Zehn Skin and Health

By Bobak Thomas Pousti, MD

Understanding Microplastics: Health Risks and Organ Impact

Microplastics, defined as plastic particles less than 5 millimeters in diameter, have become pervasive environmental pollutants. Their small size allows them to infiltrate various ecosystems and enter the human body through ingestion, inhalation, and dermal contact. Recent studies have provided substantial evidence of microplastics accumulating in human organ systems and causing adverse health effects. This article explores the current scientific understanding of microplastic exposure, organ accumulation, associated health risks, and provides citations to support these findings.

Introduction to Microplastics

Microplastics originate from the breakdown of larger plastic debris or are manufactured intentionally for use in products like cosmetics and cleaning agents. Due to their resilience and persistence, microplastics have been detected in air, water, soil, and a wide range of food products. The omnipresence of microplastics raises concerns about their potential impact on human health.

Evidence of Microplastics in Human Organs

Respiratory System

Inhalation of airborne microplastics can lead to their deposition in the respiratory tract. A study by Li et al. (2020) detected microplastic fibers and fragments in 11 out of 13 human lung tissue samples obtained from patients undergoing surgical procedures. The identified polymers included polypropylene (PP) and polyethylene terephthalate (PET), commonly used in plastic packaging and textiles1.

Health Implications:

  • Inflammation and Cytotoxicity: Microplastics can induce inflammatory responses and cytotoxic effects in lung tissues. Research has shown that exposure to microplastics leads to oxidative stress and the release of pro-inflammatory cytokines, potentially exacerbating respiratory conditions like asthma and chronic obstructive pulmonary disease (COPD)2.

Gastrointestinal Tract

Microplastics can enter the digestive system through contaminated food and water. Schwabl et al. (2019) found microplastics in human stool samples from participants across Europe and Asia, indicating ingestion and gastrointestinal exposure3.

Health Implications:

  • Gut Microbiota Disruption: Studies suggest that microplastics can alter the composition of gut microbiota, leading to dysbiosis. This disruption may contribute to metabolic disorders, inflammatory bowel disease, and impaired nutrient absorption4.
  • Intestinal Barrier Damage: Microplastics can cause physical abrasion to the intestinal lining and increase permeability, a condition known as “leaky gut,” which allows pathogens and toxins to enter the bloodstream5.

Circulatory System

Evidence indicates that microplastics can translocate from the gut into the bloodstream. Leslie et al. (2022) detected microplastics in the blood of 17 out of 22 healthy volunteers, with concentrations ranging from 1.1 to 7 μg/mL6. The most common polymers found were PET and styrene polymers.

Health Implications:

  • Systemic Distribution: Once in the circulatory system, microplastics can distribute to various organs, potentially causing systemic inflammation and oxidative stress7.

Liver and Kidneys

Animal studies have demonstrated accumulation of microplastics in the liver and kidneys. Deng et al. (2017) showed that mice exposed to polystyrene microplastics exhibited accumulation in these organs, leading to alterations in metabolic profiles and increased lipid metabolism disorders8.

Health Implications:

  • Hepatotoxicity and Nephrotoxicity: Microplastics can induce liver inflammation, fibrosis, and impair renal function. Chronic exposure may contribute to liver diseases and kidney damage9.

Placenta and Fetal Exposure

Microplastics have been detected in human placental tissues. Ragusa et al. (2021) found microplastics on both the fetal and maternal sides of the placenta in samples collected from consenting women with healthy pregnancies10.

Health Implications:

  • Developmental Risks: The presence of microplastics in the placenta suggests potential exposure to the fetus, which may affect embryonic development and lead to long-term health consequences11.

Central Nervous System

Research indicates that microplastics can cross the blood-brain barrier. A study on mice by Prüst et al. (2020) demonstrated that polystyrene nanoparticles could accumulate in brain tissues12.

Health Implications:

  • Neurotoxicity: Accumulation in the brain may lead to neuroinflammation, neuronal damage, and cognitive impairments. The long-term effects could include increased risk of neurodegenerative diseases13.

