Does your brain really have enough plastic in it to make a spoon?

Last year, we wrote about how a decimal-point error and selective framing turned black plastic spatulas into a public-health scare. Now Netflix’s The Plastic Detox is amplifying another over-the-top claim: that the human brain may contain enough microplastic to make a plastic spoon. That line traces to a February 2025 Nature Medicine paper from researchers at the University of New Mexico. In postmortem frontal cortex samples collected in 2024, the authors reported a median microplastic concentration of 4,917 µg/g, or roughly 0.49% by weight. Scale that to an average brain and you get a visually irresistible metaphor.

Median 2024 brain concentration of roughly 4,900 µg/g × 1,400g average brain = about 6.9 grams. A disposable plastic spoon weighs around 7 grams. That’s how the line was born.

Yet the paper’s own discussion flags something the Netflix documentary didn’t: the method used to isolate plastic from tissue left behind roughly 14 times more biological residue in brain samples than in liver or kidney. The authors acknowledge this, and they cite prior work showing that lipids, which the brain has in abundance, can mimic polyethylene on the same detector. The brain gave the highest reading. That means the “spoon” comparison is effectively a rough estimate.

So how much plastic is actually in the brain? It isn’t entirely clear. A separate 2024 study in JAMA Network Open used an entirely different detection method and found 1 to 4 individual microscopic particles per brain sample. Meanwhile, the best available measurement of plastic circulating in human blood sits around 1.6 µg/g. The UNM paper claims roughly 3,000 times that concentration in brain tissue, which is an accumulation factor the authors speculate about but don’t model.

To be clear, the Nature Medicine medicine paper has faced some degree of criticism. Within weeks of publication, reviewers on PubPeer flagged duplicated images in the supplementary data. Independent critics noted the reported concentrations exceeded levels typically found in sewage sludge, “which seems unlikely,” Oliver Jones, professor of chemistry at The Royal Melbourne Institute of Technology, told The Transmitter. A 2025 study from the University of Queensland concluded that the Py-GC/MS method isn’t currently reliable for detecting polyethylene in biological tissue at all.

By November of 2025, the findings had been formally challenged in a letter published in the same journal. The critics noted that the diagnostic markers needed to distinguish polyethylene from brain fat were absent from the data, and that the method’s digestion step left more than 10% of biological material intact in the brain samples, versus less than 1% in liver and kidney.

The Nature Medicine is not the only one to face scrutiny in this area. In January, The Guardian reported that seven major microplastics-in-humans studies have been formally challenged in their respective journals, with one environmental chemist calling the reported concentrations ‘completely unrealistic.’ The brain paper was among them

None of this lets plastics off the hook. A 2024 New England Journal of Medicine study, for instance, linked microplastics in carotid artery plaque to higher rates of heart attack and stroke.