Micro- and nanoplastics as transport vectors for organic contaminants in the environment: A critical review

The impact of micro- and nanosized plastic particles on the mobility of organic contaminants in the environment is a topic of ongoing scientific debate. Their extensive surface area and capacity to interact with organic contaminants have led to frequent concerns that micro- and nanoplastics significantly enhance their mobility and facilitate contaminant uptake by marine biota. For terrestrial systems, this hypothesis has been adopted, raising concerns that plastic particles could facilitate the transport of contaminants into deeper soil layers, thereby posing a threat to groundwater resources, especially in agricultural soils. These soils receive substantial plastic input through various sources, such as organic soil amendments, mulch, recycled wastewater, and atmospheric deposition. This review examines the molecular interactions between organic contaminants, including a wide range of non-intentionally added substances and additives, and plastic interfaces. We critically analyze the role of micro- and nanoplastics as vectors for contaminants in both marine environments and agricultural soils. Our analysis suggests that the vector effect of contaminants via micro- and nanoplastics in the marine environment is generally insignificant compared to other exposure routes. Our calculations regarding the mass transfer of common plastic additives indicate that the role of micro- and, particularly, nanoplastics as carriers for the majority of organic contaminants in agricultural soils is limited due to rapid desorption rates. Although micro- and nanoplastics do not considerably contribute to transport phenomena as vectors, it is crucial to recognize that they are significant sources of potentially harmful contaminants. These issues must be addressed in the forthcoming INC-5 plastic treaty.