Podcast episode 107 (in German)

Microplastics in the brain – the spoon nobody can re-measure

October 15, 2026

Your brain contains roughly one plastic spoon, so the headline went. The measurement behind it really exists, but analytical chemists do not question the size of the number, rather whether it can be re-measured at all.

What it is about

The starting point is a paper in Nature Medicine that found 4,917 micrograms of plastic per gram in brain tissue from deceased people, with an increase over 8 years. The spoon itself is a second-hand conversion. Then comes the objection: 6 research groups from environmental analytics and nanotoxicology consider the method unsuitable for distinguishing fat from polyethylene — in the fattiest organ, of all places. A new paper measures around 100 times less, but has its own problems, above all missing blank samples. What remains in the end: plastic in the brain is considered detected, its amount is unknown, and without a reliable amount there is no dose and no risk assessment. Along the way, the episode explains why many measurements do not yet add up to much knowledge.

Key points

Brain samples from 2024 contained 4,917 micrograms of plastic per gram of tissue, 8 years earlier 3,345; three quarters of the signal was polyethylene.
The spoon is an extrapolation: 0.5 percent of brain mass corresponds to about 6 grams — the conversion comes from a science magazine, not from the study.
12 brains with documented dementia came in at 26,076 micrograms per gram; as a cross-sectional finding, this does not say whether plastic causes harm or accumulates in damaged tissue.
The brain consists of about 60 percent fat, liver and kidney of less than 5 — and long-chain fatty acids break down on heating into fragments that look like polyethylene.
The new paper with 191 samples measures 50.3 micrograms per gram in healthy brain tissue, 60.9 in the meninges and 129.4 in tissue near tumors — around 100 times less than the older one.
In the carotid artery, polyethylene was found in the plaques of 58.4 percent of 257 patients; their risk of heart attack, stroke or death over 34 months was 4.5 times as high.
The episode awards human evidence 2, safety 2, use 0 and hype 9 with an open direction — papers that differ by a factor of 100 do not add up.

Where the data stop

The core of the criticism is that the values cannot be re-measured this way. The blank sample, that is, the same run without tissue, is apparently missing in the new paper too. Its particles average 32 micrometers in size and are thus too large for the blood route into the brain; in the older paper they were under 200 nanometers. Digestion with hot nitric acid attacks precisely the plastics being counted, and the polyamide 66 found hardly occurs in the environment, but does in lab coats and tubing.

For the brain, no finding so far links a measured burden to a disease course; in the tumor, the leaky tissue could just as well collect the plastic. The only clinical association, from the carotid artery, hinges on 21.7 micrograms per milligram of plaque, in individual cases 15 percent of the mass — a value an environmental chemist considers absurd. There is no tested measure against the burden. This is not an all-clear, but an open question.

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Published on October 15, 2026.

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Information only, not medical advice and not a usage or dosage recommendation. Prescription-only and unapproved substances belong in the hands of a physician. Last updated: 2026-09-22.