Invisible Invaders – How Microplastics and Nanoplastics Threaten Human Health

Plastics play an undeniably important role in human life. It gained immense popularity in the last few decades due to its cost-effectiveness, light weight, durability and resistance to corrosion and chemicals. Although it was believed that plastics are resistant to degradation, evidence suggests that breakdown of plastics occur due to chemical, biological and mechanical processes – resulting in the fragmentation of plastics into micro and nano plastic particles. Microplastics—tiny plastic particles less than 5mm in size—have become an increasing concern due to their pervasive presence in the environment and potential health effects. Even more concerning are nanoplastics (particles smaller than 1 micrometer), which can more easily penetrate biological tissues and cross critical barriers like the blood-brain barrier and the placental barrier. Found in food, water, air, and consumer products, these particles pose risks to human health, particularly for older adults who may have heightened vulnerabilities. A recent article showed that fat cells exposed to microplastics show accelerated aging.

Seafood, salt, bottled water, and processed foods often contain microplastics. A 2024 study detected microplastics in 99% (or 180 out of 182) of samples of seafood tested. Most of the particles originated from clothing or textile fibers. Another recent study showed that a liter of bottled water contained about 240,000 tiny pieces of plastic – 90% of which were nanoplastic particles. Levels of micro and nanoplastics that are detected in food and water have also increased over the years. This is in part due to continuous and unregulated use of plastic in various industries, as well as improved measurement methods.

Airborne microplastics and nanoplastics are present in household dust and urban environments. Studies have detected polymer-based particulates in lung tissues, suggesting potential respiratory risks. Some medical implants, drug coatings, and packaging materials introduce microplastics into the body. However, their long-term risks to human health are not well understood. Another potential exposure scenario includes personal care products - Skincare, cosmetics, and toothpaste which may contain microplastic ingredients.

The full extent to which microplastics and nanoplastics harm to human and animal health is not well understood. Ingested micro and nanoplastics may trigger inflammatory responses, oxidative stress, and neurological and vascular dysfunction. The role of these particles in metabolic disorders, infertility, gut issues, cardiovascular events have been examined extensively in experimental animals. Human studies in this area are limited but evidence is mounting. A recent paper in Nature Medicine showed that the accumulation of micro and nano plastics were higher in decedent dementia brains compared to healthy controls. Another study published in New England Journal of Medicine highlighted that micro and nano plastics put patients with carotid artery plaques at a higher risk of myocardial infarction, stroke or death compared to controls. A causal role of micro and nano plastics in human disease, or the exact doses that might be harmful has not been elucidated to date.

Given the abundance of micro and nano plastics, and their strong potential to cause harm in humans governments and regulatory agencies are beginning to address them. The EU has proposed restrictions on intentionally added microplastics in certain products. The Microbead-Free Waters Act of 2015 in the US prohibits the manufacturing, packaging, and distribution of rinse-off cosmetics containing plastic microbeads. A persistent challenge is testing micro and nano particles as the current laboratory-based methods (e.g., light microscopy, RAMAN microscopy, FTIR microscopy, SEM/EDX) are expensive, labor-intensive, and not readily available in many places. More research and innovation is urgently needed in this area.

There are a few steps that individuals can follow in order to minimize their exposures to micro and nano plastics. Choosing filtered water (high-quality activated carbon or reverse osmosis water filters) can help reduce microplastics and nanoplastics in drinking water. Reducing plastic waste and products can help avoid plastic packaging, especially single-use plastics and microwaving food in plastic containers, which releases micro and nanoplastics into food. Similarly, prioritizing fresh, unprocessed foods over packaged products can also reduce exposure. By using air purifiers, inhalation of synthetic textiles that shed plastic fibers can be limited. Finally, advocating for stricter regulations on plastic production and waste management as consumers can drive policy changes in the long run.