The Silent Threat – the Impact of Microplastics on Human Health

Microplastics, tiny particles measuring less than 5 millimeters in diameter, have become a pervasive and concerning environmental issue. These minuscule plastic fragments result from the breakdown of larger plastic items or are intentionally manufactured for use in products like cosmetics, clothing, and packaging. While the impact of microplastics on marine life and ecosystems has been widely acknowledged, their potential threat to human health is now under scrutiny. In this article, we delve into the ways microplastics may affect human health and explore their potential impact on vital organs, including the lungs, heart, and kidneys.

Microplastics in Human Body

Braun et al. and Ragusa et al. presented the first proof of Microplastics existence in the human placenta in 2021. After then, identifying and characterizing the loads of Microplastics in various human organs, tissues, and fluids became a “challenge.” The placenta, lungs, liver, blood, heart, human bodily fluids and kidneys have all been the subject of numerous research.

Studies on Microplastics in humans have been conducted using a variety of techniques. First, in order to reduce contaminations, plastic-free sample handling procedures have been implemented and refined (e.g., glass jar and containers and handling samples under laminar flow hoods). Various sample pre-treatments have been devised to allow for sample digestion (mostly using KOH and H2O2) and then enable the examination of Microparticles.

The fact that Microplastics have been found in internal fluids, tissues, and organs, supporting the findings of MP bioavailability and deposition in the human body, is more concerning. On the one hand, biochemical changes and toxicity in this research have been studied, and links with illnesses have been looked at in light of these current results.

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Effects of Microplastics on Inhalation and Respiratory System

One of the primary concerns surrounding microplastics is their ability to become airborne and subsequently be inhaled by humans. Studies have found microplastic particles in air samples, indicating that they can travel through the atmosphere. Once inhaled, these particles may potentially lodge themselves in the respiratory system. While the long-term effects are still not fully understood, there is growing evidence that links exposure to airborne microplastics with respiratory issues such as inflammation and reduced lung function. The potential for microplastics to exacerbate pre-existing respiratory conditions is a subject of ongoing research.

Research on occupational disease in the vinyl chloride and textile sectors supports inhalation as the intake route for airborne microparticles. Amato-Laurenço et al. showed that 13 out of 20 human lung samples have Microplastics in 2021. Distal and proximal areas of the left lung from people without smoking who had a standard coroner autopsy were used to gather all the samples. The majority of polymers identified by µRaman spectroscopy were PE and PP, with all particles measuring less than 5 µm and fibres varying in size from 8.1 to 16.8 µm.

Chen et al. conducted a well-executed investigation using 100 human lung tissue samples that had undergone pulmonary cancer surgery. They used µFTIR, LD-IR, and µRaman spectroscopy to study MPs. 65 microfibers total—24 MPs—were discovered in 46% of the normal tissues examined. The most prevalent fibre types identified were denim, rayon, cotton, and polyester. In the tumour tissues, they also discovered acrylic, phenoxy resin, and PET.

Microplastics in Cardiovascular System

Research has begun to explore the relationship between microplastic exposure and cardiovascular health. Studies on animals suggest that microplastics may contribute to oxidative stress and inflammation, both of which are linked to cardiovascular diseases. The particles’ ability to carry harmful chemicals and toxins adds another layer of concern, as these substances may have detrimental effects on the heart and circulatory system. Although more research is needed, the preliminary findings emphasize the need for a comprehensive understanding of the cardiovascular implications of microplastic exposure.

Using LD-IR, Yang et al. conducted an intriguing investigation that recently showed the existence of MPs in the human heart and surrounding tissues. 90% of the polymers were represented by PET and PU, and the majority of the Microplastics had diameters less than 50 µm. This study is particularly interesting since it examined the various cardiac system components—pericardia, myocardium, epicardial adipose tissues, and left atria appendages—individually in 15 individuals undergoing cardiac surgery. Additionally, blood samples were examined both before and after the procedure. While not present in every sample, MPs have been identified in each of the five categories of cardiac tissue.

The deposition of microparticles in the human circulatory system was the subject of additional research. Using µRaman spectroscopy, Wu et al. studied the presence of MPs in human artery thrombi. In their investigation, MPs were found in 16 of the 26 samples that were examined. Globally, 87 particles were detected, ranging in size from 2.1 to 26 µm. It’s interesting to note that the majority of the particles were identified as pigments; specifically, 21 particles were identified as being composed primarily of copper phthalocyanine.

Microplastics and Renal System

The impact of microplastics on the kidneys is an emerging area of concern. These tiny particles have been found in human urine samples, suggesting that they may be able to reach and accumulate in the kidneys. While the exact mechanisms and consequences are not yet clear, some studies on animals have demonstrated that microplastics can cause damage to renal tissues and disrupt kidney function. Researchers are investigating the potential link between chronic exposure to microplastics and kidney-related disorders, emphasizing the need for further investigation into this aspect of human health.

PS-NPs exacerbate lipopolysaccharide-induced apoptosis in mouse kidney cells by activating the oxidative stress–endoplasmic reticulum pathway, as demonstrated by Li et al. Additionally, Tang et al. show that oxidative stress, inflammation, and lipid disruption cause nephrotoxicity in mice. Following six weeks of exposure to PS-NPs, the murine renal index showed reduced kidney function due to tubular atrophy, glomerular collapse, and infiltration of inflammatory cells.

In 2017, Deng et al. conducted a groundbreaking study in which they used fluorescent microspheres measuring 5 and 20 µm to examine the toxicity and tissue accumulation of PS-MPs in mice. They showed how MPs might accumulate in mice’s kidneys. Furthermore, metabolomic analysis revealed altered lipidic, energetic, and oxidative metabolism in the findings.

Systemic Effects of Microplastics

Beyond specific organ systems, the presence of microplastics in the human body raises broader concerns about systemic effects. These particles can contain or absorb hazardous chemicals, including endocrine disruptors and carcinogens, which may be released upon ingestion or inhalation. The cumulative impact of these substances on overall health is a topic of ongoing research, with scientists striving to understand how chronic exposure to microplastics may contribute to various health conditions.

Studies have shown in human colon cancer cell lines, high concentrations of PE enhanced oxidative stress, particularly mitochondrial superoxide generation, and dose-dependently lowered cell survival. This demonstrates how MPs affect mitochondrial function.

While the full extent of the impact of microplastics on human health is still being unraveled, there is a growing body of evidence suggesting potential risks to vital organs and overall well-being. As the world grapples with the challenge of plastic pollution, it becomes imperative to address the potential consequences on human health. Further research and proactive measures to reduce plastic usage and mitigate environmental contamination are crucial steps in safeguarding both the planet and the health of its inhabitants.