Microplastic pollution has attracted significant attention as an emerging global environmental problem. One of the most important issues with microplastics is the leaching of harmful additives. This review summarizes the recent advances in the understanding of the leaching phenomena in the context of the phase equilibrium between microplastics and water, and the release kinetics. Organic additives, which are widely used in plastic products, have been introduced because they have diverse physicochemical properties and mass fractions in plastics. Many theoretical and empirical models have been utilized in laboratory and field studies. However, the partition or distribution constant between microplastics and water (Kp) and the diffusivity of an additive in microplastics (D) are the two key properties explaining the leaching equilibrium and kinetics of hydrophobic organic additives. Because microplastics in aquatic environments undergo dynamic weathering, leaching of organic additives with high Kp and/or low D cannot be described by a leaching model that only considers microplastic and water phases with a fixed boundary. Surface modifications of microplastics as well as biofilms colonizing microplastic surfaces can alter the leaching equilibrium and kinetics and transform additives. Further studies on the release of hydrophobic organic additives and their transformation products under various conditions are required to extend our understanding of the environmental fate and transport of these additives in aquatic environments.
Bibliographical noteFunding Information:
This research was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government ( MEST ) (No. 2020R1A2C2009244 ) and by the Korea Environment Industry & Technology Institute (KEITI) through the Measurement and Risk Assessment Program for Management of Microplastics Program, funded by the Korea Ministry of Environment (MOE) ( 2020003110005 ). ATND was supported by the Global Korea Scholarship (GKS).
© 2022 Elsevier Ltd
- Environmental fate and transport
- Exposure assessment
- Phase equilibrium
- Plastic additives
ASJC Scopus subject areas
- Health, Toxicology and Mutagenesis