In an article published on September 24, 2021, in the journal Current Opinion in Toxicology, Silvia Turroni and co-authors from the University of Bologna, Italy, and the Imperial College London, United Kingdom, evaluated how microplastics may affect humans’ gastrointestinal ecology based on current scientific literature.
Once microplastics are taken up by humans, e.g. via inhalation, drinking water (FPF reported and here), or foods (FPF reported, here, and here), the gut is one of the primary organs interacting with the small particles, but studies assessing the potential effects of environmentally relevant microplastics levels on the intestine are still absent. Based on the existing literature, Turroni et al. point out that 52,000 plastic particles/year may be ingested together with drinking water and food, and around 46,000 from outdoor and indoor air. When reaching the gut “particles can be taken up through different size-dependent pathways”, which are summarized in the article together with potential toxicological consequences. These impacts are reported to be dependent on the size, shape, surface charge, and solubility of the microplastics.
Concerning the human gastrointestinal tract, microplastics exposure has previously been calculated based on a study measuring microplastics in human stool (FPF reported) and was reported to be around 73,000 particles eliminated annually. By taking several previous findings together, for instance, that chronic exposure to polystyrene microplastics affects the intestinal barrier function and gut microbiota composition of mice (FPF reported), the authors summarized that microplastics “may interact with intestinal ecology in the real world, promoting dysbiotic changes in the gut microbiome, with possible detrimental consequences on gut health.” The microplastics themselves may create “an environment less favorable to the survival” of beneficial endogenous gut bacteria “possibly due to increased local inflammation and/or release of chemicals.” The particles may further facilitate pollutants and pathogens entry into the intestine, which in turn could change the human gut microbiome directly. According to Turroni and co-authors, this evidence emphasizes the need to analyze humans’ oral exposure to microplastics and their hazards in the gut and give practical recommendations for this assessment.
Turroni, S. (2021). “Microplastics shape the ecology of the human gastrointestinal intestinal tract.” Current Opinion in Toxicology. DOI: 10.1016/j.cotox.2021.09.006