Microplastics in foodstuffs come into close contact with the gastrointestinal tract and have the potential to interact either physically or chemically with the cells there. A study published in Chemosphere in April 2024 by Ekaterina Brynzak-Schreiber of the University of Vienna and co-authors explored how polystyrene micro- and nanoplastics (PS-MNPs) interact with colon cancer cells, focusing on how particle size affects uptake and distribution within the cells and their subsequent behavior.
The researchers used four types of colon cancer cells (cell lines) and examined how different sizes of PS-MNPs (0.25 μm, 1 μm, and 10 μm) were absorbed and distributed within these cells. They used both simple cell cultures and more complex, three-dimensional models to replicate tumor environments.
Small particles (0.25 μm) were more readily taken up by the cells than larger particles (1 μm), and the largest particles (10 μm) were not absorbed at all. Over time, the absorbed particles moved within the 3-D spheroid tumor model, accumulating more in the necrotic (dead) core and less in the growing areas. The HCT116 cell line absorbed the most particles, likely due to its aggressive nature. The authors noted that, “[d]espite their presence [the MNPs], no interruption of cell proliferation or division was observed”.
Colorectal cancer is the second leading cause of cancer death in the US, according to a report by the American Cancer Society in 2023. The report states that “[a]lthough overall CRC [colorectal cancer] mortality continues to decline, this progress is tempered by a rapidly changing landscape of disease that foreshadows less favorable trends ahead.” Since the mid 1990’s, colorectal cancer diagnoses have increased approximately 50% in people under age 50. The exact cause of the change is unknown.
Brynzak-Schreiber and colleagues found that exposure to the 0.25 μm PS particles increased cell movement, suggesting they might promote cancer spread. “Importantly, particles were distributed between mother and daughter cells during division, with no signs of elimination.” The persistence and bioaccumulation of MNPs in colorectal cancer cells raises concerns about their long-term effects on human health. The authors encourage researchers to investigate the chronic toxicity of more realistic MNP shapes and the potential impacts on the intestinal barrier and other organs.
Given that MNPs meet two out of three criteria for hazardous substances under REACH regulations (persistence and bioaccumulation), further research and regulatory action are crucial. Brynzak-Schreiber et al. write, “[o]ur recent findings, along with prior studies, demonstrate high tissue and cellular persistence and bioaccumulation, meeting criteria for classification of the studied particles as substances of concern.”
Reference
Brynzak-Schreiber, Ekaterina; et al. (2024). “Microplastics role in cell migration and distribution during cancer cell division.” Chemosphere. DOI: 10.1016/j.chemosphere.2024.141463
Siegel, Rebecca L.; et al. (2023). “Colorectal cancer statistics, 2023.” American Cancer Society DOI: 10.3322/caac.21772
Other recent research
Abafe, Ovokeroye Akpojevwe, et al. (2024). “Assessment of human dermal absorption of flame retardant additives in polyethylene and polypropylene microplastics using 3D human skin equivalent models.” Environment International. DOI: 10.1016/j.envint.2024.108635
Chen, Chi-Yun and Lin, Zhoumeng. (2024). “Exploring the potential and challenges of developing physiologically-based toxicokinetic models to support human health risk assessment of microplastic and nanoplastic particles.” Environment International. DOI: 10.1016/j.envint.2024.108617
Garcia, Marcus M., et al. (2024). “In vivo tissue distribution of polystyrene or mixed polymer microspheres and metabolomic analysis after oral exposure in mice.” Environmental Health Perspectives. DOI: 10.1289/EHP13435
