Fluoride and hardness in groundwater of tropical regions - review of recent evidence indicating tissue calcification and calcium phosphate nanoparticle formation in kidney tubules

In many tropical environments, groundwater has high fluoride concentrations in addition to other ions such as Na⁺, Ca²⁺, Mg²⁺ and PO₄^3-. These ions interact with one another and this geochemistry has a direct bearing on the health of the population living in such terrains. In the majority of cases, it is the groundwater that is used for drinking and the input of the above mentioned ions into the body often results in diseases such as dental and skeletal fluorosis, chronic kidney disease, soft and hard tissue calcification. Even though the actual input of the above mentioned ions into the body from drinking water as against diet, maybe low, as reported in some studies, it may be high in people living in tropical terrains where agricultural productivity and nutrition is low and where the consumption of such water is high.