The Microplastics Enigma

Image: SIV Stock Studio/Adobe Stock microplastics in glass of water
Microplastics are proliferating nearly everywhere on earth, even in the most remote parts of the planet where human activity is practically non-existent. Where are they really coming from?

News of microplastics being found in the most remote areas on earth – places where humans rarely travel – has many scientists scratching their heads. The logical answer is that plastic items somehow are breaking down into smaller and smaller pieces in a rather short period of time and blowing around the world on the jet stream. That undercuts a pet theory of the anti-plastics crowd, which preaches that plastics in the environment last for hundreds of years before breaking down in any significant manner. The microparticles end up in places where you would never expect to find them, including on top of the Himalayas. Microplastics are ubiquitous in the soil and oceans.

A paper by Igor Catic, Professor Emeritus of Mechanical Engineering and Naval Architecture and Chair for Polymer Processing at the University of Zagreb (Croatia), and Aleksandra Mihajlovic of the Society of Plastics and Rubber Engineers, Belgrade, Republic of Serbia, titled “Plastosis, Adiplastosis and Oceans,” looks at the proliferation of microplastics and the adverse effects these tiny particles can have on human health. “From an extensive analysis of the term ‘microplastics’ conducted for the [aforementioned] text, ‘What Is Plastosis?’ by Svet Polimera, which served as the basis” for this recent paper, “it can be concluded that there is no single definition of microplastics. That is why only a practical one is mentioned. The particle size of microplastics is between 100 nm and 5 mm.”

Catic and Mihajlovic next address the two forms in which microplastics appear — primary and secondary. “Primary micro plastics are particles that are released directly into the environment — into soil or water — and make up about 16% of total microplastics. They may come from intentionally added fertilizer additives; plant protection products and detergents; microspheres used in cosmetics; industrial abrasives used for sandblasting, etc. According to the European Chemicals Agency and the PlasticsEurope Association, the deliberate production of micro plastics thus defined is less than 0.1% of total plastics production,” they note.

Most of the primary microplastics released into the environment in the EU come from washing textiles and [a]brasion wear of rubber tires (about 500 thousand tons per year), which could be called a land trace of microparticles, according to Catic and Mihajlovic, to differentiate them from particles derived from marine coatings to protect hulls from fouling and corrosion. Research conducted at the University of Oldenburg in Germany “suggests that microparticles formed by the separation of layers of protective coatings against fouling and corrosion of the ship’s hull could be most prevalent in the seas.

“It was found that polyethylene and polypropylene microparticles from packaging plastics are more prevalent in areas near the coast,” making up “only a third of the collected particles. The rest, especially those collected in the open ocean, are particles of polyvinyl chloride (PVC), acrylate, and polycarbonate,” said the paper by Catic and Mihajlovic.

“Secondary microplastics make up 84% of the total microplastics and are formed by the fragmentation and weathering of larger plastic objects (bags, bottles, etc.), especially in seawater. More research is needed to improve the understanding of the sources and impacts of microplastics, including the environmental and health effects, and to develop innovative solutions to prevent their spread,” write Catic and Mihajlovic.

Aerosols riding the jet stream?

An article in the Cornell Chronicle dated April 12, 2021, “Atmospheric travel: Scientists find microplastic everywhere,proposed that plastics cycle through the oceans and roadways and, if tiny enough, can become microplastic aerosols, which ride the jet stream across continents. The authors of the article, Natalie Mahowald, Cornell’s Irving Porter Church Professor in engineering, and lead author Janice Brahney, Utah State University Assistant Professor of natural resources, believe this is one answer.

“We found a lot of legacy plastic pollution everywhere we looked; it travels in the atmosphere and it deposits all over the world,” Brahney said. “This plastic is not new from this year. It’s from what we’ve already dumped into the environment over several decades.”

Results from their study, “Constraining the Atmospheric Limb of the Plastic Cycle,” suggest that atmospheric microplastics in the western United States are primarily derived from secondary re-emission sources. From December 2017 to January 2019, researchers collected atmospheric microplastic data from the western United States, where 84% of microscopic shards came from road dust, with cars and trucks agitating the plastic. About 11% entered the atmosphere from sea spray, and 5% was derived from agricultural soil dust.

