“The future is plastics.” The Graduate (1967)
Plastics truly are a wonder material. Cheap to make, incredibly malleable, you can make a zillion different kinds of things out of plastic, from billiard balls to thin films for shopping bags, to jet fighter canopies. It can be clear or colored, textured or flat, incredibly thin and flexible, or thick and rigid enough to be used for giant aquarium windows. It’s also easy to make plastic cheaply in vast quantities, which is what makes an entire plastics industry so successful, and such an unanticipated consequence.
Even though it might seem that plastics have been around forever, the reality is that plastics started becoming commonplace in the early 20th century. With the invention of Bakelite (1907) and then nylon, polyethylene, and polyvinyl chloride (1930s), plastics were everywhere, and investment in the development of plastic manufacturing was truly the future. Within a single generation, an entirely new material was everywhere and incredibly cheap. For a while, plastics were so inexpensive that the word “plastic” became synonymous with “cheap.” Plastic containers and gadgets were so inexpensive that they defined an entirely new world of disposability. They weren’t just cheap, but also hygienic and clean. Increases in efficiency in plastics production continued to drive the costs down and increase the range of products that could be made of plastic in one form or another.
The incredible disposability of plastics led inevitably to a waste management problem. Suddenly, after 70 years of plastic generation, in 1972 people started to notice plastic debris everywhere. [Ryan] Not only did it pile up, but larger chunks of plastic continuously broke down into pieces that couldn’t be easily collected. With little oversight, the plastics industry could operate without regard for the environmental impact of their products. By 1987, the first legislation was proposed to limit dumping plastics at sea: The Marine Plastic Pollution Research and Control Act ("MARPOL Annex V").
But by then, the plastic cat was out of the plastic bag. All of those straws, bags, bottles, food packaging, clothing and cellulose acetate cigarette filters were everywhere, often taking 1000 years to decompose. [Chamas] Roughly 6.4 billion cigarette filters—a cool 1.4 million pounds—are discarded each day, a major cause of plastic waste.1
Since the 1980s, we’ve come to realize that only around 9% of all the plastic ever made has been recycled. To get a sense of that number, you need to know that 8.3 billion metric tons (Mt) of virgin plastics were created between 1907 and 2015. [Geyer]
The scale and sweep of plastic in our living space is unlike anything else. You should know that a patch of plastic trash seven times the size of Great Britain swirls in the middle of the Pacific Ocean (“the Great Garbage Patch”). It’s made up of discarded fishing gear such as buoys, lines and nets along with plastic debris generated on land at marinas, ports, rivers, harbors, docks, and storm drains flowing into the sea. Plastic trash ranges size from miles-long abandoned fishing nets to micro-pellets used in cosmetics and abrasive cleaners.
Trash has always been with us, it’s the natural byproduct of civilization. But when disaster strikes, waste products are the only item that really goes up in volume because people have bigger issues to think about.
During the COVID pandemic, single use plastic products such as masks, gloves, aprons, sanitizer containers, etc.) were all important in protecting people from COVID exposure. The widespread use of personal protective gear caused a huge waste disposal problem. As a consequence, millions of discarded single-use plastics were added to landfills, adding a new stream of plastic disposals to an already strained system. [Benson] Estimates are that as many as 219M items were discarded each day in the US, and perhaps 703M per day in China and more in the rest of the world. A reasonable estimate would be that planetwide, we used and discarded 3.4 billion pieces of single use plastic every day weighing in at 1.6 tonnes / day.
What’s more, plastic waste floods the world’s rivers, beaches, ultimately spilling over the edges of landfills everywhere. The bigger problem (the smaller problem?) is that plastics break apart into smaller and smaller particles over time. Everything does—paper, steel, wood, steel—all of the construction materials we know break down into smaller and smaller pieces.
But unlike paper (which then biodecomposes) or steel (which rusts, turning into elemental iron by the action of bacteria or oxygen), or glass (which breaks down into something that looks and behaves much like regular sand), plastic just gets smaller until it’s smaller than microscopic in size. Microplastics are bits of plastic less than 5 millimeters wide (about the size of an orange seed), ranging down to 1 μm (1 micron) in length. (The smallest dust particle you can see is around 25 microns.) But that’s not the end of the process: these microplastics break apart into even smaller particles called nanoplastics that are between 1 nanometer (nm) and 1 micron (μm) long. For size comparison, 1 nanometer is the length your fingernail grows in 1 second while 5 millimeters is how long your fingernail grows in 6 weeks. At this size, they get carried all over the planet on the smallest breeze.
