Microplastics Across the Human Body: Occurrence, Detection Methodologies, and Distribution in Human Tissues, Organs, and Biological Fluids

The rapid growth in plastic production and consumption has led to the widespread contamination of the environment with microplastics (MPs), raising increasing concerns about their potential impacts on human health. In recent years, advances in analytical techniques have revealed the presence of MPs in a wide range of human biological samples, suggesting that these particles can enter, circulate within, and accumulate throughout the human body. This narrative review provides a comprehensive overview of the current evidence on the occurrence and distribution of MPs in human tissues, organs, and biological fluids. MPs have been detected in blood, urine, stool, semen, breast milk, amniotic fluid, ocular fluids, and lavage fluids, as well as in several organs and tissues including the lungs, placenta, heart, kidneys, liver, vascular tissues, and reproductive organs. Among the identified polymers, polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polystyrene (PS), and polyvinyl chloride (PVC) are reported most frequently. This narrative review also summarizes the major analytical techniques used for MP detection and characterization, including Raman spectroscopy, μ-FTIR, LDIR spectroscopy, and Py-GC/MS, which highlight their advantages and limitations. Collectively, the available evidence demonstrates that MPs are not confined to the external environment but are now detectable in multiple compartments of the human body, including highly protected biological systems. However, important questions remain regarding their long-term persistence, transport mechanisms, biological fate, and potential health effects. Further methodological standardization and large-scale human studies are needed to better understand the extent of human exposure and the implications of MP accumulation for human health.