Where do microplastics come from?

We interact with common sources of microplastics every day

Over the last 40 years, plastics have infiltrated our daily lives. While they were technically first created in the early 1900s, it wasn’t until after World War II—when production exploded to support the war effort and the building of the atomic bomb—that synthetic products became the norm. 

Now, not only are plastics clogging up landfills, roadsides, and waterways, but we also know that even the toughest-seeming plastics will eventually degrade in the environment. Enter microplastics—the miniscule particles of debris that come off consumer products and waste and that have been found on virtually every corner of the planet, from Arctic sea ice to the air we breathe. 

What are microplastics?

In the early days of plastics, people believed that they were “forever” products that would seemingly never degrade—a long-lasting solution to breakable glass or delicate paper. Plastics, however, do break down. Some products, like the polyurethane foam used in cushioning, can fall apart in a matter of days. Others, like disposable diapers, toothbrushes and plastic bottles, may take generations to decay. When larger plastic items like water bottles or toys (“macroplastics”) are exposed to the elements, such as UV rays, they will eventually break down into smaller pieces. 

Plastics smaller than 5 millimeters (about the width of a pencil’s eraser) are considered “microplastics.” The tiniest ones—below 1 micrometer, or 1,000 times smaller than a millimeter—are called nanoplastics. Researchers have estimated there are trillions of pieces of microplastics, weighing billions of pounds, floating at the surface of the world’s oceans.1 That estimate doesn’t even account for all of the tiny pieces of micro- and nanoplastics that have sunk to the bottom, remain on land, are trapped in ice, or that float undetectably in the air.

Where do microplastics come from?

Scientists believe the majority of microplastics found in the environment come from the deterioration of macroplastic products from a variety of sources. A 2020 study estimated that most are first broken down on land due to exposure to the elements. The forces at play include temperatures, UV exposure, and “frictional forces”—which could include, for example, the slow wearing of tires as they roll over roadways.2 Many of those land-based pollutants will eventually end up in nearby waterways or even become airborne if small enough. These particles are known as “secondary microplastics.”

There are also “primary microplastics,” which are the microplastics put into circulation intentionally at incredible small sizes. Small plastic beads known as “nurdles,” for instance, are the building blocks of many plastic products from bottles to car parts. Then there are microbeads, which are used in some cosmetics and cleaning products, and microfibers, or the tiny, synthetic threads that make up fabrics like jersey and pleather.  

Once microplastics enter the environment, it’s almost impossible to clean them up. The solutions largely lie in making sure plastic doesn’t end up on the land or in waterways in the first place.

The smaller the plastic piece, the more of a risk it poses in the environment for both animals and human health. All improperly disposed plastics will eventually break down into the smallest nanoplastic particles, a threat to public health and the planet. People can be impacted by microplastics largely by ingesting them directly from food or inhaling them from contaminated air. Studies have found microplastics present in human lungs, blood, breastmilk and other tissues.  

How microplastics enter the environment

The mismanagement of plastic waste, like roadside litter or overfilled trash cans, leads to plastic exposed to the elements—which eventually breaks it down into smaller pieces. Even the recycling system itself leads to plastics being improperly disposed of in some parts of the world. 

That’s if the material even makes it to recycling. The EPA estimates that less than 10% of plastic waste is actually recycled.3 Incinerating plastics is another common method of disposal that also can create microplastic particles.4 Burning plastic products, like the masks and other medical wastes used during the COVID-19 pandemic, can also lead to the environmental release of other hazardous chemicals such as dioxins, furans, and toxic metals, researchers said in a 2023 study.5

These are just a few highly visible ways that the tiniest forms of plastic can find their way into our environments—indoors, outdoors, and inside our bodies:

Primary microplastics

Primary microplastics like microbeads, which were banned from rinse-off cosmetics and certain drugs in the United States through the Microbead-Free Waters Act of 2015, can enter the environment through drains and pipes as people rinse away toothpaste, face washes, and other products containing them. Microbeads also are banned (wholly or in part by restrictions on trade or certain products such as cosmetics) in Canada, France, Italy, New Zealand, South Korea, Sweden, and the United Kingdom, while the European Union as of October 2023 is also proposing a ban on nurdles, the pellet-shaped precursor to many plastic products.

