Fluoride distribution, contamination, toxicological effects and remedial measures: a review

Fluoride is an essential element required in low concentration in the human diet, as it helps in the prevention of dental caries and strengthens the bones. However, it adversely affects human health when ingested in high doses (> 1.5 mg L −1 ) and becomes the reason for several serious diseases such as dental fluorosis and skeletal fluorosis. Therefore, it is necessary to take the adequate amount of fluoride through different sources to prevent various diseases. Fluoride contamination mostly occurs due to anthropogenic activities and geogenic sources. The distribution of fluoride is very wide and present in the atmosphere, water, and soil. Human beings are exposed to fluoride through drinking water (0.2–42.0 mg/L) and plants (0.77–29.5 μg/g). Therefore, the current status and brief knowledge about the geochemistry of fluoride is very crucial to mitigate this problem. More than 400 articles were reviewed for the preparation of the manuscript to provide an understanding of the occurrence, health effects and different techniques and their mechanism to remove fluoride from water. Various studies reported in the literature confirmed the high level of fluoride in groundwater. The main objective of the present paper is to highlight the different resources of fluoride, its contamination and its toxic effect on human beings and plants. Article reviewed several defluoridation techniques which can be adopted to remove the fluoride from drinking water including membrane technology, coagulation, Nalgonda, and ion exchange. Proper treatment of contaminated water using advanced techniques and adequate supply of water may help people to live healthy particularly in fluoride-affected areas.