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Plastics: In our land, water and food. Now our air.

By Stacy Gittleman

Benjamin Braddock, the protagonist in the classic 1967 movie The Graduate, played by a young Dustin Hoffman, is led to the poolside for a private conversation by Mr. McGuire during his college graduation party to discuss his future. The middle-aged man, putting his arm around Benjamin, had one word of advice: plastics.

Mr. McGuire was, unfortunately, a little too accurate in his prediction. Plastic, that flexible, moldable, and infinitely useful product that was ironically first hailed by conservationists as a consumer goods material substitute for ivory and then as a lighter, cheaper substance that could save our forests from becoming shopping bags, are today in nearly every product we purchase.

We've learned the most harmful and the fastest accumulating plastic has become our consumer addiction to single-use plastics found in wrappers, water bottles, and iced coffee cups. According to the Sierra Club, single-use plastics account for 50 percent of the 380 million tons of plastic waste we throw away every year. Used sometimes for only a few minutes, they are not as recyclable as we have been led to believe and have the staying power of decades. Only about nine percent of what we separate from our garbage is in actuality recycled. The rest winds up in conventional landfills or is exported to Asian countries like Thailand and then burned.

While the environmental problem of plastics has been recognized for decades, scientists are now realizing that plastic waste has become a problem in the earth’s atmosphere.

According to data from the United Nations, there have been 8.3 billion metric tons of plastic produced since 1950. By 2050, the mass of plastic in the oceans will outweigh that of fish. Instead of disintegrating back into a natural state, these materials, made from fossil fuels, break into ever smaller parts that are becoming the planet’s least understood pollutant in terms of how it impacts organisms and human health: microplastics.

According to the National Oceanic and Atmospheric Administration (NOAA), microplastics are any bits of plastic as small as five millimeters in size – about the footprint of a pencil eraser. Although not yet widely quantified in research, the substances’ even smaller relative, nano plastics, can be as tiny as one micron and are extremely difficult to detect without advanced scientific equipment. Microplastics come in two categories: primary sources such as tiny pellets or beads once found in personal care products or craft or decorative glitter strewn on a tablecloth to add sparkle at a party, or secondary sources such as the shreds of plastic torn off from a strewn grocery bag or water bottle. Over time, bits of these improperly disposed plastics that we see strewn along the side of a road, or tangled in a tree, make it into a body of water. Waves and currents break down the plastic into ever smaller parts that are ingested by fish and wildlife and ultimately humans.

It has been widely studied that plastic has infiltrated the planet’s rivers, lakes, and oceans. Environmentalists have warned us all about plastic islands the size of Texas floating in the middle of the Pacific Ocean. According to a 2018 European study, most of the seabeds all over the world and in the Mediterranean Sea are made of plastic.

Some microplastics are so small and light that they adhere to salt and other sea minerals and get swept up by wind currents. So in only the last five years, scientists have begun to turn their research efforts to begin to examine the most remote places around the globe, and are discovering that microplastics are being carried great distances, over continents via wind currents. There are now discoveries of microplastics massing in Arctic ice, the Sahara Desert and falling as snow on European mountain tops.

In one 2019 study published in Nature Geoscience, scientists over a five-month period traced and discovered the presence of microplastics on the peaks of the Pyrenees Mountain Range between France and Spain 100 kilometers from the nearest city. In their samples, the authors each day found remnants of single-use plastics. They determined that daily, an average of 365 plastic particles sifted down from above into the square meter surface of the collection device. If comparable quantities of airborne microplastic fall across the rest of the country, the researchers estimate roughly 2,000 tons of microplastic cover France each year.

In another 2019 study, Italian researchers from the University of Milan reported that a sample from an alpine glacier, containing 131 to 162 million pieces of microplastics, was carried and deposited by the wind and was at the same level of concentration as what has been found in sediments in the oceans or coastal plains.

A July 2020 study from the Norwegian Institute for Air Research estimated that about 10 million metric tons of microplastics are emitted into the atmosphere each year, which is similar to the annual amount of black carbon emissions.

An April 2020 study by researchers from China and Scotland discovered that microplastics coming in a variety of shapes and polymers were falling over European and Asian skies regardless of the weather. The abundance of particles in the air, per square meter per day included: 118 (Paris) and 275 (Hamburg); in Dongguan, China, the number of particles ranged from 175 to 313 particles. This study also revealed that the air quality in terms of microplastic levels in these cities was even worse indoors than outdoors. Samples of indoor microplastics were likely sourced from fibers shed from carpeting, furniture, and synthetic clothing.

In the United States, the few studies conducted on atmospheric microplastic distribution that have garnered attention have been under the leadership of Janice Brahney, associate professor of watershed sciences at Utah State University.

