Plastics Have Infiltrated the Human Brain
A February 2025 study indicated there may be far more plastics in human brains than previously thought — as much as a plastic spoon! — raising the alarm on this issue.
What are microplastics and nanoplastics?
Plastic waste never disappears; it just breaks up into smaller and smaller pieces.
Microplastics are shards of plastic that are between 1 micrometer and 5 millimeters.
Nanoplastics are smaller than 1 micron. These are the particles that can most easily enter the brain.
How can micro- and nanoplastics affect the human body?
Micro- and nanoplastics may impact our health in two key ways:
Physical presence in the body can cause damage and inflammation.
Chemicals from the original plastic, or pollutants picked up in the environment, can leach into our organ tissues and cause damage.
How do micro- and nanoplastics enter the brain?
Micro- and nanoplastics enter through our mouth, nose, or skin. From there, they can travel via the bloodstream to any organ in the body, including the brain.
The brain is typically protected from harmful substances in the blood by the blood-brain barrier. However, studies have found that smaller nanoplastics can pass through it, and the presence of certain plastics can even weaken this barrier, leaving the brain more susceptible to infiltration.
Fig. 2: Visualization of putative plastics in the brain. Images courtesy of Nature Medicine (Nat Med) ISSN 1546-170X (online) ISSN 1078-8956 (print)
What happens when micro- and nanoplastics enter the brain?
This is an ongoing area of research and the exact effects likely depend on the size, shape, and type of microplastic; but early studies, mostly done in animals, have raised concerns that micro- and nanoplastics may:
Kill brain cells, disrupt the brain’s immune system, and promote the buildup of harmful proteins linked to neurodegenerative diseases like Alzheimer’s and Parkinson’s;
Impact how the brain develops, increasing the risk of neurodevelopmental disorders; and
Change the chemical signals sent between neurons and even increase some anxiety and depression-like behaviors in animals.
Why does this matter?
The brain is a very sensitive organ, is still developing into our mid-20’s, and contains many cells that aren’t able to regenerate after damage.
One study found that microplastic levels in human brains were nearly 50% higher in 2024 compared to those found in 2016. With plastic production expected to triple by 2060, the risk to our health will continue to rise unless action is taken.
What You Can Do
Start by reducing your exposure to micro- and nanoplastics in your daily life. Click here for our suggestions.
We hope you’ll also get involved in reducing plastics in your town, county, state, and beyond. Consider taking our free, virtual, two-hour-long grassroots advocacy training to learn how to tackle plastic pollution in your area. Learn more and register for the next session.
