Since 1950, approximately 8.3 billion metric tons of virgin plastics have been produced, with 79% accumulating in the natural environment because of low recycling rates. These non-biodegradable materials fragment into micro- and nanoplastics (MNPs) that have become ubiquitous contaminants. Humans are continuously exposed, especially through the inhalation of urban dust and fibres and the ingestion of contaminated food and water. This scoping review aimed to summarise the current evidence regarding the deposition of MNPs in human tissues and their subsequent pathophysiological impacts, with a focus on pathological manifestations across organ systems. Following PRISMA-ScR guidelines for scoping reviews, a comprehensive search was conducted across the PubMed, Scopus, and Cochrane Library databases. Studies investigating human microplastic exposure, tissue deposition, and physiological/pathological consequences were included. Data extraction focused on exposure routes, deposition patterns, and associated tissue alterations or disease processes. Our analysis revealed that MNPs primarily enter the human body through respiratory and digestive pathways. Subsequent deposition was documented across multiple organ systems, with significant accumulation in respiratory tissues, neurological structures, and throughout the gastrointestinal tract. The evidence suggests that these deposited particles can disrupt normal tissue physiology through multiple mechanisms, notably an exacerbation of inflammatory conditions and potentially increasing the risk of malignancy in affected tissues. Dose-dependent relationships between microplastic burden and pathological severity were observed in several studies. This review highlights that microplastics not only penetrate and persist within human tissues but may significantly contribute to inflammatory disease processes and carcinogenesis. These findings underscore the urgent need for enhanced exposure monitoring and further research into the prevention and evaluation of long-term health implications.
Fagbemi et al. (Thu,) studied this question.