From bulk to bits: understanding the degradation dynamics from plastics to microplastics, geographical influences and analytical approaches.

This article critically reviews the global production, environmental fate, and degradation dynamics of plastics and their transformation into microplastics, emphasizing the influence of geographical conditions and analytical approaches for characterization. It outlines the rapid increase in plastic production and waste generation, highlighting that over 6 billion tons of plastics persist in the environment, where they degrade via physical, chemical (photodegradation, thermo-oxidation, hydrolysis), and biological pathways into microplastics ranging from 1 to <1,000 μm. The review discusses how environmental factors such as sunlight, temperature, moisture, and microbial activity vary by location (landfills, marine, soil) and affect degradation rates and fragmentation processes. It also summarizes current analytical techniques—including Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction, thermal and mechanical analyses, and microscopy—used to assess polymer degradation and microplastic formation, noting limitations and the need for standardized methods. The authors call for enhanced understanding of degradation mechanisms, improved quantification methods, and global efforts toward plastic waste management and circular economy principles to mitigate microplastic pollution.