Microplastics: The Modern Day Boogeyman
Microplastics: The Modern Day Boogeyman
By: Evaney Soto, Maddie Brooks, Armin Abdollahzadeh
Introduction to Microplastics: Inputs and Accumulation
The rapid increase in microplastics in aquatic environments poses a multifaceted threat to marine ecosystems, human health, and the environment. Microplastics are regarded as a global issue due to their toxicity and denaturing effects on both humans and fish. Within the last decade, waste production has escalated drastically, resulting in the prevalence of microplastics in our world. When waste is dumped into the ocean, sea life consumes the microplastics, and then humans and other animals eat sea life. This creates a continuous cycle causing microplastics to travel from one living organism to another.
Microplastic pollution begins with the very convenient integration of plastic use into our lives. With such favorable properties, plastic is a highly utilized part of our everyday lives, and it proves to be very difficult to eliminate. Several diffuse and point sources contribute to the pollution that is destroying our oceans. However, it is not easy to identify the exact sources of most microplastic pollution. As far as we know, the bulk contributors to microplastic pollution are materials such as municipal debris (plastic bags and bottles), plastic pellets, personal care products containing microbeads, plastic running tracks in schools, rubber roads in cities, and vehicle tire wear (An, 1970). The debris accumulates in the ocean where it enters the ecosystem and harms the many species that reside there.
Microplastics can enter and harm an animal's system in several ways. Most tragically, the animal can accumulate so much plastic that the sheer amount of density in its gut ends up being fatal. The toxins attached to the plastic can also enter the animal through ingestion poisoning the related organs, leading to major discomfort and eventually death. Finally, the microplastics can also harm specific parts of the animal with toxins by adhering to different body parts that are not necessarily involved with the feeding process (Strokal, Avio). Due to their size and dimension, microplastics resemble many small planktonic organisms and other suspended particles like dirt. This factor makes them easily ingestible and very misleading for aquatic animals (Avio, 2017). When an animal ingests microplastics the physical material sits in their gut which can inhibit the functions of its body. When animals consume a significant amount of plastic it can cause them not to feel hungry, therefore making them unintentionally starve themselves. Larger pieces can also disrupt and cause harm to their intestinal tract blocking any excretions from leaving their body. As the plastic sits in their gut, the toxins associated with the “eco-corona” of the plastic travel into the surrounding tissues causing irreversible damage. The microplastics can also adhere to the body parts of animals leading to more potential absorption of toxins. A study done by the State Key Laboratory of Estuarine and Coastal Research at East China Normal University found that plastics are not only found in the gills of animals but also on certain bodily surfaces of different animals (Avio, 2017). All the different ways microplastics can present harm show us the grave danger posed to these aquatic creatures due to a fault that we humans are responsible for.
Microplastics in Depth
The studies on microplastics (MPs) have mostly taken place in laboratories, focusing on the physical and biological reactions within the organisms. The impact of microplastics on fish has become detrimental, leading to death. The fish used in the MP exposure tests came from multiple environments, with the majority coming from the sea. MPs can build up in the gastrointestinal system of fish after consumption, producing obstructions in the digestive tract and harming appetites (Wright). Fish are a significant source of protein for humans, and the presence of microplastics in seafood is extremely dangerous for those who consume it. Microplastics enter the intestinal system which has a toxicological effect that leads to swelling and blockage; as well as spreading to other parts of the body. Further studies show other factors that impact human health. Oxidative stress, consequent inflammatory, and cytotoxic impacts were thought to be the main effects of MP toxicity in inhalation exposure experiments. MPs can induce oxidative stress by creating oxidizing substances that connect to surfaces, as well as reactive oxygen radicals made by the host during the inflammation, posing danger to the lungs (Wright). Microplastics change the body’s metabolism and energy flow by altering metabolic enzymes. There is not enough research to determine how much it affects humans as their energy intake is higher than other creatures studied. Furthermore, the immune system can experience dysfunction, according to Farhat et al. (2011), chronic damage in cells, and the incorrect stimulation of immune cells may all contribute to MP-induced autoimmune disorders. Leading to the production of antibodies and self-antigens (Wright). The actual risk to the immune system has not yet been proven thus more research needs to be done. Microplastics can travel through the body's cardiovascular system which leads to respiratory high blood pressure. In vitro tests revealed that nanoparticle exposure can cause red blood cell coagulation and endothelium wall adherence (Wright). Not only can humans ingest microplastics but they can also be inhaled. There have been many studies that show there are MPs in the atmosphere (Blackburn, 2022). Prosthetics were also found to release microplastics in humans. There are limited studies on MPs on the wear and breakdown of joint replacement prostheses, however, one published in 2000, explains metallic and polyethylene particles from post-mortems in 29 patients (Blackburn, 2022). They found polyethylene particles in the para-aortic lymph nodes in 68% of 28 patients and in the liver or spleen of 14% of 29 patients. Where these microplastics are found depends on where the prosthetic is placed in the body. One case had granulomas formed in the liver, spleen, and abdominal lymph nodes in response to the wear from a hip prosthesis (Blackburn, 2022). Microplastics have become a problem everywhere and are now affecting humans physically, chemically, and psychologically because of the millions of plastic waste in the ocean and in landfills. As it affects aquatic environments it also affects the terrestrial systems.