Microplastic and nanoplastic particles have been found in fruits and vegetables, having been absorbed by the plants’ roots and transported up to leaves and fruits. They have been found lodged in nearly every human organ—including being passed from mother to child through breast milk.
Microplastics can be found in the tissues of penguins in Antarctica, in the interior of the smallest of plankton, and in the plastic water bottles that we drink for the cleanest of clean. (That bottle of water you just drank has around 240,000 free floating plastic particles per quart (liter). [Qian]) Scientists have found microplastics at the bottom of the Marianas Trench (35K ft; 5.9K fathoms; 10.1K meters) and floating freely in the air at 30K feet (10K meters). The hypersuccess of plastics has made them truly ubiquitous—we’re swimming in a sea of plastic too small to touch or see. We breathe and drink nanoplastics constantly, there’s currently no effective way to avoid them.
We are quickly becoming partly plastic ourselves. With careful screening, it’s possible to find microplastics in human blood. [Leslie] In their study of microplastics in the human blood stream, Leslie et al. found that their study of a small set of donors, the average concentration of plastic particles in blood was 1.6 µg/ml. That’s a very small amount, but the big surprise is that they’re in the bloodstream at all. They get into our bodies by being breathed in, or through breaks in the skin, or by being eaten and then migrate across the gut wall. The researchers also looked for different kinds of plastic polymers and found traces of PET (type 1), polystyrene (disposable plates), and polyethylene (sandwich bags, plastic wrap, toothpaste).
Each of us ingest between 0.1 – 5 grams of plastic each week through what we eat, drink, and the air we breathe. [ Senathirajah ] To put it in perspective, a credit card is around 5 grams. Depending on your diet, you could be eating a credit card a week, or at very least, we all each around one credit card each year.
Microfibers are another kind of microplastics, but rather than tiny pellets of plastic, tiny fibers (mostly from clothing) are another kind of tiny pollution. They’re even a problem in science labs where microfibers are so ubiquitous that scientists have to go to extraordinary lengths to keep their spaces free of microfibers. If you collect fibers in the open air, you’ll find, as one study from the University of Paris discovered, in much larger quantities than you’d expect. On average one study collected 118 particles per square meter per day, ranging in length from five millimeters down to 100 micrometers, or the thickness of a sheet of paper. [Beaurepaire] These are the kind of microplastics we’re breathing into our lungs. In small amounts you don’t notice them, but in larger quantities, the plastic load builds up, and can cause significant inflammation in the airways. [Saha] Unsurprisingly, smokers have more microfibers than most people, and respiratory problems that go along with inhaling smoke AND tiny plastic fibers. [Pauly]
Since microfibers are created by ordinary clothing wear (you’re leaving a plastic microfiber wake behind you) and by laundering (especially during the abrasive action of drying clothes in a tumble dryer), it’s not too surprising that during the COVID pandemic, the number of airborne microfibers dropped dramatically. During COVID, one measuring site saw five times fewer fibers each day. With people moving around outside much less, and staying home move, clothing just became much less of a source. [Beaurepaire, 2024] But they’re still everywhere, from the air inside your home, to the farthest reaches of remote, windswept beaches in Ireland where you can pick up microfibers that have traveled from North American on the winds. [Roblin] Plastic fibers can travel a remarkable distance, sometimes many thousands of miles from their original source. [Xiao] [Evangeliou]
An unexpected source of plastic pollution comes from what we think of as “rubber” car tires. [Sutton] Perhaps surprisingly, tires today are made up of a blend of several different kinds of synthetic rubber blended with natural rubber, polyester, nylon, rayon, silica, carbon black and various chemicals to make the tire perform well on the road. Of course, as we drive, the tires wear down leading us to replace them every 50,000 miles (80,000 km) or so. It’s annoying to have to replace your tires, but what do you think happens to the tire surface as it wears down—that material doesn’t just disappear. Where does the rubber from the tires go?
