The Campen laboratory at the University of New Mexico analysed 52 post-mortem brains (28 from 2016 and 24 from 2024) using pyrolysis gas chromatography mass spectrometry, along with liver and kidney samples from the same donors.
They reported polyethylene as the dominant plastic, concentrations in brain far higher than in liver or kidney, a significant rise between 2016 and 2024, and higher levels in 12 people who had died with dementia. The average of about 4,900 micrograms per gram in 2024 brains was widely reported as 'a spoonful of plastic in your brain'.
Independent scientists have raised serious objections. The pyrolysis method can mistake brain fats for polyethylene; more than 10% of brain tissue was left undigested compared with under 1% for other organs; contamination controls were weak; and the authors issued a correction for duplicated supplementary images. A 2026 study using spectroscopic particle counting found levels roughly 100 times lower.
Site guidance: do not use the 'spoon of plastic' figure. Say instead that plastic particles have been detected in virtually every brain sample tested, and that how much, and whether it causes harm, remains unresolved.