This second edition of Environmental Toxicology focuses on the biological and health effects toxicants can induce in living organisms. It discusses metabolism of xenobiotics and several natural defense systems on a cellular level. It analyzes air, soil, and water pollutants including heavy metals, fluoride, VOCs, pesticides, PCBs, dioxins. A new chapter examines endocrine disruption, and the interaction of various chemical agents with DNA leading to cancer. Based on nearly 30 years of teaching environmental toxicology and related courses, the author concludes this text with an introduction to ecological risk assessment and its role in policymaking.