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Feb 1713 min read

Microplastics: Tiny toxic timebombs


Image by 5Gyres, courtesy of Oregon State University

 

Plastic begets microplastics, and you can’t have one without the other.

 

Microplastics are pieces of plastic less than 5 millimeters long. Smaller still are nanoplastics, and at less than 1μm (micrometer) they’re small enough to enter individual cells and cross the blood-brain barrier. (1μm is about 100 times thinner than a sheet of paper.) Microplastics are classified as either primary or secondary:

  • Primary microplastics include nurdles, the small plastic pellets that are the raw material used to manufacture plastic products. Other examples include the abraded particles from car tires and the fibers resulting from the manufacturing, washing, and wearing of synthetic textiles such as polyester, nylon, acrylic, PVC, spandex, and rayon. Also in this category are glitter, sequins, microbeads used in cosmetics, granular materials in artificial turf, peeled or flaked paints and coatings, nail polish, and cigarette butts.

  • Secondary microplastics are formed by the breakdown of larger plastic items in the environment, primarily discarded fishing nets and ropes, plus plastic packaging, including grocery bags, beverage bottles, and takeout containers. Breakdown occurs when ultraviolet radiation from the sun causes plastic to become brittle and susceptible to erosion, especially when the action of waves causes flakes to shear off into the environment. The Great Pacific Garbage Patch exemplifies these conditions.

 

Nurdles account for 18% of microplastic mass in the ocean, tire particles account for a whopping 78%, and fibers from synthetic textiles, along with secondary microplastics from personal care products, account for 4%. While this last number may seem small, it translates to 144,000 trillion particles. In total, the ocean is estimated to contain 1,344,010 trillion pieces of microplastic. But the ocean contains a mere 26% of microplastic in the environment, whereas 63% ends up in soil and air. My brain is flummoxed by these millions of trillions.

 

The total amount of plastic ever made exceeds 9.1 billion tons, and half of that was created in the last 13 years. Plastic production currently amounts to 400 million tons per year and is expected to double by 2040. (In the US, production is backed by government subsidies using our own taxpayer money.) About 3.3 million tons of primary microplastics enter the global environment every year, in addition to 5.8 million tons of larger plastic items that will break down over time to become secondary microplastics.

 

Toxic relationships

Concern over microplastics is mounting for several reasons, although the sheer volume should be reason enough. Microplastics are being found pretty much everywhere scientists look, from the great heights of Mount Everest to the murky depths of the Mariana Trench. Due to their small size and light weight, microplastics are easily transported through air and water, or through a combination of both in the way of clouds. When it rains, it pours…microplastics. With atmospheric winds and ocean currents they travel vast distances. Not only are microplastics inherently toxic but they become more toxic as they age, leaching their own hazardous chemicals and attracting others, along with heavy metals.

 

In water, plastic acts as a magnet for toxic chemicals, becoming increasingly more toxic over time. Many toxic chemicals are hydrophobic, meaning they repel water. When these chemicals come in contact with plastic they readily bind to the surface. These chemicals include polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphnenyls (PCBs), phenol A, and pesticides—all of which are exceedingly long lived and linked to hormone disruption, reproductive disorders, and certain cancers. Other surface contaminants include heavy metals such as copper, vanadium, mercury, lead, and cadmium. As the surface concentration builds, the microplastic can become up to a million times more toxic than the surrounding water. Studies strongly suggest that these weathered microplastics are neurotoxic substances that affect brain health: Testing on living mice and human tissue samples showed increased inflammation and cell death in the brain.


In the history of environmental toxicology, early concerns were usually born out. – Mark Taylor, chief environmental scientist at the Environmental Protection Authority in the Australian state of Victoria

Microplastics on the menu

Much like PFAS (forever chemicals), microplastics persist in the environment—plastic never fully decomposes, it just gets smaller—and they bioaccumulate, meaning contamination levels build up in an organism (ourselves included) as microplastics are ingested, inhaled, or absorbed. Biomagnification intensifies the contamination: Microplastics move up the food chain as the “big fish eat the little fish.” The food chain in this case includes not just fish, but plants and all forms of protein.


