Microplastics in freshwater environment: occurrence, analysis, impact, control measures and challenges

World produces 360 million tons of plastic every year, out of which only 7% plastic undergo recycling leaving majority of this waste lying around that get accumulated in the environment, thus posing a serious threat especially in the form of microplastics (MPs) to the large group of organisms on earth. Microplastics have been observed both in freshwater as well as in marine environment; however, recently, the occurrence of MPs in the fresh water that will ultimately lead to pollution in drinking water is emerging as one of the major concern for the scientific community. Till now, relative to the marine environment, the MPs pollution in the fresh water system is not very well understood and still an area of research that needs to be explored in detail. A detailed understanding of the origin, qualification, quantification, hazardous effects, etc. has be established to develop a proper waste management process for the MPs found in fresh water system. This review focuses on the sources, distribution, sampling methods, separation methods, methods of characterization and toxicological effects of microplastics in the freshwater environment. Various factors that affect the transportation and distribution of microplastics in fresh water system are reviewed. It is recommended that a standard protocol must be developed for identification of microplastics for scientific community across the world. The present study will help us to understand the source, transport, and effects of microplastics on the freshwater environment which would thereafter help to standardize the process for quantification and identification of microplastics in the freshwater environment. A combination of methods for the detection and prevention of microplastics in freshwater environment has also been suggested.