Microplastics as vectors of environmental contaminants: Interactions in the natural ecosystems

Microplastics (MPs) have recently been recognized as potential pollutants and carriers for pathogens in marine, freshwater, and terrestrial environments. They can carry microbial pathogens, hydrophobic organic compounds, persistent organic pollutants, and heavy metals on the surface of these particles leading to unwanted effects on living organisms. Their harmful effects on aquatic and terrestrial organisms have been well established. This includes damage to cell membranes, tissues, and physiological processes. Further, being highly persistent in natural ecosystems, they can amass in various environments over long periods of time. Their accumulation of MPs substantially depends on plastic usage and its management policies around the world; therefore, a closer look at the potential hazards and build-up of MPs is timely. Also, it is crucial to understand the significance of currently established methods on their removal from the ecosystem including activated sludge treatment, coagulation and flocculation, and removal via membrane bioreactors. Among them, constructed wetlands are considered an environmentally friendly technology with ease in operation and low cost that could efficiently remove MPs from wastewater. This article specifically compiles existing literature on the current understanding of MPs in the environment, their role as environmental carriers, interactions in natural ecosystems, the recent developments in their research, and the way forward.