Water is contact with natural deposits of fluoride such as fluorspar, calcium fluoride and Criolite and waters contaminated by effluents from glass and aluminum manufacturing industries are found to contain excess fluoride, in India alone about 30 million people are suffering from fluorosis. Presence of large amounts of fluoride (>1.5mg/L) is associated with dental and skeletal fluorosis and less amount (<1.0mg/L)with dental cavities.
Maximum permissible range for fluoride in drinking water is 1.5mg/L
