From Rivers to Humans: Evolving Policies and Health Risks of Microplastics Pollution in Freshwater Fish

Abstract

Microplastics (MPs; <5 mm) and nanoplastics (NPs; <1 µm) have emerged as widespread contaminants in freshwater ecosystems, originating from agricultural activities, urban runoff, wastewater discharge, and atmospheric deposition. Rivers play a dual role by transporting these particles across landscapes while also acting as zones of accumulation. Freshwater fish, which form an important component of human diets, are continuously exposed to microplastics through feeding interactions and gill uptake. Most studies report higher concentrations in the gastrointestinal tract, while evidence of their presence in edible muscle tissue remains variable and influenced by analytical methods. This review brings together global and India-specific research published between 2017 and 2025, examining occurrence patterns, toxicological effects in fish, human exposure pathways, analytical challenges, and current policy responses. Recent biomonitoring studies reporting microplastics in human blood, placenta, and arterial tissues highlight the potential for internal exposure and underscore growing public health concerns. Advances in analytical tools such as µ-FTIR, Raman spectroscopy, and thermal analysis have improved detection, although differences in methodology continue to limit comparability across studies. Policy measures in regions such as the European Union and India represent important steps forward, but gaps remain in addressing secondary microplastic sources. Future efforts should focus on standardized monitoring, improved analytical consistency, and stronger integration of scientific evidence into regulatory frameworks to reduce exposure risks and protect both ecosystem and human health.