Each year, over 400 million metric tons of plastic are produced globally from petrochemicals derived from fossil fuels. Only 9% of this plastic is recycled and 19% is incinerated; 72% goes to landfills, other dumpsites or ends up in our environment. These plastics degrade into smaller and smaller pieces, through exposure to sunlight, wind or waves, eventually becoming microplastics or even smaller nanoplastics.
What are nanoplastics?
Microplastics are plastic pieces or fibers less than 5 millimeters in size— smaller than a pencil eraser. As they degrade further, they become nanoplastics, which measure less than 1 micrometer—1/1000 of a millimeter. Nanoplastics behave very differently from larger fragments of plastic because they are so tiny, have relatively large surface areas and are more reactive. They cannot easily be observed, characterized or quantified. However, we do know that over 1,500 species, including humans, ingest these plastics. Nanoplastics have also been found in oceans, rivers, the Alps, Antarctic ice, foods and in bottled and tap water.
Nanoplastics in bottled water
A 2024 study by Columbia University scientists revealed that a liter of bottled water (they tested three brands they did not identify) contained between 110,000 and 370,000 particles, 90% of which were nanoplastics; the rest were microplastics. The study’s coauthor Beizhan Yan, an environmental chemist at Columbia Climate School’s Lamont-Doherty Earth Observatory, said, “Previously this was just a dark, uncharted area. Toxicity studies were just guessing what’s in there.” But for this study, a new method called Raman scattering microscopy, developed by study coauthors Wei Min and chemistry graduate student Naixin Qian, hit plastic particles with laser beams, enabling the scientists to analyze their chemical structure and identify specific nanoplastics. Seven common plastics were recognized, including polyethylene terephthalate (PET), which water bottles are made of, and polyamide (PA), which is used to filter water before it is bottled.
Most of the nanoplastics appeared to come from the bottle itself as well as from the reverse osmosis membrane filter used to purify the water before it is bottled. Other studies indicate that PET plastic particles can come from opening and closing the bottle cap, crushing the bottle or exposing it to heat, for example, in a car.
Nanoplastics in tap water
Tap water also contains nanoplastics, as microplastics and nanoplastics are not completely removed by wastewater and drinking water treatment plants. Microfilters used in water treatment are effective at removing larger microplastics from raw water, but studies have shown that particles from 1-20 micrometers in size remain after water is treated. Reverse osmosis, which uses pressure to force water through a semi-permeable membrane, is used in many municipal water treatment systems, as well as in desalinization systems, to remove pollutants and other impurities in a third or fourth stage of treatment. But reverse osmosis membranes degrade over time, releasing micro- and nano-plastics into the water. While one study found that reverse osmosis combined with other processes removed 93-98% of microplastics, nanoplastics have still been found in water after treatment.
The water distribution system itself—pipes, pumps and valves, especially old and worn ones—can also be a source of microplastics and nanoplastics through the corrosion of pipes and fittings. Pipes in drinking water distribution systems or households are often made of polyethylene, polyvinylchloride, polypropylene or cast iron with PA fittings used to connect pipes in plumbing system.
Where do nanoplastics originate?
Since tires and laundry wastewater have been identified as significant sources of microplastics, they are also likely the main sources of nanoplastics. It’s estimated that 30% of a tire’s weight is emitted into the environment from friction and braking. Up to 279,972 metric tons of acrylic, nylon and polyester microfibers come from the washing of synthetic materials and laundry wastewater around the world, of which about half makes its way into rivers, lakes or oceans. Yan and his Lamont colleague Joaquim Goes are working on ways to remove nanoplastics from laundry wastewater. Wastewater treatment plants and stormwater systems are major sources of nanoplastics that enter surface waters.
Microplastics are also found in sludge, a byproduct of the water treatment process. These accumulate from the PA and polyester in membranes, and polyacrylamide used during water treatment to facilitate the clumping of particles to make them easier to remove, and from the microplastics that remain from the original raw water. After sludge is treated to break down the organic matter within, it is often used as fertilizer or sent to landfills, and thus nanoplastics enter the soil.
How are humans exposed to nanoplastics?
We humans are being exposed to nanoplastics throughout our lives, and because of the size of these particles, they can migrate through our bodies, penetrating tissues and cells. Their effects are not fully understood, because analytical techniques are not developed enough to quantify nanoplastics in the environment or in our bodies. Most studies about the impact of nanoplastics on health have been conducted on animals or in cell cultures. And most have exposed organisms to very high concentrations of nanoplastics, not reflective of real-world environmental conditions. While the findings are worrisome, scientists do not yet know what effects real exposure levels might be having on human health, and therefore there are no established safe levels for micro- or nanoplastics in the body.
We are exposed to nanoplastics through what we eat. Nanoplastics in the ocean are consumed by microscopic organisms like plankton and algae; these organisms are eaten by small fish, who are then consumed by larger fish. As nanoplastics accumulate in these organisms, the tiny particles make their way up the food chain to humans. Human beings ingest nanoplastics in seafood, salt, chewing gum and many other foods, and through eating plants grown in soil and drinking water contaminated with nanoplastics.
We also breathe in nanoplastics. Car tires produce nanoplastics that enter the air around streets. Industrial plants that produce plastic emit aerosolized nanoplastics that enter the atmosphere, and eventually rain and water.
We are exposed through our skin by taking showers with water that carries nanoplastics, or using personal care products and cosmetics that contain nanoplastics.
Naixin Qian asserts, however, that humans are most directly exposed to nanoplastics through medical procedures. So far, this is an area that has not gotten much attention, but she and colleagues who are now researching this believe there is real urgency about exposure to nanoplastics in medical settings. “If you go to the hospital and have an IV injection of a drug, that process actually delivers whatever plastic was in the liquid directly into your body,” she said. “That is a much more dangerous process than, say, drinking bottled water. We know the package of the bag can introduce additional plasticizers, also in the form of nanoparticles, into the blood stream. And by imaging mice as a model, we see that the [nano]particles get distributed across the entire body to all variety of organs.”
