Plastic pollution is one of the most pressing environmental issues facing the world today. Every year, billions of tons of plastic waste break down into microscopic particles, known as microplastics. These particles, which have been found in every corner of the planet, are increasingly entering the human body, accumulating in various organs, including the brain, and causing serious health problems.
Against this background, a study conducted by scientists at the NICM Health Research Institute, Western Sydney University and University of Technology Sydney (UTS) indicates that microplastics may directly contribute to the exacerbation of neurodegenerative diseases, including Alzheimer’s and Parkinson’s.
Globally, over 57 million people live with dementia, and with a sharp increase in these diseases being on the horizon, the new research, published in the journal Molecular and Cellular Biochemistry, regards the potential accumulation of microplastics in the brain as a major public health threat.
Sources of microplastics are diverse, including contaminated seafood, salt, processed foods, plastic bottles, and tea bags, as well as plastic fibers released from synthetic fabrics. As part of the study, scientists identified the specific mechanisms by which microplastics manage to damage the brain’s Blood-Brain Barrier (BBB) and stimulate inflammatory processes.
Medscriptum prepared an exclusive interview with the leading scientists of this large-scale study, whose work provides a broad picture of microplastic accumulation in the body and the increased risks of health problems.
Dr. Keshav Raj Paudel, a Senior Research Fellow associated with the Woolcock Institute of Medical Research in addition to the University of Technology Sydney, specializes in studying the molecular mechanisms of chronic respiratory diseases and environmental pollutants (including microplastics). Actively involved in the project alongside him was Professor Kamal Dua, from the Discipline of Pharmacy at the University of Technology Sydney (UTS), NICM Health Research Institute and Western Sydney University.
The professors speak in detail about how microplastics enter and accumulate in the human body, and what specific dangers chronic plastic-induced inflammation poses to our health.
What are the main research directions your group is currently working on, and what determines the relevance of these topics?
Our research activities are developing in two key directions. One already completed phase focused on the impact of inhaled microplastics on lung tissue, where we studied the mechanisms of particle accumulation and damage at the cellular level. Currently, we are working on the link between microplastics and neurodegenerative diseases, specifically the pathogenesis of Alzheimer’s and Parkinson’s diseases.
The relevance of this issue is driven by the fact that microplastics, as it turns out, remain and accumulate in various parts of the human body, creating a chronic, long-term health risk that we are only now beginning to fully comprehend.
How much plastic does an average person ingest, and what are the main sources?
The data is truly alarming, and the figures we have obtained indicate a huge scale. Global estimates suggest that people potentially ingest 11,845 to 193,200 microplastic particles annually. This is equivalent to an annual intake of 7.7 grams to 287 grams of mass. In the most striking analogy, approximately 5 grams of plastic, the weight of one credit card, enters our bodies in a single week.
If this trend continues, this figure amounts to up to 20 kilograms over our lifetime, which is equivalent to two average-sized trash bins. The largest source of microplastics is drinking water, but it is also widely present in seafood, table salt, and other products.
Can you name everyday sources through which plastic enters our bodies?
The sources are indeed diverse and often unnoticed. We ingest plastic from household items such as plastic cutting boards or plastic kettles. For example, when boiling water in a plastic kettle, the high temperature causes plastic particles to be released, which then mix with tea or coffee.
Attention should also be paid to pharmaceutical products: many medications are stored in plastic containers, and even the outer coating of some tablets may contain small amounts of plastic. These factors are not often considered, but they significantly increase chronic exposure.
What are the main cellular mechanisms by which microplastics damage tissues after entering the body?
Once microplastics enter the cell, a cascade of damage begins. The primary and most important mechanism is oxidative stress, where the level of reactive oxygen species (ROS) increases, disrupting the cell’s balance and leading to lipid peroxidation. This stress causes damage to the cell that triggers apoptosis (programmed cell death).
In addition, microplastics contribute to mitochondrial dysfunction; mitochondria, which are the cell’s main energy source (ATP), are damaged, critically weakening the vital functions of the tissue. This damage, in turn, is always followed by a secondary inflammatory reaction, as the immune system attempts to clear the damaged tissue.