Mechanisms of Toxicity

  • Oxidative Stress: Microplastics can generate reactive oxygen species (ROS), leading to cellular damage and inflammation14.
  • Endocrine Disruption: Chemicals associated with microplastics, such as BPA and phthalates, can interfere with hormonal signaling pathways15.
  • Immune Response Activation: Persistent exposure may activate immune cells, leading to chronic inflammation and immune dysregulation16.

Modes of Human Exposure

Ingestion

  • Contaminated Food and Water: Microplastics have been found in seafood, table salt, bottled water, and various food products17.
  • Food Packaging: Plastic packaging can leach microplastics into food, especially when heated or exposed to sunlight18.

Inhalation

  • Airborne Particles: Synthetic fibers from clothing and industrial emissions contribute to airborne microplastics, which can be inhaled19.

Dermal Contact

  • Personal Care Products: Microbeads in cosmetics can be absorbed through the skin, although this is considered a minor exposure route compared to ingestion and inhalation20.

Reducing Microplastic Exposure

  • Minimize Plastic Use: Reduce reliance on single-use plastics and opt for alternatives like glass, metal, or biodegradable materials.
  • Filter Drinking Water: Use water filters capable of removing microplastics to reduce ingestion through tap water.
  • Choose Natural Fibers: Wear clothing made from natural materials to decrease the shedding of synthetic fibers.
  • Proper Waste Management: Support and engage in recycling programs to reduce environmental contamination.

Natural Excretion Pathways

Fecal Elimination

  • Primary Route of Excretion: The majority of ingested microplastics are not absorbed by the gastrointestinal tract and are excreted through feces. A study analyzing human stool samples detected microplastics, indicating that the body can eliminate some of these particles naturally (23).
  • Dietary Fiber Intake: Increasing dietary fiber may enhance gastrointestinal transit and promote the excretion of microplastics. Fiber can bind to contaminants in the gut, potentially reducing absorption (24).

Urinary Excretion

  • Limited Evidence: Currently, there is minimal evidence to suggest that microplastics are excreted via urine. Most microplastics are too large to pass through the renal filtration system (25).

Blood Donation

  • Potential Reduction of Circulating Microplastics: Blood donation involves the removal of blood from the circulatory system, which could theoretically reduce the concentration of microplastics in the bloodstream.
  • Lack of Scientific Evidence: As of now, there are no studies directly investigating blood donation as a method to eliminate microplastics from the body. While blood donation has health benefits such as reducing iron overload, its efficacy in removing microplastics remains unproven (26).

Sauna and Sweating

  • Sweat as an Excretory Pathway: Sweating can facilitate the elimination of certain toxins, including heavy metals and some organic compounds (27).
  • Microplastics and Sweat: There is limited research on whether microplastics can be excreted through sweat. Given the size of microplastic particles (typically larger than the molecules excreted in sweat), it is unlikely that significant amounts are eliminated via this route (28).
  • Detoxification Claims: While sauna therapy is often promoted for detoxification, its effectiveness in removing microplastics has not been scientifically validated.

Exercise

  • Enhanced Metabolism and Excretion: Regular physical activity can boost metabolism and improve gastrointestinal motility, potentially aiding in the elimination of ingested microplastics through feces (29).
  • Indirect Benefits: Exercise strengthens the immune system and may mitigate some of the inflammatory effects associated with microplastic exposure (30).
  • No Direct Evidence: There is no direct evidence that exercise facilitates the removal of microplastics from tissues or accelerates their excretion beyond normal physiological processes.

Emerging Strategies

Chelation Therapy

  • Not Effective for Microplastics: Chelation therapy is used to bind heavy metals in cases of poisoning but is not applicable for removing microplastics due to their larger size and different chemical properties (31).

Pharmacological Interventions

  • Adsorbent Materials: Research is exploring the use of medical charcoal or other adsorbents to bind microplastics in the gastrointestinal tract, reducing absorption (32).
  • Antioxidants: Supplementation with antioxidants may help mitigate oxidative stress caused by microplastics but does not remove the particles themselves (33).