Wastewater treatment

The tiniest nanoplastics can not only pass through wastewater treatment systems, which are typically designed to capture larger solid waste, but can even negatively impact those systems’ performance.6 The wee particles can clog up equipment, at least one study found. At the same time, microplastics that make their way through these treatment systems will often end up in rivers and streams or eventually reach the world’s lakes and oceans. In some cases, plastics congregate along currents creating garbage islands like the infamous Great Pacific Garbage Patch.

The most common type of waste found in the environment is cigarette butts, which include plastic fibers.

Airborne pollutants

Scientists have found microplastics in the air in both outdoor and indoor settings. Those airborne particles also pose a risk to public health and the environment.7 Outdoors, these pollutants can come from road dust produced by the slow wearing of tires, which can also accumulate on land and in nearby waterways. 

Microplastics can also accumulate indoors. Most humans spend upwards of 90% of their lives inside their homes, which is why Robert C. Hale, an environmental chemist and professor at the Virginia Institute of Marine Science, says indoor plastic pollutants such as household dust, or debris from decaying carpet underlayment, are especially worrisome. One study linked an increased risk of illness during COVID-19 and particulate matter pollution, which Hale notes may indicate that breathing in microplastics could possibly increase people’s risk of respiratory illness.8

Plastic production 

The production of plastics themselves, whether macro or micro, is also problematic. Plastic materials are derived from fossil fuels like petroleum, and are a major source of greenhouse gas emissions that are driving climate change. According to a 2019 study published by the Center for International Environmental Law, the production and incineration of plastic in 2019 alone added more than 850 million metric tons of greenhouse gasses to the atmosphere. That’s the same amount of emissions from nearly 200 coal-burning power plants.

The biggest plastic polluters

The biggest plastic polluters aren’t individuals—even if blame seems to fall that way. Here’s what groups are making the biggest stink in the world of plastic production and pollution:

Plastic manufacturing 

Worldwide, companies produce about 400 million metric tons of plastic waste annually, the majority of which “ends up in landfills or as unregulated waste,” according to the United Nations.9 Half of those products are designed to only be used once. About 36% of plastic products are used for packaging, including wrappers, bottles, bags, and straws. The most common type of waste found in the environment is cigarette butts, which include plastic fibers. Over time, all of these plastics will eventually break down into smaller and smaller pieces.

Clothing and textiles

Clothing items—especially “fast fashion” items made for short-term use—are made from synthetic fibers like nylon and polyester, which are actually plastic. Poorly made clothing can shed those fibers when washed, and the wastewater from our washing machines will eventually reach waterways.10 


The fishing industry is a major contributor to marine plastic pollution, as an estimated 640,000 metric tons of fishing lines, nets, traps, and other gear is lost in the waves each year.11 A 2019 study out of the United Kingdom even found that synthetic rope used in maritime activities may contribute a “substantial amount of microplastic contamination” by releasing fragments as the ropes are hauled in the ocean.12


Farming equipment—such as irrigation pipes, plastic coverings, and greenhouses—can also decompose and leave microplastics. Using “treated” wastewater sludge as fertilizer on agricultural land also can lead to microplastic pollution, points out environmental chemist Hale. Those pollutants can reach waterways during storms and rain events.

The environmental consequences of microplastic pollution

Scientific research on microplastics to date has largely focused on their existence and distribution, but in recent years we’ve begun to get a picture of the particles’ impact on human and environmental health.

The challenge with determining the impact of microplastics lies in the fact that plastics are “extraordinarily diverse,” Hale explains. Not only are there about a dozen different kinds of plastic, which can be combined in a variety of ways, but products can also contain any number of other chemicals that give them color, stain-resistance, scents, non-stick properties, flame retarding abilities, and more. Many of those chemicals, such as flame retardants and per- and polyfluoroalkyl substances (PFAS), have been found to be harmful and or have a connection to certain cancers, endocrine disruption, impacts to immune and reproductive systems, and more.

Some types of plastic do break down more easily into microplastics than others, but everything will become microplastic eventually.

There is little concern about bioconcentration or biomagnification (when pollutants become more concentrated or toxic as they move up the food chain, as was the problem with pesticides like DDT) with microplastics themselves, Hale says. But there could be a concern about the chemicals added to plastic products that are released into the environment as well.

Are certain kinds of plastic more likely to become microplastics?

