Microplastics are everywhere: in the food we eat, the water we drink, and even the air we breathe. Imagine consuming the equivalent of a credit card’s worth of plastic every week—just by going about your daily routine. As startling as it may seem, this is the reality we face, exposing our bodies to a hidden threat that’s growing by the day.
What are microplastics? They're tiny pieces of plastic or other polymer-based materials, ranging from 5 millimeters (~0.2 inches) to as small as 100 nanometers, often called nanoplastics. These tiny particles contain a variety of chemicals that are harmful to humans, including polyethylene terephthalate (commonly called PET), polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyester, polyurethane, polyamide, styrene acrylate, and polymethyl-methacrylate.
Roughly 70% to 80% of micro- and nanoplastics come from the breakdown of larger plastic pieces, either through oxidation or other degradation processes. The remainder comes from plastics intentionally added to commercial products. They come in many forms, including microfibers from textiles (mostly diapers, fleece clothing, and disposable masks), plastic fragments, and industrial plastic pellets, beads, foam, and microbeads.
Humans are exposed to micro- and nanoplastics in various ways, such as ingestion, inhalation, and skin contact. Research shows these particles can accumulate in various body fluids and tissues, including the blood, endometrium, heart, liver, lungs, placenta, sputum, and testes.[1] When microplastics come into contact with protein molecules in biological fluids, tissues, or organs, they can form a crown-like structure known as a corona. Some research shows that microplastics with a corona can move through the body more efficiently, with the rate depending on the amount and type of proteins involved, potentially increasing cell interactions and toxicity.[2]
This article delves into the many ways we're exposed to microplastics, just how widespread these particles are in the human body, and what their potential health effects might be. It also provides practical tips for reducing microplastic exposure.
In brief, microplastics…
Countless studies show that microplastic exposure harms human health. These ubiquitous environmental pollutants trigger oxidative stress and increase the risk of metabolic dysfunction, neurotoxicity, and some cancers.[5] Some of these health effects may be due to compounds commonly used in plastic manufacturing, such as bisphenol A (BPA), phthalates, and heavy metals that are present in and on microplastics.[5] These compounds are known endocrine disruptors—substances that mimic or interfere with normal hormonal processes in the human body.[6]
Plastics also contain per- and poly-fluoroalkyl substances (PFAS), a large group of synthetic chemicals used in nearly every commercial product we purchase, including food packaging, household items, and water bottles. The body eliminates many synthetic substances in bodily fluids like sweat or urine. But not so with PFAS—these compounds remain in the body indefinitely, earning them the nickname "forever chemicals."[12] PFAS exposure may increase the risk of cancer, liver damage, and immune system impairment. Studies have shown that in infants and children, PFAS exposure can cause developmental issues such as low birth weight and early puberty. In adults, it's linked with thyroid disease, high cholesterol, and infertility.[13]
"The body eliminates many synthetic substances in bodily fluids like sweat or urine. But not so with PFAS-these compounds remain in the body indefinitely, earning them the nickname"forever chemicals." Click To Tweet
Microplastics are found in many environmental settings, contributing to widespread exposure among living organisms. Although exposure rates vary, one study estimated the average person’s annual exposure to microplastic particles from these sources:[14]
"Alarmingly, some studies have shown that sea ice can trap microplastics, temporarily storing them and potentially masking the true extent of microplastic pollution in Arctic waters." Click To Tweet
A study that looked at human exposure to microplastics found that intake from food and water sources can range from 39,000 to 52,000 particles per year, depending on factors like age and sex. However, people who get their daily water intake exclusively from bottled water could ingest an additional 90,000 microplastic particles each year, compared to just 4,000 particles for those who drink only tap water. While estimates vary, the researchers believe that these numbers are likely on the conservative side, and other research supports this view.[15]
In another study, researchers tested 11 globally sourced bottled water samples for microplastic content. Of 259 samples, 93% showed microplastic contamination. One sample had more than 10,000 microplastic particles per liter. More than half (54%) of the particles were polypropylene (the primary material in bottle caps), and 16% were nylon. Most particles were between 6.5 and 100 micrometers.[16] A Consumer Reports study tested 47 bottled water samples for 30 PFAS chemicals and found that nearly all the products showed measurable levels of PFAS.
