Microplastics in the environment: A critical overview on its fate, toxicity, implications, management, and bioremediation strategies

Microplastics are small plastic pieces ranging in size from 1μ to <5 mm in diameter, are water-soluble, and can be either primary as they are initially created in small sizes or secondary as they develop due to plastic degradation. Approximately 360 million tons of plastic are produced globally every year, with only 7% recycled, leaving the majority of waste to accumulate in the environment and pose a serious threat in the form of microplastics. All ecosystems, particularly freshwater ecosystems, experience microplastic accumulation and are also prone to degrading processes. Degraded microplastics accumulate in many aquatic systems, contaminate them, and enter the food chain as a result of the excessive discharge of plastic trash annually from the domestic to the industrial sector. Due to their pervasiveness, these tiny plastic particles are constantly present in freshwater environments, which are essential to human life. In this sense, microplastic pollution is seen as a worldwide problem that has a detrimental impact on every component of the freshwater environment. Microplastics act as carriers for various toxic components such as additives and other hazardous substances from industrial and urbanized areas. These microplastic-contaminated effluents are ultimately transferred into water systems and directly ingested by organisms associated with a particular ecosystem. The microplastics components also pose an indirect threat to aquatic ecosystems by adsorbing surrounding water pollutants. This review mainly focuses on the sources of microplastics, the ecotoxicity of microplastics and the impact microplastics have on aquatic and marine life, management, and bioremediation of microplastics. Policies and strategies adopted by the Government to combat microplastic pollution are also discussed in this review.