Global challenges in microplastics: From fundamental understanding to advanced degradations toward sustainable strategies

Currently, the global production and usage of plastics have increased rapidly with the expansion of synthetic polymers. Since plastics' degradation processes are prolonged and thus microplastics (MPs) potentially persist for very long periods in the environment. To date, there is a need for knowledge on the relevance of different potential entry pathways and the number of MPs entering the environment via different routes. Despite the vast quantity of studies that have been undertaken, many unanswered issues remain about the environmental impacts of MPs. The real impacts on a population subjected to many MPs of different structure, dimensions, and shapes over a lifetime are still hard to elucidate. Significantly, MPs can accumulate toxic substances, such as persistent organic pollutants, on their material surface. Hence, it represents a potential concentrated source of environmental pollution or acts as a vector of toxic pollutants in the food chain's interconnection with some severe health implications. Herein, we mainly discussed the global challenges in MPs, including the current production and use status of plastics and their impact on the environment. Additionally, finding the degradation of tiny fragment plastics (MPs level) is essential to remove plastics altogether. Some of the approaches to methods, including biodegradation, physical degradation, physicochemical degradation, have been successfully reviewed. More importantly, the sustainable concepts of using microorganisms and photocatalysis for MPs' degradation have been successfully proposed and demonstrated.