin. It prevents the metal from corroding. It keeps the contents tasting right.

For decades, that resin was made with Bisphenol A.

When research on BPA's endocrine-disrupting properties became impossible to ignore, manufacturers switched to BPA-free linings. They replaced BPA with bisphenol S, bisphenol F, and bisphenol AF.

PROTOCOL

The EPA added microplastics to its priority contaminant evaluation in April 2026. EFSA reports in late 2027. No enforceable safe exposure limit exists anywhere. The practical burden is yours, for now.

On cruciferous vegetables: the mechanism is real and the dietary addition costs nothing. Clinical confirmation specific to plastic chemical clearance in humans does not exist yet. It earns its place because of limited downside.

READER'S PULSE

This newsletter is for informational purposes only and does not constitute medical advice. Consult a licensed physician before beginning any new health intervention.