Global marine microplastic pollution is also well documented, with contamination found in bodies of water worldwide—mostly from plastic waste and commercial fishing and processing equipment. These microplastics pose immense threats to aquatic life and ecosystems because they can be ingested by marine organisms, causing toxic effects and potentially making their way into the human food chain.[17]
Although microplastic pollution is largely linked to human activity, it has also been found in remote, relatively uninhabited bodies of water around Antarctica. Scientists on a research vessel evaluated microplastic content in ocean water at surface and subsurface levels, testing samples at depths up to approximately 11 meters (~37 feet). They discovered microplastics in 65% of surface samples and 11% of subsurface samples, with 90% of the particles coming from the research vessel itself, underscoring the role of ocean-going vessels in spreading microplastics. Alarmingly, some studies have shown that sea ice can trap microplastics, temporarily storing them and potentially masking the true extent of microplastic pollution in Arctic waters.[10]
Major contributors to microplastics in water are melamine cleaning sponges, often called "magic erasers." These sponges are made of hard, plastic strands assembled into soft, lightweight foam and are extremely popular due to their abrasive qualities. Researchers looked at microplastic release from melamine cleaning sponges under different scrubbing conditions. They found that the sponges released various types of microplastic fibers made of poly(melamine-formaldehyde) polymer, ranging in size from 10 to 405 micrometers. These fibers formed when the sponge's structure broke down due to friction. As a result, the rougher the surface and denser the sponge, the more fibers it produced. The researchers estimated that typical melamine sponge wear could release up to 6.5 million fibers per gram of sponge, potentially contributing up to 4.9 trillion fibers to global water sources.[18]
Airborne microplastic particles are small enough to be inhaled and can accumulate in large quantities in the upper and lower airways. In a study comparing snow samples from a remote Arctic region to those from unpopulated and populated areas of Europe, researchers found that Arctic snow contained a surprisingly large amount of microplastics, though less than what was seen in European snow—some Arctic samples contained up to 1,760 microplastic particles per liter of air. The composition of these particles varied, and many were incredibly small—down to 11 micrometers, the smallest size detectable—suggesting that even more undetectable particles may have been present. These results demonstrate the widespread distribution of airborne microplastics and highlight the role of atmospheric transport in their spread.[11]
Microplastic particles are also found in indoor air. One study investigating indoor microplastic exposure found that an average male engaging in light activity could inhale up to 272 microplastic particles in a single day. Over a week, this exposure amounts to roughly the equivalent of the plastic in a typical credit card (see "Lungs" below).[19]
Microplastics can be found in a wide range of soils, too, including agricultural fields, greenhouses, home gardens, coastal areas, industrial sites, and floodplains. They can alter soil properties, affect microbial and enzyme activities, and influence plant growth, all while posing toxicity risks to soil organisms like earthworms. Some evidence indicates that earthworms can transport microplastics through the soil, potentially contaminating groundwater sources or entering the food chain.[20] Other research shows that earthworms—essential for soil health—struggle to thrive in microplastic-heavy soils.[21]
Microplastics can contaminate our food and beverages through contact with plastic containers, packaging, and preparation tools, but they can also enter foods in the environments where they are grown or sourced, such as seawater or soil.
