ENDOCRINE DISRUPTORS AND HORMONAL DYSREGULATION IN AQUATIC VERTEBRATES: MECHANISMS AND ECOTOXICOLOGICAL CONSEQUENCES

Background: Endocrine-disrupting chemicals (EDCs) are emerging aquatic pollutants that interfere with normal hormonal regulation in vertebrates. These contaminants enter aquatic ecosystems mainly through industrial discharge, agricultural runoff, pharmaceutical residues, municipal wastewater effluents, and urban pollution. Objective: This review aims to summarize the major sources, mechanisms, and ecotoxicological consequences of EDC exposure in aquatic vertebrates, particularly fish and amphibians. Methods: This narrative review synthesizes current literature on endocrine disruption in aquatic vertebrates, with emphasis on contaminant classes, hormonal pathways, biological effects, biomarkers, adverse outcome pathways, and emerging molecular and computational tools used for endocrine toxicity assessment. Discussion: Evidence indicates that EDC exposure can cause reproductive dysfunction, feminization, intersex conditions, thyroid disruption, developmental abnormalities, altered behaviour, and reduced population sustainability. Amphibians are especially vulnerable because their metamorphosis is strongly dependent on thyroid hormone regulation. Key mechanisms include hormone receptor interference, altered steroidogenesis, oxidative stress, mitochondrial dysfunction, epigenetic modifications, and disruption of gene expression. Recent advances in molecular tools, adverse outcome pathway frameworks, zebrafish models, and artificial intelligence-based prediction systems have improved the detection and assessment of endocrine toxicity. Conclusion: EDCs pose a significant threat to aquatic vertebrates by disrupting reproductive, developmental, thyroid, behavioural, and ecological processes. Their long-term effects may contribute to biodiversity loss, population decline, and ecosystem instability. Improved environmental monitoring, wastewater treatment, regulatory control, and advanced toxicity assessment tools are essential to reduce the ecological risks associated with endocrine-disrupting pollutants. Keywords: Endocrine-disrupting chemicals; aquatic vertebrates; hormonal dysregulation; ecotoxicological effects; endocrine toxicity mechanisms; fish; amphibians.