## 4 Discussion
Table 4 displays the percentage share of analyzed cases for which the THQ parameter exceeded the value of 1. In their research, [PERSON] et al. used 5- and 15-min brewing times and a different tea weight to water volume ratio of 1:100. In our study, it is 2:100. Therefore, the THQ parameter calculated based on the results of [PERSON] et al. was also determined for the case assuming the ratio of tea weight to the water volume of 2:100 (Table 4). For these cases, it was considered that the concentration of fluoride in the infusion would increase twice in relation to the ratio of tea weight to the water volume of 1:100. The analysis of the data contained in Table 4 allows us to conclude that tea infusions in bags, green and black, are characterized by the highest rate of exceeding the threshold THQ value. Infusions of the same teas but in the leaf form had the lowest index, so consuming infusions prepared from tea in bags is associated with a much higher risk of adverse health effects. Unfortunately, this form of tea is sold most often in Poland; in 2021, 85% of tea was sold in this form, 11% in leaf form, and 4% in the granulated form [56]. It should also be noted that green tea, traditionally produced from young leaves and buds, should be low in fluoride. The presented results and those of [PERSON] et al. [39] suggest, however, that some green teas sold in Poland, especially in the form of bags, are produced from other parts of the _Camellia sinensis_ plant, such as older leaves or stems. This may cause an increased health risk associated with fluoride intake, especially for people who believe that green tea is healthier than black tea and, therefore, may consume more significant amounts of its infusions. Kombucha is produced by fermenting tea with added sugar using SCOBY (symbiotic culture of bacteria and yeast). It was demonstrated that kombucha is a major dietary source of fluoride and that the type of tea used significantly affects its chemical composition. Therefore, making the beverage with white or red tea is recommended due to the lowest fluoride content and ensuring food safety [57]. Another tea product is Matcha, powdered green tea (Camellia sinensis) of the Tencha type. [PERSON] et al. [58] showed that matcha infusions have a high fluorine content regardless of the water temperature or harvest time--about 4 mg/L. Matcha tea can therefore be the main source of fluoride in the human diet, which is why it is important to control the amount of matcha in the daily diet. Tea quality control becomes essential to protect humans from excessive fluoride intake from infusions. Excessive fluoride intake with tea infusion, especially in regions with high fluoride concentrations in drinking water, increases the risk of fluorosis. In Poland, drinking water is not fluoridated, and in most of the country, the fluoride concentration is below 0.3 mg/L, and only in a few localities, it exceeds 2 mg/L [59]. Some regions of Poland are characterized by a natural, increased amount of fluoride in the environment, including drinking water. One of them is Malbork and its surroundings. [PERSON] et al. [60] conducted research to assess fluorosis and caries in the population of Malbork children who, in the years corresponding to the period of incisor mineralization, lived in areas with an average fluoride content in drinking water of 2.25 mg/L. The authors found fluorosis in 84.54% of the examined children aged 13-16. [PERSON] et al. [59] conducted research aimed at determining the level of fluoride in tap waters in various towns in northern and central Poland and examining whether there is a correlation between the content of fluoride in water and the concentration of fluoride in the urine of residents. These studies found no significant correlation between fluoride concentrations in drinking water and human urine. This suggests that elevated levels of fluoride in the urine may be caused by more than just fluoride from the water. Diet is another source of fluoride. [PERSON] et al.