"Big Fish Eat Little Fish" by Pieter Bruegel the Elder

 

In a 2024 study by the Ocean Conservancy and the University of Toronto, microplastics were found in 90% of protein samples that included seafood, chicken, pork, beef, tofu, and plant-based meat alternatives. Chicken breasts, pork loin chops, and tofu had the lowest averages. The highest averages were found in samples that had undergone the most processing: chicken nuggets, fish sticks, and plant-based meat patties. Contamination was consistent, regardless of brand or store where the samples were purchased. In a 2020 study published in Environmental Research journal, results showed for the first time that microplastics are taken up by crops. The study included apples, pears, broccoli, lettuce, and carrots from multiple farms and stores. Microplastics were found in all varieties, with the highest concentrations in apples and carrots.

 

The best way we can tackle microplastics in food is by supporting large-scale action to prevent microplastics from entering the food system to begin with. Advocating for policies that reduce the amount of plastics being produced and prevent microplastics from entering our lives is going to be the most effective way to take action." – George Leonard, chief scientist at the Ocean Conservancy

 

A typical meal, however, has fewer microplastics than a bottle of water. A 2018 study by State University of New York in Fredonia tested 259 bottles of water from 11 brands across nine countries. The study found that 93% contained microplastics with an average of 325 particles in every liter. (This infographic shows the results for each brand.) But it gets worse: A 2024 study by Columbia University found that bottled water can contain 10 to 100 times more plastic than previously estimated, attributed to nanoplastics that previously went undetected.

 

Tap water is a far better choice than bottled, but it’s not exempt from contamination. A 2018 study by Penn State Behrend University tested 159 samples from 14 countries and found microplastics in 81% of the samples. Contamination was higher in developed nations, averaging 6.85 particles per liter compared to 4.26 in less developed nations. Contamination was highest in the US at 9.24 particles per liter. If it’s in the water, it’s in the beer: The same study found microplastics in the samples of all 12 beers tested.

 

It’s estimated that we consume about a credit card’s weight in plastic every week, although that statement is contested. The National Institute of Health estimates that we consume at least 50,000 particles a year. Based on their 2024 study on proteins, the Ocean Conservancy estimate could be as many as 3.8 million particles, depending on contamination and consumption rates. While scientists debate the estimates, the fact remains that we consume large numbers of microplastics.

 

Some microplastics pass through our digestive tract undigested—they’ve been found in stool samples from people in 8 countries. Those that remain in our bodies can translocate—move from one part of an organism to another. Microplastics have been detected in human lungs, blood, heart tissue, hair samples, fingernail clippings, testes/semen, breast milk, and placentas. It’s not yet known if microplastics cross over to the fetus and affect fetal growth and later development.


Another estimate the scientists can debate over: We breathe in about 272 particles a day, adding up to 99,000 particles a year. Individuals with higher levels of exposure—fossil fuel workers, plastic producers, and people living near plastics production and disposal sites—experience higher rates of certain cancers, respiratory disease, and pregnancy and birth complications.

 

Precautionary principle: When an activity raises threats of harm to human health or the environment, precautionary measures should be taken even if some cause and effect relationships are not fully established scientifically. –Science and Environmental Health Network, 1998

 

By studying animals, we often observe cause and effect relationships that can translate to our own species. Microplastics weave themselves into the gills and digestive tracts of fish and cause scar tissue in the stomachs of birds. They can affect feeding, growth, and reproduction in animals that filter seawater or sediment for food. The impact on larger animals, humans included, is limited since most studies are done on dead animals and sometimes span decades. A 2023 study by Duke University assessed 32 whales, dolphins, and seals that had either been stranded or harvested between 2001 and 2021. Samples were taken from blubber, melon (whale’s forehead), acoustic fat pads (jaw), and lung tissues, all of which serve vital functions. Microplastics were found in 64% of the blubber samples and 100% of all other tissue samples. Mounting evidence indicates that bioaccumulation threatens the function of vital tissues regardless of species.

 

Microplastic pollution from beginning to no end

Microplastic pollution occurs throughout the plastic lifecycle. Nurdle loss occurs early in the lifecycle during polymer production and product manufacturing, yet most notably during transport, where accidental spills have caused trillions of these toxic pellets to pollute oceans and coastlines, disrupting marine life and fishing industries. Fragments, flakes, and powders in these early stages create micro-/nanoplastic pollution that is both airborne and in wastewater. During production and manufacturing, additional pollutants result from chemical additives, including stabilizers, softeners, plasticizers, colorants, flame retardants, and fillers. Examples include bisphenols, alkylphenols, perfluorinated compounds (PFAS, aka forever chemicals), brominated flame retardants, dioxin, phthalates, lead, and cadmium. These additives can leach out of plastic when exposed to weathering and heat, and most are linked to various cancers, genetic mutations, reproductive and developmental disease, hormone disruption, and ecotoxicity.

