Microplastics in the Human Body Systems and the Conditions They Lead To
Microplastics in the Human Body Systems and the Conditions They Lead To
By: Parker Kiepke, Maria Benitez, Keily Zuniga
Introduction
It can be said that our planet is congested with plastic. Plastic has not only taken over land and water, but it has also infested living organisms. It created a chain of destruction that begins with marine life and makes its way to humans. The presence of microplastics in the human body can cause body systems to fail and not complete their tasks. This lack of efficiency can lead to the development of countless diseases.
The Immune System
Microplastics, can cause immunotoxicity, or adverse effects on the immune system (FDA).
Microplastics and Dendritic Cells:
Over the past few years, it has been discovered that microplastics can provoke immunotoxicity in several ways. Microplastics can enter the body through inhalation, digestion, or skin exposure (Skyes, Edward A, et al). When these microplastics are inhaled, they can be absorbed into lung tissues and cause a ruckus among immune system cells. Normally, phagocytes ingest pathogens to track their genetic information in the immune system. However, dendritic cells (types of immune cells) will engulf these plastics and aren’t able to break them down as if they were bacteria. This constant failure to break down particles from dendritic cells causes extreme inflammation, which can lead to several diseases such as cancer, heart problems, diabetes, and more (Yang, Wenji, et al).
Microplastics with Pathogens:
Microplastics themselves don’t even always directly cause the issue. A study was done that showed microplastics forming a biofilm on Helicobacter pylori, a certain type of bacteria. This immensely accelerated the bacteria’s infection rate and caused extreme inflammation of internal organ tissues, showcasing the damage microplastics can do in tandem with other antibodies. Another example of this is with SARS-CoV-2. SARS-CoV-2 has been shown to bind to microplastics to be used as a carrier. This not only assists the virus with transmission between organisms but can increase the infection by having easier intracellular transport within the organisms themselves. Microplastics may prevent pathogens by occupying virus binding sites (Yang, Wenji, et al). Despite this, microplastics still negatively impact the immune system overall. Some scientists argue that exposure to germs is crucial for immune development, and early microplastic exposure may weaken immunity (Thompson).
Microplastics and Neutrophils:
In fish, microplastics reduce neutrophil response and cause degranulation. Because of this, the fish’s metabolism, behavior, and disease resistance were all affected. In vitro, microplastics caused extreme mass death (50-97%) to neutrophil cells, and the microplastics were even rereleased from the dead cells. In vitro tests suggest microplastics may harm immune cells across organisms, causing further damage when cells die. In mice, a reduction of lymphocytes, white blood cells, and mature dendritic cells were seen. Some human tests were performed that resulted in an immune response, but it’s still unclear of the intricate cellular activities that occur with microplastics (Yang, Wenji, et al).
Conclusion:
Most of this research has been conducted over the last 10 years; these discoveries are pretty new. This shows that there is still much more to be found out about the effects of microplastics on the immune system and that even more adverse effects could be discovered. But it’s clear that microplastics trigger responses, and can have an incredibly strong toll on immune systems in several organisms. Damage to the immune system leaves organisms vulnerable to disease. This could lead to a plethora of diseases such as cancer, diabetes, COVID-19, coronary heart disease, and so much more which then could lead to extreme health issues and death. The long-term effects of microplastics on immunity remain unknown, but current findings suggest widespread use of plastics could severely harm immune health.
The Reproductive System
The reproductive system of the human body works together to sexually reproduce. Reproductive organs of the female body include the vagina, uterus, fallopian tubes, ovaries, and temporarily, the placenta. There is a higher chance for pregnancy during ovulation when an egg is released(Wilcox et al., 2000). Reproductive organs of the male body include the penis, scrotum, testes, epididymis, vas deferens, prostate, and seminal vesicles.
Microplastics and the Women’s Reproductive System:
The plastic we use on a daily basis disintegrates into particle-size plastic called microplastic. Microplastics can be found in the air, the water, and the earth. Microplastics enter the human body through air, food, and water. Once microplastics enter the human body through endocytosis of the M cells and get to the subepithelial dome, dendritic cells transport them to the lymphatic circulation(Ragusa, A., Et al., 2021). From here, the microplastics have easy access to the bloodstream. As this impure blood circulates throughout the body, it can make its way into the placenta through the spiral arteries.
An experiment was conducted using Raman spectroscopy to detect the presence of microplastics in a group of women’s placentas. The results from this experiment stated, “In total, 12 microplastic fragments (ranging from 5 to 10 μm in size), with spherical or irregular shape were found in 4 placentas (5 in the fetal side, 4 in the maternal side and 3 in the chorioamniotic membranes)...”(Ragusa, A., ET al., 2021). The different sizes, types, and toxins of these microplastics are foreign and unnecessary in the human body. Due to the size of the microplastic, it can reach even the deepest parts of the body's organs.
Today, measures have been set in place to reduce the risk of microplastics entering the body. Delivery rooms allow the use of cotton-based products and metal clippers during labor to reduce microplastic exposure (Ragusa et al., 2021). The placenta nourishes the developing fetus. Due to microplastics that have been found in the placenta, developing babies are at risk of developing preeclampsia and fetal growth restrictions(Ragusa, A., Et al., 2021). Preeclampsia occurs when a pregnant mother has elevated blood pressure and high levels of protein in her urine(Preeclampsia: Symptoms, causes, treatments & prevention., n.d.). This condition can affect the mother’s organs, such as the liver or the lungs, and the blood supply that is transported into the placenta. Also, certain substances that are released from microplastics are endocrine-disrupting chemicals. In other words, they hinder the hormones of the body. These chemicals can cause Intrauterine growth restriction, thyroid dysfunction, and neurological disorders(Street, M. E., Et al., 2020). All conditions could affect the child’s development and the mother's health.
