This book provides an in-depth exploration of arsenic exposure, one of the most pressing global environmental and health challenges. It integrates geological, chemical, biological, and medical perspectives to examine how arsenic contamination in soil and water leads to cellular toxicity and long-term health risks. The chapters highlight natural and anthropogenic sources of arsenic, its pathways into the environment, and the mechanisms by which it disrupts cellular processes and promotes tumorigenesis. Special attention is given to diagnostic biomarkers such as urinary arsenic, hair, and nail samples, along with dermatological lesions that serve as reliable indicators of chronic exposure. The book further reviews therapeutic interventions, including chelation therapy, antioxidant support, and nutritional strategies, while also emphasizing preventive measures and public health policies. Case studies from different regions provide real-world insights into arsenic exposure and its socio-economic impacts. The discussion of advanced detection technologies and future directions in arsenic research underscores the urgent need for innovative solutions. Overall, this volume serves as a vital reference for researchers, medical professionals, policymakers, and environmental scientists concerned with mitigating arsenic-related risks to human health and ecosystems.