Researchers analyzed the microplastic content in a popular soda brand purchased in various US locations: Atlanta, Los Angeles, Chicago, and Washington, DC. The sodas were in aluminum, glass, or plastic containers. They found that the average concentration of microplastic particles in 100 milliliters of soda was 166, with some samples reaching a staggering 482 particles—meaning that a typical 16.9-ounce (~500-milliliter) bottle of soda could contain more than 2,400 microplastic particles. Interestingly, the sodas in glass containers had the highest concentrations of particles. The study investigators speculated that the primary contributors to the sodas' microplastic contamination were local water sources (near the packaging plants).[22]
Researchers have studied the release of micro- and nanoplastics from plastic baby food containers and reusable food pouches in various settings, including microwave heating, refrigeration, and room-temperature storage. They found that microwaving food yielded as many as 4.22 million microplastic and 2.11 billion nanoplastic particles from only one square centimeter of plastic area after just three minutes of microwave heating. Refrigeration and room-temperature storage for more than six months released millions to billions of microplastics and nanoplastics—with the amount of nanoplastics typically 1,000 times greater than that of microplastics. The researchers estimated that daily exposure to micro- and nanoplastics from microwaved foods was 20.3 nanograms per kilogram (ng/kg) of body weight for infants and 22.1 ng/kg for toddlers. In addition, when they exposed human embryonic kidney cells to the released particles, more than three-fourths (77%) of the cells died within three days, highlighting the particles' toxicity.[23]
Interestingly, one study found that plastic teabags released billions of micro- and nano-plastics during the steeping process at 95°C.[24] However, another study disputed these findings due to concerns about the methods used to identify the particles, underscoring the importance of appropriate microplastic assessment techniques.[25]
Plastic cutting boards release microplastic particles during the chopping process, but the extent of exposure varies with the type of plastic. A study comparing microplastic release from plastic cutting boards found that in a given year, a person's microplastic exposure may be as much as 50.7 grams from a board made of polyethylene (the most common material for plastic cutting boards). A person's chopping style and the type of food being chopped also influenced microplastic release, with hard foods like carrots causing greater release.[26]
Similarly, another study found that a plastic kitchen blender could release between 360 and 780 million microplastic particles during just 30 seconds of use.[27]
"Some research suggests that microplastic exposure can change the structure of beta-lactoglobulin, a protein in breast milk that helps transport nutrients like vitamin A, making it less effective." Click To Tweet
Microplastics have even been found in breast milk and infant formula, posing an essentially unavoidable exposure risk to infants. A staggering 76% of breast milk samples from lactating women contained microplastics, primarily polyethylene, polyvinyl chloride, and polypropylene. These particles, ranging from 2 to 12 micrometers, were ubiquitous, with no clear link to specific lifestyle factors.[7]
Some research suggests that microplastic exposure can change the structure of beta-lactoglobulin, a protein in breast milk that helps transport nutrients like vitamin A, making it less effective. It also appears to alter lysozyme, another important breast milk protein that fights bacteria, leading to the formation of abnormal protein clumps called amyloid fibrils.[28]
Storing breast milk may further add to infant microplastic exposure. An analysis of six commonly used breast milk storage bags found that breast milk stored in the bags contained between 0.22 and 0.47 milligrams of microplastic particles, exposing the infants to 0.61 to 0.89 milligrams daily, depending on consumption.[8]
Infant formula products may contain microplastics, too. Researchers assessed microplastic content in 13 powdered milk (formula) products with different packaging, processing systems, and milk sources. They found that the inner packaging of boxed powdered milk, which was made of plastic and aluminum foil laminate, released up to 17 microplastic particles per 100 grams of milk powder—far more than canned products. However, using plastic feeding bottles increased exposure an astonishing ninefold.[9]
Microplastics also enter our food directly from the environment. For example, seafood can contain microplastics due to contamination in seawater. Researchers found that commercially grown mussels contained an average of 0.36 particles per gram (wet weight), while oysters had 0.47 particles per gram (wet weight). They estimated that shellfish consumers could ingest approximately 11,000 microplastics annually through their diet.
Similarly, microplastics have been detected in meat, including chicken, beef, and pork.[29] [30] Some of these microplastics come from food packaging, but others are present in the meat before processing and packaging, raising concerns about the potential threats to the global food chain.[31]
Microplastics are even found in salt, which can come from sea and land sources. An analysis of 15 brands of sea salts, lake salts, and rock/well salts purchased from supermarkets found that sea salts contained between 550 and 681 microplastic particles per kilogram, considerably higher than lake salts (43 to 364 particles per kilogram) and rock/well salts (7 to 204 particles per kilogram), with PET being the most common type.[32]
A separate analysis of 17 global sea salt brands found that nearly all samples contained 1 to 10 microplastic particles per kilogram. The average particle size was 515 micrometers, primarily polypropylene and polyethylene. The researchers estimated that the average person consumes about 37 microplastic particles from salt yearly.[33]
"Microplastic particles are small enough to penetrate cell membranes and accumulate inside cells, directly impacting mitochondria." Click To Tweet
With microplastics present in our air, water, and food, it isn't surprising that they've been found throughout the respiratory and gastrointestinal tracts. Once there, they can penetrate biological barriers and enter the bloodstream, providing a means for widespread dissemination. Consequently, microplastics have found their way into nearly every organ system in the human body, including the respiratory, vascular, gastrointestinal, neurological, and reproductive systems. This section looks at some key findings highlighting how widespread microplastic bioaccumulation is.
