Various Other Sources of Exposure

There are a number of other ways in which exposure to radioactive substances can occur. These include their use in radio luminescent paints, as coloring agents in glass, ceramics, and dental prostheses, the use of various radionuclides in smoke detectors, power generators, welding electrodes, and other commercial and industrial devices, and as tracers and radiation sources in the biomedical sciences. Finally, transportation of radioactive substances must be considered. In some publications, products—such as drinking water, construction materials, fuels, tobacco, and phosphate fertilizers that contain natural radioactivity—are included among the consumer products in which radionuclides are used. However, the radioactivity in these materials is of natural origin and is inadvertently present in products that find their way to the marketplace. This chapter discusses the products, such as ceramic glazes and smoke detectors, in which radioactive substances are deliberately used to achieve a desired objective that may or may not be related directly to the radioactive properties of the substance. Before proceeding to a discussion of these and other uses of radioactive materials, the special case of radium is reviewed because of the unique place this element occupies in the history of radioactivity and its relationship to luminous-dial painting, which was the first use of a radioactive substance in manufactured products.