Adsorption of Emerging Contaminants on Microplastics in the Environment: A Systematic Review

Emerging contaminants such as synthetic organic compounds, personal care products, heavy metals, dyes, pharmaceuticals, natural organic matter, and other compounds can adsorb onto microplastic (MP) surfaces. These microplastics and microplastic-bound emerging contaminants have become a global concern, as they may pose significant risks to human health, aquatic ecosystems, and environmental sustainability. The partitioning of emerging contaminants between microplastics and the aquatic environment and their fate and transport in the aqueous environment are influenced by different environmental conditions and physicochemical characteristics. Polymer properties, such as surface area and aging, play critical roles in the fate and transport of MPs and emerging contaminants. Emerging contaminants and MPs interact primarily through van der Waals forces, electrostatic interactions, hydrophobic partitioning, and pore-filling mechanisms. Further, biofilm formation on MPs significantly enhances contaminant adsorption. MPs can act as carriers for toxic contaminants, leading to bioaccumulation and potential health risks, including reproductive and digestive disorders as well as antibiotic resistance. We finally recommend several future research directions, particularly in understanding the long-term environmental fate of contaminant-bound MPs, their bioaccumulation in organisms, and the synergistic effects of co-contamination.