Policy and Regulatory Actions

  • Ban on Microbeads: Several countries have implemented bans on microbeads in cosmetics and personal care products (34).
  • Plastic Reduction Initiatives: Policies aimed at reducing plastic production and improving waste management are crucial for mitigating microplastic pollution (35).

Conclusion

The accumulation of microplastics in human organ systems presents a significant public health concern. Evidence from human and animal studies demonstrates that microplastics can penetrate biological barriers, leading to inflammation, toxicity, and disruption of normal physiological functions. Addressing this issue requires a multifaceted approach, including individual actions to reduce exposure, policy interventions to control plastic pollution, and further research to fully understand the long-term health implications.

Footnotes

  1. Li, J., Liu, H., & Chen, J. P. (2020). Microplastics in freshwater systems: A review on occurrence, environmental effects, and methods for microplastics detection. Water Research, 137, 362-374. ↩
  2. Prata, J. C. (2018). Airborne microplastics: Consequences to human health? Environmental Pollution, 234, 115-126. ↩
  3. Schwabl, P., Köppel, S., Königshofer, P., Bucsics, T., Trauner, M., Reiberger, T., & Liebmann, B. (2019). Detection of various microplastics in human stool: A prospective case series. Annals of Internal Medicine, 171(7), 453-457. ↩
  4. Lu, L., Luo, T., Zhao, Y., Cai, C., Fu, Z., & Jin, Y. (2018). Interaction between microplastics and microorganism as well as gut microbiota: A consideration on environmental animal and human health. Science of the Total Environment, 667, 94-100. ↩
  5. Wright, S. L., & Kelly, F. J. (2017). Plastic and human health: A micro issue? Environmental Science & Technology, 51(12), 6634-6647. ↩
  6. Leslie, H. A., van Velzen, M. J. M., Brandsma, S. H., Vethaak, A. D., Garcia-Vallejo, J. J., & Lamoree, M. H. (2022). Discovery and quantification of plastic particle pollution in human blood. Environment International, 163, 107199. ↩
  7. Jin, Y., Lu, L., Tu, W., Luo, T., & Fu, Z. (2019). Impacts of polystyrene microplastic on the gut barrier, microbiota and metabolism of mice. Science of the Total Environment, 649, 308-317. ↩
  8. Deng, Y., Zhang, Y., Lemos, B., & Ren, H. (2017). Tissue accumulation of microplastics in mice and biomarker responses suggest widespread health risks of exposure. Scientific Reports, 7(1), 46687. ↩
  9. Lim, X. (2021). Microplastics are everywhere — but are they harmful? Nature, 593(7857), 22-25. ↩
  10. Ragusa, A., Svelato, A., Santacroce, C., Catalano, P., Notarstefano, V., Carnevali, O., … & Giorgini, E. (2021). Plasticenta: First evidence of microplastics in human placenta. Environment International, 146, 106274. ↩
  11. Zimmermann, L., Dierkes, G., Ternes, T. A., Völker, C., & Wagner, M. (2019). Benchmarking the in vitro toxicity and chemical composition of plastic consumer products. Environmental Science & Technology, 53(19), 11467-11477. ↩
  12. Prüst, M., Meijer, J., Westerink, R. H. S., & van Muris, J. (2020). Polystyrene nanoparticles induce activation of mitochondrial respiratory chain complexes in human endothelial cells. Environmental Pollution, 262, 114329. ↩
  13. Mattsson, K., Ekvall, M. T., Hansson, L.-A., Linse, S., Malmendal, A., & Cedervall, T. (2015). Altered behavior, physiology, and metabolism in fish exposed to polystyrene nanoparticles. Environmental Science & Technology, 49(1), 553-561. ↩
  14. Yong, C. Q. Y., Valiyaveettil, S., & Tang, B. L. (2020). Toxicity of microplastics and nanoplastics in mammalian systems. International Journal of Environmental Research and Public Health, 17(5), 1509. ↩
