Severe effects of fluoride on human health can be seen majorly in developing and underdeveloped countries. Among these countries, India is the most affected country, where there are many endemic fluorosis regions. India also has one of the largest fluorite deposits making its groundwater highly contaminated with fluoride. Most of the regions in Asia and Africa are prone to fluorosis based diseases. In Asia, India and China show the majority of cases. Whereas in the African continent, Tanzania is a popular region with a high concentration of fluoride in groundwater where it is a major source of drinking water (Shen et al., 2015; Ali et al., 2016). The Ethiopian rift valley has about 8 million people regularly over-exposed to natural fluoride present in groundwater (Rango et al., 2012; Demelash et al., 2019), while the East African rift valley has about ten times of that amount of people suffering from various fluorosis-related symptoms (Shen et al., 2015). China has approximately 21 million people affected with fluorosis and close to 10 million people suffering from skeletal fluorosis (Li et al., 2020). Fluorosis has affected around 3000 villages in China, most of which are located in arid and semi-arid island basins. Some of the major reasons for fluorosis cases are high fluoride contaminated groundwater, excess coal burning, and brick tea (Kimambo et al., 2019). In Mexico, approximately 20 million people consume water with 1.5 mg/L of fluoride and around 9,00,000 are exposed to even higher (4.5 – 29.6 mg/L) concentration of fluoride (Alarco?n-Herrera et al., 2020). Argentina, in the south American continent, is the most affected where the La Pampa region has fluoride concentrations as high as 25.7 mg/L in ground water (Smedley et al., 2002; Ali et al., 2016; Alcaine et al., 2020). Some of the European regions such as Spain and Norway have reported excess fluoride in their groundwaters, and cases of fluorosis related disorders are not severe (Kimambo et al., 2019). It is said that water fluoridation is practised in some countries in Europe due to the lack of natural fluoride; however, it is considered as controversial public health intervention, and its benefits and harms have been debated since its proposal (Peckham and Awofeso, 2014). In the USA, some regions of Arizona have reported fluoride concentrations > 4 mg/L in deep wells (McMahon et al., 2020).

… We also observed that there was no quantifiable data on groundwater fluoride levels in several areas regions in Russia, Australia, North Korea, etc. …

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