Toxicological implications of emerging pollutants on aquatic organisms

Emerging pollutants (EPs), including pharmaceuticals, pesticides, personal care products, microplastics, nanoparticles, and heavy metals, pose significant environmental threats and are increasingly affecting aquatic organisms. This review consolidates recent findings on how EPs enter aquatic systems through industrial discharges, agricultural runoff, wastewater, and landfill leachate, where they persist, bioaccumulate, and exert chronic toxic effects. Evidence indicated that EPs may induce oxidative stress, endocrine disruption, genotoxicity, and immunotoxicity as primary mechanisms of toxicity. In fish, exposure to microplastics, nanoparticles, and pesticides may disrupt antioxidant enzyme activities, impair reproduction, and alter behavior and metabolism. Amphibians may exhibit delayed metamorphosis, endocrine and thyroid dysfunction, and neurotoxicity following exposure to pesticides and bisphenols. At the same time, molluscs exhibit impaired filtration capacity, oxidative DNA damage, and reduced gamete viability upon contact with pharmaceuticals and microplastics. These mechanistic disruptions may collectively lead to reduced growth, reproductive failure, and biodiversity loss, ultimately destabilizing aquatic food webs and ecosystem functionality. The review highlights critical research gaps, particularly concerning mixture toxicity, environmentally relevant concentrations, and chronic low-dose exposure effects. Addressing these gaps through pollutant-specific regulation, advanced wastewater treatment, and sustainable practices is essential to mitigate EPs' impacts. By integrating mechanistic evidence across taxa, this study underscores the urgent need for interdisciplinary approaches to safeguard aquatic biodiversity, ecosystem balance, and public health.