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Microplastics have become an unavoidable part of our daily life, embedded in packaging and clothing, and found in our oceans, in the air we breathe, and in the water we drink. But in recent years, scientists and clinicians started exploring a new question: Could these invisible fragments also be making their way into our brains, and if so, what might that mean for our mental health?
To explore what we know and what we still don’t, I spoke with Dr. Elizabeth Ryznar, a psychiatrist and a planetary health expert focusing on microplastics’ impact on our mental health. In our conversation, she explains how microplastics enter the body, what scientists are discovering about their effects on brain and mental health, and the steps we can take, both individually and collectively, to protect ourselves.
Burcin Ikiz (BI): What first drew you, as a psychiatrist, to the issue of plastics and brain health?
Elizabeth Ryznar (ER): For a long time, I thought of plastics as an environmental problem, hurting oceans, not humans. During the early pandemic, when my usual routines stalled, I started preparing all of my own meals at home and going on hikes for fun. I noticed how much plastic piled up as trash in my kitchen or as litter on the hiking trails. That made the issue personal, and I spent three years changing my own habits to be low-plastic. I also took a class on plastics, where I learned about medical studies showing health impacts. Almost no one was discussing possible brain effects at the time, and as a psychiatrist, I felt it was an important gap to explore. Since then, the science has accelerated: the first reports of microplastics in human blood appeared in 2022, and findings in the human brain were reported at the end of 2024.
BI: Let’s define terms. What are microplastics and nanoplastics, and where do they come from?
ER: Plastics don’t dissolve into naturally reusable parts; they fragment into smaller and smaller pieces of plastic. Pieces smaller than 5 millimeters are called microplastics, and fragments less than 1 micrometer are called nanoplastics. When we talk about nanoplastics, we are talking about something that’s the size of a particle of smoke, a virus, or a protein. Micro- and nanoplastics come from daily life: food and drinks stored or heated in plastic, ultraprocessed foods made in factories with plastic equipment, synthetic clothing that sheds microfibers in the wash, and tire wear particles from driving. They can also be added as microbeads in cosmetics and personal care products. Because plastic waste is everywhere — in the air, water, and soil —these particles also enter our food chain (think sea salt, shellfish, fish) and our water supply. In short, they’re a form of pollution we inhale and ingest.
BI: How do these particles get into the brain if we have the blood–brain barrier?
ER: The blood–brain barrier isn’t a solid wall; it’s a semipermeable membrane. The smallest microplastics and all nanoplastics are small enough to pass through once they are in our bloodstream, and they can get there from our lungs or GI tract. There’s also evidence for a direct route to the brain from the nose: the olfactory nerves carry scents into the brain, and tiny pollution particles, including microplastics, appear able to travel along that same pathway.
BI: What might micro- and nanoplastics do once they’re in brain tissue?
ER: These particles can trigger inflammation and oxidative stress. They can also alter gene expression, activate microglial cells, and accelerate alpha-synuclein or amyloid aggregation (which are seen in Parkinson’s and Alzheimer’s disease). Some studies also show changes in rodent behavior or cognition. This is all based on studies of brain cells or animal models, so the research is still preliminary, but the mechanisms we’re observing are concerning.
BI: It isn’t just the particles that harm us. What about chemicals associated with plastics?
ER: Exactly. Plastic products aren’t just the plastic polymer (i.e., particle). They also contain additives to achieve durability (bisphenols like BPA), flexibility (phthalates), oil/water resistance (PFAS “forever chemicals”), or fire prevention (flame retardants). Many of these are endocrine-disrupting chemicals, meaning they can mimic or interfere with hormones that regulate growth, reproduction, metabolism, and brain development. We have decades of research linking certain additives to outcomes like altered puberty timing, reduced sperm counts, metabolic disease, and, in the case of older flame-retardants (PBDEs), loss of IQ in children. For brain and mental health, emerging studies suggest possible links to behavioral and neurodevelopmental outcomes. The results are mixed, and genetics may modify the risk. This is an active area of research.
BI: What practical steps can individuals take to reduce exposure?
ER: Focus on food, water, air, dust, and textiles:
- Avoid heating food in plastic; use glass or ceramic. Be cautious with hot liquids and plastics, including some tea bags.
- For storing food and drinks, incorporate stainless steel or glass bottles and containers.
- Reduce indoor dust (mop/vacuum regularly) and consider HEPA filtration.
- For children, opt for non-plastic toys, especially those that are put in their mouths.
- Opt for clothing made of natural fibers or materials that will last a long time; consider thrifting.
However, I also suggest that people consider reducing the amount of micro- and nanoplastics they release into the environment, as these eventually make their way back to you and your family. Reducing plastic use is by far the most important thing people can do. Most plastic items that we use end up in landfills, are burned, or littered. Recycling is helpful, but many plastics cannot be recycled. Think “refuse, reduce, or reuse” first; recycle last.
BI: What about bigger, systemic solutions?
ER: Personal choices matter, but the scale of this problem requires policy and industry action. That means curbing unnecessary single-use plastics and capping overall production growth, while also investing in safer materials and reformulating additives to avoid endocrine disruptors. Setting standards for microfiber filtration in washing machines and for tire-wear particles would make a major difference, as would procurement changes in hospitals, schools, and cities to reduce plastic waste at the source. Clearer labeling and greater transparency are also essential so that consumers and clinicians can make informed choices. Finally, civic engagement truly works; asking local, state, and national representatives what they’re doing about plastics and health helps build the political will needed to act.
BI: Where do you find hope?
ER: In human creativity and cooperation. Innovators are developing safer materials, better capture technologies, and circular reuse systems. Healthcare organizations are moving toward sustainable practices. And as more people understand the health dimensions of plastics, momentum grows. We can’t eliminate plastics entirely—they are useful in many settings—but we can eliminate excessive and unnecessary use.
BI: Thank you for your time and for sharing your insights, Elizabeth.
Plastics are both a personal and planetary issue, one that connects environmental health to brain health in ways we’re only beginning to understand. While the science is still unfolding, Dr. Ryznar’s message is clear: Awareness is the first step toward action, and even small choices, from the products we buy to the policies we support, can help reduce this hidden burden on our minds and on the planet.
About the Expert
Elizabeth Ryznar, MD, MSc is a board-certified psychiatrist and the Associate Chair of Psychiatry at St.George’s University. She is also an advisory board member for the Physician and Scientist Network Addressing Plastics and Health (PSNAP).
