Progress, prospects, and challenges in standardization of sampling and analysis of micro- and nano-plastics in the environment

To date, accurate quantification of micro- and nano-plastics (MPs and NPs) has become the need of the hour to efficiently maintain the planetary sustainability and human health in light of their potentials for the environmental perturbation. However, the analysis of MPs and NPs is impeded by the lack of standardized methods with the shortage of the knowledge on chemical composition (e.g., molecular weight) of plastic polymers and on the interactive roles between physico-chemical, biological (e.g., plastic-microbe interactions), and environmental attributes. Also, the gap between accurate quantitative analysis of plastic particles and the health hazards is huge. As such, standardized analytical protocols for these hazardous plastic particles, if established, would help monitor their behavior to safely manage the human health. In this work, critical analysis on the current status, issues, and challenges for future development in the monitoring of MPs and NPs is presented with an emphasis on monitoring of plastic particles in terrestrial (soil/sediment), atmosphere (air), aquatic (marine and freshwater), and biotic systems (model organisms and food webs). Further, an in-depth discussion on multiple methodological approaches for sampling, sample treatment, and preparation (e.g., separation, extraction, and digestion), and analysis (identification, detection, and characterization) of MPs and NPs has been made. The benefits and drawbacks of these approaches are also described to help open the new paths for the efficient monitoring of plastics in various environmental systems. At last, the adequate quality assurance/control measures are to be emphasized to help overcome the multifaceted challenges in plastic analysis.