• Potential impact of Nano and Microplastics, as an Emerging Environmental Risk Factor, on Disruption of Human Microbiome Symbiosis and Cancer Development, A Review
  • Parvin Mohammadshafiei,1,*
    1. Department of Biology, Faculty of Science, Shahid Chamran University of Ahvaz, Iran


  • Introduction: Microplastics (MPs) are major pollutants in the environment, and it is currently established that microplastics have already entered human food chains and have been incorporated into the human body through ingestion and inhalation. It is estimated that an average person inhales and consumes between 78,000 and 211,000 microplastic particles annually. Furthermore, an average adult may ingest around 1460–36,135 MPs annually through salt alone. Recent studies have revealed alarming data regarding the accumulation of MPs in humans, indicating that it is a serious health risk factor. For example, accumulated MPs have been found throughout the human body, including the blood, arteries, brain, kidneys, lungs, intestines, placenta, liver, breast milk, and most recently in testes and semen samples. Besides, MPs found in human feces confirm that they are consumed through foods and beverages and pass through the digestive system. Overall, MPs can release toxic chemicals that act as potent carcinogenic factors or pathogenic microbes into human tissues and, subsequently, cause harmful effects leading to chronic diseases conditions such as cancer. This evidence is alarming and points unknowingly to the world facing a health crisis. Therefore, MPs have become a current research focus as an emerging pollutant. Overall, this review presents evidence of the complex interplay between MPs, gut health, and cancer, which warrants in-depth investigation and exploration of effective preventive and mitigative strategies to safeguard vulnerable populations from the potential long-term effects of MPs exposure.
  • Methods: This study reviews data accumulated from literature and prestigious case studies related to our subject. The search words were:" Microplastic,” “Cancer,” “Inflammation,” “Gut microbiota,” Microbiome”, “health risk,” Colorectal Cancer”,” Micro and Nano plastics”, ”Microparticles”, ” human health threat” using the PubMed, Scopus, ScienceDirect, and Google Scholar databases. Furthermore, manual searches of other relevant journals and keyword searches were performed. We have focused on published papers from 2015 to 2025.
  • Results: The ingestion of MPs by organisms has several physical impacts, such as blockages, abnormalities, and chemical effects (additive chemicals leaching out or the chemicals in environmental contaminants adhering to them), and biological impacts caused by pathogenic microbes colonizing them. Together, these impacts pose serious health risks, as more and more alarming statistical data support increased MP accumulation in humans, which are linked to the development of chronic diseases and cancer. The research data from studies analyzed in this review demonstrate that MP bioaccumulation promotes cancer cell proliferation, and the normal cells exposed to MPs are damaged due to induced oxidative stress and inflammation, which drives cells toward a cancerous condition.
  • Conclusion: Studies have found that the cancer risk is higher with chronic exposure to pro-angiogenic factors and persistent synthetic fibers (i.e., types of MPs) for an extended period. Currently, research is focused on the carcinogenic effects of MPs' bioaccumulation and the effects of chemically enriched MPs (MPs' surfaces rich with adsorbed toxic chemical additives). The smaller the size of MPs, the higher the surface area and the amount of toxins that can be absorbed. The volatile forms enter the human body through inhalation and contribute to the progression of tumors in the lungs, liver, brain, and kidneys. Moreover, MPs are reported to positively affect the hallmarks of cancer and aid in cancer progression by impacting mitochondrial health. Their microscopic size promotes rapid translocation to other tissues including the liver, intestines, lungs, immune cells, and neurologic parts. In addition, MPs' high surface area can promote genotoxicity, oxidative stress, chronic inflammation, induce apoptosis, cytotoxicity, and autoimmune disorders. Chemicals found in plastic products used every day include BPA and phthalates, which have been reported to affect prenatal and postnatal developmental stages and act as immunomodulators affecting immune cell development and function. Overall, that plastics-driven biological dyshomeostasis can trigger oncogenic signals leading to cancer. Therefore, MPs accumulation causes physical damage, alteration in gut microbiota, inflammation, activation of immunological responses, apoptosis signals, and epigenetic alterations that drive the cell toward cancerous transformation. However, future research is required to understand the interplay between MPs' dyshomeostasis and cancer.
  • Keywords: Cancer, Microplastic, Gut microbiota, health risk