This book explores the mechanisms through which terrestrial organisms, including plants, animals, and microorganisms, are affected by toxic substances. It covers the biochemical and physiological pathways that lead to toxicity, including cellular damage, immune system suppression, and genetic mutations. The text examines the types of pollutants that most commonly affect terrestrial organisms, such as heavy metals, pesticides, and industrial chemicals. It also delves into the ecological consequences of toxic exposure, including altered species interactions and ecosystem function. The book includes discussions on risk assessment and management strategies for reducing the impact of toxins on terrestrial ecosystems. It is an essential resource for environmental toxicologists, ecologists, and conservation biologists.