Transport of micro- and nanoplastics in the environment: Trojan-Horse effect for organic contaminants

Micro- and nanoplastics (MNPs) are emerging pollutants of global concern. Because of their longevity, low density, and small size, MNPs can be transported over long distances by ocean currents, river flows, and wind, resulting in worldwide distribution. In addition, MNPs have a high affinity toward organic contaminants (OCs), including endogenetic OCs known as additives or plastic monomers and exogenetic OCs that are ubiquitous in the environment. Therefore, the transport of MNPs in the environment is accompanied by the immigration of OCs via sorption/desorption, which is designated as the “Trojan-Horse effect” of MNPs in this review. The Trojan-Horse effect significantly changes the potential health risks of MNPs via altering the environmental fate and the bioavailability of OCs for living organisms. Although many investigations have been carried out to understand such effect on the accumulation of OCs by organisms, however, most of which have been limited to lab-scale marine environments with distinctly various results under the individual circumstance. Therefore, long-term studies under field environment conditions are urgently needed. In addition, multimedium investigations, i.e., water-soil-plant systems in terrestrial environments, are also critical supplementary for a comprehensive understanding of the Trojan-Horse effect of MNPs in the environment.