Microplastics in the Human Body: A Systematic Review of Evidence, Detection Methods, and Toxicological Concerns

Background: Microplastics (MPs) are emerging contaminants detected in various human biological matrices, raising concerns about their potential health effects. However, their biological effects remain unclear. This systematic review analyzes current evidence on the presence of MPs in human tissues, detection methods, and associated health risks. Methods: A comprehensive search was conducted to identify studies published between 2013 and 2024 in several databases such as PubMed and SCOPUS, according to the PRISMA 2020 statement. Results: A total of 60 studies were included in the systematic review. These studies highlighted that MP contamination was found in the reproductive, gastrointestinal, cardiovascular, respiratory, and urinary systems, as well as in blood, cerebrospinal fluid, and bone marrow. The most frequently identified polymers were polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), and polyethylene terephthalate (PET). The most commonly used analytical methods were Raman spectroscopy (36.7%) and infrared-based techniques (28.3%). MPs have been associated with oxidative stress, inflammation, endocrine disruption, and cardiovascular diseases, with detections in thrombi from ischemic stroke and myocardial infarction patients, suggesting cardiovascular implications. Elevated MP levels in reproductive tissues and fetal matrices raise concerns about developmental toxicity. Conclusion: Despite growing evidence, gaps remain in understanding MP toxicokinetics, bioaccumulation, and systemic effects. The lack of standardized methodologies limits the comparability between studies, highlighting the need for harmonized protocols. Future research should aim to improve detection techniques, assess chronic exposure effects, and consider regulatory measures to reduce MP contamination.