Plastic pollution is no longer an issue affecting only oceans, soil, or the air. A recent scientific study found microplastics and nanoplastics inside the human brain, which has made scientists wonder about how these tiny particles enter the body and what this could mean for our health in the long term.
Although the results of the study might seem worrying, researchers point out that there are still many doubts to answer. So, let’s find out more about this study.
The study
The research was published in Nature Medicine and scientists analyzed brain tissue from 52 people who died. They compared the amount of plastic on the brain with the one in other organs, like the liver or kidneys, and they found that the brain had higher levels of plastic, in some cases up to 30 times more than other organs. To identify plastic particles scientists used a precise method called pyrolysis gas chromatography mass spectrometry along with advanced imaging techniques.
Brain samples were taken from the frontal cortex, an area responsible for thinking and decision-making. The results showed that brain tissue contained roughly seven to thirty times more microplastics and nanoplastics than the other organs studied.
According to the main author of the study, Matthew Campen, the average amount of plastic found in a brain sample was similar to the weight of a small plastic spoon.
Types of particles found in the brain
Most of the particles found were extremely small, they were nanoscale fragments, usually between 100 and 200 nanometers long. Instead of smooth shapes, they appeared as irregular shards and flakes embedded in brain tissue.
The most common plastic found was polyethylene, a material frequently used in plastic bags, food packaging, and bottles. In the brain, polyethylene represents about three quarters of the plastic found, which is a higher number of what’s found in the liver or kidneys.
Through electron microscopes, scientists saw dense concentrations of plastic fragments along blood vessel walls and near immune cells. These concentrations were especially noticeable in brain samples from individuals who had dementia.
Dementia and blood-brain barrier
The fact that they found more plastic in brains with dementia concerned them about a possible relation between microplastics and the disease. People diagnosed with dementia have significantly higher levels of plastic in the frontal cortex in comparison with people of similar age who didn’t suffer from dementia.
However, researchers highlight that this doesn’t prove a direct cause. Dementia damages the blood-brain barrier, which is the protective filter that controls which substances enter the brain. What’s more, it can slow the body’s ability to remove waste. So, this can lead scientists to think that higher plastic levels could be a result of the disease rather than its cause.
Why plastic levels are increasing
The study also compared organ samples collected in 2016 with others from 2024, and it was found that the most recent brains and livers contained more plastic than older samples.
The striking thing is that these levels weren’t related to age, sex, race, or cause of death. This suggests that internal levels appear to reflect recent environmental exposure as global plastic production continues to increase, so exposure in everyday life may also be rising.
How can microplastics reach the brain?
The human brain is protected by the blood-brain barrier, which blocks many damaging substances. Scientists believe these smaller plastic fragments could enter the brain to interact with dietary fats, which can cross the protective barrier and may carry nanoplastics with them.
Matthew Campen compared the process to grease sticking to plastic food containers. In this idea, nanoplastics could travel together with lipids into brain tissue, but researchers emphasize that the exact mechanisms are still uncertain and require further investigation.
Effects on health
Microplastics have already been detected in many parts of the human body, including blood, placenta, arteries, testes, and heart tissue. Some studies have related this to inflammation, cardiovascular problems, and reduced sperm counts. Also, experiments with animals indicated that extremely high doses of microplastics may affect organ function.
At the same time, scientists and clinicians stress that real-world exposure levels and long-term health effects are still being studied. Measurement methods are continuing to improve, and current estimates contain some uncertainty. Because of this, researchers caution against drawing strong conclusions too early.
So…
For now, the findings serve as a reminder that rising environmental plastic pollution is reflected inside the human body. Understanding how microplastics move through the body and how they may affect health will remain an important focus for scientific research in the years ahead.