Fluoride levels in various black tea commodities: measurement and safety evaluation.

In order to determine the fluoride content of various products of black tea and to make safety evaluations, 37 commodities in the different manufactured forms of tea were assessed by means of ion-selective electrode and spectrophotometric methods. The results showed wide differences in fluoride levels. The fluoride content was found 0.95-1.41 mg/L in black tea sticks, 0.70-2.44 mg/L in black tea granules and 1.15-6.01 mg/L in black tea bags. Of the products tested, the fluoride content was greatest in black tea bags, presumably because black tea bags are made of low cost, and older tea leaves. According to WHO's recommendation, fluoride exposure threshold for children is 2mg of daily intake and for adult, 4 mg. Assuming that children's daily intake of black tea was 800 ml and adult's 1500 ml, 56% of black tea bags should be considered unsafe for children and 44% should be considered unsafe for adults. At average rates of consumption, 24% of the black tea bags could result in an increasing risk of osteofluorosis and fractures (WHO). In the areas with drinking water fluoridation or other fluoride supplements, excessive fluoride exposure can become even more severe with even lower intake tea made from black tea bags. The potential hazards of fluoride arising from consumption of black tea has not aroused due public attention. Therefore, it is necessary to establish reliable fluoride surveillance in food and beverage commodities and conduct additional epidemiological research on fluoride hazards. In addition, it is urgent that governmental and international agencies adopt safe standards of fluoride content in tea commodities.