Plastic is all around us: your water bottle, makeup, car, and food packaging likely have at least some plastic components, but what about your dinner? Or the ocean? Or the air we all breathe? Well, microplastics have been found in all three; the question is how badly they are affecting us and what can be done about it. 

Microplastics Everywhere 

Where exactly are microplastics found? According to an analysis of 26 studies, bottled water has, on average, 94.37 particles per liter, 32.27 in beer, and 4.24 in tap water. Even the air we breathe contains 9.80 particles per cubic meter. All these particles add up, meaning the average person unknowingly consumes between 78,000 and 211,000 microplastic particles annually.

While that concerningly high number does vary depending on where you live and what you eat, drink, or inhale, there is clearly a problem.  Microplastics are infiltrating nearly every aspect of our environment, raising questions about their potential impact on human health over time. Research is ongoing as to how exactly the cumulative effect of this exposure is affecting human health, but the sheer scale of the problem and the nature of microscopic particles that may never fully break down is a really complex challenge. 

The Blood-Brain Barrier Problem 

The blood-brain barrier (BBB)is a selective semi-permeable membrane between the blood vessels that supply your brain and the surrounding tissue; it regulates what can and can’t leave the blood vessel and makes its way into your brain. Generally, only small, positively charged molecules like H20 can cross this barrier, keeping your brain safe from toxic substances and pathogens.   

Like any other body system, the BBB is not flawless. In a study from 2023, nanometer-sized polystyrene particles passed through the BBB in mice within two hours of ingestion, while larger particles did not. Molecular simulations revealed that cholesterol molecules on the nanoplastic’s surface (biomolecular corona) enhanced its integration into the BBB membrane, allowing it to pass. In contrast, a protein-based corona inhibited this movement. These findings suggest that surface coatings on nanoplastics significantly influence their ability to cross the BBB and potentially reach brain tissue.

Microplastics in Brain Tissue 

Aside from crossing the BBB, a recent study published in JAMA Network Open has found that microplastics can enter the brain via the nasal cavity, ending up in the olfactory bulb. “Previous studies in humans and animals have shown that air pollution reaches the brain and that particles have been found in the olfactory bulb, which is why we think the olfactory bulb is probably one of the first points for microplastics to reach the brain,” said lead study author Dr. Thais Mauad, an Associate Professor of Pathology at the University of São Paulo Medical School in Brazil.’ 

The study reveals that microplastics can reach the olfactory bulb in the human brain, indicating the olfactory pathway as a potential entry route. After examining the olfactory bulbs of 15 deceased individuals, researchers found microplastics in over half of the cases, with polypropylene as the most common polymer. Microplastics entered the brain through nasal passages, bypassing the blood-brain barrier—a previously assumed defense. 

The Effects: Researching Risk 

Okay, so microplastics can enter the olfactory bulb through the nasal cavity and potentially cross the BBB in some forms, but how pervasive is the problem? And what specific dangers does it pose to your health? 

A team at the Ryan Institute for Neuroscience decided to assess the effects of short-term microplastic exposure on mice. They found that microplastics could cross the blood-brain barrier, bioaccumulate in organs, and even induce dementia-like behaviors. At the same time, exposed mice showed reduced levels of GFAP, a protein linked to neurodegenerative disorders. The findings raise concerns about potential neurological risks of microplastic exposure, particularly as we age, and suggest further research is needed.

Another study looked at the health risks associated with microplastic exposure across multiple body systems, primarily due to ingestion and inhalation. We know that microplastics can accumulate in the digestive tract, causing physical irritation, inflammation, and microbiota imbalance, which can lead to gastrointestinal symptoms like bloating and pain. 

Outside of the gut, the study highlighted how inhaled microplastics may lead to respiratory symptoms, oxidative stress, and inflammation in lung tissue, potentially contributing to chronic respiratory conditions. Microplastics ingested in either manner may disrupt hormonal balance, pose risks to reproductive health, and trigger immune responses, with evidence of immune activation in human lung cells. Animal models show that microplastics can enter the central nervous system, induce neurotoxicity, and contribute to cognitive and locomotor issues, which concurs with the olfactory bulb study. 

The United Nations has linked microplastic consumption to endocrine disruption, weight gain, insulin resistance, decreased reproductive health, and cancer. Yet they admit further research is needed to fully understand how microplastics cause health problems. 

Living with Microplastics 

The aforementioned studies, such as the University of São Paulos, which found microplastics in the olfactory bulb, are a good step forward but represent a few small-scale studies into a complex issue that has only recently begun to attract widespread attention, much more research is needed to fully understand how and where microplastics affect us. 

Solving this problem will require collaboration from healthcare workers and researchers across the board, and it is crucial that the next generation understand the effect microplastics can have. We need to understand better how microplastics affect the human body so anyone, from nurses training through NP programs online to doctors, can effectively treat related health problems. 

Reducing the Risk

It might seem impossible to avoid these pervasive particles, but there are a few things you can do to reduce your exposure and that of your family. The experts recommend avoiding plastic-packaged food, using glass or metal storage, and opting for fresh foods over processed ones, which often have plastic additives. 

Try filtering your drinking water, as tap water can contain microplastics, and certain small particle filters can get many of them out. Avoid heating food in plastic containers, which releases more microplastics. Reduce your use of synthetic clothing and choose natural fibers like cotton. Lastly, keep your home clean to reduce plastic dust particles. Even trying a few of these changes can help minimize daily exposure and reduce potential health risks.

At the end of the day, plastics are such an ingrained part of our society and are here for good; the question is, how can we adapt to stop releasing progressively smaller particles into our environment? Once we understand how they affect the human body, can we remove them or stop them from entering in the first place? With the brightest minds in the world turned to the task rest assured, there will be solutions.