Fluoride content in various types of tea used by tea stalls in Salem district - An in vitro cross sectional study

Tea leaves are natural rich source of fluoride and are known as fluorine absorbants. It is consumed on large scale in India and thus needs to be monitored for its daily fluoride consumption by customers. Tea manufacturers should mention fluoride concentrations on the packages to avoid overdose through unknown consumption by consumers.

To detect the levels of fluoride in tea at different periods of boiling and to compare the fluoride levels in various brands of tea at different periods of boiling.

A survey was conducted in 25 tea stalls of Salem on the type of tea and time of boiling black tea. The five most common brands of tea will bought for the study. The stainless-steel vessel will be used in the methodology for boiling tea. Mettur water will be used for the preparation of black tea and 1 g of tea leaves to 100 ml of hot (~95°C) deionized water (1% w/v tea infusion) and allowed the mixture to stand for 5 min in a glass beaker. After 5 min, the infusions were filtered and again left standing until they are cooled to room temperature. All fluoride measurements will be completed within 4 h of the preparation of the infusion. About 2 min and 4 min boiling will be followed. The fluoride present in each brand of tea will be calculated from black tea prepared using 2-(parasulfophenylazo)-1,8-dihydroxy-3,6-naphthalene-disulfonate (SPADNS) calorimetric method.

The distribution of mean score of fluoride level in tea powders available in tea shops of Salem when boiled in distilled water was (559.00 ± 112.12). The mean score of fluoride level in tea powders available in tea shops of Salem boiled in Mettur water was (689.05 ± 116.34). To test the significance of difference between the average fluoride in tea powders available in tea shops of Salem when boiled in distilled water and Mettur water, the independent t-test was used. the P value is <0.05, and hence, it is found that there is significant difference between the average fluoride in tea powders available in tea shops of Salem boiled in distilled water and Mettur water.

Thus, the study showed tea consists of significant amount of fluoride concentration that is consumed on daily basis. The study also evaluated fluoride concentration in tea preparations using different water. The study shows necessity for regulations of mentioning fluoride concentration on tea packs.