Study finds alarming levels of microplastics in the brain
Microplastics, plastic particles less than 5 millimeters in size, have been infiltrating the environment at an alarming rate as global plastic use increases. Levels of microplastics in the environment have skyrocketed in recent decades, with current production of more than 300 million tons of plastic per year and about 2.5 million tons floating in the world's oceans in 2023, more than ten times the 2005 levels.
A new study published in Nature Medicine concluded that microplastics and nanoplastics (which are even smaller in size, from 1 to 1,000 nanometers) accumulate at higher levels in the human brain than in the liver and kidneys. The study also found significantly higher concentrations of microplastics and nanoplastics in 2024 samples compared to 2016 samples, and higher levels in the brains of people diagnosed with dementia.
Although the study does not establish a cause-and-effect relationship between these plastic particles and dementia, it raises questions about the potential health consequences of plastic exposure. Although the scientific community knows these plastics are present in our bodies, it is unclear how they affect our health.
"We believe this is simply a reflection of environmental accumulation and exposure," says the study's author, Matthew Campen , professor of pharmaceutical sciences at the University of New Mexico (United States), says, "People are exposed to increasing levels of microplastics and nanoplastics."
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This image shows a breach in the blood-brain barrier. A fluorescent tracer (red) has been injected into the blood and is leaking from the lower right blood vessel (round) into the surrounding brain tissue. If this barrier is breached, due to injury or disease, it can cause the surrounding tissue to die.
Plastic pollution is growing exponentially
Microplastics and nanoplastics (MNPs) can be invisible to the naked eye and come from larger plastic products (such as soft drink bottles, shopping bags, and polystyrene containers) that break down in the environment.
The scientific community has been studying MNPs in the oceans since the 1970s. It has been discovered that marine animals They have microplastics in their bodies , absorbed from water and from eating. contaminated fish . Microplastics also accumulate in the tissues of other animals that we eat, such as pigs, cows and chickens.
MNPs can also end up in the air: the indoor air It tends to contain more MNP than outside air, due to the shedding of particles from plastics in clothing, furniture, and household products.
After inhaling these particles, they can travel through the body and end up in various organs. Numerous studies have found PNM in human lungs , placentas , blood vessels and bone marrow .
A study A 2024 study found evidence that MNPs are even able to cross the blood-brain barrier, a selective filter that controls what can enter the brain from the bloodstream. While it was previously thought that only the smallest nanoplastics could cross this barrier, this study found that larger microplastics can also enter the brain.
(Related: Microplastics have reached virtually every corner of the planet )
Microplastics and nanoplastics in the brain
The study, published this week, confirms the presence of nanoparticles in the brain, and at alarming levels.
The study examined 52 human brain samples from 2016 to 2024, all taken from the frontal cortex, the part of the brain responsible for judgment, decision-making, and muscle movement. The researchers also examined liver and kidney samples from the same bodies, analyzing all tissues using microscopic imaging and molecular analysis to identify their chemical composition.
Brain and liver samples from 2024 had significantly higher concentrations of MNPs than those from 2016. The total mass of plastics in the brains studied increased by about 50 percent between 2016 and 2024, and the researchers suggest that the dramatic increase in MNP concentrations in our homes, air and water could be the culprit.
“I am quite surprised by the amount of microplastics they found,” she says. Emma Kasteel , a neurotoxicologist at Utrecht University in the Netherlands, adds, “It was much older than I would have expected.”
Rising levels of microplastics in the environment are reflected in the new findings, Kasteel says, and increased exposure is likely causing more plastic particles in organs.
Overall, brain samples had between 7 and 30 times more NMP than liver and kidney samples. The particles found in the brain were mostly small fragments or flakes of polyethylene, one of the most common plastics in the world, often used in packaging.
According to Kasteel, it's logical that MNPs accumulate more in the brain than in other organs. Inhalation through the nose into what's called the olfactory bulb, the part of the brain that processes smell, gives airborne MNPs a more direct route to the brain than to other organs.
Campen notes that a person's age was not associated with the amount of plastic in their organs, meaning the body eliminates plastic somehow; otherwise, older people's organs would continue to accumulate more and more plastic over the years.
Another notable finding was that MNP levels were three to five times higher in 12 brains of people diagnosed with dementia. The researchers clarify that this doesn't necessarily mean that MNPs cause dementia, but it does show an association that deserves further study.
Kasteel says the link is likely because the blood-brain barriers of people with dementia don't work as well as a filter as they do in healthy individuals, meaning the high concentration of MNPs could be a consequence of dementia rather than a cause.
Unclear health effects and preventive solutions
Although the scientific community still does not fully understand the health effects of nanoparticles on the brain, further research is needed to better understand whether they are harmful. Some studies have shown that the presence of nanoparticles in arteries may be a risk factor of cardiovascular diseases, and that stomach cancer cells can spread more quickly after coming into contact with nanoparticles.
“More and more studies are showing that plastics are present in the brain, including this new one, and they shouldn't be there,” says Kasteel. “We don't know much about the health effects, but the fact is that they're there and they shouldn't be, and perhaps that's worrying enough.”
Campen's research team wants to analyze the brain as a whole to determine if there is more plastic accumulation in a specific area and whether this is related to any specific health outcomes.
(Related: Plastic figures in Spain )
While there's no way to completely avoid plastic exposure, Kasteel says there are small personal choices you can make: minimizing single-use plastics, keeping your home well ventilated and vacuuming regularly to remove dust and plastic debris, and avoiding cosmetics that intentionally add MNPs, such as exfoliants with plastic beads.
Scientists are also developing solutions to reduce microplastics in the environment. a type of worm that eats polystyrene, and fungus and microbes that break down plastics in the environment. Work is also underway on new types of filters to remove MNP from drinking water.
“Plastic is everywhere. Most people can't imagine a world without plastic... even if we stopped producing plastic right now, the world would still be full of microplastics,” says Kasteel. “So it's good to think about mitigation measures, applying the precautionary principle, and see what we can do to minimize exposure, to perhaps prevent certain health risks.”