ABSTRACT
This chapter summarizes the known problems of disease in livestock and humans caused by physical and chemical agents in the natural environment in Australia and New Zealand. It focuses on the nature of potential or established causal factors, the geographic distribution of those factors, and their associated diseases. An excess of nitrate, fluoride, or arsenic can cause disease in livestock. Within many different parts of Australia and New Zealand, livestock suffer mineral deficiency diseases which reflect the soil type and, in turn, the composition of the host rock and the products of its weathering. Natural radioactivity is derived from cosmic radiation, which doesn't vary much over the earth's surface, and radioactive minerals, which can vary from place to place, depending on the geology. Radiation is in the form of electromagnetic radiation alone when it is derived from a heat source, such as the sun and particles and electromagnetic radiation when it is derived from radioactive decay.
