Microplastics as Potential Emerging Vectors for Radon Progeny: A Conceptual Review of Mechanisms, Pathways, and Implications

Microplastics are ubiquitous environmental particles with complex physical and chemical properties that enable them to interact with other contaminants. Recent evidence suggests that microplastics act as carriers for various chemical pollutants, altering their transport, deposition, and deposition dose. This conceptual review synthesizes current knowledge of radon progeny behavior and microplastic properties and suggests potential mechanisms for their interaction, although direct experimental validation of radon progeny specifically is currently lacking. It discusses attachment kinetics, transport pathways in air and water, and microplastic-mediated shifts in human lung deposition patterns and ecological exposure. Theoretical dosimetry reasoning suggests that, if attachment occurs, small respirable microplastics (1–10 μm) could increase inhalation doses by prolonging the airborne residence time of progeny indoors, whereas macro- and coarse microplastics would primarily affect localized environmental hotspots. These possibilities remain to be tested experimentally. Integrated experimental and modelling approaches, including radon chamber studies, aerosol and aquatic transport experiments, respiratory tract modelling, and ecological bioassays, are proposed to quantify these processes and inform risk assessment. Knowledge gaps remain in attachment efficiency, retention, co-contaminant interactions, and long-term exposure scenarios. Addressing these gaps is critical for refining human and ecological risk assessments and guiding regulatory frameworks in radon-microplastic-impacted environments.