As your car races down the road it sheds microscopic pieces of the tire surface onto the highway surface. Over the course of millions of cars, and some squealing tires shedding larger, obvious chunks of tire, that particulate matter accumulates on the roadbed before washing down into the nearest body of water. In San Francisco Bay, roughly 7 trillion microplastic particles per year flow into the Bay at a level that is around 300 times greater than the microplastic discharge from all wastewater treatment plants in the region, making car tires a major source of microplastics in the Bay. [Sutton] Some recent estimates point out that each person contributes 4.7 kg / year (10 pounds / year) just by driving on four rubber tires. [Kole] Even if you don’t have a personal car, when you’re transported by bus or plane, those tires wear down just as much as tires everywhere else.2
And, like other plastics, tire rubber causes behavior changes in animals, especially the small ones—when they ingest a fragment of rubber, it’s huge with respect to their size, so the chemical effects are more pronounced. The small critters tend to die more quickly (including being eaten more often because of changes to their swimming patterns) and have reduced reproductive success. [Cunningham]
Plastic particles also come from everyday paint, which is—not a real surprise—often made up of synthetic polymers that are essentially plastic in a spreadable form. For coloring, paint plastics often contain toxic metals as well making microplastic paint chips especially noisesome. Particles of paint account for more than half (58%) of all the microplastics that end up in the world’s oceans and waterways every year. [Paruta] [Turner] According to the researchers, 1.9 million tons of paint end up in our oceans and waterways every year, more than the other two most common sources of microplastics, textile fibers and tire dust.
Plastic waste on ocean floor. P/C SMR (via Pixahive)
Microplastic toxicity
As you might expect, nanoplastics and smaller microplastics can get everywhere in a body and cause all kinds of problems. Nanoplastics can invade the entire gut, alimentary canal, stomach, digestive glands, liver, pancreas, ovaries, blood, and lymph (need I go on?) causing all kinds of physical damage.
It’s clear that tiny plastic bits can cause big changes at the cellular level, with inflammatory responses throughout the body of animals that somehow consumes plastic particles. With longer exposure time to microplastics, granulocytomas (small clusters of white blood cells that form in response to an inflammatory agent) form as the body reacts to the foreign substance. [Khan]
What’s more, as the plastic particles get smaller, the bio-effects get more powerful. We know that particles between 50 and 100 nm can penetrate the cell wall of fungi and cause toxic problems. Perhaps most worrying, they can also cross the highly selective membranes of the brain with negative effects such as development delays, cognitive impairment, and neurodegenerative diseases. [Xiong] Microplastic exposure in both humans and test animals leads to gene expression changes, inflammatory and biochemical responses, and carcinogenesis.
In other words, they’re poisoning us and wreaking biological havoc. [Zhang] We inhale them, we drink them, we eat them. They leach unwanted chemicals into our bodies causing hormonal disruption, which in turn causes reproductive problems and an increased risk of certain cancers.
Hope?
Plastic particles are going to be with us more-or-less forever. What can we do about them?
There’s no simple, easy, or cheap solution. There are microplastics in your blood and floating freely in the oceans and the atmosphere. At this point, all we can to try and control this unanticipated consequence is by taking a multi-prong approach.
Reduce plastic use: This involves opting for reusable alternatives, choosing products with minimal packaging, and supporting policies that curb plastic production and consumption.
Improve waste management: Efficient waste collection, recycling, and proper disposal of plastic waste are crucial to prevent microplastic release into the environment.
More research: We need further research to understand the full extent of the health and environmental risks posed by microplastics and develop effective solutions to reduce the plastics we put into the environment and perhaps find a way to more effectively break down the plastic bits that are already out there.
Obviously, we should also be raising awareness of the plastic problem. People need to know about the issues and take grass-roots action. There’s nothing quite like informed consumers that can drive a change.
