Dental fluorosis and the use of a high fluoride-containing trona tenderizer (magadi)

It has recently been suggested that magadi, a high-fluoride trona, which is added in cooking to tenderize certain vegetables and beans in two villages in Tanzania, significantly contributed to the prevalence and severity of dental fluorosis. This report aims to substantiate the significance of magadi as a determinant of dental fluorosis. Eighteen villages in four geographical areas (districts) with water supplies containing 0.2 to 0.8 mg/L of fluoride were selected. All schoolchildren aged 12 to 17 years (n = 1566) who had been born and raised in these villages were examined for dental fluorosis according to the Thylstrup-Fejerskov Index. Dietary history was recorded. The fluoride content of magadi samples was determined and the urinary fluoride excretion of pre-schoolchildren was assessed. The prevalence of dental fluorosis in nine coastal villages where tea and seafish were regularly consumed ranged from 7% to 46%. Severe (pitting) dental fluorosis was rarely seen. The low fluorosis levels observed in non-magadi consuming communities in coastal villages indicate that a fluoride content of up to 0.8 mg/L in drinking water is acceptable under the prevailing conditions of temperature and diet. In contrast, the prevalence of dental fluorosis in nine villages located inland at 1500 m altitude, where fluoride-containing magadi was consumed, ranged from 53% to 100%, and severe (pitting) fluorosis was highly prevalent, ranging from 18% to 97%. The village with the highest fluoride content in the magadi samples collected showed the highest level of fluorosis. The urinary fluoride excretion of pre-schoolchildren from different villages corresponded with the level of fluorosis and the fluoride content in the magadi samples of the respective villages. Data on dental fluorosis from the magadi-consuming communities provide strong evidence that consumption of magadi was the major determinant of the observed high prevalence and severity of fluorosis in inland villages at 1500 m altitude.