This book covers environmental chemistry, including toxicological chemistry. It discusses the integration of toxicological chemistry along with environmental chemistry, organized on the five spheres of Earth's environment. The book includes discussion of each of the spheres of the environment based upon (1) the nature of the sphere, (2) pollution of the sphere, and (3) sustainability of the sphere. Emphasizing sustainability, it focuses on the relation of environmental/toxicological chemistry to the practice of industrial hygiene.