The amount of plastic distribution has become concerning worldwide. Plastic pollution has been estimated to be composed of more than 5 trillion plastic pieces equal to some 250,000 tons in the global seas (Johnny, 2013). That explains how sealife consumes microplastics and gets stuck on the bigger pieces that have not degraded. The environment has suffered greatly, from pollution in oceans and air, leading to potential environmental disasters due to poor recycling rates and long durability of the waste. In addition, microplastics affect soil and plants. It's reported that the amount of microplastics in sewage sludge of wastewater treatment plants can be as high as 15,385 particles kg−1 (Johnny, 2013). It was estimated that about 63,000–430,000 and 44,000–300,000 tons of microplastics were released annually through the soil on farmland in Europe and North America (Johnny, 2013). Studies have also shown that oxidative stress also occurs in soils due to the microplastics. John A Glaser, who works at the National Risk Management Research Laboratory stated that one detrimental effect of microplastics could be the conveyance of absorbed pesticides or other toxic materials to susceptible organisms leading to cellular damage.
Toxins Attached to Microplastics and Their Effects
Through indirect and direct ways, marine debris is continuously accumulated throughout our oceans. Concerning plastic debris, these objects are like a forever lasting boogeyman that simply never goes away, even when you grow old enough to outsmart him. They degrade into smaller bits and pieces of fragmentations until the si unit for meters can no longer describe its granule size. The plastic becomes so small to the point where as humans, we are breathing in the smallest amounts of microscopic plastic debris. With all of these microplastics entering an animal's system, the toxins associated with them prove to cause the most damage. Due to plastic’s hydrophobic nature, plastics can easily absorb and host hydrophobic contaminants, as well as heavy metals, all of which pose a health concern for both aquatic animals and those who consume these animals. Some hydrophobic organic contaminants (HOCs) that are commonly found include polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides, and polychlorinated biphenyls (PCBs). They also accumulate heavy metals such as cadmium, zinc, nickel, and lead (Shah, 2017). Keep in mind, these are simply toxins that leach onto plastic, they are not the toxins found within plastic themselves. For example, Nonlyphenol, commonly found in water bottles and other common usage materials, is dangerous because it poses as an endocrine disruptor within the fish, which is problematic for their health, and the food chain (Wright & Kelly, 2017).
To begin, PCBs were originally banned before the 21st century; however, in recent years, studies have shown they have been increasingly present within our lakes, water supply, and oceans. PCBs are man-made industrial chemicals that truly have no origin from where they came. There are 209 different PCB compounds, in which all of them could be mixed into different combinations. Contaminated fish are a consistent source of PCBs in the human diet. These toxins are not dangerous in small doses, but over time, exposure to this chemical proves to be a possible carcinogenic, as it has cancerous effects on laboratory animals (“PCBS in fish and shellfish”).
Toxic metals commonly found within our waters, also have an alarming effect on our entire environment. The metals commonly found in our bodies of water include copper, nickel, zinc, cobalt, and cadmium. All of which pose risks to human health and aquatic health. To briefly mention the effects of metals on humans, they can decrease energy levels and cause significant damage to the functioning of the brain and other vital organs. Long term exposure to high concentrations of these metals can lead to a variety of neurological degenerative diseases such as Parkinson’s and Alzheimer’s. In addition, repetitive long term exposure to these metals could lead to potential cancer (Shah, 2017). In fish, their exposure to these toxic metals was observed in cells and the cells of these fish were essentially torn apart to shreds and deformed. These pictures speak for themselves and show how deadly the toxins found within our environment can be.
Solutions
Through environmental concerns and continued threats of microplastics, research is continuously being conducted to find solutions to reducing microplastics as much as possible. Some of these solutions include Upstream solutions that focus on preventing plastic from going out. As a replacement for conventional plastics, bioplastics have garnered significant attention due to their ability to biodegrade in the order of months or years, which can be used in packaging for food and other supplies (Thakur et al., 2018). Cardboard straws have become more common because of their ability to degrade faster. Composting is also a beneficial solution as biodegradable products are still being dumped in landfills. Wastewater treatments with new technologies have been shown to improve the removal of microplastics in water. Talvitie et al. (2017a) tested different types of advanced wastewater treatment technologies and found that membrane bioreactor (MBR) removed the highest percentage of microplastics during treatment at 99.9%, while rapid sand filter and dissolved air flotation could remove 97% and 95% of microplastics, respectively. There are already physical methods of removing plastic such as mesh nets, pumps, and other capturing devices but these are difficult due to the large amounts of plastic already present in the environment. With technology and new solutions, the waste production can be reduced.
Being educated on the different ways these toxins enter our environment and cause harm is the first step to addressing and identifying the big problems within waste management in society. When we can pinpoint major issues and recognize the detrimental effects we are causing to our own environment, we can begin to make decisions to induce a change. Making a difference all starts with initiation.
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