 

After the production, manufacturing, and transport stages comes usage, and during this stage of the plastic lifecycle most microplastic pollution is created, most notably from tires, synthetic textiles, and mismanaged waste.

 

The four tires of a standard car shed 1 trillion particles for every kilometer (.6 miles) driven. Electric vehicles, being heavier and creating more torque, shed around 20% more. These particles are small enough to pass directly through the lungs into the blood and can cross the body’s blood-brain barrier. In general, heavier trafficked roads have higher concentrations of microplastics—not just from tires but also from the erosion of road markings and brake pads.

 

Tires are made from a synthetic rubber that contains up to 2500 chemicals and over 400 chemical compounds, many of which are harmful to human health. Growing evidence links these particles to myriad health issues, including kidney and liver damage, respiratory problems, immune deficiency, endocrine disruption, reproductive abnormalities, and cancers. When ingested by marine animals, these toxic particles can cause neurological disorders, behavioral changes, and abnormal growth. One chemical in particular, an antioxidant called 6PPD, is used to slow cracking and degradation. When exposed to ozone in the atmosphere, it becomes 6PPD-quinone, which is highly toxic to fish. Concentration from stormwater runoff can kill fish after just a few hours of exposure. A 2020 study by the University of Washington uncovered the issue when investigating why large numbers of coho salmon were dying in the Pacific Northwest.

 

Microplastic pollution from synthetic textiles is largely the result of fast fashion, which applies not just to apparel but also to our homes made fashionable with throw blankets, pillows, bedding, and rugs. Today 60% of textiles now incorporate synthetic materials. Synthetic textiles are often cheaper to produce than those made from natural fibers, and they have the added appeal of chemically engineered features like softness, wicking, flexibility, and stain resistance. (Hello, yoga pants and stretchy jeans.)

 

On the downside, a single load of laundry can release several million synthetic microfibers into the wastewater. Factors include fabric type, mechanical action, detergent, temperature, and wash cycle duration. These fibers can also contain toxic fabric dyes, anti-wrinkle agents, and flame retardants. Some governments are putting forth legislation that would require new washing machines to include devices that capture microfibers. France has already approved the requirement; Oregon, Ontario, and the European Union are planning similar measures. Governor Newsom of California vetoed such a bill, stating that the cost to the consumer would be too high. (The Ocean Conservancy wrote the governor after finding the cost to the consumer would be $14-$20 per machine. A fraction of the cost of after-market filters.) While capture and responsible disposal of these fibers is better than releasing them in wastewater, environmentalists are advocating for a wholly sustainable approach to how we make, clean, and dispose of clothing. The environmentalists are on the right track: High levels of airborne microfibers in textile plants damage workers’ lung cells, and half the fibers released from clothes result simply from wearing them. 

 

Whether from tires, textiles, or other commercial, industrial, or consumer goods, more than 10 billion tons of mismanaged plastic waste will be dispersed in the natural environment by 2050. Every year, the US sends 1 million tons of plastic waste overseas to developing countries that mismanage more than 70% of their own plastic waste. The plastic is often burned in open pits, sending microplastics and toxic chemicals into the air, creating hazardous conditions for surrounding communities. Sometimes the waste is unintentionally burned, as was the case when the world’s largest heap of discarded clothing went up in flames. Mismanaged waste also includes litter, and much of that ends up in lakes, rivers, streams, and eventually the ocean. Low-density particles float and high-density particles sink, ensuring that species of all types have an equal opportunity for mistaking it as food. For a sobering look at mismanaged waste around the world, see this gallery of images on the United Nations website.

 

At the “end” of the plastic lifecycle comes managed waste, which includes recycling and landfilling. Despite low recycling rates—9% worldwide and 5% in the US—a single recycling facility produces 3 to 6.5 million pounds of microplastic a year, depending on what type of filtering is used, if any. Between 6 to 13% of the plastic that enters a recycling facility becomes microplastic. Before the plastic can be melted down into pellets for reuse, it’s sorted and shredded, creating high levels of airborne microplastic particles. Throughout the process the plastic is washed multiple times. Particles in the wastewater end up being extremely small and difficult to filter. In a 2022 study, filtering was able to capture particles larger than 50μm (1/2 the thickness of a sheet of paper), but most particles were considerably smaller: 95% were under 10μm and 85% were under 5μm. Depending on the facility, wastewater goes directly into groundwater or to a sewer system that leads to a water treatment facility. In either case, microplastics end up in water used for drinking or irrigating crops. In the case of the water treatment facility, microplastics also end up in the filtered sewage sludge that will then be used to fertilize crops.

