Fluorides are given out during refining of materials. Fluorides cause flourosis. It is a disease which is defined by mottling of teeth, abnormal bones that "are liable to fracture because flourine replaces Ca2+ and" makes the bones brittle. Fluoride pollution is a serious problem in many districts of Rajasthan, where excess of fluoride in water adversely affects the health of man. Many villagers have aged prematurely or became hunch backs.