Academy of Diagnostics & Laboratory Medicine - Scientific Short
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Over the years, there has been an alarming rise in the use of plastics and exposure to their potentially harmful chemical constituents. Several articles have documented the use of plastics and their environmental impact, with recent figures indicating that plastic production surpassed 368 million tons in 20191. According to the United Nations Environment Programme's 2020 report, if current trends in consumption and waste management persist, it is projected that by 2050, around 12 billion metric tons of plastic waste could accumulate in landfills, open dumps, and natural environments2. While our waters continue to be flooded with these potential contaminants, there is a paucity of research on the health implications of plastics and effective methods for assessing human exposure to toxic levels of microplastics (MPs) and nanoplastics (NPs). Microplastics are defined as plastic particles smaller than 0.5 millimeters in diameter, whereas nanoplastics are even smaller, measuring 100 nanometers or less2. These particles are ubiquitously distributed in the environment due to ongoing degradation processes and ultimately affect the quality of our food and air1,3.
Animal studies have demonstrated that MPs and NPs can impact multiple systems in the human body including the cellular, digestive, respiratory, endocrine, reproductive, and immune systems. These plastic particles can generate reactive oxygen species within tissues, leading to cellular dysfunction and compromised tissue integrity4. One prospective observational study was conducted on MPs and NPs as an emerging risk factor in cardiovascular disease wherein they identified plastics in excised carotid plaques using pyrolysis–gas chromatography–mass spectrometry, stable isotope analysis, and electron microscopy5. Another study showed that within the digestive system, ingested plastic particles can induce physical irritation to the gastrointestinal tract, potentially leading to chronic inflammation and associated gastrointestinal symptomatology4. Furthermore, inhalation of microplastics poses a potential health risk to the respiratory system, leading to oxidative stress and inflammation in the airways and lung6. Lastly, MPs and NPs pose a potential threat to hormonal homeostasis by disrupting various endocrine processes, including hormone production, release, transport, metabolism, and elimination7. While the evidence that demonstrates the pathological consequences of plastic exposure is burgeoning, our comprehensive understanding of the risk that MPs and NPs pose is limited by a lack of robust methodology to accurately quantify the concentrations of these plastics in biological samples and establish toxic levels.
The first study detecting MPs and NPs in a human biological sample was published in 2019, revealing up to 50 particles per gram and identifying nine types of plastic in feces8. Since then, only a few studies have explored potential methods for detecting MPs and NPs. Several studies have identified spectroscopy and mass spectrometry as potential methods for detecting and quantifying NPs and MPs. However, these techniques are not without their limitations. One study demonstrated that Raman Spectroscopy has limitations due to its size detection threshold (approximately 1 µm) and challenges related to specimen collection and processing methods9. A more recent study employed GC/MS to identify the polymer composition of plastics in blood samples, focusing on polymethyl methacrylate, polypropylene, polystyrene, polyethylene, and polyethylene terephthalate. The study developed a protocol and provided a unique dataset supporting the hypothesis that human exposure to plastic particles results in their absorption into the bloodstream. However, the study was limited by its ability to detect polymers only within the range of 700 nm to 0.514 mm10.
The absence of standardized procedures for sampling, controls, sample processing, and analysis of MPs and NPs complicates the standardization of analytical methods for their detection and quantification. Currently, it is not feasible to quantify plastics as a toxic hazard due to their diversity and the lack of established protocols. The question of whether quantification of MPs and NPs in biological samples is necessary to gain deeper insights into their potential toxicity remains unresolved. As the use and exposure to plastics continue to increase rapidly, it is crucial to focus on this emerging environmental contaminant of clinical concern.
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