## 1 Introduction
Fluoride's harmfulness is affected by factors such as dose and exposure time. The human body may be exposed to the toxic effects of fluoride through the presence of this element in food or as a result of contamination of the natural environment with fluoride compounds. The consequence of this may be dental and skeletal fluorosis. In addition, exposure to fluoride among pregnant women has been shown to increase with tea consumption, which is associated with the likely risk of developmental neurotoxicity to their children [12]. Dental fluorosis initially manifests as white patches that darken and the enamel cracks. In the case of bone-forming cells, unfavorable changes occur, causing demineralization of bone tissue. As a result, bone fragility increases, while ligaments become less flexible. Fluorosis is a disease associated with long-term exposure to fluoride, which is too high in the body [13]. The disease is endemic in many countries due to environmental or industrial exposure. It occurs mainly in countries where the level of fluoride in drinking water is very high, especially in developing countries. In addition, dietary calcium and vitamin D deficiency can exacerbate skeletal fluorosis [14]. Nonendemic cases of skeletal fluorosis have been described in the literature. [PERSON] et al. conducted a literature review in 2020 and found 19 cases of skeletal fluorosis [14]. About half of these 19 cases have been attributed, either partially [15; 16] or fully [15; 17; 18; 19; 20], to chronic consumption of large amounts of various types of tea. Estimated daily fluoride intake from tea ranged from 13 to 74 mg throughout >20 years. In the remaining cases, the sources of fluoride were toothpaste and inhalation of fumes containing this element. There are many scientific reports on fluoride content in various tea infusions, simultaneously attempting to assess the health risk, mainly in countries where tea consumption is high [12; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30; 31; 32; 33; 34; 35]. Conclusions from these studies, in most cases, indicate that tea infusion is an important and insufficiently considered source of fluoride exposure, and its consumption, especially in larger quantities, may pose a potential health risk. Of the 16 cited publications, 6 indicate that the risk assessment did not show a significant health risk from the consumption of tea infusions [22; 27; 29; 32; 33; 35]. In addition, [PERSON] and [PERSON] [29] conclude that more significant dental health benefits could be achieved for the UK population if the average adult intake increased to four to five servings per day. However, this conclusion is not supported by their research. [PERSON] et al. [36] reviewed the results of randomized controlled trials on the use of green tea and its effect on the processes of gingivitis, periodontitis, and caries. Green tea has been found to affect gingivitis and periodontitis positively. Based on these results, sufficient evidence supports the use of green tea in preventing and treating periodontal disease. This review shows that there is currently insufficient evidence to recommend using green tea to treat tooth decay. SCHER indicates that topical application of fluoride is most effective in preventing tooth decay. Topical application of fluoride maintains oral fluoride levels and helps prevent caries with reduced systemic availability. The effectiveness of population policies, such as fluoridation of drinking water, milk or salt, in reducing social disparities in oral health remains insufficiently substantiated [10]. The tea infusion is the most popular drink in Poland, accounting for over 40% of all drinks consumed in the winter and 25% in the summer season. The annual consumption of tea per capita in Poland is almost 1 kg, usually finished 2-3 times a day. About 20% of consumers drink tea more often, 4-5 times a day [37]. So far, two works have been published to assess the concentration and daily intake of fluoride from tea and herbal infusions popular in Poland [38; 39].