Plastics present everywhere
They are omnipresent in the environment and, therefore, inhaled or ingested daily by each of us, which makes it a subject at the heart of the negotiations which reopen Tuesday in Geneva to lead to a treaty against plastic pollution.
Before the brain, scientists have already found microplastics in recent years in the lungs, the heart, the liver, the kidneys, or even in the placenta and the blood.
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An increased phenomenon
The study published in Nature Medicine was carried out from the autopsy of around fifty people who died in the American state of new-mexic. Part of the sample had died in 2016, the other in 2024. This work concluded that the systematic presence of microplasticism in the brain, as well as a clear increase between the two dates.
A brain could thus contain the equivalent of a teaspoon of microplastics, had imagined Matthew Capen, principal researcher of the study. The American toxicologist had also estimated that researchers could extract approximately 10 grams of plastic from a removed brain.
A lack of evidence
A figure likely to make an impression, but some specialists emphasize that the study cannot be self-sufficient, given the small number of people and their geographic concentration in one place.
“Even if these are interesting results, they must be interpreted with caution,” warns the researcher Theodore Henry, a specialist in environmental toxicology at the Scottish University Heriot-Watt. And “at this stage, speculation about possible health effects venture far beyond the evidence”, he puts it into perspective.
Likewise, Oliver Jones, professor of chemistry at the Australian University Rmit, prefers to remain cautious: “If-and it is a big one if in my opinion-there are microplastics in our brain, there is currently no evidence of harmful”, he underlines to AFP.
Established links
However, many researchers consider that this study largely justifies to question the effects of microplastics on our brain, while, in recent years, first elements have appeared on other health risks.
A study published in 2024 in the New England Journal of Medicine shows an association between the accumulation of these particles in blood vessels and an increased risk of heart crisis, stroke, even death, in some people with atherosclerosis, a disease affecting the arteries.
Studies remain to be done
At present, no study of this type exists for the brain and, more broadly, the neurological risks associated with microplastics in humans. But toxicologists call for the precautionary principle, citing the example of other types of pollution such as that with fine particles in the air.
“What is worrying for the brain is that fine particles are the chemical component of the exhibition”, that is to say all the environmental factors to which a person is exposed, “who is most associated with Alzheimer’s disease”, underlines the French toxicologist Xavier Coumoul, professor at Paris Cité University.
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What about microplastics?
Would it be the same for microplastics? The answer is not obvious since the fine particles are of a “quite different nature”, as Mr. COUMOUL notes, but they deserve more research, in particular experiences on animals like mice.
Still few, these studies are nevertheless beginning to give some results, even if they cannot alleviate similar effects in humans alone.
The consequences in mice
Published in January in the journal Science Advances, an experience, for example, highlighted in mice the deleterious effects of microplastics whose presence was detected live in the brain by advanced imaging techniques.
These microplastics “can cause brain thromboses […] And generate neurocomptal disorders, “conclude the authors of this study conducted in China.