Researchers looked at microplastic content in the sputum (mucus from the lower airways) of 22 people with various respiratory diseases. They found 21 types of microplastic particles, including polyurethane, polyester, chlorinated polyethylene, and alkyd varnish. Most of these particles were smaller than 500 micrometers, and smokers had more microplastics in their sputum than non-smokers.[34]
In another study, investigators analyzed lung tissue samples from 13 older adults undergoing scheduled lung surgery. The researchers found microplastic fibers, fragments, or films in 11 of the 13 samples. On average, each sample had three particles, with some samples containing up to eight. They identified 12 different polymer types, with polypropylene (used in food containers and plastic pipes) and PET (found in water and soft drink bottles) being the most common.[3]
Further studies in mice showed that exposure to microplastics could induce lung inflammation, increased immune cell activity, macrophage aggregation, and higher levels of TNF-alpha and plasma immunoglobulin G1. In mice with asthma, the symptoms worsened due to increased mucus production and inflammatory cell infiltration. Interestingly, researchers observed macrophages ingesting the microplastics—decreasing the cells’ viability—and noted considerable oxidative stress, reduced cell proliferation, and DNA damage.[35] [36]
There’s also evidence that microplastic particles can impair the lung epithelial barrier, allowing these particles to spread more easily throughout the body.[37]
"Patients with microplastics in their plaques were 4.53 times more likely to experience a cardiovascular event during a three-year follow-up than those without." Click To Tweet
A study revealed that the average concentration of microplastics in human blood was 1.6 micrograms per milliliter, suggesting that the bloodstream plays a crucial role in spreading microplastics throughout the body.[38]
Researchers also collected blood and tissue samples from 15 cardiac surgery patients to check for microplastic content. They found nine types of microplastics, the largest measuring 469 micrometers in diameter. Interestingly, the types and sizes of microplastics in the blood changed after surgery, indicating that surgical procedures involving plastic devices might introduce new microplastics or alter existing ones. However, some microplastics found in tissue samples were not linked to surgical exposure, providing direct evidence of microplastics in patients undergoing cardiac surgery.[39]
In another study, researchers found microplastics in surgically removed arterial plaques from 257 patients. More than half (58.4%) of the patients had microplastics in their plaques, appearing as jagged-edged foreign particles. Patients with microplastics in their plaques were 4.53 times more likely to experience a cardiovascular event during a three-year follow-up than those without. These patients were also more likely to be male, younger, and have diabetes, cardiovascular disease, abnormal blood lipids, and higher inflammatory markers.[40]
Another study involved removing thrombi (blood clots) from 30 patients scheduled for arterial or venous thrombectomy in the brain, heart, or legs using plastic-free surgical implements and storage techniques. The researchers found that 80% of the thrombi contained microplastics, including polyamide 66, polyvinyl chloride, and polyethylene. Higher concentrations of microplastics were linked to greater disease severity.[1]
Researchers analyzed fecal samples from 102 people, half with inflammatory bowel diseases (IBD), such as Crohn’s disease or ulcerative colitis. They found that participants with IBD had an average of 41.8 microplastic particles per gram of dry fecal matter, compared to 28.0 particles among healthy people. Most of the particles, which came from plastic packing and dust, were sheets, fibers, fragments, or pellets and typically smaller than 300 micrometers. The people with higher fecal microplastic concentrations tended to have more severe IBD symptoms.[41]
In another study, researchers exposed four human colorectal cancer cell lines to polystyrene micro- and nanoplastics of various sizes (0.25, 1, and 10 micrometers) and concentrations. They tracked the particles' uptake into cells and monitored their behavior during cell division. They found that all the cancer cells absorbed micro- and nanoplastics, with the highest uptake observed in HCT116 cells—a type of cells commonly used to study various aspects of tumor biology. Notably, the cells didn't eliminate the absorbed particles. Instead, they passed them on during cell division, sharing them between the original and new cells. Even short-term exposure to the smallest particles (0.25 micrometers) increased the cells' movement, which could facilitate metastasis.[42]
When researchers used liver organoids derived from human stem cells to study microplastic exposure, they found that even low environmental levels of polystyrene microplastics increased the expression of certain genes like HNF4A and CYP2E1. Elevated HNF4A can disrupt lipid metabolism, potentially leading to fatty liver, while increased CYP2E1 raises oxidative stress, increasing the risk of liver damage, fibrosis, and cancer. These changes may also increase the risk of insulin resistance and type 2 diabetes.[43] [44]
