Microplastics are making their way into the human brain at higher levels than previously recorded
Microplastics are burrowing into our brains with unknown consequences for human health, a new study has found.
Every day, people breathe, eat, and drink tiny shards of plastic waste known as microplastics and nanoplastics.
Scientists have long suspected they may be able to cross the blood-brain barrier, which acts as a filter between the central nervous system and the rest of the body, protecting the brain from toxic substances and providing it with nutrients.
The study, which was published in the journal Nature Medicine, is the latest to suggest they can.
Researchers from the University of New Mexico in the US analysed postmortem samples from 52 human brains, including 28 that were autopsied in 2016 and 24 samples from 2024.
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They found microplastics in every brain sample – and a 50 per cent higher concentration in 2024 than in 2016.
They also identified higher levels of microplastics in the brain than in other organs like the kidney and liver.
Microplastics appear to be crossing the blood-brain barrier
“The scientific evidence documenting plastic contamination in every imaginable matrix is amassing, so I am unfortunately no longer surprised to see this,” Bethanie Carney Almroth, an ecotoxicologist studying the environmental effects of plastics at the University of Gothenburg, told Euronews Health.
Microplastics have previously been identified in human blood, lungs, placentas, and breast milk.
But “the idea that particles … can cross the blood-brain barrier is concerning,” said Almroth, who was not involved in the new study.
Researchers still don’t know exactly how – or how much – microplastics affect health outcomes. Other studies have identified potential links to serious issues including several types of cancer, respiratory problems, heart attack, and inflammatory bowel disease.
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The new study offers another clue. The researchers studied the brains of 12 people who had dementia, and found a higher concentration of microplastics in their brains than among people without a diagnosis.
Meanwhile, the increasing concentration of microplastics in the brain likely reflects the growing production and use of plastics, Tamara Galloway, a professor of ecotoxicology at the University of Exeter in the UK who was not involved with the study, said in a statement.
Evidence of microplastic health impact is ‘growing’
Most of the plastic shards found in brain samples were polyethylene, which is widely used for food and drink packaging as well as shampoo bottles, recycling bins, and more.
Notably, there was no link between how old the patients were when they died and the amount of microplastics in their brains, suggesting “microplastics do not accumulate continuously in brain tissues as we age,” Galloway said.
“This is significant because it suggests that if we were to reduce environmental contamination with microplastics, the levels of human exposure would also decrease,” she added.
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The study authors noted that the brain samples were collected from different parts of the US, which could affect the findings.
They also stressed that more studies are needed to determine whether microplastics in the brain actually cause health problems, ideally over a longer period of time with bigger groups of people.
Even so, independent researchers said the results were worrying given how pervasive microplastics are in the environment.
“It is always difficult to prove causation, especially in human studies which tend towards correlations,” Almroth said.
But “evidence of health impacts of plastic particles is also growing”.
