BIONATURE

Pesticides have remained indispensable in modern agriculture, public health and vector control for more than seven decades. While their contribution to food security and disease prevention is undeniable, mounting scientific evidence highlights significant unintended consequences for non-target organisms, ecosystems and human health. This comprehensive review critically examines the major chemical classifications and contemporary usage patterns, followed by in-depth mechanisms involved for their toxic effects. Particular emphasis is placed on shared toxicological pathways—including acetylcholinesterase inhibition, ion channel modulation, oxidative stress induction, mitochondrial dysfunction, endocrine disruption, genotoxicity and immunomodulation—that underpin both acute and chronic health outcomes. Accumulating mechanistic and epidemiological evidence links chronic pesticide exposure to neurodegenerative disorders, carcinogenesis, reproductive dysfunction, endocrine abnormalities and immune dysregulation. Oxidative stress emerges as a central mediator across pesticide classes, contributing to mitochondrial injury, inflammatory activation and apoptotic signaling. Ecotoxicological data further demonstrate profound impacts on avifauna, pollinators, aquatic organisms and soil microbiota, with cascading effects on biodiversity, trophic interactions and ecosystem stability. Despite advances in toxicological science, important research gaps persist, particularly regarding cumulative exposures, endocrine-disrupting thresholds, immunotoxic biomarkers and long-term ecological resilience. Strengthening exposure assessment methodologies, integrating mechanistic toxicology with epidemiology and promoting translational research models are essential for improving risk characterization and public health protection. A structured search was conducted using PubMed, Scopus, Web of Science, and Google Scholar databases. Articles were screened following PRISMA-guided principles, prioritizing systematic reviews, meta-analyses and mechanistic studies. The review critically evaluates historical evolution, classification, toxicological mechanisms, ecological consequences, and human health impacts of pesticides. Particular emphasis is placed on oxidative stress and immunomodulation as convergent mechanistic pathways linking exposure to chronic disease endpoints. Collectively, this review underscores the urgency of balancing agricultural productivity with environmental sustainability and human health preservation in the era of chemical-intensive farming.