Microplastics and the Male’s Reproductive System:
The scrotum houses the testes, essential for sperm production. Within these testicles in the seminiferous tubules, testosterone and other hormones cause the germ cells to turn into sperm cells (Experts, K. M. (Ed.)., 2023). A study found microplastics in semen and testis samples, with 0.23 particles per mL of semen (Microplastics Detected in Human Testis and Semen, 2023). The presence of these microplastics threatens spermatogenesis. In other words, it has been discovered that exposure to plasticizer BPA interrupts the first round of spermatogenesis and damages the formation of the blood testis barrier(D'Angelo, S., Et al., 2021). The purpose of the blood testis barrier is to prevent the interaction between sperm cells and the immune system. Damage to the blood-testis barrier can cause the sperm cells to enter the bloodstream encountering the immune system. The immune cells will not recognize the sperm cell and perceive it as a foreign cell. As a result, the immune cell will attack the sperm cell.
Microplastics also cause oxidative stress, leading to DNA damage and gene expression failure (D'Angelo et al., 2021). As a consequence, spermatozoa cells lack axonemal phosphorylation needed by the sperm tail and motility and viability of the sperm cell(D'Angelo, S., Et al., 2021).
Overall, one of the main outcomes of the damage caused by microplastics in the male body is infertility. Other conditions that can come to the surface are hormone or pituitary gland problems and genetic conditions that can lead to birth defects due to the lack of sperm cell count or the lack of motility and viability of the sperm.
Conclusion:
Taking action against microplastics is not only critical for the health of a person but also for future generations. The termination of microplastics will reduce the number of medical conditions future children will have to experience.
The Cardiovascular System
Microplastics pose significant risks to the cardiovascular system, which transports nutrients and oxygen-rich blood throughout the body. They can lead to increased blood pressure, myocardial infarction, and impaired heart rate. Microplastics in this system can pile up in the vital organs of the human body. After entering the body, they can take approximately 15 minutes to enter the bloodstream. Following the arrival of microplastics in the bloodstream, the bloodstream transports them to different areas of the body. The effects of microplastics in the human body depend on factors like size, shape, chemical composition, surface charge, and hydrophobicity.
Microplastics and The Heart
The most crucial factor of the cardiovascular system, the heart, is impacted by microplastics in many ways. Microplastics in the body can reach the cardiac tissue and cause structural and metabolic damage. They release toxic compounds like Bisphenol A (BPA) into the bloodstream, which can promote significant blood pressure issues and cardiovascular diseases. Blood pressure issues in this state are critical to be treated. These blood pressure problems, typically increased blood pressure, can cause an alteration in the cardiac sarcomeres. Sarcomeric dysfunction plays a vital role in reduced function in heart failure.
Increased blood pressure can also cause chest pain, which may signal potential health issues including the risk of a heart attack. Another problem chest pain can cause is an abnormal heart rate. One’s heart rate can either mean the heart is beating too quickly – tachycardia, or too slowly – bradycardia. The condition of abnormal heart rate is also known as arrhythmia. Untreated arrhythmia can damage the heart and other crucial organs, resulting in life-threatening issues like strokes, heart failure, or cardiac arrest.
All these conditions are the few that can occur as a result of microplastics in the heart. Although this is not every single one of them, a good portion comes from the elevated blood pressure that can happen once microplastics release toxins into the bloodstream.
Microplastics and Blood Vessels or Arteries
Microplastics can cause serious risks to the arteries and blood vessels in the body. As said before, toxic compounds from these microplastics come in contact with the bloodstream. But these toxins can also constrict blood vessels. The constriction of the blood vessels can lead to several severe conditions like a stroke, coronary artery disease, and aneurysms. When a blood vessel bursts or is blocked, this can result in not enough blood supply reaching the brain. Without an adequate amount of blood being transported to the brain, a stroke can occur, leading to brain damage, long-term disability, or even death.
The toxin, Bisphenol A can also eventually lead to an aneurysm. This happens when a blood vessel’s wall is swelling or has a present bulge. Most of the time, these complications are found in an artery rather than a vein. They can be located in many parts of the body, like the brain, aorta, intestines, kidney, spleen, and vessels in the legs. They are most common in the aorta, which carries oxygenated blood from the heart to the body. After an aneurysm, the blood vessels in the brain may contract and narrow, also known as vasospasm.
Another complication that can happen due to BPA is atherosclerosis. Atherosclerosis is when the arteries harden or thicken up. The hardening and thickening of the arteries are from plaque in the inner lining of the artery. This slow and progressive disease consists of plaque made up of fatty substances, cholesterol, cellular waste, calcium, and fibrin. Atherosclerosis can cause a heart attack, stroke, aneurysm, or a blood clot. These complications may be life-threatening or cause someone to have long-term complications.
Conclusion
Cardiovascular diseases are the most common way of death worldwide, and researching the impact of plastics on the body could save people from these diseases and save lives.
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