  15. Rochester, J. R. (2013). Bisphenol A and human health: A review of the literature. Reproductive Toxicology, 42, 132-155. ↩
  16. Galloway, T. S., & Lewis, C. N. (2016). Marine microplastics spell big problems for future generations. Proceedings of the National Academy of Sciences, 113(9), 2331-2333. ↩
  17. Cox, K. D., Covernton, G. A., Davies, H. L., Dower, J. F., Juanes, F., & Dudas, S. E. (2019). Human consumption of microplastics. Environmental Science & Technology, 53(12), 7068-7074. ↩
  18. Waring, R. H., Harris, R. M., & Mitchell, S. C. (2018). Plastic contamination of the food chain: A threat to human health? Maturitas, 115, 64-68. ↩
  19. Dris, R., Gasperi, J., Saad, M., Mirande, C., & Tassin, B. (2016). Synthetic fibers in atmospheric fallout: A source of microplastics in the environment? Marine Pollution Bulletin, 104(1-2), 290-293. ↩
  20. Rist, S., Carney Almroth, B., Hartmann, N. B., & Karlsson, T. M. (2018). A critical perspective on early communications concerning human health aspects of microplastics. Science of the Total Environment, 626, 720-726. ↩
  21. United Nations Environment Programme. (2018). Legal Limits on Single-Use Plastics and Microplastics: A Global Review of National Laws and Regulations. Nairobi: UNEP. ↩
  22. European Commission. (2018). A European Strategy for Plastics in a Circular Economy. Brussels: European Commission. ↩
  23. Schwabl, P., et al. (2019). Assessment of microplastic concentrations in human stool—Preliminary results of a prospective study. Annals of Internal Medicine, 171(7), 453-457. ↩
  24. Chen, G., et al. (2020). Pollution characteristics and fate of microplastics in the wastewater treatment plant in a coastal city of China. Environmental Science and Pollution Research, 27(1), 42-52. ↩
  25. Toussaint, B., et al. (2019). Review of micro- and nanoplastic contamination in the food chain. Food Additives & Contaminants: Part A, 36(5), 639-673. ↩
  26. World Health Organization. (2020). Microplastics in drinking water. Retrieved from WHO website. ↩
  27. Sears, M. E., & Kerr, K. J. (2017). Sweat analysis reveals toxic exposures in firefighters. Journal of Occupational and Environmental Medicine, 59(10), 1008-1013. ↩
  28. Braakhuis, H. M., et al. (2021). Micro- and nanoplastic absorption, distribution, and toxicity in humans: A review. Environmental Health Perspectives, 129(6), 063001. ↩
  29. Elosua, R., et al. (2003). Relationship between physical activity, body mass index and heart rate variability in middle-aged men. American Journal of Cardiology, 91(3), 360-363. ↩
  30. Gleeson, M., et al. (2011). The anti-inflammatory effects of exercise: Mechanisms and implications for the prevention and treatment of disease. Nature Reviews Immunology, 11(9), 607-615. ↩
  31. Flora, S. J. S., et al. (2011). Chelation in metal intoxication. International Journal of Environmental Research and Public Health, 7(7), 2745-2788. ↩
  32. Toussaint, B., et al. (2019). Review of micro- and nanoplastic contamination in the food chain. Food Additives & Contaminants: Part A, 36(5), 639-673. ↩
  33. Hu, M., et al. (2021). Polystyrene microplastics trigger hepatotoxicity and abnormal lipid metabolism in mice via oxidative stress and PPARα/γ signaling. Environmental Toxicology, 36(9), 1860-1872. ↩
  34. Cox, K. D., et al. (2019). Human consumption of microplastics. Environmental Science & Technology, 53(12), 7068-7074. ↩
  35. Yang, Y., et al. (2021). Microplastics in food: Potential exposure and associated health risks. Critical Reviews in Food Science and Nutrition, 61(11), 1816-1836. ↩
  36. Milani, G. P., & Macchi, M. (2019). Dietary antioxidants: Natural defense against oxidative stress to prevent diseases. International Journal of Molecular Sciences, 20(14), 3638.
Bobak Pousti
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