Another ray of hope comes from microbiology research into extremophiles—that is, critters that love to live under extreme conditions.3 For instance, Japanese researchers have found a kind of bacteria living in the bottom of a plastic-rich landfill that entirely plastivorous.4 Could this bacteria one day lead to a way to biodegrade our plastic waste? Perhaps, but it’s often a long road between seeing a plastic-eating bacterium in the wild and then being able to use that in a controlled industrial setting where it can process thousands of tons of plastic waste. It’s a great discovery, but worth noting that this bug only eats Type 1 plastic (PET), which is already fairly easy to recycle. We need bacteria that will digest Types 2-6 to have a more complete solution to plastic wastelands.5 [Bruanyi] [Yoshida, 2016]
Rule of Thumb: Anticipate the breakdown of your tech. Ask yourself these questions: Where does it go when it’s not wanted any more? Have you thought about it? What will you do with your hypersuccessful project leftovers?
======References=====
[Beauepaire 2021] Beaurepaire, M., Dris, R., Gasperi, J., & Tassin, B. (2021). Microplastics in the atmospheric compartment: a comprehensive review on methods, results on their occurrence and determining factors. Current Opinion in Food Science, 41, 159-168.
[Beauepaire 2024] Beaurepaire, M., Gasperi, J., Tassin, B., & Dris, R. (2024). COVID lockdown significantly impacted microplastic bulk atmospheric deposition rates. Environmental Pollution, 123354.
[Benson] Benson, Nsikak U., David E. Bassey, and Thavamani Palanisami. "COVID pollution: impact of COVID-19 pandemic on global plastic waste footprint." Heliyon 7.2 (2021).
[Bruanyi] Buranyi, Stephen. “‘We are just getting started’: the plastic-eating bacteria that could change the world” The Guardian, Sep 2023. https://www.theguardian.com/environment/2023/sep/28/plastic-eating-bacteria-enzyme-recycling-waste
[Chamas] Chamas, Ali, Hyunjin Moon, Jiajia Zheng, Yang Qiu, Tarnuma Tabassum, Jun Hee Jang, Mahdi Abu-Omar, Susannah L. Scott, and Sangwon Suh. "Degradation rates of plastics in the environment." ACS Sustainable Chemistry & Engineering 8, no. 9 (2020): 3494-3511.
[Crichton, M., 1969] The Andromeda Strain, Knopf Publishers.
[Cunningham] Cunningham, Brittany, Bryan Harper, Susanne Brander, and Stacey Harper. "Toxicity of micro and nano tire particles and leachate for model freshwater organisms." Journal of Hazardous Materials 429 (2022): 128319.
[Evangeliou] Evangeliou, N., Grythe, H., Klimont, Z., Heyes, C., Eckhardt, S., Lopez-Aparicio, S., & Stohl, A. (2020). Atmospheric transport is a major pathway of microplastics to remote regions. Nature communications, 11(1), 3381. https://www.nature.com/articles/s41467-020-17201-9.pdf
[Geyer] Geyer, Roland and Jambeck, Jenna R. and Law, Kara Lavender. (July, 2017). Production, use, and fate of all plastics ever made. Science Advances Vol. 3, no. 7, e1700782. https://www.science.org/doi/pdf/10.1126/sciadv.1700782
[Khan] Khan, A., & Jia, Z. (2023). Recent insights into uptake, toxicity, and molecular targets of microplastics and nanoplastics relevant to human health impacts. Iscience. https://www.cell.com/iscience/pdf/S2589-0042(23)00138-4.pdf
[Kole] Kole, P.J., Löhr, A.J., Van Belleghem, F., and Ragas, A., 2017. Wear and tear of tyres: A stealthy source of microplastics in the environment. International Journal of Environmental Research and Public Health 14(10): 1265. https://doi.org/10.3390/ijerph14101265.
[Leslie] Leslie, H. A., Van Velzen, M. J., Brandsma, S. H., Vethaak, A. D., Garcia-Vallejo, J. J., & Lamoree, M. H. (2022). Discovery and quantification of plastic particle pollution in human blood. Environment international, 163, 107199.
[Paruta] Paruta et al., Plastic Paints the Environment, Environmental Action 2022, ISBN 978-2-8399-3494-7 https://www.e-a.earth/wp-content/uploads/2023/07/plastic-paint-the-environment.pdf
[Pauly] Pauly, John L., et al. "Fibers released from cigarette filters: an additional health risk to the smoker?." Cancer Research 55.2 (1995): 253-258.
