X-ray of a human head showing the brain.
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As the production of plastic continues to increase, minuscule particles of this common polymer are being found virtually everywhere on Earth. Scientists have discovered microplastics in the deepest oceans, the clouds in the sky, and even inside our bodies.
Research from the University of New Mexico now indicates that these tiny fragments are accumulating in our brains more than in other organs. According to toxicologist Matthew Campen and his team, samples from kidneys and livers contained between seven and thirty times fewer microplastics compared to the brain.
The study, published in Nature Medicine, reveals that the levels of microplastics in the brain are increasing rapidly. Brain samples from 2024 contained 50% more microplastics than those from 2016, just eight years prior.
The team identified 12 different polymers in tissue samples taken from the frontal cortex of normal adult brains. Based on their findings, an average brain could contain 4,800 micrograms of microplastics per gram, equivalent to about 0.48% by weight — the same as an entire plastic spoon, as Campen explained to CNN.
Hunting Microplastics In The Body
Scientists at the university’s Health Sciences Center developed a method for measuring microplastics in biological tissue, which they have previously used to detect the material in human placentas and testes. For those with a sensitive stomach, it may be best to skip this section.
The researchers first dissolve each tissue sample and then subject the resulting slurry to a centrifuge to create concentrated pellets. These pellets are heated to 600 degrees Centigrade, and the gases they release are analyzed.
Examining samples with high plastic content under a microscope, the scientists found deposits of microplastics smaller than 200 nanometers, tiny enough to pass through the blood-brain barrier. However, the team is uncertain about how these particles enter the brain and why they accumulate there in such quantities.
They suspect that microplastics primarily enter our bodies through food, particularly meat, which was found to contain high levels of degraded polymers.
“The way we irrigate fields with plastic-contaminated water leads us to postulate that the plastics accumulate there,” Campen stated in a statement. “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 of the microplastics.”
Potential Harm From Microplastics
Researchers are still uncertain about the potential harm of these microplastics and are particularly concerned about the presence of plastic in the brains they examined.
They discovered that brains affected by dementia contained more microplastics than others. However, it is unclear whether the plastic influenced the disease or if it reflects dementia-related changes in brain blood flow.
Although plastic is generally considered inert and used in various medical applications such as artificial joints, the scientists are considering whether the physical presence of microplastics could pose a threat, rather than the chemicals they contain.
“We are beginning to consider that perhaps these plastics obstruct blood flow in capillaries,” Campen stated. “There is a potential for these nanomaterials to interfere with the connections between axons in the brain. They could also serve as a seed for the aggregation of proteins involved in dementia. We simply do not know.”
Further research will be required to determine if and how microplastics may harm individuals. For now, Campen hopes that this research raises awareness among consumers about the significant amount of plastic present in their brains. “I have yet to meet a single person who says, ‘I have a lot of plastic in my brain and I’m okay with that,'” he remarked.
