Each year, between 10 million and 40 million metric tons of microplastics are released into the environment. If current trends persist, this amount is projected to double by 2040.
Even if all new emissions were stopped today, existing microplastic levels would continue to rise as older plastic debris breaks down into smaller particles.
A review published in Science summarizes the current understanding of microplastic pollution two decades after the term “microplastic” was first introduced. The authors critique earlier estimations of weekly plastic ingestion, suggesting that up to 5 grams—or the weight of a credit card—may be an overestimation.
How Microplastics Enter Our Bodies
Microplastics are solid plastic particles measuring less than five millimeters. They permeate ecosystems, seep into our food and water, and find their way into our bodies.
Microplastics mainly come from the breakdown of larger plastics, but they can also be released from plastic recycling, textiles, tires, paint, clothing, and soft furnishing.“Fast fashion is all made with polyester, nylon, spandex, etc.,” Charron said. Fast fashion refers to low-cost clothing produced and sold on a mass scale.
“Another ’secret' product often made of plastic textiles are carpets, curtains, and bedding,” Charron said, noting that these materials shed microplastics and toxic chemicals into the air we inhale. He said they tend to be some of the most harmful sources of microplastics because they release fibers directly into our air and waterways when washed.
One study found that more than 90 percent of microplastics indoors consist of polyester and manmade fiber, both derived from plastic.
Microplastics can enter our bodies through various means:- Inhalation: Microplastics are in the air we breathe.
- Skin absorption: We can absorb them through contact.
- Oral ingestion: Consuming food or beverages contaminated with microplastics, such as milk, soft drinks, canned goods, sugar, and salt, or via organisms such as shrimp and fish, is another way they enter our bodies. Infants are also exposed through breast milk and formula.
Microplastics in the Human Body
Research indicates that microplastics have infiltrated various parts of the human body, including:- Blood vessels: Microplastics have been detected in carotid artery plaques and leg vein tissue samples.
- Brain: Studies show that microplastics may reach the brain through the nasal passage, bypassing the blood-brain barrier. A 2024 study also found that the brain has a higher concentration of microplastics than the liver and kidneys.
- Blood: One study identified four types of plastics in a plastic-particle concentration of 6 micrograms per milliliter in 22 healthy volunteers, with polyethylene being the most abundant. Polyethylene is a widely used plastic due to its versatility. It is found in apparel, furniture, and consumer goods. There is still no established threshold or reference level for microplastics in human blood. However, for context, lead, commonly found in sources such as old paint and contaminated water, is considered concerning in children’s blood at levels above 3.5 micrograms per deciliter (1 deciliter is 100 milliliters).
- Saliva: One study found 21 types of microplastics in saliva samples from patients with respiratory diseases.
- Lungs: Microplastics were present in all regions of the lungs in 11 out of 13 study participants, with polypropylene and polyethylene terephthalate fibers being the most abundant. Higher concentrations of microplastics were found among smokers.
- Feces: In one study, 10 common types of plastics were found in stool samples. Children appear to be at greater risk, with findings showing that infants have 10 times more plastic in their feces than adults. This difference may stem from infants’ higher exposure to plastics through activities such as crawling, chewing on textiles, and mouthing objects. Studies also found microplastics in meconium—the first stool passed by newborns.
- Placenta: Microplastics were detected in part of the placenta, suggesting they can cross the placental barrier and potentially affect fetal development.
- Liver: Microplastics were seen in liver tissues of people with cirrhosis, with concentrations notably higher than in samples from those without liver disease.
- Colon: Microplastics were also detected in colon sections removed during surgeries, indicating they may remain in the digestive tract.
While there is evidence that microplastics accumulate in the body, research on their health effects is still limited.
Health Implications of Microplastics
Because microplastics are foreign bodies, they trigger an immune system response. However, the body cannot effectively eliminate them, unlike viruses and bacteria. This chronic presence may lead to oxidative stress and inflammation, potentially resulting in a range of health issues, including DNA damage, allergic reactions, cell death, and cancer.
Microplastics also contain chemicals that can disrupt normal hormone functions and metabolic processes. These harmful substances may leach from the microplastics and enter the body through skin absorption or ingestion.
“Microplastics act as vectors that also carry viruses and bacteria, which then travel into our bodies if we inhale or ingest the microplastics,” Charron said.
Research has linked microplastic exposure to an increased risk of diseases. For instance, according to the study on saliva samples, exposure may put people at higher risk of pulmonary diseases characterized by coughing, shortness of breath, wheezing, and a more severe inflammatory bowel disease. Additionally, the presence of plastic in arteriosclerotic plaques (fatty deposits that build up in the arteries), increases the likelihood of heart attack, stroke, or death.
Despite growing evidence of health risks, there is still no way to assess microplastic risks or measure human exposure.Ways to Reduce Microplastic Exposure
While eliminating plastic from our lives is unrealistic, there are actionable steps we can take to reduce our exposure.
“Ninety percent of the most harmful toxins are already present in most households, meaning individuals can reduce exposure significantly by making conscious choices in food sourcing and household product selection,” Savage said.Charron said: “Run a plastic audit of your house, and take a log of what plastic you are using every day. It is impossible to make adjustments without knowing where you are using the most amount of plastic.”
After this audit, he said, determine the most common source of plastic used in your house and find a more sustainable alternative.
In addition to avoiding single-use plastics, he recommended:
- Avoiding polyester fabrics and opting for cotton, wool, linen, and natural fibers
- Avoiding recycled plastics, such as swimwear, which shed more than plastics produced from raw materials
- Not giving children or pets plastic toys
- Opting for green vegetables over root crops that may be more contaminated
Most importantly, he advised advocating legislation aimed at reducing plastic usage. “Cigarette and plastic bag bans in certain areas are extremely effective in cutting down environmental waste,” he said.
Global efforts to combat microplastic pollution are gaining traction. In March 2022, the U.N. Environment Assembly resolved to create a legally binding treaty on plastic pollution, including marine plastics. The plan is to finalize it by the end of 2024. Such a treaty would require countries to take specific actions under international law, with penalties for noncompliance—a key step toward global cooperation on plastic waste.
The European Union has adopted a strategy to reduce plastic waste and increase recycling across member states. Similarly, countries such as the United States, Canada, and the UK have banned microbeads in cosmetics to address a major source of microplastics.