Dr. Geewananda Gunawardana
Nanoparticles are tiny particles measuring between 1 and 100 nanometers across. You could fit roughly 800 to 1,000 standard nanoparticles side-by-side across the width of a single hair strand. If a nanoparticle were the size of a marble, the diameter of a human hair would be roughly the width of a full-sized basketball court. They are like viruses in size. For example, the SARS-CoV-2 is 100nm . Due to this incredibly small size, they can enter living cells very easily, just like the viruses.
Our environment is full of a variety of nanoparticles. However, as all living beings have evolved with them, they are used to them. Other than viruses, most of them do no harm, they have become part of us. There is a new development that has no historical parallel: Plastics.
Plastics were invented after the expansion of the petroleum industry in late 19th century. They are made of byproducts or waste of oil refinery process. The first commercially available plastics polyvinyl chloride – PVC, polystyrene, and polyethylene were introduced in the early 20th century. Plastics dominate modern manufacturing and daily life because they combine unmatched chemical versatility with extreme economic efficiency. Virtually no other single material class can be engineered across such a wide spectrum of physical properties while remaining so cheap to produce at scale.
Plastics are polymers, or long chains of small molecules assembled chemically. As a result, all plastics shed small particles readily. Wear and tear of plastic products increase this process. These particles are found throughout the globe and in all living things, from the bottom of the oceans to Antarctic iceshelf to human breast milk to brain tissues.
This poses a problem of unimaginable magnitude that living organisms have never faced in history. Nature is a web of cycles; we learn of the water and carbon cycle in school. Similarly, the cycling time may vary, but everything in the universe is recycled, stars and planets included. This dependency is explained in Buddhist concepts like Dependent Arising and impermanence.
The problem with plastic microparticles is that nature has not figured out how to recycle them in the short term. That has wide-ranging consequences. Environmental impact is plainly evident. I wish to highlight how microplastics can adversely impact human health.
To understand this, we must look at molecular biology. In living organisms, all the work is done by proteins. They are also polymers. Polymers of amino acids. They are like long chains that can be folded into specific shapes just as one can fold a rope into any shape. It is this specific shape that allows proteins to do their job. Biochemist called this function catalysis. Everything in the body ranging from digestion of food, generating energy, functioning the sensory organs, and motion are some examples. Depending on their function we call them enzymes, hormones, receptors, and transporters etc.
Let is keep in mind that the shape of the protein is the most fundamental requisite for its function. This is where the plastic microparticles and nanoparticles come into play and cause havoc. As the proteins and these particles are of the same size, they can cling to each other and change the shape of the flexible protein. Once its shape changes, the protein cannot carry out its function. This is the same principle used in medicine: an anticancer drug binds to the protein that causes cancer and stops the growth of cancer.
Since humanity’s encounter with plastics is short, definitive connections between diseases and plastics have not been established. However, biochemical evidence for a potential disaster is mounting. There is evidence that plastics can cause a variety of diseases:
1. Cardiovascular Diseases (Marfella et al., 2024)
Atherosclerosis and Arterial Plaque Instability: Clinical studies have detected micro- and nanoplastics within arterial plaque. Their presence correlates with higher rates of vascular inflammation, unstable plaque buildup, and elevated risk of heart attack or stroke.
2. Respiratory & Pulmonary Diseases (Atis et al., 2005, Song et al., 2022).
Nanoplastics settle in the airways and alveoli causing chronic airway Inflammation & asthma and chronic obstructive pulmonary disease (COPD). Inhaled particulates can trigger local hypersensitive immune responses and granulomatous inflammation.
3. Gastrointestinal & Metabolic Disorders (Yan et al., 2022, Agrawal et al., 2024).
Patients with Inflammatory Bowel Disease (IBD) such as Crohn’s disease or ulcerative colitis have been found to harbor higher fecal concentrations of microplastics. Particles can disrupt the intestinal mucosal barrier, altering gut permeability called “leaky gut” and promoting chronic low-grade inflammation.
Exposure to nanoplastics shifts the microflora balance, reducing beneficial bacteria and altering short-chain fatty acid production. Nanoplastics accumulating in the liver disrupt lipid metabolism, promoting cellular fat buildup, oxidative liver injury, and potential fibrosis, hepatic steatosis & non-alcoholic fatty liver.
4. Reproductive & Endocrine Dysfunction
Studies have detected nanoplastics in testicular tissue, semen, follicular fluid, and placenta. Exposure is linked to decreased sperm motility/count, hormonal imbalances, and disrupted oocyte maturation. Nanoplastics can translocate across the placental barrier, potentially triggering fetal neurodevelopmental or growth concerns.
5. Neurodegenerative Disorders
Nanoplastics are small enough to cross the blood-brain barrier. Recent mechanistic studies show that nanoplastics can bind with proteins promoting structural misfolding and aggregation, which are key hallmarks of neurodegenerative conditions like Parkinson’s and Alzheimer’s disease.
6. Immune & Oncological Risks
Persistent, non-degradable particles create chronic foreign-body reactions, forcing immune cells into a state of persistent inflammation. The combination of chronic physical tissue irritation, generation of reactive oxygen species (ROS), DNA damage, and long-term leaching of carcinogenic plasticizers increases risk of cancer.
That is only the tip of the iceberg. Humans have hundreds of thousands to millions of functional proteins, and as described earlier, nanoplstics can interfere with any of them and cause any number of ailments. That is a serious situation that we should not take lightly. Such protein function alteration is similar to the mechanism of evolution, and it is not farfetched to think that nanoplastics could even alter the evolutionary path.
Then the question is how we can avoid or reduce nanoplstics getting into our body. Avoiding or reducing use of plastics is the easiest way to reduce this menace. Plastic containers and wraps used for food and drinks are the worst culprits. For example, recent optical imaging studies reveal that a single liter of bottled water contains roughly 240,000 tiny plastic fragments. This particle shedding becomes worse when oily foods or hot foods and drinks come in contact with plastic containers.
Those concerned with plastic pollution in general, emphasize three Rs: Reduce, Reuse, and Recycle. With what science we know, the advice for reusing must be taken with caution: As plastic items age, their particle sheading increases. Therefore, it is not advisable to reuse plastic items that come into contact with food and drinks. We must seek alternate materials for such purposes. Let us not forget, plastic came to use in the recent past; before that, we lived just fine with non-plastic alternatives. It may sound as if we go backwards, but what is more important than our wellbeing.
Unfortunately, plastic recycling is a paradox. In addition to logistical, economic, and technical problems associated with recycling, turning one plastic item into another does not eliminate the nanoparticle hazard. It only shifts the problem. Therefore, reducing plastic use is the intelligent thing to do. For example, we Sri Lankans are very fond of sili-sili bags: roughly 150,000 to 20 million sili-sili shopping bags are used and discarded across the country every single day. In English, silly means foolish or unwise. That means we engage in a practice that is twice foolish and unwise when we carry our groceries in sili-sili bags. Let us think of alternatives, encourage sustainable industries, and take care of our own health.