Unveiling the complex impact of microplastics on environmental health, ecosystems, and humans

Microplastics (MPs) are becoming a ubiquitous global contaminant, with impacts on ecosystems and human well-being worldwide. As such, this review aims to consolidate the current state of knowledge in relation to MPs pollution, describing: sources; transport pathways and fate; impact on biota; environmental sampling techniques, technologies and methods for quantification; issues surrounding regulation; and research priorities within the various environments investigated (marine, freshwater, terrestrial and atmospheric). Rivers represent a significant pathway for MPs into the oceans, with an estimated 1.15-2.41 million metric tons of plastic debris entering the oceans annually through riverine systems. The review highlights the influence of microplastics on ecosystem processes, such as reduced carbon fixation by marine phytoplankton (up to 20 % reductions in photosynthesis rates). We also discuss the potential consequences of microplastics for climate change, documenting tentative evidence of microplastic-induced greenhouse gas emissions. The review analyses, in a critical manner, alternative protocols for removing microplastics and new technologies, including advanced filtration and nanomaterials, with examples of performance enhancement, scaling-up capacity, and environmental impact. Notwithstanding these advances, significant gaps remain in our understanding of the long-term ecological and health impacts of these particles, underscoring the critical importance of harmonized methods, interdisciplinary research, and an integrated global strategy to address this emerging challenge.