“We did the modeling to find out the sources, not knowing what the sources might be,” said Mahowald, a fellow at the Cornell Atkinson Center for Sustainability. “It’s amazing that this much plastic is in the atmosphere at that level and unfortunately accumulating in the oceans and on land and just recirculating and moving everywhere, including remote places.”

The Guardian posted an article on Aug. 13, 2019, about US Geological Survey Researcher Gregory Wetherbee finding “multicolored microscopic plastic fibers as well as beads and shards in rainwater samples collected from the Rocky Mountains. “I think the most important result that we can share with the American public is that there’s more plastic out there than meets the eye,” Wetherbee said in the Guardian’s article. “It’s in the rain, it’s in the snow. It’s part of our environment now.”

Yes, it is. But there is still the question of how it’s getting in all of these places all over the earth. According to the abstract for an American Chemistry Society (ACS) paper, “Ice Nucleation of Model Nanoplastics and Microplastics: A Novel Synthetic Protocol and the Influence of Particle Capping at Diverse Atmospheric Environments,” little is known about airborne atmospheric aerosols containing emerging contaminants such as nano- and microplastics.

According to the ACS paper, “stable plastic hydrosols were synthesized and characterized using three different types of plastics. The ice nucleation efficiency (INE) was investigated in both normal and synthetic seawater to mimic environmental ice nucleation. Among the three tested plastic precursors — LDPE, HDPE, and PP — polypropylene produced the highest particle density with narrow particle size distribution.”

The INE was altered based on the various sizes, shapes, surface charges, and electronic behaviors of the plastic nano- and microparticles. Also examined were the effects of environmental factors, such as particle acidity and temperature, on ice nucleation. Four types of capping were used on the surfaces of nano- and microplastics to investigate how the plastics act to nucleate ice when mixed with different particles.

Airborne nano- and microplastics may act as ice nucleating agents, which is any agent in the atmosphere that promotes the formation of ice crystals. Such agents can be minute solid particles, such as dust or other airborne particulates, and large molecules, including nano- and microplastics in the atmosphere. How do they get into the atmosphere?

Ice nucleating agents such as nano- or microplastics could be blown there on the jet stream, as the Cornell paper suggests. But what about higher up in the atmosphere – even in the stratosphere – where ice crystals form? There is one proposal I will make that some are considering as an ice nucleating agent, with the possible result of spreading polymer nano- and micro particles into the atmosphere: Ongoing climate geo-engineering.

Climate geo-engineering in war and peace

Climate geo-engineering is the ability to change weather patterns to create rain or snow when and where needed or to induce drought and destroy an enemy’s economy, as government experiments in the 1950s onward showed. Operation Popeye, for example, was a five-year cloud-seeding operation to lengthen Vietnam’s monsoon season and destabilize the enemy. Weather modification in warfare has since been banned by the United Nations under the Environmental Modification Convention.

However, over the past nearly three decades, there has been an increase in geo-engineering to modify weather for peaceful ends, such as putting a cap on global warming, known as Stratospheric Aerosol Injection (SAI), aka Solar Radiation Management (SRM), as a means to block the sun’s radiation and cool the atmosphere, thus reducing global warming. Often mistaken for condensation trails, these trails are different in that they linger and spread, often for many hours, until the once-blue sky is white and the sun is dimmed.

Utibe Effiong and corresponding author Richard L. Neitzel, writing for Environmental Health in a paper published on Jan. 18, 2016, “Assessing the direct occupational and public health impacts of solar radiation management with stratospheric aerosols,” looked at the health impacts of the chemistry in geo-engineering, which they defined as “the deliberate large-scale manipulation of environmental processes that affect the Earth’s climate, in an attempt to counteract the effects of climate change." Neitzel is affiliated with the Department of Environmental Health Sciences, University of Michigan, in Ann Arbor, MI.

“Injecting sulfate aerosol precursors and designed nanoparticles into the stratosphere via SRM, has been suggested as one approach to geoengineering. Although much is being done to unravel the scientific and technical challenges around geoengineering, there have been few efforts to characterize the potential human health impacts of geoengineering, particularly with regards to SRM approaches involving stratospheric aerosols.”

Effiong and Neitzel note that a “wide range of particles could be released into the stratosphere to achieve the SRM objectives of scattering sunlight back into space. Sulfates and nanoparticles currently favored for SRM include sulfur dioxide (SO2), hydrogen sulfide, carbonyl sulfide, black carbon, and specially engineered discs composed of metallic aluminum, aluminum oxide, and barium titanate.”

