Microplastics are often viewed as pollutants in their own right, but their environmental impact may extend far beyond the plastic particles themselves. A new review shows that microplastics can act as mobile "pollutant shuttles," carrying toxic chemicals, microorganisms and antibiotic resistance genes through water, soil, food webs and even across environmental boundaries.
Published in Energy & Environment Nexus, the review by researchers from Jiangxi Agricultural University provides a comprehensive analysis of the dual role of microplastics as vectors for both chemical and biological contaminants. The authors also introduce a three-tiered framework for understanding the physical, chemical and biological factors that determine when these transport effects may become major ecological risks.
"Microplastics should not be considered isolated particles in the environment," said corresponding author Jingliang Shi. "They can interact with chemicals and microorganisms, transport them between environmental compartments and, under certain conditions, amplify their ecological effects. Understanding when these processes become dominant is essential for realistic risk assessment."
One major concern is the "Trojan horse effect." Microplastics can adsorb persistent organic pollutants, heavy metals and other contaminants on their surfaces. After being ingested by organisms, these pollutants may be released in the digestive system, increasing their bioavailability. The review highlights an important size dependence: conventional microplastics generally deliver contaminants through the gastrointestinal tract, while nanoplastics smaller than about 1 micrometer may cross biological membranes and distribute associated pollutants to internal organs.
The biological dimension may be equally important. Microplastic surfaces can develop microbial communities known as the plastisphere, which can provide protected habitats for pathogens and antibiotic resistance genes. Within these biofilms, close contact between microorganisms may promote horizontal gene transfer, potentially accelerating the spread of antimicrobial resistance.
The review further shows that chemical and biological effects may reinforce each other. Pollutants attached to microplastics can create selective pressure on microbial communities, while biofilms can alter plastic surface properties and increase subsequent pollutant adsorption. This bidirectional positive feedback may intensify both contaminant accumulation and the transfer of antibiotic resistance genes.
To move beyond simple descriptions of microplastic pollution, the authors propose a three-tiered regulatory framework involving physical, chemical and biological drivers. Particle size, shape and aging influence transport and surface reactivity. Polymer chemistry and environmental conditions control adsorption and desorption. Biological processes, including biofilm formation, ingestion and food-web transfer, determine how contaminants ultimately reach organisms.
The researchers also identify conditions under which combined chemical and biological vector effects may become particularly important. These include strong microbial selective pressure at relatively low contaminant concentrations, high extracellular polymeric substance content in biofilms, highly aged microplastics with oxygen-rich surface groups, and prolonged exposure exceeding 30 days.
The authors emphasize that future research should shift toward quantitative, environmentally realistic studies that can define ecological risk thresholds. Current toxicity experiments often rely on short-term, high-concentration exposures that poorly represent chronic environmental conditions. The review calls for long-term observations, improved exposure models, targeted removal of high-risk aged microplastics and more unified approaches to global microplastic governance.
Ultimately, the study reframes microplastics not simply as contaminants, but as dynamic platforms capable of connecting chemical pollution, microbial ecology and antimicrobial resistance across ecosystems.
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Journal reference: He Z, Zhu X, Pei R, Shi J, Zhang Q. 2026. Microplastics as pollutant shuttles: unraveling the drivers of chemical and biological vector effects. Energy & Environment Nexus 2: e023 doi: 10.48130/een-0026-0017
https://www.maxapress.com/article/doi/10.48130/een-0026-0017
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About Energy & Environment Nexus :
Energy & Environment Nexus (e-ISSN 3070-0582) is an open-access journal publishing high-quality research on the interplay between energy systems and environmental sustainability, including renewable energy, carbon mitigation, and green technologies.