In her June 2020 paper, Plastic Rain on Protected Areas of the United States, Brahney and her team of researchers collected samples in 11 national park locations in the western United States over 14 months. They analyzed the number of particulates of microplastics from wet samples of rain and snow and dry samples of soil. The researchers estimated that between 1,000 and 4,000 tons fall into these supposedly pristine regions each year – equal to 100 to 400 million plastic bottles. 

Realizing that the title of her paper may have been a bit misleading, Brahney clarified that plastic is constantly falling out of the sky even without precipitation.

“Actually, more plastic falls from the sky when it is sunny outside,” noted Brahney. “When it rains, the rain scrubs the atmosphere below the cloud level, but we also detected plastics moving much higher in the atmosphere, above the clouds, so there is plastic falling from the sky pretty much all the time.”

In April 2021, she was the lead author of Constraining the Atmospheric Limb Of The Plastic Cycle, published in the Proceedings of the National Academy of Sciences of the United States of America. Brahney and her research team examined how plastic fragments between five millimeters and one micron (to put a micron’s size in perspective, the thickness of one strand of human hair is 70 microns) – are emitted into the atmosphere and end up traveling around the globe in a process akin to the water cycle. They concluded that most atmospheric plastics are derived from legacy plastic production that over the decades has accumulated in the environment. Roads and rural stretches of highway dominated the sources of microplastics (84 percent), followed by oceans (11 percent), and agricultural fields and dust emissions (five percent).

At the current rate of a four percent increase of plastic production per year, the researchers concluded that understanding the sources and consequences of microplastics in the atmosphere should be a priority.

“If you’ve ever been traveling on a dusty road or highway, and that car in front of you kicks up a plume of dust off their tires – some of that dust going into the air could be microplastics,” Brahney said. “We did not find cars in cities churning up a lot of microplastics. because there tends to be a lot of buildings and disruption of wind flow and so there’s not a lot of wind energy to move plastics high enough into the atmosphere to be transported a long distance. Our sampling sites were in very remote parts of the country far away from any large city.”

Brahney said while microplastics that fall with rain or snow are sourced locally, those that fall with no precipitation may have drifted as far away as another continent, propelled by the oceans and then wind currents.

Brahney explained that microplastics are not part of the water cycle because they cannot evaporate into a gaseous state. However, the same churning of the seas that aerosolizes sea salt also does the same to ocean microplastics.

“When you have a lot of wave action that moves tiny liquid droplets into the atmosphere and then dries out, whatever was in that droplet – be it salt or a microplastic – becomes a particulate in the air. That is the mechanism that is producing microplastics from a marine environment,” she explained.

Brahney concluded that plastics are creating their own lifecycle in their permanence in the environment. Though she said there have been researchers who have hypothesized that microplastics were becoming so tiny that they could become aerosolized, studies, such as the ones coming from her lab, are just now trying to catch up with those predictions.

“Most countries measure atmospheric particulates that are smaller than 10 microns and stop there because that particle size is harmful to human health,” she said. “It is what creates that visible haze. But most of what’s floating around in the atmosphere is much larger than 10 microns and that is not monitored anywhere but in the United States right now, and that monitoring is happening through my lab, and only in discreet locations and finite amounts of time.”

Timothy Hoellein, associate professor, Department of Biology at Loyola University Chicago, studies the uptake of microplastics in aquatic food webs in urban settings and how microplastics are processed through raw sewerage wastewater treatment plants in and around Chicago. Though study samples show that 99 percent of the microplastics found in raw sewerage are filtered out of the wastewater effluent, the captured microplastics in that sewerage sludge either end up in a landfill or are spread on agricultural fields as biosolids for growing crops. Unlike other pollutants such as mercury or lead, the many kinds of plastics in our waste are not registered as a regulated pollutant, so plastics can go out into the waste stream, and the wastewater treatment plants are still operating under the law without committing any environmental violations.

Backing up Hoellein’s findings is a 2020 report from the Sierra Club, which estimates that each year, 107,000 to 730,000 tons of microplastics are dumped onto agricultural soils in the U.S. and Europe. From that statistic, 21,249 tons of microplastics are released to U.S. agricultural lands from sewage sludge annually. The Sierra Club goes on to state that the physical and chemical properties of microplastics can potentially change the soil composition, disrupt natural microbial communities, damage the digestive tracts of earthworms, alter water holding capacity, and other properties that influence plant development.

“A wastewater treatment plant that is releasing microplastics is not doing anything wrong,” said Hoellein. “While it is true that wastewater systems retain a lot of that microplastic from initially going into the wastewater effluent going back into our streams and waterways, where that filtered microplastic goes, we don’t know. It goes into a landfill or is spread on a field as fertilizer, it goes back into the environment anyway. It’s not a closed loop system. “

Hoellein said though it may seem like a small dent, individuals can lessen the impact of microplastics by making sure there is less litter along roadsides or coastal areas, which can prevent bottles and bags from breaking down and floating off into the air.

