Natural geologic environments in India affect human health in a variety of ways through interactions between geochemical, hydrologic, and biologic processes and human activities. Numerous national-scale cases serve as examples, fluorosis in Rajasthan and arsenicism diseases in West Bengal regions. The areas of fluorine-related endemic ailments, which occur in many parts of Indian states that include Tamil Nadu, Andhra Pradesh and Karnataka, have a distribution that tends to match that of regions with high-fluorine rocks and aquifers. Environmental factors such as climate, along with the human activities and cultural customs, can also enhance health impacts in areas with high natural background concentrations of hazardous geochemical compounds. The serious arsenicism in parts of West Bengal state is related not only to the high arsenic content (as high as 28 µg/g) in recent Ganges alluvium deposits but also to the semi-arid conditions on the desert in the sulphide mining Rajasthan of the western part of India.