Healthcare depends on single-use plastics. For example, blood is collected in plastic bags for blood infusions. Dialysis involves plastic tubing and membranes for the entire dialysis process. Moreover, dialysis patients must have these procedures repeatedly. “How many of those processes can introduce micro- and nanoplastics to the patients?” Qian asked. “And more importantly, these people already have bad health or an impaired immune system. So the toxicity implications from the nanoplastics are only going to be more significant and dangerous for them.”
Impacts on human health
Ingested nanoplastics can affect the microbiome , potentially leading to the development of inflammatory bowel disease, autoimmune diseases and cancer. Studies have shown that nanoplastics in the intestines also penetrate the intestinal barrier to enter the blood stream. The circulatory system can then carry nanoplastics to the neurological, musculoskeletal, reproductive and endocrine systems.
According to studies of fish, nanoplastics caused an impaired heart rate, thrombosis, damage to the vascular structure, hormone changes, reduced immunity and altered blood biochemistry. A 2024 study analyzed the plaque buildup removed from patients who had narrowing of the carotid arteries for micro- and nanoplastics. They found that, 34 months later, patients that had micro- and nanoplastics in their carotid artery plaque had a higher risk of heart attacks, stroke or death from any cause than patients in whom no plastic particles had been detected.
Research also shows that nanoplastics can cross the blood-brain barrier and cause brain damage in fish. Mice fed nanoplastics showed a decline in cognitive function and short-term memory. One recent study analyzed the brains of people who had recently died and discovered 50% more plastic in them than brain samples from 2016. The scientists also found that the brains of people who had had dementia contained far more nanoplastic in them than people without it, but they were not sure if this was because their brains had a less robust blood-brain barrier.
Nanoplastics have also been found in the placenta, potentially causing harm to the developing fetus, as well as in testes, semen and breast milk.
Inhaled nanoplastics can affect the respiratory tract, leading to chronic inflammation of the lungs, asthma, pulmonary fibrosis and increased risk of lung cancer.
Research has shown that almost every cell type in the body is affected if it comes into contact with nanoplastics and, generally, the interaction results in inflammation, which can cause other problems. However, scientists still do not understand the underlying mechanisms for these effects.
In addition to the impacts from the nanoplastic particles themselves, because of their large surface area, they can transport toxic chemicals such as the PCBs, dioxins, DDT, PAH, BPA and phthalates used in the manufacturing of plastic. Many of these chemicals are carcinogenic or endocrine disrupters. A new study linked 356,238 deaths globally from cardiovascular disease to the phthalates typically used in personal care products, packaging and food containers.
Solutions to nanoplastic pollution
Researchers are trying to develop better technologies to remove nanoplastics from water. Physical methods include filtration using new membrane materials, and adsorption with various materials that can bind to pollutants and remove them from liquid. Magnetic particles are being developed that can be altered to attract nanoplastics and allow them to be removed with a magnetic field. Electrochemical techniques apply electricity that enables certain materials to identify, separate and attract nanoplastics or break them into smaller less harmful pieces. Biodegradable polymers that decompose into natural substances aided by microorganisms are being used to attract and bind to nanoplastics allowing them to be easily removed. Scientists at the University of Missouri developed a new nontoxic chemical solvent that captured nanoplastics from water, then rose back to the top, allowing for easy removal of 98% of the nanoplastics from both fresh and salt water in the lab.
Chinese researchers have experimented with boiling water and then filtering out the nanoplastics, removing up to 90% of them. Qian said she herself boils her water before drinking it. “Nanoplastics tend to aggregate and form larger particles in higher temperatures. By boiling the water, you can make small nanoparticles aggregate into larger, micro particles, thousands of them into one. That reduces their toxicity implications, because their larger size reduces their ability to cross the biological barrier and get into your cells,” she said.
These removal techniques have shown promise in the lab, but more research is needed to see if they can be scaled up, and to determine their impacts on the environment.
Qian believes it’s also important to explore new materials to replace plastics and hopes to pursue post-graduate research in this area. “There is a good chance we can build materials that will have friendly interactions with biological systems,” she said. “There should be a way we can learn from nature and come up with solutions that are friendly to our health.”
Right now, however, she hopes that the potential peril of micro- and nanoplastics in the medical area will be more widely acknowledged and that measures will be taken to address it. “It’s going to need collaborative efforts from the whole society, with manufacturing to reduce the exposure of micro- and nanoplastics in their products, agencies to impose regulations on products, and researchers from all different areas—material science, biology and chemistry—to understand their toxicity and provide alternatives to adopt.”
How to lessen your exposure to nanoplastics
Avoid:
- Bottled water
- Processed foods; their production and packaging convey nanoplastics
- Dishwasher or laundry pods
- Washing plastic products in hot water and microwaving plastics
- Single-use plastics, such as cutlery or cups
- Plastic wrap and packaging
- Cosmetics and personal care products containing microbeads, and silicone-based polymers used as thickeners; use bar soap and shampoo bars
- Clothes made from synthetic fibers such as polyester, nylon or spandex; choose natural fibers like cotton, wool or linen instead
Do:
- Buy and store products in glass if possible
- Filter your tap water or boil it before drinking.
- Opt for loose leaf teas; many tea bags shed nanoplastics
- Reduce seafood consumption
- Eat deeply colored fruits and vegetables. The antioxidants in them reduce microplastic-induced inflammation
- Be aware of plastics in medical procedures and avoid them if at all possible