In another study, liver samples from healthy people and those with liver cirrhosis were analyzed, and all samples contained microplastics. However, the concentration was considerably higher in those with cirrhosis, suggesting that microplastic accumulation might contribute to or result from liver disease.[45]
"The researchers also noted the activation of pro-inflammatory proteins like NF-κB and apoptotic markers, suggesting that microplastics might be able to cross the blood-brain barrier and trigger immune responses and cell death in microglial cells" Click To Tweet
Studies on the brain have shown that microplastics can accumulate in the microglial cells (the brain’s immune cells) of mice and humans. In humans, exposing microglial cells to microplastics altered the cells' shapes, interfered with immune responses, and promoted cell death. These changes were linked to alterations in the expression of immune response genes, antibodies, and related microRNAs. The researchers also noted the activation of pro-inflammatory proteins like NF-κB and apoptotic markers, suggesting that microplastics might be able to cross the blood-brain barrier and trigger immune responses and cell death in microglial cells.[4]
Similarly, another study exposed mice to different types of plastic microspheres and found that polystyrene microspheres accumulated in the brain, liver, and kidney, leading to metabolic disturbances that varied depending on the type and concentration of the microspheres.[46] In worms, microplastic exposure impaired movement similar to the neurotoxin paraquat.[28]
Microplastics don’t spare the reproductive system either, accumulating in both female and male reproductive tissues. In females, exposure to microplastics is linked to altered sex hormone levels and oxidative stress, while in males, it’s linked with testicular inflammation and blood-testis barrier dysfunction, potentially impairing reproductive health.[47] [48] [49]
In one study, researchers explored the effects of microplastics from disposable paper cups filled with hot water on pregnant mice. They found that microplastics accumulated in all 13 tissues analyzed, with the highest amounts in the intestinal contents, followed by the fetus, placenta, kidney, spleen, lung, and heart. More than 90% of microplastics smaller than 10 micrometers ended up in the brain. The researchers also noticed marked effects on metabolic and immune health, raising concerns about potential risks for brain disorders and miscarriage.[50]
A study of endometrial tissues from 20 women revealed 13 types of microplastics, with most particles being between 20 and 100 micrometers. Women who drank milk tea, tea, and carbonated beverages from plastic containers or chewed gum regularly had higher levels of microplastics in their endometrial tissues.[51]
In a study involving six human placentas from normal pregnancies, researchers found microplastic fragments in four of the placentas, with sizes ranging from 5 to 10 micrometers. These fragments, which were located on the fetal side, maternal side, and the membranes that make up the amniotic sac, were made of polypropylene and pigments commonly used in synthetic coatings, paints, adhesives, and cosmetic products.[52]
Another study looked at the effects of microplastics on placental and meconium microbiotas, finding 16 types of microplastics, mostly polyamide and polyurethane. More than 76% of the particles measured between 20 and 50 micrometers, with some larger than 150 micrometers. The presence of microplastics was linked with reduced bacterial diversity in meconium and changes in the placenta’s bacterial populations.[53]
Researchers identified microplastics in amniotic fluid, too, with 90% of pregnant women having various forms.
In a small study of penile tissue from six healthy males, researchers identified microplastics in 80% of samples, ranging in size from 2 to 500 micrometers. They identified seven distinct polymers, with PET and polypropylene being the most common, raising questions about microplastic exposure's possible role in erectile dysfunction.[54]
Microplastics were found in the testes of dogs and humans, with considerable variability between samples. Higher levels of certain microplastics, like polyvinyl chloride and PET, were linked to lower testes weight in both species.[55]
In an assessment of semen samples from 40 young, healthy men, all samples contained microplastics, with an average of two particles per sample, ranging from 0.72 to 7.02 micrometers. Eight distinct polymers were present, with polystyrene being the most common at 31%. Sperm in the samples showed various abnormalities and impaired motility, especially those exposed to polyvinyl chloride, a plastic used in pipes and many other products.[56]
Microplastic particles are small enough to penetrate cell membranes and accumulate inside cells, directly impacting mitochondria.[57] Once there, these tiny plastics can cause noticeable structural changes, such as swelling and a loss of integrity in the mitochondria.[57] This damage doesn’t just stop at structural issues—it also leads to functional problems. For example, polystyrene nanoparticles can disrupt the electron transport chain, which is crucial for cellular energy production, ultimately reducing ATP synthesis.[58]
Beyond energy production, microplastics can interfere with these aspects of mitochondrial function [59]:
The link between these mitochondrial disruptions and various diseases emphasizes the importance of understanding how these interactions affect long-term health.
