You have plastic in your brain. That part is probably true, and the headlines have it right. What they get wrong is the sentence that comes next.
Two studies are behind the alarm. In February 2025, a team at the University of New Mexico published autopsy work in Nature Medicine that found microplastics in every one of 52 human brain samples, at 7 to 30 times the concentration in liver and kidney. The brains of people who died in 2024 held roughly 50 percent more plastic than those from 2016. The total in an average brain came to about a plastic spoon's worth. Most of it was polyethylene, the plastic of shopping bags and bottles.
A year earlier, in March 2024, Italian researchers reported in the New England Journal of Medicine on 257 patients who had fatty plaque surgically scraped from a neck artery. In more than half, the plaque contained plastic. Over the next 34 months, the patients with plastic in their plaque had about 4.5 times the rate of heart attack, stroke, or death from any cause as those without it (hazard ratio 4.53; 95 percent confidence interval 2.00 to 10.27).
Those are the numbers. Now the sentence the coverage keeps dropping. Neither study shows that the plastic caused any harm. Both found an association: the plastic was present where the disease was worse. That is not the same as the plastic making it worse.
Take the brains with dementia, which held the most plastic, 3 to 5 times the rest. It reads like a smoking gun until you remember that dementia damages the blood-brain barrier, the filter that keeps foreign material out of the brain. A leaky barrier lets more plastic in. So the plastic may be a mark of the failing brain rather than its cause, and the authors say as much: brain shrinkage, a leaky barrier, and poor clearance are all hallmarks of dementia, all of them likely to raise the plastic count, so the paper assumes no cause and effect. The dementia group was also tiny, three brains. The method itself is contested, too. A second Nature Medicine paper in late 2025 argued that telling plastic apart from the body's own molecules at these levels is harder than the first paper allowed.
The artery study carries its own asterisk. Its authors say outright that it does not prove causality and that unmeasured factors could explain the result. In letters to the journal, other physicians went further and questioned whether the plastic was even in the plaque to begin with: an operating room is full of polyethylene and PVC tubing, the study took few precautions against a sample picking up stray plastic during surgery, so some of what was measured may have come from the room, not the patient.
None of that makes the plastic imaginary. It is genuinely everywhere, and it does get into us. The routes are boring: what we drink, what we breathe indoors, food that has sat against plastic. People who drink only bottled water take in something like 90,000 plastic particles a year; people who drink tap water, around 4,000. What you can safely ignore is the line, repeated everywhere, that each of us swallows a credit card's worth of plastic a week. A credit card weighs five grams, which is five million micrograms. The real estimates run in the low micrograms a week, hundreds of thousands of times smaller. It is a tidy example of how this subject gets inflated.
So here is where the evidence actually leaves us. Plastic is in the brain and in diseased arteries, in amounts that appear to be rising and are worth watching. Whether it harms us, at what dose, and whether removing it would help, we do not know. Cutting bottled water and not heating food in plastic will lower the amount in your body. Nobody can yet tell you it will lower your risk of anything. That is less than the headlines promise. It is also the truth, and the truth is the part worth keeping.
