The human brain is now accumulating microplastics in alarming quantities. These particles, resulting from the degradation of plastic waste, could play a role in the development of neurodegenerative diseases.
A recent study, published in
Brain Medicine, reveals that brain tissues contain concentrations of microplastics and nanoplastics significantly higher than those in other organs. Researchers highlight an alarming increase in these particles between 2016 and 2024, parallel to the rise in plastic levels in the environment.
A concerning infiltration into the brain
Microplastics, measuring less than 5 millimeters, and nanoplastics, even smaller, are found everywhere: in water, air, and the food chain. Their tiny size allows them to cross biological barriers (such as the blood-brain barrier in the case of the brain), where they accumulate in surprising amounts. Researchers estimate that the human brain contains the equivalent of a tablespoon of these particles, an alarming quantity for such a sensitive organ.
Post-mortem analyses show that the brain contains up to 30 times more of these particles than the liver or kidneys. Nanoparticles, in particular, are capable of penetrating the walls of cerebral blood vessels, which could explain their high concentration. Individuals with dementia show levels 3 to 5 times higher than those without neurological disorders.
Researchers have identified 12 types of plastic polymers in brain tissues, with a predominance of polyethylene, commonly used in packaging. This discovery raises questions about the long-term effects of these materials on neurological health, especially since their concentration in the brain has increased exponentially between 2016 and 2024.
Simple solutions to limit exposure
One of the main sources of exposure to microplastics is bottled water. Replacing it with filtered tap water could reduce annual ingestion of these particles by 90%. Plastic tea bags and microwave-heated food containers are also significant sources.
The study's authors recommend avoiding plastic containers for heating or storing food, favoring glass or stainless steel instead. Although these measures seem effective, further research is needed to confirm their impact on reducing microplastics in the body.
Preliminary studies suggest that sweating could help eliminate some plastic compounds. However, the elimination mechanisms remain poorly understood, and scientists call for in-depth research to establish safe exposure limits.
To go further: What is the blood-brain barrier?
The blood-brain barrier is a protective structure that regulates exchanges between blood and the brain. Composed of tightly linked endothelial cells, it normally prevents harmful substances, pathogens, and toxins from entering brain tissue. It plays an essential role in maintaining the stable environment necessary for the proper functioning of neurons.
However, this barrier is not infallible. Some very small particles, such as nanoplastics (less than 200 nanometers), can cross it. Once in the brain, these particles accumulate and could disrupt brain functions, particularly by causing inflammation or interfering with immune cells specific to the nervous system.
The ability of nanoplastics to cross this barrier partly explains their high concentration in the brain. This discovery raises concerns about their potential role in the development of neurodegenerative diseases, such as dementia. Further research is needed to fully understand the mechanisms of action and long-term consequences.
Article author: Cédric DEPOND