Abstract
BACKGROUND: Microplastics and nanoplastics, ubiquitous in ecosystems, pose significant ecological and health risks. At the biological level, plastics impact multiple trophic levels. While numerous studies have confirmed this phenomenon, conflicting conclusions may arise due to variations in particle types or target organisms, underscoring the necessity for additional exploration. AIM OF REVIEW: This review explores their sources, environmental pathways, and interactions with other pollutants, emphasizing the multifaceted threats they present to biodiversity and ecosystem stability. This paper delves deeply into bridging knowledge gaps by presenting emerging evidence of differential effects across trophic levels and organism groups, and highlighting the role of vectors for other environmental pollutants and modifying factors of photodegradation and weathering, offering a nuanced analysis of their synergistic effects on gut microbiota and intestinal health. KEY SCIENTIFIC CONCEPTS OF REVIEW: Emerging insights into photodegraded plastics, synergistic toxicities, and their role as pollutant vectors call for immediate action. Ultraviolet radiation accelerates the aging of plastics, enhancing their adsorption capacity for pollutants like heavy metals and persistent organic pollutants, thereby amplifying their toxicity. For instance, aged plastic particles in zebrafish have been shown to induce severe intestinal damage and disrupt microbial balance. Similarly, combined exposures of plastics and antibiotics alter the gut microbiota in organisms, affecting phyla such as Firmicutes and Bacteroidetes. In soil ecosystems, aged plastics elevate heavy metal accumulation in earthworms, intensifying intestinal injury. Our analysis reveals a remarkable ability of the gut microbiota in certain terrestrial organisms to break down microplastics, while specific chemicals help alleviate the intestinal toxicity caused by microplastics and nanoplastics. These findings provide fresh perspectives for future mitigation tactics, underscoring the need for sustainable plastic alternatives, improved waste management strategies, and further research to mitigate the long-term impacts of microplastics and nanoplastics on ecosystem health and functionality.