Some types of plastic do break down more easily into microplastics than others, chemist Hale says, but everything will become microplastic eventually. Polyurethane foam typically used in cushioning, for example, is relatively fragile. When exposed to sunlight, it becomes very brittle and can fragment into microplastic pieces in a matter of days. On the other hand, products made from some polyester polymers, such as the polyethylene terephthalate (PET) used in many plastic bottles, can take hundreds of years to degrade.

While bottles and roadside trash may be more at the forefront of discussions regarding plastic pollution, it’s important to understand that chemical composition and form of the plastic itself have incredibly important roles to play, says Hale.“Plastics are not just a single thing,” he explains. “It’s like saying people are all the same. They’re all varied. They’re all different. The repercussions of interacting with different people is enormous. The repercussions of interacting with different plastics is enormous.”

Size also matters. The smaller a plastic particle, the easier it can fit into small spaces—including across cell membranes and into sensitive places like gills and lungs. Smaller items can also be transported more easily. And, unfortunately, the scientific community still faces limitations when it comes to measuring the smallest of microplastics, Hale says.

How a person can minimize microplastic pollution

The best way to minimize microplastic pollution is to avoid purchasing new plastic items, especially single-use plastics like disposable bags, bottles, plates, cups, containers, and straws.

National nonprofits like Break Free From Plastic also call for corporate responsibility in campaigns aimed at curbing plastic pollution at the point of production. Engaging in activism, like getting involved in campaigns that call out or boycott companies for their contributions to plastic pollution, is another way to make an impact. Beyond Plastics, based in Vermont, is another project pursuing both policy changes and grassroots advocacy to address plastics pollution that is looking for people to get involved by starting local affiliates in their own neighborhoods. Other environmental advocacy groups, such as the Sierra Club, may also have local options on how to impact change in your city, town or state.

Can microplastic pollution be cleaned up or remediated?

Unfortunately, says Hale, once microplastics enter the environment, it’s almost impossible to clean them up. The solutions largely lie in making sure they don’t end up on the land or in waterways in the first place.

Regulations and policies

Experts have called on waste management officials to implement policies and strategies to address the problem, such as preventing plastic use or waste in the first place and implementing better recycling initiatives.

In the United States, there are no federal regulations on single-use plastics, but some state governments, including California, Connecticut, Delaware, Hawaii, Maine, New York, Oregon and Vermont, have instituted consumer bans on plastic bags and other single-use items like plastic straws and styrofoam. According to Politico, more than 90 countries, including Panama, Tanzania and New Zealand, have similar bans on single-use plastic bags. In Karnataka, India, single-use plastics, from bags to spoons to cling film, are completely banned, according to Greenpeace.

Emerging solutions

There is a chance that innovative solutions could also one day help address plastic pollution. Researchers are exploring bio-based plastics, also known as bioplastics, and even enlisting microbes or other living creatures like to digest plastic products. But these methods could lead to a new kind of plastic degrading in the environment, or would provide a less-than-ideal product susceptible to deterioration.

  1. A growing plastic smog, now estimated to be over 170 trillion plastic particles afloat in the world’s oceans—Urgent solutions required, PLoS One, Mar. 2023 ↩︎
  2. A global perspective on microplastics, JGR Reports, Jan. 2020 ↩︎
  3. Advancing sustainable materials management, EPA ↩︎
  4. Is incineration the terminator of plastics and microplastics?, Journal of Hazardous Materials, Jan 2021 ↩︎
  5. Microbial strategies for degradation of microplastics generated from COVID-19 healthcare waste, Environmental Research, Jan. 2023 ↩︎
  6. Understanding the fate of nano-plastics in wastewater treatment plants and their removal using membrane processes, Chemosphere, Dec. 2021 ↩︎
  7. There’s something in the air: A review of sources, prevalence and behaviour of microplastics in the atmosphere, Science of the Total Environment, May 2023 ↩︎
  8. Air Pollution and COVID-19: The Role of Particulate Matter in the Spread and Increase of COVID-19’s Morbidity and Mortality, International Journal Environmental Research and Public Health, Jan. 2020 ↩︎
  9. Our planet is choking on plastic, United Nations Environment Programme ↩︎
  10. How fast fashion can cut its staggering environmental impact, Nature, Sep. 2022 ↩︎
  11. Perceptions of plastic pollution in a prominent fishery: Building strategies to inform management, Marine Policy, Jan. 2022 ↩︎
  12. Potential microplastic release from the maritime industry: Abrasion of rope, Science of the Total Environment, Jan. 2022 ↩︎