Microbial risks associated with microplastics in the food chain and possible control measures (literature review). Part 1. Dietary intake and influence on the gut microbiota

Environmental contamination by polymer wastes and microplastics (MPs) has recently become important for health care, due to the emergence of a lot of evidence that MPs affect the health of living organisms, including humans. MPs commonly presented in drinking water and various groups of food products, and are found in human stool, colon tissue, and blood samples. When MPs are orally ingested, the first object for their interaction with the organism is the gastrointestinal microbiota. Considering the essential importance of the intestinal microbiota for human health, the study of the negative consequences of such contact becomes very important. The results of “in vitro” and “in vivo” experimental studies summarized in the review indicate MPs to have negative effects on the microbial community composition and of the intestinal barrier state, and are themselves subject to microbial degradation in the gastrointestinal tract. “In vivo” studies, the entry of MPs into the intestine is accompanied by an increase in α-diversity of the microbiota, presumably due to foreign microorganisms attached to the particles, including those in as part of biofilms formed on their surfaces. Competing with representatives of normal intestinal flora, these microorganisms are able to enzymatically degrade or overcome the mucosal barrier. Simultaneously the biofilm matrix associate with intestinal mucus and provides MPs particles with retention in the mucin layer and direct contact with the apical part of epitheliocytes. This leads to irritation, local inflammation, and damage to the intestinal barrier. MPs and their biotransformation products can also systemically affect the host organism, translocating from the intestine into the bloodstream. The review emphasizes that to identify and characterize the health risks associated with the intake of various MPs from food, studies assessing their interaction with the microbiota and biotransformation pathways in the intestine are necessary.