Dietary sources of fluoride in Kenya

Abstract

Analysis offluoride concentrations in Kenyan waters have been carried out using two methods: the fluoride ion selective electrode method and colorimetric method. Water samplesanalysed were taken from boreholes and rivers in Nairobi. Central and Rift Valley Provincesand from the Rift Valley lakes. The high levels of fluoride content present in the Rift Valley lakes and boreholes would pose a threat if the water is used for drinking or for irrigation purposes. However the fluoride concentrations for most potable waters (especially those derived from rivers) is less than the accepted limits of 0.7-1.8 ppm. In order to account for the high incidence of dental fluorosis in Kenya, it is necessary to determine the fluoride intakefrom the total diet. A method suitable for analyzing fluoride content in foods and plant materials is discussed. Preliminary survey of fluoride concentrations for various foods showed: bananas, 4.2ppm; potatoes, 5.6 ppm; cabbages, 0.3ppm; maize 0.7ppm. High levels of fluoride were found in tea leaves in the range 229-340 ppm per kg. which is quite equivalent to 4.4-7.3 ppm F per 125 c.c. cup of tea. Fluoride concentration in coffee beans is quite low – 6.6 ppm per kg. and sodas, beer, cow’s milk have less than 0.01 ppm.