[Qian ]Rapid single-particle chemical imaging of nanoplastics by SRS microscopy. Qian N, Gao X, Lang X, Deng H, Bratu TM, Chen Q, Stapleton P, Yan B, Min W. Proc Natl Acad Sci U S A. 2024 Jan 16;121(3):e2300582121. doi: 10.1073/pnas.2300582121. Epub 2024 Jan 8. PMID: 38190543. https://pubmed.ncbi.nlm.nih.gov/38190543/
[Roblin] Roblin, B., Ryan, M., Vreugdenhil, A., & Aherne, J. (2020). Ambient atmospheric deposition of anthropogenic microfibers and microplastics on the western periphery of Europe (Ireland). Environmental science & technology, 54(18), 11100-11108.
[Ryan] Ryan, Peter G. "A brief history of marine litter research." Marine anthropogenic litter (2015): 1-25.
[Saha] Saha, Suvash C., and Goutam Saha. "Effect of microplastics deposition on human lung airways: A review with computational benefits and challenges." Heliyon (2024).
[Senathirajah ] Senathirajah, K., Attwood, S., Bhagwat, G., Carbery, M., Wilson, S., & Palanisami, T. (2021). Estimation of the mass of microplastics ingested–A pivotal first step towards human health risk assessment. Journal of Hazardous Materials, 404, 124004.
[Sutton] Sutton, Rebecca, Amy Franz, Alicia Gilbreath, Diana Lin, Liz Miller, Carolynn Box, Rusty Holleman, Keenan Munno, Xia Zhu, and Chelsea Rochman. "Understanding microplastic levels, pathways, and transport in the San Francisco Bay region." (2019).
[Yoshida] Yoshida, Shosuke, Kazumi Hiraga, Toshihiko Takehana, Ikuo Taniguchi, Hironao Yamaji, Yasuhito Maeda, Kiyotsuna Toyohara, Kenji Miyamoto, Yoshiharu Kimura, and Kohei Oda. "A bacterium that degrades and assimilates poly (ethylene terephthalate)." Science 351, no. 6278 (2016): 1196-1199.
[Turner] Turner, Andrew, Clare Ostle, and Marianne Wootton. "Occurrence and chemical characteristics of microplastic paint flakes in the North Atlantic Ocean." Science of the Total Environment 806 (2022): 150375.
[Xiao] Xiao, S., Cui, Y., Brahney, J., Mahowald, N. M., & Li, Q. (2023). Long-distance atmospheric transport of microplastic fibres influenced by their shapes. Nature Geoscience, 16(10), 863-870. https://www.nature.com/articles/s41561-023-01264-6
[Xiong] Xiong, F., Liu, J., Xu, K., Huang, J., Wang, D., Li, F., ... & Sun, R. (2023). Microplastics induce neurotoxicity in aquatic animals at environmentally realistic concentrations: A meta-analysis. Environmental Pollution, 318, 120939.
[Zhang] Zhang, S., Wang, J., Liu, X., Qu, F., Wang, X., Wang, X., ... & Sun, Y. (2019). Microplastics in the environment: A review of analytical methods, distribution, and biological effects. TrAC Trends in Analytical Chemistry, 111, 62-72. LINK
Each filter is around 0.1 grams. Or 640 million grams of discarded filters / day, which is 1.4 million pounds, 640,000 kg, or 705 tons / day.
When a plane lands, each tires loses around 1.5 pounds (0.68 kg) of rubber each time. When an A-380 lands, with its 20 tires in the landing gear, that’s 30 pounds (13.6 kg) of rubber on the runway every time. Airports have to check their runways weekly to see if too much rubber has accumulated, and when it does, they have to manually scrape it up and dispose of it all.
This is the kind of research that seems frivolous but can sometimes pay off handsomely.
See, for example, the plastivores work being done in Europe. This WHYY story goes into detail.
And, as always, we should be thinking about the potential unanticipated consequences of these plastic-eating microbes. While it’s fictional, Michael Crichton’s novel, Andromeda Strain dramatically tells the story of a plastic-eating microbe that degrades plastics causing jet fighters and spacecraft to plummet from the sky. The book was written well-before the discovery of actual plastivorous bacteria. [Crichton, 1969]