So how would polymeric nanoparticles work in a geo-engineering application?

Polymeric nanoparticles (NPs) are “particles within the size range from 1 to 1000 nm and can be loaded with active compounds entrapped within or surface-adsorbed onto the polymeric core,” according to a paper published Aug. 25, 2020, “Polymeric Nanoparticles: Production, Characterization, Toxicology, and Ecotoxicology,” by Aleksandra Zielinska, et al. “The term ‘nanoparticle’ stands for both ‘nanocapsules’ and nanospheres, which are distinguished by the morphological structure.”

These polymeric NPs have great potential for “targeted delivery of drugs to treat disease,” which also means they can be produced to contain the chemicals required for geo-engineering. These NPs have the advantage of controlled release, which would be beneficial in the geo-engineering process.

According to the European Commission Recommendation 2011/696/EU (REACH), nanomaterials are defined as “natural, accidently formed or produced material containing particles, in the unbound state, as an aggregate or as agglomerate. In this case, 50% or more of the particles have one or more external dimensions in the size range of 1 nm – 100 nm.” In REACH, the nanomaterials are treated like other chemicals, as substances, although there is no explicit reference to nanomaterials.

Catic and Mihajlovic define a disease created by polymer nanoparticles as “microplastosis” (similar to the term “asbestosis” for the disease caused by asbestos).

Plastic is an inert material, explain Catic and Mihajlovic, and “there are a wide range of properties that characterize microplastics, such as size, shape, chemical composition, color, hydrophobicity, etc., that could harm by the impact of particles on cells and tissues. Adverse effects on all organisms exposed to microplastics can be divided into two groups — physical and chemical impacts. Physical impacts relate to particle size, shape, and concentration of microplastics, and chemical to hazardous chemicals (e.g., monomer residues, polymer additives) associated with microplastics.”

Using satellites to track microplastics

An article from NASA’s news site on June 21, 2021, “Scientists Use NASA Satellite Data to Track Ocean Microplastics from Space,” explained that scientists from the University of Michigan have developed an innovative way to use NASA satellite data to track the movement of tiny pieces of plastic in the ocean. These microplastics form when “plastic trash in the ocean breaks down from the sun’s rays and the motion of ocean waves. These small flecks of plastic are harmful to marine organisms and ecosystems,” said NASA. “Microplastics can be carried hundreds or thousands of miles away from the source by ocean currents, making it difficult to track and remove them. Currently, the main source of information about the location of microplastics comes from fishing trawlers that use nets to catch plankton and, unintentionally, microplastics.”

The first thing that the proliferation of microplastics — not nanoplastics, which are too small to trap in fishing nets — shows us is that traditional plastic breaks down rather quickly. This is in contradiction to the oft-heard claim that it takes hundreds, even thousands, of years for plastic items to break down in the environment. Since plastic in the environment has only been a problem for the past few decades, we have actual proof through soil samples that plastic breaks down rather quickly in the environment. Second, nanoparticles of plastic are found in places where few humans go, such as remote geographic locations, whereas microplastics are found in the soil and waterways.

Geo-engineering using nanoparticles of plastic to carry the chemicals required to create the cloud film and manage solar radiation is called nano-geo. The benefit according to a paper, “Nanotechnology Geoengineering: An Upstream Technology Assessment of Two Converging Technologies,” by Lucas G. Hollenkamp from May 2, 2010, is lower cost in mitigating the earth’s heat caused by greenhouse gas (GHG) emissions than through attempts to reduce CO2 by expanding forests or ridding the world of fossil-fueled vehicles and moving toward electric. The latter would require large-scale, consistent, and reliable electricity that presently can only be produced by natural gas, coal, or nuclear power plants.

Alan Robock, Professor, Department of Environmental Sciences, School of Environmental and Biological Sciences, at Rutgers University, testified at a Congressional hearing before the Committee on Science and Technology, House of Representatives, at the 111th Congress, first and second sessions Nov. 5, 2009, Feb. 4, 2010, and March 18, 2010. Robock noted in his address that he has studied the effects of volcanic eruptions for 35 years, and has performed “climate model simulations of what would happen if we put the equivalent of one Mount Pinatubo volcanic eruption every four years.”

