Free Fluoride Content in Tea Liquor and Identification of Efficient Low Cost Defluoridating Materials

Abstract

Fluoride is considered as a double edged weapon as in correct dosage it strengthens the enamel to prevent dental caries and in excess causes ugly brown stains of the teeth called dental fluorosis. Drinking water with high fluoride content has been the main reason for development of fluorosis, but food items may also contribute in areas with high concentration of fluoride in soil and water. The purpose of this study was to assess the fluoride content in tea liquor and identify low cost efficient defluoridating materials to remove excess fluoride in drinking water. Fluoride content in tea liquor obtained from eleven brands of low grown tea and six brands of tea available in the market including green tea were determined. The fluoride content was found to increase with increase in brewing time for all types of tea. Market available tea showed higher levels of fluoride in tea liquor compared to low grown tea. Green tea showed the highest level of fluoride in tea liquor (0.19 mg). Detluoridating ability of clay pots, asbestos, granite and ceramic powder was also examined. With clay pots, optimum fluoride concentration that can be tolerated is around 2.5 mg dm' Of the three filtering media namely asbestos, granite and ceramic powder, asbestos showed the highest exchange and breakthrough capacities. Asbestos appears to be the best defluoridating material reported to date.