Microplastics as an emerging threat to ecosystems: a comprehensive review of their interactions with contaminants, toxicological implications, monitoring and remediation strategies.

Microplastics have emerged as pervasive and persistent pollutants across marine, freshwater, terrestrial and atmospheric environments. Their small size and environmental persistence facilitate wide dispersal and long-term accumulation, posing significant ecological and human health risks. Beyond their intrinsic effects, microplastics act as carriers for environmental contaminants, including hydrophobic organic compounds, heavy metals and radionuclides, thereby influencing their transport, bioavailability and trophic transfer. This review synthesizes findings from approximately 235 studies (2004-2025) to provide an integrated understanding of microplastics-contaminant interactions, associated toxicological implications and the effectiveness of current monitoring, detection and remediation strategies. Interactions of microplastics with organic pollutants and heavy metals are first comprehensively discussed to establish a broad and unified framework of contaminant dynamics. Against this background, the review presents a focused and in-depth evaluation of microplastics-radionuclide interactions, an area that remains comparatively underexplored. Particular emphasis is placed on the role of aqueous speciation, oxidation state and competitive ions in governing radionuclide sorption mechanisms. This review critically evaluates the outcomes of existing studies to synthesize current limitations and advancements in microplastics research. By identifying key knowledge gaps and highlighting emerging research directions, it aims to support the development of informed mitigation strategies.