Microplastics are ubiquitous, and preventing exposure is likely impossible. However, here are some practical steps you can take to minimize your exposure:
Given the widespread environmental burden of microplastics, finding effective removal strategies has become crucial. This section presents approaches—both traditional and novel— that could help eliminate microplastics from the environment.
"While treatment plants can filter out larger plastics, many microplastics remain in the treated water, with quantities varying widely depending on the location and type of wastewater." Click To Tweet
Wastewater from industries, homes, farms, and livestock contains many microplastics. Wastewater treatment plants are the first line of microplastic removal for municipal water sources. However, while treatment plants can filter out larger plastics, many microplastics remain in the treated water, with quantities varying widely depending on the location and type of wastewater.[60]
Physical methods to remove microplastics use flotation, sedimentation, and various types of filtration. These include:[60]
Chemical methods involve using coagulants to clump microplastics together so they can be removed more easily. The effectiveness of this method depends on the type and amount of coagulant used, as well as the specific conditions of the water. Evidence suggests combining certain coagulants can remove up to 99% of microplastics.[60]
Biological methods use bacteria and other organisms to trap microplastics.[60] These include:
Overall, while biological methods can trap some microplastics, they are generally less effective and can contribute to further contamination.
"Certain plants and algae can absorb or trap microplastics in their tissues. Implementing these in water treatment systems could provide a natural method for microplastic removal." Click To Tweet
Scientists have developed a hydrogel composed of a complex polymer infused with copper substitute nanoclusters. These nanoclusters act as catalysts under ultraviolet light, breaking down microplastics trapped in the hydrogel. This method has achieved up to 95% removal efficiency for specific microplastics, offering a promising and sustainable approach to reducing microplastic pollution in water.[61]
Advanced oxidation processes use powerful oxidants, such as ozone, hydrogen peroxide, or ultraviolet light, to break down microplastics into harmless substances. Researchers are exploring this method for its potential to degrade even the smallest plastic particles.[62]
Nanotechnology offers another promising avenue for tackling microplastic pollution. Researchers are developing nanomaterials that can adsorb or degrade microplastics. Nanoparticles can capture microplastics more effectively than traditional methods, potentially providing a more efficient solution.[63]
Certain enzymes can break down plastic polymers. Scientists are developing strategies that enhance these enzymes to target and degrade microplastics specifically.[64]
By coating microplastics with magnetic materials, researchers can use magnets to attract and remove microplastics from water. This technique offers a novel and potentially highly efficient way to clean water from microplastics.[65]
This method uses electric currents to induce coagulation, causing microplastics to clump together and settle out of the water. It's an emerging technology that shows promise in improving microplastic removal efficiency.[66]
Some microorganisms can degrade plastic materials. Research is focusing on harnessing these microbes to target and break down microplastics in water.[67]
Using natural materials like plant fibers, which can trap microplastics, is an eco-friendly approach. These biodegradable filters offer a sustainable alternative to synthetic filtration systems.[68]
Certain plants and algae can absorb or trap microplastics in their tissues. Implementing these in water treatment systems could provide a natural method for microplastic removal.[69]
Microplastics are everywhere—in air, water, food, and even our bodies—with far-reaching implications for both human and environmental health. From endocrine disruption and oxidative stress to potential links with cancer and metabolic dysfunction, the evidence points to considerable risks associated with microplastic exposure.
While completely avoiding microplastics is likely impossible, understanding how these particles enter our bodies and the potential harm they cause is the first step toward protecting ourselves. By making informed choices—whether in the food we eat, the products we use, or the materials we surround ourselves with—we can reduce our exposure and mitigate some of the risks posed by this pervasive pollutant.