Abstract

Environmental toxicants, including heavy metals, particulate matter, pesticides, and industrial chemicals, constitute 
a major global health burden due to their ability to trigger oxidative stress and dysregulate innate immune 
responses. These early biological events play essential roles in determining susceptibility, severity, and progression 
of toxicant-induced diseases. Oxidative stress arises when the balance between the production of reactive oxygen 
species and the antioxidant defense system is disrupted, leading to macromolecular damage and altered cellular 
signalling. Simultaneously, innate immunity, which provides the first line of defense against harmful stimuli, 
responds to toxicant exposure through pattern-recognition receptors, inflammasome activation, cytokine release, 
and recruitment of inflammatory cells. The interplay between oxidative stress and innate immune pathways 
represents a critical early mechanism driving tissue injury, inflammatory diseases, metabolic dysfunction, 
carcinogenesis, and long-term systemic toxicity. This review synthesizes current understanding of how oxidative 
signalling, redox-sensitive transcription factors, mitochondrial dysfunction, and lipid peroxidation integrate with 
toll-like receptor activation, macrophage polarization, neutrophil responses, and inflammasome dynamics during the 
initial stages of toxicant exposure. Furthermore, it discusses emerging biomarkers, vulnerable populations, and 
potential therapeutic strategies targeting redox and immune pathways. Understanding these early events is key to 
improving environmental health assessments and designing effective preventive and therapeutic interventions.