The Toxicology of Radioactive Substances, Volume 4: Thorium-232 and Uranium-238 deals with the toxic properties of two radioactive elements, thorium-232 and uranium-238, as well as their soluble and insoluble compounds. Emphasis is placed on their biological effects and the late sequelae of their administration, especially in the case of insoluble compounds. Some of the results of laboratory studies on the acute and chronic effects of the very poorly soluble uranium compound U3O8 are presented. This volume is comprised of 12 chapters and opens with an overview of certain aspects of the toxicology of insoluble compounds of thorium-232 and uranium-238, followed by a discussion on the comparative toxicity of soluble and insoluble compounds of thorium-232. Subsequent chapters explore the absorption, distribution, and excretion of certain soluble compounds of natural thorium; the behavior of thorium dioxide in rats after intratracheal and intraperitoneal administration; the effect of thorium dioxide on the peripheral blood of rats; and photometric determination of low amounts of thorium in biological materials. Changes in the peripheral blood following chronic and acute poisoning with U308 are also considered. This book will be of interest to chemists and toxicologists.