Microplastics have now been found in the human brain, accumulating over time to about a spoonful and potentially more, according to a recent study.
The study published Monday in Nature Medicine found high concentrations of microplastics in human brains—higher than in any other organ—raising questions about their potential role in neurological diseases.
The research out of the University of New Mexico Health Sciences (UNM) found that plastic accumulation in the brain has surged by 50 per cent over the past eight years, with dementia patients showing up to 10 times the plastic levels compared to others.
“We start thinking that maybe these plastics obstruct blood flow in capillaries,” lead author and toxicologist Matthew Campen said in a media release.
“There’s the potential that these nanomaterials interfere with the connections between axons in the brain. They could also be a seed for aggregation of proteins involved in dementia. We just don’t know.”
Microplastics are tiny plastic particles, typically five millimetres or smaller, that break away from larger plastics in the environment.
Nanoplastics are even tinier — so small that they are invisible to the naked eye, explained Erica Cirino, communications manager at Plastic Pollution Coalition and author of Thicker Than Water: The Quest for Solutions to the Plastic Crisis.
And they are everywhere, she said — in our food, drinking water and oceans.
She said that while the discovery of plastic in the brain is certainly shocking, it is unfortunately not surprising.
“The brain appears to be a major accumulation zone for plastic, including microplastics and nanoplastics,” Cirino said.
“But knowing that perhaps more than any other organ, the brain is an accumulation of these particles is very concerning. The brain is the powerhouse of our bodies in many ways.”
Previous research has found microplastics in other parts of the human body, including the kidneys, liver and testes, as well as in placenta.
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And more studies are revealing the health effects of microplastics, including links to heart disease, stroke, reproductive issues, erectile dysfunction and even death. Recent research in mice also suggests a potential connection to neurodegenerative diseases such as Alzheimer’s, Parkinson’s and ALS.
For this study, the UNM team looked at brain tissue samples donated by the New Mexico Office of the Medical Investigator, which is required by law to keep autopsy tissue for seven years before disposal.
The older samples, dating back to 2016 on average, were compared with tissue collected in 2024.
All the samples were taken from the frontal cortex, the area of the brain located just above and behind the eyes, Campen said.
The researchers identified 12 different types of plastics in the brain tissue. The most common polymer they found was polyethylene, which is widely used in everyday items such as packaging, bottles and cups.
They also discovered clusters of tiny plastic fragments as small as 200 nanometers or smaller—about the size of viruses.
These tiny plastic pieces are small enough to potentially pass through the blood-brain barrier, a protective layer that usually prevents harmful substances from entering the brain, the researchers said.
They found significantly higher levels of microplastics in the 2024 brain tissue compared to the 2016 samples, regardless of the patient’s age, sex, race, ethnicity or cause of death.
Campen told CNN on Monday that the concentrations found in the brain tissue of normal individuals, with an average age of around 45 to 50 years, were 4,800 micrograms per gram.
“That’s equivalent to an entire standard plastic spoon,” Campen said.
Although the researchers found plastic in the brain, they are still unsure of the exact method by which these particles are transported to the brain.
Campen suspects that most of the microplastics in the body are ingested through food, particularly meat because commercial meat production tends to concentrate plastics in the food chain.
“The way we irrigate fields with plastic-contaminated water, we postulate that the plastics build up there,” Campen said. “We feed those crops to our livestock. We take the manure and put it back on the field, so there may be a sort of feed-forward biomagnification.”
The researchers said the findings should give rise to alarm about a global threat to human health.
“I have yet to encounter a single human being who says, ‘There’s a bunch of plastic in my brain and I’m totally cool with that’,” Campen said.
Cirino said that while microplastics are widespread, you can still limit your exposure by examining and changing some of your household items.
“So instead of drinking out of plastic water bottles, opt for stainless steel, ceramic or glass vessels. That’s a really simple swap,” she said.
“Carry reusable canvas bags when you go shopping at the store, try to buy loose fruits and vegetables and other foods in bulk rather than in single plastic containers. When you go look for clothing, it’s always great to shop secondhand because you’re reducing waste.”
She recommended making one change at a time, noting that as long as you’re reducing the plastic around you, you’ll lower your inhalation, ingestion and overall exposure to plastic particles.
— With files from Global News’ Saba Aziz
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