“Picking up litter really makes an impact. But ultimately, we need to think longer term about the lifecycle of the plastic materials that we produce and the pathways these plastics get into our waste streams and ultimately the atmosphere.”

Hoellein said he is encouraged when scientific discoveries lead the public to a change in policy such as the implementation of the Microbead-Free Waters Act of 2015. Under the law, manufacturers had until July 1, 2017, to stop the manufacture of products and July 1, 2019, to stop their delivery.

Academics urge that more funding and better methodology needs to show how, or how much, these microplastics are getting into our bodies, either bu digesting or inhaling them, and how they are affecting our health.

Like any dust particles, the human pulmonary system has ways of ridding the body of most microplastic invaders by sneezing or coughing. Scientists however are concerned that the smallest nano plastics – those below five microns – are capable of getting stuck within lung tissue. While most larger particles can be extracted from the lungs when we cough or sneeze, if microplastics become encapsulated in mucus that we swallow, there is a potential for them to enter our digestive system.

In 2019, a study by engineers from Denmark and China simulated the anatomy and function of a lung within a mechanized mannequin within three apartments in a 24-hour period and found that up to four percent of all the particles the mannequins inhaled were made of polyester.

In an April 2021 Florida State University study, a team of researchers exposed human lung tissue in a petri dish with bits of polystyrene microplastics, the materials most used in disposable cutlery and takeout boxes. They found that though the plastic didn’t cause cell death, it caused some abnormalities in cellular activity. After only a few days, the cell’s metabolic processes had slowed down, cell proliferation was inhibited, the shape of the cell morphed and the delustering had occurred.

Professor Donna Kashian at Wayne State University’s Department of Biology said while studies such as these does not mean there is a direct correlation between inhaling microplastics and serious diseases like cancer, microplastic atmospheric distribution is something the general public should be concerned about because of its ubiquitous nature.

“When we talk about other contaminants, such as overuse of pesticides or lead in our drinking water, these are problems but not as visible as the number of plastics that are getting thrown out and winding up in the environment and the atmosphere,” said Kashian. “All you have to do is take a walk in your neighborhood, go to a beach and see that plastic Starbucks cup in the sand, or the use of disposable plastics at the next event you attend, and know it is breaking down and getting into the food chain to the point that we could be consuming about a credit card’s worth of microplastic each week.”

Kashian said the microplastics-cancer connection is a difficult one to answer.

She described cancer as a vicious beast. There are a multitude of toxins in the environment that may trigger cell receptors to cause cancer to emerge and grow. While some carcinogens trigger cancer receptors in some people, it may not do so in others, and some cancers can skip generations within a family, she clarified.

“It is difficult to pinpoint and affirm that (microplastics) cause (cancer). There has been research done to see how cell tissue reacts and is triggered by exposure to plastic, but you don’t know how long a timeline that takes or the amount of the material that will trigger it, so it is very complex,” she said.

Other studies examined how microplastics can affect the health of infants and human fetuses.

A recent study by researchers from Trinity College Dublin discovered how those high levels of microplastics are released from infant-feeding bottles during the sterilization and preparation of baby formula. The research, published in the Nature Food journal, found that polypropylene infant feeding bottles can release up to 16 million microplastics and trillions of smaller nano plastics per liter. The authors recommended that infant formula should be prepared with water at 70 degrees in a non-plastic container, cooled to room temperature and then transferred into a high-quality plastic sterilized infant feeding bottle.

In a more disturbing study that was published in January 2021 by Italian researchers, about a total of one dozen microplastic fragments between five to 10 nanometers were found in placental tissue donated by six consenting pregnant women. The tissue specimens were viewed through micro spectroscopy and most likely originated from polymers that are used for man-made coatings, paints, adhesives, plasters, finger paints, cosmetics and personal care products.

Weighing in on these studies is University of Michigan Professor Allen Burton, who teaches a graduate level course, Microplastics: Human and Environmental Risks. He has researched the impacts of microplastics in marine environments since 2013. He attributed the reason for a low number of studies on atmospheric microplastic due to the bigger perceived threat to human health from marine microplastics that are disrupting the food chain. Burton said the greater potential danger from microplastics are those we ingest and drink, not those that we inhale.

Allen said in spite of the FSU research that directly aggravated human lung tissue with microplastics, he believes it is not conclusive that microplastics can cross into the lung tissue with enough frequency to trigger cancer.

According to Burton, concentration of combustion related particulates – bits of carbon that contain known carcinogens – pose a far greater health concern and are more abundant in the air than airborne microplastics.

“If you compare the number of microplastic particles that would be in the air, say, in an urban environment, versus these other really combustion-related particles, it would be much smaller,” he said. “Just as with most chemicals, the primary concern is how humans and other organisms in the food chain ingest microplastics through water or food, so that’s where most of the funding for research is happening right now.”