Potential exposure and risk of fluoride intakes from tea drinks produced in Taiwan

Abstract

Tea is the second most commonly consumed drink in the world. Excess fluoride intakes from tea drinks may cause health effects. This work assesses infusible fluoride levels in popular tea sold in Taiwan and evaluates potential exposure factors. Lungjing, pouchong, tienguanyin, oolong, pureh, and black tea specimens were purchased from different counties in Taiwan. Fluoride levels were evaluated in one complete cycle of tea making as well as at different calcium carbonate contents in water, with glass or porcelain teapots, and with/without adding sugar. Oolong tea leaves in each manufacturing step were also analyzed for infusible fluoride. Potential fluoride intakes and risks are estimated based on a national survey. Among six kinds of tea, black tea had the highest fluoride concentrations (8.6472.96 mg/l), whereas pureh (1.9772.70 mg/l) had the lowest levels. Higher percentages of infusible fluoride can be rinsed away from tea leaves curved lengthways compared to those curved end-to-end in the first 2.5 min. The use of glass or porcelain teapots and calcium carbonate content (up to 400 mg/l) in water would not affect infusible fluoride levels, whereas adding sugar increased the infusible fluoride in the first few minutes. In addition, it was found that the critical step during the manufacturing process affecting the percentage of infusible fluoride was ball rolling rather than fermentation. Furthermore, intakes of high amounts (Z5 l/week) of certain tea may result in excess risks of dental or skeletal fluorosis. Tea lovers could be exposed to excess fluoride and may be at risk of fluorosis.

Analysis of Naturally Occurring Fluoride in Commercial Teas and Estimation of Its Daily Intake through Tea Consumption

“…In addition, the fluoride contents in different tea types were different mainly due to variations in the tea leaf maturity rather than the manufacturing process. It has been reported that the infusible fluoride in tea leaves remains almost constant during processing, though the fluoride content increased after rolling or ball rolling, which break down tea leaf cells and tissues (Lung and others ).…”

Black Tea Source, Production, and Consumption: Assessment of Health Risks of Fluoride Intake in New Zealand

“…Similarly, in the Persian Gulf, early studies by Azar et al (1961) observed that habitual and excessive tea drinking may exaggerate the manifestation of fluorosis [31]. Many individuals drink tea rather than water as their primary means of fluid intake [32, 33]. Most people drink tea as an infusion (adding hot or boiling water); however, in some countries, including India, China, and Egypt, tea is drunk as a decoction (tea and water are boiled together) [34].…”

The Benefits and Risks of Consuming Brewed Tea: Beware of Toxic Element Contamination

“…Environmental pollutants such as fluoride and aluminum have been found in tea in part due to the tea plants absorption and deposition and concentration of these compounds in the leaves [3]. The drinking of more than 5 liters of tea per week may result in dental or skeletal fluorosis [4]. Mercury, lead, arsenic, and cadmium as well as other toxic elements have been found in tea leaves as described in the literature [5, 6].…”