Medical Geology is defined as the science dealing with the relationship between geological factors and health problems in humans, animals and plants. The International Medical Geology Association (IMGA) aims to provide a network and a forum to characterize the properties of geological processes and agents, the dispersal of geological material and their effects on human populations. MEDGEO series conferences are held by IMGA once every two years, and the 8th International Conference on Medical Geology is held in Guiyang, China, during August 12–15, 2019. This special issue focuses on the various studies on medical geology. Potential topics include, but not limited to environmental geochemistry and human health, water and human health, soil pollution and remediation, atmosphere pollution and human health. Studies associated with analytical methodology, medical geology in toxicology and epidemiology, medical geology, public health and regulatory sciences are also welcome.