(Nano)plastics in the environment – Sources, fates and effects

There has been a considerable increase on research of the ecological consequences of microplastics released into the environment, but only a handful of works have focused on the nano-sized particles of polymer-based materials. Though their presence has been difficult to adequately ascertain, due to the inherent technical difficulties for isolating and quantifying them, there is an overall consensus that these are not only present in the environment – either directly released or as the result of weathering of larger fragments – but that they also pose a significant threat to the environment and human health, as well. The reduced size of these particulates (< 1 μm) makes them susceptible of ingestion by organisms that are at the base of the food-chain. Moreover, the characteristic high surface area-to-volume ratio of nanoparticles may add to their potential hazardous effects, as other contaminants, such as persistent organic pollutants, could be adsorbed and undergo bioaccumulation and bioamplification phenomena. In this review, we describe the most relevant sources of nanoplastics and offer some insights into their fate once released into the environment. Furthermore, we overview the most prominent effects of these small particulates, while identifying the key challenges scientists currently face in the research of nanoplastics in the environment. Lastly, we give a brief summary of the economic impacts of the pollution caused by plastic litter – a potential key source of nanoplastics – in the oceans, the most common destination of these contaminants.