 

Soil samples from a long-running UK study show that microplastic pollution has risen sharply in the past 50 years and is much higher in fields treated with fertilizers (both organic and inorganic). Microplastics in soil affect porosity, aeration, pH, organic matter, microbial diversity, and nutrient content, and of course bring a bevy of chemical pollutants. Microplastics also affect the diversity of soil microbes and their metabolic activities. In short, microplastics are a threat to soil ecosystems.

 

Ironically, after we pay the price of toxic air, water, and soil, recycling brings us back where we started with more toxic little nurdles.


It seems a bit backward, almost, that we do plastic recycling in order to protect the environment, and then end up increasing a different and potentially more harmful problem.” – Erina Brown, bioresources consultant & PhD student in microplastics research

In the US, plastic recycling rates have been decreasing since 2018, and in 2021, 85% of plastic waste was sent to landfills. By 2050, global landfills will hold 13.2 billion metric tons of plastic. Little research has been done on the effects of microplastics in landfills, and microplastics aren’t listed as a pollutant in the landfill regulations of any country. Landfill conditions create microplastic pollution through accelerated plastic fragmentation and degradation. Landfill conditions also create leachate and gases. Leachate is produced when water percolates through waste deposits, and gases are primarily methane and carbon dioxide but also toxic VOCs (volatile organic compounds). Both the leachate and the gases become vehicles for microplastic pollution. Leachate enters the environment through leaks and through discharge to water treatment facilities. Plastic emits VOCs—possibly throughout its lifespan—and as it degrades, its surface-to-volume ratio increases, and it emits more VOCs.

 

A 2022 study found that the concentration of microplastic in landfills is higher than in sediments, sewage sludge, and agricultural soil. The same study found that the majority of microplastics in groundwater comes from landfills and the main causes are surface runoff, discharged liquid waste, open dumping, and open burning. It ended with the following statement:

 

The landfilling of plastics should be avoided by implementing strategies to prioritize the reduction, recycling, and conversion of waste into energy, and by campaigning to change consumer behaviour, in particular by avoiding the purchase of short-lived products, such as single-use plastics. – I. Wojnowska-Baryła, K. Bernat, M. Zaborowska, et. al. 2022

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Actions you can take to minimize risk

While we don’t yet fully understand the harmful effects of microplastics, we can be certain that reducing exposure is beneficial. And since most exposure occurs at home, you have options to maintain a healthier home environment.

 

  • Minimize the use of non-essential plastic.

  • Choose clothing with tightly woven fabrics over loosely woven fabrics that are fluffy or fuzzy. Along those same lines, reconsider stuffed animals made from fluffy synthetic fur.

  • Opt for natural fabrics like wool, cotton, or linen.

  • Wash clothes less often, and to reduce shedding, wash full loads, use cold water, use less detergent, use shorter wash cycles, use a front-load washer, and air-dry clothes.

  • Reduce microfibers in laundry waste water by using a washing bag or installing an external filter for your washer.

  • Reduce consumption of processed and packaged foods and drinks.

  • Minimize the contact of hot foods with plastic, such as boil-in-the-bag meals, food-grade nylon liners for baking pans and slow cookers, and takeout food containers.

  • Don’t consume hot liquid that has come in contact with plastic (e.g., plastic coated paper cups).

  • Switch to a tea brand that doesn’t use plastic in their bags, or use loose-leaf tea instead.

  • Choose tap water over bottled.

  • Use a water filter. (Although, most home water filters are usually plastic and will shed microplastics as they degrade over time. I've got my eye on a plastic-free Berkey filter once they're back in stock.)

  • Vacuum often since microfibers accumulate in dust and carpets shed fibers from daily use.

  • Wet-mop hardwood and laminate floors.

  • Avoid heavily trafficked roads when possible, especially when walking, running or cycling.

  • Check out my recommendations for more sustainable products.

 

Sources


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