An overview of the sources, hazards and removal of microplastics

Plastics, which constitute an important component of environmental pollution, appear as micro (≤5 mm) and nano-sized (≤1000 nm) particles. These particles are classified as primary and secondary based on their origin. Primary microplastics (MPs) and nanoplastics (NPs) are intentionally produced at micro/nano sizes in industrial processes or in consumer products. Secondary MPs and NPs are formed due to the breakdown of macroplastic waste, e.g., plastic bottles, plastic bags, etc, by environmental factors, i.e., UV-radiation, mechanical abrasion, weathering, and microbial activity. These particles constitute >90% of total plastic pollution. The increase in MPs and NPs in natural environments has brought about concerns for most living species, humans, animals, and plants. As microplastics can enter the food chain, they pose a serious threat to human and animal health as well as the ecosystem. Therefore, microplastic removal from wastewater and water bodies is very important for all living species. Here, the sources of microplastics and the problems they cause, and the techniques and materials used to remove microplastics from the atmosphere, are discussed by surveying the current relevant publications. In addition, ways to deal with MP pollution, which has become a global problem in terms of both environment and human health, were discussed.