What specifically did your study show regarding the consequences of microplastic accumulation in the lungs, and how does this harm the respiratory system?
Inhaled plastic in the lungs causes dual damage. The smallest particles are deposited on the cell surface, acting as a kind of coating, thereby disrupting the connections between cells and the integrity of the cell itself.
Experiments conducted on mice showed that 8 weeks of exposure (approximately 15 years of human life) is enough for a significant amount of plastic to be deposited in the lungs and cause a chronic inflammatory process. In this process, macrophages, the immune cells, engulf the microplastics, and it is this activity that triggers large-scale inflammation. As a result of excessive plastic accumulation, phlegm forms in the lung, leading to the obstruction of the bronchioles and bronchi, which, in turn, exacerbates chronic diseases such as Chronic Obstructive and Restrictive Pulmonary Diseases.
What risks does microplastic exposure create for people with chronic respiratory diseases and vulnerable groups?
For individuals who already have asthma or other chronic lung diseases, microplastic exposure causes even greater harm because an inflammatory background already exists, and microplastics exacerbate this condition.
Special attention must be paid to vulnerable groups such as infants, pregnant women, the elderly, or those who are immunocompromised for other reasons. While a healthy immune system can eliminate a certain dose of plastic, the problem of accumulation is significantly more serious for these groups, increasing the risk of developing chronic health problems.
How do microplastics manage to enter the brain, and what is their effect on the blood-brain barrier?
The issue of penetration into the brain is critically important because it requires bypassing defensive mechanisms. The smallest fragments of microplastics that enter the bloodstream have been found in every tissue because they can cross the Blood-Brain Barrier (BBB). This barrier, which is the brain’s protective mechanism, is damaged.
Studies have shown that the particle size is crucial: particles of 0.2 size cause significantly more permeability than 1.0 particles. Microplastics can use various mechanisms, including transcytosis (transport through the cell) and phagocytosis, allowing them to deposit in the brain parenchyma.
What cellular and molecular damage occurs in the brain as a result of microplastic exposure?
After depositing in the brain tissue, microplastics cause an inflammatory process. This is a multi-factorial pathology that collectively damages tissues, neurons, and the connections between neurons. The damage process includes:
- Oxidative stress, which damages cells at the mitochondrial level.
- This is followed by mitochondrial dysfunction, which is critically important because mitochondria are the main energy source for neurons.
- Finally, the inflammatory process damages the synapses, or the connections between neurons, which are responsible for thought and all cognitive functions.
How does the accumulation of microplastics increase the risk of developing neurodegenerative diseases?
The problem of neurodegenerative diseases, such as Alzheimer’s and Parkinson’s, is already growing, caused by aging and various chronic illnesses. Our research suggests that microplastics contribute to these processes.
Chronic neuro-inflammation and oxidative stress caused by microplastics are the primary mechanisms that act as a catalyst for accelerating existing neurodegenerative problems. Damage to the connections between neurons is directly linked to neurodegenerative processes. Consequently, the accumulation of plastic presents a new, serious risk factor for the development of neurodegenerative diseases.
What practical steps and industrial changes are needed to reduce plastic exposure, and what are your future plans?
Reducing the global spread of plastic requires changes at both the individual and industrial levels. At the individual level, it is essential to replace plastic-containing items: we should use biodegradable options. For example, plastic containers, cutting boards, and utensils should be replaced with products made from wood, stainless steel, or glass.
At the industrial level, the enhancement of plastic recycling will play a huge role. Also, the introduction of technological innovations, such as washing machine filters, is critical, as washing machines release millions of microplastics into the environment.
What are your future plans in this direction, and what kind of support do you need to continue your research?
Our main future plan is to continue the ongoing research investigating the impact of microplastics on brain damage and cognition. This research continues in collaboration with American scientists, and our goal is to fully decipher these pathological mechanisms to establish specific cause-and-effect relationships and develop preventive measures. This is a fundamental and large-scale scientific project that requires significant financial resources. Accordingly, we are currently actively seeking sponsors and funding to continue and expand these studies.