Mount Pinatubo in the Philippines erupted on June 15, 1991, and was the second largest volcanic eruption in the 20th century (Novarupta in Alaska in 1912 was the largest). Robock believes that sulfur dioxide (SO2) or sulfur particles in the atmosphere would be a viable method to provide SRM. However, he posed several pertinent rhetorical questions to the Congressional panel: “What temperature do we want the planet to be? Do we want it to stay constant? Do we want it to be at 1980 levels; do we want it at 1880 levels? And who decides?”

Because of its reflective properties, SO2 is a very effective SRM method. This is evidenced by intense volcanic activity, such as when Mount Tambora in the Dutch East Indies erupted on April 10, 1815, and did such an effective job of dimming the sun that 1816 was known as the “year without a summer in the northern hemisphere.” This came at a time when the northern hemisphere was just beginning to come out of the “Little Ice Age,” and North America and Europe were already seeing colder than normal temperatures.

Robock is convinced that reflective sulfur particles put into the stratosphere would mitigate the sun’s radiation enough to cool the climate, and in 2014 he produced a paper, titled “Stratospheric Aerosol Geoengineering,” in which he noted the “large volcanic eruptions” that “inject massive amounts of sulfur dioxide (SO2) into the stratosphere.” But how to get these particles there, when currently “only volcanic eruptions . . . are strong enough to get sulfur into the stratosphere” and have an impact on climate?

Polymer nanoparticles could be helpful in getting reflective particles into the stratosphere, but at what cost to human and animal life? Nietzel and Effiong note that due to “atmospheric and gravitational deposition, large-scale population exposures to atmospherically injected SRM materials will almost certainly occur after their deployment. Population exposures also could occur through injection of food and water contaminated with deposited particles, as well as transdermally.  . . . Stratospheric injection of sulfur dioxide and black carbon has already been modeled to analyze potential deposition of sulfate and soot . . .” and has been determined through models that the “intentional addition” of these materials “will exacerbate adverse health effects already resulting from unintentional release at ground level.”

The fragmentation of ocean plastics into microparticles, along with the possibility of plastic nanoparticles being put into the atmosphere in SRM testing, being ingested by marine life and, thus, by humans who eat them present health dangers to the food chain. As Catic and Mihajlovic note in their paper on plastosis, “nanoplastics and microplastic particles most often enter the human system by ingesting contaminated foodstuffs.” While the “human excretory system is expected to remove up to 90% of the ingested microplastics” . . . it is estimated that nanoplastics would more easily enter the cells.

Data lacking on impact of plastic particles on human health

“Potential environmental and health risks for humans being caused by microplastics are relatively new areas of research, and there is currently a high degree of uncertainty about this issue,” note Catic and Mihajlovic. “The risk is a function of hazard and exposure (dose). The dangers that plastic [particles] pose to the environment vary depending on the size of the plastic particles and the size of the organism. . . . The extent to which microplastics in certain foods harm human health is a matter of debate. Given the widespread use of plastic materials in everyday life, microplastics from food and beverages is probably only a minor route of exposure for human beings.

“The estimated daily amount of microplastics ingested by food and drink in an adult is 2 microns, according to data from the World Health Organization (WHO). Quantitative data on human exposure to microplastics through diet are not yet available, and there is still no legislation on microplastics and nanoplastics in food. Based on the available data, there are large gaps in the knowledge about the intake and fate of plastic particles of micro dimensions and nano dimensions in humans and their impact on human health,” said Catic and Mihajlovic.

Microplastics are prolific in the environment, which proves that even traditional polymers break down rather quickly. As for polymer nanoparticles, their use is being demonstrated in many applications, including drug delivery in humans and the possibility of chemical delivery in geo-engineering experiments. While there is concern for the health of the environment as more of these polymer nano-particles are found in the soil, remote mountaintops, and almost every waterway where few actual plastic products are located, it is obvious these polymer nano-particles are coming from somewhere — including, perhaps, the atmosphere.

Catic and Mihajlovic conclude that the presence and effects of plastic residues are being increasingly investigated. Most research has focused on micro-plastics, but few reports suggest whether plastic fragments in the <100 nm size range can be formed in aquatic environments, and then in humans, as well.

“In general, there is a lack of the results of in-depth studies of the impact of these particles on human health and the environment. Therefore, the aggressive attack of the environmentalists, emphasizing the impact of plastic particles on the health of human beings, is unjustified. For the moment, there is not enough evidence about their impact on the health of human beings,” write Catic and Mihajlovic.

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